AddressSanitizer.cpp revision 3386d252579ea00d0fc26a3ba7874bec25ce4516 
1//===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
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
13//
14//===----------------------------------------------------------------------===//
15
16#define DEBUG_TYPE "asan"
17
18#include "llvm/Transforms/Instrumentation.h"
19#include "llvm/ADT/ArrayRef.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/DepthFirstIterator.h"
22#include "llvm/ADT/OwningPtr.h"
23#include "llvm/ADT/SmallSet.h"
24#include "llvm/ADT/SmallString.h"
25#include "llvm/ADT/SmallVector.h"
26#include "llvm/ADT/Statistic.h"
27#include "llvm/ADT/StringExtras.h"
28#include "llvm/ADT/Triple.h"
29#include "llvm/DIBuilder.h"
30#include "llvm/IR/DataLayout.h"
31#include "llvm/IR/Function.h"
32#include "llvm/IR/IRBuilder.h"
33#include "llvm/IR/InlineAsm.h"
34#include "llvm/IR/IntrinsicInst.h"
35#include "llvm/IR/LLVMContext.h"
36#include "llvm/IR/Module.h"
37#include "llvm/IR/Type.h"
38#include "llvm/InstVisitor.h"
39#include "llvm/Support/CallSite.h"
40#include "llvm/Support/CommandLine.h"
41#include "llvm/Support/DataTypes.h"
42#include "llvm/Support/Debug.h"
43#include "llvm/Support/Endian.h"
44#include "llvm/Support/raw_ostream.h"
45#include "llvm/Support/system_error.h"
46#include "llvm/Transforms/Utils/BasicBlockUtils.h"
47#include "llvm/Transforms/Utils/Cloning.h"
48#include "llvm/Transforms/Utils/Local.h"
49#include "llvm/Transforms/Utils/ModuleUtils.h"
50#include "llvm/Transforms/Utils/SpecialCaseList.h"
51#include <algorithm>
52#include <string>
53
54using namespace llvm;
55
56static const uint64_t kDefaultShadowScale = 3;
57static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
58static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
59static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
60static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
61static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
62
63static const size_t kMinStackMallocSize = 1 << 6;  // 64B
64static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
65static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
66static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
67
68static const char *const kAsanModuleCtorName = "asan.module_ctor";
69static const char *const kAsanModuleDtorName = "asan.module_dtor";
70static const int         kAsanCtorAndCtorPriority = 1;
71static const char *const kAsanReportErrorTemplate = "__asan_report_";
72static const char *const kAsanReportLoadN = "__asan_report_load_n";
73static const char *const kAsanReportStoreN = "__asan_report_store_n";
74static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
75static const char *const kAsanUnregisterGlobalsName =
76    "__asan_unregister_globals";
77static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
78static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
79static const char *const kAsanInitName = "__asan_init_v3";
80static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
81static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
82static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
83static const int         kMaxAsanStackMallocSizeClass = 10;
84static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
85static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
86static const char *const kAsanGenPrefix = "__asan_gen_";
87static const char *const kAsanPoisonStackMemoryName =
88    "__asan_poison_stack_memory";
89static const char *const kAsanUnpoisonStackMemoryName =
90    "__asan_unpoison_stack_memory";
91
92static const char *const kAsanOptionDetectUAR =
93    "__asan_option_detect_stack_use_after_return";
94
95// These constants must match the definitions in the run-time library.
96static const int kAsanStackLeftRedzoneMagic = 0xf1;
97static const int kAsanStackMidRedzoneMagic = 0xf2;
98static const int kAsanStackRightRedzoneMagic = 0xf3;
99static const int kAsanStackPartialRedzoneMagic = 0xf4;
100#ifndef NDEBUG
101static const int kAsanStackAfterReturnMagic = 0xf5;
102#endif
103
104// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105static const size_t kNumberOfAccessSizes = 5;
106
107// Command-line flags.
108
109// This flag may need to be replaced with -f[no-]asan-reads.
110static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
111       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
112static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
113       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
114static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
115       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
116       cl::Hidden, cl::init(true));
117static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
118       cl::desc("use instrumentation with slow path for all accesses"),
119       cl::Hidden, cl::init(false));
120// This flag limits the number of instructions to be instrumented
121// in any given BB. Normally, this should be set to unlimited (INT_MAX),
122// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
123// set it to 10000.
124static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
125       cl::init(10000),
126       cl::desc("maximal number of instructions to instrument in any given BB"),
127       cl::Hidden);
128// This flag may need to be replaced with -f[no]asan-stack.
129static cl::opt<bool> ClStack("asan-stack",
130       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
131// This flag may need to be replaced with -f[no]asan-use-after-return.
132static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
134// This flag may need to be replaced with -f[no]asan-globals.
135static cl::opt<bool> ClGlobals("asan-globals",
136       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
137static cl::opt<bool> ClInitializers("asan-initialization-order",
138       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
139static cl::opt<bool> ClMemIntrin("asan-memintrin",
140       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
141static cl::opt<bool> ClRealignStack("asan-realign-stack",
142       cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
143static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
144       cl::desc("File containing the list of objects to ignore "
145                "during instrumentation"), cl::Hidden);
146
147// This is an experimental feature that will allow to choose between
148// instrumented and non-instrumented code at link-time.
149// If this option is on, just before instrumenting a function we create its
150// clone; if the function is not changed by asan the clone is deleted.
151// If we end up with a clone, we put the instrumented function into a section
152// called "ASAN" and the uninstrumented function into a section called "NOASAN".
153//
154// This is still a prototype, we need to figure out a way to keep two copies of
155// a function so that the linker can easily choose one of them.
156static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
157       cl::desc("Keep uninstrumented copies of functions"),
158       cl::Hidden, cl::init(false));
159
160// These flags allow to change the shadow mapping.
161// The shadow mapping looks like
162//    Shadow = (Mem >> scale) + (1 << offset_log)
163static cl::opt<int> ClMappingScale("asan-mapping-scale",
164       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
165static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
166       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
167static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
168       cl::desc("Use short immediate constant as the mapping offset for 64bit"),
169       cl::Hidden, cl::init(true));
170
171// Optimization flags. Not user visible, used mostly for testing
172// and benchmarking the tool.
173static cl::opt<bool> ClOpt("asan-opt",
174       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
175static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
176       cl::desc("Instrument the same temp just once"), cl::Hidden,
177       cl::init(true));
178static cl::opt<bool> ClOptGlobals("asan-opt-globals",
179       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
180
181static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
182       cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
183       cl::Hidden, cl::init(false));
184
185// Debug flags.
