lib/ObjectYAML/ELFEmitter.cpp

   1 //===- yaml2elf - Convert YAML to a ELF object file -----------------------===//
   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 /// The ELF component of yaml2obj.
  11 ///
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/ArrayRef.h"
  15 #include "llvm/ADT/StringSet.h"
  16 #include "llvm/BinaryFormat/ELF.h"
  17 #include "llvm/MC/StringTableBuilder.h"
  18 #include "llvm/Object/ELFObjectFile.h"
  19 #include "llvm/ObjectYAML/ELFYAML.h"
  20 #include "llvm/ObjectYAML/yaml2obj.h"
  21 #include "llvm/Support/EndianStream.h"
  22 #include "llvm/Support/LEB128.h"
  23 #include "llvm/Support/MemoryBuffer.h"
  24 #include "llvm/Support/WithColor.h"
  25 #include "llvm/Support/YAMLTraits.h"
  26 #include "llvm/Support/raw_ostream.h"
  27
  28 using namespace llvm;
  29
  30 // This class is used to build up a contiguous binary blob while keeping
  31 // track of an offset in the output (which notionally begins at
  32 // `InitialOffset`).
  33 namespace {
  34 class ContiguousBlobAccumulator {
  35   const uint64_t InitialOffset;
  36   SmallVector<char, 128> Buf;
  37   raw_svector_ostream OS;
  38
  39   /// \returns The new offset.
  40   uint64_t padToAlignment(unsigned Align) {
  41     if (Align == 0)
  42       Align = 1;
  43     uint64_t CurrentOffset = InitialOffset + OS.tell();
  44     uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
  45     OS.write_zeros(AlignedOffset - CurrentOffset);
  46     return AlignedOffset; // == CurrentOffset;
  47   }
  48
  49 public:
  50   ContiguousBlobAccumulator(uint64_t InitialOffset_)
  51       : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
  52   template <class Integer>
  53   raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
  54     Offset = padToAlignment(Align);
  55     return OS;
  56   }
  57   void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
  58 };
  59
  60 // Used to keep track of section and symbol names, so that in the YAML file
  61 // sections and symbols can be referenced by name instead of by index.
  62 class NameToIdxMap {
  63   StringMap<unsigned> Map;
  64
  65 public:
  66   /// \Returns false if name is already present in the map.
  67   bool addName(StringRef Name, unsigned Ndx) {
  68     return Map.insert({Name, Ndx}).second;
  69   }
  70   /// \Returns false if name is not present in the map.
  71   bool lookup(StringRef Name, unsigned &Idx) const {
  72     auto I = Map.find(Name);
  73     if (I == Map.end())
  74       return false;
  75     Idx = I->getValue();
  76     return true;
  77   }
  78   /// Asserts if name is not present in the map.
  79   unsigned get(StringRef Name) const {
  80     unsigned Idx;
  81     if (lookup(Name, Idx))
  82       return Idx;
  83     assert(false && "Expected section not found in index");
  84     return 0;
  85   }
  86   unsigned size() const { return Map.size(); }
  87 };
  88
  89 /// "Single point of truth" for the ELF file construction.
  90 /// TODO: This class still has a ways to go before it is truly a "single
  91 /// point of truth".
  92 template <class ELFT> class ELFState {
  93   typedef typename ELFT::Ehdr Elf_Ehdr;
  94   typedef typename ELFT::Phdr Elf_Phdr;
  95   typedef typename ELFT::Shdr Elf_Shdr;
  96   typedef typename ELFT::Sym Elf_Sym;
  97   typedef typename ELFT::Rel Elf_Rel;
  98   typedef typename ELFT::Rela Elf_Rela;
  99   typedef typename ELFT::Relr Elf_Relr;
 100   typedef typename ELFT::Dyn Elf_Dyn;
 101
 102   enum class SymtabType { Static, Dynamic };
 103
 104   /// The future ".strtab" section.
 105   StringTableBuilder DotStrtab{StringTableBuilder::ELF};
 106
 107   /// The future ".shstrtab" section.
 108   StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
 109
 110   /// The future ".dynstr" section.
