1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "asan"
18 #include "BlackList.h"
19 #include "llvm/Function.h"
20 #include "llvm/IRBuilder.h"
21 #include "llvm/InlineAsm.h"
22 #include "llvm/IntrinsicInst.h"
23 #include "llvm/LLVMContext.h"
24 #include "llvm/Module.h"
25 #include "llvm/Type.h"
26 #include "llvm/ADT/ArrayRef.h"
27 #include "llvm/ADT/OwningPtr.h"
28 #include "llvm/ADT/SmallSet.h"
29 #include "llvm/ADT/SmallString.h"
30 #include "llvm/ADT/SmallVector.h"
31 #include "llvm/ADT/StringExtras.h"
32 #include "llvm/ADT/Triple.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/DataTypes.h"
35 #include "llvm/Support/Debug.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Support/system_error.h"
38 #include "llvm/DataLayout.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "llvm/Transforms/Instrumentation.h"
41 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
42 #include "llvm/Transforms/Utils/ModuleUtils.h"
49 static const uint64_t kDefaultShadowScale = 3;
50 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
51 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
52 static const uint64_t kDefaultShadowOffsetAndroid = 0;
54 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
55 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
56 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
58 static const char *kAsanModuleCtorName = "asan.module_ctor";
59 static const char *kAsanModuleDtorName = "asan.module_dtor";
60 static const int kAsanCtorAndCtorPriority = 1;
61 static const char *kAsanReportErrorTemplate = "__asan_report_";
62 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
63 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
64 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
65 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
66 static const char *kAsanInitName = "__asan_init";
67 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
68 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
69 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
70 static const char *kAsanStackMallocName = "__asan_stack_malloc";
71 static const char *kAsanStackFreeName = "__asan_stack_free";
72 static const char *kAsanGenPrefix = "__asan_gen_";
74 static const int kAsanStackLeftRedzoneMagic = 0xf1;
75 static const int kAsanStackMidRedzoneMagic = 0xf2;
76 static const int kAsanStackRightRedzoneMagic = 0xf3;
77 static const int kAsanStackPartialRedzoneMagic = 0xf4;
79 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
80 static const size_t kNumberOfAccessSizes = 5;
82 // Command-line flags.
84 // This flag may need to be replaced with -f[no-]asan-reads.
85 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
86 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
87 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
88 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
89 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
90 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
91 cl::Hidden, cl::init(true));
92 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
93 cl::desc("use instrumentation with slow path for all accesses"),
94 cl::Hidden, cl::init(false));
95 // This flag limits the number of instructions to be instrumented
96 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
97 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
99 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
101 cl::desc("maximal number of instructions to instrument in any given BB"),
103 // This flag may need to be replaced with -f[no]asan-stack.
104 static cl::opt<bool> ClStack("asan-stack",
105 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
106 // This flag may need to be replaced with -f[no]asan-use-after-return.
107 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
108 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
109 // This flag may need to be replaced with -f[no]asan-globals.
110 static cl::opt<bool> ClGlobals("asan-globals",
111 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
112 static cl::opt<bool> ClInitializers("asan-initialization-order",
113 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
114 static cl::opt<bool> ClMemIntrin("asan-memintrin",
115 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
116 // This flag may need to be replaced with -fasan-blacklist.
117 static cl::opt<std::string> ClBlackListFile("asan-blacklist",
118 cl::desc("File containing the list of functions to ignore "
119 "during instrumentation"), cl::Hidden);
121 // These flags allow to change the shadow mapping.
122 // The shadow mapping looks like
123 // Shadow = (Mem >> scale) + (1 << offset_log)
124 static cl::opt<int> ClMappingScale("asan-mapping-scale",
125 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
126 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
127 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
129 // Optimization flags. Not user visible, used mostly for testing
130 // and benchmarking the tool.
