1 //===-- ELFDump.cpp - ELF-specific dumper -----------------------*- 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 /// \file 10 /// This file implements the ELF-specific dumper for llvm-objdump. 11 /// 12 //===----------------------------------------------------------------------===// 13 14 #include "ELFDump.h" 15 16 #include "llvm-objdump.h" 17 #include "llvm/Demangle/Demangle.h" 18 #include "llvm/Object/ELFObjectFile.h" 19 #include "llvm/Support/Format.h" 20 #include "llvm/Support/MathExtras.h" 21 #include "llvm/Support/raw_ostream.h" 22 23 using namespace llvm; 24 using namespace llvm::object; 25 using namespace llvm::objdump; 26 27 template <class ELFT> 28 static Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> &Elf) { 29 auto DynamicEntriesOrError = Elf.dynamicEntries(); 30 if (!DynamicEntriesOrError) 31 return DynamicEntriesOrError.takeError(); 32 33 for (const typename ELFT::Dyn &Dyn : *DynamicEntriesOrError) { 34 if (Dyn.d_tag == ELF::DT_STRTAB) { 35 auto MappedAddrOrError = Elf.toMappedAddr(Dyn.getPtr()); 36 if (!MappedAddrOrError) 37 consumeError(MappedAddrOrError.takeError()); 38 return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError)); 39 } 40 } 41 42 // If the dynamic segment is not present, we fall back on the sections. 43 auto SectionsOrError = Elf.sections(); 44 if (!SectionsOrError) 45 return SectionsOrError.takeError(); 46 47 for (const typename ELFT::Shdr &Sec : *SectionsOrError) { 48 if (Sec.sh_type == ELF::SHT_DYNSYM) 49 return Elf.getStringTableForSymtab(Sec); 50 } 51 52 return createError("dynamic string table not found"); 53 } 54 55 template <class ELFT> 56 static Error getRelocationValueString(const ELFObjectFile<ELFT> *Obj, 57 const RelocationRef &RelRef, 58 SmallVectorImpl<char> &Result) { 59 const ELFFile<ELFT> &EF = Obj->getELFFile(); 60 DataRefImpl Rel = RelRef.getRawDataRefImpl(); 61 auto SecOrErr = EF.getSection(Rel.d.a); 62 if (!SecOrErr) 63 return SecOrErr.takeError(); 64 65 int64_t Addend = 0; 66 // If there is no Symbol associated with the relocation, we set the undef 67 // boolean value to 'true'. This will prevent us from calling functions that 68 // requires the relocation to be associated with a symbol. 69 // 70 // In SHT_REL case we would need to read the addend from section data. 71 // GNU objdump does not do that and we just follow for simplicity atm. 72 bool Undef = false; 73 if ((*SecOrErr)->sh_type == ELF::SHT_RELA) { 74 const typename ELFT::Rela *ERela = Obj->getRela(Rel); 75 Addend = ERela->r_addend; 76 Undef = ERela->getSymbol(false) == 0; 77 } else if ((*SecOrErr)->sh_type == ELF::SHT_REL) { 78 const typename ELFT::Rel *ERel = Obj->getRel(Rel); 79 Undef = ERel->getSymbol(false) == 0; 80 } else { 81 return make_error<BinaryError>(); 82 } 83 84 // Default scheme is to print Target, as well as "+ <addend>" for nonzero 85 // addend. Should be acceptable for all normal purposes. 86 std::string FmtBuf; 87 raw_string_ostream Fmt(FmtBuf); 88 89 if (!Undef) { 90 symbol_iterator SI = RelRef.getSymbol(); 91 Expected<const typename ELFT::Sym *> SymOrErr = 92 Obj->getSymbol(SI->getRawDataRefImpl()); 93 // TODO: test this error. 