From fb1bf1067de979c89ae33589e0466d6ce0dde204 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Sat, 15 Mar 2025 16:43:02 +0100 Subject: rust: alloc: add missing invariant in Vec::set_len() When setting a new length, we have to justify that the set length represents the exact number of elements stored in the vector. Reviewed-by: Benno Lossin Reported-by: Alice Ryhl Closes: https://lore.kernel.org/rust-for-linux/20250311-iov-iter-v1-4-f6c9134ea824@google.com Fixes: 2aac4cd7dae3 ("rust: alloc: implement kernel `Vec` type") Link: https://lore.kernel.org/r/20250315154436.65065-2-dakr@kernel.org Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 3 +++ 1 file changed, 3 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index ae9d072741ce..b01dabfe35aa 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -193,6 +193,9 @@ where #[inline] pub unsafe fn set_len(&mut self, new_len: usize) { debug_assert!(new_len <= self.capacity()); + + // INVARIANT: By the safety requirements of this method `new_len` represents the exact + // number of elements stored within `self`. self.len = new_len; } -- cgit v1.2.3 From 81e1c4dab5d0c508907722f18b028102454d52e6 Mon Sep 17 00:00:00 2001 From: Andrew Ballance Date: Sun, 16 Mar 2025 06:16:42 -0500 Subject: rust: alloc: add Vec::truncate method Implement the equivalent to the std's Vec::truncate on the kernel's Vec type. Link: https://lore.kernel.org/r/20250316111644.154602-2-andrewjballance@gmail.com Signed-off-by: Andrew Ballance [ Rewrote safety comment of set_len(). - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index b01dabfe35aa..8fd941429d7c 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -455,6 +455,41 @@ where Ok(()) } + + /// Shortens the vector, setting the length to `len` and drops the removed values. + /// If `len` is greater than or equal to the current length, this does nothing. + /// + /// This has no effect on the capacity and will not allocate. + /// + /// # Examples + /// + /// ``` + /// let mut v = kernel::kvec![1, 2, 3]?; + /// v.truncate(1); + /// assert_eq!(v.len(), 1); + /// assert_eq!(&v, &[1]); + /// + /// # Ok::<(), Error>(()) + /// ``` + pub fn truncate(&mut self, len: usize) { + if len >= self.len() { + return; + } + + let drop_range = len..self.len(); + + // SAFETY: `drop_range` is a subrange of `[0, len)` by the bounds check above. + let ptr: *mut [T] = unsafe { self.get_unchecked_mut(drop_range) }; + + // SAFETY: By the above bounds check, it is guaranteed that `len < self.capacity()`. + unsafe { self.set_len(len) }; + + // SAFETY: + // - the dropped values are valid `T`s by the type invariant + // - we are allowed to invalidate [`new_len`, `old_len`) because we just changed the + // len, therefore we have exclusive access to [`new_len`, `old_len`) + unsafe { ptr::drop_in_place(ptr) }; + } } impl Vec { -- cgit v1.2.3 From 1679b7159379d11100e4ab7d1de23c8cd7765aa1 Mon Sep 17 00:00:00 2001 From: Andrew Ballance Date: Sun, 16 Mar 2025 06:16:43 -0500 Subject: rust: alloc: add Vec::resize method Implement the equivalent of the rust std's Vec::resize on the kernel's Vec type. Reviewed-by: Benno Lossin Reviewed-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250316111644.154602-3-andrewjballance@gmail.com Signed-off-by: Andrew Ballance [ Use checked_sub(), as suggested by Tamir. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 8fd941429d7c..7ebec5c4a277 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -556,6 +556,33 @@ impl Vec { Ok(v) } + + /// Resizes the [`Vec`] so that `len` is equal to `new_len`. + /// + /// If `new_len` is smaller than `len`, the `Vec` is [`Vec::truncate`]d. + /// If `new_len` is larger, each new slot is filled with clones of `value`. + /// + /// # Examples + /// + /// ``` + /// let mut v = kernel::kvec![1, 2, 3]?; + /// v.resize(1, 42, GFP_KERNEL)?; + /// assert_eq!(&v, &[1]); + /// + /// v.resize(3, 42, GFP_KERNEL)?; + /// assert_eq!(&v, &[1, 42, 42]); + /// + /// # Ok::<(), Error>(()) + /// ``` + pub fn resize(&mut self, new_len: usize, value: T, flags: Flags) -> Result<(), AllocError> { + match new_len.checked_sub(self.len()) { + Some(n) => self.extend_with(n, value, flags), + None => { + self.truncate(new_len); + Ok(()) + } + } + } } impl Drop for Vec -- cgit v1.2.3 From c3152988c047a7b6abb10d4dc5e24fafbabe8b7e Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Tue, 18 Mar 2025 10:52:42 -0400 Subject: rust: alloc: use `spare_capacity_mut` to reduce unsafe Use `spare_capacity_mut` in the implementation of `push` to reduce the use of `unsafe`. Both methods were added in commit 2aac4cd7dae3 ("rust: alloc: implement kernel `Vec` type"). Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250318-vec-push-use-spare-v3-1-68741671d1af@gmail.com Signed-off-by: Tamir Duberstein Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 7ebec5c4a277..6ac8756989e5 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -288,15 +288,10 @@ where pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> { self.reserve(1, flags)?; - // SAFETY: - // - `self.len` is smaller than `self.capacity` and hence, the resulting pointer is - // guaranteed to be part of the same allocated object. - // - `self.len` can not overflow `isize`. - let ptr = unsafe { self.as_mut_ptr().add(self.len) }; + let spare = self.spare_capacity_mut(); - // SAFETY: - // - `ptr` is properly aligned and valid for writes. - unsafe { core::ptr::write(ptr, v) }; + // SAFETY: The call to `reserve` was successful so the spare capacity is at least 1. + unsafe { spare.get_unchecked_mut(0) }.write(v); // SAFETY: We just initialised the first spare entry, so it is safe to increase the length // by 1. We also know that the new length is <= capacity because of the previous call to -- cgit v1.2.3 From 85f8e98dbb0135d2bc1999c6015cd374fe2c69fa Mon Sep 17 00:00:00 2001 From: Alexandre Courbot Date: Sat, 12 Apr 2025 15:29:13 +0900 Subject: rust: alloc: allow coercion from `Box` to `Box` if T implements U This enables the creation of trait objects backed by a Box, similarly to what can be done with the standard library. Suggested-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Signed-off-by: Alexandre Courbot Link: https://lore.kernel.org/r/20250412-box_trait_objs-v3-1-f67ced62d520@nvidia.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kbox.rs | 40 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs index b77d32f3a58b..e043bf2f4687 100644 --- a/rust/kernel/alloc/kbox.rs +++ b/rust/kernel/alloc/kbox.rs @@ -57,12 +57,50 @@ use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption}; /// assert!(KVBox::::new_uninit(GFP_KERNEL).is_ok()); /// ``` /// +/// [`Box`]es can also be used to store trait objects by coercing their type: +/// +/// ``` +/// trait FooTrait {} +/// +/// struct FooStruct; +/// impl FooTrait for FooStruct {} +/// +/// let _ = KBox::new(FooStruct, GFP_KERNEL)? as KBox; +/// # Ok::<(), Error>(()) +/// ``` +/// /// # Invariants /// /// `self.0` is always properly aligned and either points to memory allocated with `A` or, for /// zero-sized types, is a dangling, well aligned pointer. #[repr(transparent)] -pub struct Box(NonNull, PhantomData); +#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, derive(core::marker::CoercePointee))] +pub struct Box<#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, pointee)] T: ?Sized, A: Allocator>( + NonNull, + PhantomData, +); + +// This is to allow coercion from `Box` to `Box` if `T` can be converted to the +// dynamically-sized type (DST) `U`. +#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] +impl core::ops::CoerceUnsized> for Box +where + T: ?Sized + core::marker::Unsize, + U: ?Sized, + A: Allocator, +{ +} + +// This is to allow `Box` to be dispatched on when `Box` can be coerced into `Box`. +#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] +impl core::ops::DispatchFromDyn> for Box +where + T: ?Sized + core::marker::Unsize, + U: ?Sized, + A: Allocator, +{ +} /// Type alias for [`Box`] with a [`Kmalloc`] allocator. /// -- cgit v1.2.3 From 47a17a63f9e23f7e8f39d0965bcda8fee6c322f8 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 16 Apr 2025 13:15:40 -0400 Subject: rust: alloc: add Vec::len() <= Vec::capacity invariant Document the invariant that the vector's length is always less than or equal to its capacity. This is already implied by these other invariants: - `self.len` always represents the exact number of elements stored in the vector. - `self.layout` represents the absolute number of elements that can be stored within the vector without re-allocation. but it doesn't hurt to spell it out. Note that the language references `self.capacity` rather than `self.layout.len` as the latter is zero for a vector of ZSTs. Update a safety comment touched by this patch to correctly reference `realloc` rather than `alloc` and replace "leaves" with "leave" to improve grammar. Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250416-vec-set-len-v4-1-112b222604cd@gmail.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 6ac8756989e5..ca30fad90de5 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -90,6 +90,8 @@ macro_rules! kvec { /// without re-allocation. For ZSTs `self.layout`'s capacity is zero. However, it is legal for the /// backing buffer to be larger than `layout`. /// +/// - `self.len()` is always less than or equal to `self.capacity()`. +/// /// - The `Allocator` type `A` of the vector is the exact same `Allocator` type the backing buffer /// was allocated with (and must be freed with). pub struct Vec { @@ -262,8 +264,8 @@ where /// Returns a slice of `MaybeUninit` for the remaining spare capacity of the vector. pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit] { // SAFETY: - // - `self.len` is smaller than `self.capacity` and hence, the resulting pointer is - // guaranteed to be part of the same allocated object. + // - `self.len` is smaller than `self.capacity` by the type invariant and hence, the + // resulting pointer is guaranteed to be part of the same allocated object. // - `self.len` can not overflow `isize`. let ptr = unsafe { self.as_mut_ptr().add(self.len) } as *mut MaybeUninit; @@ -817,12 +819,13 @@ where unsafe { ptr::copy(ptr, buf.as_ptr(), len) }; ptr = buf.as_ptr(); - // SAFETY: `len` is guaranteed to be smaller than `self.layout.len()`. + // SAFETY: `len` is guaranteed to be smaller than `self.layout.len()` by the type + // invariant. let layout = unsafe { ArrayLayout::::new_unchecked(len) }; - // SAFETY: `buf` points to the start of the backing buffer and `len` is guaranteed to be - // smaller than `cap`. Depending on `alloc` this operation may shrink the buffer or leaves - // it as it is. + // SAFETY: `buf` points to the start of the backing buffer and `len` is guaranteed by + // the type invariant to be smaller than `cap`. Depending on `realloc` this operation + // may shrink the buffer or leave it as it is. ptr = match unsafe { A::realloc(Some(buf.cast()), layout.into(), old_layout.into(), flags) } { -- cgit v1.2.3 From dbb0b840a0cd2ebabbc94a0040e366c7f1a70f7b Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 16 Apr 2025 13:15:41 -0400 Subject: rust: alloc: add `Vec::dec_len` Add `Vec::dec_len` that reduces the length of the receiver. This method is intended to be used from methods that remove elements from `Vec` such as `truncate`, `pop`, `remove`, and others. This method is intentionally not `pub`. Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250416-vec-set-len-v4-2-112b222604cd@gmail.com [ Add #[expect(unused)] to dec_len(). - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index ca30fad90de5..7671867165a0 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -201,6 +201,26 @@ where self.len = new_len; } + /// Decreases `self.len` by `count`. + /// + /// Returns a mutable slice to the elements forgotten by the vector. It is the caller's + /// responsibility to drop these elements if necessary. + /// + /// # Safety + /// + /// - `count` must be less than or equal to `self.len`. + #[expect(unused)] + unsafe fn dec_len(&mut self, count: usize) -> &mut [T] { + debug_assert!(count <= self.len()); + // INVARIANT: We relinquish ownership of the elements within the range `[self.len - count, + // self.len)`, hence the updated value of `set.len` represents the exact number of elements + // stored within `self`. + self.len -= count; + // SAFETY: The memory after `self.len()` is guaranteed to contain `count` initialized + // elements of type `T`. + unsafe { slice::from_raw_parts_mut(self.as_mut_ptr().add(self.len), count) } + } + /// Returns a slice of the entire vector. #[inline] pub fn as_slice(&self) -> &[T] { -- cgit v1.2.3 From 1b04b466c873f62413bf65a05a558f036660aedc Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 16 Apr 2025 13:15:42 -0400 Subject: rust: alloc: refactor `Vec::truncate` using `dec_len` Use `checked_sub` to satisfy the safety requirements of `dec_len` and replace nearly the whole body of `truncate` with a call to `dec_len`. Reviewed-by: Andrew Ballance Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250416-vec-set-len-v4-3-112b222604cd@gmail.com [ Remove #[expect(unused)] from dec_len(). - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 7671867165a0..87dc37ecb94d 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -209,7 +209,6 @@ where /// # Safety /// /// - `count` must be less than or equal to `self.len`. - #[expect(unused)] unsafe fn dec_len(&mut self, count: usize) -> &mut [T] { debug_assert!(count <= self.len()); // INVARIANT: We relinquish ownership of the elements within the range `[self.len - count, @@ -489,23 +488,15 @@ where /// # Ok::<(), Error>(()) /// ``` pub fn truncate(&mut self, len: usize) { - if len >= self.len() { - return; + if let Some(count) = self.len().checked_sub(len) { + // SAFETY: `count` is `self.len() - len` so it is guaranteed to be less than or + // equal to `self.len()`. + let ptr: *mut [T] = unsafe { self.dec_len(count) }; + + // SAFETY: the contract of `dec_len` guarantees that the elements in `ptr` are + // valid elements whose ownership has been transferred to the caller. + unsafe { ptr::drop_in_place(ptr) }; } - - let drop_range = len..self.len(); - - // SAFETY: `drop_range` is a subrange of `[0, len)` by the bounds check above. - let ptr: *mut [T] = unsafe { self.get_unchecked_mut(drop_range) }; - - // SAFETY: By the above bounds check, it is guaranteed that `len < self.capacity()`. - unsafe { self.set_len(len) }; - - // SAFETY: - // - the dropped values are valid `T`s by the type invariant - // - we are allowed to invalidate [`new_len`, `old_len`) because we just changed the - // len, therefore we have exclusive access to [`new_len`, `old_len`) - unsafe { ptr::drop_in_place(ptr) }; } } -- cgit v1.2.3 From 88d5d6a38d5161228fbfe017eb94d777d5e8a0e4 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 16 Apr 2025 13:15:43 -0400 Subject: rust: alloc: replace `Vec::set_len` with `inc_len` Rename `set_len` to `inc_len` and simplify its safety contract. Note that the usage in `CString::try_from_fmt` remains correct as the receiver is known to have `len == 0`. Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250416-vec-set-len-v4-4-112b222604cd@gmail.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 25 ++++++++++++------------- rust/kernel/str.rs | 2 +- rust/kernel/uaccess.rs | 2 +- 3 files changed, 14 insertions(+), 15 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 87dc37ecb94d..5798e2c890a2 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -185,20 +185,19 @@ where self.len } - /// Forcefully sets `self.len` to `new_len`. + /// Increments `self.len` by `additional`. /// /// # Safety /// - /// - `new_len` must be less than or equal to [`Self::capacity`]. - /// - If `new_len` is greater than `self.len`, all elements within the interval - /// [`self.len`,`new_len`) must be initialized. + /// - `additional` must be less than or equal to `self.capacity - self.len`. + /// - All elements within the interval [`self.len`,`self.len + additional`) must be initialized. #[inline] - pub unsafe fn set_len(&mut self, new_len: usize) { - debug_assert!(new_len <= self.capacity()); - - // INVARIANT: By the safety requirements of this method `new_len` represents the exact - // number of elements stored within `self`. - self.len = new_len; + pub unsafe fn inc_len(&mut self, additional: usize) { + // Guaranteed by the type invariant to never underflow. + debug_assert!(additional <= self.capacity() - self.len()); + // INVARIANT: By the safety requirements of this method this represents the exact number of + // elements stored within `self`. + self.len += additional; } /// Decreases `self.len` by `count`. @@ -317,7 +316,7 @@ where // SAFETY: We just initialised the first spare entry, so it is safe to increase the length // by 1. We also know that the new length is <= capacity because of the previous call to // `reserve` above. - unsafe { self.set_len(self.len() + 1) }; + unsafe { self.inc_len(1) }; Ok(()) } @@ -521,7 +520,7 @@ impl Vec { // SAFETY: // - `self.len() + n < self.capacity()` due to the call to reserve above, // - the loop and the line above initialized the next `n` elements. - unsafe { self.set_len(self.len() + n) }; + unsafe { self.inc_len(n) }; Ok(()) } @@ -552,7 +551,7 @@ impl Vec { // the length by the same number. // - `self.len() + other.len() <= self.capacity()` is guaranteed by the preceding `reserve` // call. - unsafe { self.set_len(self.len() + other.len()) }; + unsafe { self.inc_len(other.len()) }; Ok(()) } diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 878111cb77bc..d3b0b00e05fa 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -886,7 +886,7 @@ impl CString { // SAFETY: The number of bytes that can be written to `f` is bounded by `size`, which is // `buf`'s capacity. The contents of the buffer have been initialised by writes to `f`. - unsafe { buf.set_len(f.bytes_written()) }; + unsafe { buf.inc_len(f.bytes_written()) }; // Check that there are no `NUL` bytes before the end. // SAFETY: The buffer is valid for read because `f.bytes_written()` is bounded by `size` diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs index 80a9782b1c6e..e4882f113d79 100644 --- a/rust/kernel/uaccess.rs +++ b/rust/kernel/uaccess.rs @@ -290,7 +290,7 @@ impl UserSliceReader { // SAFETY: Since the call to `read_raw` was successful, so the next `len` bytes of the // vector have been initialized. - unsafe { buf.set_len(buf.len() + len) }; + unsafe { buf.inc_len(len) }; Ok(()) } } -- cgit v1.2.3 From 1116f0c5ff3385658ceb8ae2c5c4cb05bd7836d7 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Thu, 24 Apr 2025 04:28:51 +0900 Subject: rust: hrtimer: Add Ktime temporarily Add Ktime temporarily until hrtimer is refactored to use Instant and Delta types. Reviewed-by: Andreas Hindborg Reviewed-by: Boqun Feng Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-2-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg --- rust/kernel/time/hrtimer.rs | 18 +++++++++++++++++- rust/kernel/time/hrtimer/arc.rs | 2 +- rust/kernel/time/hrtimer/pin.rs | 2 +- rust/kernel/time/hrtimer/pin_mut.rs | 4 ++-- rust/kernel/time/hrtimer/tbox.rs | 2 +- 5 files changed, 22 insertions(+), 6 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index ce53f8579d18..17824aa0c0f3 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -68,10 +68,26 @@ //! `start` operation. use super::ClockId; -use crate::{prelude::*, time::Ktime, types::Opaque}; +use crate::{prelude::*, types::Opaque}; use core::marker::PhantomData; use pin_init::PinInit; +/// A Rust wrapper around a `ktime_t`. +// NOTE: Ktime is going to be removed when hrtimer is converted to Instant/Delta. +#[repr(transparent)] +#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)] +pub struct Ktime { + inner: bindings::ktime_t, +} + +impl Ktime { + /// Returns the number of nanoseconds. + #[inline] + pub fn to_ns(self) -> i64 { + self.inner + } +} + /// A timer backed by a C `struct hrtimer`. /// /// # Invariants diff --git a/rust/kernel/time/hrtimer/arc.rs b/rust/kernel/time/hrtimer/arc.rs index 4a984d85b4a1..ccf1e66e5b2d 100644 --- a/rust/kernel/time/hrtimer/arc.rs +++ b/rust/kernel/time/hrtimer/arc.rs @@ -5,10 +5,10 @@ use super::HrTimer; use super::HrTimerCallback; use super::HrTimerHandle; use super::HrTimerPointer; +use super::Ktime; use super::RawHrTimerCallback; use crate::sync::Arc; use crate::sync::ArcBorrow; -use crate::time::Ktime; /// A handle for an `Arc>` returned by a call to /// [`HrTimerPointer::start`]. diff --git a/rust/kernel/time/hrtimer/pin.rs b/rust/kernel/time/hrtimer/pin.rs index f760db265c7b..293ca9cf058c 100644 --- a/rust/kernel/time/hrtimer/pin.rs +++ b/rust/kernel/time/hrtimer/pin.rs @@ -4,9 +4,9 @@ use super::HasHrTimer; use super::HrTimer; use super::HrTimerCallback; use super::HrTimerHandle; +use super::Ktime; use super::RawHrTimerCallback; use super::UnsafeHrTimerPointer; -use crate::time::Ktime; use core::pin::Pin; /// A handle for a `Pin<&HasHrTimer>`. When the handle exists, the timer might be diff --git a/rust/kernel/time/hrtimer/pin_mut.rs b/rust/kernel/time/hrtimer/pin_mut.rs index 90c0351d62e4..6033572d35ad 100644 --- a/rust/kernel/time/hrtimer/pin_mut.rs +++ b/rust/kernel/time/hrtimer/pin_mut.rs @@ -1,9 +1,9 @@ // SPDX-License-Identifier: GPL-2.0 use super::{ - HasHrTimer, HrTimer, HrTimerCallback, HrTimerHandle, RawHrTimerCallback, UnsafeHrTimerPointer, + HasHrTimer, HrTimer, HrTimerCallback, HrTimerHandle, Ktime, RawHrTimerCallback, + UnsafeHrTimerPointer, }; -use crate::time::Ktime; use core::{marker::PhantomData, pin::Pin, ptr::NonNull}; /// A handle for a `Pin<&mut HasHrTimer>`. When the handle exists, the timer might diff --git a/rust/kernel/time/hrtimer/tbox.rs b/rust/kernel/time/hrtimer/tbox.rs index 2071cae07234..29526a5da203 100644 --- a/rust/kernel/time/hrtimer/tbox.rs +++ b/rust/kernel/time/hrtimer/tbox.rs @@ -5,9 +5,9 @@ use super::HrTimer; use super::HrTimerCallback; use super::HrTimerHandle; use super::HrTimerPointer; +use super::Ktime; use super::RawHrTimerCallback; use crate::prelude::*; -use crate::time::Ktime; use core::ptr::NonNull; /// A handle for a [`Box>`] returned by a call to -- cgit v1.2.3 From 3caad57d29b5f64fa41cff0b12cc5d9144dacb04 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Thu, 24 Apr 2025 04:28:52 +0900 Subject: rust: time: Add PartialEq/Eq/PartialOrd/Ord trait to Ktime Add PartialEq/Eq/PartialOrd/Ord trait to Ktime so two Ktime instances can be compared to determine whether a timeout is met or not. Use the derive implements; we directly touch C's ktime_t rather than using the C's accessors because it is more efficient and we already do in the existing code (Ktime::sub). Reviewed-by: Trevor Gross Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-3-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg --- rust/kernel/time.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index f509cb0eb71e..9d57e8a5552a 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -29,7 +29,7 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies { /// A Rust wrapper around a `ktime_t`. #[repr(transparent)] -#[derive(Copy, Clone)] +#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)] pub struct Ktime { inner: bindings::ktime_t, } -- cgit v1.2.3 From fae0cdc12340ce402a4681dba0f357b05d167d00 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Thu, 24 Apr 2025 04:28:53 +0900 Subject: rust: time: Introduce Delta type Introduce a type representing a span of time. Define our own type because `core::time::Duration` is large and could panic during creation. time::Ktime could be also used for time duration but timestamp and timedelta are different so better to use a new type. i64 is used instead of u64 to represent a span of time; some C drivers uses negative Deltas and i64 is more compatible with Ktime using i64 too (e.g., ktime_[us|ms]_delta() APIs return i64 so we create Delta object without type conversion. i64 is used instead of bindings::ktime_t because when the ktime_t type is used as timestamp, it represents values from 0 to KTIME_MAX, which is different from Delta. as_millis() method isn't used in this patchset. It's planned to be used in Binder driver. Reviewed-by: Andrew Lunn Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-4-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg --- rust/kernel/time.rs | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index 9d57e8a5552a..e00b9a853e6a 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -10,9 +10,15 @@ pub mod hrtimer; +/// The number of nanoseconds per microsecond. +pub const NSEC_PER_USEC: i64 = bindings::NSEC_PER_USEC as i64; + /// The number of nanoseconds per millisecond. pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64; +/// The number of nanoseconds per second. +pub const NSEC_PER_SEC: i64 = bindings::NSEC_PER_SEC as i64; + /// The time unit of Linux kernel. One jiffy equals (1/HZ) second. pub type Jiffies = crate::ffi::c_ulong; @@ -149,3 +155,85 @@ impl ClockId { self as bindings::clockid_t } } + +/// A span of time. +/// +/// This struct represents a span of time, with its value stored as nanoseconds. +/// The value can represent any valid i64 value, including negative, zero, and +/// positive numbers. +#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Debug)] +pub struct Delta { + nanos: i64, +} + +impl Delta { + /// A span of time equal to zero. + pub const ZERO: Self = Self { nanos: 0 }; + + /// Create a new [`Delta`] from a number of microseconds. + /// + /// The `micros` can range from -9_223_372_036_854_775 to 9_223_372_036_854_775. + /// If `micros` is outside this range, `i64::MIN` is used for negative values, + /// and `i64::MAX` is used for positive values due to saturation. + #[inline] + pub const fn from_micros(micros: i64) -> Self { + Self { + nanos: micros.saturating_mul(NSEC_PER_USEC), + } + } + + /// Create a new [`Delta`] from a number of milliseconds. + /// + /// The `millis` can range from -9_223_372_036_854 to 9_223_372_036_854. + /// If `millis` is outside this range, `i64::MIN` is used for negative values, + /// and `i64::MAX` is used for positive values due to saturation. + #[inline] + pub const fn from_millis(millis: i64) -> Self { + Self { + nanos: millis.saturating_mul(NSEC_PER_MSEC), + } + } + + /// Create a new [`Delta`] from a number of seconds. + /// + /// The `secs` can range from -9_223_372_036 to 9_223_372_036. + /// If `secs` is outside this range, `i64::MIN` is used for negative values, + /// and `i64::MAX` is used for positive values due to saturation. + #[inline] + pub const fn from_secs(secs: i64) -> Self { + Self { + nanos: secs.saturating_mul(NSEC_PER_SEC), + } + } + + /// Return `true` if the [`Delta`] spans no time. + #[inline] + pub fn is_zero(self) -> bool { + self.as_nanos() == 0 + } + + /// Return `true` if the [`Delta`] spans a negative amount of time. + #[inline] + pub fn is_negative(self) -> bool { + self.as_nanos() < 0 + } + + /// Return the number of nanoseconds in the [`Delta`]. + #[inline] + pub const fn as_nanos(self) -> i64 { + self.nanos + } + + /// Return the smallest number of microseconds greater than or equal + /// to the value in the [`Delta`]. + #[inline] + pub const fn as_micros_ceil(self) -> i64 { + self.as_nanos().saturating_add(NSEC_PER_USEC - 1) / NSEC_PER_USEC + } + + /// Return the number of milliseconds in the [`Delta`]. + #[inline] + pub const fn as_millis(self) -> i64 { + self.as_nanos() / NSEC_PER_MSEC + } +} -- cgit v1.2.3 From ddc671506458849c1a1c882208bbffed033e770c Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Thu, 24 Apr 2025 04:28:54 +0900 Subject: rust: time: Introduce Instant type Introduce a type representing a specific point in time. We could use the Ktime type but C's ktime_t is used for both timestamp and timedelta. To avoid confusion, introduce a new Instant type for timestamp. Rename Ktime to Instant and modify their methods for timestamp. Implement the subtraction operator for Instant: Delta = Instant A - Instant B Reviewed-by: Boqun Feng Reviewed-by: Gary Guo Reviewed-by: Fiona Behrens Tested-by: Daniel Almeida Reviewed-by: Andreas Hindborg Signed-off-by: FUJITA Tomonori Link: https://lore.kernel.org/r/20250423192857.199712-5-fujita.tomonori@gmail.com Signed-off-by: Andreas Hindborg --- rust/kernel/time.rs | 77 +++++++++++++++++++++++++++-------------------------- 1 file changed, 39 insertions(+), 38 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index e00b9a853e6a..a8089a98da9e 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -5,6 +5,22 @@ //! This module contains the kernel APIs related to time and timers that //! have been ported or wrapped for usage by Rust code in the kernel. //! +//! There are two types in this module: +//! +//! - The [`Instant`] type represents a specific point in time. +//! - The [`Delta`] type represents a span of time. +//! +//! Note that the C side uses `ktime_t` type to represent both. However, timestamp +//! and timedelta are different. To avoid confusion, we use two different types. +//! +//! A [`Instant`] object can be created by calling the [`Instant::now()`] function. +//! It represents a point in time at which the object was created. +//! By calling the [`Instant::elapsed()`] method, a [`Delta`] object representing +//! the elapsed time can be created. The [`Delta`] object can also be created +//! by subtracting two [`Instant`] objects. +//! +//! A [`Delta`] type supports methods to retrieve the duration in various units. +//! //! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h). //! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h). @@ -33,59 +49,44 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies { unsafe { bindings::__msecs_to_jiffies(msecs) } } -/// A Rust wrapper around a `ktime_t`. +/// A specific point in time. +/// +/// # Invariants +/// +/// The `inner` value is in the range from 0 to `KTIME_MAX`. #[repr(transparent)] #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)] -pub struct Ktime { +pub struct Instant { inner: bindings::ktime_t, } -impl Ktime { - /// Create a `Ktime` from a raw `ktime_t`. - #[inline] - pub fn from_raw(inner: bindings::ktime_t) -> Self { - Self { inner } - } - +impl Instant { /// Get the current time using `CLOCK_MONOTONIC`. #[inline] - pub fn ktime_get() -> Self { - // SAFETY: It is always safe to call `ktime_get` outside of NMI context. - Self::from_raw(unsafe { bindings::ktime_get() }) - } - - /// Divide the number of nanoseconds by a compile-time constant. - #[inline] - fn divns_constant(self) -> i64 { - self.to_ns() / DIV - } - - /// Returns the number of nanoseconds. - #[inline] - pub fn to_ns(self) -> i64 { - self.inner + pub fn now() -> Self { + // INVARIANT: The `ktime_get()` function returns a value in the range + // from 0 to `KTIME_MAX`. + Self { + // SAFETY: It is always safe to call `ktime_get()` outside of NMI context. + inner: unsafe { bindings::ktime_get() }, + } } - /// Returns the number of milliseconds. + /// Return the amount of time elapsed since the [`Instant`]. #[inline] - pub fn to_ms(self) -> i64 { - self.divns_constant::() + pub fn elapsed(&self) -> Delta { + Self::now() - *self } } -/// Returns the number of milliseconds between two ktimes. -#[inline] -pub fn ktime_ms_delta(later: Ktime, earlier: Ktime) -> i64 { - (later - earlier).to_ms() -} - -impl core::ops::Sub for Ktime { - type Output = Ktime; +impl core::ops::Sub for Instant { + type Output = Delta; + // By the type invariant, it never overflows. #[inline] - fn sub(self, other: Ktime) -> Ktime { - Self { - inner: self.inner - other.inner, + fn sub(self, other: Instant) -> Delta { + Delta { + nanos: self.inner - other.inner, } } } -- cgit v1.2.3 From 1a4736c3d8394f5e64557a41b4b2b8d6dcd04622 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 23 Apr 2025 09:54:37 -0400 Subject: rust: types: add `ForeignOwnable::PointedTo` Allow implementors to specify the foreign pointer type; this exposes information about the pointed-to type such as its alignment. This requires the trait to be `unsafe` since it is now possible for implementors to break soundness by returning a misaligned pointer. Encoding the pointer type in the trait (and avoiding pointer casts) allows the compiler to check that implementors return the correct pointer type. This is preferable to directly encoding the alignment in the trait using a constant as the compiler would be unable to check it. Acked-by: Danilo Krummrich Signed-off-by: Tamir Duberstein Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250423-rust-xarray-bindings-v19-1-83cdcf11c114@gmail.com Signed-off-by: Andreas Hindborg --- rust/kernel/alloc/kbox.rs | 38 ++++++++++++++++++++------------------ rust/kernel/miscdevice.rs | 10 +++++----- rust/kernel/pci.rs | 2 +- rust/kernel/platform.rs | 2 +- rust/kernel/sync/arc.rs | 21 ++++++++++++--------- rust/kernel/types.rs | 46 +++++++++++++++++++++++++++++++--------------- 6 files changed, 70 insertions(+), 49 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs index b77d32f3a58b..6aa88b01e84d 100644 --- a/rust/kernel/alloc/kbox.rs +++ b/rust/kernel/alloc/kbox.rs @@ -360,68 +360,70 @@ where } } -impl ForeignOwnable for Box +// SAFETY: The `into_foreign` function returns a pointer that is well-aligned. +unsafe impl ForeignOwnable for Box where A: Allocator, { + type PointedTo = T; type Borrowed<'a> = &'a T; type BorrowedMut<'a> = &'a mut T; - fn into_foreign(self) -> *mut crate::ffi::c_void { - Box::into_raw(self).cast() + fn into_foreign(self) -> *mut Self::PointedTo { + Box::into_raw(self) } - unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self { + unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self { // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous // call to `Self::into_foreign`. - unsafe { Box::from_raw(ptr.cast()) } + unsafe { Box::from_raw(ptr) } } - unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> &'a T { + unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> &'a T { // SAFETY: The safety requirements of this method ensure that the object remains alive and // immutable for the duration of 'a. - unsafe { &*ptr.cast() } + unsafe { &*ptr } } - unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> &'a mut T { - let ptr = ptr.cast(); + unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> &'a mut T { // SAFETY: The safety requirements of this method ensure that the pointer is valid and that // nothing else will access the value for the duration of 'a. unsafe { &mut *ptr } } } -impl ForeignOwnable for Pin> +// SAFETY: The `into_foreign` function returns a pointer that is well-aligned. +unsafe impl ForeignOwnable for Pin> where A: Allocator, { + type PointedTo = T; type Borrowed<'a> = Pin<&'a T>; type BorrowedMut<'a> = Pin<&'a mut T>; - fn into_foreign(self) -> *mut crate::ffi::c_void { + fn into_foreign(self) -> *mut Self::PointedTo { // SAFETY: We are still treating the box as pinned. - Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }).cast() + Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }) } - unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self { + unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self { // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous // call to `Self::into_foreign`. - unsafe { Pin::new_unchecked(Box::from_raw(ptr.cast())) } + unsafe { Pin::new_unchecked(Box::from_raw(ptr)) } } - unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> Pin<&'a T> { + unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> Pin<&'a T> { // SAFETY: The safety requirements for this function ensure that the object is still alive, // so it is safe to dereference the raw pointer. // The safety requirements of `from_foreign` also ensure that the object remains alive for // the lifetime of the returned value. - let r = unsafe { &*ptr.cast() }; + let r = unsafe { &*ptr }; // SAFETY: This pointer originates from a `Pin>`. unsafe { Pin::new_unchecked(r) } } - unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> Pin<&'a mut T> { - let ptr = ptr.cast(); + unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> Pin<&'a mut T> { // SAFETY: The safety requirements for this function ensure that the object is still alive, // so it is safe to dereference the raw pointer. // The safety requirements of `from_foreign` also ensure that the object remains alive for diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index fa9ecc42602a..b4c5f74de23d 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -200,7 +200,7 @@ impl MiscdeviceVTable { // type. // // SAFETY: The open call of a file can access the private data. - unsafe { (*raw_file).private_data = ptr.into_foreign() }; + unsafe { (*raw_file).private_data = ptr.into_foreign().cast() }; 0 } @@ -211,7 +211,7 @@ impl MiscdeviceVTable { /// must be associated with a `MiscDeviceRegistration`. unsafe extern "C" fn release(_inode: *mut bindings::inode, file: *mut bindings::file) -> c_int { // SAFETY: The release call of a file owns the private data. - let private = unsafe { (*file).private_data }; + let private = unsafe { (*file).private_data }.cast(); // SAFETY: The release call of a file owns the private data. let ptr = unsafe { ::from_foreign(private) }; @@ -228,7 +228,7 @@ impl MiscdeviceVTable { /// `file` must be a valid file that is associated with a `MiscDeviceRegistration`. unsafe extern "C" fn ioctl(file: *mut bindings::file, cmd: c_uint, arg: c_ulong) -> c_long { // SAFETY: The ioctl call of a file can access the private data. - let private = unsafe { (*file).private_data }; + let private = unsafe { (*file).private_data }.cast(); // SAFETY: Ioctl calls can borrow the private data of the file. let device = unsafe { ::borrow(private) }; @@ -253,7 +253,7 @@ impl MiscdeviceVTable { arg: c_ulong, ) -> c_long { // SAFETY: The compat ioctl call of a file can access the private data. - let private = unsafe { (*file).private_data }; + let private = unsafe { (*file).private_data }.cast(); // SAFETY: Ioctl calls can borrow the private data of the file. let device = unsafe { ::borrow(private) }; @@ -274,7 +274,7 @@ impl MiscdeviceVTable { /// - `seq_file` must be a valid `struct seq_file` that we can write to. unsafe extern "C" fn show_fdinfo(seq_file: *mut bindings::seq_file, file: *mut bindings::file) { // SAFETY: The release call of a file owns the private data. - let private = unsafe { (*file).private_data }; + let private = unsafe { (*file).private_data }.cast(); // SAFETY: Ioctl calls can borrow the private data of the file. let device = unsafe { ::borrow(private) }; // SAFETY: diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs index c97d6d470b28..3aeb1250c27f 100644 --- a/rust/kernel/pci.rs +++ b/rust/kernel/pci.rs @@ -89,7 +89,7 @@ impl Adapter { extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) { // SAFETY: The PCI bus only ever calls the remove callback with a valid pointer to a // `struct pci_dev`. - let ptr = unsafe { bindings::pci_get_drvdata(pdev) }; + let ptr = unsafe { bindings::pci_get_drvdata(pdev) }.cast(); // SAFETY: `remove_callback` is only ever called after a successful call to // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs index 4917cb34e2fe..fd4a494f30e8 100644 --- a/rust/kernel/platform.rs +++ b/rust/kernel/platform.rs @@ -80,7 +80,7 @@ impl Adapter { extern "C" fn remove_callback(pdev: *mut bindings::platform_device) { // SAFETY: `pdev` is a valid pointer to a `struct platform_device`. - let ptr = unsafe { bindings::platform_get_drvdata(pdev) }; + let ptr = unsafe { bindings::platform_get_drvdata(pdev) }.cast(); // SAFETY: `remove_callback` is only ever called after a successful call to // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 8484c814609a..a42c164e577a 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -140,9 +140,10 @@ pub struct Arc { _p: PhantomData>, } +#[doc(hidden)] #[pin_data] #[repr(C)] -struct ArcInner { +pub struct ArcInner { refcount: Opaque, data: T, } @@ -371,18 +372,20 @@ impl Arc { } } -impl ForeignOwnable for Arc { +// SAFETY: The `into_foreign` function returns a pointer that is well-aligned. +unsafe impl ForeignOwnable for Arc { + type PointedTo = ArcInner; type Borrowed<'a> = ArcBorrow<'a, T>; type BorrowedMut<'a> = Self::Borrowed<'a>; - fn into_foreign(self) -> *mut crate::ffi::c_void { - ManuallyDrop::new(self).ptr.as_ptr().cast() + fn into_foreign(self) -> *mut Self::PointedTo { + ManuallyDrop::new(self).ptr.as_ptr() } - unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self { + unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self { // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous // call to `Self::into_foreign`. - let inner = unsafe { NonNull::new_unchecked(ptr.cast::>()) }; + let inner = unsafe { NonNull::new_unchecked(ptr) }; // SAFETY: By the safety requirement of this function, we know that `ptr` came from // a previous call to `Arc::into_foreign`, which guarantees that `ptr` is valid and @@ -390,17 +393,17 @@ impl ForeignOwnable for Arc { unsafe { Self::from_inner(inner) } } - unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> ArcBorrow<'a, T> { + unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> ArcBorrow<'a, T> { // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous // call to `Self::into_foreign`. - let inner = unsafe { NonNull::new_unchecked(ptr.cast::>()) }; + let inner = unsafe { NonNull::new_unchecked(ptr) }; // SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive // for the lifetime of the returned value. unsafe { ArcBorrow::new(inner) } } - unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> ArcBorrow<'a, T> { + unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> ArcBorrow<'a, T> { // SAFETY: The safety requirements for `borrow_mut` are a superset of the safety // requirements for `borrow`. unsafe { Self::borrow(ptr) } diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index 9d0471afc964..86562e738eac 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -18,7 +18,19 @@ use pin_init::{PinInit, Zeroable}; /// /// This trait is meant to be used in cases when Rust objects are stored in C objects and /// eventually "freed" back to Rust. -pub trait ForeignOwnable: Sized { +/// +/// # Safety +/// +/// Implementers must ensure that [`into_foreign`] returns a pointer which meets the alignment +/// requirements of [`PointedTo`]. +/// +/// [`into_foreign`]: Self::into_foreign +/// [`PointedTo`]: Self::PointedTo +pub unsafe trait ForeignOwnable: Sized { + /// Type used when the value is foreign-owned. In practical terms only defines the alignment of + /// the pointer. + type PointedTo; + /// Type used to immutably borrow a value that is currently foreign-owned. type Borrowed<'a>; @@ -27,16 +39,18 @@ pub trait ForeignOwnable: Sized { /// Converts a Rust-owned object to a foreign-owned one. /// - /// The foreign representation is a pointer to void. There are no guarantees for this pointer. - /// For example, it might be invalid, dangling or pointing to uninitialized memory. Using it in - /// any way except for [`from_foreign`], [`try_from_foreign`], [`borrow`], or [`borrow_mut`] can - /// result in undefined behavior. + /// # Guarantees + /// + /// The return value is guaranteed to be well-aligned, but there are no other guarantees for + /// this pointer. For example, it might be null, dangling, or point to uninitialized memory. + /// Using it in any way except for [`ForeignOwnable::from_foreign`], [`ForeignOwnable::borrow`], + /// [`ForeignOwnable::try_from_foreign`] can result in undefined behavior. /// /// [`from_foreign`]: Self::from_foreign /// [`try_from_foreign`]: Self::try_from_foreign /// [`borrow`]: Self::borrow /// [`borrow_mut`]: Self::borrow_mut - fn into_foreign(self) -> *mut crate::ffi::c_void; + fn into_foreign(self) -> *mut Self::PointedTo; /// Converts a foreign-owned object back to a Rust-owned one. /// @@ -46,7 +60,7 @@ pub trait ForeignOwnable: Sized { /// must not be passed to `from_foreign` more than once. /// /// [`into_foreign`]: Self::into_foreign - unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self; + unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self; /// Tries to convert a foreign-owned object back to a Rust-owned one. /// @@ -58,7 +72,7 @@ pub trait ForeignOwnable: Sized { /// `ptr` must either be null or satisfy the safety requirements for [`from_foreign`]. /// /// [`from_foreign`]: Self::from_foreign - unsafe fn try_from_foreign(ptr: *mut crate::ffi::c_void) -> Option { + unsafe fn try_from_foreign(ptr: *mut Self::PointedTo) -> Option { if ptr.is_null() { None } else { @@ -81,7 +95,7 @@ pub trait ForeignOwnable: Sized { /// /// [`into_foreign`]: Self::into_foreign /// [`from_foreign`]: Self::from_foreign - unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> Self::Borrowed<'a>; + unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> Self::Borrowed<'a>; /// Borrows a foreign-owned object mutably. /// @@ -109,21 +123,23 @@ pub trait ForeignOwnable: Sized { /// [`from_foreign`]: Self::from_foreign /// [`borrow`]: Self::borrow /// [`Arc`]: crate::sync::Arc - unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> Self::BorrowedMut<'a>; + unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> Self::BorrowedMut<'a>; } -impl ForeignOwnable for () { +// SAFETY: The `into_foreign` function returns a pointer that is dangling, but well-aligned. +unsafe impl ForeignOwnable for () { + type PointedTo = (); type Borrowed<'a> = (); type BorrowedMut<'a> = (); - fn into_foreign(self) -> *mut crate::ffi::c_void { + fn into_foreign(self) -> *mut Self::PointedTo { core::ptr::NonNull::dangling().as_ptr() } - unsafe fn from_foreign(_: *mut crate::ffi::c_void) -> Self {} + unsafe fn from_foreign(_: *mut Self::PointedTo) -> Self {} - unsafe fn borrow<'a>(_: *mut crate::ffi::c_void) -> Self::Borrowed<'a> {} - unsafe fn borrow_mut<'a>(_: *mut crate::ffi::c_void) -> Self::BorrowedMut<'a> {} + unsafe fn borrow<'a>(_: *mut Self::PointedTo) -> Self::Borrowed<'a> {} + unsafe fn borrow_mut<'a>(_: *mut Self::PointedTo) -> Self::BorrowedMut<'a> {} } /// Runs a cleanup function/closure when dropped. -- cgit v1.2.3 From 210b81578efbe5c5e7748e50d313e1a90b03df55 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 23 Apr 2025 09:54:38 -0400 Subject: rust: xarray: Add an abstraction for XArray MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit `XArray` is an efficient sparse array of pointers. Add a Rust abstraction for this type. This implementation bounds the element type on `ForeignOwnable` and requires explicit locking for all operations. Future work may leverage RCU to enable lockless operation. Inspired-by: Maíra Canal Inspired-by: Asahi Lina Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250423-rust-xarray-bindings-v19-2-83cdcf11c114@gmail.com Signed-off-by: Andreas Hindborg --- rust/kernel/lib.rs | 1 + rust/kernel/xarray.rs | 275 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 276 insertions(+) create mode 100644 rust/kernel/xarray.rs (limited to 'rust/kernel') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de07aadd1ff5..715fab6b1345 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -88,6 +88,7 @@ pub mod transmute; pub mod types; pub mod uaccess; pub mod workqueue; +pub mod xarray; #[doc(hidden)] pub use bindings; diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs new file mode 100644 index 000000000000..75719e7bb491 --- /dev/null +++ b/rust/kernel/xarray.rs @@ -0,0 +1,275 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! XArray abstraction. +//! +//! C header: [`include/linux/xarray.h`](srctree/include/linux/xarray.h) + +use crate::{ + alloc, bindings, build_assert, + error::{Error, Result}, + types::{ForeignOwnable, NotThreadSafe, Opaque}, +}; +use core::{iter, marker::PhantomData, mem, pin::Pin, ptr::NonNull}; +use pin_init::{pin_data, pin_init, pinned_drop, PinInit}; + +/// An array which efficiently maps sparse integer indices to owned objects. +/// +/// This is similar to a [`crate::alloc::kvec::Vec>`], but more efficient when there are +/// holes in the index space, and can be efficiently grown. +/// +/// # Invariants +/// +/// `self.xa` is always an initialized and valid [`bindings::xarray`] whose entries are either +/// `XA_ZERO_ENTRY` or came from `T::into_foreign`. +/// +/// # Examples +/// +/// ```rust +/// use kernel::alloc::KBox; +/// use kernel::xarray::{AllocKind, XArray}; +/// +/// let xa = KBox::pin_init(XArray::new(AllocKind::Alloc1), GFP_KERNEL)?; +/// +/// let dead = KBox::new(0xdead, GFP_KERNEL)?; +/// let beef = KBox::new(0xbeef, GFP_KERNEL)?; +/// +/// let mut guard = xa.lock(); +/// +/// assert_eq!