1 //===- InstrumentationMap.cpp - XRay Instrumentation Map ------------------===// 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 // Implementation of the InstrumentationMap type for XRay sleds. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/XRay/InstrumentationMap.h" 14 #include "llvm/ADT/DenseMap.h" 15 #include "llvm/ADT/None.h" 16 #include "llvm/ADT/STLExtras.h" 17 #include "llvm/ADT/StringRef.h" 18 #include "llvm/ADT/Triple.h" 19 #include "llvm/ADT/Twine.h" 20 #include "llvm/Object/Binary.h" 21 #include "llvm/Object/ELFObjectFile.h" 22 #include "llvm/Object/ObjectFile.h" 23 #include "llvm/Object/RelocationResolver.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 ObjFile.getBinary()->getArch() == Triple::arm || 65 ObjFile.getBinary()->getArch() == Triple::aarch64)) 66 return make_error<StringError>( 67 "File format not supported (only does ELF and Mach-O little endian " 68 "64-bit).", 69 std::make_error_code(std::errc::not_supported)); 70 71 StringRef Contents = ""; 72 const auto &Sections = ObjFile.getBinary()->sections(); 73 uint64_t Address = 0; 74 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) { 75 Expected<StringRef> NameOrErr = Section.getName(); 76 if (NameOrErr) { 77 Address = Section.getAddress(); 78 return *NameOrErr == "xray_instr_map"; 79 } 80 consumeError(NameOrErr.takeError()); 81 return false; 82 }); 83 84 if (I == Sections.end()) 85 return make_error<StringError>( 86 "Failed to find XRay instrumentation map.", 87 std::make_error_code(std::errc::executable_format_error)); 88 89 if (Expected<StringRef> E = I->getContents()) 90 Contents = *E; 91 else 92 return E.takeError(); 93 94 RelocMap Relocs; 95 if (ObjFile.getBinary()->isELF()) { 96 uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) { 97 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile)) 98 return ELFObj->getELFFile().getRelativeRelocationType(); 99 else if (const auto *ELFObj = 100 dyn_cast<object::ELF32BEObjectFile>(ObjFile)) 101 return ELFObj->getELFFile().getRelativeRelocationType(); 102 else if (const auto *ELFObj = 103 dyn_cast<object::ELF64LEObjectFile>(ObjFile)) 104 return ELFObj->getELFFile().getRelativeRelocationType(); 105 else if (const auto *ELFObj = 106 dyn_cast<object::ELF64BEObjectFile>(ObjFile)) 107 return ELFObj->getELFFile().getRelativeRelocationType(); 108 else 109 return static_cast<uint32_t>(0); 110 }(ObjFile.getBinary()); 111 112 object::SupportsRelocation Supports; 113 object::RelocationResolver Resolver; 114 std::tie(Supports, Resolver) = 115 object::getRelocationResolver(*ObjFile.getBinary()); 116 117 for (const object::SectionRef &Section : Sections) { 118 for (const object::RelocationRef &Reloc : Section.relocations()) { 119 if (ObjFile.getBinary()->getArch() == Triple::arm) { 120 if (Supports && Supports(Reloc.getType())) { 121 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 122 if (!ValueOrErr) 123 return ValueOrErr.takeError(); 124 Relocs.insert( 125 {Reloc.getOffset(), 126 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, 0)}); 127 } 128 } else if (Supports && Supports(Reloc.getType())) { 129 auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend(); 130 auto A = AddendOrErr ? *AddendOrErr : 0; 131 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 132 if (!ValueOrErr) 133 // TODO: Test this error. 134 return ValueOrErr.takeError(); 135 Relocs.insert( 136 {Reloc.getOffset(), 137 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, A)}); 138 } else if (Reloc.getType() == RelativeRelocation) { 139 if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend()) 140 Relocs.insert({Reloc.getOffset(), *AddendOrErr}); 141 } 142 } 143 } 144 } 145 146 // Copy the instrumentation map data into the Sleds data structure. 147 auto C = Contents.bytes_begin(); 148 bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit(); 149 size_t ELFSledEntrySize = Is32Bit ? 16 : 32; 150 151 if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0) 152 return make_error<StringError>( 153 Twine("Instrumentation map entries not evenly divisible by size of " 154 "an XRay sled entry."), 155 std::make_error_code(std::errc::executable_format_error)); 156 157 auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) { 158 if (!Address) { 159 uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset; 160 RelocMap::const_iterator R = Relocs.find(A); 161 if (R != Relocs.end()) 162 return R->second; 163 } 164 return Address; 165 }; 166 167 const int WordSize = Is32Bit ? 