compiler-rt/lib/fuzzer/FuzzerTracePC.cpp

   1 //===- FuzzerTracePC.cpp - PC tracing--------------------------------------===//
   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 // Trace PCs.
   9 // This module implements __sanitizer_cov_trace_pc_guard[_init],
  10 // the callback required for -fsanitize-coverage=trace-pc-guard instrumentation.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "FuzzerTracePC.h"
  15 #include "FuzzerBuiltins.h"
  16 #include "FuzzerBuiltinsMsvc.h"
  17 #include "FuzzerCorpus.h"
  18 #include "FuzzerDefs.h"
  19 #include "FuzzerDictionary.h"
  20 #include "FuzzerExtFunctions.h"
  21 #include "FuzzerIO.h"
  22 #include "FuzzerPlatform.h"
  23 #include "FuzzerUtil.h"
  24 #include "FuzzerValueBitMap.h"
  25 #include <set>
  26
  27 // Used by -fsanitize-coverage=stack-depth to track stack depth
  28 ATTRIBUTES_INTERFACE_TLS_INITIAL_EXEC uintptr_t __sancov_lowest_stack;
  29
  30 namespace fuzzer {
  31
  32 TracePC TPC;
  33
  34 size_t TracePC::GetTotalPCCoverage() {
  35   return ObservedPCs.size();
  36 }
  37
  38
  39 void TracePC::HandleInline8bitCountersInit(uint8_t *Start, uint8_t *Stop) {
  40   if (Start == Stop) return;
  41   if (NumModules &&
  42       Modules[NumModules - 1].Start() == Start)
  43     return;
  44   assert(NumModules <
  45          sizeof(Modules) / sizeof(Modules[0]));
  46   auto &M = Modules[NumModules++];
  47   uint8_t *AlignedStart = RoundUpByPage(Start);
  48   uint8_t *AlignedStop  = RoundDownByPage(Stop);
  49   size_t NumFullPages = AlignedStop > AlignedStart ?
  50                         (AlignedStop - AlignedStart) / PageSize() : 0;
  51   bool NeedFirst = Start < AlignedStart || !NumFullPages;
  52   bool NeedLast  = Stop > AlignedStop && AlignedStop >= AlignedStart;
  53   M.NumRegions = NumFullPages + NeedFirst + NeedLast;;
  54   assert(M.NumRegions > 0);
  55   M.Regions = new Module::Region[M.NumRegions];
  56   assert(M.Regions);
  57   size_t R = 0;
  58   if (NeedFirst)
  59     M.Regions[R++] = {Start, std::min(Stop, AlignedStart), true, false};
  60   for (uint8_t *P = AlignedStart; P < AlignedStop; P += PageSize())
  61     M.Regions[R++] = {P, P + PageSize(), true, true};
  62   if (NeedLast)
  63     M.Regions[R++] = {AlignedStop, Stop, true, false};
  64   assert(R == M.NumRegions);
  65   assert(M.Size() == (size_t)(Stop - Start));
  66   assert(M.Stop() == Stop);
  67   assert(M.Start() == Start);
  68   NumInline8bitCounters += M.Size();
  69 }
  70
  71 void TracePC::HandlePCsInit(const uintptr_t *Start, const uintptr_t *Stop) {
  72   const PCTableEntry *B = reinterpret_cast<const PCTableEntry *>(Start);
  73   const PCTableEntry *E = reinterpret_cast<const PCTableEntry *>(Stop);
  74   if (NumPCTables && ModulePCTable[NumPCTables - 1].Start == B) return;
  75   assert(NumPCTables < sizeof(ModulePCTable) / sizeof(ModulePCTable[0]));
  76   ModulePCTable[NumPCTables++] = {B, E};
  77   NumPCsInPCTables += E - B;
  78 }
  79
  80 void TracePC::PrintModuleInfo() {
  81   if (NumModules) {