(guard.get(0), None); +/// +/// assert_eq!(guard.store(0, dead, GFP_KERNEL)?.as_deref(), None); +/// assert_eq!(guard.get(0).copied(), Some(0xdead)); +/// +/// *guard.get_mut(0).unwrap() = 0xffff; +/// assert_eq!(guard.get(0).copied(), Some(0xffff)); +/// +/// assert_eq!(guard.store(0, beef, GFP_KERNEL)?.as_deref().copied(), Some(0xffff)); +/// assert_eq!(guard.get(0).copied(), Some(0xbeef)); +/// +/// guard.remove(0); +/// assert_eq!(guard.get(0), None); +/// +/// # Ok::<(), Error>(()) +/// ``` +#[pin_data(PinnedDrop)] +pub struct XArray { + #[pin] + xa: Opaque, + _p: PhantomData, +} + +#[pinned_drop] +impl PinnedDrop for XArray { + fn drop(self: Pin<&mut Self>) { + self.iter().for_each(|ptr| { + let ptr = ptr.as_ptr(); + // SAFETY: `ptr` came from `T::into_foreign`. + // + // INVARIANT: we own the only reference to the array which is being dropped so the + // broken invariant is not observable on function exit. + drop(unsafe { T::from_foreign(ptr) }) + }); + + // SAFETY: `self.xa` is always valid by the type invariant. + unsafe { bindings::xa_destroy(self.xa.get()) }; + } +} + +/// Flags passed to [`XArray::new`] to configure the array's allocation tracking behavior. +pub enum AllocKind { + /// Consider the first element to be at index 0. + Alloc, + /// Consider the first element to be at index 1. + Alloc1, +} + +impl XArray { + /// Creates a new initializer for this type. + pub fn new(kind: AllocKind) -> impl PinInit { + let flags = match kind { + AllocKind::Alloc => bindings::XA_FLAGS_ALLOC, + AllocKind::Alloc1 => bindings::XA_FLAGS_ALLOC1, + }; + pin_init!(Self { + // SAFETY: `xa` is valid while the closure is called. + // + // INVARIANT: `xa` is initialized here to an empty, valid [`bindings::xarray`]. + xa <- Opaque::ffi_init(|xa| unsafe { + bindings::xa_init_flags(xa, flags) + }), + _p: PhantomData, + }) + } + + fn iter(&self) -> impl Iterator> + '_ { + let mut index = 0; + + // SAFETY: `self.xa` is always valid by the type invariant. + iter::once(unsafe { + bindings::xa_find(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT) + }) + .chain(iter::from_fn(move || { + // SAFETY: `self.xa` is always valid by the type invariant. + Some(unsafe { + bindings::xa_find_after(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT) + }) + })) + .map_while(|ptr| NonNull::new(ptr.cast())) + } + + /// Attempts to lock the [`XArray`] for exclusive access. + pub fn try_lock(&self) -> Option> { + // SAFETY: `self.xa` is always valid by the type invariant. + if (unsafe { bindings::xa_trylock(self.xa.get()) } != 0) { + Some(Guard { + xa: self, + _not_send: NotThreadSafe, + }) + } else { + None + } + } + + /// Locks the [`XArray`] for exclusive access. + pub fn lock(&self) -> Guard<'_, T> { + // SAFETY: `self.xa` is always valid by the type invariant. + unsafe { bindings::xa_lock(self.xa.get()) }; + + Guard { + xa: self, + _not_send: NotThreadSafe, + } + } +} + +/// A lock guard. +/// +/// The lock is unlocked when the guard goes out of scope. +#[must_use = "the lock unlocks immediately when the guard is unused"] +pub struct Guard<'a, T: ForeignOwnable> { + xa: &'a XArray, + _not_send: NotThreadSafe, +} + +impl Drop for Guard<'_, T> { + fn drop(&mut self) { + // SAFETY: + // - `self.xa.xa` is always valid by the type invariant. + // - The caller holds the lock, so it is safe to unlock it. + unsafe { bindings::xa_unlock(self.xa.xa.get()) }; + } +} + +/// The error returned by [`store`](Guard::store). +/// +/// Contains the underlying error and the value that was not stored. +pub struct StoreError { + /// The error that occurred. + pub error: Error, + /// The value that was not stored. + pub value: T, +} + +impl From> for Error { + fn from(value: StoreError) -> Self { + value.error + } +} + +impl<'a, T: ForeignOwnable> Guard<'a, T> { + fn load(&self, index: usize, f: F) -> Option + where + F: FnOnce(NonNull) -> U, + { + // SAFETY: `self.xa.xa` is always valid by the type invariant. + let ptr = unsafe { bindings::xa_load(self.xa.xa.get(), index) }; + let ptr = NonNull::new(ptr.cast())?; + Some(f(ptr)) + } + + /// Provides a reference to the element at the given index. + pub fn get(&self, index: usize) -> Option> { + self.load(index, |ptr| { + // SAFETY: `ptr` came from `T::into_foreign`. + unsafe { T::borrow(ptr.as_ptr()) } + }) + } + + /// Provides a mutable reference to the element at the given index. + pub fn get_mut(&mut self, index: usize) -> Option> { + self.load(index, |ptr| { + // SAFETY: `ptr` came from `T::into_foreign`. + unsafe { T::borrow_mut(ptr.as_ptr()) } + }) + } + + /// Removes and returns the element at the given index. + pub fn remove(&mut self, index: usize) -> Option { + // SAFETY: + // - `self.xa.xa` is always valid by the type invariant. + // - The caller holds the lock. + let ptr = unsafe { bindings::__xa_erase(self.xa.xa.get(), index) }.cast(); + // SAFETY: + // - `ptr` is either NULL or came from `T::into_foreign`. + // - `&mut self` guarantees that the lifetimes of [`T::Borrowed`] and [`T::BorrowedMut`] + // borrowed from `self` have ended. + unsafe { T::try_from_foreign(ptr) } + } + + /// Stores an element at the given index. + /// + /// May drop the lock if needed to allocate memory, and then reacquire it afterwards. + /// + /// On success, returns the element which was previously at the given index. + /// + /// On failure, returns the element which was attempted to be stored. + pub fn store( + &mut self, + index: usize, + value: T, + gfp: alloc::Flags, + ) -> Result, StoreError> { + build_assert!( + mem::align_of::() >= 4, + "pointers stored in XArray must be 4-byte aligned" + ); + let new = value.into_foreign(); + + let old = { + let new = new.cast(); + // SAFETY: + // - `self.xa.xa` is always valid by the type invariant. + // - The caller holds the lock. + // + // INVARIANT: `new` came from `T::into_foreign`. + unsafe { bindings::__xa_store(self.xa.xa.get(), index, new, gfp.as_raw()) } + }; + + // SAFETY: `__xa_store` returns the old entry at this index on success or `xa_err` if an + // error happened. + let errno = unsafe { bindings::xa_err(old) }; + if errno != 0 { + // SAFETY: `new` came from `T::into_foreign` and `__xa_store` does not take + // ownership of the value on error. + let value = unsafe { T::from_foreign(new) }; + Err(StoreError { + value, + error: Error::from_errno(errno), + }) + } else { + let old = old.cast(); + // SAFETY: `ptr` is either NULL or came from `T::into_foreign`. + // + // NB: `XA_ZERO_ENTRY` is never returned by functions belonging to the Normal XArray + // API; such entries present as `NULL`. + Ok(unsafe { T::try_from_foreign(old) }) + } + } +} + +// SAFETY: `XArray` has no shared mutable state so it is `Send` iff `T` is `Send`. +unsafe impl Send for XArray {} + +// SAFETY: `XArray` serialises the interior mutability it provides so it is `Sync` iff `T` is +// `Send`. +unsafe impl Sync for XArray {} -- cgit v1.2.3 From a39f3087092716f2bd531d6fdc20403c3dc2a879 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 16:02:34 +0200 Subject: rust: allow Rust 1.87.0's `clippy::ptr_eq` lint Starting with Rust 1.87.0 (expected 2025-05-15) [1], Clippy may expand the `ptr_eq` lint, e.g.: error: use `core::ptr::eq` when comparing raw pointers --> rust/kernel/list.rs:438:12 | 438 | if self.first == item { | ^^^^^^^^^^^^^^^^^^ help: try: `core::ptr::eq(self.first, item)` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_eq = note: `-D clippy::ptr-eq` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::ptr_eq)]` It is expected that a PR to relax the lint will be backported [2] by the time Rust 1.87.0 releases, since the lint was considered too eager (at least by default) [3]. Thus allow the lint temporarily just in case. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust-clippy/pull/14339 [1] Link: https://github.com/rust-lang/rust-clippy/pull/14526 [2] Link: https://github.com/rust-lang/rust-clippy/issues/14525 [3] Link: https://lore.kernel.org/r/20250502140237.1659624-3-ojeda@kernel.org [ Converted to `allow`s since backport was confirmed. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/kvec.rs | 3 +++ rust/kernel/list.rs | 3 +++ 2 files changed, 6 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index ae9d072741ce..87a71fd40c3c 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -2,6 +2,9 @@ //! Implementation of [`Vec`]. +// May not be needed in Rust 1.87.0 (pending beta backport). +#![allow(clippy::ptr_eq)] + use super::{ allocator::{KVmalloc, Kmalloc, Vmalloc}, layout::ArrayLayout, diff --git a/rust/kernel/list.rs b/rust/kernel/list.rs index a335c3b1ff5e..2054682c5724 100644 --- a/rust/kernel/list.rs +++ b/rust/kernel/list.rs @@ -4,6 +4,9 @@ //! A linked list implementation. +// May not be needed in Rust 1.87.0 (pending beta backport). +#![allow(clippy::ptr_eq)] + use crate::sync::ArcBorrow; use crate::types::Opaque; use core::iter::{DoubleEndedIterator, FusedIterator}; -- cgit v1.2.3 From 211dcf77856db64c73e0c3b9ce0c624ec855daca Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 16:02:37 +0200 Subject: rust: clean Rust 1.88.0's `clippy::uninlined_format_args` lint Starting with Rust 1.88.0 (expected 2025-06-26) [1], `rustc` may move back the `uninlined_format_args` to `style` from `pedantic` (it was there waiting for rust-analyzer suppotr), and thus we will start to see lints like: warning: variables can be used directly in the `format!` string --> rust/macros/kunit.rs:105:37 | 105 | let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{}", test); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args help: change this to | 105 - let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{}", test); 105 + let kunit_wrapper_fn_name = format!("kunit_rust_wrapper_{test}"); There is even a case that is a pure removal: warning: variables can be used directly in the `format!` string --> rust/macros/module.rs:51:13 | 51 | format!("{field}={content}\0", field = field, content = content) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args help: change this to | 51 - format!("{field}={content}\0", field = field, content = content) 51 + format!("{field}={content}\0") The lints all seem like nice cleanups, thus just apply them. We may want to disable `allow-mixed-uninlined-format-args` in the future. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust-clippy/pull/14160 [1] Acked-by: Benno Lossin Reviewed-by: Tamir Duberstein Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250502140237.1659624-6-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/str.rs | 46 +++++++++++++++++++++++----------------------- 1 file changed, 23 insertions(+), 23 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 878111cb77bc..fb61ce81ea28 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -73,7 +73,7 @@ impl fmt::Display for BStr { b'\r' => f.write_str("\\r")?, // Printable characters. 0x20..=0x7e => f.write_char(b as char)?, - _ => write!(f, "\\x{:02x}", b)?, + _ => write!(f, "\\x{b:02x}")?, } } Ok(()) @@ -109,7 +109,7 @@ impl fmt::Debug for BStr { b'\\' => f.write_str("\\\\")?, // Printable characters. 0x20..=0x7e => f.write_char(b as char)?, - _ => write!(f, "\\x{:02x}", b)?, + _ => write!(f, "\\x{b:02x}")?, } } f.write_char('"') @@ -447,7 +447,7 @@ impl fmt::Display for CStr { // Printable character. f.write_char(c as char)?; } else { - write!(f, "\\x{:02x}", c)?; + write!(f, "\\x{c:02x}")?; } } Ok(()) @@ -479,7 +479,7 @@ impl fmt::Debug for CStr { // Printable characters. b'\"' => f.write_str("\\\"")?, 0x20..=0x7e => f.write_char(c as char)?, - _ => write!(f, "\\x{:02x}", c)?, + _ => write!(f, "\\x{c:02x}")?, } } f.write_str("\"") @@ -641,13 +641,13 @@ mod tests { #[test] fn test_cstr_display() { let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap(); - assert_eq!(format!("{}", hello_world), "hello, world!"); + assert_eq!(format!("{hello_world}"), "hello, world!"); let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap(); - assert_eq!(format!("{}", non_printables), "\\x01\\x09\\x0a"); + assert_eq!(format!("{non_printables}"), "\\x01\\x09\\x0a"); let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap(); - assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu"); + assert_eq!(format!("{non_ascii}"), "d\\xe9j\\xe0 vu"); let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap(); - assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80"); + assert_eq!(format!("{good_bytes}"), "\\xf0\\x9f\\xa6\\x80"); } #[test] @@ -658,47 +658,47 @@ mod tests { bytes[i as usize] = i.wrapping_add(1); } let cstr = CStr::from_bytes_with_nul(&bytes).unwrap(); - assert_eq!(format!("{}", cstr), ALL_ASCII_CHARS); + assert_eq!(format!("{cstr}"), ALL_ASCII_CHARS); } #[test] fn test_cstr_debug() { let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap(); - assert_eq!(format!("{:?}", hello_world), "\"hello, world!\""); + assert_eq!(format!("{hello_world:?}"), "\"hello, world!\""); let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap(); - assert_eq!(format!("{:?}", non_printables), "\"\\x01\\x09\\x0a\""); + assert_eq!(format!("{non_printables:?}"), "\"\\x01\\x09\\x0a\""); let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap(); - assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\""); + assert_eq!(format!("{non_ascii:?}"), "\"d\\xe9j\\xe0 vu\""); let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap(); - assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\""); + assert_eq!(format!("{good_bytes:?}"), "\"\\xf0\\x9f\\xa6\\x80\""); } #[test] fn test_bstr_display() { let hello_world = BStr::from_bytes(b"hello, world!"); - assert_eq!(format!("{}", hello_world), "hello, world!"); + assert_eq!(format!("{hello_world}"), "hello, world!"); let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_"); - assert_eq!(format!("{}", escapes), "_\\t_\\n_\\r_\\_'_\"_"); + assert_eq!(format!("{escapes}"), "_\\t_\\n_\\r_\\_'_\"_"); let others = BStr::from_bytes(b"\x01"); - assert_eq!(format!("{}", others), "\\x01"); + assert_eq!(format!("{others}"), "\\x01"); let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu"); - assert_eq!(format!("{}", non_ascii), "d\\xe9j\\xe0 vu"); + assert_eq!(format!("{non_ascii}"), "d\\xe9j\\xe0 vu"); let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80"); - assert_eq!(format!("{}", good_bytes), "\\xf0\\x9f\\xa6\\x80"); + assert_eq!(format!("{good_bytes}"), "\\xf0\\x9f\\xa6\\x80"); } #[test] fn test_bstr_debug() { let hello_world = BStr::from_bytes(b"hello, world!"); - assert_eq!(format!("{:?}", hello_world), "\"hello, world!\""); + assert_eq!(format!("{hello_world:?}"), "\"hello, world!\""); let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_"); - assert_eq!(format!("{:?}", escapes), "\"_\\t_\\n_\\r_\\\\_'_\\\"_\""); + assert_eq!(format!("{escapes:?}"), "\"_\\t_\\n_\\r_\\\\_'_\\\"_\""); let others = BStr::from_bytes(b"\x01"); - assert_eq!(format!("{:?}", others), "\"\\x01\""); + assert_eq!(format!("{others:?}"), "\"\\x01\""); let non_ascii = BStr::from_bytes(b"d\xe9j\xe0 vu"); - assert_eq!(format!("{:?}", non_ascii), "\"d\\xe9j\\xe0 vu\""); + assert_eq!(format!("{non_ascii:?}"), "\"d\\xe9j\\xe0 vu\""); let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80"); - assert_eq!(format!("{:?}", good_bytes), "\"\\xf0\\x9f\\xa6\\x80\""); + assert_eq!(format!("{good_bytes:?}"), "\"\\xf0\\x9f\\xa6\\x80\""); } } -- cgit v1.2.3 From a1e4d5c9d708d7a0e7071015a120a4489404128f Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:29 +0000 Subject: rust: alloc: add Vec::clear Our custom Vec type is missing the stdlib method `clear`, thus add it. It will be used in the miscdevice sample. Reviewed-by: Benno Lossin Reviewed-by: Tamir Duberstein Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20250502-vec-methods-v5-1-06d20ad9366f@google.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 5798e2c890a2..412a2fe3ce79 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -413,6 +413,26 @@ where (ptr, len, capacity) } + /// Clears the vector, removing all values. + /// + /// Note that this method has no effect on the allocated capacity + /// of the vector. + /// + /// # Examples + /// + /// ``` + /// let mut v = kernel::kvec![1, 2, 3]?; + /// + /// v.clear(); + /// + /// assert!(v.is_empty()); + /// # Ok::<(), Error>(()) + /// ``` + #[inline] + pub fn clear(&mut self) { + self.truncate(0); + } + /// Ensures that the capacity exceeds the length by at least `additional` elements. /// /// # Examples -- cgit v1.2.3 From f2b4dd7093438e4884cb01a783212abfbc9cc40b Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:30 +0000 Subject: rust: alloc: add Vec::pop This introduces a basic method that our custom Vec is missing. I expect that it will be used in many places, but at the time of writing, Rust Binder has six calls to Vec::pop. Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-2-06d20ad9366f@google.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 412a2fe3ce79..ebca0cfd31c6 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -320,6 +320,37 @@ where Ok(()) } + /// Removes the last element from a vector and returns it, or `None` if it is empty. + /// + /// # Examples + /// + /// ``` + /// let mut v = KVec::new(); + /// v.push(1, GFP_KERNEL)?; + /// v.push(2, GFP_KERNEL)?; + /// assert_eq!(&v, &[1, 2]); + /// + /// assert_eq!(v.pop(), Some(2)); + /// assert_eq!(v.pop(), Some(1)); + /// assert_eq!(v.pop(), None); + /// # Ok::<(), Error>(()) + /// ``` + pub fn pop(&mut self) -> Option { + if self.is_empty() { + return None; + } + + let removed: *mut T = { + // SAFETY: We just checked that the length is at least one. + let slice = unsafe { self.dec_len(1) }; + // SAFETY: The argument to `dec_len` was 1 so this returns a slice of length 1. + unsafe { slice.get_unchecked_mut(0) } + }; + + // SAFETY: The guarantees of `dec_len` allow us to take ownership of this value. + Some(unsafe { removed.read() }) + } + /// Creates a new [`Vec`] instance with at least the given capacity. /// /// # Examples -- cgit v1.2.3 From 9def0d0a2a1c62d7970f4ce5ad5557968c98f637 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:31 +0000 Subject: rust: alloc: add Vec::push_within_capacity This introduces a new method called `push_within_capacity` for appending to a vector without attempting to allocate if the capacity is full. Rust Binder will use this in various places to safely push to a vector while holding a spinlock. The implementation is moved to a push_within_capacity_unchecked method. This is preferred over having push() call push_within_capacity() followed by an unwrap_unchecked() for simpler unsafe. Panics in the kernel are best avoided when possible, so an error is returned if the vector does not have sufficient capacity. An error type is used rather than just returning Result<(),T> to make it more convenient for callers (i.e. they can use ? or unwrap). Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-3-06d20ad9366f@google.com [ Remove public visibility from `Vec::push_within_capacity_unchecked()`. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 46 ++++++++++++++++++++++++++++++++++++---- rust/kernel/alloc/kvec/errors.rs | 23 ++++++++++++++++++++ 2 files changed, 65 insertions(+), 4 deletions(-) create mode 100644 rust/kernel/alloc/kvec/errors.rs (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index ebca0cfd31c6..64dfa9af5589 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -21,6 +21,9 @@ use core::{ slice::SliceIndex, }; +mod errors; +pub use self::errors::PushError; + /// Create a [`KVec`] containing the arguments. /// /// New memory is allocated with `GFP_KERNEL`. @@ -307,17 +310,52 @@ where /// ``` pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> { self.reserve(1, flags)?; + // SAFETY: The call to `reserve` was successful, so the capacity is at least one greater + // than the length. + unsafe { self.push_within_capacity_unchecked(v) }; + Ok(()) + } + /// Appends an element to the back of the [`Vec`] instance without reallocating. + /// + /// Fails if the vector does not have capacity for the new element. + /// + /// # Examples + /// + /// ``` + /// let mut v = KVec::with_capacity(10, GFP_KERNEL)?; + /// for i in 0..10 { + /// v.push_within_capacity(i)?; + /// } + /// + /// assert!(v.push_within_capacity(10).is_err()); + /// # Ok::<(), Error>(()) + /// ``` + pub fn push_within_capacity(&mut self, v: T) -> Result<(), PushError> { + if self.len() < self.capacity() { + // SAFETY: The length is less than the capacity. + unsafe { self.push_within_capacity_unchecked(v) }; + Ok(()) + } else { + Err(PushError(v)) + } + } + + /// Appends an element to the back of the [`Vec`] instance without reallocating. + /// + /// # Safety + /// + /// The length must be less than the capacity. + unsafe fn push_within_capacity_unchecked(&mut self, v: T) { let spare = self.spare_capacity_mut(); - // SAFETY: The call to `reserve` was successful so the spare capacity is at least 1. + // SAFETY: By the safety requirements, `spare` is non-empty. unsafe { spare.get_unchecked_mut(0) }.write(v); // SAFETY: We just initialised the first spare entry, so it is safe to increase the length - // by 1. We also know that the new length is <= capacity because of the previous call to - // `reserve` above. + // by 1. We also know that the new length is <= capacity because the caller guarantees that + // the length is less than the capacity at the beginning of this function. unsafe { self.inc_len(1) }; - Ok(()) } /// Removes the last element from a vector and returns it, or `None` if it is empty. diff --git a/rust/kernel/alloc/kvec/errors.rs b/rust/kernel/alloc/kvec/errors.rs new file mode 100644 index 000000000000..84c96ec5007d --- /dev/null +++ b/rust/kernel/alloc/kvec/errors.rs @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Errors for the [`Vec`] type. + +use core::fmt::{self, Debug, Formatter}; +use kernel::prelude::*; + +/// Error type for [`Vec::push_within_capacity`]. +pub struct PushError(pub T); + +impl Debug for PushError { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + write!(f, "Not enough capacity") + } +} + +impl From> for Error { + fn from(_: PushError) -> Error { + // Returning ENOMEM isn't appropriate because the system is not out of memory. The vector + // is just full and we are refusing to resize it. + EINVAL + } +} -- cgit v1.2.3 From 088bf14a886e1e746c961a862ebccbb76d7cbd4e Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:32 +0000 Subject: rust: alloc: add Vec::drain_all This is like the stdlib method drain, except that it's hard-coded to use the entire vector's range. Rust Binder uses it in the range allocator to take ownership of everything in a vector in a case where reusing the vector is desirable. Implementing `DrainAll` in terms of `slice::IterMut` lets us reuse some nice optimizations in core for the case where T is a ZST. Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-4-06d20ad9366f@google.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 59 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 64dfa9af5589..afaf22865342 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -586,6 +586,30 @@ where unsafe { ptr::drop_in_place(ptr) }; } } + + /// Takes ownership of all items in this vector without consuming the allocation. + /// + /// # Examples + /// + /// ``` + /// let mut v = kernel::kvec![0, 1, 2, 3]?; + /// + /// for (i, j) in v.drain_all().enumerate() { + /// assert_eq!(i, j); + /// } + /// + /// assert!(v.capacity() >= 4); + /// # Ok::<(), Error>(()) + /// ``` + pub fn drain_all(&mut self) -> DrainAll<'_, T> { + // SAFETY: This does not underflow the length. + let elems = unsafe { self.dec_len(self.len()) }; + // INVARIANT: The first `len` elements of the spare capacity are valid values, and as we + // just set the length to zero, we may transfer ownership to the `DrainAll` object. + DrainAll { + elements: elems.iter_mut(), + } + } } impl Vec { @@ -1073,3 +1097,38 @@ where } } } + +/// An iterator that owns all items in a vector, but does not own its allocation. +/// +/// # Invariants +/// +/// Every `&mut T` returned by the iterator references a `T` that the iterator may take ownership +/// of. +pub struct DrainAll<'vec, T> { + elements: slice::IterMut<'vec, T>, +} + +impl<'vec, T> Iterator for DrainAll<'vec, T> { + type Item = T; + + fn next(&mut self) -> Option { + let elem: *mut T = self.elements.next()?; + // SAFETY: By the type invariants, we may take ownership of this value. + Some(unsafe { elem.read() }) + } + + fn size_hint(&self) -> (usize, Option) { + self.elements.size_hint() + } +} + +impl<'vec, T> Drop for DrainAll<'vec, T> { + fn drop(&mut self) { + if core::mem::needs_drop::() { + let iter = core::mem::take(&mut self.elements); + let ptr: *mut [T] = iter.into_slice(); + // SAFETY: By the type invariants, we own these values so we may destroy them. + unsafe { ptr::drop_in_place(ptr) }; + } + } +} -- cgit v1.2.3 From 9f140894e72735f034fdc0e963d0550ef03c6f44 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:33 +0000 Subject: rust: alloc: add Vec::retain This adds a common Vec method called `retain` that removes all elements that don't match a certain condition. Rust Binder uses it to find all processes that match a given pid. The stdlib retain method takes &T rather than &mut T and has a separate retain_mut for the &mut T case. However, this is considered an API mistake that can't be fixed now due to backwards compatibility. There's no reason for us to repeat that mistake. Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-5-06d20ad9366f@google.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 72 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index afaf22865342..8843dea0b377 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -610,6 +610,29 @@ where elements: elems.iter_mut(), } } + + /// Removes all elements that don't match the provided closure. + /// + /// # Examples + /// + /// ``` + /// let mut v = kernel::kvec![1, 2, 3, 4]?; + /// v.retain(|i| *i % 2 == 0); + /// assert_eq!(v, [2, 4]); + /// # Ok::<(), Error>(()) + /// ``` + pub fn retain(&mut self, mut f: impl FnMut(&mut T) -> bool) { + let mut num_kept = 0; + let mut next_to_check = 0; + while let Some(to_check) = self.get_mut(next_to_check) { + if f(to_check) { + self.swap(num_kept, next_to_check); + num_kept += 1; + } + next_to_check += 1; + } + self.truncate(num_kept); + } } impl Vec { @@ -1132,3 +1155,52 @@ impl<'vec, T> Drop for DrainAll<'vec, T> { } } } + +#[macros::kunit_tests(rust_kvec_kunit)] +mod tests { + use super::*; + use crate::prelude::*; + + #[test] + fn test_kvec_retain() { + /// Verify correctness for one specific function. + #[expect(clippy::needless_range_loop)] + fn verify(c: &[bool]) { + let mut vec1: KVec = KVec::with_capacity(c.len(), GFP_KERNEL).unwrap(); + let mut vec2: KVec = KVec::with_capacity(c.len(), GFP_KERNEL).unwrap(); + + for i in 0..c.len() { + vec1.push_within_capacity(i).unwrap(); + if c[i] { + vec2.push_within_capacity(i).unwrap(); + } + } + + vec1.retain(|i| c[*i]); + + assert_eq!(vec1, vec2); + } + + /// Add one to a binary integer represented as a boolean array. + fn add(value: &mut [bool]) { + let mut carry = true; + for v in value { + let new_v = carry != *v; + carry = carry && *v; + *v = new_v; + } + } + + // This boolean array represents a function from index to boolean. We check that `retain` + // behaves correctly for all possible boolean arrays of every possible length less than + // ten. + let mut func = KVec::with_capacity(10, GFP_KERNEL).unwrap(); + for len in 0..10 { + for _ in 0u32..1u32 << len { + verify(&func); + add(&mut func); + } + func.push_within_capacity(false).unwrap(); + } + } +} -- cgit v1.2.3 From 294a7ecbdf0a5d65c6df1287c5d56241e9331cf2 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:34 +0000 Subject: rust: alloc: add Vec::remove This is needed by Rust Binder in the range allocator, and by upcoming GPU drivers during firmware initialization. Panics in the kernel are best avoided when possible, so an error is returned if the index is out of bounds. An error type is used rather than just returning Option to let callers handle errors with ?. Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-6-06d20ad9366f@google.com [ Remove `# Panics` section; `Vec::remove() handles the error properly.` - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 38 +++++++++++++++++++++++++++++++++++++- rust/kernel/alloc/kvec/errors.rs | 15 +++++++++++++++ 2 files changed, 52 insertions(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 8843dea0b377..3f2617b08753 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -22,7 +22,7 @@ use core::{ }; mod errors; -pub use self::errors::PushError; +pub use self::errors::{PushError, RemoveError}; /// Create a [`KVec`] containing the arguments. /// @@ -389,6 +389,42 @@ where Some(unsafe { removed.read() }) } + /// Removes the element at the given index. + /// + /// # Examples + /// + /// ``` + /// let mut v = kernel::kvec![1, 2, 3]?; + /// assert_eq!(v.remove(1)?, 2); + /// assert_eq!(v, [1, 3]); + /// # Ok::<(), Error>(()) + /// ``` + pub fn remove(&mut self, i: usize) -> Result { + let value = { + let value_ref = self.get(i).ok_or(RemoveError)?; + // INVARIANT: This breaks the invariants by invalidating the value at index `i`, but we + // restore the invariants below. + // SAFETY: The value at index `i` is valid, because otherwise we would have already + // failed with `RemoveError`. + unsafe { ptr::read(value_ref) } + }; + + // SAFETY: We checked that `i` is in-bounds. + let p = unsafe { self.as_mut_ptr().add(i) }; + + // INVARIANT: After this call, the invalid value is at the last slot, so the Vec invariants + // are restored after the below call to `dec_len(1)`. + // SAFETY: `p.add(1).add(self.len - i - 1)` is `i+1+len-i-1 == len` elements after the + // beginning of the vector, so this is in-bounds of the vector's allocation. + unsafe { ptr::copy(p.add(1), p, self.len - i - 1) }; + + // SAFETY: Since the check at the beginning of this call did not fail with `RemoveError`, + // the length is at least one. + unsafe { self.dec_len(1) }; + + Ok(value) + } + /// Creates a new [`Vec`] instance with at least the given capacity. /// /// # Examples diff --git a/rust/kernel/alloc/kvec/errors.rs b/rust/kernel/alloc/kvec/errors.rs index 84c96ec5007d..06fe696e8bc6 100644 --- a/rust/kernel/alloc/kvec/errors.rs +++ b/rust/kernel/alloc/kvec/errors.rs @@ -21,3 +21,18 @@ impl From> for Error { EINVAL } } + +/// Error type for [`Vec::remove`]. +pub struct RemoveError; + +impl Debug for RemoveError { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + write!(f, "Index out of bounds") + } +} + +impl From for Error { + fn from(_: RemoveError) -> Error { + EINVAL + } +} -- cgit v1.2.3 From 771c5a7d9843643b035938624050e7769133b9cc Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:35 +0000 Subject: rust: alloc: add Vec::insert_within_capacity This adds a variant of Vec::insert that does not allocate memory. This makes it safe to use this function while holding a spinlock. Rust Binder uses it for the range allocator fast path. Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-7-06d20ad9366f@google.com Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec.rs | 51 +++++++++++++++++++++++++++++++++++++++- rust/kernel/alloc/kvec/errors.rs | 23 ++++++++++++++++++ 2 files changed, 73 insertions(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 3f2617b08753..1a0dd852a468 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -22,7 +22,7 @@ use core::{ }; mod errors; -pub use self::errors::{PushError, RemoveError}; +pub use self::errors::{InsertError, PushError, RemoveError}; /// Create a [`KVec`] containing the arguments. /// @@ -358,6 +358,55 @@ where unsafe { self.inc_len(1) }; } + /// Inserts an element at the given index in the [`Vec`] instance. + /// + /// Fails if the vector does not have capacity for the new element. Panics if the index is out + /// of bounds. + /// + /// # Examples + /// + /// ``` + /// use kernel::alloc::kvec::InsertError; + /// + /// let mut v = KVec::with_capacity(5, GFP_KERNEL)?; + /// for i in 0..5 { + /// v.insert_within_capacity(0, i)?; + /// } + /// + /// assert!(matches!(v.insert_within_capacity(0, 5), Err(InsertError::OutOfCapacity(_)))); + /// assert!(matches!(v.insert_within_capacity(1000, 5), Err(InsertError::IndexOutOfBounds(_)))); + /// assert_eq!(v, [4, 3, 2, 1, 0]); + /// # Ok::<(), Error>(()) + /// ``` + pub fn insert_within_capacity( + &mut self, + index: usize, + element: T, + ) -> Result<(), InsertError> { + let len = self.len(); + if index > len { + return Err(InsertError::IndexOutOfBounds(element)); + } + + if len >= self.capacity() { + return Err(InsertError::OutOfCapacity(element)); + } + + // SAFETY: This is in bounds since `index <= len < capacity`. + let p = unsafe { self.as_mut_ptr().add(index) }; + // INVARIANT: This breaks the Vec invariants by making `index` contain an invalid element, + // but we restore the invariants below. + // SAFETY: Both the src and dst ranges end no later than one element after the length. + // Since the length is less than the capacity, both ranges are in bounds of the allocation. + unsafe { ptr::copy(p, p.add(1), len - index) }; + // INVARIANT: This restores the Vec invariants. + // SAFETY: The pointer is in-bounds of the allocation. + unsafe { ptr::write(p, element) }; + // SAFETY: Index `len` contains a valid element due to the above copy and write. + unsafe { self.inc_len(1) }; + Ok(()) + } + /// Removes the last element from a vector and returns it, or `None` if it is empty. /// /// # Examples diff --git a/rust/kernel/alloc/kvec/errors.rs b/rust/kernel/alloc/kvec/errors.rs index 06fe696e8bc6..348b8d27e102 100644 --- a/rust/kernel/alloc/kvec/errors.rs +++ b/rust/kernel/alloc/kvec/errors.rs @@ -36,3 +36,26 @@ impl From for Error { EINVAL } } + +/// Error type for [`Vec::insert_within_capacity`]. +pub enum InsertError { + /// The value could not be inserted because the index is out of bounds. + IndexOutOfBounds(T), + /// The value could not be inserted because the vector is out of capacity. + OutOfCapacity(T), +} + +impl Debug for InsertError { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + match self { + InsertError::IndexOutOfBounds(_) => write!(f, "Index out of bounds"), + InsertError::OutOfCapacity(_) => write!(f, "Not enough capacity"), + } + } +} + +impl From> for Error { + fn from(_: InsertError) -> Error { + EINVAL + } +} -- cgit v1.2.3 From 878620c5a93a24af10e64b116e66c2314e91a719 Mon Sep 17 00:00:00 2001 From: Kunwu Chan Date: Fri, 21 Mar 2025 16:01:24 +0800 Subject: rust: page: optimize rust symbol generation for Page When build the kernel using the llvm-18.1.3-rust-1.85.0-x86_64 with ARCH=arm64, the following symbols are generated: $nm vmlinux | grep ' _R'.*Page | rustfilt ffff8000805b6f98 T ::alloc_page ffff8000805b715c T ::fill_zero_raw ffff8000805b720c T ::copy_from_user_slice_raw ffff8000805b6fb4 T ::read_raw ffff8000805b7088 T ::write_raw ffff8000805b72fc T ::drop These Rust symbols(alloc_page and drop) are trivial wrappers around the C functions alloc_pages and __free_pages. It doesn't make sense to go through a trivial wrapper for these functions, so mark them inline. Link: https://github.com/Rust-for-Linux/linux/issues/1145 Suggested-by: Alice Ryhl Co-developed-by: Grace Deng Signed-off-by: Grace Deng Signed-off-by: Kunwu Chan Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250321080124.484647-1-kunwu.chan@linux.dev [ Removed spurious colon in title. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/page.rs | 2 ++ 1 file changed, 2 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/page.rs b/rust/kernel/page.rs index f6126aca33a6..7c1b17246ed5 100644 --- a/rust/kernel/page.rs +++ b/rust/kernel/page.rs @@ -69,6 +69,7 @@ impl Page { /// let page = Page::alloc_page(GFP_KERNEL | __GFP_ZERO)?; /// # Ok::<(), kernel::alloc::AllocError>(()) /// ``` + #[inline] pub fn alloc_page(flags: Flags) -> Result { // SAFETY: Depending on the value of `gfp_flags`, this call may sleep. Other than that, it // is always safe to call this method. @@ -251,6 +252,7 @@ impl Page { } impl Drop for Page { + #[inline] fn drop(&mut self) { // SAFETY: By the type invariants, we have ownership of the page and can free it. unsafe { bindings::__free_pages(self.page.as_ptr(), 0) }; -- cgit v1.2.3 From 0fa5f8c877cae959de7cf6c3dc054e23e7ebcd75 Mon Sep 17 00:00:00 2001 From: Altan Ozlu Date: Wed, 26 Mar 2025 20:25:36 +0000 Subject: rust: static_assert: add optional message Add an optional panic message to the `static_assert!` macro. The panic message doesn't support argument formatting, because the `assert!` macro only supports formatting in non-const contexts. Suggested-by: Miguel Ojeda Link: https://github.com/Rust-for-Linux/linux/issues/1149 Signed-off-by: Altan Ozlu Reviewed-by: Benno Lossin Reviewed-by: Trevor Gross Link: https://lore.kernel.org/r/20250326202520.1176162-2-altan@ozlu.eu Signed-off-by: Miguel Ojeda --- rust/kernel/static_assert.rs | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/static_assert.rs b/rust/kernel/static_assert.rs index 3115ee0ba8e9..d8120f838260 100644 --- a/rust/kernel/static_assert.rs +++ b/rust/kernel/static_assert.rs @@ -6,6 +6,10 @@ /// /// Similar to C11 [`_Static_assert`] and C++11 [`static_assert`]. /// +/// An optional panic message can be supplied after the expression. +/// Currently only a string literal without formatting is supported +/// due to constness limitations of the [`assert!`] macro. +/// /// The feature may be added to Rust in the future: see [RFC 2790]. /// /// [`_Static_assert`]: https://en.cppreference.com/w/c/language/_Static_assert @@ -25,10 +29,11 @@ /// x + 2 /// } /// static_assert!(f(40) == 42); +/// static_assert!(f(40) == 42, "f(x) must add 2 to the given input."); /// ``` #[macro_export] macro_rules! static_assert { - ($condition:expr) => { - const _: () = core::assert!($condition); + ($condition:expr $(,$arg:literal)?) => { + const _: () = core::assert!($condition $(,$arg)?); }; } -- cgit v1.2.3 From 7d8dee4689278e174900509b8c4604651159d8ee Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Tue, 29 Apr 2025 17:14:45 +0200 Subject: rust: uaccess: take advantage of the prelude and `Result`'s defaults The `kernel` prelude brings `Result` and the error codes; and the prelude itself is already available in the examples automatically. In addition, `Result` already defaults to `T = ()`. Thus simplify. Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250429151445.438977-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/uaccess.rs | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs index 80a9782b1c6e..7e4c953ba8a1 100644 --- a/rust/kernel/uaccess.rs +++ b/rust/kernel/uaccess.rs @@ -46,10 +46,9 @@ pub type UserPtr = usize; /// /// ```no_run /// use kernel::ffi::c_void; -/// use kernel::error::Result; /// use kernel::uaccess::{UserPtr, UserSlice}; /// -/// fn bytes_add_one(uptr: UserPtr, len: usize) -> Result<()> { +/// fn bytes_add_one(uptr: UserPtr, len: usize) -> Result { /// let (read, mut write) = UserSlice::new(uptr, len).reader_writer(); /// /// let mut buf = KVec::new(); @@ -68,7 +67,6 @@ pub type UserPtr = usize; /// /// ```no_run /// use kernel::ffi::c_void; -/// use kernel::error::{code::EINVAL, Result}; /// use kernel::uaccess::{UserPtr, UserSlice}; /// /// /// Returns whether the data in this region is valid. -- cgit v1.2.3 From b9b701fce49a448b1e046f7cda592fec2958e5cd Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Thu, 27 Mar 2025 22:13:02 +0100 Subject: rust: clarify the language unstable features in use We track the details of which Rust features we use at our usual "live list" [1] (and its sub-lists), but in light of a discussion in the LWN article [2], it would help to clarify it in the source code. In particular, we are very close to rely only on stable Rust language-wise -- essentially only two language features remain (including the `kernel` crate). Thus add some details in both the feature list of the `kernel` crate as well as the list of allowed features. This does not over every single feature, and there are quite a few non-language features that we use too. To have the full picture, please refer to [1]. Link: https://github.com/Rust-for-Linux/linux/issues/2 [1] Link: https://lwn.net/Articles/1015409/ [2] Suggested-by: Andreas Hindborg Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250327211302.286313-1-ojeda@kernel.org [ Improved comments with suggestions from the list. