1 //===- InstrumentationMap.cpp - XRay Instrumentation Map ------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Implementation of the InstrumentationMap type for XRay sleds. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/XRay/InstrumentationMap.h" 15 #include "llvm/ADT/DenseMap.h" 16 #include "llvm/ADT/None.h" 17 #include "llvm/ADT/STLExtras.h" 18 #include "llvm/ADT/StringRef.h" 19 #include "llvm/ADT/Triple.h" 20 #include "llvm/ADT/Twine.h" 21 #include "llvm/Object/Binary.h" 22 #include "llvm/Object/ELFObjectFile.h" 23 #include "llvm/Object/ObjectFile.h" 24 #include "llvm/Support/DataExtractor.h" 25 #include "llvm/Support/Error.h" 26 #include "llvm/Support/FileSystem.h" 27 #include "llvm/Support/YAMLTraits.h" 28 #include <algorithm> 29 #include <cstddef> 30 #include <cstdint> 31 #include <system_error> 32 #include <vector> 33 34 using namespace llvm; 35 using namespace xray; 36 37 Optional<int32_t> InstrumentationMap::getFunctionId(uint64_t Addr) const { 38 auto I = FunctionIds.find(Addr); 39 if (I != FunctionIds.end()) 40 return I->second; 41 return None; 42 } 43 44 Optional<uint64_t> InstrumentationMap::getFunctionAddr(int32_t FuncId) const { 45 auto I = FunctionAddresses.find(FuncId); 46 if (I != FunctionAddresses.end()) 47 return I->second; 48 return None; 49 } 50 51 using RelocMap = DenseMap<uint64_t, uint64_t>; 52 53 static Error 54 loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile, 55 InstrumentationMap::SledContainer &Sleds, 56 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 57 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 58 InstrumentationMap Map; 59 60 // Find the section named "xray_instr_map". 61 if ((!ObjFile.getBinary()->isELF() && !ObjFile.getBinary()->isMachO()) || 62 !(ObjFile.getBinary()->getArch() == Triple::x86_64 || 63 ObjFile.getBinary()->getArch() == Triple::ppc64le)) 64 return make_error<StringError>( 65 "File format not supported (only does ELF and Mach-O little endian 64-bit).", 66 std::make_error_code(std::errc::not_supported)); 67 68 StringRef Contents = ""; 69 const auto &Sections = ObjFile.getBinary()->sections(); 70 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) { 71 StringRef Name = ""; 72 if (Section.getName(Name)) 73 return false; 74 return Name == "xray_instr_map"; 75 }); 76 77 if (I == Sections.end()) 78 return make_error<StringError>( 79 "Failed to find XRay instrumentation map.", 80 std::make_error_code(std::errc::executable_format_error)); 81 82 if (I->getContents(Contents)) 83 return errorCodeToError( 84 std::make_error_code(std::errc::executable_format_error)); 85 86 RelocMap Relocs; 87 if (ObjFile.getBinary()->isELF()) { 88 uint32_t RelrRelocationType = [](object::ObjectFile *ObjFile) { 89 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile)) 90 return ELFObj->getELFFile()->getRelrRelocationType(); 91 else if (const auto *ELFObj = dyn_cast<object::ELF32BEObjectFile>(ObjFile)) 92 return ELFObj->getELFFile()->getRelrRelocationType(); 93 else if (const auto *ELFObj = dyn_cast<object::ELF64LEObjectFile>(ObjFile)) 94 return ELFObj->getELFFile()->getRelrRelocationType(); 95 else if (const auto *ELFObj = dyn_cast<object::ELF64BEObjectFile>(ObjFile)) 96 return ELFObj->getELFFile()->getRelrRelocationType(); 97 else 98 return static_cast<uint32_t>(0); 99 }(ObjFile.getBinary()); 100 101 for (const object::SectionRef &Section : Sections) { 102 for (const object::RelocationRef &Reloc : Section.relocations()) { 103 if (Reloc.getType() != RelrRelocationType) 104 continue; 105 if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend()) 106 Relocs.insert({Reloc.getOffset(), *AddendOrErr}); 107 } 108 } 109 } 110 111 // Copy the instrumentation map data into the Sleds data structure. 