1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
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 // Coverage instrumentation that works with AddressSanitizer
11 // and potentially with other Sanitizers.
12 //
13 // We create a Guard variable with the same linkage
14 // as the function and inject this code into the entry block (SCK_Function)
15 // or all blocks (SCK_BB):
16 // if (Guard < 0) {
17 // __sanitizer_cov(&Guard);
18 // }
19 // The accesses to Guard are atomic. The rest of the logic is
20 // in __sanitizer_cov (it's fine to call it more than once).
21 //
22 // With SCK_Edge we also split critical edges this effectively
23 // instrumenting all edges.
24 //
25 // This coverage implementation provides very limited data:
26 // it only tells if a given function (block) was ever executed. No counters.
27 // But for many use cases this is what we need and the added slowdown small.
28 //
29 //===----------------------------------------------------------------------===//
30
31 #include "llvm/ADT/ArrayRef.h"
32 #include "llvm/ADT/SmallVector.h"
33 #include "llvm/Analysis/EHPersonalities.h"
34 #include "llvm/Analysis/PostDominators.h"
35 #include "llvm/IR/CFG.h"
36 #include "llvm/IR/CallSite.h"
37 #include "llvm/IR/DataLayout.h"
38 #include "llvm/IR/DebugInfo.h"
39 #include "llvm/IR/Dominators.h"
40 #include "llvm/IR/Function.h"
41 #include "llvm/IR/IRBuilder.h"
42 #include "llvm/IR/InlineAsm.h"
43 #include "llvm/IR/LLVMContext.h"
44 #include "llvm/IR/MDBuilder.h"
45 #include "llvm/IR/Module.h"
46 #include "llvm/IR/Type.h"
47 #include "llvm/Support/CommandLine.h"
48 #include "llvm/Support/Debug.h"
49 #include "llvm/Support/raw_ostream.h"
50 #include "llvm/Transforms/Instrumentation.h"
51 #include "llvm/Transforms/Scalar.h"
52 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
53 #include "llvm/Transforms/Utils/ModuleUtils.h"
54
55 using namespace llvm;
56
57 #define DEBUG_TYPE "sancov"
58
59 static const char *const SanCovModuleInitName = "__sanitizer_cov_module_init";
60 static const char *const SanCovName = "__sanitizer_cov";
61 static const char *const SanCovWithCheckName = "__sanitizer_cov_with_check";
62 static const char *const SanCovIndirCallName = "__sanitizer_cov_indir_call16";
63 static const char *const SanCovTracePCIndirName =
64 "__sanitizer_cov_trace_pc_indir";
65 static const char *const SanCovTraceEnterName =
66 "__sanitizer_cov_trace_func_enter";
67 static const char *const SanCovTraceBBName =
68 "__sanitizer_cov_trace_basic_block";
69 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
70 static const char *const SanCovTraceCmpName = "__sanitizer_cov_trace_cmp";
71 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
72 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
73 static const uint64_t SanCtorAndDtorPriority = 2;
74
75 static cl::opt<int> ClCoverageLevel(
76 "sanitizer-coverage-level",
77 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
78 "3: all blocks and critical edges, "
79 "4: above plus indirect calls"),
80 cl::Hidden, cl::init(0));
81
82 static cl::opt<unsigned> ClCoverageBlockThreshold(
83 "sanitizer-coverage-block-threshold",
84 cl::desc("Use a callback with a guard check inside it if there are"
85 " more than this number of blocks."),
86 cl::Hidden, cl::init(500));
87
88 static cl::opt<bool>
89 ClExperimentalTracing("sanitizer-coverage-experimental-tracing",
90 cl::desc("Experimental basic-block tracing: insert "
91 "callbacks at every basic block"),
92 cl::Hidden, cl::init(false));
93
94 static cl::opt<bool> ClExperimentalTracePC("sanitizer-coverage-trace-pc",
95 cl::desc("Experimental pc tracing"),
96 cl::Hidden, cl::init(false));
97
98 static cl::opt<bool>
99 ClExperimentalCMPTracing("sanitizer-coverage-experimental-trace-compares",
100 cl::desc("Experimental tracing of CMP and similar "
101 "instructions"),
102 cl::Hidden, cl::init(false));
103
104 static cl::opt<bool>
105 ClPruneBlocks("sanitizer-coverage-prune-blocks",
106 cl::desc("Reduce the number of instrumented blocks"),
107 cl::Hidden, cl::init(true));
108
109 // Experimental 8-bit counters used as an additional search heuristic during
110 // coverage-guided fuzzing.