186static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
187                            cl::init(0));
188static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
189                                 cl::Hidden, cl::init(0));
190static cl::opt<std::string> ClDebugFunc("asan-debug-func",
191                                        cl::Hidden, cl::desc("Debug func"));
192static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
193                               cl::Hidden, cl::init(-1));
194static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
195                               cl::Hidden, cl::init(-1));
196
197STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
198STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
199STATISTIC(NumOptimizedAccessesToGlobalArray,
200          "Number of optimized accesses to global arrays");
201STATISTIC(NumOptimizedAccessesToGlobalVar,
202          "Number of optimized accesses to global vars");
203
204namespace {
205/// A set of dynamically initialized globals extracted from metadata.
206class SetOfDynamicallyInitializedGlobals {
207 public:
208  void Init(Module& M) {
209    // Clang generates metadata identifying all dynamically initialized globals.
210    NamedMDNode *DynamicGlobals =
211        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
212    if (!DynamicGlobals)
213      return;
214    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
215      MDNode *MDN = DynamicGlobals->getOperand(i);
216      assert(MDN->getNumOperands() == 1);
217      Value *VG = MDN->getOperand(0);
218      // The optimizer may optimize away a global entirely, in which case we
219      // cannot instrument access to it.
220      if (!VG)
221        continue;
222      DynInitGlobals.insert(cast<GlobalVariable>(VG));
223    }
224  }
225  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
226 private:
227  SmallSet<GlobalValue*, 32> DynInitGlobals;
228};
229
230/// This struct defines the shadow mapping using the rule:
231///   shadow = (mem >> Scale) ADD-or-OR Offset.
232struct ShadowMapping {
233  int Scale;
234  uint64_t Offset;
235  bool OrShadowOffset;
236};
237
238static ShadowMapping getShadowMapping(const Module &M, int LongSize,
239                                      bool ZeroBaseShadow) {
240  llvm::Triple TargetTriple(M.getTargetTriple());
241  bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
242  bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
243  bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
244                 TargetTriple.getArch() == llvm::Triple::ppc64le;
245  bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
246  bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
247                  TargetTriple.getArch() == llvm::Triple::mipsel;
248
249  ShadowMapping Mapping;
250
251  // OR-ing shadow offset if more efficient (at least on x86),
252  // but on ppc64 we have to use add since the shadow offset is not neccesary
253  // 1/8-th of the address space.
254  Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
255
256  Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
257      (LongSize == 32 ?
258       (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
259       IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
260  if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
261    assert(LongSize == 64);
262    Mapping.Offset = kDefaultShort64bitShadowOffset;
263  }
264  if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
265    // Zero offset log is the special case.
266    Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
267  }
268
269  Mapping.Scale = kDefaultShadowScale;
270  if (ClMappingScale) {
271    Mapping.Scale = ClMappingScale;
272  }
273
274  return Mapping;
275}
276
277static size_t RedzoneSizeForScale(int MappingScale) {
278  // Redzone used for stack and globals is at least 32 bytes.
279  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
280  return std::max(32U, 1U << MappingScale);
281}
282
283/// AddressSanitizer: instrument the code in module to find memory bugs.
284struct AddressSanitizer : public FunctionPass {
285  AddressSanitizer(bool CheckInitOrder = true,
286                   bool CheckUseAfterReturn = false,
287                   bool CheckLifetime = false,
288                   StringRef BlacklistFile = StringRef(),
289                   bool ZeroBaseShadow = false)
290      : FunctionPass(ID),
291        CheckInitOrder(CheckInitOrder || ClInitializers),
292        CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
293        CheckLifetime(CheckLifetime || ClCheckLifetime),
294        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
295                                            : BlacklistFile),
296        ZeroBaseShadow(ZeroBaseShadow) {}
297  virtual const char *getPassName() const {
298    return "AddressSanitizerFunctionPass";
299  }
300  void instrumentMop(Instruction *I);
301  void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
302                         Value *Addr, uint32_t TypeSize, bool IsWrite,
303                         Value *SizeArgument);
304  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
305                           Value *ShadowValue, uint32_t TypeSize);
306  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
307                                 bool IsWrite, size_t AccessSizeIndex,
308                                 Value *SizeArgument);
309  bool instrumentMemIntrinsic(MemIntrinsic *MI);
310  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
311                                   Value *Size,
312                                   Instruction *InsertBefore, bool IsWrite);
313  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
314  bool runOnFunction(Function &F);
315  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
316  void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
317  virtual bool doInitialization(Module &M);
318  static char ID;  // Pass identification, replacement for typeid
319
320 private:
321  void initializeCallbacks(Module &M);
322
323  bool ShouldInstrumentGlobal(GlobalVariable *G);
324  bool LooksLikeCodeInBug11395(Instruction *I);
325  void FindDynamicInitializers(Module &M);
326  bool GlobalIsLinkerInitialized(GlobalVariable *G);
327
328  bool CheckInitOrder;
329  bool CheckUseAfterReturn;
330  bool CheckLifetime;
331  SmallString<64> BlacklistFile;
332  bool ZeroBaseShadow;
333
334  LLVMContext *C;
335  DataLayout *TD;
336  int LongSize;
337  Type *IntptrTy;
338  ShadowMapping Mapping;
339  Function *AsanCtorFunction;
340  Function *AsanInitFunction;
341  Function *AsanHandleNoReturnFunc;
342  OwningPtr<SpecialCaseList> BL;
343  // This array is indexed by AccessIsWrite and log2(AccessSize).
344  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
345  // This array is indexed by AccessIsWrite.
346  Function *AsanErrorCallbackSized[2];
347  InlineAsm *EmptyAsm;
348  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
349
350  friend struct FunctionStackPoisoner;
351};
352
353class AddressSanitizerModule : public ModulePass {
354 public:
355  AddressSanitizerModule(bool CheckInitOrder = true,
356                         StringRef BlacklistFile = StringRef(),
357                         bool ZeroBaseShadow = false)
358      : ModulePass(ID),
359        CheckInitOrder(CheckInitOrder || ClInitializers),
360        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
361                                            : BlacklistFile),
362        ZeroBaseShadow(ZeroBaseShadow) {}
363  bool runOnModule(Module &M);
364  static char ID;  // Pass identification, replacement for typeid
365  virtual const char *getPassName() const {
366    return "AddressSanitizerModule";
367  }
368
369 private:
370  void initializeCallbacks(Module &M);
371
372  bool ShouldInstrumentGlobal(GlobalVariable *G);
373  void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
374  size_t RedzoneSize() const {
375    return RedzoneSizeForScale(Mapping.Scale);
376  }
377
378  bool CheckInitOrder;
379  SmallString<64> BlacklistFile;
380  bool ZeroBaseShadow;
381
382  OwningPtr<SpecialCaseList> BL;
383  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
384  Type *IntptrTy;
385  LLVMContext *C;
386  DataLayout *TD;
387  ShadowMapping Mapping;
388  Function *AsanPoisonGlobals;
389  Function *AsanUnpoisonGlobals;
390  Function *AsanRegisterGlobals;
391  Function *AsanUnregisterGlobals;
392};
393
394// Stack poisoning does not play well with exception handling.
