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 return make_error<BinaryError>(); 79 } 80 81 // Default scheme is to print Target, as well as "+ <addend>" for nonzero 82 // addend. Should be acceptable for all normal purposes. 83 std::string FmtBuf; 84 raw_string_ostream Fmt(FmtBuf); 85 86 if (!Undef) { 87 symbol_iterator SI = RelRef.getSymbol(); 88 const typename ELFT::Sym *Sym = Obj->getSymbol(SI->getRawDataRefImpl()); 89 if (Sym->getType() == ELF::STT_SECTION) { 90 Expected<section_iterator> SymSI = SI->getSection(); 91 if (!SymSI) 92 return SymSI.takeError(); 93 const typename ELFT::Shdr *SymSec = 94 Obj->getSection((*SymSI)->getRawDataRefImpl()); 95 auto SecName = EF.getSectionName(SymSec); 96 if (!SecName) 97 return SecName.takeError(); 98 Fmt << *SecName; 99 } else { 100 Expected<StringRef> SymName = SI->getName(); 101 if (!SymName) 102 return SymName.takeError(); 103 if (Demangle) 104 Fmt << demangle(std::string(*SymName)); 105 else 106 Fmt << *SymName; 107 } 108 } else { 109 Fmt << "*ABS*"; 110 } 111 if (Addend != 0) { 112 Fmt << (Addend < 0 113 ? "-" 114 : "+") << format("0x%" PRIx64, 115 (Addend < 0 ? -(uint64_t)Addend : (uint64_t)Addend)); 116 } 117 Fmt.flush(); 118 Result.append(FmtBuf.begin(), FmtBuf.end()); 119 return Error::success(); 120 } 121 122 Error objdump::getELFRelocationValueString(const ELFObjectFileBase *Obj, 123 const RelocationRef &Rel, 124 SmallVectorImpl<char> &Result) { 125 if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj)) 126 return getRelocationValueString(ELF32LE, Rel, Result); 127 if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj)) 128 return getRelocationValueString(ELF64LE, Rel, Result); 129 if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj)) 130 return getRelocationValueString(ELF32BE, Rel, Result); 131 auto *ELF64BE = cast<ELF64BEObjectFile>(Obj); 132 return getRelocationValueString(ELF64BE, Rel, Result); 133 } 134 135 template <class ELFT> 136 static uint64_t getSectionLMA(const ELFFile<ELFT> *Obj, 137 const object::ELFSectionRef &Sec) { 138 auto PhdrRangeOrErr = Obj->program_headers(); 139 if (!PhdrRangeOrErr) 140 report_fatal_error(toString(PhdrRangeOrErr.takeError())); 141 142 // Search for a PT_LOAD segment containing the requested section. Use this 143 // segment's p_addr to calculate the section's LMA. 144 for (const typename ELFT::Phdr &Phdr : *PhdrRangeOrErr) 145 if ((Phdr.p_type == ELF::PT_LOAD) && (Phdr.p_vaddr <= Sec.getAddress()) && 146 (Phdr.p_vaddr + Phdr.p_memsz > Sec.getAddress())) 147 return Sec.getAddress() - Phdr.p_vaddr + Phdr.p_paddr; 148 149 // Return section's VMA if it isn't in a PT_LOAD segment. 150 return Sec.getAddress(); 151 } 152 153 uint64_t objdump::getELFSectionLMA(const object::ELFSectionRef &Sec) { 154 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Sec.getObject())) 155 return getSectionLMA(ELFObj->getELFFile(), Sec); 156 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Sec.getObject())) 157 return getSectionLMA(ELFObj->getELFFile(), Sec); 158 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Sec.getObject())) 159 return getSectionLMA(ELFObj->getELFFile(), Sec); 160 const auto *ELFObj = cast<ELF64BEObjectFile>(Sec.getObject()); 161 return getSectionLMA(ELFObj->getELFFile(), Sec); 162 } 163 164 template <class ELFT> 165 static void printDynamicSection(const ELFFile<ELFT> *Elf, StringRef Filename) { 166 ArrayRef<typename ELFT::Dyn> DynamicEntries = 167 unwrapOrError(Elf->dynamicEntries(), Filename); 168 169 // Find the maximum tag name length to format the value column properly. 