X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;ds=sidebyside;f=lib%2FCodeGen%2FStackProtector.cpp;h=d1fae9558b26649e692ac0e23435836a4e1e0710;hb=d6b76f9466f267ac5ec8ac0f3afa83da0d810490;hp=3e6f44cabf18c4e4edc912713e20201333dde90a;hpb=47d6e07a9be631c582d47d8187a9073619d1c158;p=oota-llvm.git diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp index 3e6f44cabf1..d1fae9558b2 100644 --- a/lib/CodeGen/StackProtector.cpp +++ b/lib/CodeGen/StackProtector.cpp @@ -14,14 +14,13 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "stack-protector" -#include "llvm/CodeGen/Analysis.h" -#include "llvm/CodeGen/Passes.h" +#include "llvm/CodeGen/StackProtector.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/Statistic.h" -#include "llvm/ADT/Triple.h" -#include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/BranchProbabilityInfo.h" #include "llvm/Analysis/ValueTracking.h" +#include "llvm/CodeGen/Analysis.h" +#include "llvm/CodeGen/Passes.h" #include "llvm/IR/Attributes.h" #include "llvm/IR/Constants.h" #include "llvm/IR/DataLayout.h" @@ -29,156 +28,132 @@ #include "llvm/IR/Function.h" #include "llvm/IR/GlobalValue.h" #include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/IRBuilder.h" #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/Pass.h" #include "llvm/Support/CommandLine.h" -#include "llvm/Target/TargetLowering.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."); -static cl::opt -EnableSelectionDAGSP("enable-selectiondag-sp", cl::init(true), - cl::Hidden); - -namespace { - class StackProtector : public FunctionPass { - const TargetMachine *TM; - - /// TLI - Keep a pointer of a TargetLowering to consult for determining - /// target type sizes. - const TargetLoweringBase *TLI; - const Triple Trip; - - Function *F; - Module *M; - - DominatorTree *DT; - - /// \brief The minimum size of buffers that will receive stack smashing - /// protection when -fstack-protection is used. - unsigned SSPBufferSize; - - /// VisitedPHIs - The set of PHI nodes visited when determining - /// if a variable's reference has been taken. This set - /// is maintained to ensure we don't visit the same PHI node multiple - /// times. - SmallPtrSet VisitedPHIs; - - /// InsertStackProtectors - Insert code into the prologue and epilogue of - /// the function. - /// - /// - The prologue code loads and stores the stack guard onto the stack. - /// - The epilogue checks the value stored in the prologue against the - /// original value. It calls __stack_chk_fail if they differ. - bool InsertStackProtectors(); - - /// CreateFailBB - Create a basic block to jump to when the stack protector - /// check fails. - BasicBlock *CreateFailBB(); - - /// ContainsProtectableArray - Check whether the type either is an array or - /// contains an array of sufficient size so that we need stack protectors - /// for it. - bool ContainsProtectableArray(Type *Ty, bool Strong = false, - bool InStruct = false) const; - - /// \brief Check whether a stack allocation has its address taken. - bool HasAddressTaken(const Instruction *AI); - - /// RequiresStackProtector - Check whether or not this function needs a - /// stack protector based upon the stack protector level. - bool RequiresStackProtector(); - public: - static char ID; // Pass identification, replacement for typeid. - StackProtector() : FunctionPass(ID), TM(0), TLI(0), SSPBufferSize(0) { - initializeStackProtectorPass(*PassRegistry::getPassRegistry()); - } - StackProtector(const TargetMachine *TM) - : FunctionPass(ID), TM(TM), TLI(0), Trip(TM->getTargetTriple()), - SSPBufferSize(8) { - initializeStackProtectorPass(*PassRegistry::getPassRegistry()); - } - - virtual void getAnalysisUsage(AnalysisUsage &AU) const { - AU.addPreserved(); - } - - virtual bool runOnFunction(Function &Fn); - }; -} // end anonymous namespace +static cl::opt EnableSelectionDAGSP("enable-selectiondag-sp", + cl::init(true), cl::Hidden); char StackProtector::ID = 0; -INITIALIZE_PASS(StackProtector, "stack-protector", - "Insert stack protectors", false, false) +INITIALIZE_PASS(StackProtector, "stack-protector", "Insert