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/SymbolSize.h"
16 #include "llvm/Support/DataExtractor.h"
17 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
18
19 namespace llvm {
20 namespace symbolize {
21
22 using namespace object;
23
24 static DILineInfoSpecifier
getDILineInfoSpecifier(FunctionNameKind FNKind)25 getDILineInfoSpecifier(FunctionNameKind FNKind) {
26 return DILineInfoSpecifier(
27 DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FNKind);
28 }
29
30 ErrorOr<std::unique_ptr<SymbolizableObjectFile>>
create(object::ObjectFile * Obj,std::unique_ptr<DIContext> DICtx)31 SymbolizableObjectFile::create(object::ObjectFile *Obj,
32 std::unique_ptr<DIContext> DICtx) {
33 std::unique_ptr<SymbolizableObjectFile> res(
34 new SymbolizableObjectFile(Obj, std::move(DICtx)));
35 std::unique_ptr<DataExtractor> OpdExtractor;
36 uint64_t OpdAddress = 0;
37 // Find the .opd (function descriptor) section if any, for big-endian
38 // PowerPC64 ELF.
39 if (Obj->getArch() == Triple::ppc64) {
40 for (section_iterator Section : Obj->sections()) {
41 StringRef Name;
42 StringRef Data;
43 if (auto EC = Section->getName(Name))
44 return EC;
45 if (Name == ".opd") {
46 if (auto EC = Section->getContents(Data))
47 return EC;
48 OpdExtractor.reset(new DataExtractor(Data, Obj->isLittleEndian(),
49 Obj->getBytesInAddress()));
50 OpdAddress = Section->getAddress();
51 break;
52 }
53 }
54 }
55 std::vector<std::pair<SymbolRef, uint64_t>> Symbols =
56 computeSymbolSizes(*Obj);
57 for (auto &P : Symbols)
58 res->addSymbol(P.first, P.second, OpdExtractor.get(), OpdAddress);
59
60 // If this is a COFF object and we didn't find any symbols, try the export
61 // table.
62 if (Symbols.empty()) {
63 if (auto *CoffObj = dyn_cast<COFFObjectFile>(Obj))
64 if (auto EC = res->addCoffExportSymbols(CoffObj))
65 return EC;
66 }
67 return std::move(res);
68 }
69
SymbolizableObjectFile(ObjectFile * Obj,std::unique_ptr<DIContext> DICtx)70 SymbolizableObjectFile::SymbolizableObjectFile(ObjectFile *Obj,
71 std::unique_ptr<DIContext> DICtx)
72 : Module(Obj), DebugInfoContext(std::move(DICtx)) {}
73
74 namespace {
75 struct OffsetNamePair {
76 uint32_t Offset;
77 StringRef Name;
operator <llvm::symbolize::__anon08cf6d2a0111::OffsetNamePair78 bool operator<(const OffsetNamePair &R) const {
79 return Offset < R.Offset;
80 }
81 };
82 }
83
addCoffExportSymbols(const COFFObjectFile * CoffObj)84 std::error_code SymbolizableObjectFile::addCoffExportSymbols(
85 const COFFObjectFile *CoffObj) {
86 // Get all export names and offsets.
87 std::vector<OffsetNamePair> ExportSyms;
88 for (const ExportDirectoryEntryRef &Ref : CoffObj->export_directories()) {
89 StringRef Name;
90 uint32_t Offset;
91 if (auto EC = Ref.getSymbolName(Name))
92 return EC;
93 if (auto EC = Ref.getExportRVA(Offset))
94 return EC;
95 ExportSyms.push_back(OffsetNamePair{Offset, Name});
96 }
97 if (ExportSyms.empty())
98 return std::error_code();
99
100 // Sort by ascending offset.
101 array_pod_sort(ExportSyms.begin(), ExportSyms.end());
102
103 // Approximate the symbol sizes by assuming they run to the next symbol.
104 // FIXME: This assumes all exports are functions.