112 auto C = Contents.bytes_begin(); 113 static constexpr size_t ELF64SledEntrySize = 32; 114 115 if ((C - Contents.bytes_end()) % ELF64SledEntrySize != 0) 116 return make_error<StringError>( 117 Twine("Instrumentation map entries not evenly divisible by size of " 118 "an XRay sled entry in ELF64."), 119 std::make_error_code(std::errc::executable_format_error)); 120 121 auto RelocateOrElse = [&](uint32_t Offset, uint64_t Address) { 122 if (!Address) { 123 uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset; 124 RelocMap::const_iterator R = Relocs.find(A); 125 if (R != Relocs.end()) 126 return R->second; 127 } 128 return Address; 129 }; 130 131 int32_t FuncId = 1; 132 uint64_t CurFn = 0; 133 for (; C != Contents.bytes_end(); C += ELF64SledEntrySize) { 134 DataExtractor Extractor( 135 StringRef(reinterpret_cast<const char *>(C), ELF64SledEntrySize), true, 136 8); 137 Sleds.push_back({}); 138 auto &Entry = Sleds.back(); 139 uint32_t OffsetPtr = 0; 140 Entry.Address = RelocateOrElse(OffsetPtr, Extractor.getU64(&OffsetPtr)); 141 Entry.Function = RelocateOrElse(OffsetPtr, Extractor.getU64(&OffsetPtr)); 142 auto Kind = Extractor.getU8(&OffsetPtr); 143 static constexpr SledEntry::FunctionKinds Kinds[] = { 144 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT, 145 SledEntry::FunctionKinds::TAIL, 146 SledEntry::FunctionKinds::LOG_ARGS_ENTER, 147 SledEntry::FunctionKinds::CUSTOM_EVENT}; 148 if (Kind >= sizeof(Kinds)) 149 return errorCodeToError( 150 std::make_error_code(std::errc::executable_format_error)); 151 Entry.Kind = Kinds[Kind]; 152 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0; 153 154 // We do replicate the function id generation scheme implemented in the 155 // XRay runtime. 156 // FIXME: Figure out how to keep this consistent with the XRay runtime. 157 if (CurFn == 0) { 158 CurFn = Entry.Function; 159 FunctionAddresses[FuncId] = Entry.Function; 160 FunctionIds[Entry.Function] = FuncId; 161 } 162 if (Entry.Function != CurFn) { 163 ++FuncId; 164 CurFn = Entry.Function; 165 FunctionAddresses[FuncId] = Entry.Function; 166 FunctionIds[Entry.Function] = FuncId; 167 } 168 } 169 return Error::success(); 170 } 171 172 static Error 173 loadYAML(int Fd, size_t FileSize, StringRef Filename, 174 InstrumentationMap::SledContainer &Sleds, 175 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 176 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 177 std::error_code EC; 178 sys::fs::mapped_file_region MappedFile( 179 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC); 180 if (EC) 181 return make_error<StringError>( 182 Twine("Failed memory-mapping file '") + Filename + "'.", EC); 183 184 std::vector<YAMLXRaySledEntry> YAMLSleds; 185 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size())); 186 In >> YAMLSleds; 187 if (In.error()) 188 return make_error<StringError>( 189 Twine("Failed loading YAML document from '") + Filename + "'.", 190 In.error()); 191 192 Sleds.reserve(YAMLSleds.size()); 193 for (const auto &Y : YAMLSleds) { 194 FunctionAddresses[Y.FuncId] = Y.Function; 195 FunctionIds[Y.Function] = Y.FuncId; 196 Sleds.push_back( 197 SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument}); 198 } 199 return Error::success(); 200 } 201 202 // FIXME: Create error types that encapsulate a bit more information than what 203 // StringError instances contain. 204 Expected<InstrumentationMap> 205 llvm::xray::loadInstrumentationMap(StringRef Filename) { 206 // At this point we assume the file is an object file -- and if that doesn't 207 // work, we treat it as YAML. 208 // FIXME: Extend to support non-ELF and non-x86_64 binaries. 209 210 InstrumentationMap Map; 211 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename); 212 if (!ObjectFileOrError) { 213 auto E = ObjectFileOrError.takeError(); 214 // We try to load it as YAML if the ELF load didn't work. 215 int Fd; 216 if (sys::fs::openFileForRead(Filename, Fd)) 217 return std::move(E); 218 219 uint64_t FileSize; 220 if (sys::fs::file_size(Filename, FileSize)) 221 return std::move(E); 222 223 // If the file is empty, we return the original error. 224 if (FileSize == 0) 225 return std::move(E); 226 227 // From this point on the errors will be only for the YAML parts, so we 228 // consume the errors at this point. 229 consumeError(std::move(E)); 230 if (auto E = loadYAML(Fd, FileSize, Filename, Map.Sleds, 231 Map.FunctionAddresses, Map.FunctionIds)) 232 return std::move(E); 233 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds, 234 Map.FunctionAddresses, Map.FunctionIds)) { 235 return std::move(E); 236 } 237 return Map; 238 } 239