Index: lib/Transforms/Instrumentation/AddressSanitizer.cpp =================================================================== --- lib/Transforms/Instrumentation/AddressSanitizer.cpp +++ lib/Transforms/Instrumentation/AddressSanitizer.cpp @@ -600,6 +600,22 @@ void initializeCallbacks(Module &M); bool InstrumentGlobals(IRBuilder<> &IRB, Module &M); + void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M, + ArrayRef ExtendedGlobals, + ArrayRef MetadataInitializers); + void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M, + ArrayRef ExtendedGlobals, + ArrayRef MetadataInitializers); + void + InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M, + ArrayRef ExtendedGlobals, + ArrayRef MetadataInitializers); + + GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer, + StringRef OriginalName); + void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata); + IRBuilder<> CreateAsanModuleDtor(Module &M); + bool ShouldInstrumentGlobal(GlobalVariable *G); bool ShouldUseMachOGlobalsSection() const; StringRef getGlobalMetadataSection() const; @@ -1553,17 +1569,172 @@ // Declare the functions that find globals in a shared object and then invoke // the (un)register function on them. - AsanRegisterImageGlobals = checkSanitizerInterfaceFunction( - M.getOrInsertFunction(kAsanRegisterImageGlobalsName, - IRB.getVoidTy(), IntptrTy, nullptr)); + AsanRegisterImageGlobals = + checkSanitizerInterfaceFunction(M.getOrInsertFunction( + kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr)); AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage); - AsanUnregisterImageGlobals = checkSanitizerInterfaceFunction( - M.getOrInsertFunction(kAsanUnregisterImageGlobalsName, - IRB.getVoidTy(), IntptrTy, nullptr)); + AsanUnregisterImageGlobals = + checkSanitizerInterfaceFunction(M.getOrInsertFunction( + kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr)); AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage); } +// Put the metadata and the instrumented global in the same group. This ensures +// that the metadata is discarded if the instrumented global is discarded. +void AddressSanitizerModule::SetComdatForGlobalMetadata( + GlobalVariable *G, GlobalVariable *Metadata) { + Module &M = *G->getParent(); + Comdat *C = G->getComdat(); + if (!C) { + if (!G->hasName()) { + // If G is unnamed, it must be internal. Give it an artificial name + // so we can put it in a comdat. + assert(G->hasLocalLinkage()); + G->setName(Twine(kAsanGenPrefix) + "_anon_global"); + } + C = M.getOrInsertComdat(G->getName()); + // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF. + if (TargetTriple.isOSBinFormatCOFF()) + C->setSelectionKind(Comdat::NoDuplicates); + G->setComdat(C); + } + + assert(G->hasComdat()); + Metadata->setComdat(G->getComdat()); +} + +// Create a separate metadata global and put it in the appropriate ASan +// global registration section. +GlobalVariable * +AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer, + StringRef OriginalName) { + auto &DL = M.getDataLayout(); + GlobalVariable *Metadata = + new GlobalVariable(M, Initializer->getType(), false, + GlobalVariable::InternalLinkage, Initializer, + Twine("__asan_global_") + + GlobalValue::getRealLinkageName(OriginalName)); + Metadata->setSection(getGlobalMetadataSection()); + + // We don't want any padding, but we also need a reasonable alignment. + // The MSVC linker always inserts padding when linking incrementally. We + // cope with that by aligning each struct to its size, which must be a power + // of two. + unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType()); + assert(isPowerOf2_32(SizeOfGlobalStruct) && + "global metadata will not be padded appropriately"); + Metadata->setAlignment(SizeOfGlobalStruct); + return Metadata; +} + +IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) { + Function *AsanDtorFunction = + Function::Create(FunctionType::get(Type::getVoidTy(*C), false), + GlobalValue::InternalLinkage, kAsanModuleDtorName, &M); + BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction); + appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority); + + return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB)); +} + +void