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/STLExtras.h" 16 #include "llvm/ADT/StringRef.h" 17 #include "llvm/ADT/Triple.h" 18 #include "llvm/ADT/Twine.h" 19 #include "llvm/Object/Binary.h" 20 #include "llvm/Object/ELFObjectFile.h" 21 #include "llvm/Object/ObjectFile.h" 22 #include "llvm/Object/RelocationResolver.h" 23 #include "llvm/Support/DataExtractor.h" 24 #include "llvm/Support/Error.h" 25 #include "llvm/Support/FileSystem.h" 26 #include "llvm/Support/YAMLTraits.h" 27 #include <algorithm> 28 #include <cstddef> 29 #include <cstdint> 30 #include <system_error> 31 #include <vector> 32 33 using namespace llvm; 34 using namespace xray; 35 36 Optional<int32_t> InstrumentationMap::getFunctionId(uint64_t Addr) const { 37 auto I = FunctionIds.find(Addr); 38 if (I != FunctionIds.end()) 39 return I->second; 40 return std::nullopt; 41 } 42 43 Optional<uint64_t> InstrumentationMap::getFunctionAddr(int32_t FuncId) const { 44 auto I = FunctionAddresses.find(FuncId); 45 if (I != FunctionAddresses.end()) 46 return I->second; 47 return std::nullopt; 48 } 49 50 using RelocMap = DenseMap<uint64_t, uint64_t>; 51 52 static Error 53 loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile, 54 InstrumentationMap::SledContainer &Sleds, 55 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 56 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 57 InstrumentationMap Map; 58 59 // Find the section named "xray_instr_map". 60 if ((!ObjFile.getBinary()->isELF() && !ObjFile.getBinary()->isMachO()) || 61 !(ObjFile.getBinary()->getArch() == Triple::x86_64 || 62 ObjFile.getBinary()->getArch() == Triple::ppc64le || 63 ObjFile.getBinary()->getArch() == Triple::arm || 64 ObjFile.getBinary()->getArch() == Triple::aarch64)) 65 return make_error<StringError>( 66 "File format not supported (only does ELF and Mach-O little endian " 67 "64-bit).", 68 std::make_error_code(std::errc::not_supported)); 69 70 StringRef Contents = ""; 71 const auto &Sections = ObjFile.getBinary()->sections(); 72 uint64_t Address = 0; 73 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) { 74 Expected<StringRef> NameOrErr = Section.getName(); 75 if (NameOrErr) { 76 Address = Section.getAddress(); 77 return *NameOrErr == "xray_instr_map"; 78 } 79 consumeError(NameOrErr.takeError()); 80 return false; 81 }); 82 83 if (I == Sections.end()) 84 return make_error<StringError>( 85 "Failed to find XRay instrumentation map.", 86 std::make_error_code(std::errc::executable_format_error)); 87 88 if (Error E = I->getContents().moveInto(Contents)) 89 return E; 90 91 RelocMap Relocs; 92 if (ObjFile.getBinary()->isELF()) { 93 uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) { 94 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile)) 95 return ELFObj->getELFFile().getRelativeRelocationType(); 96 else if (const auto *ELFObj = 97 dyn_cast<object::ELF32BEObjectFile>(ObjFile)) 98 return ELFObj->getELFFile().getRelativeRelocationType(); 99 else if (const auto *ELFObj = 100 dyn_cast<object::ELF64LEObjectFile>(ObjFile)) 101 return ELFObj->getELFFile().getRelativeRelocationType(); 102 else if (const auto *ELFObj = 103 dyn_cast<object::ELF64BEObjectFile>(ObjFile)) 104 return ELFObj->getELFFile().getRelativeRelocationType(); 105 else 106 return static_cast<uint32_t>(0); 107 }(ObjFile.getBinary()); 108 109 object::SupportsRelocation Supports; 110 object::RelocationResolver Resolver; 111 std::tie(Supports, Resolver) = 112 object::getRelocationResolver(*ObjFile.getBinary()); 113 114 for (const object::SectionRef &Section : Sections) { 115 for (const object::RelocationRef &Reloc : Section.relocations()) { 116 if (ObjFile.getBinary()->getArch() == Triple::arm) { 117 if (Supports && Supports(Reloc.getType())) { 118 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 119 if (!ValueOrErr) 120 return ValueOrErr.takeError(); 121 Relocs.insert( 122 {Reloc.getOffset(), 123 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, 0)}); 124 } 125 } else if (Supports && Supports(Reloc.getType())) { 126 auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend(); 127 auto A = AddendOrErr ? *AddendOrErr : 0; 128 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 129 if (!ValueOrErr) 130 // TODO: Test this error. 131 return ValueOrErr.takeError(); 132 Relocs.insert( 133 {Reloc.getOffset(), 134 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, A)}); 135 } else if (Reloc.getType() == RelativeRelocation) { 136 if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend()) 137 Relocs.insert({Reloc.getOffset(), *AddendOrErr}); 138 } 139 } 140 } 141 } 142 143 // Copy the instrumentation map data into the Sleds data structure. 144 auto C = Contents.bytes_begin(); 145 bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit(); 146 size_t ELFSledEntrySize = Is32Bit ? 