diff options
author | Dimitry Andric <dim@FreeBSD.org> | 2015-06-21 13:59:01 +0000 |
---|---|---|
committer | Dimitry Andric <dim@FreeBSD.org> | 2015-06-21 13:59:01 +0000 |
commit | 3a0822f094b578157263e04114075ad7df81db41 (patch) | |
tree | bc48361fe2cd1ca5f93ac01b38b183774468fc79 /lib/Transforms/Instrumentation | |
parent | 85d8b2bbe386bcfe669575d05b61482d7be07e5d (diff) | |
download | src-3a0822f094b578157263e04114075ad7df81db41.tar.gz src-3a0822f094b578157263e04114075ad7df81db41.zip |
Vendor import of llvm trunk r240225:vendor/llvm/llvm-trunk-r240225
Notes
Notes:
svn path=/vendor/llvm/dist/; revision=284677
svn path=/vendor/llvm/llvm-trunk-r240225/; revision=284678; tag=vendor/llvm/llvm-trunk-r240225
Diffstat (limited to 'lib/Transforms/Instrumentation')
-rw-r--r-- | lib/Transforms/Instrumentation/AddressSanitizer.cpp | 123 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/BoundsChecking.cpp | 2 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/CMakeLists.txt | 1 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/DataFlowSanitizer.cpp | 2 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/GCOVProfiling.cpp | 4 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/Instrumentation.cpp | 1 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/MemorySanitizer.cpp | 2 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/SafeStack.cpp | 608 | ||||
-rw-r--r-- | lib/Transforms/Instrumentation/SanitizerCoverage.cpp | 12 |
9 files changed, 694 insertions, 61 deletions
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp index 25f78b0b2a26..2dd2fe6211c3 100644 --- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp +++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp @@ -67,6 +67,7 @@ static const uint64_t kDefaultShadowOffset32 = 1ULL << 29; static const uint64_t kIOSShadowOffset32 = 1ULL << 30; static const uint64_t kDefaultShadowOffset64 = 1ULL << 44; static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G. +static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000; static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41; static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000; static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37; @@ -106,10 +107,8 @@ static const char *const kAsanUnpoisonStackMemoryName = static const char *const kAsanOptionDetectUAR = "__asan_option_detect_stack_use_after_return"; -static const char *const kAsanAllocaPoison = - "__asan_alloca_poison"; -static const char *const kAsanAllocasUnpoison = - "__asan_allocas_unpoison"; +static const char *const kAsanAllocaPoison = "__asan_alloca_poison"; +static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison"; // Accesses sizes are powers of two: 1, 2, 4, 8, 16. static const size_t kNumberOfAccessSizes = 5; @@ -117,6 +116,9 @@ static const size_t kNumberOfAccessSizes = 5; static const unsigned kAllocaRzSize = 32; // Command-line flags. +static cl::opt<bool> ClEnableKasan( + "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"), + cl::Hidden, cl::init(false)); // This flag may need to be replaced with -f[no-]asan-reads. static cl::opt<bool> ClInstrumentReads("asan-instrument-reads", @@ -317,7 +319,8 @@ struct ShadowMapping { bool OrShadowOffset; }; -static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) { +static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize, + bool IsKasan) { bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android; bool IsIOS = TargetTriple.isiOS(); bool IsFreeBSD = TargetTriple.isOSFreeBSD(); @@ -352,9 +355,12 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) { Mapping.Offset = kPPC64_ShadowOffset64; else if (IsFreeBSD) Mapping.Offset = kFreeBSD_ShadowOffset64; - else if (IsLinux && IsX86_64) - Mapping.Offset = kSmallX86_64ShadowOffset; - else if (IsMIPS64) + else if (IsLinux && IsX86_64) { + if (IsKasan) + Mapping.Offset = kLinuxKasan_ShadowOffset64; + else + Mapping.Offset = kSmallX86_64ShadowOffset; + } else if (IsMIPS64) Mapping.Offset = kMIPS64_ShadowOffset64; else if (IsAArch64) Mapping.Offset = kAArch64_ShadowOffset64; @@ -383,7 +389,8 @@ static size_t RedzoneSizeForScale(int MappingScale) { /// AddressSanitizer: instrument the code in module to find memory bugs. struct AddressSanitizer : public FunctionPass { - AddressSanitizer() : FunctionPass(ID) { + explicit AddressSanitizer(bool CompileKernel = false) + : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) { initializeAddressSanitizerPass(*PassRegistry::getPassRegistry()); } const char *getPassName() const override { @@ -410,8 +417,7 @@ struct AddressSanitizer : public FunctionPass { /// If it is an interesting memory access, return the PointerOperand /// and set IsWrite/Alignment. Otherwise return nullptr. Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite, - uint64_t *TypeSize, - unsigned *Alignment); + uint64_t *TypeSize, unsigned *Alignment); void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I, bool UseCalls, const DataLayout &DL); void instrumentPointerComparisonOrSubtraction(Instruction *I); @@ -447,11 +453,12 @@ struct AddressSanitizer : public FunctionPass { LLVMContext *C; Triple TargetTriple; int LongSize; + bool CompileKernel; Type *IntptrTy; ShadowMapping Mapping; DominatorTree *DT; - Function *AsanCtorFunction; - Function *AsanInitFunction; + Function *AsanCtorFunction = nullptr; + Function *AsanInitFunction = nullptr; Function *AsanHandleNoReturnFunc; Function *AsanPtrCmpFunction, *AsanPtrSubFunction; // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize). @@ -470,7 +477,8 @@ struct AddressSanitizer : public FunctionPass { class AddressSanitizerModule : public ModulePass { public: - AddressSanitizerModule() : ModulePass(ID) {} + explicit AddressSanitizerModule(bool CompileKernel = false) + : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {} bool runOnModule(Module &M) override; static char ID; // Pass identification, replacement for typeid const char *getPassName() const override { return "AddressSanitizerModule"; } @@ -487,6 +495,7 @@ class AddressSanitizerModule : public ModulePass { } GlobalsMetadata GlobalsMD; + bool CompileKernel; Type *IntptrTy; LLVMContext *C; Triple TargetTriple; @@ -588,7 +597,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> { Value *SavedStack) { IRBuilder<> IRB(InstBefore); IRB.CreateCall(AsanAllocasUnpoisonFunc, - {IRB.CreateLoad(DynamicAllocaLayout), + {IRB.CreateLoad(DynamicAllocaLayout), IRB.CreatePtrToInt(SavedStack, IntptrTy)}); } @@ -692,8 +701,8 @@ INITIALIZE_PASS_END( AddressSanitizer, "asan", "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false, false) -FunctionPass *llvm::createAddressSanitizerFunctionPass() { - return new AddressSanitizer(); +FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) { + return new AddressSanitizer(CompileKernel); } char AddressSanitizerModule::ID = 0; @@ -702,8 +711,8 @@ INITIALIZE_PASS( "AddressSanitizer: detects use-after-free and out-of-bounds bugs." "ModulePass", false, false) -ModulePass *llvm::createAddressSanitizerModulePass() { - return new AddressSanitizerModule(); +ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) { + return new AddressSanitizerModule(CompileKernel); } static size_t TypeSizeToSizeIndex(uint32_t TypeSize) { @@ -1347,16 +1356,18 @@ bool AddressSanitizerModule::runOnModule(Module &M) { int LongSize = M.getDataLayout().getPointerSizeInBits(); IntptrTy = Type::getIntNTy(*C, LongSize); TargetTriple = Triple(M.getTargetTriple()); - Mapping = getShadowMapping(TargetTriple, LongSize); + Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel); initializeCallbacks(M); bool Changed = false; - Function *CtorFunc = M.getFunction(kAsanModuleCtorName); - assert(CtorFunc); - IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator()); - - if (ClGlobals) Changed |= InstrumentGlobals(IRB, M); + // TODO(glider): temporarily disabled globals instrumentation for KASan. + if (ClGlobals && !CompileKernel) { + Function *CtorFunc = M.getFunction(kAsanModuleCtorName); + assert(CtorFunc); + IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator()); + Changed |= InstrumentGlobals(IRB, M); + } return Changed; } @@ -1369,38 +1380,44 @@ void AddressSanitizer::initializeCallbacks(Module &M) { for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) { const std::string TypeStr = AccessIsWrite ? "store" : "load"; const std::string ExpStr = Exp ? "exp_" : ""; + const std::string SuffixStr = CompileKernel ? "N" : "_n"; + const std::string EndingStr = CompileKernel ? "_noabort" : ""; const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr; + // TODO(glider): for KASan builds add _noabort to error reporting + // functions and make them actually noabort (remove the UnreachableInst). AsanErrorCallbackSized[AccessIsWrite][Exp] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - kAsanReportErrorTemplate + ExpStr + TypeStr + "_n", + kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr, IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr)); AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N", + ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr, IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr)); for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes; AccessSizeIndex++) { const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex); AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - kAsanReportErrorTemplate + ExpStr + Suffix, IRB.getVoidTy(), - IntptrTy, ExpType, nullptr)); + kAsanReportErrorTemplate + ExpStr + Suffix, + IRB.getVoidTy(), IntptrTy, ExpType, nullptr)); AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - ClMemoryAccessCallbackPrefix + ExpStr + Suffix, IRB.getVoidTy(), - IntptrTy, ExpType, nullptr)); + ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr, + IRB.getVoidTy(), IntptrTy, ExpType, nullptr)); } } } + const std::string MemIntrinCallbackPrefix = + CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix; AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(), + MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr)); AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(), + MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr)); AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction( - ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(), + MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr)); AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction( @@ -1427,14 +1444,14 @@ bool AddressSanitizer::doInitialization(Module &M) { IntptrTy = Type::getIntNTy(*C, LongSize); TargetTriple = Triple(M.getTargetTriple()); - std::tie(AsanCtorFunction, AsanInitFunction) = - createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName, kAsanInitName, - /*InitArgTypes=*/{}, - /*InitArgs=*/{}); - - Mapping = getShadowMapping(TargetTriple, LongSize); - - appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); + if (!CompileKernel) { + std::tie(AsanCtorFunction, AsanInitFunction) = + createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName, kAsanInitName, + /*InitArgTypes=*/{}, + /*InitArgs=*/{}); + appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); + } + Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel); return true; } @@ -1516,11 +1533,10 @@ bool AddressSanitizer::runOnFunction(Function &F) { } } - bool UseCalls = false; - if (ClInstrumentationWithCallsThreshold >= 0 && - ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold) - UseCalls = true; - + bool UseCalls = + CompileKernel || + (ClInstrumentationWithCallsThreshold >= 0 && + ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold); const TargetLibraryInfo *TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); const DataLayout &DL = F.getParent()->getDataLayout(); @@ -1706,8 +1722,7 @@ void FunctionStackPoisoner::poisonStack() { if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) { // Handle dynamic allocas. createDynamicAllocasInitStorage(); - for (auto &AI : DynamicAllocaVec) - handleDynamicAllocaCall(AI); + for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI); unpoisonDynamicAllocas(); } @@ -1736,8 +1751,8 @@ void FunctionStackPoisoner::poisonStack() { ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L); DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n"); uint64_t LocalStackSize = L.FrameSize; - bool DoStackMalloc = - ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize; + bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel && + LocalStackSize <= kMaxStackMallocSize; // Don't do dynamic alloca in presence of inline asm: too often it makes // assumptions on which registers are available. Don't do stack malloc in the // presence of inline asm on 32-bit platforms for the same reason. @@ -1901,9 +1916,9 @@ void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size, // For now just insert the call to ASan runtime. Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy); Value *SizeArg = ConstantInt::get(IntptrTy, Size); - IRB.CreateCall(DoPoison ? AsanPoisonStackMemoryFunc - : AsanUnpoisonStackMemoryFunc, - {AddrArg, SizeArg}); + IRB.CreateCall( + DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc, + {AddrArg, SizeArg}); } // Handling llvm.lifetime intrinsics for a given %alloca: diff --git a/lib/Transforms/Instrumentation/BoundsChecking.cpp b/lib/Transforms/Instrumentation/BoundsChecking.cpp index f6858034d79e..a8874251ee07 100644 --- a/lib/Transforms/Instrumentation/BoundsChecking.cpp +++ b/lib/Transforms/Instrumentation/BoundsChecking.cpp @@ -63,7 +63,7 @@ namespace { void emitBranchToTrap(Value *Cmp = nullptr); bool instrument(Value *Ptr, Value *Val, const DataLayout &DL); }; -} +} // namespace char BoundsChecking::ID = 0; INITIALIZE_PASS(BoundsChecking, "bounds-checking", "Run-time bounds checking", diff --git a/lib/Transforms/Instrumentation/CMakeLists.txt b/lib/Transforms/Instrumentation/CMakeLists.txt index b2ff03343eb0..9b81f4bb1619 100644 --- a/lib/Transforms/Instrumentation/CMakeLists.txt +++ b/lib/Transforms/Instrumentation/CMakeLists.txt @@ -6,6 +6,7 @@ add_llvm_library(LLVMInstrumentation MemorySanitizer.cpp Instrumentation.cpp InstrProfiling.cpp + SafeStack.cpp SanitizerCoverage.cpp ThreadSanitizer.cpp diff --git a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp index 2de6e1afaba9..43091572aeb1 100644 --- a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp +++ b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp @@ -346,7 +346,7 @@ class DFSanVisitor : public InstVisitor<DFSanVisitor> { void