tools/obj2yaml/elf2yaml.cpp

   1 //===------ utils/elf2yaml.cpp - obj2yaml conversion tool -------*- C++ -*-===//
   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 #include "Error.h"
  11 #include "obj2yaml.h"
  12 #include "llvm/ADT/DenseSet.h"
  13 #include "llvm/ADT/STLExtras.h"
  14 #include "llvm/Object/ELFObjectFile.h"
  15 #include "llvm/ObjectYAML/ELFYAML.h"
  16 #include "llvm/Support/ErrorHandling.h"
  17 #include "llvm/Support/YAMLTraits.h"
  18
  19 using namespace llvm;
  20
  21 namespace {
  22
  23 template <class ELFT>
  24 class ELFDumper {
  25   typedef object::Elf_Sym_Impl<ELFT> Elf_Sym;
  26   typedef typename object::ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
  27   typedef typename object::ELFFile<ELFT>::Elf_Word Elf_Word;
  28   typedef typename object::ELFFile<ELFT>::Elf_Rel Elf_Rel;
  29   typedef typename object::ELFFile<ELFT>::Elf_Rela Elf_Rela;
  30
  31   ArrayRef<Elf_Shdr> Sections;
  32
  33   // If the file has multiple sections with the same name, we add a
  34   // suffix to make them unique.
  35   unsigned Suffix = 0;
  36   DenseSet<StringRef> UsedSectionNames;
  37   std::vector<std::string> SectionNames;
  38   Expected<StringRef> getUniquedSectionName(const Elf_Shdr *Sec);
  39   Expected<StringRef> getSymbolName(const Elf_Sym *Sym, StringRef StrTable,
  40                                     const Elf_Shdr *SymTab);
  41
  42   const object::ELFFile<ELFT> &Obj;
  43   ArrayRef<Elf_Word> ShndxTable;
  44
  45   std::error_code dumpSymbol(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
  46                              StringRef StrTable, ELFYAML::Symbol &S);
  47   std::error_code dumpCommonSection(const Elf_Shdr *Shdr, ELFYAML::Section &S);
  48   std::error_code dumpCommonRelocationSection(const Elf_Shdr *Shdr,
  49                                               ELFYAML::RelocationSection &S);
  50   template <class RelT>
  51   std::error_code dumpRelocation(const RelT *Rel, const Elf_Shdr *SymTab,
  52                                  ELFYAML::Relocation &R);
  53
  54   ErrorOr<ELFYAML::RelocationSection *> dumpRelSection(const Elf_Shdr *Shdr);
  55   ErrorOr<ELFYAML::RelocationSection *> dumpRelaSection(const Elf_Shdr *Shdr);
  56   ErrorOr<ELFYAML::RawContentSection *>
  57   dumpContentSection(const Elf_Shdr *Shdr);
  58   ErrorOr<ELFYAML::NoBitsSection *> dumpNoBitsSection(const Elf_Shdr *Shdr);
  59   ErrorOr<ELFYAML::Group *> dumpGroup(const Elf_Shdr *Shdr);
  60   ErrorOr<ELFYAML::MipsABIFlags *> dumpMipsABIFlags(const Elf_Shdr *Shdr);
  61
  62 public:
  63   ELFDumper(const object::ELFFile<ELFT> &O);
  64   ErrorOr<ELFYAML::Object *> dump();
  65 };
  66
  67 }
  68
  69 template <class ELFT>
  70 ELFDumper<ELFT>::ELFDumper(const object::ELFFile<ELFT> &O)
  71     : Obj(O) {}
  72
  73 template <class ELFT>
  74 Expected<StringRef>
  75 ELFDumper<ELFT>::getUniquedSectionName(const Elf_Shdr *Sec) {
  76   unsigned SecIndex = Sec - &Sections[0];
  77   assert(&Sections[SecIndex] == Sec);
  78   if (!SectionNames[SecIndex].empty())
  79     return SectionNames[SecIndex];
  80
  81   auto NameOrErr = Obj.getSectionName(Sec);
  82   if (!NameOrErr)
  83     return NameOrErr;
  84   StringRef Name = *NameOrErr;
  85   std::string &Ret = SectionNames[SecIndex];
  86   Ret = Name;
  87   while (!UsedSectionNames.insert(Ret).second)
  88     Ret = (Name + to_string(++Suffix)).str();
  89   return Ret;
  90 }
  91
  92 template <class ELFT>
  93 Expected<StringRef> ELFDumper<ELFT>::getSymbolName(const Elf_Sym *Sym,
  94                                                    StringRef StrTable,
