compiler-rt/lib/scudo/standalone/tests/checksum_test.cpp

   1 //===-- checksum_test.cpp ---------------------------------------*- 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 #include "tests/scudo_unit_test.h"
  10
  11 #include "checksum.h"
  12
  13 #include <string.h>
  14
  15 static scudo::u16 computeSoftwareChecksum(scudo::u32 Seed, scudo::uptr *Array,
  16                                           scudo::uptr ArraySize) {
  17   scudo::u16 Checksum = static_cast<scudo::u16>(Seed & 0xffff);
  18   for (scudo::uptr I = 0; I < ArraySize; I++)
  19     Checksum = scudo::computeBSDChecksum(Checksum, Array[I]);
  20   return Checksum;
  21 }
  22
  23 static scudo::u16 computeHardwareChecksum(scudo::u32 Seed, scudo::uptr *Array,
  24                                           scudo::uptr ArraySize) {
  25   scudo::u32 Crc = Seed;
  26   for (scudo::uptr I = 0; I < ArraySize; I++)
  27     Crc = scudo::computeHardwareCRC32(Crc, Array[I]);
  28   return static_cast<scudo::u16>((Crc & 0xffff) ^ (Crc >> 16));
  29 }
  30
  31 typedef scudo::u16 (*ComputeChecksum)(scudo::u32, scudo::uptr *, scudo::uptr);
  32
  33 // This verifies that flipping bits in the data being checksummed produces a
  34 // different checksum. We do not use random data to avoid flakyness.
  35 template <ComputeChecksum F> static void verifyChecksumFunctionBitFlip() {
  36   scudo::uptr Array[sizeof(scudo::u64) / sizeof(scudo::uptr)];
  37   const scudo::uptr ArraySize = ARRAY_SIZE(Array);
  38   memset(Array, 0xaa, sizeof(Array));
  39   const scudo::u32 Seed = 0x41424343U;
  40   const scudo::u16 Reference = F(Seed, Array, ArraySize);
  41   scudo::u8 IdenticalChecksums = 0;
  42   for (scudo::uptr I = 0; I < ArraySize; I++) {
  43     for (scudo::uptr J = 0; J < SCUDO_WORDSIZE; J++) {
  44       Array[I] ^= scudo::uptr{1} << J;
  45       if (F(Seed, Array, ArraySize) == Reference)
  46         IdenticalChecksums++;
  47       Array[I] ^= scudo::uptr{1} << J;
  48     }
  49   }
  50   // Allow for a couple of identical checksums over the whole set of flips.
  51   EXPECT_LE(IdenticalChecksums, 2);
  52 }
  53
  54 TEST(ScudoChecksumTest, ChecksumFunctions) {
  55   verifyChecksumFunctionBitFlip<computeSoftwareChecksum>();
  56   if (&scudo::computeHardwareCRC32 && scudo::hasHardwareCRC32())
  57     verifyChecksumFunctionBitFlip<computeHardwareChecksum>();
  58 }