1 //===- FileAnalysis.cpp -----------------------------------------*- C++ -*-===//
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 #include "FileAnalysis.h"
10 #include "GraphBuilder.h"
11 
12 #include "llvm/BinaryFormat/ELF.h"
13 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
14 #include "llvm/MC/MCAsmInfo.h"
15 #include "llvm/MC/MCContext.h"
16 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
17 #include "llvm/MC/MCInst.h"
18 #include "llvm/MC/MCInstPrinter.h"
19 #include "llvm/MC/MCInstrAnalysis.h"
20 #include "llvm/MC/MCInstrDesc.h"
21 #include "llvm/MC/MCInstrInfo.h"
22 #include "llvm/MC/MCObjectFileInfo.h"
23 #include "llvm/MC/MCRegisterInfo.h"
24 #include "llvm/MC/MCSubtargetInfo.h"
25 #include "llvm/MC/MCTargetOptions.h"
26 #include "llvm/Object/Binary.h"
27 #include "llvm/Object/COFF.h"
28 #include "llvm/Object/ELFObjectFile.h"
29 #include "llvm/Object/ObjectFile.h"
fdi<T: FromDeriveInput>(src: &str) -> Result<T>30 #include "llvm/Support/Casting.h"
31 #include "llvm/Support/CommandLine.h"
32 #include "llvm/Support/Error.h"
33 #include "llvm/Support/MemoryBuffer.h"
34 #include "llvm/Support/TargetRegistry.h"
35 #include "llvm/Support/TargetSelect.h"
36 #include "llvm/Support/raw_ostream.h"
37 
38 
39 using Instr = llvm::cfi_verify::FileAnalysis::Instr;
40 using LLVMSymbolizer = llvm::symbolize::LLVMSymbolizer;
41 
42 namespace llvm {
expand_some()43 namespace cfi_verify {
44 
45 bool IgnoreDWARFFlag;
46 
47 static cl::opt<bool, true> IgnoreDWARFArg(
48     "ignore-dwarf",
49     cl::desc(
50         "Ignore all DWARF data. This relaxes the requirements for all "
51         "statically linked libraries to have been compiled with '-g', but "
52         "will result in false positives for 'CFI unprotected' instructions."),
53     cl::location(IgnoreDWARFFlag), cl::init(false));
54 
55 StringRef stringCFIProtectionStatus(CFIProtectionStatus Status) {
56   switch (Status) {
57   case CFIProtectionStatus::PROTECTED:
58     return "PROTECTED";
59   case CFIProtectionStatus::FAIL_NOT_INDIRECT_CF:
60     return "FAIL_NOT_INDIRECT_CF";
61   case CFIProtectionStatus::FAIL_ORPHANS:
62     return "FAIL_ORPHANS";
63   case CFIProtectionStatus::FAIL_BAD_CONDITIONAL_BRANCH:
64     return "FAIL_BAD_CONDITIONAL_BRANCH";
65   case CFIProtectionStatus::FAIL_REGISTER_CLOBBERED:
66     return "FAIL_REGISTER_CLOBBERED";
67   case CFIProtectionStatus::FAIL_INVALID_INSTRUCTION:
68     return "FAIL_INVALID_INSTRUCTION";
69   }
70   llvm_unreachable("Attempted to stringify an unknown enum value.");
71 }
72 
73 Expected<FileAnalysis> FileAnalysis::Create(StringRef Filename) {
74   // Open the filename provided.
75   Expected<object::OwningBinary<object::Binary>> BinaryOrErr =
76       object::createBinary(Filename);
77   if (!BinaryOrErr)
78     return BinaryOrErr.takeError();
79 
80   // Construct the object and allow it to take ownership of the binary.
81   object::OwningBinary<object::Binary> Binary = std::move(BinaryOrErr.get());
82   FileAnalysis Analysis(std::move(Binary));
83 
84   Analysis.Object = dyn_cast<object::ObjectFile>(Analysis.Binary.getBinary());
85   if (!Analysis.Object)
86     return make_error<UnsupportedDisassembly>("Failed to cast object");
87 
88   switch (Analysis.Object->getArch()) {
89     case Triple::x86:
90     case Triple::x86_64:
91     case Triple::aarch64:
92     case Triple::aarch64_be:
93       break;
94     default:
95       return make_error<UnsupportedDisassembly>("Unsupported architecture.");
96   }
97 
98   Analysis.ObjectTriple = Analysis.Object->makeTriple();
99   Analysis.Features = Analysis.Object->getFeatures();
100 
101   // Init the rest of the object.
