#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/FunctionAttrs.h"
#include "llvm/Transforms/Utils/Cloning.h"
-#include "llvm/Transforms/Utils/ModuleUtils.h"
using namespace llvm;
namespace {
+// Produce a unique identifier for this module by taking the MD5 sum of the
+// names of the module's strong external symbols. This identifier is
+// normally guaranteed to be unique, or the program would fail to link due to
+// multiply defined symbols.
+//
+// If the module has no strong external symbols (such a module may still have a
+// semantic effect if it performs global initialization), we cannot produce a
+// unique identifier for this module, so we return the empty string, which
+// causes the entire module to be written as a regular LTO module.
+std::string getModuleId(Module *M) {
+ MD5 Md5;
+ bool ExportsSymbols = false;
+ for (auto &GV : M->global_values()) {
+ if (GV.isDeclaration() || GV.getName().startswith("llvm.") ||
+ !GV.hasExternalLinkage())
+ continue;
+ ExportsSymbols = true;
+ Md5.update(GV.getName());
+ Md5.update(ArrayRef<uint8_t>{0});
+ }
+
+ if (!ExportsSymbols)
+ return "";
+
+ MD5::MD5Result R;
+ Md5.final(R);
+
+ SmallString<32> Str;
+ MD5::stringifyResult(R, Str);
+ return ("$" + Str).str();
+}
+
// Promote each local-linkage entity defined by ExportM and used by ImportM by
// changing visibility and appending the given ModuleId.
void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId) {
void splitAndWriteThinLTOBitcode(
raw_ostream &OS, raw_ostream *ThinLinkOS,
function_ref<AAResults &(Function &)> AARGetter, Module &M) {
- std::string ModuleId = getUniqueModuleId(&M);
+ std::string ModuleId = getModuleId(&M);
if (ModuleId.empty()) {
// We couldn't generate a module ID for this module, just write it out as a
// regular LTO module.
"__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";
"__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";
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);
GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
StringRef OriginalName);
- void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
- StringRef InternalSuffix);
+ void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata);
IRBuilder<> CreateAsanModuleDtor(Module &M);
bool ShouldInstrumentGlobal(GlobalVariable *G);
Function *AsanUnregisterGlobals;
Function *AsanRegisterImageGlobals;
Function *AsanUnregisterImageGlobals;
- Function *AsanRegisterElfGlobals;
- Function *AsanUnregisterElfGlobals;
Function *AsanCtorFunction = nullptr;
Function *AsanDtorFunction = nullptr;
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
-
- AsanRegisterElfGlobals = checkSanitizerInterfaceFunction(
- M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
- IntptrTy, IntptrTy, IntptrTy, nullptr));
- AsanRegisterElfGlobals->setLinkage(Function::ExternalLinkage);
-
- AsanUnregisterElfGlobals = checkSanitizerInterfaceFunction(
- M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
- IntptrTy, IntptrTy, IntptrTy, nullptr));
- 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, StringRef InternalSuffix) {
+ GlobalVariable *G, GlobalVariable *Metadata) {
Module &M = *G->getParent();
Comdat *C = G->getComdat();
if (!C) {
assert(G->hasLocalLinkage());
G->setName(Twine(kAsanGenPrefix) + "_anon_global");
}
-
- if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
- std::string Name = G->getName();
- Name += InternalSuffix;
- C = M.getOrInsertComdat(Name);
- } else {
- C = M.getOrInsertComdat(G->getName());
- }
-
+ C = M.getOrInsertComdat(G->getName());
// Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
if (TargetTriple.isOSBinFormatCOFF())
C->setSelectionKind(Comdat::NoDuplicates);
"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) {
Initializers[i] = Initializer;
}
- std::string ELFUniqueModuleId =
- TargetTriple.isOSBinFormatELF() ? getUniqueModuleId(&M) : "";
-
- if (!ELFUniqueModuleId.empty()) {
- InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
- *CtorComdat = true;
- } else if (TargetTriple.isOSBinFormatCOFF()) {
+ if (TargetTriple.isOSBinFormatCOFF()) {
InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
} else if (ShouldUseMachOGlobalsSection()) {
InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_asan_globals.cpp, i8* null }]
; Check that globals were instrumented:
-
-; CHECK: @global = global { i32, [60 x i8] } zeroinitializer, comdat, align 32
-; CHECK: @.str = internal unnamed_addr constant { [14 x i8], [50 x i8] } { [14 x i8] c"Hello, world!\00", [50 x i8] zeroinitializer }, comdat($".str${{[01-9a-f]+}}"), align 32
+; CHECK: @global = global { i32, [60 x i8] } zeroinitializer, align 32
+; CHECK: @.str = internal unnamed_addr constant { [14 x i8], [50 x i8] } { [14 x i8] c"Hello, world!\00", [50 x i8] zeroinitializer }, align 32
; Check emitted location descriptions:
; CHECK: [[VARNAME:@__asan_gen_.[0-9]+]] = private unnamed_addr constant [7 x i8] c"global\00", align 1
; CHECK: [[FILENAME:@__asan_gen_.[0-9]+]] = private unnamed_addr constant [22 x i8] c"/tmp/asan-globals.cpp\00", align 1
; CHECK: [[LOCDESCR:@__asan_gen_.[0-9]+]] = private unnamed_addr constant { [22 x i8]*, i32, i32 } { [22 x i8]* [[FILENAME]], i32 5, i32 5 }
-; CHECK: @__asan_global_global = {{.*}}i64 ptrtoint ({ i32, [60 x i8] }* @global to i64){{.*}} section "asan_globals"{{.*}}, !associated
-; CHECK: @__asan_global_.str = {{.*}}i64 ptrtoint ({ [14 x i8], [50 x i8] }* @.str to i64){{.*}} section "asan_globals"{{.*}}, !associated
-
-; The metadata has to be inserted to llvm.compiler.used to avoid being stripped
-; during LTO.
-; CHECK: @llvm.compiler.used {{.*}} @__asan_global_global {{.*}} section "llvm.metadata"
; Check that location descriptors and global names were passed into __asan_register_globals:
-; CHECK: call void @__asan_register_elf_globals(i64 ptrtoint (i64* @___asan_globals_registered to i64), i64 ptrtoint (i64* @__start_asan_globals to i64), i64 ptrtoint (i64* @__stop_asan_globals to i64))
+; CHECK: i64 ptrtoint ([7 x i8]* [[VARNAME]] to i64)
+; CHECK: i64 ptrtoint ({ [22 x i8]*, i32, i32 }* [[LOCDESCR]] to i64)
; Function Attrs: nounwind sanitize_address
define internal void @__cxx_global_var_init() #0 section ".text.startup" {
projects / llvm / commitdiff