From 7dd34dfc8dfa92a7244242098110388367996ac3 Mon Sep 17 00:00:00 2001 From: Alexandre Courbot Date: Tue, 24 Feb 2026 19:37:56 +0900 Subject: rust: kunit: fix warning when !CONFIG_PRINTK If `CONFIG_PRINTK` is not set, then the following warnings are issued during build: warning: unused variable: `args` --> ../rust/kernel/kunit.rs:16:12 | 16 | pub fn err(args: fmt::Arguments<'_>) { | ^^^^ help: if this is intentional, prefix it with an underscore: `_args` | = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default warning: unused variable: `args` --> ../rust/kernel/kunit.rs:32:13 | 32 | pub fn info(args: fmt::Arguments<'_>) { | ^^^^ help: if this is intentional, prefix it with an underscore: `_args` Fix this by adding a no-op assignment using `args` when `CONFIG_PRINTK` is not set. Fixes: a66d733da801 ("rust: support running Rust documentation tests as KUnit ones") Signed-off-by: Alexandre Courbot Reviewed-by: Alice Ryhl Reviewed-by: David Gow Signed-off-by: Shuah Khan --- rust/kernel/kunit.rs | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'rust') diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index f93f24a60bdd..a1edf7491579 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -14,6 +14,10 @@ use crate::prelude::*; /// Public but hidden since it should only be used from KUnit generated code. #[doc(hidden)] pub fn err(args: fmt::Arguments<'_>) { + // `args` is unused if `CONFIG_PRINTK` is not set - this avoids a build-time warning. + #[cfg(not(CONFIG_PRINTK))] + let _ = args; + // SAFETY: The format string is null-terminated and the `%pA` specifier matches the argument we // are passing. #[cfg(CONFIG_PRINTK)] @@ -30,6 +34,10 @@ pub fn err(args: fmt::Arguments<'_>) { /// Public but hidden since it should only be used from KUnit generated code. #[doc(hidden)] pub fn info(args: fmt::Arguments<'_>) { + // `args` is unused if `CONFIG_PRINTK` is not set - this avoids a build-time warning. + #[cfg(not(CONFIG_PRINTK))] + let _ = args; + // SAFETY: The format string is null-terminated and the `%pA` specifier matches the argument we // are passing. #[cfg(CONFIG_PRINTK)] -- cgit v1.2.3 From 3ac88a9948792b092a4b11323e2abd1ecbe0cc68 Mon Sep 17 00:00:00 2001 From: Alexandre Courbot Date: Tue, 24 Feb 2026 11:25:34 +0900 Subject: rust: str: make NullTerminatedFormatter public If `CONFIG_BLOCK` is disabled, the following warnings are displayed during build: warning: struct `NullTerminatedFormatter` is never constructed --> ../rust/kernel/str.rs:667:19 | 667 | pub(crate) struct NullTerminatedFormatter<'a> { | ^^^^^^^^^^^^^^^^^^^^^^^ | = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default warning: associated function `new` is never used --> ../rust/kernel/str.rs:673:19 | 671 | impl<'a> NullTerminatedFormatter<'a> { | ------------------------------------ associated function in this implementation 672 | /// Create a new [`Self`] instance. 673 | pub(crate) fn new(buffer: &'a mut [u8]) -> Option> { Fix them by making `NullTerminatedFormatter` public, as it could be useful for drivers anyway. Fixes: cdde7a1951ff ("rust: str: introduce `NullTerminatedFormatter`") Signed-off-by: Alexandre Courbot Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260224-nullterminatedformatter-v1-1-5bef7b9b3d4c@nvidia.com Signed-off-by: Miguel Ojeda --- rust/kernel/str.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'rust') diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index fa87779d2253..3f8918764640 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -664,13 +664,13 @@ impl fmt::Write for Formatter<'_> { /// /// * The first byte of `buffer` is always zero. /// * The length of `buffer` is at least 1. -pub(crate) struct NullTerminatedFormatter<'a> { +pub struct NullTerminatedFormatter<'a> { buffer: &'a mut [u8], } impl<'a> NullTerminatedFormatter<'a> { /// Create a new [`Self`] instance. - pub(crate) fn new(buffer: &'a mut [u8]) -> Option> { + pub fn new(buffer: &'a mut [u8]) -> Option> { *(buffer.first_mut()?) = 0; // INVARIANT: -- cgit v1.2.3 From e174dd14bf0beac811a5201e370ab26ce8c67f23 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Tue, 24 Feb 2026 15:29:56 +0800 Subject: rust: kbuild: emit dep-info into $(depfile) directly MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After commit 295d8398c67e ("kbuild: specify output names separately for each emission type from rustc"), the preferred pattern is to ask rustc to emit dependency information into $(depfile) directly, and after commit 2185242faddd ("kbuild: remove sed commands after rustc rules"), the post-processing to remove comments is no longer necessary as fixdep can handle comments directly. Thus, emit dep-info into $(depfile) directly and remove the mv and sed invocation. This fixes the issue where a non-ignored .d file is emitted during compilation and removed shortly afterwards. [ Like Gary mentioned in Zulip, this likely happened due to rebasing the builds part of the old `syn` work I had. - Miguel ] Reported-by: Onur Özkan Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/syn.20artifact.20being.20tracked.20by.20git/with/575467879 Fixes: 7dbe46c0b11d ("rust: kbuild: add proc macro library support") Signed-off-by: Gary Guo Tested-by: Onur Özkan Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260224072957.214979-1-gary@garyguo.net [ Reworded for a couple of typos. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/Makefile | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'rust') diff --git a/rust/Makefile b/rust/Makefile index 629b3bdd2b20..1500993d7ecc 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -526,11 +526,9 @@ quiet_cmd_rustc_procmacrolibrary = $(RUSTC_OR_CLIPPY_QUIET) PL $@ cmd_rustc_procmacrolibrary = \ $(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \ $(filter-out $(skip_flags),$(rust_common_flags) $(rustc_target_flags)) \ - --emit=dep-info,link --crate-type rlib -O \ + --emit=dep-info=$(depfile) --emit=link=$@ --crate-type rlib -O \ --out-dir $(objtree)/$(obj) -L$(objtree)/$(obj) \ - --crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $<; \ - mv $(objtree)/$(obj)/$(patsubst lib%.rlib,%,$(notdir $@)).d $(depfile); \ - sed -i '/^\#/d' $(depfile) + --crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $< $(obj)/libproc_macro2.rlib: private skip_clippy = 1 $(obj)/libproc_macro2.rlib: private rustc_target_flags = $(proc_macro2-flags) -- cgit v1.2.3 From dda135077ecc9f15c407f094dcfe7800376be867 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Thu, 26 Feb 2026 15:21:11 +0000 Subject: rust: build: remap path to avoid absolute path When building with an out directory (O=), absolute paths can end up in the file name in `#[track_caller]` or the panic message. This is not desirable as this leaks the exact path being used to build the kernel and means that the same location can appear in two forms (relative or absolute). This is reported by Asahi [1] and is being workaround in [2] previously to force everything to be absolute path. Using absolute path for everything solves the inconsistency, however it does not address the reproducibility issue. So, fix this by remap all absolute paths to srctree to relative path instead. This is previously attempted in commit dbdffaf50ff9 ("kbuild, rust: use -fremap-path-prefix to make paths relative") but that was reverted as remapping debug info causes some tool (e.g. objdump) to be unable to find sources. Therefore, use `--remap-path-scope` to only remap macros but leave debuginfo untouched. `--remap-path-scope` is only stable in Rust 1.95, so use `rustc-option` to detect its presence. This feature has been available as `-Zremap-path-scope` for all versions that we support; however due to bugs in the Rust compiler, it does not work reliably until 1.94. I opted to not enable it for 1.94 as it's just a single version that we missed. This change can be validated by building a kernel with O=, strip debug info on vmlinux, and then check if the absolute path exists in `strings vmlinux`, e.g. `strings vmlinux |grep \/home`. Reported-by: Janne Grunau Reported-by: Asahi Lina Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Per-call-site.20data.20and.20lock.20class.20keys/near/572466559 [1] Link: https://github.com/AsahiLinux/linux/commit/54ab88878869036c9d6620101bfe17a81e88c2f9 [2] Signed-off-by: Gary Guo Acked-by: Nicolas Schier # kbuild Link: https://patch.msgid.link/20260226152112.3222886-1-gary@kernel.org [ Reworded for few typos. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/Makefile | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'rust') diff --git a/rust/Makefile b/rust/Makefile index 1500993d7ecc..9801af2e1e02 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -148,7 +148,8 @@ doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rust quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $< cmd_rustdoc = \ OBJTREE=$(abspath $(objtree)) \ - $(RUSTDOC) $(filter-out $(skip_flags) --remap-path-prefix=%,$(if $(rustdoc_host),$(rust_common_flags),$(rust_flags))) \ + $(RUSTDOC) $(filter-out $(skip_flags) --remap-path-prefix=% --remap-path-scope=%, \ + $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags))) \ $(rustc_target_flags) -L$(objtree)/$(obj) \ -Zunstable-options --generate-link-to-definition \ --output $(rustdoc_output) \ @@ -334,7 +335,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $< rm -rf $(objtree)/$(obj)/test/doctests/kernel; \ mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \ OBJTREE=$(abspath $(objtree)) \ - $(RUSTDOC) --test $(filter-out --remap-path-prefix=%,$(rust_flags)) \ + $(RUSTDOC) --test $(filter-out --remap-path-prefix=% --remap-path-scope=%,$(rust_flags)) \ -L$(objtree)/$(obj) --extern ffi --extern pin_init \ --extern kernel --extern build_error --extern macros \ --extern bindings --extern uapi \ -- cgit v1.2.3 From a075082a15e7f5c4889d0cbb51a4041c332cb00c Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Mon, 2 Mar 2026 15:04:14 +0100 Subject: rust: pin-init: internal: init: remove `#[disable_initialized_field_access]` Gary noticed [1] that the initializer macros as well as the `[Pin]Init` traits cannot support unaligned fields, since they use operations that require aligned pointers. This means that any code using structs with unaligned fields in pin-init is unsound. By default, the `init!` macro generates references to initialized fields, which makes the compiler check that those fields are aligned. However, we added the `#[disable_initialized_field_access]` attribute to avoid this behavior in commit ceca298c53f9 ("rust: pin-init: internal: init: add escape hatch for referencing initialized fields"). Thus remove the `#[disable_initialized_field_access]` attribute from `init!`, which is the only safe way to create an initializer handling unaligned fields. If support for in-place initializing structs with unaligned fields is required in the future, we could figure out a solution. This is tracked in [2]. Reported-by: Gary Guo Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/561532-pin-init/topic/initialized.20field.20accessor.20detection/with/576210658 [1] Link: https://github.com/Rust-for-Linux/pin-init/issues/112 [2] Fixes: ceca298c53f9 ("rust: pin-init: internal: init: add escape hatch for referencing initialized fields") Signed-off-by: Benno Lossin Acked-by: Janne Grunau Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Link: https://patch.msgid.link/20260302140424.4097655-1-lossin@kernel.org [ Adjusted tags and reworded as discussed. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/pin-init/internal/src/init.rs | 39 ++++++++------------------------------ 1 file changed, 8 insertions(+), 31 deletions(-) (limited to 'rust') diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs index 42936f915a07..da53adc44ecf 100644 --- a/rust/pin-init/internal/src/init.rs +++ b/rust/pin-init/internal/src/init.rs @@ -62,7 +62,6 @@ impl InitializerKind { enum InitializerAttribute { DefaultError(DefaultErrorAttribute), - DisableInitializedFieldAccess, } struct DefaultErrorAttribute { @@ -86,6 +85,7 @@ pub(crate) fn expand( let error = error.map_or_else( || { if let Some(default_error) = attrs.iter().fold(None, |acc, attr| { + #[expect(irrefutable_let_patterns)] if let InitializerAttribute::DefaultError(DefaultErrorAttribute { ty }) = attr { Some(ty.clone()) } else { @@ -145,15 +145,7 @@ pub(crate) fn expand( }; // `mixed_site` ensures that the data is not accessible to the user-controlled code. let data = Ident::new("__data", Span::mixed_site()); - let init_fields = init_fields( - &fields, - pinned, - !attrs - .iter() - .any(|attr| matches!