1 //===-- SymbolizableObjectFile.cpp ----------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Implementation of SymbolizableObjectFile class.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "SymbolizableObjectFile.h"
15 #include "llvm/Object/COFF.h"
16 #include "llvm/Object/SymbolSize.h"
17 #include "llvm/Support/DataExtractor.h"
18 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
19
20 namespace llvm {
21 namespace symbolize {
22
23 using namespace object;
24
25 static DILineInfoSpecifier
getDILineInfoSpecifier(FunctionNameKind FNKind)26 getDILineInfoSpecifier(FunctionNameKind FNKind) {
27 return DILineInfoSpecifier(
28 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FNKind);
29 }
30
31 ErrorOr<std::unique_ptr<SymbolizableObjectFile>>
create(object::ObjectFile * Obj,std::unique_ptr<DIContext> DICtx)32 SymbolizableObjectFile::create(object::ObjectFile *Obj,
33 std::unique_ptr<DIContext> DICtx) {
34 std::unique_ptr<SymbolizableObjectFile> res(
35 new SymbolizableObjectFile(Obj, std::move(DICtx)));
36 std::unique_ptr<DataExtractor> OpdExtractor;
37 uint64_t OpdAddress = 0;
38 // Find the .opd (function descriptor) section if any, for big-endian
39 // PowerPC64 ELF.
40 if (Obj->getArch() == Triple::ppc64) {
41 for (section_iterator Section : Obj->sections()) {
42 StringRef Name;
43 StringRef Data;
44 if (auto EC = Section->getName(Name))
45 return EC;
46 if (Name == ".opd") {
47 if (auto EC = Section->getContents(Data))
48 return EC;
49 OpdExtractor.reset(new DataExtractor(Data, Obj->isLittleEndian(),
50 Obj->getBytesInAddress()));
51 OpdAddress = Section->getAddress();
52 break;
53 }
54 }
55 }
56 std::vector<std::pair<SymbolRef, uint64_t>> Symbols =
57 computeSymbolSizes(*Obj);
58 for (auto &P : Symbols)
59 res->addSymbol(P.first, P.second, OpdExtractor.get(), OpdAddress);
60
61 // If this is a COFF object and we didn't find any symbols, try the export
62 // table.
63 if (Symbols.empty()) {
64 if (auto *CoffObj = dyn_cast<COFFObjectFile>(Obj))
65 if (auto EC = res->addCoffExportSymbols(CoffObj))
66 return EC;
67 }
68 return std::move(res);
69 }
70
SymbolizableObjectFile(ObjectFile * Obj,std::unique_ptr<DIContext> DICtx)71 SymbolizableObjectFile::SymbolizableObjectFile(ObjectFile *Obj,
72 std::unique_ptr<DIContext> DICtx)
73 : Module(Obj), DebugInfoContext(std::move(DICtx)) {}
74
75 namespace {
76 struct OffsetNamePair {
77 uint32_t Offset;
78 StringRef Name;
operator <llvm::symbolize::__anonfd7b95a20111::OffsetNamePair79 bool operator<(const OffsetNamePair &R) const {
80 return Offset < R.Offset;
81 }
82 };
83 }
84
addCoffExportSymbols(const COFFObjectFile * CoffObj)85 std::error_code SymbolizableObjectFile::addCoffExportSymbols(
86 const COFFObjectFile *CoffObj) {
87 // Get all export names and offsets.
88 std::vector<OffsetNamePair> ExportSyms;
89 for (const ExportDirectoryEntryRef &Ref : CoffObj->export_directories()) {
90 StringRef Name;
91 uint32_t Offset;
92 if (auto EC = Ref.getSymbolName(Name))
93 return EC;
94 if (auto EC = Ref.getExportRVA(Offset))
95 return EC;
96 ExportSyms.push_back(OffsetNamePair{Offset, Name});
97 }
98 if (ExportSyms.empty())
99 return std::error_code();
100
101 // Sort by ascending offset.
102 array_pod_sort(ExportSyms.begin(), ExportSyms.end());
103
104 // Approximate the symbol sizes by assuming they run to the next symbol.
105 // FIXME: This assumes all exports are functions.