102   if (auto InitResponse = Analysis.initialiseDisassemblyMembers())
103     return std::move(InitResponse);
104 
105   if (auto SectionParseResponse = Analysis.parseCodeSections())
106     return std::move(SectionParseResponse);
107 
108   if (auto SymbolTableParseResponse = Analysis.parseSymbolTable())
109     return std::move(SymbolTableParseResponse);
110 
111   return std::move(Analysis);
112 }
113 
114 FileAnalysis::FileAnalysis(object::OwningBinary<object::Binary> Binary)
115     : Binary(std::move(Binary)) {}
116 
117 FileAnalysis::FileAnalysis(const Triple &ObjectTriple,
118                            const SubtargetFeatures &Features)
119     : ObjectTriple(ObjectTriple), Features(Features) {}
120 
121 const Instr *
122 FileAnalysis::getPrevInstructionSequential(const Instr &InstrMeta) const {
123   std::map<uint64_t, Instr>::const_iterator KV =
124       Instructions.find(InstrMeta.VMAddress);
125   if (KV == Instructions.end() || KV == Instructions.begin())
126     return nullptr;
127 
128   if (!(--KV)->second.Valid)
129     return nullptr;
130 
131   return &KV->second;
132 }
133 
134 const Instr *
135 FileAnalysis::getNextInstructionSequential(const Instr &InstrMeta) const {
136   std::map<uint64_t, Instr>::const_iterator KV =
137       Instructions.find(InstrMeta.VMAddress);
138   if (KV == Instructions.end() || ++KV == Instructions.end())
139     return nullptr;
140 
141   if (!KV->second.Valid)
142     return nullptr;
143 
144   return &KV->second;
145 }
146 
147 bool FileAnalysis::usesRegisterOperand(const Instr &InstrMeta) const {
148   for (const auto &Operand : InstrMeta.Instruction) {
149     if (Operand.isReg())
150       return true;
151   }
152   return false;
153 }
154 
155 const Instr *FileAnalysis::getInstruction(uint64_t Address) const {
156   const auto &InstrKV = Instructions.find(Address);
157   if (InstrKV == Instructions.end())
158     return nullptr;
159 
160   return &InstrKV->second;
161 }
162 
163 const Instr &FileAnalysis::getInstructionOrDie(uint64_t Address) const {
164   const auto &InstrKV = Instructions.find(Address);
165   assert(InstrKV != Instructions.end() && "Address doesn't exist.");
166   return InstrKV->second;
167 }
168 
169 bool FileAnalysis::isCFITrap(const Instr &InstrMeta) const {
170   const auto &InstrDesc = MII->get(InstrMeta.Instruction.getOpcode());
171   return InstrDesc.isTrap() || willTrapOnCFIViolation(InstrMeta);
172 }
173 
174 bool FileAnalysis::willTrapOnCFIViolation(const Instr &InstrMeta) const {
175   const auto &InstrDesc = MII->get(InstrMeta.Instruction.getOpcode());
176   if (!InstrDesc.isCall())
177     return false;
178   uint64_t Target;
179   if (!MIA->evaluateBranch(InstrMeta.Instruction, InstrMeta.VMAddress,
180                            InstrMeta.InstructionSize, Target))
181     return false;
182   return TrapOnFailFunctionAddresses.contains(Target);
183 }
184 
185 bool FileAnalysis::canFallThrough(const Instr &InstrMeta) const {
186   if (!InstrMeta.Valid)
187     return false;
188 
189   if (isCFITrap(InstrMeta))
190     return false;
191 
192   const auto &InstrDesc = MII->get(InstrMeta.Instruction.getOpcode());
193   if (InstrDesc.mayAffectControlFlow(InstrMeta.Instruction, *RegisterInfo))
194     return InstrDesc.isConditionalBranch();
195 
196   return true;
197 }
198 
199 const Instr *
200 FileAnalysis::getDefiniteNextInstruction(const Instr &InstrMeta) const {
201   if (!InstrMeta.Valid)
202     return nullptr;
203 
204   if (isCFITrap(InstrMeta))
205     return nullptr;
206 
207   const auto &InstrDesc = MII->get(InstrMeta.Instruction.getOpcode());
208   const Instr *NextMetaPtr;
209   if (InstrDesc.mayAffectControlFlow(InstrMeta.Instruction, *RegisterInfo)) {
210     if (InstrDesc.isConditionalBranch())
