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afl-llvm-pass.so.cc
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afl-llvm-pass.so.cc
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/*
american fuzzy lop++ - LLVM-mode instrumentation pass
---------------------------------------------------
Written by Laszlo Szekeres <[email protected]>,
Adrian Herrera <[email protected]>,
Michal Zalewski
LLVM integration design comes from Laszlo Szekeres. C bits copied-and-pasted
from afl-as.c are Michal's fault.
NGRAM previous location coverage comes from Adrian Herrera.
Copyright 2015, 2016 Google Inc. All rights reserved.
Copyright 2019-2023 AFLplusplus Project. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at:
https://www.apache.org/licenses/LICENSE-2.0
This library is plugged into LLVM when invoking clang through afl-clang-fast.
It tells the compiler to add code roughly equivalent to the bits discussed
in ../afl-as.h.
*/
#define AFL_LLVM_PASS
#include "config.h"
#include "debug.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <list>
#include <string>
#include <fstream>
#include <sys/time.h>
#include "llvm/Config/llvm-config.h"
#if LLVM_VERSION_MAJOR == 3 && LLVM_VERSION_MINOR < 5
typedef long double max_align_t;
#endif
#include "llvm/Pass.h"
#if LLVM_VERSION_MAJOR >= 11 /* use new pass manager */
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/IR/PassManager.h"
#else
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#endif
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#if LLVM_VERSION_MAJOR >= 14 /* how about stable interfaces? */
#include "llvm/Passes/OptimizationLevel.h"
#endif
#if LLVM_VERSION_MAJOR >= 4 || \
(LLVM_VERSION_MAJOR == 3 && LLVM_VERSION_MINOR > 4)
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/CFG.h"
#else
#include "llvm/DebugInfo.h"
#include "llvm/Support/CFG.h"
#endif
#include "llvm/IR/IRBuilder.h"
#include "afl-llvm-common.h"
#include "llvm-alternative-coverage.h"
using namespace llvm;
namespace {
#if LLVM_VERSION_MAJOR >= 11 /* use new pass manager */
class AFLCoverage : public PassInfoMixin<AFLCoverage> {
public:
AFLCoverage() {
#else
class AFLCoverage : public ModulePass {
public:
static char ID;
AFLCoverage() : ModulePass(ID) {
#endif
initInstrumentList();
}
#if LLVM_VERSION_MAJOR >= 11 /* use new pass manager */
PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
#else
bool runOnModule(Module &M) override;
#endif
protected:
uint32_t ngram_size = 0;
uint32_t ctx_k = 0;
uint32_t map_size = MAP_SIZE;
uint32_t function_minimum_size = 1;
const char *ctx_str = NULL, *caller_str = NULL, *skip_nozero = NULL;
const char *use_threadsafe_counters = nullptr;
};
} // namespace
#if LLVM_VERSION_MAJOR >= 11 /* use new pass manager */
extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK
llvmGetPassPluginInfo() {
return {LLVM_PLUGIN_API_VERSION, "AFLCoverage", "v0.1",
/* lambda to insert our pass into the pass pipeline. */
[](PassBuilder &PB) {
#if 1
#if LLVM_VERSION_MAJOR <= 13
using OptimizationLevel = typename PassBuilder::OptimizationLevel;
#endif
PB.registerOptimizerLastEPCallback(
[](ModulePassManager &MPM, OptimizationLevel OL) {
MPM.addPass(AFLCoverage());
});
/* TODO LTO registration */
#else
using PipelineElement = typename PassBuilder::PipelineElement;
PB.registerPipelineParsingCallback([](StringRef Name,
ModulePassManager &MPM,
ArrayRef<PipelineElement>) {
if (Name == "AFLCoverage") {
MPM.addPass(AFLCoverage());
return true;
} else {