  82     Printf("INFO: Loaded %zd modules   (%zd inline 8-bit counters): ",
  83            NumModules, NumInline8bitCounters);
  84     for (size_t i = 0; i < NumModules; i++)
  85       Printf("%zd [%p, %p), ", Modules[i].Size(), Modules[i].Start(),
  86              Modules[i].Stop());
  87     Printf("\n");
  88   }
  89   if (NumPCTables) {
  90     Printf("INFO: Loaded %zd PC tables (%zd PCs): ", NumPCTables,
  91            NumPCsInPCTables);
  92     for (size_t i = 0; i < NumPCTables; i++) {
  93       Printf("%zd [%p,%p), ", ModulePCTable[i].Stop - ModulePCTable[i].Start,
  94              ModulePCTable[i].Start, ModulePCTable[i].Stop);
  95     }
  96     Printf("\n");
  97
  98     if (NumInline8bitCounters && NumInline8bitCounters != NumPCsInPCTables) {
  99       Printf("ERROR: The size of coverage PC tables does not match the\n"
 100              "number of instrumented PCs. This might be a compiler bug,\n"
 101              "please contact the libFuzzer developers.\n"
 102              "Also check https://bugs.llvm.org/show_bug.cgi?id=34636\n"
 103              "for possible workarounds (tl;dr: don't use the old GNU ld)\n");
 104       _Exit(1);
 105     }
 106   }
 107   if (size_t NumExtraCounters = ExtraCountersEnd() - ExtraCountersBegin())
 108     Printf("INFO: %zd Extra Counters\n", NumExtraCounters);
 109
 110   size_t MaxFeatures = CollectFeatures([](uint32_t) {});
 111   if (MaxFeatures > std::numeric_limits<uint32_t>::max())
 112     Printf("WARNING: The coverage PC tables may produce up to %zu features.\n"
 113            "This exceeds the maximum 32-bit value. Some features may be\n"
 114            "ignored, and fuzzing may become less precise. If possible,\n"
 115            "consider refactoring the fuzzer into several smaller fuzzers\n"
 116            "linked against only a portion of the current target.\n",
 117            MaxFeatures);
 118 }
 119
 120 ATTRIBUTE_NO_SANITIZE_ALL
 121 void TracePC::HandleCallerCallee(uintptr_t Caller, uintptr_t Callee) {
 122   const uintptr_t kBits = 12;
 123   const uintptr_t kMask = (1 << kBits) - 1;
 124   uintptr_t Idx = (Caller & kMask) | ((Callee & kMask) << kBits);
 125   ValueProfileMap.AddValueModPrime(Idx);
 126 }
 127
 128 /// \return the address of the previous instruction.
 129 /// Note: the logic is copied from `sanitizer_common/sanitizer_stacktrace.h`
 130 inline ALWAYS_INLINE uintptr_t GetPreviousInstructionPc(uintptr_t PC) {
 131 #if defined(__arm__)
 132   // T32 (Thumb) branch instructions might be 16 or 32 bit long,
 133   // so we return (pc-2) in that case in order to be safe.
 134   // For A32 mode we return (pc-4) because all instructions are 32 bit long.
 135   return (PC - 3) & (~1);
 136 #elif defined(__sparc__) || defined(__mips__)
 137   return PC - 8;
 138 #elif defined(__riscv__)
 139   return PC - 2;
 140 #elif defined(__i386__) || defined(__x86_64__) || defined(_M_IX86) || defined(_M_X64)
 141   return PC - 1;
 142 #else
 143   return PC - 4;
 144 #endif
 145 }
 146
 147 /// \return the address of the next instruction.