 111   StringTableBuilder DotDynstr{StringTableBuilder::ELF};
 112
 113   NameToIdxMap SN2I;
 114   NameToIdxMap SymN2I;
 115   NameToIdxMap DynSymN2I;
 116   ELFYAML::Object &Doc;
 117
 118   bool HasError = false;
 119   yaml::ErrorHandler ErrHandler;
 120   void reportError(const Twine &Msg);
 121
 122   std::vector<Elf_Sym> toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
 123                                     const StringTableBuilder &Strtab);
 124   unsigned toSectionIndex(StringRef S, StringRef LocSec, StringRef LocSym = "");
 125   unsigned toSymbolIndex(StringRef S, StringRef LocSec, bool IsDynamic);
 126
 127   void buildSectionIndex();
 128   void buildSymbolIndexes();
 129   void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
 130   bool initImplicitHeader(ContiguousBlobAccumulator &CBA, Elf_Shdr &Header,
 131                           StringRef SecName, ELFYAML::Section *YAMLSec);
 132   void initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
 133                           ContiguousBlobAccumulator &CBA);
 134   void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
 135                                ContiguousBlobAccumulator &CBA,
 136                                ELFYAML::Section *YAMLSec);
 137   void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 138                                StringTableBuilder &STB,
 139                                ContiguousBlobAccumulator &CBA,
 140                                ELFYAML::Section *YAMLSec);
 141   void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 142                               std::vector<Elf_Shdr> &SHeaders);
 143   void finalizeStrings();
 144   void writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS);
 145   void writeSectionContent(Elf_Shdr &SHeader,
 146                            const ELFYAML::RawContentSection &Section,
 147                            ContiguousBlobAccumulator &CBA);
 148   void writeSectionContent(Elf_Shdr &SHeader,
 149                            const ELFYAML::RelocationSection &Section,
 150                            ContiguousBlobAccumulator &CBA);
 151   void writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
 152                            ContiguousBlobAccumulator &CBA);
 153   void writeSectionContent(Elf_Shdr &SHeader,
 154                            const ELFYAML::SymtabShndxSection &Shndx,
 155                            ContiguousBlobAccumulator &CBA);
 156   void writeSectionContent(Elf_Shdr &SHeader,
 157                            const ELFYAML::SymverSection &Section,
 158                            ContiguousBlobAccumulator &CBA);
 159   void writeSectionContent(Elf_Shdr &SHeader,
 160                            const ELFYAML::VerneedSection &Section,
 161                            ContiguousBlobAccumulator &CBA);
 162   void writeSectionContent(Elf_Shdr &SHeader,
 163                            const ELFYAML::VerdefSection &Section,
 164                            ContiguousBlobAccumulator &CBA);
 165   void writeSectionContent(Elf_Shdr &SHeader,
 166                            const ELFYAML::MipsABIFlags &Section,
 167                            ContiguousBlobAccumulator &CBA);
 168   void writeSectionContent(Elf_Shdr &SHeader,
 169                            const ELFYAML::DynamicSection &Section,
 170                            ContiguousBlobAccumulator &CBA);
 171   void writeSectionContent(Elf_Shdr &SHeader,
 172                            const ELFYAML::StackSizesSection &Section,
 173                            ContiguousBlobAccumulator &CBA);
 174   void writeSectionContent(Elf_Shdr &SHeader,
 175                            const ELFYAML::HashSection &Section,
 176                            ContiguousBlobAccumulator &CBA);
 177   void writeSectionContent(Elf_Shdr &SHeader,
 178                            const ELFYAML::AddrsigSection &Section,
 179                            ContiguousBlobAccumulator &CBA);
 180
 181   ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
 182
 183 public:
 184   static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
 185                        yaml::ErrorHandler EH);
 186 };
 187 } // end anonymous namespace
 188
 189 template <class T> static size_t arrayDataSize(ArrayRef<T> A) {
 190   return A.size() * sizeof(T);
 191 }
 192
 193 template <class T> static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
 194   OS.write((const char *)A.data(), arrayDataSize(A));
 195 }
 196
 197 template <class T> static void zero(T &Obj) { memset(&Obj, 0, sizeof(Obj)); }
 198
 199 template <class ELFT>
 200 ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
 201     : Doc(D), ErrHandler(EH) {
 202   StringSet<> DocSections;
 203   for (std::unique_ptr<ELFYAML::Section> &D : Doc.Sections) {
 204     if (!D->Name.empty())
 205       DocSections.insert(D->Name);
 206
 207     // Some sections wants to link to .symtab by default.
 208     // That means we want to create the symbol table for them.
 209     if (D->Type == llvm::ELF::SHT_REL || D->Type == llvm::ELF::SHT_RELA)
 210       if (!Doc.Symbols && D->Link.empty())
 211         Doc.Symbols.emplace();
 212   }
 213
 214   // Insert SHT_NULL section implicitly when it is not defined in YAML.
 215   if (Doc.Sections.empty() || Doc.Sections.front()->Type != ELF::SHT_NULL)
 216     Doc.Sections.insert(
 217         Doc.Sections.begin(),
 218         std::make_unique<ELFYAML::Section>(
 219             ELFYAML::Section::SectionKind::RawContent, /*IsImplicit=*/true));
 220
 221   std::vector<StringRef> ImplicitSections;
 222   if (Doc.Symbols)
 223     ImplicitSections.push_back(".symtab");
 224   ImplicitSections.insert(ImplicitSections.end(), {".strtab", ".shstrtab"});
 225
 226   if (!Doc.DynamicSymbols.empty())
 227     ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
 228
 229   // Insert placeholders for implicit sections that are not
 230   // defined explicitly in YAML.
 231   for (StringRef SecName : ImplicitSections) {
 232     if (DocSections.count(SecName))
 233       continue;
 234
 235     std::unique_ptr<ELFYAML::Section> Sec = std::make_unique<ELFYAML::Section>(
 236         ELFYAML::Section::SectionKind::RawContent, true /*IsImplicit*/);
 237     Sec->Name = SecName;
 238     Doc.Sections.push_back(std::move(Sec));
 239   }
 240 }
 241
 242 template <class ELFT>
 243 void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS) {
 244   using namespace llvm::ELF;
 245
 246   Elf_Ehdr Header;
 247   zero(Header);
 248   Header.e_ident[EI_MAG0] = 0x7f;
 249   Header.e_ident[EI_MAG1] = 'E';
 250   Header.e_ident[EI_MAG2] = 'L';
 251   Header.e_ident[EI_MAG3] = 'F';
 252   Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
 253   Header.e_ident[EI_DATA] = Doc.Header.Data;
 254   Header.e_ident[EI_VERSION] = EV_CURRENT;
 255   Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
 256   Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
 257   Header.e_type = Doc.Header.Type;
 258   Header.e_machine = Doc.Header.Machine;
 259   Header.e_version = EV_CURRENT;
 260   Header.e_entry = Doc.Header.Entry;
 261   Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
 262   Header.e_flags = Doc.Header.Flags;
 263   Header.e_ehsize = sizeof(Elf_Ehdr);
 264   Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
 265   Header.e_phnum = Doc.ProgramHeaders.size();
 266
 267   Header.e_shentsize =
 268       Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
 269   // Immediately following the ELF header and program headers.