return false;
}
});
#endif
}};
}
#else
char AFLCoverage::ID = 0;
#endif
/* needed up to 3.9.0 */
#if LLVM_VERSION_MAJOR == 3 && \
(LLVM_VERSION_MINOR < 9 || \
(LLVM_VERSION_MINOR == 9 && LLVM_VERSION_PATCH < 1))
uint64_t PowerOf2Ceil(unsigned in) {
uint64_t in64 = in - 1;
in64 |= (in64 >> 1);
in64 |= (in64 >> 2);
in64 |= (in64 >> 4);
in64 |= (in64 >> 8);
in64 |= (in64 >> 16);
in64 |= (in64 >> 32);
return in64 + 1;
}
#endif
/* #if LLVM_VERSION_STRING >= "4.0.1" */
#if LLVM_VERSION_MAJOR >= 5 || \
(LLVM_VERSION_MAJOR == 4 && LLVM_VERSION_PATCH >= 1)
#define AFL_HAVE_VECTOR_INTRINSICS 1
#endif
#if LLVM_VERSION_MAJOR >= 11 /* use new pass manager */
PreservedAnalyses AFLCoverage::run(Module &M, ModuleAnalysisManager &MAM) {
#else
bool AFLCoverage::runOnModule(Module &M) {
#endif
LLVMContext &C = M.getContext();
IntegerType *Int8Ty = IntegerType::getInt8Ty(C);
IntegerType *Int32Ty = IntegerType::getInt32Ty(C);
#ifdef AFL_HAVE_VECTOR_INTRINSICS
IntegerType *IntLocTy =
IntegerType::getIntNTy(C, sizeof(PREV_LOC_T) * CHAR_BIT);
#endif
struct timeval tv;
struct timezone tz;
u32 rand_seed;
unsigned int cur_loc = 0;
#if LLVM_VERSION_MAJOR >= 11 /* use new pass manager */
auto PA = PreservedAnalyses::all();
#endif
/* Setup random() so we get Actually Random(TM) outputs from AFL_R() */
gettimeofday(&tv, &tz);
rand_seed = tv.tv_sec ^ tv.tv_usec ^ getpid();
AFL_SR(rand_seed);
/* Show a banner */
setvbuf(stdout, NULL, _IONBF, 0);
if (getenv("AFL_DEBUG")) debug = 1;
if ((isatty(2) && !getenv("AFL_QUIET")) || getenv("AFL_DEBUG") != NULL) {
SAYF(cCYA "afl-llvm-pass" VERSION cRST
" by <[email protected]> and <[email protected]>\n");
} else
be_quiet = 1;
/*
char *ptr;
if ((ptr = getenv("AFL_MAP_SIZE")) || (ptr = getenv("AFL_MAPSIZE"))) {
map_size = atoi(ptr);
if (map_size < 8 || map_size > (1 << 29))
FATAL("illegal AFL_MAP_SIZE %u, must be between 2^3 and 2^30",
map_size); if (map_size % 8) map_size = (((map_size >> 3) + 1) << 3);
}
*/
/* Decide instrumentation ratio */
char *inst_ratio_str = getenv("AFL_INST_RATIO");
unsigned int inst_ratio = 100;
if (inst_ratio_str) {
if (sscanf(inst_ratio_str, "%u", &inst_ratio) != 1 || !inst_ratio ||
inst_ratio > 100)
FATAL("Bad value of AFL_INST_RATIO (must be between 1 and 100)");
}
#if LLVM_VERSION_MAJOR < 9
char *neverZero_counters_str = getenv("AFL_LLVM_NOT_ZERO");
#endif
skip_nozero = getenv("AFL_LLVM_SKIP_NEVERZERO");
use_threadsafe_counters = getenv("AFL_LLVM_THREADSAFE_INST");
if ((isatty(2) && !getenv("AFL_QUIET")) || !!getenv("AFL_DEBUG")) {
if (use_threadsafe_counters) {
// disabled unless there is support for other modules as well
// (increases documentation complexity)
/* if (!getenv("AFL_LLVM_NOT_ZERO")) { */
skip_nozero = "1";
SAYF(cCYA "afl-llvm-pass" VERSION cRST " using thread safe counters\n");
/*
} else {
SAYF(cCYA "afl-llvm-pass" VERSION cRST
" using thread safe not-zero-counters\n");
}
*/
} else {
SAYF(cCYA "afl-llvm-pass" VERSION cRST
" using non-thread safe instrumentation\n");
}
}
unsigned PrevLocSize = 0;
unsigned PrevCallerSize = 0;
char *ngram_size_str = getenv("AFL_LLVM_NGRAM_SIZE");
if (!ngram_size_str) ngram_size_str = getenv("AFL_NGRAM_SIZE");
char *ctx_k_str = getenv("AFL_LLVM_CTX_K");
if (!ctx_k_str) ctx_k_str = getenv("AFL_CTX_K");
ctx_str = getenv("AFL_LLVM_CTX");
caller_str = getenv("AFL_LLVM_CALLER");
bool instrument_ctx = ctx_str || caller_str;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
/* Decide previous location vector size (must be a power of two) */