106 uint64_t ImageBase = CoffObj->getImageBase();
107 for (auto I = ExportSyms.begin(), E = ExportSyms.end(); I != E; ++I) {
108 OffsetNamePair &Export = *I;
109 // FIXME: The last export has a one byte size now.
110 uint32_t NextOffset = I != E ? I->Offset : Export.Offset + 1;
111 uint64_t SymbolStart = ImageBase + Export.Offset;
112 uint64_t SymbolSize = NextOffset - Export.Offset;
113 SymbolDesc SD = {SymbolStart, SymbolSize};
114 Functions.insert(std::make_pair(SD, Export.Name));
115 }
116 return std::error_code();
117 }
118
addSymbol(const SymbolRef & Symbol,uint64_t SymbolSize,DataExtractor * OpdExtractor,uint64_t OpdAddress)119 std::error_code SymbolizableObjectFile::addSymbol(const SymbolRef &Symbol,
120 uint64_t SymbolSize,
121 DataExtractor *OpdExtractor,
122 uint64_t OpdAddress) {
123 Expected<SymbolRef::Type> SymbolTypeOrErr = Symbol.getType();
124 if (!SymbolTypeOrErr)
125 return errorToErrorCode(SymbolTypeOrErr.takeError());
126 SymbolRef::Type SymbolType = *SymbolTypeOrErr;
127 if (SymbolType != SymbolRef::ST_Function && SymbolType != SymbolRef::ST_Data)
128 return std::error_code();
129 Expected<uint64_t> SymbolAddressOrErr = Symbol.getAddress();
130 if (!SymbolAddressOrErr)
131 return errorToErrorCode(SymbolAddressOrErr.takeError());
132 uint64_t SymbolAddress = *SymbolAddressOrErr;
133 if (OpdExtractor) {
134 // For big-endian PowerPC64 ELF, symbols in the .opd section refer to
135 // function descriptors. The first word of the descriptor is a pointer to
136 // the function's code.
137 // For the purposes of symbolization, pretend the symbol's address is that
138 // of the function's code, not the descriptor.
139 uint64_t OpdOffset = SymbolAddress - OpdAddress;
140 uint32_t OpdOffset32 = OpdOffset;
141 if (OpdOffset == OpdOffset32 &&
142 OpdExtractor->isValidOffsetForAddress(OpdOffset32))
143 SymbolAddress = OpdExtractor->getAddress(&OpdOffset32);
144 }
145 Expected<StringRef> SymbolNameOrErr = Symbol.getName();
146 if (!SymbolNameOrErr)
147 return errorToErrorCode(SymbolNameOrErr.takeError());
148 StringRef SymbolName = *SymbolNameOrErr;
149 // Mach-O symbol table names have leading underscore, skip it.
150 if (Module->isMachO() && SymbolName.size() > 0 && SymbolName[0] == '_')
151 SymbolName = SymbolName.drop_front();
152 // FIXME: If a function has alias, there are two entries in symbol table
153 // with same address size. Make sure we choose the correct one.
154 auto &M = SymbolType == SymbolRef::ST_Function ? Functions : Objects;
155 SymbolDesc SD = { SymbolAddress, SymbolSize };
156 M.insert(std::make_pair(SD, SymbolName));
157 return std::error_code();
158 }
159
160 // Return true if this is a 32-bit x86 PE COFF module.