4 : 8; 168 int32_t FuncId = 1; 169 uint64_t CurFn = 0; 170 for (; C != Contents.bytes_end(); C += ELFSledEntrySize) { 171 DataExtractor Extractor( 172 StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true, 173 8); 174 Sleds.push_back({}); 175 auto &Entry = Sleds.back(); 176 uint64_t OffsetPtr = 0; 177 uint64_t AddrOff = OffsetPtr; 178 if (Is32Bit) 179 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr)); 180 else 181 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr)); 182 uint64_t FuncOff = OffsetPtr; 183 if (Is32Bit) 184 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr)); 185 else 186 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr)); 187 auto Kind = Extractor.getU8(&OffsetPtr); 188 static constexpr SledEntry::FunctionKinds Kinds[] = { 189 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT, 190 SledEntry::FunctionKinds::TAIL, 191 SledEntry::FunctionKinds::LOG_ARGS_ENTER, 192 SledEntry::FunctionKinds::CUSTOM_EVENT}; 193 if (Kind >= sizeof(Kinds)) 194 return errorCodeToError( 195 std::make_error_code(std::errc::executable_format_error)); 196 Entry.Kind = Kinds[Kind]; 197 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0; 198 Entry.Version = Extractor.getU8(&OffsetPtr); 199 if (Entry.Version >= 2) { 200 Entry.Address += C - Contents.bytes_begin() + Address; 201 Entry.Function += C - Contents.bytes_begin() + WordSize + Address; 202 } 203 204 // We do replicate the function id generation scheme implemented in the 205 // XRay runtime. 206 // FIXME: Figure out how to keep this consistent with the XRay runtime. 207 if (CurFn == 0) { 208 CurFn = Entry.Function; 209 FunctionAddresses[FuncId] = Entry.Function; 210 FunctionIds[Entry.Function] = FuncId; 211 } 212 if (Entry.Function != CurFn) { 213 ++FuncId; 214 CurFn = Entry.Function; 215 FunctionAddresses[FuncId] = Entry.Function; 216 FunctionIds[Entry.Function] = FuncId; 217 } 218 } 219 return Error::success(); 220 } 221 222 static Error 223 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename, 224 InstrumentationMap::SledContainer &Sleds, 225 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 226 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 227 std::error_code EC; 228 sys::fs::mapped_file_region MappedFile( 229 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC); 230 sys::fs::closeFile(Fd); 231 if (EC) 232 return make_error<StringError>( 233 Twine("Failed memory-mapping file '") + Filename + "'.", EC); 234 235 std::vector<YAMLXRaySledEntry> YAMLSleds; 236 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size())); 237 In >> YAMLSleds; 238 if (In.error()) 239 return make_error<StringError>( 240 Twine("Failed loading YAML document from '") + Filename + "'.", 241 In.error()); 242 243 Sleds.reserve(YAMLSleds.size()); 244 for (const auto &Y : YAMLSleds) { 245 FunctionAddresses[Y.FuncId] = Y.Function; 246 FunctionIds[Y.Function] = Y.FuncId; 247 Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument, 248 Y.Version}); 249 } 250 return Error::success(); 251 } 252 253 // FIXME: Create error types that encapsulate a bit more information than what 254 // StringError instances contain. 255 Expected<InstrumentationMap> 256 llvm::xray::loadInstrumentationMap(StringRef Filename) { 257 // At this point we assume the file is an object file -- and if that doesn't 258 // work, we treat it as YAML. 259 // FIXME: Extend to support non-ELF and non-x86_64 binaries. 260 261 InstrumentationMap Map; 262 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename); 263 if (!ObjectFileOrError) { 264 auto E = ObjectFileOrError.takeError(); 265 // We try to load it as YAML if the ELF load didn't work. 266 Expected<sys::fs::file_t> FdOrErr = 267 sys::fs::openNativeFileForRead(Filename); 268 if (!FdOrErr) { 269 // Report the ELF load error if YAML failed. 270 consumeError(FdOrErr.takeError()); 271 return std::move(E); 272 } 273 274 uint64_t FileSize; 275 if (sys::fs::file_size(Filename, FileSize)) 276 return std::move(E); 277 278 // If the file is empty, we return the original error. 279 if (FileSize == 0) 280 return std::move(E); 281 282 // From this point on the errors will be only for the YAML parts, so we 283 // consume the errors at this point. 284 consumeError(std::move(E)); 285 if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds, 286 Map.FunctionAddresses, Map.FunctionIds)) 287 return std::move(E); 288 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds, 289 Map.FunctionAddresses, Map.FunctionIds)) { 290 return std::move(E); 291 } 292 return Map; 293 } 294