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rust: alloc: Add realloc and alloc_zeroed to the GlobalAlloc impl

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While there are default impls for these methods, using the respective C
api's is faster. Currently neither the existing nor these new
GlobalAlloc method implementations are actually called. Instead the
__rust_* function defined below the GlobalAlloc impl are used. With
rustc 1.71 these functions will be gone and all allocation calls will go
through the GlobalAlloc implementation.

Link: https://github.com/Rust-for-Linux/linux/issues/68
Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
[boqun: add size adjustment for alignment requirement]
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230730012905.643822-4-boqun.feng@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Björn Roy Baron 2023-07-29 18:29:04 -07:00 committed by Miguel Ojeda
parent f39a97d0d8
commit 0beaf546b4
1 changed files with 27 additions and 0 deletions
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27
rust/kernel/allocator.rs
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@ -51,6 +51,33 @@ unsafe impl GlobalAlloc for KernelAllocator {
bindings::kfree(ptr as *const core::ffi::c_void);
}
}
unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
// SAFETY:
// - `new_size`, when rounded up to the nearest multiple of `layout.align()`, will not
// overflow `isize` by the function safety requirement.
// - `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
// SAFETY:
// - `ptr` is either null or a pointer allocated by this allocator by the function safety
// requirement.
// - the size of `layout` is not zero because `new_size` is not zero by the function safety
// requirement.
unsafe { krealloc_aligned(ptr, layout, bindings::GFP_KERNEL) }
}
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
// SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
// requirement.
unsafe {
krealloc_aligned(
ptr::null_mut(),
layout,
bindings::GFP_KERNEL | bindings::__GFP_ZERO,
)
}
}
}
#[global_allocator]