395// When an exception is thrown, we essentially bypass the code
396// that unpoisones the stack. This is why the run-time library has
397// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
398// stack in the interceptor. This however does not work inside the
399// actual function which catches the exception. Most likely because the
400// compiler hoists the load of the shadow value somewhere too high.
401// This causes asan to report a non-existing bug on 453.povray.
402// It sounds like an LLVM bug.
403struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
404  Function &F;
405  AddressSanitizer &ASan;
406  DIBuilder DIB;
407  LLVMContext *C;
408  Type *IntptrTy;
409  Type *IntptrPtrTy;
410  ShadowMapping Mapping;
411
412  SmallVector<AllocaInst*, 16> AllocaVec;
413  SmallVector<Instruction*, 8> RetVec;
414  uint64_t TotalStackSize;
415  unsigned StackAlignment;
416
417  Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
418           *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
419  Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
420
421  // Stores a place and arguments of poisoning/unpoisoning call for alloca.
422  struct AllocaPoisonCall {
423    IntrinsicInst *InsBefore;
424    uint64_t Size;
425    bool DoPoison;
426  };
427  SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
428
429  // Maps Value to an AllocaInst from which the Value is originated.
430  typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
431  AllocaForValueMapTy AllocaForValue;
432
433  FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
434      : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
435        IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
436        Mapping(ASan.Mapping),
437        TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
438
439  bool runOnFunction() {
440    if (!ClStack) return false;
441    // Collect alloca, ret, lifetime instructions etc.
442    for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
443         DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
444      BasicBlock *BB = *DI;
445      visit(*BB);
446    }
447    if (AllocaVec.empty()) return false;
448
449    initializeCallbacks(*F.getParent());
450
451    poisonStack();
452
453    if (ClDebugStack) {
454      DEBUG(dbgs() << F);
455    }
456    return true;
457  }
458
459  // Finds all static Alloca instructions and puts
460  // poisoned red zones around all of them.
461  // Then unpoison everything back before the function returns.
462  void poisonStack();
463
464  // ----------------------- Visitors.
465  /// \brief Collect all Ret instructions.
466  void visitReturnInst(ReturnInst &RI) {
467    RetVec.push_back(&RI);
468  }
469
470  /// \brief Collect Alloca instructions we want (and can) handle.
471  void visitAllocaInst(AllocaInst &AI) {
472    if (!isInterestingAlloca(AI)) return;
473
474    StackAlignment = std::max(StackAlignment, AI.getAlignment());
475    AllocaVec.push_back(&AI);
476    uint64_t AlignedSize = getAlignedAllocaSize(&AI);
477    TotalStackSize += AlignedSize;
478  }
479
480  /// \brief Collect lifetime intrinsic calls to check for use-after-scope
481  /// errors.
482  void visitIntrinsicInst(IntrinsicInst &II) {
483    if (!ASan.CheckLifetime) return;
484    Intrinsic::ID ID = II.getIntrinsicID();
485    if (ID != Intrinsic::lifetime_start &&
486        ID != Intrinsic::lifetime_end)
487      return;
488    // Found lifetime intrinsic, add ASan instrumentation if necessary.
489    ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
490    // If size argument is undefined, don't do anything.
491    if (Size->isMinusOne()) return;
492    // Check that size doesn't saturate uint64_t and can
493    // be stored in IntptrTy.
494    const uint64_t SizeValue = Size->getValue().getLimitedValue();
495    if (SizeValue == ~0ULL ||
496        !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
497      return;
498    // Find alloca instruction that corresponds to llvm.lifetime argument.
499    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
500    if (!AI) return;
501    bool DoPoison = (ID == Intrinsic::lifetime_end);
502    AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
503    AllocaPoisonCallVec.push_back(APC);
504  }
505
506  // ---------------------- Helpers.
507  void initializeCallbacks(Module &M);
508
509  // Check if we want (and can) handle this alloca.
510  bool isInterestingAlloca(AllocaInst &AI) const {
511    return (!AI.isArrayAllocation() &&
512            AI.isStaticAlloca() &&
513            AI.getAlignment() <= RedzoneSize() &&
514            AI.getAllocatedType()->isSized());
515  }
516
517  size_t RedzoneSize() const {
518    return RedzoneSizeForScale(Mapping.Scale);
519  }
520  uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
521    Type *Ty = AI->getAllocatedType();
522    uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
523    return SizeInBytes;
524  }
525  uint64_t getAlignedSize(uint64_t SizeInBytes) const {
526    size_t RZ = RedzoneSize();
527    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
528  }
529  uint64_t getAlignedAllocaSize(AllocaInst *AI) const {
530    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
531    return getAlignedSize(SizeInBytes);
532  }
533  /// Finds alloca where the value comes from.
534  AllocaInst *findAllocaForValue(Value *V);
535  void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB,
536                      Value *ShadowBase, bool DoPoison);
537  void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
538
539  void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
540                                          int Size);
541};
542
543}  // namespace
544
545char AddressSanitizer::ID = 0;
546INITIALIZE_PASS(AddressSanitizer, "asan",
547    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
548    false, false)
549FunctionPass *llvm::createAddressSanitizerFunctionPass(
550    bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
551    StringRef BlacklistFile, bool ZeroBaseShadow) {
552  return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
553                              CheckLifetime, BlacklistFile, ZeroBaseShadow);
554}
555
556char AddressSanitizerModule::ID = 0;
557INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
558    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
559    "ModulePass", false, false)
560ModulePass *llvm::createAddressSanitizerModulePass(
561    bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
562  return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
563                                    ZeroBaseShadow);
564}
565
566static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
567  size_t Res = countTrailingZeros(TypeSize / 8);
568  assert(Res < kNumberOfAccessSizes);
569  return Res;
570}
571
572// \brief Create a constant for Str so that we can pass it to the run-time lib.
573static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
574  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
575  GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
576                            GlobalValue::InternalLinkage, StrConst,
577                            kAsanGenPrefix);
578  GV->setUnnamedAddr(true);  // Ok to merge these.
579  GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
580  return GV;
581}
582
583static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
584  return G->getName().find(kAsanGenPrefix) == 0;
585}
586
587Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
588  // Shadow >> scale
589  Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
590  if (Mapping.Offset == 0)
591    return Shadow;
592  // (Shadow >> scale) | offset
593  if (Mapping.OrShadowOffset)
594    return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
595  else
596    return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
597}
598
599void AddressSanitizer::instrumentMemIntrinsicParam(
600    Instruction *OrigIns,
601    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
602  IRBuilder<> IRB(InsertBefore);
603  if (Size->getType() != IntptrTy)
604    Size = IRB.CreateIntCast(Size, IntptrTy, false);
605  // Check the first byte.
