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/ADT/Triple.h"
17 #include "llvm/Analysis/EHPersonalities.h"
18 #include "llvm/Analysis/PostDominators.h"
19 #include "llvm/IR/CFG.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/PassManager.h"
35 #include "llvm/IR/Type.h"
36 #include "llvm/InitializePasses.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/SpecialCaseList.h"
40 #include "llvm/Support/VirtualFileSystem.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include "llvm/Transforms/Instrumentation.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/ModuleUtils.h"
45 #include "llvm/Passes/PassPlugin.h"
46 #include "llvm/Passes/PassBuilder.h"
47 #include "llvm/IR/PassManager.h"
48
49 #include "config.h"
50 #include "debug.h"
51 #include "afl-llvm-common.h"
52
53 using namespace llvm;
54
55 #define DEBUG_TYPE "sancov"
56
57 const char SanCovTracePCIndirName[] = "__sanitizer_cov_trace_pc_indir";
58 const char SanCovTracePCName[] = "__sanitizer_cov_trace_pc";
59 const char SanCovTraceCmp1[] = "__sanitizer_cov_trace_cmp1";
60 const char SanCovTraceCmp2[] = "__sanitizer_cov_trace_cmp2";
61 const char SanCovTraceCmp4[] = "__sanitizer_cov_trace_cmp4";
62 const char SanCovTraceCmp8[] = "__sanitizer_cov_trace_cmp8";
63 const char SanCovTraceConstCmp1[] = "__sanitizer_cov_trace_const_cmp1";
64 const char SanCovTraceConstCmp2[] = "__sanitizer_cov_trace_const_cmp2";
65 const char SanCovTraceConstCmp4[] = "__sanitizer_cov_trace_const_cmp4";
66 const char SanCovTraceConstCmp8[] = "__sanitizer_cov_trace_const_cmp8";
67 const char SanCovTraceDiv4[] = "__sanitizer_cov_trace_div4";
68 const char SanCovTraceDiv8[] = "__sanitizer_cov_trace_div8";
69 const char SanCovTraceGep[] = "__sanitizer_cov_trace_gep";
70 const char SanCovTraceSwitchName[] = "__sanitizer_cov_trace_switch";
71 const char SanCovModuleCtorTracePcGuardName[] =
72 "sancov.module_ctor_trace_pc_guard";
73 const char SanCovModuleCtor8bitCountersName[] =
74 "sancov.module_ctor_8bit_counters";
75 const char SanCovModuleCtorBoolFlagName[] = "sancov.module_ctor_bool_flag";
76 static const uint64_t SanCtorAndDtorPriority = 2;
77
78 const char SanCovTracePCGuardName[] = "__sanitizer_cov_trace_pc_guard";
79 const char SanCovTracePCGuardInitName[] = "__sanitizer_cov_trace_pc_guard_init";
80 const char SanCov8bitCountersInitName[] = "__sanitizer_cov_8bit_counters_init";
81 const char SanCovBoolFlagInitName[] = "__sanitizer_cov_bool_flag_init";
82 const char SanCovPCsInitName[] = "__sanitizer_cov_pcs_init";
83
84 const char SanCovGuardsSectionName[] = "sancov_guards";
85 const char SanCovCountersSectionName[] = "sancov_cntrs";
86 const char SanCovBoolFlagSectionName[] = "sancov_bools";
87 const char SanCovPCsSectionName[] = "sancov_pcs";
88
89 const char SanCovLowestStackName[] = "__sancov_lowest_stack";
90
91 static const char *skip_nozero;
92 static const char *use_threadsafe_counters;
93
94 namespace {
95
OverrideFromCL(SanitizerCoverageOptions Options)96 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
97
98 // Sets CoverageType and IndirectCalls.
99 // SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
100 Options.CoverageType =
101 SanitizerCoverageOptions::SCK_Edge; // std::max(Options.CoverageType,
102 // CLOpts.CoverageType);
103 Options.IndirectCalls = false; // CLOpts.IndirectCalls;
104 Options.TraceCmp = false; //|= ClCMPTracing;
105 Options.TraceDiv = false; //|= ClDIVTracing;
106 Options.TraceGep = false; //|= ClGEPTracing;
107 Options.TracePC = false; //|= ClTracePC;
108 Options.TracePCGuard = true; // |= ClTracePCGuard;
109 Options.Inline8bitCounters = 0; //|= ClInline8bitCounters;
110 // Options.InlineBoolFlag = 0; //|= ClInlineBoolFlag;
111 Options.PCTable = false; //|= ClCreatePCTable;
112 Options.NoPrune = false; //|= !ClPruneBlocks;
113 Options.StackDepth = false; //|= ClStackDepth;
114 if (!Options.TracePCGuard && !Options.TracePC &&
115 !Options.Inline8bitCounters && !Options.StackDepth /*&&
116 !Options.InlineBoolFlag*/)
117 Options.TracePCGuard = true; // TracePCGuard is default.
118
119 return Options;
120
121 }
122
123 using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>;
124 using PostDomTreeCallback =
125 function_ref<const PostDominatorTree *(Function &F)>;
126
127 class ModuleSanitizerCoverageAFL
128 : public PassInfoMixin<ModuleSanitizerCoverageAFL> {
129
130 public:
ModuleSanitizerCoverageAFL(const SanitizerCoverageOptions & Options=SanitizerCoverageOptions ())131 ModuleSanitizerCoverageAFL(
132 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
133 : Options(OverrideFromCL(Options)) {
134
135 }
136
137 PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
138
139 bool instrumentModule(Module &M, DomTreeCallback DTCallback,
140 PostDomTreeCallback PDTCallback);
141
142 private:
143 void instrumentFunction(Function &F, DomTreeCallback DTCallback,
144 PostDomTreeCallback PDTCallback);
145 void InjectCoverageForIndirectCalls(Function & F,
146 ArrayRef<Instruction *> IndirCalls);
147 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
148 void InjectTraceForDiv(Function & F,
149 ArrayRef<BinaryOperator *> DivTraceTargets);
150 void InjectTraceForGep(Function & F,
151 ArrayRef<GetElementPtrInst *> GepTraceTargets);
152 void InjectTraceForSwitch(Function & F,
153 ArrayRef<Instruction *> SwitchTraceTargets);
154 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
155 bool IsLeafFunc = true);
156 GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
157 Function &F, Type *Ty,
158 const char *Section);
159 GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
160 void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks,
161 uint32_t special);
162 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
163 bool IsLeafFunc = true);
164 Function *CreateInitCallsForSections(Module &M, const char *CtorName,
165 const char *InitFunctionName, Type *Ty,
166 const char *Section);
167 std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
168 Type *Ty);
169
SetNoSanitizeMetadata(Instruction * I)170 void SetNoSanitizeMetadata(Instruction *I) {
171
172 I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
173 MDNode::get(*C, None));
174
175 }
176
177 std::string getSectionName(const std::string &Section) const;
178 std::string getSectionStart(const std::string &Section) const;
179 std::string getSectionEnd(const std::string &Section) const;
180 FunctionCallee SanCovTracePCIndir;
181 FunctionCallee SanCovTracePC, SanCovTracePCGuard;
182 FunctionCallee SanCovTraceCmpFunction[4];
183 FunctionCallee SanCovTraceConstCmpFunction[4];
184 FunctionCallee SanCovTraceDivFunction[2];
185 FunctionCallee SanCovTraceGepFunction;
186 FunctionCallee SanCovTraceSwitchFunction;
187 GlobalVariable *SanCovLowestStack;
188 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
189 *Int16Ty, *Int8Ty, *Int8PtrTy, *Int1Ty, *Int1PtrTy;
190 Module * CurModule;
191 std::string CurModuleUniqueId;
192 Triple TargetTriple;
193 LLVMContext * C;
194 const DataLayout *DL;
