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final touches

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This commit is contained in:
van Hauser
2019-07-05 11:28:08 +02:00
parent 9199967022
commit 7f6aaa5314
5 changed files with 71 additions and 55 deletions
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89
llvm_mode/afl-llvm-pass.so.cc
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@ -118,7 +118,9 @@ bool AFLCoverage::runOnModule(Module &M) {
}
char* neverZero_counters_str = getenv("AFL_NZERO_COUNTS");
#if LLVM_VERSION_MAJOR < 9
char* neverZero_counters_str = getenv("AFL_LLVM_NOT_ZERO");
#endif
/* Get globals for the SHM region and the previous location. Note that
__afl_prev_loc is thread-local. */
@ -236,75 +238,56 @@ bool AFLCoverage::runOnModule(Module &M) {
LoadInst *Counter = IRB.CreateLoad(MapPtrIdx);
Counter->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
Value *Incr;
// if (neverZero_counters_str == NULL || neverZero_counters_str[0] != '4')
Incr = IRB.CreateAdd(Counter, ConstantInt::get(Int8Ty, 1));
Value *Incr = IRB.CreateAdd(Counter, ConstantInt::get(Int8Ty, 1));
if (neverZero_counters_str != NULL) {
/* 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
*/
// Solution #1 - creates
//mov ecx,edx
//add cl,0x1
//adc dl,0x1
/*
if (neverZero_counters_str[0] == '1') {
CallInst *AddOv = IRB.CreateBinaryIntrinsic(Intrinsic::uadd_with_overflow, Counter, ConstantInt::get(Int8Ty, 1));
AddOv->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
Value *SumWithOverflowBit = AddOv;
Incr = IRB.CreateAdd(IRB.CreateExtractValue(SumWithOverflowBit, 0), // sum
IRB.CreateZExt( // convert from one bit type to 8 bits type
IRB.CreateExtractValue(SumWithOverflowBit, 1), // overflow
Int8Ty));
// Solution #2 - creates the same code as #1
#if LLVM_VERSION_MAJOR < 9
if (neverZero_counters_str != NULL) { // with llvm 9 we make this the default as the bug in llvm is then fixed
#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
*/
/* // we keep the old solutions just in case
// Solution #1
if (neverZero_counters_str[0] == '1') {
CallInst *AddOv = IRB.CreateBinaryIntrinsic(Intrinsic::uadd_with_overflow, Counter, ConstantInt::get(Int8Ty, 1));
AddOv->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));
Value *SumWithOverflowBit = AddOv;
Incr = IRB.CreateAdd(IRB.CreateExtractValue(SumWithOverflowBit, 0), // sum
IRB.CreateZExt( // convert from one bit type to 8 bits type
IRB.CreateExtractValue(SumWithOverflowBit, 1), // overflow
Int8Ty));
// Solution #2
} else if (neverZero_counters_str[0] == '2') {
auto cf = IRB.CreateICmpULT(Incr, ConstantInt::get(Int8Ty, 1));
Incr = IRB.CreateAdd(Incr, cf);
// Solution #3 - creates
//add cl,0x1
//cmp cl,0x1
//adc cl,0x0
} else if (neverZero_counters_str[0] == '3') {
auto cf = IRB.CreateICmpEQ(Incr, ConstantInt::get(Int8Ty, 0));
Incr = IRB.CreateAdd(Incr, cf);
// Solution #4 - creates
// cmp dl, $0xff
// sete cl
// add dl,cl
// add dl,0x01
} else if (neverZero_counters_str[0] == '4') {
auto cf = IRB.CreateICmpEQ(Counter, ConstantInt::get(Int8Ty, 255));
Value *HowMuch = IRB.CreateAdd(ConstantInt::get(Int8Ty, 1), cf);
Incr = IRB.CreateAdd(Counter, HowMuch);
} else if (neverZero_counters_str[0] == '5') {
// Solution #3
} else if (neverZero_counters_str[0] == '3') {
*/
// this is the solution we choose because llvm9 should do the right thing here
auto cf = IRB.CreateICmpEQ(Incr, ConstantInt::get(Int8Ty, 0));
auto carry = IRB.CreateZExt(cf, Int8Ty);
Incr = IRB.CreateAdd(Incr, carry);
/*
} else if (neverZero_counters_str[0] == '6') {
// Solution #4
} else if (neverZero_counters_str[0] == '4') {
auto cf = IRB.CreateICmpULT(Incr, ConstantInt::get(Int8Ty, 1));
auto carry = IRB.CreateZExt(cf, Int8Ty);
Incr = IRB.CreateAdd(Incr, carry);
// no other implementations yet
} else {
} else {
fprintf(stderr, "Error: unknown value for AFL_NZERO_COUNTS: %s (valid is 1-4)\n", neverZero_counters_str);
exit(-1);
}
}
*/
#if LLVM_VERSION_MAJOR < 9
}
#endif
IRB.CreateStore(Incr, MapPtrIdx)->setMetadata(M.getMDKindID("nosanitize"), MDNode::get(C, None));