94 if (!SymOrErr) 95 return SymOrErr.takeError(); 96 97 if ((*SymOrErr)->getType() == ELF::STT_SECTION) { 98 Expected<section_iterator> SymSI = SI->getSection(); 99 if (!SymSI) 100 return SymSI.takeError(); 101 const typename ELFT::Shdr *SymSec = 102 Obj->getSection((*SymSI)->getRawDataRefImpl()); 103 auto SecName = EF.getSectionName(*SymSec); 104 if (!SecName) 105 return SecName.takeError(); 106 Fmt << *SecName; 107 } else { 108 Expected<StringRef> SymName = SI->getName(); 109 if (!SymName) 110 return SymName.takeError(); 111 if (Demangle) 112 Fmt << demangle(std::string(*SymName)); 113 else 114 Fmt << *SymName; 115 } 116 } else { 117 Fmt << "*ABS*"; 118 } 119 if (Addend != 0) { 120 Fmt << (Addend < 0 121 ? "-" 122 : "+") << format("0x%" PRIx64, 123 (Addend < 0 ? -(uint64_t)Addend : (uint64_t)Addend)); 124 } 125 Fmt.flush(); 126 Result.append(FmtBuf.begin(), FmtBuf.end()); 127 return Error::success(); 128 } 129 130 Error objdump::getELFRelocationValueString(const ELFObjectFileBase *Obj, 131 const RelocationRef &Rel, 132 SmallVectorImpl<char> &Result) { 133 if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj)) 134 return getRelocationValueString(ELF32LE, Rel, Result); 135 if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj)) 136 return getRelocationValueString(ELF64LE, Rel, Result); 137 if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj)) 138 return getRelocationValueString(ELF32BE, Rel, Result); 139 auto *ELF64BE = cast<ELF64BEObjectFile>(Obj); 140 return getRelocationValueString(ELF64BE, Rel, Result); 141 } 142 143 template <class ELFT> 144 static uint64_t getSectionLMA(const ELFFile<ELFT> &Obj, 145 const object::ELFSectionRef &Sec) { 146 auto PhdrRangeOrErr = Obj.program_headers(); 147 if (!PhdrRangeOrErr) 148 report_fatal_error(Twine(toString(PhdrRangeOrErr.takeError()))); 149 150 // Search for a PT_LOAD segment containing the requested section. Use this 151 // segment's p_addr to calculate the section's LMA. 152 for (const typename ELFT::Phdr &Phdr : *PhdrRangeOrErr) 153 if ((Phdr.p_type == ELF::PT_LOAD) && (Phdr.p_vaddr <= Sec.getAddress()) && 154 (Phdr.p_vaddr + Phdr.p_memsz > Sec.getAddress())) 155 return Sec.getAddress() - Phdr.p_vaddr + Phdr.p_paddr; 156 157 // Return section's VMA if it isn't in a PT_LOAD segment. 158 return Sec.getAddress(); 159 } 160 161 uint64_t objdump::getELFSectionLMA(const object::ELFSectionRef &Sec) { 162 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Sec.getObject())) 163 return getSectionLMA(ELFObj->getELFFile(), Sec); 164 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Sec.getObject())) 165 return getSectionLMA(ELFObj->getELFFile(), Sec); 166 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Sec.getObject())) 167 return getSectionLMA(ELFObj->getELFFile(), Sec); 168 const auto *ELFObj = cast<ELF64BEObjectFile>(Sec.getObject()); 169 return getSectionLMA(ELFObj->getELFFile(), Sec); 170 } 171 172 template <class ELFT> 173 static void printDynamicSection(const ELFFile<ELFT> &Elf, StringRef Filename) { 174 auto DynamicEntriesOrErr = Elf.dynamicEntries(); 175 if (!DynamicEntriesOrErr) { 176 reportWarning(toString(DynamicEntriesOrErr.takeError()), Filename); 177 return; 178 } 179 ArrayRef<typename ELFT::Dyn> DynamicEntries = *DynamicEntriesOrErr; 180 181 // Find the maximum tag name length to format the value column properly. 182 size_t MaxLen = 0; 183 for (const typename ELFT::Dyn &Dyn : DynamicEntries) 184 MaxLen = std::max(MaxLen, Elf.getDynamicTagAsString(Dyn.d_tag).size()); 185 std::string TagFmt = " %-" + std::to_string(MaxLen) + "s "; 186 187 outs() << "\nDynamic Section:\n"; 188 for (const typename ELFT::Dyn &Dyn : DynamicEntries) { 189 if (Dyn.d_tag == ELF::DT_NULL) 190 continue; 191 192 std::string Str = Elf.getDynamicTagAsString(Dyn.d_tag); 193 outs() << format(TagFmt.c_str(), Str.c_str()); 194 195 const char *Fmt = 196 ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n"; 197 if (Dyn.d_tag == ELF::DT_NEEDED || Dyn.d_tag == ELF::DT_RPATH || 198 Dyn.d_tag == ELF::DT_RUNPATH || Dyn.d_tag == ELF::DT_SONAME || 199 Dyn.d_tag == ELF::DT_AUXILIARY || Dyn.d_tag == ELF::DT_FILTER) { 