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author | Björn Roy Baron <bjorn3_gh@protonmail.com> | 2023-07-29 18:29:04 -0700 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2023-08-07 11:33:34 +0200 |
commit | 0beaf546b4f198dd767b5a01a73f24db269ff6e2 (patch) | |
tree | 3e2140a0f3fbe42b45a981150736c8ea8b578508 /rust | |
parent | f39a97d0d8a765268b8de17f2e34393e7cb2cd2d (diff) | |
download | lwn-0beaf546b4f198dd767b5a01a73f24db269ff6e2.tar.gz lwn-0beaf546b4f198dd767b5a01a73f24db269ff6e2.zip |
rust: alloc: Add realloc and alloc_zeroed to the GlobalAlloc impl
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>
Diffstat (limited to 'rust')
-rw-r--r-- | rust/kernel/allocator.rs | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs index d4a3670ef405..72d66c23883c 100644 --- a/rust/kernel/allocator.rs +++ b/rust/kernel/allocator.rs @@ -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] |