mirror of
https://github.com/torvalds/linux
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743766565d
Currently, for `const`s that bindgen doesn't recognise, we define a
helper constant with
const <TYPE> BINDINGS_<NAME> = <NAME>;
in `bindings_helper.h` and then we put
pub const <NAME>: <TYPE> = BINDINGS_<NAME>;
in `bindings/lib.rs`. This is fine since we currently only have 3
constants that are defined this way, but is going to be more annoying
when more constants are added since every new constant needs to be
defined in two places.
This patch changes the way we define constant helpers to
const <TYPE> RUST_CONST_HELPER_<NAME> = <NAME>;
and then use `sed` to postprocess Rust code generated by bindgen to
remove the distinct prefix, so users of the `bindings` crate can refer
to the name directly.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231104145700.2495176-1-gary@garyguo.net
[ Reworded for typos. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
89 lines
3.4 KiB
Rust
89 lines
3.4 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Allocator support.
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use core::alloc::{GlobalAlloc, Layout};
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use core::ptr;
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use crate::bindings;
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struct KernelAllocator;
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/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.
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///
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/// # Safety
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///
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/// - `ptr` can be either null or a pointer which has been allocated by this allocator.
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/// - `new_layout` must have a non-zero size.
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unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
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// Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
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let layout = new_layout.pad_to_align();
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let mut size = layout.size();
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if layout.align() > bindings::ARCH_SLAB_MINALIGN {
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// The alignment requirement exceeds the slab guarantee, thus try to enlarge the size
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// to use the "power-of-two" size/alignment guarantee (see comments in `kmalloc()` for
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// more information).
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//
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// Note that `layout.size()` (after padding) is guaranteed to be a multiple of
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// `layout.align()`, so `next_power_of_two` gives enough alignment guarantee.
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size = size.next_power_of_two();
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}
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// SAFETY:
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// - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
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// function safety requirement.
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// - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
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// according to the function safety requirement) or a result from `next_power_of_two()`.
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unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 }
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}
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unsafe impl GlobalAlloc for KernelAllocator {
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unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
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// SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
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// requirement.
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unsafe { krealloc_aligned(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
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}
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unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
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unsafe {
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bindings::kfree(ptr as *const core::ffi::c_void);
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}
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}
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unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
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// SAFETY:
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// - `new_size`, when rounded up to the nearest multiple of `layout.align()`, will not
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// overflow `isize` by the function safety requirement.
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// - `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
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let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
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// SAFETY:
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// - `ptr` is either null or a pointer allocated by this allocator by the function safety
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// requirement.
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// - the size of `layout` is not zero because `new_size` is not zero by the function safety
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// requirement.
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unsafe { krealloc_aligned(ptr, layout, bindings::GFP_KERNEL) }
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}
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unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
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// SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
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// requirement.
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unsafe {
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krealloc_aligned(
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ptr::null_mut(),
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layout,
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bindings::GFP_KERNEL | bindings::__GFP_ZERO,
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)
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}
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}
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}
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#[global_allocator]
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static ALLOCATOR: KernelAllocator = KernelAllocator;
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// See <https://github.com/rust-lang/rust/pull/86844>.
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#[no_mangle]
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static __rust_no_alloc_shim_is_unstable: u8 = 0;
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