195
196 GlobalVariable *FunctionGuardArray; // for trace-pc-guard.
197 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters.
198 GlobalVariable *FunctionBoolArray; // for inline-bool-flag.
199 GlobalVariable *FunctionPCsArray; // for pc-table.
200 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
201 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
202
203 SanitizerCoverageOptions Options;
204
205 uint32_t instr = 0, selects = 0, unhandled = 0;
206 GlobalVariable *AFLMapPtr = NULL;
207 ConstantInt * One = NULL;
208 ConstantInt * Zero = NULL;
209
210 };
211
212 class ModuleSanitizerCoverageLegacyPass : public ModulePass {
213
214 public:
ModuleSanitizerCoverageLegacyPass(const SanitizerCoverageOptions & Options=SanitizerCoverageOptions ())215 ModuleSanitizerCoverageLegacyPass(
216 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
217 : ModulePass(ID), Options(Options) {
218
219 initializeModuleSanitizerCoverageLegacyPassPass(
220 *PassRegistry::getPassRegistry());
221
222 }
223
runOnModule(Module & M)224 bool runOnModule(Module &M) override {
225
226 ModuleSanitizerCoverageAFL ModuleSancov(Options);
227 auto DTCallback = [this](Function &F) -> const DominatorTree * {
228
229 return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
230
231 };
232
233 auto PDTCallback = [this](Function &F) -> const PostDominatorTree * {
234
235 return &this->getAnalysis<PostDominatorTreeWrapperPass>(F)
236 .getPostDomTree();
237
238 };
239
240 return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback);
241
242 }
243
244 /*static*/ char ID; // Pass identification, replacement for typeid
getPassName() const245 StringRef getPassName() const override {
246
247 return "ModuleSanitizerCoverage";
248
249 }
250
getAnalysisUsage(AnalysisUsage & AU) const251 void getAnalysisUsage(AnalysisUsage &AU) const override {
252
253 AU.addRequired<DominatorTreeWrapperPass>();
254 AU.addRequired<PostDominatorTreeWrapperPass>();
255
256 }
257
258 private:
259 SanitizerCoverageOptions Options;
260
261 };
262
263 } // namespace
264
265 #if 1
266
267 extern "C" ::llvm::PassPluginLibraryInfo LLVM_ATTRIBUTE_WEAK
llvmGetPassPluginInfo()268 llvmGetPassPluginInfo() {
269
270 return {LLVM_PLUGIN_API_VERSION, "SanitizerCoveragePCGUARD", "v0.1",
271 /* lambda to insert our pass into the pass pipeline. */
272 [](PassBuilder &PB) {
273
274 #if LLVM_VERSION_MAJOR <= 13
275 using OptimizationLevel = typename PassBuilder::OptimizationLevel;
276 #endif
277 PB.registerOptimizerLastEPCallback(
278 [](ModulePassManager &MPM, OptimizationLevel OL) {
279
280 MPM.addPass(ModuleSanitizerCoverageAFL());
281
282 });
283
284 }};
285
286 }
287
288 #endif
289
run(Module & M,ModuleAnalysisManager & MAM)290 PreservedAnalyses ModuleSanitizerCoverageAFL::run(Module & M,
291 ModuleAnalysisManager &MAM) {
292
293 ModuleSanitizerCoverageAFL ModuleSancov(Options);
294 auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
295 auto DTCallback = [&FAM](Function &F) -> const DominatorTree * {
296
297 return &FAM.getResult<DominatorTreeAnalysis>(F);
298
299 };
300
301 auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * {
302
303 return &FAM.getResult<PostDominatorTreeAnalysis>(F);
304
305 };
306
307 if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback))
308 return PreservedAnalyses::none();
309 return PreservedAnalyses::all();
310
311 }
312
CreateSecStartEnd(Module & M,const char * Section,Type * Ty)313 std::pair<Value *, Value *> ModuleSanitizerCoverageAFL::CreateSecStartEnd(
314 Module &M, const char *Section, Type *Ty) {
315
316 GlobalVariable *SecStart =
317 new GlobalVariable(M,
318 #if LLVM_VERSION_MAJOR >= 15
319 Ty,
320 #else
321 Ty->getPointerElementType(),
322 #endif
323 false, GlobalVariable::ExternalWeakLinkage, nullptr,
324 getSectionStart(Section));
325 SecStart->setVisibility(GlobalValue::HiddenVisibility);
326 GlobalVariable *SecEnd =
327 new GlobalVariable(M,
328 #if LLVM_VERSION_MAJOR >= 15
329 Ty,
330 #else
331 Ty->getPointerElementType(),
332 #endif
333 false, GlobalVariable::ExternalWeakLinkage, nullptr,
334 getSectionEnd(Section));
335 SecEnd->setVisibility(GlobalValue::HiddenVisibility);
336 IRBuilder<> IRB(M.getContext());
337 if (!TargetTriple.isOSBinFormatCOFF())
338 return std::make_pair(SecStart, SecEnd);
339
340 // Account for the fact that on windows-msvc __start_* symbols actually
341 // point to a uint64_t before the start of the array.
342 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
343 auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
344 ConstantInt::get(IntptrTy, sizeof(uint64_t)));
345 return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEnd);
346
347 }
348
CreateInitCallsForSections(Module & M,const char * CtorName,const char * InitFunctionName,Type * Ty,const char * Section)349 Function *ModuleSanitizerCoverageAFL::CreateInitCallsForSections(
350 Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
351 const char *Section) {
352
353 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
354 auto SecStart = SecStartEnd.first;
355 auto SecEnd = SecStartEnd.second;
356 Function *CtorFunc;
357 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
358 M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
359 assert(CtorFunc->getName() == CtorName);
360
361 if (TargetTriple.supportsCOMDAT()) {
362
363 // Use comdat to dedup CtorFunc.