111 // The counters are not thread-friendly:
112 // - contention on these counters may cause significant slowdown;
113 // - the counter updates are racy and the results may be inaccurate.
114 // They are also inaccurate due to 8-bit integer overflow.
115 static cl::opt<bool> ClUse8bitCounters("sanitizer-coverage-8bit-counters",
116 cl::desc("Experimental 8-bit counters"),
117 cl::Hidden, cl::init(false));
118
119 namespace {
120
getOptions(int LegacyCoverageLevel)121 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
122 SanitizerCoverageOptions Res;
123 switch (LegacyCoverageLevel) {
124 case 0:
125 Res.CoverageType = SanitizerCoverageOptions::SCK_None;
126 break;
127 case 1:
128 Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
129 break;
130 case 2:
131 Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
132 break;
133 case 3:
134 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
135 break;
136 case 4:
137 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
138 Res.IndirectCalls = true;
139 break;
140 }
141 return Res;
142 }
143
OverrideFromCL(SanitizerCoverageOptions Options)144 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
145 // Sets CoverageType and IndirectCalls.
146 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
147 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
148 Options.IndirectCalls |= CLOpts.IndirectCalls;
149 Options.TraceBB |= ClExperimentalTracing;
150 Options.TraceCmp |= ClExperimentalCMPTracing;
151 Options.Use8bitCounters |= ClUse8bitCounters;
152 Options.TracePC |= ClExperimentalTracePC;
153 return Options;
154 }
155
156 class SanitizerCoverageModule : public ModulePass {
157 public:
SanitizerCoverageModule(const SanitizerCoverageOptions & Options=SanitizerCoverageOptions ())158 SanitizerCoverageModule(
159 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
160 : ModulePass(ID), Options(OverrideFromCL(Options)) {
161 initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
162 }
163 bool runOnModule(Module &M) override;
164 bool runOnFunction(Function &F);
165 static char ID; // Pass identification, replacement for typeid
getPassName() const166 const char *getPassName() const override { return "SanitizerCoverageModule"; }
167
getAnalysisUsage(AnalysisUsage & AU) const168 void getAnalysisUsage(AnalysisUsage &AU) const override {
169 AU.addRequired<DominatorTreeWrapperPass>();
170 AU.addRequired<PostDominatorTreeWrapperPass>();
171 }
172
173 private:
174 void InjectCoverageForIndirectCalls(Function &F,
175 ArrayRef<Instruction *> IndirCalls);
176 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
177 void InjectTraceForSwitch(Function &F,
178 ArrayRef<Instruction *> SwitchTraceTargets);
179 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
180 void SetNoSanitizeMetadata(Instruction *I);
181 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, bool UseCalls);
NumberOfInstrumentedBlocks()182 unsigned NumberOfInstrumentedBlocks() {
183 return SanCovFunction->getNumUses() +
184 SanCovWithCheckFunction->getNumUses() + SanCovTraceBB->getNumUses() +
185 SanCovTraceEnter->getNumUses();
186 }
187 Function *SanCovFunction;
188 Function *SanCovWithCheckFunction;
189 Function *SanCovIndirCallFunction, *SanCovTracePCIndir;
190 Function *SanCovTraceEnter, *SanCovTraceBB, *SanCovTracePC;
191 Function *SanCovTraceCmpFunction;
192 Function *SanCovTraceSwitchFunction;
193 InlineAsm *EmptyAsm;
194 Type *IntptrTy, *Int64Ty, *Int64PtrTy;
195 Module *CurModule;