211       return nullptr;
212 
213     uint64_t Target;
214     if (!MIA->evaluateBranch(InstrMeta.Instruction, InstrMeta.VMAddress,
215                              InstrMeta.InstructionSize, Target))
216       return nullptr;
217 
218     NextMetaPtr = getInstruction(Target);
219   } else {
220     NextMetaPtr =
221         getInstruction(InstrMeta.VMAddress + InstrMeta.InstructionSize);
222   }
223 
224   if (!NextMetaPtr || !NextMetaPtr->Valid)
225     return nullptr;
226 
227   return NextMetaPtr;
228 }
229 
230 std::set<const Instr *>
231 FileAnalysis::getDirectControlFlowXRefs(const Instr &InstrMeta) const {
232   std::set<const Instr *> CFCrossReferences;
233   const Instr *PrevInstruction = getPrevInstructionSequential(InstrMeta);
234 
235   if (PrevInstruction && canFallThrough(*PrevInstruction))
236     CFCrossReferences.insert(PrevInstruction);
237 
238   const auto &TargetRefsKV = StaticBranchTargetings.find(InstrMeta.VMAddress);
239   if (TargetRefsKV == StaticBranchTargetings.end())
240     return CFCrossReferences;
241 
242   for (uint64_t SourceInstrAddress : TargetRefsKV->second) {
243     const auto &SourceInstrKV = Instructions.find(SourceInstrAddress);
244     if (SourceInstrKV == Instructions.end()) {
245       errs() << "Failed to find source instruction at address "
246              << format_hex(SourceInstrAddress, 2)
247              << " for the cross-reference to instruction at address "
248              << format_hex(InstrMeta.VMAddress, 2) << ".\n";
249       continue;
250     }
251 
252     CFCrossReferences.insert(&SourceInstrKV->second);
253   }
254 
255   return CFCrossReferences;
256 }
257 
258 const std::set<object::SectionedAddress> &
259 FileAnalysis::getIndirectInstructions() const {
260   return IndirectInstructions;
261 }
262 
263 const MCRegisterInfo *FileAnalysis::getRegisterInfo() const {
264   return RegisterInfo.get();
265 }
266 
267 const MCInstrInfo *FileAnalysis::getMCInstrInfo() const { return MII.get(); }
268 
269 const MCInstrAnalysis *FileAnalysis::getMCInstrAnalysis() const {
270   return MIA.get();
271 }
272 
273 Expected<DIInliningInfo>
274 FileAnalysis::symbolizeInlinedCode(object::SectionedAddress Address) {
275   assert(Symbolizer != nullptr && "Symbolizer is invalid.");
276 
277   return Symbolizer->symbolizeInlinedCode(std::string(Object->getFileName()),
278                                           Address);
279 }
280 
281 CFIProtectionStatus
282 FileAnalysis::validateCFIProtection(const GraphResult &Graph) const {
283   const Instr *InstrMetaPtr = getInstruction(Graph.BaseAddress);
284   if (!InstrMetaPtr)
285     return CFIProtectionStatus::FAIL_INVALID_INSTRUCTION;
286 
287   const auto &InstrDesc = MII->get(InstrMetaPtr->Instruction.getOpcode());
288   if (!InstrDesc.mayAffectControlFlow(InstrMetaPtr->Instruction, *RegisterInfo))
289     return CFIProtectionStatus::FAIL_NOT_INDIRECT_CF;
290 
291   if (!usesRegisterOperand(*InstrMetaPtr))
292     return CFIProtectionStatus::FAIL_NOT_INDIRECT_CF;
293 
294   if (!Graph.OrphanedNodes.empty())
295     return CFIProtectionStatus::FAIL_ORPHANS;
296 
297   for (const auto &BranchNode : Graph.ConditionalBranchNodes) {
298     if (!BranchNode.CFIProtection)
299       return CFIProtectionStatus::FAIL_BAD_CONDITIONAL_BRANCH;
300   }
301 
302   if (indirectCFOperandClobber(Graph) != Graph.BaseAddress)
303     return CFIProtectionStatus::FAIL_REGISTER_CLOBBERED;
304 
305   return CFIProtectionStatus::PROTECTED;
306 }
307 
308 uint64_t FileAnalysis::indirectCFOperandClobber(const GraphResult &Graph) const {
309   assert(Graph.OrphanedNodes.empty() && "Orphaned nodes should be empty.");
310 
311   // Get the set of registers we must check to ensure they're not clobbered.