AddressSanitizerModule::InstrumentGlobalsCOFF( + IRBuilder<> &IRB, Module &M, ArrayRef ExtendedGlobals, + ArrayRef MetadataInitializers) { + assert(ExtendedGlobals.size() == MetadataInitializers.size()); + + for (size_t i = 0; i < ExtendedGlobals.size(); i++) { + GlobalVariable *G = ExtendedGlobals[i]; + GlobalVariable *Metadata = + CreateMetadataGlobal(M, MetadataInitializers[i], G->getName()); + SetComdatForGlobalMetadata(G, Metadata); + } +} + +void AddressSanitizerModule::InstrumentGlobalsMachO( + IRBuilder<> &IRB, Module &M, ArrayRef ExtendedGlobals, + ArrayRef MetadataInitializers) { + assert(ExtendedGlobals.size() == MetadataInitializers.size()); + + // On recent Mach-O platforms, use a structure which binds the liveness of + // the global variable to the metadata struct. Keep the list of "Liveness" GV + // created to be added to llvm.compiler.used + StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr); + SmallVector LivenessGlobals(ExtendedGlobals.size()); + + for (size_t i = 0; i < ExtendedGlobals.size(); i++) { + Constant *Initializer = MetadataInitializers[i]; + GlobalVariable *G = ExtendedGlobals[i]; + GlobalVariable *Metadata = + CreateMetadataGlobal(M, Initializer, G->getName()); + + // On recent Mach-O platforms, we emit the global metadata in a way that + // allows the linker to properly strip dead globals. + auto LivenessBinder = ConstantStruct::get( + LivenessTy, Initializer->getAggregateElement(0u), + ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr); + GlobalVariable *Liveness = new GlobalVariable( + M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder, + Twine("__asan_binder_") + G->getName()); + Liveness->setSection("__DATA,__asan_liveness,regular,live_support"); + LivenessGlobals[i] = Liveness; + } + + // Update llvm.compiler.used, adding the new liveness globals. This is + // needed so that during LTO these variables stay alive. The alternative + // would be to have the linker handling the LTO symbols, but libLTO + // current API does not expose access to the section for each symbol. + if (!LivenessGlobals.empty()) + appendToCompilerUsed(M, LivenessGlobals); + + // RegisteredFlag serves two purposes. First, we can pass it to dladdr() + // to look up the loaded image that contains it. Second, we can store in it + // whether registration has already occurred, to prevent duplicate + // registration. + // + // common linkage ensures that there is only one global per shared library. + GlobalVariable *RegisteredFlag = new GlobalVariable( + M, IntptrTy, false, GlobalVariable::CommonLinkage, + ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName); + RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility); + + IRB.CreateCall(AsanRegisterImageGlobals, + {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)}); + + // We also need to unregister globals at the end, e.g., when a shared library + // gets closed. + IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M); + IRB_Dtor.CreateCall(AsanUnregisterImageGlobals, + {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)}); +} + +void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray( + IRBuilder<> &IRB, Module &M, ArrayRef ExtendedGlobals, + ArrayRef MetadataInitializers) { + assert(ExtendedGlobals.size() == MetadataInitializers.size()); + unsigned N = ExtendedGlobals.size(); + assert(N > 0); + + // On platforms that don't have a custom metadata section, we emit an array + // of global metadata structures. + ArrayType *ArrayOfGlobalStructTy = + ArrayType::get(MetadataInitializers[0]->getType(), N); + auto AllGlobals = new GlobalVariable( + M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage, + ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), ""); + + IRB.CreateCall(AsanRegisterGlobals, + {IRB.CreatePointerCast(AllGlobals, IntptrTy), + ConstantInt::get(IntptrTy, N)}); + + // We also need to unregister globals at the end, e.g., when a shared library + // gets closed. + IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M); + IRB_Dtor.CreateCall(AsanUnregisterGlobals, + {IRB.CreatePointerCast(AllGlobals, IntptrTy), + ConstantInt::get(IntptrTy, N)}); +} + // This function replaces all global variables with new variables that have // trailing redzones. It also creates a function that poisons // redzones and inserts this function into llvm.global_ctors. @@ -1580,9 +1751,6 @@ if (n == 0) return false; auto &DL = M.getDataLayout(); - bool UseComdatMetadata = TargetTriple.isOSBinFormatCOFF(); - bool UseMachOGlobalsSection = ShouldUseMachOGlobalsSection(); - bool UseMetadataArray = !