(attr, InitializerAttribute::DisableInitializedFieldAccess)), - &data, - &slot, - ); + let init_fields = init_fields(&fields, pinned, &data, &slot); let field_check = make_field_check(&fields, init_kind, &path); Ok(quote! {{ // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return @@ -236,7 +228,6 @@ fn get_init_kind(rest: Option<(Token![..], Expr)>, dcx: &mut DiagCtxt) -> InitKi fn init_fields( fields: &Punctuated, pinned: bool, - generate_initialized_accessors: bool, data: &Ident, slot: &Ident, ) -> TokenStream { @@ -272,13 +263,6 @@ fn init_fields( unsafe { &mut (*#slot).#ident } } }; - let accessor = generate_initialized_accessors.then(|| { - quote! { - #(#cfgs)* - #[allow(unused_variables)] - let #ident = #accessor; - } - }); quote! { #(#attrs)* { @@ -286,7 +270,9 @@ fn init_fields( // SAFETY: TODO unsafe { #write(::core::ptr::addr_of_mut!((*#slot).#ident), #value_ident) }; } - #accessor + #(#cfgs)* + #[allow(unused_variables)] + let #ident = #accessor; } } InitializerKind::Init { ident, value, .. } => { @@ -326,20 +312,15 @@ fn init_fields( }, ) }; - let accessor = generate_initialized_accessors.then(|| { - quote! { - #(#cfgs)* - #[allow(unused_variables)] - let #ident = #accessor; - } - }); quote! { #(#attrs)* { let #init = #value; #value_init } - #accessor + #(#cfgs)* + #[allow(unused_variables)] + let #ident = #accessor; } } InitializerKind::Code { block: value, .. } => quote! { @@ -466,10 +447,6 @@ impl Parse for Initializer { if a.path().is_ident("default_error") { a.parse_args::() .map(InitializerAttribute::DefaultError) - } else if a.path().is_ident("disable_initialized_field_access") { - a.meta - .require_path_only() - .map(|_| InitializerAttribute::DisableInitializedFieldAccess) } else { Err(syn::Error::new_spanned(a, "unknown initializer attribute")) } -- cgit v1.2.3 From 580cc37b1de4fcd9997c48d7080e744533f09f36 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Mon, 2 Mar 2026 15:04:15 +0100 Subject: rust: pin-init: internal: init: document load-bearing fact of field accessors The functions `[Pin]Init::__[pinned_]init` and `ptr::write` called from the `init!` macro require the passed pointer to be aligned. This fact is ensured by the creation of field accessors to previously initialized fields. Since we missed this very important fact from the beginning [1], document it in the code. Link: https://rust-for-linux.zulipchat.com/#narrow/channel/561532-pin-init/topic/initialized.20field.20accessor.20detection/with/576210658 [1] Fixes: 90e53c5e70a6 ("rust: add pin-init API core") Cc: # 6.6.y, 6.12.y: 42415d163e5d: rust: pin-init: add references to previously initialized fields Cc: # 6.6.y, 6.12.y, 6.18.y, 6.19.y Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260302140424.4097655-2-lossin@kernel.org [ Updated Cc: stable@ tags as discussed. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/pin-init/internal/src/init.rs | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'rust') diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs index da53adc44ecf..738f62c8105c 100644 --- a/rust/pin-init/internal/src/init.rs +++ b/rust/pin-init/internal/src/init.rs @@ -251,6 +251,10 @@ fn init_fields( }); // Again span for better diagnostics let write = quote_spanned!(ident.span()=> ::core::ptr::write); + // NOTE: the field accessor ensures that the initialized field is properly aligned. + // Unaligned fields will cause the compiler to emit E0793. We do not support + // unaligned fields since `Init::__init` requires an aligned pointer; the call to + // `ptr::write` below has the same requirement. let accessor = if pinned { let project_ident = format_ident!("__project_{ident}"); quote! { @@ -278,6 +282,10 @@ fn init_fields( InitializerKind::Init { ident, value, .. } => { // Again span for better diagnostics let init = format_ident!("init", span = value.span()); + // NOTE: the field accessor ensures that the initialized field is properly aligned. + // Unaligned fields will cause the compiler to emit E0793. We do not support + // unaligned fields since `Init::__init` requires an aligned pointer; the call to + // `ptr::write` below has the same requirement. let (value_init, accessor) = if pinned { let project_ident = format_ident!("__project_{ident}"); ( -- cgit v1.2.3 From 08da98f18f4f99aa16838397b76086d2d1d364b3 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Mon, 2 Mar 2026 16:42:34 +0000 Subject: rust: ptr: add `KnownSize` trait to support DST size info extraction Add a `KnownSize` trait which is used obtain a size from a raw pointer's metadata. This makes it possible to obtain size information on a raw slice pointer. This is similar to Rust `core::mem::size_of_val_raw` which is not yet stable. Signed-off-by: Gary Guo Reviewed-by: Benno Lossin Acked-by: Miguel Ojeda Link: https://patch.msgid.link/20260302164239.284084-2-gary@kernel.org [ Fix wording in doc-comment. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/lib.rs | 1 + rust/kernel/ptr.rs | 27 ++++++++++++++++++++++++++- 2 files changed, 27 insertions(+), 1 deletion(-) (limited to 'rust') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 3da92f18f4ee..510cc7fe4961 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -20,6 +20,7 @@ #![feature(generic_nonzero)] #![feature(inline_const)] #![feature(pointer_is_aligned)] +#![feature(slice_ptr_len)] // // Stable since Rust 1.80.0. #![feature(slice_flatten)] diff --git a/rust/kernel/ptr.rs b/rust/kernel/ptr.rs index 5b6a382637fe..e91de5f0d78f 100644 --- a/rust/kernel/ptr.rs +++ b/rust/kernel/ptr.rs @@ -2,7 +2,10 @@ //! Types and functions to work with pointers and addresses. -use core::mem::align_of; +use core::mem::{ + align_of, + size_of, // +}; use core::num::NonZero; /// Type representing an alignment, which is always a power of two. @@ -225,3 +228,25 @@ macro_rules! impl_alignable_uint { } impl_alignable_uint!