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 done on LLVM IR level, works with Sanitizers.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/ADT/ArrayRef.h"
15 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/Analysis/EHPersonalities.h"
17 #include "llvm/Analysis/PostDominators.h"
18 #include "llvm/IR/CFG.h"
19 #include "llvm/IR/CallSite.h"
20 #include "llvm/IR/Constant.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/DebugInfo.h"
23 #include "llvm/IR/Dominators.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/IR/GlobalVariable.h"
26 #include "llvm/IR/IRBuilder.h"
27 #include "llvm/IR/InlineAsm.h"
28 #include "llvm/IR/IntrinsicInst.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/LLVMContext.h"
31 #include "llvm/IR/MDBuilder.h"
32 #include "llvm/IR/Mangler.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Type.h"
35 #include "llvm/Support/CommandLine.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/raw_ostream.h"
38 #include "llvm/Transforms/Instrumentation.h"
39 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
40 #include "llvm/Transforms/Utils/ModuleUtils.h"
41
42 using namespace llvm;
43
44 #define DEBUG_TYPE "sancov"
45
46 static const char *const SanCovTracePCIndirName =
47 "__sanitizer_cov_trace_pc_indir";
48 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
49 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
50 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
51 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
52 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
53 static const char *const SanCovTraceConstCmp1 =
54 "__sanitizer_cov_trace_const_cmp1";
55 static const char *const SanCovTraceConstCmp2 =
56 "__sanitizer_cov_trace_const_cmp2";
57 static const char *const SanCovTraceConstCmp4 =
58 "__sanitizer_cov_trace_const_cmp4";
59 static const char *const SanCovTraceConstCmp8 =
60 "__sanitizer_cov_trace_const_cmp8";
61 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
62 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
63 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
64 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
65 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
66 static const uint64_t SanCtorAndDtorPriority = 2;
67
68 static const char *const SanCovTracePCGuardName =
69 "__sanitizer_cov_trace_pc_guard";
70 static const char *const SanCovTracePCGuardInitName =
71 "__sanitizer_cov_trace_pc_guard_init";
72 static const char *const SanCov8bitCountersInitName =
73 "__sanitizer_cov_8bit_counters_init";
74 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
75
76 static const char *const SanCovGuardsSectionName = "sancov_guards";
77 static const char *const SanCovCountersSectionName = "sancov_cntrs";
78 static const char *const SanCovPCsSectionName = "sancov_pcs";
79
80 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
81
82 static cl::opt<int> ClCoverageLevel(
83 "sanitizer-coverage-level",
84 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
85 "3: all blocks and critical edges"),
86 cl::Hidden, cl::init(0));
87
88 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
89 cl::desc("Experimental pc tracing"), cl::Hidden,
90 cl::init(false));
91
92 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
93 cl::desc("pc tracing with a guard"),
94 cl::Hidden, cl::init(false));
95
96 // If true, we create a global variable that contains PCs of all instrumented
97 // BBs, put this global into a named section, and pass this section's bounds
98 // to __sanitizer_cov_pcs_init.
99 // This way the coverage instrumentation does not need to acquire the PCs
100 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
101 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
102 cl::desc("create a static PC table"),
103 cl::Hidden, cl::init(false));
104
105 static cl::opt<bool>
106 ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
107 cl::desc("increments 8-bit counter for every edge"),
108 cl::Hidden, cl::init(false));
109
110 static cl::opt<bool>
111 ClCMPTracing("sanitizer-coverage-trace-compares",
112 cl::desc("Tracing of CMP and similar instructions"),
113 cl::Hidden, cl::init(false));
114
115 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
116 cl::desc("Tracing of DIV instructions"),
117 cl::Hidden, cl::init(false));
118
119 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
120 cl::desc("Tracing of GEP instructions"),
121 cl::Hidden, cl::init(false));
122
123 static cl::opt<bool>
124 ClPruneBlocks("sanitizer-coverage-prune-blocks",
125 cl::desc("Reduce the number of instrumented blocks"),
126 cl::Hidden, cl::init(true));
127
128 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
129 cl::desc("max stack depth tracing"),
130 cl::Hidden, cl::init(false));
131
132 namespace {
133
getOptions(int LegacyCoverageLevel)134 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
135 SanitizerCoverageOptions Res;
136 switch (LegacyCoverageLevel) {
137 case 0:
138 Res.CoverageType = SanitizerCoverageOptions::SCK_None;
139 break;
140 case 1:
141 Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
142 break;
143 case 2:
144 Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
145 break;
146 case 3:
147 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
148 break;
149 case 4:
150 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
151 Res.IndirectCalls = true;
152 break;
153 }
154 return Res;
155 }
156
OverrideFromCL(SanitizerCoverageOptions Options)157 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
158 // Sets CoverageType and IndirectCalls.