 148 /// Note: the logic is copied from `sanitizer_common/sanitizer_stacktrace.cpp`
 149 ALWAYS_INLINE uintptr_t TracePC::GetNextInstructionPc(uintptr_t PC) {
 150 #if defined(__mips__)
 151   return PC + 8;
 152 #elif defined(__powerpc__) || defined(__sparc__) || defined(__arm__) ||        \
 153     defined(__aarch64__) || defined(__loongarch__)
 154   return PC + 4;
 155 #else
 156   return PC + 1;
 157 #endif
 158 }
 159
 160 void TracePC::UpdateObservedPCs() {
 161   std::vector<uintptr_t> CoveredFuncs;
 162   auto ObservePC = [&](const PCTableEntry *TE) {
 163     if (ObservedPCs.insert(TE).second && DoPrintNewPCs) {
 164       PrintPC("\tNEW_PC: %p %F %L", "\tNEW_PC: %p",
 165               GetNextInstructionPc(TE->PC));
 166       Printf("\n");
 167     }
 168   };
 169
 170   auto Observe = [&](const PCTableEntry *TE) {
 171     if (PcIsFuncEntry(TE))
 172       if (++ObservedFuncs[TE->PC] == 1 && NumPrintNewFuncs)
 173         CoveredFuncs.push_back(TE->PC);
 174     ObservePC(TE);
 175   };
 176
 177   if (NumPCsInPCTables) {
 178     if (NumInline8bitCounters == NumPCsInPCTables) {
 179       for (size_t i = 0; i < NumModules; i++) {
 180         auto &M = Modules[i];
 181         assert(M.Size() ==
 182                (size_t)(ModulePCTable[i].Stop - ModulePCTable[i].Start));
 183         for (size_t r = 0; r < M.NumRegions; r++) {
 184           auto &R = M.Regions[r];
 185           if (!R.Enabled) continue;
 186           for (uint8_t *P = R.Start; P < R.Stop; P++)
 187             if (*P)
 188               Observe(&ModulePCTable[i].Start[M.Idx(P)]);
 189         }
 190       }
 191     }
 192   }
 193
 194   for (size_t i = 0, N = Min(CoveredFuncs.size(), NumPrintNewFuncs); i < N;
 195        i++) {
 196     Printf("\tNEW_FUNC[%zd/%zd]: ", i + 1, CoveredFuncs.size());
 197     PrintPC("%p %F %L", "%p", GetNextInstructionPc(CoveredFuncs[i]));
 198     Printf("\n");
 199   }
 200 }
 201
 202 uintptr_t TracePC::PCTableEntryIdx(const PCTableEntry *TE) {
 203   size_t TotalTEs = 0;
 204   for (size_t i = 0; i < NumPCTables; i++) {
 205     auto &M = ModulePCTable[i];
 206     if (TE >= M.Start && TE < M.Stop)
 207       return TotalTEs + TE - M.Start;
 208     TotalTEs += M.Stop - M.Start;
 209   }
 210   assert(0);
 211   return 0;
 212 }
 213
 214 const TracePC::PCTableEntry *TracePC::PCTableEntryByIdx(uintptr_t Idx) {
 215   for (size_t i = 0; i < NumPCTables; i++) {
 216     auto &M = ModulePCTable[i];
 217     size_t Size = M.Stop - M.Start;
 218     if (Idx < Size) return &M.Start[Idx];
 219     Idx -= Size;
 220   }
 221   return nullptr;
 222 }
 223
 224 static std::string GetModuleName(uintptr_t PC) {
 225   char ModulePathRaw[4096] = "";  // What's PATH_MAX in portable C++?
 226   void *OffsetRaw = nullptr;
 227   if (!EF->__sanitizer_get_module_and_offset_for_pc(
 228       reinterpret_cast<void *>(PC), ModulePathRaw,
 229       sizeof(ModulePathRaw), &OffsetRaw))
 230     return "";
 231   return ModulePathRaw;
 232 }
 233
 234 template<class CallBack>
 235 void TracePC::IterateCoveredFunctions(CallBack CB) {
 236   for (size_t i = 0; i < NumPCTables; i++) {
 237     auto &M = ModulePCTable[i];
 238     assert(M.Start < M.Stop);
 239     auto ModuleName = GetModuleName(M.Start->PC);
 240     for (auto NextFE = M.Start; NextFE < M.Stop; ) {
 241       auto FE = NextFE;
 242       assert(PcIsFuncEntry(FE) && "Not a function entry point");
 243       do {
 244         NextFE++;
 245       } while (NextFE < M.Stop && !(PcIsFuncEntry(NextFE)));
 246       CB(FE, NextFE, ObservedFuncs[FE->PC]);
 247     }
 248   }
 249 }
 250
 251 void TracePC::SetFocusFunction(const std::string &FuncName) {
 252   // This function should be called once.
 253   assert(!FocusFunctionCounterPtr);
 254   // "auto" is not a valid function name. If this function is called with "auto"
 255   // that means the auto focus functionality failed.