131 static cl::opt<bool> ClOpt("asan-opt",
132 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
133 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
134 cl::desc("Instrument the same temp just once"), cl::Hidden,
136 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
137 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
140 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
142 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
143 cl::Hidden, cl::init(0));
144 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
145 cl::Hidden, cl::desc("Debug func"));
146 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
147 cl::Hidden, cl::init(-1));
148 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
149 cl::Hidden, cl::init(-1));
152 /// A set of dynamically initialized globals extracted from metadata.
153 class SetOfDynamicallyInitializedGlobals {
155 void Init(Module& M) {
156 // Clang generates metadata identifying all dynamically initialized globals.
157 NamedMDNode *DynamicGlobals =
158 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
161 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
162 MDNode *MDN = DynamicGlobals->getOperand(i);
163 assert(MDN->getNumOperands() == 1);
164 Value *VG = MDN->getOperand(0);
165 // The optimizer may optimize away a global entirely, in which case we
166 // cannot instrument access to it.
169 DynInitGlobals.insert(cast<GlobalVariable>(VG));
172 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
174 SmallSet<GlobalValue*, 32> DynInitGlobals;
177 static int MappingScale() {
178 return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
181 static size_t RedzoneSize() {
182 // Redzone used for stack and globals is at least 32 bytes.
183 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
184 return std::max(32U, 1U << MappingScale());
187 /// AddressSanitizer: instrument the code in module to find memory bugs.
188 struct AddressSanitizer : public FunctionPass {
190 virtual const char *getPassName() const {
191 return "AddressSanitizerFunctionPass";
193 void instrumentMop(Instruction *I);
194 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
195 Value *Addr, uint32_t TypeSize, bool IsWrite);
196 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
197 Value *ShadowValue, uint32_t TypeSize);
198 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
199 bool IsWrite, size_t AccessSizeIndex);
200 bool instrumentMemIntrinsic(MemIntrinsic *MI);
201 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
203 Instruction *InsertBefore, bool IsWrite);
204 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
205 bool runOnFunction(Function &F);
206 void createInitializerPoisonCalls(Module &M,
207 Value *FirstAddr, Value *LastAddr);
208 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
209 bool poisonStackInFunction(Function &F);
210 virtual bool doInitialization(Module &M);
211 static char ID; // Pass identification, replacement for typeid
214 void initializeCallbacks(Module &M);
215 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
216 Type *Ty = AI->getAllocatedType();
217 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
220 uint64_t getAlignedSize(uint64_t SizeInBytes) {
221 size_t RZ = RedzoneSize();
222 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
224 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
225 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
226 return getAlignedSize(SizeInBytes);
229 bool ShouldInstrumentGlobal(GlobalVariable *G);
230 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
231 Value *ShadowBase, bool DoPoison);
232 bool LooksLikeCodeInBug11395(Instruction *I);
233 void FindDynamicInitializers(Module &M);
237 uint64_t MappingOffset;
241 Function *AsanCtorFunction;
242 Function *AsanInitFunction;
243 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
244 Function *AsanHandleNoReturnFunc;
245 OwningPtr<BlackList> BL;
246 // This array is indexed by AccessIsWrite and log2(AccessSize).
247 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
249 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
252 class AddressSanitizerModule : public ModulePass {
254 bool runOnModule(Module &M);
255 static char ID; // Pass identification, replacement for typeid
256 AddressSanitizerModule() : ModulePass(ID) { }
257 virtual const char *getPassName() const {
258 return "AddressSanitizerModule";
261 bool ShouldInstrumentGlobal(GlobalVariable *G);
262 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
265 OwningPtr<BlackList> BL;
266 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
274 char AddressSanitizer::ID = 0;
275 INITIALIZE_PASS(AddressSanitizer, "asan",
276 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
278 AddressSanitizer::AddressSanitizer() : FunctionPass(ID) { }
279 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
280 return new AddressSanitizer();
283 char AddressSanitizerModule::ID = 0;
284 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
285 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
286 "ModulePass", false, false)
287 ModulePass *llvm::createAddressSanitizerModulePass() {
288 return new AddressSanitizerModule();
291 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
292 size_t Res = CountTrailingZeros_32(TypeSize / 8);
293 assert(Res < kNumberOfAccessSizes);
297 // Create a constant for Str so that we can pass it to the run-time lib.
