`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>
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>
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>
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>
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>
Alexandre Courbot
Christian S. Lima
Aliet Exposito Garcia