606  instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
607  // Check the last byte.
608  IRB.SetInsertPoint(InsertBefore);
609  Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
610  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
611  Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
612  instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
613}
614
615// Instrument memset/memmove/memcpy
616bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
617  Value *Dst = MI->getDest();
618  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
619  Value *Src = MemTran ? MemTran->getSource() : 0;
620  Value *Length = MI->getLength();
621
622  Constant *ConstLength = dyn_cast<Constant>(Length);
623  Instruction *InsertBefore = MI;
624  if (ConstLength) {
625    if (ConstLength->isNullValue()) return false;
626  } else {
627    // The size is not a constant so it could be zero -- check at run-time.
628    IRBuilder<> IRB(InsertBefore);
629
630    Value *Cmp = IRB.CreateICmpNE(Length,
631                                  Constant::getNullValue(Length->getType()));
632    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
633  }
634
635  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
636  if (Src)
637    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
638  return true;
639}
640
641// If I is an interesting memory access, return the PointerOperand
642// and set IsWrite. Otherwise return NULL.
643static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
644  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
645    if (!ClInstrumentReads) return NULL;
646    *IsWrite = false;
647    return LI->getPointerOperand();
648  }
649  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
650    if (!ClInstrumentWrites) return NULL;
651    *IsWrite = true;
652    return SI->getPointerOperand();
653  }
654  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
655    if (!ClInstrumentAtomics) return NULL;
656    *IsWrite = true;
657    return RMW->getPointerOperand();
658  }
659  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
660    if (!ClInstrumentAtomics) return NULL;
661    *IsWrite = true;
662    return XCHG->getPointerOperand();
663  }
664  return NULL;
665}
666
667bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
668  // If a global variable does not have dynamic initialization we don't
669  // have to instrument it.  However, if a global does not have initializer
670  // at all, we assume it has dynamic initializer (in other TU).
671  return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
672}
673
674void AddressSanitizer::instrumentMop(Instruction *I) {
675  bool IsWrite = false;
676  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
677  assert(Addr);
678  if (ClOpt && ClOptGlobals) {
679    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
680      // If initialization order checking is disabled, a simple access to a
681      // dynamically initialized global is always valid.
682      if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
683        NumOptimizedAccessesToGlobalVar++;
684        return;
685      }
686    }
687    ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
688    if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
689      if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
690        if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
691          NumOptimizedAccessesToGlobalArray++;
692          return;
693        }
694      }
695    }
696  }
697
698  Type *OrigPtrTy = Addr->getType();
699  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
700
701  assert(OrigTy->isSized());
702  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
703
704  assert((TypeSize % 8) == 0);
705
706  if (IsWrite)
707    NumInstrumentedWrites++;
708  else
709    NumInstrumentedReads++;
710
711  // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
712  if (TypeSize == 8  || TypeSize == 16 ||
713      TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
714    return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
715  // Instrument unusual size (but still multiple of 8).
716  // We can not do it with a single check, so we do 1-byte check for the first
717  // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
718  // to report the actual access size.
719  IRBuilder<> IRB(I);
720  Value *LastByte =  IRB.CreateIntToPtr(
721      IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
722                    ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
723      OrigPtrTy);
724  Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
725  instrumentAddress(I, I, Addr, 8, IsWrite, Size);
726  instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
727}
728
729// Validate the result of Module::getOrInsertFunction called for an interface
730// function of AddressSanitizer. If the instrumented module defines a function
731// with the same name, their prototypes must match, otherwise
732// getOrInsertFunction returns a bitcast.
733static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
734  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
735  FuncOrBitcast->dump();
736  report_fatal_error("trying to redefine an AddressSanitizer "
737                     "interface function");
738}
739
740Instruction *AddressSanitizer::generateCrashCode(
741    Instruction *InsertBefore, Value *Addr,
742    bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
743  IRBuilder<> IRB(InsertBefore);
744  CallInst *Call = SizeArgument
745    ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
746    : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
747
748  // We don't do Call->setDoesNotReturn() because the BB already has
749  // UnreachableInst at the end.
750  // This EmptyAsm is required to avoid callback merge.
751  IRB.CreateCall(EmptyAsm);
752  return Call;
753}
754
755Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
756                                            Value *ShadowValue,
757                                            uint32_t TypeSize) {
758  size_t Granularity = 1 << Mapping.Scale;
759  // Addr & (Granularity - 1)
760  Value *LastAccessedByte = IRB.CreateAnd(
761      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
762  // (Addr & (Granularity - 1)) + size - 1
763  if (TypeSize / 8 > 1)
764    LastAccessedByte = IRB.CreateAdd(
765        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
766  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
767  LastAccessedByte = IRB.CreateIntCast(
768      LastAccessedByte, ShadowValue->getType(), false);
769  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
770  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
771}
772
773void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
774                                         Instruction *InsertBefore,
775                                         Value *Addr, uint32_t TypeSize,
776                                         bool IsWrite, Value *SizeArgument) {
777  IRBuilder<> IRB(InsertBefore);
778  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
779
780  Type *ShadowTy  = IntegerType::get(
781      *C, std::max(8U, TypeSize >> Mapping.Scale));
782  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
783  Value *ShadowPtr = memToShadow(AddrLong, IRB);
784  Value *CmpVal = Constant::getNullValue(ShadowTy);
785  Value *ShadowValue = IRB.CreateLoad(
786      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
787
788  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
789  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
790  size_t Granularity = 1 << Mapping.Scale;
791  TerminatorInst *CrashTerm = 0;
792
793  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
794    TerminatorInst *CheckTerm =
795        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
796    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
797    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
798    IRB.SetInsertPoint(CheckTerm);
799    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
800    BasicBlock *CrashBlock =
801        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
802    CrashTerm = new UnreachableInst(*C, CrashBlock);
803    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
804    ReplaceInstWithInst(CheckTerm, NewTerm);
805  } else {
806    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
807  }
808
809  Instruction *Crash = generateCrashCode(
810      CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
811  Crash->setDebugLoc(OrigIns->getDebugLoc());
812}
813
814void AddressSanitizerModule::createInitializerPoisonCalls(
815    Module &M, GlobalValue *ModuleName) {
816  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
817  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
818  // If that function is not present, this TU contains no globals, or they have
819  // all been optimized away
820  if (!GlobalInit)
821    return;
822
823  // Set up the arguments to our poison/unpoison functions.
824  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
825
826  // Add a call to poison all external globals before the given function starts.
827  Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
828  IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
829
830  // Add calls to unpoison all globals before each return instruction.
831  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
832      I != E; ++I) {
833    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
834      CallInst::Create(AsanUnpoisonGlobals, "", RI);
835    }
836  }
837}
838
839bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
840  Type *Ty = cast<PointerType>(G->getType())->getElementType();
841  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
842
843  if (BL->isIn(*G)) return false;
844  if (!Ty->isSized()) return false;
845  if (!G->hasInitializer()) return false;
846  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
847  // Touch only those globals that will not be defined in other modules.
