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/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 None; 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 None; 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 return make_error<StringError>( 64 "File format not supported (only does ELF and Mach-O little endian 64-bit).", 65 std::make_error_code(std::errc::not_supported)); 66 67 StringRef Contents = ""; 68 const auto &Sections = ObjFile.getBinary()->sections(); 69 auto I = llvm::find_if(Sections, [&](object::SectionRef Section) { 70 StringRef Name = ""; 71 if (Section.getName(Name)) 72 return false; 73 return Name == "xray_instr_map"; 74 }); 75 76 if (I == Sections.end()) 77 return make_error<StringError>( 78 "Failed to find XRay instrumentation map.", 79 std::make_error_code(std::errc::executable_format_error)); 80 81 if (Expected<StringRef> E = I->getContents()) 82 Contents = *E; 83 else 84 return E.takeError(); 85 86 RelocMap Relocs; 87 if (ObjFile.getBinary()->isELF()) { 88 uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) { 89 if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile)) 90 return ELFObj->getELFFile()->getRelativeRelocationType(); 91 else if (const auto *ELFObj = dyn_cast<object::ELF32BEObjectFile>(ObjFile)) 92 return ELFObj->getELFFile()->getRelativeRelocationType(); 93 else if (const auto *ELFObj = dyn_cast<object::ELF64LEObjectFile>(ObjFile)) 94 return ELFObj->getELFFile()->getRelativeRelocationType(); 95 else if (const auto *ELFObj = dyn_cast<object::ELF64BEObjectFile>(ObjFile)) 96 return ELFObj->getELFFile()->getRelativeRelocationType(); 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() != RelativeRelocation) 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 uint32_t AddrOff = OffsetPtr; 141 Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr)); 142 uint32_t FuncOff = OffsetPtr; 143 Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr)); 144 auto Kind = Extractor.getU8(&OffsetPtr); 145 static constexpr SledEntry::FunctionKinds Kinds[] = { 146 SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT, 147 SledEntry::FunctionKinds::TAIL, 148 SledEntry::FunctionKinds::LOG_ARGS_ENTER, 149 SledEntry::FunctionKinds::CUSTOM_EVENT}; 150 if (Kind >= sizeof(Kinds)) 151 return errorCodeToError( 152 std::make_error_code(std::errc::executable_format_error)); 153 Entry.Kind = Kinds[Kind]; 154 Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0; 155 156 // We do replicate the function id generation scheme implemented in the 157 // XRay runtime. 158 // FIXME: Figure out how to keep this consistent with the XRay runtime. 159 if (CurFn == 0) { 160 CurFn = Entry.Function; 161 FunctionAddresses[FuncId] = Entry.Function; 162 FunctionIds[Entry.Function] = FuncId; 163 } 164 if (Entry.Function != CurFn) { 165 ++FuncId; 166 CurFn = Entry.Function; 167 FunctionAddresses[FuncId] = Entry.Function; 168 FunctionIds[Entry.Function] = FuncId; 169 } 170 } 171 return Error::success(); 172 } 173 174 static Error 175 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename, 176 InstrumentationMap::SledContainer &Sleds, 177 InstrumentationMap::FunctionAddressMap &FunctionAddresses, 178 InstrumentationMap::FunctionAddressReverseMap &FunctionIds) { 179 std::error_code EC; 180 sys::fs::mapped_file_region MappedFile( 181 Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC); 182 sys::fs::closeFile(Fd); 183 if (EC) 184 return make_error<StringError>( 185 Twine("Failed memory-mapping file '") + Filename + "'.", EC); 186 187 std::vector<YAMLXRaySledEntry> YAMLSleds; 188 yaml::Input In(StringRef(MappedFile.data(), MappedFile.size())); 189 In >> YAMLSleds; 190 if (In.error()) 191 return make_error<StringError>( 192 Twine("Failed loading YAML document from '") + Filename + "'.", 193 In.error()); 194 195 Sleds.reserve(YAMLSleds.size()); 196 for (const auto &Y : YAMLSleds) { 197 FunctionAddresses[Y.FuncId] = Y.Function; 198 FunctionIds[Y.Function] = Y.FuncId; 199 Sleds.push_back( 200 SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument}); 201 } 202 return Error::success(); 203 } 204 205 // FIXME: Create error types that encapsulate a bit more information than what 206 // StringError instances contain. 207 Expected<InstrumentationMap> 208 llvm::xray::loadInstrumentationMap(StringRef Filename) { 209 // At this point we assume the file is an object file -- and if that doesn't 210 // work, we treat it as YAML. 211 // FIXME: Extend to support non-ELF and non-x86_64 binaries. 212 213 InstrumentationMap Map; 214 auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename); 215 if (!ObjectFileOrError) { 216 auto E = ObjectFileOrError.takeError(); 217 // We try to load it as YAML if the ELF load didn't work. 218 Expected<sys::fs::file_t> FdOrErr = sys::fs::openNativeFileForRead(Filename); 219 if (!FdOrErr) { 220 // Report the ELF load error if YAML failed. 221 consumeError(FdOrErr.takeError()); 222 return std::move(E); 223 } 224 225 uint64_t FileSize; 226 if (sys::fs::file_size(Filename, FileSize)) 227 return std::move(E); 228 229 // If the file is empty, we return the original error. 230 if (FileSize == 0) 231 return std::move(E); 232 233 // From this point on the errors will be only for the YAML parts, so we 234 // consume the errors at this point. 235 consumeError(std::move(E)); 236 if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds, 237 Map.FunctionAddresses, Map.FunctionIds)) 238 return std::move(E); 239 } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds, 240 Map.FunctionAddresses, Map.FunctionIds)) { 241 return std::move(E); 242 } 243 return Map; 244 } 245