170 size_t MaxLen = 0; 171 for (const typename ELFT::Dyn &Dyn : DynamicEntries) 172 MaxLen = std::max(MaxLen, Elf->getDynamicTagAsString(Dyn.d_tag).size()); 173 std::string TagFmt = " %-" + std::to_string(MaxLen) + "s "; 174 175 outs() << "Dynamic Section:\n"; 176 for (const typename ELFT::Dyn &Dyn : DynamicEntries) { 177 if (Dyn.d_tag == ELF::DT_NULL) 178 continue; 179 180 std::string Str = Elf->getDynamicTagAsString(Dyn.d_tag); 181 outs() << format(TagFmt.c_str(), Str.c_str()); 182 183 const char *Fmt = 184 ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n"; 185 if (Dyn.d_tag == ELF::DT_NEEDED || Dyn.d_tag == ELF::DT_RPATH || 186 Dyn.d_tag == ELF::DT_RUNPATH || Dyn.d_tag == ELF::DT_SONAME || 187 Dyn.d_tag == ELF::DT_AUXILIARY || Dyn.d_tag == ELF::DT_FILTER) { 188 Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf); 189 if (StrTabOrErr) { 190 const char *Data = StrTabOrErr.get().data(); 191 outs() << (Data + Dyn.d_un.d_val) << "\n"; 192 continue; 193 } 194 reportWarning(toString(StrTabOrErr.takeError()), Filename); 195 consumeError(StrTabOrErr.takeError()); 196 } 197 outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val); 198 } 199 } 200 201 template <class ELFT> 202 static void printProgramHeaders(const ELFFile<ELFT> *Obj, StringRef FileName) { 203 outs() << "Program Header:\n"; 204 auto ProgramHeaderOrError = Obj->program_headers(); 205 if (!ProgramHeaderOrError) { 206 reportWarning("unable to read program headers: " + 207 toString(ProgramHeaderOrError.takeError()), 208 FileName); 209 return; 210 } 211 212 for (const typename ELFT::Phdr &Phdr : *ProgramHeaderOrError) { 213 switch (Phdr.p_type) { 214 case ELF::PT_DYNAMIC: 215 outs() << " DYNAMIC "; 216 break; 217 case ELF::PT_GNU_EH_FRAME: 218 outs() << "EH_FRAME "; 219 break; 220 case ELF::PT_GNU_RELRO: 221 outs() << " RELRO "; 222 break; 223 case ELF::PT_GNU_PROPERTY: 224 outs() << " PROPERTY "; 225 break; 226 case ELF::PT_GNU_STACK: 227 outs() << " STACK "; 228 break; 229 case ELF::PT_INTERP: 230 outs() << " INTERP "; 231 break; 232 case ELF::PT_LOAD: 233 outs() << " LOAD "; 234 break; 235 case ELF::PT_NOTE: 236 outs() << " NOTE "; 237 break; 238 case ELF::PT_OPENBSD_BOOTDATA: 239 outs() << " OPENBSD_BOOTDATA "; 240 break; 241 case ELF::PT_OPENBSD_RANDOMIZE: 242 outs() << " OPENBSD_RANDOMIZE "; 243 break; 244 case ELF::PT_OPENBSD_WXNEEDED: 245 outs() << " OPENBSD_WXNEEDED "; 246 break; 247 case ELF::PT_PHDR: 248 outs() << " PHDR "; 249 break; 250 case ELF::PT_TLS: 251 outs() << " TLS "; 252 break; 253 default: 254 outs() << " UNKNOWN "; 255 } 256 257 const char *Fmt = ELFT::Is64Bits ? "0x%016" PRIx64 " " : "0x%08" PRIx64 " "; 258 259 outs() << "off " << format(Fmt, (uint64_t)Phdr.p_offset) << "vaddr " 260 << format(Fmt, (uint64_t)Phdr.p_vaddr) << "paddr " 261 << format(Fmt, (uint64_t)Phdr.p_paddr) 262 << format("align 2**%u\n", 263 countTrailingZeros<uint64_t>(Phdr.p_align)) 264 << " filesz " << format(Fmt, (uint64_t)Phdr.p_filesz) 265 << "memsz " << format(Fmt, (uint64_t)Phdr.p_memsz) << "flags " 266 << ((Phdr.p_flags & ELF::PF_R) ? "r" : "-") 267 << ((Phdr.p_flags & ELF::PF_W) ? "w" : "-") 268 << ((Phdr.p_flags & ELF::PF_X) ? "x" : "-") << "\n"; 269 } 270 outs() << "\n"; 271 } 272 273 template <class ELFT> 274 static void printSymbolVersionDependency(ArrayRef<uint8_t> Contents, 275 StringRef StrTab) { 276 outs() << "Version References:\n"; 277 278 const uint8_t *Buf = Contents.data(); 279 while (Buf) { 280 auto *Verneed = reinterpret_cast<const typename ELFT::Verneed *>(Buf); 281 outs() << " required from " 282 << StringRef(StrTab.drop_front(Verneed->vn_file).data()) << ":\n"; 283 284 const uint8_t *BufAux = Buf + Verneed->vn_aux; 285 while (BufAux) { 286 auto *Vernaux = reinterpret_cast<const typename ELFT::Vernaux *>(BufAux); 287 outs() << " " 288 << format("0x%08" PRIx32 " ", (uint32_t)Vernaux->vna_hash) 289 << format("0x%02" PRIx16 " ", (uint16_t)Vernaux->vna_flags) 290 << format("%02" PRIu16 " ", (uint16_t)Vernaux->vna_other) 291 << StringRef(StrTab.drop_front(Vernaux->vna_name).data()) << '\n'; 292 BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr; 293 } 294 Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr; 295 } 296 } 297 298 template <class