1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Coverage instrumentation done on LLVM IR level, works with Sanitizers.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
14 #include "llvm/ADT/ArrayRef.h"
15 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/Analysis/GlobalsModRef.h"
17 #include "llvm/Analysis/PostDominators.h"
18 #include "llvm/IR/Constant.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/Dominators.h"
21 #include "llvm/IR/EHPersonalities.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/IR/GlobalVariable.h"
24 #include "llvm/IR/IRBuilder.h"
25 #include "llvm/IR/IntrinsicInst.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/LLVMContext.h"
28 #include "llvm/IR/MDBuilder.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/IR/Type.h"
31 #include "llvm/Support/CommandLine.h"
32 #include "llvm/Support/SpecialCaseList.h"
33 #include "llvm/Support/VirtualFileSystem.h"
34 #include "llvm/TargetParser/Triple.h"
35 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
36 #include "llvm/Transforms/Utils/ModuleUtils.h"
37
38 using namespace llvm;
39
40 #define DEBUG_TYPE "sancov"
41
42 const char SanCovTracePCIndirName[] = "__sanitizer_cov_trace_pc_indir";
43 const char SanCovTracePCName[] = "__sanitizer_cov_trace_pc";
44 const char SanCovTraceCmp1[] = "__sanitizer_cov_trace_cmp1";
45 const char SanCovTraceCmp2[] = "__sanitizer_cov_trace_cmp2";
46 const char SanCovTraceCmp4[] = "__sanitizer_cov_trace_cmp4";
47 const char SanCovTraceCmp8[] = "__sanitizer_cov_trace_cmp8";
48 const char SanCovTraceConstCmp1[] = "__sanitizer_cov_trace_const_cmp1";
49 const char SanCovTraceConstCmp2[] = "__sanitizer_cov_trace_const_cmp2";
50 const char SanCovTraceConstCmp4[] = "__sanitizer_cov_trace_const_cmp4";
51 const char SanCovTraceConstCmp8[] = "__sanitizer_cov_trace_const_cmp8";
52 const char SanCovLoad1[] = "__sanitizer_cov_load1";
53 const char SanCovLoad2[] = "__sanitizer_cov_load2";
54 const char SanCovLoad4[] = "__sanitizer_cov_load4";
55 const char SanCovLoad8[] = "__sanitizer_cov_load8";
56 const char SanCovLoad16[] = "__sanitizer_cov_load16";
57 const char SanCovStore1[] = "__sanitizer_cov_store1";
58 const char SanCovStore2[] = "__sanitizer_cov_store2";
59 const char SanCovStore4[] = "__sanitizer_cov_store4";
60 const char SanCovStore8[] = "__sanitizer_cov_store8";
61 const char SanCovStore16[] = "__sanitizer_cov_store16";
62 const char SanCovTraceDiv4[] = "__sanitizer_cov_trace_div4";
63 const char SanCovTraceDiv8[] = "__sanitizer_cov_trace_div8";
64 const char SanCovTraceGep[] = "__sanitizer_cov_trace_gep";
65 const char SanCovTraceSwitchName[] = "__sanitizer_cov_trace_switch";
66 const char SanCovModuleCtorTracePcGuardName[] =
67 "sancov.module_ctor_trace_pc_guard";
68 const char SanCovModuleCtor8bitCountersName[] =
69 "sancov.module_ctor_8bit_counters";
70 const char SanCovModuleCtorBoolFlagName[] = "sancov.module_ctor_bool_flag";
71 static const uint64_t SanCtorAndDtorPriority = 2;
72
73 const char SanCovTracePCGuardName[] = "__sanitizer_cov_trace_pc_guard";
74 const char SanCovTracePCGuardInitName[] = "__sanitizer_cov_trace_pc_guard_init";
75 const char SanCov8bitCountersInitName[] = "__sanitizer_cov_8bit_counters_init";
76 const char SanCovBoolFlagInitName[] = "__sanitizer_cov_bool_flag_init";
77 const char SanCovPCsInitName[] = "__sanitizer_cov_pcs_init";
78 const char SanCovCFsInitName[] = "__sanitizer_cov_cfs_init";
79
80 const char SanCovGuardsSectionName[] = "sancov_guards";
81 const char SanCovCountersSectionName[] = "sancov_cntrs";
82 const char SanCovBoolFlagSectionName[] = "sancov_bools";
83 const char SanCovPCsSectionName[] = "sancov_pcs";
84 const char SanCovCFsSectionName[] = "sancov_cfs";
85
86 const char SanCovLowestStackName[] = "__sancov_lowest_stack";
87
88 static cl::opt<int> ClCoverageLevel(
89 "sanitizer-coverage-level",
90 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
91 "3: all blocks and critical edges"),
92 cl::Hidden);
93
94 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
95 cl::desc("Experimental pc tracing"), cl::Hidden);
96
97 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
98 cl::desc("pc tracing with a guard"),
99 cl::Hidden);
100
101 // If true, we create a global variable that contains PCs of all instrumented
102 // BBs, put this global into a named section, and pass this section's bounds
103 // to __sanitizer_cov_pcs_init.
104 // This way the coverage instrumentation does not need to acquire the PCs
105 // at run-time. Works with trace-pc-guard, inline-8bit-counters, and
106 // inline-bool-flag.