159 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
160 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
161 Options.IndirectCalls |= CLOpts.IndirectCalls;
162 Options.TraceCmp |= ClCMPTracing;
163 Options.TraceDiv |= ClDIVTracing;
164 Options.TraceGep |= ClGEPTracing;
165 Options.TracePC |= ClTracePC;
166 Options.TracePCGuard |= ClTracePCGuard;
167 Options.Inline8bitCounters |= ClInline8bitCounters;
168 Options.PCTable |= ClCreatePCTable;
169 Options.NoPrune |= !ClPruneBlocks;
170 Options.StackDepth |= ClStackDepth;
171 if (!Options.TracePCGuard && !Options.TracePC &&
172 !Options.Inline8bitCounters && !Options.StackDepth)
173 Options.TracePCGuard = true; // TracePCGuard is default.
174 return Options;
175 }
176
177 class SanitizerCoverageModule : public ModulePass {
178 public:
SanitizerCoverageModule(const SanitizerCoverageOptions & Options=SanitizerCoverageOptions ())179 SanitizerCoverageModule(
180 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
181 : ModulePass(ID), Options(OverrideFromCL(Options)) {
182 initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
183 }
184 bool runOnModule(Module &M) override;
185 bool runOnFunction(Function &F);
186 static char ID; // Pass identification, replacement for typeid
getPassName() const187 StringRef getPassName() const override { return "SanitizerCoverageModule"; }
188
getAnalysisUsage(AnalysisUsage & AU) const189 void getAnalysisUsage(AnalysisUsage &AU) const override {
190 AU.addRequired<DominatorTreeWrapperPass>();
191 AU.addRequired<PostDominatorTreeWrapperPass>();
192 }
193
194 private:
195 void InjectCoverageForIndirectCalls(Function &F,
196 ArrayRef<Instruction *> IndirCalls);
197 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
198 void InjectTraceForDiv(Function &F,
199 ArrayRef<BinaryOperator *> DivTraceTargets);
200 void InjectTraceForGep(Function &F,
201 ArrayRef<GetElementPtrInst *> GepTraceTargets);
202 void InjectTraceForSwitch(Function &F,
203 ArrayRef<Instruction *> SwitchTraceTargets);
204 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
205 bool IsLeafFunc = true);
206 GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
207 Function &F, Type *Ty,
208 const char *Section);
209 GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
210 void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
211 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
212 bool IsLeafFunc = true);
213 Function *CreateInitCallsForSections(Module &M, const char *InitFunctionName,
214 Type *Ty, const char *Section);
215 std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
216 Type *Ty);
217
SetNoSanitizeMetadata(Instruction * I)218 void SetNoSanitizeMetadata(Instruction *I) {
219 I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
220 MDNode::get(*C, None));
221 }
222
223 std::string getSectionName(const std::string &Section) const;
224 std::string getSectionStart(const std::string &Section) const;
225 std::string getSectionEnd(const std::string &Section) const;
226 Function *SanCovTracePCIndir;
227 Function *SanCovTracePC, *SanCovTracePCGuard;
228 Function *SanCovTraceCmpFunction[4];
229 Function *SanCovTraceConstCmpFunction[4];
230 Function *SanCovTraceDivFunction[2];
231 Function *SanCovTraceGepFunction;
232 Function *SanCovTraceSwitchFunction;
233 GlobalVariable *SanCovLowestStack;
234 InlineAsm *EmptyAsm;
235 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
236 *Int16Ty, *Int8Ty, *Int8PtrTy;
237 Module *CurModule;
238 std::string CurModuleUniqueId;
239 Triple TargetTriple;
240 LLVMContext *C;
241 const DataLayout *DL;