298 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
299 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
300 return new GlobalVariable(M, StrConst->getType(), true,
301 GlobalValue::PrivateLinkage, StrConst,
305 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
306 return G->getName().find(kAsanGenPrefix) == 0;
309 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
311 Shadow = IRB.CreateLShr(Shadow, MappingScale());
312 if (MappingOffset == 0)
314 // (Shadow >> scale) | offset
315 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
319 void AddressSanitizer::instrumentMemIntrinsicParam(
320 Instruction *OrigIns,
321 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
322 // Check the first byte.
324 IRBuilder<> IRB(InsertBefore);
325 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
327 // Check the last byte.
329 IRBuilder<> IRB(InsertBefore);
330 Value *SizeMinusOne = IRB.CreateSub(
331 Size, ConstantInt::get(Size->getType(), 1));
332 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
333 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
334 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
335 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
339 // Instrument memset/memmove/memcpy
340 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
341 Value *Dst = MI->getDest();
342 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
343 Value *Src = MemTran ? MemTran->getSource() : 0;
344 Value *Length = MI->getLength();
346 Constant *ConstLength = dyn_cast<Constant>(Length);
347 Instruction *InsertBefore = MI;
349 if (ConstLength->isNullValue()) return false;
351 // The size is not a constant so it could be zero -- check at run-time.
352 IRBuilder<> IRB(InsertBefore);
354 Value *Cmp = IRB.CreateICmpNE(Length,
355 Constant::getNullValue(Length->getType()));
356 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
359 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
361 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
365 // If I is an interesting memory access, return the PointerOperand
366 // and set IsWrite. Otherwise return NULL.
367 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
368 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
369 if (!ClInstrumentReads) return NULL;
371 return LI->getPointerOperand();
373 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
374 if (!ClInstrumentWrites) return NULL;
376 return SI->getPointerOperand();
378 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
379 if (!ClInstrumentAtomics) return NULL;
381 return RMW->getPointerOperand();
383 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
384 if (!ClInstrumentAtomics) return NULL;
386 return XCHG->getPointerOperand();
391 void AddressSanitizer::instrumentMop(Instruction *I) {
392 bool IsWrite = false;
393 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
395 if (ClOpt && ClOptGlobals) {
396 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
397 // If initialization order checking is disabled, a simple access to a
398 // dynamically initialized global is always valid.
401 // If a global variable does not have dynamic initialization we don't
402 // have to instrument it. However, if a global does not have initailizer
403 // at all, we assume it has dynamic initializer (in other TU).
404 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
409 Type *OrigPtrTy = Addr->getType();
410 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
412 assert(OrigTy->isSized());
413 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
415 if (TypeSize != 8 && TypeSize != 16 &&
416 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
417 // Ignore all unusual sizes.
422 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
425 // Validate the result of Module::getOrInsertFunction called for an interface
426 // function of AddressSanitizer. If the instrumented module defines a function
427 // with the same name, their prototypes must match, otherwise
428 // getOrInsertFunction returns a bitcast.
429 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
430 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
431 FuncOrBitcast->dump();
432 report_fatal_error("trying to redefine an AddressSanitizer "
433 "interface function");
436 Instruction *AddressSanitizer::generateCrashCode(
437 Instruction *InsertBefore, Value *Addr,
438 bool IsWrite, size_t AccessSizeIndex) {
439 IRBuilder<> IRB(InsertBefore);
440 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
442 // We don't do Call->setDoesNotReturn() because the BB already has
443 // UnreachableInst at the end.
444 // This EmptyAsm is required to avoid callback merge.