312   const Instr &IndirectCF = getInstructionOrDie(Graph.BaseAddress);
313   DenseSet<unsigned> RegisterNumbers;
314   for (const auto &Operand : IndirectCF.Instruction) {
315     if (Operand.isReg())
316       RegisterNumbers.insert(Operand.getReg());
317   }
318   assert(RegisterNumbers.size() && "Zero register operands on indirect CF.");
319 
320   // Now check all branches to indirect CFs and ensure no clobbering happens.
321   for (const auto &Branch : Graph.ConditionalBranchNodes) {
322     uint64_t Node;
323     if (Branch.IndirectCFIsOnTargetPath)
324       Node = Branch.Target;
325     else
326       Node = Branch.Fallthrough;
327 
328     // Some architectures (e.g., AArch64) cannot load in an indirect branch, so
329     // we allow them one load.
330     bool canLoad = !MII->get(IndirectCF.Instruction.getOpcode()).mayLoad();
331 
332     // We walk backwards from the indirect CF.  It is the last node returned by
333     // Graph.flattenAddress, so we skip it since we already handled it.
334     DenseSet<unsigned> CurRegisterNumbers = RegisterNumbers;
335     std::vector<uint64_t> Nodes = Graph.flattenAddress(Node);
336     for (auto I = Nodes.rbegin() + 1, E = Nodes.rend(); I != E; ++I) {
337       Node = *I;
338       const Instr &NodeInstr = getInstructionOrDie(Node);
339       const auto &InstrDesc = MII->get(NodeInstr.Instruction.getOpcode());
340 
341       for (auto RI = CurRegisterNumbers.begin(), RE = CurRegisterNumbers.end();
342            RI != RE; ++RI) {
343         unsigned RegNum = *RI;
344         if (InstrDesc.hasDefOfPhysReg(NodeInstr.Instruction, RegNum,
345                                       *RegisterInfo)) {
346           if (!canLoad || !InstrDesc.mayLoad())
347             return Node;
348           canLoad = false;
349           CurRegisterNumbers.erase(RI);
350           // Add the registers this load reads to those we check for clobbers.
351           for (unsigned i = InstrDesc.getNumDefs(),
352                         e = InstrDesc.getNumOperands(); i != e; i++) {
353             const auto Operand = NodeInstr.Instruction.getOperand(i);
354             if (Operand.isReg())
355               CurRegisterNumbers.insert(Operand.getReg());
356           }
357           break;
358         }
359       }
360     }
361   }
362 
363   return Graph.BaseAddress;
364 }
365 
366 void FileAnalysis::printInstruction(const Instr &InstrMeta,
367                                     raw_ostream &OS) const {
368   Printer->printInst(&InstrMeta.Instruction, 0, "", *SubtargetInfo.get(), OS);
369 }
370 
371 Error FileAnalysis::initialiseDisassemblyMembers() {
372   std::string TripleName = ObjectTriple.getTriple();
373   ArchName = "";
374   MCPU = "";
375   std::string ErrorString;
376 
377   LLVMSymbolizer::Options Opt;
378   Opt.UseSymbolTable = false;
379   Symbolizer.reset(new LLVMSymbolizer(Opt));
380 
381   ObjectTarget =
382       TargetRegistry::lookupTarget(ArchName, ObjectTriple, ErrorString);
383   if (!ObjectTarget)
384     return make_error<UnsupportedDisassembly>(
385         (Twine("Couldn't find target \"") + ObjectTriple.getTriple() +
386          "\", failed with error: " + ErrorString)
387             .str());
388 
389   RegisterInfo.reset(ObjectTarget->createMCRegInfo(TripleName));
390   if (!RegisterInfo)
391     return make_error<UnsupportedDisassembly>(
392         "Failed to initialise RegisterInfo.");
393 
394   MCTargetOptions MCOptions;
395   AsmInfo.reset(
396       ObjectTarget->createMCAsmInfo(*RegisterInfo, TripleName, MCOptions));
397   if (!AsmInfo)
398     return make_error<UnsupportedDisassembly>("Failed to initialise AsmInfo.");
399 
400   SubtargetInfo.reset(ObjectTarget->createMCSubtargetInfo(
401       TripleName, MCPU, Features.getString()));