 270   // Align the start of the section header and write the ELF header.
 271   uint64_t SHOff;
 272   CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
 273   Header.e_shoff =
 274       Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
 275   Header.e_shnum =
 276       Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.Sections.size();
 277   Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
 278                                           : SN2I.get(".shstrtab");
 279
 280   OS.write((const char *)&Header, sizeof(Header));
 281 }
 282
 283 template <class ELFT>
 284 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
 285   for (const auto &YamlPhdr : Doc.ProgramHeaders) {
 286     Elf_Phdr Phdr;
 287     Phdr.p_type = YamlPhdr.Type;
 288     Phdr.p_flags = YamlPhdr.Flags;
 289     Phdr.p_vaddr = YamlPhdr.VAddr;
 290     Phdr.p_paddr = YamlPhdr.PAddr;
 291     PHeaders.push_back(Phdr);
 292   }
 293 }
 294
 295 template <class ELFT>
 296 unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
 297                                         StringRef LocSym) {
 298   unsigned Index;
 299   if (SN2I.lookup(S, Index) || to_integer(S, Index))
 300     return Index;
 301
 302   assert(LocSec.empty() || LocSym.empty());
 303   if (!LocSym.empty())
 304     reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
 305                 LocSym + "'");
 306   else
 307     reportError("unknown section referenced: '" + S + "' by YAML section '" +
 308                 LocSec + "'");
 309   return 0;
 310 }
 311
 312 template <class ELFT>
 313 unsigned ELFState<ELFT>::toSymbolIndex(StringRef S, StringRef LocSec,
 314                                        bool IsDynamic) {
 315   const NameToIdxMap &SymMap = IsDynamic ? DynSymN2I : SymN2I;
 316   unsigned Index;
 317   // Here we try to look up S in the symbol table. If it is not there,
 318   // treat its value as a symbol index.
 319   if (!SymMap.lookup(S, Index) && !to_integer(S, Index)) {
 320     reportError("unknown symbol referenced: '" + S + "' by YAML section '" +
 321                 LocSec + "'");
 322     return 0;
 323   }
 324   return Index;
 325 }
 326
 327 template <class ELFT>
 328 bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
 329                                         Elf_Shdr &Header, StringRef SecName,
 330                                         ELFYAML::Section *YAMLSec) {
 331   // Check if the header was already initialized.
 332   if (Header.sh_offset)
 333     return false;
 334
 335   if (SecName == ".symtab")
 336     initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
 337   else if (SecName == ".strtab")
 338     initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
 339   else if (SecName == ".shstrtab")
 340     initStrtabSectionHeader(Header, SecName, DotShStrtab, CBA, YAMLSec);
 341   else if (SecName == ".dynsym")
 342     initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
 343   else if (SecName == ".dynstr")
 344     initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
 345   else
 346     return false;
 347
 348   // Override the fields if requested.
 349   if (YAMLSec) {
 350     if (YAMLSec->ShName)
 351       Header.sh_name = *YAMLSec->ShName;
 352     if (YAMLSec->ShOffset)
 353       Header.sh_offset = *YAMLSec->ShOffset;
 354     if (YAMLSec->ShSize)
 355       Header.sh_size = *YAMLSec->ShSize;
 356   }
 357
 358   return true;
 359 }
 360
 361 StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
 362   size_t SuffixPos = S.rfind(" [");
 363   if (SuffixPos == StringRef::npos)
 364     return S;
 365   return S.substr(0, SuffixPos);
 366 }
 367
 368 template <class ELFT>
 369 void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
 370                                         ContiguousBlobAccumulator &CBA) {
 371   // Ensure SHN_UNDEF entry is present. An all-zero section header is a
 372   // valid SHN_UNDEF entry since SHT_NULL == 0.
 373   SHeaders.resize(Doc.Sections.size());
 374
 375   for (size_t I = 0; I < Doc.Sections.size(); ++I) {
 376     ELFYAML::Section *Sec = Doc.Sections[I].get();
 377     if (I == 0 && Sec->IsImplicit)
 378       continue;
 379
 380     // We have a few sections like string or symbol tables that are usually
 381     // added implicitly to the end. However, if they are explicitly specified
 382     // in the YAML, we need to write them here. This ensures the file offset
 383     // remains correct.
 384     Elf_Shdr &SHeader = SHeaders[I];
 385     if (initImplicitHeader(CBA, SHeader, Sec->Name,
 386                            Sec->IsImplicit ? nullptr : Sec))
 387       continue;
 388
 389     assert(Sec && "It can't be null unless it is an implicit section. But all "
 390                   "implicit sections should already have been handled above.");
 391
 392     SHeader.sh_name =
 393         DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
 394     SHeader.sh_type = Sec->Type;
 395     if (Sec->Flags)
 396       SHeader.sh_flags = *Sec->Flags;
 397     SHeader.sh_addr = Sec->Address;
 398     SHeader.sh_addralign = Sec->AddressAlign;
 399
 400     if (!Sec->Link.empty())
 401       SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
 402
 403     if (I == 0) {
 404       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 405         // We do not write any content for special SHN_UNDEF section.
