X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FStackProtector.cpp;h=0824d6f91db0776c0ba79a255d98b725372530a0;hb=f5b42730589f63e5000102a288ce198ce449d98d;hp=b350237f9b61bd3d8e9d4c96382616c30f39de7a;hpb=7f2eff792a2e18758a25956abdac2440ee18dd7f;p=oota-llvm.git diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp index b350237f9b6..0824d6f91db 100644 --- a/lib/CodeGen/StackProtector.cpp +++ b/lib/CodeGen/StackProtector.cpp @@ -14,10 +14,10 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "stack-protector" #include "llvm/CodeGen/StackProtector.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/BranchProbabilityInfo.h" #include "llvm/Analysis/ValueTracking.h" #include "llvm/CodeGen/Analysis.h" #include "llvm/CodeGen/Passes.h" @@ -32,11 +32,15 @@ #include "llvm/IR/Instructions.h" #include "llvm/IR/IntrinsicInst.h" #include "llvm/IR/Intrinsics.h" +#include "llvm/IR/MDBuilder.h" #include "llvm/IR/Module.h" #include "llvm/Support/CommandLine.h" +#include "llvm/Target/TargetSubtargetInfo.h" #include using namespace llvm; +#define DEBUG_TYPE "stack-protector" + STATISTIC(NumFunProtected, "Number of functions protected"); STATISTIC(NumAddrTaken, "Number of local variables that have their address" " taken."); @@ -57,22 +61,43 @@ StackProtector::getSSPLayout(const AllocaInst *AI) const { return AI ? Layout.lookup(AI) : SSPLK_None; } +void StackProtector::adjustForColoring(const AllocaInst *From, + const AllocaInst *To) { + // When coloring replaces one alloca with another, transfer the SSPLayoutKind + // tag from the remapped to the target alloca. The remapped alloca should + // have a size smaller than or equal to the replacement alloca. + SSPLayoutMap::iterator I = Layout.find(From); + if (I != Layout.end()) { + SSPLayoutKind Kind = I->second; + Layout.erase(I); + + // Transfer the tag, but make sure that SSPLK_AddrOf does not overwrite + // SSPLK_SmallArray or SSPLK_LargeArray, and make sure that + // SSPLK_SmallArray does not overwrite SSPLK_LargeArray. + I = Layout.find(To); + if (I == Layout.end()) + Layout.insert(std::make_pair(To, Kind)); + else if (I->second != SSPLK_LargeArray && Kind != SSPLK_AddrOf) + I->second = Kind; + } +} + bool StackProtector::runOnFunction(Function &Fn) { F = &Fn; M = F->getParent(); DominatorTreeWrapperPass *DTWP = getAnalysisIfAvailable(); - DT = DTWP ? &DTWP->getDomTree() : 0; - TLI = TM->getTargetLowering(); + DT = DTWP ? &DTWP->getDomTree() : nullptr; + TLI = TM->getSubtargetImpl(Fn)->getTargetLowering(); + + Attribute Attr = Fn.getFnAttribute("stack-protector-buffer-size"); + if (Attr.isStringAttribute() && + Attr.getValueAsString().getAsInteger(10, SSPBufferSize)) + return false; // Invalid integer string if (!RequiresStackProtector()) return false; - Attribute Attr = Fn.getAttributes().getAttribute( - AttributeSet::FunctionIndex, "stack-protector-buffer-size"); - if (Attr.isStringAttribute()) - Attr.getValueAsString().getAsInteger(10, SSPBufferSize); - ++NumFunProtected; return InsertStackProtectors(); } @@ -128,9 +153,7 @@ bool StackProtector::ContainsProtectableArray(Type *Ty, bool &IsLarge, } bool StackProtector::HasAddressTaken(const Instruction *AI) { - for (Value::const_use_iterator UI = AI->use_begin(), UE = AI->use_end(); - UI != UE; ++UI) { - const User *U = *UI; + for (const User *U : AI->users()) { if (const StoreInst *SI = dyn_cast(U)) { if (AI == SI->getValueOperand()) return true; @@ -147,7 +170,7 @@ bool StackProtector::HasAddressTaken(const Instruction *AI) { } else if (const PHINode *PN = dyn_cast(U)) { // Keep track of what PHI nodes we have already visited to ensure // they are only visited once. - if (VisitedPHIs.insert(PN)) + if (VisitedPHIs.insert(PN).second) if (HasAddressTaken(PN)) return true; } else if (const GetElementPtrInst *GEP = dyn_cast(U)) { @@ -177,31 +200,24 @@ bool StackProtector::HasAddressTaken(const Instruction *AI) { bool StackProtector::RequiresStackProtector() { bool Strong = false; bool NeedsProtector = false; - if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtectReq)) { + if (F->hasFnAttribute(Attribute::StackProtectReq)) { NeedsProtector = true; Strong = true; // Use the same heuristic as strong to determine SSPLayout - } else if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtectStrong)) + } else if (F->hasFnAttribute(Attribute::StackProtectStrong)) Strong = true; - else if (!F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtect)) + else if (!F->hasFnAttribute(Attribute::StackProtect)) return false; - for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) { - BasicBlock *BB = I; - - for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; - ++II) { - if (AllocaInst *AI = dyn_cast(II)) { + for (const BasicBlock &BB : *F) { + for (const Instruction &I : BB) { + if (const AllocaInst *AI = dyn_cast(&I)) { if (AI->isArrayAllocation()) { // SSP-Strong: Enable protectors for any call to alloca, regardless // of size. if (Strong) return true; - if (const ConstantInt *CI = - dyn_cast(AI->getArraySize())) { + if (const auto *CI = dyn_cast(AI->getArraySize())) { if (CI->getLimitedValue(SSPBufferSize) >= SSPBufferSize) { // A call to alloca with size >= SSPBufferSize requires // stack protectors. @@ -262,8 +278,7 @@ static CallInst *FindPotentialTailCall(BasicBlock *BB, ReturnInst *RI, const unsigned MaxSearch = 4; bool NoInterposingChain = true; - for (BasicBlock::reverse_iterator I = llvm::next(BB->rbegin()), - E = BB->rend(); + for (BasicBlock::reverse_iterator I = std::next(BB->rbegin()), E = BB->rend(); I != E && SearchCounter < MaxSearch; ++I) { Instruction *Inst = &*I; @@ -300,7 +315,7 @@ static CallInst *FindPotentialTailCall(BasicBlock *BB, ReturnInst *RI, SearchCounter++; } - return 0; + return nullptr; } /// Insert code into the entry block that stores the __stack_chk_guard @@ -314,7 +329,7 @@ static CallInst *FindPotentialTailCall(BasicBlock *BB, ReturnInst *RI, /// Returns true if the platform/triple supports the stackprotectorcreate pseudo /// node. static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, - const TargetLoweringBase *TLI, const Triple &Trip, + const TargetLoweringBase *TLI, const Triple &TT, AllocaInst *&AI, Value *&StackGuardVar) { bool SupportsSelectionDAGSP = false; PointerType *PtrTy = Type::getInt8PtrTy(RI->getContext()); @@ -323,9 +338,10 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, Constant *OffsetVal = ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset); - StackGuardVar = ConstantExpr::getIntToPtr( - OffsetVal, PointerType::get(PtrTy, AddressSpace)); - } else if (Trip.getOS() == llvm::Triple::OpenBSD) { + StackGuardVar = + ConstantExpr::getIntToPtr(OffsetVal, PointerType::get(PtrTy, + AddressSpace)); + } else if (TT.isOSOpenBSD()) { StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy); cast(StackGuardVar) ->setVisibility(GlobalValue::HiddenVisibility); @@ -335,10 +351,10 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, } IRBuilder<> B(&F->getEntryBlock().front()); - AI = B.CreateAlloca(PtrTy, 