242
243 GlobalVariable *FunctionGuardArray; // for trace-pc-guard.
244 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters.
245 GlobalVariable *FunctionPCsArray; // for pc-table.
246 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
247 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
248
249 SanitizerCoverageOptions Options;
250 };
251
252 } // namespace
253
254 std::pair<Value *, Value *>
CreateSecStartEnd(Module & M,const char * Section,Type * Ty)255 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section,
256 Type *Ty) {
257 GlobalVariable *SecStart =
258 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
259 getSectionStart(Section));
260 SecStart->setVisibility(GlobalValue::HiddenVisibility);
261 GlobalVariable *SecEnd =
262 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
263 nullptr, getSectionEnd(Section));
264 SecEnd->setVisibility(GlobalValue::HiddenVisibility);
265 IRBuilder<> IRB(M.getContext());
266 Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
267 if (!TargetTriple.isOSBinFormatCOFF())
268 return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
269
270 // Account for the fact that on windows-msvc __start_* symbols actually
271 // point to a uint64_t before the start of the array.
272 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
273 auto GEP = IRB.CreateGEP(SecStartI8Ptr,
274 ConstantInt::get(IntptrTy, sizeof(uint64_t)));
275 return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
276 }
277
CreateInitCallsForSections(Module & M,const char * InitFunctionName,Type * Ty,const char * Section)278 Function *SanitizerCoverageModule::CreateInitCallsForSections(
279 Module &M, const char *InitFunctionName, Type *Ty,
280 const char *Section) {
281 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
282 auto SecStart = SecStartEnd.first;
283 auto SecEnd = SecStartEnd.second;
284 Function *CtorFunc;
285 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
286 M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
287
288 if (TargetTriple.supportsCOMDAT()) {
289 // Use comdat to dedup CtorFunc.
290 CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
291 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
292 } else {
293 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
294 }
295
296 if (TargetTriple.isOSBinFormatCOFF()) {
297 // In COFF files, if the contructors are set as COMDAT (they are because
298 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
299 // functions and data) is used, the constructors get stripped. To prevent
300 // this, give the constructors weak ODR linkage and ensure the linker knows
301 // to include the sancov constructor. This way the linker can deduplicate
302 // the constructors but always leave one copy.