848  // Don't handle ODR type linkages since other modules may be built w/o asan.
849  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
850      G->getLinkage() != GlobalVariable::PrivateLinkage &&
851      G->getLinkage() != GlobalVariable::InternalLinkage)
852    return false;
853  // Two problems with thread-locals:
854  //   - The address of the main thread's copy can't be computed at link-time.
855  //   - Need to poison all copies, not just the main thread's one.
856  if (G->isThreadLocal())
857    return false;
858  // For now, just ignore this Alloca if the alignment is large.
859  if (G->getAlignment() > RedzoneSize()) return false;
860
861  // Ignore all the globals with the names starting with "\01L_OBJC_".
862  // Many of those are put into the .cstring section. The linker compresses
863  // that section by removing the spare \0s after the string terminator, so
864  // our redzones get broken.
865  if ((G->getName().find("\01L_OBJC_") == 0) ||
866      (G->getName().find("\01l_OBJC_") == 0)) {
867    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
868    return false;
869  }
870
871  if (G->hasSection()) {
872    StringRef Section(G->getSection());
873    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
874    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
875    // them.
876    if ((Section.find("__OBJC,") == 0) ||
877        (Section.find("__DATA, __objc_") == 0)) {
878      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
879      return false;
880    }
881    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
882    // Constant CFString instances are compiled in the following way:
883    //  -- the string buffer is emitted into
884    //     __TEXT,__cstring,cstring_literals
885    //  -- the constant NSConstantString structure referencing that buffer
886    //     is placed into __DATA,__cfstring
887    // Therefore there's no point in placing redzones into __DATA,__cfstring.
888    // Moreover, it causes the linker to crash on OS X 10.7
889    if (Section.find("__DATA,__cfstring") == 0) {
890      DEBUG(dbgs() << "Ignoring CFString: " << *G);
891      return false;
892    }
893  }
894
895  return true;
896}
897
898void AddressSanitizerModule::initializeCallbacks(Module &M) {
899  IRBuilder<> IRB(*C);
900  // Declare our poisoning and unpoisoning functions.
901  AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
902      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
903  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
904  AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
905      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
906  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
907  // Declare functions that register/unregister globals.
908  AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
909      kAsanRegisterGlobalsName, IRB.getVoidTy(),
910      IntptrTy, IntptrTy, NULL));
911  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
912  AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
913      kAsanUnregisterGlobalsName,
914      IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
915  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
916}
917
918// This function replaces all global variables with new variables that have
919// trailing redzones. It also creates a function that poisons
920// redzones and inserts this function into llvm.global_ctors.
921bool AddressSanitizerModule::runOnModule(Module &M) {
922  if (!ClGlobals) return false;
923  TD = getAnalysisIfAvailable<DataLayout>();
924  if (!TD)
925    return false;
926  BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
927  if (BL->isIn(M)) return false;
928  C = &(M.getContext());
929  int LongSize = TD->getPointerSizeInBits();
930  IntptrTy = Type::getIntNTy(*C, LongSize);
931  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
932  initializeCallbacks(M);
933  DynamicallyInitializedGlobals.Init(M);
934
935  SmallVector<GlobalVariable *, 16> GlobalsToChange;
936
937  for (Module::GlobalListType::iterator G = M.global_begin(),
938       E = M.global_end(); G != E; ++G) {
939    if (ShouldInstrumentGlobal(G))
940      GlobalsToChange.push_back(G);
941  }
942
943  size_t n = GlobalsToChange.size();
944  if (n == 0) return false;
945
946  // A global is described by a structure
947  //   size_t beg;
948  //   size_t size;
949  //   size_t size_with_redzone;
950  //   const char *name;
951  //   const char *module_name;
952  //   size_t has_dynamic_init;
953  // We initialize an array of such structures and pass it to a run-time call.
954  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
955                                               IntptrTy, IntptrTy,
956                                               IntptrTy, IntptrTy, NULL);
957  SmallVector<Constant *, 16> Initializers(n);
958
959  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
960  assert(CtorFunc);
961  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
962
963  bool HasDynamicallyInitializedGlobals = false;
964
965  GlobalVariable *ModuleName = createPrivateGlobalForString(
966      M, M.getModuleIdentifier());
967  // We shouldn't merge same module names, as this string serves as unique
968  // module ID in runtime.
969  ModuleName->setUnnamedAddr(false);
970
971  for (size_t i = 0; i < n; i++) {
972    static const uint64_t kMaxGlobalRedzone = 1 << 18;
973    GlobalVariable *G = GlobalsToChange[i];
974    PointerType *PtrTy = cast<PointerType>(G->getType());
975    Type *Ty = PtrTy->getElementType();
976    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
977    uint64_t MinRZ = RedzoneSize();
978    // MinRZ <= RZ <= kMaxGlobalRedzone
979    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
980    uint64_t RZ = std::max(MinRZ,
981                         std::min(kMaxGlobalRedzone,
982                                  (SizeInBytes / MinRZ / 4) * MinRZ));
983    uint64_t RightRedzoneSize = RZ;
984    // Round up to MinRZ
985    if (SizeInBytes % MinRZ)
986      RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
987    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
988    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
989    // Determine whether this global should be poisoned in initialization.
990    bool GlobalHasDynamicInitializer =
991        DynamicallyInitializedGlobals.Contains(G);
992    // Don't check initialization order if this global is blacklisted.
993    GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
994
995    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
996    Constant *NewInitializer = ConstantStruct::get(
997        NewTy, G->getInitializer(),
998        Constant::getNullValue(RightRedZoneTy), NULL);
999
1000    GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
1001
1002    // Create a new global variable with enough space for a redzone.
1003    GlobalValue::LinkageTypes Linkage = G->getLinkage();
1004    if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1005      Linkage = GlobalValue::InternalLinkage;
1006    GlobalVariable *NewGlobal = new GlobalVariable(
1007        M, NewTy, G->isConstant(), Linkage,
1008        NewInitializer, "", G, G->getThreadLocalMode());
1009    NewGlobal->copyAttributesFrom(G);
1010    NewGlobal->setAlignment(MinRZ);
1011
1012    Value *Indices2[2];
1013    Indices2[0] = IRB.getInt32(0);
1014    Indices2[1] = IRB.getInt32(0);
1015
1016    G->replaceAllUsesWith(
1017        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1018    NewGlobal->takeName(G);
1019    G->eraseFromParent();
1020
1021    Initializers[i] = ConstantStruct::get(
1022        GlobalStructTy,
1023        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1024        ConstantInt::get(IntptrTy, SizeInBytes),
1025        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1026        ConstantExpr::getPointerCast(Name, IntptrTy),
1027        ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1028        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1029        NULL);
1030
1031    // Populate the first and last globals declared in this TU.