VectorType *PrevLocTy = NULL;
if (ngram_size_str)
if (sscanf(ngram_size_str, "%u", &ngram_size) != 1 || ngram_size < 2 ||
ngram_size > NGRAM_SIZE_MAX)
FATAL(
"Bad value of AFL_NGRAM_SIZE (must be between 2 and NGRAM_SIZE_MAX "
"(%u))",
NGRAM_SIZE_MAX);
if (ngram_size == 1) ngram_size = 0;
if (ngram_size)
PrevLocSize = ngram_size - 1;
else
PrevLocSize = 1;
/* Decide K-ctx vector size (must be a power of two) */
VectorType *PrevCallerTy = NULL;
if (ctx_k_str)
if (sscanf(ctx_k_str, "%u", &ctx_k) != 1 || ctx_k < 1 || ctx_k > CTX_MAX_K)
FATAL("Bad value of AFL_CTX_K (must be between 1 and CTX_MAX_K (%u))",
CTX_MAX_K);
if (ctx_k == 1) {
ctx_k = 0;
instrument_ctx = true;
caller_str = ctx_k_str; // Enable CALLER instead
}
if (ctx_k) {
PrevCallerSize = ctx_k;
instrument_ctx = true;
}
#else
if (ngram_size_str)
#ifndef LLVM_VERSION_PATCH
FATAL(
"Sorry, NGRAM branch coverage is not supported with llvm version "
"%d.%d.%d!",
LLVM_VERSION_MAJOR, LLVM_VERSION_MINOR, 0);
#else
FATAL(
"Sorry, NGRAM branch coverage is not supported with llvm version "
"%d.%d.%d!",
LLVM_VERSION_MAJOR, LLVM_VERSION_MINOR, LLVM_VERSION_PATCH);
#endif
if (ctx_k_str)
#ifndef LLVM_VERSION_PATCH
FATAL(
"Sorry, K-CTX branch coverage is not supported with llvm version "
"%d.%d.%d!",
LLVM_VERSION_MAJOR, LLVM_VERSION_MINOR, 0);
#else
FATAL(
"Sorry, K-CTX branch coverage is not supported with llvm version "
"%d.%d.%d!",
LLVM_VERSION_MAJOR, LLVM_VERSION_MINOR, LLVM_VERSION_PATCH);
#endif
PrevLocSize = 1;
#endif
#ifdef AFL_HAVE_VECTOR_INTRINSICS
int PrevLocVecSize = PowerOf2Ceil(PrevLocSize);
if (ngram_size)
PrevLocTy = VectorType::get(IntLocTy, PrevLocVecSize
#if LLVM_VERSION_MAJOR >= 12
,
false
#endif
);
#endif
#ifdef AFL_HAVE_VECTOR_INTRINSICS
int PrevCallerVecSize = PowerOf2Ceil(PrevCallerSize);
if (ctx_k)
PrevCallerTy = VectorType::get(IntLocTy, PrevCallerVecSize
#if LLVM_VERSION_MAJOR >= 12
,
false
#endif
);
#endif
/* Get globals for the SHM region and the previous location. Note that
__afl_prev_loc is thread-local. */
GlobalVariable *AFLMapPtr =
new GlobalVariable(M, PointerType::get(Int8Ty, 0), false,
GlobalValue::ExternalLinkage, 0, "__afl_area_ptr");
GlobalVariable *AFLPrevLoc;
GlobalVariable *AFLPrevCaller;
GlobalVariable *AFLContext = NULL;
if (ctx_str || caller_str)
#if defined(__ANDROID__) || defined(__HAIKU__) || defined(NO_TLS)
AFLContext = new GlobalVariable(
M, Int32Ty, false, GlobalValue::ExternalLinkage, 0, "__afl_prev_ctx");
#else
AFLContext = new GlobalVariable(
M, Int32Ty, false, GlobalValue::ExternalLinkage, 0, "__afl_prev_ctx", 0,
GlobalVariable::GeneralDynamicTLSModel, 0, false);
#endif
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ngram_size)
#if defined(__ANDROID__) || defined(__HAIKU__) || defined(NO_TLS)
AFLPrevLoc = new GlobalVariable(
M, PrevLocTy, /* isConstant */ false, GlobalValue::ExternalLinkage,
/* Initializer */ nullptr, "__afl_prev_loc");
#else
AFLPrevLoc = new GlobalVariable(
M, PrevLocTy, /* isConstant */ false, GlobalValue::ExternalLinkage,
/* Initializer */ nullptr, "__afl_prev_loc",
/* InsertBefore */ nullptr, GlobalVariable::GeneralDynamicTLSModel,
/* AddressSpace */ 0, /* IsExternallyInitialized */ false);
#endif
else
#endif
#if defined(__ANDROID__) || defined(__HAIKU__) || defined(NO_TLS)
AFLPrevLoc = new GlobalVariable(
M, Int32Ty, false, GlobalValue::ExternalLinkage, 0, "__afl_prev_loc");
#else
AFLPrevLoc = new GlobalVariable(
M, Int32Ty, false, GlobalValue::ExternalLinkage, 0, "__afl_prev_loc", 0,