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de07aadd1ff5..28007be98fba 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -12,20 +12,34 @@ //! do so first instead of bypassing this crate. #![no_std] -#![feature(arbitrary_self_types)] -#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dyn))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))] +// +// Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on +// the unstable features in use. +// +// Stable since Rust 1.79.0. #![feature(inline_const)] +// +// Stable since Rust 1.81.0. #![feature(lint_reasons)] -// Stable in Rust 1.82 +// +// Stable since Rust 1.82.0. #![feature(raw_ref_op)] -// Stable in Rust 1.83 +// +// Stable since Rust 1.83.0. #![feature(const_maybe_uninit_as_mut_ptr)] #![feature(const_mut_refs)] #![feature(const_ptr_write)] #![feature(const_refs_to_cell)] +// +// Expected to become stable. +#![feature(arbitrary_self_types)] +// +// `feature(derive_coerce_pointee)` is expected to become stable. Before Rust +// 1.84.0, it did not exist, so enable the predecessor features. +#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))] +#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))] +#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dyn))] +#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))] // Ensure conditional compilation based on the kernel configuration works; // otherwise we may silently break things like initcall handling. -- cgit v1.2.3 From 86d990c7b699581918de2a379c6eebac7292940e Mon Sep 17 00:00:00 2001 From: Xizhe Yin Date: Mon, 7 Apr 2025 11:34:41 +0800 Subject: rust: convert raw URLs to Markdown autolinks in comments Some comments in Rust files use raw URLs (http://example.com) rather than Markdown autolinks . This inconsistency makes the documentation less uniform and harder to maintain. This patch converts all remaining raw URLs in Rust code comments to use the Markdown autolink format, maintaining consistency with the rest of the codebase which already uses this style. Suggested-by: Miguel Ojeda Link: https://github.com/Rust-for-Linux/linux/issues/1153 Signed-off-by: Xizhe Yin Link: https://lore.kernel.org/r/509F0B66E3C1575D+20250407033441.5567-1-xizheyin@smail.nju.edu.cn [ Used From form for Signed-off-by. Sorted tags. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/kbox.rs | 2 +- rust/kernel/block/mq/gen_disk.rs | 2 +- rust/kernel/std_vendor.rs | 2 +- rust/kernel/sync/arc.rs | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs index b77d32f3a58b..604d12c6f5bd 100644 --- a/rust/kernel/alloc/kbox.rs +++ b/rust/kernel/alloc/kbox.rs @@ -101,7 +101,7 @@ pub type VBox = Box; pub type KVBox = Box; // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee: -// https://doc.rust-lang.org/stable/std/option/index.html#representation). +// ). unsafe impl ZeroableOption for Box {} // SAFETY: `Box` is `Send` if `T` is `Send` because the `Box` owns a `T`. diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs index 14806e1997fd..cd54cd64ea88 100644 --- a/rust/kernel/block/mq/gen_disk.rs +++ b/rust/kernel/block/mq/gen_disk.rs @@ -129,7 +129,7 @@ impl GenDiskBuilder { get_unique_id: None, // TODO: Set to THIS_MODULE. Waiting for const_refs_to_static feature to // be merged (unstable in rustc 1.78 which is staged for linux 6.10) - // https://github.com/rust-lang/rust/issues/119618 + // owner: core::ptr::null_mut(), pr_ops: core::ptr::null_mut(), free_disk: None, diff --git a/rust/kernel/std_vendor.rs b/rust/kernel/std_vendor.rs index 279bd353687a..abbab5050cc5 100644 --- a/rust/kernel/std_vendor.rs +++ b/rust/kernel/std_vendor.rs @@ -148,7 +148,7 @@ macro_rules! dbg { }; ($val:expr $(,)?) => { // Use of `match` here is intentional because it affects the lifetimes - // of temporaries - https://stackoverflow.com/a/48732525/1063961 + // of temporaries - match $val { tmp => { $crate::pr_info!("[{}:{}:{}] {} = {:#?}\n", diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 8484c814609a..350c380bb8d4 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -135,7 +135,7 @@ pub struct Arc { // meaningful with respect to dropck - but this may change in the future so this is left here // out of an abundance of caution. // - // See https://doc.rust-lang.org/nomicon/phantom-data.html#generic-parameters-and-drop-checking + // See // for more detail on the semantics of dropck in the presence of `PhantomData`. _p: PhantomData>, } -- cgit v1.2.3 From edc5e6e019c99b529b3d1f2801d5cce9924ae79b Mon Sep 17 00:00:00 2001 From: Andrew Ballance Date: Tue, 25 Mar 2025 08:33:52 -0500 Subject: rust: replace rustdoc references to alloc::format Replace alloc::format[1] in the pr_* and dev_* macros' doc comments with std::format[2] because they are identical but less likely to get confused with the kernel's alloc crate. And add a url link for the std::format! macro. Link: https://doc.rust-lang.org/alloc/macro.format.html [1] Link: https://doc.rust-lang.org/std/macro.format.html [2] Reviewed-by: Benno Lossin Signed-off-by: Andrew Ballance Link: https://lore.kernel.org/r/20250325133352.441425-1-andrewjballance@gmail.com [ Fixed typo and reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/device.rs | 24 ++++++++++++++++-------- rust/kernel/print.rs | 27 ++++++++++++++++++--------- 2 files changed, 34 insertions(+), 17 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 21b343a1dc4d..5c372cf27ed0 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -252,9 +252,10 @@ macro_rules! dev_printk { /// Equivalent to the kernel's `dev_emerg` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -277,9 +278,10 @@ macro_rules! dev_emerg { /// Equivalent to the kernel's `dev_alert` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -302,9 +304,10 @@ macro_rules! dev_alert { /// Equivalent to the kernel's `dev_crit` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -327,9 +330,10 @@ macro_rules! dev_crit { /// Equivalent to the kernel's `dev_err` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -352,9 +356,10 @@ macro_rules! dev_err { /// Equivalent to the kernel's `dev_warn` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -377,9 +382,10 @@ macro_rules! dev_warn { /// Equivalent to the kernel's `dev_notice` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -402,9 +408,10 @@ macro_rules! dev_notice { /// Equivalent to the kernel's `dev_info` macro. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -427,9 +434,10 @@ macro_rules! dev_info { /// Equivalent to the kernel's `dev_dbg` macro, except that it doesn't support dynamic debug yet. /// /// Mimics the interface of [`std::print!`]. More information about the syntax is available from -/// [`core::fmt`] and `alloc::format!`. +/// [`core::fmt`] and [`std::format!`]. /// /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs index cf4714242e14..9783d960a97a 100644 --- a/rust/kernel/print.rs +++ b/rust/kernel/print.rs @@ -198,10 +198,11 @@ macro_rules! print_macro ( /// Equivalent to the kernel's [`pr_emerg`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_emerg`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_emerg /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -222,10 +223,11 @@ macro_rules! pr_emerg ( /// Equivalent to the kernel's [`pr_alert`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_alert`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_alert /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -246,10 +248,11 @@ macro_rules! pr_alert ( /// Equivalent to the kernel's [`pr_crit`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_crit`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_crit /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -270,10 +273,11 @@ macro_rules! pr_crit ( /// Equivalent to the kernel's [`pr_err`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_err`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_err /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -294,10 +298,11 @@ macro_rules! pr_err ( /// Equivalent to the kernel's [`pr_warn`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_warn`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_warn /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -318,10 +323,11 @@ macro_rules! pr_warn ( /// Equivalent to the kernel's [`pr_notice`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_notice`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_notice /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -342,10 +348,11 @@ macro_rules! pr_notice ( /// Equivalent to the kernel's [`pr_info`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_info`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_info /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -368,10 +375,11 @@ macro_rules! pr_info ( /// yet. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_debug`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_debug /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// @@ -395,11 +403,12 @@ macro_rules! pr_debug ( /// Equivalent to the kernel's [`pr_cont`] macro. /// /// Mimics the interface of [`std::print!`]. See [`core::fmt`] and -/// `alloc::format!` for information about the formatting syntax. +/// [`std::format!`] for information about the formatting syntax. /// /// [`pr_info!`]: crate::pr_info! /// [`pr_cont`]: https://docs.kernel.org/core-api/printk-basics.html#c.pr_cont /// [`std::print!`]: https://doc.rust-lang.org/std/macro.print.html +/// [`std::format!`]: https://doc.rust-lang.org/std/macro.format.html /// /// # Examples /// -- cgit v1.2.3 From 5bb9ed6cdfeb75883652fd0ed3e3885083a92b4b Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:38 +0000 Subject: mm: rust: add abstraction for struct mm_struct MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Patch series "Rust support for mm_struct, vm_area_struct, and mmap", v16. This updates the vm_area_struct support to use the approach we discussed at LPC where there are several different Rust wrappers for vm_area_struct depending on the kind of access you have to the vma. Each case allows a different set of operations on the vma. This includes an MM MAINTAINERS entry as proposed by Lorenzo: https://lore.kernel.org/all/33e64b12-aa07-4e78-933a-b07c37ff1d84@lucifer.local/ This patch (of 9): These abstractions allow you to reference a `struct mm_struct` using both mmgrab and mmget refcounts. This is done using two Rust types: * Mm - represents an mm_struct where you don't know anything about the value of mm_users. * MmWithUser - represents an mm_struct where you know at compile time that mm_users is non-zero. This allows us to encode in the type system whether a method requires that mm_users is non-zero or not. For instance, you can always call `mmget_not_zero` but you can only call `mmap_read_lock` when mm_users is non-zero. The struct is called Mm to keep consistency with the C side. The ability to obtain `current->mm` is added later in this series. The mm module is defined to only exist when CONFIG_MMU is set. This avoids various errors due to missing types and functions when CONFIG_MMU is disabled. More fine-grained cfgs can be considered in the future. See the thread at [1] for more info. Link: https://lkml.kernel.org/r/20250408-vma-v16-9-d8b446e885d9@google.com Link: https://lkml.kernel.org/r/20250408-vma-v16-1-d8b446e885d9@google.com Link: https://lore.kernel.org/all/202503091916.QousmtcY-lkp@intel.com/ Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Acked-by: Balbir Singh Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: Jann Horn Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/lib.rs | 1 + rust/kernel/mm.rs | 210 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 211 insertions(+) create mode 100644 rust/kernel/mm.rs (limited to 'rust/kernel') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de07aadd1ff5..42ab6cf4053f 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -61,6 +61,7 @@ pub mod jump_label; pub mod kunit; pub mod list; pub mod miscdevice; +pub mod mm; #[cfg(CONFIG_NET)] pub mod net; pub mod of; diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs new file mode 100644 index 000000000000..eda7a479cff7 --- /dev/null +++ b/rust/kernel/mm.rs @@ -0,0 +1,210 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Memory management. +//! +//! This module deals with managing the address space of userspace processes. Each process has an +//! instance of [`Mm`], which keeps track of multiple VMAs (virtual memory areas). Each VMA +//! corresponds to a region of memory that the userspace process can access, and the VMA lets you +//! control what happens when userspace reads or writes to that region of memory. +//! +//! C header: [`include/linux/mm.h`](srctree/include/linux/mm.h) +#![cfg(CONFIG_MMU)] + +use crate::{ + bindings, + types::{ARef, AlwaysRefCounted, NotThreadSafe, Opaque}, +}; +use core::{ops::Deref, ptr::NonNull}; + +/// A wrapper for the kernel's `struct mm_struct`. +/// +/// This represents the address space of a userspace process, so each process has one `Mm` +/// instance. It may hold many VMAs internally. +/// +/// There is a counter called `mm_users` that counts the users of the address space; this includes +/// the userspace process itself, but can also include kernel threads accessing the address space. +/// Once `mm_users` reaches zero, this indicates that the address space can be destroyed. To access +/// the address space, you must prevent `mm_users` from reaching zero while you are accessing it. +/// The [`MmWithUser`] type represents an address space where this is guaranteed, and you can +/// create one using [`mmget_not_zero`]. +/// +/// The `ARef` smart pointer holds an `mmgrab` refcount. Its destructor may sleep. +/// +/// # Invariants +/// +/// Values of this type are always refcounted using `mmgrab`. +/// +/// [`mmget_not_zero`]: Mm::mmget_not_zero +#[repr(transparent)] +pub struct Mm { + mm: Opaque, +} + +// SAFETY: It is safe to call `mmdrop` on another thread than where `mmgrab` was called. +unsafe impl Send for Mm {} +// SAFETY: All methods on `Mm` can be called in parallel from several threads. +unsafe impl Sync for Mm {} + +// SAFETY: By the type invariants, this type is always refcounted. +unsafe impl AlwaysRefCounted for Mm { + #[inline] + fn inc_ref(&self) { + // SAFETY: The pointer is valid since self is a reference. + unsafe { bindings::mmgrab(self.as_raw()) }; + } + + #[inline] + unsafe fn dec_ref(obj: NonNull) { + // SAFETY: The caller is giving up their refcount. + unsafe { bindings::mmdrop(obj.cast().as_ptr()) }; + } +} + +/// A wrapper for the kernel's `struct mm_struct`. +/// +/// This type is like [`Mm`], but with non-zero `mm_users`. It can only be used when `mm_users` can +/// be proven to be non-zero at compile-time, usually because the relevant code holds an `mmget` +/// refcount. It can be used to access the associated address space. +/// +/// The `ARef` smart pointer holds an `mmget` refcount. Its destructor may sleep. +/// +/// # Invariants +/// +/// Values of this type are always refcounted using `mmget`. The value of `mm_users` is non-zero. +#[repr(transparent)] +pub struct MmWithUser { + mm: Mm, +} + +// SAFETY: It is safe to call `mmput` on another thread than where `mmget` was called. +unsafe impl Send for MmWithUser {} +// SAFETY: All methods on `MmWithUser` can be called in parallel from several threads. +unsafe impl Sync for MmWithUser {} + +// SAFETY: By the type invariants, this type is always refcounted. +unsafe impl AlwaysRefCounted for MmWithUser { + #[inline] + fn inc_ref(&self) { + // SAFETY: The pointer is valid since self is a reference. + unsafe { bindings::mmget(self.as_raw()) }; + } + + #[inline] + unsafe fn dec_ref(obj: NonNull) { + // SAFETY: The caller is giving up their refcount. + unsafe { bindings::mmput(obj.cast().as_ptr()) }; + } +} + +// Make all `Mm` methods available on `MmWithUser`. +impl Deref for MmWithUser { + type Target = Mm; + + #[inline] + fn deref(&self) -> &Mm { + &self.mm + } +} + +// These methods are safe to call even if `mm_users` is zero. +impl Mm { + /// Returns a raw pointer to the inner `mm_struct`. + #[inline] + pub fn as_raw(&self) -> *mut bindings::mm_struct { + self.mm.get() + } + + /// Obtain a reference from a raw pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` points at an `mm_struct`, and that it is not deallocated + /// during the lifetime 'a. + #[inline] + pub unsafe fn from_raw<'a>(ptr: *const bindings::mm_struct) -> &'a Mm { + // SAFETY: Caller promises that the pointer is valid for 'a. Layouts are compatible due to + // repr(transparent). + unsafe { &*ptr.cast() } + } + + /// Calls `mmget_not_zero` and returns a handle if it succeeds. + #[inline] + pub fn mmget_not_zero(&self) -> Option> { + // SAFETY: The pointer is valid since self is a reference. + let success = unsafe { bindings::mmget_not_zero(self.as_raw()) }; + + if success { + // SAFETY: We just created an `mmget` refcount. + Some(unsafe { ARef::from_raw(NonNull::new_unchecked(self.as_raw().cast())) }) + } else { + None + } + } +} + +// These methods require `mm_users` to be non-zero. +impl MmWithUser { + /// Obtain a reference from a raw pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` points at an `mm_struct`, and that `mm_users` remains + /// non-zero for the duration of the lifetime 'a. + #[inline] + pub unsafe fn from_raw<'a>(ptr: *const bindings::mm_struct) -> &'a MmWithUser { + // SAFETY: Caller promises that the pointer is valid for 'a. The layout is compatible due + // to repr(transparent). + unsafe { &*ptr.cast() } + } + + /// Lock the mmap read lock. + #[inline] + pub fn mmap_read_lock(&self) -> MmapReadGuard<'_> { + // SAFETY: The pointer is valid since self is a reference. + unsafe { bindings::mmap_read_lock(self.as_raw()) }; + + // INVARIANT: We just acquired the read lock. + MmapReadGuard { + mm: self, + _nts: NotThreadSafe, + } + } + + /// Try to lock the mmap read lock. + #[inline] + pub fn mmap_read_trylock(&self) -> Option> { + // SAFETY: The pointer is valid since self is a reference. + let success = unsafe { bindings::mmap_read_trylock(self.as_raw()) }; + + if success { + // INVARIANT: We just acquired the read lock. + Some(MmapReadGuard { + mm: self, + _nts: NotThreadSafe, + }) + } else { + None + } + } +} + +/// A guard for the mmap read lock. +/// +/// # Invariants +/// +/// This `MmapReadGuard` guard owns the mmap read lock. +pub struct MmapReadGuard<'a> { + mm: &'a MmWithUser, + // `mmap_read_lock` and `mmap_read_unlock` must be called on the same thread + _nts: NotThreadSafe, +} + +impl Drop for MmapReadGuard<'_> { + #[inline] + fn drop(&mut self) { + // SAFETY: We hold the read lock by the type invariants. + unsafe { bindings::mmap_read_unlock(self.mm.as_raw()) }; + } +} -- cgit v1.2.3 From 040f404b731207935ed644b14bcc2bb8b8488d00 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:39 +0000 Subject: mm: rust: add vm_area_struct methods that require read access MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This adds a type called VmaRef which is used when referencing a vma that you have read access to. Here, read access means that you hold either the mmap read lock or the vma read lock (or stronger). Additionally, a vma_lookup method is added to the mmap read guard, which enables you to obtain a &VmaRef in safe Rust code. This patch only provides a way to lock the mmap read lock, but a follow-up patch also provides a way to just lock the vma read lock. Link: https://lkml.kernel.org/r/20250408-vma-v16-2-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Jann Horn Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/mm.rs | 23 ++++++ rust/kernel/mm/virt.rs | 210 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 233 insertions(+) create mode 100644 rust/kernel/mm/virt.rs (limited to 'rust/kernel') diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs index eda7a479cff7..f1689ccb3740 100644 --- a/rust/kernel/mm.rs +++ b/rust/kernel/mm.rs @@ -18,6 +18,8 @@ use crate::{ }; use core::{ops::Deref, ptr::NonNull}; +pub mod virt; + /// A wrapper for the kernel's `struct mm_struct`. /// /// This represents the address space of a userspace process, so each process has one `Mm` @@ -201,6 +203,27 @@ pub struct MmapReadGuard<'a> { _nts: NotThreadSafe, } +impl<'a> MmapReadGuard<'a> { + /// Look up a vma at the given address. + #[inline] + pub fn vma_lookup(&self, vma_addr: usize) -> Option<&virt::VmaRef> { + // SAFETY: By the type invariants we hold the mmap read guard, so we can safely call this + // method. Any value is okay for `vma_addr`. + let vma = unsafe { bindings::vma_lookup(self.mm.as_raw(), vma_addr) }; + + if vma.is_null() { + None + } else { + // SAFETY: We just checked that a vma was found, so the pointer references a valid vma. + // + // Furthermore, the returned vma is still under the protection of the read lock guard + // and can be used while the mmap read lock is still held. That the vma is not used + // after the MmapReadGuard gets dropped is enforced by the borrow-checker. + unsafe { Some(virt::VmaRef::from_raw(vma)) } + } + } +} + impl Drop for MmapReadGuard<'_> { #[inline] fn drop(&mut self) { diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs new file mode 100644 index 000000000000..a66be649f0b8 --- /dev/null +++ b/rust/kernel/mm/virt.rs @@ -0,0 +1,210 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Virtual memory. +//! +//! This module deals with managing a single VMA in the address space of a userspace process. Each +//! VMA corresponds to a region of memory that the userspace process can access, and the VMA lets +//! you control what happens when userspace reads or writes to that region of memory. +//! +//! The module has several different Rust types that all correspond to the C type called +//! `vm_area_struct`. The different structs represent what kind of access you have to the VMA, e.g. +//! [`VmaRef`] is used when you hold the mmap or vma read lock. Using the appropriate struct +//! ensures that you can't, for example, accidentally call a function that requires holding the +//! write lock when you only hold the read lock. + +use crate::{bindings, mm::MmWithUser, types::Opaque}; + +/// A wrapper for the kernel's `struct vm_area_struct` with read access. +/// +/// It represents an area of virtual memory. +/// +/// # Invariants +/// +/// The caller must hold the mmap read lock or the vma read lock. +#[repr(transparent)] +pub struct VmaRef { + vma: Opaque, +} + +// Methods you can call when holding the mmap or vma read lock (or stronger). They must be usable +// no matter what the vma flags are. +impl VmaRef { + /// Access a virtual memory area given a raw pointer. + /// + /// # Safety + /// + /// Callers must ensure that `vma` is valid for the duration of 'a, and that the mmap or vma + /// read lock (or stronger) is held for at least the duration of 'a. + #[inline] + pub unsafe fn from_raw<'a>(vma: *const bindings::vm_area_struct) -> &'a Self { + // SAFETY: The caller ensures that the invariants are satisfied for the duration of 'a. + unsafe { &*vma.cast() } + } + + /// Returns a raw pointer to this area. + #[inline] + pub fn as_ptr(&self) -> *mut bindings::vm_area_struct { + self.vma.get() + } + + /// Access the underlying `mm_struct`. + #[inline] + pub fn mm(&self) -> &MmWithUser { + // SAFETY: By the type invariants, this `vm_area_struct` is valid and we hold the mmap/vma + // read lock or stronger. This implies that the underlying mm has a non-zero value of + // `mm_users`. + unsafe { MmWithUser::from_raw((*self.as_ptr()).vm_mm) } + } + + /// Returns the flags associated with the virtual memory area. + /// + /// The possible flags are a combination of the constants in [`flags`]. + #[inline] + pub fn flags(&self) -> vm_flags_t { + // SAFETY: By the type invariants, the caller holds at least the mmap read lock, so this + // access is not a data race. + unsafe { (*self.as_ptr()).__bindgen_anon_2.vm_flags } + } + + /// Returns the (inclusive) start address of the virtual memory area. + #[inline] + pub fn start(&self) -> usize { + // SAFETY: By the type invariants, the caller holds at least the mmap read lock, so this + // access is not a data race. + unsafe { (*self.as_ptr()).__bindgen_anon_1.__bindgen_anon_1.vm_start } + } + + /// Returns the (exclusive) end address of the virtual memory area. + #[inline] + pub fn end(&self) -> usize { + // SAFETY: By the type invariants, the caller holds at least the mmap read lock, so this + // access is not a data race. + unsafe { (*self.as_ptr()).__bindgen_anon_1.__bindgen_anon_1.vm_end } + } + + /// Zap pages in the given page range. + /// + /// This clears page table mappings for the range at the leaf level, leaving all other page + /// tables intact, and freeing any memory referenced by the VMA in this range. That is, + /// anonymous memory is completely freed, file-backed memory has its reference count on page + /// cache folio's dropped, any dirty data will still be written back to disk as usual. + /// + /// It may seem odd that we clear at the leaf level, this is however a product of the page + /// table structure used to map physical memory into a virtual address space - each virtual + /// address actually consists of a bitmap of array indices into page tables, which form a + /// hierarchical page table level structure. + /// + /// As a result, each page table level maps a multiple of page table levels below, and thus + /// span ever increasing ranges of pages. At the leaf or PTE level, we map the actual physical + /// memory. + /// + /// It is here where a zap operates, as it the only place we can be certain of clearing without + /// impacting any other virtual mappings. It is an implementation detail as to whether the + /// kernel goes further in freeing unused page tables, but for the purposes of this operation + /// we must only assume that the leaf level is cleared. + #[inline] + pub fn zap_page_range_single(&self, address: usize, size: usize) { + let (end, did_overflow) = address.overflowing_add(size); + if did_overflow || address < self.start() || self.end() < end { + // TODO: call WARN_ONCE once Rust version of it is added + return; + } + + // SAFETY: By the type invariants, the caller has read access to this VMA, which is + // sufficient for this method call. This method has no requirements on the vma flags. The + // address range is checked to be within the vma. + unsafe { + bindings::zap_page_range_single(self.as_ptr(), address, size, core::ptr::null_mut()) + }; + } +} + +/// The integer type used for vma flags. +#[doc(inline)] +pub use bindings::vm_flags_t; + +/// All possible flags for [`VmaRef`]. +pub mod flags { + use super::vm_flags_t; + use crate::bindings; + + /// No flags are set. + pub const NONE: vm_flags_t = bindings::VM_NONE as _; + + /// Mapping allows reads. + pub const READ: vm_flags_t = bindings::VM_READ as _; + + /// Mapping allows writes. + pub const WRITE: vm_flags_t = bindings::VM_WRITE as _; + + /// Mapping allows execution. + pub const EXEC: vm_flags_t = bindings::VM_EXEC as _; + + /// Mapping is shared. + pub const SHARED: vm_flags_t = bindings::VM_SHARED as _; + + /// Mapping may be updated to allow reads. + pub const MAYREAD: vm_flags_t = bindings::VM_MAYREAD as _; + + /// Mapping may be updated to allow writes. + pub const MAYWRITE: vm_flags_t = bindings::VM_MAYWRITE as _; + + /// Mapping may be updated to allow execution. + pub const MAYEXEC: vm_flags_t = bindings::VM_MAYEXEC as _; + + /// Mapping may be updated to be shared. + pub const MAYSHARE: vm_flags_t = bindings::VM_MAYSHARE as _; + + /// Page-ranges managed without `struct page`, just pure PFN. + pub const PFNMAP: vm_flags_t = bindings::VM_PFNMAP as _; + + /// Memory mapped I/O or similar. + pub const IO: vm_flags_t = bindings::VM_IO as _; + + /// Do not copy this vma on fork. + pub const DONTCOPY: vm_flags_t = bindings::VM_DONTCOPY as _; + + /// Cannot expand with mremap(). + pub const DONTEXPAND: vm_flags_t = bindings::VM_DONTEXPAND as _; + + /// Lock the pages covered when they are faulted in. + pub const LOCKONFAULT: vm_flags_t = bindings::VM_LOCKONFAULT as _; + + /// Is a VM accounted object. + pub const ACCOUNT: vm_flags_t = bindings::VM_ACCOUNT as _; + + /// Should the VM suppress accounting. + pub const NORESERVE: vm_flags_t = bindings::VM_NORESERVE as _; + + /// Huge TLB Page VM. + pub const HUGETLB: vm_flags_t = bindings::VM_HUGETLB as _; + + /// Synchronous page faults. (DAX-specific) + pub const SYNC: vm_flags_t = bindings::VM_SYNC as _; + + /// Architecture-specific flag. + pub const ARCH_1: vm_flags_t = bindings::VM_ARCH_1 as _; + + /// Wipe VMA contents in child on fork. + pub const WIPEONFORK: vm_flags_t = bindings::VM_WIPEONFORK as _; + + /// Do not include in the core dump. + pub const DONTDUMP: vm_flags_t = bindings::VM_DONTDUMP as _; + + /// Not soft dirty clean area. + pub const SOFTDIRTY: vm_flags_t = bindings::VM_SOFTDIRTY as _; + + /// Can contain `struct page` and pure PFN pages. + pub const MIXEDMAP: vm_flags_t = bindings::VM_MIXEDMAP as _; + + /// MADV_HUGEPAGE marked this vma. + pub const HUGEPAGE: vm_flags_t = bindings::VM_HUGEPAGE as _; + + /// MADV_NOHUGEPAGE marked this vma. + pub const NOHUGEPAGE: vm_flags_t = bindings::VM_NOHUGEPAGE as _; + + /// KSM may merge identical pages. + pub const MERGEABLE: vm_flags_t = bindings::VM_MERGEABLE as _; +} -- cgit v1.2.3 From bf3d331bb80749542cf299f94c471f611fb113b1 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:40 +0000 Subject: mm: rust: add vm_insert_page MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The vm_insert_page method is only usable on vmas with the VM_MIXEDMAP flag, so we introduce a new type to keep track of such vmas. The approach used in this patch assumes that we will not need to encode many flag combinations in the type. I don't think we need to encode more than VM_MIXEDMAP and VM_PFNMAP as things are now. However, if that becomes necessary, using generic parameters in a single type would scale better as the number of flags increases. Link: https://lkml.kernel.org/r/20250408-vma-v16-3-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: Jann Horn Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/mm/virt.rs | 79 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 78 insertions(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs index a66be649f0b8..3e2eabcc2145 100644 --- a/rust/kernel/mm/virt.rs +++ b/rust/kernel/mm/virt.rs @@ -14,7 +14,15 @@ //! ensures that you can't, for example, accidentally call a function that requires holding the //! write lock when you only hold the read lock. -use crate::{bindings, mm::MmWithUser, types::Opaque}; +use crate::{ + bindings, + error::{to_result, Result}, + mm::MmWithUser, + page::Page, + types::Opaque, +}; + +use core::ops::Deref; /// A wrapper for the kernel's `struct vm_area_struct` with read access. /// @@ -119,6 +127,75 @@ impl VmaRef { bindings::zap_page_range_single(self.as_ptr(), address, size, core::ptr::null_mut()) }; } + + /// If the [`VM_MIXEDMAP`] flag is set, returns a [`VmaMixedMap`] to this VMA, otherwise + /// returns `None`. + /// + /// This can be used to access methods that require [`VM_MIXEDMAP`] to be set. + /// + /// [`VM_MIXEDMAP`]: flags::MIXEDMAP + #[inline] + pub fn as_mixedmap_vma(&self) -> Option<&VmaMixedMap> { + if self.flags() & flags::MIXEDMAP != 0 { + // SAFETY: We just checked that `VM_MIXEDMAP` is set. All other requirements are + // satisfied by the type invariants of `VmaRef`. + Some(unsafe { VmaMixedMap::from_raw(self.as_ptr()) }) + } else { + None + } + } +} + +/// A wrapper for the kernel's `struct vm_area_struct` with read access and [`VM_MIXEDMAP`] set. +/// +/// It represents an area of virtual memory. +/// +/// This struct is identical to [`VmaRef`] except that it must only be used when the +/// [`VM_MIXEDMAP`] flag is set on the vma. +/// +/// # Invariants +/// +/// The caller must hold the mmap read lock or the vma read lock. The `VM_MIXEDMAP` flag must be +/// set. +/// +/// [`VM_MIXEDMAP`]: flags::MIXEDMAP +#[repr(transparent)] +pub struct VmaMixedMap { + vma: VmaRef, +} + +// Make all `VmaRef` methods available on `VmaMixedMap`. +impl Deref for VmaMixedMap { + type Target = VmaRef; + + #[inline] + fn deref(&self) -> &VmaRef { + &self.vma + } +} + +impl VmaMixedMap { + /// Access a virtual memory area given a raw pointer. + /// + /// # Safety + /// + /// Callers must ensure that `vma` is valid for the duration of 'a, and that the mmap read lock + /// (or stronger) is held for at least the duration of 'a. The `VM_MIXEDMAP` flag must be set. + #[inline] + pub unsafe fn from_raw<'a>(vma: *const bindings::vm_area_struct) -> &'a Self { + // SAFETY: The caller ensures that the invariants are satisfied for the duration of 'a. + unsafe { &*vma.cast() } + } + + /// Maps a single page at the given address within the virtual memory area. + /// + /// This operation does not take ownership of the page. + #[inline] + pub fn vm_insert_page(&self, address: usize, page: &Page) -> Result { + // SAFETY: By the type invariant of `Self` caller has read access and has verified that + // `VM_MIXEDMAP` is set. By invariant on `Page` the page has order 0. + to_result(unsafe { bindings::vm_insert_page(self.as_ptr(), address, page.as_ptr()) }) + } } /// The integer type used for vma flags. -- cgit v1.2.3 From 3105f8f391ce00153c553bfe89efbb30b120d858 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:41 +0000 Subject: mm: rust: add lock_vma_under_rcu MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, the binder driver always uses the mmap lock to make changes to its vma. Because the mmap lock is global to the process, this can involve significant contention. However, the kernel has a feature called per-vma locks, which can significantly reduce contention. For example, you can take a vma lock in parallel with an mmap write lock. This is important because contention on the mmap lock has been a long-term recurring challenge for the Binder driver. This patch introduces support for using `lock_vma_under_rcu` from Rust. The Rust Binder driver will be able to use this to reduce contention on the mmap lock. Link: https://lkml.kernel.org/r/20250408-vma-v16-4-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Jann Horn Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/mm.rs | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs index f1689ccb3740..c160fb52603f 100644 --- a/rust/kernel/mm.rs +++ b/rust/kernel/mm.rs @@ -19,6 +19,7 @@ use crate::{ use core::{ops::Deref, ptr::NonNull}; pub mod virt; +use virt::VmaRef; /// A wrapper for the kernel's `struct mm_struct`. /// @@ -161,6 +162,36 @@ impl MmWithUser { unsafe { &*ptr.cast() } } + /// Attempt to access a vma using the vma read lock. + /// + /// This is an optimistic trylock operation, so it may fail if there is contention. In that + /// case, you should fall back to taking the mmap read lock. + /// + /// When per-vma locks are disabled, this always returns `None`. + #[inline] + pub fn lock_vma_under_rcu(&self, vma_addr: usize) -> Option> { + #[cfg(CONFIG_PER_VMA_LOCK)] + { + // SAFETY: Calling `bindings::lock_vma_under_rcu` is always okay given an mm where + // `mm_users` is non-zero. + let vma = unsafe { bindings::lock_vma_under_rcu(self.as_raw(), vma_addr) }; + if !vma.is_null() { + return Some(VmaReadGuard { + // SAFETY: If `lock_vma_under_rcu` returns a non-null ptr, then it points at a + // valid vma. The vma is stable for as long as the vma read lock is held. + vma: unsafe { VmaRef::from_raw(vma) }, + _nts: NotThreadSafe, + }); + } + } + + // Silence warnings about unused variables. + #[cfg(not(CONFIG_PER_VMA_LOCK))] + let _ = vma_addr; + + None + } + /// Lock the mmap read lock. #[inline] pub fn mmap_read_lock(&self) -> MmapReadGuard<'_> { @@ -231,3 +262,32 @@ impl Drop for MmapReadGuard<'_> { unsafe { bindings::mmap_read_unlock(self.mm.as_raw()) }; } } + +/// A guard for the vma read lock. +/// +/// # Invariants +/// +/// This `VmaReadGuard` guard owns the vma read lock. +pub struct VmaReadGuard<'a> { + vma: &'a VmaRef, + // `vma_end_read` must be called on the same thread as where the lock was taken + _nts: NotThreadSafe, +} + +// Make all `VmaRef` methods available on `VmaReadGuard`. +impl Deref for VmaReadGuard<'_> { + type Target = VmaRef; + + #[inline] + fn deref(&self) -> &VmaRef { + self.vma + } +} + +impl Drop for VmaReadGuard<'_> { + #[inline] + fn drop(&mut self) { + // SAFETY: We hold the read lock by the type invariants. + unsafe { bindings::vma_end_read(self.vma.as_ptr()) }; + } +} -- cgit v1.2.3 From 114ba9b9e8191925438365089c0d300f4f1b6fb1 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:42 +0000 Subject: mm: rust: add mmput_async support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Adds an MmWithUserAsync type that uses mmput_async when dropped but is otherwise identical to MmWithUser. This has to be done using a separate type because the thing we are changing is the destructor. Rust Binder needs this to avoid a certain deadlock. See commit 9a9ab0d96362 ("binder: fix race between mmput() and do_exit()") for details. It's also needed in the shrinker to avoid cleaning up the mm in the shrinker's context. Link: https://lkml.kernel.org/r/20250408-vma-v16-5-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: Jann Horn Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/mm.rs | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs index c160fb52603f..615907a0f3b4 100644 --- a/rust/kernel/mm.rs +++ b/rust/kernel/mm.rs @@ -111,6 +111,50 @@ impl Deref for MmWithUser { } } +/// A wrapper for the kernel's `struct mm_struct`. +/// +/// This type is identical to `MmWithUser` except that it uses `mmput_async` when dropping a +/// refcount. This means that the destructor of `ARef` is safe to call in atomic +/// context. +/// +/// # Invariants +/// +/// Values of this type are always refcounted using `mmget`. The value of `mm_users` is non-zero. +#[repr(transparent)] +pub struct MmWithUserAsync { + mm: MmWithUser, +} + +// SAFETY: It is safe to call `mmput_async` on another thread than where `mmget` was called. +unsafe impl Send for MmWithUserAsync {} +// SAFETY: All methods on `MmWithUserAsync` can be called in parallel from several threads. +unsafe impl Sync for MmWithUserAsync {} + +// SAFETY: By the type invariants, this type is always refcounted. +unsafe impl AlwaysRefCounted for MmWithUserAsync { + #[inline] + fn inc_ref(&self) { + // SAFETY: The pointer is valid since self is a reference. + unsafe { bindings::mmget(self.as_raw()) }; + } + + #[inline] + unsafe fn dec_ref(obj: NonNull) { + // SAFETY: The caller is giving up their refcount. + unsafe { bindings::mmput_async(obj.cast().as_ptr()) }; + } +} + +// Make all `MmWithUser` methods available on `MmWithUserAsync`. +impl Deref for MmWithUserAsync { + type Target = MmWithUser; + + #[inline] + fn deref(&self) -> &MmWithUser { + &self.mm + } +} + // These methods are safe to call even if `mm_users` is zero. impl Mm { /// Returns a raw pointer to the inner `mm_struct`. @@ -162,6 +206,13 @@ impl MmWithUser { unsafe { &*ptr.cast() } } + /// Use `mmput_async` when dropping this refcount. + #[inline] + pub fn into_mmput_async(me: ARef) -> ARef { + // SAFETY: The layouts and invariants are compatible. + unsafe { ARef::from_raw(ARef::into_raw(me).cast()) } + } + /// Attempt to access a vma using the vma read lock. /// /// This is an optimistic trylock operation, so it may fail if there is contention. In that -- cgit v1.2.3 From dcb81aeab406e417bc0b4cf68de6eb07a1d2e6ce Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:43 +0000 Subject: mm: rust: add VmaNew for f_ops->mmap() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This type will be used when setting up a new vma in an f_ops->mmap() hook. Using a separate type from VmaRef allows us to have a separate set of operations that you are only able to use during the mmap() hook. For example, the VM_MIXEDMAP flag must not be changed after the initial setup that happens during the f_ops->mmap() hook. To avoid setting invalid flag values, the methods for clearing VM_MAYWRITE and similar involve a check of VM_WRITE, and return an error if VM_WRITE is set. Trying to use `try_clear_maywrite` without checking the return value results in a compilation error because the `Result` type is marked #[must_use]. For now, there's only a method for VM_MIXEDMAP and not VM_PFNMAP. When we add a VM_PFNMAP method, we will need some way to prevent you from setting both VM_MIXEDMAP and VM_PFNMAP on the same vma. Link: https://lkml.kernel.org/r/20250408-vma-v16-6-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Jann Horn Reviewed-by: Andreas Hindborg Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Gary Guo Cc: Greg Kroah-Hartman Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/mm/virt.rs | 186 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 185 insertions(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs index 3e2eabcc2145..31803674aecc 100644 --- a/rust/kernel/mm/virt.rs +++ b/rust/kernel/mm/virt.rs @@ -16,7 +16,7 @@ use crate::{ bindings, - error::{to_result, Result}, + error::{code::EINVAL, to_result, Result}, mm::MmWithUser, page::Page, types::Opaque, @@ -198,6 +198,190 @@ impl VmaMixedMap { } } +/// A configuration object for setting up a VMA in an `f_ops->mmap()` hook. +/// +/// The `f_ops->mmap()` hook is called when a new VMA is being created, and the hook is able to +/// configure the VMA in various ways to fit the driver that owns it. Using `VmaNew` indicates that +/// you are allowed to perform operations on the VMA that can only be performed before the VMA is +/// fully initialized. +/// +/// # Invariants +/// +/// For the duration of 'a, the referenced vma must be undergoing initialization in an +/// `f_ops->mmap()` hook. +pub struct VmaNew { + vma: VmaRef, +} + +// Make all `VmaRef` methods available on `VmaNew`. +impl Deref for VmaNew { + type Target = VmaRef; + + #[inline] + fn deref(&self) -> &VmaRef { + &self.vma + } +} + +impl VmaNew { + /// Access a virtual memory area given a raw pointer. + /// + /// # Safety + /// + /// Callers must ensure that `vma` is undergoing initial vma setup for the duration of 'a. + #[inline] + pub unsafe fn from_raw<'a>(vma: *mut bindings::vm_area_struct) -> &'a Self { + // SAFETY: The caller ensures that the invariants are satisfied for the duration of 'a. + unsafe { &*vma.cast() } + } + + /// Internal method for updating the vma flags. + /// + /// # Safety + /// + /// This must not be used to set the flags to an invalid value. + #[inline] + unsafe fn update_flags(&self, set: vm_flags_t, unset: vm_flags_t) { + let mut flags = self.flags(); + flags |= set; + flags &= !unset; + + // SAFETY: This is not a data race: the vma is undergoing initial setup, so it's not yet + // shared. Additionally, `VmaNew` is `!Sync`, so it cannot be used to write in parallel. + // The caller promises that this does not set the flags to an invalid value. + unsafe { (*self.as_ptr()).__bindgen_anon_2.