X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FStackProtector.cpp;h=e478f31d54552f33eba9ece7c6cd26a1c864fff5;hb=fe0bf8fbf9d401a67a1842da6cefbb58aa8975a3;hp=cb22082e4da01df48a2642135938f7c4cb65257e;hpb=18ebd48960afe9a4e694dac3ba0ee1002044d297;p=oota-llvm.git diff --git a/lib/CodeGen/StackProtector.cpp b/lib/CodeGen/StackProtector.cpp index cb22082e4da..e478f31d545 100644 --- a/lib/CodeGen/StackProtector.cpp +++ b/lib/CodeGen/StackProtector.cpp @@ -14,14 +14,12 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "stack-protector" #include "llvm/CodeGen/StackProtector.h" -#include "llvm/CodeGen/Analysis.h" -#include "llvm/CodeGen/Passes.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/Statistic.h" -#include "llvm/Analysis/Dominators.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" @@ -35,82 +33,126 @@ #include "llvm/IR/Intrinsics.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."); -static cl::opt -EnableSelectionDAGSP("enable-selectiondag-sp", cl::init(true), - cl::Hidden); +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(); - - if (!RequiresStackProtector()) return false; - - Attribute Attr = - Fn.getAttributes().getAttribute(AttributeSet::FunctionIndex, - "stack-protector-buffer-size"); - if (Attr.isStringAttribute()) - Attr.getValueAsString().getAsInteger(10, SSPBufferSize); + DominatorTreeWrapperPass *DTWP = + getAnalysisIfAvailable(); + DT = DTWP ? &DTWP->getDomTree() : nullptr; + TLI = TM->getSubtargetImpl()->getTargetLowering(); + + Attribute Attr = Fn.getAttributes().getAttribute( + AttributeSet::FunctionIndex, "stack-protector-buffer-size"); + if (Attr.isStringAttribute() && + Attr.getValueAsString().getAsInteger(10, SSPBufferSize)) + return false; // Invalid integer string + + 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; @@ -156,11 +198,13 @@ bool StackProtector::HasAddressTaken(const Instruction *AI) { /// address taken. bool StackProtector::RequiresStackProtector() { bool Strong = false; + bool NeedsProtector = false; if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtectReq)) - return true; - else if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, - Attribute::StackProtectStrong)) + Attribute::StackProtectReq)) { + NeedsProtector = true; + Strong = true; // Use the same heuristic as strong to determine SSPLayout + } else if (F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, + Attribute::StackProtectStrong)) Strong = true; else if (!F->getAttributes().hasAttribute(AttributeSet::FunctionIndex, Attribute::StackProtect)) @@ -169,8 +213,8 @@ bool StackProtector::RequiresStackProtector() { 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) { + for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; + ++II) { if (AllocaInst *AI = dyn_cast(II)) { if (AI->isArrayAllocation()) { // SSP-Strong: Enable protectors for any call to alloca, regardless @@ -179,34 +223,48 @@ bool StackProtector::RequiresStackProtector() { return true; if (const ConstantInt *CI = - dyn_cast(AI->getArraySize())) { - if (CI->getLimitedValue(SSPBufferSize) >= SSPBufferSize) + 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; + 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 @@ -226,7 +284,7 @@ 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; @@ -256,13 +314,14 @@ 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 @@ -283,22 +342,21 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, unsigned AddressSpace, Offset; if (TLI->getStackCookieLocation(AddressSpace, Offset)) { Constant *OffsetVal = - ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset); + ConstantInt::get(Type::getInt32Ty(RI->getContext()), Offset); - StackGuardVar = ConstantExpr::getIntToPtr(OffsetVal, - PointerType::get(PtrTy, - AddressSpace)); + StackGuardVar = ConstantExpr::getIntToPtr( + OffsetVal, PointerType::get(PtrTy, AddressSpace)); } else if (Trip.getOS() == llvm::Triple::OpenBSD) { StackGuardVar = M->getOrInsertGlobal("__guard_local", PtrTy); cast(StackGuardVar) - ->setVisibility(GlobalValue::HiddenVisibility); + ->setVisibility(GlobalValue::HiddenVisibility); } else { SupportsSelectionDAGSP = true; StackGuardVar = M->getOrInsertGlobal("__stack_chk_guard", PtrTy); } 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); @@ -315,11 +373,11 @@ static bool CreatePrologue(Function *F, Module *M, ReturnInst *RI, 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. + 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) @@ -327,26 +385,26 @@ bool StackProtector::InsertStackProtectors() { if (!HasPrologue) { HasPrologue = true; - SupportsSelectionDAGSP &= CreatePrologue(F, M, RI, TLI, Trip, AI, - StackGuardVar); + SupportsSelectionDAGSP &= + CreatePrologue(F, M, RI, TLI, Trip, AI, StackGuardVar); } 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); + Intrinsic::getDeclaration(M, Intrinsic::stackprotectorcheck); CallInst::Create(Intrinsic, StackGuardVar, "", InsertionPt); } else {