 406         if (RawSec->Size)
 407           SHeader.sh_size = *RawSec->Size;
 408         if (RawSec->Info)
 409           SHeader.sh_info = *RawSec->Info;
 410       }
 411       if (Sec->EntSize)
 412         SHeader.sh_entsize = *Sec->EntSize;
 413     } else if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
 414       writeSectionContent(SHeader, *S, CBA);
 415     } else if (auto S = dyn_cast<ELFYAML::SymtabShndxSection>(Sec)) {
 416       writeSectionContent(SHeader, *S, CBA);
 417     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
 418       writeSectionContent(SHeader, *S, CBA);
 419     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
 420       writeSectionContent(SHeader, *S, CBA);
 421     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
 422       writeSectionContent(SHeader, *S, CBA);
 423     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
 424       SHeader.sh_entsize = 0;
 425       SHeader.sh_size = S->Size;
 426       // SHT_NOBITS section does not have content
 427       // so just to setup the section offset.
 428       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 429     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
 430       writeSectionContent(SHeader, *S, CBA);
 431     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
 432       writeSectionContent(SHeader, *S, CBA);
 433     } else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
 434       writeSectionContent(SHeader, *S, CBA);
 435     } else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
 436       writeSectionContent(SHeader, *S, CBA);
 437     } else if (auto S = dyn_cast<ELFYAML::StackSizesSection>(Sec)) {
 438       writeSectionContent(SHeader, *S, CBA);
 439     } else if (auto S = dyn_cast<ELFYAML::HashSection>(Sec)) {
 440       writeSectionContent(SHeader, *S, CBA);
 441     } else if (auto S = dyn_cast<ELFYAML::AddrsigSection>(Sec)) {
 442       writeSectionContent(SHeader, *S, CBA);
 443     } else {
 444       llvm_unreachable("Unknown section type");
 445     }
 446
 447     // Override the fields if requested.
 448     if (Sec) {
 449       if (Sec->ShName)
 450         SHeader.sh_name = *Sec->ShName;
 451       if (Sec->ShOffset)
 452         SHeader.sh_offset = *Sec->ShOffset;
 453       if (Sec->ShSize)
 454         SHeader.sh_size = *Sec->ShSize;
 455     }
 456   }
 457 }
 458
 459 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
 460   for (size_t I = 0; I < Symbols.size(); ++I)
 461     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
 462       return I;
 463   return Symbols.size();
 464 }
 465
 466 static uint64_t writeContent(raw_ostream &OS,
 467                              const Optional<yaml::BinaryRef> &Content,
 468                              const Optional<llvm::yaml::Hex64> &Size) {
 469   size_t ContentSize = 0;
 470   if (Content) {
 471     Content->writeAsBinary(OS);
 472     ContentSize = Content->binary_size();
 473   }
 474
 475   if (!Size)
 476     return ContentSize;
 477
 478   OS.write_zeros(*Size - ContentSize);
 479   return *Size;
 480 }
 481
 482 template <class ELFT>
 483 std::vector<typename ELFT::Sym>
 484 ELFState<ELFT>::toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
 485                              const StringTableBuilder &Strtab) {
 486   std::vector<Elf_Sym> Ret;
 487   Ret.resize(Symbols.size() + 1);
 488
 489   size_t I = 0;
 490   for (const auto &Sym : Symbols) {
 491     Elf_Sym &Symbol = Ret[++I];
 492
 493     // If NameIndex, which contains the name offset, is explicitly specified, we
 494     // use it. This is useful for preparing broken objects. Otherwise, we add
 495     // the specified Name to the string table builder to get its offset.
 496     if (Sym.NameIndex)
 497       Symbol.st_name = *Sym.NameIndex;
 498     else if (!Sym.Name.empty())
 499       Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
 500
 501     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
 502     if (!Sym.Section.empty())
 503       Symbol.st_shndx = toSectionIndex(Sym.Section, "", Sym.Name);
 504     else if (Sym.Index)
 505       Symbol.st_shndx = *Sym.Index;
 506
 507     Symbol.st_value = Sym.Value;
 508     Symbol.st_other = Sym.Other ? *Sym.Other : 0;
 509     Symbol.st_size = Sym.Size;
 510   }
 511
 512   return Ret;
 513 }
 514
 515 template <class ELFT>
 516 void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
 517                                              SymtabType STType,
 518                                              ContiguousBlobAccumulator &CBA,
 519                                              ELFYAML::Section *YAMLSec) {
 520
 521   bool IsStatic = STType == SymtabType::Static;
 522   ArrayRef<ELFYAML::Symbol> Symbols;
 523   if (IsStatic && Doc.Symbols)
 524     Symbols = *Doc.Symbols;
 525   else if (!IsStatic)
 526     Symbols = Doc.DynamicSymbols;
 527
 528   ELFYAML::RawContentSection *RawSec =
 529       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 530   if (RawSec && !Symbols.empty() && (RawSec->Content || RawSec->Size)) {
 531     if (RawSec->Content)
 532       reportError("cannot specify both `Content` and " +
 533                   (IsStatic ? Twine("`Symbols`") : Twine("`DynamicSymbols`")) +
 534                   " for symbol table section '" + RawSec->Name + "'");
 535     if (RawSec->Size)
 536       reportError("cannot specify both `Size` and " +
 537                   (IsStatic ? Twine("`Symbols`") : Twine("`DynamicSymbols`")) +
 538                   " for symbol table section '" + RawSec->Name + "'");
 539     return;
 540   }
 541
 542   zero(SHeader);
 543   SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
 544
 545   if (YAMLSec)
 546     SHeader.sh_type = YAMLSec->Type;
 547   else
 548     SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
 549
 550   if (RawSec && !RawSec->Link.empty()) {
 551     // If the Link field is explicitly defined in the document,
 552     // we should use it.