364 CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
365 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
366
367 } else {
368
369 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
370
371 }
372
373 if (TargetTriple.isOSBinFormatCOFF()) {
374
375 // In COFF files, if the contructors are set as COMDAT (they are because
376 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
377 // functions and data) is used, the constructors get stripped. To prevent
378 // this, give the constructors weak ODR linkage and ensure the linker knows
379 // to include the sancov constructor. This way the linker can deduplicate
380 // the constructors but always leave one copy.
381 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
382 appendToUsed(M, CtorFunc);
383
384 }
385
386 return CtorFunc;
387
388 }
389
instrumentModule(Module & M,DomTreeCallback DTCallback,PostDomTreeCallback PDTCallback)390 bool ModuleSanitizerCoverageAFL::instrumentModule(
391 Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
392
393 setvbuf(stdout, NULL, _IONBF, 0);
394 if (getenv("AFL_DEBUG")) debug = 1;
395
396 if ((isatty(2) && !getenv("AFL_QUIET")) || debug) {
397
398 SAYF(cCYA "SanitizerCoveragePCGUARD" VERSION cRST "\n");
399
400 } else
401
402 be_quiet = 1;
403
404 skip_nozero = getenv("AFL_LLVM_SKIP_NEVERZERO");
405 use_threadsafe_counters = getenv("AFL_LLVM_THREADSAFE_INST");
406
407 initInstrumentList();
408 scanForDangerousFunctions(&M);
409
410 if (debug) {
411
412 fprintf(stderr,
413 "SANCOV: covtype:%u indirect:%d stack:%d noprune:%d "
414 "createtable:%d tracepcguard:%d tracepc:%d\n",
415 Options.CoverageType, Options.IndirectCalls == true ? 1 : 0,
416 Options.StackDepth == true ? 1 : 0, Options.NoPrune == true ? 1 : 0,
417 // Options.InlineBoolFlag == true ? 1 : 0,
418 Options.PCTable == true ? 1 : 0,
419 Options.TracePCGuard == true ? 1 : 0,
420 Options.TracePC == true ? 1 : 0);
421
422 }
423
424 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None) return false;
425 C = &(M.getContext());
426 DL = &M.getDataLayout();
427 CurModule = &M;
428 CurModuleUniqueId = getUniqueModuleId(CurModule);
429 TargetTriple = Triple(M.getTargetTriple());
430 FunctionGuardArray = nullptr;
431 Function8bitCounterArray = nullptr;
432 FunctionBoolArray = nullptr;
433 FunctionPCsArray = nullptr;
434 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
435 IntptrPtrTy = PointerType::getUnqual(IntptrTy);
436 Type * VoidTy = Type::getVoidTy(*C);
437 IRBuilder<> IRB(*C);
438 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
439 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
440 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
441 Int1PtrTy = PointerType::getUnqual(IRB.getInt1Ty());
442 Int64Ty = IRB.getInt64Ty();
443 Int32Ty = IRB.getInt32Ty();
444 Int16Ty = IRB.getInt16Ty();
445 Int8Ty = IRB.getInt8Ty();
446 Int1Ty = IRB.getInt1Ty();
447 LLVMContext &Ctx = M.getContext();
448
449 AFLMapPtr =
450 new GlobalVariable(M, PointerType::get(Int8Ty, 0), false,
451 GlobalValue::ExternalLinkage, 0, "__afl_area_ptr");
452 One = ConstantInt::get(IntegerType::getInt8Ty(Ctx), 1);
453 Zero = ConstantInt::get(IntegerType::getInt8Ty(Ctx), 0);
454
455 SanCovTracePCIndir =
456 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
457 // Make sure smaller parameters are zero-extended to i64 if required by the
458 // target ABI.
459 AttributeList SanCovTraceCmpZeroExtAL;
460 SanCovTraceCmpZeroExtAL =
461 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
462 SanCovTraceCmpZeroExtAL =
463 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
464
465 SanCovTraceCmpFunction[0] =
466 M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
467 IRB.getInt8Ty(), IRB.getInt8Ty());
468 SanCovTraceCmpFunction[1] =
469 M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
470 IRB.getInt16Ty(), IRB.getInt16Ty());
471 SanCovTraceCmpFunction[2] =
472 M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
473 IRB.getInt32Ty(), IRB.getInt32Ty());
474 SanCovTraceCmpFunction[3] =
475 M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
476
477 SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
478 SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
479 SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
480 SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
481 SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
482 SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
483 SanCovTraceConstCmpFunction[3] =
484 M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
485
486 {
487
488 AttributeList AL;
489 AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
490 SanCovTraceDivFunction[0] =
491 M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
492
493 }
494
495 SanCovTraceDivFunction[1] =
496 M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
497 SanCovTraceGepFunction =
498 M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
499 SanCovTraceSwitchFunction =
500 M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
501
502 Constant *SanCovLowestStackConstant =
503 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
504 SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
505 if (!SanCovLowestStack) {
506
507 C->emitError(StringRef("'") + SanCovLowestStackName +
508 "' should not be declared by the user");
509 return true;
510
511 }
512
513 SanCovLowestStack->setThreadLocalMode(
514 GlobalValue::ThreadLocalMode::InitialExecTLSModel);
515 if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
516 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
517
518 SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
519 SanCovTracePCGuard =
520 M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
521
522 for (auto &F : M)
523 instrumentFunction(F, DTCallback, PDTCallback);
524
525 Function *Ctor = nullptr;
526
527 if (FunctionGuardArray)
528 Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
529 SanCovTracePCGuardInitName, Int32PtrTy,
530 SanCovGuardsSectionName);
531 if (Function8bitCounterArray)
532 Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
533 SanCov8bitCountersInitName, Int8PtrTy,
534 SanCovCountersSectionName);
535 if (FunctionBoolArray) {
536
537 Ctor = CreateInitCallsForSections(M, SanCovModuleCtorBoolFlagName,
538 SanCovBoolFlagInitName, Int1PtrTy,
539 SanCovBoolFlagSectionName);
540
541 }
542
543 if (Ctor && Options.PCTable) {
544
545 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
546 FunctionCallee InitFunction = declareSanitizerInitFunction(
547 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
548 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
549 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
550
551 }
552
553 // We don't reference these arrays directly in any of our runtime functions,
554 // so we need to prevent them from being dead stripped.