1032    if (CheckInitOrder && GlobalHasDynamicInitializer)
1033      HasDynamicallyInitializedGlobals = true;
1034
1035    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1036  }
1037
1038  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1039  GlobalVariable *AllGlobals = new GlobalVariable(
1040      M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1041      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1042
1043  // Create calls for poisoning before initializers run and unpoisoning after.
1044  if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1045    createInitializerPoisonCalls(M, ModuleName);
1046  IRB.CreateCall2(AsanRegisterGlobals,
1047                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
1048                  ConstantInt::get(IntptrTy, n));
1049
1050  // We also need to unregister globals at the end, e.g. when a shared library
1051  // gets closed.
1052  Function *AsanDtorFunction = Function::Create(
1053      FunctionType::get(Type::getVoidTy(*C), false),
1054      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1055  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1056  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1057  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1058                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
1059                       ConstantInt::get(IntptrTy, n));
1060  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1061
1062  DEBUG(dbgs() << M);
1063  return true;
1064}
1065
1066void AddressSanitizer::initializeCallbacks(Module &M) {
1067  IRBuilder<> IRB(*C);
1068  // Create __asan_report* callbacks.
1069  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1070    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1071         AccessSizeIndex++) {
1072      // IsWrite and TypeSize are encoded in the function name.
1073      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1074          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1075      // If we are merging crash callbacks, they have two parameters.
1076      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1077          checkInterfaceFunction(M.getOrInsertFunction(
1078              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1079    }
1080  }
1081  AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1082              kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1083  AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1084              kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1085
1086  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1087      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1088  // We insert an empty inline asm after __asan_report* to avoid callback merge.
1089  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1090                            StringRef(""), StringRef(""),
1091                            /*hasSideEffects=*/true);
1092}
1093
1094void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1095  // Tell the values of mapping offset and scale to the run-time.
1096  GlobalValue *asan_mapping_offset =
1097      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1098                     ConstantInt::get(IntptrTy, Mapping.Offset),
1099                     kAsanMappingOffsetName);
1100  // Read the global, otherwise it may be optimized away.
1101  IRB.CreateLoad(asan_mapping_offset, true);
1102
1103  GlobalValue *asan_mapping_scale =
1104      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1105                         ConstantInt::get(IntptrTy, Mapping.Scale),
1106                         kAsanMappingScaleName);
1107  // Read the global, otherwise it may be optimized away.
1108  IRB.CreateLoad(asan_mapping_scale, true);
1109}
1110
1111// virtual
1112bool AddressSanitizer::doInitialization(Module &M) {
1113  // Initialize the private fields. No one has accessed them before.
1114  TD = getAnalysisIfAvailable<DataLayout>();
1115
1116  if (!TD)
1117    return false;
1118  BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1119  DynamicallyInitializedGlobals.Init(M);
1120
1121  C = &(M.getContext());
1122  LongSize = TD->getPointerSizeInBits();
1123  IntptrTy = Type::getIntNTy(*C, LongSize);
1124
1125  AsanCtorFunction = Function::Create(
1126      FunctionType::get(Type::getVoidTy(*C), false),
1127      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1128  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1129  // call __asan_init in the module ctor.
1130  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1131  AsanInitFunction = checkInterfaceFunction(
1132      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1133  AsanInitFunction->setLinkage(Function::ExternalLinkage);
1134  IRB.CreateCall(AsanInitFunction);
1135
1136  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1137  emitShadowMapping(M, IRB);
1138
1139  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1140  return true;
1141}
1142
1143bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1144  // For each NSObject descendant having a +load method, this method is invoked
1145  // by the ObjC runtime before any of the static constructors is called.
1146  // Therefore we need to instrument such methods with a call to __asan_init
1147  // at the beginning in order to initialize our runtime before any access to
1148  // the shadow memory.
1149  // We cannot just ignore these methods, because they may call other
1150  // instrumented functions.
1151  if (F.getName().find(" load]") != std::string::npos) {
1152    IRBuilder<> IRB(F.begin()->begin());
1153    IRB.CreateCall(AsanInitFunction);
1154    return true;
1155  }
1156  return false;
1157}
1158
1159bool AddressSanitizer::runOnFunction(Function &F) {
1160  if (BL->isIn(F)) return false;
1161  if (&F == AsanCtorFunction) return false;
1162  if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1163  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1164  initializeCallbacks(*F.getParent());
1165
1166  // If needed, insert __asan_init before checking for SanitizeAddress attr.
1167  maybeInsertAsanInitAtFunctionEntry(F);
1168
1169  if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1170    return false;
1171
1172  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1173    return false;
1174
1175  // We want to instrument every address only once per basic block (unless there
1176  // are calls between uses).
1177  SmallSet<Value*, 16> TempsToInstrument;
1178  SmallVector<Instruction*, 16> ToInstrument;
1179  SmallVector<Instruction*, 8> NoReturnCalls;
1180  int NumAllocas = 0;
1181  bool IsWrite;
1182
1183  // Fill the set of memory operations to instrument.
1184  for (Function::iterator FI = F.begin(), FE = F.end();
1185       FI != FE; ++FI) {
1186    TempsToInstrument.clear();
1187    int NumInsnsPerBB = 0;
1188    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1189         BI != BE; ++BI) {
1190      if (LooksLikeCodeInBug11395(BI)) return false;
1191      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1192        if (ClOpt && ClOptSameTemp) {
1193          if (!TempsToInstrument.insert(Addr))
1194            continue;  // We've seen this temp in the current BB.
1195        }
1196      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1197        // ok, take it.
1198      } else {
1199        if (isa<AllocaInst>(BI))
1200          NumAllocas++;
1201        CallSite CS(BI);
1202        if (CS) {
1203          // A call inside BB.
1204          TempsToInstrument.clear();
1205          if (CS.doesNotReturn())
1206            NoReturnCalls.push_back(CS.getInstruction());
1207        }
1208        continue;
1209      }
1210      ToInstrument.push_back(BI);
1211      NumInsnsPerBB++;
1212      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1213        break;
1214    }
1215  }
1216
1217  Function *UninstrumentedDuplicate = 0;
1218  bool LikelyToInstrument =
1219      !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1220  if (ClKeepUninstrumented && LikelyToInstrument) {
1221    ValueToValueMapTy VMap;
1222    UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1223    UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1224    UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1225    F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1226  }
1227
1228  // Instrument.