 256   if (FuncName.empty() || FuncName == "auto")
 257     return;
 258   for (size_t M = 0; M < NumModules; M++) {
 259     auto &PCTE = ModulePCTable[M];
 260     size_t N = PCTE.Stop - PCTE.Start;
 261     for (size_t I = 0; I < N; I++) {
 262       if (!(PcIsFuncEntry(&PCTE.Start[I]))) continue;  // not a function entry.
 263       auto Name = DescribePC("%F", GetNextInstructionPc(PCTE.Start[I].PC));
 264       if (Name[0] == 'i' && Name[1] == 'n' && Name[2] == ' ')
 265         Name = Name.substr(3, std::string::npos);
 266       if (FuncName != Name) continue;
 267       Printf("INFO: Focus function is set to '%s'\n", Name.c_str());
 268       FocusFunctionCounterPtr = Modules[M].Start() + I;
 269       return;
 270     }
 271   }
 272
 273   Printf("ERROR: Failed to set focus function. Make sure the function name is "
 274          "valid (%s) and symbolization is enabled.\n", FuncName.c_str());
 275   exit(1);
 276 }
 277
 278 bool TracePC::ObservedFocusFunction() {
 279   return FocusFunctionCounterPtr && *FocusFunctionCounterPtr;
 280 }
 281
 282 void TracePC::PrintCoverage(bool PrintAllCounters) {
 283   if (!EF->__sanitizer_symbolize_pc ||
 284       !EF->__sanitizer_get_module_and_offset_for_pc) {
 285     Printf("INFO: __sanitizer_symbolize_pc or "
 286            "__sanitizer_get_module_and_offset_for_pc is not available,"
 287            " not printing coverage\n");
 288     return;
 289   }
 290   Printf(PrintAllCounters ? "FULL COVERAGE:\n" : "COVERAGE:\n");
 291   auto CoveredFunctionCallback = [&](const PCTableEntry *First,
 292                                      const PCTableEntry *Last,
 293                                      uintptr_t Counter) {
 294     assert(First < Last);
 295     auto VisualizePC = GetNextInstructionPc(First->PC);
 296     std::string FileStr = DescribePC("%s", VisualizePC);
 297     if (!IsInterestingCoverageFile(FileStr))
 298       return;
 299     std::string FunctionStr = DescribePC("%F", VisualizePC);
 300     if (FunctionStr.find("in ") == 0)
 301       FunctionStr = FunctionStr.substr(3);
 302     std::string LineStr = DescribePC("%l", VisualizePC);
 303     size_t NumEdges = Last - First;
 304     std::vector<uintptr_t> UncoveredPCs;
 305     std::vector<uintptr_t> CoveredPCs;
 306     for (auto TE = First; TE < Last; TE++)
 307       if (!ObservedPCs.count(TE))
 308         UncoveredPCs.push_back(TE->PC);
 309       else
 310         CoveredPCs.push_back(TE->PC);
 311
 312     if (PrintAllCounters) {
 313       Printf("U");
 314       for (auto PC : UncoveredPCs)
 315         Printf(DescribePC(" %l", GetNextInstructionPc(PC)).c_str());
 316       Printf("\n");
 317
 318       Printf("C");
 319       for (auto PC : CoveredPCs)
 320         Printf(DescribePC(" %l", GetNextInstructionPc(PC)).c_str());
 321       Printf("\n");
 322     } else {
 323       Printf("%sCOVERED_FUNC: hits: %zd", Counter ? "" : "UN", Counter);
 324       Printf(" edges: %zd/%zd", NumEdges - UncoveredPCs.size(), NumEdges);
 325       Printf(" %s %s:%s\n", FunctionStr.c_str(), FileStr.c_str(),
 326              LineStr.c_str());
 327       if (Counter)
 328         for (auto PC : UncoveredPCs)
 329           Printf("  UNCOVERED_PC: %s\n",
 330                  DescribePC("%s:%l", GetNextInstructionPc(PC)).c_str());
 331     }
 332   };
 333
 334   IterateCoveredFunctions(CoveredFunctionCallback);
 335 }
 336
 337 // Value profile.
 338 // We keep track of various values that affect control flow.
 339 // These values are inserted into a bit-set-based hash map.