(u8, u16, u32, u64, usize); + +/// Trait to represent compile-time known size information. +/// +/// This is a generalization of [`size_of`] that works for dynamically sized types. +pub trait KnownSize { + /// Get the size of an object of this type in bytes, with the metadata of the given pointer. + fn size(p: *const Self) -> usize; +} + +impl KnownSize for T { + #[inline(always)] + fn size(_: *const Self) -> usize { + size_of::() + } +} + +impl KnownSize for [T] { + #[inline(always)] + fn size(p: *const Self) -> usize { + p.len() * size_of::() + } +} -- cgit v1.2.3 From f41941aab3acd33f13d65a2ae496329bc8ae4de0 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Mon, 2 Mar 2026 16:42:35 +0000 Subject: rust: ptr: add projection infrastructure Add a generic infrastructure for performing field and index projections on raw pointers. This will form the basis of performing I/O projections. Pointers manipulations are intentionally using the safe wrapping variants instead of the unsafe variants, as the latter requires pointers to be inside an allocation which is not necessarily true for I/O pointers. This projection macro protects against rogue `Deref` implementation, which can causes the projected pointer to be outside the bounds of starting pointer. This is extremely unlikely and Rust has a lint to catch this, but is unsoundness regardless. The protection works by inducing type inference ambiguity when `Deref` is implemented. This projection macro also stops projecting into unaligned fields (i.e. fields of `#[repr(packed)]` structs), as misaligned pointers require special handling. This is implemented by attempting to create reference to projected field inside a `if false` block. Despite being unreachable, Rust still checks that they're not unaligned fields. The projection macro supports both fallible and infallible index projections. These are described in detail inside the documentation. Signed-off-by: Gary Guo Reviewed-by: Benno Lossin Acked-by: Miguel Ojeda Link: https://patch.msgid.link/20260302164239.284084-3-gary@kernel.org [ * Add intro-doc links where possible, * Fix typos and slightly improve wording, e.g. "as documentation describes" -> "as the documentation of [`Self::proj`] describes", * Add an empty line between regular and safety comments, before examples, and between logically independent comments, * Capitalize various safety comments. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/lib.rs | 3 + rust/kernel/ptr.rs | 3 + rust/kernel/ptr/projection.rs | 305 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 311 insertions(+) create mode 100644 rust/kernel/ptr/projection.rs (limited to 'rust') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 510cc7fe4961..d93292d47420 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -38,6 +38,9 @@ #![feature(const_ptr_write)] #![feature(const_refs_to_cell)] // +// Stable since Rust 1.84.0. +#![feature(strict_provenance)] +// // Expected to become stable. #![feature(arbitrary_self_types)] // diff --git a/rust/kernel/ptr.rs b/rust/kernel/ptr.rs index e91de5f0d78f..bdc2d79ff669 100644 --- a/rust/kernel/ptr.rs +++ b/rust/kernel/ptr.rs @@ -2,6 +2,9 @@ //! Types and functions to work with pointers and addresses. +pub mod projection; +pub use crate::project_pointer as project; + use core::mem::{ align_of, size_of, // diff --git a/rust/kernel/ptr/projection.rs b/rust/kernel/ptr/projection.rs new file mode 100644 index 000000000000..140ea8e21617 --- /dev/null +++ b/rust/kernel/ptr/projection.rs @@ -0,0 +1,305 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Infrastructure for handling projections. + +use core::{ + mem::MaybeUninit, + ops::Deref, // +}; + +use crate::prelude::*; + +/// Error raised when a projection is attempted on an array or slice out of bounds. +pub struct OutOfBound; + +impl From for Error { + #[inline(always)] + fn from(_: OutOfBound) -> Self { + ERANGE + } +} + +/// A helper trait to perform index projection. +/// +/// This is similar to [`core::slice::SliceIndex`], but operates on raw pointers safely and +/// fallibly. +/// +/// # Safety +/// +/// The implementation of `index` and `get` (if [`Some`] is returned) must ensure that, if provided +/// input pointer `slice` and returned pointer `output`, then: +/// - `output` has the same provenance as `slice`; +/// - `output.byte_offset_from(slice)` is between 0 to +/// `KnownSize::size(slice) - KnownSize::size(output)`. +/// +/// This means that if the input pointer is valid, then pointer returned by `get` or `index` is +/// also valid. +#[diagnostic::on_unimplemented(message = "`{Self}` cannot be used to index `{T}`")] +#[doc(hidden)] +pub unsafe trait ProjectIndex: Sized { + type Output: ?Sized; + + /// Returns an index-projected pointer, if in bounds. + fn get(self, slice: *mut T) -> Option<*mut Self::Output>; + + /// Returns an index-projected pointer; fail the build if it cannot be proved to be in bounds. + #[inline(always)] + fn index(self, slice: *mut T) -> *mut Self::Output { + Self::get(self, slice).unwrap_or_else(|| build_error!()) + } +} + +// Forward array impl to slice impl. +// +// SAFETY: Safety requirement guaranteed by the forwarded impl. +unsafe impl ProjectIndex<[T; N]> for I +where + I: ProjectIndex<[T]>, +{ + type Output = >::Output; + + #[inline(always)] + fn get(self, slice: *mut [T; N]) -> Option<*mut Self::Output> { + >::get(self, slice) + } + + #[inline(always)] + fn index(self, slice: *mut [T; N]) -> *mut Self::Output { + >::index(self, slice) + } +} + +// SAFETY: `get`-returned pointer has the same provenance as `slice` and the offset is checked to +// not exceed the required bound. +unsafe impl ProjectIndex<[T]> for usize { + type Output = T; + + #[inline(always)] + fn get(self, slice: *mut [T]) -> Option<*mut T> { + if self >= slice.len() { + None + } else { + Some(slice.cast::().wrapping_add(self)) + } + } +} + +// SAFETY: `get`-returned pointer has the same provenance as `slice` and the offset is checked to +// not exceed the required bound. +unsafe impl ProjectIndex<[T]> for core::ops::Range { + type Output = [T]; + + #[inline(always)] + fn get(self, slice: *mut [T]) -> Option<*mut [T]> { + let new_len = self.end.checked_sub(self.start)?; + if self.end > slice.len() { + return None; + } + Some(core::ptr::slice_from_raw_parts_mut( + slice.cast::().wrapping_add(self.start), + new_len, + )) + } +} + +// SAFETY: Safety requirement guaranteed by the forwarded impl. +unsafe impl ProjectIndex<[T]> for core::ops::RangeTo { + type Output = [T]; + + #[inline(always)] + fn get(self, slice: *mut [T]) -> Option<*mut [T]> { + (0..self.end).get(slice) + } +} + +// SAFETY: Safety requirement guaranteed by the forwarded impl. +unsafe impl ProjectIndex<[T]> for core::ops::RangeFrom { + type Output = [T]; + + #[inline(always)] + fn get(self, slice: *mut [T]) -> Option<*mut [T]> { + (self.start..slice.len()).get(slice) + } +} + +// SAFETY: `get` returned the pointer as is, so it always has the same provenance and offset of 0. +unsafe impl ProjectIndex<[T]> for core::ops::RangeFull { + type Output = [T]; + + #[inline(always)] + fn get(self, slice: *mut [T]) -> Option<*mut [T]> { + Some(slice) + } +} + +/// A helper trait to perform field projection. +/// +/// This trait has a `DEREF` generic parameter so it can be implemented twice for types that +/// implement [`Deref`]. This will cause an ambiguity error and thus block [`Deref`] types being +/// used as base of projection, as they can inject unsoundness. Users therefore must not specify +/// `DEREF` and should always leave it to be inferred. +/// +/// # Safety +/// +/// `proj` may only invoke `f` with a valid allocation, as the documentation of [`Self::proj`] +/// describes. +#[doc(hidden)] +pub unsafe trait ProjectField { + /// Project a pointer to a type to a pointer of a field. + /// + /// `f` may only be invoked with a valid allocation so it can safely obtain raw pointers to + /// fields using `&raw mut`. + /// + /// This is needed because `base` might not point to a valid allocation, while `&raw mut` + /// requires pointers to be in bounds of a valid allocation. + /// + /// # Safety + /// + /// `f` must return a pointer in bounds of the provided pointer. + unsafe fn proj(base: *mut Self, f: impl FnOnce(*mut Self) -> *mut F) -> *mut F; +} + +// NOTE: in theory, this API should work for `T: ?Sized` and `F: ?Sized`, too. However, we cannot +// currently support that as we need to obtain a valid allocation that `&raw const` can operate on. +// +// SAFETY: `proj` invokes `f` with valid allocation. +unsafe impl ProjectField for T { + #[inline(always)] + unsafe fn proj(base: *mut Self, f: impl FnOnce(*mut Self) -> *mut F) -> *mut F { + // Create a valid allocation to start projection, as `base` is not necessarily so. The + // memory is never actually used so it will be optimized out, so it should work even for + // very large `T` (`memoffset` crate also relies on this). To be extra certain, we also + // annotate `f` closure with `#[inline(always)]` in the macro. + let mut place = MaybeUninit::uninit(); + let place_base = place.as_mut_ptr(); + let field = f(place_base); + // SAFETY: `field` is in bounds from `base` per safety requirement. + let offset = unsafe { field.byte_offset_from(place_base) }; + // Use `wrapping_byte_offset` as `base` does not need to be of valid allocation. + base.wrapping_byte_offset(offset).cast() + } +} + +// SAFETY: Vacuously satisfied. +unsafe impl ProjectField for T { + #[inline(always)] + unsafe fn proj(_: *mut Self, _: impl FnOnce(*mut Self) -> *mut F) -> *mut F { + build_error!("this function is a guard against `Deref` impl and is never invoked"); + } +} + +/// Create a projection from a raw pointer. +/// +/// The projected pointer is within the memory region marked by the input pointer. There is no +/// requirement that the input raw pointer needs to be valid, so this macro may be used for +/// projecting pointers outside normal address space, e.g. I/O pointers. However, if the input +/// pointer is valid, the projected pointer is also valid. +/// +/// Supported projections include field projections and index projections. +/// It is not allowed to project into types that implement custom [`Deref`] or +/// [`Index`](core::ops::Index). +/// +/// The macro has basic syntax of `kernel::ptr::project!(ptr, projection)`, where `ptr` is an +/// expression that evaluates to a raw pointer which serves as the base of projection. `projection` +/// can be a projection expression of form `.field` (normally identifier, or numeral in case of +/// tuple structs) or of form `[index]`. +/// +/// If a mutable pointer is needed, the macro input can be prefixed with the `mut` keyword, i.e. +/// `kernel::ptr::project!(mut ptr, projection)`. By default, a const pointer is created. +/// +/// `ptr::project!` macro can perform both fallible indexing and build-time checked indexing. +/// `[index]` form performs build-time bounds checking; if compiler fails to prove `[index]` is in +/// bounds, compilation will fail. `[index]?` can be used to perform runtime bounds checking; +/// `OutOfBound` error is raised via `?` if the index is out of bounds. +/// +/// # Examples +/// +/// Field projections are performed with `.field_name`: +/// +/// ``` +/// struct MyStruct { field: u32, } +/// let ptr: *const MyStruct = core::ptr::dangling(); +/// let field_ptr: *const u32 = kernel::ptr::project!(ptr, .field); +/// +/// struct MyTupleStruct(u32, u32); +/// +/// fn proj(ptr: *const MyTupleStruct) { +/// let field_ptr: *const u32 = kernel::ptr::project!(ptr, .1); +/// } +/// ``` +/// +/// Index projections are performed with `[index]`: +/// +/// ``` +/// fn proj(ptr: *const [u8; 32]) -> Result { +/// let field_ptr: *const u8 = kernel::ptr::project!(ptr, [1]); +/// // The following invocation, if uncommented, would fail the build. +/// // +/// // kernel::ptr::project!(ptr, [128]); +/// +/// // This will raise an `OutOfBound` error (which is convertible to `ERANGE`). +/// kernel::ptr::project!(ptr, [128]?); +/// Ok(()) +/// } +/// ``` +/// +/// If you need to match on the error instead of propagate, put the invocation inside a closure: +/// +/// ``` +/// let ptr: *const [u8; 32] = core::ptr::dangling(); +/// let field_ptr: Result<*const u8> = (|| -> Result<_> { +/// Ok(kernel::ptr::project!(ptr, [128]?)) +/// })(); +/// assert!(field_ptr.is_err()); +/// ``` +/// +/// For mutable pointers, put `mut` as the first token in macro invocation. +/// +/// ``` +/// let ptr: *mut [(u8, u16); 32] = core::ptr::dangling_mut(); +/// let field_ptr: *mut u16 = kernel::ptr::project!(mut ptr, [1].1); +/// ``` +#[macro_export] +macro_rules! project_pointer { + (@gen $ptr:ident, ) => {}; + // Field projection. `$field` needs to be `tt` to support tuple index like `.0`. + (@gen $ptr:ident, .