107 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
108 cl::desc("create a static PC table"),
109 cl::Hidden);
110
111 static cl::opt<bool>
112 ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
113 cl::desc("increments 8-bit counter for every edge"),
114 cl::Hidden);
115
116 static cl::opt<bool>
117 ClInlineBoolFlag("sanitizer-coverage-inline-bool-flag",
118 cl::desc("sets a boolean flag for every edge"),
119 cl::Hidden);
120
121 static cl::opt<bool>
122 ClCMPTracing("sanitizer-coverage-trace-compares",
123 cl::desc("Tracing of CMP and similar instructions"),
124 cl::Hidden);
125
126 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
127 cl::desc("Tracing of DIV instructions"),
128 cl::Hidden);
129
130 static cl::opt<bool> ClLoadTracing("sanitizer-coverage-trace-loads",
131 cl::desc("Tracing of load instructions"),
132 cl::Hidden);
133
134 static cl::opt<bool> ClStoreTracing("sanitizer-coverage-trace-stores",
135 cl::desc("Tracing of store instructions"),
136 cl::Hidden);
137
138 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
139 cl::desc("Tracing of GEP instructions"),
140 cl::Hidden);
141
142 static cl::opt<bool>
143 ClPruneBlocks("sanitizer-coverage-prune-blocks",
144 cl::desc("Reduce the number of instrumented blocks"),
145 cl::Hidden, cl::init(true));
146
147 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
148 cl::desc("max stack depth tracing"),
149 cl::Hidden);
150
151 static cl::opt<bool>
152 ClCollectCF("sanitizer-coverage-control-flow",
153 cl::desc("collect control flow for each function"), cl::Hidden);
154
155 namespace {
156
getOptions(int LegacyCoverageLevel)157 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
158 SanitizerCoverageOptions Res;
159 switch (LegacyCoverageLevel) {
160 case 0:
161 Res.CoverageType = SanitizerCoverageOptions::SCK_None;
162 break;
163 case 1:
164 Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
165 break;
166 case 2:
167 Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
168 break;
169 case 3:
170 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
171 break;
172 case 4:
173 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
174 Res.IndirectCalls = true;
175 break;
176 }
177 return Res;
178 }
179
OverrideFromCL(SanitizerCoverageOptions Options)180 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
181 // Sets CoverageType and IndirectCalls.
182 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
183 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
184 Options.IndirectCalls |= CLOpts.IndirectCalls;
185 Options.TraceCmp |= ClCMPTracing;
186 Options.TraceDiv |= ClDIVTracing;
187 Options.TraceGep |= ClGEPTracing;
188 Options.TracePC |= ClTracePC;
189 Options.TracePCGuard |= ClTracePCGuard;
190 Options.Inline8bitCounters |= ClInline8bitCounters;
191 Options.InlineBoolFlag |= ClInlineBoolFlag;
192 Options.PCTable |= ClCreatePCTable;
193 Options.NoPrune |= !ClPruneBlocks;
194 Options.StackDepth |= ClStackDepth;
195 Options.TraceLoads |= ClLoadTracing;
196 Options.TraceStores |= ClStoreTracing;
197 if (!Options.TracePCGuard && !Options.TracePC &&
198 !Options.Inline8bitCounters && !Options.StackDepth &&
199 !Options.InlineBoolFlag && !Options.TraceLoads && !Options.TraceStores)
200 Options.TracePCGuard = true; // TracePCGuard is default.
201 Options.CollectControlFlow |= ClCollectCF;
202 return Options;
203 }
204
205 class ModuleSanitizerCoverage {
206 public:
207 using DomTreeCallback = function_ref<const DominatorTree &(Function &F)>;
208 using PostDomTreeCallback =
209 function_ref<const PostDominatorTree &(Function &F)>;
210
ModuleSanitizerCoverage(Module & M,DomTreeCallback DTCallback,PostDomTreeCallback PDTCallback,const SanitizerCoverageOptions & Options,const SpecialCaseList * Allowlist,const SpecialCaseList * Blocklist)211 ModuleSanitizerCoverage(Module &M, DomTreeCallback DTCallback,
212 PostDomTreeCallback PDTCallback,
213 const SanitizerCoverageOptions &Options,
214 const SpecialCaseList *Allowlist,
215 const SpecialCaseList *Blocklist)
216 : M(M), DTCallback(DTCallback), PDTCallback(PDTCallback),
217 Options(Options), Allowlist(Allowlist), Blocklist(Blocklist) {}
218
219 bool instrumentModule();
220
221 private:
222 void createFunctionControlFlow(Function &F);
223 void instrumentFunction(Function &F);
224 void InjectCoverageForIndirectCalls(Function &F,
225 ArrayRef<Instruction *> IndirCalls);
226 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
227 void InjectTraceForDiv(Function &F,
228 ArrayRef<BinaryOperator *> DivTraceTargets);
229 void InjectTraceForGep(Function &F,
230 ArrayRef<GetElementPtrInst *> GepTraceTargets);
231 void InjectTraceForLoadsAndStores(Function &F, ArrayRef<LoadInst *> Loads,
232 ArrayRef<StoreInst *> Stores);
233 void InjectTraceForSwitch(Function &F,
234 ArrayRef<Instruction *> SwitchTraceTargets);
235 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
236 bool IsLeafFunc = true);
237 GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
238 Function &F, Type *Ty,
239 const char *Section);
240 GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
241 void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
242 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
243 bool IsLeafFunc = true);
244 Function *CreateInitCallsForSections(Module &M, const char *CtorName,
245 const char *InitFunctionName, Type *Ty,
246 const char *Section);
247 std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
248 Type *Ty);
249
250 std::string getSectionName(const std::string &Section) const;
251 std::string getSectionStart(const std::string &Section) const;
252 std::string getSectionEnd(const std::string &Section) const;
253
254 Module &M;
255 DomTreeCallback DTCallback;
256 PostDomTreeCallback PDTCallback;
257
258 FunctionCallee SanCovTracePCIndir;
259 FunctionCallee SanCovTracePC, SanCovTracePCGuard;
260 std::array<FunctionCallee, 4> SanCovTraceCmpFunction;
261 std::array<FunctionCallee, 4> SanCovTraceConstCmpFunction;
262 std::array<FunctionCallee, 5> SanCovLoadFunction;
263 std::array<FunctionCallee, 5> SanCovStoreFunction;
264 std::array<FunctionCallee, 2> SanCovTraceDivFunction;
265 FunctionCallee SanCovTraceGepFunction;
266 FunctionCallee SanCovTraceSwitchFunction;
267 GlobalVariable *SanCovLowestStack;
268 Type *PtrTy, *IntptrTy, *Int64Ty, *Int32Ty, *Int16Ty, *Int8Ty, *Int1Ty;
269 Module *CurModule;
270 std::string CurModuleUniqueId;
271 Triple TargetTriple;
272 LLVMContext *C;
273 const DataLayout *DL;
274
275 GlobalVariable *FunctionGuardArray; // for trace-pc-guard.
276 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters.
