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 std::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 std::optional<uint64_t> 44 InstrumentationMap::getFunctionAddr(int32_t FuncId) const { 45 auto I = FunctionAddresses.find(FuncId); 46 if (I != FunctionAddresses.end()) 47 return I->second; 48 return std::nullopt; 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 (Error E = I->getContents().moveInto(Contents)) 90 return E; 91 92 RelocMap Relocs; 93 if (ObjFile.getBinary()->isELF()) { 94 uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) { 95 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile)) 96 return ELFObj->getELFFile().getRelativeRelocationType(); 97 else if (const auto *ELFObj = 98 dyn_cast<object::ELF32BEObjectFile>(ObjFile)) 99 return ELFObj->getELFFile().getRelativeRelocationType(); 100 else if (const auto *ELFObj = 101 dyn_cast<object::ELF64LEObjectFile>(ObjFile)) 102 return ELFObj->getELFFile().getRelativeRelocationType(); 103 else if (const auto *ELFObj = 104 dyn_cast<object::ELF64BEObjectFile>(ObjFile)) 105 return ELFObj->getELFFile().getRelativeRelocationType(); 106 else 107 return static_cast<uint32_t>(0); 108 }(ObjFile.getBinary()); 109 110 object::SupportsRelocation Supports; 111 object::RelocationResolver Resolver; 112 std::tie(Supports, Resolver) = 113 object::getRelocationResolver(*ObjFile.getBinary()); 114 115 for (const object::SectionRef &Section : Sections) { 116 for (const object::RelocationRef &Reloc : Section.relocations()) { 117 if (ObjFile.getBinary()->getArch() == Triple::arm) { 118 if (Supports && Supports(Reloc.getType())) { 119 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 120 if (!ValueOrErr) 121 return ValueOrErr.takeError(); 122 Relocs.insert( 123 {Reloc.getOffset(), 124 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, 0)}); 125 } 126 } else if (Supports && Supports(Reloc.getType())) { 127 auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend(); 128 auto A = AddendOrErr ? *AddendOrErr : 0; 129 Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue(); 130 if (!ValueOrErr) 131 // TODO: Test this error. 132 return ValueOrErr.takeError(); 133 Relocs.insert( 134 {Reloc.getOffset(), 135 object::resolveRelocation(Resolver, Reloc, *ValueOrErr, A)}); 136 } else if (Reloc.getType() == RelativeRelocation) { 137 if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend()) 138 Relocs.insert({Reloc.getOffset(), *AddendOrErr}); 139 } 140 } 141 } 142 } 143 144 // Copy the instrumentation map data into the Sleds data structure. 145 auto C = Contents.bytes_begin(); 146 bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit(); 147 size_t ELFSledEntrySize = Is32Bit ? 16 : 32; 148 149 if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0) 150 return make_error<StringError>( 151 Twine("Instrumentation map entries not evenly divisible by size of " 152 "an XRay sled entry."), 153 std::make_error_code(std::errc::executable_format_error)); 154 155 auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) { 156 if (!Address) { 157 uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset; 158 RelocMap::const_iterator R = Relocs.find(A); 159 if (R != Relocs.end()) 160 return R->second; 161 } 162 return Address; 163 }; 164 165 const int WordSize = Is32Bit ? 4 : 8; 166 int32_t FuncId = 1; 167 uint64_t CurFn = 0; 168 for (; C != Contents.bytes_end(); C += ELFSledEntrySize) { 169 DataExtractor Extractor( 170 StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true, 171 8); 172 Sleds.push_back({}); 173 auto &Entry = Sleds.back(); 174 uint64_t OffsetPtr = 0; 175 uint64_t AddrOff = OffsetPtr; 176 if (Is32Bit) 177 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr)); 178 else 179 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr)); 180 uint64_t FuncOff = OffsetPtr; 181 if (Is32Bit) 182 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr)); 183 else 184 