llvm/lib/XRay/InstrumentationMap.cpp

   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/Twine.h"
  18 #include "llvm/Object/Binary.h"
  19 #include "llvm/Object/ELFObjectFile.h"
  20 #include "llvm/Object/ObjectFile.h"
  21 #include "llvm/Object/RelocationResolver.h"
  22 #include "llvm/Support/DataExtractor.h"
  23 #include "llvm/Support/Error.h"
  24 #include "llvm/Support/FileSystem.h"
  25 #include "llvm/Support/YAMLTraits.h"
  26 #include "llvm/TargetParser/Triple.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::loongarch64 ||
  64         ObjFile.getBinary()->getArch() == Triple::ppc64le ||
  65         ObjFile.getBinary()->getArch() == Triple::arm ||
  66         ObjFile.getBinary()->getArch() == Triple::aarch64))
  67     return make_error<StringError>(
  68         "File format not supported (only does ELF and Mach-O little endian "
  69         "64-bit).",
  70         std::make_error_code(std::errc::not_supported));
  71
  72   StringRef Contents = "";
  73   const auto &Sections = ObjFile.getBinary()->sections();
  74   uint64_t Address = 0;
  75   auto I = llvm::find_if(Sections, [&](object::SectionRef Section) {
  76     Expected<StringRef> NameOrErr = Section.getName();
  77     if (NameOrErr) {
  78       Address = Section.getAddress();
  79       return *NameOrErr == "xray_instr_map";
  80     }
  81     consumeError(NameOrErr.takeError());
  82     return false;
  83   });
  84
  85   if (I == Sections.end())
  86     return make_error<StringError>(
  87         "Failed to find XRay instrumentation map.",
  88         std::make_error_code(std::errc::executable_format_error));
  89
  90   if (Error E = I->getContents().moveInto(Contents))
  91     return E;
  92
  93   RelocMap Relocs;
  94   if (ObjFile.getBinary()->isELF()) {
  95     uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) {
  96       if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile))
  97         return ELFObj->getELFFile().getRelativeRelocationType();
  98       else if (const auto *ELFObj =
  99                    dyn_cast<object::ELF32BEObjectFile>(ObjFile))
 100         return ELFObj->getELFFile().getRelativeRelocationType();
 101       else if (const auto *ELFObj =
 102                    dyn_cast<object::ELF64LEObjectFile>(ObjFile))
 103         return ELFObj->getELFFile().getRelativeRelocationType();
 104       else if (const auto *ELFObj =
 105                    dyn_cast<object::ELF64BEObjectFile>(ObjFile))
 106         return ELFObj->getELFFile().getRelativeRelocationType();
 107       else
 108         return static_cast<uint32_t>(0);
 109     }(ObjFile.getBinary());
 110
 111     object::SupportsRelocation Supports;
 112     object::RelocationResolver Resolver;
 113     std::tie(Supports, Resolver) =
 114         object::getRelocationResolver(*ObjFile.getBinary());
 115
 116     for (const object::SectionRef &Section : Sections) {
 117       for (const object::RelocationRef &Reloc : Section.relocations()) {
 118         if (ObjFile.getBinary()->getArch() == Triple::arm) {
 119           if (Supports && Supports(Reloc.getType())) {
 120             Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
 121             if (!ValueOrErr)
 122               return ValueOrErr.takeError();
 123             Relocs.insert(
 124                 {Reloc.getOffset(),
 125                  object::resolveRelocation(Resolver, Reloc, *ValueOrErr, 0)});
 126           }
 127         } else if (Supports && Supports(Reloc.getType())) {
 128           auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend();
 129           auto A = AddendOrErr ? *AddendOrErr : 0;
 130           Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
 131           if (!ValueOrErr)
 132             // TODO: Test this error.
 133             return ValueOrErr.takeError();
 134           Relocs.insert(
 135               {Reloc.getOffset(),
 136                object::resolveRelocation(Resolver, Reloc, *ValueOrErr, A)});
 137         } else if (Reloc.getType() == RelativeRelocation) {
 138           if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend())
 139             Relocs.insert({Reloc.getOffset(), *AddendOrErr});
 140         }
 141       }
 142     }
 143   }
 144
 145   // Copy the instrumentation map data into the Sleds data structure.
