summaryrefslogtreecommitdiff
path: root/rust/kernel/transmute.rs
AgeCommit message (Collapse)Author
2025-11-05rust: transmute: add `from_bytes_prefix` family of methodsAlexandre Courbot
The `from_bytes*` family of functions expect a slice of the exact same size as the requested type. This can be sometimes cumbersome for callers that deal with dynamic stream of data that needs to be manually cut before each invocation of `from_bytes`. To simplify such callers, introduce a new `from_bytes*_prefix` family of methods, which split the input slice at the index required for the equivalent `from_bytes` method to succeed, and return its result alongside with the remainder of the slice. This design is inspired by zerocopy's `try_*_from_prefix` family of methods. Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com> Reviewed-by: Danilo Krummrich <dakr@kernel.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Danilo Krummrich <dakr@kernel.org> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Message-ID: <20251029-nova-vbios-frombytes-v1-1-ac441ebc1de3@nvidia.com> Message-ID: <20251101-b4-frombytes-prefix-v1-1-0d9c1fd63b34@nvidia.com>
2025-08-28rust: transmute: add `from_bytes_copy` method to `FromBytes` traitAlexandre Courbot
`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. Lima
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 Courbot
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 Courbot
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 Garcia
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>