445 IRB.CreateCall(EmptyAsm);
449 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
452 size_t Granularity = 1 << MappingScale();
453 // Addr & (Granularity - 1)
454 Value *LastAccessedByte = IRB.CreateAnd(
455 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
456 // (Addr & (Granularity - 1)) + size - 1
457 if (TypeSize / 8 > 1)
458 LastAccessedByte = IRB.CreateAdd(
459 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
460 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
461 LastAccessedByte = IRB.CreateIntCast(
462 LastAccessedByte, ShadowValue->getType(), false);
463 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
464 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
467 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
468 IRBuilder<> &IRB, Value *Addr,
469 uint32_t TypeSize, bool IsWrite) {
470 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
472 Type *ShadowTy = IntegerType::get(
473 *C, std::max(8U, TypeSize >> MappingScale()));
474 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
475 Value *ShadowPtr = memToShadow(AddrLong, IRB);
476 Value *CmpVal = Constant::getNullValue(ShadowTy);
477 Value *ShadowValue = IRB.CreateLoad(
478 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
480 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
481 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
482 size_t Granularity = 1 << MappingScale();
483 TerminatorInst *CrashTerm = 0;
485 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
486 TerminatorInst *CheckTerm =
487 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
488 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
489 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
490 IRB.SetInsertPoint(CheckTerm);
491 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
492 BasicBlock *CrashBlock =
493 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
494 CrashTerm = new UnreachableInst(*C, CrashBlock);
495 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
496 ReplaceInstWithInst(CheckTerm, NewTerm);
498 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
502 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
503 Crash->setDebugLoc(OrigIns->getDebugLoc());
506 void AddressSanitizerModule::createInitializerPoisonCalls(
507 Module &M, Value *FirstAddr, Value *LastAddr) {
508 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
509 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
510 // If that function is not present, this TU contains no globals, or they have
511 // all been optimized away
515 // Set up the arguments to our poison/unpoison functions.
516 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
518 // Declare our poisoning and unpoisoning functions.
519 Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
520 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
521 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
522 Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
523 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
524 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
526 // Add a call to poison all external globals before the given function starts.
527 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
529 // Add calls to unpoison all globals before each return instruction.
530 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
532 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
533 CallInst::Create(AsanUnpoisonGlobals, "", RI);
538 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
539 Type *Ty = cast<PointerType>(G->getType())->getElementType();
540 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
542 if (BL->isIn(*G)) return false;
543 if (!Ty->isSized()) return false;
544 if (!G->hasInitializer()) return false;
545 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
546 // Touch only those globals that will not be defined in other modules.
547 // Don't handle ODR type linkages since other modules may be built w/o asan.
548 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
549 G->getLinkage() != GlobalVariable::PrivateLinkage &&
550 G->getLinkage() != GlobalVariable::InternalLinkage)
552 // Two problems with thread-locals:
553 // - The address of the main thread's copy can't be computed at link-time.
554 // - Need to poison all copies, not just the main thread's one.
555 if (G->isThreadLocal())
557 // For now, just ignore this Alloca if the alignment is large.
558 if (G->getAlignment() > RedzoneSize()) return false;
560 // Ignore all the globals with the names starting with "\01L_OBJC_".
561 // Many of those are put into the .cstring section. The linker compresses
562 // that section by removing the spare \0s after the string terminator, so
563 // our redzones get broken.
564 if ((G->getName().find("\01L_OBJC_") == 0) ||
565 (G->getName().find("\01l_OBJC_") == 0)) {
566 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
570 if (G->hasSection()) {
571 StringRef Section(G->getSection());
572 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
573 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
575 if ((Section.find("__OBJC,") == 0) ||
576 (Section.find("__DATA, __objc_") == 0)) {
577 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
580 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
581 // Constant CFString instances are compiled in the following way:
582 // -- the string buffer is emitted into
583 // __TEXT,__cstring,cstring_literals
584 // -- the constant NSConstantString structure referencing that buffer
585 // is placed into __DATA,__cfstring
586 // Therefore there's no point in placing redzones into __DATA,__cfstring.
587 // Moreover, it causes the linker to crash on OS X 10.7
588 if (Section.find("__DATA,__cfstring") == 0) {
589 DEBUG(dbgs() << "Ignoring CFString: " << *G);
597 // This function replaces all global variables with new variables that have
598 // trailing redzones. It also creates a function that poisons
599 // redzones and inserts this function into llvm.global_ctors.