GlobalVariable::GeneralDynamicTLSModel, 0, false);
#endif
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ctx_k)
#if defined(__ANDROID__) || defined(__HAIKU__) || defined(NO_TLS)
AFLPrevCaller = new GlobalVariable(
M, PrevCallerTy, /* isConstant */ false, GlobalValue::ExternalLinkage,
/* Initializer */ nullptr, "__afl_prev_caller");
#else
AFLPrevCaller = new GlobalVariable(
M, PrevCallerTy, /* isConstant */ false, GlobalValue::ExternalLinkage,
/* Initializer */ nullptr, "__afl_prev_caller",
/* InsertBefore */ nullptr, GlobalVariable::GeneralDynamicTLSModel,
/* AddressSpace */ 0, /* IsExternallyInitialized */ false);
#endif
else
#endif
#if defined(__ANDROID__) || defined(__HAIKU__) || defined(NO_TLS)
AFLPrevCaller =
new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage, 0,
"__afl_prev_caller");
#else
AFLPrevCaller = new GlobalVariable(
M, Int32Ty, false, GlobalValue::ExternalLinkage, 0, "__afl_prev_caller",
0, GlobalVariable::GeneralDynamicTLSModel, 0, false);
#endif
#ifdef AFL_HAVE_VECTOR_INTRINSICS
/* Create the vector shuffle mask for updating the previous block history.
Note that the first element of the vector will store cur_loc, so just set
it to undef to allow the optimizer to do its thing. */
SmallVector<Constant *, 32> PrevLocShuffle = {UndefValue::get(Int32Ty)};
for (unsigned I = 0; I < PrevLocSize - 1; ++I)
PrevLocShuffle.push_back(ConstantInt::get(Int32Ty, I));
for (int I = PrevLocSize; I < PrevLocVecSize; ++I)
PrevLocShuffle.push_back(ConstantInt::get(Int32Ty, PrevLocSize));
Constant *PrevLocShuffleMask = ConstantVector::get(PrevLocShuffle);
Constant *PrevCallerShuffleMask = NULL;
SmallVector<Constant *, 32> PrevCallerShuffle = {UndefValue::get(Int32Ty)};
if (ctx_k) {
for (unsigned I = 0; I < PrevCallerSize - 1; ++I)
PrevCallerShuffle.push_back(ConstantInt::get(Int32Ty, I));
for (int I = PrevCallerSize; I < PrevCallerVecSize; ++I)
PrevCallerShuffle.push_back(ConstantInt::get(Int32Ty, PrevCallerSize));
PrevCallerShuffleMask = ConstantVector::get(PrevCallerShuffle);
}
#endif
// other constants we need
ConstantInt *One = ConstantInt::get(Int8Ty, 1);
Value *PrevCtx = NULL; // CTX sensitive coverage
LoadInst *PrevCaller = NULL; // K-CTX coverage
/* Instrument all the things! */
int inst_blocks = 0;
scanForDangerousFunctions(&M);
for (auto &F : M) {
int has_calls = 0;
if (debug)
fprintf(stderr, "FUNCTION: %s (%zu)\n", F.getName().str().c_str(),
F.size());
if (!isInInstrumentList(&F, MNAME)) { continue; }
if (F.size() < function_minimum_size) { continue; }
std::list<Value *> todo;
for (auto &BB : F) {
BasicBlock::iterator IP = BB.getFirstInsertionPt();
IRBuilder<> IRB(&(*IP));
// Context sensitive coverage
if (instrument_ctx && &BB == &F.getEntryBlock()) {
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ctx_k) {
PrevCaller = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
PrevCallerTy,
#endif
AFLPrevCaller);
PrevCaller->setMetadata(M.getMDKindID("nosanitize"),
MDNode::get(C, None));
PrevCtx =
IRB.CreateZExt(IRB.CreateXorReduce(PrevCaller), IRB.getInt32Ty());
} else
#endif
{
// load the context ID of the previous function and write to to a
// local variable on the stack
LoadInst *PrevCtxLoad = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
IRB.getInt32Ty(),
#endif
AFLContext);
PrevCtxLoad->setMetadata(M.getMDKindID("nosanitize"),
MDNode::get(C, None));
PrevCtx = PrevCtxLoad;
}
// does the function have calls? and is any of the calls larger than one
// basic block?