__vm_flags = flags }; + } + + /// Set the `VM_MIXEDMAP` flag on this vma. + /// + /// This enables the vma to contain both `struct page` and pure PFN pages. Returns a reference + /// that can be used to call `vm_insert_page` on the vma. + #[inline] + pub fn set_mixedmap(&self) -> &VmaMixedMap { + // SAFETY: We don't yet provide a way to set VM_PFNMAP, so this cannot put the flags in an + // invalid state. + unsafe { self.update_flags(flags::MIXEDMAP, 0) }; + + // SAFETY: We just set `VM_MIXEDMAP` on the vma. + unsafe { VmaMixedMap::from_raw(self.vma.as_ptr()) } + } + + /// Set the `VM_IO` flag on this vma. + /// + /// This is used for memory mapped IO and similar. The flag tells other parts of the kernel to + /// avoid looking at the pages. For memory mapped IO this is useful as accesses to the pages + /// could have side effects. + #[inline] + pub fn set_io(&self) { + // SAFETY: Setting the VM_IO flag is always okay. + unsafe { self.update_flags(flags::IO, 0) }; + } + + /// Set the `VM_DONTEXPAND` flag on this vma. + /// + /// This prevents the vma from being expanded with `mremap()`. + #[inline] + pub fn set_dontexpand(&self) { + // SAFETY: Setting the VM_DONTEXPAND flag is always okay. + unsafe { self.update_flags(flags::DONTEXPAND, 0) }; + } + + /// Set the `VM_DONTCOPY` flag on this vma. + /// + /// This prevents the vma from being copied on fork. This option is only permanent if `VM_IO` + /// is set. + #[inline] + pub fn set_dontcopy(&self) { + // SAFETY: Setting the VM_DONTCOPY flag is always okay. + unsafe { self.update_flags(flags::DONTCOPY, 0) }; + } + + /// Set the `VM_DONTDUMP` flag on this vma. + /// + /// This prevents the vma from being included in core dumps. This option is only permanent if + /// `VM_IO` is set. + #[inline] + pub fn set_dontdump(&self) { + // SAFETY: Setting the VM_DONTDUMP flag is always okay. + unsafe { self.update_flags(flags::DONTDUMP, 0) }; + } + + /// Returns whether `VM_READ` is set. + /// + /// This flag indicates whether userspace is mapping this vma as readable. + #[inline] + pub fn readable(&self) -> bool { + (self.flags() & flags::READ) != 0 + } + + /// Try to clear the `VM_MAYREAD` flag, failing if `VM_READ` is set. + /// + /// This flag indicates whether userspace is allowed to make this vma readable with + /// `mprotect()`. + /// + /// Note that this operation is irreversible. Once `VM_MAYREAD` has been cleared, it can never + /// be set again. + #[inline] + pub fn try_clear_mayread(&self) -> Result { + if self.readable() { + return Err(EINVAL); + } + // SAFETY: Clearing `VM_MAYREAD` is okay when `VM_READ` is not set. + unsafe { self.update_flags(0, flags::MAYREAD) }; + Ok(()) + } + + /// Returns whether `VM_WRITE` is set. + /// + /// This flag indicates whether userspace is mapping this vma as writable. + #[inline] + pub fn writable(&self) -> bool { + (self.flags() & flags::WRITE) != 0 + } + + /// Try to clear the `VM_MAYWRITE` flag, failing if `VM_WRITE` is set. + /// + /// This flag indicates whether userspace is allowed to make this vma writable with + /// `mprotect()`. + /// + /// Note that this operation is irreversible. Once `VM_MAYWRITE` has been cleared, it can never + /// be set again. + #[inline] + pub fn try_clear_maywrite(&self) -> Result { + if self.writable() { + return Err(EINVAL); + } + // SAFETY: Clearing `VM_MAYWRITE` is okay when `VM_WRITE` is not set. + unsafe { self.update_flags(0, flags::MAYWRITE) }; + Ok(()) + } + + /// Returns whether `VM_EXEC` is set. + /// + /// This flag indicates whether userspace is mapping this vma as executable. + #[inline] + pub fn executable(&self) -> bool { + (self.flags() & flags::EXEC) != 0 + } + + /// Try to clear the `VM_MAYEXEC` flag, failing if `VM_EXEC` is set. + /// + /// This flag indicates whether userspace is allowed to make this vma executable with + /// `mprotect()`. + /// + /// Note that this operation is irreversible. Once `VM_MAYEXEC` has been cleared, it can never + /// be set again. + #[inline] + pub fn try_clear_mayexec(&self) -> Result { + if self.executable() { + return Err(EINVAL); + } + // SAFETY: Clearing `VM_MAYEXEC` is okay when `VM_EXEC` is not set. + unsafe { self.update_flags(0, flags::MAYEXEC) }; + Ok(()) + } +} + /// The integer type used for vma flags. #[doc(inline)] pub use bindings::vm_flags_t; -- cgit v1.2.3 From f8c78198816f04619da6eebfc5b67741bff56325 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:44 +0000 Subject: rust: miscdevice: add mmap support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add the ability to write a file_operations->mmap hook in Rust when using the miscdevice abstraction. The `vma` argument to the `mmap` hook uses the `VmaNew` type from the previous commit; this type provides the correct set of operations for a file_operations->mmap hook. Link: https://lkml.kernel.org/r/20250408-vma-v16-7-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Greg Kroah-Hartman Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Jann Horn Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/miscdevice.rs | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index fa9ecc42602a..9d9771247c38 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -14,6 +14,7 @@ use crate::{ error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR}, ffi::{c_int, c_long, c_uint, c_ulong}, fs::File, + mm::virt::VmaNew, prelude::*, seq_file::SeqFile, str::CStr, @@ -119,6 +120,22 @@ pub trait MiscDevice: Sized { drop(device); } + /// Handle for mmap. + /// + /// This function is invoked when a user space process invokes the `mmap` system call on + /// `file`. The function is a callback that is part of the VMA initializer. The kernel will do + /// initial setup of the VMA before calling this function. The function can then interact with + /// the VMA initialization by calling methods of `vma`. If the function does not return an + /// error, the kernel will complete initialization of the VMA according to the properties of + /// `vma`. + fn mmap( + _device: ::Borrowed<'_>, + _file: &File, + _vma: &VmaNew, + ) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + /// Handler for ioctls. /// /// The `cmd` argument is usually manipulated using the utilties in [`kernel::ioctl`]. @@ -223,6 +240,33 @@ impl MiscdeviceVTable { 0 } + /// # Safety + /// + /// `file` must be a valid file that is associated with a `MiscDeviceRegistration`. + /// `vma` must be a vma that is currently being mmap'ed with this file. + unsafe extern "C" fn mmap( + file: *mut bindings::file, + vma: *mut bindings::vm_area_struct, + ) -> c_int { + // SAFETY: The mmap call of a file can access the private data. + let private = unsafe { (*file).private_data }; + // SAFETY: This is a Rust Miscdevice, so we call `into_foreign` in `open` and + // `from_foreign` in `release`, and `fops_mmap` is guaranteed to be called between those + // two operations. + let device = unsafe { ::borrow(private) }; + // SAFETY: The caller provides a vma that is undergoing initial VMA setup. + let area = unsafe { VmaNew::from_raw(vma) }; + // SAFETY: + // * The file is valid for the duration of this call. + // * There is no active fdget_pos region on the file on this thread. + let file = unsafe { File::from_raw_file(file) }; + + match T::mmap(device, file, area) { + Ok(()) => 0, + Err(err) => err.to_errno(), + } + } + /// # Safety /// /// `file` must be a valid file that is associated with a `MiscDeviceRegistration`. @@ -291,6 +335,7 @@ impl MiscdeviceVTable { const VTABLE: bindings::file_operations = bindings::file_operations { open: Some(Self::open), release: Some(Self::release), + mmap: if T::HAS_MMAP { Some(Self::mmap) } else { None }, unlocked_ioctl: if T::HAS_IOCTL { Some(Self::ioctl) } else { -- cgit v1.2.3 From 6acb75ad7b9e1548ae7f7532312295f74e48c973 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 8 Apr 2025 09:22:45 +0000 Subject: task: rust: rework how current is accessed MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Introduce a new type called `CurrentTask` that lets you perform various operations that are only safe on the `current` task. Use the new type to provide a way to access the current mm without incrementing its refcount. With this change, you can write stuff such as let vma = current!().mm().lock_vma_under_rcu(addr); without incrementing any refcounts. This replaces the existing abstractions for accessing the current pid namespace. With the old approach, every field access to current involves both a macro and a unsafe helper function. The new approach simplifies that to a single safe function on the `CurrentTask` type. This makes it less heavy-weight to add additional current accessors in the future. That said, creating a `CurrentTask` type like the one in this patch requires that we are careful to ensure that it cannot escape the current task or otherwise access things after they are freed. To do this, I declared that it cannot escape the current "task context" where I defined a "task context" as essentially the region in which `current` remains unchanged. So e.g., release_task() or begin_new_exec() would leave the task context. If a userspace thread returns to userspace and later makes another syscall, then I consider the two syscalls to be different task contexts. This allows values stored in that task to be modified between syscalls, even if they're guaranteed to be immutable during a syscall. Ensuring correctness of `CurrentTask` is slightly tricky if we also want the ability to have a safe `kthread_use_mm()` implementation in Rust. To support that safely, there are two patterns we need to ensure are safe: // Case 1: current!() called inside the scope. let mm; kthread_use_mm(some_mm, || { mm = current!().mm(); }); drop(some_mm); mm.do_something(); // UAF and: // Case 2: current!() called before the scope. let mm; let task = current!(); kthread_use_mm(some_mm, || { mm = task.mm(); }); drop(some_mm); mm.do_something(); // UAF The existing `current!()` abstraction already natively prevents the first case: The `&CurrentTask` would be tied to the inner scope, so the borrow-checker ensures that no reference derived from it can escape the scope. Fixing the second case is a bit more tricky. The solution is to essentially pretend that the contents of the scope execute on an different thread, which means that only thread-safe types can cross the boundary. Since `CurrentTask` is marked `NotThreadSafe`, attempts to move it to another thread will fail, and this includes our fake pretend thread boundary. This has the disadvantage that other types that aren't thread-safe for reasons unrelated to `current` also cannot be moved across the `kthread_use_mm()` boundary. I consider this an acceptable tradeoff. Link: https://lkml.kernel.org/r/20250408-vma-v16-8-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Boqun Feng Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Greg Kroah-Hartman Cc: Jann Horn Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- rust/kernel/task.rs | 247 +++++++++++++++++++++++++++------------------------- 1 file changed, 129 insertions(+), 118 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index 9e6f6854948d..927413d85484 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -7,6 +7,7 @@ use crate::{ bindings, ffi::{c_int, c_long, c_uint}, + mm::MmWithUser, pid_namespace::PidNamespace, types::{ARef, NotThreadSafe, Opaque}, }; @@ -33,22 +34,20 @@ pub const TASK_NORMAL: c_uint = bindings::TASK_NORMAL as c_uint; #[macro_export] macro_rules! current { () => { - // SAFETY: Deref + addr-of below create a temporary `TaskRef` that cannot outlive the - // caller. + // SAFETY: This expression creates a temporary value that is dropped at the end of the + // caller's scope. The following mechanisms ensure that the resulting `&CurrentTask` cannot + // leave current task context: + // + // * To return to userspace, the caller must leave the current scope. + // * Operations such as `begin_new_exec()` are necessarily unsafe and the caller of + // `begin_new_exec()` is responsible for safety. + // * Rust abstractions for things such as a `kthread_use_mm()` scope must require the + // closure to be `Send`, so the `NotThreadSafe` field of `CurrentTask` ensures that the + // `&CurrentTask` cannot cross the scope in either direction. unsafe { &*$crate::task::Task::current() } }; } -/// Returns the currently running task's pid namespace. -#[macro_export] -macro_rules! current_pid_ns { - () => { - // SAFETY: Deref + addr-of below create a temporary `PidNamespaceRef` that cannot outlive - // the caller. - unsafe { &*$crate::task::Task::current_pid_ns() } - }; -} - /// Wraps the kernel's `struct task_struct`. /// /// # Invariants @@ -87,7 +86,7 @@ macro_rules! current_pid_ns { /// impl State { /// fn new() -> Self { /// Self { -/// creator: current!().into(), +/// creator: ARef::from(&**current!()), /// index: 0, /// } /// } @@ -107,6 +106,44 @@ unsafe impl Send for Task {} // synchronised by C code (e.g., `signal_pending`). unsafe impl Sync for Task {} +/// Represents the [`Task`] in the `current` global. +/// +/// This type exists to provide more efficient operations that are only valid on the current task. +/// For example, to retrieve the pid-namespace of a task, you must use rcu protection unless it is +/// the current task. +/// +/// # Invariants +/// +/// Each value of this type must only be accessed from the task context it was created within. +/// +/// Of course, every thread is in a different task context, but for the purposes of this invariant, +/// these operations also permanently leave the task context: +/// +/// * Returning to userspace from system call context. +/// * Calling `release_task()`. +/// * Calling `begin_new_exec()` in a binary format loader. +/// +/// Other operations temporarily create a new sub-context: +/// +/// * Calling `kthread_use_mm()` creates a new context, and `kthread_unuse_mm()` returns to the +/// old context. +/// +/// This means that a `CurrentTask` obtained before a `kthread_use_mm()` call may be used again +/// once `kthread_unuse_mm()` is called, but it must not be used between these two calls. +/// Conversely, a `CurrentTask` obtained between a `kthread_use_mm()`/`kthread_unuse_mm()` pair +/// must not be used after `kthread_unuse_mm()`. +#[repr(transparent)] +pub struct CurrentTask(Task, NotThreadSafe); + +// Make all `Task` methods available on `CurrentTask`. +impl Deref for CurrentTask { + type Target = Task; + #[inline] + fn deref(&self) -> &Task { + &self.0 + } +} + /// The type of process identifiers (PIDs). pub type Pid = bindings::pid_t; @@ -133,119 +170,29 @@ impl Task { /// /// # Safety /// - /// Callers must ensure that the returned object doesn't outlive the current task/thread. - pub unsafe fn current() -> impl Deref { - struct TaskRef<'a> { - task: &'a Task, - _not_send: NotThreadSafe, + /// Callers must ensure that the returned object is only used to access a [`CurrentTask`] + /// within the task context that was active when this function was called. For more details, + /// see the invariants section for [`CurrentTask`]. + pub unsafe fn current() -> impl Deref { + struct TaskRef { + task: *const CurrentTask, } - impl Deref for TaskRef<'_> { - type Target = Task; + impl Deref for TaskRef { + type Target = CurrentTask; fn deref(&self) -> &Self::Target { - self.task + // SAFETY: The returned reference borrows from this `TaskRef`, so it cannot outlive + // the `TaskRef`, which the caller of `Task::current()` has promised will not + // outlive the task/thread for which `self.task` is the `current` pointer. Thus, it + // is okay to return a `CurrentTask` reference here. + unsafe { &*self.task } } } - let current = Task::current_raw(); TaskRef { - // SAFETY: If the current thread is still running, the current task is valid. Given - // that `TaskRef` is not `Send`, we know it cannot be transferred to another thread - // (where it could potentially outlive the caller). - task: unsafe { &*current.cast() }, - _not_send: NotThreadSafe, - } - } - - /// Returns a PidNamespace reference for the currently executing task's/thread's pid namespace. - /// - /// This function can be used to create an unbounded lifetime by e.g., storing the returned - /// PidNamespace in a global variable which would be a bug. So the recommended way to get the - /// current task's/thread's pid namespace is to use the [`current_pid_ns`] macro because it is - /// safe. - /// - /// # Safety - /// - /// Callers must ensure that the returned object doesn't outlive the current task/thread. - pub unsafe fn current_pid_ns() -> impl Deref { - struct PidNamespaceRef<'a> { - task: &'a PidNamespace, - _not_send: NotThreadSafe, - } - - impl Deref for PidNamespaceRef<'_> { - type Target = PidNamespace; - - fn deref(&self) -> &Self::Target { - self.task - } - } - - // The lifetime of `PidNamespace` is bound to `Task` and `struct pid`. - // - // The `PidNamespace` of a `Task` doesn't ever change once the `Task` is alive. A - // `unshare(CLONE_NEWPID)` or `setns(fd_pidns/pidfd, CLONE_NEWPID)` will not have an effect - // on the calling `Task`'s pid namespace. It will only effect the pid namespace of children - // created by the calling `Task`. This invariant guarantees that after having acquired a - // reference to a `Task`'s pid namespace it will remain unchanged. - // - // When a task has exited and been reaped `release_task()` will be called. This will set - // the `PidNamespace` of the task to `NULL`. So retrieving the `PidNamespace` of a task - // that is dead will return `NULL`. Note, that neither holding the RCU lock nor holding a - // referencing count to - // the `Task` will prevent `release_task()` being called. - // - // In order to retrieve the `PidNamespace` of a `Task` the `task_active_pid_ns()` function - // can be used. There are two cases to consider: - // - // (1) retrieving the `PidNamespace` of the `current` task - // (2) retrieving the `PidNamespace` of a non-`current` task - // - // From system call context retrieving the `PidNamespace` for case (1) is always safe and - // requires neither RCU locking nor a reference count to be held. Retrieving the - // `PidNamespace` after `release_task()` for current will return `NULL` but no codepath - // like that is exposed to Rust. - // - // Retrieving the `PidNamespace` from system call context for (2) requires RCU protection. - // Accessing `PidNamespace` outside of RCU protection requires a reference count that - // must've been acquired while holding the RCU lock. Note that accessing a non-`current` - // task means `NULL` can be returned as the non-`current` task could have already passed - // through `release_task()`. - // - // To retrieve (1) the `current_pid_ns!()` macro should be used which ensure that the - // returned `PidNamespace` cannot outlive the calling scope. The associated - // `current_pid_ns()` function should not be called directly as it could be abused to - // created an unbounded lifetime for `PidNamespace`. The `current_pid_ns!()` macro allows - // Rust to handle the common case of accessing `current`'s `PidNamespace` without RCU - // protection and without having to acquire a reference count. - // - // For (2) the `task_get_pid_ns()` method must be used. This will always acquire a - // reference on `PidNamespace` and will return an `Option` to force the caller to - // explicitly handle the case where `PidNamespace` is `None`, something that tends to be - // forgotten when doing the equivalent operation in `C`. Missing RCU primitives make it - // difficult to perform operations that are otherwise safe without holding a reference - // count as long as RCU protection is guaranteed. But it is not important currently. But we - // do want it in the future. - // - // Note for (2) the required RCU protection around calling `task_active_pid_ns()` - // synchronizes against putting the last reference of the associated `struct pid` of - // `task->thread_pid`. The `struct pid` stored in that field is used to retrieve the - // `PidNamespace` of the caller. When `release_task()` is called `task->thread_pid` will be - // `NULL`ed and `put_pid()` on said `struct pid` will be delayed in `free_pid()` via - // `call_rcu()` allowing everyone with an RCU protected access to the `struct pid` acquired - // from `task->thread_pid` to finish. - // - // SAFETY: The current task's pid namespace is valid as long as the current task is running. - let pidns = unsafe { bindings::task_active_pid_ns(Task::current_raw()) }; - PidNamespaceRef { - // SAFETY: If the current thread is still running, the current task and its associated - // pid namespace are valid. `PidNamespaceRef` is not `Send`, so we know it cannot be - // transferred to another thread (where it could potentially outlive the current - // `Task`). The caller needs to ensure that the PidNamespaceRef doesn't outlive the - // current task/thread. - task: unsafe { PidNamespace::from_ptr(pidns) }, - _not_send: NotThreadSafe, + // CAST: The layout of `struct task_struct` and `CurrentTask` is identical. + task: Task::current_raw().cast(), } } @@ -328,6 +275,70 @@ impl Task { } } +impl CurrentTask { + /// Access the address space of the current task. + /// + /// This function does not touch the refcount of the mm. + #[inline] + pub fn mm(&self) -> Option<&MmWithUser> { + // SAFETY: The `mm` field of `current` is not modified from other threads, so reading it is + // not a data race. + let mm = unsafe { (*self.as_ptr()).mm }; + + if mm.is_null() { + return None; + } + + // SAFETY: If `current->mm` is non-null, then it references a valid mm with a non-zero + // value of `mm_users`. Furthermore, the returned `&MmWithUser` borrows from this + // `CurrentTask`, so it cannot escape the scope in which the current pointer was obtained. + // + // This is safe even if `kthread_use_mm()`/`kthread_unuse_mm()` are used. There are two + // relevant cases: + // * If the `&CurrentTask` was created before `kthread_use_mm()`, then it cannot be + // accessed during the `kthread_use_mm()`/`kthread_unuse_mm()` scope due to the + // `NotThreadSafe` field of `CurrentTask`. + // * If the `&CurrentTask` was created within a `kthread_use_mm()`/`kthread_unuse_mm()` + // scope, then the `&CurrentTask` cannot escape that scope, so the returned `&MmWithUser` + // also cannot escape that scope. + // In either case, it's not possible to read `current->mm` and keep using it after the + // scope is ended with `kthread_unuse_mm()`. + Some(unsafe { MmWithUser::from_raw(mm) }) + } + + /// Access the pid namespace of the current task. + /// + /// This function does not touch the refcount of the namespace or use RCU protection. + /// + /// To access the pid namespace of another task, see [`Task::get_pid_ns`]. + #[doc(alias = "task_active_pid_ns")] + #[inline] + pub fn active_pid_ns(&self) -> Option<&PidNamespace> { + // SAFETY: It is safe to call `task_active_pid_ns` without RCU protection when calling it + // on the current task. + let active_ns = unsafe { bindings::task_active_pid_ns(self.as_ptr()) }; + + if active_ns.is_null() { + return None; + } + + // The lifetime of `PidNamespace` is bound to `Task` and `struct pid`. + // + // The `PidNamespace` of a `Task` doesn't ever change once the `Task` is alive. + // + // From system call context retrieving the `PidNamespace` for the current task is always + // safe and requires neither RCU locking nor a reference count to be held. Retrieving the + // `PidNamespace` after `release_task()` for current will return `NULL` but no codepath + // like that is exposed to Rust. + // + // SAFETY: If `current`'s pid ns is non-null, then it references a valid pid ns. + // Furthermore, the returned `&PidNamespace` borrows from this `CurrentTask`, so it cannot + // escape the scope in which the current pointer was obtained, e.g. it cannot live past a + // `release_task()` call. + Some(unsafe { PidNamespace::from_ptr(active_ns) }) + } +} + // SAFETY: The type invariants guarantee that `Task` is always refcounted. unsafe impl crate::types::AlwaysRefCounted for Task { fn inc_ref(&self) { -- cgit v1.2.3 From 446cafc295bfc0e89da94a482fe8290bd8b429fb Mon Sep 17 00:00:00 2001 From: Andreas Hindborg Date: Thu, 8 May 2025 10:52:09 +0200 Subject: rust: configfs: introduce rust support for configfs Add a Rust API for configfs, thus allowing Rust modules to use configfs for configuration. Make the implementation a shim on top of the C configfs implementation, allowing safe use of the C infrastructure from Rust. Link: https://lore.kernel.org/r/20250508-configfs-v8-1-8ebde6180edc@kernel.org Signed-off-by: Andreas Hindborg --- rust/kernel/configfs.rs | 1049 +++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 + 2 files changed, 1051 insertions(+) create mode 100644 rust/kernel/configfs.rs (limited to 'rust/kernel') diff --git a/rust/kernel/configfs.rs b/rust/kernel/configfs.rs new file mode 100644 index 000000000000..b93ac7b0bebc --- /dev/null +++ b/rust/kernel/configfs.rs @@ -0,0 +1,1049 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! configfs interface: Userspace-driven Kernel Object Configuration +//! +//! configfs is an in-memory pseudo file system for configuration of kernel +//! modules. Please see the [C documentation] for details and intended use of +//! configfs. +//! +//! This module does not support the following configfs features: +//! +//! - Items. All group children are groups. +//! - Symlink support. +//! - `disconnect_notify` hook. +//! - Default groups. +//! +//! See the [`rust_configfs.rs`] sample for a full example use of this module. +//! +//! C header: [`include/linux/configfs.h`](srctree/include/linux/configfs.h) +//! +//! # Example +//! +//! ```ignore +//! use kernel::alloc::flags; +//! use kernel::c_str; +//! use kernel::configfs_attrs; +//! use kernel::configfs; +//! use kernel::new_mutex; +//! use kernel::page::PAGE_SIZE; +//! use kernel::sync::Mutex; +//! use kernel::ThisModule; +//! +//! #[pin_data] +//! struct RustConfigfs { +//! #[pin] +//! config: configfs::Subsystem, +//! } +//! +//! impl kernel::InPlaceModule for RustConfigfs { +//! fn init(_module: &'static ThisModule) -> impl PinInit { +//! pr_info!("Rust configfs sample (init)\n"); +//! +//! let item_type = configfs_attrs! { +//! container: configfs::Subsystem, +//! data: Configuration, +//! attributes: [ +//! message: 0, +//! bar: 1, +//! ], +//! }; +//! +//! try_pin_init!(Self { +//! config <- configfs::Subsystem::new( +//! c_str!("rust_configfs"), item_type, Configuration::new() +//! ), +//! }) +//! } +//! } +//! +//! #[pin_data] +//! struct Configuration { +//! message: &'static CStr, +//! #[pin] +//! bar: Mutex<(KBox<[u8; PAGE_SIZE]>, usize)>, +//! } +//! +//! impl Configuration { +//! fn new() -> impl PinInit { +//! try_pin_init!(Self { +//! message: c_str!("Hello World\n"), +//! bar <- new_mutex!((KBox::new([0; PAGE_SIZE], flags::GFP_KERNEL)?, 0)), +//! }) +//! } +//! } +//! +//! #[vtable] +//! impl configfs::AttributeOperations<0> for Configuration { +//! type Data = Configuration; +//! +//! fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result { +//! pr_info!("Show message\n"); +//! let data = container.message; +//! page[0..data.len()].copy_from_slice(data); +//! Ok(data.len()) +//! } +//! } +//! +//! #[vtable] +//! impl configfs::AttributeOperations<1> for Configuration { +//! type Data = Configuration; +//! +//! fn show(container: &Configuration, page: &mut [u8; PAGE_SIZE]) -> Result { +//! pr_info!("Show bar\n"); +//! let guard = container.bar.lock(); +//! let data = guard.0.as_slice(); +//! let len = guard.1; +//! page[0..len].copy_from_slice(&data[0..len]); +//! Ok(len) +//! } +//! +//! fn store(container: &Configuration, page: &[u8]) -> Result { +//! pr_info!("Store bar\n"); +//! let mut guard = container.bar.lock(); +//! guard.0[0..page.len()].copy_from_slice(page); +//! guard.1 = page.len(); +//! Ok(()) +//! } +//! } +//! ``` +//! +//! [C documentation]: srctree/Documentation/filesystems/configfs.rst +//! [`rust_configfs.rs`]: srctree/samples/rust/rust_configfs.rs + +use crate::alloc::flags; +use crate::container_of; +use crate::page::PAGE_SIZE; +use crate::prelude::*; +use crate::str::CString; +use crate::sync::Arc; +use crate::sync::ArcBorrow; +use crate::types::Opaque; +use core::cell::UnsafeCell; +use core::marker::PhantomData; + +/// A configfs subsystem. +/// +/// This is the top level entrypoint for a configfs hierarchy. To register +/// with configfs, embed a field of this type into your kernel module struct. +#[pin_data(PinnedDrop)] +pub struct Subsystem { + #[pin] + subsystem: Opaque, + #[pin] + data: Data, +} + +// SAFETY: We do not provide any operations on `Subsystem`. +unsafe impl Sync for Subsystem {} + +// SAFETY: Ownership of `Subsystem` can safely be transferred to other threads. +unsafe impl Send for Subsystem {} + +impl Subsystem { + /// Create an initializer for a [`Subsystem`]. + /// + /// The subsystem will appear in configfs as a directory name given by + /// `name`. The attributes available in directory are specified by + /// `item_type`. + pub fn new( + name: &'static CStr, + item_type: &'static ItemType, Data>, + data: impl PinInit, + ) -> impl PinInit { + try_pin_init!(Self { + subsystem <- pin_init::zeroed().chain( + |place: &mut Opaque| { + // SAFETY: We initialized the required fields of `place.group` above. + unsafe { + bindings::config_group_init_type_name( + &mut (*place.get()).su_group, + name.as_ptr(), + item_type.as_ptr(), + ) + }; + + // SAFETY: `place.su_mutex` is valid for use as a mutex. + unsafe { + bindings::__mutex_init( + &mut (*place.get()).su_mutex, + kernel::optional_name!().as_char_ptr(), + kernel::static_lock_class!().as_ptr(), + ) + } + Ok(()) + } + ), + data <- data, + }) + .pin_chain(|this| { + crate::error::to_result( + // SAFETY: We initialized `this.subsystem` according to C API contract above. + unsafe { bindings::configfs_register_subsystem(this.subsystem.get()) }, + ) + }) + } +} + +#[pinned_drop] +impl PinnedDrop for Subsystem { + fn drop(self: Pin<&mut Self>) { + // SAFETY: We registered `self.subsystem` in the initializer returned by `Self::new`. + unsafe { bindings::configfs_unregister_subsystem(self.subsystem.get()) }; + // SAFETY: We initialized the mutex in `Subsystem::new`. + unsafe { bindings::mutex_destroy(&raw mut (*self.subsystem.get()).su_mutex) }; + } +} + +/// Trait that allows offset calculations for structs that embed a +/// `bindings::config_group`. +/// +/// Users of the configfs API should not need to implement this trait. +/// +/// # Safety +/// +/// - Implementers of this trait must embed a `bindings::config_group`. +/// - Methods must be implemented according to method documentation. +pub unsafe trait HasGroup { + /// Return the address of the `bindings::config_group` embedded in [`Self`]. + /// + /// # Safety + /// + /// - `this` must be a valid allocation of at least the size of [`Self`]. + unsafe fn group(this: *const Self) -> *const bindings::config_group; + + /// Return the address of the [`Self`] that `group` is embedded in. + /// + /// # Safety + /// + /// - `group` must point to the `bindings::config_group` that is embedded in + /// [`Self`]. + unsafe fn container_of(group: *const bindings::config_group) -> *const Self; +} + +// SAFETY: `Subsystem` embeds a field of type `bindings::config_group` +// within the `subsystem` field. +unsafe impl HasGroup for Subsystem { + unsafe fn group(this: *const Self) -> *const bindings::config_group { + // SAFETY: By impl and function safety requirement this projection is in bounds. + unsafe { &raw const (*(*this).subsystem.get()).su_group } + } + + unsafe fn container_of(group: *const bindings::config_group) -> *const Self { + // SAFETY: By impl and function safety requirement this projection is in bounds. + let c_subsys_ptr = unsafe { container_of!(group, bindings::configfs_subsystem, su_group) }; + let opaque_ptr = c_subsys_ptr.cast::>(); + // SAFETY: By impl and function safety requirement, `opaque_ptr` and the + // pointer it returns, are within the same allocation. + unsafe { container_of!(opaque_ptr, Subsystem, subsystem) } + } +} + +/// A configfs group. +/// +/// To add a subgroup to configfs, pass this type as `ctype` to +/// [`crate::configfs_attrs`] when creating a group in [`GroupOperations::make_group`]. +#[pin_data] +pub struct Group { + #[pin] + group: Opaque, + #[pin] + data: Data, +} + +impl Group { + /// Create an initializer for a new group. + /// + /// When instantiated, the group will appear as a directory with the name + /// given by `name` and it will contain attributes specified by `item_type`. + pub fn new( + name: CString, + item_type: &'static ItemType, Data>, + data: impl PinInit, + ) -> impl PinInit { + try_pin_init!(Self { + group <- pin_init::zeroed().chain(|v: &mut Opaque| { + let place = v.get(); + let name = name.as_bytes_with_nul().as_ptr(); + // SAFETY: It is safe to initialize a group once it has been zeroed. + unsafe { + bindings::config_group_init_type_name(place, name.cast(), item_type.as_ptr()) + }; + Ok(()) + }), + data <- data, + }) + } +} + +// SAFETY: `Group` embeds a field of type `bindings::config_group` +// within the `group` field. +unsafe impl HasGroup for Group { + unsafe fn group(this: *const Self) -> *const bindings::config_group { + Opaque::raw_get( + // SAFETY: By impl and function safety requirements this field + // projection is within bounds of the allocation. + unsafe { &raw const (*this).group }, + ) + } + + unsafe fn container_of(group: *const bindings::config_group) -> *const Self { + let opaque_ptr = group.cast::>(); + // SAFETY: By impl and function safety requirement, `opaque_ptr` and + // pointer it returns will be in the same allocation. + unsafe { container_of!(opaque_ptr, Self, group) } + } +} + +/// # Safety +/// +/// `this` must be a valid pointer. +/// +/// If `this` does not represent the root group of a configfs subsystem, +/// `this` must be a pointer to a `bindings::config_group` embedded in a +/// `Group`. +/// +/// Otherwise, `this` must be a pointer to a `bindings::config_group` that +/// is embedded in a `bindings::configfs_subsystem` that is embedded in a +/// `Subsystem`. +unsafe fn get_group_data<'a, Parent>(this: *mut bindings::config_group) -> &'a Parent { + // SAFETY: `this` is a valid pointer. + let is_root = unsafe { (*this).cg_subsys.is_null() }; + + if !is_root { + // SAFETY: By C API contact,`this` was returned from a call to + // `make_group`. The pointer is known to be embedded within a + // `Group`. + unsafe { &(*Group::::container_of(this)).data } + } else { + // SAFETY: By C API contract, `this` is a pointer to the + // `bindings::config_group` field within a `Subsystem`. + unsafe { &(*Subsystem::container_of(this)).data } + } +} + +struct GroupOperationsVTable(PhantomData<(Parent, Child)>); + +impl GroupOperationsVTable +where + Parent: GroupOperations, + Child: 'static, +{ + /// # Safety + /// + /// `this` must be a valid pointer. + /// + /// If `this` does not represent the root group of a configfs subsystem, + /// `this` must be a pointer to a `bindings::config_group` embedded in a + /// `Group`. + /// + /// Otherwise, `this` must be a pointer to a `bindings::config_group` that + /// is embedded in a `bindings::configfs_subsystem` that is embedded in a + /// `Subsystem`. + /// + /// `name` must point to a null terminated string. + unsafe extern "C" fn make_group( + this: *mut bindings::config_group, + name: *const kernel::ffi::c_char, + ) -> *mut bindings::config_group { + // SAFETY: By function safety requirements of this function, this call + // is safe. + let parent_data = unsafe { get_group_data(this) }; + + let group_init = match Parent::make_group( + parent_data, + // SAFETY: By function safety requirements, name points to a null + // terminated string. + unsafe { CStr::from_char_ptr(name) }, + ) { + Ok(init) => init, + Err(e) => return e.to_ptr(), + }; + + let child_group = > as InPlaceInit>>::try_pin_init( + group_init, + flags::GFP_KERNEL, + ); + + match child_group { + Ok(child_group) => { + let child_group_ptr = child_group.into_raw(); + // SAFETY: We allocated the pointee of `child_ptr` above as a + // `Group`. + unsafe { Group::::group(child_group_ptr) }.cast_mut() + } + Err(e) => e.to_ptr(), + } + } + + /// # Safety + /// + /// If `this` does not represent the root group of a configfs subsystem, + /// `this` must be a pointer to a `bindings::config_group` embedded in a + /// `Group`. + /// + /// Otherwise, `this` must be a pointer to a `bindings::config_group` that + /// is embedded in a `bindings::configfs_subsystem` that is embedded in a + /// `Subsystem`. + /// + /// `item` must point to a `bindings::config_item` within a + /// `bindings::config_group` within a `Group`. + unsafe extern "C" fn drop_item( + this: *mut bindings::config_group, + item: *mut bindings::config_item, + ) { + // SAFETY: By function safety requirements of this function, this call + // is safe. + let parent_data = unsafe { get_group_data(this) }; + + // SAFETY: By function safety requirements, `item` is embedded in a + // `config_group`. + let c_child_group_ptr = unsafe { container_of!(item, bindings::config_group, cg_item) }; + // SAFETY: By function safety requirements, `c_child_group_ptr` is + // embedded within a `Group`. + let r_child_group_ptr = unsafe { Group::::container_of(c_child_group_ptr) }; + + if Parent::HAS_DROP_ITEM { + // SAFETY: We called `into_raw` to produce `r_child_group_ptr` in + // `make_group`. + let arc: Arc> = unsafe { Arc::from_raw(r_child_group_ptr.cast_mut()) }; + + Parent::drop_item(parent_data, arc.as_arc_borrow()); + arc.into_raw(); + } + + // SAFETY: By C API contract, we are required to drop a refcount on + // `item`. + unsafe { bindings::config_item_put(item) }; + } + + const VTABLE: bindings::configfs_group_operations = bindings::configfs_group_operations { + make_item: None, + make_group: Some(Self::make_group), + disconnect_notify: None, + drop_item: Some(Self::drop_item), + is_visible: None, + is_bin_visible: None, + }; + + const fn vtable_ptr() -> *const bindings::configfs_group_operations { + &Self::VTABLE as *const bindings::configfs_group_operations + } +} + +struct ItemOperationsVTable(PhantomData<(Container, Data)>); + +impl ItemOperationsVTable, Data> +where + Data: 'static, +{ + /// # Safety + /// + /// `this` must be a pointer to a `bindings::config_group` embedded in a + /// `Group`. + /// + /// This function will destroy the pointee of `this`. The pointee of `this` + /// must not be accessed after the function returns. + unsafe extern "C" fn release(this: *mut bindings::config_item) { + // SAFETY: By function safety requirements, `this` is embedded in a + // `config_group`. + let c_group_ptr = unsafe { kernel::container_of!(this, bindings::config_group, cg_item) }; + // SAFETY: By function safety requirements, `c_group_ptr` is + // embedded within a `Group`. + let r_group_ptr = unsafe { Group::::container_of(c_group_ptr) }; + + // SAFETY: We called `into_raw` on `r_group_ptr` in + // `make_group`. + let pin_self: Arc> = unsafe { Arc::from_raw(r_group_ptr.cast_mut()) }; + drop(pin_self); + } + + const VTABLE: bindings::configfs_item_operations = bindings::configfs_item_operations { + release: Some(Self::release), + allow_link: None, + drop_link: None, + }; + + const fn vtable_ptr() -> *const bindings::configfs_item_operations { + &Self::VTABLE as *const bindings::configfs_item_operations + } +} + +impl ItemOperationsVTable, Data> { + const VTABLE: bindings::configfs_item_operations = bindings::configfs_item_operations { + release: None, + allow_link: None, + drop_link: None, + }; + + const fn vtable_ptr() -> *const bindings::configfs_item_operations { + &Self::VTABLE as *const bindings::configfs_item_operations + } +} + +/// Operations implemented by configfs groups that can create subgroups. +/// +/// Implement this trait on structs that embed a [`Subsystem`] or a [`Group`]. +#[vtable] +pub trait GroupOperations { + /// The child data object type. + /// + /// This group will create subgroups (subdirectories) backed by this kind of + /// object. + type Child: 'static; + + /// Creates a new subgroup. + /// + /// The kernel will call this method in response to `mkdir(2)` in the + /// directory representing `this`. + /// + /// To accept the request to create a group, implementations should + /// return an initializer of a `Group`. To prevent creation, + /// return a suitable error. + fn make_group(&self, name: &CStr) -> Result, Error>>; + + /// Prepares the group for removal from configfs. + /// + /// The kernel will call this method before the directory representing `_child` is removed from + /// configfs. + /// + /// Implementations can use this method to do house keeping before configfs drops its + /// reference to `Child`. + /// + /// NOTE: "drop" in the name of this function is not related to the Rust drop term. Rather, the + /// name is inherited from the callback name in the underlying C code. + fn drop_item(&self, _child: ArcBorrow<'_, Group>) { + kernel::build_error!(kernel::error::VTABLE_DEFAULT_ERROR) + } +} + +/// A configfs attribute. +/// +/// An attribute appears as a file in configfs, inside a folder that represent +/// the group that the attribute belongs to. +#[repr(transparent)] +pub struct Attribute { + attribute: Opaque, + _p: PhantomData<(O, Data)>, +} + +// SAFETY: We do not provide any operations on `Attribute`. +unsafe impl Sync for Attribute {} + +// SAFETY: Ownership of `Attribute` can safely be transferred to other threads. +unsafe impl Send for Attribute {} + +impl Attribute +where + O: AttributeOperations, +{ + /// # Safety + /// + /// `item` must be embedded in a `bindings::config_group`. + /// + /// If `item` does not represent the root group of a configfs subsystem, + /// the group must be embedded in a `Group`. + /// + /// Otherwise, the group must be a embedded in a + /// `bindings::configfs_subsystem` that is embedded in a `Subsystem`. + /// + /// `page` must point to a writable buffer of size at least [`PAGE_SIZE`]. + unsafe extern "C" fn show( + item: *mut bindings::config_item, + page: *mut kernel::ffi::c_char, + ) -> isize { + let c_group: *mut bindings::config_group = + // SAFETY: By function safety requirements, `item` is embedded in a + // `config_group`. + unsafe { container_of!(item, bindings::config_group, cg_item) }.cast_mut(); + + // SAFETY: The function safety requirements for this function satisfy + // the conditions for this call. + let data: &Data = unsafe { get_group_data(c_group) }; + + // SAFETY: By function safety requirements, `page` is writable for `PAGE_SIZE`. + let ret = O::show(data, unsafe { &mut *(page as *mut [u8; PAGE_SIZE]) }); + + match ret { + Ok(size) => size as isize, + Err(err) => err.to_errno() as isize, + } + } + + /// # Safety + /// + /// `item` must be embedded in a `bindings::config_group`. + /// + /// If `item` does not represent the root group of a configfs subsystem, + /// the group must be embedded in a `Group`. + /// + /// Otherwise, the group must be a embedded in a + /// `bindings::configfs_subsystem` that is embedded in a `Subsystem`. + /// + /// `page` must point to a readable buffer of size at least `size`. + unsafe extern "C" fn store( + item: *mut bindings::config_item, + page: *const kernel::ffi::c_char, + size: usize, + ) -> isize { + let c_group: *mut bindings::config_group = + // SAFETY: By function safety requirements, `item` is embedded in a + // `config_group`. + unsafe { container_of!(item, bindings::config_group, cg_item) }.cast_mut(); + + // SAFETY: The function safety requirements for this function satisfy + // the conditions for this call. + let data: &Data = unsafe { get_group_data(c_group) }; + + let ret = O::store( + data, + // SAFETY: By function safety requirements, `page` is readable + // for at least `size`. + unsafe { core::slice::from_raw_parts(page.cast(), size) }, + ); + + match ret { + Ok(()) => size as isize, + Err(err) => err.to_errno() as isize, + } + } + + /// Create a new attribute. + /// + /// The attribute will appear as a file with name given by `name`. + pub const fn new(name: &'static CStr) -> Self { + Self { + attribute: Opaque::new(bindings::configfs_attribute { + ca_name: name.as_char_ptr(), + ca_owner: core::ptr::null_mut(), + ca_mode: 0o660, + show: Some(Self::show), + store: if O::HAS_STORE { + Some(Self::store) + } else { + None + }, + }), + _p: PhantomData, + } + } +} + +/// Operations supported by an attribute. +/// +/// Implement this trait on type and pass that type as generic parameter when +/// creating an [`Attribute`]. The type carrying the implementation serve no +/// purpose other than specifying the attribute operations. +/// +/// This trait must be implemented on the `Data` type of for types that +/// implement `HasGroup`. The trait must be implemented once for each +/// attribute of the group. The constant type parameter `ID` maps the +/// implementation to a specific `Attribute`. `ID` must be passed when declaring +/// attributes via the [`kernel::configfs_attrs`] macro, to tie +/// `AttributeOperations` implementations to concrete named attributes. +#[vtable] +pub trait AttributeOperations { + /// The type of the object that contains the field that is backing the + /// attribute for this operation. + type Data; + + /// Renders the value of an attribute. + /// + /// This function is called by the kernel to read the value of an attribute. + /// + /// Implementations should write the rendering of the attribute to `page` + /// and return the number of bytes written. + fn show(data: &Self::Data, page: &mut [u8; PAGE_SIZE]) -> Result; + + /// Stores the value of an attribute. + /// + /// This function is called by the kernel to update the value of an attribute. + /// + /// Implementations should parse the value from `page` and update internal + /// state to reflect the parsed value. + fn store(_data: &Self::Data, _page: &[u8]) -> Result { + kernel::build_error!(kernel::error::VTABLE_DEFAULT_ERROR) + } +} + +/// A list of attributes. +/// +/// This type is used to construct a new [`ItemType`]. It represents a list of +/// [`Attribute`] that will appear in the directory representing a [`Group`]. +/// Users should not directly instantiate this type, rather they should use the +/// [`kernel::configfs_attrs`] macro to declare a static set of attributes for a +/// group. +/// +/// # Note +/// +/// Instances of this type are constructed statically at compile by the +/// [`kernel::configfs_attrs`] macro. +#[repr(transparent)] +pub struct AttributeList( + /// Null terminated Array of pointers to [`Attribute`]. The type is [`c_void`] + /// to conform to the C API. + UnsafeCell<[*mut kernel::ffi::c_void; N]>, + PhantomData, +); + +// SAFETY: Ownership of `AttributeList` can safely be transferred to other threads. +unsafe impl Send for AttributeList {} + +// SAFETY: We do not provide any operations on `AttributeList` that need synchronization. +unsafe impl Sync for AttributeList {} + +impl AttributeList { + /// # Safety + /// + /// This function must only be called by the [`kernel::configfs_attrs`] + /// macro. + #[doc(hidden)] + pub const unsafe fn new() -> Self { + Self(UnsafeCell::new([core::ptr::null_mut(); N]), PhantomData) + } + + /// # Safety + /// + /// The caller must ensure that there are no other concurrent accesses to + /// `self`. That is, the caller has exclusive access to `self.` + #[doc(hidden)] + pub const unsafe fn add( + &'static self, + attribute: &'static Attribute, + ) where + O: AttributeOperations, + { + // We need a space at the end of our list for a null terminator. + const { assert!