From 66084c81211cf754766306b11ae31e186c02278b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= <bjorn3_gh@protonmail.com>
Date: Sat, 29 Jul 2023 18:29:04 -0700
Subject: [PATCH] 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>
---
rust/kernel/allocator.rs | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/rust/kernel/allocator.rs b/rust/kernel/allocator.rs
index d4a3670ef4050..72d66c23883c1 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]