for (auto &BB_2 : F) {
if (has_calls) break;
for (auto &IN : BB_2) {
CallInst *callInst = nullptr;
if ((callInst = dyn_cast<CallInst>(&IN))) {
Function *Callee = callInst->getCalledFunction();
if (!Callee || Callee->size() < function_minimum_size)
continue;
else {
has_calls = 1;
break;
}
}
}
}
// if yes we store a context ID for this function in the global var
if (has_calls) {
Value *NewCtx = ConstantInt::get(Int32Ty, AFL_R(map_size));
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ctx_k) {
Value *ShuffledPrevCaller = IRB.CreateShuffleVector(
PrevCaller, UndefValue::get(PrevCallerTy),
PrevCallerShuffleMask);
Value *UpdatedPrevCaller = IRB.CreateInsertElement(
ShuffledPrevCaller, NewCtx, (uint64_t)0);
StoreInst *Store =
IRB.CreateStore(UpdatedPrevCaller, AFLPrevCaller);
Store->setMetadata(M.getMDKindID("nosanitize"),
MDNode::get(C, None));
} else
#endif
{
if (ctx_str) NewCtx = IRB.CreateXor(PrevCtx, NewCtx);
StoreInst *StoreCtx = IRB.CreateStore(NewCtx, AFLContext);
StoreCtx->setMetadata(M.getMDKindID("nosanitize"),
MDNode::get(C, None));
}
}
}
if (AFL_R(100) >= inst_ratio) continue;
/* Make up cur_loc */
// cur_loc++;
cur_loc = AFL_R(map_size);
/* There is a problem with Ubuntu 18.04 and llvm 6.0 (see issue #63).
The inline function successors() is not inlined and also not found at runtime
:-( As I am unable to detect Ubuntu18.04 heree, the next best thing is to
disable this optional optimization for LLVM 6.0.0 and Linux */
#if !(LLVM_VERSION_MAJOR == 6 && LLVM_VERSION_MINOR == 0) || !defined __linux__
// only instrument if this basic block is the destination of a previous
// basic block that has multiple successors
// this gets rid of ~5-10% of instrumentations that are unnecessary
// result: a little more speed and less map pollution
int more_than_one = -1;
// fprintf(stderr, "BB %u: ", cur_loc);
for (pred_iterator PI = pred_begin(&BB), E = pred_end(&BB); PI != E;
++PI) {
BasicBlock *Pred = *PI;
int count = 0;
if (more_than_one == -1) more_than_one = 0;
// fprintf(stderr, " %p=>", Pred);
for (succ_iterator SI = succ_begin(Pred), E = succ_end(Pred); SI != E;
++SI) {
BasicBlock *Succ = *SI;
// if (count > 0)
// fprintf(stderr, "|");
if (Succ != NULL) count++;
// fprintf(stderr, "%p", Succ);
}
if (count > 1) more_than_one = 1;
}
// fprintf(stderr, " == %d\n", more_than_one);
if (F.size() > 1 && more_than_one != 1) {
// in CTX mode we have to restore the original context for the caller -
// she might be calling other functions which need the correct CTX
if (instrument_ctx && has_calls) {
Instruction *Inst = BB.getTerminator();
if (isa<ReturnInst>(Inst) || isa<ResumeInst>(Inst)) {
IRBuilder<> Post_IRB(Inst);
StoreInst *RestoreCtx;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ctx_k)
RestoreCtx = IRB.CreateStore(PrevCaller, AFLPrevCaller);
else
#endif
RestoreCtx = Post_IRB.CreateStore(PrevCtx, AFLContext);
RestoreCtx->setMetadata(M.getMDKindID("nosanitize"),
MDNode::get(C, None));
}
}
continue;
}
#endif
ConstantInt *CurLoc;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ngram_size)
CurLoc = ConstantInt::get(IntLocTy, cur_loc);
else
#endif
CurLoc = ConstantInt::get(Int32Ty, cur_loc);
/* Load prev_loc */
LoadInst *PrevLoc;
if (ngram_size) {
PrevLoc = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