0, "StackGuardSlot"); + AI = B.CreateAlloca(PtrTy, nullptr, "StackGuardSlot"); LoadInst *LI = B.CreateLoad(StackGuardVar, "StackGuard"); - B.CreateCall2(Intrinsic::getDeclaration(M, Intrinsic::stackprotector), LI, - AI); + B.CreateCall(Intrinsic::getDeclaration(M, Intrinsic::stackprotector), + {LI, AI}); return SupportsSelectionDAGSP; } @@ -353,8 +369,8 @@ bool StackProtector::InsertStackProtectors() { bool HasPrologue = false; bool SupportsSelectionDAGSP = EnableSelectionDAGSP && !TM->Options.EnableFastISel; - AllocaInst *AI = 0; // Place on stack that stores the stack guard. - Value *StackGuardVar = 0; // The stack guard variable. + AllocaInst *AI = nullptr; // Place on stack that stores the stack guard. + Value *StackGuardVar = nullptr; // The stack guard variable. for (Function::iterator I = F->begin(), E = F->end(); I != E;) { BasicBlock *BB = I++; @@ -371,21 +387,20 @@ bool StackProtector::InsertStackProtectors() { if (SupportsSelectionDAGSP) { // Since we have a potential tail call, insert the special stack check // intrinsic. - Instruction *InsertionPt = 0; + Instruction *InsertionPt = nullptr; if (CallInst *CI = FindPotentialTailCall(BB, RI, TLI)) { InsertionPt = CI; } else { InsertionPt = RI; // At this point we know that BB has a return statement so it *DOES* // have a terminator. - assert(InsertionPt != 0 && "BB must have a terminator instruction at " - "this point."); + assert(InsertionPt != nullptr && + "BB must have a terminator instruction at this point."); } Function *Intrinsic = Intrinsic::getDeclaration(M, Intrinsic::stackprotectorcheck); CallInst::Create(Intrinsic, StackGuardVar, "", InsertionPt); - } else { // If we do not support SelectionDAG based tail calls, generate IR level // tail calls. @@ -438,11 +453,17 @@ bool StackProtector::InsertStackProtectors() { LoadInst *LI1 = B.CreateLoad(StackGuardVar); LoadInst *LI2 = B.CreateLoad(AI); Value *Cmp = B.CreateICmpEQ(LI1, LI2); - B.CreateCondBr(Cmp, NewBB, FailBB); + unsigned SuccessWeight = + BranchProbabilityInfo::getBranchWeightStackProtector(true); + unsigned FailureWeight = + BranchProbabilityInfo::getBranchWeightStackProtector(false); + MDNode *Weights = MDBuilder(F->getContext()) + .createBranchWeights(SuccessWeight, FailureWeight); + B.CreateCondBr(Cmp, NewBB, FailBB, Weights); } } - // Return if we didn't modify any basic blocks. I.e., there are no return + // Return if we didn't modify any basic blocks. i.e., there are no return // statements in the function. if (!HasPrologue) return false; @@ -456,16 +477,18 @@ BasicBlock *StackProtector::CreateFailBB() { LLVMContext &Context = F->getContext(); BasicBlock *FailBB = BasicBlock::Create(Context, "CallStackCheckFailBlk", F); IRBuilder<> B(FailBB); - if (Trip.getOS() == llvm::Triple::OpenBSD) { - Constant *StackChkFail = M->getOrInsertFunction( - "__stack_smash_handler", Type::getVoidTy(Context), - Type::getInt8PtrTy(Context), NULL); + if (Trip.isOSOpenBSD()) { + Constant *StackChkFail = + M->getOrInsertFunction("__stack_smash_handler", + Type::getVoidTy(Context), + Type::getInt8PtrTy(Context), nullptr); B.CreateCall(StackChkFail, B.CreateGlobalStringPtr(F->getName(), "SSH")); } else { - Constant *StackChkFail = M->getOrInsertFunction( - "__stack_chk_fail", Type::getVoidTy(Context), NULL); - B.CreateCall(StackChkFail); + Constant *StackChkFail = + M->getOrInsertFunction("__stack_chk_fail", Type::getVoidTy(Context), + nullptr); + B.CreateCall(StackChkFail, {}); } B.CreateUnreachable(); return FailBB;