  95                                                    const Elf_Shdr *SymTab) {
  96   Expected<StringRef> SymbolNameOrErr = Sym->getName(StrTable);
  97   if (!SymbolNameOrErr)
  98     return SymbolNameOrErr;
  99   StringRef Name = *SymbolNameOrErr;
 100   if (Name.empty() && Sym->getType() == ELF::STT_SECTION) {
 101     auto ShdrOrErr = Obj.getSection(Sym, SymTab, ShndxTable);
 102     if (!ShdrOrErr)
 103       return ShdrOrErr.takeError();
 104     return getUniquedSectionName(*ShdrOrErr);
 105   }
 106   return Name;
 107 }
 108
 109 template <class ELFT> ErrorOr<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
 110   auto Y = make_unique<ELFYAML::Object>();
 111
 112   // Dump header
 113   Y->Header.Class = ELFYAML::ELF_ELFCLASS(Obj.getHeader()->getFileClass());
 114   Y->Header.Data = ELFYAML::ELF_ELFDATA(Obj.getHeader()->getDataEncoding());
 115   Y->Header.OSABI = Obj.getHeader()->e_ident[ELF::EI_OSABI];
 116   Y->Header.Type = Obj.getHeader()->e_type;
 117   Y->Header.Machine = Obj.getHeader()->e_machine;
 118   Y->Header.Flags = Obj.getHeader()->e_flags;
 119   Y->Header.Entry = Obj.getHeader()->e_entry;
 120
 121   const Elf_Shdr *Symtab = nullptr;
 122
 123   // Dump sections
 124   auto SectionsOrErr = Obj.sections();
 125   if (!SectionsOrErr)
 126     return errorToErrorCode(SectionsOrErr.takeError());
 127   Sections = *SectionsOrErr;
 128   SectionNames.resize(Sections.size());
 129   for (const Elf_Shdr &Sec : Sections) {
 130     switch (Sec.sh_type) {
 131     case ELF::SHT_NULL:
 132     case ELF::SHT_DYNSYM:
 133     case ELF::SHT_STRTAB:
 134       // Do not dump these sections.
 135       break;
 136     case ELF::SHT_SYMTAB:
 137       Symtab = &Sec;
 138       break;
 139     case ELF::SHT_SYMTAB_SHNDX: {
 140       auto TableOrErr = Obj.getSHNDXTable(Sec);
 141       if (!TableOrErr)
 142         return errorToErrorCode(TableOrErr.takeError());
 143       ShndxTable = *TableOrErr;
 144       break;
 145     }
 146     case ELF::SHT_RELA: {
 147       ErrorOr<ELFYAML::RelocationSection *> S = dumpRelaSection(&Sec);
 148       if (std::error_code EC = S.getError())
 149         return EC;
 150       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
 151       break;
 152     }
 153     case ELF::SHT_REL: {
 154       ErrorOr<ELFYAML::RelocationSection *> S = dumpRelSection(&Sec);
 155       if (std::error_code EC = S.getError())
 156         return EC;
 157       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
 158       break;
 159     }
 160     case ELF::SHT_GROUP: {
 161       ErrorOr<ELFYAML::Group *> G = dumpGroup(&Sec);
 162       if (std::error_code EC = G.getError())
 163         return EC;
 164       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(G.get()));
 165       break;
 166     }
 167     case ELF::SHT_MIPS_ABIFLAGS: {
 168       ErrorOr<ELFYAML::MipsABIFlags *> G = dumpMipsABIFlags(&Sec);
 169       if (std::error_code EC = G.getError())
 170         return EC;
 171       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(G.get()));
 172       break;
 173     }
 174     case ELF::SHT_NOBITS: {
 175       ErrorOr<ELFYAML::NoBitsSection *> S = dumpNoBitsSection(&Sec);
 176       if (std::error_code EC = S.getError())
 177         return EC;
 178       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
 179       break;
 180     }
 181     default: {
 182       ErrorOr<ELFYAML::RawContentSection *> S = dumpContentSection(&Sec);
 183       if (std::error_code EC = S.getError())
 184         return EC;
 185       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
 186     }
 187     }
 188   }
 189
 190   // Dump symbols