555 if (TargetTriple.isOSBinFormatMachO()) appendToUsed(M, GlobalsToAppendToUsed);
556 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
557
558 if (!be_quiet) {
559
560 if (!instr)
561 WARNF("No instrumentation targets found.");
562 else {
563
564 char modeline[100];
565 snprintf(modeline, sizeof(modeline), "%s%s%s%s%s%s",
566 getenv("AFL_HARDEN") ? "hardened" : "non-hardened",
567 getenv("AFL_USE_ASAN") ? ", ASAN" : "",
568 getenv("AFL_USE_MSAN") ? ", MSAN" : "",
569 getenv("AFL_USE_TSAN") ? ", TSAN" : "",
570 getenv("AFL_USE_CFISAN") ? ", CFISAN" : "",
571 getenv("AFL_USE_UBSAN") ? ", UBSAN" : "");
572 OKF("Instrumented %u locations with no collisions (%s mode) of which are "
573 "%u handled and %u unhandled selects.",
574 instr, modeline, selects, unhandled);
575
576 }
577
578 }
579
580 return true;
581
582 }
583
584 // True if block has successors and it dominates all of them.
isFullDominator(const BasicBlock * BB,const DominatorTree * DT)585 bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
586
587 if (succ_begin(BB) == succ_end(BB)) return false;
588
589 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
590
591 if (!DT->dominates(BB, SUCC)) return false;
592
593 }
594
595 return true;
596
597 }
598
599 // True if block has predecessors and it postdominates all of them.
isFullPostDominator(const BasicBlock * BB,const PostDominatorTree * PDT)600 bool isFullPostDominator(const BasicBlock *BB, const PostDominatorTree *PDT) {
601
602 if (pred_begin(BB) == pred_end(BB)) return false;
603
604 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
605
606 if (!PDT->dominates(BB, PRED)) return false;
607
608 }
609
610 return true;
611
612 }
613
shouldInstrumentBlock(const Function & F,const BasicBlock * BB,const DominatorTree * DT,const PostDominatorTree * PDT,const SanitizerCoverageOptions & Options)614 bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
615 const DominatorTree * DT,
616 const PostDominatorTree * PDT,
617 const SanitizerCoverageOptions &Options) {
618
619 // Don't insert coverage for blocks containing nothing but unreachable: we
620 // will never call __sanitizer_cov() for them, so counting them in
621 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
622 // percentage. Also, unreachable instructions frequently have no debug
623 // locations.
624 if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime())) return false;
625
626 // Don't insert coverage into blocks without a valid insertion point
627 // (catchswitch blocks).
628 if (BB->getFirstInsertionPt() == BB->end()) return false;
629
630 if (Options.NoPrune || &F.getEntryBlock() == BB) return true;
631
632 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
633 &F.getEntryBlock() != BB)
634 return false;
635
636 // Do not instrument full dominators, or full post-dominators with multiple
637 // predecessors.
638 return !isFullDominator(BB, DT) &&
639 !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
640
641 }
642
643 // Returns true iff From->To is a backedge.
644 // A twist here is that we treat From->To as a backedge if
645 // * To dominates From or
646 // * To->UniqueSuccessor dominates From
IsBackEdge(BasicBlock * From,BasicBlock * To,const DominatorTree * DT)647 bool IsBackEdge(BasicBlock *From, BasicBlock *To, const DominatorTree *DT) {
648
649 if (DT->dominates(To, From)) return true;
650 if (auto Next = To->getUniqueSuccessor())
651 if (DT->dominates(Next, From)) return true;
652 return false;
653
654 }
655
656 // Prunes uninteresting Cmp instrumentation:
657 // * CMP instructions that feed into loop backedge branch.
658 //
659 // Note that Cmp pruning is controlled by the same flag as the
660 // BB pruning.
IsInterestingCmp(ICmpInst * CMP,const DominatorTree * DT,const SanitizerCoverageOptions & Options)661 bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
662 const SanitizerCoverageOptions &Options) {
663
664 if (!Options.NoPrune)
665 if (CMP->hasOneUse())
666 if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
667 for (BasicBlock *B : BR->successors())
668 if (IsBackEdge(BR->getParent(), B, DT)) return false;
669 return true;
670
671 }
672
instrumentFunction(Function & F,DomTreeCallback DTCallback,PostDomTreeCallback PDTCallback)673 void ModuleSanitizerCoverageAFL::instrumentFunction(
674 Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
675
676 if (F.empty()) return;
677 if (!isInInstrumentList(&F, FMNAME)) return;
678
679 if (F.getName().find(".module_ctor") != std::string::npos)
680 return; // Should not instrument sanitizer init functions.
681 if (F.getName().startswith("__sanitizer_"))
682 return; // Don't instrument __sanitizer_* callbacks.
683 // Don't touch available_externally functions, their actual body is elewhere.
684 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return;
685 // Don't instrument MSVC CRT configuration helpers. They may run before normal
686 // initialization.
687 if (F.getName() == "__local_stdio_printf_options" ||
688 F.getName() == "__local_stdio_scanf_options")
689 return;
690 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator())) return;
691 // Don't instrument functions using SEH for now. Splitting basic blocks like
692 // we do for coverage breaks WinEHPrepare.
693 // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
694 if (F.hasPersonalityFn() &&
695 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
696 return;
697 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
698 SplitAllCriticalEdges(
699 F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
700 SmallVector<Instruction *, 8> IndirCalls;
701 SmallVector<BasicBlock *, 16> BlocksToInstrument;
702 SmallVector<Instruction *, 8> CmpTraceTargets;
703 SmallVector<Instruction *, 8> SwitchTraceTargets;
704 SmallVector<BinaryOperator *, 8> DivTraceTargets;
705 SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
706
707 const DominatorTree * DT = DTCallback(F);
708 const PostDominatorTree *PDT = PDTCallback(F);
709 bool IsLeafFunc = true;
710
711 for (auto &BB : F) {
712
713 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
714 BlocksToInstrument.push_back(&BB);
715 for (auto &Inst : BB) {
716
717 if (Options.IndirectCalls) {
718
719 CallBase *CB = dyn_cast<CallBase>(&Inst);
720 if (CB && !CB->getCalledFunction()) IndirCalls.push_back(&Inst);
721
722 }
723
724 if (Options.TraceCmp) {
725
726 if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
727 if (IsInterestingCmp(CMP, DT, Options))
728 CmpTraceTargets.push_back(&Inst);
729 if (isa<SwitchInst>(&Inst)) SwitchTraceTargets.push_back(&Inst);
730
731 }