600 bool AddressSanitizerModule::runOnModule(Module &M) {
601 if (!ClGlobals) return false;
602 TD = getAnalysisIfAvailable<DataLayout>();
605 BL.reset(new BlackList(ClBlackListFile));
606 DynamicallyInitializedGlobals.Init(M);
607 C = &(M.getContext());
608 IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
610 SmallVector<GlobalVariable *, 16> GlobalsToChange;
612 for (Module::GlobalListType::iterator G = M.global_begin(),
613 E = M.global_end(); G != E; ++G) {
614 if (ShouldInstrumentGlobal(G))
615 GlobalsToChange.push_back(G);
618 size_t n = GlobalsToChange.size();
619 if (n == 0) return false;
621 // A global is described by a structure
624 // size_t size_with_redzone;
626 // size_t has_dynamic_init;
627 // We initialize an array of such structures and pass it to a run-time call.
628 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
631 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
634 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
636 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
638 // The addresses of the first and last dynamically initialized globals in
639 // this TU. Used in initialization order checking.
640 Value *FirstDynamic = 0, *LastDynamic = 0;
642 for (size_t i = 0; i < n; i++) {
643 GlobalVariable *G = GlobalsToChange[i];
644 PointerType *PtrTy = cast<PointerType>(G->getType());
645 Type *Ty = PtrTy->getElementType();
646 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
647 size_t RZ = RedzoneSize();
648 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
649 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
650 // Determine whether this global should be poisoned in initialization.
651 bool GlobalHasDynamicInitializer =
652 DynamicallyInitializedGlobals.Contains(G);
653 // Don't check initialization order if this global is blacklisted.
654 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
656 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
657 Constant *NewInitializer = ConstantStruct::get(
658 NewTy, G->getInitializer(),
659 Constant::getNullValue(RightRedZoneTy), NULL);
661 SmallString<2048> DescriptionOfGlobal = G->getName();
662 DescriptionOfGlobal += " (";
663 DescriptionOfGlobal += M.getModuleIdentifier();
664 DescriptionOfGlobal += ")";
665 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
667 // Create a new global variable with enough space for a redzone.
668 GlobalVariable *NewGlobal = new GlobalVariable(
669 M, NewTy, G->isConstant(), G->getLinkage(),
670 NewInitializer, "", G, G->getThreadLocalMode());
671 NewGlobal->copyAttributesFrom(G);
672 NewGlobal->setAlignment(RZ);
675 Indices2[0] = IRB.getInt32(0);
676 Indices2[1] = IRB.getInt32(0);
678 G->replaceAllUsesWith(
679 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
680 NewGlobal->takeName(G);
681 G->eraseFromParent();
683 Initializers[i] = ConstantStruct::get(
685 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
686 ConstantInt::get(IntptrTy, SizeInBytes),
687 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
688 ConstantExpr::getPointerCast(Name, IntptrTy),
689 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
692 // Populate the first and last globals declared in this TU.
693 if (ClInitializers && GlobalHasDynamicInitializer) {
694 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
695 if (FirstDynamic == 0)
696 FirstDynamic = LastDynamic;
699 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
702 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
703 GlobalVariable *AllGlobals = new GlobalVariable(
704 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
705 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
707 // Create calls for poisoning before initializers run and unpoisoning after.
708 if (ClInitializers && FirstDynamic && LastDynamic)
709 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
711 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
712 kAsanRegisterGlobalsName, IRB.getVoidTy(),
713 IntptrTy, IntptrTy, NULL));
714 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
716 IRB.CreateCall2(AsanRegisterGlobals,
717 IRB.CreatePointerCast(AllGlobals, IntptrTy),
718 ConstantInt::get(IntptrTy, n));
720 // We also need to unregister globals at the end, e.g. when a shared library
722 Function *AsanDtorFunction = Function::Create(
723 FunctionType::get(Type::getVoidTy(*C), false),
724 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
725 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
726 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
727 Function *AsanUnregisterGlobals =
728 checkInterfaceFunction(M.getOrInsertFunction(
729 kAsanUnregisterGlobalsName,
730 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
731 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
733 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
734 IRB.CreatePointerCast(AllGlobals, IntptrTy),
735 ConstantInt::get(IntptrTy, n));
736 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
742 void AddressSanitizer::initializeCallbacks(Module &M) {
744 // Create __asan_report* callbacks.
