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: -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 #ifdef __SSE4_2__ 21 #include <smmintrin.h> 22 #define CRC32_INTRINSIC FIRST_32_SECOND_64(_mm_crc32_u32, _mm_crc32_u64) 23 #endif 24 #ifdef __ARM_FEATURE_CRC32 25 #include <arm_acle.h> 26 #define CRC32_INTRINSIC FIRST_32_SECOND_64(__crc32cw, __crc32cd) 27 #endif 28 29 namespace scudo { 30 31 enum class Checksum : u8 { 32 BSD = 0, 33 HardwareCRC32 = 1, 34 }; 35 36 // BSD checksum, unlike a software CRC32, doesn't use any array lookup. We save 37 // significantly on memory accesses, as well as 1K of CRC32 table, on platforms 38 // that do no support hardware CRC32. The checksum itself is 16-bit, which is at 39 // odds with CRC32, but enough for our needs. 40 inline u16 computeBSDChecksum(u16 Sum, uptr Data) { 41 for (u8 I = 0; I < sizeof(Data); I++) { 42 Sum = static_cast<u16>((Sum >> 1) | ((Sum & 1) << 15)); 43 Sum = static_cast<u16>(Sum + (Data & 0xff)); 44 Data >>= 8; 45 } 46 return Sum; 47 } 48 49 bool hasHardwareCRC32(); 50 WEAK u32 computeHardwareCRC32(u32 Crc, uptr Data); 51 52 } // namespace scudo 53 54 #endif // SCUDO_CHECKSUM_H_ 55