732
733 if (Options.TraceDiv)
734 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
735 if (BO->getOpcode() == Instruction::SDiv ||
736 BO->getOpcode() == Instruction::UDiv)
737 DivTraceTargets.push_back(BO);
738 if (Options.TraceGep)
739 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
740 GepTraceTargets.push_back(GEP);
741 if (Options.StackDepth)
742 if (isa<InvokeInst>(Inst) ||
743 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
744 IsLeafFunc = false;
745
746 }
747
748 }
749
750 InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
751 InjectCoverageForIndirectCalls(F, IndirCalls);
752 InjectTraceForCmp(F, CmpTraceTargets);
753 InjectTraceForSwitch(F, SwitchTraceTargets);
754 InjectTraceForDiv(F, DivTraceTargets);
755 InjectTraceForGep(F, GepTraceTargets);
756
757 }
758
CreateFunctionLocalArrayInSection(size_t NumElements,Function & F,Type * Ty,const char * Section)759 GlobalVariable *ModuleSanitizerCoverageAFL::CreateFunctionLocalArrayInSection(
760 size_t NumElements, Function &F, Type *Ty, const char *Section) {
761
762 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
763 auto Array = new GlobalVariable(
764 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
765 Constant::getNullValue(ArrayTy), "__sancov_gen_");
766
767 #if LLVM_VERSION_MAJOR >= 13
768 if (TargetTriple.supportsCOMDAT() &&
769 (TargetTriple.isOSBinFormatELF() || !F.isInterposable()))
770 if (auto Comdat = getOrCreateFunctionComdat(F, TargetTriple))
771 Array->setComdat(Comdat);
772 #else
773 if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
774 if (auto Comdat =
775 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
776 Array->setComdat(Comdat);
777 #endif
778
779 Array->setSection(getSectionName(Section));
780 #if (LLVM_VERSION_MAJOR >= 11) || \
781 (LLVM_VERSION_MAJOR == 10 && LLVM_VERSION_MINOR >= 1)
782 Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedSize()));
783 #else
784 Array->setAlignment(Align(4)); // cheating
785 #endif
786 GlobalsToAppendToUsed.push_back(Array);
787 GlobalsToAppendToCompilerUsed.push_back(Array);
788 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
789 Array->addMetadata(LLVMContext::MD_associated, *MD);
790
791 return Array;
792
793 }
794
CreatePCArray(Function & F,ArrayRef<BasicBlock * > AllBlocks)795 GlobalVariable *ModuleSanitizerCoverageAFL::CreatePCArray(
796 Function &F, ArrayRef<BasicBlock *> AllBlocks) {
797
798 size_t N = AllBlocks.size();
799 assert(N);
800 SmallVector<Constant *, 32> PCs;
801 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
802 for (size_t i = 0; i < N; i++) {
803
804 if (&F.getEntryBlock() == AllBlocks[i]) {
805
806 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
807 PCs.push_back((Constant *)IRB.CreateIntToPtr(
808 ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
809
810 } else {
811
812 PCs.push_back((Constant *)IRB.CreatePointerCast(
813 BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
814 PCs.push_back((Constant *)IRB.CreateIntToPtr(
815 ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
816
817 }
818
819 }
820
821 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
822 SanCovPCsSectionName);
823 PCArray->setInitializer(
824 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
825 PCArray->setConstant(true);
826
827 return PCArray;
828
829 }
830
CreateFunctionLocalArrays(Function & F,ArrayRef<BasicBlock * > AllBlocks,uint32_t special)831 void ModuleSanitizerCoverageAFL::CreateFunctionLocalArrays(
832 Function &F, ArrayRef<BasicBlock *> AllBlocks, uint32_t special) {
833
834 if (Options.TracePCGuard)
835 FunctionGuardArray = CreateFunctionLocalArrayInSection(
836 AllBlocks.size() + special, F, Int32Ty, SanCovGuardsSectionName);
837
838 if (Options.Inline8bitCounters)
839 Function8bitCounterArray = CreateFunctionLocalArrayInSection(
840 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
841 /*
842 if (Options.InlineBoolFlag)
843 FunctionBoolArray = CreateFunctionLocalArrayInSection(
844 AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
845 */
846 if (Options.PCTable) FunctionPCsArray = CreatePCArray(F, AllBlocks);
847
848 }
849
InjectCoverage(Function & F,ArrayRef<BasicBlock * > AllBlocks,bool IsLeafFunc)850 bool ModuleSanitizerCoverageAFL::InjectCoverage(
851 Function &F, ArrayRef<BasicBlock *> AllBlocks, bool IsLeafFunc) {
852
853 uint32_t cnt_cov = 0, cnt_sel = 0, cnt_sel_inc = 0;
854
855 for (auto &BB : F) {
856
857 for (auto &IN : BB) {
858
859 CallInst *callInst = nullptr;
860
861 if ((callInst = dyn_cast<CallInst>(&IN))) {
862
863 Function *Callee = callInst->getCalledFunction();
864 if (!Callee) continue;
865 if (callInst->getCallingConv() != llvm::CallingConv::C) continue;
866 StringRef FuncName = Callee->getName();
867 if (!FuncName.compare(StringRef("dlopen")) ||
868 !FuncName.compare(StringRef("_dlopen"))) {
869
870 fprintf(stderr,
871 "WARNING: dlopen() detected. To have coverage for a library "
872 "that your target dlopen()'s this must either happen before "
873 "__AFL_INIT() or you must use AFL_PRELOAD to preload all "
874 "dlopen()'ed libraries!\n");
875 continue;
876
877 }
878
879 if (FuncName.compare(StringRef("__afl_coverage_interesting"))) continue;
880
881 cnt_cov++;
882
883 }
884
885 SelectInst *selectInst = nullptr;
886
887 if ((selectInst = dyn_cast<SelectInst>(&IN))) {
888
889 Value *c = selectInst->getCondition();
890 auto t = c->getType();
891 if (t->getTypeID() == llvm::Type::IntegerTyID) {
892
893 cnt_sel++;
894 cnt_sel_inc += 2;
895
896 }
897
898 #if (LLVM_VERSION_MAJOR >= 12)
899 else if (t->getTypeID() == llvm::Type::FixedVectorTyID) {
900
901 FixedVectorType *tt = dyn_cast<FixedVectorType>(t);
902 if (tt) {
903
904 cnt_sel++;
905 cnt_sel_inc += tt->getElementCount().getKnownMinValue();
906
907 }
908
909 }
910
911 #endif
912
913 }
914
915 }
916
917 }
918
919 /* Create PCGUARD array */
920 CreateFunctionLocalArrays(F, AllBlocks, cnt_cov + cnt_sel_inc);
921 selects += cnt_sel;
922
923 uint32_t special = 0, local_selects = 0, skip_next = 0;
924
925 for (auto &BB : F) {
926
927 for (auto &IN : BB) {
928
929 CallInst *callInst = nullptr;
930
931 /*
932 std::string errMsg;
933 raw_string_ostream os(errMsg);
934 IN.print(os);
935 fprintf(stderr, "X: %s\n", os.str().c_str());
936 */
937 if ((callInst = dyn_cast<CallInst>(&IN))) {
938
939 Function *Callee = callInst->getCalledFunction();
940 if (!Callee) continue;
941 if (callInst->getCallingConv() != llvm::CallingConv::C) continue;
942 StringRef FuncName = Callee->getName();
943 if (FuncName.compare(StringRef("__afl_coverage_interesting"))) continue;
944