105 uint64_t ImageBase = CoffObj->getImageBase();
106 for (auto I = ExportSyms.begin(), E = ExportSyms.end(); I != E; ++I) {
107 OffsetNamePair &Export = *I;
108 // FIXME: The last export has a one byte size now.
109 uint32_t NextOffset = I != E ? I->Offset : Export.Offset + 1;
110 uint64_t SymbolStart = ImageBase + Export.Offset;
111 uint64_t SymbolSize = NextOffset - Export.Offset;
112 SymbolDesc SD = {SymbolStart, SymbolSize};
113 Functions.insert(std::make_pair(SD, Export.Name));
114 }
115 return std::error_code();
116 }
117
addSymbol(const SymbolRef & Symbol,uint64_t SymbolSize,DataExtractor * OpdExtractor,uint64_t OpdAddress)118 std::error_code SymbolizableObjectFile::addSymbol(const SymbolRef &Symbol,
119 uint64_t SymbolSize,
120 DataExtractor *OpdExtractor,
121 uint64_t OpdAddress) {
122 SymbolRef::Type SymbolType = Symbol.getType();
123 if (SymbolType != SymbolRef::ST_Function && SymbolType != SymbolRef::ST_Data)
124 return std::error_code();
125 ErrorOr<uint64_t> SymbolAddressOrErr = Symbol.getAddress();
126 if (auto EC = SymbolAddressOrErr.getError())
127 return EC;
128 uint64_t SymbolAddress = *SymbolAddressOrErr;
129 if (OpdExtractor) {
130 // For big-endian PowerPC64 ELF, symbols in the .opd section refer to
131 // function descriptors. The first word of the descriptor is a pointer to
132 // the function's code.
133 // For the purposes of symbolization, pretend the symbol's address is that
134 // of the function's code, not the descriptor.
135 uint64_t OpdOffset = SymbolAddress - OpdAddress;
136 uint32_t OpdOffset32 = OpdOffset;
137 if (OpdOffset == OpdOffset32 &&
138 OpdExtractor->isValidOffsetForAddress(OpdOffset32))
139 SymbolAddress = OpdExtractor->getAddress(&OpdOffset32);
140 }
141 ErrorOr<StringRef> SymbolNameOrErr = Symbol.getName();
142 if (auto EC = SymbolNameOrErr.getError())
143 return EC;
144 StringRef SymbolName = *SymbolNameOrErr;
145 // Mach-O symbol table names have leading underscore, skip it.
146 if (Module->isMachO() && SymbolName.size() > 0 && SymbolName[0] == '_')
147 SymbolName = SymbolName.drop_front();
148 // FIXME: If a function has alias, there are two entries in symbol table
149 // with same address size. Make sure we choose the correct one.
150 auto &M = SymbolType == SymbolRef::ST_Function ? Functions : Objects;
151 SymbolDesc SD = { SymbolAddress, SymbolSize };
152 M.insert(std::make_pair(SD, SymbolName));
153 return std::error_code();
154 }
155
156 // Return true if this is a 32-bit x86 PE COFF module.
