diff options
| author | Alice Ryhl <aliceryhl@google.com> | 2025-08-11 12:31:50 +0000 |
|---|---|---|
| committer | Danilo Krummrich <dakr@kernel.org> | 2025-08-15 20:55:16 +0200 |
| commit | 1b1a946dc2b535785663742f9e4f15fd64bece60 (patch) | |
| tree | 48efba1b1aa1a92aaca4329c53a6f74b385a974c /rust/kernel/alloc | |
| parent | f87de6919dc126f22c7b5bf92e378f0346f190a8 (diff) | |
rust: alloc: specify the minimum alignment of each allocator
The kernel's allocators sometimes provide a higher alignment than the
end-user requested, so add a new constant on the Allocator trait to let
the allocator specify what its minimum guaranteed alignment is.
This allows the ForeignOwnable trait to provide a more accurate value of
FOREIGN_ALIGN when using a pointer type such as Box, which will be
useful with certain collections such as XArray that store its own data
in the low bits of pointers.
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250811-align-min-allocator-v2-1-3386cc94f4fc@google.com
[ Add helper for ARCH_KMALLOC_MINALIGN; remove cast to usize. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Diffstat (limited to 'rust/kernel/alloc')
| -rw-r--r-- | rust/kernel/alloc/allocator.rs | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index aa2dfa9dca4c..5003907f0240 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -17,6 +17,8 @@ use crate::alloc::{AllocError, Allocator}; use crate::bindings; use crate::pr_warn; +const ARCH_KMALLOC_MINALIGN: usize = bindings::ARCH_KMALLOC_MINALIGN; + /// The contiguous kernel allocator. /// /// `Kmalloc` is typically used for physically contiguous allocations up to page size, but also @@ -128,6 +130,8 @@ impl ReallocFunc { // - passing a pointer to a valid memory allocation is OK, // - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same. unsafe impl Allocator for Kmalloc { + const MIN_ALIGN: usize = ARCH_KMALLOC_MINALIGN; + #[inline] unsafe fn realloc( ptr: Option<NonNull<u8>>, @@ -145,6 +149,8 @@ unsafe impl Allocator for Kmalloc { // - passing a pointer to a valid memory allocation is OK, // - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same. unsafe impl Allocator for Vmalloc { + const MIN_ALIGN: usize = kernel::page::PAGE_SIZE; + #[inline] unsafe fn realloc( ptr: Option<NonNull<u8>>, @@ -169,6 +175,8 @@ unsafe impl Allocator for Vmalloc { // - passing a pointer to a valid memory allocation is OK, // - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same. unsafe impl Allocator for KVmalloc { + const MIN_ALIGN: usize = ARCH_KMALLOC_MINALIGN; + #[inline] unsafe fn realloc( ptr: Option<NonNull<u8>>, |