compiler-rt/lib/scudo/standalone/checksum.h

   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
  34 namespace scudo {
  35
  36 enum 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.
  45 inline 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
  54 bool hasHardwareCRC32();
  55 WEAK u32 computeHardwareCRC32(u32 Crc, uptr Data);
  56
  57 } // namespace scudo
  58
  59 #endif // SCUDO_CHECKSUM_H_