1229  int NumInstrumented = 0;
1230  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1231    Instruction *Inst = ToInstrument[i];
1232    if (ClDebugMin < 0 || ClDebugMax < 0 ||
1233        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1234      if (isInterestingMemoryAccess(Inst, &IsWrite))
1235        instrumentMop(Inst);
1236      else
1237        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1238    }
1239    NumInstrumented++;
1240  }
1241
1242  FunctionStackPoisoner FSP(F, *this);
1243  bool ChangedStack = FSP.runOnFunction();
1244
1245  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1246  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1247  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1248    Instruction *CI = NoReturnCalls[i];
1249    IRBuilder<> IRB(CI);
1250    IRB.CreateCall(AsanHandleNoReturnFunc);
1251  }
1252
1253  bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1254  DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1255
1256  if (ClKeepUninstrumented) {
1257    if (!res) {
1258      // No instrumentation is done, no need for the duplicate.
1259      if (UninstrumentedDuplicate)
1260        UninstrumentedDuplicate->eraseFromParent();
1261    } else {
1262      // The function was instrumented. We must have the duplicate.
1263      assert(UninstrumentedDuplicate);
1264      UninstrumentedDuplicate->setSection("NOASAN");
1265      assert(!F.hasSection());
1266      F.setSection("ASAN");
1267    }
1268  }
1269
1270  return res;
1271}
1272
1273static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1274  if (ShadowRedzoneSize == 1) return PoisonByte;
1275  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1276  if (ShadowRedzoneSize == 4)
1277    return (PoisonByte << 24) + (PoisonByte << 16) +
1278        (PoisonByte << 8) + (PoisonByte);
1279  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1280}
1281
1282static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1283                                            size_t Size,
1284                                            size_t RZSize,
1285                                            size_t ShadowGranularity,
1286                                            uint8_t Magic) {
1287  for (size_t i = 0; i < RZSize;
1288       i+= ShadowGranularity, Shadow++) {
1289    if (i + ShadowGranularity <= Size) {
1290      *Shadow = 0;  // fully addressable
1291    } else if (i >= Size) {
1292      *Shadow = Magic;  // unaddressable
1293    } else {
1294      *Shadow = Size - i;  // first Size-i bytes are addressable
1295    }
1296  }
1297}
1298
1299// Workaround for bug 11395: we don't want to instrument stack in functions
1300// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1301// FIXME: remove once the bug 11395 is fixed.
1302bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1303  if (LongSize != 32) return false;
1304  CallInst *CI = dyn_cast<CallInst>(I);
1305  if (!CI || !CI->isInlineAsm()) return false;
1306  if (CI->getNumArgOperands() <= 5) return false;
1307  // We have inline assembly with quite a few arguments.
1308  return true;
1309}
1310
1311void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1312  IRBuilder<> IRB(*C);
1313  for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1314    std::string Suffix = itostr(i);
1315    AsanStackMallocFunc[i] = checkInterfaceFunction(
1316        M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1317                              IntptrTy, IntptrTy, NULL));
1318    AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1319        kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1320        IntptrTy, IntptrTy, NULL));
1321  }
1322  AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1323      kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1324  AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1325      kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1326}
1327
1328void FunctionStackPoisoner::poisonRedZones(
1329  const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> &IRB, Value *ShadowBase,
1330  bool DoPoison) {
1331  size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1332  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1333  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1334  Type *RZPtrTy = PointerType::get(RZTy, 0);
1335
1336  Value *PoisonLeft  = ConstantInt::get(RZTy,
1337    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1338  Value *PoisonMid   = ConstantInt::get(RZTy,
1339    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1340  Value *PoisonRight = ConstantInt::get(RZTy,
1341    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1342
1343  // poison the first red zone.
1344  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1345
1346  // poison all other red zones.
1347  uint64_t Pos = RedzoneSize();
1348  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1349    AllocaInst *AI = AllocaVec[i];
1350    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1351    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1352    assert(AlignedSize - SizeInBytes < RedzoneSize());
1353    Value *Ptr = NULL;
1354
1355    Pos += AlignedSize;
1356
1357    assert(ShadowBase->getType() == IntptrTy);
1358    if (SizeInBytes < AlignedSize) {
1359      // Poison the partial redzone at right
1360      Ptr = IRB.CreateAdd(
1361          ShadowBase, ConstantInt::get(IntptrTy,
1362                                       (Pos >> Mapping.Scale) - ShadowRZSize));
1363      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1364      uint32_t Poison = 0;
1365      if (DoPoison) {
1366        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1367                                        RedzoneSize(),
1368                                        1ULL << Mapping.Scale,
1369                                        kAsanStackPartialRedzoneMagic);
1370        Poison =
1371            ASan.TD->isLittleEndian()
1372                ? support::endian::byte_swap<uint32_t, support::little>(Poison)
1373                : support::endian::byte_swap<uint32_t, support::big>(Poison);
1374      }
1375      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1376      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1377    }
1378
1379    // Poison the full redzone at right.
1380    Ptr = IRB.CreateAdd(ShadowBase,
1381                        ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1382    bool LastAlloca = (i == AllocaVec.size() - 1);
1383    Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1384    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1385
1386    Pos += RedzoneSize();
1387  }
1388}
1389
1390// Fake stack allocator (asan_fake_stack.h) has 11 size classes
1391// for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1392static int StackMallocSizeClass(uint64_t LocalStackSize) {
1393  assert(LocalStackSize <= kMaxStackMallocSize);
1394  uint64_t MaxSize = kMinStackMallocSize;
1395  for (int i = 0; ; i++, MaxSize *= 2)
1396    if (LocalStackSize <= MaxSize)
1397      return i;
1398  llvm_unreachable("impossible LocalStackSize");
1399}
1400
1401// Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1402// We can not use MemSet intrinsic because it may end up calling the actual
1403// memset. Size is a multiple of 8.
1404// Currently this generates 8-byte stores on x86_64; it may be better to
1405// generate wider stores.
1406void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1407    IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1408  assert(!(Size % 8));
1409  assert(kAsanStackAfterReturnMagic == 0xf5);
1410  for (int i = 0; i < Size; i += 8) {
1411    Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1412    IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1413                    IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1414  }
1415}
1416
1417void FunctionStackPoisoner::poisonStack() {
1418  uint64_t LocalStackSize = TotalStackSize +
1419                            (AllocaVec.size() + 1) * RedzoneSize();
1420
1421  bool DoStackMalloc = ASan.CheckUseAfterReturn
1422      && LocalStackSize <= kMaxStackMallocSize;
1423  int StackMallocIdx = -1;
1424
1425  assert(AllocaVec.size() > 0);
1426  Instruction *InsBefore = AllocaVec[0];
1427  IRBuilder<> IRB(InsBefore);
1428
1429
1430  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1431  AllocaInst *MyAlloca =
1432      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1433  if (ClRealignStack && StackAlignment < RedzoneSize())
1434    StackAlignment = RedzoneSize();
1435  MyAlloca->setAlignment(StackAlignment);
1436  assert(MyAlloca->isStaticAlloca());
1437  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1438  Value *LocalStackBase = OrigStackBase;
1439
1440  if (DoStackMalloc) {
1441    // LocalStackBase = OrigStackBase
1442    // if (__asan_option_detect_stack_use_after_return)
1443    //   LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1444    StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1445    assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1446    Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1447        kAsanOptionDetectUAR, IRB.getInt32Ty());
1448    Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1449                                  Constant::getNullValue(IRB.getInt32Ty()));
1450    Instruction *Term =
1451        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
1452    BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1453    IRBuilder<> IRBIf(Term);
1454    LocalStackBase = IRBIf.CreateCall2(
1455        AsanStackMallocFunc[StackMallocIdx],
1456        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1457    BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1458    IRB.SetInsertPoint(InsBefore);
1459    PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1460    Phi->addIncoming(OrigStackBase, CmpBlock);
1461    Phi->addIncoming(LocalStackBase, SetBlock);
1462    LocalStackBase = Phi;
1463  }
1464
1465  // This string will be parsed by the run-time (DescribeAddressIfStack).