303 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
304 appendToUsed(M, CtorFunc);
305 }
306 return CtorFunc;
307 }
308
runOnModule(Module & M)309 bool SanitizerCoverageModule::runOnModule(Module &M) {
310 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
311 return false;
312 C = &(M.getContext());
313 DL = &M.getDataLayout();
314 CurModule = &M;
315 CurModuleUniqueId = getUniqueModuleId(CurModule);
316 TargetTriple = Triple(M.getTargetTriple());
317 FunctionGuardArray = nullptr;
318 Function8bitCounterArray = nullptr;
319 FunctionPCsArray = nullptr;
320 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
321 IntptrPtrTy = PointerType::getUnqual(IntptrTy);
322 Type *VoidTy = Type::getVoidTy(*C);
323 IRBuilder<> IRB(*C);
324 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
325 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
326 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
327 Int64Ty = IRB.getInt64Ty();
328 Int32Ty = IRB.getInt32Ty();
329 Int16Ty = IRB.getInt16Ty();
330 Int8Ty = IRB.getInt8Ty();
331
332 SanCovTracePCIndir = checkSanitizerInterfaceFunction(
333 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy));
334 SanCovTraceCmpFunction[0] =
335 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
336 SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty()));
337 SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
338 M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
339 IRB.getInt16Ty()));
340 SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
341 M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
342 IRB.getInt32Ty()));
343 SanCovTraceCmpFunction[3] =
344 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
345 SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty));
346
347 SanCovTraceConstCmpFunction[0] =
348 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
349 SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty));
350 SanCovTraceConstCmpFunction[1] =
351 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
352 SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty));
353 SanCovTraceConstCmpFunction[2] =
354 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
355 SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty));
356 SanCovTraceConstCmpFunction[3] =
357 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
358 SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty));
359
360 SanCovTraceDivFunction[0] =
361 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
362 SanCovTraceDiv4, VoidTy, IRB.getInt32Ty()));
363 SanCovTraceDivFunction[1] =
364 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
365 SanCovTraceDiv8, VoidTy, Int64Ty));
366 SanCovTraceGepFunction =
367 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
368 SanCovTraceGep, VoidTy, IntptrTy));
369 SanCovTraceSwitchFunction =
370 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
371 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy));
372
373 Constant *SanCovLowestStackConstant =
374 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
375 SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant);
376 SanCovLowestStack->setThreadLocalMode(
377 GlobalValue::ThreadLocalMode::InitialExecTLSModel);
378 if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
379 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
380
381 // Make sure smaller parameters are zero-extended to i64 as required by the
382 // x86_64 ABI.
383 if (TargetTriple.getArch() == Triple::x86_64) {
384 for (int i = 0; i < 3; i++) {
385 SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
386 SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
387 SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
388 SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
389 }
390 SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt);
391 }
392
393
394 // We insert an empty inline asm after cov callbacks to avoid callback merge.
395 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
396 StringRef(""), StringRef(""),
397 /*hasSideEffects=*/true);
398
399 SanCovTracePC = checkSanitizerInterfaceFunction(
400 M.getOrInsertFunction(SanCovTracePCName, VoidTy));
401 SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
402 SanCovTracePCGuardName, VoidTy, Int32PtrTy));
403
404 for (auto &F : M)
405 runOnFunction(F);
406
407 Function *Ctor = nullptr;
408
409 if (FunctionGuardArray)
410 Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy,
411 SanCovGuardsSectionName);
412 if (Function8bitCounterArray)
413 Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy,
414 SanCovCountersSectionName);
415 if (Ctor && Options.PCTable) {
416 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
417 Function *InitFunction = declareSanitizerInitFunction(
418 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
419 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
420 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
421 }
422 // We don't reference these arrays directly in any of our runtime functions,
423 // so we need to prevent them from being dead stripped.
424 if (TargetTriple.isOSBinFormatMachO())
425 appendToUsed(M, GlobalsToAppendToUsed);
426 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
427 return true;
428 }
429
430 // True if block has successors and it dominates all of them.
isFullDominator(const BasicBlock * BB,const DominatorTree * DT)431 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
432 if (succ_begin(BB) == succ_end(BB))
433 return false;
434
435 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
436 if (!DT->dominates(BB, SUCC))
437 return false;
438 }
439
440 return true;
441 }
442
443 // True if block has predecessors and it postdominates all of them.
isFullPostDominator(const BasicBlock * BB,const PostDominatorTree * PDT)444 static bool isFullPostDominator(const BasicBlock *BB,
445 const PostDominatorTree *PDT) {
446 if (pred_begin(BB) == pred_end(BB))
447 return false;
448
449 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
450 if (!PDT->dominates(BB, PRED))
451 return false;
452 }
453
454 return true;
455 }
456
shouldInstrumentBlock(const Function & F,const BasicBlock * BB,const DominatorTree * DT,const PostDominatorTree * PDT,const SanitizerCoverageOptions & Options)457 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
458 const DominatorTree *DT,
459 const PostDominatorTree *PDT,
460 const SanitizerCoverageOptions &Options) {
461 // Don't insert coverage for unreachable blocks: we will never call
462 // __sanitizer_cov() for them, so counting them in
463 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
464 // percentage. Also, unreachable instructions frequently have no debug
465 // locations.