277 GlobalVariable *FunctionBoolArray; // for inline-bool-flag.
278 GlobalVariable *FunctionPCsArray; // for pc-table.
279 GlobalVariable *FunctionCFsArray; // for control flow table
280 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
281 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
282
283 SanitizerCoverageOptions Options;
284
285 const SpecialCaseList *Allowlist;
286 const SpecialCaseList *Blocklist;
287 };
288 } // namespace
289
run(Module & M,ModuleAnalysisManager & MAM)290 PreservedAnalyses SanitizerCoveragePass::run(Module &M,
291 ModuleAnalysisManager &MAM) {
292 auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
293 auto DTCallback = [&FAM](Function &F) -> const DominatorTree & {
294 return FAM.getResult<DominatorTreeAnalysis>(F);
295 };
296 auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree & {
297 return FAM.getResult<PostDominatorTreeAnalysis>(F);
298 };
299 ModuleSanitizerCoverage ModuleSancov(M, DTCallback, PDTCallback,
300 OverrideFromCL(Options), Allowlist.get(),
301 Blocklist.get());
302 if (!ModuleSancov.instrumentModule())
303 return PreservedAnalyses::all();
304
305 PreservedAnalyses PA = PreservedAnalyses::none();
306 // GlobalsAA is considered stateless and does not get invalidated unless
307 // explicitly invalidated; PreservedAnalyses::none() is not enough. Sanitizers
308 // make changes that require GlobalsAA to be invalidated.
309 PA.abandon<GlobalsAA>();
310 return PA;
311 }
312
313 std::pair<Value *, Value *>
CreateSecStartEnd(Module & M,const char * Section,Type * Ty)314 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
315 Type *Ty) {
316 // Use ExternalWeak so that if all sections are discarded due to section
317 // garbage collection, the linker will not report undefined symbol errors.
318 // Windows defines the start/stop symbols in compiler-rt so no need for
319 // ExternalWeak.
320 GlobalValue::LinkageTypes Linkage = TargetTriple.isOSBinFormatCOFF()
321 ? GlobalVariable::ExternalLinkage
322 : GlobalVariable::ExternalWeakLinkage;
323 GlobalVariable *SecStart =
324 new GlobalVariable(M, Ty, false, Linkage, nullptr,
325 getSectionStart(Section));
326 SecStart->setVisibility(GlobalValue::HiddenVisibility);
327 GlobalVariable *SecEnd =
328 new GlobalVariable(M, Ty, false, Linkage, nullptr,
329 getSectionEnd(Section));
330 SecEnd->setVisibility(GlobalValue::HiddenVisibility);
331 IRBuilder<> IRB(M.getContext());
332 if (!TargetTriple.isOSBinFormatCOFF())
333 return std::make_pair(SecStart, SecEnd);
334
335 // Account for the fact that on windows-msvc __start_* symbols actually
336 // point to a uint64_t before the start of the array.
337 auto GEP =
338 IRB.CreatePtrAdd(SecStart, ConstantInt::get(IntptrTy, sizeof(uint64_t)));
339 return std::make_pair(GEP, SecEnd);
340 }
341
CreateInitCallsForSections(Module & M,const char * CtorName,const char * InitFunctionName,Type * Ty,const char * Section)342 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
343 Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
344 const char *Section) {
345 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
346 auto SecStart = SecStartEnd.first;
347 auto SecEnd = SecStartEnd.second;
348 Function *CtorFunc;
349 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
350 M, CtorName, InitFunctionName, {PtrTy, PtrTy}, {SecStart, SecEnd});
351 assert(CtorFunc->getName() == CtorName);
352
353 if (TargetTriple.supportsCOMDAT()) {
354 // Use comdat to dedup CtorFunc.
355 CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
356 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
357 } else {
358 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
359 }
360
361 if (TargetTriple.isOSBinFormatCOFF()) {
362 // In COFF files, if the contructors are set as COMDAT (they are because
363 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
364 // functions and data) is used, the constructors get stripped. To prevent
365 // this, give the constructors weak ODR linkage and ensure the linker knows
366 // to include the sancov constructor. This way the linker can deduplicate
367 // the constructors but always leave one copy.
368 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
369 }
370 return CtorFunc;
371 }
372
instrumentModule()373 bool ModuleSanitizerCoverage::instrumentModule() {
374 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
375 return false;
376 if (Allowlist &&
377 !Allowlist->inSection("coverage", "src", M.getSourceFileName()))
378 return false;
379 if (Blocklist &&
380 Blocklist->inSection("coverage", "src", M.getSourceFileName()))
381 return false;
382 C = &(M.getContext());
383 DL = &M.getDataLayout();
384 CurModule = &M;
385 CurModuleUniqueId = getUniqueModuleId(CurModule);
386 TargetTriple = Triple(M.getTargetTriple());
387 FunctionGuardArray = nullptr;
388 Function8bitCounterArray = nullptr;
389 FunctionBoolArray = nullptr;
390 FunctionPCsArray = nullptr;
391 FunctionCFsArray = nullptr;
392 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
393 PtrTy = PointerType::getUnqual(*C);
394 Type *VoidTy = Type::getVoidTy(*C);
395 IRBuilder<> IRB(*C);
396 Int64Ty = IRB.getInt64Ty();
397 Int32Ty = IRB.getInt32Ty();
398 Int16Ty = IRB.getInt16Ty();
399 Int8Ty = IRB.getInt8Ty();
400 Int1Ty = IRB.getInt1Ty();
401
402 SanCovTracePCIndir =
403 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
404 // Make sure smaller parameters are zero-extended to i64 if required by the
405 // target ABI.
