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292 lines
8.9 KiB
292 lines
8.9 KiB
//===- FuzzerTracePC.h - Internal header for the Fuzzer ---------*- C++ -* ===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// fuzzer::TracePC
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_FUZZER_TRACE_PC
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#define LLVM_FUZZER_TRACE_PC
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#include "FuzzerDefs.h"
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#include "FuzzerDictionary.h"
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#include "FuzzerValueBitMap.h"
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#include <set>
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#include <unordered_map>
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namespace fuzzer {
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// TableOfRecentCompares (TORC) remembers the most recently performed
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// comparisons of type T.
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// We record the arguments of CMP instructions in this table unconditionally
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// because it seems cheaper this way than to compute some expensive
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// conditions inside __sanitizer_cov_trace_cmp*.
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// After the unit has been executed we may decide to use the contents of
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// this table to populate a Dictionary.
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template<class T, size_t kSizeT>
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struct TableOfRecentCompares {
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static const size_t kSize = kSizeT;
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struct Pair {
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T A, B;
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};
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ATTRIBUTE_NO_SANITIZE_ALL
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void Insert(size_t Idx, const T &Arg1, const T &Arg2) {
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Idx = Idx % kSize;
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Table[Idx].A = Arg1;
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Table[Idx].B = Arg2;
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}
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Pair Get(size_t I) { return Table[I % kSize]; }
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Pair Table[kSize];
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};
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template <size_t kSizeT>
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struct MemMemTable {
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static const size_t kSize = kSizeT;
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Word MemMemWords[kSize];
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Word EmptyWord;
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void Add(const uint8_t *Data, size_t Size) {
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if (Size <= 2) return;
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Size = std::min(Size, Word::GetMaxSize());
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size_t Idx = SimpleFastHash(Data, Size) % kSize;
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MemMemWords[Idx].Set(Data, Size);
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}
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const Word &Get(size_t Idx) {
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for (size_t i = 0; i < kSize; i++) {
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const Word &W = MemMemWords[(Idx + i) % kSize];
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if (W.size()) return W;
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}
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EmptyWord.Set(nullptr, 0);
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return EmptyWord;
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}
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};
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class TracePC {
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public:
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void HandleInline8bitCountersInit(uint8_t *Start, uint8_t *Stop);
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void HandlePCsInit(const uintptr_t *Start, const uintptr_t *Stop);
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void HandleCallerCallee(uintptr_t Caller, uintptr_t Callee);
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template <class T> void HandleCmp(uintptr_t PC, T Arg1, T Arg2);
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size_t GetTotalPCCoverage();
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void SetUseCounters(bool UC) { UseCounters = UC; }
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void SetUseValueProfileMask(uint32_t VPMask) { UseValueProfileMask = VPMask; }
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void SetPrintNewPCs(bool P) { DoPrintNewPCs = P; }
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void SetPrintNewFuncs(size_t P) { NumPrintNewFuncs = P; }
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void UpdateObservedPCs();
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template <class Callback> void CollectFeatures(Callback CB) const;
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void ResetMaps() {
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ValueProfileMap.Reset();
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ClearExtraCounters();
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ClearInlineCounters();
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}
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void ClearInlineCounters();
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void UpdateFeatureSet(size_t CurrentElementIdx, size_t CurrentElementSize);
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void PrintFeatureSet();
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void PrintModuleInfo();
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void PrintCoverage(bool PrintAllCounters);
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template<class CallBack>
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void IterateCoveredFunctions(CallBack CB);
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void AddValueForMemcmp(void *caller_pc, const void *s1, const void *s2,
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size_t n, bool StopAtZero);
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TableOfRecentCompares<uint32_t, 32> TORC4;
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TableOfRecentCompares<uint64_t, 32> TORC8;
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TableOfRecentCompares<Word, 32> TORCW;
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MemMemTable<1024> MMT;
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void RecordInitialStack();
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uintptr_t GetMaxStackOffset() const;
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template<class CallBack>
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void ForEachObservedPC(CallBack CB) {
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for (auto PC : ObservedPCs)
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CB(PC);
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}
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void SetFocusFunction(const std::string &FuncName);
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bool ObservedFocusFunction();
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struct PCTableEntry {
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uintptr_t PC, PCFlags;
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};
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uintptr_t PCTableEntryIdx(const PCTableEntry *TE);
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const PCTableEntry *PCTableEntryByIdx(uintptr_t Idx);
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static uintptr_t GetNextInstructionPc(uintptr_t PC);
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bool PcIsFuncEntry(const PCTableEntry *TE) { return TE->PCFlags & 1; }
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private:
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bool UseCounters = false;
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uint32_t UseValueProfileMask = false;
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bool DoPrintNewPCs = false;
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size_t NumPrintNewFuncs = 0;
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// Module represents the array of 8-bit counters split into regions
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// such that every region, except maybe the first and the last one, is one
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// full page.
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struct Module {
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struct Region {
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uint8_t *Start, *Stop;
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bool Enabled;
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bool OneFullPage;
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};
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Region *Regions;
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size_t NumRegions;
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uint8_t *Start() { return Regions[0].Start; }
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uint8_t *Stop() { return Regions[NumRegions - 1].Stop; }
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size_t Size() { return Stop() - Start(); }
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size_t Idx(uint8_t *P) {
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assert(P >= Start() && P < Stop());
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return P - Start();
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}
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};
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Module Modules[4096];
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size_t NumModules; // linker-initialized.
