1 // Copyright 2024, The Android Open Source Project
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 //! Low-level CPU-specific operations.
16
17 #[cfg(target_arch = "aarch64")]
18 pub mod aarch64;
19
20 /// Write with well-defined compiled behavior.
21 ///
22 /// See https://github.com/rust-lang/rust/issues/131894
23 ///
24 /// # Safety
25 ///
26 /// `dst` must be valid for writes.
27 #[inline]
write_volatile_u8(dst: *mut u8, src: u8)28 pub unsafe fn write_volatile_u8(dst: *mut u8, src: u8) {
29 cfg_if::cfg_if! {
30 if #[cfg(target_arch = "aarch64")] {
31 // SAFETY: `dst` is valid for writes.
32 unsafe { aarch64::strb(dst, src) }
33 } else {
34 compile_error!("Unsupported target_arch")
35 }
36 }
37 }
38
39 /// Flush `size` bytes of data cache by virtual address.
40 #[inline]
flush_region(start: usize, size: usize)41 pub(crate) fn flush_region(start: usize, size: usize) {
42 cfg_if::cfg_if! {
43 if #[cfg(target_arch = "aarch64")] {
44 let line_size = aarch64::min_dcache_line_size();
45 let end = start + size;
46 let start = crate::util::unchecked_align_down(start, line_size);
47
48 for line in (start..end).step_by(line_size) {
49 crate::dc!("cvau", line);
50 }
51 } else {
52 compile_error!("Unsupported target_arch")
53 }
54 }
55 }
56