406 AttributeList SanCovTraceCmpZeroExtAL;
407 SanCovTraceCmpZeroExtAL =
408 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
409 SanCovTraceCmpZeroExtAL =
410 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
411
412 SanCovTraceCmpFunction[0] =
413 M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
414 IRB.getInt8Ty(), IRB.getInt8Ty());
415 SanCovTraceCmpFunction[1] =
416 M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
417 IRB.getInt16Ty(), IRB.getInt16Ty());
418 SanCovTraceCmpFunction[2] =
419 M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
420 IRB.getInt32Ty(), IRB.getInt32Ty());
421 SanCovTraceCmpFunction[3] =
422 M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
423
424 SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
425 SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
426 SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
427 SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
428 SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
429 SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
430 SanCovTraceConstCmpFunction[3] =
431 M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
432
433 // Loads.
434 SanCovLoadFunction[0] = M.getOrInsertFunction(SanCovLoad1, VoidTy, PtrTy);
435 SanCovLoadFunction[1] =
436 M.getOrInsertFunction(SanCovLoad2, VoidTy, PtrTy);
437 SanCovLoadFunction[2] =
438 M.getOrInsertFunction(SanCovLoad4, VoidTy, PtrTy);
439 SanCovLoadFunction[3] =
440 M.getOrInsertFunction(SanCovLoad8, VoidTy, PtrTy);
441 SanCovLoadFunction[4] =
442 M.getOrInsertFunction(SanCovLoad16, VoidTy, PtrTy);
443 // Stores.
444 SanCovStoreFunction[0] =
445 M.getOrInsertFunction(SanCovStore1, VoidTy, PtrTy);
446 SanCovStoreFunction[1] =
447 M.getOrInsertFunction(SanCovStore2, VoidTy, PtrTy);
448 SanCovStoreFunction[2] =
449 M.getOrInsertFunction(SanCovStore4, VoidTy, PtrTy);
450 SanCovStoreFunction[3] =
451 M.getOrInsertFunction(SanCovStore8, VoidTy, PtrTy);
452 SanCovStoreFunction[4] =
453 M.getOrInsertFunction(SanCovStore16, VoidTy, PtrTy);
454
455 {
456 AttributeList AL;
457 AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
458 SanCovTraceDivFunction[0] =
459 M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
460 }
461 SanCovTraceDivFunction[1] =
462 M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
463 SanCovTraceGepFunction =
464 M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
465 SanCovTraceSwitchFunction =
466 M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, PtrTy);
467
468 Constant *SanCovLowestStackConstant =
469 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
470 SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
471 if (!SanCovLowestStack || SanCovLowestStack->getValueType() != IntptrTy) {
472 C->emitError(StringRef("'") + SanCovLowestStackName +
473 "' should not be declared by the user");
474 return true;
475 }
476 SanCovLowestStack->setThreadLocalMode(
477 GlobalValue::ThreadLocalMode::InitialExecTLSModel);
478 if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
479 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
480
481 SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
482 SanCovTracePCGuard =
483 M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, PtrTy);
484
485 for (auto &F : M)
486 instrumentFunction(F);
487
488 Function *Ctor = nullptr;
489
490 if (FunctionGuardArray)
491 Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
492 SanCovTracePCGuardInitName, Int32Ty,
493 SanCovGuardsSectionName);
494 if (Function8bitCounterArray)
495 Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
496 SanCov8bitCountersInitName, Int8Ty,
497 SanCovCountersSectionName);
498 if (FunctionBoolArray) {
499 Ctor = CreateInitCallsForSections(M, SanCovModuleCtorBoolFlagName,
500 SanCovBoolFlagInitName, Int1Ty,
501 SanCovBoolFlagSectionName);
502 }
503 if (Ctor && Options.PCTable) {
504 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrTy);
505 FunctionCallee InitFunction = declareSanitizerInitFunction(
506 M, SanCovPCsInitName, {PtrTy, PtrTy});
507 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
508 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
509 }
510
511 if (Ctor && Options.CollectControlFlow) {
512 auto SecStartEnd = CreateSecStartEnd(M, SanCovCFsSectionName, IntptrTy);
513 FunctionCallee InitFunction = declareSanitizerInitFunction(
514 M, SanCovCFsInitName, {PtrTy, PtrTy});
515 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
516 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
517 }
518
519 appendToUsed(M, GlobalsToAppendToUsed);
520 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
521 return true;
522 }
523
524 // True if block has successors and it dominates all of them.
isFullDominator(const BasicBlock * BB,const DominatorTree & DT)525 static bool isFullDominator(const BasicBlock *BB, const DominatorTree &DT) {
526 if (succ_empty(BB))
527 return false;
528
529 return llvm::all_of(successors(BB), [&](const BasicBlock *SUCC) {
530 return DT.dominates(BB, SUCC);
531 });
532 }
533
534 // True if block has predecessors and it postdominates all of them.
isFullPostDominator(const BasicBlock * BB,const PostDominatorTree & PDT)535 static bool isFullPostDominator(const BasicBlock *BB,
536 const PostDominatorTree &PDT) {
537 if (pred_empty(BB))
538 return false;
539
540 return llvm::all_of(predecessors(BB), [&](const BasicBlock *PRED) {
541 return PDT.dominates(BB, PRED);
542 });
543 }
544
shouldInstrumentBlock(const Function & F,const BasicBlock * BB,const DominatorTree & DT,const PostDominatorTree & PDT,const SanitizerCoverageOptions & Options)545 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
546 const DominatorTree &DT,
547 const PostDominatorTree &PDT,
548 const SanitizerCoverageOptions &Options) {
549 // Don't insert coverage for blocks containing nothing but unreachable: we
550 // will never call __sanitizer_cov() for them, so counting them in
551 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
552 // percentage. Also, unreachable instructions frequently have no debug
553 // locations.