945 IRBuilder<> IRB(callInst);
946
947 if (!FunctionGuardArray) {
948
949 fprintf(stderr,
950 "SANCOV: FunctionGuardArray is NULL, failed to emit "
951 "instrumentation.");
952 continue;
953
954 }
955
956 Value *GuardPtr = IRB.CreateIntToPtr(
957 IRB.CreateAdd(
958 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
959 ConstantInt::get(IntptrTy, (++special + AllBlocks.size()) * 4)),
960 Int32PtrTy);
961
962 LoadInst *Idx = IRB.CreateLoad(IRB.getInt32Ty(), GuardPtr);
963 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(Idx);
964
965 callInst->setOperand(1, Idx);
966
967 }
968
969 SelectInst *selectInst = nullptr;
970
971 if (!skip_next && (selectInst = dyn_cast<SelectInst>(&IN))) {
972
973 uint32_t vector_cnt = 0;
974 Value * condition = selectInst->getCondition();
975 Value * result;
976 auto t = condition->getType();
977 IRBuilder<> IRB(selectInst->getNextNode());
978
979 if (t->getTypeID() == llvm::Type::IntegerTyID) {
980
981 if (!FunctionGuardArray) {
982
983 fprintf(stderr,
984 "SANCOV: FunctionGuardArray is NULL, failed to emit "
985 "instrumentation.");
986 continue;
987
988 }
989
990 auto GuardPtr1 = IRB.CreateIntToPtr(
991 IRB.CreateAdd(
992 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
993 ConstantInt::get(
994 IntptrTy,
995 (cnt_cov + ++local_selects + AllBlocks.size()) * 4)),
996 Int32PtrTy);
997
998 auto GuardPtr2 = IRB.CreateIntToPtr(
999 IRB.CreateAdd(
1000 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1001 ConstantInt::get(
1002 IntptrTy,
1003 (cnt_cov + ++local_selects + AllBlocks.size()) * 4)),
1004 Int32PtrTy);
1005
1006 result = IRB.CreateSelect(condition, GuardPtr1, GuardPtr2);
1007
1008 } else
1009
1010 #if LLVM_VERSION_MAJOR >= 14
1011 if (t->getTypeID() == llvm::Type::FixedVectorTyID) {
1012
1013 FixedVectorType *tt = dyn_cast<FixedVectorType>(t);
1014 if (tt) {
1015
1016 uint32_t elements = tt->getElementCount().getFixedValue();
1017 vector_cnt = elements;
1018 if (elements) {
1019
1020 FixedVectorType *GuardPtr1 =
1021 FixedVectorType::get(Int32PtrTy, elements);
1022 FixedVectorType *GuardPtr2 =
1023 FixedVectorType::get(Int32PtrTy, elements);
1024 Value *x, *y;
1025
1026 if (!FunctionGuardArray) {
1027
1028 fprintf(stderr,
1029 "SANCOV: FunctionGuardArray is NULL, failed to emit "
1030 "instrumentation.");
1031 continue;
1032
1033 }
1034
1035 Value *val1 = IRB.CreateIntToPtr(
1036 IRB.CreateAdd(
1037 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1038 ConstantInt::get(
1039 IntptrTy,
1040 (cnt_cov + ++local_selects + AllBlocks.size()) * 4)),
1041 Int32PtrTy);
1042 x = IRB.CreateInsertElement(GuardPtr1, val1, (uint64_t)0);
1043
1044 Value *val2 = IRB.CreateIntToPtr(
1045 IRB.CreateAdd(
1046 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1047 ConstantInt::get(
1048 IntptrTy,
1049 (cnt_cov + ++local_selects + AllBlocks.size()) * 4)),
1050 Int32PtrTy);
1051 y = IRB.CreateInsertElement(GuardPtr2, val2, (uint64_t)0);
1052
1053 for (uint64_t i = 1; i < elements; i++) {
1054
1055 val1 = IRB.CreateIntToPtr(
1056 IRB.CreateAdd(
1057 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1058 ConstantInt::get(IntptrTy, (cnt_cov + ++local_selects +
1059 AllBlocks.size()) *
1060 4)),
1061 Int32PtrTy);
1062 x = IRB.CreateInsertElement(x, val1, i);
1063
1064 val2 = IRB.CreateIntToPtr(
1065 IRB.CreateAdd(
1066 IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1067 ConstantInt::get(IntptrTy, (cnt_cov + ++local_selects +
1068 AllBlocks.size()) *
1069 4)),
1070 Int32PtrTy);
1071 y = IRB.CreateInsertElement(y, val2, i);
1072
1073 }
1074
1075 /*
1076 std::string errMsg;
1077 raw_string_ostream os(errMsg);
1078 x->print(os);
1079 fprintf(stderr, "X: %s\n", os.str().c_str());
1080 */
1081 result = IRB.CreateSelect(condition, x, y);
1082
1083 }
1084
1085 }
1086
1087 } else
1088
1089 #endif
1090 {
1091
1092 unhandled++;
1093 continue;
1094
1095 }
1096
1097 uint32_t vector_cur = 0;
1098
1099 /* Load SHM pointer */
1100
1101 LoadInst *MapPtr =
1102 IRB.CreateLoad(PointerType::get(Int8Ty, 0), AFLMapPtr);
1103 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(MapPtr);
1104
1105 /*
1106 std::string errMsg;
1107 raw_string_ostream os(errMsg);
1108 result->print(os);
1109 fprintf(stderr, "X: %s\n", os.str().c_str());
1110 */
1111
1112 while (1) {
1113
1114 /* Get CurLoc */
1115 LoadInst *CurLoc = nullptr;
1116 Value * MapPtrIdx = nullptr;
1117
1118 /* Load counter for CurLoc */
1119 if (!vector_cnt) {
1120
1121 CurLoc = IRB.CreateLoad(IRB.getInt32Ty(), result);
1122 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(CurLoc);
1123 MapPtrIdx = IRB.CreateGEP(Int8Ty, MapPtr, CurLoc);
1124
1125 } else {
1126
1127 auto element = IRB.CreateExtractElement(result, vector_cur++);
1128 auto elementptr = IRB.CreateIntToPtr(element, Int32PtrTy);
1129 auto elementld = IRB.CreateLoad(IRB.getInt32Ty(), elementptr);
1130 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(elementld);
1131 MapPtrIdx = IRB.CreateGEP(Int8Ty, MapPtr, elementld);
1132
1133 }
1134
1135 if (use_threadsafe_counters) {
1136
1137 IRB.CreateAtomicRMW(llvm::AtomicRMWInst::BinOp::Add, MapPtrIdx, One,
1138 #if LLVM_VERSION_MAJOR >= 13
1139 llvm::MaybeAlign(1),
1140 #endif
1141 llvm::AtomicOrdering::Monotonic);
1142
1143 } else {
1144
1145 LoadInst *Counter = IRB.CreateLoad(IRB.getInt8Ty(), MapPtrIdx);
1146 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(Counter);
1147
1148 /* Update bitmap */
1149
1150 Value *Incr = IRB.CreateAdd(Counter, One);
1151
1152 if (skip_nozero == NULL) {
1153
1154 auto cf = IRB.CreateICmpEQ(Incr, Zero);
1155 auto carry = IRB.CreateZExt(cf, Int8Ty);
1156 Incr = IRB.CreateAdd(Incr, carry);
1157
1158 }
1159
1160 StoreInst *StoreCtx = IRB.CreateStore(Incr, MapPtrIdx);
1161 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(StoreCtx);
1162
1163 }
1164
1165 if (!vector_cnt) {
1166
1167 vector_cnt = 2;
1168 break;
1169
1170 } else if (vector_cnt == vector_cur) {
1171
1172 break;
1173
1174 }
1175
1176 }
1177
1178 skip_next = 1;
1179 instr += vector_cnt;
1180
1181 } else {
1182
1183 skip_next = 0;
1184
1185 }
1186
1187 }
1188
1189 }
1190
1191 if (AllBlocks.empty() && !special && !local_selects) return false;
1192
1193 if (!AllBlocks.empty())
1194 for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
1195 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
1196
1197 return true;
1198
1199 }
1200
1201 // On every indirect call we call a run-time function
1202 // __sanitizer_cov_indir_call* with two parameters:
1203 // - callee address,
1204 // - global cache array that contains CacheSize pointers (zero-initialized).