isWin32Module() const157 bool SymbolizableObjectFile::isWin32Module() const {
158 auto *CoffObject = dyn_cast<COFFObjectFile>(Module);
159 return CoffObject && CoffObject->getMachine() == COFF::IMAGE_FILE_MACHINE_I386;
160 }
161
getModulePreferredBase() const162 uint64_t SymbolizableObjectFile::getModulePreferredBase() const {
163 if (auto *CoffObject = dyn_cast<COFFObjectFile>(Module))
164 return CoffObject->getImageBase();
165 return 0;
166 }
167
getNameFromSymbolTable(SymbolRef::Type Type,uint64_t Address,std::string & Name,uint64_t & Addr,uint64_t & Size) const168 bool SymbolizableObjectFile::getNameFromSymbolTable(SymbolRef::Type Type,
169 uint64_t Address,
170 std::string &Name,
171 uint64_t &Addr,
172 uint64_t &Size) const {
173 const auto &SymbolMap = Type == SymbolRef::ST_Function ? Functions : Objects;
174 if (SymbolMap.empty())
175 return false;
176 SymbolDesc SD = { Address, Address };
177 auto SymbolIterator = SymbolMap.upper_bound(SD);
178 if (SymbolIterator == SymbolMap.begin())
179 return false;
180 --SymbolIterator;
181 if (SymbolIterator->first.Size != 0 &&
182 SymbolIterator->first.Addr + SymbolIterator->first.Size <= Address)
183 return false;
184 Name = SymbolIterator->second.str();
185 Addr = SymbolIterator->first.Addr;
186 Size = SymbolIterator->first.Size;
187 return true;
188 }
189
shouldOverrideWithSymbolTable(FunctionNameKind FNKind,bool UseSymbolTable) const190 bool SymbolizableObjectFile::shouldOverrideWithSymbolTable(
191 FunctionNameKind FNKind, bool UseSymbolTable) const {
192 // When DWARF is used with -gline-tables-only / -gmlt, the symbol table gives
193 // better answers for linkage names than the DIContext. Otherwise, we are
194 // probably using PEs and PDBs, and we shouldn't do the override. PE files
195 // generally only contain the names of exported symbols.
196 return FNKind == FunctionNameKind::LinkageName && UseSymbolTable &&
197 isa<DWARFContext>(DebugInfoContext.get());
198 }
199
symbolizeCode(uint64_t ModuleOffset,FunctionNameKind FNKind,bool UseSymbolTable) const200 DILineInfo SymbolizableObjectFile::symbolizeCode(uint64_t ModuleOffset,
201 FunctionNameKind FNKind,
202 bool UseSymbolTable) const {
203 DILineInfo LineInfo;
204 if (DebugInfoContext) {
205 LineInfo = DebugInfoContext->getLineInfoForAddress(
206 ModuleOffset, getDILineInfoSpecifier(FNKind));
207 }
208 // Override function name from symbol table if necessary.
209 if (shouldOverrideWithSymbolTable(FNKind, UseSymbolTable)) {
210 std::string FunctionName;
211 uint64_t Start, Size;
212 if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
213 FunctionName, Start, Size)) {
214 LineInfo.FunctionName = FunctionName;
215 }
216 }
217 return LineInfo;
218 }
219
symbolizeInlinedCode(uint64_t ModuleOffset,FunctionNameKind FNKind,bool UseSymbolTable) const220 DIInliningInfo SymbolizableObjectFile::symbolizeInlinedCode(
221 uint64_t ModuleOffset, FunctionNameKind FNKind, bool UseSymbolTable) const {
222 DIInliningInfo InlinedContext;
223
224 if (DebugInfoContext)
225 InlinedContext = DebugInfoContext->getInliningInfoForAddress(
226 ModuleOffset, getDILineInfoSpecifier(FNKind));
227 // Make sure there is at least one frame in context.
228 if (InlinedContext.getNumberOfFrames() == 0)
229 InlinedContext.addFrame(DILineInfo());
230
231 // Override the function name in lower frame with name from symbol table.
232 if (shouldOverrideWithSymbolTable(FNKind, UseSymbolTable)) {
233 std::string FunctionName;
234 uint64_t Start, Size;
235 if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
236 FunctionName, Start, Size)) {
237 InlinedContext.getMutableFrame(InlinedContext.getNumberOfFrames() - 1)
238 ->FunctionName = FunctionName;
239 }
240 }
241
242 return InlinedContext;
243 }
244
symbolizeData(uint64_t ModuleOffset) const245 DIGlobal SymbolizableObjectFile::symbolizeData(uint64_t ModuleOffset) const {
246 DIGlobal Res;
247 getNameFromSymbolTable(SymbolRef::ST_Data, ModuleOffset, Res.Name, Res.Start,
248 Res.Size);
249 return Res;
250 }
251
252 } // namespace symbolize
253 } // namespace llvm
254
255