 340 // Every new bit in the map is treated as a new coverage.
 341 //
 342 // For memcmp/strcmp/etc the interesting value is the length of the common
 343 // prefix of the parameters.
 344 // For cmp instructions the interesting value is a XOR of the parameters.
 345 // The interesting value is mixed up with the PC and is then added to the map.
 346
 347 ATTRIBUTE_NO_SANITIZE_ALL
 348 void TracePC::AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
 349                                 size_t n, bool StopAtZero) {
 350   if (!n) return;
 351   size_t Len = std::min(n, Word::GetMaxSize());
 352   const uint8_t *A1 = reinterpret_cast<const uint8_t *>(s1);
 353   const uint8_t *A2 = reinterpret_cast<const uint8_t *>(s2);
 354   uint8_t B1[Word::kMaxSize];
 355   uint8_t B2[Word::kMaxSize];
 356   // Copy the data into locals in this non-msan-instrumented function
 357   // to avoid msan complaining further.
 358   size_t Hash = 0;  // Compute some simple hash of both strings.
 359   for (size_t i = 0; i < Len; i++) {
 360     B1[i] = A1[i];
 361     B2[i] = A2[i];
 362     size_t T = B1[i];
 363     Hash ^= (T << 8) | B2[i];
 364   }
 365   size_t I = 0;
 366   uint8_t HammingDistance = 0;
 367   for (; I < Len; I++) {
 368     if (B1[I] != B2[I] || (StopAtZero && B1[I] == 0)) {
 369       HammingDistance = static_cast<uint8_t>(Popcountll(B1[I] ^ B2[I]));
 370       break;
 371     }
 372   }
 373   size_t PC = reinterpret_cast<size_t>(caller_pc);
 374   size_t Idx = (PC & 4095) | (I << 12);
 375   Idx += HammingDistance;
 376   ValueProfileMap.AddValue(Idx);
 377   TORCW.Insert(Idx ^ Hash, Word(B1, Len), Word(B2, Len));
 378 }
 379
 380 template <class T>
 381 ATTRIBUTE_TARGET_POPCNT ALWAYS_INLINE
 382 ATTRIBUTE_NO_SANITIZE_ALL
 383 void TracePC::HandleCmp(uintptr_t PC, T Arg1, T Arg2) {
 384   uint64_t ArgXor = Arg1 ^ Arg2;
 385   if (sizeof(T) == 4)
 386       TORC4.Insert(ArgXor, Arg1, Arg2);
 387   else if (sizeof(T) == 8)
 388       TORC8.Insert(ArgXor, Arg1, Arg2);
 389   uint64_t HammingDistance = Popcountll(ArgXor);  // [0,64]
 390   uint64_t AbsoluteDistance = (Arg1 == Arg2 ? 0 : Clzll(Arg1 - Arg2) + 1);
 391   ValueProfileMap.AddValue(PC * 128 + HammingDistance);
 392   ValueProfileMap.AddValue(PC * 128 + 64 + AbsoluteDistance);
 393 }
 394
 395 ATTRIBUTE_NO_SANITIZE_MEMORY
 396 static size_t InternalStrnlen(const char *S, size_t MaxLen) {
 397   size_t Len = 0;
 398   for (; Len < MaxLen && S[Len]; Len++) {}
 399   return Len;
 400 }
 401
 402 // Finds min of (strlen(S1), strlen(S2)).
 403 // Needed because one of these strings may actually be non-zero terminated.
 404 ATTRIBUTE_NO_SANITIZE_MEMORY
 405 static size_t InternalStrnlen2(const char *S1, const char *S2) {
 406   size_t Len = 0;
 407   for (; S1[Len] && S2[Len]; Len++)  {}
 408   return Len;
 409 }
 410
 411 void TracePC::ClearInlineCounters() {
 412   IterateCounterRegions([](const Module::Region &R){
 413     if (R.Enabled)
 414       memset(R.Start, 0, R.Stop - R.Start);
 415   });
 416 }
 417
 418 ATTRIBUTE_NO_SANITIZE_ALL
 419 void TracePC::RecordInitialStack() {
 420   int stack;
 421   __sancov_lowest_stack = InitialStack = reinterpret_cast<uintptr_t>(&stack);
 422 }
 423
 424 uintptr_t TracePC::GetMaxStackOffset() const {
 425   return InitialStack - __sancov_lowest_stack;  // Stack grows down
 426 }
 427
 428 void WarnAboutDeprecatedInstrumentation(const char *flag) {
 429   // Use RawPrint because Printf cannot be used on Windows before OutputFile is
 430   // initialized.