1205 // The cache is used to speed up recording the caller-callee pairs.
1206 // The address of the caller is passed implicitly via caller PC.
1207 // CacheSize is encoded in the name of the run-time function.
InjectCoverageForIndirectCalls(Function & F,ArrayRef<Instruction * > IndirCalls)1208 void ModuleSanitizerCoverageAFL::InjectCoverageForIndirectCalls(
1209 Function &F, ArrayRef<Instruction *> IndirCalls) {
1210
1211 if (IndirCalls.empty()) return;
1212 for (auto I : IndirCalls) {
1213
1214 IRBuilder<> IRB(I);
1215 CallBase & CB = cast<CallBase>(*I);
1216 Value * Callee = CB.getCalledOperand();
1217 if (isa<InlineAsm>(Callee)) continue;
1218 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
1219
1220 }
1221
1222 }
1223
1224 // For every switch statement we insert a call:
1225 // __sanitizer_cov_trace_switch(CondValue,
1226 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
1227
InjectTraceForSwitch(Function &,ArrayRef<Instruction * > SwitchTraceTargets)1228 void ModuleSanitizerCoverageAFL::InjectTraceForSwitch(
1229 Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
1230
1231 for (auto I : SwitchTraceTargets) {
1232
1233 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
1234
1235 IRBuilder<> IRB(I);
1236 SmallVector<Constant *, 16> Initializers;
1237 Value * Cond = SI->getCondition();
1238 if (Cond->getType()->getScalarSizeInBits() >
1239 Int64Ty->getScalarSizeInBits())
1240 continue;
1241 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
1242 Initializers.push_back(
1243 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
1244 if (Cond->getType()->getScalarSizeInBits() <
1245 Int64Ty->getScalarSizeInBits())
1246 Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
1247 for (auto It : SI->cases()) {
1248
1249 Constant *C = It.getCaseValue();
1250 if (C->getType()->getScalarSizeInBits() <
1251 Int64Ty->getScalarSizeInBits())
1252 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
1253 Initializers.push_back(C);
1254
1255 }
1256
1257 llvm::sort(drop_begin(Initializers, 2),
1258 [](const Constant *A, const Constant *B) {
1259
1260 return cast<ConstantInt>(A)->getLimitedValue() <
1261 cast<ConstantInt>(B)->getLimitedValue();
1262
1263 });
1264
1265 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
1266 GlobalVariable *GV = new GlobalVariable(
1267 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
1268 ConstantArray::get(ArrayOfInt64Ty, Initializers),
1269 "__sancov_gen_cov_switch_values");
1270 IRB.CreateCall(SanCovTraceSwitchFunction,
1271 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
1272
1273 }
1274
1275 }
1276
1277 }
1278
InjectTraceForDiv(Function &,ArrayRef<BinaryOperator * > DivTraceTargets)1279 void ModuleSanitizerCoverageAFL::InjectTraceForDiv(
1280 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
1281
1282 for (auto BO : DivTraceTargets) {
1283
1284 IRBuilder<> IRB(BO);
1285 Value * A1 = BO->getOperand(1);
1286 if (isa<ConstantInt>(A1)) continue;
1287 if (!A1->getType()->isIntegerTy()) continue;
1288 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
1289 int CallbackIdx = TypeSize == 32 ? 0 : TypeSize == 64 ? 1 : -1;
1290 if (CallbackIdx < 0) continue;
1291 auto Ty = Type::getIntNTy(*C, TypeSize);
1292 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
1293 {IRB.CreateIntCast(A1, Ty, true)});
1294
1295 }
1296
1297 }
1298
InjectTraceForGep(Function &,ArrayRef<GetElementPtrInst * > GepTraceTargets)1299 void ModuleSanitizerCoverageAFL::InjectTraceForGep(
1300 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
1301
1302 for (auto GEP : GepTraceTargets) {
1303
1304 IRBuilder<> IRB(GEP);
1305 for (Use &Idx : GEP->indices())
1306 if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
1307 IRB.CreateCall(SanCovTraceGepFunction,
1308 {IRB.CreateIntCast(Idx, IntptrTy, true)});
1309
1310 }
1311
1312 }
1313
InjectTraceForCmp(Function &,ArrayRef<Instruction * > CmpTraceTargets)1314 void ModuleSanitizerCoverageAFL::InjectTraceForCmp(
1315 Function &, ArrayRef<Instruction *> CmpTraceTargets) {
1316
1317 for (auto I : CmpTraceTargets) {
1318
1319 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
1320
1321 IRBuilder<> IRB(ICMP);
1322 Value * A0 = ICMP->getOperand(0);
1323 Value * A1 = ICMP->getOperand(1);
1324 if (!A0->getType()->isIntegerTy()) continue;
1325 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
1326 int CallbackIdx = TypeSize == 8 ? 0
1327 : TypeSize == 16 ? 1
1328 : TypeSize == 32 ? 2
1329 : TypeSize == 64 ? 3
1330 : -1;
1331 if (CallbackIdx < 0) continue;
1332 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
1333 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
1334 bool FirstIsConst = isa<ConstantInt>(A0);
1335 bool SecondIsConst = isa<ConstantInt>(A1);
1336 // If both are const, then we don't need such a comparison.
1337 if (FirstIsConst && SecondIsConst) continue;
1338 // If only one is const, then make it the first callback argument.
1339 if (FirstIsConst || SecondIsConst) {
1340
1341 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
1342 if (SecondIsConst) std::swap(A0, A1);
1343
1344 }
1345
1346 auto Ty = Type::getIntNTy(*C, TypeSize);
1347 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
1348 IRB.CreateIntCast(A1, Ty, true)});
1349
1350 }
1351
1352 }
1353
1354 }
1355
InjectCoverageAtBlock(Function & F,BasicBlock & BB,size_t Idx,bool IsLeafFunc)1356 void ModuleSanitizerCoverageAFL::InjectCoverageAtBlock(Function & F,
1357 BasicBlock &BB,
1358 size_t Idx,
1359 bool IsLeafFunc) {
1360
1361 BasicBlock::iterator IP = BB.getFirstInsertionPt();
1362 bool IsEntryBB = &BB == &F.getEntryBlock();
1363
1364 if (IsEntryBB) {
1365
1366 // Keep allocas and llvm.localescape calls in the entry block. Even
1367 // if we aren't splitting the block, it's nice for allocas to be before
1368 // calls.