554 if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
555 return false;
556
557 // Don't insert coverage into blocks without a valid insertion point
558 // (catchswitch blocks).
559 if (BB->getFirstInsertionPt() == BB->end())
560 return false;
561
562 if (Options.NoPrune || &F.getEntryBlock() == BB)
563 return true;
564
565 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
566 &F.getEntryBlock() != BB)
567 return false;
568
569 // Do not instrument full dominators, or full post-dominators with multiple
570 // predecessors.
571 return !isFullDominator(BB, DT)
572 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
573 }
574
575 // Returns true iff From->To is a backedge.
576 // A twist here is that we treat From->To as a backedge if
577 // * To dominates From or
578 // * To->UniqueSuccessor dominates From
IsBackEdge(BasicBlock * From,BasicBlock * To,const DominatorTree & DT)579 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
580 const DominatorTree &DT) {
581 if (DT.dominates(To, From))
582 return true;
583 if (auto Next = To->getUniqueSuccessor())
584 if (DT.dominates(Next, From))
585 return true;
586 return false;
587 }
588
589 // Prunes uninteresting Cmp instrumentation:
590 // * CMP instructions that feed into loop backedge branch.
591 //
592 // Note that Cmp pruning is controlled by the same flag as the
593 // BB pruning.
IsInterestingCmp(ICmpInst * CMP,const DominatorTree & DT,const SanitizerCoverageOptions & Options)594 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree &DT,
595 const SanitizerCoverageOptions &Options) {
596 if (!Options.NoPrune)
597 if (CMP->hasOneUse())
598 if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
599 for (BasicBlock *B : BR->successors())
600 if (IsBackEdge(BR->getParent(), B, DT))
601 return false;
602 return true;
603 }
604
instrumentFunction(Function & F)605 void ModuleSanitizerCoverage::instrumentFunction(Function &F) {
606 if (F.empty())
607 return;
608 if (F.getName().contains(".module_ctor"))
609 return; // Should not instrument sanitizer init functions.
610 if (F.getName().starts_with("__sanitizer_"))
611 return; // Don't instrument __sanitizer_* callbacks.
612 // Don't touch available_externally functions, their actual body is elewhere.
613 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
614 return;
615 // Don't instrument MSVC CRT configuration helpers. They may run before normal
616 // initialization.
617 if (F.getName() == "__local_stdio_printf_options" ||
618 F.getName() == "__local_stdio_scanf_options")
619 return;
620 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
621 return;
622 // Don't instrument functions using SEH for now. Splitting basic blocks like
623 // we do for coverage breaks WinEHPrepare.
624 // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
625 if (F.hasPersonalityFn() &&
626 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
627 return;
628 if (Allowlist && !Allowlist->inSection("coverage", "fun", F.getName()))
629 return;
630 if (Blocklist && Blocklist->inSection("coverage", "fun", F.getName()))
631 return;
632 if (F.hasFnAttribute(Attribute::NoSanitizeCoverage))
633 return;
634 if (F.hasFnAttribute(Attribute::DisableSanitizerInstrumentation))
635 return;
636 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) {
637 SplitAllCriticalEdges(
638 F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
639 }
640 SmallVector<Instruction *, 8> IndirCalls;
641 SmallVector<BasicBlock *, 16> BlocksToInstrument;
642 SmallVector<Instruction *, 8> CmpTraceTargets;
643 SmallVector<Instruction *, 8> SwitchTraceTargets;
644 SmallVector<BinaryOperator *, 8> DivTraceTargets;
645 SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
646 SmallVector<LoadInst *, 8> Loads;
647 SmallVector<StoreInst *, 8> Stores;
648
649 const DominatorTree &DT = DTCallback(F);
650 const PostDominatorTree &PDT = PDTCallback(F);
651 bool IsLeafFunc = true;
652
653 for (auto &BB : F) {
654 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
655 BlocksToInstrument.push_back(&BB);
656 for (auto &Inst : BB) {
657 if (Options.IndirectCalls) {
658 CallBase *CB = dyn_cast<CallBase>(&Inst);
659 if (CB && CB->isIndirectCall())
660 IndirCalls.push_back(&Inst);
661 }
662 if (Options.TraceCmp) {
663 if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
664 if (IsInterestingCmp(CMP, DT, Options))
665 CmpTraceTargets.push_back(&Inst);
666 if (isa<SwitchInst>(&Inst))
667 SwitchTraceTargets.push_back(&Inst);
668 }
669 if (Options.TraceDiv)
670 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
671 if (BO->getOpcode() == Instruction::SDiv ||
672 BO->getOpcode() == Instruction::UDiv)
673 DivTraceTargets.push_back(BO);
674 if (Options.TraceGep)
675 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
676 GepTraceTargets.push_back(GEP);
677 if (Options.TraceLoads)
678 if (LoadInst *LI = dyn_cast<LoadInst>(&Inst))
679 Loads.push_back(LI);
680 if (Options.TraceStores)
681 if (StoreInst *SI = dyn_cast<StoreInst>(&Inst))
682 Stores.push_back(SI);
683 if (Options.StackDepth)
684 if (isa<InvokeInst>(Inst) ||
685 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
686 IsLeafFunc = false;
687 }
688 }
689
690 if (Options.CollectControlFlow)
691 createFunctionControlFlow(F);
692
693 InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
694 InjectCoverageForIndirectCalls(F, IndirCalls);
695 InjectTraceForCmp(F, CmpTraceTargets);
696 InjectTraceForSwitch(F, SwitchTraceTargets);
697 InjectTraceForDiv(F, DivTraceTargets);
698 InjectTraceForGep(F, GepTraceTargets);
699 InjectTraceForLoadsAndStores(F, Loads, Stores);
700 }
701
CreateFunctionLocalArrayInSection(size_t NumElements,Function & F,Type * Ty,const char * Section)702 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
703 size_t NumElements, Function &F, Type *Ty, const char *Section) {
704 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
705 auto Array = new GlobalVariable(
706 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
707 Constant::getNullValue(ArrayTy), "__sancov_gen_");
708
709 if (TargetTriple.supportsCOMDAT() &&
710 (TargetTriple.isOSBinFormatELF() || !F.isInterposable()))
711 if (auto Comdat = getOrCreateFunctionComdat(F, TargetTriple))
712 Array->setComdat(Comdat);
713 Array->setSection(getSectionName(Section));
714 Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedValue()));
715
716 // sancov_pcs parallels the other metadata section(s). Optimizers (e.g.
