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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 "FuzzerTracePC.h"
#include "FuzzerCorpus.h"
#include "FuzzerDefs.h"
#include "FuzzerDictionary.h"
#include "FuzzerExtFunctions.h"
#include "FuzzerIO.h"
#include "FuzzerUtil.h"
#include "FuzzerValueBitMap.h"
#include <map>
#include <set>
#include <sstream>
// The coverage counters and PCs.
// These are declared as global variables named "__sancov_*" to simplify
// experiments with inlined instrumentation.
alignas(64) ATTRIBUTE_INTERFACE
uint8_t __sancov_trace_pc_guard_8bit_counters[fuzzer::TracePC::kNumPCs];
ATTRIBUTE_INTERFACE
uintptr_t __sancov_trace_pc_pcs[fuzzer::TracePC::kNumPCs];
namespace fuzzer {
TracePC TPC;
uint8_t *TracePC::Counters() const {
return __sancov_trace_pc_guard_8bit_counters;
}
uintptr_t *TracePC::PCs() const {
return __sancov_trace_pc_pcs;
}
size_t TracePC::GetTotalPCCoverage() {
size_t Res = 0;
for (size_t i = 1, N = GetNumPCs(); i < N; i++)
if (PCs()[i])
Res++;
return Res;
}
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++) {
NumGuards++;
if (NumGuards == kNumPCs) {
RawPrint(
"WARNING: The binary has too many instrumented PCs.\n"
" You may want to reduce the size of the binary\n"
" for more efficient fuzzing and precise coverage data\n");
}
*P = NumGuards % kNumPCs;
}
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");
}
ATTRIBUTE_NO_SANITIZE_ALL
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);
ValueProfileMap.AddValueModPrime(Idx);
}
void TracePC::InitializePrintNewPCs() {
if (!DoPrintNewPCs) return;
assert(!PrintedPCs);
PrintedPCs = new std::set<uintptr_t>;
for (size_t i = 1; i < GetNumPCs(); i++)
if (PCs()[i])
PrintedPCs->insert(PCs()[i]);
}
void TracePC::PrintNewPCs() {
if (!DoPrintNewPCs) return;
assert(PrintedPCs);
for (size_t i = 1; i < GetNumPCs(); i++)
if (PCs()[i] && PrintedPCs->insert(PCs()[i]).second)
PrintPC("\tNEW_PC: %p %F %L\n", "\tNEW_PC: %p\n", PCs()[i]);
}
void TracePC::PrintCoverage() {
if (!EF->__sanitizer_symbolize_pc ||
!EF->__sanitizer_get_module_and_offset_for_pc) {
Printf("INFO: __sanitizer_symbolize_pc or "
"__sanitizer_get_module_and_offset_for_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> CoveredDirs, CoveredFiles, CoveredFunctions,
CoveredLines;
Printf("COVERAGE:\n");
for (size_t i = 1; i < GetNumPCs(); i++) {
uintptr_t PC = PCs()[i];
if (!PC) continue;
std::string FileStr = DescribePC("%s", PC);
if (!IsInterestingCoverageFile(FileStr)) continue;
std::string FixedPCStr = DescribePC("%p", PC);
std::string FunctionStr = DescribePC("%F", PC);
std::string LineStr = DescribePC("%l", PC);
char ModulePathRaw[4096] = ""; // What's PATH_MAX in portable C++?
void *OffsetRaw = nullptr;
if (!EF->__sanitizer_get_module_and_offset_for_pc(
reinterpret_cast<void *>(PC), ModulePathRaw,
sizeof(ModulePathRaw), &OffsetRaw))
continue;
std::string Module = ModulePathRaw;
uintptr_t FixedPC = std::stoull(FixedPCStr, 0, 16);
uintptr_t PcOffset = reinterpret_cast<uintptr_t>(OffsetRaw);
ModuleOffsets[Module] = FixedPC - PcOffset;
CoveredPCsPerModule[Module].push_back(PcOffset);
CoveredFunctions.insert(FunctionStr);
CoveredFiles.insert(FileStr);
CoveredDirs.insert(DirName(FileStr));
if (!CoveredLines.insert(FileStr + ":" + LineStr).second)
continue;
Printf("COVERED: %s %s:%s\n", FunctionStr.c_str(),
FileStr.c_str(), LineStr.c_str());
}
std::string CoveredDirsStr;
for (auto &Dir : CoveredDirs) {
if (!CoveredDirsStr.empty())
CoveredDirsStr += ",";
CoveredDirsStr += Dir;
}
Printf("COVERED_DIRS: %s\n", CoveredDirsStr.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 = DisassembleCmd(ModuleName) + " | " +
SearchRegexCmd("call.*__sanitizer_cov_trace_pc_guard");
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')) {
size_t PcOffsetEnd = S.find(':');
if (PcOffsetEnd == std::string::npos)
continue;
S.resize(PcOffsetEnd);
uintptr_t PcOffset = std::stoull(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());
}
}
inline ALWAYS_INLINE uintptr_t GetPreviousInstructionPc(uintptr_t PC) {
// TODO: this implementation is x86 only.