466 if (isa<UnreachableInst>(BB->getTerminator()))
467 return false;
468
469 // Don't insert coverage into blocks without a valid insertion point
470 // (catchswitch blocks).
471 if (BB->getFirstInsertionPt() == BB->end())
472 return false;
473
474 if (Options.NoPrune || &F.getEntryBlock() == BB)
475 return true;
476
477 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
478 &F.getEntryBlock() != BB)
479 return false;
480
481 // Do not instrument full dominators, or full post-dominators with multiple
482 // predecessors.
483 return !isFullDominator(BB, DT)
484 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
485 }
486
runOnFunction(Function & F)487 bool SanitizerCoverageModule::runOnFunction(Function &F) {
488 if (F.empty())
489 return false;
490 if (F.getName().find(".module_ctor") != std::string::npos)
491 return false; // Should not instrument sanitizer init functions.
492 if (F.getName().startswith("__sanitizer_"))
493 return false; // Don't instrument __sanitizer_* callbacks.
494 // Don't touch available_externally functions, their actual body is elewhere.
495 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
496 return false;
497 // Don't instrument MSVC CRT configuration helpers. They may run before normal
498 // initialization.
499 if (F.getName() == "__local_stdio_printf_options" ||
500 F.getName() == "__local_stdio_scanf_options")
501 return false;
502 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
503 return false;
504 // Don't instrument functions using SEH for now. Splitting basic blocks like
505 // we do for coverage breaks WinEHPrepare.
506 // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
507 if (F.hasPersonalityFn() &&
508 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
509 return false;
510 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
511 SplitAllCriticalEdges(F);
512 SmallVector<Instruction *, 8> IndirCalls;
513 SmallVector<BasicBlock *, 16> BlocksToInstrument;
514 SmallVector<Instruction *, 8> CmpTraceTargets;
515 SmallVector<Instruction *, 8> SwitchTraceTargets;
516 SmallVector<BinaryOperator *, 8> DivTraceTargets;
517 SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
518
519 const DominatorTree *DT =
520 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
521 const PostDominatorTree *PDT =
522 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
523 bool IsLeafFunc = true;
524
525 for (auto &BB : F) {
526 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
527 BlocksToInstrument.push_back(&BB);
528 for (auto &Inst : BB) {
529 if (Options.IndirectCalls) {
530 CallSite CS(&Inst);
531 if (CS && !CS.getCalledFunction())
532 IndirCalls.push_back(&Inst);
533 }
534 if (Options.TraceCmp) {
535 if (isa<ICmpInst>(&Inst))
536 CmpTraceTargets.push_back(&Inst);
537 if (isa<SwitchInst>(&Inst))
538 SwitchTraceTargets.push_back(&Inst);
539 }
540 if (Options.TraceDiv)
541 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
542 if (BO->getOpcode() == Instruction::SDiv ||
543 BO->getOpcode() == Instruction::UDiv)
544 DivTraceTargets.push_back(BO);
545 if (Options.TraceGep)
546 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
547 GepTraceTargets.push_back(GEP);
548 if (Options.StackDepth)
549 if (isa<InvokeInst>(Inst) ||
550 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
551 IsLeafFunc = false;
552 }
553 }
554
555 InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
556 InjectCoverageForIndirectCalls(F, IndirCalls);
557 InjectTraceForCmp(F, CmpTraceTargets);
558 InjectTraceForSwitch(F, SwitchTraceTargets);
559 InjectTraceForDiv(F, DivTraceTargets);