visitMemTransferInst(MemTransferInst &I); }; -} +} // namespace char DataFlowSanitizer::ID; INITIALIZE_PASS(DataFlowSanitizer, "dfsan", diff --git a/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/lib/Transforms/Instrumentation/GCOVProfiling.cpp index 9a3ed5c04efc..43caf1fcb8d0 100644 --- a/lib/Transforms/Instrumentation/GCOVProfiling.cpp +++ b/lib/Transforms/Instrumentation/GCOVProfiling.cpp @@ -139,7 +139,7 @@ namespace { LLVMContext *Ctx; SmallVector<std::unique_ptr<GCOVFunction>, 16> Funcs; }; -} +} // namespace char GCOVProfiler::ID = 0; INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling", @@ -419,7 +419,7 @@ namespace { DenseMap<BasicBlock *, GCOVBlock> Blocks; GCOVBlock ReturnBlock; }; -} +} // namespace std::string GCOVProfiler::mangleName(const DICompileUnit *CU, const char *NewStem) { diff --git a/lib/Transforms/Instrumentation/Instrumentation.cpp b/lib/Transforms/Instrumentation/Instrumentation.cpp index a91fc0ec2a48..27505859100b 100644 --- a/lib/Transforms/Instrumentation/Instrumentation.cpp +++ b/lib/Transforms/Instrumentation/Instrumentation.cpp @@ -30,6 +30,7 @@ void llvm::initializeInstrumentation(PassRegistry &Registry) { initializeThreadSanitizerPass(Registry); initializeSanitizerCoverageModulePass(Registry); initializeDataFlowSanitizerPass(Registry); + initializeSafeStackPass(Registry); } /// LLVMInitializeInstrumentation - C binding for diff --git a/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/lib/Transforms/Instrumentation/MemorySanitizer.cpp index 100824e59af5..63eee2f7153a 100644 --- a/lib/Transforms/Instrumentation/MemorySanitizer.cpp +++ b/lib/Transforms/Instrumentation/MemorySanitizer.cpp @@ -2022,6 +2022,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> { Value *CopyOp, *ConvertOp; switch (I.getNumArgOperands()) { + case 3: + assert(isa<ConstantInt>(I.getArgOperand(2)) && "Invalid rounding mode"); case 2: CopyOp = I.getArgOperand(0); ConvertOp = I.getArgOperand(1); diff --git a/lib/Transforms/Instrumentation/SafeStack.cpp b/lib/Transforms/Instrumentation/SafeStack.cpp new file mode 100644 index 000000000000..13c541218313 --- /dev/null +++ b/lib/Transforms/Instrumentation/SafeStack.cpp @@ -0,0 +1,608 @@ +//===-- SafeStack.cpp - Safe Stack Insertion ------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This pass splits the stack into the safe stack (kept as-is for LLVM backend) +// and the unsafe stack (explicitly allocated and managed through the runtime +// support library). +// +// http://clang.llvm.org/docs/SafeStack.html +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Instrumentation.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/ADT/Triple.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/DIBuilder.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/InstIterator.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/Module.h" +#include "llvm/Pass.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/Format.h" +#include "llvm/Support/MathExtras.h" +#include "llvm/Support/raw_os_ostream.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Transforms/Utils/ModuleUtils.h" + +using namespace llvm; + +#define DEBUG_TYPE "safestack" + +namespace llvm { + +STATISTIC(NumFunctions, "Total number of functions"); +STATISTIC(NumUnsafeStackFunctions, "Number of functions with unsafe stack"); +STATISTIC(NumUnsafeStackRestorePointsFunctions, + "Number of functions that use setjmp or exceptions"); + +STATISTIC(NumAllocas, "Total number of allocas"); +STATISTIC(NumUnsafeStaticAllocas, "Number of unsafe static allocas"); +STATISTIC(NumUnsafeDynamicAllocas, "Number of unsafe dynamic allocas"); +STATISTIC(NumUnsafeStackRestorePoints, "Number of setjmps and landingpads"); + +} // namespace llvm + +namespace { + +/// Check whether a given alloca instruction (AI) should be put on the safe +/// stack or not. The function analyzes all uses of AI and checks whether it is +/// only accessed in a memory safe way (as decided statically). +bool IsSafeStackAlloca(const AllocaInst *AI) { + // Go through all uses of this alloca and check whether all accesses to the + // allocated object are statically known to be memory safe and, hence, the + // object can be placed on the safe stack. + + SmallPtrSet<const Value *, 16> Visited; + SmallVector<const Instruction *, 8> WorkList; + WorkList.push_back(AI); + + // A DFS search through all uses of the alloca in bitcasts/PHI/GEPs/etc. + while (!WorkList.empty()) { + const Instruction *V = WorkList.pop_back_val(); + for (const Use &UI : V->uses()) { + auto I = cast<const Instruction>(UI.getUser()); + assert(V == UI.get()); + + switch (I->getOpcode()) { + case Instruction::Load: + // Loading from a pointer is safe. + break; + case Instruction::VAArg: + // "va-arg" from a pointer is safe. + break; + case Instruction::Store: + if (V == I->getOperand(0)) + // Stored