1369 IP = PrepareToSplitEntryBlock(BB, IP);
1370
1371 }
1372
1373 IRBuilder<> IRB(&*IP);
1374
1375 if (Options.TracePC) {
1376
1377 IRB.CreateCall(SanCovTracePC);
1378 // ->setCannotMerge(); // gets the PC using GET_CALLER_PC.
1379
1380 }
1381
1382 if (Options.TracePCGuard) {
1383
1384 /* Get CurLoc */
1385
1386 Value *GuardPtr = IRB.CreateIntToPtr(
1387 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1388 ConstantInt::get(IntptrTy, Idx * 4)),
1389 Int32PtrTy);
1390
1391 LoadInst *CurLoc = IRB.CreateLoad(IRB.getInt32Ty(), GuardPtr);
1392 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(CurLoc);
1393
1394 /* Load SHM pointer */
1395
1396 LoadInst *MapPtr = IRB.CreateLoad(PointerType::get(Int8Ty, 0), AFLMapPtr);
1397 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(MapPtr);
1398
1399 /* Load counter for CurLoc */
1400
1401 Value *MapPtrIdx = IRB.CreateGEP(Int8Ty, MapPtr, CurLoc);
1402
1403 if (use_threadsafe_counters) {
1404
1405 IRB.CreateAtomicRMW(llvm::AtomicRMWInst::BinOp::Add, MapPtrIdx, One,
1406 #if LLVM_VERSION_MAJOR >= 13
1407 llvm::MaybeAlign(1),
1408 #endif
1409 llvm::AtomicOrdering::Monotonic);
1410
1411 } else {
1412
1413 LoadInst *Counter = IRB.CreateLoad(IRB.getInt8Ty(), MapPtrIdx);
1414 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(Counter);
1415
1416 /* Update bitmap */
1417
1418 Value *Incr = IRB.CreateAdd(Counter, One);
1419
1420 if (skip_nozero == NULL) {
1421
1422 auto cf = IRB.CreateICmpEQ(Incr, Zero);
1423 auto carry = IRB.CreateZExt(cf, Int8Ty);
1424 Incr = IRB.CreateAdd(Incr, carry);
1425
1426 }
1427
1428 StoreInst *StoreCtx = IRB.CreateStore(Incr, MapPtrIdx);
1429 ModuleSanitizerCoverageAFL::SetNoSanitizeMetadata(StoreCtx);
1430
1431 }
1432
1433 // done :)
1434
1435 // IRB.CreateCall(SanCovTracePCGuard, Offset)->setCannotMerge();
1436 // IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
1437 ++instr;
1438
1439 }
1440
1441 if (Options.Inline8bitCounters) {
1442
1443 auto CounterPtr = IRB.CreateGEP(
1444 Function8bitCounterArray->getValueType(), Function8bitCounterArray,
1445 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
1446 auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
1447 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
1448 auto Store = IRB.CreateStore(Inc, CounterPtr);
1449 SetNoSanitizeMetadata(Load);
1450 SetNoSanitizeMetadata(Store);
1451
1452 }
1453
1454 /*
1455 if (Options.InlineBoolFlag) {
1456
1457 auto FlagPtr = IRB.CreateGEP(
1458 FunctionBoolArray->getValueType(), FunctionBoolArray,
1459 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
1460 auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
1461 auto ThenTerm =
1462 SplitBlockAndInsertIfThen(IRB.CreateIsNull(Load), &*IP, false);
1463 IRBuilder<> ThenIRB(ThenTerm);
1464 auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
1465 SetNoSanitizeMetadata(Load);
1466 SetNoSanitizeMetadata(Store);
1467
1468 }
1469
1470 */
1471
1472 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
1473
1474 // Check stack depth. If it's the deepest so far, record it.
1475 Module * M = F.getParent();
1476 Function *GetFrameAddr = Intrinsic::getDeclaration(
1477 M, Intrinsic::frameaddress,
1478 IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
1479 auto FrameAddrPtr =
1480 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
1481 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
1482 auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
1483 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
1484 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
1485 IRBuilder<> ThenIRB(ThenTerm);
1486 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
1487 SetNoSanitizeMetadata(LowestStack);
1488 SetNoSanitizeMetadata(Store);
1489
1490 }
1491
1492 }
1493
getSectionName(const std::string & Section) const1494 std::string ModuleSanitizerCoverageAFL::getSectionName(
1495 const std::string &Section) const {
1496
1497 if (TargetTriple.isOSBinFormatCOFF()) {
1498
1499 if (Section == SanCovCountersSectionName) return ".SCOV$CM";
1500 if (Section == SanCovBoolFlagSectionName) return ".SCOV$BM";
1501 if (Section == SanCovPCsSectionName) return ".SCOVP$M";
1502 return ".SCOV$GM"; // For SanCovGuardsSectionName.
1503
1504 }
1505
1506 if (TargetTriple.isOSBinFormatMachO()) return "__DATA,__" + Section;
1507 return "__" + Section;
1508
1509 }
1510
getSectionStart(const std::string & Section) const1511 std::string ModuleSanitizerCoverageAFL::getSectionStart(
1512 const std::string &Section) const {
1513
1514 if (TargetTriple.isOSBinFormatMachO())
1515 return "\1section$start$__DATA$__" + Section;
1516 return "__start___" + Section;
1517
1518 }
1519
getSectionEnd(const std::string & Section) const1520 std::string ModuleSanitizerCoverageAFL::getSectionEnd(
1521 const std::string &Section) const {
1522
1523 if (TargetTriple.isOSBinFormatMachO())
1524 return "\1section$end$__DATA$__" + Section;
1525 return "__stop___" + Section;
1526
1527 }
1528
1529 #if 0
1530
1531 char ModuleSanitizerCoverageLegacyPass::ID = 0;
1532 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov",
1533 "Pass for instrumenting coverage on functions", false,
1534 false)
1535 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
1536 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
1537 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov",
1538 "Pass for instrumenting coverage on functions", false,
1539 false)
1540 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
1541 const SanitizerCoverageOptions &Options,
1542 const std::vector<std::string> &AllowlistFiles,
1543 const std::vector<std::string> &BlocklistFiles) {
1544
1545 return new ModuleSanitizerCoverageLegacyPass(Options, AllowlistFiles,
1546 BlocklistFiles);
1547
1548 }
1549
1550 #endif
1551
1552