 431   RawPrint(flag);
 432   RawPrint(
 433       " is no longer supported by libFuzzer.\n"
 434       "Please either migrate to a compiler that supports -fsanitize=fuzzer\n"
 435       "or use an older version of libFuzzer\n");
 436   exit(1);
 437 }
 438
 439 } // namespace fuzzer
 440
 441 extern "C" {
 442 ATTRIBUTE_INTERFACE
 443 ATTRIBUTE_NO_SANITIZE_ALL
 444 void __sanitizer_cov_trace_pc_guard(uint32_t *Guard) {
 445   fuzzer::WarnAboutDeprecatedInstrumentation(
 446       "-fsanitize-coverage=trace-pc-guard");
 447 }
 448
 449 // Best-effort support for -fsanitize-coverage=trace-pc, which is available
 450 // in both Clang and GCC.
 451 ATTRIBUTE_INTERFACE
 452 ATTRIBUTE_NO_SANITIZE_ALL
 453 void __sanitizer_cov_trace_pc() {
 454   fuzzer::WarnAboutDeprecatedInstrumentation("-fsanitize-coverage=trace-pc");
 455 }
 456
 457 ATTRIBUTE_INTERFACE
 458 void __sanitizer_cov_trace_pc_guard_init(uint32_t *Start, uint32_t *Stop) {
 459   fuzzer::WarnAboutDeprecatedInstrumentation(
 460       "-fsanitize-coverage=trace-pc-guard");
 461 }
 462
 463 ATTRIBUTE_INTERFACE
 464 void __sanitizer_cov_8bit_counters_init(uint8_t *Start, uint8_t *Stop) {
 465   fuzzer::TPC.HandleInline8bitCountersInit(Start, Stop);
 466 }
 467
 468 ATTRIBUTE_INTERFACE
 469 void __sanitizer_cov_pcs_init(const uintptr_t *pcs_beg,
 470                               const uintptr_t *pcs_end) {
 471   fuzzer::TPC.HandlePCsInit(pcs_beg, pcs_end);
 472 }
 473
 474 ATTRIBUTE_INTERFACE
 475 ATTRIBUTE_NO_SANITIZE_ALL
 476 void __sanitizer_cov_trace_pc_indir(uintptr_t Callee) {
 477   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 478   fuzzer::TPC.HandleCallerCallee(PC, Callee);
 479 }
 480
 481 ATTRIBUTE_INTERFACE
 482 ATTRIBUTE_NO_SANITIZE_ALL
 483 ATTRIBUTE_TARGET_POPCNT
 484 void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2) {
 485   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 486   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 487 }
 488
 489 ATTRIBUTE_INTERFACE
 490 ATTRIBUTE_NO_SANITIZE_ALL
 491 ATTRIBUTE_TARGET_POPCNT
 492 // Now the __sanitizer_cov_trace_const_cmp[1248] callbacks just mimic
 493 // the behaviour of __sanitizer_cov_trace_cmp[1248] ones. This, however,
 494 // should be changed later to make full use of instrumentation.