(I < N - 1, "Invalid attribute index") }; + + // SAFETY: By function safety requirements, we have exclusive access to + // `self` and the reference created below will be exclusive. + unsafe { + (&mut *self.0.get())[I] = (attribute as *const Attribute) + .cast_mut() + .cast() + }; + } +} + +/// A representation of the attributes that will appear in a [`Group`] or +/// [`Subsystem`]. +/// +/// Users should not directly instantiate objects of this type. Rather, they +/// should use the [`kernel::configfs_attrs`] macro to statically declare the +/// shape of a [`Group`] or [`Subsystem`]. +#[pin_data] +pub struct ItemType { + #[pin] + item_type: Opaque, + _p: PhantomData<(Container, Data)>, +} + +// SAFETY: We do not provide any operations on `ItemType` that need synchronization. +unsafe impl Sync for ItemType {} + +// SAFETY: Ownership of `ItemType` can safely be transferred to other threads. +unsafe impl Send for ItemType {} + +macro_rules! impl_item_type { + ($tpe:ty) => { + impl ItemType<$tpe, Data> { + #[doc(hidden)] + pub const fn new_with_child_ctor( + owner: &'static ThisModule, + attributes: &'static AttributeList, + ) -> Self + where + Data: GroupOperations, + Child: 'static, + { + Self { + item_type: Opaque::new(bindings::config_item_type { + ct_owner: owner.as_ptr(), + ct_group_ops: GroupOperationsVTable::::vtable_ptr().cast_mut(), + ct_item_ops: ItemOperationsVTable::<$tpe, Data>::vtable_ptr().cast_mut(), + ct_attrs: (attributes as *const AttributeList) + .cast_mut() + .cast(), + ct_bin_attrs: core::ptr::null_mut(), + }), + _p: PhantomData, + } + } + + #[doc(hidden)] + pub const fn new( + owner: &'static ThisModule, + attributes: &'static AttributeList, + ) -> Self { + Self { + item_type: Opaque::new(bindings::config_item_type { + ct_owner: owner.as_ptr(), + ct_group_ops: core::ptr::null_mut(), + ct_item_ops: ItemOperationsVTable::<$tpe, Data>::vtable_ptr().cast_mut(), + ct_attrs: (attributes as *const AttributeList) + .cast_mut() + .cast(), + ct_bin_attrs: core::ptr::null_mut(), + }), + _p: PhantomData, + } + } + } + }; +} + +impl_item_type!(Subsystem); +impl_item_type!(Group); + +impl ItemType { + fn as_ptr(&self) -> *const bindings::config_item_type { + self.item_type.get() + } +} + +/// Define a list of configfs attributes statically. +/// +/// Invoking the macro in the following manner: +/// +/// ```ignore +/// let item_type = configfs_attrs! { +/// container: configfs::Subsystem, +/// data: Configuration, +/// child: Child, +/// attributes: [ +/// message: 0, +/// bar: 1, +/// ], +/// }; +/// ``` +/// +/// Expands the following output: +/// +/// ```ignore +/// let item_type = { +/// static CONFIGURATION_MESSAGE_ATTR: kernel::configfs::Attribute< +/// 0, +/// Configuration, +/// Configuration, +/// > = unsafe { +/// kernel::configfs::Attribute::new({ +/// const S: &str = "message\u{0}"; +/// const C: &kernel::str::CStr = match kernel::str::CStr::from_bytes_with_nul( +/// S.as_bytes() +/// ) { +/// Ok(v) => v, +/// Err(_) => { +/// core::panicking::panic_fmt(core::const_format_args!( +/// "string contains interior NUL" +/// )); +/// } +/// }; +/// C +/// }) +/// }; +/// +/// static CONFIGURATION_BAR_ATTR: kernel::configfs::Attribute< +/// 1, +/// Configuration, +/// Configuration +/// > = unsafe { +/// kernel::configfs::Attribute::new({ +/// const S: &str = "bar\u{0}"; +/// const C: &kernel::str::CStr = match kernel::str::CStr::from_bytes_with_nul( +/// S.as_bytes() +/// ) { +/// Ok(v) => v, +/// Err(_) => { +/// core::panicking::panic_fmt(core::const_format_args!( +/// "string contains interior NUL" +/// )); +/// } +/// }; +/// C +/// }) +/// }; +/// +/// const N: usize = (1usize + (1usize + 0usize)) + 1usize; +/// +/// static CONFIGURATION_ATTRS: kernel::configfs::AttributeList = +/// unsafe { kernel::configfs::AttributeList::new() }; +/// +/// { +/// const N: usize = 0usize; +/// unsafe { CONFIGURATION_ATTRS.add::(&CONFIGURATION_MESSAGE_ATTR) }; +/// } +/// +/// { +/// const N: usize = (1usize + 0usize); +/// unsafe { CONFIGURATION_ATTRS.add::(&CONFIGURATION_BAR_ATTR) }; +/// } +/// +/// static CONFIGURATION_TPE: +/// kernel::configfs::ItemType ,Configuration> +/// = kernel::configfs::ItemType::< +/// configfs::Subsystem, +/// Configuration +/// >::new_with_child_ctor::( +/// &THIS_MODULE, +/// &CONFIGURATION_ATTRS +/// ); +/// +/// &CONFIGURATION_TPE +/// } +/// ``` +#[macro_export] +macro_rules! configfs_attrs { + ( + container: $container:ty, + data: $data:ty, + attributes: [ + $($name:ident: $attr:literal),* $(,)? + ] $(,)? + ) => { + $crate::configfs_attrs!( + count: + @container($container), + @data($data), + @child(), + @no_child(x), + @attrs($($name $attr)*), + @eat($($name $attr,)*), + @assign(), + @cnt(0usize), + ) + }; + ( + container: $container:ty, + data: $data:ty, + child: $child:ty, + attributes: [ + $($name:ident: $attr:literal),* $(,)? + ] $(,)? + ) => { + $crate::configfs_attrs!( + count: + @container($container), + @data($data), + @child($child), + @no_child(), + @attrs($($name $attr)*), + @eat($($name $attr,)*), + @assign(), + @cnt(0usize), + ) + }; + (count: + @container($container:ty), + @data($data:ty), + @child($($child:ty)?), + @no_child($($no_child:ident)?), + @attrs($($aname:ident $aattr:literal)*), + @eat($name:ident $attr:literal, $($rname:ident $rattr:literal,)*), + @assign($($assign:block)*), + @cnt($cnt:expr), + ) => { + $crate::configfs_attrs!( + count: + @container($container), + @data($data), + @child($($child)?), + @no_child($($no_child)?), + @attrs($($aname $aattr)*), + @eat($($rname $rattr,)*), + @assign($($assign)* { + const N: usize = $cnt; + // The following macro text expands to a call to `Attribute::add`. + + // SAFETY: By design of this macro, the name of the variable we + // invoke the `add` method on below, is not visible outside of + // the macro expansion. The macro does not operate concurrently + // on this variable, and thus we have exclusive access to the + // variable. + unsafe { + $crate::macros::paste!( + [< $data:upper _ATTRS >] + .add::(&[< $data:upper _ $name:upper _ATTR >]) + ) + }; + }), + @cnt(1usize + $cnt), + ) + }; + (count: + @container($container:ty), + @data($data:ty), + @child($($child:ty)?), + @no_child($($no_child:ident)?), + @attrs($($aname:ident $aattr:literal)*), + @eat(), + @assign($($assign:block)*), + @cnt($cnt:expr), + ) => + { + $crate::configfs_attrs!( + final: + @container($container), + @data($data), + @child($($child)?), + @no_child($($no_child)?), + @attrs($($aname $aattr)*), + @assign($($assign)*), + @cnt($cnt), + ) + }; + (final: + @container($container:ty), + @data($data:ty), + @child($($child:ty)?), + @no_child($($no_child:ident)?), + @attrs($($name:ident $attr:literal)*), + @assign($($assign:block)*), + @cnt($cnt:expr), + ) => + { + $crate::macros::paste!{ + { + $( + // SAFETY: We are expanding `configfs_attrs`. + static [< $data:upper _ $name:upper _ATTR >]: + $crate::configfs::Attribute<$attr, $data, $data> = + unsafe { + $crate::configfs::Attribute::new(c_str!(::core::stringify!($name))) + }; + )* + + + // We need space for a null terminator. + const N: usize = $cnt + 1usize; + + // SAFETY: We are expanding `configfs_attrs`. + static [< $data:upper _ATTRS >]: + $crate::configfs::AttributeList = + unsafe { $crate::configfs::AttributeList::new() }; + + $($assign)* + + $( + const [<$no_child:upper>]: bool = true; + + static [< $data:upper _TPE >] : $crate::configfs::ItemType<$container, $data> = + $crate::configfs::ItemType::<$container, $data>::new::( + &THIS_MODULE, &[<$ data:upper _ATTRS >] + ); + )? + + $( + static [< $data:upper _TPE >]: + $crate::configfs::ItemType<$container, $data> = + $crate::configfs::ItemType::<$container, $data>:: + new_with_child_ctor::( + &THIS_MODULE, &[<$ data:upper _ATTRS >] + ); + )? + + & [< $data:upper _TPE >] + } + } + }; + +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de07aadd1ff5..bcbf5026449d 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -42,6 +42,8 @@ pub mod alloc; pub mod block; #[doc(hidden)] pub mod build_assert; +#[cfg(CONFIG_CONFIGFS_FS)] +pub mod configfs; pub mod cred; pub mod device; pub mod device_id; -- cgit v1.2.3 From 9520371e3daa75cd508b262ac16a732d3ffc9a30 Mon Sep 17 00:00:00 2001 From: I Hsin Cheng Date: Wed, 19 Mar 2025 10:26:40 +0800 Subject: rust: sync: rcu: Mark Guard methods as inline Currently the implementation of "Guard" methods are basically wrappers around rcu's function within kernel. Building the kernel with llvm 18.1.8 on x86_64 machine will generate the following symbols: $ nm vmlinux | grep ' _R'.*Guard | rustfilt ffffffff817b6c90 T ::new ffffffff817b6cb0 T ::unlock ffffffff817b6cd0 T ::drop ffffffff817b6c90 T ::default These Rust symbols are basically wrappers around functions "rcu_read_lock" and "rcu_read_unlock". Marking them as inline can reduce the generation of these symbols, and saves the size of code generation for 132 bytes. $ ./scripts/bloat-o-meter vmlinux_old vmlinux_new (Output is demangled for readability) add/remove: 0/10 grow/shrink: 0/1 up/down: 0/-132 (-132) Function old new delta rust_driver_pci::SampleDriver::probe 1041 1034 -7 kernel::sync::rcu::Guard::default 9 - -9 kernel::sync::rcu::Guard::drop 9 - -9 kernel::sync::rcu::read_lock 9 - -9 kernel::sync::rcu::Guard::unlock 9 - -9 kernel::sync::rcu::Guard::new 9 - -9 __pfx__kernel::sync::rcu::Guard::default 16 - -16 __pfx__kernel::sync::rcu::Guard::drop 16 - -16 __pfx__kernel::sync::rcu::read_lock 16 - -16 __pfx__kernel::sync::rcu::Guard::unlock 16 - -16 __pfx__kernel::sync::rcu::Guard::new 16 - -16 Total: Before=23365955, After=23365823, chg -0.00% Link: https://github.com/Rust-for-Linux/linux/issues/1145 Signed-off-by: I Hsin Cheng Reviewed-by: Joel Fernandes Reviewed-by: Benno Lossin Reviewed-by: Charalampos Mitrodimas Acked-by: Miguel Ojeda Signed-off-by: Joel Fernandes --- rust/kernel/sync/rcu.rs | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs index b51d9150ffe2..a32bef6e490b 100644 --- a/rust/kernel/sync/rcu.rs +++ b/rust/kernel/sync/rcu.rs @@ -17,6 +17,7 @@ pub struct Guard(NotThreadSafe); impl Guard { /// Acquires the RCU read side lock and returns a guard. + #[inline] pub fn new() -> Self { // SAFETY: An FFI call with no additional requirements. unsafe { bindings::rcu_read_lock() }; @@ -25,16 +26,19 @@ impl Guard { } /// Explicitly releases the RCU read side lock. + #[inline] pub fn unlock(self) {} } impl Default for Guard { + #[inline] fn default() -> Self { Self::new() } } impl Drop for Guard { + #[inline] fn drop(&mut self) { // SAFETY: By the type invariants, the RCU read side is locked, so it is ok to unlock it. unsafe { bindings::rcu_read_unlock() }; @@ -42,6 +46,7 @@ impl Drop for Guard { } /// Acquires the RCU read side lock. +#[inline] pub fn read_lock() -> Guard { Guard::new() } -- cgit v1.2.3 From 8961b8cb3099abd06486394aaf12dd535baaf070 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Thu, 6 Jun 2024 15:23:39 +0530 Subject: rust: cpumask: Add initial abstractions Add initial Rust abstractions for struct cpumask, covering a subset of its APIs. Additional APIs can be added as needed. These abstractions will be used in upcoming Rust support for cpufreq and OPP frameworks. Signed-off-by: Viresh Kumar Reviewed-by: Yury Norov [NVIDIA] --- rust/kernel/cpumask.rs | 330 +++++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 331 insertions(+) create mode 100644 rust/kernel/cpumask.rs (limited to 'rust/kernel') diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs new file mode 100644 index 000000000000..c90bfac9346a --- /dev/null +++ b/rust/kernel/cpumask.rs @@ -0,0 +1,330 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! CPU Mask abstractions. +//! +//! C header: [`include/linux/cpumask.h`](srctree/include/linux/cpumask.h) + +use crate::{ + alloc::{AllocError, Flags}, + prelude::*, + types::Opaque, +}; + +#[cfg(CONFIG_CPUMASK_OFFSTACK)] +use core::ptr::{self, NonNull}; + +#[cfg(not(CONFIG_CPUMASK_OFFSTACK))] +use core::mem::MaybeUninit; + +use core::ops::{Deref, DerefMut}; + +/// A CPU Mask. +/// +/// Rust abstraction for the C `struct cpumask`. +/// +/// # Invariants +/// +/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`. +/// +/// The callers must ensure that the `struct cpumask` is valid for access and +/// remains valid for the lifetime of the returned reference. +/// +/// ## Examples +/// +/// The following example demonstrates how to update a [`Cpumask`]. +/// +/// ``` +/// use kernel::bindings; +/// use kernel::cpumask::Cpumask; +/// +/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: u32, clear_cpu: i32) { +/// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the +/// // returned reference. +/// let mask = unsafe { Cpumask::as_mut_ref(ptr) }; +/// +/// mask.set(set_cpu); +/// mask.clear(clear_cpu); +/// } +/// ``` +#[repr(transparent)] +pub struct Cpumask(Opaque); + +impl Cpumask { + /// Creates a mutable reference to an existing `struct cpumask` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime + /// of the returned reference. + pub unsafe fn as_mut_ref<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the + // lifetime of the returned reference. + unsafe { &mut *ptr.cast() } + } + + /// Creates a reference to an existing `struct cpumask` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime + /// of the returned reference. + pub unsafe fn as_ref<'a>(ptr: *const bindings::cpumask) -> &'a Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the + // lifetime of the returned reference. + unsafe { &*ptr.cast() } + } + + /// Obtain the raw `struct cpumask` pointer. + pub fn as_raw(&self) -> *mut bindings::cpumask { + let this: *const Self = self; + this.cast_mut().cast() + } + + /// Set `cpu` in the cpumask. + /// + /// ATTENTION: Contrary to C, this Rust `set()` method is non-atomic. + /// This mismatches kernel naming convention and corresponds to the C + /// function `__cpumask_set_cpu()`. + #[inline] + pub fn set(&mut self, cpu: u32) { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`. + unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) }; + } + + /// Clear `cpu` in the cpumask. + /// + /// ATTENTION: Contrary to C, this Rust `clear()` method is non-atomic. + /// This mismatches kernel naming convention and corresponds to the C + /// function `__cpumask_clear_cpu()`. + #[inline] + pub fn clear(&mut self, cpu: i32) { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to + // `__cpumask_clear_cpu`. + unsafe { bindings::__cpumask_clear_cpu(cpu, self.as_raw()) }; + } + + /// Test `cpu` in the cpumask. + /// + /// Equivalent to the kernel's `cpumask_test_cpu` API. + #[inline] + pub fn test(&self, cpu: i32) -> bool { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`. + unsafe { bindings::cpumask_test_cpu(cpu, self.as_raw()) } + } + + /// Set all CPUs in the cpumask. + /// + /// Equivalent to the kernel's `cpumask_setall` API. + #[inline] + pub fn setall(&mut self) { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_setall`. + unsafe { bindings::cpumask_setall(self.as_raw()) }; + } + + /// Checks if cpumask is empty. + /// + /// Equivalent to the kernel's `cpumask_empty` API. + #[inline] + pub fn empty(&self) -> bool { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_empty`. + unsafe { bindings::cpumask_empty(self.as_raw()) } + } + + /// Checks if cpumask is full. + /// + /// Equivalent to the kernel's `cpumask_full` API. + #[inline] + pub fn full(&self) -> bool { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_full`. + unsafe { bindings::cpumask_full(self.as_raw()) } + } + + /// Get weight of the cpumask. + /// + /// Equivalent to the kernel's `cpumask_weight` API. + #[inline] + pub fn weight(&self) -> u32 { + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_weight`. + unsafe { bindings::cpumask_weight(self.as_raw()) } + } + + /// Copy cpumask. + /// + /// Equivalent to the kernel's `cpumask_copy` API. + #[inline] + pub fn copy(&self, dstp: &mut Self) { + // SAFETY: By the type invariant, `Self::as_raw` is a valid argument to `cpumask_copy`. + unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) }; + } +} + +/// A CPU Mask pointer. +/// +/// Rust abstraction for the C `struct cpumask_var_t`. +/// +/// # Invariants +/// +/// A [`CpumaskVar`] instance always corresponds to a valid C `struct cpumask_var_t`. +/// +/// The callers must ensure that the `struct cpumask_var_t` is valid for access and remains valid +/// for the lifetime of [`CpumaskVar`]. +/// +/// ## Examples +/// +/// The following example demonstrates how to create and update a [`CpumaskVar`]. +/// +/// ``` +/// use kernel::cpumask::CpumaskVar; +/// +/// let mut mask = CpumaskVar::new_zero(GFP_KERNEL).unwrap(); +/// +/// assert!(mask.empty()); +/// mask.set(2); +/// assert!(mask.test(2)); +/// mask.set(3); +/// assert!(mask.test(3)); +/// assert_eq!(mask.weight(), 2); +/// +/// let mask2 = CpumaskVar::try_clone(&mask).unwrap(); +/// assert!(mask2.test(2)); +/// assert!(mask2.test(3)); +/// assert_eq!(mask2.weight(), 2); +/// ``` +pub struct CpumaskVar { + #[cfg(CONFIG_CPUMASK_OFFSTACK)] + ptr: NonNull, + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))] + mask: Cpumask, +} + +impl CpumaskVar { + /// Creates a zero-initialized instance of the [`CpumaskVar`]. + pub fn new_zero(_flags: Flags) -> Result { + Ok(Self { + #[cfg(CONFIG_CPUMASK_OFFSTACK)] + ptr: { + let mut ptr: *mut bindings::cpumask = ptr::null_mut(); + + // SAFETY: It is safe to call this method as the reference to `ptr` is valid. + // + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of + // scope. + unsafe { bindings::zalloc_cpumask_var(&mut ptr, _flags.as_raw()) }; + NonNull::new(ptr.cast()).ok_or(AllocError)? + }, + + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))] + // SAFETY: FFI type is valid to be zero-initialized. + // + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope. + mask: unsafe { core::mem::zeroed() }, + }) + } + + /// Creates an instance of the [`CpumaskVar`]. + /// + /// # Safety + /// + /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before + /// getting used. + pub unsafe fn new(_flags: Flags) -> Result { + Ok(Self { + #[cfg(CONFIG_CPUMASK_OFFSTACK)] + ptr: { + let mut ptr: *mut bindings::cpumask = ptr::null_mut(); + + // SAFETY: It is safe to call this method as the reference to `ptr` is valid. + // + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of + // scope. + unsafe { bindings::alloc_cpumask_var(&mut ptr, _flags.as_raw()) }; + NonNull::new(ptr.cast()).ok_or(AllocError)? + }, + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))] + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope. + mask: unsafe { MaybeUninit::uninit().assume_init() }, + }) + } + + /// Creates a mutable reference to an existing `struct cpumask_var_t` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime + /// of the returned reference. + pub unsafe fn as_mut_ref<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the + // lifetime of the returned reference. + unsafe { &mut *ptr.cast() } + } + + /// Creates a reference to an existing `struct cpumask_var_t` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime + /// of the returned reference. + pub unsafe fn as_ref<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the + // lifetime of the returned reference. + unsafe { &*ptr.cast() } + } + + /// Clones cpumask. + pub fn try_clone(cpumask: &Cpumask) -> Result { + // SAFETY: The returned cpumask_var is initialized right after this call. + let mut cpumask_var = unsafe { Self::new(GFP_KERNEL) }?; + + cpumask.copy(&mut cpumask_var); + Ok(cpumask_var) + } +} + +// Make [`CpumaskVar`] behave like a pointer to [`Cpumask`]. +impl Deref for CpumaskVar { + type Target = Cpumask; + + #[cfg(CONFIG_CPUMASK_OFFSTACK)] + fn deref(&self) -> &Self::Target { + // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask. + unsafe { &*self.ptr.as_ptr() } + } + + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))] + fn deref(&self) -> &Self::Target { + &self.mask + } +} + +impl DerefMut for CpumaskVar { + #[cfg(CONFIG_CPUMASK_OFFSTACK)] + fn deref_mut(&mut self) -> &mut Cpumask { + // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask. + unsafe { self.ptr.as_mut() } + } + + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))] + fn deref_mut(&mut self) -> &mut Cpumask { + &mut self.mask + } +} + +impl Drop for CpumaskVar { + fn drop(&mut self) { + #[cfg(CONFIG_CPUMASK_OFFSTACK)] + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `free_cpumask_var`. + unsafe { + bindings::free_cpumask_var(self.as_raw()) + }; + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de07aadd1ff5..75f78f6bfaa6 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -42,6 +42,7 @@ pub mod alloc; pub mod block; #[doc(hidden)] pub mod build_assert; +pub mod cpumask; pub mod cred; pub mod device; pub mod device_id; -- cgit v1.2.3 From d01d7020560116876c6e39e056737b8f81f153e0 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Thu, 20 Feb 2025 16:45:47 +0530 Subject: rust: clk: Add initial abstractions Add initial abstractions for the clk APIs. These provide the minimal functionality needed for common use cases, making them straightforward to introduce in the first iteration. These will be used by Rust based cpufreq / OPP layers to begin with. Tested-by: Daniel Almeida Reviewed-by: Daniel Almeida Signed-off-by: Viresh Kumar --- rust/kernel/clk.rs | 334 +++++++++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 335 insertions(+) create mode 100644 rust/kernel/clk.rs (limited to 'rust/kernel') diff --git a/rust/kernel/clk.rs b/rust/kernel/clk.rs new file mode 100644 index 000000000000..6041c6d07527 --- /dev/null +++ b/rust/kernel/clk.rs @@ -0,0 +1,334 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Clock abstractions. +//! +//! C header: [`include/linux/clk.h`](srctree/include/linux/clk.h) +//! +//! Reference: + +use crate::ffi::c_ulong; + +/// The frequency unit. +/// +/// Represents a frequency in hertz, wrapping a [`c_ulong`] value. +/// +/// ## Examples +/// +/// ``` +/// use kernel::clk::Hertz; +/// +/// let hz = 1_000_000_000; +/// let rate = Hertz(hz); +/// +/// assert_eq!(rate.as_hz(), hz); +/// assert_eq!(rate, Hertz(hz)); +/// assert_eq!(rate, Hertz::from_khz(hz / 1_000)); +/// assert_eq!(rate, Hertz::from_mhz(hz / 1_000_000)); +/// assert_eq!(rate, Hertz::from_ghz(hz / 1_000_000_000)); +/// ``` +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub struct Hertz(pub c_ulong); + +impl Hertz { + /// Create a new instance from kilohertz (kHz) + pub fn from_khz(khz: c_ulong) -> Self { + Self(khz * 1_000) + } + + /// Create a new instance from megahertz (MHz) + pub fn from_mhz(mhz: c_ulong) -> Self { + Self(mhz * 1_000_000) + } + + /// Create a new instance from gigahertz (GHz) + pub fn from_ghz(ghz: c_ulong) -> Self { + Self(ghz * 1_000_000_000) + } + + /// Get the frequency in hertz + pub fn as_hz(&self) -> c_ulong { + self.0 + } + + /// Get the frequency in kilohertz + pub fn as_khz(&self) -> c_ulong { + self.0 / 1_000 + } + + /// Get the frequency in megahertz + pub fn as_mhz(&self) -> c_ulong { + self.0 / 1_000_000 + } + + /// Get the frequency in gigahertz + pub fn as_ghz(&self) -> c_ulong { + self.0 / 1_000_000_000 + } +} + +impl From for c_ulong { + fn from(freq: Hertz) -> Self { + freq.0 + } +} + +#[cfg(CONFIG_COMMON_CLK)] +mod common_clk { + use super::Hertz; + use crate::{ + device::Device, + error::{from_err_ptr, to_result, Result}, + prelude::*, + }; + + use core::{ops::Deref, ptr}; + + /// A reference-counted clock. + /// + /// Rust abstraction for the C [`struct clk`]. + /// + /// # Invariants + /// + /// A [`Clk`] instance holds either a pointer to a valid [`struct clk`] created by the C + /// portion of the kernel or a NULL pointer. + /// + /// Instances of this type are reference-counted. Calling [`Clk::get`] ensures that the + /// allocation remains valid for the lifetime of the [`Clk`]. + /// + /// ## Examples + /// + /// The following example demonstrates how to obtain and configure a clock for a device. + /// + /// ``` + /// use kernel::c_str; + /// use kernel::clk::{Clk, Hertz}; + /// use kernel::device::Device; + /// use kernel::error::Result; + /// + /// fn configure_clk(dev: &Device) -> Result { + /// let clk = Clk::get(dev, Some(c_str!("apb_clk")))?; + /// + /// clk.prepare_enable()?; + /// + /// let expected_rate = Hertz::from_ghz(1); + /// + /// if clk.rate() != expected_rate { + /// clk.set_rate(expected_rate)?; + /// } + /// + /// clk.disable_unprepare(); + /// Ok(()) + /// } + /// ``` + /// + /// [`struct clk`]: https://docs.kernel.org/driver-api/clk.html + #[repr(transparent)] + pub struct Clk(*mut bindings::clk); + + impl Clk { + /// Gets [`Clk`] corresponding to a [`Device`] and a connection id. + /// + /// Equivalent to the kernel's [`clk_get`] API. + /// + /// [`clk_get`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get + pub fn get(dev: &Device, name: Option<&CStr>) -> Result { + let con_id = if let Some(name) = name { + name.as_ptr() + } else { + ptr::null() + }; + + // SAFETY: It is safe to call [`clk_get`] for a valid device pointer. + // + // INVARIANT: The reference-count is decremented when [`Clk`] goes out of scope. + Ok(Self(from_err_ptr(unsafe { + bindings::clk_get(dev.as_raw(), con_id) + })?)) + } + + /// Obtain the raw [`struct clk`] pointer. + #[inline] + pub fn as_raw(&self) -> *mut bindings::clk { + self.0 + } + + /// Enable the clock. + /// + /// Equivalent to the kernel's [`clk_enable`] API. + /// + /// [`clk_enable`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_enable + #[inline] + pub fn enable(&self) -> Result { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_enable`]. + to_result(unsafe { bindings::clk_enable(self.as_raw()) }) + } + + /// Disable the clock. + /// + /// Equivalent to the kernel's [`clk_disable`] API. + /// + /// [`clk_disable`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_disable + #[inline] + pub fn disable(&self) { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_disable`]. + unsafe { bindings::clk_disable(self.as_raw()) }; + } + + /// Prepare the clock. + /// + /// Equivalent to the kernel's [`clk_prepare`] API. + /// + /// [`clk_prepare`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_prepare + #[inline] + pub fn prepare(&self) -> Result { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_prepare`]. + to_result(unsafe { bindings::clk_prepare(self.as_raw()) }) + } + + /// Unprepare the clock. + /// + /// Equivalent to the kernel's [`clk_unprepare`] API. + /// + /// [`clk_unprepare`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_unprepare + #[inline] + pub fn unprepare(&self) { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_unprepare`]. + unsafe { bindings::clk_unprepare(self.as_raw()) }; + } + + /// Prepare and enable the clock. + /// + /// Equivalent to calling [`Clk::prepare`] followed by [`Clk::enable`]. + #[inline] + pub fn prepare_enable(&self) -> Result { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_prepare_enable`]. + to_result(unsafe { bindings::clk_prepare_enable(self.as_raw()) }) + } + + /// Disable and unprepare the clock. + /// + /// Equivalent to calling [`Clk::disable`] followed by [`Clk::unprepare`]. + #[inline] + pub fn disable_unprepare(&self) { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_disable_unprepare`]. + unsafe { bindings::clk_disable_unprepare(self.as_raw()) }; + } + + /// Get clock's rate. + /// + /// Equivalent to the kernel's [`clk_get_rate`] API. + /// + /// [`clk_get_rate`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_get_rate + #[inline] + pub fn rate(&self) -> Hertz { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_get_rate`]. + Hertz(unsafe { bindings::clk_get_rate(self.as_raw()) }) + } + + /// Set clock's rate. + /// + /// Equivalent to the kernel's [`clk_set_rate`] API. + /// + /// [`clk_set_rate`]: https://docs.kernel.org/core-api/kernel-api.html#c.clk_set_rate + #[inline] + pub fn set_rate(&self, rate: Hertz) -> Result { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for + // [`clk_set_rate`]. + to_result(unsafe { bindings::clk_set_rate(self.as_raw(), rate.as_hz()) }) + } + } + + impl Drop for Clk { + fn drop(&mut self) { + // SAFETY: By the type invariants, self.as_raw() is a valid argument for [`clk_put`]. + unsafe { bindings::clk_put(self.as_raw()) }; + } + } + + /// A reference-counted optional clock. + /// + /// A lightweight wrapper around an optional [`Clk`]. An [`OptionalClk`] represents a [`Clk`] + /// that a driver can function without but may improve performance or enable additional + /// features when available. + /// + /// # Invariants + /// + /// An [`OptionalClk`] instance encapsulates a [`Clk`] with either a valid [`struct clk`] or + /// `NULL` pointer. + /// + /// Instances of this type are reference-counted. Calling [`OptionalClk::get`] ensures that the + /// allocation remains valid for the lifetime of the [`OptionalClk`]. + /// + /// ## Examples + /// + /// The following example demonstrates how to obtain and configure an optional clock for a + /// device. The code functions correctly whether or not the clock is available. + /// + /// ``` + /// use kernel::c_str; + /// use kernel::clk::{OptionalClk, Hertz}; + /// use kernel::device::Device; + /// use kernel::error::Result; + /// + /// fn configure_clk(dev: &Device) -> Result { + /// let clk = OptionalClk::get(dev, Some(c_str!("apb_clk")))?; + /// + /// clk.prepare_enable()?; + /// + /// let expected_rate = Hertz::from_ghz(1); + /// + /// if clk.rate() != expected_rate { + /// clk.set_rate(expected_rate)?; + /// } + /// + /// clk.disable_unprepare(); + /// Ok(()) + /// } + /// ``` + /// + /// [`struct clk`]: https://docs.kernel.org/driver-api/clk.html + pub struct OptionalClk(Clk); + + impl OptionalClk { + /// Gets [`OptionalClk`] corresponding to a [`Device`] and a connection id. + /// + /// Equivalent to the kernel's [`clk_get_optional`] API. + /// + /// [`clk_get_optional`]: + /// https://docs.kernel.org/core-api/kernel-api.html#c.clk_get_optional + pub fn get(dev: &Device, name: Option<&CStr>) -> Result { + let con_id = if let Some(name) = name { + name.as_ptr() + } else { + ptr::null() + }; + + // SAFETY: It is safe to call [`clk_get_optional`] for a valid device pointer. + // + // INVARIANT: The reference-count is decremented when [`OptionalClk`] goes out of + // scope. + Ok(Self(Clk(from_err_ptr(unsafe { + bindings::clk_get_optional(dev.as_raw(), con_id) + })?))) + } + } + + // Make [`OptionalClk`] behave like [`Clk`]. + impl Deref for OptionalClk { + type Target = Clk; + + fn deref(&self) -> &Clk { + &self.0 + } + } +} + +#[cfg(CONFIG_COMMON_CLK)] +pub use common_clk::*; diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 75f78f6bfaa6..3fd7c17cbc06 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -42,6 +42,7 @@ pub mod alloc; pub mod block; #[doc(hidden)] pub mod build_assert; +pub mod clk; pub mod cpumask; pub mod cred; pub mod device; -- cgit v1.2.3 From 3accb57d56a9bcf1cab1e908e88a235e899a2e82 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 8 Jan 2025 16:18:38 +0530 Subject: rust: cpu: Add from_cpu() This implements cpu::from_cpu(), which returns a reference to Device for a CPU. The C struct is created at initialization time for CPUs and is never freed and so ARef isn't returned from this function. The new helper will be used by Rust based cpufreq drivers. Signed-off-by: Viresh Kumar --- rust/kernel/cpu.rs | 30 ++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 31 insertions(+) create mode 100644 rust/kernel/cpu.rs (limited to 'rust/kernel') diff --git a/rust/kernel/cpu.rs b/rust/kernel/cpu.rs new file mode 100644 index 000000000000..10c5c3b25873 --- /dev/null +++ b/rust/kernel/cpu.rs @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Generic CPU definitions. +//! +//! C header: [`include/linux/cpu.h`](srctree/include/linux/cpu.h) + +use crate::{bindings, device::Device, error::Result, prelude::ENODEV}; + +/// Creates a new instance of CPU's device. +/// +/// # Safety +/// +/// Reference counting is not implemented for the CPU device in the C code. When a CPU is +/// hot-unplugged, the corresponding CPU device is unregistered, but its associated memory +/// is not freed. +/// +/// Callers must ensure that the CPU device is not used after it has been unregistered. +/// This can be achieved, for example, by registering a CPU hotplug notifier and removing +/// any references to the CPU device within the notifier's callback. +pub unsafe fn from_cpu(cpu: u32) -> Result<&'static Device> { + // SAFETY: It is safe to call `get_cpu_device()` for any CPU. + let ptr = unsafe { bindings::get_cpu_device(cpu) }; + if ptr.is_null() { + return Err(ENODEV); + } + + // SAFETY: The pointer returned by `get_cpu_device()`, if not `NULL`, is a valid pointer to + // a `struct device` and is never freed by the C code. + Ok(unsafe { Device::as_ref(ptr) }) +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 3fd7c17cbc06..de0a840fcc99 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -43,6 +43,7 @@ pub mod block; #[doc(hidden)] pub mod build_assert; pub mod clk; +pub mod cpu; pub mod cpumask; pub mod cred; pub mod device; -- cgit v1.2.3 From 8f835497b32b59c0ba8b5e1805b7e89dd38cd9f9 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 18 Dec 2023 11:15:13 +0530 Subject: rust: opp: Add initial abstractions for OPP framework Introduce initial Rust abstractions for the Operating Performance Points (OPP) framework. This includes bindings for `struct dev_pm_opp` and `struct dev_pm_opp_data`, laying the groundwork for further OPP integration. Signed-off-by: Viresh Kumar --- rust/kernel/lib.rs | 2 + rust/kernel/opp.rs | 299 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 301 insertions(+) create mode 100644 rust/kernel/opp.rs (limited to 'rust/kernel') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index de0a840fcc99..ea589254b4ac 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -67,6 +67,8 @@ pub mod miscdevice; #[cfg(CONFIG_NET)] pub mod net; pub mod of; +#[cfg(CONFIG_PM_OPP)] +pub mod opp; pub mod page; #[cfg(CONFIG_PCI)] pub mod pci; diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs new file mode 100644 index 000000000000..8f0493a8b6e8 --- /dev/null +++ b/rust/kernel/opp.rs @@ -0,0 +1,299 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Operating performance points. +//! +//! This module provides rust abstractions for interacting with the OPP subsystem. +//! +//! C header: [`include/linux/pm_opp.h`](srctree/include/linux/pm_opp.h) +//! +//! Reference: + +use crate::{ + clk::Hertz, + device::Device, + error::{code::*, to_result, Result}, + ffi::c_ulong, + types::{ARef, AlwaysRefCounted, Opaque}, +}; + +use core::ptr; + +/// The voltage unit. +/// +/// Represents voltage in microvolts, wrapping a [`c_ulong`] value. +/// +/// ## Examples +/// +/// ``` +/// use kernel::opp::MicroVolt; +/// +/// let raw = 90500; +/// let volt = MicroVolt(raw); +/// +/// assert_eq!(usize::from(volt), raw); +/// assert_eq!(volt, MicroVolt(raw)); +/// ``` +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub struct MicroVolt(pub c_ulong); + +impl From for c_ulong { + #[inline] + fn from(volt: MicroVolt) -> Self { + volt.0 + } +} + +/// The power unit. +/// +/// Represents power in microwatts, wrapping a [`c_ulong`] value. +/// +/// ## Examples +/// +/// ``` +/// use kernel::opp::MicroWatt; +/// +/// let raw = 1000000; +/// let power = MicroWatt(raw); +/// +/// assert_eq!(usize::from(power), raw); +/// assert_eq!(power, MicroWatt(raw)); +/// ``` +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub struct MicroWatt(pub c_ulong); + +impl From for c_ulong { + #[inline] + fn from(power: MicroWatt) -> Self { + power.0 + } +} + +/// Handle for a dynamically created [`OPP`]. +/// +/// The associated [`OPP`] is automatically removed when the [`Token`] is dropped. +/// +/// ## Examples +/// +/// The following example demonstrates how to create an [`OPP`] dynamically. +/// +/// ``` +/// use kernel::clk::Hertz; +/// use kernel::device::Device; +/// use kernel::error::Result; +/// use kernel::opp::{Data, MicroVolt, Token}; +/// use kernel::types::ARef; +/// +/// fn create_opp(dev: &ARef, freq: Hertz, volt: MicroVolt, level: u32) -> Result { +/// let data = Data::new(freq, volt, level, false); +/// +/// // OPP is removed once token goes out of scope. +/// data.add_opp(dev) +/// } +/// ``` +pub struct Token { + dev: ARef, + freq: Hertz, +} + +impl Token { + /// Dynamically adds an [`OPP`] and returns a [`Token`] that removes it on drop. + fn new(dev: &ARef, mut data: Data) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_add_dynamic(dev.as_raw(), &mut data.0) })?; + Ok(Self { + dev: dev.clone(), + freq: data.freq(), + }) + } +} + +impl Drop for Token { + fn drop(&mut self) { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + unsafe { bindings::dev_pm_opp_remove(self.dev.as_raw(), self.freq.into()) }; + } +} + +/// OPP data. +/// +/// Rust abstraction for the C `struct dev_pm_opp_data`, used to define operating performance +/// points (OPPs) dynamically. +/// +/// ## Examples +/// +/// The following example demonstrates how to create an [`OPP`] with [`Data`]. +/// +/// ``` +/// use kernel::clk::Hertz; +/// use kernel::device::Device; +/// use kernel::error::Result; +/// use kernel::opp::{Data, MicroVolt, Token}; +/// use kernel::types::ARef; +/// +/// fn create_opp(dev: &ARef, freq: Hertz, volt: MicroVolt, level: u32) -> Result { +/// let data = Data::new(freq, volt, level, false); +/// +/// // OPP is removed once token goes out of scope. +/// data.add_opp(dev) +/// } +/// ``` +#[repr(transparent)] +pub struct Data(bindings::dev_pm_opp_data); + +impl Data { + /// Creates a new instance of [`Data`]. + /// + /// This can be used to define a dynamic OPP to be added to a device. + pub fn new(freq: Hertz, volt: MicroVolt, level: u32, turbo: bool) -> Self { + Self(bindings::dev_pm_opp_data { + turbo, + freq: freq.into(), + u_volt: volt.into(), + level, + }) + } + + /// Adds an [`OPP`] dynamically. + /// + /// Returns a [`Token`] that ensures the OPP is automatically removed + /// when it goes out of scope. + #[inline] + pub fn add_opp(self, dev: &ARef) -> Result { + Token::new(dev, self) + } + + /// Returns the frequency associated with this OPP data. + #[inline] + fn freq(&self) -> Hertz { + Hertz(self.0.freq) + } +} + +/// A reference-counted Operating performance point (OPP). +/// +/// Rust abstraction for the C `struct dev_pm_opp`. +/// +/// # Invariants +/// +/// The pointer stored in `Self` is non-null and valid for the lifetime of the [`OPP`]. +/// +/// Instances of this type are reference-counted. The reference count is incremented by the +/// `dev_pm_opp_get` function and decremented by `dev_pm_opp_put`. The Rust type `ARef` +/// represents a pointer that owns a reference count on the [`OPP`]. +/// +/// A reference to the [`OPP`], &[`OPP`], isn't refcounted by the Rust code. +#[repr(transparent)] +pub struct OPP(Opaque); + +/// SAFETY: It is okay to send the ownership of [`OPP`] across thread boundaries. +unsafe impl Send for OPP {} + +/// SAFETY: It is okay to access [`OPP`] through shared references from other threads because we're +/// either accessing properties that don't change or that are properly synchronised by C code. +unsafe impl Sync for OPP {} + +/// SAFETY: The type invariants guarantee that [`OPP`] is always refcounted. +unsafe impl AlwaysRefCounted for OPP { + fn inc_ref(&self) { + // SAFETY: The existence of a shared reference means that the refcount is nonzero. + unsafe { bindings::dev_pm_opp_get(self.0.get()) }; + } + + unsafe fn dec_ref(obj: ptr::NonNull) { + // SAFETY: The safety requirements guarantee that the refcount is nonzero. + unsafe { bindings::dev_pm_opp_put(obj.cast().as_ptr()) } + } +} + +impl OPP { + /// Creates an owned reference to a [`OPP`] from a valid pointer. + /// + /// The refcount is incremented by the C code and will be decremented by `dec_ref` when the + /// [`ARef`] object is dropped. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid and the refcount of the [`OPP`] is incremented. + /// The caller must also ensure that it doesn't explicitly drop the refcount of the [`OPP`], as + /// the returned [`ARef`] object takes over the refcount increment on the underlying object and + /// the same will be dropped along with it. + pub unsafe fn from_raw_opp_owned(ptr: *mut bindings::dev_pm_opp) -> Result> { + let ptr = ptr::NonNull::new(ptr).ok_or(ENODEV)?; + + // SAFETY: The safety requirements guarantee the validity of the pointer. + // + // INVARIANT: The reference-count is decremented when [`OPP`] goes out of scope. + Ok(unsafe { ARef::from_raw(ptr.cast()) }) + } + + /// Creates a reference to a [`OPP`] from a valid pointer. + /// + /// The refcount is not updated by the Rust API unless the returned reference is converted to + /// an [`ARef`] object. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid and remains valid for the duration of `'a`. + #[inline] + pub unsafe fn from_raw_opp<'a>(ptr: *mut bindings::dev_pm_opp) -> Result<&'a Self> { + // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the + // duration of 'a. The cast is okay because [`OPP`] is `repr(transparent)`. + Ok(unsafe { &*ptr.cast() }) + } + + #[inline] + fn as_raw(&self) -> *mut bindings::dev_pm_opp { + self.0.get() + } + + /// Returns the frequency of an [`OPP`]. + pub fn freq(&self, index: Option) -> Hertz { + let index = index.unwrap_or(0); + + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + Hertz(unsafe { bindings::dev_pm_opp_get_freq_indexed(self.as_raw(), index) }) + } + + /// Returns the voltage of an [`OPP`]. + #[inline] + pub fn voltage(&self) -> MicroVolt { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + MicroVolt(unsafe { bindings::dev_pm_opp_get_voltage(self.as_raw()) }) + } + + /// Returns the level of an [`OPP`]. + #[inline] + pub fn level(&self) -> u32 { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_level(self.as_raw()) } + } + + /// Returns the power of an [`OPP`]. + #[inline] + pub fn power(&self) -> MicroWatt { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + MicroWatt(unsafe { bindings::dev_pm_opp_get_power(self.as_raw()) }) + } + + /// Returns the required pstate of an [`OPP`]. + #[inline] + pub fn required_pstate(&self, index: u32) -> u32 { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_get_required_pstate(self.as_raw(), index) } + } + + /// Returns true if the [`OPP`] is turbo. + #[inline] + pub fn is_turbo(&self) -> bool { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe to + // use it. + unsafe { bindings::dev_pm_opp_is_turbo(self.as_raw()) } + } +} -- cgit v1.2.3 From d52c7e868fbc134d88bb04d5909f2df2f9da5202 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 18 Dec 2023 11:15:13 +0530 Subject: rust: opp: Add abstractions for the OPP table Introduce Rust abstractions for `struct opp_table`, enabling access to OPP tables from Rust. Signed-off-by: Viresh Kumar --- rust/kernel/opp.rs | 487 ++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 486 insertions(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs index 8f0493a8b6e8..26a0ecfe046a 100644 --- a/rust/kernel/opp.rs +++ b/rust/kernel/opp.rs @@ -10,8 +10,9 @@ use crate::{ clk::Hertz, + cpumask::{Cpumask, CpumaskVar}, device::Device, - error::{code::*, to_result, Result}, + error::{code::*, from_err_ptr, to_result, Error, Result}, ffi::c_ulong, types::{ARef, AlwaysRefCounted, Opaque}, }; @@ -171,6 +172,469 @@ impl Data { } } +/// [`OPP`] search options. +/// +/// ## Examples +/// +/// Defines how to search for an [`OPP`] in a [`Table`] relative to a frequency. +/// +/// ``` +/// use kernel::clk::Hertz; +/// use kernel::error::Result; +/// use kernel::opp::{OPP, SearchType, Table}; +/// use kernel::types::ARef; +/// +/// fn find_opp(table: &Table, freq: Hertz) -> Result> { +/// let opp = table.opp_from_freq(freq, Some(true), None, SearchType::Exact)?; +/// +/// pr_info!("OPP frequency is: {:?}\n", opp.freq(None)); +/// pr_info!("OPP voltage is: {:?}\n", opp.voltage()); +/// pr_info!("OPP level is: {}\n", opp.level()); +/// pr_info!("OPP power is: {:?}\n", opp.power()); +/// +/// Ok(opp) +/// } +/// ``` +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub enum SearchType { + /// Match the exact frequency. + Exact, + /// Find the highest frequency less than or equal to the given value. + Floor, + /// Find the lowest frequency greater than or equal to the given value. + Ceil, +} + +/// A reference-counted OPP table. +/// +/// Rust abstraction for the C `struct opp_table`. +/// +/// # Invariants +/// +/// The pointer stored in `Self` is non-null and valid for the lifetime of the [`Table`]. +/// +/// Instances of this type are reference-counted. +/// +/// ## Examples +/// +/// The following example demonstrates how to get OPP [`Table`] for a [`Cpumask`] and set its +/// frequency. +/// +/// ``` +/// use kernel::clk::Hertz; +/// use kernel::cpumask::Cpumask; +/// use kernel::device::Device; +/// use kernel::error::Result; +/// use kernel::opp::Table; +/// use kernel::types::ARef; +/// +/// fn get_table(dev: &ARef, mask: &mut Cpumask, freq: Hertz) -> Result { +/// let mut opp_table = Table::from_of_cpumask(dev, mask)?; +/// +/// if opp_table.opp_count()? == 0 { +/// return Err(EINVAL); +/// } +/// +/// pr_info!