stack protectors", + false, true) FunctionPass *llvm::createStackProtectorPass(const TargetMachine *TM) { return new StackProtector(TM); } +StackProtector::SSPLayoutKind +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(); - DT = getAnalysisIfAvailable(); - TLI = TM->getTargetLowering(); + DominatorTreeWrapperPass *DTWP = + getAnalysisIfAvailable(); + DT = DTWP ? &DTWP->getDomTree() : nullptr; + TLI = TM->getSubtargetImpl(Fn)->getTargetLowering(); - if (!RequiresStackProtector()) return false; + Attribute Attr = Fn.getFnAttribute("stack-protector-buffer-size"); + if (Attr.isStringAttribute() && + Attr.getValueAsString().getAsInteger(10, SSPBufferSize)) + return false; // Invalid integer string - Attribute Attr = - Fn.getAttributes().getAttribute(AttributeSet::FunctionIndex, - "stack-protector-buffer-size"); - if (Attr.isStringAttribute()) - SSPBufferSize = atoi(Attr.getValueAsString().data()); + if (!RequiresStackProtector()) + return false; ++NumFunProtected; return InsertStackProtectors(); } -/// ContainsProtectableArray - Check whether the type either is an array or -/// contains a char array of sufficient size so that we need stack protectors -/// for it. -bool StackProtector::ContainsProtectableArray(Type *Ty, bool Strong, +/// \param [out] IsLarge is set to true if a protectable array is found and +/// it is "large" ( >= ssp-buffer-size). In the case of a structure with +/// multiple arrays, this gets set if any of them is large. +bool StackProtector::ContainsProtectableArray(Type *Ty, bool &IsLarge, + bool Strong, bool InStruct) const { - if (!Ty) return false; + if (!Ty) + return false; if (ArrayType *AT = dyn_cast(Ty)) { - // In strong mode any array, regardless of type and size, triggers a - // protector - if (Strong) - return true; if (!AT->getElementType()->isIntegerTy(8)) { // If we're on a non-Darwin platform or we're inside of a structure, don't // add stack protectors unless the array is a character array. - if (InStruct || !Trip.isOSDarwin()) - return false; + // However, in strong mode any array, regardless of type and size, + // triggers a protector. + if (!Strong && (InStruct || !Trip.isOSDarwin())) + return false; } // If an array has more than SSPBufferSize bytes of allocated space, then we // emit stack protectors. - if (SSPBufferSize <= TLI->getDataLayout()->getTypeAllocSize(AT)) + if (SSPBufferSize <= TLI->getDataLayout()->getTypeAllocSize(AT)) { + IsLarge = true; + return true; + } + + if (Strong) + // Require a protector for all arrays in strong mode return true; } const StructType *ST = dyn_cast(Ty); - if (!ST) return false; + if (!ST) + return false; + bool NeedsProtector = false; for (StructType::element_iterator I = ST->element_begin(), - E = ST->element_end(); I != E; ++I) - if (ContainsProtectableArray(*I, Strong, true)) - return true; + E = ST->element_end(); + I != E; ++I) + if (ContainsProtectableArray(*I, IsLarge, Strong, true)) { + // If the element is a protectable array and is large (>= SSPBufferSize) + // then we are done. If the protectable array is not large, then + // keep looking in case a subsequent element is a large array. + if (IsLarge) + return true; + NeedsProtector = true; + } - return false; + return NeedsProtector; } 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; @@ -195,7 +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)) { @@ -224,63 +199,77 @@ bool StackProtector::HasAddressTaken(const Instruction *AI) { /// address taken. bool StackProtector::RequiresStackProtector() { bool Strong = false; - if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtectReq)) - return true; - else if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtectStrong)) + bool NeedsProtector = false; + if (F->hasFnAttribute(Attribute::StackProtectReq)) { + NeedsProtector = true; + Strong = true; // Use the same heuristic as strong to determine SSPLayout + } 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 (CI->getLimitedValue(SSPBufferSize) >= SSPBufferSize) + + if (const auto *CI = dyn_cast(AI->getArraySize())) { + if (CI->getLimitedValue(SSPBufferSize) >= SSPBufferSize) { // A call to alloca with size >= SSPBufferSize requires // stack protectors. - return true; + Layout.insert(std::make_pair(AI, SSPLK_LargeArray)); + NeedsProtector = true; + } else if (Strong) { + // Require protectors for all alloca calls in strong mode. + Layout.insert(std::make_pair(AI, SSPLK_SmallArray)); + NeedsProtector = true; + } } else { // A call to alloca with a variable size requires protectors. - return true; + Layout.insert(std::make_pair(AI, SSPLK_LargeArray)); + NeedsProtector = true; } + continue; } - if (ContainsProtectableArray(AI->getAllocatedType(), Strong)) - return true; + bool IsLarge = false; + if (ContainsProtectableArray(AI->getAllocatedType(), IsLarge, Strong)) { + Layout.insert(std::make_pair(AI, IsLarge ? SSPLK_LargeArray + : SSPLK_SmallArray)); + NeedsProtector = true; + continue; + } if (Strong && HasAddressTaken(AI)) { - ++NumAddrTaken; - return true; + ++NumAddrTaken; + Layout.insert(std::make_pair(AI, SSPLK_AddrOf)); + NeedsProtector = true; } } } } - return false; + return NeedsProtector; } static bool InstructionWillNotHaveChain(const Instruction *I) { return !I->mayHaveSideEffects() && !I->mayReadFromMemory() && - isSafeToSpeculativelyExecute(I); + isSafeToSpeculativelyExecute(I); } /// Identify if RI has a previous instruction in the "Tail Position" and return /// it. Otherwise return 0. /// -/// This is based off of the code in llvm::isInTailCallPosition +/// This is based off of the code in llvm::isInTailCallPosition. The difference +/// is that it inverts the first part of llvm::isInTailCallPosition since +/// isInTailCallPosition is checking if a call is in a tail call position, and +/// we are searching for an unknown tail call that might be in the tail call +/// position. Once we find the call though, the code uses the same refactored +/// code, returnTypeIsEligibleForTailCall. static CallInst *FindPotentialTailCall(BasicBlock *BB, ReturnInst *RI, const TargetLoweringBase *TLI) { // Establish a reasonable upper bound on the maximum amount of instructions we @@ -289,7 +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; @@ -319,13 +308,14 @@ static CallInst *FindPotentialTailCall(BasicBlock *BB, ReturnInst *RI, // If we did not find a call see if we have an instruction that may create // an interposing chain. - NoInterposingChain = NoInterposingChain && InstructionWillNotHaveChain(Inst); + NoInterposingChain = + NoInterposingChain && InstructionWillNotHaveChain(Inst); // Increment max search. SearchCounter++; } - return 0; + return nullptr; } /// Insert code into the entry block that stores the __stack_chk_guard @@ -339,37 +329,32 @@ 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()); unsigned AddressSpace, Offset; if (TLI->getStackCookieLocation(AddressSpace, Offset)) { Constant *OffsetVal = - ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset); - - StackGuardVar = ConstantExpr::getIntToPtr(OffsetVal, - PointerType::get(PtrTy, - AddressSpace)); - } else if (Trip.getOS() == llvm::Triple::OpenBSD) { + ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset); + + StackGuardVar = + ConstantExpr::getIntToPtr(OffsetVal, PointerType::get(PtrTy, + AddressSpace)); + } else if (TT.isOSOpenBSD()) { StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy); cast(StackGuardVar) - ->setVisibility(GlobalValue::HiddenVisibility); + ->setVisibility(GlobalValue::HiddenVisibility); } else { SupportsSelectionDAGSP = true; - StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy); + StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy); } - - BasicBlock &Entry = F->getEntryBlock(); - Instruction *InsPt = &Entry.front(); - - AI = new AllocaInst(PtrTy, "StackGuardSlot", InsPt); - LoadInst *LI = new LoadInst(StackGuardVar, "StackGuard", false, InsPt); - - Value *Args[] = { LI, AI }; - CallInst:: - Create(Intrinsic::getDeclaration(M, Intrinsic::stackprotector), - Args, "", InsPt); + + IRBuilder<> B(&F->getEntryBlock().front()); + AI = B.CreateAlloca(PtrTy, nullptr, "StackGuardSlot"); + LoadInst *LI = B.CreateLoad(StackGuardVar, "StackGuard"); + B.CreateCall2(Intrinsic::getDeclaration(M, Intrinsic::stackprotector), LI, + AI); return SupportsSelectionDAGSP; } @@ -382,41 +367,40 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, /// value. It calls __stack_chk_fail if they differ. bool StackProtector::InsertStackProtectors() { bool HasPrologue = false; - bool SupportsSelectionDAGSP = false; - AllocaInst *AI = 0; // Place on stack that stores the stack guard. - Value *StackGuardVar = 0; // The stack guard variable. + bool SupportsSelectionDAGSP = + EnableSelectionDAGSP && !TM->Options.EnableFastISel; + 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; ) { + for (Function::iterator I = F->begin(), E = F->end(); I != E;) { BasicBlock *BB = I++; ReturnInst *RI = dyn_cast(BB->getTerminator()); - if (!RI) continue; + if (!RI) + continue; if (!HasPrologue) { HasPrologue = true; - SupportsSelectionDAGSP = CreatePrologue(F, M, RI, TLI, Trip, AI, - StackGuardVar); - } + SupportsSelectionDAGSP &= + CreatePrologue(F, M, RI, TLI, Trip, AI, StackGuardVar); + } - if (EnableSelectionDAGSP && !TM->Options.EnableFastISel && - SupportsSelectionDAGSP) { + 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 { + } 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); - Value *Args[] = { StackGuardVar }; - CallInst::Create(Intrinsic, Args, "", InsertionPt); - + 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. @@ -445,34 +429,41 @@ bool StackProtector::InsertStackProtectors() { // Create the FailBB. We duplicate the BB every time since the MI tail // merge pass will merge together all of the various BB into one including - // fail BB generated by the stack protector pseudo instruction. + // fail BB generated by the stack protector pseudo instruction. BasicBlock *FailBB = CreateFailBB(); - + // Split the basic block before the return instruction. BasicBlock *NewBB = BB->splitBasicBlock(RI, "SP_return"); - + // Update the dominator tree if we need to. if (DT && DT->isReachableFromEntry(BB)) { DT->addNewBlock(NewBB, BB); DT->addNewBlock(FailBB, BB); } - + // Remove default branch instruction to the new BB. BB->getTerminator()->eraseFromParent(); - + // Move the newly created basic block to the point right after the old // basic block so that it's in the "fall through" position. NewBB->moveAfter(BB); - + // Generate the stack protector instructions in the old basic block. - LoadInst *LI1 = new LoadInst(StackGuardVar, "", false, BB); - LoadInst *LI2 = new LoadInst(AI, "", true, BB); - ICmpInst *Cmp = new ICmpInst(*BB, CmpInst::ICMP_EQ, LI1, LI2, ""); - BranchInst::Create(NewBB, FailBB, Cmp, BB); + IRBuilder<> B(BB); + LoadInst *LI1 = B.CreateLoad(StackGuardVar); + LoadInst *LI2 = B.CreateLoad(AI); + Value *Cmp = B.CreateICmpEQ(LI1, LI2); + 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; @@ -485,29 +476,20 @@ bool StackProtector::InsertStackProtectors() { BasicBlock *StackProtector::CreateFailBB() { LLVMContext &Context = F->getContext(); BasicBlock *FailBB = BasicBlock::Create(Context, "CallStackCheckFailBlk", F); - if (Trip.getOS() == llvm::Triple::OpenBSD) { - Constant *StackChkFail = M->getOrInsertFunction( - "__stack_smash_handler", Type::getVoidTy(Context), - Type::getInt8PtrTy(Context), NULL); - - Constant *NameStr = ConstantDataArray::getString(Context, F->getName()); - Constant *FuncName = - new GlobalVariable(*M, NameStr->getType(), true, - GlobalVariable::PrivateLinkage, NameStr, "SSH"); - - SmallVector IdxList; - IdxList.push_back(ConstantInt::get(Type::getInt8Ty(Context), 0)); - IdxList.push_back(ConstantInt::get(Type::getInt8Ty(Context), 0)); - - SmallVector Args; - Args.push_back(ConstantExpr::getGetElementPtr(FuncName, IdxList)); - - CallInst::Create(StackChkFail, Args, "", FailBB); + IRBuilder<> B(FailBB); + 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); - CallInst::Create(StackChkFail, "", FailBB); + Constant *StackChkFail = + M->getOrInsertFunction("__stack_chk_fail", Type::getVoidTy(Context), + nullptr); + B.CreateCall(StackChkFail); } - new UnreachableInst(Context, FailBB); + B.CreateUnreachable(); return FailBB; }