 495 void __sanitizer_cov_trace_const_cmp8(uint64_t Arg1, uint64_t Arg2) {
 496   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 497   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 498 }
 499
 500 ATTRIBUTE_INTERFACE
 501 ATTRIBUTE_NO_SANITIZE_ALL
 502 ATTRIBUTE_TARGET_POPCNT
 503 void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2) {
 504   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 505   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 506 }
 507
 508 ATTRIBUTE_INTERFACE
 509 ATTRIBUTE_NO_SANITIZE_ALL
 510 ATTRIBUTE_TARGET_POPCNT
 511 void __sanitizer_cov_trace_const_cmp4(uint32_t Arg1, uint32_t Arg2) {
 512   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 513   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 514 }
 515
 516 ATTRIBUTE_INTERFACE
 517 ATTRIBUTE_NO_SANITIZE_ALL
 518 ATTRIBUTE_TARGET_POPCNT
 519 void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2) {
 520   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 521   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 522 }
 523
 524 ATTRIBUTE_INTERFACE
 525 ATTRIBUTE_NO_SANITIZE_ALL
 526 ATTRIBUTE_TARGET_POPCNT
 527 void __sanitizer_cov_trace_const_cmp2(uint16_t Arg1, uint16_t Arg2) {
 528   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 529   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 530 }
 531
 532 ATTRIBUTE_INTERFACE
 533 ATTRIBUTE_NO_SANITIZE_ALL
 534 ATTRIBUTE_TARGET_POPCNT
 535 void __sanitizer_cov_trace_cmp1(uint8_t Arg1, uint8_t Arg2) {
 536   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 537   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 538 }
 539
 540 ATTRIBUTE_INTERFACE
 541 ATTRIBUTE_NO_SANITIZE_ALL
 542 ATTRIBUTE_TARGET_POPCNT
 543 void __sanitizer_cov_trace_const_cmp1(uint8_t Arg1, uint8_t Arg2) {
 544   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 545   fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
 546 }
 547
 548 ATTRIBUTE_INTERFACE
 549 ATTRIBUTE_NO_SANITIZE_ALL
 550 ATTRIBUTE_TARGET_POPCNT
 551 void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t *Cases) {
 552   uint64_t N = Cases[0];
 553   uint64_t ValSizeInBits = Cases[1];
 554   uint64_t *Vals = Cases + 2;
 555   // Skip the most common and the most boring case: all switch values are small.
 556   // We may want to skip this at compile-time, but it will make the
 557   // instrumentation less general.
 558   if (Vals[N - 1]  < 256)
 559     return;
 560   // Also skip small inputs values, they won't give good signal.
 561   if (Val < 256)
 562     return;
 563   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 564   size_t i;
 565   uint64_t Smaller = 0;
 566   uint64_t Larger = ~(uint64_t)0;
 567   // Find two switch values such that Smaller < Val < Larger.
 568   // Use 0 and 0xfff..f as the defaults.
 569   for (i = 0; i < N; i++) {
 570     if (Val < Vals[i]) {
 571       Larger = Vals[i];
 572       break;
 573     }
 574     if (Val > Vals[i]) Smaller = Vals[i];
 575   }
 576
 577   // Apply HandleCmp to {Val,Smaller} and {Val, Larger},
 578   // use i as the PC modifier for HandleCmp.
 579   if (ValSizeInBits == 16) {
 580     fuzzer::TPC.HandleCmp(PC + 2 * i, static_cast<uint16_t>(Val),
 581                           (uint16_t)(Smaller));
 582     fuzzer::TPC.HandleCmp(PC + 2 * i + 1, static_cast<uint16_t>(Val),
 583                           (uint16_t)(Larger));
 584   } else if (ValSizeInBits == 32) {
 585     fuzzer::TPC.HandleCmp(PC + 2 * i, static_cast<uint32_t>(Val),
 586                           (uint32_t)(Smaller));
 587     fuzzer::TPC.HandleCmp(PC + 2 * i + 1, static_cast<uint32_t>(Val),
 588                           (uint32_t)(Larger));
 589   } else {
 590     fuzzer::TPC.HandleCmp(PC + 2*i, Val, Smaller);
 591     fuzzer::TPC.HandleCmp(PC + 2*i + 1, Val, Larger);
 592   }
 593 }
 594
 595 ATTRIBUTE_INTERFACE
 596 ATTRIBUTE_NO_SANITIZE_ALL
 597 ATTRIBUTE_TARGET_POPCNT
 598 void __sanitizer_cov_trace_div4(uint32_t Val) {
 599   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 600   fuzzer::TPC.HandleCmp(PC, Val, (uint32_t)0);
 601 }
 602
 603 ATTRIBUTE_INTERFACE
 604 ATTRIBUTE_NO_SANITIZE_ALL
 605 ATTRIBUTE_TARGET_POPCNT
 606 void __sanitizer_cov_trace_div8(uint64_t Val) {
 607   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 608   fuzzer::TPC.HandleCmp(PC, Val, (uint64_t)0);
 609 }
 610
 611 ATTRIBUTE_INTERFACE
 612 ATTRIBUTE_NO_SANITIZE_ALL
 613 ATTRIBUTE_TARGET_POPCNT
 614 void __sanitizer_cov_trace_gep(uintptr_t Idx) {
 615   uintptr_t PC = reinterpret_cast<uintptr_t>(GET_CALLER_PC());
 616   fuzzer::TPC.HandleCmp(PC, Idx, (uintptr_t)0);
 617 }
 618
 619 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 620 void __sanitizer_weak_hook_memcmp(void *caller_pc, const void *s1,
 621                                   const void *s2, size_t n, int result) {
 622   if (!fuzzer::RunningUserCallback) return;
 623   if (result == 0) return;  // No reason to mutate.