the pointer - conservatively assume it may be unsafe. + return false; + // Storing to the pointee is safe. + break; + + case Instruction::GetElementPtr: + if (!cast<const GetElementPtrInst>(I)->hasAllConstantIndices()) + // GEP with non-constant indices can lead to memory errors. + // This also applies to inbounds GEPs, as the inbounds attribute + // represents an assumption that the address is in bounds, rather than + // an assertion that it is. + return false; + + // We assume that GEP on static alloca with constant indices is safe, + // otherwise a compiler would detect it and warn during compilation. + + if (!isa<const ConstantInt>(AI->getArraySize())) + // However, if the array size itself is not constant, the access + // might still be unsafe at runtime. + return false; + + /* fallthrough */ + + case Instruction::BitCast: + case Instruction::IntToPtr: + case Instruction::PHI: + case Instruction::PtrToInt: + case Instruction::Select: + // The object can be safe or not, depending on how the result of the + // instruction is used. + if (Visited.insert(I).second) + WorkList.push_back(cast<const Instruction>(I)); + break; + + case Instruction::Call: + case Instruction::Invoke: { + // FIXME: add support for memset and memcpy intrinsics. + ImmutableCallSite CS(I); + + // LLVM 'nocapture' attribute is only set for arguments whose address + // is not stored, passed around, or used in any other non-trivial way. + // We assume that passing a pointer to an object as a 'nocapture' + // argument is safe. + // FIXME: a more precise solution would require an interprocedural + // analysis here, which would look at all uses of an argument inside + // the function being called. + ImmutableCallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end(); + for (ImmutableCallSite::arg_iterator A = B; A != E; ++A) + if (A->get() == V && !CS.doesNotCapture(A - B)) + // The parameter is not marked 'nocapture' - unsafe. + return false; + continue; + } + + default: + // The object is unsafe if it is used in any other way. + return false; + } + } + } + + // All uses of the alloca are safe, we can place it on the safe stack. + return true; +} + +/// The SafeStack pass splits the stack of each function into the +/// safe stack, which is only accessed through memory safe dereferences +/// (as determined statically), and the unsafe stack, which contains all +/// local variables that are accessed in unsafe ways. +class SafeStack : public FunctionPass { + const DataLayout *DL; + + Type *StackPtrTy; + Type *IntPtrTy; + Type *Int32Ty; + Type *Int8Ty; + + Constant *UnsafeStackPtr; + + /// Unsafe stack alignment. Each stack frame must ensure that the stack is + /// aligned to this value. We need to re-align the unsafe stack if the + /// alignment of any object on the stack exceeds this value. + /// + /// 16 seems like a reasonable upper bound on the alignment of objects that we + /// might expect to appear on the stack on most common targets. + enum { StackAlignment = 16 }; + + /// \brief Build a constant representing a pointer to the unsafe stack + /// pointer. + Constant *getOrCreateUnsafeStackPtr(Module &M); + + /// \brief Find all static allocas, dynamic allocas, return instructions and + /// stack restore points (exception unwind blocks and setjmp calls) in the + /// given function and append them to the respective vectors. + void findInsts(Function &F, SmallVectorImpl<AllocaInst *> &StaticAllocas, + SmallVectorImpl<AllocaInst *> &DynamicAllocas, + SmallVectorImpl<ReturnInst *> &Returns, + SmallVectorImpl<Instruction *> &StackRestorePoints); + + /// \brief Allocate space for all static allocas in \p StaticAllocas, + /// replace allocas with pointers into the unsafe stack and generate code to + /// restore the stack pointer before all return instructions in \p Returns. + /// + /// \returns A pointer to the top of the unsafe stack after all unsafe static + /// allocas are allocated. + Value *moveStaticAllocasToUnsafeStack(Function &F, + ArrayRef<AllocaInst *> StaticAllocas, + ArrayRef<ReturnInst *> Returns); + + /// \brief Generate code to restore the stack after all stack restore points + /// in \p StackRestorePoints. + /// + /// \returns A local variable in which to maintain the dynamic top of the + /// unsafe stack if needed. + AllocaInst * + createStackRestorePoints(Function &F, + ArrayRef<Instruction *> StackRestorePoints, + Value *StaticTop, bool NeedDynamicTop); + + /// \brief Replace all allocas in \p DynamicAllocas with code to allocate + /// space dynamically on the unsafe stack and store the dynamic unsafe stack + /// top to \p DynamicTop if non-null. + void moveDynamicAllocasToUnsafeStack(Function &F, Value *UnsafeStackPtr, + AllocaInst *DynamicTop, + ArrayRef<AllocaInst *> DynamicAllocas); + +public: + static char ID; // Pass