pm24.git, branch rust-6.13

rust: alloc: Fix `ArrayLayout` allocations

2024-11-24T23:11:07Z

We were accidentally allocating a layout for the *square* of the object size due to a variable shadowing mishap. Fixes memory bloat and page allocation failures in drm/asahi. Reported-by: Janne Grunau Fixes: 9e7bbfa18276 ("rust: alloc: introduce `ArrayLayout`") Signed-off-by: Asahi Lina Acked-by: Danilo Krummrich Reviewed-by: Neal Gompa Link: https://lore.kernel.org/r/20241123-rust-fix-arraylayout-v1-1-197e64c95bd4@asahilina.net Signed-off-by: Miguel Ojeda

docs: rust: remove spurious item in `expect` list

2024-11-24T23:10:29Z

This list started as a "when to prefer `expect`" list, but at some point during writing I changed it to a "prefer `expect` unless..." one. However, the first bullet remained, which does not make sense anymore. Thus remove it. In addition, fix nearby typo. Fixes: 04866494e936 ("Documentation: rust: discuss `#[expect(...)]` in the guidelines") Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20241117133127.473937-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda

rust: allow `clippy::needless_lifetimes`

2024-11-24T23:09:16Z

In beta Clippy (i.e. Rust 1.83.0), the `needless_lifetimes` lint has been extended [1] to suggest eliding `impl` lifetimes, e.g. error: the following explicit lifetimes could be elided: 'a --> rust/kernel/list.rs:647:6 | 647 | impl<'a, T: ?Sized + ListItem, const ID: u64> FusedIterator for Iter<'a, T, ID> {} | ^^ ^^ | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes = note: `-D clippy::needless-lifetimes` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]` help: elide the lifetimes | 647 - impl<'a, T: ?Sized + ListItem, const ID: u64> FusedIterator for Iter<'a, T, ID> {} 647 + impl, const ID: u64> FusedIterator for Iter<'_, T, ID> {} A possibility would have been to clean them -- the RFC patch [2] did this, while asking if we wanted these cleanups. There is an open issue [3] in Clippy about being able to differentiate some of the new cases, e.g. those that do not involve introducing `'_`. Thus it seems others feel similarly. Thus, for the time being, we decided to `allow` the lint. Link: https://github.com/rust-lang/rust-clippy/pull/13286 [1] Link: https://lore.kernel.org/rust-for-linux/20241012231300.397010-1-ojeda@kernel.org/ [2] Link: https://github.com/rust-lang/rust-clippy/issues/13514 [3] Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20241116181538.369355-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda

rust: warn on bindgen < 0.69.5 and libclang >= 19.1

2024-11-12T20:26:54Z

When testing a `clang` upgrade with Rust Binder, Alice encountered [1] a build failure caused by `bindgen` not translating some symbols related to tracepoints. This was caused by commit 2e770edd8ce1 ("[libclang] Compute the right spelling location") changing the behavior of a function exposed by `libclang`. `bindgen` fixed the regression in commit 600f63895f73 ("Use clang_getFileLocation instead of clang_getSpellingLocation"). However, the regression fix is only available in `bindgen` versions 0.69.5 or later (it was backported for 0.69.x). This means that when older bindgen versions are used with new versions of `libclang`, `bindgen` may do the wrong thing, which could lead to a build failure. Alice encountered the bug with some header files related to tracepoints, but it could also cause build failures in other circumstances. Thus, always emit a warning when using an old `bindgen` with a new `libclang` so that other people do not have to spend time chasing down the same bug. However, testing just the version is inconvenient, since distributions do patch their packages without changing the version, so I reduced the issue into the following piece of code that can trigger the issue: #define F(x) int x##x F(foo); In particular, an unpatched `bindgen` will ignore the macro expansion and thus not provide a declaration for the exported `int`. Thus add a build test to `rust_is_available.sh` using the code above (that is only triggered if the versions appear to be affected), following what we did for the 0.66.x issue. Moreover, I checked the status in the major distributions we have instructions for: - Fedora 41 was affected but is now OK, since it now ships `bindgen` 0.69.5. Thanks Ben for the quick reply on the updates that were ongoing. Fedora 40 and earlier are OK (older `libclang`, and they also now carry `bindgen` 0.69.5). - Debian Sid was affected but is now OK, since they now ship a patched `bindgen` binary (0.66.1-7+b3). The issue was reported to Debian by email and then as a bug report [2]. Thanks NoisyCoil and Matthias for the quick replies. NoisyCoil handled the needed updates. Debian may upgrade to `bindgen` 0.70.x, too. Debian Testing is OK (older `libclang` so far). - Ubuntu non-LTS (oracular) is affected. The issue was reported to Ubuntu by email and then as a bug report [3]. Ubuntu LTS is not affected (older `libclang` so far). - Arch Linux, Gentoo Linux and openSUSE should be OK (newer `bindgen` is provided). Nix as well (older `libclang` so far). This issue was also added to our "live list" that tracks issues around distributions [4]. Cc: Ben Beasley Cc: NoisyCoil Cc: Matthias Geiger Link: https://lore.kernel.org/rust-for-linux/20241030-bindgen-libclang-warn-v1-1-3a7ba9fedcfe@google.com/ [1] Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1086510 [2] Link: https://bugs.launchpad.net/ubuntu/+source/rust-bindgen-cli/+bug/2086639 [3] Link: https://github.com/Rust-for-Linux/linux/issues/1127 [4] Co-developed-by: Alice Ryhl Signed-off-by: Alice Ryhl Link: https://lore.kernel.org/r/20241111201607.653149-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda

rust: use custom FFI integer types

2024-11-10T22:58:00Z

Currently FFI integer types are defined in libcore. This commit creates the `ffi` crate and asks bindgen to use that crate for FFI integer types instead of `core::ffi`. This commit is preparatory and no type changes are made in this commit yet. Signed-off-by: Gary Guo Link: https://lore.kernel.org/r/20240913213041.395655-4-gary@garyguo.net [ Added `rustdoc`, `rusttest` and KUnit tests support. Rebased on top of `rust-next` (e.g. migrated more `core::ffi` cases). Reworded crate docs slightly and formatted. - Miguel ] Signed-off-by: Miguel Ojeda

rust: map `__kernel_size_t` and friends also to usize/isize

2024-11-10T22:58:00Z

Currently bindgen has special logic to recognise `size_t` and `ssize_t` and map them to Rust `usize` and `isize`. Similarly, `ptrdiff_t` is mapped to `isize`. However this falls short for `__kernel_size_t`, `__kernel_ssize_t` and `__kernel_ptrdiff_t`. To ensure that they are mapped to usize/isize rather than 32/64 integers depending on platform, blocklist them in bindgen parameters and manually provide their definition. Signed-off-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Trevor Gross Link: https://lore.kernel.org/r/20240913213041.395655-3-gary@garyguo.net [ Formatted comment. - Miguel ] Signed-off-by: Miguel Ojeda

rust: fix size_t in bindgen prototypes of C builtins

2024-11-10T22:54:43Z

Without `-fno-builtin`, for functions like memcpy/memmove (and many others), bindgen seems to be using the clang-provided prototype. This prototype is ABI-wise compatible, but the issue is that it does not have the same information as the source code w.r.t. typedefs. For example, bindgen generates the following: extern "C" { pub fn strlen(s: *const core::ffi::c_char) -> core::ffi::c_ulong; } note that the return type is `c_ulong` (i.e. unsigned long), despite the size_t-is-usize behavior (this is default, and we have not opted out from it using --no-size_t-is-usize). Similarly, memchr's size argument should be of type `__kernel_size_t`, but bindgen generates `c_ulong` directly. We want to ensure any `size_t` is translated to Rust `usize` so that we can avoid having them be different type on 32-bit and 64-bit architectures, and hence would require a lot of excessive type casts when calling FFI functions. I found that this bindgen behavior (which probably is caused by libclang) can be disabled by `-fno-builtin`. Using the flag for compiled code can result in less optimisation because compiler cannot assume about their properties anymore, but this should not affect bindgen. [ Trevor asked: "I wonder how reliable this behavior is. Maybe bindgen could do a better job controlling this, is there an open issue?". Gary replied: ..."apparently this is indeed the suggested approach in https://github.com/rust-lang/rust-bindgen/issues/1770". - Miguel ] Signed-off-by: Gary Guo Link: https://lore.kernel.org/r/20240913213041.395655-2-gary@garyguo.net [ Formatted comment. - Miguel ] Signed-off-by: Miguel Ojeda

rust: sync: add global lock support

2024-11-10T21:56:57Z

Add support for creating global variables that are wrapped in a mutex or spinlock. The implementation here is intended to replace the global mutex workaround found in the Rust Binder RFC [1]. In both cases, the global lock must be initialized before first use. The macro is unsafe to use for the same reason. The separate initialization step is required because it is tricky to access the value of __ARCH_SPIN_LOCK_UNLOCKED from Rust. Doing so will require changes to the C side. That change will happen as a follow-up to this patch. Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-2-08ba9197f637@google.com/#Z31drivers:android:context.rs [1] Signed-off-by: Alice Ryhl Reviewed-by: Boqun Feng Link: https://lore.kernel.org/r/20241023-static-mutex-v6-1-d7efdadcc84f@google.com [ Simplified a few intra-doc links. Formatted a few comments. Reworded title. - Miguel ] Signed-off-by: Miguel Ojeda

rust: macros: enable the rest of the tests

2024-11-01T21:02:53Z

Now that the rusttest target for the macros crate is compiled with the kernel crate as a dependency, the rest of the rustdoc tests can be enabled. Signed-off-by: Ethan D. Twardy Reviewed-by: Alice Ryhl Link: https://github.com/Rust-for-Linux/linux/issues/1076 Link: https://lore.kernel.org/r/20240704145607.17732-5-ethan.twardy@gmail.com [ Rebased (use `K{Box,Vec}` instead, enable `lint_reasons` feature). Remove unneeded `rust` as language in examples, as well as `#[macro_use]` `extern`s. - Miguel ] Signed-off-by: Miguel Ojeda

rust: macros: enable paste! use from macro_rules!

2024-11-01T21:02:53Z

According to the rustdoc for the proc_macro crate[1], tokens captured from a "macro variable" (e.g. from within macro_rules!) may be delimited by invisible tokens and be contained within a proc_macro::Group. Previously, this scenario was not handled by macros::paste, which caused a proc-macro panic when the corresponding tests are enabled. Enable the tests, and handle this case by making macros::paste::concat recursive. Link: https://doc.rust-lang.org/stable/proc_macro/enum.Delimiter.html [1] Signed-off-by: Ethan D. Twardy Reviewed-by: Alice Ryhl Link: https://github.com/Rust-for-Linux/linux/issues/1076 Link: https://lore.kernel.org/r/20240704145607.17732-4-ethan.twardy@gmail.com [ Rebased (one fix was already applied) and reworded. Remove unneeded `rust` as language in examples. - Miguel ] Signed-off-by: Miguel Ojeda