1466  SmallString<2048> StackDescriptionStorage;
1467  raw_svector_ostream StackDescription(StackDescriptionStorage);
1468  StackDescription << AllocaVec.size() << " ";
1469
1470  // Insert poison calls for lifetime intrinsics for alloca.
1471  bool HavePoisonedAllocas = false;
1472  for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1473    const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1474    IntrinsicInst *II = APC.InsBefore;
1475    AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1476    assert(AI);
1477    IRBuilder<> IRB(II);
1478    poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1479    HavePoisonedAllocas |= APC.DoPoison;
1480  }
1481
1482  uint64_t Pos = RedzoneSize();
1483  // Replace Alloca instructions with base+offset.
1484  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1485    AllocaInst *AI = AllocaVec[i];
1486    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1487    StringRef Name = AI->getName();
1488    StackDescription << Pos << " " << SizeInBytes << " "
1489                     << Name.size() << " " << Name << " ";
1490    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1491    assert((AlignedSize % RedzoneSize()) == 0);
1492    Value *NewAllocaPtr = IRB.CreateIntToPtr(
1493            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1494            AI->getType());
1495    replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1496    AI->replaceAllUsesWith(NewAllocaPtr);
1497    Pos += AlignedSize + RedzoneSize();
1498  }
1499  assert(Pos == LocalStackSize);
1500
1501  // The left-most redzone has enough space for at least 4 pointers.
1502  // Write the Magic value to redzone[0].
1503  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1504  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1505                  BasePlus0);
1506  // Write the frame description constant to redzone[1].
1507  Value *BasePlus1 = IRB.CreateIntToPtr(
1508    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1509    IntptrPtrTy);
1510  GlobalVariable *StackDescriptionGlobal =
1511      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1512  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1513                                             IntptrTy);
1514  IRB.CreateStore(Description, BasePlus1);
1515  // Write the PC to redzone[2].
1516  Value *BasePlus2 = IRB.CreateIntToPtr(
1517    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1518                                                   2 * ASan.LongSize/8)),
1519    IntptrPtrTy);
1520  IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1521
1522  // Poison the stack redzones at the entry.
1523  Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1524  poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1525
1526  // Unpoison the stack before all ret instructions.
1527  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1528    Instruction *Ret = RetVec[i];
1529    IRBuilder<> IRBRet(Ret);
1530    // Mark the current frame as retired.
1531    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1532                       BasePlus0);
1533    // Unpoison the stack.
1534    poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1535    if (DoStackMalloc) {
1536      assert(StackMallocIdx >= 0);
1537      // In use-after-return mode, mark the whole stack frame unaddressable.
1538      if (StackMallocIdx <= 4) {
1539        // For small sizes inline the whole thing:
1540        // if LocalStackBase != OrigStackBase:
1541        //     memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1542        //     **SavedFlagPtr(LocalStackBase) = 0
1543        // FIXME: if LocalStackBase != OrigStackBase don't call poisonRedZones.
1544        Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1545        TerminatorInst *PoisonTerm =
1546            SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
1547        IRBuilder<> IRBPoison(PoisonTerm);
1548        int ClassSize = kMinStackMallocSize << StackMallocIdx;
1549        SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1550                                           ClassSize >> Mapping.Scale);
1551        Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1552            LocalStackBase,
1553            ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1554        Value *SavedFlagPtr = IRBPoison.CreateLoad(
1555            IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1556        IRBPoison.CreateStore(
1557            Constant::getNullValue(IRBPoison.getInt8Ty()),
1558            IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1559      } else {
1560        // For larger frames call __asan_stack_free_*.
1561        IRBRet.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1562                           ConstantInt::get(IntptrTy, LocalStackSize),
1563                           OrigStackBase);
1564      }
1565    } else if (HavePoisonedAllocas) {
1566      // If we poisoned some allocas in llvm.lifetime analysis,
1567      // unpoison whole stack frame now.
1568      assert(LocalStackBase == OrigStackBase);
1569      poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1570    }
1571  }
1572
1573  // We are done. Remove the old unused alloca instructions.
1574  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1575    AllocaVec[i]->eraseFromParent();
1576}
1577
1578void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1579                                         IRBuilder<> &IRB, bool DoPoison) {
1580  // For now just insert the call to ASan runtime.
1581  Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1582  Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1583  IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1584                           : AsanUnpoisonStackMemoryFunc,
1585                  AddrArg, SizeArg);
1586}
1587
1588// Handling llvm.lifetime intrinsics for a given %alloca:
1589// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1590// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1591//     invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1592//     could be poisoned by previous llvm.lifetime.end instruction, as the
1593//     variable may go in and out of scope several times, e.g. in loops).
1594// (3) if we poisoned at least one %alloca in a function,
1595//     unpoison the whole stack frame at function exit.
1596
1597AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1598  if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1599    // We're intested only in allocas we can handle.
1600    return isInterestingAlloca(*AI) ? AI : 0;
1601  // See if we've already calculated (or started to calculate) alloca for a
1602  // given value.
1603  AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1604  if (I != AllocaForValue.end())
1605    return I->second;
1606  // Store 0 while we're calculating alloca for value V to avoid
1607  // infinite recursion if the value references itself.
1608  AllocaForValue[V] = 0;
1609  AllocaInst *Res = 0;
1610  if (CastInst *CI = dyn_cast<CastInst>(V))
1611    Res = findAllocaForValue(CI->getOperand(0));
1612  else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1613    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1614      Value *IncValue = PN->getIncomingValue(i);
1615      // Allow self-referencing phi-nodes.
1616      if (IncValue == PN) continue;
1617      AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1618      // AI for incoming values should exist and should all be equal.
1619      if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1620        return 0;
1621      Res = IncValueAI;
1622    }
1623  }
1624  if (Res != 0)
1625    AllocaForValue[V] = Res;
1626  return Res;
1627}
1628