("Max transition latency is: {} ns\n", opp_table.max_transition_latency_ns()); +/// pr_info!("Suspend frequency is: {:?}\n", opp_table.suspend_freq()); +/// +/// opp_table.set_rate(freq)?; +/// Ok(opp_table) +/// } +/// ``` +pub struct Table { + ptr: *mut bindings::opp_table, + dev: ARef, + #[allow(dead_code)] + em: bool, + #[allow(dead_code)] + of: bool, + cpus: Option, +} + +/// SAFETY: It is okay to send ownership of [`Table`] across thread boundaries. +unsafe impl Send for Table {} + +/// SAFETY: It is okay to access [`Table`] through shared references from other threads because +/// we're either accessing properties that don't change or that are properly synchronised by C code. +unsafe impl Sync for Table {} + +impl Table { + /// Creates a new reference-counted [`Table`] from a raw pointer. + /// + /// # Safety + /// + /// Callers must ensure that `ptr` is valid and non-null. + unsafe fn from_raw_table(ptr: *mut bindings::opp_table, dev: &ARef) -> Self { + // SAFETY: By the safety requirements, ptr is valid and its refcount will be incremented. + // + // INVARIANT: The reference-count is decremented when [`Table`] goes out of scope. + unsafe { bindings::dev_pm_opp_get_opp_table_ref(ptr) }; + + Self { + ptr, + dev: dev.clone(), + em: false, + of: false, + cpus: None, + } + } + + /// Creates a new reference-counted [`Table`] instance for a [`Device`]. + pub fn from_dev(dev: &Device) -> Result { + // SAFETY: The requirements are satisfied by the existence of the [`Device`] and its safety + // requirements. + // + // INVARIANT: The reference-count is incremented by the C code and is decremented when + // [`Table`] goes out of scope. + let ptr = from_err_ptr(unsafe { bindings::dev_pm_opp_get_opp_table(dev.as_raw()) })?; + + Ok(Self { + ptr, + dev: dev.into(), + em: false, + of: false, + cpus: None, + }) + } + + /// Creates a new reference-counted [`Table`] instance for a [`Device`] based on device tree + /// entries. + #[cfg(CONFIG_OF)] + pub fn from_of(dev: &ARef, index: i32) -> Result { + // SAFETY: The requirements are satisfied by the existence of the [`Device`] and its safety + // requirements. + // + // INVARIANT: The reference-count is incremented by the C code and is decremented when + // [`Table`] goes out of scope. + to_result(unsafe { bindings::dev_pm_opp_of_add_table_indexed(dev.as_raw(), index) })?; + + // Get the newly created [`Table`]. + let mut table = Self::from_dev(dev)?; + table.of = true; + + Ok(table) + } + + /// Remove device tree based [`Table`]. + #[cfg(CONFIG_OF)] + #[inline] + fn remove_of(&self) { + // SAFETY: The requirements are satisfied by the existence of the [`Device`] and its safety + // requirements. We took the reference from [`from_of`] earlier, it is safe to drop the + // same now. + unsafe { bindings::dev_pm_opp_of_remove_table(self.dev.as_raw()) }; + } + + /// Creates a new reference-counted [`Table`] instance for a [`Cpumask`] based on device tree + /// entries. + #[cfg(CONFIG_OF)] + pub fn from_of_cpumask(dev: &Device, cpumask: &mut Cpumask) -> Result { + // SAFETY: The cpumask is valid and the returned pointer will be owned by the [`Table`] + // instance. + // + // INVARIANT: The reference-count is incremented by the C code and is decremented when + // [`Table`] goes out of scope. + to_result(unsafe { bindings::dev_pm_opp_of_cpumask_add_table(cpumask.as_raw()) })?; + + // Fetch the newly created table. + let mut table = Self::from_dev(dev)?; + table.cpus = Some(CpumaskVar::try_clone(cpumask)?); + + Ok(table) + } + + /// Remove device tree based [`Table`] for a [`Cpumask`]. + #[cfg(CONFIG_OF)] + #[inline] + fn remove_of_cpumask(&self, cpumask: &Cpumask) { + // SAFETY: The cpumask is valid and we took the reference from [`from_of_cpumask`] earlier, + // it is safe to drop the same now. + unsafe { bindings::dev_pm_opp_of_cpumask_remove_table(cpumask.as_raw()) }; + } + + /// Returns the number of [`OPP`]s in the [`Table`]. + pub fn opp_count(&self) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + let ret = unsafe { bindings::dev_pm_opp_get_opp_count(self.dev.as_raw()) }; + if ret < 0 { + Err(Error::from_errno(ret)) + } else { + Ok(ret as u32) + } + } + + /// Returns max clock latency (in nanoseconds) of the [`OPP`]s in the [`Table`]. + #[inline] + pub fn max_clock_latency_ns(&self) -> usize { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + unsafe { bindings::dev_pm_opp_get_max_clock_latency(self.dev.as_raw()) } + } + + /// Returns max volt latency (in nanoseconds) of the [`OPP`]s in the [`Table`]. + #[inline] + pub fn max_volt_latency_ns(&self) -> usize { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + unsafe { bindings::dev_pm_opp_get_max_volt_latency(self.dev.as_raw()) } + } + + /// Returns max transition latency (in nanoseconds) of the [`OPP`]s in the [`Table`]. + #[inline] + pub fn max_transition_latency_ns(&self) -> usize { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + unsafe { bindings::dev_pm_opp_get_max_transition_latency(self.dev.as_raw()) } + } + + /// Returns the suspend [`OPP`]'s frequency. + #[inline] + pub fn suspend_freq(&self) -> Hertz { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + Hertz(unsafe { bindings::dev_pm_opp_get_suspend_opp_freq(self.dev.as_raw()) }) + } + + /// Synchronizes regulators used by the [`Table`]. + #[inline] + pub fn sync_regulators(&self) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_sync_regulators(self.dev.as_raw()) }) + } + + /// Gets sharing CPUs. + #[inline] + pub fn sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_get_sharing_cpus(dev.as_raw(), cpumask.as_raw()) }) + } + + /// Sets sharing CPUs. + pub fn set_sharing_cpus(&mut self, cpumask: &mut Cpumask) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { + bindings::dev_pm_opp_set_sharing_cpus(self.dev.as_raw(), cpumask.as_raw()) + })?; + + if let Some(mask) = self.cpus.as_mut() { + // Update the cpumask as this will be used while removing the table. + cpumask.copy(mask); + } + + Ok(()) + } + + /// Gets sharing CPUs from device tree. + #[cfg(CONFIG_OF)] + #[inline] + pub fn of_sharing_cpus(dev: &Device, cpumask: &mut Cpumask) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { + bindings::dev_pm_opp_of_get_sharing_cpus(dev.as_raw(), cpumask.as_raw()) + }) + } + + /// Updates the voltage value for an [`OPP`]. + #[inline] + pub fn adjust_voltage( + &self, + freq: Hertz, + volt: MicroVolt, + volt_min: MicroVolt, + volt_max: MicroVolt, + ) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { + bindings::dev_pm_opp_adjust_voltage( + self.dev.as_raw(), + freq.into(), + volt.into(), + volt_min.into(), + volt_max.into(), + ) + }) + } + + /// Configures device with [`OPP`] matching the frequency value. + #[inline] + pub fn set_rate(&self, freq: Hertz) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_set_rate(self.dev.as_raw(), freq.into()) }) + } + + /// Configures device with [`OPP`]. + #[inline] + pub fn set_opp(&self, opp: &OPP) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_set_opp(self.dev.as_raw(), opp.as_raw()) }) + } + + /// Finds [`OPP`] based on frequency. + pub fn opp_from_freq( + &self, + freq: Hertz, + available: Option, + index: Option, + stype: SearchType, + ) -> Result> { + let raw_dev = self.dev.as_raw(); + let index = index.unwrap_or(0); + let mut rate = freq.into(); + + let ptr = from_err_ptr(match stype { + SearchType::Exact => { + if let Some(available) = available { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and + // its safety requirements. The returned pointer will be owned by the new + // [`OPP`] instance. + unsafe { + bindings::dev_pm_opp_find_freq_exact_indexed( + raw_dev, rate, index, available, + ) + } + } else { + return Err(EINVAL); + } + } + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Ceil => unsafe { + bindings::dev_pm_opp_find_freq_ceil_indexed(raw_dev, &mut rate, index) + }, + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Floor => unsafe { + bindings::dev_pm_opp_find_freq_floor_indexed(raw_dev, &mut rate, index) + }, + })?; + + // SAFETY: The `ptr` is guaranteed by the C code to be valid. + unsafe { OPP::from_raw_opp_owned(ptr) } + } + + /// Finds [`OPP`] based on level. + pub fn opp_from_level(&self, mut level: u32, stype: SearchType) -> Result> { + let raw_dev = self.dev.as_raw(); + + let ptr = from_err_ptr(match stype { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Exact => unsafe { bindings::dev_pm_opp_find_level_exact(raw_dev, level) }, + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Ceil => unsafe { + bindings::dev_pm_opp_find_level_ceil(raw_dev, &mut level) + }, + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Floor => unsafe { + bindings::dev_pm_opp_find_level_floor(raw_dev, &mut level) + }, + })?; + + // SAFETY: The `ptr` is guaranteed by the C code to be valid. + unsafe { OPP::from_raw_opp_owned(ptr) } + } + + /// Finds [`OPP`] based on bandwidth. + pub fn opp_from_bw(&self, mut bw: u32, index: i32, stype: SearchType) -> Result> { + let raw_dev = self.dev.as_raw(); + + let ptr = from_err_ptr(match stype { + // The OPP core doesn't support this yet. + SearchType::Exact => return Err(EINVAL), + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Ceil => unsafe { + bindings::dev_pm_opp_find_bw_ceil(raw_dev, &mut bw, index) + }, + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The returned pointer will be owned by the new [`OPP`] instance. + SearchType::Floor => unsafe { + bindings::dev_pm_opp_find_bw_floor(raw_dev, &mut bw, index) + }, + })?; + + // SAFETY: The `ptr` is guaranteed by the C code to be valid. + unsafe { OPP::from_raw_opp_owned(ptr) } + } + + /// Enables the [`OPP`]. + #[inline] + pub fn enable_opp(&self, freq: Hertz) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_enable(self.dev.as_raw(), freq.into()) }) + } + + /// Disables the [`OPP`]. + #[inline] + pub fn disable_opp(&self, freq: Hertz) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { bindings::dev_pm_opp_disable(self.dev.as_raw(), freq.into()) }) + } + + /// Registers with the Energy model. + #[cfg(CONFIG_OF)] + pub fn of_register_em(&mut self, cpumask: &mut Cpumask) -> Result { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { + bindings::dev_pm_opp_of_register_em(self.dev.as_raw(), cpumask.as_raw()) + })?; + + self.em = true; + Ok(()) + } + + /// Unregisters with the Energy model. + #[cfg(all(CONFIG_OF, CONFIG_ENERGY_MODEL))] + #[inline] + fn of_unregister_em(&self) { + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. We registered with the EM framework earlier, it is safe to unregister now. + unsafe { bindings::em_dev_unregister_perf_domain(self.dev.as_raw()) }; + } +} + +impl Drop for Table { + fn drop(&mut self) { + // SAFETY: By the type invariants, we know that `self` owns a reference, so it is safe + // to relinquish it now. + unsafe { bindings::dev_pm_opp_put_opp_table(self.ptr) }; + + #[cfg(CONFIG_OF)] + { + #[cfg(CONFIG_ENERGY_MODEL)] + if self.em { + self.of_unregister_em(); + } + + if self.of { + self.remove_of(); + } else if let Some(cpumask) = self.cpus.take() { + self.remove_of_cpumask(&cpumask); + } + } + } +} + /// A reference-counted Operating performance point (OPP). /// /// Rust abstraction for the C `struct dev_pm_opp`. @@ -184,6 +648,27 @@ impl Data { /// represents a pointer that owns a reference count on the [`OPP`]. /// /// A reference to the [`OPP`], &[`OPP`], isn't refcounted by the Rust code. +/// +/// ## Examples +/// +/// The following example demonstrates how to get [`OPP`] corresponding to a frequency value and +/// configure the device with it. +/// +/// ``` +/// use kernel::clk::Hertz; +/// use kernel::error::Result; +/// use kernel::opp::{SearchType, Table}; +/// +/// fn configure_opp(table: &Table, freq: Hertz) -> Result { +/// let opp = table.opp_from_freq(freq, Some(true), None, SearchType::Exact)?; +/// +/// if opp.freq(None) != freq { +/// return Err(EINVAL); +/// } +/// +/// table.set_opp(&opp) +/// } +/// ``` #[repr(transparent)] pub struct OPP(Opaque); -- cgit v1.2.3 From ce32e2d47ce6c472a931eabe53f841c62b6abfe5 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 18 Dec 2023 11:15:13 +0530 Subject: rust: opp: Add abstractions for the configuration options Introduce Rust abstractions for the OPP core configuration options, enabling safe access to various configurable aspects of the OPP framework. Signed-off-by: Viresh Kumar --- rust/kernel/opp.rs | 295 ++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 293 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs index 26a0ecfe046a..5293d878cb55 100644 --- a/rust/kernel/opp.rs +++ b/rust/kernel/opp.rs @@ -12,12 +12,29 @@ use crate::{ clk::Hertz, cpumask::{Cpumask, CpumaskVar}, device::Device, - error::{code::*, from_err_ptr, to_result, Error, Result}, + error::{code::*, from_err_ptr, from_result, to_result, Error, Result, VTABLE_DEFAULT_ERROR}, ffi::c_ulong, + prelude::*, + str::CString, types::{ARef, AlwaysRefCounted, Opaque}, }; -use core::ptr; +use core::{marker::PhantomData, ptr}; + +use macros::vtable; + +/// Creates a null-terminated slice of pointers to [`Cstring`]s. +fn to_c_str_array(names: &[CString]) -> Result> { + // Allocated a null-terminated vector of pointers. + let mut list = KVec::with_capacity(names.len() + 1, GFP_KERNEL)?; + + for name in names.iter() { + list.push(name.as_ptr() as _, GFP_KERNEL)?; + } + + list.push(ptr::null(), GFP_KERNEL)?; + Ok(list) +} /// The voltage unit. /// @@ -205,6 +222,280 @@ pub enum SearchType { Ceil, } +/// OPP configuration callbacks. +/// +/// Implement this trait to customize OPP clock and regulator setup for your device. +#[vtable] +pub trait ConfigOps { + /// This is typically used to scale clocks when transitioning between OPPs. + #[inline] + fn config_clks(_dev: &Device, _table: &Table, _opp: &OPP, _scaling_down: bool) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// This provides access to the old and new OPPs, allowing for safe regulator adjustments. + #[inline] + fn config_regulators( + _dev: &Device, + _opp_old: &OPP, + _opp_new: &OPP, + _data: *mut *mut bindings::regulator, + _count: u32, + ) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } +} + +/// OPP configuration token. +/// +/// Returned by the OPP core when configuration is applied to a [`Device`]. The associated +/// configuration is automatically cleared when the token is dropped. +pub struct ConfigToken(i32); + +impl Drop for ConfigToken { + fn drop(&mut self) { + // SAFETY: This is the same token value returned by the C code via `dev_pm_opp_set_config`. + unsafe { bindings::dev_pm_opp_clear_config(self.0) }; + } +} + +/// OPP configurations. +/// +/// Rust abstraction for the C `struct dev_pm_opp_config`. +/// +/// ## Examples +/// +/// The following example demonstrates how to set OPP property-name configuration for a [`Device`]. +/// +/// ``` +/// use kernel::device::Device; +/// use kernel::error::Result; +/// use kernel::opp::{Config, ConfigOps, ConfigToken}; +/// use kernel::str::CString; +/// use kernel::types::ARef; +/// use kernel::macros::vtable; +/// +/// #[derive(Default)] +/// struct Driver; +/// +/// #[vtable] +/// impl ConfigOps for Driver {} +/// +/// fn configure(dev: &ARef) -> Result { +/// let name = CString::try_from_fmt(fmt!("{}", "slow"))?; +/// +/// // The OPP configuration is cleared once the [`ConfigToken`] goes out of scope. +/// Config::::new() +/// .set_prop_name(name)? +/// .set(dev) +/// } +/// ``` +#[derive(Default)] +pub struct Config +where + T: Default, +{ + clk_names: Option>, + prop_name: Option, + regulator_names: Option>, + supported_hw: Option>, + + // Tuple containing (required device, index) + required_dev: Option<(ARef, u32)>, + _data: PhantomData, +} + +impl Config { + /// Creates a new instance of [`Config`]. + #[inline] + pub fn new() -> Self { + Self::default() + } + + /// Initializes clock names. + pub fn set_clk_names(mut self, names: KVec) -> Result { + if self.clk_names.is_some() { + return Err(EBUSY); + } + + if names.is_empty() { + return Err(EINVAL); + } + + self.clk_names = Some(names); + Ok(self) + } + + /// Initializes property name. + pub fn set_prop_name(mut self, name: CString) -> Result { + if self.prop_name.is_some() { + return Err(EBUSY); + } + + self.prop_name = Some(name); + Ok(self) + } + + /// Initializes regulator names. + pub fn set_regulator_names(mut self, names: KVec) -> Result { + if self.regulator_names.is_some() { + return Err(EBUSY); + } + + if names.is_empty() { + return Err(EINVAL); + } + + self.regulator_names = Some(names); + + Ok(self) + } + + /// Initializes required devices. + pub fn set_required_dev(mut self, dev: ARef, index: u32) -> Result { + if self.required_dev.is_some() { + return Err(EBUSY); + } + + self.required_dev = Some((dev, index)); + Ok(self) + } + + /// Initializes supported hardware. + pub fn set_supported_hw(mut self, hw: KVec) -> Result { + if self.supported_hw.is_some() { + return Err(EBUSY); + } + + if hw.is_empty() { + return Err(EINVAL); + } + + self.supported_hw = Some(hw); + Ok(self) + } + + /// Sets the configuration with the OPP core. + /// + /// The returned [`ConfigToken`] will remove the configuration when dropped. + pub fn set(self, dev: &Device) -> Result { + let (_clk_list, clk_names) = match &self.clk_names { + Some(x) => { + let list = to_c_str_array(x)?; + let ptr = list.as_ptr(); + (Some(list), ptr) + } + None => (None, ptr::null()), + }; + + let (_regulator_list, regulator_names) = match &self.regulator_names { + Some(x) => { + let list = to_c_str_array(x)?; + let ptr = list.as_ptr(); + (Some(list), ptr) + } + None => (None, ptr::null()), + }; + + let prop_name = self + .prop_name + .as_ref() + .map_or(ptr::null(), |p| p.as_char_ptr()); + + let (supported_hw, supported_hw_count) = self + .supported_hw + .as_ref() + .map_or((ptr::null(), 0), |hw| (hw.as_ptr(), hw.len() as u32)); + + let (required_dev, required_dev_index) = self + .required_dev + .as_ref() + .map_or((ptr::null_mut(), 0), |(dev, idx)| (dev.as_raw(), *idx)); + + let mut config = bindings::dev_pm_opp_config { + clk_names, + config_clks: if T::HAS_CONFIG_CLKS { + Some(Self::config_clks) + } else { + None + }, + prop_name, + regulator_names, + config_regulators: if T::HAS_CONFIG_REGULATORS { + Some(Self::config_regulators) + } else { + None + }, + supported_hw, + supported_hw_count, + + required_dev, + required_dev_index, + }; + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. The OPP core guarantees not to access fields of [`Config`] after this call + // and so we don't need to save a copy of them for future use. + let ret = unsafe { bindings::dev_pm_opp_set_config(dev.as_raw(), &mut config) }; + if ret < 0 { + Err(Error::from_errno(ret)) + } else { + Ok(ConfigToken(ret)) + } + } + + /// Config's clk callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn config_clks( + dev: *mut bindings::device, + opp_table: *mut bindings::opp_table, + opp: *mut bindings::dev_pm_opp, + _data: *mut kernel::ffi::c_void, + scaling_down: bool, + ) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: 'dev' is guaranteed by the C code to be valid. + let dev = unsafe { Device::get_device(dev) }; + T::config_clks( + &dev, + // SAFETY: 'opp_table' is guaranteed by the C code to be valid. + &unsafe { Table::from_raw_table(opp_table, &dev) }, + // SAFETY: 'opp' is guaranteed by the C code to be valid. + unsafe { OPP::from_raw_opp(opp)? }, + scaling_down, + ) + .map(|()| 0) + }) + } + + /// Config's regulator callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn config_regulators( + dev: *mut bindings::device, + old_opp: *mut bindings::dev_pm_opp, + new_opp: *mut bindings::dev_pm_opp, + regulators: *mut *mut bindings::regulator, + count: kernel::ffi::c_uint, + ) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: 'dev' is guaranteed by the C code to be valid. + let dev = unsafe { Device::get_device(dev) }; + T::config_regulators( + &dev, + // SAFETY: 'old_opp' is guaranteed by the C code to be valid. + unsafe { OPP::from_raw_opp(old_opp)? }, + // SAFETY: 'new_opp' is guaranteed by the C code to be valid. + unsafe { OPP::from_raw_opp(new_opp)? }, + regulators, + count, + ) + .map(|()| 0) + }) + } +} + /// A reference-counted OPP table. /// /// Rust abstraction for the C `struct opp_table`. -- cgit v1.2.3 From 2207856ff0bc8d953d6e89bda70b8978c2de8bab Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 7 Jan 2025 12:51:08 +0530 Subject: rust: cpufreq: Add initial abstractions for cpufreq framework Introduce initial Rust abstractions for the cpufreq core. This includes basic representations for cpufreq flags, relation types, and the cpufreq table. Signed-off-by: Viresh Kumar --- rust/kernel/cpufreq.rs | 365 +++++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 + 2 files changed, 367 insertions(+) create mode 100644 rust/kernel/cpufreq.rs (limited to 'rust/kernel') diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs new file mode 100644 index 000000000000..94fa63bda75a --- /dev/null +++ b/rust/kernel/cpufreq.rs @@ -0,0 +1,365 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! CPU frequency scaling. +//! +//! This module provides rust abstractions for interacting with the cpufreq subsystem. +//! +//! C header: [`include/linux/cpufreq.h`](srctree/include/linux/cpufreq.h) +//! +//! Reference: + +use crate::{ + clk::Hertz, + error::{code::*, to_result, Result}, + ffi::c_ulong, + prelude::*, + types::Opaque, +}; + +use core::{ops::Deref, pin::Pin}; + +/// Default transition latency value in nanoseconds. +pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32; + +/// CPU frequency driver flags. +pub mod flags { + /// Driver needs to update internal limits even if frequency remains unchanged. + pub const NEED_UPDATE_LIMITS: u16 = 1 << 0; + + /// Platform where constants like `loops_per_jiffy` are unaffected by frequency changes. + pub const CONST_LOOPS: u16 = 1 << 1; + + /// Register driver as a thermal cooling device automatically. + pub const IS_COOLING_DEV: u16 = 1 << 2; + + /// Supports multiple clock domains with per-policy governors in `cpu/cpuN/cpufreq/`. + pub const HAVE_GOVERNOR_PER_POLICY: u16 = 1 << 3; + + /// Allows post-change notifications outside of the `target()` routine. + pub const ASYNC_NOTIFICATION: u16 = 1 << 4; + + /// Ensure CPU starts at a valid frequency from the driver's freq-table. + pub const NEED_INITIAL_FREQ_CHECK: u16 = 1 << 5; + + /// Disallow governors with `dynamic_switching` capability. + pub const NO_AUTO_DYNAMIC_SWITCHING: u16 = 1 << 6; +} + +/// Relations from the C code. +const CPUFREQ_RELATION_L: u32 = 0; +const CPUFREQ_RELATION_H: u32 = 1; +const CPUFREQ_RELATION_C: u32 = 2; + +/// Can be used with any of the above values. +const CPUFREQ_RELATION_E: u32 = 1 << 2; + +/// CPU frequency selection relations. +/// +/// CPU frequency selection relations, each optionally marked as "efficient". +#[derive(Copy, Clone, Debug, Eq, PartialEq)] +pub enum Relation { + /// Select the lowest frequency at or above target. + Low(bool), + /// Select the highest frequency below or at target. + High(bool), + /// Select the closest frequency to the target. + Close(bool), +} + +impl Relation { + // Construct from a C-compatible `u32` value. + fn new(val: u32) -> Result { + let efficient = val & CPUFREQ_RELATION_E != 0; + + Ok(match val & !CPUFREQ_RELATION_E { + CPUFREQ_RELATION_L => Self::Low(efficient), + CPUFREQ_RELATION_H => Self::High(efficient), + CPUFREQ_RELATION_C => Self::Close(efficient), + _ => return Err(EINVAL), + }) + } +} + +impl From for u32 { + // Convert to a C-compatible `u32` value. + fn from(rel: Relation) -> Self { + let (mut val, efficient) = match rel { + Relation::Low(e) => (CPUFREQ_RELATION_L, e), + Relation::High(e) => (CPUFREQ_RELATION_H, e), + Relation::Close(e) => (CPUFREQ_RELATION_C, e), + }; + + if efficient { + val |= CPUFREQ_RELATION_E; + } + + val + } +} + +/// Policy data. +/// +/// Rust abstraction for the C `struct cpufreq_policy_data`. +/// +/// # Invariants +/// +/// A [`PolicyData`] instance always corresponds to a valid C `struct cpufreq_policy_data`. +/// +/// The callers must ensure that the `struct cpufreq_policy_data` is valid for access and remains +/// valid for the lifetime of the returned reference. +#[repr(transparent)] +pub struct PolicyData(Opaque); + +impl PolicyData { + /// Creates a mutable reference to an existing `struct cpufreq_policy_data` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime + /// of the returned reference. + #[inline] + pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpufreq_policy_data) -> &'a mut Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the + // lifetime of the returned reference. + unsafe { &mut *ptr.cast() } + } + + /// Returns a raw pointer to the underlying C `cpufreq_policy_data`. + #[inline] + pub fn as_raw(&self) -> *mut bindings::cpufreq_policy_data { + let this: *const Self = self; + this.cast_mut().cast() + } + + /// Wrapper for `cpufreq_generic_frequency_table_verify`. + #[inline] + pub fn generic_verify(&self) -> Result { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + to_result(unsafe { bindings::cpufreq_generic_frequency_table_verify(self.as_raw()) }) + } +} + +/// The frequency table index. +/// +/// Represents index with a frequency table. +/// +/// # Invariants +/// +/// The index must correspond to a valid entry in the [`Table`] it is used for. +#[derive(Copy, Clone, PartialEq, Eq, Debug)] +pub struct TableIndex(usize); + +impl TableIndex { + /// Creates an instance of [`TableIndex`]. + /// + /// # Safety + /// + /// The caller must ensure that `index` correspond to a valid entry in the [`Table`] it is used + /// for. + pub unsafe fn new(index: usize) -> Self { + // INVARIANT: The caller ensures that `index` correspond to a valid entry in the [`Table`]. + Self(index) + } +} + +impl From for usize { + #[inline] + fn from(index: TableIndex) -> Self { + index.0 + } +} + +/// CPU frequency table. +/// +/// Rust abstraction for the C `struct cpufreq_frequency_table`. +/// +/// # Invariants +/// +/// A [`Table`] instance always corresponds to a valid C `struct cpufreq_frequency_table`. +/// +/// The callers must ensure that the `struct cpufreq_frequency_table` is valid for access and +/// remains valid for the lifetime of the returned reference. +/// +/// ## Examples +/// +/// The following example demonstrates how to read a frequency value from [`Table`]. +/// +/// ``` +/// use kernel::cpufreq::{Policy, TableIndex}; +/// +/// fn show_freq(policy: &Policy) -> Result { +/// let table = policy.freq_table()?; +/// +/// // SAFETY: Index is a valid entry in the table. +/// let index = unsafe { TableIndex::new(0) }; +/// +/// pr_info!("The frequency at index 0 is: {:?}\n", table.freq(index)?); +/// pr_info!("The flags at index 0 is: {}\n", table.flags(index)); +/// pr_info!("The data at index 0 is: {}\n", table.data(index)); +/// Ok(()) +/// } +/// ``` +#[repr(transparent)] +pub struct Table(Opaque); + +impl Table { + /// Creates a reference to an existing C `struct cpufreq_frequency_table` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime + /// of the returned reference. + #[inline] + pub unsafe fn from_raw<'a>(ptr: *const bindings::cpufreq_frequency_table) -> &'a Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the + // lifetime of the returned reference. + unsafe { &*ptr.cast() } + } + + /// Returns the raw mutable pointer to the C `struct cpufreq_frequency_table`. + #[inline] + pub fn as_raw(&self) -> *mut bindings::cpufreq_frequency_table { + let this: *const Self = self; + this.cast_mut().cast() + } + + /// Returns frequency at `index` in the [`Table`]. + #[inline] + pub fn freq(&self, index: TableIndex) -> Result { + // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is + // guaranteed to be valid by its safety requirements. + Ok(Hertz::from_khz(unsafe { + (*self.as_raw().add(index.into())).frequency.try_into()? + })) + } + + /// Returns flags at `index` in the [`Table`]. + #[inline] + pub fn flags(&self, index: TableIndex) -> u32 { + // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is + // guaranteed to be valid by its safety requirements. + unsafe { (*self.as_raw().add(index.into())).flags } + } + + /// Returns data at `index` in the [`Table`]. + #[inline] + pub fn data(&self, index: TableIndex) -> u32 { + // SAFETY: By the type invariant, the pointer stored in `self` is valid and `index` is + // guaranteed to be valid by its safety requirements. + unsafe { (*self.as_raw().add(index.into())).driver_data } + } +} + +/// CPU frequency table owned and pinned in memory, created from a [`TableBuilder`]. +pub struct TableBox { + entries: Pin>, +} + +impl TableBox { + /// Constructs a new [`TableBox`] from a [`KVec`] of entries. + /// + /// # Errors + /// + /// Returns `EINVAL` if the entries list is empty. + #[inline] + fn new(entries: KVec) -> Result { + if entries.is_empty() { + return Err(EINVAL); + } + + Ok(Self { + // Pin the entries to memory, since we are passing its pointer to the C code. + entries: Pin::new(entries), + }) + } + + /// Returns a raw pointer to the underlying C `cpufreq_frequency_table`. + #[inline] + fn as_raw(&self) -> *const bindings::cpufreq_frequency_table { + // The pointer is valid until the table gets dropped. + self.entries.as_ptr() + } +} + +impl Deref for TableBox { + type Target = Table; + + fn deref(&self) -> &Self::Target { + // SAFETY: The caller owns TableBox, it is safe to deref. + unsafe { Self::Target::from_raw(self.as_raw()) } + } +} + +/// CPU frequency table builder. +/// +/// This is used by the CPU frequency drivers to build a frequency table dynamically. +/// +/// ## Examples +/// +/// The following example demonstrates how to create a CPU frequency table. +/// +/// ``` +/// use kernel::cpufreq::{TableBuilder, TableIndex}; +/// use kernel::clk::Hertz; +/// +/// let mut builder = TableBuilder::new(); +/// +/// // Adds few entries to the table. +/// builder.add(Hertz::from_mhz(700), 0, 1).unwrap(); +/// builder.add(Hertz::from_mhz(800), 2, 3).unwrap(); +/// builder.add(Hertz::from_mhz(900), 4, 5).unwrap(); +/// builder.add(Hertz::from_ghz(1), 6, 7).unwrap(); +/// +/// let table = builder.to_table().unwrap(); +/// +/// // SAFETY: Index values correspond to valid entries in the table. +/// let (index0, index2) = unsafe { (TableIndex::new(0), TableIndex::new(2)) }; +/// +/// assert_eq!(table.freq(index0), Ok(Hertz::from_mhz(700))); +/// assert_eq!(table.flags(index0), 0); +/// assert_eq!(table.data(index0), 1); +/// +/// assert_eq!(table.freq(index2), Ok(Hertz::from_mhz(900))); +/// assert_eq!(table.flags(index2), 4); +/// assert_eq!(table.data(index2), 5); +/// ``` +#[derive(Default)] +#[repr(transparent)] +pub struct TableBuilder { + entries: KVec, +} + +impl TableBuilder { + /// Creates a new instance of [`TableBuilder`]. + #[inline] + pub fn new() -> Self { + Self { + entries: KVec::new(), + } + } + + /// Adds a new entry to the table. + pub fn add(&mut self, freq: Hertz, flags: u32, driver_data: u32) -> Result { + // Adds the new entry at the end of the vector. + Ok(self.entries.push( + bindings::cpufreq_frequency_table { + flags, + driver_data, + frequency: freq.as_khz() as u32, + }, + GFP_KERNEL, + )?) + } + + /// Consumes the [`TableBuilder`] and returns [`TableBox`]. + pub fn to_table(mut self) -> Result { + // Add last entry to the table. + self.add(Hertz(c_ulong::MAX), 0, 0)?; + + TableBox::new(self.entries) + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index ea589254b4ac..133ebee4f9d3 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -44,6 +44,8 @@ pub mod block; pub mod build_assert; pub mod clk; pub mod cpu; +#[cfg(CONFIG_CPU_FREQ)] +pub mod cpufreq; pub mod cpumask; pub mod cred; pub mod device; -- cgit v1.2.3 From 6ebdd7c9317737123b260a24e2780018008f1295 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 7 May 2025 15:32:25 +0530 Subject: rust: cpufreq: Extend abstractions for policy and driver ops Extend the cpufreq abstractions to include support for policy handling and driver operations. Signed-off-by: Viresh Kumar --- rust/kernel/cpufreq.rs | 463 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 461 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs index 94fa63bda75a..1bc208b91822 100644 --- a/rust/kernel/cpufreq.rs +++ b/rust/kernel/cpufreq.rs @@ -10,13 +10,25 @@ use crate::{ clk::Hertz, - error::{code::*, to_result, Result}, + cpumask, + device::Device, + error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR}, ffi::c_ulong, prelude::*, + types::ForeignOwnable, types::Opaque, }; -use core::{ops::Deref, pin::Pin}; +#[cfg(CONFIG_COMMON_CLK)] +use crate::clk::Clk; + +use core::{ + ops::{Deref, DerefMut}, + pin::Pin, + ptr, +}; + +use macros::vtable; /// Default transition latency value in nanoseconds. pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32; @@ -363,3 +375,450 @@ impl TableBuilder { TableBox::new(self.entries) } } + +/// CPU frequency policy. +/// +/// Rust abstraction for the C `struct cpufreq_policy`. +/// +/// # Invariants +/// +/// A [`Policy`] instance always corresponds to a valid C `struct cpufreq_policy`. +/// +/// The callers must ensure that the `struct cpufreq_policy` is valid for access and remains valid +/// for the lifetime of the returned reference. +/// +/// ## Examples +/// +/// The following example demonstrates how to create a CPU frequency table. +/// +/// ``` +/// use kernel::cpufreq::{ETERNAL_LATENCY_NS, Policy}; +/// +/// fn update_policy(policy: &mut Policy) { +/// policy +/// .set_dvfs_possible_from_any_cpu(true) +/// .set_fast_switch_possible(true) +/// .set_transition_latency_ns(ETERNAL_LATENCY_NS); +/// +/// pr_info!("The policy details are: {:?}\n", (policy.cpu(), policy.cur())); +/// } +/// ``` +#[repr(transparent)] +pub struct Policy(Opaque); + +impl Policy { + /// Creates a reference to an existing `struct cpufreq_policy` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime + /// of the returned reference. + #[inline] + pub unsafe fn from_raw<'a>(ptr: *const bindings::cpufreq_policy) -> &'a Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the + // lifetime of the returned reference. + unsafe { &*ptr.cast() } + } + + /// Creates a mutable reference to an existing `struct cpufreq_policy` pointer. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime + /// of the returned reference. + #[inline] + pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpufreq_policy) -> &'a mut Self { + // SAFETY: Guaranteed by the safety requirements of the function. + // + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the + // lifetime of the returned reference. + unsafe { &mut *ptr.cast() } + } + + /// Returns a raw mutable pointer to the C `struct cpufreq_policy`. + #[inline] + fn as_raw(&self) -> *mut bindings::cpufreq_policy { + let this: *const Self = self; + this.cast_mut().cast() + } + + #[inline] + fn as_ref(&self) -> &bindings::cpufreq_policy { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + unsafe { &*self.as_raw() } + } + + #[inline] + fn as_mut_ref(&mut self) -> &mut bindings::cpufreq_policy { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + unsafe { &mut *self.as_raw() } + } + + /// Returns the primary CPU for the [`Policy`]. + #[inline] + pub fn cpu(&self) -> u32 { + self.as_ref().cpu + } + + /// Returns the minimum frequency for the [`Policy`]. + #[inline] + pub fn min(&self) -> Hertz { + Hertz::from_khz(self.as_ref().min as usize) + } + + /// Set the minimum frequency for the [`Policy`]. + #[inline] + pub fn set_min(&mut self, min: Hertz) -> &mut Self { + self.as_mut_ref().min = min.as_khz() as u32; + self + } + + /// Returns the maximum frequency for the [`Policy`]. + #[inline] + pub fn max(&self) -> Hertz { + Hertz::from_khz(self.as_ref().max as usize) + } + + /// Set the maximum frequency for the [`Policy`]. + #[inline] + pub fn set_max(&mut self, max: Hertz) -> &mut Self { + self.as_mut_ref().max = max.as_khz() as u32; + self + } + + /// Returns the current frequency for the [`Policy`]. + #[inline] + pub fn cur(&self) -> Hertz { + Hertz::from_khz(self.as_ref().cur as usize) + } + + /// Returns the suspend frequency for the [`Policy`]. + #[inline] + pub fn suspend_freq(&self) -> Hertz { + Hertz::from_khz(self.as_ref().suspend_freq as usize) + } + + /// Sets the suspend frequency for the [`Policy`]. + #[inline] + pub fn set_suspend_freq(&mut self, freq: Hertz) -> &mut Self { + self.as_mut_ref().suspend_freq = freq.as_khz() as u32; + self + } + + /// Provides a wrapper to the generic suspend routine. + #[inline] + pub fn generic_suspend(&mut self) -> Result { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + to_result(unsafe { bindings::cpufreq_generic_suspend(self.as_mut_ref()) }) + } + + /// Provides a wrapper to the generic get routine. + #[inline] + pub fn generic_get(&self) -> Result { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + Ok(unsafe { bindings::cpufreq_generic_get(self.cpu()) }) + } + + /// Provides a wrapper to the register with energy model using the OPP core. + #[cfg(CONFIG_PM_OPP)] + #[inline] + pub fn register_em_opp(&mut self) { + // SAFETY: By the type invariant, the pointer stored in `self` is valid. + unsafe { bindings::cpufreq_register_em_with_opp(self.as_mut_ref()) }; + } + + /// Gets [`cpumask::Cpumask`] for a cpufreq [`Policy`]. + #[inline] + pub fn cpus(&mut self) -> &mut cpumask::Cpumask { + // SAFETY: The pointer to `cpus` is valid for writing and remains valid for the lifetime of + // the returned reference. + unsafe { cpumask::CpumaskVar::as_mut_ref(&mut self.as_mut_ref().cpus) } + } + + /// Sets clock for the [`Policy`]. + /// + /// # Safety + /// + /// The caller must guarantee that the returned [`Clk`] is not dropped while it is getting used + /// by the C code. + #[cfg(CONFIG_COMMON_CLK)] + pub unsafe fn set_clk(&mut self, dev: &Device, name: Option<&CStr>) -> Result { + let clk = Clk::get(dev, name)?; + self.as_mut_ref().clk = clk.as_raw(); + Ok(clk) + } + + /// Allows / disallows frequency switching code to run on any CPU. + #[inline] + pub fn set_dvfs_possible_from_any_cpu(&mut self, val: bool) -> &mut Self { + self.as_mut_ref().dvfs_possible_from_any_cpu = val; + self + } + + /// Returns if fast switching of frequencies is possible or not. + #[inline] + pub fn fast_switch_possible(&self) -> bool { + self.as_ref().fast_switch_possible + } + + /// Enables / disables fast frequency switching. + #[inline] + pub fn set_fast_switch_possible(&mut self, val: bool) -> &mut Self { + self.as_mut_ref().fast_switch_possible = val; + self + } + + /// Sets transition latency (in nanoseconds) for the [`Policy`]. + #[inline] + pub fn set_transition_latency_ns(&mut self, latency_ns: u32) -> &mut Self { + self.as_mut_ref().cpuinfo.transition_latency = latency_ns; + self + } + + /// Sets cpuinfo `min_freq`. + #[inline] + pub fn set_cpuinfo_min_freq(&mut self, min_freq: Hertz) -> &mut Self { + self.as_mut_ref().cpuinfo.min_freq = min_freq.as_khz() as u32; + self + } + + /// Sets cpuinfo `max_freq`. + #[inline] + pub fn set_cpuinfo_max_freq(&mut self, max_freq: Hertz) -> &mut Self { + self.as_mut_ref().cpuinfo.max_freq = max_freq.as_khz() as u32; + self + } + + /// Set `transition_delay_us`, i.e. the minimum time between successive frequency change + /// requests. + #[inline] + pub fn set_transition_delay_us(&mut self, transition_delay_us: u32) -> &mut Self { + self.as_mut_ref().transition_delay_us = transition_delay_us; + self + } + + /// Returns reference to the CPU frequency [`Table`] for the [`Policy`]. + pub fn freq_table(&self) -> Result<&Table> { + if self.as_ref().freq_table.is_null() { + return Err(EINVAL); + } + + // SAFETY: The `freq_table` is guaranteed to be valid for reading and remains valid for the + // lifetime of the returned reference. + Ok(unsafe { Table::from_raw(self.as_ref().freq_table) }) + } + + /// Sets the CPU frequency [`Table`] for the [`Policy`]. + /// + /// # Safety + /// + /// The caller must guarantee that the [`Table`] is not dropped while it is getting used by the + /// C code. + #[inline] + pub unsafe fn set_freq_table(&mut self, table: &Table) -> &mut Self { + self.as_mut_ref().freq_table = table.as_raw(); + self + } + + /// Returns the [`Policy`]'s private data. + pub fn data(&mut self) -> Option<::Borrowed<'_>> { + if self.as_ref().driver_data.is_null() { + None + } else { + // SAFETY: The data is earlier set from [`set_data`]. + Some(unsafe { T::borrow(self.as_ref().driver_data) }) + } + } + + /// Sets the private data of the [`Policy`] using a foreign-ownable wrapper. + /// + /// # Errors + /// + /// Returns `EBUSY` if private data is already set. + fn set_data(&mut self, data: T) -> Result { + if self.as_ref().driver_data.is_null() { + // Transfer the ownership of the data to the foreign interface. + self.as_mut_ref().driver_data = ::into_foreign(data) as _; + Ok(()) + } else { + Err(EBUSY) + } + } + + /// Clears and returns ownership of the private data. + fn clear_data(&mut self) -> Option { + if self.as_ref().driver_data.is_null() { + None + } else { + let data = Some( + // SAFETY: The data is earlier set by us from [`set_data`]. It is safe to take + // back the ownership of the data from the foreign interface. + unsafe { ::from_foreign(self.as_ref().driver_data) }, + ); + self.as_mut_ref().driver_data = ptr::null_mut(); + data + } + } +} + +/// CPU frequency policy created from a CPU number. +/// +/// This struct represents the CPU frequency policy obtained for a specific CPU, providing safe +/// access to the underlying `cpufreq_policy` and ensuring proper cleanup when the `PolicyCpu` is +/// dropped. +struct PolicyCpu<'a>(&'a mut Policy); + +impl<'a> PolicyCpu<'a> { + fn from_cpu(cpu: u32) -> Result { + // SAFETY: It is safe to call `cpufreq_cpu_get` for any valid CPU. + let ptr = from_err_ptr(unsafe { bindings::cpufreq_cpu_get(cpu) })?; + + Ok(Self( + // SAFETY: The `ptr` is guaranteed to be valid and remains valid for the lifetime of + // the returned reference. + unsafe { Policy::from_raw_mut(ptr) }, + )) + } +} + +impl<'a> Deref for PolicyCpu<'a> { + type Target = Policy; + + fn deref(&self) -> &Self::Target { + self.0 + } +} + +impl<'a> DerefMut for PolicyCpu<'a> { + fn deref_mut(&mut self) -> &mut Policy { + self.0 + } +} + +impl<'a> Drop for PolicyCpu<'a> { + fn drop(&mut self) { + // SAFETY: The underlying pointer is guaranteed to be valid for the lifetime of `self`. + unsafe { bindings::cpufreq_cpu_put(self.0.as_raw()) }; + } +} + +/// CPU frequency driver. +/// +/// Implement this trait to provide a CPU frequency driver and its callbacks. +/// +/// Reference: +#[vtable] +pub trait Driver { + /// Driver's name. + const NAME: &'static CStr; + + /// Driver's flags. + const FLAGS: u16; + + /// Boost support. + const BOOST_ENABLED: bool; + + /// Policy specific data. + /// + /// Require that `PData` implements `ForeignOwnable`. We guarantee to never move the underlying + /// wrapped data structure. + type PData: ForeignOwnable; + + /// Driver's `init` callback. + fn init(policy: &mut Policy) -> Result; + + /// Driver's `exit` callback. + fn exit(_policy: &mut Policy, _data: Option) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `online` callback. + fn online(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `offline` callback. + fn offline(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `suspend` callback. + fn suspend(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `resume` callback. + fn resume(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `ready` callback. + fn ready(_policy: &mut Policy) { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `verify` callback. + fn verify(data: &mut PolicyData) -> Result; + + /// Driver's `setpolicy` callback. + fn setpolicy(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `target` callback. + fn target(_policy: &mut Policy, _target_freq: u32, _relation: Relation) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `target_index` callback. + fn target_index(_policy: &mut Policy, _index: TableIndex) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `fast_switch` callback. + fn fast_switch(_policy: &mut Policy, _target_freq: u32) -> u32 { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `adjust_perf` callback. + fn adjust_perf(_policy: &mut Policy, _min_perf: usize, _target_perf: usize, _capacity: usize) { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `get_intermediate` callback. + fn get_intermediate(_policy: &mut Policy, _index: TableIndex) -> u32 { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `target_intermediate` callback. + fn target_intermediate(_policy: &mut Policy, _index: TableIndex) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `get` callback. + fn get(_policy: &mut Policy) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `update_limits` callback. + fn update_limits(_policy: &mut Policy) { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `bios_limit` callback. + fn bios_limit(_policy: &mut Policy, _limit: &mut u32) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `set_boost` callback. + fn set_boost(_policy: &mut Policy, _state: i32) -> Result { + build_error!