From b481dd85f5694aa241a6a638240526d48637d19e Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sat, 17 Feb 2024 01:27:17 +0100 Subject: rust: upgrade to Rust 1.77.1 This is the next upgrade to the Rust toolchain, from 1.76.0 to 1.77.1 (i.e. the latest) [1]. See the upgrade policy [2] and the comments on the first upgrade in commit 3ed03f4da06e ("rust: upgrade to Rust 1.68.2"). # Unstable features The `offset_of` feature (single-field `offset_of!`) that we were using got stabilized in Rust 1.77.0 [3]. Therefore, now the only unstable features allowed to be used outside the `kernel` crate is `new_uninit`, though other code to be upstreamed may increase the list. Please see [4] for details. # Required changes Rust 1.77.0 merged the `unused_tuple_struct_fields` lint into `dead_code`, thus upgrading it from `allow` to `warn` [5]. In turn, this made `rustc` complain about the `ThisModule`'s pointer field being never read, but the previous patch adds the `as_ptr` method to it, needed by Binder [6], so that we do not need to locally `allow` it. # Other changes Rust 1.77.0 introduces the `--check-cfg` feature [7], for which there is a Call for Testing going on [8]. We were requested to test it and we found it useful [9] -- we will likely enable it in the future. # `alloc` upgrade and reviewing The vast majority of changes are due to our `alloc` fork being upgraded at once. There are two kinds of changes to be aware of: the ones coming from upstream, which we should follow as closely as possible, and the updates needed in our added fallible APIs to keep them matching the newer infallible APIs coming from upstream. Instead of taking a look at the diff of this patch, an alternative approach is reviewing a diff of the changes between upstream `alloc` and the kernel's. This allows to easily inspect the kernel additions only, especially to check if the fallible methods we already have still match the infallible ones in the new version coming from upstream. Another approach is reviewing the changes introduced in the additions in the kernel fork between the two versions. This is useful to spot potentially unintended changes to our additions. To apply these approaches, one may follow steps similar to the following to generate a pair of patches that show the differences between upstream Rust and the kernel (for the subset of `alloc` we use) before and after applying this patch: # Get the difference with respect to the old version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > old.patch git -C linux restore rust/alloc # Apply this patch. git -C linux am rust-upgrade.patch # Get the difference with respect to the new version. git -C rust checkout $(linux/scripts/min-tool-version.sh rustc) git -C linux ls-tree -r --name-only HEAD -- rust/alloc | cut -d/ -f3- | grep -Fv README.md | xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH git -C linux diff --patch-with-stat --summary -R > new.patch git -C linux restore rust/alloc Now one may check the `new.patch` to take a look at the additions (first approach) or at the difference between those two patches (second approach). For the latter, a side-by-side tool is recommended. Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1770-2024-03-21 [1] Link: https://rust-for-linux.com/rust-version-policy [2] Link: https://github.com/rust-lang/rust/pull/118799 [3] Link: https://github.com/Rust-for-Linux/linux/issues/2 [4] Link: https://github.com/rust-lang/rust/pull/118297 [5] Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-2-08ba9197f637@google.com/#Z31rust:kernel:lib.rs [6] Link: https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html [7] Link: https://github.com/rust-lang/rfcs/pull/3013#issuecomment-1936648479 [8] Link: https://github.com/rust-lang/rust/issues/82450#issuecomment-1947462977 [9] Reviewed-by: Alice Ryhl Tested-by: Boqun Feng Link: https://lore.kernel.org/r/20240217002717.57507-1-ojeda@kernel.org [ Upgraded to 1.77.1. Removed `allow(dead_code)` thanks to the previous patch. Reworded accordingly. No changes to `alloc` during the beta. ] Signed-off-by: Miguel Ojeda --- scripts/min-tool-version.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/min-tool-version.sh') diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh index 5927cc6b7de3..6086e00e640e 100755 --- a/scripts/min-tool-version.sh +++ b/scripts/min-tool-version.sh @@ -33,7 +33,7 @@ llvm) fi ;; rustc) - echo 1.76.0 + echo 1.77.1 ;; bindgen) echo 0.65.1 -- cgit v1.2.3 From 56f64b370612d8967df2c2e0cead805444d4e71a Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 1 Apr 2024 23:23:03 +0200 Subject: rust: upgrade to Rust 1.78.0 This is the next upgrade to the Rust toolchain, from 1.77.1 to 1.78.0 (i.e. the latest) [1]. See the upgrade policy [2] and the comments on the first upgrade in commit 3ed03f4da06e ("rust: upgrade to Rust 1.68.2"). It is much smaller than previous upgrades, since the `alloc` fork was dropped in commit 9d0441bab775 ("rust: alloc: remove our fork of the `alloc` crate") [3]. # Unstable features There have been no changes to the set of unstable features used in our own code. Therefore, the