717 // GlobalOpt/ConstantMerge) may not discard sancov_pcs and the other
718 // section(s) as a unit, so we conservatively retain all unconditionally in
719 // the compiler.
720 //
721 // With comdat (COFF/ELF), the linker can guarantee the associated sections
722 // will be retained or discarded as a unit, so llvm.compiler.used is
723 // sufficient. Otherwise, conservatively make all of them retained by the
724 // linker.
725 if (Array->hasComdat())
726 GlobalsToAppendToCompilerUsed.push_back(Array);
727 else
728 GlobalsToAppendToUsed.push_back(Array);
729
730 return Array;
731 }
732
733 GlobalVariable *
CreatePCArray(Function & F,ArrayRef<BasicBlock * > AllBlocks)734 ModuleSanitizerCoverage::CreatePCArray(Function &F,
735 ArrayRef<BasicBlock *> AllBlocks) {
736 size_t N = AllBlocks.size();
737 assert(N);
738 SmallVector<Constant *, 32> PCs;
739 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
740 for (size_t i = 0; i < N; i++) {
741 if (&F.getEntryBlock() == AllBlocks[i]) {
742 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, PtrTy));
743 PCs.push_back((Constant *)IRB.CreateIntToPtr(
744 ConstantInt::get(IntptrTy, 1), PtrTy));
745 } else {
746 PCs.push_back((Constant *)IRB.CreatePointerCast(
747 BlockAddress::get(AllBlocks[i]), PtrTy));
748 PCs.push_back(Constant::getNullValue(PtrTy));
749 }
750 }
751 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, PtrTy,
752 SanCovPCsSectionName);
753 PCArray->setInitializer(
754 ConstantArray::get(ArrayType::get(PtrTy, N * 2), PCs));
755 PCArray->setConstant(true);
756
757 return PCArray;
758 }
759
CreateFunctionLocalArrays(Function & F,ArrayRef<BasicBlock * > AllBlocks)760 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
761 Function &F, ArrayRef<BasicBlock *> AllBlocks) {
762 if (Options.TracePCGuard)
763 FunctionGuardArray = CreateFunctionLocalArrayInSection(
764 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
765
766 if (Options.Inline8bitCounters)
767 Function8bitCounterArray = CreateFunctionLocalArrayInSection(
768 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
769 if (Options.InlineBoolFlag)
770 FunctionBoolArray = CreateFunctionLocalArrayInSection(
771 AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
772
773 if (Options.PCTable)
774 FunctionPCsArray = CreatePCArray(F, AllBlocks);
775 }
776
InjectCoverage(Function & F,ArrayRef<BasicBlock * > AllBlocks,bool IsLeafFunc)777 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
778 ArrayRef<BasicBlock *> AllBlocks,
779 bool IsLeafFunc) {
780 if (AllBlocks.empty()) return false;
781 CreateFunctionLocalArrays(F, AllBlocks);
782 for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
783 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
784 return true;
785 }
786
787 // On every indirect call we call a run-time function
788 // __sanitizer_cov_indir_call* with two parameters:
789 // - callee address,
790 // - global cache array that contains CacheSize pointers (zero-initialized).
791 // The cache is used to speed up recording the caller-callee pairs.
792 // The address of the caller is passed implicitly via caller PC.
793 // CacheSize is encoded in the name of the run-time function.
