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f3accd0437
commit 1bae8729e5 upstream.
The following FFI types are replaced compared to `core::ffi`:
1. `char` type is now always mapped to `u8`, since kernel uses
`-funsigned-char` on the C code. `core::ffi` maps it to platform
default ABI, which can be either signed or unsigned.
2. `long` is now always mapped to `isize`. It's very common in the
kernel to use `long` to represent a pointer-sized integer, and in
fact `intptr_t` is a typedef of `long` in the kernel. Enforce this
mapping rather than mapping to `i32/i64` depending on platform can
save us a lot of unnecessary casts.
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240913213041.395655-5-gary@garyguo.net
[ Moved `uaccess` changes from the next commit, since they were
irrefutable patterns that Rust >= 1.82.0 warns about. Reworded
slightly and reformatted a few documentation comments. Rebased on
top of `rust-next`. Added the removal of two casts to avoid Clippy
warnings. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
49 lines
1.2 KiB
Rust
49 lines
1.2 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Foreign function interface (FFI) types.
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//!
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//! This crate provides mapping from C primitive types to Rust ones.
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//!
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//! The Rust [`core`] crate provides [`core::ffi`], which maps integer types to the platform default
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//! C ABI. The kernel does not use [`core::ffi`], so it can customise the mapping that deviates from
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//! the platform default.
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#![no_std]
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macro_rules! alias {
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($($name:ident = $ty:ty;)*) => {$(
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#[allow(non_camel_case_types, missing_docs)]
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pub type $name = $ty;
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// Check size compatibility with `core`.
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const _: () = assert!(
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core::mem::size_of::<$name>() == core::mem::size_of::<core::ffi::$name>()
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);
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)*}
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}
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alias! {
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// `core::ffi::c_char` is either `i8` or `u8` depending on architecture. In the kernel, we use
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// `-funsigned-char` so it's always mapped to `u8`.
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c_char = u8;
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c_schar = i8;
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c_uchar = u8;
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c_short = i16;
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c_ushort = u16;
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c_int = i32;
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c_uint = u32;
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// In the kernel, `intptr_t` is defined to be `long` in all platforms, so we can map the type to
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// `isize`.
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c_long = isize;
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c_ulong = usize;
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c_longlong = i64;
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c_ulonglong = u64;
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}
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pub use core::ffi::c_void;
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