 553     SHeader.sh_link = toSectionIndex(RawSec->Link, RawSec->Name);
 554   } else {
 555     // When we describe the .dynsym section in the document explicitly, it is
 556     // allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
 557     // added implicitly and we should be able to leave the Link zeroed if
 558     // .dynstr is not defined.
 559     unsigned Link = 0;
 560     if (IsStatic)
 561       Link = SN2I.get(".strtab");
 562     else
 563       SN2I.lookup(".dynstr", Link);
 564     SHeader.sh_link = Link;
 565   }
 566
 567   if (YAMLSec && YAMLSec->Flags)
 568     SHeader.sh_flags = *YAMLSec->Flags;
 569   else if (!IsStatic)
 570     SHeader.sh_flags = ELF::SHF_ALLOC;
 571
 572   // If the symbol table section is explicitly described in the YAML
 573   // then we should set the fields requested.
 574   SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
 575                                              : findFirstNonGlobal(Symbols) + 1;
 576   SHeader.sh_entsize = (YAMLSec && YAMLSec->EntSize)
 577                            ? (uint64_t)(*YAMLSec->EntSize)
 578                            : sizeof(Elf_Sym);
 579   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
 580   SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
 581
 582   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 583   if (RawSec && (RawSec->Content || RawSec->Size)) {
 584     assert(Symbols.empty());
 585     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
 586     return;
 587   }
 588
 589   std::vector<Elf_Sym> Syms =
 590       toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
 591   writeArrayData(OS, makeArrayRef(Syms));
 592   SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
 593 }
 594
 595 template <class ELFT>
 596 void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
 597                                              StringTableBuilder &STB,
 598                                              ContiguousBlobAccumulator &CBA,
 599                                              ELFYAML::Section *YAMLSec) {
 600   zero(SHeader);
 601   SHeader.sh_name = DotShStrtab.getOffset(Name);
 602   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
 603   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
 604
 605   ELFYAML::RawContentSection *RawSec =
 606       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 607
 608   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 609   if (RawSec && (RawSec->Content || RawSec->Size)) {
 610     SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
 611   } else {
 612     STB.write(OS);
 613     SHeader.sh_size = STB.getSize();
 614   }
 615
 616   if (YAMLSec && YAMLSec->EntSize)
 617     SHeader.sh_entsize = *YAMLSec->EntSize;
 618
 619   if (RawSec && RawSec->Info)
 620     SHeader.sh_info = *RawSec->Info;
 621
 622   if (YAMLSec && YAMLSec->Flags)
 623     SHeader.sh_flags = *YAMLSec->Flags;
 624   else if (Name == ".dynstr")
 625     SHeader.sh_flags = ELF::SHF_ALLOC;
 626
 627   // If the section is explicitly described in the YAML
 628   // then we want to use its section address.
 629   if (YAMLSec)
 630     SHeader.sh_addr = YAMLSec->Address;
 631 }
 632
 633 template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
 634   ErrHandler(Msg);
 635   HasError = true;
 636 }
 637
 638 template <class ELFT>
 639 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
 640                                             std::vector<Elf_Shdr> &SHeaders) {
 641   uint32_t PhdrIdx = 0;
 642   for (auto &YamlPhdr : Doc.ProgramHeaders) {
 643     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
 644
 645     std::vector<Elf_Shdr *> Sections;
 646     for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
 647       unsigned Index;
 648       if (!SN2I.lookup(SecName.Section, Index)) {
 649         reportError("unknown section referenced: '" + SecName.Section +
 650                     "' by program header");
 651         continue;
 652       }
 653       Sections.push_back(&SHeaders[Index]);
 654     }
 655
 656     if (YamlPhdr.Offset) {
 657       PHeader.p_offset = *YamlPhdr.Offset;
 658     } else {
 659       if (YamlPhdr.Sections.size())
 660         PHeader.p_offset = UINT32_MAX;
 661       else
 662         PHeader.p_offset = 0;
 663
 664       // Find the minimum offset for the program header.
 665       for (Elf_Shdr *SHeader : Sections)
 666         PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
 667     }
 668
 669     // Find the maximum offset of the end of a section in order to set p_filesz
 670     // and p_memsz. When setting p_filesz, trailing SHT_NOBITS sections are not
 671     // counted.
 672     uint64_t FileOffset = PHeader.p_offset, MemOffset = PHeader.p_offset;
 673     for (Elf_Shdr *SHeader : Sections) {
 674       uint64_t End = SHeader->sh_offset + SHeader->sh_size;
 675       MemOffset = std::max(MemOffset, End);
 676
 677       if (SHeader->sh_type != llvm::ELF::SHT_NOBITS)
 678         FileOffset = std::max(FileOffset, End);
 679     }
 680
 681     // Set the file size and the memory size if not set explicitly.
 682     PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
 683                                          : FileOffset - PHeader.p_offset;
 684     PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
 685                                        : MemOffset - PHeader.p_offset;
 686
 687     if (YamlPhdr.Align) {
 688       PHeader.p_align = *YamlPhdr.Align;
 689     } else {
 690       // Set the alignment of the segment to be the maximum alignment of the
 691       // sections so that by default the segment has a valid and sensible
 692       // alignment.