identification, replacement for typeid. + SafeStack() : FunctionPass(ID), DL(nullptr) { + initializeSafeStackPass(*PassRegistry::getPassRegistry()); + } + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired<AliasAnalysis>(); + } + + virtual bool doInitialization(Module &M) { + DL = &M.getDataLayout(); + + StackPtrTy = Type::getInt8PtrTy(M.getContext()); + IntPtrTy = DL->getIntPtrType(M.getContext()); + Int32Ty = Type::getInt32Ty(M.getContext()); + Int8Ty = Type::getInt8Ty(M.getContext()); + + UnsafeStackPtr = getOrCreateUnsafeStackPtr(M); + + return false; + } + + bool runOnFunction(Function &F); + +}; // class SafeStack + +Constant *SafeStack::getOrCreateUnsafeStackPtr(Module &M) { + // The unsafe stack pointer is stored in a global variable with a magic name. + const char *kUnsafeStackPtrVar = "__safestack_unsafe_stack_ptr"; + + auto UnsafeStackPtr = + dyn_cast_or_null<GlobalVariable>(M.getNamedValue(kUnsafeStackPtrVar)); + + if (!UnsafeStackPtr) { + // The global variable is not defined yet, define it ourselves. + // We use the initial-exec TLS model because we do not support the variable + // living anywhere other than in the main executable. + UnsafeStackPtr = new GlobalVariable( + /*Module=*/M, /*Type=*/StackPtrTy, + /*isConstant=*/false, /*Linkage=*/GlobalValue::ExternalLinkage, + /*Initializer=*/0, /*Name=*/kUnsafeStackPtrVar, + /*InsertBefore=*/nullptr, + /*ThreadLocalMode=*/GlobalValue::InitialExecTLSModel); + } else { + // The variable exists, check its type and attributes. + if (UnsafeStackPtr->getValueType() != StackPtrTy) { + report_fatal_error(Twine(kUnsafeStackPtrVar) + " must have void* type"); + } + + if (!UnsafeStackPtr->isThreadLocal()) { + report_fatal_error(Twine(kUnsafeStackPtrVar) + " must be thread-local"); + } + } + + return UnsafeStackPtr; +} + +void SafeStack::findInsts(Function &F, + SmallVectorImpl<AllocaInst *> &StaticAllocas, + SmallVectorImpl<AllocaInst *> &DynamicAllocas, + SmallVectorImpl<ReturnInst *> &Returns, + SmallVectorImpl<Instruction *> &StackRestorePoints) { + for (Instruction &I : inst_range(&F)) { + if (auto AI = dyn_cast<AllocaInst>(&I)) { + ++NumAllocas; + + if (IsSafeStackAlloca(AI)) + continue; + + if (AI->isStaticAlloca()) { + ++NumUnsafeStaticAllocas; + StaticAllocas.push_back(AI); + } else { + ++NumUnsafeDynamicAllocas; + DynamicAllocas.push_back(AI); + } + } else if (auto RI = dyn_cast<ReturnInst>(&I)) { + Returns.push_back(RI); + } else if (auto CI = dyn_cast<CallInst>(&I)) { + // setjmps require stack restore. + if (CI->getCalledFunction() && CI->canReturnTwice()) + StackRestorePoints.push_back(CI); + } else if (auto LP = dyn_cast<LandingPadInst>(&I)) { + // Exception landing pads require stack restore. + StackRestorePoints.push_back(LP); + } else if (auto II = dyn_cast<IntrinsicInst>(&I)) { + if (II->getIntrinsicID() == Intrinsic::gcroot) + llvm::report_fatal_error( + "gcroot intrinsic not compatible with safestack attribute"); + } + } +} + +AllocaInst * +SafeStack::createStackRestorePoints(Function &F, + ArrayRef<Instruction *> StackRestorePoints, + Value *StaticTop, bool NeedDynamicTop) { + if (StackRestorePoints.empty()) + return nullptr; + + IRBuilder<> IRB(StaticTop + ? cast<Instruction>(StaticTop)->getNextNode() + : (Instruction *)F.getEntryBlock().getFirstInsertionPt()); + + // We need the current value of the shadow stack pointer to restore + // after longjmp or exception catching. + + // FIXME: On some platforms this could be handled by the longjmp/exception + // runtime itself. + + AllocaInst *DynamicTop = nullptr; + if (NeedDynamicTop) + // If we also have dynamic alloca's, the stack pointer value changes + // throughout the function. For now we store it in an alloca. + DynamicTop = IRB.CreateAlloca(StackPtrTy, /*ArraySize=*/nullptr, + "unsafe_stack_dynamic_ptr"); + + if (!StaticTop) + // We need the original unsafe stack pointer value, even if there are + // no unsafe static allocas. + StaticTop = IRB.CreateLoad(UnsafeStackPtr, false, "unsafe_stack_ptr"); + + if (NeedDynamicTop) + IRB.CreateStore(StaticTop, DynamicTop); + + // Restore current stack pointer after longjmp/exception catch. + for (Instruction *I : StackRestorePoints) { + ++NumUnsafeStackRestorePoints; + + IRB.SetInsertPoint(cast<Instruction>(I->getNextNode())); + Value *CurrentTop = DynamicTop ? IRB.CreateLoad(DynamicTop) : StaticTop; + IRB.CreateStore(CurrentTop, UnsafeStackPtr); + } + + return DynamicTop; +} + +Value * +SafeStack::moveStaticAllocasToUnsafeStack(Function &F, + ArrayRef<AllocaInst *> StaticAllocas, + ArrayRef<ReturnInst *> Returns) { + if (StaticAllocas.empty()) + return nullptr; + + IRBuilder<> IRB(F.getEntryBlock().getFirstInsertionPt()); + DIBuilder DIB(*F.getParent()); + + // We explicitly compute and set the unsafe stack layout for all unsafe + // static alloca instructions. We