llvm/lib/DebugInfo/GSYM/ObjectFileTransformer.cpp

   1 //===- ObjectFileTransformer.cpp --------------------------------*- C++ -*-===//
   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 #include <unordered_set>
  10
  11 #include "llvm/Object/ELFObjectFile.h"
  12 #include "llvm/Object/MachOUniversal.h"
  13 #include "llvm/Object/ObjectFile.h"
  14 #include "llvm/Support/DataExtractor.h"
  15 #include "llvm/Support/raw_ostream.h"
  16
  17 #include "llvm/DebugInfo/GSYM/ObjectFileTransformer.h"
  18 #include "llvm/DebugInfo/GSYM/GsymCreator.h"
  19
  20 using namespace llvm;
  21 using namespace gsym;
  22
  23 constexpr uint32_t NT_GNU_BUILD_ID_TAG = 0x03;
  24
  25 static std::vector<uint8_t> getUUID(const object::ObjectFile &Obj) {
  26   // Extract the UUID from the object file
  27   std::vector<uint8_t> UUID;
  28   if (auto *MachO = dyn_cast<object::MachOObjectFile>(&Obj)) {
  29     const ArrayRef<uint8_t> MachUUID = MachO->getUuid();
  30     if (!MachUUID.empty())
  31       UUID.assign(MachUUID.data(), MachUUID.data() + MachUUID.size());
  32   } else if (isa<object::ELFObjectFileBase>(&Obj)) {
  33     const StringRef GNUBuildID(".note.gnu.build-id");
  34     for (const object::SectionRef &Sect : Obj.sections()) {
  35       Expected<StringRef> SectNameOrErr = Sect.getName();
  36       if (!SectNameOrErr) {
  37         consumeError(SectNameOrErr.takeError());
  38         continue;
  39       }
  40       StringRef SectName(*SectNameOrErr);
  41       if (SectName != GNUBuildID)
  42         continue;
  43       StringRef BuildIDData;
  44       Expected<StringRef> E = Sect.getContents();
  45       if (E)
  46         BuildIDData = *E;
  47       else {
  48         consumeError(E.takeError());
  49         continue;
  50       }
  51       DataExtractor Decoder(BuildIDData, Obj.makeTriple().isLittleEndian(), 8);
  52       uint64_t Offset = 0;
  53       const uint32_t NameSize = Decoder.getU32(&Offset);
  54       const uint32_t PayloadSize = Decoder.getU32(&Offset);
  55       const uint32_t PayloadType = Decoder.getU32(&Offset);
  56       StringRef Name(Decoder.getFixedLengthString(&Offset, NameSize));
  57       if (Name == "GNU" && PayloadType == NT_GNU_BUILD_ID_TAG) {
  58         Offset = alignTo(Offset, 4);
  59         StringRef UUIDBytes(Decoder.getBytes(&Offset, PayloadSize));
  60         if (!UUIDBytes.empty()) {
  61           auto Ptr = reinterpret_cast<const uint8_t *>(UUIDBytes.data());
  62           UUID.assign(Ptr, Ptr + UUIDBytes.size());
  63         }
  64       }
  65     }
  66   }
  67   return UUID;
  68 }
  69
  70 llvm::Error ObjectFileTransformer::convert(const object::ObjectFile &Obj,
  71                                            raw_ostream &Log,
  72                                            GsymCreator &Gsym) {
  73   using namespace llvm::object;
  74
  75   const bool IsMachO = isa<MachOObjectFile>(&Obj);
  76   const bool IsELF = isa<ELFObjectFileBase>(&Obj);
  77
  78   // Read build ID.
  79   Gsym.setUUID(getUUID(Obj));
  80
  81   // Parse the symbol table.
  82   size_t NumBefore = Gsym.getNumFunctionInfos();
  83   for (const object::SymbolRef &Sym : Obj.symbols()) {
  84     Expected<SymbolRef::Type> SymType = Sym.getType();
  85     if (!SymType) {
  86       consumeError(SymType.takeError());
  87       continue;
  88     }
  89     Expected<uint64_t> AddrOrErr = Sym.getValue();
  90     if (!AddrOrErr)
  91       // TODO: Test this error.
  92       return AddrOrErr.takeError();
  93
  94     if (SymType.get() != SymbolRef::Type::ST_Function ||
  95         !Gsym.IsValidTextAddress(*AddrOrErr) ||
  96         Gsym.hasFunctionInfoForAddress(*AddrOrErr))
  97       continue;
  98     // Function size for MachO files will be 0
  99     constexpr bool NoCopy = false;
 100     const uint64_t size = IsELF ? ELFSymbolRef(Sym).getSize() : 0;
 101     Expected<StringRef> Name = Sym.getName();
 102     if (!Name) {
 103       logAllUnhandledErrors(Name.takeError(), Log, "ObjectFileTransformer: ");
 104       continue;
 105     }
 106     // Remove the leading '_' character in any symbol names if there is one
 107     // for mach-o files.
 108     if (IsMachO)
 109       Name->consume_front("_");
 110     Gsym.addFunctionInfo(
 111         FunctionInfo(*AddrOrErr, size, Gsym.insertString(*Name, NoCopy)));
 112   }
 113   size_t FunctionsAddedCount = Gsym.getNumFunctionInfos() - NumBefore;
 114   Log << "Loaded " << FunctionsAddedCount << " functions from symbol table.\n";
 115   return Error::success();
 116 }