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr)); 185 auto Kind = Extractor.getU8(&OffsetPtr); 186 static constexpr SledEntry::FunctionKinds Kinds[] = { 187 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT, 188 SledEntry::FunctionKinds::TAIL, 189 SledEntry::FunctionKinds::LOG_ARGS_ENTER, 190 SledEntry::FunctionKinds::CUSTOM_EVENT}; 191 if (Kind >= std::size(Kinds)) 192 return errorCodeToError( 193 std::make_error_code(std::errc::executable_format_error)); 194 Entry.Kind = Kinds[Kind]; 195 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0; 196 Entry.Version = Extractor.getU8(&OffsetPtr); 197 if (Entry.Version >= 2) { 198 Entry.Address += C - Contents.bytes_begin() + Address; 199 Entry.Function += C - Contents.bytes_begin() + WordSize + Address; 200 } 201 202 // We do replicate the function id generation scheme implemented in the 203 // XRay runtime. 204 // FIXME: Figure out how to keep this consistent with the XRay runtime. 205 if (CurFn == 0) { 206 CurFn = Entry.Function; 207 FunctionAddresses[FuncId] = Entry.Function; 208 FunctionIds[Entry.Function] = FuncId; 209 } 210 if (Entry.Function != CurFn) { 211 ++FuncId; 212 CurFn = Entry.Function; 213 FunctionAddresses[FuncId] = Entry.Function; 214 FunctionIds[Entry.Function] = FuncId; 215 } 216 } 217 return Error::success(); 218 } 219 220 static Error 221 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename, 222 InstrumentationMap::SledContainer &Sleds, 223 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 224 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 225 std::error_code EC; 226 sys::fs::mapped_file_region MappedFile( 227 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC); 228 sys::fs::closeFile(Fd); 229 if (EC) 230 return make_error<StringError>( 231 Twine("Failed memory-mapping file '") + Filename + "'.", EC); 232 233 std::vector<YAMLXRaySledEntry> YAMLSleds; 234 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size())); 235 In >> YAMLSleds; 236 if (In.error()) 237 return make_error<StringError>( 238 Twine("Failed loading YAML document from '") + Filename + "'.", 239 In.error()); 240 241 Sleds.reserve(YAMLSleds.size()); 242 for (const auto &Y : YAMLSleds) { 243 FunctionAddresses[Y.FuncId] = Y.Function; 244 FunctionIds[Y.Function] = Y.FuncId; 245 Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument, 246 Y.Version}); 247 } 248 return Error::success(); 249 } 250 251 // FIXME: Create error types that encapsulate a bit more information than what 252 // StringError instances contain. 253 Expected<InstrumentationMap> 254 llvm::xray::loadInstrumentationMap(StringRef Filename) { 255 // At this point we assume the file is an object file -- and if that doesn't 256 // work, we treat it as YAML. 257 // FIXME: Extend to support non-ELF and non-x86_64 binaries. 258 259 InstrumentationMap Map; 260 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename); 261 if (!ObjectFileOrError) { 262 auto E = ObjectFileOrError.takeError(); 263 // We try to load it as YAML if the ELF load didn't work. 264 Expected<sys::fs::file_t> FdOrErr = 265 sys::fs::openNativeFileForRead(Filename); 266 if (!FdOrErr) { 267 // Report the ELF load error if YAML failed. 268 consumeError(FdOrErr.takeError()); 269 return std::move(E); 270 } 271 272 uint64_t FileSize; 273 if (sys::fs::file_size(Filename, FileSize)) 274 return std::move(E); 275 276 // If the file is empty, we return the original error. 277 if (FileSize == 0) 278 return std::move(E); 279 280 // From this point on the errors will be only for the YAML parts, so we 281 // consume the errors at this point. 282 consumeError(std::move(E)); 283 if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds, 284 Map.FunctionAddresses, Map.FunctionIds)) 285 return std::move(E); 286 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds, 287 Map.FunctionAddresses, Map.FunctionIds)) { 288 return std::move(E); 289 } 290 return Map; 291 } 292