PrevLocTy,
#endif
AFLPrevLoc);
} else {
PrevLoc = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
IRB.getInt32Ty(),
#endif
AFLPrevLoc);
}
PrevLoc->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
Value *PrevLocTrans;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
/* "For efficiency, we propose to hash the tuple as a key into the
hit_count map as (prev_block_trans << 1) ^ curr_block_trans, where
prev_block_trans = (block_trans_1 ^ ... ^ block_trans_(n-1)" */
if (ngram_size)
PrevLocTrans =
IRB.CreateZExt(IRB.CreateXorReduce(PrevLoc), IRB.getInt32Ty());
else
#endif
PrevLocTrans = PrevLoc;
if (instrument_ctx)
PrevLocTrans =
IRB.CreateZExt(IRB.CreateXor(PrevLocTrans, PrevCtx), Int32Ty);
else
PrevLocTrans = IRB.CreateZExt(PrevLocTrans, IRB.getInt32Ty());
/* Load SHM pointer */
LoadInst *MapPtr = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
PointerType::get(Int8Ty, 0),
#endif
AFLMapPtr);
MapPtr->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
Value *MapPtrIdx;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ngram_size)
MapPtrIdx = IRB.CreateGEP(
Int8Ty, MapPtr,
IRB.CreateZExt(
IRB.CreateXor(PrevLocTrans, IRB.CreateZExt(CurLoc, Int32Ty)),
Int32Ty));
else
#endif
MapPtrIdx = IRB.CreateGEP(
#if LLVM_VERSION_MAJOR >= 14
Int8Ty,
#endif
MapPtr, IRB.CreateXor(PrevLocTrans, CurLoc));
/* Update bitmap */
if (use_threadsafe_counters) { /* Atomic */
IRB.CreateAtomicRMW(llvm::AtomicRMWInst::BinOp::Add, MapPtrIdx, One,
#if LLVM_VERSION_MAJOR >= 13
llvm::MaybeAlign(1),
#endif
llvm::AtomicOrdering::Monotonic);
/*
}
*/
} else {
LoadInst *Counter = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
IRB.getInt8Ty(),
#endif
MapPtrIdx);
Counter->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
Value *Incr = IRB.CreateAdd(Counter, One);
#if LLVM_VERSION_MAJOR >= 9
if (!skip_nozero) {
#else
if (neverZero_counters_str != NULL) {
#endif
/* hexcoder: Realize a counter that skips zero during overflow.
* Once this counter reaches its maximum value, it next increments to
* 1
*
* Instead of
* Counter + 1 -> Counter
* we inject now this
* Counter + 1 -> {Counter, OverflowFlag}
* Counter + OverflowFlag -> Counter
*/
ConstantInt *Zero = ConstantInt::get(Int8Ty, 0);
auto cf = IRB.CreateICmpEQ(Incr, Zero);
auto carry = IRB.CreateZExt(cf, Int8Ty);
Incr = IRB.CreateAdd(Incr, carry);
}
IRB.CreateStore(Incr, MapPtrIdx)
->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
} /* non atomic case */
/* Update prev_loc history vector (by placing cur_loc at the head of the
vector and shuffle the other elements back by one) */
StoreInst *Store;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ngram_size) {
Value *ShuffledPrevLoc = IRB.CreateShuffleVector(
PrevLoc, UndefValue::get(PrevLocTy), PrevLocShuffleMask);
Value *UpdatedPrevLoc = IRB.CreateInsertElement(
ShuffledPrevLoc, IRB.CreateLShr(CurLoc, (uint64_t)1), (uint64_t)0);
Store = IRB.CreateStore(UpdatedPrevLoc, AFLPrevLoc);
Store->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
} else
#endif
{
Store = IRB.CreateStore(ConstantInt::get(Int32Ty, cur_loc >> 1),
AFLPrevLoc);
Store->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
}
// in CTX mode we have to restore the original context for the caller -
// she might be calling other functions which need the correct CTX.
