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DataFlowSanitizer: Add a debugging feature to help us track nonzero labels.
Summary: When the -dfsan-debug-nonzero-labels parameter is supplied, the code is instrumented such that when a call parameter, return value or load produces a nonzero label, the function __dfsan_nonzero_label is called. The idea is that a debugger breakpoint can be set on this function in a nominally label-free program to help identify any bugs in the instrumentation pass causing labels to be introduced. Reviewers: eugenis CC: llvm-commits Differential Revision: http://llvm-reviews.chandlerc.com/D1405 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188472 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
parent
e427297997
commit
a77d9f726a
@ -95,6 +95,12 @@ static cl::opt<bool> ClArgsABI(
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cl::desc("Use the argument ABI rather than the TLS ABI"),
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cl::Hidden);
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static cl::opt<bool> ClDebugNonzeroLabels(
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"dfsan-debug-nonzero-labels",
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cl::desc("Insert calls to __dfsan_nonzero_label on observing a parameter, "
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"load or return with a nonzero label"),
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cl::Hidden);
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namespace {
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class DataFlowSanitizer : public ModulePass {
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@ -160,10 +166,12 @@ class DataFlowSanitizer : public ModulePass {
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FunctionType *DFSanUnionLoadFnTy;
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FunctionType *DFSanUnimplementedFnTy;
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FunctionType *DFSanSetLabelFnTy;
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FunctionType *DFSanNonzeroLabelFnTy;
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Constant *DFSanUnionFn;
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Constant *DFSanUnionLoadFn;
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Constant *DFSanUnimplementedFn;
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Constant *DFSanSetLabelFn;
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Constant *DFSanNonzeroLabelFn;
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MDNode *ColdCallWeights;
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OwningPtr<SpecialCaseList> ABIList;
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DenseMap<Value *, Function *> UnwrappedFnMap;
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@ -197,6 +205,7 @@ struct DFSanFunction {
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DenseMap<AllocaInst *, AllocaInst *> AllocaShadowMap;
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std::vector<std::pair<PHINode *, PHINode *> > PHIFixups;
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DenseSet<Instruction *> SkipInsts;
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DenseSet<Value *> NonZeroChecks;
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DFSanFunction(DataFlowSanitizer &DFS, Function *F, bool IsNativeABI)
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: DFS(DFS), F(F), IA(DFS.getInstrumentedABI()),
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@ -311,6 +320,8 @@ bool DataFlowSanitizer::doInitialization(Module &M) {
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Type *DFSanSetLabelArgs[3] = { ShadowTy, Type::getInt8PtrTy(*Ctx), IntptrTy };
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DFSanSetLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx),
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DFSanSetLabelArgs, /*isVarArg=*/false);
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DFSanNonzeroLabelFnTy = FunctionType::get(
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Type::getVoidTy(*Ctx), ArrayRef<Type *>(), /*isVarArg=*/false);
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if (GetArgTLSPtr) {
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Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
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@ -389,6 +400,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
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if (Function *F = dyn_cast<Function>(DFSanSetLabelFn)) {
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F->addAttribute(1, Attribute::ZExt);
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}
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DFSanNonzeroLabelFn =
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Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
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std::vector<Function *> FnsToInstrument;
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llvm::SmallPtrSet<Function *, 2> FnsWithNativeABI;
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@ -397,7 +410,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
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i != DFSanUnionFn &&
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i != DFSanUnionLoadFn &&
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i != DFSanUnimplementedFn &&
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i != DFSanSetLabelFn)
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i != DFSanSetLabelFn &&
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i != DFSanNonzeroLabelFn)
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FnsToInstrument.push_back(&*i);
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}
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@ -560,6 +574,31 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
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val, DFSF.getShadow(i->first->getIncomingValue(val)));
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}
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}
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// -dfsan-debug-nonzero-labels will split the CFG in all kinds of crazy
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// places (i.e. instructions in basic blocks we haven't even begun visiting
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// yet). To make our life easier, do this work in a pass after the main
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// instrumentation.
