1//===-- checksum.h ----------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef SCUDO_CHECKSUM_H_
10#define SCUDO_CHECKSUM_H_
11
12#include "internal_defs.h"
13
14// Hardware CRC32 is supported at compilation via the following:
15// - for i386 & x86_64: -mcrc32 (earlier: -msse4.2)
16// - for ARM & AArch64: -march=armv8-a+crc or -mcrc
17// An additional check must be performed at runtime as well to make sure the
18// emitted instructions are valid on the target host.
19
20#if defined(__CRC32__)
21// NB: clang has <crc32intrin.h> but GCC does not
22#include <smmintrin.h>
23#define CRC32_INTRINSIC \
24 FIRST_32_SECOND_64(__builtin_ia32_crc32si, __builtin_ia32_crc32di)
25#elif defined(__SSE4_2__)
26#include <smmintrin.h>
27#define CRC32_INTRINSIC FIRST_32_SECOND_64(_mm_crc32_u32, _mm_crc32_u64)
28#endif
29#ifdef __ARM_FEATURE_CRC32
30#include <arm_acle.h>
31#define CRC32_INTRINSIC FIRST_32_SECOND_64(__crc32cw, __crc32cd)
32#endif
33#ifdef __loongarch__
34#include <larchintrin.h>
35#define CRC32_INTRINSIC FIRST_32_SECOND_64(__crcc_w_w_w, __crcc_w_d_w)
36#endif
37
38namespace scudo {
39
40enum class Checksum : u8 {
41 BSD = 0,
42 HardwareCRC32 = 1,
43};
44
45// BSD checksum, unlike a software CRC32, doesn't use any array lookup. We save
46// significantly on memory accesses, as well as 1K of CRC32 table, on platforms
47// that do no support hardware CRC32. The checksum itself is 16-bit, which is at
48// odds with CRC32, but enough for our needs.
49inline u16 computeBSDChecksum(u16 Sum, uptr Data) {
50 for (u8 I = 0; I < sizeof(Data); I++) {
51 Sum = static_cast<u16>((Sum >> 1) | ((Sum & 1) << 15));
52 Sum = static_cast<u16>(Sum + (Data & 0xff));
53 Data >>= 8;
54 }
55 return Sum;
56}
57
58bool hasHardwareCRC32();
59WEAK u32 computeHardwareCRC32(u32 Crc, uptr Data);
60
61} // namespace scudo
62
63#endif // SCUDO_CHECKSUM_H_
64