402   if (!SubtargetInfo)
403     return make_error<UnsupportedDisassembly>(
404         "Failed to initialise SubtargetInfo.");
405 
406   MII.reset(ObjectTarget->createMCInstrInfo());
407   if (!MII)
408     return make_error<UnsupportedDisassembly>("Failed to initialise MII.");
409 
410   Context.reset(new MCContext(Triple(TripleName), AsmInfo.get(),
411                               RegisterInfo.get(), SubtargetInfo.get()));
412 
413   Disassembler.reset(
414       ObjectTarget->createMCDisassembler(*SubtargetInfo, *Context));
415 
416   if (!Disassembler)
417     return make_error<UnsupportedDisassembly>(
418         "No disassembler available for target");
419 
420   MIA.reset(ObjectTarget->createMCInstrAnalysis(MII.get()));
421 
422   Printer.reset(ObjectTarget->createMCInstPrinter(
423       ObjectTriple, AsmInfo->getAssemblerDialect(), *AsmInfo, *MII,
424       *RegisterInfo));
425 
426   return Error::success();
427 }
428 
429 Error FileAnalysis::parseCodeSections() {
430   if (!IgnoreDWARFFlag) {
431     std::unique_ptr<DWARFContext> DWARF = DWARFContext::create(*Object);
432     if (!DWARF)
433       return make_error<StringError>("Could not create DWARF information.",
434                                      inconvertibleErrorCode());
435 
436     bool LineInfoValid = false;
437 
438     for (auto &Unit : DWARF->compile_units()) {
439       const auto &LineTable = DWARF->getLineTableForUnit(Unit.get());
440       if (LineTable && !LineTable->Rows.empty()) {
441         LineInfoValid = true;
442         break;
443       }
444     }
445 
446     if (!LineInfoValid)
447       return make_error<StringError>(
448           "DWARF line information missing. Did you compile with '-g'?",
449           inconvertibleErrorCode());
450   }
451 
452   for (const object::SectionRef &Section : Object->sections()) {
453     // Ensure only executable sections get analysed.
454     if (!(object::ELFSectionRef(Section).getFlags() & ELF::SHF_EXECINSTR))
455       continue;
456 
457     // Avoid checking the PLT since it produces spurious failures on AArch64
458     // when ignoring DWARF data.
459     Expected<StringRef> NameOrErr = Section.getName();
460     if (NameOrErr && *NameOrErr == ".plt")
461       continue;
462     consumeError(NameOrErr.takeError());
463 
464     Expected<StringRef> Contents = Section.getContents();
465     if (!Contents)
466       return Contents.takeError();
467     ArrayRef<uint8_t> SectionBytes = arrayRefFromStringRef(*Contents);
468 
469     parseSectionContents(SectionBytes,
470                          {Section.getAddress(), Section.getIndex()});
471   }
472   return Error::success();
473 }
474 
475 void FileAnalysis::parseSectionContents(ArrayRef<uint8_t> SectionBytes,
476                                         object::SectionedAddress Address) {
477   assert(Symbolizer && "Symbolizer is uninitialised.");
478   MCInst Instruction;
479   Instr InstrMeta;
480   uint64_t InstructionSize;
481 
482   for (uint64_t Byte = 0; Byte < SectionBytes.size();) {
483     bool ValidInstruction =
484         Disassembler->getInstruction(Instruction, InstructionSize,
485                                      SectionBytes.drop_front(Byte), 0,
486                                      outs()) == MCDisassembler::Success;
487 
488     Byte += InstructionSize;
489 
490     uint64_t VMAddress = Address.Address + Byte - InstructionSize;
491     InstrMeta.Instruction = Instruction;
492     InstrMeta.VMAddress = VMAddress;
493     InstrMeta.InstructionSize = InstructionSize;
494     InstrMeta.Valid = ValidInstruction;
495 
496     addInstruction(InstrMeta);
497 
498     if (!ValidInstruction)
499       continue;
500 
501     // Skip additional parsing for instructions that do not affect the control
502     // flow.