 624   if (n <= 1) return;  // Not interesting.
 625   fuzzer::TPC.AddValueForMemcmp(caller_pc, s1, s2, n, /*StopAtZero*/false);
 626 }
 627
 628 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 629 void __sanitizer_weak_hook_strncmp(void *caller_pc, const char *s1,
 630                                    const char *s2, size_t n, int result) {
 631   if (!fuzzer::RunningUserCallback) return;
 632   if (result == 0) return;  // No reason to mutate.
 633   size_t Len1 = fuzzer::InternalStrnlen(s1, n);
 634   size_t Len2 = fuzzer::InternalStrnlen(s2, n);
 635   n = std::min(n, Len1);
 636   n = std::min(n, Len2);
 637   if (n <= 1) return;  // Not interesting.
 638   fuzzer::TPC.AddValueForMemcmp(caller_pc, s1, s2, n, /*StopAtZero*/true);
 639 }
 640
 641 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 642 void __sanitizer_weak_hook_strcmp(void *caller_pc, const char *s1,
 643                                    const char *s2, int result) {
 644   if (!fuzzer::RunningUserCallback) return;
 645   if (result == 0) return;  // No reason to mutate.
 646   size_t N = fuzzer::InternalStrnlen2(s1, s2);
 647   if (N <= 1) return;  // Not interesting.
 648   fuzzer::TPC.AddValueForMemcmp(caller_pc, s1, s2, N, /*StopAtZero*/true);
 649 }
 650
 651 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 652 void __sanitizer_weak_hook_strncasecmp(void *called_pc, const char *s1,
 653                                        const char *s2, size_t n, int result) {
 654   if (!fuzzer::RunningUserCallback) return;
 655   return __sanitizer_weak_hook_strncmp(called_pc, s1, s2, n, result);
 656 }
 657
 658 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 659 void __sanitizer_weak_hook_strcasecmp(void *called_pc, const char *s1,
 660                                       const char *s2, int result) {
 661   if (!fuzzer::RunningUserCallback) return;
 662   return __sanitizer_weak_hook_strcmp(called_pc, s1, s2, result);
 663 }
 664
 665 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 666 void __sanitizer_weak_hook_strstr(void *called_pc, const char *s1,
 667                                   const char *s2, char *result) {
 668   if (!fuzzer::RunningUserCallback) return;
 669   fuzzer::TPC.MMT.Add(reinterpret_cast<const uint8_t *>(s2), strlen(s2));
 670 }
 671
 672 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 673 void __sanitizer_weak_hook_strcasestr(void *called_pc, const char *s1,
 674                                       const char *s2, char *result) {
 675   if (!fuzzer::RunningUserCallback) return;
 676   fuzzer::TPC.MMT.Add(reinterpret_cast<const uint8_t *>(s2), strlen(s2));
 677 }
 678
 679 ATTRIBUTE_INTERFACE ATTRIBUTE_NO_SANITIZE_MEMORY
 680 void __sanitizer_weak_hook_memmem(void *called_pc, const void *s1, size_t len1,
 681                                   const void *s2, size_t len2, void *result) {
 682   if (!fuzzer::RunningUserCallback) return;
 683   fuzzer::TPC.MMT.Add(reinterpret_cast<const uint8_t *>(s2), len2);
 684 }
 685 }  // extern "C"