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 let mut size = layout.size();
22 // which together with the slab guarantees !! 22
23 // object (see comments in `kmalloc()` for !! 23 if layout.align() > bindings::ARCH_SLAB_MINALIGN {
24 let size = layout.size(); !! 24 // The alignment requirement exceeds the slab guarantee, thus try to enlarge the size
>> 25 // to use the "power-of-two" size/alignment guarantee (see comments in `kmalloc()` for
>> 26 // more information).
>> 27 //
>> 28 // Note that `layout.size()` (after padding) is guaranteed to be a multiple of
>> 29 // `layout.align()`, so `next_power_of_two` gives enough alignment guarantee.
>> 30 size = size.next_power_of_two();
>> 31 }
25 32
26 // SAFETY: 33 // SAFETY:
27 // - `ptr` is either null or a pointer ret 34 // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the
28 // function safety requirement. 35 // function safety requirement.
29 // - `size` is greater than 0 since it's f !! 36 // - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
30 // to the function safety requirement) !! 37 // according to the function safety requirement) or a result from `next_power_of_two()`.
31 unsafe { bindings::krealloc(ptr as *const 38 unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 }
32 } 39 }
33 40
34 unsafe impl GlobalAlloc for KernelAllocator { 41 unsafe impl GlobalAlloc for KernelAllocator {
35 unsafe fn alloc(&self, layout: Layout) -> 42 unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
36 // SAFETY: `ptr::null_mut()` is null a 43 // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
37 // requirement. 44 // requirement.
38 unsafe { krealloc_aligned(ptr::null_mu 45 unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL) }
39 } 46 }
40 47
41 unsafe fn dealloc(&self, ptr: *mut u8, _la 48 unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
42 unsafe { 49 unsafe {
43 bindings::kfree(ptr as *const core 50 bindings::kfree(ptr as *const core::ffi::c_void);
44 } 51 }
45 } 52 }
46 53
47 unsafe fn realloc(&self, ptr: *mut u8, lay 54 unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
48 // SAFETY: 55 // SAFETY:
49 // - `new_size`, when rounded up to th 56 // - `new_size`, when rounded up to the nearest multiple of `layout.align()`, will not
50 // overflow `isize` by the function 57 // overflow `isize` by the function safety requirement.
51 // - `layout.align()` is a proper alig 58 // - `layout.align()` is a proper alignment (i.e. not zero and must be a power of two).
52 let layout = unsafe { Layout::from_siz 59 let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) };
53 60
54 // SAFETY: 61 // SAFETY:
55 // - `ptr` is either null or a pointer 62 // - `ptr` is either null or a pointer allocated by this allocator by the function safety
56 // requirement. 63 // requirement.
57 // - the size of `layout` is not zero 64 // - the size of `layout` is not zero because `new_size` is not zero by the function safety
58 // requirement. 65 // requirement.
59 unsafe { krealloc_aligned(ptr, layout, 66 unsafe { krealloc_aligned(ptr, layout, GFP_KERNEL) }
60 } 67 }
61 68
62 unsafe fn alloc_zeroed(&self, layout: Layo 69 unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
63 // SAFETY: `ptr::null_mut()` is null a 70 // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
64 // requirement. 71 // requirement.
65 unsafe { krealloc_aligned(ptr::null_mu 72 unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL | __GFP_ZERO) }
66 } 73 }
67 } 74 }
68 75
69 #[global_allocator] 76 #[global_allocator]
70 static ALLOCATOR: KernelAllocator = KernelAllo 77 static ALLOCATOR: KernelAllocator = KernelAllocator;
71 78
72 // See <https://github.com/rust-lang/rust/pull 79 // See <https://github.com/rust-lang/rust/pull/86844>.
73 #[no_mangle] 80 #[no_mangle]
74 static __rust_no_alloc_shim_is_unstable: u8 = 81 static __rust_no_alloc_shim_is_unstable: u8 = 0;
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.