503     const auto &InstrDesc = MII->get(Instruction.getOpcode());
504     if (!InstrDesc.mayAffectControlFlow(Instruction, *RegisterInfo))
505       continue;
506 
507     uint64_t Target;
508     if (MIA->evaluateBranch(Instruction, VMAddress, InstructionSize, Target)) {
509       // If the target can be evaluated, it's not indirect.
510       StaticBranchTargetings[Target].push_back(VMAddress);
511       continue;
512     }
513 
514     if (!usesRegisterOperand(InstrMeta))
515       continue;
516 
517     if (InstrDesc.isReturn())
518       continue;
519 
520     // Check if this instruction exists in the range of the DWARF metadata.
521     if (!IgnoreDWARFFlag) {
522       auto LineInfo =
523           Symbolizer->symbolizeCode(std::string(Object->getFileName()),
524                                     {VMAddress, Address.SectionIndex});
525       if (!LineInfo) {
526         handleAllErrors(LineInfo.takeError(), [](const ErrorInfoBase &E) {
527           errs() << "Symbolizer failed to get line: " << E.message() << "\n";
528         });
529         continue;
530       }
531 
532       if (LineInfo->FileName == DILineInfo::BadString)
533         continue;
534     }
535 
536     IndirectInstructions.insert({VMAddress, Address.SectionIndex});
537   }
538 }
539 
540 void FileAnalysis::addInstruction(const Instr &Instruction) {
541   const auto &KV =
542       Instructions.insert(std::make_pair(Instruction.VMAddress, Instruction));
543   if (!KV.second) {
544     errs() << "Failed to add instruction at address "
545            << format_hex(Instruction.VMAddress, 2)
546            << ": Instruction at this address already exists.\n";
547     exit(EXIT_FAILURE);
548   }
549 }
550 
551 Error FileAnalysis::parseSymbolTable() {
552   // Functions that will trap on CFI violations.
553   SmallSet<StringRef, 4> TrapOnFailFunctions;
554   TrapOnFailFunctions.insert("__cfi_slowpath");
555   TrapOnFailFunctions.insert("__cfi_slowpath_diag");
556   TrapOnFailFunctions.insert("abort");
557 
558   // Look through the list of symbols for functions that will trap on CFI
559   // violations.
560   for (auto &Sym : Object->symbols()) {
561     auto SymNameOrErr = Sym.getName();
562     if (!SymNameOrErr)
563       consumeError(SymNameOrErr.takeError());
564     else if (TrapOnFailFunctions.contains(*SymNameOrErr)) {
565       auto AddrOrErr = Sym.getAddress();
566       if (!AddrOrErr)
567         consumeError(AddrOrErr.takeError());
568       else
569         TrapOnFailFunctionAddresses.insert(*AddrOrErr);
570     }
571   }
572   if (auto *ElfObject = dyn_cast<object::ELFObjectFileBase>(Object)) {
573     for (const auto &Addr : ElfObject->getPltAddresses()) {
574       if (!Addr.first)
575         continue;
576       object::SymbolRef Sym(*Addr.first, Object);
577       auto SymNameOrErr = Sym.getName();
578       if (!SymNameOrErr)
579         consumeError(SymNameOrErr.takeError());
580       else if (TrapOnFailFunctions.contains(*SymNameOrErr))
581         TrapOnFailFunctionAddresses.insert(Addr.second);
582     }
583   }
584   return Error::success();
585 }
586 
587 UnsupportedDisassembly::UnsupportedDisassembly(StringRef Text)
588     : Text(std::string(Text)) {}
589 
590 char UnsupportedDisassembly::ID;
591 void UnsupportedDisassembly::log(raw_ostream &OS) const {
592   OS << "Could not initialise disassembler: " << Text;
593 }
594 
595 std::error_code UnsupportedDisassembly::convertToErrorCode() const {
596   return std::error_code();
597 }
598 
599 } // namespace cfi_verify
600 } // namespace llvm
601