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llvm-project/llvm/lib/Fuzzer/FuzzerTracePC.cpp

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//===- FuzzerTracePC.cpp - PC tracing--------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Trace PCs.
// This module implements __sanitizer_cov_trace_pc_guard[_init],
// the callback required for -fsanitize-coverage=trace-pc-guard instrumentation.
//
//===----------------------------------------------------------------------===//
#include <map>
#include <set>
#include <sstream>
#include "FuzzerCorpus.h"
#include "FuzzerDefs.h"
#include "FuzzerDictionary.h"
#include "FuzzerExtFunctions.h"
#include "FuzzerTracePC.h"
#include "FuzzerValueBitMap.h"
namespace fuzzer {
TracePC TPC;
void TracePC::HandleTrace(uint32_t *Guard, uintptr_t PC) {
uint32_t Idx = *Guard;
if (!Idx) return;
uint8_t *CounterPtr = &Counters[Idx % kNumCounters];
uint8_t Counter = *CounterPtr;
if (Counter == 0) {
if (!PCs[Idx % kNumPCs]) {
AddNewPCID(Idx);
TotalPCCoverage++;
PCs[Idx % kNumPCs] = PC;
}
}
if (UseCounters) {
if (Counter < 128)
*CounterPtr = Counter + 1;
else
*Guard = 0;
} else {
*CounterPtr = 1;
*Guard = 0;
}
}
void TracePC::HandleInit(uint32_t *Start, uint32_t *Stop) {
if (Start == Stop || *Start) return;
assert(NumModules < sizeof(Modules) / sizeof(Modules[0]));
for (uint32_t *P = Start; P < Stop; P++)
*P = ++NumGuards;
Modules[NumModules].Start = Start;
Modules[NumModules].Stop = Stop;
NumModules++;
}
void TracePC::PrintModuleInfo() {
Printf("INFO: Loaded %zd modules (%zd guards): ", NumModules, NumGuards);
for (size_t i = 0; i < NumModules; i++)
Printf("[%p, %p), ", Modules[i].Start, Modules[i].Stop);
Printf("\n");
}
void TracePC::ResetGuards() {
uint32_t N = 0;
for (size_t M = 0; M < NumModules; M++)
for (uint32_t *X = Modules[M].Start, *End = Modules[M].Stop; X < End; X++)
*X = ++N;
assert(N == NumGuards);
}
size_t TracePC::FinalizeTrace(InputCorpus *C, size_t InputSize, bool Shrink) {
if (!UsingTracePcGuard()) return 0;
size_t Res = 0;
const size_t Step = 8;
assert(reinterpret_cast<uintptr_t>(Counters) % Step == 0);
size_t N = Min(kNumCounters, NumGuards + 1);
N = (N + Step - 1) & ~(Step - 1); // Round up.
for (size_t Idx = 0; Idx < N; Idx += Step) {
uint64_t Bundle = *reinterpret_cast<uint64_t*>(&Counters[Idx]);
if (!Bundle) continue;
for (size_t i = Idx; i < Idx + Step; i++) {
uint8_t Counter = (Bundle >> (i * 8)) & 0xff;
if (!Counter) continue;
Counters[i] = 0;
unsigned Bit = 0;
/**/ if (Counter >= 128) Bit = 7;
else if (Counter >= 32) Bit = 6;
else if (Counter >= 16) Bit = 5;
else if (Counter >= 8) Bit = 4;
else if (Counter >= 4) Bit = 3;
else if (Counter >= 3) Bit = 2;
else if (Counter >= 2) Bit = 1;
size_t Feature = (i * 8 + Bit);
if (C->AddFeature(Feature, InputSize, Shrink))
Res++;
}
}
if (UseValueProfile)
ValueProfileMap.ForEach([&](size_t Idx) {
if (C->AddFeature(NumGuards + Idx, InputSize, Shrink))
Res++;
});
return Res;
}
void TracePC::HandleCallerCallee(uintptr_t Caller, uintptr_t Callee) {
const uintptr_t kBits = 12;
const uintptr_t kMask = (1 << kBits) - 1;
uintptr_t Idx = (Caller & kMask) | ((Callee & kMask) << kBits);
HandleValueProfile(Idx);
}
static bool IsInterestingCoverageFile(std::string &File) {
if (File.find("compiler-rt/lib/") != std::string::npos)
return false; // sanitizer internal.
if (File.find("/usr/lib/") != std::string::npos)
return false;
if (File.find("/usr/include/") != std::string::npos)
return false;
if (File == "<null>")
return false;
return true;
}
void TracePC::PrintCoverage() {
if (!EF->__sanitizer_symbolize_pc) {
Printf("INFO: __sanitizer_symbolize_pc is not available,"
" not printing coverage\n");
return;
}
std::map<std::string, std::vector<uintptr_t>> CoveredPCsPerModule;
std::map<std::string, uintptr_t> ModuleOffsets;
std::set<std::string> CoveredFiles, CoveredFunctions, CoveredLines;
Printf("COVERAGE:\n");
for (size_t i = 0; i < Min(NumGuards + 1, kNumPCs); i++) {
if (!PCs[i]) continue;
std::string FileStr = DescribePC("%s", PCs[i]);
if (!IsInterestingCoverageFile(FileStr)) continue;
std::string FixedPCStr = DescribePC("%p", PCs[i]);
std::string FunctionStr = DescribePC("%F", PCs[i]);
std::string LineStr = DescribePC("%l", PCs[i]);
// TODO(kcc): get the module using some other way since this
// does not work with ASAN_OPTIONS=strip_path_prefix=something.