196 LLVMContext *C;
197 const DataLayout *DL;
198
199 GlobalVariable *GuardArray;
200 GlobalVariable *EightBitCounterArray;
201
202 SanitizerCoverageOptions Options;
203 };
204
205 } // namespace
206
runOnModule(Module & M)207 bool SanitizerCoverageModule::runOnModule(Module &M) {
208 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
209 return false;
210 C = &(M.getContext());
211 DL = &M.getDataLayout();
212 CurModule = &M;
213 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
214 Type *VoidTy = Type::getVoidTy(*C);
215 IRBuilder<> IRB(*C);
216 Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
217 Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
218 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
219 Int64Ty = IRB.getInt64Ty();
220
221 SanCovFunction = checkSanitizerInterfaceFunction(
222 M.getOrInsertFunction(SanCovName, VoidTy, Int32PtrTy, nullptr));
223 SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
224 M.getOrInsertFunction(SanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
225 SanCovTracePCIndir = checkSanitizerInterfaceFunction(
226 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy, nullptr));
227 SanCovIndirCallFunction =
228 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
229 SanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
230 SanCovTraceCmpFunction =
231 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
232 SanCovTraceCmpName, VoidTy, Int64Ty, Int64Ty, Int64Ty, nullptr));
233 SanCovTraceSwitchFunction =
234 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
235 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy, nullptr));
236
237 // We insert an empty inline asm after cov callbacks to avoid callback merge.
238 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
239 StringRef(""), StringRef(""),
240 /*hasSideEffects=*/true);
241
242 SanCovTracePC = checkSanitizerInterfaceFunction(
243 M.getOrInsertFunction(SanCovTracePCName, VoidTy, nullptr));
244 SanCovTraceEnter = checkSanitizerInterfaceFunction(
245 M.getOrInsertFunction(SanCovTraceEnterName, VoidTy, Int32PtrTy, nullptr));
246 SanCovTraceBB = checkSanitizerInterfaceFunction(
247 M.getOrInsertFunction(SanCovTraceBBName, VoidTy, Int32PtrTy, nullptr));
248
249 // At this point we create a dummy array of guards because we don't
250 // know how many elements we will need.
251 Type *Int32Ty = IRB.getInt32Ty();
252 Type *Int8Ty = IRB.getInt8Ty();
253
254 GuardArray =
255 new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
256 nullptr, "__sancov_gen_cov_tmp");
257 if (Options.Use8bitCounters)
258 EightBitCounterArray =
259 new GlobalVariable(M, Int8Ty, false, GlobalVariable::ExternalLinkage,
260 nullptr, "__sancov_gen_cov_tmp");
261
262 for (auto &F : M)
263 runOnFunction(F);
264
265 auto N = NumberOfInstrumentedBlocks();
266
267 // Now we know how many elements we need. Create an array of guards
268 // with one extra element at the beginning for the size.
269 Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
270 GlobalVariable *RealGuardArray = new GlobalVariable(
271 M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
272 Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
273
274 // Replace the dummy array with the real one.
275 GuardArray->replaceAllUsesWith(
276 IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
277 GuardArray->eraseFromParent();
278
279 GlobalVariable *RealEightBitCounterArray;
280 if (Options.Use8bitCounters) {
281 // Make sure the array is 16-aligned.