 191   if (!Symtab)
 192     return Y.release(); // if the symbol table is missing return early
 193   auto StrTableOrErr = Obj.getStringTableForSymtab(*Symtab);
 194   if (!StrTableOrErr)
 195     return errorToErrorCode(StrTableOrErr.takeError());
 196   StringRef StrTable = *StrTableOrErr;
 197
 198   bool IsFirstSym = true;
 199   auto SymtabOrErr = Obj.symbols(Symtab);
 200   if (!SymtabOrErr)
 201     return errorToErrorCode(SymtabOrErr.takeError());
 202   for (const Elf_Sym &Sym : *SymtabOrErr) {
 203     if (IsFirstSym) {
 204       IsFirstSym = false;
 205       continue;
 206     }
 207
 208     ELFYAML::Symbol S;
 209     if (std::error_code EC =
 210             ELFDumper<ELFT>::dumpSymbol(&Sym, Symtab, StrTable, S))
 211       return EC;
 212
 213     switch (Sym.getBinding())
 214     {
 215     case ELF::STB_LOCAL:
 216       Y->Symbols.Local.push_back(S);
 217       break;
 218     case ELF::STB_GLOBAL:
 219       Y->Symbols.Global.push_back(S);
 220       break;
 221     case ELF::STB_WEAK:
 222       Y->Symbols.Weak.push_back(S);
 223       break;
 224     default:
 225       llvm_unreachable("Unknown ELF symbol binding");
 226     }
 227   }
 228
 229   return Y.release();
 230 }
 231
 232 template <class ELFT>
 233 std::error_code
 234 ELFDumper<ELFT>::dumpSymbol(const Elf_Sym *Sym, const Elf_Shdr *SymTab,
 235                             StringRef StrTable, ELFYAML::Symbol &S) {
 236   S.Type = Sym->getType();
 237   S.Value = Sym->st_value;
 238   S.Size = Sym->st_size;
 239   S.Other = Sym->st_other;
 240
 241   Expected<StringRef> SymbolNameOrErr = getSymbolName(Sym, StrTable, SymTab);
 242   if (!SymbolNameOrErr)
 243     return errorToErrorCode(SymbolNameOrErr.takeError());
 244   S.Name = SymbolNameOrErr.get();
 245
 246   auto ShdrOrErr = Obj.getSection(Sym, SymTab, ShndxTable);
 247   if (!ShdrOrErr)
 248     return errorToErrorCode(ShdrOrErr.takeError());
 249   const Elf_Shdr *Shdr = *ShdrOrErr;
 250   if (!Shdr)
 251     return obj2yaml_error::success;
 252
 253   auto NameOrErr = getUniquedSectionName(Shdr);
 254   if (!NameOrErr)
 255     return errorToErrorCode(NameOrErr.takeError());
 256   S.Section = NameOrErr.get();
 257
 258   return obj2yaml_error::success;
 259 }
 260
 261 template <class ELFT>
 262 template <class RelT>
 263 std::error_code ELFDumper<ELFT>::dumpRelocation(const RelT *Rel,
 264                                                 const Elf_Shdr *SymTab,
 265                                                 ELFYAML::Relocation &R) {
 266   R.Type = Rel->getType(Obj.isMips64EL());
 267   R.Offset = Rel->r_offset;
 268   R.Addend = 0;
 269
 270   auto SymOrErr = Obj.getRelocationSymbol(Rel, SymTab);
 271   if (!SymOrErr)
 272     return errorToErrorCode(SymOrErr.takeError());
 273   const Elf_Sym *Sym = *SymOrErr;
 274   auto StrTabSec = Obj.getSection(SymTab->sh_link);
 275   if (!StrTabSec)
 276     return errorToErrorCode(StrTabSec.takeError());
 277   auto StrTabOrErr = Obj.getStringTable(*StrTabSec);
 278   if (!StrTabOrErr)
 279     return errorToErrorCode(StrTabOrErr.takeError());
 280   StringRef StrTab = *StrTabOrErr;
 281
 282   if (Sym) {
 283     Expected<StringRef> NameOrErr = getSymbolName(Sym, StrTab, SymTab);
 284     if (!NameOrErr)
 285       return errorToErrorCode(NameOrErr.takeError());
 286     R.Symbol = NameOrErr.get();
 287   } else {
 288     // We have some edge cases of relocations without a symbol associated,
 289     // e.g. an object containing the invalid (according to the System V
 290     // ABI) R_X86_64_NONE reloc. Create a symbol with an empty name instead
 291     // of crashing.