(VTABLE_DEFAULT_ERROR) + } + + /// Driver's `register_em` callback. + fn register_em(_policy: &mut Policy) { + build_error!(VTABLE_DEFAULT_ERROR) + } +} -- cgit v1.2.3 From c6af9a1191d042839e56abff69e8b0302d117988 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 24 Jan 2024 12:36:33 +0530 Subject: rust: cpufreq: Extend abstractions for driver registration Extend the cpufreq abstractions to support driver registration from Rust. Reviewed-by: Danilo Krummrich Signed-off-by: Viresh Kumar --- rust/kernel/cpufreq.rs | 503 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 500 insertions(+), 3 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs index 1bc208b91822..09b856bb297b 100644 --- a/rust/kernel/cpufreq.rs +++ b/rust/kernel/cpufreq.rs @@ -11,9 +11,10 @@ use crate::{ clk::Hertz, cpumask, - device::Device, - error::{code::*, from_err_ptr, to_result, Result, VTABLE_DEFAULT_ERROR}, - ffi::c_ulong, + device::{Bound, Device}, + devres::Devres, + error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR}, + ffi::{c_char, c_ulong}, prelude::*, types::ForeignOwnable, types::Opaque, @@ -23,6 +24,9 @@ use crate::{ use crate::clk::Clk; use core::{ + cell::UnsafeCell, + marker::PhantomData, + mem::MaybeUninit, ops::{Deref, DerefMut}, pin::Pin, ptr, @@ -30,6 +34,9 @@ use core::{ use macros::vtable; +/// Maximum length of CPU frequency driver's name. +const CPUFREQ_NAME_LEN: usize = bindings::CPUFREQ_NAME_LEN as usize; + /// Default transition latency value in nanoseconds. pub const ETERNAL_LATENCY_NS: u32 = bindings::CPUFREQ_ETERNAL as u32; @@ -822,3 +829,493 @@ pub trait Driver { build_error!(VTABLE_DEFAULT_ERROR) } } + +/// CPU frequency driver Registration. +/// +/// ## Examples +/// +/// The following example demonstrates how to register a cpufreq driver. +/// +/// ``` +/// use kernel::{ +/// cpufreq, +/// c_str, +/// device::{Core, Device}, +/// macros::vtable, +/// of, platform, +/// sync::Arc, +/// }; +/// struct SampleDevice; +/// +/// #[derive(Default)] +/// struct SampleDriver; +/// +/// #[vtable] +/// impl cpufreq::Driver for SampleDriver { +/// const NAME: &'static CStr = c_str!("cpufreq-sample"); +/// const FLAGS: u16 = cpufreq::flags::NEED_INITIAL_FREQ_CHECK | cpufreq::flags::IS_COOLING_DEV; +/// const BOOST_ENABLED: bool = true; +/// +/// type PData = Arc; +/// +/// fn init(policy: &mut cpufreq::Policy) -> Result { +/// // Initialize here +/// Ok(Arc::new(SampleDevice, GFP_KERNEL)?) +/// } +/// +/// fn exit(_policy: &mut cpufreq::Policy, _data: Option) -> Result { +/// Ok(()) +/// } +/// +/// fn suspend(policy: &mut cpufreq::Policy) -> Result { +/// policy.generic_suspend() +/// } +/// +/// fn verify(data: &mut cpufreq::PolicyData) -> Result { +/// data.generic_verify() +/// } +/// +/// fn target_index(policy: &mut cpufreq::Policy, index: cpufreq::TableIndex) -> Result { +/// // Update CPU frequency +/// Ok(()) +/// } +/// +/// fn get(policy: &mut cpufreq::Policy) -> Result { +/// policy.generic_get() +/// } +/// } +/// +/// impl platform::Driver for SampleDriver { +/// type IdInfo = (); +/// const OF_ID_TABLE: Option> = None; +/// +/// fn probe( +/// pdev: &platform::Device, +/// _id_info: Option<&Self::IdInfo>, +/// ) -> Result>> { +/// cpufreq::Registration::::new_foreign_owned(pdev.as_ref())?; +/// Ok(KBox::new(Self {}, GFP_KERNEL)?.into()) +/// } +/// } +/// ``` +#[repr(transparent)] +pub struct Registration(KBox>, PhantomData); + +/// SAFETY: `Registration` doesn't offer any methods or access to fields when shared between threads +/// or CPUs, so it is safe to share it. +unsafe impl Sync for Registration {} + +#[allow(clippy::non_send_fields_in_send_ty)] +/// SAFETY: Registration with and unregistration from the cpufreq subsystem can happen from any +/// thread. +unsafe impl Send for Registration {} + +impl Registration { + const VTABLE: bindings::cpufreq_driver = bindings::cpufreq_driver { + name: Self::copy_name(T::NAME), + boost_enabled: T::BOOST_ENABLED, + flags: T::FLAGS, + + // Initialize mandatory callbacks. + init: Some(Self::init_callback), + verify: Some(Self::verify_callback), + + // Initialize optional callbacks based on the traits of `T`. + setpolicy: if T::HAS_SETPOLICY { + Some(Self::setpolicy_callback) + } else { + None + }, + target: if T::HAS_TARGET { + Some(Self::target_callback) + } else { + None + }, + target_index: if T::HAS_TARGET_INDEX { + Some(Self::target_index_callback) + } else { + None + }, + fast_switch: if T::HAS_FAST_SWITCH { + Some(Self::fast_switch_callback) + } else { + None + }, + adjust_perf: if T::HAS_ADJUST_PERF { + Some(Self::adjust_perf_callback) + } else { + None + }, + get_intermediate: if T::HAS_GET_INTERMEDIATE { + Some(Self::get_intermediate_callback) + } else { + None + }, + target_intermediate: if T::HAS_TARGET_INTERMEDIATE { + Some(Self::target_intermediate_callback) + } else { + None + }, + get: if T::HAS_GET { + Some(Self::get_callback) + } else { + None + }, + update_limits: if T::HAS_UPDATE_LIMITS { + Some(Self::update_limits_callback) + } else { + None + }, + bios_limit: if T::HAS_BIOS_LIMIT { + Some(Self::bios_limit_callback) + } else { + None + }, + online: if T::HAS_ONLINE { + Some(Self::online_callback) + } else { + None + }, + offline: if T::HAS_OFFLINE { + Some(Self::offline_callback) + } else { + None + }, + exit: if T::HAS_EXIT { + Some(Self::exit_callback) + } else { + None + }, + suspend: if T::HAS_SUSPEND { + Some(Self::suspend_callback) + } else { + None + }, + resume: if T::HAS_RESUME { + Some(Self::resume_callback) + } else { + None + }, + ready: if T::HAS_READY { + Some(Self::ready_callback) + } else { + None + }, + set_boost: if T::HAS_SET_BOOST { + Some(Self::set_boost_callback) + } else { + None + }, + register_em: if T::HAS_REGISTER_EM { + Some(Self::register_em_callback) + } else { + None + }, + // SAFETY: All zeros is a valid value for `bindings::cpufreq_driver`. + ..unsafe { MaybeUninit::zeroed().assume_init() } + }; + + const fn copy_name(name: &'static CStr) -> [c_char; CPUFREQ_NAME_LEN] { + let src = name.as_bytes_with_nul(); + let mut dst = [0; CPUFREQ_NAME_LEN]; + + build_assert!(src.len() <= CPUFREQ_NAME_LEN); + + let mut i = 0; + while i < src.len() { + dst[i] = src[i]; + i += 1; + } + + dst + } + + /// Registers a CPU frequency driver with the cpufreq core. + pub fn new() -> Result { + // We can't use `&Self::VTABLE` directly because the cpufreq core modifies some fields in + // the C `struct cpufreq_driver`, which requires a mutable reference. + let mut drv = KBox::new(UnsafeCell::new(Self::VTABLE), GFP_KERNEL)?; + + // SAFETY: `drv` is guaranteed to be valid for the lifetime of `Registration`. + to_result(unsafe { bindings::cpufreq_register_driver(drv.get_mut()) })?; + + Ok(Self(drv, PhantomData)) + } + + /// Same as [`Registration::new`], but does not return a [`Registration`] instance. + /// + /// Instead the [`Registration`] is owned by [`Devres`] and will be revoked / dropped, once the + /// device is detached. + pub fn new_foreign_owned(dev: &Device) -> Result { + Devres::new_foreign_owned(dev, Self::new()?, GFP_KERNEL) + } +} + +/// CPU frequency driver callbacks. +impl Registration { + /// Driver's `init` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn init_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + + let data = T::init(policy)?; + policy.set_data(data)?; + Ok(0) + }) + } + + /// Driver's `exit` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn exit_callback(ptr: *mut bindings::cpufreq_policy) { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + + let data = policy.clear_data(); + let _ = T::exit(policy, data); + } + + /// Driver's `online` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn online_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::online(policy).map(|()| 0) + }) + } + + /// Driver's `offline` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn offline_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::offline(policy).map(|()| 0) + }) + } + + /// Driver's `suspend` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn suspend_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::suspend(policy).map(|()| 0) + }) + } + + /// Driver's `resume` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn resume_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::resume(policy).map(|()| 0) + }) + } + + /// Driver's `ready` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn ready_callback(ptr: *mut bindings::cpufreq_policy) { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::ready(policy); + } + + /// Driver's `verify` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn verify_callback(ptr: *mut bindings::cpufreq_policy_data) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let data = unsafe { PolicyData::from_raw_mut(ptr) }; + T::verify(data).map(|()| 0) + }) + } + + /// Driver's `setpolicy` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn setpolicy_callback(ptr: *mut bindings::cpufreq_policy) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::setpolicy(policy).map(|()| 0) + }) + } + + /// Driver's `target` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn target_callback( + ptr: *mut bindings::cpufreq_policy, + target_freq: u32, + relation: u32, + ) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::target(policy, target_freq, Relation::new(relation)?).map(|()| 0) + }) + } + + /// Driver's `target_index` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn target_index_callback( + ptr: *mut bindings::cpufreq_policy, + index: u32, + ) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + + // SAFETY: The C code guarantees that `index` corresponds to a valid entry in the + // frequency table. + let index = unsafe { TableIndex::new(index as usize) }; + + T::target_index(policy, index).map(|()| 0) + }) + } + + /// Driver's `fast_switch` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn fast_switch_callback( + ptr: *mut bindings::cpufreq_policy, + target_freq: u32, + ) -> kernel::ffi::c_uint { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::fast_switch(policy, target_freq) + } + + /// Driver's `adjust_perf` callback. + extern "C" fn adjust_perf_callback( + cpu: u32, + min_perf: usize, + target_perf: usize, + capacity: usize, + ) { + if let Ok(mut policy) = PolicyCpu::from_cpu(cpu) { + T::adjust_perf(&mut policy, min_perf, target_perf, capacity); + } + } + + /// Driver's `get_intermediate` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn get_intermediate_callback( + ptr: *mut bindings::cpufreq_policy, + index: u32, + ) -> kernel::ffi::c_uint { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + + // SAFETY: The C code guarantees that `index` corresponds to a valid entry in the + // frequency table. + let index = unsafe { TableIndex::new(index as usize) }; + + T::get_intermediate(policy, index) + } + + /// Driver's `target_intermediate` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn target_intermediate_callback( + ptr: *mut bindings::cpufreq_policy, + index: u32, + ) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + + // SAFETY: The C code guarantees that `index` corresponds to a valid entry in the + // frequency table. + let index = unsafe { TableIndex::new(index as usize) }; + + T::target_intermediate(policy, index).map(|()| 0) + }) + } + + /// Driver's `get` callback. + extern "C" fn get_callback(cpu: u32) -> kernel::ffi::c_uint { + PolicyCpu::from_cpu(cpu).map_or(0, |mut policy| T::get(&mut policy).map_or(0, |f| f)) + } + + /// Driver's `update_limit` callback. + extern "C" fn update_limits_callback(ptr: *mut bindings::cpufreq_policy) { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::update_limits(policy); + } + + /// Driver's `bios_limit` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn bios_limit_callback(cpu: i32, limit: *mut u32) -> kernel::ffi::c_int { + from_result(|| { + let mut policy = PolicyCpu::from_cpu(cpu as u32)?; + + // SAFETY: `limit` is guaranteed by the C code to be valid. + T::bios_limit(&mut policy, &mut (unsafe { *limit })).map(|()| 0) + }) + } + + /// Driver's `set_boost` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn set_boost_callback( + ptr: *mut bindings::cpufreq_policy, + state: i32, + ) -> kernel::ffi::c_int { + from_result(|| { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::set_boost(policy, state).map(|()| 0) + }) + } + + /// Driver's `register_em` callback. + /// + /// SAFETY: Called from C. Inputs must be valid pointers. + extern "C" fn register_em_callback(ptr: *mut bindings::cpufreq_policy) { + // SAFETY: The `ptr` is guaranteed to be valid by the contract with the C code for the + // lifetime of `policy`. + let policy = unsafe { Policy::from_raw_mut(ptr) }; + T::register_em(policy); + } +} + +impl Drop for Registration { + /// Unregisters with the cpufreq core. + fn drop(&mut self) { + // SAFETY: `self.0` is guaranteed to be valid for the lifetime of `Registration`. + unsafe { bindings::cpufreq_unregister_driver(self.0.get_mut()) }; + } +} -- cgit v1.2.3 From 14f47156cf390606eb719da9ad1058f87af0a291 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 7 Jan 2025 12:53:32 +0530 Subject: rust: opp: Extend OPP abstractions with cpufreq support Extend the OPP abstractions to include support for interacting with the cpufreq core, including the ability to retrieve frequency tables from OPP table. Signed-off-by: Viresh Kumar --- rust/kernel/opp.rs | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs index 5293d878cb55..212555dacd45 100644 --- a/rust/kernel/opp.rs +++ b/rust/kernel/opp.rs @@ -19,6 +19,69 @@ use crate::{ types::{ARef, AlwaysRefCounted, Opaque}, }; +#[cfg(CONFIG_CPU_FREQ)] +/// Frequency table implementation. +mod freq { + use super::*; + use crate::cpufreq; + use core::ops::Deref; + + /// OPP frequency table. + /// + /// A [`cpufreq::Table`] created from [`Table`]. + pub struct FreqTable { + dev: ARef, + ptr: *mut bindings::cpufreq_frequency_table, + } + + impl FreqTable { + /// Creates a new instance of [`FreqTable`] from [`Table`]. + pub(crate) fn new(table: &Table) -> Result { + let mut ptr: *mut bindings::cpufreq_frequency_table = ptr::null_mut(); + + // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety + // requirements. + to_result(unsafe { + bindings::dev_pm_opp_init_cpufreq_table(table.dev.as_raw(), &mut ptr) + })?; + + Ok(Self { + dev: table.dev.clone(), + ptr, + }) + } + + /// Returns a reference to the underlying [`cpufreq::Table`]. + #[inline] + fn table(&self) -> &cpufreq::Table { + // SAFETY: The `ptr` is guaranteed by the C code to be valid. + unsafe { cpufreq::Table::from_raw(self.ptr) } + } + } + + impl Deref for FreqTable { + type Target = cpufreq::Table; + + #[inline] + fn deref(&self) -> &Self::Target { + self.table() + } + } + + impl Drop for FreqTable { + fn drop(&mut self) { + // SAFETY: The pointer was created via `dev_pm_opp_init_cpufreq_table`, and is only + // freed here. + unsafe { + bindings::dev_pm_opp_free_cpufreq_table(self.dev.as_raw(), &mut self.as_raw()) + }; + } + } +} + +#[cfg(CONFIG_CPU_FREQ)] +pub use freq::FreqTable; + use core::{marker::PhantomData, ptr}; use macros::vtable; @@ -753,6 +816,13 @@ impl Table { }) } + /// Creates [`FreqTable`] from [`Table`]. + #[cfg(CONFIG_CPU_FREQ)] + #[inline] + pub fn cpufreq_table(&mut self) -> Result { + FreqTable::new(self) + } + /// Configures device with [`OPP`] matching the frequency value. #[inline] pub fn set_rate(&self, freq: Hertz) -> Result { -- cgit v1.2.3 From ae8b3a83fb9de394f609035041cd7a668fda2ab3 Mon Sep 17 00:00:00 2001 From: Jihed Chaibi Date: Sat, 17 May 2025 02:26:04 +0200 Subject: rust: str: fix typo in comment Fix a typo ("then" to "than") in a comment. Signed-off-by: Jihed Chaibi Reviewed-by: Benno Lossin Fixes: fffed679eeea ("rust: str: add `Formatter` type") Link: https://lore.kernel.org/r/20250517002604.603223-1-jihed.chaibi.dev@gmail.com [ Reworded. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/str.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 8768ab790580..98d5c74ec4f7 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -752,7 +752,7 @@ impl RawFormatter { /// for the lifetime of the returned [`RawFormatter`]. pub(crate) unsafe fn from_buffer(buf: *mut u8, len: usize) -> Self { let pos = buf as usize; - // INVARIANT: We ensure that `end` is never less then `buf`, and the safety requirements + // INVARIANT: We ensure that `end` is never less than `buf`, and the safety requirements // guarantees that the memory region is valid for writes. Self { pos, -- cgit v1.2.3 From 81e9edc1a8d657291409d70d93361d8277d226d8 Mon Sep 17 00:00:00 2001 From: Christian Schrefl Date: Sat, 17 May 2025 13:06:15 +0200 Subject: rust: miscdevice: fix typo in MiscDevice::ioctl documentation Fixes one small typo (`utilties` to `utilities`) in the documentation of `MiscDevice::ioctl`. Fixes: f893691e7426 ("rust: miscdevice: add base miscdevice abstraction") Signed-off-by: Christian Schrefl Reviewed-by: Benno Lossin Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250517-rust_miscdevice_fix_typo-v1-1-8c30a6237ba9@gmail.com Signed-off-by: Greg Kroah-Hartman --- rust/kernel/miscdevice.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs index fa9ecc42602a..15d10e5c1db7 100644 --- a/rust/kernel/miscdevice.rs +++ b/rust/kernel/miscdevice.rs @@ -121,7 +121,7 @@ pub trait MiscDevice: Sized { /// Handler for ioctls. /// - /// The `cmd` argument is usually manipulated using the utilties in [`kernel::ioctl`]. + /// The `cmd` argument is usually manipulated using the utilities in [`kernel::ioctl`]. /// /// [`kernel::ioctl`]: mod@crate::ioctl fn ioctl( -- cgit v1.2.3 From 31afd6bc55cc0093c3e5b0a368319e423d4de8ea Mon Sep 17 00:00:00 2001 From: Christian Marangi Date: Sat, 17 May 2025 22:13:45 +0200 Subject: net: phy: pass PHY driver to .match_phy_device OP Pass PHY driver pointer to .match_phy_device OP in addition to phydev. Having access to the PHY driver struct might be useful to check the PHY ID of the driver is being matched for in case the PHY ID scanned in the phydev is not consistent. A scenario for this is a PHY that change PHY ID after a firmware is loaded, in such case, the PHY ID stored in PHY device struct is not valid anymore and PHY will manually scan the ID in the match_phy_device function. Having the PHY driver info is also useful for those PHY driver that implement multiple simple .match_phy_device OP to match specific MMD PHY ID. With this extra info if the parsing logic is the same, the matching function can be generalized by using the phy_id in the PHY driver instead of hardcoding. Rust wrapper callback is updated to align to the new match_phy_device arguments. Suggested-by: Russell King (Oracle) Reviewed-by: Russell King (Oracle) Signed-off-by: Christian Marangi Reviewed-by: Benno Lossin # for Rust Reviewed-by: FUJITA Tomonori Link: https://patch.msgid.link/20250517201353.5137-2-ansuelsmth@gmail.com Signed-off-by: Jakub Kicinski --- rust/kernel/net/phy.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust/kernel') diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs index a59469c785e3..32ea43ece646 100644 --- a/rust/kernel/net/phy.rs +++ b/rust/kernel/net/phy.rs @@ -421,6 +421,7 @@ impl Adapter { /// `phydev` must be passed by the corresponding callback in `phy_driver`. unsafe extern "C" fn match_phy_device_callback( phydev: *mut bindings::phy_device, + _phydrv: *const bindings::phy_driver, ) -> crate::ffi::c_int { // SAFETY: This callback is called only in contexts // where we hold `phy_device->lock`, so the accessors on -- cgit v1.2.3 From bb941ea789f803cce766ca1e0f7c59a362aaf99a Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Tue, 20 May 2025 20:21:25 +0200 Subject: rust: remove unneeded Rust 1.87.0 `allow(clippy::ptr_eq)` For the Rust 1.87.0 release, Clippy was expected to warn with: error: use `core::ptr::eq` when comparing raw pointers --> rust/kernel/list.rs:438:12 | 438 | if self.first == item { | ^^^^^^^^^^^^^^^^^^ help: try: `core::ptr::eq(self.first, item)` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_eq = note: `-D clippy::ptr-eq` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::ptr_eq)]` However, a backport to relax a bit the `clippy::ptr_eq` finally landed, and thus Clippy did not warn by the time the release happened. Thus remove the `allow`s added back then, which were added just in case the backport did not land in time. See commit a39f30870927 ("rust: allow Rust 1.87.0's `clippy::ptr_eq` lint") for details. Link: https://github.com/rust-lang/rust/pull/140859 [1] Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250520182125.806758-1-ojeda@kernel.org [ Reworded for clarity. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/kvec.rs | 3 --- rust/kernel/list.rs | 3 --- 2 files changed, 6 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index d9f5b79b26dc..1a0dd852a468 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -2,9 +2,6 @@ //! Implementation of [`Vec`]. -// May not be needed in Rust 1.87.0 (pending beta backport). -#![allow(clippy::ptr_eq)] - use super::{ allocator::{KVmalloc, Kmalloc, Vmalloc}, layout::ArrayLayout, diff --git a/rust/kernel/list.rs b/rust/kernel/list.rs index 2054682c5724..a335c3b1ff5e 100644 --- a/rust/kernel/list.rs +++ b/rust/kernel/list.rs @@ -4,9 +4,6 @@ //! A linked list implementation. -// May not be needed in Rust 1.87.0 (pending beta backport). -#![allow(clippy::ptr_eq)] - use crate::sync::ArcBorrow; use crate::types::Opaque; use core::iter::{DoubleEndedIterator, FusedIterator}; -- cgit v1.2.3 From 28669b2f37e9b7e98b62d0be2e10a5bf31c2b16f Mon Sep 17 00:00:00 2001 From: I Hsin Cheng Date: Mon, 10 Mar 2025 15:38:52 +0800 Subject: rust: list: Use "List::is_empty()" to perform checking when possible "List::is_empty()" provides a straight forward convention to check whether a given "List" is empty or not. There're numerous places in the current implementation still use "self.first.is_null()" to perform the equivalent check, replace them with "List::is_empty()". Signed-off-by: I Hsin Cheng Link: https://lore.kernel.org/r/20250310073853.427954-1-richard120310@gmail.com Reviewed-by: Benno Lossin [ Rebased dropping the cases that do not apply anymore. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/list.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/list.rs b/rust/kernel/list.rs index a335c3b1ff5e..7740c8f16cf6 100644 --- a/rust/kernel/list.rs +++ b/rust/kernel/list.rs @@ -319,7 +319,7 @@ impl, const ID: u64> List { /// Removes the last item from this list. pub fn pop_back(&mut self) -> Option> { - if self.first.is_null() { + if self.is_empty() { return None; } @@ -331,7 +331,7 @@ impl, const ID: u64> List { /// Removes the first item from this list. pub fn pop_front(&mut self) -> Option> { - if self.first.is_null() { + if self.is_empty() { return None; } -- cgit v1.2.3 From 195746046c256ce5324772394c886ba798859fca Mon Sep 17 00:00:00 2001 From: I Hsin Cheng Date: Tue, 11 Mar 2025 21:33:57 +0800 Subject: rust: list: Add examples for linked list Add basic examples for the structure "List", which also serve as unit tests for basic list methods. It includes the following manipulations: * List creation * List emptiness check * List insertion through push_front(), push_back() * List item removal through pop_front(), pop_back() * Push one list to another through push_all_back() The method "remove()" doesn't have an example here because insertion with push_front() or push_back() will take the ownership of the item, which means we can't keep any valid reference to the node we want to remove, unless Cursor is used. The "remove" example through Cursor is already demonstrated with commit 52ae96f5187c ("rust: list: make the cursor point between elements"). Link: https://github.com/Rust-for-Linux/linux/issues/1121 Signed-off-by: I Hsin Cheng Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250311133357.90322-1-richard120310@gmail.com [ Removed prelude import and spurious newlines. Formatted comments with the usual style. Reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/list.rs | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/list.rs b/rust/kernel/list.rs index 7740c8f16cf6..c391c30b80f8 100644 --- a/rust/kernel/list.rs +++ b/rust/kernel/list.rs @@ -35,6 +35,114 @@ pub use self::arc_field::{define_list_arc_field_getter, ListArcField}; /// * All prev/next pointers in `ListLinks` fields of items in the list are valid and form a cycle. /// * For every item in the list, the list owns the associated [`ListArc`] reference and has /// exclusive access to the `ListLinks` field. +/// +/// # Examples +/// +/// ``` +/// use kernel::list::*; +/// +/// #[pin_data] +/// struct BasicItem { +/// value: i32, +/// #[pin] +/// links: ListLinks, +/// } +/// +/// impl BasicItem { +/// fn new(value: i32) -> Result> { +/// ListArc::pin_init(try_pin_init!(Self { +/// value, +/// links <- ListLinks::new(), +/// }), GFP_KERNEL) +/// } +/// } +/// +/// impl_has_list_links! { +/// impl HasListLinks<0> for BasicItem { self.links } +/// } +/// impl_list_arc_safe! { +/// impl ListArcSafe<0> for BasicItem { untracked; } +/// } +/// impl_list_item! { +/// impl ListItem<0> for BasicItem { using ListLinks; } +/// } +/// +/// // Create a new empty list. +/// let mut list = List::new(); +/// { +/// assert!(list.is_empty()); +/// } +/// +/// // Insert 3 elements using `push_back()`. +/// list.push_back(BasicItem::new(15)?); +/// list.push_back(BasicItem::new(10)?); +/// list.push_back(BasicItem::new(30)?); +/// +/// // Iterate over the list to verify the nodes were inserted correctly. +/// // [15, 10, 30] +/// { +/// let mut iter = list.iter(); +/// assert_eq!(iter.next().unwrap().value, 15); +/// assert_eq!(iter.next().unwrap().value, 10); +/// assert_eq!(iter.next().unwrap().value, 30); +/// assert!(iter.next().is_none()); +/// +/// // Verify the length of the list. +/// assert_eq!(list.iter().count(), 3); +/// } +/// +/// // Pop the items from the list using `pop_back()` and verify the content. +/// { +/// assert_eq!(list.pop_back().unwrap().value, 30); +/// assert_eq!(list.pop_back().unwrap().value, 10); +/// assert_eq!(list.pop_back().unwrap().value, 15); +/// } +/// +/// // Insert 3 elements using `push_front()`. +/// list.push_front(BasicItem::new(15)?); +/// list.push_front(BasicItem::new(10)?); +/// list.push_front(BasicItem::new(30)?); +/// +/// // Iterate over the list to verify the nodes were inserted correctly. +/// // [30, 10, 15] +/// { +/// let mut iter = list.iter(); +/// assert_eq!(iter.next().unwrap().value, 30); +/// assert_eq!(iter.next().unwrap().value, 10); +/// assert_eq!(iter.next().unwrap().value, 15); +/// assert!(iter.next().is_none()); +/// +/// // Verify the length of the list. +/// assert_eq!(list.iter().count(), 3); +/// } +/// +/// // Pop the items from the list using `pop_front()` and verify the content. +/// { +/// assert_eq!(list.pop_front().unwrap().value, 30); +/// assert_eq!(list.pop_front().unwrap().value, 10); +/// } +/// +/// // Push `list2` to `list` through `push_all_back()`. +/// // list: [15] +/// // list2: [25, 35] +/// { +/// let mut list2 = List::new(); +/// list2.push_back(BasicItem::new(25)?); +/// list2.push_back(BasicItem::new(35)?); +/// +/// list.push_all_back(&mut list2); +/// +/// // list: [15, 25, 35] +/// // list2: [] +/// let mut iter = list.iter(); +/// assert_eq!(iter.next().unwrap().value, 15); +/// assert_eq!(iter.next().unwrap().value, 25); +/// assert_eq!(iter.next().unwrap().value, 35); +/// assert!(iter.next().is_none()); +/// assert!(list2.is_empty()); +/// } +/// # Result::<(), Error>::Ok(()) +/// ``` pub struct List, const ID: u64 = 0> { first: *mut ListLinksFields, _ty: PhantomData>, -- cgit v1.2.3 From 8cbc95f983bcec7e042266766ffe0d68980e4290 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Tue, 25 Mar 2025 19:43:09 +0100 Subject: rust: workaround `bindgen` issue with forward references to `enum` types `bindgen` currently generates the wrong type for an `enum` when there is a forward reference to it. For instance: enum E; enum E { A }; generates: pub const E_A: E = 0; pub type E = i32; instead of the expected: pub const E_A: E = 0; pub type E = ffi::c_uint; The issue was reported to upstream `bindgen` [1]. Now, both GCC and Clang support silently these forward references to `enum` types, unless `-Wpedantic` is passed, and it turns out that some headers in the kernel depend on them. Thus, depending on how the headers are included, which in turn may depend on the kernel configuration or the architecture, we may get a different type on the Rust side for a given C `enum`. That can be quite confusing, to say the least, especially since developers may only notice issues when building for other architectures like in [2]. In particular, they may end up forcing a cast and adding an `#[allow(clippy::unnecessary_cast)]` like it was done in commit 94e05a66ea3e ("rust: hrtimer: allow timer restart from timer handler"), which isn't great. Instead, let's have a section at the top of our `bindings_helper.h` that `#include`s the headers with the affected types -- hopefully there are not many cases and there is a single ordering that covers all cases. This allows us to remove the cast and the `#[allow]`, thus keeping the correct code in the source files. When the issue gets resolved in upstream `bindgen` (and we update our minimum `bindgen` version), we can easily remove this section at the top. Link: https://github.com/rust-lang/rust-bindgen/issues/3179 [1] Link: https://lore.kernel.org/rust-for-linux/87tt7md1s6.fsf@kernel.org/ [2] Acked-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250325184309.97170-1-ojeda@kernel.org [ Added extra paragraph on the comment to clarify that the workaround may not be possible in some cases. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/time/hrtimer.rs | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index 17824aa0c0f3..9df3dcd2fa39 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -400,11 +400,9 @@ pub unsafe trait HasHrTimer { #[repr(u32)] pub enum HrTimerRestart { /// Timer should not be restarted. - #[allow(clippy::unnecessary_cast)] - NoRestart = bindings::hrtimer_restart_HRTIMER_NORESTART as u32, + NoRestart = bindings::hrtimer_restart_HRTIMER_NORESTART, /// Timer should be restarted. - #[allow(clippy::unnecessary_cast)] - Restart = bindings::hrtimer_restart_HRTIMER_RESTART as u32, + Restart = bindings::hrtimer_restart_HRTIMER_RESTART, } impl HrTimerRestart { -- cgit v1.2.3 From de7cd3e4d6387df6a5ae8c4c32ff0479ebe0efb5 Mon Sep 17 00:00:00 2001 From: Igor Korotin Date: Mon, 19 May 2025 17:45:53 +0100 Subject: rust: use absolute paths in macros referencing core and kernel Macros and auto-generated code should use absolute paths, `::core::...` and `::kernel::...`, for core and kernel references. This prevents issues where user-defined modules named `core` or `kernel` could be picked up instead of the `core` or `kernel` crates. Thus clean some references up. Suggested-by: Benno Lossin Closes: https://github.com/Rust-for-Linux/linux/issues/1150 Signed-off-by: Igor Korotin Reviewed-by: Benno Lossin Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20250519164615.3310844-1-igor.korotin.linux@gmail.com [ Applied `rustfmt`. Reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/device.rs | 2 +- rust/kernel/device_id.rs | 4 ++-- rust/kernel/kunit.rs | 8 ++++---- rust/kernel/static_assert.rs | 2 +- rust/kernel/str.rs | 4 ++-- 5 files changed, 10 insertions(+), 10 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 5c372cf27ed0..539888465cc6 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -240,7 +240,7 @@ impl DeviceContext for Normal {} macro_rules! dev_printk { ($method:ident, $dev:expr, $($f:tt)*) => { { - ($dev).$method(core::format_args!($($f)*)); + ($dev).$method(::core::format_args!($($f)*)); } } } diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs index e5859217a579..0a4eb56d98f2 100644 --- a/rust/kernel/device_id.rs +++ b/rust/kernel/device_id.rs @@ -159,7 +159,7 @@ macro_rules! module_device_table { "_", line!(), "_", stringify!($table_name)) ] - static $module_table_name: [core::mem::MaybeUninit; $table_name.raw_ids().size()] = - unsafe { core::mem::transmute_copy($table_name.raw_ids()) }; + static $module_table_name: [::core::mem::MaybeUninit; $table_name.raw_ids().size()] = + unsafe { ::core::mem::transmute_copy($table_name.raw_ids()) }; }; } diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 1604fb6a5b1b..81833a687b75 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -59,7 +59,7 @@ macro_rules! kunit_assert { } static FILE: &'static $crate::str::CStr = $crate::c_str!($file); - static LINE: i32 = core::line!() as i32 - $diff; + static LINE: i32 = ::core::line!() as i32 - $diff; static CONDITION: &'static $crate::str::CStr = $crate::c_str!(stringify!($condition)); // SAFETY: FFI call without safety requirements. @@ -130,11 +130,11 @@ macro_rules! kunit_assert { unsafe { $crate::bindings::__kunit_do_failed_assertion( kunit_test, - core::ptr::addr_of!(LOCATION.0), + ::core::ptr::addr_of!(LOCATION.0), $crate::bindings::kunit_assert_type_KUNIT_ASSERTION, - core::ptr::addr_of!(ASSERTION.0.assert), + ::core::ptr::addr_of!(ASSERTION.0.assert), Some($crate::bindings::kunit_unary_assert_format), - core::ptr::null(), + ::core::ptr::null(), ); } diff --git a/rust/kernel/static_assert.rs b/rust/kernel/static_assert.rs index d8120f838260..a57ba14315a0 100644 --- a/rust/kernel/static_assert.rs +++ b/rust/kernel/static_assert.rs @@ -34,6 +34,6 @@ #[macro_export] macro_rules! static_assert { ($condition:expr $(,$arg:literal)?) => { - const _: () = core::assert!($condition $(,$arg)?); + const _: () = ::core::assert!($condition $(,$arg)?); }; } diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 98d5c74ec4f7..c554b243ebcb 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -595,7 +595,7 @@ mod tests { macro_rules! format { ($($f:tt)*) => ({ - &*String::from_fmt(kernel::fmt!($($f)*)) + &*String::from_fmt(::kernel::fmt!($($f)*)) }) } @@ -944,5 +944,5 @@ impl fmt::Debug for CString { /// A convenience alias for [`core::format_args`]. #[macro_export] macro_rules! fmt { - ($($f:tt)*) => ( core::format_args!($($f)*) ) + ($($f:tt)*) => ( ::core::format_args!($($f)*) ) } -- cgit v1.2.3 From 3d5bef5d47c371e17041cd6c84e9c08e54ea9e63 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 13 Apr 2025 02:56:50 +0200 Subject: rust: add C FFI types to the prelude Rust kernel code is supposed to use the custom mapping of C FFI types, i.e. those from the `ffi` crate, rather than the ones coming from `core`. Thus, to minimize mistakes and to simplify the code everywhere, just provide them in the `kernel` prelude and ask in the Coding Guidelines to use them directly, i.e. as a single segment path. After this lands, we can start cleaning up the existing users. Ideally, we would use something like Clippy's `disallowed-types` to prevent the use of the `core` ones, but that one sees through aliases. Link: https://lore.kernel.org/rust-for-linux/CANiq72kc4gzfieD-FjuWfELRDXXD2vLgPv4wqk3nt4pjdPQ=qg@mail.gmail.com/ Reviewed-by: Danilo Krummrich Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250413005650.1745894-1-ojeda@kernel.org [ Reworded content of the documentation to focus on how to use the aliases first. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/prelude.rs | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index baa774a351ce..f869b02f1f25 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -14,6 +14,11 @@ #[doc(no_inline)] pub use core::pin::Pin; +pub use ::ffi::{ + c_char, c_int, c_long, c_longlong, c_schar, c_short, c_uchar, c_uint, c_ulong, c_ulonglong, + c_ushort, c_void, +}; + pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec, Vec}; #[doc(no_inline)] -- cgit v1.2.3 From 9f047636831a61ce0840929555245dd17695206a Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 24 Mar 2025 22:03:55 +0100 Subject: rust: platform: fix docs related to missing Markdown code spans Convert `TODO` from documentation to a normal comment, and put code in block. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: 683a63befc73 ("rust: platform: add basic platform device / driver abstractions") Reviewed-by: Benno Lossin Acked-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/20250324210359.1199574-9-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/platform.rs | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs index fd4a494f30e8..a02ae5b25b74 100644 --- a/rust/kernel/platform.rs +++ b/rust/kernel/platform.rs @@ -151,10 +151,11 @@ macro_rules! module_platform_driver { ///``` pub trait Driver: Send { /// The type holding driver private data about each device id supported by the driver. - /// - /// TODO: Use associated_type_defaults once stabilized: - /// - /// type IdInfo: 'static = (); + // TODO: Use associated_type_defaults once stabilized: + // + // ``` + // type IdInfo: 'static = (); + // ``` type IdInfo: 'static; /// The table of OF device ids supported by the driver. -- cgit v1.2.3 From 673ec360cfb099a5f44dabee0f0e6c9b282efa7e Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 24 Mar 2025 22:03:50 +0100 Subject: rust: alloc: add missing Markdown code spans Add missing Markdown code spans. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: b6a006e21b82 ("rust: alloc: introduce allocation flags") Reviewed-by: Benno Lossin Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250324210359.1199574-4-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/alloc.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs index fc9c9c41cd79..a2c49e5494d3 100644 --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -94,10 +94,10 @@ pub mod flags { /// /// A lower watermark is applied to allow access to "atomic reserves". The current /// implementation doesn't support NMI and few other strict non-preemptive contexts (e.g. - /// raw_spin_lock). The same applies to [`GFP_NOWAIT`]. + /// `raw_spin_lock`). The same applies to [`GFP_NOWAIT`]. pub const GFP_ATOMIC: Flags = Flags(bindings::GFP_ATOMIC); - /// Typical for kernel-internal allocations. The caller requires ZONE_NORMAL or a lower zone + /// Typical for kernel-internal allocations. The caller requires `ZONE_NORMAL` or a lower zone /// for direct access but can direct reclaim. pub const GFP_KERNEL: Flags = Flags(bindings::GFP_KERNEL); -- cgit v1.2.3 From abd21a163d4188c180cabb6747b1d94e3c0586b9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 24 Mar 2025 22:03:51 +0100 Subject: rust: alloc: add missing Markdown code span Add missing Markdown code span. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: dd09538fb409 ("rust: alloc: implement `Cmalloc` in module allocator_test") Reviewed-by: Benno Lossin Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250324210359.1199574-5-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/allocator_test.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs index c37d4c0c64e9..d19c06ef0498 100644 --- a/rust/kernel/alloc/allocator_test.rs +++ b/rust/kernel/alloc/allocator_test.rs @@ -4,7 +4,7 @@ //! of those types (e.g. `CString`) use kernel allocators for instantiation. //! //! In order to allow userspace test cases to make use of such types as well, implement the -//! `Cmalloc` allocator within the allocator_test module and type alias all kernel allocators to +//! `Cmalloc` allocator within the `allocator_test` module and type alias all kernel allocators to //! `Cmalloc`. The `Cmalloc` allocator uses libc's `realloc()` function as allocator backend. #![allow(missing_docs)] -- cgit v1.2.3 From 1dbaf8b1bafb8557904eb54b98bb323a3061dd2c Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 24 Mar 2025 22:03:54 +0100 Subject: rust: pci: fix docs related to missing Markdown code spans In particular: - Add missing Markdown code spans. - Improve title for `DeviceId`, adding a link to the struct in the C side, rather than referring to `bindings::`. - Convert `TODO` from documentation to a normal comment, and put code in block. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: 1bd8b6b2c5d3 ("rust: pci: add basic PCI device / driver abstractions") Reviewed-by: Benno Lossin Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250324210359.1199574-8-ojeda@kernel.org [ Prefixed link text with `struct`. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/pci.rs | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs index 3aeb1250c27f..c17a32b76d74 100644 --- a/rust/kernel/pci.rs +++ b/rust/kernel/pci.rs @@ -118,7 +118,9 @@ macro_rules! module_pci_driver { }; } -/// Abstraction for bindings::pci_device_id. +/// Abstraction for the PCI device ID structure ([`struct pci_device_id`]). +/// +/// [`struct pci_device_id`]: https://docs.kernel.org/PCI/pci.html#c.pci_device_id #[repr(transparent)] #[derive(Clone, Copy)] pub struct DeviceId(bindings::pci_device_id); @@ -173,7 +175,7 @@ unsafe impl RawDeviceId for DeviceId { } } -/// IdTable type for PCI +/// `IdTable` type for PCI. pub type IdTable = &'static dyn kernel::device_id::IdTable; /// Create a PCI `IdTable` with its alias for modpost. @@ -224,10 +226,11 @@ macro_rules! pci_device_table { /// `Adapter` documentation for an example. pub trait Driver: Send { /// The type holding information about each device id supported by the driver. - /// - /// TODO: Use associated_type_defaults once stabilized: - /// - /// type IdInfo: 'static = (); + // TODO: Use `associated_type_defaults` once stabilized: + // + // ``` + // type IdInfo: 'static = (); + // ``` type IdInfo: 'static; /// The table of device ids supported by the driver. -- cgit v1.2.3 From f54c750333381bfeaa0e4a69b9563d4e4e21f1b3 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 24 Mar 2025 22:03:56 +0100 Subject: rust: task: add missing Markdown code spans and intra-doc links Add missing Markdown code spans and also convert them into intra-doc links. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: e0020ba6cbcb ("rust: add PidNamespace") Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250324210359.1199574-10-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/task.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index 9e6f6854948d..9dce3705ff63 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -158,10 +158,10 @@ impl Task { } } - /// Returns a PidNamespace reference for the currently executing task's/thread's pid namespace. + /// Returns a [`PidNamespace`] reference for the currently executing task's/thread's pid namespace. /// /// This function can be used to create an unbounded lifetime by e.g., storing the returned - /// PidNamespace in a global variable which would be a bug. So the recommended way to get the + /// [`PidNamespace`] in a global variable which would be a bug. So the recommended way to get the /// current task's/thread's pid namespace is to use the [`current_pid_ns`] macro because it is /// safe. /// -- cgit v1.2.3 From df523db15a06c37cbabad8f477ae87d08c9081f2 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 24 Mar 2025 22:03:52 +0100 Subject: rust: dma: add missing Markdown code span Add missing Markdown code span. This was found using the Clippy `doc_markdown` lint, which we may want to enable. Fixes: ad2907b4e308 ("rust: add dma coherent allocator abstraction") Reviewed-by: Benno Lossin Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250324210359.1199574-6-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/dma.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs index 8cdc76043ee7..35fd8a638473 100644 --- a/rust/kernel/dma.rs +++ b/rust/kernel/dma.rs @@ -94,7 +94,7 @@ pub mod attrs { pub const DMA_ATTR_ALLOC_SINGLE_PAGES: Attrs = Attrs(bindings::DMA_ATTR_ALLOC_SINGLE_PAGES); /// This tells the DMA-mapping subsystem to suppress allocation failure reports (similarly to - /// __GFP_NOWARN). + /// `__GFP_NOWARN`). pub const DMA_ATTR_NO_WARN: Attrs = Attrs(bindings::DMA_ATTR_NO_WARN); /// Used to indicate that the buffer is fully accessible at an elevated privilege level (and -- cgit v1.2.3 From 21d8a6857bc11f3fa14b19768d840cf6d1f3fccd Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 26 May 2025 11:05:03 +0530 Subject: rust: opp: Make the doctest example depend on CONFIG_OF The doctest example uses a function only available for CONFIG_OF and so the build with doc tests fails when it isn't enabled. error[E0599]: no function or associated item named `from_of_cpumask` found for struct `rust_doctest_kernel_alloc_kbox_rs_4::kernel::opp::Table` in the current scope Fix this by making the doctest depend on CONFIG_OF. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202505260856.ZQWHW2xT-lkp@intel.com/ Signed-off-by: Viresh Kumar Link: https://patch.msgid.link/a80bfedcb4d94531dc27d3b48062db5042078e88.1748237646.git.viresh.kumar@linaro.org Signed-off-by: Rafael J. Wysocki --- rust/kernel/opp.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust/kernel') diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs index 212555dacd45..c2bdc11f3999 100644 --- a/rust/kernel/opp.rs +++ b/rust/kernel/opp.rs @@ -582,6 +582,7 @@ impl Config { /// use kernel::opp::Table; /// use kernel::types::ARef; /// +/// #[cfg(CONFIG_OF)] /// fn get_table(dev: &ARef, mask: &mut Cpumask, freq: Hertz) -> Result