560 InjectTraceForGep(F, GepTraceTargets);
561 return true;
562 }
563
CreateFunctionLocalArrayInSection(size_t NumElements,Function & F,Type * Ty,const char * Section)564 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection(
565 size_t NumElements, Function &F, Type *Ty, const char *Section) {
566 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
567 auto Array = new GlobalVariable(
568 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
569 Constant::getNullValue(ArrayTy), "__sancov_gen_");
570
571 if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
572 if (auto Comdat =
573 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
574 Array->setComdat(Comdat);
575 Array->setSection(getSectionName(Section));
576 Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize()
577 : Ty->getPrimitiveSizeInBits() / 8);
578 GlobalsToAppendToUsed.push_back(Array);
579 GlobalsToAppendToCompilerUsed.push_back(Array);
580 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
581 Array->addMetadata(LLVMContext::MD_associated, *MD);
582
583 return Array;
584 }
585
586 GlobalVariable *
CreatePCArray(Function & F,ArrayRef<BasicBlock * > AllBlocks)587 SanitizerCoverageModule::CreatePCArray(Function &F,
588 ArrayRef<BasicBlock *> AllBlocks) {
589 size_t N = AllBlocks.size();
590 assert(N);
591 SmallVector<Constant *, 32> PCs;
592 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
593 for (size_t i = 0; i < N; i++) {
594 if (&F.getEntryBlock() == AllBlocks[i]) {
595 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
596 PCs.push_back((Constant *)IRB.CreateIntToPtr(
597 ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
598 } else {
599 PCs.push_back((Constant *)IRB.CreatePointerCast(
600 BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
601 PCs.push_back((Constant *)IRB.CreateIntToPtr(
602 ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
603 }
604 }
605 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
606 SanCovPCsSectionName);
607 PCArray->setInitializer(
608 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
609 PCArray->setConstant(true);
610
611 return PCArray;
612 }
613
CreateFunctionLocalArrays(Function & F,ArrayRef<BasicBlock * > AllBlocks)614 void SanitizerCoverageModule::CreateFunctionLocalArrays(
615 Function &F, ArrayRef<BasicBlock *> AllBlocks) {
616 if (Options.TracePCGuard)
617 FunctionGuardArray = CreateFunctionLocalArrayInSection(
618 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
619
620 if (Options.Inline8bitCounters)
621 Function8bitCounterArray = CreateFunctionLocalArrayInSection(
622 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
623
624 if (Options.PCTable)
625 FunctionPCsArray = CreatePCArray(F, AllBlocks);
626 }
627
InjectCoverage(Function & F,ArrayRef<BasicBlock * > AllBlocks,bool IsLeafFunc)628 bool SanitizerCoverageModule::InjectCoverage(Function &F,
629 ArrayRef<BasicBlock *> AllBlocks,
630 bool IsLeafFunc) {
631 if (AllBlocks.empty()) return false;
632 CreateFunctionLocalArrays(F, AllBlocks);
633 for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
634 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
635 return true;
636 }
637
638 // On every indirect call we call a run-time function
639 // __sanitizer_cov_indir_call* with two parameters:
640 // - callee address,
641 // - global cache array that contains CacheSize pointers (zero-initialized).
642 // The cache is used to speed up recording the caller-callee pairs.
643 // The address of the caller is passed implicitly via caller PC.
644 // CacheSize is encoded in the name of the run-time function.