 292     R.Symbol = "";
 293   }
 294
 295   return obj2yaml_error::success;
 296 }
 297
 298 template <class ELFT>
 299 std::error_code ELFDumper<ELFT>::dumpCommonSection(const Elf_Shdr *Shdr,
 300                                                    ELFYAML::Section &S) {
 301   S.Type = Shdr->sh_type;
 302   S.Flags = Shdr->sh_flags;
 303   S.Address = Shdr->sh_addr;
 304   S.AddressAlign = Shdr->sh_addralign;
 305
 306   auto NameOrErr = getUniquedSectionName(Shdr);
 307   if (!NameOrErr)
 308     return errorToErrorCode(NameOrErr.takeError());
 309   S.Name = NameOrErr.get();
 310
 311   if (Shdr->sh_link != ELF::SHN_UNDEF) {
 312     auto LinkSection = Obj.getSection(Shdr->sh_link);
 313     if (LinkSection.takeError())
 314       return errorToErrorCode(LinkSection.takeError());
 315     NameOrErr = getUniquedSectionName(*LinkSection);
 316     if (!NameOrErr)
 317       return errorToErrorCode(NameOrErr.takeError());
 318     S.Link = NameOrErr.get();
 319   }
 320
 321   return obj2yaml_error::success;
 322 }
 323
 324 template <class ELFT>
 325 std::error_code
 326 ELFDumper<ELFT>::dumpCommonRelocationSection(const Elf_Shdr *Shdr,
 327                                              ELFYAML::RelocationSection &S) {
 328   if (std::error_code EC = dumpCommonSection(Shdr, S))
 329     return EC;
 330
 331   auto InfoSection = Obj.getSection(Shdr->sh_info);
 332   if (!InfoSection)
 333     return errorToErrorCode(InfoSection.takeError());
 334
 335   auto NameOrErr = getUniquedSectionName(*InfoSection);
 336   if (!NameOrErr)
 337     return errorToErrorCode(NameOrErr.takeError());
 338   S.Info = NameOrErr.get();
 339
 340   return obj2yaml_error::success;
 341 }
 342
 343 template <class ELFT>
 344 ErrorOr<ELFYAML::RelocationSection *>
 345 ELFDumper<ELFT>::dumpRelSection(const Elf_Shdr *Shdr) {
 346   assert(Shdr->sh_type == ELF::SHT_REL && "Section type is not SHT_REL");
 347   auto S = make_unique<ELFYAML::RelocationSection>();
 348
 349   if (std::error_code EC = dumpCommonRelocationSection(Shdr, *S))
 350     return EC;
 351
 352   auto SymTabOrErr = Obj.getSection(Shdr->sh_link);
 353   if (!SymTabOrErr)
 354     return errorToErrorCode(SymTabOrErr.takeError());
 355   const Elf_Shdr *SymTab = *SymTabOrErr;
 356
 357   auto Rels = Obj.rels(Shdr);
 358   if (!Rels)
 359     return errorToErrorCode(Rels.takeError());
 360   for (const Elf_Rel &Rel : *Rels) {