// Currently this is only needed for the Ubuntu clang-6.0 bug
if (instrument_ctx && has_calls) {
Instruction *Inst = BB.getTerminator();
if (isa<ReturnInst>(Inst) || isa<ResumeInst>(Inst)) {
IRBuilder<> Post_IRB(Inst);
StoreInst *RestoreCtx;
#ifdef AFL_HAVE_VECTOR_INTRINSICS
if (ctx_k)
RestoreCtx = IRB.CreateStore(PrevCaller, AFLPrevCaller);
else
#endif
RestoreCtx = Post_IRB.CreateStore(PrevCtx, AFLContext);
RestoreCtx->setMetadata(M.getMDKindID("nosanitize"),
MDNode::get(C, None));
}
}
inst_blocks++;
}
#if 0
if (use_threadsafe_counters) { /*Atomic NeverZero */
// handle the list of registered blocks to instrument
for (auto val : todo) {
/* hexcoder: Realize a thread-safe counter that skips zero during
* overflow. Once this counter reaches its maximum value, it next
* increments to 1
*
* Instead of
* Counter + 1 -> Counter
* we inject now this
* Counter + 1 -> {Counter, OverflowFlag}
* Counter + OverflowFlag -> Counter
*/
/* equivalent c code looks like this
* Thanks to
https://preshing.com/20150402/you-can-do-any-kind-of-atomic-read-modify-write-operation/
int old = atomic_load_explicit(&Counter, memory_order_relaxed);
int new;
do {
if (old == 255) {
new = 1;
} else {
new = old + 1;
}
} while (!atomic_compare_exchange_weak_explicit(&Counter, &old, new,
memory_order_relaxed, memory_order_relaxed));
*/
Value * MapPtrIdx = val;
Instruction * MapPtrIdxInst = cast<Instruction>(val);
BasicBlock::iterator it0(&(*MapPtrIdxInst));
++it0;
IRBuilder<> IRB(&(*it0));
// load the old counter value atomically
LoadInst *Counter = IRB.CreateLoad(
#if LLVM_VERSION_MAJOR >= 14
IRB.getInt8Ty(),
#endif
MapPtrIdx);
Counter->setAlignment(llvm::Align());
Counter->setAtomic(llvm::AtomicOrdering::Monotonic);
Counter->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
BasicBlock *BB = IRB.GetInsertBlock();
// insert a basic block with the corpus of a do while loop
// the calculation may need to repeat, if atomic compare_exchange is not
// successful
BasicBlock::iterator it(*Counter);
it++; // split after load counter
BasicBlock *end_bb = BB->splitBasicBlock(it);
end_bb->setName("injected");
// insert the block before the second half of the split
BasicBlock *do_while_bb =
BasicBlock::Create(C, "injected", end_bb->getParent(), end_bb);
// set terminator of BB from target end_bb to target do_while_bb
auto term = BB->getTerminator();
BranchInst::Create(do_while_bb, BB);
term->eraseFromParent();
// continue to fill instructions into the do_while loop
IRB.SetInsertPoint(do_while_bb, do_while_bb->getFirstInsertionPt());
PHINode *PN = IRB.CreatePHI(Int8Ty, 2);
// compare with maximum value 0xff
auto *Cmp = IRB.CreateICmpEQ(Counter, ConstantInt::get(Int8Ty, -1));
// increment the counter
Value *Incr = IRB.CreateAdd(Counter, One);
// select the counter value or 1
auto *Select = IRB.CreateSelect(Cmp, One, Incr);
// try to save back the new counter value
auto *CmpXchg = IRB.CreateAtomicCmpXchg(
MapPtrIdx, PN, Select, llvm::AtomicOrdering::Monotonic,
llvm::AtomicOrdering::Monotonic);
CmpXchg->setAlignment(llvm::Align());
CmpXchg->setWeak(true);
CmpXchg->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
// get the result of trying to update the Counter
Value *Success =
IRB.CreateExtractValue(CmpXchg, ArrayRef<unsigned>({1}));
// get the (possibly updated) value of Counter
Value *OldVal =
IRB.CreateExtractValue(CmpXchg, ArrayRef<unsigned>({0}));
// initially we use Counter
PN->addIncoming(Counter, BB);
// on retry, we use the updated value
PN->addIncoming(OldVal, do_while_bb);
// if the cmpXchg was not successful, retry