16 : 32; 147 148 if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0) 149 return make_error<StringError>( 150 Twine("Instrumentation map entries not evenly divisible by size of " 151 "an XRay sled entry."), 152 std::make_error_code(std::errc::executable_format_error)); 153 154 auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) { 155 if (!Address) { 156 uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset; 157 RelocMap::const_iterator R = Relocs.find(A); 158 if (R != Relocs.end()) 159 return R->second; 160 } 161 return Address; 162 }; 163 164 const int WordSize = Is32Bit ? 4 : 8; 165 int32_t FuncId = 1; 166 uint64_t CurFn = 0; 167 for (; C != Contents.bytes_end(); C += ELFSledEntrySize) { 168 DataExtractor Extractor( 169 StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true, 170 8); 171 Sleds.push_back({}); 172 auto &Entry = Sleds.back(); 173 uint64_t OffsetPtr = 0; 174 uint64_t AddrOff = OffsetPtr; 175 if (Is32Bit) 176 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr)); 177 else 178 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr)); 179 uint64_t FuncOff = OffsetPtr; 180 if (Is32Bit) 181 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr)); 182 else 183 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr)); 184 auto Kind = Extractor.getU8(&OffsetPtr); 185 static constexpr SledEntry::FunctionKinds Kinds[] = { 186 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT, 187 SledEntry::FunctionKinds::TAIL, 188 SledEntry::FunctionKinds::LOG_ARGS_ENTER, 189 SledEntry::FunctionKinds::CUSTOM_EVENT}; 190 if (Kind >= std::size(Kinds)) 191 return errorCodeToError( 192 std::make_error_code(std::errc::executable_format_error)); 193 Entry.Kind = Kinds[Kind]; 194 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0; 195 Entry.Version = Extractor.getU8(&OffsetPtr); 196 if (Entry.Version >= 2) { 197 Entry.Address += C - Contents.bytes_begin() + Address; 198 Entry.Function += C - Contents.bytes_begin() + WordSize + Address; 199 } 200 201 // We do replicate the function id generation scheme implemented in the 202 // XRay runtime. 203 // FIXME: Figure out how to keep this consistent with the XRay runtime. 204 if (CurFn == 0) { 205 CurFn = Entry.Function; 206 FunctionAddresses[FuncId] = Entry.Function; 207 FunctionIds[Entry.Function] = FuncId; 208 } 209 if (Entry.Function != CurFn) { 210 ++FuncId; 211 CurFn = Entry.Function; 212 FunctionAddresses[FuncId] = Entry.Function; 213 FunctionIds[Entry.Function] = FuncId; 214 } 215 } 216 return Error::success(); 217 } 218 219 static Error 220 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename, 221 InstrumentationMap::SledContainer &Sleds, 222 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 223 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 224 std::error_code EC; 225 sys::fs::mapped_file_region MappedFile( 226 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC); 227 sys::fs::closeFile(Fd); 228 if (EC) 229 return make_error<StringError>( 230 Twine("Failed memory-mapping file '") + Filename + "'.", EC); 231 232 std::vector<YAMLXRaySledEntry> YAMLSleds; 233 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size())); 234 In >> YAMLSleds; 235 if (In.error()) 236 return make_error<StringError>( 237 Twine("Failed loading YAML document from '") + Filename + "'.", 238 In.error()); 239 240 Sleds.reserve(YAMLSleds.size()); 241 for (const auto &Y : YAMLSleds) { 242 FunctionAddresses[Y.FuncId] = Y.Function; 243 FunctionIds[Y.Function] = Y.FuncId; 244 Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument, 245 Y.Version}); 246 } 247 return Error::success(); 248 } 249 250 // FIXME: Create error types that encapsulate a bit more information than what 251 // StringError instances contain. 252 Expected<InstrumentationMap> 253 llvm::xray::loadInstrumentationMap(StringRef Filename) { 254 // At this point we assume the file is an object file -- and if that doesn't 255 // work, we treat it as YAML. 256 // FIXME: Extend to support non-ELF and non-x86_64 binaries. 257 258 InstrumentationMap Map; 259 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename); 260 if (!ObjectFileOrError) { 261 auto E = ObjectFileOrError.takeError(); 262 // We try to load it as YAML if the ELF load didn't work. 263 Expected<sys::fs::file_t> FdOrErr = 264 sys::fs::openNativeFileForRead(Filename); 265 if (!FdOrErr) { 266 // Report the ELF load error if YAML failed. 267 consumeError(FdOrErr.takeError()); 268 return std::move(E); 269 } 270 271 uint64_t FileSize; 272 if (sys::fs::file_size(Filename, FileSize)) 273 return std::move(E); 274 275 // If the file is empty, we return the original error. 276 if (FileSize == 0) 277 return std::move(E); 278 279 // From this point on the errors will be only for the YAML parts, so we 280 // consume the errors at this point. 281 consumeError(std::move(E)); 282 if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds, 283 Map.FunctionAddresses, Map.FunctionIds)) 284 return std::move(E); 285 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds, 286 Map.FunctionAddresses, Map.FunctionIds)) { 287 return std::move(E); 288 } 289 return Map; 290 } 291