 361     ELFYAML::Relocation R;
 362     if (std::error_code EC = dumpRelocation(&Rel, SymTab, R))
 363       return EC;
 364     S->Relocations.push_back(R);
 365   }
 366
 367   return S.release();
 368 }
 369
 370 template <class ELFT>
 371 ErrorOr<ELFYAML::RelocationSection *>
 372 ELFDumper<ELFT>::dumpRelaSection(const Elf_Shdr *Shdr) {
 373   assert(Shdr->sh_type == ELF::SHT_RELA && "Section type is not SHT_RELA");
 374   auto S = make_unique<ELFYAML::RelocationSection>();
 375
 376   if (std::error_code EC = dumpCommonRelocationSection(Shdr, *S))
 377     return EC;
 378
 379   auto SymTabOrErr = Obj.getSection(Shdr->sh_link);
 380   if (!SymTabOrErr)
 381     return errorToErrorCode(SymTabOrErr.takeError());
 382   const Elf_Shdr *SymTab = *SymTabOrErr;
 383
 384   auto Rels = Obj.relas(Shdr);
 385   if (!Rels)
 386     return errorToErrorCode(Rels.takeError());
 387   for (const Elf_Rela &Rel : *Rels) {
 388     ELFYAML::Relocation R;
 389     if (std::error_code EC = dumpRelocation(&Rel, SymTab, R))
 390       return EC;
 391     R.Addend = Rel.r_addend;
 392     S->Relocations.push_back(R);
 393   }
 394
 395   return S.release();
 396 }
 397
 398 template <class ELFT>
 399 ErrorOr<ELFYAML::RawContentSection *>
 400 ELFDumper<ELFT>::dumpContentSection(const Elf_Shdr *Shdr) {
 401   auto S = make_unique<ELFYAML::RawContentSection>();
 402
 403   if (std::error_code EC = dumpCommonSection(Shdr, *S))
 404     return EC;
 405
 406   auto ContentOrErr = Obj.getSectionContents(Shdr);
 407   if (!ContentOrErr)
 408     return errorToErrorCode(ContentOrErr.takeError());
 409   S->Content = yaml::BinaryRef(ContentOrErr.get());
 410   S->Size = S->Content.binary_size();
 411
 412   return S.release();
 413 }
 414
 415 template <class ELFT>
 416 ErrorOr<ELFYAML::NoBitsSection *>
 417 ELFDumper<ELFT>::dumpNoBitsSection(const Elf_Shdr *Shdr) {
 418   auto S = make_unique<ELFYAML::NoBitsSection>();
 419
 420   if (std::error_code EC = dumpCommonSection(Shdr, *S))
 421     return EC;
 422   S->Size = Shdr->sh_size;
 423
 424   return S.release();
 425 }
 426
 427 template <class ELFT>
 428 ErrorOr<ELFYAML::Group *> ELFDumper<ELFT>::dumpGroup(const Elf_Shdr *Shdr) {
 429   auto S = make_unique<ELFYAML::Group>();
 430
 431   if (std::error_code EC = dumpCommonSection(Shdr, *S))
 432     return EC;
 433   // Get sh_info which is the signature.