save the unsafe "base pointer" in the + // prologue into a local variable and restore it in the epilogue. + + // Load the current stack pointer (we'll also use it as a base pointer). + // FIXME: use a dedicated register for it ? + Instruction *BasePointer = + IRB.CreateLoad(UnsafeStackPtr, false, "unsafe_stack_ptr"); + assert(BasePointer->getType() == StackPtrTy); + + for (ReturnInst *RI : Returns) { + IRB.SetInsertPoint(RI); + IRB.CreateStore(BasePointer, UnsafeStackPtr); + } + + // Compute maximum alignment among static objects on the unsafe stack. + unsigned MaxAlignment = 0; + for (AllocaInst *AI : StaticAllocas) { + Type *Ty = AI->getAllocatedType(); + unsigned Align = + std::max((unsigned)DL->getPrefTypeAlignment(Ty), AI->getAlignment()); + if (Align > MaxAlignment) + MaxAlignment = Align; + } + + if (MaxAlignment > StackAlignment) { + // Re-align the base pointer according to the max requested alignment. + assert(isPowerOf2_32(MaxAlignment)); + IRB.SetInsertPoint(cast<Instruction>(BasePointer->getNextNode())); + BasePointer = cast<Instruction>(IRB.CreateIntToPtr( + IRB.CreateAnd(IRB.CreatePtrToInt(BasePointer, IntPtrTy), + ConstantInt::get(IntPtrTy, ~uint64_t(MaxAlignment - 1))), + StackPtrTy)); + } + + // Allocate space for every unsafe static AllocaInst on the unsafe stack. + int64_t StaticOffset = 0; // Current stack top. + for (AllocaInst *AI : StaticAllocas) { + IRB.SetInsertPoint(AI); + + auto CArraySize = cast<ConstantInt>(AI->getArraySize()); + Type *Ty = AI->getAllocatedType(); + + uint64_t Size = DL->getTypeAllocSize(Ty) * CArraySize->getZExtValue(); + if (Size == 0) + Size = 1; // Don't create zero-sized stack objects. + + // Ensure the object is properly aligned. + unsigned Align = + std::max((unsigned)DL->getPrefTypeAlignment(Ty), AI->getAlignment()); + + // Add alignment. + // NOTE: we ensure that BasePointer itself is aligned to >= Align. + StaticOffset += Size; + StaticOffset = RoundUpToAlignment(StaticOffset, Align); + + Value *Off = IRB.CreateGEP(BasePointer, // BasePointer is i8* + ConstantInt::get(Int32Ty, -StaticOffset)); + Value *NewAI = IRB.CreateBitCast(Off, AI->getType(), AI->getName()); + if (AI->hasName() && isa<Instruction>(NewAI)) + cast<Instruction>(NewAI)->takeName(AI); + + // Replace alloc with the new location. + replaceDbgDeclareForAlloca(AI, NewAI, DIB, /*Deref=*/true); + AI->replaceAllUsesWith(NewAI); + AI->eraseFromParent(); + } + + // Re-align BasePointer so that our callees would see it aligned as + // expected. + // FIXME: no need to update BasePointer in leaf functions. + StaticOffset = RoundUpToAlignment(StaticOffset, StackAlignment); + + // Update shadow stack pointer in the function epilogue. + IRB.SetInsertPoint(cast<Instruction>(BasePointer->getNextNode())); + + Value *StaticTop = + IRB.CreateGEP(BasePointer, ConstantInt::get(Int32Ty, -StaticOffset), + "unsafe_stack_static_top"); + IRB.CreateStore(StaticTop, UnsafeStackPtr); + return StaticTop; +} + +void SafeStack::moveDynamicAllocasToUnsafeStack( + Function &F, Value *UnsafeStackPtr, AllocaInst *DynamicTop, + ArrayRef<AllocaInst *> DynamicAllocas) { + DIBuilder DIB(*F.getParent()); + + for (AllocaInst *AI : DynamicAllocas) { + IRBuilder<> IRB(AI); + + // Compute the new SP value (after AI). + Value *ArraySize = AI->getArraySize(); + if (ArraySize->getType() != IntPtrTy) + ArraySize = IRB.CreateIntCast(ArraySize, IntPtrTy, false); + + Type *Ty = AI->getAllocatedType(); + uint64_t TySize = DL->getTypeAllocSize(Ty); + Value *Size = IRB.CreateMul(ArraySize, ConstantInt::get(IntPtrTy, TySize)); + + Value *SP = IRB.CreatePtrToInt(IRB.CreateLoad(UnsafeStackPtr), IntPtrTy); + SP = IRB.CreateSub(SP, Size); + + // Align the SP value to satisfy the AllocaInst, type and stack alignments. + unsigned Align = std::max( + std::max((unsigned)DL->getPrefTypeAlignment(Ty), AI->getAlignment()), + (unsigned)StackAlignment); + + assert(isPowerOf2_32(Align)); + Value *NewTop = IRB.CreateIntToPtr( + IRB.CreateAnd(SP, ConstantInt::get(IntPtrTy, ~uint64_t(Align - 1))), + StackPtrTy); + + // Save the stack pointer. + IRB.CreateStore(NewTop, UnsafeStackPtr); + if (DynamicTop) + IRB.CreateStore(NewTop, DynamicTop); + + Value *NewAI = IRB.CreateIntToPtr(SP, AI->getType()); + if (AI->hasName() && isa<Instruction>(NewAI)) + NewAI->takeName(AI); + + replaceDbgDeclareForAlloca(AI, NewAI, DIB, /*Deref=*/true); + AI->replaceAllUsesWith(NewAI); + AI->eraseFromParent(); + } + + if (!DynamicAllocas.empty()) { + // Now go through the instructions again, replacing stacksave/stackrestore. + for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F); It != Ie;) { + Instruction *I = &*(It++); + auto II = dyn_cast<IntrinsicInst>(I); + if (!II) + continue; + + if (II->getIntrinsicID() == Intrinsic::stacksave) { + IRBuilder<> IRB(II); + Instruction *LI = IRB.CreateLoad(UnsafeStackPtr); + LI->takeName(II); + II->replaceAllUsesWith(LI); + II->eraseFromParent(); + } else if (II->getIntrinsicID() == Intrinsic::stackrestore) { + IRBuilder<> IRB(II); + Instruction *SI = IRB.CreateStore(II->getArgOperand(0), UnsafeStackPtr); + SI->takeName(II); + assert(II->use_empty()); + II->eraseFromParent(); + } + } + } +} + +bool SafeStack::runOnFunction(Function &F) { + auto AA = &getAnalysis<AliasAnalysis>(); + + DEBUG(dbgs() << "[SafeStack] Function: " << F.getName() << "\n"); + + if (!F.hasFnAttribute(Attribute::SafeStack)) { + DEBUG(dbgs() << "[SafeStack] safestack is not requested" + " for this function\n"); + return false; + } + + if (F.isDeclaration()) { + DEBUG(dbgs() << "[SafeStack] function definition" + " is not available\n"); + return false; + } + + { + // Make sure the regular stack protector won't run on this function + // (safestack attribute takes precedence). + AttrBuilder B; + B.addAttribute(Attribute::StackProtect) + .addAttribute(Attribute::StackProtectReq) + .addAttribute(Attribute::StackProtectStrong); + F.removeAttributes( + AttributeSet::FunctionIndex, + AttributeSet::get(F.getContext(), AttributeSet::FunctionIndex, B)); + } + + if (AA->onlyReadsMemory(&F)) { + // XXX: we don't protect against information leak attacks for now. + DEBUG(dbgs() << "[SafeStack] function only reads memory\n"); + return false; + } + + ++NumFunctions; + + SmallVector<AllocaInst *, 16> StaticAllocas; + SmallVector<AllocaInst *, 4> DynamicAllocas; + SmallVector<ReturnInst *, 4> Returns; + + // Collect all points where stack gets unwound and needs to be restored + // This is only necessary because the runtime (setjmp and unwind code) is + // not aware of the unsafe stack and won't unwind/restore it prorerly. + // To work around this problem without changing the runtime, we insert + // instrumentation to restore the unsafe stack pointer when necessary. + SmallVector<Instruction *, 4> StackRestorePoints; + + // Find all static and dynamic alloca instructions that must be moved to the + // unsafe stack, all return instructions and stack restore points. + findInsts(F, StaticAllocas, DynamicAllocas, Returns, StackRestorePoints); + + if (StaticAllocas.empty() && DynamicAllocas.empty() && + StackRestorePoints.empty()) + return false; // Nothing to do in this function. + + if (!StaticAllocas.empty() || !DynamicAllocas.empty()) + ++NumUnsafeStackFunctions; // This function has the unsafe stack. + + if (!StackRestorePoints.empty()) + ++NumUnsafeStackRestorePointsFunctions; + + // The top of the unsafe stack after all unsafe static allocas are allocated. + Value *StaticTop = moveStaticAllocasToUnsafeStack(F, StaticAllocas, Returns); + + // Safe stack object that stores the current unsafe stack top. It is updated + // as unsafe dynamic (non-constant-sized) allocas are allocated and freed. + // This is only needed if we need to restore stack pointer after longjmp + // or exceptions, and we have dynamic allocations. + // FIXME: a better alternative might be to store the unsafe stack pointer + // before setjmp / invoke instructions. + AllocaInst *DynamicTop = createStackRestorePoints( + F, StackRestorePoints, StaticTop, !DynamicAllocas.empty()); + + // Handle dynamic allocas. + moveDynamicAllocasToUnsafeStack(F, UnsafeStackPtr, DynamicTop, + DynamicAllocas); + + DEBUG(dbgs() << "[SafeStack] safestack applied\n"); + return true; +} + +} // end anonymous namespace + +char SafeStack::ID = 0; +INITIALIZE_PASS_BEGIN(SafeStack, "safe-stack", + "Safe Stack instrumentation pass", false, false) +INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) +INITIALIZE_PASS_END(SafeStack, "safe-stack", "Safe Stack instrumentation pass", + false, false) + +FunctionPass *llvm::createSafeStackPass() { return new SafeStack(); } diff --git a/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/lib/Transforms/Instrumentation/SanitizerCoverage.cpp index f6ae0c2dd5f9..dff39efa5b96 100644 --- a/lib/Transforms/Instrumentation/SanitizerCoverage.cpp +++ b/lib/Transforms/Instrumentation/SanitizerCoverage.cpp @@ -33,6 +33,7 @@ #include "llvm/ADT/SmallVector.h" #include "llvm/IR/CallSite.h" #include "llvm/IR/DataLayout.h" +#include "llvm/IR/DebugInfo.h" #include "llvm/IR/Function.h" #include "llvm/IR/IRBuilder.h" #include "llvm/IR/InlineAsm.h" @@ -385,9 +386,14 @@ void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB, } bool IsEntryBB = &BB == &F.getEntryBlock(); - DebugLoc EntryLoc = IsEntryBB && IP->getDebugLoc() - ? IP->getDebugLoc().getFnDebugLoc() - : IP->getDebugLoc(); + DebugLoc EntryLoc; + if (IsEntryBB) { + if (auto SP = getDISubprogram(&F)) + EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP); + } else { + EntryLoc = IP->getDebugLoc(); + } + IRBuilder<> IRB(IP); IRB.SetCurrentDebugLocation(EntryLoc); SmallVector<Value *, 1> Indices; |