282 static const int CounterAlignment = 16;
283 Type *Int8ArrayNTy = ArrayType::get(Int8Ty, alignTo(N, CounterAlignment));
284 RealEightBitCounterArray = new GlobalVariable(
285 M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage,
286 Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter");
287 RealEightBitCounterArray->setAlignment(CounterAlignment);
288 EightBitCounterArray->replaceAllUsesWith(
289 IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy));
290 EightBitCounterArray->eraseFromParent();
291 }
292
293 // Create variable for module (compilation unit) name
294 Constant *ModNameStrConst =
295 ConstantDataArray::getString(M.getContext(), M.getName(), true);
296 GlobalVariable *ModuleName =
297 new GlobalVariable(M, ModNameStrConst->getType(), true,
298 GlobalValue::PrivateLinkage, ModNameStrConst);
299
300 if (!Options.TracePC) {
301 Function *CtorFunc;
302 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
303 M, SanCovModuleCtorName, SanCovModuleInitName,
304 {Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy},
305 {IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
306 ConstantInt::get(IntptrTy, N),
307 Options.Use8bitCounters
308 ? IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy)
309 : Constant::getNullValue(Int8PtrTy),
310 IRB.CreatePointerCast(ModuleName, Int8PtrTy)});
311
312 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
313 }
314
315 return true;
316 }
317
318 // True if block has successors and it dominates all of them.
isFullDominator(const BasicBlock * BB,const DominatorTree * DT)319 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
320 if (succ_begin(BB) == succ_end(BB))
321 return false;
322
323 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
324 if (!DT->dominates(BB, SUCC))
325 return false;
326 }
327
328 return true;
329 }
330
331 // True if block has predecessors and it postdominates all of them.
isFullPostDominator(const BasicBlock * BB,const PostDominatorTree * PDT)332 static bool isFullPostDominator(const BasicBlock *BB,
333 const PostDominatorTree *PDT) {
334 if (pred_begin(BB) == pred_end(BB))
335 return false;
336
337 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
338 if (!PDT->dominates(BB, PRED))
339 return false;
340 }
341
342 return true;
343 }
344
shouldInstrumentBlock(const Function & F,const BasicBlock * BB,const DominatorTree * DT,const PostDominatorTree * PDT)345 static bool shouldInstrumentBlock(const Function& F, const BasicBlock *BB, const DominatorTree *DT,
346 const PostDominatorTree *PDT) {
347 if (!ClPruneBlocks || &F.getEntryBlock() == BB)
348 return true;
349
350 return !(isFullDominator(BB, DT) || isFullPostDominator(BB, PDT));
351 }
352
runOnFunction(Function & F)353 bool SanitizerCoverageModule::runOnFunction(Function &F) {
354 if (F.empty())
355 return false;
356 if (F.getName().find(".module_ctor") != std::string::npos)
357 return false; // Should not instrument sanitizer init functions.
358 // Don't instrument functions using SEH for now. Splitting basic blocks like
359 // we do for coverage breaks WinEHPrepare.
360 // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
361 if (F.hasPersonalityFn() &&
362 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
363 return false;
364 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
365 SplitAllCriticalEdges(F);
366 SmallVector<Instruction *, 8> IndirCalls;
367 SmallVector<BasicBlock *, 16> BlocksToInstrument;
368 SmallVector<Instruction *, 8> CmpTraceTargets;
369 SmallVector<Instruction *, 8> SwitchTraceTargets;
370
371 const DominatorTree *DT =
372 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
373 const PostDominatorTree *PDT =
374 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
375
376 for (auto &BB : F) {
377 if (shouldInstrumentBlock(F, &BB, DT, PDT))
378 BlocksToInstrument.push_back(&BB);
379 for (auto &Inst : BB) {
380 if (Options.IndirectCalls) {
381 CallSite CS(&Inst);
382 if (CS && !CS.getCalledFunction())
383 IndirCalls.push_back(&Inst);
384 }
385 if (Options.TraceCmp) {
386 if (isa<ICmpInst>(&Inst))
387 CmpTraceTargets.push_back(&Inst);
388 if (isa<SwitchInst>(&Inst))
389 SwitchTraceTargets.push_back(&Inst);
390 }
391 }
392 }
393
394 InjectCoverage(F, BlocksToInstrument);
395 InjectCoverageForIndirectCalls(F, IndirCalls);
396 InjectTraceForCmp(F, CmpTraceTargets);
397 InjectTraceForSwitch(F, SwitchTraceTargets);
398 return true;
399 }
400
InjectCoverage(Function & F,ArrayRef<BasicBlock * > AllBlocks)401 bool SanitizerCoverageModule::InjectCoverage(Function &F,
402 ArrayRef<BasicBlock *> AllBlocks) {
403 switch (Options.CoverageType) {
404 case SanitizerCoverageOptions::SCK_None:
405 return false;
406 case SanitizerCoverageOptions::SCK_Function:
407 InjectCoverageAtBlock(F, F.getEntryBlock(), false);
408 return true;
409 default: {
410 bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
411 for (auto BB : AllBlocks)
412 InjectCoverageAtBlock(F, *BB, UseCalls);
413 return true;
414 }
415 }
416 }
417
418 // On every indirect call we call a run-time function
419 // __sanitizer_cov_indir_call* with two parameters:
420 // - callee address,
421 // - global cache array that contains CacheSize pointers (zero-initialized).