 434   auto SymtabOrErr = Obj.getSection(Shdr->sh_link);
 435   if (!SymtabOrErr)
 436     return errorToErrorCode(SymtabOrErr.takeError());
 437   const Elf_Shdr *Symtab = *SymtabOrErr;
 438   auto SymOrErr = Obj.getSymbol(Symtab, Shdr->sh_info);
 439   if (!SymOrErr)
 440     return errorToErrorCode(SymOrErr.takeError());
 441   const Elf_Sym *symbol = *SymOrErr;
 442   auto StrTabOrErr = Obj.getStringTableForSymtab(*Symtab);
 443   if (!StrTabOrErr)
 444     return errorToErrorCode(StrTabOrErr.takeError());
 445   StringRef StrTab = *StrTabOrErr;
 446   auto sectionContents = Obj.getSectionContents(Shdr);
 447   if (!sectionContents)
 448     return errorToErrorCode(sectionContents.takeError());
 449   Expected<StringRef> symbolName = getSymbolName(symbol, StrTab, Symtab);
 450   if (!symbolName)
 451     return errorToErrorCode(symbolName.takeError());
 452   S->Info = *symbolName;
 453   const Elf_Word *groupMembers =
 454       reinterpret_cast<const Elf_Word *>(sectionContents->data());
 455   const long count = (Shdr->sh_size) / sizeof(Elf_Word);
 456   ELFYAML::SectionOrType s;
 457   for (int i = 0; i < count; i++) {
 458     if (groupMembers[i] == llvm::ELF::GRP_COMDAT) {
 459       s.sectionNameOrType = "GRP_COMDAT";
 460     } else {
 461       auto sHdr = Obj.getSection(groupMembers[i]);
 462       if (!sHdr)
 463         return errorToErrorCode(sHdr.takeError());
 464       auto sectionName = getUniquedSectionName(*sHdr);
 465       if (!sectionName)
 466         return errorToErrorCode(sectionName.takeError());
 467       s.sectionNameOrType = *sectionName;
 468     }
 469     S->Members.push_back(s);
 470   }
 471   return S.release();
 472 }
 473
 474 template <class ELFT>
 475 ErrorOr<ELFYAML::MipsABIFlags *>
 476 ELFDumper<ELFT>::dumpMipsABIFlags(const Elf_Shdr *Shdr) {
 477   assert(Shdr->sh_type == ELF::SHT_MIPS_ABIFLAGS &&
 478          "Section type is not SHT_MIPS_ABIFLAGS");
 479   auto S = make_unique<ELFYAML::MipsABIFlags>();
 480   if (std::error_code EC = dumpCommonSection(Shdr, *S))
 481     return EC;
 482
 483   auto ContentOrErr = Obj.getSectionContents(Shdr);
 484   if (!ContentOrErr)
 485     return errorToErrorCode(ContentOrErr.takeError());
 486
 487   auto *Flags = reinterpret_cast<const object::Elf_Mips_ABIFlags<ELFT> *>(
 488       ContentOrErr.get().data());
 489   S->Version = Flags->version;
 490   S->ISALevel = Flags->isa_level;
 491   S->ISARevision = Flags->isa_rev;
 492   S->GPRSize = Flags->gpr_size;
 493   S->CPR1Size = Flags->cpr1_size;
 494   S->CPR2Size = Flags->cpr2_size;
 495   S->FpABI = Flags->fp_abi;
 496   S->ISAExtension = Flags->isa_ext;
 497   S->ASEs = Flags->ases;
 498   S->Flags1 = Flags->flags1;
 499   S->Flags2 = Flags->flags2;
 500   return S.release();
 501 }
 502
 503 template <class ELFT>
 504 static std::error_code elf2yaml(raw_ostream &Out,
 505                                 const object::ELFFile<ELFT> &Obj) {
 506   ELFDumper<ELFT> Dumper(Obj);
 507   ErrorOr<ELFYAML::Object *> YAMLOrErr = Dumper.dump();
 508   if (std::error_code EC = YAMLOrErr.getError())
 509     return EC;
 510
 511   std::unique_ptr<ELFYAML::Object> YAML(YAMLOrErr.get());
 512   yaml::Output Yout(Out);
 513   Yout << *YAML;
 514
 515   return std::error_code();
 516 }
 517
 518 std::error_code elf2yaml(raw_ostream &Out, const object::ObjectFile &Obj) {
 519   if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(&Obj))
 520     return elf2yaml(Out, *ELFObj->getELFFile());
 521
 522   if (const auto *ELFObj = dyn_cast<object::ELF32BEObjectFile>(&Obj))
 523     return elf2yaml(Out, *ELFObj->getELFFile());
 524
 525   if (const auto *ELFObj = dyn_cast<object::ELF64LEObjectFile>(&Obj))
 526     return elf2yaml(Out, *ELFObj->getELFFile());
 527
 528   if (const auto *ELFObj = dyn_cast<object::ELF64BEObjectFile>(&Obj))
 529     return elf2yaml(Out, *ELFObj->getELFFile());
 530
 531   return obj2yaml_error::unsupported_obj_file_format;
 532 }