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2025-08-28rust: transmute: add `from_bytes_copy` method to `FromBytes` traitAlexandre Courbot1-0/+18
`FromBytes::from_bytes` comes with a few practical limitations: - It requires the bytes slice to have the same alignment as the returned type, which might not be guaranteed in the case of a byte stream, - It returns a reference, requiring the returned type to implement `Clone` if one wants to keep the value for longer than the lifetime of the slice. To overcome these when needed, add a `from_bytes_copy` with a default implementation in the trait. `from_bytes_copy` returns an owned value that is populated using an unaligned read, removing the lifetime constraint and making it usable even on non-aligned byte slices. Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Benno Lossin <lossin@kernel.org> Link: https://lore.kernel.org/r/20250826-nova_firmware-v2-1-93566252fe3a@nvidia.com Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
2025-08-28rust: transmute: Add methods for FromBytes traitChristian S. Lima1-1/+68
The two methods added take a slice of bytes and return those bytes in a specific type. These methods are useful when we need to transform the stream of bytes into specific type. Since the `is_aligned` method for pointer types has been stabilized in `1.79` version and is being used in this patch, I'm enabling the feature. In this case, using this method is useful to check the alignment and avoid a giant boilerplate, such as `(foo.as_ptr() as usize) % core::mem::align_of::<T>() == 0`. Also add `#[allow(clippy::incompatible_msrv)]` where needed until the MSRV is updated to `1.79`. Suggested-by: Benno Lossin <benno.lossin@proton.me> Link: https://github.com/Rust-for-Linux/linux/issues/1119 Reviewed-by: Alice Ryhl <aliceryhl@google.com> Tested-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Christian S. Lima <christiansantoslima21@gmail.com> Link: https://lore.kernel.org/r/20250824213134.27079-1-christiansantoslima21@gmail.com Acked-by: Miguel Ojeda <ojeda@kernel.org> [acourbot@nvidia.com: minor rewording of commit messages and doccomments] [acourbot@nvidia.com: revert slice implementation removal] [acourbot@nvidia.com: move incompatible_msrv clippy allow closer to site of need] [acourbot@nvidia.com: call the doctest method] Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
2025-08-22rust: transmute: add `as_bytes_mut` method to `AsBytes` traitAlexandre Courbot1-0/+15
Types that implement both `AsBytes` and `FromBytes` can be safely modified as a slice of bytes. Add a `as_bytes_mut` method for that purpose. [acourbot@nvidia.com: use fully qualified `core::mem::size_of_val` to build with Rust 1.78.] Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Danilo Krummrich <dakr@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> Reviewed-by: Benno Lossin <lossin@kernel.org> Acked-by: Miguel Ojeda <ojeda@kernel.org> Link: https://lore.kernel.org/r/20250801-as_bytes-v5-2-975f87d5dc85@nvidia.com Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
2025-08-22rust: transmute: add `as_bytes` method for `AsBytes` traitAlexandre Courbot1-1/+11
Every type that implements `AsBytes` should be able to provide its byte representation. Introduce the `as_bytes` method that returns the implementer as a stream of bytes, and provide a default implementation that should be suitable for any type that satisfies `AsBytes`'s safety requirements. [acourbot@nvidia.com: use fully qualified `core::mem::size_of_val` to build with Rust 1.78.] Reviewed-by: Danilo Krummrich <dakr@kernel.org> Reviewed-by: Benno Lossin <lossin@kernel.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Gary Guo <gary@garyguo.net> Acked-by: Miguel Ojeda <ojeda@kernel.org> Link: https://lore.kernel.org/r/20250801-as_bytes-v5-1-975f87d5dc85@nvidia.com Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
2024-10-10rust: kernel: move `FromBytes` and `AsBytes` traits to a new `transmute` moduleAliet Exposito Garcia1-0/+71
Refactor the `FromBytes` and `AsBytes` traits from `types.rs` into a new `transmute.rs` module: - Add `rust/kernel/transmute.rs` with the definitions of `FromBytes` and `AsBytes`. - Remove the same trait definitions from `rust/kernel/types.rs`. - Update `rust/kernel/uaccess.rs` to import `AsBytes` and `FromBytes` from `transmute.rs`. The traits and their implementations remain unchanged. Suggested-by: Benno Lossin <benno.lossin@proton.me> Link: https://github.com/Rust-for-Linux/linux/issues/1117 Signed-off-by: Aliet Exposito Garcia <aliet.exposito@gmail.com> Reviewed-by: Fiona Behrens <me@kloenk.dev> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20240918225115.2309224-2-aliet.exposito@gmail.com [ Rebased on top of the lints series and slightly reworded. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>