isWin32Module() const161 bool SymbolizableObjectFile::isWin32Module() const {
162 auto *CoffObject = dyn_cast<COFFObjectFile>(Module);
163 return CoffObject && CoffObject->getMachine() == COFF::IMAGE_FILE_MACHINE_I386;
164 }
165
getModulePreferredBase() const166 uint64_t SymbolizableObjectFile::getModulePreferredBase() const {
167 if (auto *CoffObject = dyn_cast<COFFObjectFile>(Module))
168 return CoffObject->getImageBase();
169 return 0;
170 }
171
getNameFromSymbolTable(SymbolRef::Type Type,uint64_t Address,std::string & Name,uint64_t & Addr,uint64_t & Size) const172 bool SymbolizableObjectFile::getNameFromSymbolTable(SymbolRef::Type Type,
173 uint64_t Address,
174 std::string &Name,
175 uint64_t &Addr,
176 uint64_t &Size) const {
177 const auto &SymbolMap = Type == SymbolRef::ST_Function ? Functions : Objects;
178 if (SymbolMap.empty())
179 return false;
180 SymbolDesc SD = { Address, Address };
181 auto SymbolIterator = SymbolMap.upper_bound(SD);
182 if (SymbolIterator == SymbolMap.begin())
183 return false;
184 --SymbolIterator;
185 if (SymbolIterator->first.Size != 0 &&
186 SymbolIterator->first.Addr + SymbolIterator->first.Size <= Address)
187 return false;
188 Name = SymbolIterator->second.str();
189 Addr = SymbolIterator->first.Addr;
190 Size = SymbolIterator->first.Size;
191 return true;
192 }
193
shouldOverrideWithSymbolTable(FunctionNameKind FNKind,bool UseSymbolTable) const194 bool SymbolizableObjectFile::shouldOverrideWithSymbolTable(
195 FunctionNameKind FNKind, bool UseSymbolTable) const {
196 // When DWARF is used with -gline-tables-only / -gmlt, the symbol table gives
197 // better answers for linkage names than the DIContext. Otherwise, we are
198 // probably using PEs and PDBs, and we shouldn't do the override. PE files
199 // generally only contain the names of exported symbols.
200 return FNKind == FunctionNameKind::LinkageName && UseSymbolTable &&
201 isa<DWARFContext>(DebugInfoContext.get());
202 }
203
symbolizeCode(uint64_t ModuleOffset,FunctionNameKind FNKind,bool UseSymbolTable) const204 DILineInfo SymbolizableObjectFile::symbolizeCode(uint64_t ModuleOffset,
205 FunctionNameKind FNKind,
206 bool UseSymbolTable) const {
207 DILineInfo LineInfo;
208 if (DebugInfoContext) {
209 LineInfo = DebugInfoContext->getLineInfoForAddress(
210 ModuleOffset, getDILineInfoSpecifier(FNKind));
211 }
212 // Override function name from symbol table if necessary.
213 if (shouldOverrideWithSymbolTable(FNKind, UseSymbolTable)) {
214 std::string FunctionName;
215 uint64_t Start, Size;
216 if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
217 FunctionName, Start, Size)) {
218 LineInfo.FunctionName = FunctionName;
219 }
220 }
221 return LineInfo;
222 }
223
symbolizeInlinedCode(uint64_t ModuleOffset,FunctionNameKind FNKind,bool UseSymbolTable) const224 DIInliningInfo SymbolizableObjectFile::symbolizeInlinedCode(
225 uint64_t ModuleOffset, FunctionNameKind FNKind, bool UseSymbolTable) const {
226 DIInliningInfo InlinedContext;
227
228 if (DebugInfoContext)
229 InlinedContext = DebugInfoContext->getInliningInfoForAddress(
230 ModuleOffset, getDILineInfoSpecifier(FNKind));
231 // Make sure there is at least one frame in context.
232 if (InlinedContext.getNumberOfFrames() == 0)
233 InlinedContext.addFrame(DILineInfo());
234
235 // Override the function name in lower frame with name from symbol table.
236 if (shouldOverrideWithSymbolTable(FNKind, UseSymbolTable)) {
237 std::string FunctionName;
238 uint64_t Start, Size;
239 if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
240 FunctionName, Start, Size)) {
241 InlinedContext.getMutableFrame(InlinedContext.getNumberOfFrames() - 1)
242 ->FunctionName = FunctionName;
243 }
244 }
245
246 return InlinedContext;
247 }
248
symbolizeData(uint64_t ModuleOffset) const249 DIGlobal SymbolizableObjectFile::symbolizeData(uint64_t ModuleOffset) const {
250 DIGlobal Res;
251 getNameFromSymbolTable(SymbolRef::ST_Data, ModuleOffset, Res.Name, Res.Start,
252 Res.Size);
253 return Res;
254 }
255
256 } // namespace symbolize
257 } // namespace llvm
258
259