$field:tt $($rest:tt)*) => { + // SAFETY: The provided closure always returns an in-bounds pointer. + let $ptr = unsafe { + $crate::ptr::projection::ProjectField::proj($ptr, #[inline(always)] |ptr| { + // Check unaligned field. Not all users (e.g. DMA) can handle unaligned + // projections. + if false { + let _ = &(*ptr).$field; + } + // SAFETY: `$field` is in bounds, and no implicit `Deref` is possible (if the + // type implements `Deref`, Rust cannot infer the generic parameter `DEREF`). + &raw mut (*ptr).$field + }) + }; + $crate::ptr::project!(@gen $ptr, $($rest)*) + }; + // Fallible index projection. + (@gen $ptr:ident, [$index:expr]? $($rest:tt)*) => { + let $ptr = $crate::ptr::projection::ProjectIndex::get($index, $ptr) + .ok_or($crate::ptr::projection::OutOfBound)?; + $crate::ptr::project!(@gen $ptr, $($rest)*) + }; + // Build-time checked index projection. + (@gen $ptr:ident, [$index:expr] $($rest:tt)*) => { + let $ptr = $crate::ptr::projection::ProjectIndex::index($index, $ptr); + $crate::ptr::project!(@gen $ptr, $($rest)*) + }; + (mut $ptr:expr, $($proj:tt)*) => {{ + let ptr: *mut _ = $ptr; + $crate::ptr::project!(@gen ptr, $($proj)*); + ptr + }}; + ($ptr:expr, $($proj:tt)*) => {{ + let ptr = <*const _>::cast_mut($ptr); + // We currently always project using mutable pointer, as it is not decided whether `&raw + // const` allows the resulting pointer to be mutated (see documentation of `addr_of!`). + $crate::ptr::project!(@gen ptr, $($proj)*); + ptr.cast_const() + }}; +} -- cgit v1.2.3 From 4da879a0d3fd170a70994b73baa554c6913918b5 Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Mon, 2 Mar 2026 16:42:36 +0000 Subject: rust: dma: use pointer projection infra for `dma_{read,write}` macro Current `dma_read!`, `dma_write!` macros also use a custom `addr_of!()`-based implementation for projecting pointers, which has soundness issue as it relies on absence of `Deref` implementation on types. It also has a soundness issue where it does not protect against unaligned fields (when `#[repr(packed)]` is used) so it can generate misaligned accesses. This commit migrates them to use the general pointer projection infrastructure, which handles these cases correctly. As part of migration, the macro is updated to have an improved surface syntax. The current macro have dma_read!(a.b.c[d].e.f) to mean `a.b.c` is a DMA coherent allocation and it should project into it with `[d].e.f` and do a read, which is confusing as it makes the indexing operator integral to the macro (so it will break if you have an array of `CoherentAllocation`, for example). This also is problematic as we would like to generalize `CoherentAllocation` from just slices to arbitrary types. Make the macro expects `dma_read!(path.to.dma, .path.inside.dma)` as the canonical syntax. The index operator is no longer special and is just one type of projection (in additional to field projection). Similarly, make `dma_write!(path.to.dma, .path.inside.dma, value)` become the canonical syntax for writing. Another issue of the current macro is that it is always fallible. This makes sense with existing design of `CoherentAllocation`, but once we support fixed size arrays with `CoherentAllocation`, it is desirable to have the ability to perform infallible indexing as well, e.g. doing a `[0]` index of `[Foo; 2]` is okay and can be checked at build-time, so forcing falliblity is non-ideal. To capture this, the macro is changed to use `[idx]` as infallible projection and `[idx]?` as fallible index projection (those syntax are part of the general projection infra). A benefit of this is that while individual indexing operation may fail, the overall read/write operation is not fallible. Fixes: ad2907b4e308 ("rust: add dma coherent allocator abstraction") Reviewed-by: Benno Lossin Signed-off-by: Gary Guo Link: https://patch.msgid.link/20260302164239.284084-4-gary@kernel.org [ Capitalize safety comments; slightly improve wording in doc-comments. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/dma.rs | 114 +++++++++++++++++++++++------------------------------ 1 file changed, 50 insertions(+), 64 deletions(-) (limited to 'rust') diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs index 909d56fd5118..a396f8435739 100644 --- a/rust/kernel/dma.rs +++ b/rust/kernel/dma.rs @@ -461,6 +461,19 @@ impl CoherentAllocation { self.count * core::mem::size_of::() } + /// Returns the raw pointer to the allocated region in the CPU's virtual address space. + #[inline] + pub fn as_ptr(&self) -> *const [T] { + core::ptr::slice_from_raw_parts(self.cpu_addr.as_ptr(), self.count) + } + + /// Returns the raw pointer to the allocated region in the CPU's virtual address space as + /// a mutable pointer. + #[inline] + pub fn as_mut_ptr(&self) -> *mut [T] { + core::ptr::slice_from_raw_parts_mut(self.cpu_addr.as_ptr(), self.count) + } + /// Returns the base address to the allocated region in the CPU's virtual address space. pub fn start_ptr(&self) -> *const T { self.cpu_addr.as_ptr() @@ -581,23 +594,6 @@ impl CoherentAllocation { Ok(()) } - /// Returns a pointer to an element from the region with bounds checking. `offset` is in - /// units of `T`, not the number of bytes. - /// - /// Public but hidden since it should only be used from [`dma_read`] and [`dma_write`] macros. - #[doc(hidden)] - pub fn item_from_index(&self, offset: usize) -> Result<*mut T> { - if offset >= self.count { - return Err(EINVAL); - } - // SAFETY: - // - The pointer is valid due to type invariant on `CoherentAllocation` - // and we've just checked that the range and index is within bounds. - // - `offset` can't overflow since it is smaller than `self.count` and we've checked - // that `self.count` won't overflow early in the constructor. - Ok(unsafe { self.cpu_addr.as_ptr().add(offset) }) - } - /// Reads the value of `field` and ensures that its type is [`FromBytes`]. /// /// # Safety @@ -670,6 +666,9 @@ unsafe impl Send for CoherentAllocation {} /// Reads a field of an item from an allocated region of structs. /// +/// The syntax is of the form `kernel::dma_read!