diff options
Diffstat (limited to 'llvm')
3 files changed, 61 insertions, 10 deletions
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp index b866958e3c4..8ee02dc8321 100644 --- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp +++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp @@ -270,6 +270,13 @@ static cl::opt<bool> "code stripping of globals"), cl::Hidden, cl::init(true)); +// This is on by default even though there is a bug in gold: +// https://sourceware.org/bugzilla/show_bug.cgi?id=19002 +static cl::opt<bool> + ClWithComdat("asan-with-comdat", + cl::desc("Place ASan constructors in comdat sections"), + cl::Hidden, cl::init(true)); + // Debug flags. static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden, cl::init(0)); @@ -607,7 +614,7 @@ public: private: void initializeCallbacks(Module &M); - bool InstrumentGlobals(IRBuilder<> &IRB, Module &M); + bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat); void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals, ArrayRef<Constant *> MetadataInitializers); @@ -647,6 +654,9 @@ private: Function *AsanUnregisterGlobals; Function *AsanRegisterImageGlobals; Function *AsanUnregisterImageGlobals; + + Function *AsanCtorFunction = nullptr; + Function *AsanDtorFunction = nullptr; }; // Stack poisoning does not play well with exception handling. @@ -1431,8 +1441,13 @@ void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit, void AddressSanitizerModule::createInitializerPoisonCalls( Module &M, GlobalValue *ModuleName) { GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors"); + if (!GV) + return; + + ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer()); + if (!CA) + return; - ConstantArray *CA = cast<ConstantArray>(GV->getInitializer()); for (Use &OP : CA->operands()) { if (isa<ConstantAggregateZero>(OP)) continue; ConstantStruct *CS = cast<ConstantStruct>(OP); @@ -1636,11 +1651,10 @@ AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer, } IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) { - Function *AsanDtorFunction = + 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)); } @@ -1756,7 +1770,10 @@ void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray( // 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. -bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) { +// Sets *CtorComdat to true if the global registration code emitted into the +// asan constructor is comdat-compatible. +bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat) { + *CtorComdat = false; GlobalsMD.init(M); SmallVector<GlobalVariable *, 16> GlobalsToChange; @@ -1766,7 +1783,10 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) { } size_t n = GlobalsToChange.size(); - if (n == 0) return false; + if (n == 0) { + *CtorComdat = true; + return false; + } auto &DL = M.getDataLayout(); @@ -1938,17 +1958,36 @@ bool AddressSanitizerModule::runOnModule(Module &M) { if (CompileKernel) return false; - Function *AsanCtorFunction; + // Create a module constructor. A destructor is created lazily because not all + // platforms, and not all modules need it. std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions( M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName); - appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); + bool CtorComdat = true; bool Changed = false; // TODO(glider): temporarily disabled globals instrumentation for KASan. if (ClGlobals) { IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator()); - Changed |= InstrumentGlobals(IRB, M); + Changed |= InstrumentGlobals(IRB, M, &CtorComdat); + } + + // Put the constructor and destructor in comdat if both + // (1) global instrumentation is not TU-specific + // (2) target is ELF. + if (ClWithComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) { + AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName)); + appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority, + AsanCtorFunction); + if (AsanDtorFunction) { + AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName)); + appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority, + AsanDtorFunction); + } + } else { + appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); + if (AsanDtorFunction) + appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority); } return Changed; diff --git a/llvm/test/Instrumentation/AddressSanitizer/instrument_global.ll b/llvm/test/Instrumentation/AddressSanitizer/instrument_global.ll index 7df3d22dcde..cddb4aaca3b 100644 --- a/llvm/test/Instrumentation/AddressSanitizer/instrument_global.ll +++ b/llvm/test/Instrumentation/AddressSanitizer/instrument_global.ll @@ -6,8 +6,8 @@ target triple = "x86_64-unknown-linux-gnu" ; If a global is present, __asan_[un]register_globals should be called from ; module ctor/dtor -; CHECK: llvm.global_ctors ; CHECK: @__asan_gen_ = private constant [8 x i8] c"<stdin>\00", align 1 +; CHECK: llvm.global_ctors ; CHECK: llvm.global_dtors ; Test that we don't instrument global arrays with static initializer diff --git a/llvm/test/Instrumentation/AddressSanitizer/no-globals.ll b/llvm/test/Instrumentation/AddressSanitizer/no-globals.ll new file mode 100644 index 00000000000..e75b91c93d9 --- /dev/null +++ b/llvm/test/Instrumentation/AddressSanitizer/no-globals.ll @@ -0,0 +1,12 @@ +; A module with no asan-instrumented globals has no asan destructor, and has an asan constructor in a comdat. +; RUN: opt -mtriple=x86_64-unknown-linux-gnu < %s -asan -asan-module -asan-with-comdat=1 -S | FileCheck %s + +define void @f() { + ret void +} + +; CHECK-NOT: @llvm.global_dtors +; CHECK: @llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 1, void ()* @asan.module_ctor, i8* bitcast (void ()* @asan.module_ctor to i8*) }] +; CHECK-NOT: @llvm.global_dtors +; CHECK: define internal void @asan.module_ctor() comdat +; CHECK-NOT: @llvm.global_dtors |