ELFT> 299 static void printSymbolVersionDefinition(const typename ELFT::Shdr &Shdr, 300 ArrayRef<uint8_t> Contents, 301 StringRef StrTab) { 302 outs() << "Version definitions:\n"; 303 304 const uint8_t *Buf = Contents.data(); 305 uint32_t VerdefIndex = 1; 306 // sh_info contains the number of entries in the SHT_GNU_verdef section. To 307 // make the index column have consistent width, we should insert blank spaces 308 // according to sh_info. 309 uint16_t VerdefIndexWidth = std::to_string(Shdr.sh_info).size(); 310 while (Buf) { 311 auto *Verdef = reinterpret_cast<const typename ELFT::Verdef *>(Buf); 312 outs() << format_decimal(VerdefIndex++, VerdefIndexWidth) << " " 313 << format("0x%02" PRIx16 " ", (uint16_t)Verdef->vd_flags) 314 << format("0x%08" PRIx32 " ", (uint32_t)Verdef->vd_hash); 315 316 const uint8_t *BufAux = Buf + Verdef->vd_aux; 317 uint16_t VerdauxIndex = 0; 318 while (BufAux) { 319 auto *Verdaux = reinterpret_cast<const typename ELFT::Verdaux *>(BufAux); 320 if (VerdauxIndex) 321 outs() << std::string(VerdefIndexWidth + 17, ' '); 322 outs() << StringRef(StrTab.drop_front(Verdaux->vda_name).data()) << '\n'; 323 BufAux = Verdaux->vda_next ? BufAux + Verdaux->vda_next : nullptr; 324 ++VerdauxIndex; 325 } 326 Buf = Verdef->vd_next ? Buf + Verdef->vd_next : nullptr; 327 } 328 } 329 330 template <class ELFT> 331 static void printSymbolVersionInfo(const ELFFile<ELFT> *Elf, 332 StringRef FileName) { 333 ArrayRef<typename ELFT::Shdr> Sections = 334 unwrapOrError(Elf->sections(), FileName); 335 for (const typename ELFT::Shdr &Shdr : Sections) { 336 if (Shdr.sh_type != ELF::SHT_GNU_verneed && 337 Shdr.sh_type != ELF::SHT_GNU_verdef) 338 continue; 339 340 ArrayRef<uint8_t> Contents = 341 unwrapOrError(Elf->getSectionContents(&Shdr), FileName); 342 const typename ELFT::Shdr *StrTabSec = 343 unwrapOrError(Elf->getSection(Shdr.sh_link), FileName); 344 StringRef StrTab = unwrapOrError(Elf->getStringTable(StrTabSec), FileName); 345 346 if (Shdr.sh_type == ELF::SHT_GNU_verneed) 347 printSymbolVersionDependency<ELFT>(Contents, StrTab); 348 else 349 printSymbolVersionDefinition<ELFT>(Shdr, Contents, StrTab); 350 } 351 } 352 353 void objdump::printELFFileHeader(const object::ObjectFile *Obj) { 354 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj)) 355 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 356 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj)) 357 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 358 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj)) 359 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 360 else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj)) 361 printProgramHeaders(ELFObj->getELFFile(), Obj->getFileName()); 362 } 363 364 void objdump::printELFDynamicSection(const object::ObjectFile *Obj) { 365 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj)) 366 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 367 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj)) 368 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 369 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj)) 370 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 371 else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj)) 372 printDynamicSection(ELFObj->getELFFile(), Obj->getFileName()); 373 } 374 375 void objdump::printELFSymbolVersionInfo(const object::ObjectFile *Obj) { 376 if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj)) 377 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 378 else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj)) 379 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 380 else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj)) 381 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 382 else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj)) 383 printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName()); 384 } 385