InjectCoverageForIndirectCalls(Function & F,ArrayRef<Instruction * > IndirCalls)645 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
646 Function &F, ArrayRef<Instruction *> IndirCalls) {
647 if (IndirCalls.empty())
648 return;
649 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
650 for (auto I : IndirCalls) {
651 IRBuilder<> IRB(I);
652 CallSite CS(I);
653 Value *Callee = CS.getCalledValue();
654 if (isa<InlineAsm>(Callee))
655 continue;
656 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
657 }
658 }
659
660 // For every switch statement we insert a call:
661 // __sanitizer_cov_trace_switch(CondValue,
662 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
663
InjectTraceForSwitch(Function &,ArrayRef<Instruction * > SwitchTraceTargets)664 void SanitizerCoverageModule::InjectTraceForSwitch(
665 Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
666 for (auto I : SwitchTraceTargets) {
667 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
668 IRBuilder<> IRB(I);
669 SmallVector<Constant *, 16> Initializers;
670 Value *Cond = SI->getCondition();
671 if (Cond->getType()->getScalarSizeInBits() >
672 Int64Ty->getScalarSizeInBits())
673 continue;
674 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
675 Initializers.push_back(
676 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
677 if (Cond->getType()->getScalarSizeInBits() <
678 Int64Ty->getScalarSizeInBits())
679 Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
680 for (auto It : SI->cases()) {
681 Constant *C = It.getCaseValue();
682 if (C->getType()->getScalarSizeInBits() <
683 Int64Ty->getScalarSizeInBits())
684 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
685 Initializers.push_back(C);
686 }
687 llvm::sort(Initializers.begin() + 2, Initializers.end(),
688 [](const Constant *A, const Constant *B) {
689 return cast<ConstantInt>(A)->getLimitedValue() <
690 cast<ConstantInt>(B)->getLimitedValue();
691 });
692 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
693 GlobalVariable *GV = new GlobalVariable(
694 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
695 ConstantArray::get(ArrayOfInt64Ty, Initializers),
696 "__sancov_gen_cov_switch_values");
697 IRB.CreateCall(SanCovTraceSwitchFunction,
698 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
699 }
700 }
701 }
702
InjectTraceForDiv(Function &,ArrayRef<BinaryOperator * > DivTraceTargets)703 void SanitizerCoverageModule::InjectTraceForDiv(
704 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
705 for (auto BO : DivTraceTargets) {
706 IRBuilder<> IRB(BO);
707 Value *A1 = BO->getOperand(1);
708 if (isa<ConstantInt>(A1)) continue;
709 if (!A1->getType()->isIntegerTy())
710 continue;
711 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
712 int CallbackIdx = TypeSize == 32 ? 0 :
713 TypeSize == 64 ? 1 : -1;
714 if (CallbackIdx < 0) continue;
715 auto Ty = Type::getIntNTy(*C, TypeSize);
716 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
717 {IRB.CreateIntCast(A1, Ty, true)});
718 }
719 }
720
InjectTraceForGep(Function &,ArrayRef<GetElementPtrInst * > GepTraceTargets)721 void SanitizerCoverageModule::InjectTraceForGep(
722 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
723 for (auto GEP : GepTraceTargets) {
724 IRBuilder<> IRB(GEP);
725 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
726 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
727 IRB.CreateCall(SanCovTraceGepFunction,
728 {IRB.CreateIntCast(*I, IntptrTy, true)});
729 }
730 }
731
InjectTraceForCmp(Function &,ArrayRef<Instruction * > CmpTraceTargets)732 void SanitizerCoverageModule::InjectTraceForCmp(
733 Function &, ArrayRef<Instruction *> CmpTraceTargets) {
734 for (auto I : CmpTraceTargets) {
735 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
736 IRBuilder<> IRB(ICMP);
737 Value *A0 = ICMP->getOperand(0);
738 Value *A1 = ICMP->getOperand(1);
739 if (!A0->getType()->isIntegerTy())
740 continue;
741 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
742 int CallbackIdx = TypeSize == 8 ? 0 :
743 TypeSize == 16 ? 1 :
744 TypeSize == 32 ? 2 :
745 TypeSize == 64 ? 3 : -1;
746 if (CallbackIdx < 0) continue;
747 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
748 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
749 bool FirstIsConst = isa<ConstantInt>(A0);
750 bool SecondIsConst = isa<ConstantInt>(A1);
751 // If both are const, then we don't need such a comparison.
752 if (FirstIsConst && SecondIsConst) continue;
753 // If only one is const, then make it the first callback argument.