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if (ClDebugNonzeroLabels) {
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for (DenseSet<Value *>::iterator i = DFSF.NonZeroChecks.begin(),
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e = DFSF.NonZeroChecks.end();
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i != e; ++i) {
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Instruction *Pos;
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if (Instruction *I = dyn_cast<Instruction>(*i))
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Pos = I->getNextNode();
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else
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Pos = DFSF.F->getEntryBlock().begin();
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while (isa<PHINode>(Pos) || isa<AllocaInst>(Pos))
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Pos = Pos->getNextNode();
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IRBuilder<> IRB(Pos);
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Instruction *NeInst = cast<Instruction>(
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IRB.CreateICmpNE(*i, DFSF.DFS.ZeroShadow));
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BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
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NeInst, /*Unreachable=*/ false, ColdCallWeights));
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IRBuilder<> ThenIRB(BI);
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ThenIRB.CreateCall(DFSF.DFS.DFSanNonzeroLabelFn);
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}
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}
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}
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return false;
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@ -618,6 +657,7 @@ Value *DFSanFunction::getShadow(Value *V) {
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break;
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}
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}
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NonZeroChecks.insert(Shadow);
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} else {
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Shadow = DFS.ZeroShadow;
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}
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@ -814,7 +854,11 @@ void DFSanVisitor::visitLoadInst(LoadInst &LI) {
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Value *LoadedShadow =
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DFSF.loadShadow(LI.getPointerOperand(), Size, Align, &LI);
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Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand());
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DFSF.setShadow(&LI, DFSF.DFS.combineShadows(LoadedShadow, PtrShadow, &LI));
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Value *CombinedShadow = DFSF.DFS.combineShadows(LoadedShadow, PtrShadow, &LI);
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if (CombinedShadow != DFSF.DFS.ZeroShadow)
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DFSF.NonZeroChecks.insert(CombinedShadow);
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DFSF.setShadow(&LI, CombinedShadow);
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}
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void DFSanFunction::storeShadow(Value *Addr, uint64_t Size, uint64_t Align,
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@ -1131,6 +1175,7 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
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LoadInst *LI = NextIRB.CreateLoad(DFSF.getRetvalTLS());
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DFSF.SkipInsts.insert(LI);
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DFSF.setShadow(CS.getInstruction(), LI);
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DFSF.NonZeroChecks.insert(LI);
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}
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}
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@ -1184,6 +1229,7 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
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ExtractValueInst::Create(NewCS.getInstruction(), 1, "", Next);
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DFSF.SkipInsts.insert(ExShadow);
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DFSF.setShadow(ExVal, ExShadow);
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DFSF.NonZeroChecks.insert(ExShadow);
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CS.getInstruction()->replaceAllUsesWith(ExVal);
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}
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@ -0,0 +1,23 @@
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; RUN: opt < %s -dfsan -dfsan-args-abi -dfsan-debug-nonzero-labels -S | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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declare i32 @g()
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; CHECK: define { i32, i16 } @f(i32, i16)
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define i32 @f(i32) {
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; CHECK: [[LOCALLABELALLOCA:%.*]] = alloca i16
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; CHECK: [[ARGCMP:%.*]] = icmp ne i16 %1, 0
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; CHECK: br i1 [[ARGCMP]]
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%i = alloca i32
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store i32 %0, i32* %i
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; CHECK: [[CALL:%.*]] = call { i32, i16 } @g()
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; CHECK: [[CALLLABEL:%.*]] = extractvalue { i32, i16 } [[CALL]], 1
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; CHECK: [[CALLCMP:%.*]] = icmp ne i16 [[CALLLABEL]], 0
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; CHECK: br i1 [[CALLCMP]]
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%call = call i32 @g()
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; CHECK: [[LOCALLABEL:%.*]] = load i16* [[LOCALLABELALLOCA]]
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; CHECK: [[LOCALCMP:%.*]] = icmp ne i16 [[LOCALLABEL]], 0
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; CHECK: br i1 [[LOCALCMP]]
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%load = load i32* %i
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ret i32 %load
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}
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