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size_t NumInline8bitCounters;
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template <class Callback>
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void IterateCounterRegions(Callback CB) {
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for (size_t m = 0; m < NumModules; m++)
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for (size_t r = 0; r < Modules[m].NumRegions; r++)
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CB(Modules[m].Regions[r]);
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}
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struct { const PCTableEntry *Start, *Stop; } ModulePCTable[4096];
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size_t NumPCTables;
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size_t NumPCsInPCTables;
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Set<const PCTableEntry*> ObservedPCs;
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std::unordered_map<uintptr_t, uintptr_t> ObservedFuncs; // PC => Counter.
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uint8_t *FocusFunctionCounterPtr = nullptr;
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ValueBitMap ValueProfileMap;
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uintptr_t InitialStack;
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};
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template <class Callback>
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// void Callback(size_t FirstFeature, size_t Idx, uint8_t Value);
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ATTRIBUTE_NO_SANITIZE_ALL
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size_t ForEachNonZeroByte(const uint8_t *Begin, const uint8_t *End,
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size_t FirstFeature, Callback Handle8bitCounter) {
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typedef uintptr_t LargeType;
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const size_t Step = sizeof(LargeType) / sizeof(uint8_t);
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const size_t StepMask = Step - 1;
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auto P = Begin;
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// Iterate by 1 byte until either the alignment boundary or the end.
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for (; reinterpret_cast<uintptr_t>(P) & StepMask && P < End; P++)
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if (uint8_t V = *P)
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Handle8bitCounter(FirstFeature, P - Begin, V);
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// Iterate by Step bytes at a time.
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for (; P < End; P += Step)
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if (LargeType Bundle = *reinterpret_cast<const LargeType *>(P)) {
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Bundle = HostToLE(Bundle);
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for (size_t I = 0; I < Step; I++, Bundle >>= 8)
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if (uint8_t V = Bundle & 0xff)
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Handle8bitCounter(FirstFeature, P - Begin + I, V);
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}
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// Iterate by 1 byte until the end.
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for (; P < End; P++)
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if (uint8_t V = *P)
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Handle8bitCounter(FirstFeature, P - Begin, V);
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return End - Begin;
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}
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// Given a non-zero Counter returns a number in the range [0,7].
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template<class T>
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unsigned CounterToFeature(T Counter) {
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// Returns a feature number by placing Counters into buckets as illustrated
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// below.
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//
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// Counter bucket: [1] [2] [3] [4-7] [8-15] [16-31] [32-127] [128+]
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// Feature number: 0 1 2 3 4 5 6 7
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//
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// This is a heuristic taken from AFL (see
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// http://lcamtuf.coredump.cx/afl/technical_details.txt).
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//
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// This implementation may change in the future so clients should
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// not rely on it.
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assert(Counter);
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unsigned Bit = 0;
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/**/ if (Counter >= 128) Bit = 7;
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else if (Counter >= 32) Bit = 6;
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else if (Counter >= 16) Bit = 5;
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else if (Counter >= 8) Bit = 4;
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else if (Counter >= 4) Bit = 3;
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else if (Counter >= 3) Bit = 2;
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else if (Counter >= 2) Bit = 1;
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return Bit;
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}
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template <class Callback> // void Callback(size_t Feature)
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ATTRIBUTE_NO_SANITIZE_ADDRESS
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ATTRIBUTE_NOINLINE
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void TracePC::CollectFeatures(Callback HandleFeature) const {
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auto Handle8bitCounter = [&](size_t FirstFeature,
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size_t Idx, uint8_t Counter) {
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if (UseCounters)
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HandleFeature(FirstFeature + Idx * 8 + CounterToFeature(Counter));
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else
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HandleFeature(FirstFeature + Idx);
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};
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size_t FirstFeature = 0;
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for (size_t i = 0; i < NumModules; i++) {
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for (size_t r = 0; r < Modules[i].NumRegions; r++) {
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if (!Modules[i].Regions[r].Enabled) continue;
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FirstFeature += 8 * ForEachNonZeroByte(Modules[i].Regions[r].Start,
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Modules[i].Regions[r].Stop,
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FirstFeature, Handle8bitCounter);
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}
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}
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FirstFeature +=
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8 * ForEachNonZeroByte(ExtraCountersBegin(), ExtraCountersEnd(),
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FirstFeature, Handle8bitCounter);
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if (UseValueProfileMask) {
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ValueProfileMap.ForEach([&](size_t Idx) {
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HandleFeature(FirstFeature + Idx);
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});
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FirstFeature += ValueProfileMap.SizeInBits();
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}
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// Step function, grows similar to 8 * Log_2(A).
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auto StackDepthStepFunction = [](uint32_t A) -> uint32_t {
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if (!A) return A;
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uint32_t Log2 = Log(A);
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if (Log2 < 3) return A;
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Log2 -= 3;
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return (Log2 + 1) * 8 + ((A >> Log2) & 7);
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};
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assert(StackDepthStepFunction(1024) == 64);
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assert(StackDepthStepFunction(1024 * 4) == 80);
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assert(StackDepthStepFunction(1024 * 1024) == 144);
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if (auto MaxStackOffset = GetMaxStackOffset())
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HandleFeature(FirstFeature + StackDepthStepFunction(MaxStackOffset / 8));
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}
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extern TracePC TPC;
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} // namespace fuzzer
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#endif // LLVM_FUZZER_TRACE_PC
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