std::string Module = DescribePC("%m", PCs[i]);
std::string OffsetStr = DescribePC("%o", PCs[i]);
uintptr_t FixedPC = std::stol(FixedPCStr, 0, 16);
uintptr_t PcOffset = std::stol(OffsetStr, 0, 16);
ModuleOffsets[Module] = FixedPC - PcOffset;
CoveredPCsPerModule[Module].push_back(PcOffset);
CoveredFunctions.insert(FunctionStr);
CoveredFiles.insert(FileStr);
if (!CoveredLines.insert(FileStr + ":" + LineStr).second)
continue;
Printf("COVERED: %s %s:%s\n", FunctionStr.c_str(),
FileStr.c_str(), LineStr.c_str());
}
for (auto &M : CoveredPCsPerModule) {
std::set<std::string> UncoveredFiles, UncoveredFunctions;
std::map<std::string, std::set<int> > UncoveredLines; // Func+File => lines
auto &ModuleName = M.first;
auto &CoveredOffsets = M.second;
uintptr_t ModuleOffset = ModuleOffsets[ModuleName];
std::sort(CoveredOffsets.begin(), CoveredOffsets.end());
Printf("MODULE_WITH_COVERAGE: %s\n", ModuleName.c_str());
// sancov does not yet fully support DSOs.
// std::string Cmd = "sancov -print-coverage-pcs " + ModuleName;
std::string Cmd = "objdump -d " + ModuleName +
" | grep 'call.*__sanitizer_cov_trace_pc_guard' | awk -F: '{print $1}'";
std::string SanCovOutput;
if (!ExecuteCommandAndReadOutput(Cmd, &SanCovOutput)) {
Printf("INFO: Command failed: %s\n", Cmd.c_str());
continue;
}
std::istringstream ISS(SanCovOutput);
std::string S;
while (std::getline(ISS, S, '\n')) {
uintptr_t PcOffset = std::stol(S, 0, 16);
if (!std::binary_search(CoveredOffsets.begin(), CoveredOffsets.end(),
PcOffset)) {
uintptr_t PC = ModuleOffset + PcOffset;
auto FileStr = DescribePC("%s", PC);
if (!IsInterestingCoverageFile(FileStr)) continue;
if (CoveredFiles.count(FileStr) == 0) {
UncoveredFiles.insert(FileStr);
continue;
}
auto FunctionStr = DescribePC("%F", PC);
if (CoveredFunctions.count(FunctionStr) == 0) {
UncoveredFunctions.insert(FunctionStr);
continue;
}
std::string LineStr = DescribePC("%l", PC);
uintptr_t Line = std::stoi(LineStr);
std::string FileLineStr = FileStr + ":" + LineStr;
if (CoveredLines.count(FileLineStr) == 0)
UncoveredLines[FunctionStr + " " + FileStr].insert(Line);
}
}
for (auto &FileLine: UncoveredLines)
for (int Line : FileLine.second)
Printf("UNCOVERED_LINE: %s:%d\n", FileLine.first.c_str(), Line);
for (auto &Func : UncoveredFunctions)
Printf("UNCOVERED_FUNC: %s\n", Func.c_str());
for (auto &File : UncoveredFiles)
Printf("UNCOVERED_FILE: %s\n", File.c_str());
}
}
// Value profile.
// We keep track of various values that affect control flow.
// These values are inserted into a bit-set-based hash map.
// Every new bit in the map is treated as a new coverage.
//
// For memcmp/strcmp/etc the interesting value is the length of the common
// prefix of the parameters.
// For cmp instructions the interesting value is a XOR of the parameters.
// The interesting value is mixed up with the PC and is then added to the map.