745 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
746 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
748 // IsWrite and TypeSize are encoded in the function name.
749 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
750 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
751 // If we are merging crash callbacks, they have two parameters.
752 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
753 checkInterfaceFunction(M.getOrInsertFunction(
754 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
758 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
759 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
760 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
761 kAsanStackFreeName, IRB.getVoidTy(),
762 IntptrTy, IntptrTy, IntptrTy, NULL));
763 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
764 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
766 // We insert an empty inline asm after __asan_report* to avoid callback merge.
767 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
768 StringRef(""), StringRef(""),
769 /*hasSideEffects=*/true);
773 bool AddressSanitizer::doInitialization(Module &M) {
774 // Initialize the private fields. No one has accessed them before.
775 TD = getAnalysisIfAvailable<DataLayout>();
779 BL.reset(new BlackList(ClBlackListFile));
780 DynamicallyInitializedGlobals.Init(M);
782 C = &(M.getContext());
783 LongSize = TD->getPointerSizeInBits();
784 IntptrTy = Type::getIntNTy(*C, LongSize);
785 IntptrPtrTy = PointerType::get(IntptrTy, 0);
787 AsanCtorFunction = Function::Create(
788 FunctionType::get(Type::getVoidTy(*C), false),
789 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
790 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
791 // call __asan_init in the module ctor.
792 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
793 AsanInitFunction = checkInterfaceFunction(
794 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
795 AsanInitFunction->setLinkage(Function::ExternalLinkage);
796 IRB.CreateCall(AsanInitFunction);
798 llvm::Triple targetTriple(M.getTargetTriple());
799 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
801 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
802 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
803 if (ClMappingOffsetLog >= 0) {
804 if (ClMappingOffsetLog == 0) {
808 MappingOffset = 1ULL << ClMappingOffsetLog;
813 if (ClMappingOffsetLog >= 0) {
814 // Tell the run-time the current values of mapping offset and scale.
815 GlobalValue *asan_mapping_offset =
816 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
817 ConstantInt::get(IntptrTy, MappingOffset),
818 kAsanMappingOffsetName);
819 // Read the global, otherwise it may be optimized away.
820 IRB.CreateLoad(asan_mapping_offset, true);
822 if (ClMappingScale) {
823 GlobalValue *asan_mapping_scale =
824 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
825 ConstantInt::get(IntptrTy, MappingScale()),
826 kAsanMappingScaleName);
827 // Read the global, otherwise it may be optimized away.
828 IRB.CreateLoad(asan_mapping_scale, true);
831 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
836 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
837 // For each NSObject descendant having a +load method, this method is invoked
838 // by the ObjC runtime before any of the static constructors is called.
839 // Therefore we need to instrument such methods with a call to __asan_init
840 // at the beginning in order to initialize our runtime before any access to
841 // the shadow memory.
842 // We cannot just ignore these methods, because they may call other
843 // instrumented functions.
844 if (F.getName().find(" load]") != std::string::npos) {
845 IRBuilder<> IRB(F.begin()->begin());
846 IRB.CreateCall(AsanInitFunction);
852 // Check both the call and the callee for doesNotReturn().
853 static bool isNoReturnCall(CallInst *CI) {
854 if (CI->doesNotReturn()) return true;
855 Function *F = CI->getCalledFunction();
856 if (F && F->doesNotReturn()) return true;
860 bool AddressSanitizer::runOnFunction(Function &F) {
861 if (BL->isIn(F)) return false;
862 if (&F == AsanCtorFunction) return false;
863 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
864 initializeCallbacks(*F.getParent());
866 // If needed, insert __asan_init before checking for AddressSafety attr.