200 Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf); 201 if (StrTabOrErr) { 202 const char *Data = StrTabOrErr.get().data(); 203 outs() << (Data + Dyn.d_un.d_val) << "\n"; 204 continue; 205 } 206 reportWarning(toString(StrTabOrErr.takeError()), Filename); 207 consumeError(StrTabOrErr.takeError()); 208 } 209 outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val); 210 } 211 } 212 213 template <class ELFT> 214 static void printProgramHeaders(const ELFFile<ELFT> &Obj, StringRef FileName) { 215 outs() << "\nProgram Header:\n"; 216 auto ProgramHeaderOrError = Obj.program_headers(); 217 if (!ProgramHeaderOrError) { 218 reportWarning("unable to read program headers: " + 219 toString(ProgramHeaderOrError.takeError()), 220 FileName); 221 return; 222 } 223 224 for (const typename ELFT::Phdr &Phdr : *ProgramHeaderOrError) { 225 switch (Phdr.p_type) { 226 case ELF::PT_DYNAMIC: 227 outs() << " DYNAMIC "; 228 break; 229 case ELF::PT_GNU_EH_FRAME: 230 outs() << "EH_FRAME "; 231 break; 232 case ELF::PT_GNU_RELRO: 233 outs() << " RELRO "; 234 break; 235 case ELF::PT_GNU_PROPERTY: 236 outs() << " PROPERTY "; 237 break; 238 case ELF::PT_GNU_STACK: 239 outs() << " STACK "; 240 break; 241 case ELF::PT_INTERP: 242 outs() << " INTERP "; 243 break; 244 case ELF::PT_LOAD: 245 outs() << " LOAD "; 246 break; 247 case ELF::PT_NOTE: 248 outs() << " NOTE "; 249 break; 250 case ELF::PT_OPENBSD_BOOTDATA: 251 outs() << " OPENBSD_BOOTDATA "; 252 break; 253 case ELF::PT_OPENBSD_RANDOMIZE: 254 outs() << " OPENBSD_RANDOMIZE "; 255 break; 256 case ELF::PT_OPENBSD_WXNEEDED: 257 outs() << " OPENBSD_WXNEEDED "; 258 break; 259 case ELF::PT_PHDR: 260 outs() << " PHDR "; 261 break; 262 case ELF::PT_TLS: 263 outs() << " TLS "; 264 break; 265 default: 266 outs() << " UNKNOWN "; 267 } 268 269 const char *Fmt = ELFT::Is64Bits ? "0x%016" PRIx64 " " : "0x%08" PRIx64 " "; 270 271 outs() << "off " << format(Fmt, (uint64_t)Phdr.p_offset) << "vaddr " 272 << format(Fmt, (uint64_t)Phdr.p_vaddr) << "paddr " 273 << format(Fmt, (uint64_t)Phdr.p_paddr) 274 << format("align 2**%u\n", 275 countTrailingZeros<uint64_t>(Phdr.p_align)) 276 << " filesz " << format(Fmt, (uint64_t)Phdr.p_filesz) 277 << "memsz " << format(Fmt, (uint64_t)Phdr.p_memsz) << "flags " 278 << ((Phdr.p_flags & ELF::PF_R) ? "r" : "-") 279 << ((Phdr.p_flags & ELF::PF_W) ? "w" : "-") 280 << ((Phdr.p_flags & ELF::PF_X) ? "x" : "-") << "\n"; 281 } 282 } 283 284 template <class ELFT> 285 static void printSymbolVersionDependency(ArrayRef<uint8_t> Contents, 286 StringRef StrTab) { 287 outs() << "\nVersion References:\n"; 288 289 const uint8_t *Buf = Contents.data(); 290 while (Buf) { 291 auto *Verneed = reinterpret_cast<const typename ELFT::Verneed *>(Buf); 292 outs() << " required from " 293 << StringRef(StrTab.drop_front(Verneed->vn_file).data()) << ":\n"; 294 295 const uint8_t *BufAux = Buf + Verneed->vn_aux; 296 while (BufAux) { 297 auto *Vernaux = reinterpret_cast<const typename ELFT::Vernaux *>(BufAux); 298 outs() << " " 299 << format("0x%08" PRIx32 " ", (uint32_t)Vernaux->vna_hash) 300 << format("0x%02" PRIx16 " ", (uint16_t)Vernaux->vna_flags) 301 << format("%02" PRIu16 " ", (uint16_t)Vernaux->vna_other) 302 << StringRef(StrTab.drop_front(Vernaux->vna_name).data()) << '\n'; 303 BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr; 304 } 305 Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr; 306 } 307 } 308 309 template <class ELFT> 310 static void printSymbolVersionDefinition(const typename ELFT::Shdr &Shdr, 311 ArrayRef<uint8_t> Contents, 312 StringRef StrTab) { 313 outs() << "\nVersion definitions:\n"; 314 315 const uint8_t *Buf = Contents.data(); 316 uint32_t VerdefIndex = 1; 317 // sh_info contains the number of entries in the SHT_GNU_verdef section. To 318 // make the index column have consistent width, we should insert blank spaces 319 // according to sh_info. 320 uint16_t VerdefIndexWidth = std::to_string(Shdr.sh_info).size(); 321 while (Buf) { 322 auto *Verdef = reinterpret_cast<const typename ELFT::Verdef *>(Buf); 323 outs() << format_decimal(VerdefIndex++, VerdefIndexWidth) << " " 324 << format("0x%02" PRIx16 " ", (uint16_t)Verdef->vd_flags) 325 << format("0x%08" PRIx32 " ", (uint32_t)Verdef->vd_hash); 326 327 const uint8_t *BufAux = Buf + Verdef->vd_aux; 328 uint16_t VerdauxIndex = 0; 329 while (BufAux) { 330 auto *Verdaux = reinterpret_cast<const typename ELFT::Verdaux *>(BufAux); 331 if (VerdauxIndex) 332 outs() << std::string(VerdefIndexWidth + 17, ' '); 333 outs() << StringRef(StrTab.drop_front(Verdaux->vda_name).data()) << '\n'; 334 BufAux = Verdaux->vda_next ? BufAux + Verdaux->vda_next : nullptr; 335 ++VerdauxIndex; 336 } 337 Buf = Verdef->vd_next ? Buf + Verdef->vd_next : nullptr; 338 } 339 } 340 341 template <class ELFT> 342 static void printSymbolVersionInfo(const ELFFile<ELFT> &Elf, 343 StringRef FileName) { 344 ArrayRef<typename ELFT::Shdr> Sections = 345 unwrapOrError(Elf.sections(), FileName); 346 for (const typename ELFT::Shdr &Shdr : Sections) { 347 if (Shdr.sh_type != ELF::SHT_GNU_verneed && 348 Shdr.sh_type != ELF::SHT_GNU_verdef) 349 continue; 350 351 ArrayRef<uint8_t> Contents = 352 unwrapOrError(Elf.getSectionContents(Shdr), FileName); 353 const typename ELFT::Shdr *StrTabSec = 354 unwrapOrError(Elf.getSection(Shdr.sh_link), FileName); 355 StringRef StrTab = unwrapOrError(Elf.getStringTable(*StrTabSec), FileName); 356 357 if (Shdr.sh_type == ELF::SHT_GNU_verneed) 358 printSymbolVersionDependency<ELFT>(Contents, StrTab); 359 else 360 printSymbolVersionDefinition<ELFT>(Shdr, Contents, StrTab); 361 } 362 } 363 364 void objdump::printELFFileHeader(const object::ObjectFile *Obj) { 365 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj)) 366 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 367 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj)) 368 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 369 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj)) 370 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 371 else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj)) 372 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 373 } 374 375 void objdump::printELFDynamicSection(const object::ObjectFile *Obj) { 376 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj)) 377 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 378 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj)) 379 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 380 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj)) 381 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 382 else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj)) 383 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 384 } 385 386 void objdump::printELFSymbolVersionInfo(const object::ObjectFile *Obj) { 387 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj)) 388 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 389 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj)) 390 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 391 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj)) 392 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 393 else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj)) 394 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 395 } 396