void TracePC::AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
size_t n) {
if (!n) return;
size_t Len = std::min(n, (size_t)32);
const uint8_t *A1 = reinterpret_cast<const uint8_t *>(s1);
const uint8_t *A2 = reinterpret_cast<const uint8_t *>(s2);
size_t I = 0;
for (; I < Len; I++)
if (A1[I] != A2[I])
break;
size_t PC = reinterpret_cast<size_t>(caller_pc);
size_t Idx = I;
// if (I < Len)
// Idx += __builtin_popcountl((A1[I] ^ A2[I])) - 1;
TPC.HandleValueProfile((PC & 4095) | (Idx << 12));
}
void TracePC::AddValueForStrcmp(void *caller_pc, const char *s1, const char *s2,
size_t n) {
if (!n) return;
size_t Len = std::min(n, (size_t)32);
const uint8_t *A1 = reinterpret_cast<const uint8_t *>(s1);
const uint8_t *A2 = reinterpret_cast<const uint8_t *>(s2);
size_t I = 0;
for (; I < Len; I++)
if (A1[I] != A2[I] || A1[I] == 0)
break;
size_t PC = reinterpret_cast<size_t>(caller_pc);
size_t Idx = I;
// if (I < Len && A1[I])
// Idx += __builtin_popcountl((A1[I] ^ A2[I])) - 1;
TPC.HandleValueProfile((PC & 4095) | (Idx << 12));
}
template <class T>
ATTRIBUTE_TARGET_POPCNT
#ifdef __clang__ // g++ can't handle this __attribute__ here :(
__attribute__((always_inline))
#endif // __clang__
void TracePC::HandleCmp(void *PC, T Arg1, T Arg2) {
uintptr_t PCuint = reinterpret_cast<uintptr_t>(PC);
uint64_t ArgXor = Arg1 ^ Arg2;
uint64_t ArgDistance = __builtin_popcountl(ArgXor) + 1; // [1,65]
uintptr_t Idx = ((PCuint & 4095) + 1) * ArgDistance;
TORCInsert(ArgXor, Arg1, Arg2);
HandleValueProfile(Idx);
}
void TracePC::ProcessTORC(Dictionary *Dict, const uint8_t *Data, size_t Size) {
TORCToDict(TORC8, Dict, Data, Size);
TORCToDict(TORC4, Dict, Data, Size);
}
template <class T>
void TracePC::TORCToDict(const TableOfRecentCompares<T, kTORCSize> &TORC,
Dictionary *Dict, const uint8_t *Data, size_t Size) {
ScopedDoingMyOwnMemmem scoped_doing_my_own_memmem;
for (size_t i = 0; i < TORC.kSize; i++) {
T A[2] = {TORC.Table[i][0], TORC.Table[i][1]};
if (!A[0] && !A[1]) continue;
for (int j = 0; j < 2; j++)
TORCToDict(Dict, A[j], A[!j], Data, Size);
}
}
template <class T>
void TracePC::TORCToDict(Dictionary *Dict, T FindInData, T Substitute,
const uint8_t *Data, size_t Size) {
if (FindInData == Substitute) return;
if (sizeof(T) == 4) {
uint16_t HigherBytes = Substitute >> sizeof(T) * 4;
if (HigherBytes == 0 || HigherBytes == 0xffff)
TORCToDict(Dict, static_cast<uint16_t>(FindInData),
static_cast<uint16_t>(Substitute), Data, Size);
}
const size_t DataSize = sizeof(T);
const uint8_t *End = Data + Size;
int Attempts = 3;
for (int DoSwap = 0; DoSwap <= 1; DoSwap++) {
for (const uint8_t *Cur = Data; Cur < End && Attempts--; Cur++) {
Cur = (uint8_t *)memmem(Cur, End - Cur, &FindInData, DataSize);
if (!Cur)
break;
size_t Pos = Cur - Data;
Word W(reinterpret_cast<uint8_t *>(&Substitute), sizeof(Substitute));
DictionaryEntry DE(W, Pos);
// TODO: evict all entries from Dic if it's full.
Dict->push_back(DE);
// Printf("Dict[%zd] TORC%zd %llx => %llx pos %zd\n", Dict->size(),
// sizeof(T),
// (uint64_t)FindInData, (uint64_t)Substitute, Pos);
}
FindInData = Bswap(FindInData);
Substitute = Bswap(Substitute);
}
}
} // namespace fuzzer
extern "C" {
__attribute__((visibility("default")))
void __sanitizer_cov_trace_pc_guard(uint32_t *Guard) {
uintptr_t PC = (uintptr_t)__builtin_return_address(0);
fuzzer::TPC.HandleTrace(Guard, PC);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_pc_guard_init(uint32_t *Start, uint32_t *Stop) {
fuzzer::TPC.HandleInit(Start, Stop);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_pc_indir(uintptr_t Callee) {
uintptr_t PC = (uintptr_t)__builtin_return_address(0);
fuzzer::TPC.HandleCallerCallee(PC, Callee);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Arg1, Arg2);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Arg1, Arg2);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Arg1, Arg2);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_cmp1(uint8_t Arg1, uint8_t Arg2) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Arg1, Arg2);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t *Cases) {
uint64_t N = Cases[0];
uint64_t *Vals = Cases + 2;
char *PC = (char*)__builtin_return_address(0);
for (size_t i = 0; i < N; i++)
if (Val != Vals[i])
fuzzer::TPC.HandleCmp(PC + i, Val, Vals[i]);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_div4(uint32_t Val) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Val, (uint32_t)0);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_div8(uint64_t Val) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Val, (uint64_t)0);
}
__attribute__((visibility("default")))
void __sanitizer_cov_trace_gep(uintptr_t Idx) {
fuzzer::TPC.HandleCmp(__builtin_return_address(0), Idx, (uintptr_t)0);
}
} // extern "C"
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