only unstable features allowed to be used outside the `kernel` crate is still `new_uninit`. However, since we finally dropped our `alloc` fork [3], all the unstable features used by `alloc` (~30 language ones, ~60 library ones) are not a concern anymore. This reduces the maintenance burden, increases the chances of new compiler versions working without changes and gets us closer to the goal of supporting several compiler versions. It also means that, ignoring non-language/library features, we are currently left with just the few language features needed to implement the kernel `Arc`, the `new_uninit` library feature, the `compiler_builtins` marker and the few `no_*` `cfg`s we pass when compiling `core`/`alloc`. Please see [4] for details. # Required changes ## LLVM's data layout Rust 1.77.0 (i.e. the previous upgrade) introduced a check for matching LLVM data layouts [5]. Then, Rust 1.78.0 upgraded LLVM's bundled major version from 17 to 18 [6], which changed the data layout in x86 [7]. Thus update the data layout in our custom target specification for x86 so that the compiler does not complain about the mismatch: error: data-layout for target `target-5559158138856098584`, `e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128`, differs from LLVM target's `x86_64-linux-gnu` default layout, `e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128` In the future, the goal is to drop the custom target specifications. Meanwhile, if we want to support other LLVM versions used in `rustc` (e.g. for LTO), we will need to add some extra logic (e.g. conditional on LLVM's version, or extracting the data layout from an existing built-in target specification). ## `unused_imports` Rust's `unused_imports` lint covers both unused and redundant imports. Now, in 1.78.0, the lint detects more cases of redundant imports [8]. Thus one of the previous patches cleaned them up. ## Clippy's `new_without_default` Clippy now suggests to implement `Default` even when `new()` is `const`, since `Default::default()` may call `const` functions even if it is not `const` itself [9]. Thus one of the previous patches implemented it. # Other changes in Rust Rust 1.78.0 introduced `feature(asm_goto)` [10] [11]. This feature was discussed in the past [12]. Rust 1.78.0 introduced `feature(const_refs_to_static)` [13] to allow referencing statics in constants and extended `feature(const_mut_refs)` to allow raw mutable pointers in constants. Together, this should cover the kernel's `VTABLE` use case. In fact, the implementation [14] in upstream Rust added a test case for it [15]. Rust 1.78.0 with debug assertions enabled (i.e. `-Cdebug-assertions=y`, kernel's `CONFIG_RUST_DEBUG_ASSERTIONS=y`) now always checks all unsafe preconditions, though without a way to opt-out for particular cases [16]. It would be ideal to have a way to selectively disable certain checks per-call site for this one (i.e. not just per check but for particular instances of a check), even if the vast majority of the checks remain in place [17]. Rust 1.78.0 also improved a couple issues we reported when giving feedback for the new `--check-cfg` feature [18] [19]. # `alloc` upgrade and reviewing As mentioned above, compiler upgrades will not update `alloc` anymore, since we dropped our `alloc` fork [3]. Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1780-2024-05-02 [1] Link: https://rust-for-linux.com/rust-version-policy [2] Link: https://lore.kernel.org/rust-for-linux/20240328013603.206764-1-wedsonaf@gmail.com/ [3] Link: https://github.com/Rust-for-Linux/linux/issues/2 [4] Link: https://github.com/rust-lang/rust/pull/120062 [5] Link: https://github.com/rust-lang/rust/pull/120055 [6] Link: https://reviews.llvm.org/D86310 [7] Link: https://github.com/rust-lang/rust/pull/117772 [8] Link: https://github.com/rust-lang/rust-clippy/pull/10903 [9] Link: https://github.com/rust-lang/rust/pull/119365 [10] Link: https://github.com/rust-lang/rust/issues/119364 [11] Link: https://lore.kernel.org/rust-for-linux/ZWipTZysC2YL7qsq@Boquns-Mac-mini.home/ [12] Link: https://github.com/rust-lang/rust/issues/119618 [13] Link: https://github.com/rust-lang/rust/pull/120932 [14] Link: https://github.com/rust-lang/rust/pull/120932/files#diff-e6fc1622c46054cd46b1d225c5386c5554564b3b0fa8a03c2dc2d8627a1079d9 [15] Link: https://github.com/rust-lang/rust/issues/120969 [16] Link: https://github.com/Rust-for-Linux/linux/issues/354 [17] Link: https://github.com/rust-lang/rust/pull/121202 [18] Link: https://github.com/rust-lang/rust/pull/121237 [19] Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20240401212303.537355-4-ojeda@kernel.org [ Added a few more details and links I mentioned in the list. - Miguel ] Signed-off-by: Miguel Ojeda --- scripts/min-tool-version.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/min-tool-version.sh') diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh index 6086e00e640e..91c91201212c 100755 --- a/scripts/min-tool-version.sh +++ b/scripts/min-tool-version.sh @@ -33,7 +33,7 @@ llvm) fi ;; rustc) - echo 1.77.1 + echo 1.78.0 ;; bindgen) echo 0.65.1 -- cgit v1.2.3