422 // The cache is used to speed up recording the caller-callee pairs.
423 // The address of the caller is passed implicitly via caller PC.
424 // CacheSize is encoded in the name of the run-time function.
InjectCoverageForIndirectCalls(Function & F,ArrayRef<Instruction * > IndirCalls)425 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
426 Function &F, ArrayRef<Instruction *> IndirCalls) {
427 if (IndirCalls.empty())
428 return;
429 const int CacheSize = 16;
430 const int CacheAlignment = 64; // Align for better performance.
431 Type *Ty = ArrayType::get(IntptrTy, CacheSize);
432 for (auto I : IndirCalls) {
433 IRBuilder<> IRB(I);
434 CallSite CS(I);
435 Value *Callee = CS.getCalledValue();
436 if (isa<InlineAsm>(Callee))
437 continue;
438 GlobalVariable *CalleeCache = new GlobalVariable(
439 *F.getParent(), Ty, false, GlobalValue::PrivateLinkage,
440 Constant::getNullValue(Ty), "__sancov_gen_callee_cache");
441 CalleeCache->setAlignment(CacheAlignment);
442 if (Options.TracePC)
443 IRB.CreateCall(SanCovTracePCIndir,
444 IRB.CreatePointerCast(Callee, IntptrTy));
445 else
446 IRB.CreateCall(SanCovIndirCallFunction,
447 {IRB.CreatePointerCast(Callee, IntptrTy),
448 IRB.CreatePointerCast(CalleeCache, IntptrTy)});
449 }
450 }
451
452 // For every switch statement we insert a call:
453 // __sanitizer_cov_trace_switch(CondValue,
454 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
455
InjectTraceForSwitch(Function &,ArrayRef<Instruction * > SwitchTraceTargets)456 void SanitizerCoverageModule::InjectTraceForSwitch(
457 Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
458 for (auto I : SwitchTraceTargets) {
459 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
460 IRBuilder<> IRB(I);
461 SmallVector<Constant *, 16> Initializers;
462 Value *Cond = SI->getCondition();
463 if (Cond->getType()->getScalarSizeInBits() >
464 Int64Ty->getScalarSizeInBits())
465 continue;
466 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
467 Initializers.push_back(
468 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
469 if (Cond->getType()->getScalarSizeInBits() <
470 Int64Ty->getScalarSizeInBits())
471 Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
472 for (auto It : SI->cases()) {
473 Constant *C = It.getCaseValue();
474 if (C->getType()->getScalarSizeInBits() <
475 Int64Ty->getScalarSizeInBits())
476 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
477 Initializers.push_back(C);
478 }
479 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
480 GlobalVariable *GV = new GlobalVariable(
481 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
482 ConstantArray::get(ArrayOfInt64Ty, Initializers),
483 "__sancov_gen_cov_switch_values");
484 IRB.CreateCall(SanCovTraceSwitchFunction,
485 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
486 }
487 }
488 }
489
InjectTraceForCmp(Function &,ArrayRef<Instruction * > CmpTraceTargets)490 void SanitizerCoverageModule::InjectTraceForCmp(
491 Function &, ArrayRef<Instruction *> CmpTraceTargets) {
492 for (auto I : CmpTraceTargets) {
493 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
494 IRBuilder<> IRB(ICMP);
495 Value *A0 = ICMP->getOperand(0);
496 Value *A1 = ICMP->getOperand(1);
497 if (!A0->getType()->isIntegerTy())
498 continue;
499 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
500 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
501 IRB.CreateCall(
502 SanCovTraceCmpFunction,
503 {ConstantInt::get(Int64Ty, (TypeSize << 32) | ICMP->getPredicate()),
504 IRB.CreateIntCast(A0, Int64Ty, true),
505 IRB.CreateIntCast(A1, Int64Ty, true)});