InjectCoverageForIndirectCalls(Function & F,ArrayRef<Instruction * > IndirCalls)794 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
795 Function &F, ArrayRef<Instruction *> IndirCalls) {
796 if (IndirCalls.empty())
797 return;
798 assert(Options.TracePC || Options.TracePCGuard ||
799 Options.Inline8bitCounters || Options.InlineBoolFlag);
800 for (auto *I : IndirCalls) {
801 InstrumentationIRBuilder IRB(I);
802 CallBase &CB = cast<CallBase>(*I);
803 Value *Callee = CB.getCalledOperand();
804 if (isa<InlineAsm>(Callee))
805 continue;
806 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
807 }
808 }
809
810 // For every switch statement we insert a call:
811 // __sanitizer_cov_trace_switch(CondValue,
812 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
813
InjectTraceForSwitch(Function &,ArrayRef<Instruction * > SwitchTraceTargets)814 void ModuleSanitizerCoverage::InjectTraceForSwitch(
815 Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
816 for (auto *I : SwitchTraceTargets) {
817 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
818 InstrumentationIRBuilder IRB(I);
819 SmallVector<Constant *, 16> Initializers;
820 Value *Cond = SI->getCondition();
821 if (Cond->getType()->getScalarSizeInBits() >
822 Int64Ty->getScalarSizeInBits())
823 continue;
824 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
825 Initializers.push_back(
826 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
827 if (Cond->getType()->getScalarSizeInBits() <
828 Int64Ty->getScalarSizeInBits())
829 Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
830 for (auto It : SI->cases()) {
831 ConstantInt *C = It.getCaseValue();
832 if (C->getType()->getScalarSizeInBits() < 64)
833 C = ConstantInt::get(C->getContext(), C->getValue().zext(64));
834 Initializers.push_back(C);
835 }
836 llvm::sort(drop_begin(Initializers, 2),
837 [](const Constant *A, const Constant *B) {
838 return cast<ConstantInt>(A)->getLimitedValue() <
839 cast<ConstantInt>(B)->getLimitedValue();
840 });
841 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
842 GlobalVariable *GV = new GlobalVariable(
843 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
844 ConstantArray::get(ArrayOfInt64Ty, Initializers),
845 "__sancov_gen_cov_switch_values");
846 IRB.CreateCall(SanCovTraceSwitchFunction, {Cond, GV});
847 }
848 }
849 }
850
InjectTraceForDiv(Function &,ArrayRef<BinaryOperator * > DivTraceTargets)851 void ModuleSanitizerCoverage::InjectTraceForDiv(
852 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
853 for (auto *BO : DivTraceTargets) {
854 InstrumentationIRBuilder IRB(BO);
855 Value *A1 = BO->getOperand(1);
856 if (isa<ConstantInt>(A1)) continue;
857 if (!A1->getType()->isIntegerTy())
858 continue;
859 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
860 int CallbackIdx = TypeSize == 32 ? 0 :
861 TypeSize == 64 ? 1 : -1;
862 if (CallbackIdx < 0) continue;
863 auto Ty = Type::getIntNTy(*C, TypeSize);
864 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
865 {IRB.CreateIntCast(A1, Ty, true)});
866 }
867 }
868
InjectTraceForGep(Function &,ArrayRef<GetElementPtrInst * > GepTraceTargets)869 void ModuleSanitizerCoverage::InjectTraceForGep(
870 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
871 for (auto *GEP : GepTraceTargets) {
872 InstrumentationIRBuilder IRB(GEP);
873 for (Use &Idx : GEP->indices())
874 if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
875 IRB.CreateCall(SanCovTraceGepFunction,
876 {IRB.CreateIntCast(Idx, IntptrTy, true)});
877 }
878 }
879
InjectTraceForLoadsAndStores(Function &,ArrayRef<LoadInst * > Loads,ArrayRef<StoreInst * > Stores)880 void ModuleSanitizerCoverage::InjectTraceForLoadsAndStores(
881 Function &, ArrayRef<LoadInst *> Loads, ArrayRef<StoreInst *> Stores) {
882 auto CallbackIdx = [&](Type *ElementTy) -> int {
883 uint64_t TypeSize = DL->getTypeStoreSizeInBits(ElementTy);
884 return TypeSize == 8 ? 0
885 : TypeSize == 16 ? 1
886 : TypeSize == 32 ? 2
887 : TypeSize == 64 ? 3
888 : TypeSize == 128 ? 4
889 : -1;
890 };
891 for (auto *LI : Loads) {
892 InstrumentationIRBuilder IRB(LI);
893 auto Ptr = LI->getPointerOperand();
894 int Idx = CallbackIdx(LI->getType());
895 if (Idx < 0)
896 continue;
897 IRB.CreateCall(SanCovLoadFunction[Idx], Ptr);
898 }
899 for (auto *SI : Stores) {
900 InstrumentationIRBuilder IRB(SI);
901 auto Ptr = SI->getPointerOperand();
902 int Idx = CallbackIdx(SI->getValueOperand()->getType());
903 if (Idx < 0)
904 continue;
905 IRB.CreateCall(SanCovStoreFunction[Idx], Ptr);
906 }
907 }
908
InjectTraceForCmp(Function &,ArrayRef<Instruction * > CmpTraceTargets)909 void ModuleSanitizerCoverage::InjectTraceForCmp(
910 Function &, ArrayRef<Instruction *> CmpTraceTargets) {
911 for (auto *I : CmpTraceTargets) {
912 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
913 InstrumentationIRBuilder IRB(ICMP);
914 Value *A0 = ICMP->getOperand(0);
915 Value *A1 = ICMP->getOperand(1);
916 if (!A0->getType()->isIntegerTy())
917 continue;
918 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
919 int CallbackIdx = TypeSize == 8 ? 0 :
920 TypeSize == 16 ? 1 :
921 TypeSize == 32 ? 2 :
922 TypeSize == 64 ? 3 : -1;
923 if (CallbackIdx < 0) continue;
924 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
925 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
926 bool FirstIsConst = isa<ConstantInt>(A0);
927 bool SecondIsConst = isa<ConstantInt>(A1);
928 // If both are const, then we don't need such a comparison.
929 if (FirstIsConst && SecondIsConst) continue;
930 // If only one is const, then make it the first callback argument.
931 if (FirstIsConst || SecondIsConst) {
932 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
933 if (SecondIsConst)
934 std::swap(A0, A1);
935 }
936
937 auto Ty = Type::getIntNTy(*C, TypeSize);
938 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
939 IRB.CreateIntCast(A1, Ty, true)});
940 }
941 }
942 }
943
InjectCoverageAtBlock(Function & F,BasicBlock & BB,size_t Idx,bool IsLeafFunc)944 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
945 size_t Idx,
946 bool IsLeafFunc) {
947 BasicBlock::iterator IP = BB.getFirstInsertionPt();
948 bool IsEntryBB = &BB == &F.getEntryBlock();
949 DebugLoc EntryLoc;
950 if (IsEntryBB) {
951 if (auto SP = F.getSubprogram())
952 EntryLoc = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
953 // Keep static allocas and llvm.localescape calls in the entry block. Even
954 // if we aren't splitting the block, it's nice for allocas to be before
955 // calls.