 693       PHeader.p_align = 1;
 694       for (Elf_Shdr *SHeader : Sections)
 695         PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
 696     }
 697   }
 698 }
 699
 700 template <class ELFT>
 701 void ELFState<ELFT>::writeSectionContent(
 702     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
 703     ContiguousBlobAccumulator &CBA) {
 704   raw_ostream &OS =
 705       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 706   SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
 707
 708   if (Section.EntSize)
 709     SHeader.sh_entsize = *Section.EntSize;
 710   else if (Section.Type == llvm::ELF::SHT_RELR)
 711     SHeader.sh_entsize = sizeof(Elf_Relr);
 712   else
 713     SHeader.sh_entsize = 0;
 714
 715   if (Section.Info)
 716     SHeader.sh_info = *Section.Info;
 717 }
 718
 719 static bool isMips64EL(const ELFYAML::Object &Doc) {
 720   return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
 721          Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
 722          Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
 723 }
 724
 725 template <class ELFT>
 726 void ELFState<ELFT>::writeSectionContent(
 727     Elf_Shdr &SHeader, const ELFYAML::RelocationSection &Section,
 728     ContiguousBlobAccumulator &CBA) {
 729   assert((Section.Type == llvm::ELF::SHT_REL ||
 730           Section.Type == llvm::ELF::SHT_RELA) &&
 731          "Section type is not SHT_REL nor SHT_RELA");
 732
 733   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
 734   SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
 735   SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
 736
 737   // For relocation section set link to .symtab by default.
 738   if (Section.Link.empty())
 739     SHeader.sh_link = SN2I.get(".symtab");
 740
 741   if (!Section.RelocatableSec.empty())
 742     SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
 743
 744   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 745   for (const auto &Rel : Section.Relocations) {
 746     unsigned SymIdx = Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name,
 747                                                  Section.Link == ".dynsym")
 748                                  : 0;
 749     if (IsRela) {
 750       Elf_Rela REntry;
 751       zero(REntry);
 752       REntry.r_offset = Rel.Offset;
 753       REntry.r_addend = Rel.Addend;
 754       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 755       OS.write((const char *)&REntry, sizeof(REntry));
 756     } else {
 757       Elf_Rel REntry;
 758       zero(REntry);
 759       REntry.r_offset = Rel.Offset;
 760       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
 761       OS.write((const char *)&REntry, sizeof(REntry));
 762     }
 763   }
 764 }
 765
 766 template <class ELFT>
 767 void ELFState<ELFT>::writeSectionContent(
 768     Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
 769     ContiguousBlobAccumulator &CBA) {
 770   raw_ostream &OS =
 771       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 772
 773   for (uint32_t E : Shndx.Entries)
 774     support::endian::write<uint32_t>(OS, E, ELFT::TargetEndianness);
 775
 776   SHeader.sh_entsize = Shndx.EntSize ? (uint64_t)*Shndx.EntSize : 4;
 777   SHeader.sh_size = Shndx.Entries.size() * SHeader.sh_entsize;
 778 }
 779
 780 template <class ELFT>
 781 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 782                                          const ELFYAML::Group &Section,
 783                                          ContiguousBlobAccumulator &CBA) {
 784   assert(Section.Type == llvm::ELF::SHT_GROUP &&
 785          "Section type is not SHT_GROUP");
 786
 787   SHeader.sh_entsize = 4;
 788   SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
 789   SHeader.sh_info =
 790       toSymbolIndex(Section.Signature, Section.Name, /*IsDynamic=*/false);
 791
 792   raw_ostream &OS =
 793       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 794
 795   for (const ELFYAML::SectionOrType &Member : Section.Members) {
 796     unsigned int SectionIndex = 0;
 797     if (Member.sectionNameOrType == "GRP_COMDAT")
 798       SectionIndex = llvm::ELF::GRP_COMDAT;
 799     else
 800       SectionIndex = toSectionIndex(Member.sectionNameOrType, Section.Name);
 801     support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
 802   }
 803 }
 804
 805 template <class ELFT>
 806 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 807                                          const ELFYAML::SymverSection &Section,
 808                                          ContiguousBlobAccumulator &CBA) {
 809   raw_ostream &OS =
 810       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 811   for (uint16_t Version : Section.Entries)
 812     support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
 813
 814   SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
 815   SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
 816 }
 817
 818 template <class ELFT>
 819 void ELFState<ELFT>::writeSectionContent(
 820     Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
 821     ContiguousBlobAccumulator &CBA) {
 822   using uintX_t = typename ELFT::uint;
 823   raw_ostream &OS =
 824       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 825
 826   if (Section.Content || Section.Size) {
 827     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
 828     return;
 829   }
 830
 831   for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
 832     support::endian::write<uintX_t>(OS, E.Address, ELFT::TargetEndianness);
 833     SHeader.sh_size += sizeof(uintX_t) + encodeULEB128(E.Size, OS);
 834   }
 835 }
 836
 837 template <class ELFT>
 838 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 839                                          const ELFYAML::HashSection &Section,
 840                                          ContiguousBlobAccumulator &CBA) {
 841   raw_ostream &OS =
 842       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 843
