1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 2
3 //! Allocator support. 3 //! Allocator support.
4 4
5 use super::{flags::*, Flags}; 5 use super::{flags::*, Flags};
6 use core::alloc::{GlobalAlloc, Layout}; 6 use core::alloc::{GlobalAlloc, Layout};
7 use core::ptr; 7 use core::ptr;
8 8
9 struct KernelAllocator; 9 struct KernelAllocator;
10 10
11 /// Calls `krealloc` with a proper size to all 11 /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.
12 /// 12 ///
13 /// # Safety 13 /// # Safety
14 /// 14 ///
15 /// - `ptr` can be either null or a pointer wh 15 /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
16 /// - `new_layout` must have a non-zero size. 16 /// - `new_layout` must have a non-zero size.
17 pub(crate) unsafe fn krealloc_aligned(ptr: *mu 17 pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {
18 // Customized layouts from `Layout::from_s 18 // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
19 let layout = new_layout.pad_to_align(); 19 let layout = new_layout.pad_to_align();
20 20
21 // Note that `layout.size()` (after paddin 21 // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`
22 // which together with the slab guarantees 22 // which together with the slab guarantees means the `krealloc` will return a properly aligned
23 // object (see comments in `kmalloc()` for 23 // object (see comments in `kmalloc()` for more information).
24 let size = layout.size(); 24 let size = layout.size();
25 25
26 // SAFETY: 26 // SAFETY:
27 // - `ptr` is either null or a pointer ret 27 // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
28 // function safety requirement. 28 // function safety requirement.
29 // - `size` is greater than 0 since it's f 29 // - `size` is greater than 0 since it's from `layout.size()` (which cannot be zero according
30 // to the function safety requirement) 30 // to the function safety requirement)
31 unsafe { bindings::krealloc(ptr as *const 31 unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 }
32 } 32 }
33 33
34 unsafe impl GlobalAlloc for KernelAllocator { 34 unsafe impl GlobalAlloc for KernelAllocator {
35 unsafe fn alloc(&self, layout: Layout) -> 35 unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
36 // SAFETY: `ptr::null_mut()` is null a 36 // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
37 // requirement. 37 // requirement.
38 unsafe { krealloc_aligned(ptr::null_mu 38 unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL) }
39 } 39 }
40 40
41 unsafe fn dealloc(&self, ptr: *mut u8, _la 41 unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
42 unsafe { 42 unsafe {
43 bindings::kfree(ptr as *const core 43 bindings::kfree(ptr as *const core::ffi::c_void);
44 } 44 }
45 } 45 }
46 46
47 unsafe fn realloc(&self, ptr: *mut u8, lay 47 unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
48 // SAFETY: 48 // SAFETY:
49 // - `new_size`, when rounded up to th 49 // - `new_size`, when rounded up to the nearest multiple of `layout.align()`, will not
50 // overflow `isize` by the function 50 // overflow `isize` by the function safety requirement.
51 // - `layout.align()` is a proper alig 51 // - `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
52 let layout = unsafe { Layout::from_siz 52 let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
53 53
54 // SAFETY: 54 // SAFETY:
55 // - `ptr` is either null or a pointer 55 // - `ptr` is either null or a pointer allocated by this allocator by the function safety
56 // requirement. 56 // requirement.
57 // - the size of `layout` is not zero 57 // - the size of `layout` is not zero because `new_size` is not zero by the function safety
58 // requirement. 58 // requirement.
59 unsafe { krealloc_aligned(ptr, layout, 59 unsafe { krealloc_aligned(ptr, layout, GFP_KERNEL) }
60 } 60 }
61 61
62 unsafe fn alloc_zeroed(&self, layout: Layo 62 unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
63 // SAFETY: `ptr::null_mut()` is null a 63 // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
64 // requirement. 64 // requirement.
65 unsafe { krealloc_aligned(ptr::null_mu 65 unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL | __GFP_ZERO) }
66 } 66 }
67 } 67 }
68 68
69 #[global_allocator] 69 #[global_allocator]
70 static ALLOCATOR: KernelAllocator = KernelAllo 70 static ALLOCATOR: KernelAllocator = KernelAllocator;
71 71
72 // See <https://github.com/rust-lang/rust/pull 72 // See <https://github.com/rust-lang/rust/pull/86844>.
73 #[no_mangle] 73 #[no_mangle]
74 static __rust_no_alloc_shim_is_unstable: u8 = 74 static __rust_no_alloc_shim_is_unstable: u8 = 0;
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