 146   auto C = Contents.bytes_begin();
 147   bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit();
 148   size_t ELFSledEntrySize = Is32Bit ? 16 : 32;
 149
 150   if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0)
 151     return make_error<StringError>(
 152         Twine("Instrumentation map entries not evenly divisible by size of "
 153               "an XRay sled entry."),
 154         std::make_error_code(std::errc::executable_format_error));
 155
 156   auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) {
 157     if (!Address) {
 158       uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset;
 159       RelocMap::const_iterator R = Relocs.find(A);
 160       if (R != Relocs.end())
 161         return R->second;
 162     }
 163     return Address;
 164   };
 165
 166   const int WordSize = Is32Bit ? 4 : 8;
 167   int32_t FuncId = 1;
 168   uint64_t CurFn = 0;
 169   for (; C != Contents.bytes_end(); C += ELFSledEntrySize) {
 170     DataExtractor Extractor(
 171         StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true,
 172         8);
 173     Sleds.push_back({});
 174     auto &Entry = Sleds.back();
 175     uint64_t OffsetPtr = 0;
 176     uint64_t AddrOff = OffsetPtr;
 177     if (Is32Bit)
 178       Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr));
 179     else
 180       Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr));
 181     uint64_t FuncOff = OffsetPtr;
 182     if (Is32Bit)
 183       Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr));
 184     else
 185       Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr));
 186     auto Kind = Extractor.getU8(&OffsetPtr);
 187     static constexpr SledEntry::FunctionKinds Kinds[] = {
 188         SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT,
 189         SledEntry::FunctionKinds::TAIL,
 190         SledEntry::FunctionKinds::LOG_ARGS_ENTER,
 191         SledEntry::FunctionKinds::CUSTOM_EVENT};
 192     if (Kind >= std::size(Kinds))
 193       return errorCodeToError(
 194           std::make_error_code(std::errc::executable_format_error));
 195     Entry.Kind = Kinds[Kind];
 196     Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0;
 197     Entry.Version = Extractor.getU8(&OffsetPtr);
 198     if (Entry.Version >= 2) {
 199       Entry.Address += C - Contents.bytes_begin() + Address;
 200       Entry.Function += C - Contents.bytes_begin() + WordSize + Address;
 201     }
 202
 203     // We do replicate the function id generation scheme implemented in the
 204     // XRay runtime.
 205     // FIXME: Figure out how to keep this consistent with the XRay runtime.
 206     if (CurFn == 0) {
 207       CurFn = Entry.Function;
 208       FunctionAddresses[FuncId] = Entry.Function;
 209       FunctionIds[Entry.Function] = FuncId;
 210     }
 211     if (Entry.Function != CurFn) {
 212       ++FuncId;
 213       CurFn = Entry.Function;
 214       FunctionAddresses[FuncId] = Entry.Function;
 215       FunctionIds[Entry.Function] = FuncId;
 216     }
 217   }
 218   return Error::success();
 219 }
 220
 221 static Error
 222 loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename,
 223          InstrumentationMap::SledContainer &Sleds,
 224          InstrumentationMap::FunctionAddressMap &FunctionAddresses,
 225          InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
 226   std::error_code EC;
 227   sys::fs::mapped_file_region MappedFile(
 228       Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC);
 229   sys::fs::closeFile(Fd);
 230   if (EC)
 231     return make_error<StringError>(
 232         Twine("Failed memory-mapping file '") + Filename + "'.", EC);
 233
 234   std::vector<YAMLXRaySledEntry> YAMLSleds;
 235   yaml::Input In(StringRef(MappedFile.data(), MappedFile.size()));
 236   In >> YAMLSleds;
 237   if (In.error())
 238     return make_error<StringError>(
 239         Twine("Failed loading YAML document from '") + Filename + "'.",
 240         In.error());
 241
 242   Sleds.reserve(YAMLSleds.size());
 243   for (const auto &Y : YAMLSleds) {
 244     FunctionAddresses[Y.FuncId] = Y.Function;
 245     FunctionIds[Y.Function] = Y.FuncId;
 246     Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument,
 247                               Y.Version});
 248   }
 249   return Error::success();
 250 }
 251
 252 // FIXME: Create error types that encapsulate a bit more information than what
 253 // StringError instances contain.
 254 Expected<InstrumentationMap>
 255 llvm::xray::loadInstrumentationMap(StringRef Filename) {
 256   // At this point we assume the file is an object file -- and if that doesn't
 257   // work, we treat it as YAML.
 258   // FIXME: Extend to support non-ELF and non-x86_64 binaries.
 259
 260   InstrumentationMap Map;
 261   auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename);
 262   if (!ObjectFileOrError) {
 263     auto E = ObjectFileOrError.takeError();
 264     // We try to load it as YAML if the ELF load didn't work.
 265     Expected<sys::fs::file_t> FdOrErr =
 266         sys::fs::openNativeFileForRead(Filename);
 267     if (!FdOrErr) {
 268       // Report the ELF load error if YAML failed.
 269       consumeError(FdOrErr.takeError());
 270       return std::move(E);
 271     }
 272
 273     uint64_t FileSize;
 274     if (sys::fs::file_size(Filename, FileSize))
 275       return std::move(E);
 276
 277     // If the file is empty, we return the original error.
 278     if (FileSize == 0)
 279       return std::move(E);
 280
 281     // From this point on the errors will be only for the YAML parts, so we
 282     // consume the errors at this point.
 283     consumeError(std::move(E));
 284     if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds,
 285                           Map.FunctionAddresses, Map.FunctionIds))
 286       return std::move(E);
 287   } else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds,
 288                               Map.FunctionAddresses, Map.FunctionIds)) {
 289     return std::move(E);
 290   }
 291   return Map;
 292 }