// see sanitizer_common GetPreviousInstructionPc for full implementation.
return PC - 1;
}
void TracePC::DumpCoverage() {
if (EF->__sanitizer_dump_coverage) {
std::vector<uintptr_t> PCsCopy(GetNumPCs());
for (size_t i = 0; i < GetNumPCs(); i++)
PCsCopy[i] = PCs()[i] ? GetPreviousInstructionPc(PCs()[i]) : 0;
EF->__sanitizer_dump_coverage(PCsCopy.data(), PCsCopy.size());
}
}
// 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.
ATTRIBUTE_NO_SANITIZE_ALL
void TracePC::AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
size_t n, bool StopAtZero) {
if (!n) return;
size_t Len = std::min(n, Word::GetMaxSize());
const uint8_t *A1 = reinterpret_cast<const uint8_t *>(s1);
const uint8_t *A2 = reinterpret_cast<const uint8_t *>(s2);
uint8_t B1[Word::kMaxSize];
uint8_t B2[Word::kMaxSize];
// Copy the data into locals in this non-msan-instrumented function
// to avoid msan complaining further.
size_t Hash = 0; // Compute some simple hash of both strings.
for (size_t i = 0; i < Len; i++) {
B1[i] = A1[i];
B2[i] = A2[i];
size_t T = B1[i];
Hash ^= (T << 8) | B2[i];
}
size_t I = 0;
for (; I < Len; I++)
if (B1[I] != B2[I] || (StopAtZero && B1[I] == 0))
break;
size_t PC = reinterpret_cast<size_t>(caller_pc);
size_t Idx = (PC & 4095) | (I << 12);
ValueProfileMap.AddValue(Idx);
TORCW.Insert(Idx ^ Hash, Word(B1, Len), Word(B2, Len));
}
template <class T>
ATTRIBUTE_TARGET_POPCNT ALWAYS_INLINE
ATTRIBUTE_NO_SANITIZE_ALL
void TracePC::HandleCmp(uintptr_t PC, T Arg1, T Arg2) {
uint64_t ArgXor = Arg1 ^ Arg2;
uint64_t ArgDistance = __builtin_popcountll(ArgXor) + 1; // [1,65]
uintptr_t Idx = ((PC & 4095) + 1) * ArgDistance;
if (sizeof(T) == 4)
TORC4.Insert(ArgXor, Arg1, Arg2);
else if (sizeof(T) == 8)
TORC8.Insert(ArgXor, Arg1, Arg2);
ValueProfileMap.AddValue(Idx);
}
} // namespace fuzzer
extern "C" {
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
void __sanitizer_cov_trace_pc_guard(uint32_t *Guard) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
uint32_t Idx = *Guard;
__sancov_trace_pc_pcs[Idx] = PC;
__sancov_trace_pc_guard_8bit_counters[Idx]++;
}
// Best-effort support for -fsanitize-coverage=trace-pc, which is available
// in both Clang and GCC.
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
void __sanitizer_cov_trace_pc() {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
uintptr_t Idx = PC & (((uintptr_t)1 << fuzzer::TracePC::kTracePcBits) - 1);
__sancov_trace_pc_pcs[Idx] = PC;
__sancov_trace_pc_guard_8bit_counters[Idx]++;
}
ATTRIBUTE_INTERFACE
void __sanitizer_cov_trace_pc_guard_init(uint32_t *Start, uint32_t *Stop) {
fuzzer::TPC.HandleInit(Start, Stop);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
void __sanitizer_cov_trace_pc_indir(uintptr_t Callee) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCallerCallee(PC, Callee);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_cmp8(uint64_t Arg1, uint64_t Arg2) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_cmp4(uint32_t Arg1, uint32_t Arg2) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_cmp2(uint16_t Arg1, uint16_t Arg2) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_cmp1(uint8_t Arg1, uint8_t Arg2) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Arg1, Arg2);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t *Cases) {
uint64_t N = Cases[0];
uint64_t ValSizeInBits = Cases[1];
uint64_t *Vals = Cases + 2;
// Skip the most common and the most boring case.
if (Vals[N - 1] < 256 && Val < 256)
return;
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
size_t i;
uint64_t Token = 0;
for (i = 0; i < N; i++) {
Token = Val ^ Vals[i];
if (Val < Vals[i])
break;
}
if (ValSizeInBits == 16)
fuzzer::TPC.HandleCmp(PC + i, static_cast<uint16_t>(Token), (uint16_t)(0));
else if (ValSizeInBits == 32)
fuzzer::TPC.HandleCmp(PC + i, static_cast<uint32_t>(Token), (uint32_t)(0));
else
fuzzer::TPC.HandleCmp(PC + i, Token, (uint64_t)(0));
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_div4(uint32_t Val) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Val, (uint32_t)0);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_div8(uint64_t Val) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Val, (uint64_t)0);
}
ATTRIBUTE_INTERFACE
ATTRIBUTE_NO_SANITIZE_ALL
ATTRIBUTE_TARGET_POPCNT
void __sanitizer_cov_trace_gep(uintptr_t Idx) {
uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
fuzzer::TPC.HandleCmp(PC, Idx, (uintptr_t)0);
}
} // extern "C"