 844   unsigned Link = 0;
 845   if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
 846     SHeader.sh_link = Link;
 847
 848   if (Section.Content || Section.Size) {
 849     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
 850     return;
 851   }
 852
 853   support::endian::write<uint32_t>(OS, Section.Bucket->size(),
 854                                    ELFT::TargetEndianness);
 855   support::endian::write<uint32_t>(OS, Section.Chain->size(),
 856                                    ELFT::TargetEndianness);
 857   for (uint32_t Val : *Section.Bucket)
 858     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
 859   for (uint32_t Val : *Section.Chain)
 860     support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
 861
 862   SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
 863 }
 864
 865 template <class ELFT>
 866 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 867                                          const ELFYAML::VerdefSection &Section,
 868                                          ContiguousBlobAccumulator &CBA) {
 869   typedef typename ELFT::Verdef Elf_Verdef;
 870   typedef typename ELFT::Verdaux Elf_Verdaux;
 871   raw_ostream &OS =
 872       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 873
 874   uint64_t AuxCnt = 0;
 875   for (size_t I = 0; I < Section.Entries.size(); ++I) {
 876     const ELFYAML::VerdefEntry &E = Section.Entries[I];
 877
 878     Elf_Verdef VerDef;
 879     VerDef.vd_version = E.Version;
 880     VerDef.vd_flags = E.Flags;
 881     VerDef.vd_ndx = E.VersionNdx;
 882     VerDef.vd_hash = E.Hash;
 883     VerDef.vd_aux = sizeof(Elf_Verdef);
 884     VerDef.vd_cnt = E.VerNames.size();
 885     if (I == Section.Entries.size() - 1)
 886       VerDef.vd_next = 0;
 887     else
 888       VerDef.vd_next =
 889           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
 890     OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
 891
 892     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
 893       Elf_Verdaux VernAux;
 894       VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
 895       if (J == E.VerNames.size() - 1)
 896         VernAux.vda_next = 0;
 897       else
 898         VernAux.vda_next = sizeof(Elf_Verdaux);
 899       OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
 900     }
 901   }
 902
 903   SHeader.sh_size = Section.Entries.size() * sizeof(Elf_Verdef) +
 904                     AuxCnt * sizeof(Elf_Verdaux);
 905   SHeader.sh_info = Section.Info;
 906 }
 907
 908 template <class ELFT>
 909 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 910                                          const ELFYAML::VerneedSection &Section,
 911                                          ContiguousBlobAccumulator &CBA) {
 912   typedef typename ELFT::Verneed Elf_Verneed;
 913   typedef typename ELFT::Vernaux Elf_Vernaux;
 914
 915   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 916
 917   uint64_t AuxCnt = 0;
 918   for (size_t I = 0; I < Section.VerneedV.size(); ++I) {
 919     const ELFYAML::VerneedEntry &VE = Section.VerneedV[I];
 920
 921     Elf_Verneed VerNeed;
 922     VerNeed.vn_version = VE.Version;
 923     VerNeed.vn_file = DotDynstr.getOffset(VE.File);
 924     if (I == Section.VerneedV.size() - 1)
 925       VerNeed.vn_next = 0;
 926     else
 927       VerNeed.vn_next =
 928           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
 929     VerNeed.vn_cnt = VE.AuxV.size();
 930     VerNeed.vn_aux = sizeof(Elf_Verneed);
 931     OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
 932
 933     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
 934       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
 935
 936       Elf_Vernaux VernAux;
 937       VernAux.vna_hash = VAuxE.Hash;
 938       VernAux.vna_flags = VAuxE.Flags;
 939       VernAux.vna_other = VAuxE.Other;
 940       VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
 941       if (J == VE.AuxV.size() - 1)
 942         VernAux.vna_next = 0;
 943       else
 944         VernAux.vna_next = sizeof(Elf_Vernaux);
 945       OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
 946     }
 947   }
 948
 949   SHeader.sh_size = Section.VerneedV.size() * sizeof(Elf_Verneed) +
 950                     AuxCnt * sizeof(Elf_Vernaux);
 951   SHeader.sh_info = Section.Info;
 952 }
 953
 954 template <class ELFT>
 955 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 956                                          const ELFYAML::MipsABIFlags &Section,
 957                                          ContiguousBlobAccumulator &CBA) {
 958   assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
 959          "Section type is not SHT_MIPS_ABIFLAGS");
 960
 961   object::Elf_Mips_ABIFlags<ELFT> Flags;
 962   zero(Flags);
 963   SHeader.sh_entsize = sizeof(Flags);
 964   SHeader.sh_size = SHeader.sh_entsize;
 965
 966   auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 967   Flags.version = Section.Version;
 968   Flags.isa_level = Section.ISALevel;
 969   Flags.isa_rev = Section.ISARevision;
 970   Flags.gpr_size = Section.GPRSize;
 971   Flags.cpr1_size = Section.CPR1Size;
 972   Flags.cpr2_size = Section.CPR2Size;
 973   Flags.fp_abi = Section.FpABI;
 974   Flags.isa_ext = Section.ISAExtension;
 975   Flags.ases = Section.ASEs;
 976   Flags.flags1 = Section.Flags1;
 977   Flags.flags2 = Section.Flags2;
 978   OS.write((const char *)&Flags, sizeof(Flags));
 979 }
 980
 981 template <class ELFT>
 982 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 983                                          const ELFYAML::DynamicSection &Section,
 984                                          ContiguousBlobAccumulator &CBA) {
 985   typedef typename ELFT::uint uintX_t;
 986
 987   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
 988          "Section type is not SHT_DYNAMIC");
 989
 990   if (!Section.Entries.empty() && Section.Content)
 991     reportError("cannot specify both raw content and explicit entries "