506 }
507 }
508 }
509
SetNoSanitizeMetadata(Instruction * I)510 void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
511 I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
512 MDNode::get(*C, None));
513 }
514
InjectCoverageAtBlock(Function & F,BasicBlock & BB,bool UseCalls)515 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
516 bool UseCalls) {
517 // Don't insert coverage for unreachable blocks: we will never call
518 // __sanitizer_cov() for them, so counting them in
519 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
520 // percentage. Also, unreachable instructions frequently have no debug
521 // locations.
522 if (isa<UnreachableInst>(BB.getTerminator()))
523 return;
524 BasicBlock::iterator IP = BB.getFirstInsertionPt();
525
526 bool IsEntryBB = &BB == &F.getEntryBlock();
527 DebugLoc EntryLoc;
528 if (IsEntryBB) {
529 if (auto SP = F.getSubprogram())
530 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
531 // Keep static allocas and llvm.localescape calls in the entry block. Even
532 // if we aren't splitting the block, it's nice for allocas to be before
533 // calls.
534 IP = PrepareToSplitEntryBlock(BB, IP);
535 } else {
536 EntryLoc = IP->getDebugLoc();
537 }
538
539 IRBuilder<> IRB(&*IP);
540 IRB.SetCurrentDebugLocation(EntryLoc);
541 Value *GuardP = IRB.CreateAdd(
542 IRB.CreatePointerCast(GuardArray, IntptrTy),
543 ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
544 Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
545 GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
546 if (Options.TracePC) {
547 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
548 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
549 } else if (Options.TraceBB) {
550 IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
551 } else if (UseCalls) {
552 IRB.CreateCall(SanCovWithCheckFunction, GuardP);
553 } else {
554 LoadInst *Load = IRB.CreateLoad(GuardP);
555 Load->setAtomic(AtomicOrdering::Monotonic);
556 Load->setAlignment(4);
557 SetNoSanitizeMetadata(Load);
558 Value *Cmp =
559 IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
560 Instruction *Ins = SplitBlockAndInsertIfThen(
561 Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
562 IRB.SetInsertPoint(Ins);
563 IRB.SetCurrentDebugLocation(EntryLoc);
564 // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
565 IRB.CreateCall(SanCovFunction, GuardP);
566 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
567 }
568
569 if (Options.Use8bitCounters) {
570 IRB.SetInsertPoint(&*IP);
571 Value *P = IRB.CreateAdd(
572 IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
573 ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
574 P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
575 LoadInst *LI = IRB.CreateLoad(P);
576 Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
577 StoreInst *SI = IRB.CreateStore(Inc, P);
578 SetNoSanitizeMetadata(LI);
579 SetNoSanitizeMetadata(SI);
580 }
581 }
582
583 char SanitizerCoverageModule::ID = 0;
584 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
585 "SanitizerCoverage: TODO."
586 "ModulePass",
587 false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)588 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
589 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
590 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
591 "SanitizerCoverage: TODO."
592 "ModulePass",
593 false, false)
594 ModulePass *llvm::createSanitizerCoverageModulePass(
595 const SanitizerCoverageOptions &Options) {
596 return new SanitizerCoverageModule(Options);
597 }
598