{ /// let mut opp_table = Table::from_of_cpumask(dev, mask)?; /// -- cgit v1.2.3 From eb71feaacaaca227ae8f91c8578cf831553c5ab5 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sun, 25 May 2025 19:34:45 +0200 Subject: rust: list: fix path of `assert_pinned!` Commit dbd5058ba60c ("rust: make pin-init its own crate") moved all items from pin-init into the pin-init crate, including the `assert_pinned!` macro. Thus fix the path of the sole user of the `assert_pinned!` macro. This occurrence was missed in the commit above, since it is in a macro rule that has no current users (although binder is a future user). Cc: stable@kernel.org Fixes: dbd5058ba60c ("rust: make pin-init its own crate") Signed-off-by: Benno Lossin Link: https://lore.kernel.org/r/20250525173450.853413-1-lossin@kernel.org [ Reworded slightly as discussed in the list. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/list/arc.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/list/arc.rs b/rust/kernel/list/arc.rs index 13c50df37b89..a88a2dc65aa7 100644 --- a/rust/kernel/list/arc.rs +++ b/rust/kernel/list/arc.rs @@ -96,7 +96,7 @@ macro_rules! impl_list_arc_safe { } $($rest:tt)*) => { impl$(<$($generics)*>)? $crate::list::ListArcSafe<$num> for $t { unsafe fn on_create_list_arc_from_unique(self: ::core::pin::Pin<&mut Self>) { - $crate::assert_pinned!($t, $field, $fty, inline); + ::pin_init::assert_pinned!($t, $field, $fty, inline); // SAFETY: This field is structurally pinned as per the above assertion. let field = unsafe { -- cgit v1.2.3 From 4bf7b97eb390f0a0730572101e0ce3367d31a770 Mon Sep 17 00:00:00 2001 From: Patrick Miller Date: Wed, 2 Oct 2024 02:28:48 +0000 Subject: rust: make section names plural Clean Rust documentation section headers to use plural names. Suggested-by: Miguel Ojeda Link: https://github.com/Rust-for-Linux/linux/issues/1110 Signed-off-by: Patrick Miller Link: https://lore.kernel.org/r/20241002022749.390836-1-paddymills@proton.me [ Removed the `init` one that doesn't apply anymore and reworded slightly. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/list/arc.rs | 2 +- rust/kernel/sync/arc.rs | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/list/arc.rs b/rust/kernel/list/arc.rs index a88a2dc65aa7..8401ddcd178a 100644 --- a/rust/kernel/list/arc.rs +++ b/rust/kernel/list/arc.rs @@ -464,7 +464,7 @@ where /// A utility for tracking whether a [`ListArc`] exists using an atomic. /// -/// # Invariant +/// # Invariants /// /// If the boolean is `false`, then there is no [`ListArc`] for this value. #[repr(transparent)] diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 356eef3afdae..c7af0aa48a0a 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -492,7 +492,7 @@ impl From>> for Arc { /// There are no mutable references to the underlying [`Arc`], and it remains valid for the /// lifetime of the [`ArcBorrow`] instance. /// -/// # Example +/// # Examples /// /// ``` /// use kernel::sync::{Arc, ArcBorrow}; -- cgit v1.2.3 From 15bc5c00d10fb643df7939d34438d50ffa732cb2 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 27 May 2025 11:03:26 +0530 Subject: rust: opp: Move `cfg(CONFIG_OF)` attribute to the top of doc test Move the `#[cfg(CONFIG_OF)]` attribute to the top of the documentation test block and hide it. This applies the condition to the entire test and improves readability. Placing configuration flags like `CONFIG_OF` at the top serves as a clear indicator of the conditions under which the example is valid, effectively acting like configuration metadata for the example itself. Suggested-by: Miguel Ojeda Signed-off-by: Viresh Kumar Link: https://patch.msgid.link/9d93c783cc4419f16dd8942a4359d74bc0149203.1748323971.git.viresh.kumar@linaro.org Signed-off-by: Rafael J. Wysocki --- rust/kernel/opp.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs index c2bdc11f3999..a566fc3e7dcb 100644 --- a/rust/kernel/opp.rs +++ b/rust/kernel/opp.rs @@ -575,6 +575,7 @@ impl Config { /// frequency. /// /// ``` +/// # #![cfg(CONFIG_OF)] /// use kernel::clk::Hertz; /// use kernel::cpumask::Cpumask; /// use kernel::device::Device; @@ -582,7 +583,6 @@ impl Config { /// use kernel::opp::Table; /// use kernel::types::ARef; /// -/// #[cfg(CONFIG_OF)] /// fn get_table(dev: &ARef, mask: &mut Cpumask, freq: Hertz) -> Result
{ /// let mut opp_table = Table::from_of_cpumask(dev, mask)?; /// -- cgit v1.2.3 From 36174d16f3ec072f9e07b6c6d59ba91b2d52f9e2 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 23:51:26 +0200 Subject: rust: kunit: support KUnit-mapped `assert!` macros in `#[test]`s The KUnit `#[test]` support that landed recently is very basic and does not map the `assert*!` macros into KUnit like the doctests do, so they panic at the moment. Thus implement the custom mapping in a similar way to doctests, reusing the infrastructure there. In Rust 1.88.0, the `file()` method in `Span` may be stable [1]. However, it was changed recently (from `SourceFile`), so we need to do something different in previous versions. Thus create a helper for it and use it to get the path. With this, a failing test suite like: #[kunit_tests(my_test_suite)] mod tests { use super::*; #[test] fn my_first_test() { assert_eq!(42, 43); } #[test] fn my_second_test() { assert!(42 >= 43); } } will properly map back to KUnit, printing something like: [ 1.924325] KTAP version 1 [ 1.924421] # Subtest: my_test_suite [ 1.924506] # speed: normal [ 1.924525] 1..2 [ 1.926385] # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251 [ 1.926385] Expected 42 == 43 to be true, but is false [ 1.928026] # my_first_test.speed: normal [ 1.928075] not ok 1 my_first_test [ 1.928723] # my_second_test: ASSERTION FAILED at rust/kernel/lib.rs:256 [ 1.928723] Expected 42 >= 43 to be true, but is false [ 1.929834] # my_second_test.speed: normal [ 1.929868] not ok 2 my_second_test [ 1.930032] # my_test_suite: pass:0 fail:2 skip:0 total:2 [ 1.930153] # Totals: pass:0 fail:2 skip:0 total Link: https://github.com/rust-lang/rust/pull/140514 [1] Reviewed-by: David Gow Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250502215133.1923676-2-ojeda@kernel.org [ Required `KUNIT=y` like for doctests. Used the `cfg_attr` from the TODO comment and clarified its comment now that the stabilization is in beta and thus quite likely stable in Rust 1.88.0. Simplified the `new_body` code by introducing a new variable. Added `#[allow(clippy::incompatible_msrv)]`. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/kunit.rs | 1 - 1 file changed, 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 81833a687b75..78b4acb6595f 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -323,7 +323,6 @@ mod tests { #[test] fn rust_test_kunit_example_test() { - #![expect(clippy::eq_op)] assert_eq!(1 + 1, 2); } -- cgit v1.2.3 From 950b306c296ec1e90d2d76f1974d2de2375a3d82 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 23:51:27 +0200 Subject: rust: kunit: support checked `-> Result`s in KUnit `#[test]`s Currently, return values of KUnit `#[test]` functions are ignored. Thus introduce support for `-> Result` functions by checking their returned values. At the same time, require that test functions return `()` or `Result`, which should avoid mistakes, especially with non-`#[must_use]` types. Other types can be supported in the future if needed. With this, a failing test like: #[test] fn my_test() -> Result { f()?; Ok(()) } will output: [ 3.744214] KTAP version 1 [ 3.744287] # Subtest: my_test_suite [ 3.744378] # speed: normal [ 3.744399] 1..1 [ 3.745817] # my_test: ASSERTION FAILED at rust/kernel/lib.rs:321 [ 3.745817] Expected is_test_result_ok(my_test()) to be true, but is false [ 3.747152] # my_test.speed: normal [ 3.747199] not ok 1 my_test [ 3.747345] not ok 4 my_test_suite Reviewed-by: David Gow Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250502215133.1923676-3-ojeda@kernel.org [ Used `::kernel` for paths. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/kunit.rs | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'rust/kernel') diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 78b4acb6595f..355e9d56dada 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -164,6 +164,31 @@ macro_rules! kunit_assert_eq { }}; } +trait TestResult { + fn is_test_result_ok(&self) -> bool; +} + +impl TestResult for () { + fn is_test_result_ok(&self) -> bool { + true + } +} + +impl TestResult for Result { + fn is_test_result_ok(&self) -> bool { + self.is_ok() + } +} + +/// Returns whether a test result is to be considered OK. +/// +/// This will be `assert!`ed from the generated tests. +#[doc(hidden)] +#[expect(private_bounds)] +pub fn is_test_result_ok(t: impl TestResult) -> bool { + t.is_test_result_ok() +} + /// Represents an individual test case. /// /// The [`kunit_unsafe_test_suite!`] macro expects a NULL-terminated list of valid test cases. -- cgit v1.2.3 From 897d1df6532f05814acd364af9055cd6628fd1b3 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 23:51:28 +0200 Subject: rust: add `kunit_tests` to the prelude It is convenient to have certain things in the `kernel` prelude, and means kernel developers will find it even easier to start writing tests. And, anyway, nobody should need to use this identifier for anything else. Thus add it to the prelude. Reviewed-by: David Gow Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250502215133.1923676-4-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/kunit.rs | 3 +-- rust/kernel/prelude.rs | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index 355e9d56dada..4b8cdcb21e77 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -6,6 +6,7 @@ //! //! Reference: +use crate::prelude::*; use core::{ffi::c_void, fmt}; /// Prints a KUnit error-level message. @@ -40,8 +41,6 @@ pub fn info(args: fmt::Arguments<'_>) { } } -use macros::kunit_tests; - /// Asserts that a boolean expression is `true` at runtime. /// /// Public but hidden since it should only be used from generated tests. diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index f869b02f1f25..2f30a398dddd 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -22,7 +22,7 @@ pub use ::ffi::{ pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec, Vec}; #[doc(no_inline)] -pub use macros::{export, module, vtable}; +pub use macros::{export, kunit_tests, module, vtable}; pub use pin_init::{init, pin_data, pin_init, pinned_drop, InPlaceWrite, Init, PinInit, Zeroable}; -- cgit v1.2.3 From 028df914e5466a02326829427bb8e26a31a05545 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 23:51:29 +0200 Subject: rust: str: convert `rusttest` tests into KUnit In general, we should aim to test as much as possible within the actual kernel, and not in the build host. Thus convert these `rusttest` tests into KUnit tests. Reviewed-by: David Gow Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250502215133.1923676-5-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/str.rs | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index c554b243ebcb..9b5228025e2c 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -6,7 +6,7 @@ use crate::alloc::{flags::*, AllocError, KVec}; use core::fmt::{self, Write}; use core::ops::{self, Deref, DerefMut, Index}; -use crate::error::{code::*, Error}; +use crate::prelude::*; /// Byte string without UTF-8 validity guarantee. #[repr(transparent)] @@ -572,8 +572,7 @@ macro_rules! c_str { }}; } -#[cfg(test)] -#[expect(clippy::items_after_test_module)] +#[kunit_tests(rust_kernel_str)] mod tests { use super::*; @@ -622,11 +621,10 @@ mod tests { } #[test] - #[should_panic] - fn test_cstr_to_str_panic() { + fn test_cstr_to_str_invalid_utf8() { let bad_bytes = b"\xc3\x28\0"; let checked_cstr = CStr::from_bytes_with_nul(bad_bytes).unwrap(); - checked_cstr.to_str().unwrap(); + assert!(checked_cstr.to_str().is_err()); } #[test] -- cgit v1.2.3 From 1486554392e242da5cbe95092d8dfec887bb8cca Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 26 May 2025 20:01:42 +0200 Subject: rust: str: simplify KUnit tests `format!` macro Simplify the `format!` macro used in the tests by using `CString::try_from_fmt` and directly `unwrap()`ing. This will allow us to change both `unwrap()`s here in order to showcase the `?` operator support now that the tests are KUnit ones. Reviewed-by: David Gow Acked-by: Danilo Krummrich [ Split from the next commit as suggested by Tamir. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/str.rs | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 9b5228025e2c..52a500742c1a 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -576,25 +576,9 @@ macro_rules! c_str { mod tests { use super::*; - struct String(CString); - - impl String { - fn from_fmt(args: fmt::Arguments<'_>) -> Self { - String(CString::try_from_fmt(args).unwrap()) - } - } - - impl Deref for String { - type Target = str; - - fn deref(&self) -> &str { - self.0.to_str().unwrap() - } - } - macro_rules! format { ($($f:tt)*) => ({ - &*String::from_fmt(::kernel::fmt!($($f)*)) + CString::try_from_fmt(::kernel::fmt!($($f)*)).unwrap().to_str().unwrap() }) } -- cgit v1.2.3 From 2d6c87d0d6a0c0acf6b4dd9eec9ed44a82886836 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 2 May 2025 23:51:30 +0200 Subject: rust: str: take advantage of the `-> Result` support in KUnit `#[test]`'s Since now we have support for returning `-> Result`s, we can convert some of these tests to use the feature, and serve as a first user for it too. Thus convert them, which allows us to remove some `unwrap()`s. We keep the actual assertions we want to make as explicit ones with `assert*!`s. Reviewed-by: David Gow Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250502215133.1923676-6-ojeda@kernel.org [ Split the `CString` simplification into a new commit. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/str.rs | 52 ++++++++++++++++++++++++++++++---------------------- 1 file changed, 30 insertions(+), 22 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index 52a500742c1a..a927db8e079c 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -578,7 +578,7 @@ mod tests { macro_rules! format { ($($f:tt)*) => ({ - CString::try_from_fmt(::kernel::fmt!($($f)*)).unwrap().to_str().unwrap() + CString::try_from_fmt(::kernel::fmt!($($f)*))?.to_str()? }) } @@ -597,66 +597,72 @@ mod tests { \\xf0\\xf1\\xf2\\xf3\\xf4\\xf5\\xf6\\xf7\\xf8\\xf9\\xfa\\xfb\\xfc\\xfd\\xfe\\xff"; #[test] - fn test_cstr_to_str() { + fn test_cstr_to_str() -> Result { let good_bytes = b"\xf0\x9f\xa6\x80\0"; - let checked_cstr = CStr::from_bytes_with_nul(good_bytes).unwrap(); - let checked_str = checked_cstr.to_str().unwrap(); + let checked_cstr = CStr::from_bytes_with_nul(good_bytes)?; + let checked_str = checked_cstr.to_str()?; assert_eq!(checked_str, "🦀"); + Ok(()) } #[test] - fn test_cstr_to_str_invalid_utf8() { + fn test_cstr_to_str_invalid_utf8() -> Result { let bad_bytes = b"\xc3\x28\0"; - let checked_cstr = CStr::from_bytes_with_nul(bad_bytes).unwrap(); + let checked_cstr = CStr::from_bytes_with_nul(bad_bytes)?; assert!(checked_cstr.to_str().is_err()); + Ok(()) } #[test] - fn test_cstr_as_str_unchecked() { + fn test_cstr_as_str_unchecked() -> Result { let good_bytes = b"\xf0\x9f\x90\xA7\0"; - let checked_cstr = CStr::from_bytes_with_nul(good_bytes).unwrap(); + let checked_cstr = CStr::from_bytes_with_nul(good_bytes)?; // SAFETY: The contents come from a string literal which contains valid UTF-8. let unchecked_str = unsafe { checked_cstr.as_str_unchecked() }; assert_eq!(unchecked_str, "🐧"); + Ok(()) } #[test] - fn test_cstr_display() { - let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap(); + fn test_cstr_display() -> Result { + let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0")?; assert_eq!(format!("{hello_world}"), "hello, world!"); - let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap(); + let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0")?; assert_eq!(format!("{non_printables}"), "\\x01\\x09\\x0a"); - let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap(); + let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0")?; assert_eq!(format!("{non_ascii}"), "d\\xe9j\\xe0 vu"); - let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap(); + let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0")?; assert_eq!(format!("{good_bytes}"), "\\xf0\\x9f\\xa6\\x80"); + Ok(()) } #[test] - fn test_cstr_display_all_bytes() { + fn test_cstr_display_all_bytes() -> Result { let mut bytes: [u8; 256] = [0; 256]; // fill `bytes` with [1..=255] + [0] for i in u8::MIN..=u8::MAX { bytes[i as usize] = i.wrapping_add(1); } - let cstr = CStr::from_bytes_with_nul(&bytes).unwrap(); + let cstr = CStr::from_bytes_with_nul(&bytes)?; assert_eq!(format!("{cstr}"), ALL_ASCII_CHARS); + Ok(()) } #[test] - fn test_cstr_debug() { - let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0").unwrap(); + fn test_cstr_debug() -> Result { + let hello_world = CStr::from_bytes_with_nul(b"hello, world!\0")?; assert_eq!(format!("{hello_world:?}"), "\"hello, world!\""); - let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0").unwrap(); + let non_printables = CStr::from_bytes_with_nul(b"\x01\x09\x0a\0")?; assert_eq!(format!("{non_printables:?}"), "\"\\x01\\x09\\x0a\""); - let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0").unwrap(); + let non_ascii = CStr::from_bytes_with_nul(b"d\xe9j\xe0 vu\0")?; assert_eq!(format!("{non_ascii:?}"), "\"d\\xe9j\\xe0 vu\""); - let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0").unwrap(); + let good_bytes = CStr::from_bytes_with_nul(b"\xf0\x9f\xa6\x80\0")?; assert_eq!(format!("{good_bytes:?}"), "\"\\xf0\\x9f\\xa6\\x80\""); + Ok(()) } #[test] - fn test_bstr_display() { + fn test_bstr_display() -> Result { let hello_world = BStr::from_bytes(b"hello, world!"); assert_eq!(format!("{hello_world}"), "hello, world!"); let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_"); @@ -667,10 +673,11 @@ mod tests { assert_eq!(format!("{non_ascii}"), "d\\xe9j\\xe0 vu"); let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80"); assert_eq!(format!("{good_bytes}"), "\\xf0\\x9f\\xa6\\x80"); + Ok(()) } #[test] - fn test_bstr_debug() { + fn test_bstr_debug() -> Result { let hello_world = BStr::from_bytes(b"hello, world!"); assert_eq!(format!("{hello_world:?}"), "\"hello, world!\""); let escapes = BStr::from_bytes(b"_\t_\n_\r_\\_\'_\"_"); @@ -681,6 +688,7 @@ mod tests { assert_eq!(format!("{non_ascii:?}"), "\"d\\xe9j\\xe0 vu\""); let good_bytes = BStr::from_bytes(b"\xf0\x9f\xa6\x80"); assert_eq!(format!("{good_bytes:?}"), "\"\\xf0\\x9f\\xa6\\x80\""); + Ok(()) } } -- cgit v1.2.3 From 74d6a606c2b39fd830d2d7a6363bc5688b4e4b56 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Wed, 9 Apr 2025 10:43:16 -0400 Subject: rust: retain pointer mut-ness in `container_of!` Avoid casting the input pointer to `*const _`, allowing the output pointer to be `*mut` if the input is `*mut`. This allows a number of `*const` to `*mut` conversions to be removed at the cost of slightly worse ergonomics when the macro is used with a reference rather than a pointer; the only example of this was in the macro's own doctest. Reviewed-by: Benno Lossin Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20250409-container-of-mutness-v1-1-64f472b94534@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 5 ++--- rust/kernel/rbtree.rs | 23 ++++++++++------------- 2 files changed, 12 insertions(+), 16 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 6e9287136cac..909d305d0be8 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -205,7 +205,7 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { /// } /// /// let test = Test { a: 10, b: 20 }; -/// let b_ptr = &test.b; +/// let b_ptr: *const _ = &test.b; /// // SAFETY: The pointer points at the `b` field of a `Test`, so the resulting pointer will be /// // in-bounds of the same allocation as `b_ptr`. /// let test_alias = unsafe { container_of!(b_ptr, Test, b) }; @@ -214,9 +214,8 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { #[macro_export] macro_rules! container_of { ($ptr:expr, $type:ty, $($f:tt)*) => {{ - let ptr = $ptr as *const _ as *const u8; let offset: usize = ::core::mem::offset_of!($type, $($f)*); - ptr.sub(offset) as *const $type + $ptr.byte_sub(offset).cast::<$type>() }} } diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs index 5246b2c8a4ff..8d978c896747 100644 --- a/rust/kernel/rbtree.rs +++ b/rust/kernel/rbtree.rs @@ -424,7 +424,7 @@ where while !node.is_null() { // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(node, Node, links) }.cast_mut(); + let this = unsafe { container_of!(node, Node, links) }; // SAFETY: `this` is a non-null node so it is valid by the type invariants. let this_key = unsafe { &(*this).key }; // SAFETY: `node` is a non-null node so it is valid by the type invariants. @@ -496,7 +496,7 @@ impl Drop for RBTree { // but it is not observable. The loop invariant is still maintained. // SAFETY: `this` is valid per the loop invariant. - unsafe { drop(KBox::from_raw(this.cast_mut())) }; + unsafe { drop(KBox::from_raw(this)) }; } } } @@ -761,7 +761,7 @@ impl<'a, K, V> Cursor<'a, K, V> { let next = self.get_neighbor_raw(Direction::Next); // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(self.current.as_ptr(), Node, links) }.cast_mut(); + let this = unsafe { container_of!(self.current.as_ptr(), Node, links) }; // SAFETY: `this` is valid by the type invariants as described above. let node = unsafe { KBox::from_raw(this) }; let node = RBTreeNode { node }; @@ -806,7 +806,7 @@ impl<'a, K, V> Cursor<'a, K, V> { unsafe { bindings::rb_erase(neighbor, addr_of_mut!(self.tree.root)) }; // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(neighbor, Node, links) }.cast_mut(); + let this = unsafe { container_of!(neighbor, Node, links) }; // SAFETY: `this` is valid by the type invariants as described above. let node = unsafe { KBox::from_raw(this) }; return Some(RBTreeNode { node }); @@ -912,7 +912,7 @@ impl<'a, K, V> Cursor<'a, K, V> { unsafe fn to_key_value_raw<'b>(node: NonNull) -> (&'b K, *mut V) { // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(node.as_ptr(), Node, links) }.cast_mut(); + let this = unsafe { container_of!(node.as_ptr(), Node, links) }; // SAFETY: The passed `node` is the current node or a non-null neighbor, // thus `this` is valid by the type invariants. let k = unsafe { &(*this).key }; @@ -1021,7 +1021,7 @@ impl Iterator for IterRaw { // SAFETY: By the type invariant of `IterRaw`, `self.next` is a valid node in an `RBTree`, // and by the type invariant of `RBTree`, all nodes point to the links field of `Node` objects. - let cur = unsafe { container_of!(self.next, Node, links) }.cast_mut(); + let cur = unsafe { container_of!(self.next, Node, links) }; // SAFETY: `self.next` is a valid tree node by the type invariants. self.next = unsafe { bindings::rb_next(self.next) }; @@ -1216,7 +1216,7 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { // SAFETY: // - `self.node_links` is a valid pointer to a node in the tree. // - We have exclusive access to the underlying tree, and can thus give out a mutable reference. - unsafe { &mut (*(container_of!(self.node_links, Node, links).cast_mut())).value } + unsafe { &mut (*(container_of!(self.node_links, Node, links))).value } } /// Converts the entry into a mutable reference to its value. @@ -1226,7 +1226,7 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { // SAFETY: // - `self.node_links` is a valid pointer to a node in the tree. // - This consumes the `&'a mut RBTree`, therefore it can give out a mutable reference that lives for `'a`. - unsafe { &mut (*(container_of!(self.node_links, Node, links).cast_mut())).value } + unsafe { &mut (*(container_of!(self.node_links, Node, links))).value } } /// Remove this entry from the [`RBTree`]. @@ -1239,9 +1239,7 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { RBTreeNode { // SAFETY: The node was a node in the tree, but we removed it, so we can convert it // back into a box. - node: unsafe { - KBox::from_raw(container_of!(self.node_links, Node, links).cast_mut()) - }, + node: unsafe { KBox::from_raw(container_of!(self.node_links, Node, links)) }, } } @@ -1272,8 +1270,7 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { // SAFETY: // - `self.node_ptr` produces a valid pointer to a node in the tree. // - Now that we removed this entry from the tree, we can convert the node to a box. - let old_node = - unsafe { KBox::from_raw(container_of!(self.node_links, Node, links).cast_mut()) }; + let old_node = unsafe { KBox::from_raw(container_of!(self.node_links, Node, links)) }; RBTreeNode { node: old_node } } -- cgit v1.2.3 From 1ce98bb2bb30713ec4374ef11ead0d7d3e856766 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Fri, 11 Apr 2025 10:08:27 -0400 Subject: rust: workqueue: remove HasWork::OFFSET Implement `HasWork::work_container_of` in `impl_has_work!`, narrowing the interface of `HasWork` and replacing pointer arithmetic with `container_of!`. Remove the provided implementation of `HasWork::get_work_offset` without replacement; an implementation is already generated in `impl_has_work!`. Remove the `Self: Sized` bound on `HasWork::work_container_of` which was apparently necessary to access `OFFSET` as `OFFSET` no longer exists. A similar API change was discussed on the hrtimer series[1]. Link: https://lore.kernel.org/all/20250224-hrtimer-v3-v6-12-rc2-v9-1-5bd3bf0ce6cc@kernel.org/ [1] Reviewed-by: Benno Lossin Reviewed-by: Alice Ryhl Tested-by: Alice Ryhl Reviewed-by: Andreas Hindborg Signed-off-by: Tamir Duberstein Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20250411-no-offset-v3-1-c0b174640ec3@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/workqueue.rs | 50 ++++++++++++++++-------------------------------- 1 file changed, 17 insertions(+), 33 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs index f98bd02b838f..d092112d843f 100644 --- a/rust/kernel/workqueue.rs +++ b/rust/kernel/workqueue.rs @@ -429,51 +429,28 @@ impl Work { /// /// # Safety /// -/// The [`OFFSET`] constant must be the offset of a field in `Self` of type [`Work`]. The -/// methods on this trait must have exactly the behavior that the definitions given below have. +/// The methods [`raw_get_work`] and [`work_container_of`] must return valid pointers and must be +/// true inverses of each other; that is, they must satisfy the following invariants: +/// - `work_container_of(raw_get_work(ptr)) == ptr` for any `ptr: *mut Self`. +/// - `raw_get_work(work_container_of(ptr)) == ptr` for any `ptr: *mut Work`. /// /// [`impl_has_work!`]: crate::impl_has_work -/// [`OFFSET`]: HasWork::OFFSET +/// [`raw_get_work`]: HasWork::raw_get_work +/// [`work_container_of`]: HasWork::work_container_of pub unsafe trait HasWork { - /// The offset of the [`Work`] field. - const OFFSET: usize; - - /// Returns the offset of the [`Work`] field. - /// - /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not - /// [`Sized`]. - /// - /// [`OFFSET`]: HasWork::OFFSET - #[inline] - fn get_work_offset(&self) -> usize { - Self::OFFSET - } - /// Returns a pointer to the [`Work`] field. /// /// # Safety /// /// The provided pointer must point at a valid struct of type `Self`. - #[inline] - unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work { - // SAFETY: The caller promises that the pointer is valid. - unsafe { (ptr as *mut u8).add(Self::OFFSET) as *mut Work } - } + unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work; /// Returns a pointer to the struct containing the [`Work`] field. /// /// # Safety /// /// The pointer must point at a [`Work`] field in a struct of type `Self`. - #[inline] - unsafe fn work_container_of(ptr: *mut Work) -> *mut Self - where - Self: Sized, - { - // SAFETY: The caller promises that the pointer points at a field of the right type in the - // right kind of struct. - unsafe { (ptr as *mut u8).sub(Self::OFFSET) as *mut Self } - } + unsafe fn work_container_of(ptr: *mut Work) -> *mut Self; } /// Used to safely implement the [`HasWork`] trait. @@ -504,8 +481,6 @@ macro_rules! impl_has_work { // SAFETY: The implementation of `raw_get_work` only compiles if the field has the right // type. unsafe impl$(<$($generics)+>)? $crate::workqueue::HasWork<$work_type $(, $id)?> for $self { - const OFFSET: usize = ::core::mem::offset_of!(Self, $field) as usize; - #[inline] unsafe fn raw_get_work(ptr: *mut Self) -> *mut $crate::workqueue::Work<$work_type $(, $id)?> { // SAFETY: The caller promises that the pointer is not dangling. @@ -513,6 +488,15 @@ macro_rules! impl_has_work { ::core::ptr::addr_of_mut!((*ptr).$field) } } + + #[inline] + unsafe fn work_container_of( + ptr: *mut $crate::workqueue::Work<$work_type $(, $id)?>, + ) -> *mut Self { + // SAFETY: The caller promises that the pointer points at a field of the right type + // in the right kind of struct. + unsafe { $crate::container_of!(ptr, Self, $field) } + } } )*}; } -- cgit v1.2.3 From b20fbbc08a363f28fd0f3ad5163b2b0ff7605ba5 Mon Sep 17 00:00:00 2001 From: Tamir Duberstein Date: Thu, 29 May 2025 09:11:33 -0400 Subject: rust: check type of `$ptr` in `container_of!` Add a compile-time check that `*$ptr` is of the type of `$type->$($f)*`. Rename those placeholders for clarity. Given the incorrect usage: > diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs > index 8d978c896747..6a7089149878 100644 > --- a/rust/kernel/rbtree.rs > +++ b/rust/kernel/rbtree.rs > @@ -329,7 +329,7 @@ fn raw_entry(&mut self, key: &K) -> RawEntry<'_, K, V> { > while !(*child_field_of_parent).is_null() { > let curr = *child_field_of_parent; > // SAFETY: All links fields we create are in a `Node`. > - let node = unsafe { container_of!(curr, Node, links) }; > + let node = unsafe { container_of!(curr, Node, key) }; > > // SAFETY: `node` is a non-null node so it is valid by the type invariants. > match key.cmp(unsafe { &(*node).key }) { this patch produces the compilation error: > error[E0308]: mismatched types > --> rust/kernel/lib.rs:220:45 > | > 220 | $crate::assert_same_type(field_ptr, (&raw const (*container_ptr).$($fields)*).cast_mut()); > | ------------------------ --------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `*mut rb_node`, found `*mut K` > | | | > | | expected all arguments to be this `*mut bindings::rb_node` type because they need to match the type of this parameter > | arguments to this function are incorrect > | > ::: rust/kernel/rbtree.rs:270:6 > | > 270 | impl RBTree > | - found this type parameter > ... > 332 | let node = unsafe { container_of!(curr, Node, key) }; > | ------------------------------------ in this macro invocation > | > = note: expected raw pointer `*mut bindings::rb_node` > found raw pointer `*mut K` > note: function defined here > --> rust/kernel/lib.rs:227:8 > | > 227 | pub fn assert_same_type(_: T, _: T) {} > | ^^^^^^^^^^^^^^^^ - ---- ---- this parameter needs to match the `*mut bindings::rb_node` type of parameter #1 > | | | > | | parameter #2 needs to match the `*mut bindings::rb_node` type of this parameter > | parameter #1 and parameter #2 both reference this parameter `T` > = note: this error originates in the macro `container_of` (in Nightly builds, run with -Z macro-backtrace for more info) [ We decided to go with a variation of v1 [1] that became v4, since it seems like the obvious approach, the error messages seem good enough and the debug performance should be fine, given the kernel is always built with -O2. In the future, we may want to make the helper non-hidden, with proper documentation, for others to use. [1] https://lore.kernel.org/rust-for-linux/CANiq72kQWNfSV0KK6qs6oJt+aGdgY=hXg=wJcmK3zYcokY1LNw@mail.gmail.com/ - Miguel ] Suggested-by: Alice Ryhl Link: https://lore.kernel.org/all/CAH5fLgh6gmqGBhPMi2SKn7mCmMWfOSiS0WP5wBuGPYh9ZTAiww@mail.gmail.com/ Signed-off-by: Tamir Duberstein Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250529-b4-container-of-type-check-v4-1-bf3a7ad73cec@gmail.com [ Added intra-doc link. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 909d305d0be8..7e227b52b4d8 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -213,12 +213,19 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { /// ``` #[macro_export] macro_rules! container_of { - ($ptr:expr, $type:ty, $($f:tt)*) => {{ - let offset: usize = ::core::mem::offset_of!($type, $($f)*); - $ptr.byte_sub(offset).cast::<$type>() + ($field_ptr:expr, $Container:ty, $($fields:tt)*) => {{ + let offset: usize = ::core::mem::offset_of!($Container, $($fields)*); + let field_ptr = $field_ptr; + let container_ptr = field_ptr.byte_sub(offset).cast::<$Container>(); + $crate::assert_same_type(field_ptr, (&raw const (*container_ptr).$($fields)*).cast_mut()); + container_ptr }} } +/// Helper for [`container_of!`]. +#[doc(hidden)] +pub fn assert_same_type(_: T, _: T) {} + /// Helper for `.rs.S` files. #[doc(hidden)] #[macro_export] -- cgit v1.2.3 From 7a17bbc1d952057898cb0739e60665908fbb8c72 Mon Sep 17 00:00:00 2001 From: Sylvan Smit Date: Thu, 29 May 2025 18:29:23 +0200 Subject: rust: list: Fix typo `much` in arc.rs Correct the typo (s/much/must) in the ListArc documentation. Reported-by: Miguel Ojeda Closes: https://github.com/Rust-for-Linux/linux/issues/1166 Fixes: a48026315cd7 ("rust: list: add tracking for ListArc") Signed-off-by: Sylvan Smit Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250529162923.434978-1-sylvan@sylvansmit.com [ Changed tag to "Reported-by" and sorted. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/list/arc.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel') diff --git a/rust/kernel/list/arc.rs b/rust/kernel/list/arc.rs index 8401ddcd178a..d92bcf665c89 100644 --- a/rust/kernel/list/arc.rs +++ b/rust/kernel/list/arc.rs @@ -74,7 +74,7 @@ pub unsafe trait TryNewListArc: ListArcSafe { /// /// * The `untracked` strategy does not actually keep track of whether a [`ListArc`] exists. When /// using this strategy, the only way to create a [`ListArc`] is using a [`UniqueArc`]. -/// * The `tracked_by` strategy defers the tracking to a field of the struct. The user much specify +/// * The `tracked_by` strategy defers the tracking to a field of the struct. The user must specify /// which field to defer the tracking to. The field must implement [`ListArcSafe`]. If the field /// implements [`TryNewListArc`], then the type will also implement [`TryNewListArc`]. /// -- cgit v1.2.3 From 15ecd83dc06277385ad71dc7ea26911d9a79acaf Mon Sep 17 00:00:00 2001 From: Pekka Ristola Date: Tue, 27 May 2025 20:48:55 +0000 Subject: rust: file: mark `LocalFile` as `repr(transparent)` Unsafe code in `LocalFile`'s methods assumes that the type has the same layout as the inner `bindings::file`. This is not guaranteed by the default struct representation in Rust, but requires specifying the `transparent` representation. The `File` struct (which also wraps `bindings::file`) is already marked as `repr(transparent)`, so this change makes their layouts equivalent. Fixes: 851849824bb5 ("rust: file: add Rust abstraction for `struct file`") Closes: https://github.com/Rust-for-Linux/linux/issues/1165 Signed-off-by: Pekka Ristola Link: https://lore.kernel.org/20250527204636.12573-1-pekkarr@protonmail.com Reviewed-by: Benno Lossin Reviewed-by: Alice Ryhl Signed-off-by: Christian Brauner --- rust/kernel/fs/file.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust/kernel') diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs index 13a0e44cd1aa..138693bdeb3f 100644 --- a/rust/kernel/fs/file.rs +++ b/rust/kernel/fs/file.rs @@ -219,6 +219,7 @@ unsafe impl AlwaysRefCounted for File { /// must be on the same thread as this file. /// /// [`assume_no_fdget_pos`]: LocalFile::assume_no_fdget_pos +#[repr(transparent)] pub struct LocalFile { inner: Opaque, } -- cgit v1.2.3 From 946026ba4293a14970b4b0b72f5f0cbb698ad77e Mon Sep 17 00:00:00 2001 From: Pekka Ristola Date: Tue, 27 May 2025 20:48:59 +0000 Subject: rust: file: improve safety comments Some of the safety comments in `LocalFile`'s methods incorrectly refer to the `File` type instead of `LocalFile`, so fix them to use the correct type. Also add missing Markdown code spans around lifetimes in the safety comments, i.e. change 'a to `'a`. Link: https://github.com/Rust-for-Linux/linux/issues/1165 Signed-off-by: Pekka Ristola Link: https://lore.kernel.org/20250527204636.12573-2-pekkarr@protonmail.com Reviewed-by: Benno Lossin Reviewed-by: Alice Ryhl Signed-off-by: Christian Brauner --- rust/kernel/fs/file.rs | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'rust/kernel') diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs index 138693bdeb3f..72d84fb0e266 100644 --- a/rust/kernel/fs/file.rs +++ b/rust/kernel/fs/file.rs @@ -225,7 +225,7 @@ pub struct LocalFile { } // SAFETY: The type invariants guarantee that `LocalFile` is always ref-counted. This implementation -// makes `ARef` own a normal refcount. +// makes `ARef` own a normal refcount. unsafe impl AlwaysRefCounted for LocalFile { #[inline] fn inc_ref(&self) { @@ -236,7 +236,8 @@ unsafe impl AlwaysRefCounted for LocalFile { #[inline] unsafe fn dec_ref(obj: ptr::NonNull) { // SAFETY: To call this method, the caller passes us ownership of a normal refcount, so we - // may drop it. The cast is okay since `File` has the same representation as `struct file`. + // may drop it. The cast is okay since `LocalFile` has the same representation as + // `struct file`. unsafe { bindings::fput(obj.cast().as_ptr()) } } } @@ -274,7 +275,7 @@ impl LocalFile { #[inline] pub unsafe fn from_raw_file<'a>(ptr: *const bindings::file) -> &'a LocalFile { // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the - // duration of 'a. The cast is okay because `File` is `repr(transparent)`. + // duration of `'a`. The cast is okay because `LocalFile` is `repr(transparent)`. // // INVARIANT: The caller guarantees that there are no problematic `fdget_pos` calls. unsafe { &*ptr.cast() } @@ -348,7 +349,7 @@ impl File { #[inline] pub unsafe fn from_raw_file<'a>(ptr: *const bindings::file) -> &'a File { // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the - // duration of 'a. The cast is okay because `File` is `repr(transparent)`. + // duration of `'a`. The cast is okay because `File` is `repr(transparent)`. // // INVARIANT: The caller guarantees that there are no problematic `fdget_pos` calls. unsafe { &*ptr.cast() } -- cgit v1.2.3 From 5a78977262f47dd52a4880689a2ca3d21dbf149a Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 16 May 2025 19:32:19 +0000 Subject: mm: rust: make CONFIG_MMU ifdefs more narrow Currently the entire kernel::mm module is ifdef'd out when CONFIG_MMU=n. However, there are some downstream users of the module in rust/kernel/task.rs and rust/kernel/miscdevice.rs. Thus, update the cfgs so that only MmWithUserAsync is removed with CONFIG_MMU=n. The code is moved into a new file, since the #[cfg()] annotation otherwise has to be duplicated several times. Link: https://lkml.kernel.org/r/20250516193219.2987032-1-aliceryhl@google.com Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202505071753.kldNHYVQ-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202505072116.eSYC8igT-lkp@intel.com/ Fixes: 5bb9ed6cdfeb ("mm: rust: add abstraction for struct mm_struct") Signed-off-by: Alice Ryhl Reviewed-by: Boqun Feng Cc: Boqun Feng Cc: Liam Howlett Cc: Lorenzo Stoakes Signed-off-by: Andrew Morton --- rust/kernel/mm.rs | 56 +++-------------------------------- rust/kernel/mm/mmput_async.rs | 68 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 72 insertions(+), 52 deletions(-) create mode 100644 rust/kernel/mm/mmput_async.rs (limited to 'rust/kernel') diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs index 615907a0f3b4..43f525c0d16c 100644 --- a/rust/kernel/mm.rs +++ b/rust/kernel/mm.rs @@ -10,7 +10,6 @@ //! control what happens when userspace reads or writes to that region of memory. //! //! C header: [`include/linux/mm.h`](srctree/include/linux/mm.h) -#![cfg(CONFIG_MMU)] use crate::{ bindings, @@ -21,6 +20,10 @@ use core::{ops::Deref, ptr::NonNull}; pub mod virt; use virt::VmaRef; +#[cfg(CONFIG_MMU)] +pub use mmput_async::MmWithUserAsync; +mod mmput_async; + /// A wrapper for the kernel's `struct mm_struct`. /// /// This represents the address space of a userspace process, so each process has one `Mm` @@ -111,50 +114,6 @@ impl Deref for MmWithUser { } } -/// A wrapper for the kernel's `struct mm_struct`. -/// -/// This type is identical to `MmWithUser` except that it uses `mmput_async` when dropping a -/// refcount. This means that the destructor of `ARef` is safe to call in atomic -/// context. -/// -/// # Invariants -/// -/// Values of this type are always refcounted using `mmget`. The value of `mm_users` is non-zero. -#[repr(transparent)] -pub struct MmWithUserAsync { - mm: MmWithUser, -} - -// SAFETY: It is safe to call `mmput_async` on another thread than where `mmget` was called. -unsafe impl Send for MmWithUserAsync {} -// SAFETY: All methods on `MmWithUserAsync` can be called in parallel from several threads. -unsafe impl Sync for MmWithUserAsync {} - -// SAFETY: By the type invariants, this type is always refcounted. -unsafe impl AlwaysRefCounted for MmWithUserAsync { - #[inline] - fn inc_ref(&self) { - // SAFETY: The pointer is valid since self is a reference. - unsafe { bindings::mmget(self.as_raw()) }; - } - - #[inline] - unsafe fn dec_ref(obj: NonNull) { - // SAFETY: The caller is giving up their refcount. - unsafe { bindings::mmput_async(obj.cast().as_ptr()) }; - } -} - -// Make all `MmWithUser` methods available on `MmWithUserAsync`. -impl Deref for MmWithUserAsync { - type Target = MmWithUser; - - #[inline] - fn deref(&self) -> &MmWithUser { - &self.mm - } -} - // These methods are safe to call even if `mm_users` is zero. impl Mm { /// Returns a raw pointer to the inner `mm_struct`. @@ -206,13 +165,6 @@ impl MmWithUser { unsafe { &*ptr.cast() } } - /// Use `mmput_async` when dropping this refcount. - #[inline] - pub fn into_mmput_async(me: ARef) -> ARef { - // SAFETY: The layouts and invariants are compatible. - unsafe { ARef::from_raw(ARef::into_raw(me).cast()) } - } - /// Attempt to access a vma using the vma read lock. /// /// This is an optimistic trylock operation, so it may fail if there is contention. In that diff --git a/rust/kernel/mm/mmput_async.rs b/rust/kernel/mm/mmput_async.rs new file mode 100644 index 000000000000..9289e05f7a67 --- /dev/null +++ b/rust/kernel/mm/mmput_async.rs @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Version of `MmWithUser` using `mmput_async`. +//! +//! This is a separate file from `mm.rs` due to the dependency on `CONFIG_MMU=y`. +#![cfg(CONFIG_MMU)] + +use crate::{ + bindings, + mm::MmWithUser, + types::{ARef, AlwaysRefCounted}, +}; +use core::{ops::Deref, ptr::NonNull}; + +/// A wrapper for the kernel's `struct mm_struct`. +/// +/// This type is identical to `MmWithUser` except that it uses `mmput_async` when dropping a +/// refcount. This means that the destructor of `ARef` is safe to call in atomic +/// context. +/// +/// # Invariants +/// +/// Values of this type are always refcounted using `mmget`. The value of `mm_users` is non-zero. +#[repr(transparent)] +pub struct MmWithUserAsync { + mm: MmWithUser, +} + +// SAFETY: It is safe to call `mmput_async` on another thread than where `mmget` was called. +unsafe impl Send for MmWithUserAsync {} +// SAFETY: All methods on `MmWithUserAsync` can be called in parallel from several threads. +unsafe impl Sync for MmWithUserAsync {} + +// SAFETY: By the type invariants, this type is always refcounted. +unsafe impl AlwaysRefCounted for MmWithUserAsync { + #[inline] + fn inc_ref(&self) { + // SAFETY: The pointer is valid since self is a reference. + unsafe { bindings::mmget(self.as_raw()) }; + } + + #[inline] + unsafe fn dec_ref(obj: NonNull) { + // SAFETY: The caller is giving up their refcount. + unsafe { bindings::mmput_async(obj.cast().as_ptr()) }; + } +} + +// Make all `MmWithUser` methods available on `MmWithUserAsync`. +impl Deref for MmWithUserAsync { + type Target = MmWithUser; + + #[inline] + fn deref(&self) -> &MmWithUser { + &self.mm + } +} + +impl MmWithUser { + /// Use `mmput_async` when dropping this refcount. + #[inline] + pub fn into_mmput_async(me: ARef) -> ARef { + // SAFETY: The layouts and invariants are compatible. + unsafe { ARef::from_raw(ARef::into_raw(me).cast()) } + } +} -- cgit v1.2.3