867 maybeInsertAsanInitAtFunctionEntry(F);
869 if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
872 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
875 // We want to instrument every address only once per basic block (unless there
876 // are calls between uses).
877 SmallSet<Value*, 16> TempsToInstrument;
878 SmallVector<Instruction*, 16> ToInstrument;
879 SmallVector<Instruction*, 8> NoReturnCalls;
882 // Fill the set of memory operations to instrument.
883 for (Function::iterator FI = F.begin(), FE = F.end();
885 TempsToInstrument.clear();
886 int NumInsnsPerBB = 0;
887 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
889 if (LooksLikeCodeInBug11395(BI)) return false;
890 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
891 if (ClOpt && ClOptSameTemp) {
892 if (!TempsToInstrument.insert(Addr))
893 continue; // We've seen this temp in the current BB.
895 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
898 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
900 TempsToInstrument.clear();
901 if (isNoReturnCall(CI)) {
902 NoReturnCalls.push_back(CI);
907 ToInstrument.push_back(BI);
909 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
915 int NumInstrumented = 0;
916 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
917 Instruction *Inst = ToInstrument[i];
918 if (ClDebugMin < 0 || ClDebugMax < 0 ||
919 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
920 if (isInterestingMemoryAccess(Inst, &IsWrite))
923 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
928 bool ChangedStack = poisonStackInFunction(F);
930 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
931 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
932 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
933 Instruction *CI = NoReturnCalls[i];
935 IRB.CreateCall(AsanHandleNoReturnFunc);
937 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
939 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
942 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
943 if (ShadowRedzoneSize == 1) return PoisonByte;
944 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
945 if (ShadowRedzoneSize == 4)
946 return (PoisonByte << 24) + (PoisonByte << 16) +
947 (PoisonByte << 8) + (PoisonByte);
948 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
951 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
954 size_t ShadowGranularity,
956 for (size_t i = 0; i < RZSize;
957 i+= ShadowGranularity, Shadow++) {
958 if (i + ShadowGranularity <= Size) {
959 *Shadow = 0; // fully addressable
960 } else if (i >= Size) {
961 *Shadow = Magic; // unaddressable
963 *Shadow = Size - i; // first Size-i bytes are addressable
968 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
970 Value *ShadowBase, bool DoPoison) {
971 size_t ShadowRZSize = RedzoneSize() >> MappingScale();
972 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
973 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
974 Type *RZPtrTy = PointerType::get(RZTy, 0);
976 Value *PoisonLeft = ConstantInt::get(RZTy,
977 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
978 Value *PoisonMid = ConstantInt::get(RZTy,
979 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
980 Value *PoisonRight = ConstantInt::get(RZTy,
981 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
983 // poison the first red zone.
984 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
986 // poison all other red zones.
987 uint64_t Pos = RedzoneSize();
988 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
989 AllocaInst *AI = AllocaVec[i];
990 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
991 uint64_t AlignedSize = getAlignedAllocaSize(AI);
992 assert(AlignedSize - SizeInBytes < RedzoneSize());
997 assert(ShadowBase->getType() == IntptrTy);
998 if (SizeInBytes < AlignedSize) {
999 // Poison the partial redzone at right
1000 Ptr = IRB.CreateAdd(
1001 ShadowBase, ConstantInt::get(IntptrTy,
1002 (Pos >> MappingScale()) - ShadowRZSize));
1003 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1004 uint32_t Poison = 0;
1006 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1008 1ULL << MappingScale(),
1009 kAsanStackPartialRedzoneMagic);
1011 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1012 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1015 // Poison the full redzone at right.
1016 Ptr = IRB.CreateAdd(ShadowBase,
1017 ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1018 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1019 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1021 Pos += RedzoneSize();
1025 // Workaround for bug 11395: we don't want to instrument stack in functions
1026 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1027 // FIXME: remove once the bug 11395 is fixed.
1028 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1029 if (LongSize != 32) return false;
1030 CallInst *CI = dyn_cast<CallInst>(I);
1031 if (!CI || !CI->isInlineAsm()) return false;
1032 if (CI->getNumArgOperands() <= 5) return false;
1033 // We have inline assembly with quite a few arguments.
