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Diffstat (limited to 'lib/Transforms/Instrumentation/AddressSanitizer.cpp')
-rw-r--r--lib/Transforms/Instrumentation/AddressSanitizer.cpp169
1 files changed, 153 insertions, 16 deletions
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index b866958e3c4b..b034ccc46933 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -101,6 +101,10 @@ static const char *const kAsanRegisterImageGlobalsName =
"__asan_register_image_globals";
static const char *const kAsanUnregisterImageGlobalsName =
"__asan_unregister_image_globals";
+static const char *const kAsanRegisterElfGlobalsName =
+ "__asan_register_elf_globals";
+static const char *const kAsanUnregisterElfGlobalsName =
+ "__asan_unregister_elf_globals";
static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
static const char *const kAsanInitName = "__asan_init";
@@ -120,8 +124,11 @@ static const char *const kAsanPoisonStackMemoryName =
"__asan_poison_stack_memory";
static const char *const kAsanUnpoisonStackMemoryName =
"__asan_unpoison_stack_memory";
+
+// ASan version script has __asan_* wildcard. Triple underscore prevents a
+// linker (gold) warning about attempting to export a local symbol.
static const char *const kAsanGlobalsRegisteredFlagName =
- "__asan_globals_registered";
+ "___asan_globals_registered";
static const char *const kAsanOptionDetectUseAfterReturn =
"__asan_option_detect_stack_use_after_return";
@@ -270,6 +277,13 @@ 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));
@@ -607,10 +621,14 @@ 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);
+ void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
+ ArrayRef<GlobalVariable *> ExtendedGlobals,
+ ArrayRef<Constant *> MetadataInitializers,
+ const std::string &UniqueModuleId);
void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers);
@@ -621,7 +639,8 @@ private:
GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
StringRef OriginalName);
- void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata);
+ void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
+ StringRef InternalSuffix);
IRBuilder<> CreateAsanModuleDtor(Module &M);
bool ShouldInstrumentGlobal(GlobalVariable *G);
@@ -647,6 +666,11 @@ private:
Function *AsanUnregisterGlobals;
Function *AsanRegisterImageGlobals;
Function *AsanUnregisterImageGlobals;
+ Function *AsanRegisterElfGlobals;
+ Function *AsanUnregisterElfGlobals;
+
+ Function *AsanCtorFunction = nullptr;
+ Function *AsanDtorFunction = nullptr;
};
// Stack poisoning does not play well with exception handling.
@@ -1431,8 +1455,13 @@ 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);
@@ -1594,12 +1623,22 @@ void AddressSanitizerModule::initializeCallbacks(Module &M) {
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy));
AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
+
+ AsanRegisterElfGlobals = checkSanitizerInterfaceFunction(
+ M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
+ IntptrTy, IntptrTy, IntptrTy));
+ AsanRegisterElfGlobals->setLinkage(Function::ExternalLinkage);
+
+ AsanUnregisterElfGlobals = checkSanitizerInterfaceFunction(
+ M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
+ IntptrTy, IntptrTy, IntptrTy));
+ AsanUnregisterElfGlobals->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) {
+ GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
Module &M = *G->getParent();
Comdat *C = G->getComdat();
if (!C) {
@@ -1609,7 +1648,15 @@ void AddressSanitizerModule::SetComdatForGlobalMetadata(
assert(G->hasLocalLinkage());
G->setName(Twine(kAsanGenPrefix) + "_anon_global");
}
- C = M.getOrInsertComdat(G->getName());
+
+ if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
+ std::string Name = G->getName();
+ Name += InternalSuffix;
+ C = M.getOrInsertComdat(Name);
+ } else {
+ C = M.getOrInsertComdat(G->getName());
+ }
+
// Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
if (TargetTriple.isOSBinFormatCOFF())
C->setSelectionKind(Comdat::NoDuplicates);
@@ -1636,11 +1683,10 @@ 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));
}
@@ -1665,10 +1711,69 @@ void AddressSanitizerModule::InstrumentGlobalsCOFF(
"global metadata will not be padded appropriately");
Metadata->setAlignment(SizeOfGlobalStruct);
- SetComdatForGlobalMetadata(G, Metadata);
+ SetComdatForGlobalMetadata(G, Metadata, "");
}
}
+void AddressSanitizerModule::InstrumentGlobalsELF(
+ IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
+ ArrayRef<Constant *> MetadataInitializers,
+ const std::string &UniqueModuleId) {
+ assert(ExtendedGlobals.size() == MetadataInitializers.size());
+
+ SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
+ for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
+ GlobalVariable *G = ExtendedGlobals[i];
+ GlobalVariable *Metadata =
+ CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
+ MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
+ Metadata->setMetadata(LLVMContext::MD_associated, MD);
+ MetadataGlobals[i] = Metadata;
+
+ SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
+ }
+
+ // Update llvm.compiler.used, adding the new metadata globals. This is
+ // needed so that during LTO these variables stay alive.
+ if (!MetadataGlobals.empty())
+ appendToCompilerUsed(M, MetadataGlobals);
+
+ // 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);
+
+ // Create start and stop symbols.
+ GlobalVariable *StartELFMetadata = new GlobalVariable(
+ M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
+ "__start_" + getGlobalMetadataSection());
+ StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
+ GlobalVariable *StopELFMetadata = new GlobalVariable(
+ M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
+ "__stop_" + getGlobalMetadataSection());
+ StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
+
+ // Create a call to register the globals with the runtime.
+ IRB.CreateCall(AsanRegisterElfGlobals,
+ {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
+ IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
+ IRB.CreatePointerCast(StopELFMetadata, 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(AsanUnregisterElfGlobals,
+ {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
+ IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
+ IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
+}
+
void AddressSanitizerModule::InstrumentGlobalsMachO(
IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers) {
@@ -1756,7 +1861,10 @@ 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 +1874,10 @@ 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();
@@ -1911,7 +2022,14 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
Initializers[i] = Initializer;
}
- if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
+ std::string ELFUniqueModuleId =
+ (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
+ : "";
+
+ if (!ELFUniqueModuleId.empty()) {
+ InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
+ *CtorComdat = true;
+ } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
} else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
@@ -1938,17 +2056,36 @@ 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;
@@ -2586,7 +2723,7 @@ void FunctionStackPoisoner::processStaticAllocas() {
Value *NewAllocaPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
AI->getType());
- replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/false);
+ replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, DIExpression::NoDeref);
AI->replaceAllUsesWith(NewAllocaPtr);
}
generated by cgit v1.3 (git 2.53.0) at 2026-07-24 21:30:58 +0000