754 if (FirstIsConst || SecondIsConst) {
755 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
756 if (SecondIsConst)
757 std::swap(A0, A1);
758 }
759
760 auto Ty = Type::getIntNTy(*C, TypeSize);
761 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
762 IRB.CreateIntCast(A1, Ty, true)});
763 }
764 }
765 }
766
InjectCoverageAtBlock(Function & F,BasicBlock & BB,size_t Idx,bool IsLeafFunc)767 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
768 size_t Idx,
769 bool IsLeafFunc) {
770 BasicBlock::iterator IP = BB.getFirstInsertionPt();
771 bool IsEntryBB = &BB == &F.getEntryBlock();
772 DebugLoc EntryLoc;
773 if (IsEntryBB) {
774 if (auto SP = F.getSubprogram())
775 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
776 // Keep static allocas and llvm.localescape calls in the entry block. Even
777 // if we aren't splitting the block, it's nice for allocas to be before
778 // calls.
779 IP = PrepareToSplitEntryBlock(BB, IP);
780 } else {
781 EntryLoc = IP->getDebugLoc();
782 }
783
784 IRBuilder<> IRB(&*IP);
785 IRB.SetCurrentDebugLocation(EntryLoc);
786 if (Options.TracePC) {
787 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
788 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
789 }
790 if (Options.TracePCGuard) {
791 auto GuardPtr = IRB.CreateIntToPtr(
792 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
793 ConstantInt::get(IntptrTy, Idx * 4)),
794 Int32PtrTy);
795 IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
796 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
797 }
798 if (Options.Inline8bitCounters) {
799 auto CounterPtr = IRB.CreateGEP(
800 Function8bitCounterArray,
801 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
802 auto Load = IRB.CreateLoad(CounterPtr);
803 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
804 auto Store = IRB.CreateStore(Inc, CounterPtr);
805 SetNoSanitizeMetadata(Load);
806 SetNoSanitizeMetadata(Store);
807 }
808 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
809 // Check stack depth. If it's the deepest so far, record it.
810 Function *GetFrameAddr =
811 Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress);
812 auto FrameAddrPtr =
813 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
814 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
815 auto LowestStack = IRB.CreateLoad(SanCovLowestStack);
816 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
817 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
818 IRBuilder<> ThenIRB(ThenTerm);
819 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
820 SetNoSanitizeMetadata(LowestStack);
821 SetNoSanitizeMetadata(Store);
822 }
823 }
824
825 std::string
getSectionName(const std::string & Section) const826 SanitizerCoverageModule::getSectionName(const std::string &Section) const {
827 if (TargetTriple.isOSBinFormatCOFF()) {
828 if (Section == SanCovCountersSectionName)
829 return ".SCOV$CM";
830 if (Section == SanCovPCsSectionName)
831 return ".SCOVP$M";
832 return ".SCOV$GM"; // For SanCovGuardsSectionName.
833 }
834 if (TargetTriple.isOSBinFormatMachO())
835 return "__DATA,__" + Section;
836 return "__" + Section;
837 }
838
839 std::string
getSectionStart(const std::string & Section) const840 SanitizerCoverageModule::getSectionStart(const std::string &Section) const {
841 if (TargetTriple.isOSBinFormatMachO())
842 return "\1section$start$__DATA$__" + Section;
843 return "__start___" + Section;
844 }
845
846 std::string
getSectionEnd(const std::string & Section) const847 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const {
848 if (TargetTriple.isOSBinFormatMachO())
849 return "\1section$end$__DATA$__" + Section;
850 return "__stop___" + Section;
851 }
852
853
854 char SanitizerCoverageModule::ID = 0;
855 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
856 "SanitizerCoverage: TODO."
857 "ModulePass",
858 false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)859 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
860 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
861 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
862 "SanitizerCoverage: TODO."
863 "ModulePass",
864 false, false)
865 ModulePass *llvm::createSanitizerCoverageModulePass(
866 const SanitizerCoverageOptions &Options) {
867 return new SanitizerCoverageModule(Options);
868 }
869