1037 // Find all static Alloca instructions and put
1038 // poisoned red zones around all of them.
1039 // Then unpoison everything back before the function returns.
1041 // Stack poisoning does not play well with exception handling.
1042 // When an exception is thrown, we essentially bypass the code
1043 // that unpoisones the stack. This is why the run-time library has
1044 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1045 // stack in the interceptor. This however does not work inside the
1046 // actual function which catches the exception. Most likely because the
1047 // compiler hoists the load of the shadow value somewhere too high.
1048 // This causes asan to report a non-existing bug on 453.povray.
1049 // It sounds like an LLVM bug.
1050 bool AddressSanitizer::poisonStackInFunction(Function &F) {
1051 if (!ClStack) return false;
1052 SmallVector<AllocaInst*, 16> AllocaVec;
1053 SmallVector<Instruction*, 8> RetVec;
1054 uint64_t TotalSize = 0;
1056 // Filter out Alloca instructions we want (and can) handle.
1057 // Collect Ret instructions.
1058 for (Function::iterator FI = F.begin(), FE = F.end();
1060 BasicBlock &BB = *FI;
1061 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1063 if (isa<ReturnInst>(BI)) {
1064 RetVec.push_back(BI);
1068 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1070 if (AI->isArrayAllocation()) continue;
1071 if (!AI->isStaticAlloca()) continue;
1072 if (!AI->getAllocatedType()->isSized()) continue;
1073 if (AI->getAlignment() > RedzoneSize()) continue;
1074 AllocaVec.push_back(AI);
1075 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1076 TotalSize += AlignedSize;
1080 if (AllocaVec.empty()) return false;
1082 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize();
1084 bool DoStackMalloc = ClUseAfterReturn
1085 && LocalStackSize <= kMaxStackMallocSize;
1087 Instruction *InsBefore = AllocaVec[0];
1088 IRBuilder<> IRB(InsBefore);
1091 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1092 AllocaInst *MyAlloca =
1093 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1094 MyAlloca->setAlignment(RedzoneSize());
1095 assert(MyAlloca->isStaticAlloca());
1096 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1097 Value *LocalStackBase = OrigStackBase;
1099 if (DoStackMalloc) {
1100 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1101 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1104 // This string will be parsed by the run-time (DescribeStackAddress).
1105 SmallString<2048> StackDescriptionStorage;
1106 raw_svector_ostream StackDescription(StackDescriptionStorage);
1107 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1109 uint64_t Pos = RedzoneSize();
1110 // Replace Alloca instructions with base+offset.
1111 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1112 AllocaInst *AI = AllocaVec[i];
1113 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1114 StringRef Name = AI->getName();
1115 StackDescription << Pos << " " << SizeInBytes << " "
1116 << Name.size() << " " << Name << " ";
1117 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1118 assert((AlignedSize % RedzoneSize()) == 0);
1119 AI->replaceAllUsesWith(
1121 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1123 Pos += AlignedSize + RedzoneSize();
1125 assert(Pos == LocalStackSize);
1127 // Write the Magic value and the frame description constant to the redzone.
1128 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1129 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1131 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1132 ConstantInt::get(IntptrTy, LongSize/8));
1133 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1134 GlobalVariable *StackDescriptionGlobal =
1135 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1136 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1137 IRB.CreateStore(Description, BasePlus1);
1139 // Poison the stack redzones at the entry.
1140 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1141 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1143 // Unpoison the stack before all ret instructions.
1144 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1145 Instruction *Ret = RetVec[i];
1146 IRBuilder<> IRBRet(Ret);
1148 // Mark the current frame as retired.
1149 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1151 // Unpoison the stack.
1152 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1154 if (DoStackMalloc) {
1155 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1156 ConstantInt::get(IntptrTy, LocalStackSize),
1161 // We are done. Remove the old unused alloca instructions.
1162 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1163 AllocaVec[i]->eraseFromParent();