(UseComdatMetadata || UseMachOGlobalsSection); // A global is described by a structure // size_t beg; @@ -1597,19 +1765,8 @@ StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, nullptr); - unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(GlobalStructTy); - assert(isPowerOf2_32(SizeOfGlobalStruct) && - "global metadata will not be padded appropriately"); - SmallVector Initializers(UseMetadataArray ? n : 0); - - // On recent Mach-O platforms, use a structure which binds the liveness of - // the global variable to the metadata struct. Keep the list of "Liveness" GV - // created to be added to llvm.compiler.used - StructType *LivenessTy = nullptr; - if (UseMachOGlobalsSection) - LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr); - SmallVector LivenessGlobals( - UseMachOGlobalsSection ? n : 0); + SmallVector NewGlobals(n); + SmallVector Initializers(n); bool HasDynamicallyInitializedGlobals = false; @@ -1681,25 +1838,7 @@ ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true)); NewGlobal->takeName(G); G->eraseFromParent(); - G = NewGlobal; - - if (UseComdatMetadata) { - // Get or create a COMDAT for G so that we can use it with our metadata. - Comdat *C = G->getComdat(); - if (!C) { - if (!G->hasName()) { - // If G is unnamed, it must be internal. Give it an artificial name - // so we can put it in a comdat. - assert(G->hasLocalLinkage()); - G->setName(Twine(kAsanGenPrefix) + "_anon_global"); - } - C = M.getOrInsertComdat(G->getName()); - // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF. - if (TargetTriple.isOSBinFormatCOFF()) - C->setSelectionKind(Comdat::NoDuplicates); - G->setComdat(C); - } - } + NewGlobals[i] = NewGlobal; Constant *SourceLoc; if (!MD.SourceLoc.empty()) { @@ -1750,117 +1889,21 @@ DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n"); - // If we aren't using separate metadata globals, add it to the initializer - // list and continue. - if (UseMetadataArray) { - Initializers[i] = Initializer; - continue; - } - - // Create a separate metadata global and put it in the appropriate ASan - // global registration section. - GlobalVariable *Metadata = new GlobalVariable( - M, GlobalStructTy, false, GlobalVariable::InternalLinkage, - Initializer, Twine("__asan_global_") + - GlobalValue::getRealLinkageName(G->getName())); - Metadata->setSection(getGlobalMetadataSection()); - - // We don't want any padding, but we also need a reasonable alignment. - // The MSVC linker always inserts padding when linking incrementally. We - // cope with that by aligning each struct to its size, which must be a power - // of two. - Metadata->setAlignment(SizeOfGlobalStruct); - - // On platforms that support comdats, put the metadata and the - // instrumented global in the same group. This ensures that the metadata - // is discarded if the instrumented global is discarded. - if (UseComdatMetadata) { - assert(G->hasComdat()); - Metadata->setComdat(G->getComdat()); - continue; - } - assert(UseMachOGlobalsSection); + Initializers[i] = Initializer; + } - // On recent Mach-O platforms, we emit the global metadata in a way that - // allows the linker to properly strip dead globals. - auto LivenessBinder = ConstantStruct::get( - LivenessTy, Initializer->getAggregateElement(0u), - ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr); - GlobalVariable *Liveness = new GlobalVariable( - M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder, - Twine("__asan_binder_") + G->getName()); - Liveness->setSection("__DATA,__asan_liveness,regular,live_support"); - LivenessGlobals[i] = Liveness; + if (TargetTriple.isOSBinFormatCOFF()) { + InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers); + } else if (ShouldUseMachOGlobalsSection()) { + InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers); + } else { + InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers); } // Create calls for poisoning before initializers run and unpoisoning after. if (HasDynamicallyInitializedGlobals) createInitializerPoisonCalls(M, ModuleName); - // Platforms with a dedicated metadata section don't need to emit any more - // code. - if (UseComdatMetadata) - return true; - - GlobalVariable *AllGlobals = nullptr; - GlobalVariable *RegisteredFlag = nullptr; - - if (UseMachOGlobalsSection) { - // RegisteredFlag serves two purposes. First, we can pass it to dladdr() - // to look up the loaded image that contains it. Second, we can store in it - // whether registration has already occurred, to prevent duplicate - // registration. - // - // common linkage ensures that there is only one global per shared library. - RegisteredFlag = new GlobalVariable( - M, IntptrTy, false, GlobalVariable::CommonLinkage, - ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName); - RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility); - - // Update llvm.compiler.used, adding the new liveness globals. This is - // needed so that during LTO these variables stay alive. The alternative - // would be to have the linker handling the LTO symbols, but libLTO - // current API does not expose access to the section for each symbol. - if (!LivenessGlobals.empty()) - appendToCompilerUsed(M, LivenessGlobals); - } else if (UseMetadataArray) { - // On platforms that don't have a custom metadata section, we emit an array - // of global metadata structures. - ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n); - AllGlobals = new GlobalVariable( - M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage, - ConstantArray::get(ArrayOfGlobalStructTy, Initializers), ""); - } - - // Create a call to register the globals with the runtime. - if (UseMachOGlobalsSection) { - IRB.CreateCall(AsanRegisterImageGlobals, - {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)}); - } else { - IRB.CreateCall(AsanRegisterGlobals, - {IRB.CreatePointerCast(AllGlobals, IntptrTy), - ConstantInt::get(IntptrTy, n)}); - } - - // We also need to unregister globals at the end, e.g., when a shared library - // gets closed. - Function *AsanDtorFunction = - Function::Create(FunctionType::get(Type::getVoidTy(*C), false), - GlobalValue::InternalLinkage, kAsanModuleDtorName, &M); - BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction); - IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB)); - - if (UseMachOGlobalsSection) { - IRB_Dtor.CreateCall(AsanUnregisterImageGlobals, - {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)}); - } else { - IRB_Dtor.CreateCall(AsanUnregisterGlobals, - {IRB.CreatePointerCast(AllGlobals, IntptrTy), - ConstantInt::get(IntptrTy, n)}); - } - - appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority); - DEBUG(dbgs() << M); return true; } Index: test/Instrumentation/AddressSanitizer/global_metadata_darwin.ll =================================================================== --- test/Instrumentation/AddressSanitizer/global_metadata_darwin.ll +++ test/Instrumentation/AddressSanitizer/global_metadata_darwin.ll @@ -21,13 +21,12 @@ ; Find the liveness binder for @global and its metadata: ; CHECK: @__asan_binder_global = internal global {{.*}} @global {{.*}} [[METADATA]] {{.*}} section "__DATA,__asan_liveness,regular,live_support" -; Test that there is the flag global variable: -; CHECK: @__asan_globals_registered = common hidden global i64 0 - ; The binder has to be inserted to llvm.compiler.used to avoid being stripped ; during LTO. ; CHECK: @llvm.compiler.used {{.*}} @__asan_binder_global {{.*}} section "llvm.metadata" +; Test that there is the flag global variable: +; CHECK: @__asan_globals_registered = common hidden global i64 0 ; Test that __asan_register_image_globals is invoked from the constructor: ; CHECK-LABEL: define internal void @asan.module_ctor