(dma, proj)` where `dma` is an expression evaluating +/// to a [`CoherentAllocation`] and `proj` is a [projection specification](kernel::ptr::project!). +/// /// # Examples /// /// ``` @@ -684,36 +683,29 @@ unsafe impl Send for CoherentAllocation {} /// unsafe impl kernel::transmute::AsBytes for MyStruct{}; /// /// # fn test(alloc: &kernel::dma::CoherentAllocation) -> Result { -/// let whole = kernel::dma_read!(alloc[2]); -/// let field = kernel::dma_read!(alloc[1].field); +/// let whole = kernel::dma_read!(alloc, [2]?); +/// let field = kernel::dma_read!(alloc, [1]?.field); /// # Ok::<(), Error>(()) } /// ``` #[macro_export] macro_rules! dma_read { - ($dma:expr, $idx: expr, $($field:tt)*) => {{ - (|| -> ::core::result::Result<_, $crate::error::Error> { - let item = $crate::dma::CoherentAllocation::item_from_index(&$dma, $idx)?; - // SAFETY: `item_from_index` ensures that `item` is always a valid pointer and can be - // dereferenced. The compiler also further validates the expression on whether `field` - // is a member of `item` when expanded by the macro. - unsafe { - let ptr_field = ::core::ptr::addr_of!((*item) $($field)*); - ::core::result::Result::Ok( - $crate::dma::CoherentAllocation::field_read(&$dma, ptr_field) - ) - } - })() + ($dma:expr, $($proj:tt)*) => {{ + let dma = &$dma; + let ptr = $crate::ptr::project!( + $crate::dma::CoherentAllocation::as_ptr(dma), $($proj)* + ); + // SAFETY: The pointer created by the projection is within the DMA region. + unsafe { $crate::dma::CoherentAllocation::field_read(dma, ptr) } }}; - ($dma:ident [ $idx:expr ] $($field:tt)* ) => { - $crate::dma_read!($dma, $idx, $($field)*) - }; - ($($dma:ident).* [ $idx:expr ] $($field:tt)* ) => { - $crate::dma_read!($($dma).*, $idx, $($field)*) - }; } /// Writes to a field of an item from an allocated region of structs. /// +/// The syntax is of the form `kernel::dma_write!(dma, proj, val)` where `dma` is an expression +/// evaluating to a [`CoherentAllocation`], `proj` is a +/// [projection specification](kernel::ptr::project!), and `val` is the value to be written to the +/// projected location. +/// /// # Examples /// /// ``` @@ -728,37 +720,31 @@ macro_rules! dma_read { /// unsafe impl kernel::transmute::AsBytes for MyStruct{}; /// /// # fn test(alloc: &kernel::dma::CoherentAllocation) -> Result { -/// kernel::dma_write!(alloc[2].member = 0xf); -/// kernel::dma_write!(alloc[1] = MyStruct { member: 0xf }); +/// kernel::dma_write!(alloc, [2]?.member, 0xf); +/// kernel::dma_write!(alloc, [1]?, MyStruct { member: 0xf }); /// # Ok::<(), Error>(()) } /// ``` #[macro_export] macro_rules! dma_write { - ($dma:ident [ $idx:expr ] $($field:tt)*) => {{ - $crate::dma_write!($dma, $idx, $($field)*) - }}; - ($($dma:ident).* [ $idx:expr ] $($field:tt)* ) => {{ - $crate::dma_write!($($dma).*, $idx, $($field)*) + (@parse [$dma:expr] [$($proj:tt)*] [, $val:expr]) => {{ + let dma = &$dma; + let ptr = $crate::ptr::project!( + mut $crate::dma::CoherentAllocation::as_mut_ptr(dma), $($proj)* + ); + let val = $val; + // SAFETY: The pointer created by the projection is within the DMA region. + unsafe { $crate::dma::CoherentAllocation::field_write(dma, ptr, val) } }}; - ($dma:expr, $idx: expr, = $val:expr) => { - (|| -> ::core::result::Result<_, $crate::error::Error> { - let item = $crate::dma::CoherentAllocation::item_from_index(&$dma, $idx)?; - // SAFETY: `item_from_index` ensures that `item` is always a valid item. - unsafe { $crate::dma::CoherentAllocation::field_write(&$dma, item, $val) } - ::core::result::Result::Ok(()) - })() + (@parse [$dma:expr] [$($proj:tt)*] [.$field:tt $($rest:tt)*]) => { + $crate::dma_write!(@parse [$dma] [$($proj)* .$field] [$($rest)*]) + }; + (@parse [$dma:expr] [$($proj:tt)*] [[$index:expr]? $($rest:tt)*]) => { + $crate::dma_write!(@parse [$dma] [$($proj)* [$index]?] [$($rest)*]) + }; + (@parse [$dma:expr] [$($proj:tt)*] [[$index:expr] $($rest:tt)*]) => { + $crate::dma_write!(@parse [$dma] [$($proj)* [$index]] [$($rest)*]) }; - ($dma:expr, $idx: expr, $(.$field:ident)* = $val:expr) => { - (|| -> ::core::result::Result<_, $crate::error::Error> { - let item = $crate::dma::CoherentAllocation::item_from_index(&$dma, $idx)?; - // SAFETY: `item_from_index` ensures that `item` is always a valid pointer and can be - // dereferenced. The compiler also further validates the expression on whether `field` - // is a member of `item` when expanded by the macro. - unsafe { - let ptr_field = ::core::ptr::addr_of_mut!((*item) $(.$field)*); - $crate::dma::CoherentAllocation::field_write(&$dma, ptr_field, $val) - } - ::core::result::Result::Ok(()) - })() + ($dma:expr, $($rest:tt)*) => { + $crate::dma_write!(@parse [$dma] [] [$($rest)*]) }; } -- cgit v1.2.3 From fdbaa9d2b78e0da9e1aeb303bbdc3adfe6d8e749 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Wed, 11 Mar 2026 11:50:49 +0100 Subject: rust: pin-init: replace shadowed return token by `unsafe`-to-create token We use a unit struct `__InitOk` in the closure generated by the initializer macros as the return value. We shadow it by creating a struct with the same name again inside of the closure, preventing early returns of `Ok` in the initializer (before all fields have been initialized). In the face of Type Alias Impl Trait (TAIT) and the next trait solver, this solution no longer works [1]. The shadowed struct can be named through type inference. In addition, there is an RFC proposing to add the feature of path inference to Rust, which would similarly allow [2]. Thus remove the shadowed token and replace it with an `unsafe` to create token. The reason we initially used the shadowing solution was because an alternative solution used a builder pattern. Gary writes [3]: In the early builder-pattern based InitOk, having a single InitOk type for token is unsound because one can launder an InitOk token used for one place to another initializer. I used a branded lifetime solution, and then you figured out that using a shadowed type would work better because nobody could construct it at all. The laundering issue does not apply to the approach we ended up with today. With this change, the example by Tim Chirananthavat in [1] no longer compiles and results in this error: error: cannot construct `pin_init::__internal::InitOk` with struct literal syntax due to private fields --> src/main.rs:26:17 | 26 | InferredType {} | ^^^^^^^^^^^^ | = note: private field `0` that was not provided help: you might have meant to use the `new` associated function | 26 - InferredType {} 26 + InferredType::new() | Applying the suggestion of using the `::new()` function, results in another expected error: error[E0133]: call to unsafe function `pin_init::__internal::InitOk::new` is unsafe and requires unsafe block --> src/main.rs:26:17 | 26 | InferredType::new() | ^^^^^^^^^^^^^^^^^^^ call to unsafe function | = note: consult the function's documentation for information on how to avoid undefined behavior Reported-by: Tim Chirananthavat Link: https://github.com/rust-lang/rust/issues/153535 [1] Link: https://github.com/rust-lang/rfcs/pull/3444#issuecomment-4016145373 [2] Link: https://github.com/rust-lang/rust/issues/153535#issuecomment-4017620804 [3] Fixes: fc6c6baa1f40 ("rust: init: add initialization macros") Cc: stable@vger.kernel.org Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260311105056.1425041-1-lossin@kernel.org [ Added period as mentioned. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/pin-init/internal/src/init.rs | 22 +++++++--------------- rust/pin-init/src/__internal.rs | 28 ++++++++++++++++++++++++---- 2 files changed, 31 insertions(+), 19 deletions(-) (limited to 'rust') diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs index 738f62c8105c..2fe918f4d82a 100644 --- a/rust/pin-init/internal/src/init.rs +++ b/rust/pin-init/internal/src/init.rs @@ -148,11 +148,6 @@ pub(crate) fn expand( let init_fields = init_fields(&fields, pinned, &data, &slot); let field_check = make_field_check(&fields, init_kind, &path); Ok(quote! {{ - // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return - // type and shadow it later when we insert the arbitrary user code. That way there will be - // no possibility of returning without `unsafe`. - struct __InitOk; - // Get the data about fields from the supplied type. // SAFETY: TODO let #data = unsafe { @@ -162,18 +157,15 @@ pub(crate) fn expand( #path::#get_data() }; // Ensure that `#data` really is of type `#data` and help with type inference: - let init = ::pin_init::__internal::#data_trait::make_closure::<_, __InitOk, #error>( + let init = ::pin_init::__internal::#data_trait::make_closure::<_, #error>( #data, move |slot| { - { - // Shadow the structure so it cannot be used to return early. - struct __InitOk; - #zeroable_check - #this - #init_fields - #field_check - } - Ok(__InitOk) + #zeroable_check + #this + #init_fields + #field_check + // SAFETY: we are the `init!` macro that is allowed to call this. + Ok(unsafe { ::pin_init::__internal::InitOk::new() }) } ); let init = move |slot| -> ::core::result::Result<(), #error> { diff --git a/rust/pin-init/src/__internal.rs b/rust/pin-init/src/__internal.rs index 90f18e9a2912..90adbdc1893b 100644 --- a/rust/pin-init/src/__internal.rs +++ b/rust/pin-init/src/__internal.rs @@ -46,6 +46,24 @@ where } } +/// Token type to signify successful initialization. +/// +/// Can only be constructed via the unsafe [`Self::new`] function. The initializer macros use this +/// token type to prevent returning `Ok` from an initializer without initializing all fields. +pub struct InitOk(()); + +impl InitOk { + /// Creates a new token. + /// + /// # Safety + /// + /// This function may only be called from the `init!` macro in `../internal/src/init.rs`. + #[inline(always)] + pub unsafe fn new() -> Self { + Self(()) + } +} + /// This trait is only implemented via the `#[pin_data]` proc-macro. It is used to facilitate /// the pin projections within the initializers. /// @@ -68,9 +86,10 @@ pub unsafe trait PinData: Copy { type Datee: ?Sized + HasPinData; /// Type inference helper function. - fn make_closure(self, f: F) -> F + #[inline(always)] + fn make_closure(self, f: F) -> F where - F: FnOnce(*mut Self::Datee) -> Result, + F: FnOnce(*mut Self::Datee) -> Result, { f } @@ -98,9 +117,10 @@ pub unsafe trait InitData: Copy { type Datee: ?Sized + HasInitData; /// Type inference helper function. - fn make_closure(self, f: F) -> F + #[inline(always)] + fn make_closure(self, f: F) -> F where - F: FnOnce(*mut Self::Datee) -> Result, + F: FnOnce(*mut Self::Datee) -> Result, { f } -- cgit v1.2.3 From 487f9b3dc6e507a982f1b984aa6bfbd9dc4b0567 Mon Sep 17 00:00:00 2001 From: John Hubbard Date: Wed, 11 Mar 2026 21:19:34 -0700 Subject: rust: cpufreq: suppress clippy::double_parens in Policy doctest The kernel fmt! proc macro wraps each format argument as &(arg). Passing a tuple such as (a, b) produces &((a, b)) after expansion. Clippy flags that as double_parens, but it is a false positive fixed in Clippy 1.92 [1] [2]. Suppress the warning on the affected doctest function with a reason attribute so it can be removed once the minimum toolchain moves past 1.92. [ We may end up deciding to support per-version Clippy lints, in which case we will need [3]. In the future, if [4] gets fixed, we may be able to use `Delimiter::None` as Gary suggested in [5]. Link: https://lore.kernel.org/rust-for-linux/20260307170929.153892-1-ojeda@kernel.org/ [3] Link: https://github.com/rust-lang/rust/issues/67062 [4] Link: https://lore.kernel.org/rust-for-linux/DGUA5GY2DGYN.3PG0FKLG7GFN1@garyguo.net/ [5] - Miguel ] Link: https://github.com/rust-lang/rust-clippy/issues/15852 [1] Link: https://github.com/rust-lang/rust-clippy/pull/15939 [2] Suggested-by: Gary Guo Signed-off-by: John Hubbard Acked-by: Viresh Kumar Link: https://patch.msgid.link/20260312041934.362840-2-jhubbard@nvidia.com [ Reworded to replace GitHub-like short link with full URLs in Link tags. Reworded reason string to match the style of a couple others we have elsewhere. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/cpufreq.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust') diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs index 76faa1ac8501..f5adee48d40c 100644 --- a/rust/kernel/cpufreq.rs +++ b/rust/kernel/cpufreq.rs @@ -401,6 +401,7 @@ impl TableBuilder { /// ``` /// use kernel::cpufreq::{DEFAULT_TRANSITION_LATENCY_NS, Policy}; /// +/// #[allow(clippy::double_parens, reason = "False positive before 1.92.0")] /// fn update_policy(policy: &mut Policy) { /// policy /// .set_dvfs_possible_from_any_cpu(true) -- cgit v1.2.3