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 34namespace scudo { 35 36enum class Checksum : u8 { 37 BSD = 0, 38 HardwareCRC32 = 1, 39}; 40 41// BSD checksum, unlike a software CRC32, doesn't use any array lookup. We save 42// significantly on memory accesses, as well as 1K of CRC32 table, on platforms 43// that do no support hardware CRC32. The checksum itself is 16-bit, which is at 44// odds with CRC32, but enough for our needs. 45inline u16 computeBSDChecksum(u16 Sum, uptr Data) { 46 for (u8 I = 0; I < sizeof(Data); I++) { 47 Sum = static_cast<u16>((Sum >> 1) | ((Sum & 1) << 15)); 48 Sum = static_cast<u16>(Sum + (Data & 0xff)); 49 Data >>= 8; 50 } 51 return Sum; 52} 53 54bool hasHardwareCRC32(); 55WEAK u32 computeHardwareCRC32(u32 Crc, uptr Data); 56 57} // namespace scudo 58 59#endif // SCUDO_CHECKSUM_H_ 60