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 "llvm/Object/ELFObjectFile.h"
10#include "llvm/Object/MachOUniversal.h"
11#include "llvm/Object/ObjectFile.h"
12#include "llvm/Support/DataExtractor.h"
13#include "llvm/Support/raw_ostream.h"
14
15#include "llvm/DebugInfo/GSYM/GsymCreator.h"
16#include "llvm/DebugInfo/GSYM/ObjectFileTransformer.h"
17#include "llvm/DebugInfo/GSYM/OutputAggregator.h"
18
19using namespace llvm;
20using namespace gsym;
21
22constexpr uint32_t NT_GNU_BUILD_ID_TAG = 0x03;
23
24static std::vector<uint8_t> getUUID(const object::ObjectFile &Obj) {
25 // Extract the UUID from the object file
26 std::vector<uint8_t> UUID;
27 if (auto *MachO = dyn_cast<object::MachOObjectFile>(Val: &Obj)) {
28 const ArrayRef<uint8_t> MachUUID = MachO->getUuid();
29 if (!MachUUID.empty())
30 UUID.assign(first: MachUUID.data(), last: MachUUID.data() + MachUUID.size());
31 } else if (isa<object::ELFObjectFileBase>(Val: &Obj)) {
32 const StringRef GNUBuildID(".note.gnu.build-id");
33 for (const object::SectionRef &Sect : Obj.sections()) {
34 Expected<StringRef> SectNameOrErr = Sect.getName();
35 if (!SectNameOrErr) {
36 consumeError(Err: SectNameOrErr.takeError());
37 continue;
38 }
39 StringRef SectName(*SectNameOrErr);
40 if (SectName != GNUBuildID)
41 continue;
42 StringRef BuildIDData;
43 Expected<StringRef> E = Sect.getContents();
44 if (E)
45 BuildIDData = *E;
46 else {
47 consumeError(Err: E.takeError());
48 continue;
49 }
50 DataExtractor Decoder(BuildIDData, Obj.makeTriple().isLittleEndian(), 8);
51 uint64_t Offset = 0;
52 const uint32_t NameSize = Decoder.getU32(offset_ptr: &Offset);
53 const uint32_t PayloadSize = Decoder.getU32(offset_ptr: &Offset);
54 const uint32_t PayloadType = Decoder.getU32(offset_ptr: &Offset);
55 StringRef Name(Decoder.getFixedLengthString(OffsetPtr: &Offset, Length: NameSize));
56 if (Name == "GNU" && PayloadType == NT_GNU_BUILD_ID_TAG) {
57 Offset = alignTo(Value: Offset, Align: 4);
58 StringRef UUIDBytes(Decoder.getBytes(OffsetPtr: &Offset, Length: PayloadSize));
59 if (!UUIDBytes.empty()) {
60 auto Ptr = reinterpret_cast<const uint8_t *>(UUIDBytes.data());
61 UUID.assign(first: Ptr, last: Ptr + UUIDBytes.size());
62 }
63 }
64 }
65 }
66 return UUID;
67}
68
69llvm::Error ObjectFileTransformer::convert(const object::ObjectFile &Obj,
70 OutputAggregator &Out,
71 GsymCreator &Gsym) {
72 using namespace llvm::object;
73
74 const bool IsMachO = isa<MachOObjectFile>(Val: &Obj);
75 const bool IsELF = isa<ELFObjectFileBase>(Val: &Obj);
76
77 // Read build ID.
78 Gsym.setUUID(getUUID(Obj));
79
80 // Parse the symbol table.
81 size_t NumBefore = Gsym.getNumFunctionInfos();
82 for (const object::SymbolRef &Sym : Obj.symbols()) {
83 Expected<SymbolRef::Type> SymType = Sym.getType();
84 if (!SymType) {
85 consumeError(Err: SymType.takeError());
86 continue;
87 }
88 Expected<uint64_t> AddrOrErr = Sym.getValue();
89 if (!AddrOrErr)
90 // TODO: Test this error.
91 return AddrOrErr.takeError();
92
93 if (SymType.get() != SymbolRef::Type::ST_Function ||
94 !Gsym.IsValidTextAddress(Addr: *AddrOrErr))
95 continue;
96 // Function size for MachO files will be 0
97 constexpr bool NoCopy = false;
98 const uint64_t size = IsELF ? ELFSymbolRef(Sym).getSize() : 0;
99 Expected<StringRef> Name = Sym.getName();
100 if (!Name) {
101 if (Out.GetOS())
102 logAllUnhandledErrors(E: Name.takeError(), OS&: *Out.GetOS(),
103 ErrorBanner: "ObjectFileTransformer: ");
104 else
105 consumeError(Err: Name.takeError());
106 continue;
107 }
108 // Remove the leading '_' character in any symbol names if there is one
109 // for mach-o files.
110 if (IsMachO)
111 Name->consume_front(Prefix: "_");
112 Gsym.addFunctionInfo(
113 FI: FunctionInfo(*AddrOrErr, size, Gsym.insertString(S: *Name, Copy: NoCopy)));
114 }
115 size_t FunctionsAddedCount = Gsym.getNumFunctionInfos() - NumBefore;
116 if (Out.GetOS())
117 *Out.GetOS() << "Loaded " << FunctionsAddedCount
118 << " functions from symbol table.\n";
119 return Error::success();
120}
121