 992                 "for dynamic section '" +
 993                 Section.Name + "'");
 994
 995   if (Section.Content)
 996     SHeader.sh_size = Section.Content->binary_size();
 997   else
 998     SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
 999   if (Section.EntSize)
1000     SHeader.sh_entsize = *Section.EntSize;
1001   else
1002     SHeader.sh_entsize = sizeof(Elf_Dyn);
1003
1004   raw_ostream &OS =
1005       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1006   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
1007     support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
1008     support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
1009   }
1010   if (Section.Content)
1011     Section.Content->writeAsBinary(OS);
1012 }
1013
1014 template <class ELFT>
1015 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
1016                                          const ELFYAML::AddrsigSection &Section,
1017                                          ContiguousBlobAccumulator &CBA) {
1018   raw_ostream &OS =
1019       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
1020
1021   unsigned Link = 0;
1022   if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
1023     SHeader.sh_link = Link;
1024
1025   if (Section.Content || Section.Size) {
1026     SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
1027     return;
1028   }
1029
1030   for (const ELFYAML::AddrsigSymbol &Sym : *Section.Symbols) {
1031     uint64_t Val =
1032         Sym.Name ? toSymbolIndex(*Sym.Name, Section.Name, /*IsDynamic=*/false)
1033                  : (uint32_t)*Sym.Index;
1034     SHeader.sh_size += encodeULEB128(Val, OS);
1035   }
1036 }
1037
1038 template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
1039   for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
1040     StringRef Name = Doc.Sections[I]->Name;
1041     if (Name.empty())
1042       continue;
1043
1044     DotShStrtab.add(ELFYAML::dropUniqueSuffix(Name));
1045     if (!SN2I.addName(Name, I))
1046       reportError("repeated section name: '" + Name +
1047                   "' at YAML section number " + Twine(I));
1048   }
1049
1050   DotShStrtab.finalize();
1051 }
1052
1053 template <class ELFT> void ELFState<ELFT>::buildSymbolIndexes() {
1054   auto Build = [this](ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
1055     for (size_t I = 0, S = V.size(); I < S; ++I) {
1056       const ELFYAML::Symbol &Sym = V[I];
1057       if (!Sym.Name.empty() && !Map.addName(Sym.Name, I + 1))
1058         reportError("repeated symbol name: '" + Sym.Name + "'");
1059     }
1060   };
1061
1062   if (Doc.Symbols)
1063     Build(*Doc.Symbols, SymN2I);
1064   Build(Doc.DynamicSymbols, DynSymN2I);
1065 }
1066
1067 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
1068   // Add the regular symbol names to .strtab section.
1069   if (Doc.Symbols)
1070     for (const ELFYAML::Symbol &Sym : *Doc.Symbols)
1071       DotStrtab.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1072   DotStrtab.finalize();
1073
1074   // Add the dynamic symbol names to .dynstr section.
1075   for (const ELFYAML::Symbol &Sym : Doc.DynamicSymbols)
1076     DotDynstr.add(ELFYAML::dropUniqueSuffix(Sym.Name));
1077
1078   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
1079   // add strings to .dynstr section.
1080   for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
1081     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
1082       for (const ELFYAML::VerneedEntry &VE : VerNeed->VerneedV) {
1083         DotDynstr.add(VE.File);
1084         for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
1085           DotDynstr.add(Aux.Name);
1086       }
1087     } else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec.get())) {
1088       for (const ELFYAML::VerdefEntry &E : VerDef->Entries)
1089         for (StringRef Name : E.VerNames)
1090           DotDynstr.add(Name);
1091     }
1092   }
1093
1094   DotDynstr.finalize();
1095 }
1096
1097 template <class ELFT>
1098 bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
1099                               yaml::ErrorHandler EH) {
1100   ELFState<ELFT> State(Doc, EH);
1101
1102   // Finalize .strtab and .dynstr sections. We do that early because want to
1103   // finalize the string table builders before writing the content of the
1104   // sections that might want to use them.
1105   State.finalizeStrings();
1106
1107   State.buildSectionIndex();
1108   State.buildSymbolIndexes();
1109
1110   std::vector<Elf_Phdr> PHeaders;
1111   State.initProgramHeaders(PHeaders);
1112
1113   // XXX: This offset is tightly coupled with the order that we write
1114   // things to `OS`.
1115   const size_t SectionContentBeginOffset =
1116       sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
1117   ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
1118
1119   std::vector<Elf_Shdr> SHeaders;
1120   State.initSectionHeaders(SHeaders, CBA);
1121
1122   // Now we can decide segment offsets
1123   State.setProgramHeaderLayout(PHeaders, SHeaders);
1124
1125   if (State.HasError)
1126     return false;
1127
1128   State.writeELFHeader(CBA, OS);
1129   writeArrayData(OS, makeArrayRef(PHeaders));
1130   CBA.writeBlobToStream(OS);
1131   writeArrayData(OS, makeArrayRef(SHeaders));
1132   return true;
1133 }
1134
1135 namespace llvm {
1136 namespace yaml {
1137
1138 bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH) {
1139   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
1140   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
1141   if (Is64Bit) {
1142     if (IsLE)
1143       return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH);
1144     return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH);
1145   }
1146   if (IsLE)
1147     return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH);
1148   return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH);
1149 }
1150
1151 } // namespace yaml
1152 } // namespace llvm