956 IP = PrepareToSplitEntryBlock(BB, IP);
957 }
958
959 InstrumentationIRBuilder IRB(&*IP);
960 if (EntryLoc)
961 IRB.SetCurrentDebugLocation(EntryLoc);
962 if (Options.TracePC) {
963 IRB.CreateCall(SanCovTracePC)
964 ->setCannotMerge(); // gets the PC using GET_CALLER_PC.
965 }
966 if (Options.TracePCGuard) {
967 auto GuardPtr = IRB.CreateIntToPtr(
968 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
969 ConstantInt::get(IntptrTy, Idx * 4)),
970 PtrTy);
971 IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
972 }
973 if (Options.Inline8bitCounters) {
974 auto CounterPtr = IRB.CreateGEP(
975 Function8bitCounterArray->getValueType(), Function8bitCounterArray,
976 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
977 auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
978 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
979 auto Store = IRB.CreateStore(Inc, CounterPtr);
980 Load->setNoSanitizeMetadata();
981 Store->setNoSanitizeMetadata();
982 }
983 if (Options.InlineBoolFlag) {
984 auto FlagPtr = IRB.CreateGEP(
985 FunctionBoolArray->getValueType(), FunctionBoolArray,
986 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
987 auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
988 auto ThenTerm = SplitBlockAndInsertIfThen(
989 IRB.CreateIsNull(Load), &*IP, false,
990 MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
991 IRBuilder<> ThenIRB(ThenTerm);
992 auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
993 Load->setNoSanitizeMetadata();
994 Store->setNoSanitizeMetadata();
995 }
996 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
997 // Check stack depth. If it's the deepest so far, record it.
998 Module *M = F.getParent();
999 Function *GetFrameAddr = Intrinsic::getDeclaration(
1000 M, Intrinsic::frameaddress,
1001 IRB.getPtrTy(M->getDataLayout().getAllocaAddrSpace()));
1002 auto FrameAddrPtr =
1003 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
1004 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
1005 auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
1006 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
1007 auto ThenTerm = SplitBlockAndInsertIfThen(
1008 IsStackLower, &*IP, false,
1009 MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
1010 IRBuilder<> ThenIRB(ThenTerm);
1011 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
1012 LowestStack->setNoSanitizeMetadata();
1013 Store->setNoSanitizeMetadata();
1014 }
1015 }
1016
1017 std::string
getSectionName(const std::string & Section) const1018 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
1019 if (TargetTriple.isOSBinFormatCOFF()) {
1020 if (Section == SanCovCountersSectionName)
1021 return ".SCOV$CM";
1022 if (Section == SanCovBoolFlagSectionName)
1023 return ".SCOV$BM";
1024 if (Section == SanCovPCsSectionName)
1025 return ".SCOVP$M";
1026 return ".SCOV$GM"; // For SanCovGuardsSectionName.
1027 }
1028 if (TargetTriple.isOSBinFormatMachO())
1029 return "__DATA,__" + Section;
1030 return "__" + Section;
1031 }
1032
1033 std::string
getSectionStart(const std::string & Section) const1034 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
1035 if (TargetTriple.isOSBinFormatMachO())
1036 return "\1section$start$__DATA$__" + Section;
1037 return "__start___" + Section;
1038 }
1039
1040 std::string
getSectionEnd(const std::string & Section) const1041 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
1042 if (TargetTriple.isOSBinFormatMachO())
1043 return "\1section$end$__DATA$__" + Section;
1044 return "__stop___" + Section;
1045 }
1046
createFunctionControlFlow(Function & F)1047 void ModuleSanitizerCoverage::createFunctionControlFlow(Function &F) {
1048 SmallVector<Constant *, 32> CFs;
1049 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
1050
1051 for (auto &BB : F) {
1052 // blockaddress can not be used on function's entry block.
1053 if (&BB == &F.getEntryBlock())
1054 CFs.push_back((Constant *)IRB.CreatePointerCast(&F, PtrTy));
1055 else
1056 CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(&BB),
1057 PtrTy));
1058
1059 for (auto SuccBB : successors(&BB)) {
1060 assert(SuccBB != &F.getEntryBlock());
1061 CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(SuccBB),
1062 PtrTy));
1063 }
1064
1065 CFs.push_back((Constant *)Constant::getNullValue(PtrTy));
1066
1067 for (auto &Inst : BB) {
1068 if (CallBase *CB = dyn_cast<CallBase>(&Inst)) {
1069 if (CB->isIndirectCall()) {
1070 // TODO(navidem): handle indirect calls, for now mark its existence.
1071 CFs.push_back((Constant *)IRB.CreateIntToPtr(
1072 ConstantInt::get(IntptrTy, -1), PtrTy));
1073 } else {
1074 auto CalledF = CB->getCalledFunction();
1075 if (CalledF && !CalledF->isIntrinsic())
1076 CFs.push_back(
1077 (Constant *)IRB.CreatePointerCast(CalledF, PtrTy));
1078 }
1079 }
1080 }
1081
1082 CFs.push_back((Constant *)Constant::getNullValue(PtrTy));
1083 }
1084
1085 FunctionCFsArray = CreateFunctionLocalArrayInSection(
1086 CFs.size(), F, PtrTy, SanCovCFsSectionName);
1087 FunctionCFsArray->setInitializer(
1088 ConstantArray::get(ArrayType::get(PtrTy, CFs.size()), CFs));
1089 FunctionCFsArray->setConstant(true);
1090 }
1091