1 //===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===// 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 // This file implements ELF object file writer information. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "ELFObjectWriter.h" 15 #include "llvm/ADT/STLExtras.h" 16 #include "llvm/ADT/StringMap.h" 17 #include "llvm/ADT/Twine.h" 18 #include "llvm/MC/MCAsmBackend.h" 19 #include "llvm/MC/MCAsmLayout.h" 20 #include "llvm/MC/MCContext.h" 21 #include "llvm/MC/MCExpr.h" 22 #include "llvm/MC/MCSectionELF.h" 23 #include "llvm/MC/MCValue.h" 24 #include "llvm/Support/Debug.h" 25 #include "llvm/Support/ErrorHandling.h" 26 #include "llvm/Support/ELF.h" 27 #include "llvm/Support/CommandLine.h" 28 #include "llvm/ADT/Statistic.h" 29 #include "llvm/ADT/StringSwitch.h" 30 31 #include "../Target/Mips/MCTargetDesc/MipsFixupKinds.h" 32 #include "../Target/X86/MCTargetDesc/X86FixupKinds.h" 33 #include "../Target/ARM/MCTargetDesc/ARMFixupKinds.h" 34 #include "../Target/PowerPC/MCTargetDesc/PPCFixupKinds.h" 35 36 #include <vector> 37 using namespace llvm; 38 39 #undef DEBUG_TYPE 40 #define DEBUG_TYPE "reloc-info" 41 42 bool ELFObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) { 43 const MCFixupKindInfo &FKI = 44 Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind); 45 46 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel; 47 } 48 49 bool ELFObjectWriter::RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) { 50 switch (Variant) { 51 default: 52 return false; 53 case MCSymbolRefExpr::VK_GOT: 54 case MCSymbolRefExpr::VK_PLT: 55 case MCSymbolRefExpr::VK_GOTPCREL: 56 case MCSymbolRefExpr::VK_GOTOFF: 57 case MCSymbolRefExpr::VK_TPOFF: 58 case MCSymbolRefExpr::VK_TLSGD: 59 case MCSymbolRefExpr::VK_GOTTPOFF: 60 case MCSymbolRefExpr::VK_INDNTPOFF: 61 case MCSymbolRefExpr::VK_NTPOFF: 62 case MCSymbolRefExpr::VK_GOTNTPOFF: 63 case MCSymbolRefExpr::VK_TLSLDM: 64 case MCSymbolRefExpr::VK_DTPOFF: 65 case MCSymbolRefExpr::VK_TLSLD: 66 return true; 67 } 68 } 69 70 ELFObjectWriter::~ELFObjectWriter() 71 {} 72 73 // Emit the ELF header. 74 void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize, 75 unsigned NumberOfSections) { 76 // ELF Header 77 // ---------- 78 // 79 // Note 80 // ---- 81 // emitWord method behaves differently for ELF32 and ELF64, writing 82 // 4 bytes in the former and 8 in the latter. 83 84 Write8(0x7f); // e_ident[EI_MAG0] 85 Write8('E'); // e_ident[EI_MAG1] 86 Write8('L'); // e_ident[EI_MAG2] 87 Write8('F'); // e_ident[EI_MAG3] 88 89 Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS] 90 91 // e_ident[EI_DATA] 92 Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB); 93 94 Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION] 95 // e_ident[EI_OSABI] 96 switch (TargetObjectWriter->getOSType()) { 97 case Triple::FreeBSD: Write8(ELF::ELFOSABI_FREEBSD); break; 98 case Triple::Linux: Write8(ELF::ELFOSABI_LINUX); break; 99 default: Write8(ELF::ELFOSABI_NONE); break; 100 } 101 Write8(0); // e_ident[EI_ABIVERSION] 102 103 WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD); 104 105 Write16(ELF::ET_REL); // e_type 106 107 Write16(TargetObjectWriter->getEMachine()); // e_machine = target 108 109 Write32(ELF::EV_CURRENT); // e_version 110 WriteWord(0); // e_entry, no entry point in .o file 111 WriteWord(0); // e_phoff, no program header for .o 112 WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) : 113 sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes 114 115 // e_flags = whatever the target wants 116 WriteEFlags(); 117 118 // e_ehsize = ELF header size 119 Write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr)); 120 121 Write16(0); // e_phentsize = prog header entry size 122 Write16(0); // e_phnum = # prog header entries = 0 123 124 // e_shentsize = Section header entry size 125 Write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr)); 126 127 // e_shnum = # of section header ents 128 if (NumberOfSections >= ELF::SHN_LORESERVE) 129 Write16(ELF::SHN_UNDEF); 130 else 131 Write16(NumberOfSections); 132 133 // e_shstrndx = Section # of '.shstrtab' 134 if (ShstrtabIndex >= ELF::SHN_LORESERVE) 135 Write16(ELF::SHN_XINDEX); 136 else 137 Write16(ShstrtabIndex); 138 } 139 140 void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF, 141 MCDataFragment *ShndxF, 142 uint64_t name, 143 uint8_t info, uint64_t value, 144 uint64_t size, uint8_t other, 145 uint32_t shndx, 146 bool Reserved) { 147 if (ShndxF) { 148 if (shndx >= ELF::SHN_LORESERVE && !Reserved) 149 String32(*ShndxF, shndx); 150 else 151 String32(*ShndxF, 0); 152 } 153 154 uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ? 155 uint16_t(ELF::SHN_XINDEX) : shndx; 156 157 if (is64Bit()) { 158 String32(*SymtabF, name); // st_name 159 String8(*SymtabF, info); // st_info 160 String8(*SymtabF, other); // st_other 161 String16(*SymtabF, Index); // st_shndx 162 String64(*SymtabF, value); // st_value 163 String64(*SymtabF, size); // st_size 164 } else { 165 String32(*SymtabF, name); // st_name 166 String32(*SymtabF, value); // st_value 167 String32(*SymtabF, size); // st_size 168 String8(*SymtabF, info); // st_info 169 String8(*SymtabF, other); // st_other 170 String16(*SymtabF, Index); // st_shndx 171 } 172 } 173 174 uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data, 175 const MCAsmLayout &Layout) { 176 if (Data.isCommon() && Data.isExternal()) 177 return Data.getCommonAlignment(); 178 179 const MCSymbol &Symbol = Data.getSymbol(); 180 181 if (Symbol.isAbsolute() && Symbol.isVariable()) { 182 if (const MCExpr *Value = Symbol.getVariableValue()) { 183 int64_t IntValue; 184 if (Value->EvaluateAsAbsolute(IntValue, Layout)) 185 return (uint64_t)IntValue; 186 } 187 } 188 189 if (!Symbol.isInSection()) 190 return 0; 191 192 193 if (Data.getFragment()) { 194 if (Data.getFlags() & ELF_Other_ThumbFunc) 195 return Layout.getSymbolOffset(&Data)+1; 196 else 197 return Layout.getSymbolOffset(&Data); 198 } 199 200 return 0; 201 } 202 203 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm, 204 const MCAsmLayout &Layout) { 205 // The presence of symbol versions causes undefined symbols and 206 // versions declared with @@@ to be renamed. 207 208 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), 209 ie = Asm.symbol_end(); it != ie; ++it) { 210 const MCSymbol &Alias = it->getSymbol(); 211 const MCSymbol &Symbol = Alias.AliasedSymbol(); 212 MCSymbolData &SD = Asm.getSymbolData(Symbol); 213 214 // Not an alias. 215 if (&Symbol == &Alias) 216 continue; 217 218 StringRef AliasName = Alias.getName(); 219 size_t Pos = AliasName.find('@'); 220 if (Pos == StringRef::npos) 221 continue; 222 223 // Aliases defined with .symvar copy the binding from the symbol they alias. 224 // This is the first place we are able to copy this information. 225 it->setExternal(SD.isExternal()); 226 MCELF::SetBinding(*it, MCELF::GetBinding(SD)); 227 228 StringRef Rest = AliasName.substr(Pos); 229 if (!Symbol.isUndefined() && !Rest.startswith("@@@")) 230 continue; 231 232 // FIXME: produce a better error message. 233 if (Symbol.isUndefined() && Rest.startswith("@@") && 234 !Rest.startswith("@@@")) 235 report_fatal_error("A @@ version cannot be undefined"); 236 237 Renames.insert(std::make_pair(&Symbol, &Alias)); 238 } 239 } 240 241 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF, 242 MCDataFragment *ShndxF, 243 ELFSymbolData &MSD, 244 const MCAsmLayout &Layout) { 245 MCSymbolData &OrigData = *MSD.SymbolData; 246 MCSymbolData &Data = 247 Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol()); 248 249 bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() || 250 Data.getSymbol().isVariable(); 251 252 uint8_t Binding = MCELF::GetBinding(OrigData); 253 uint8_t Visibility = MCELF::GetVisibility(OrigData); 254 uint8_t Type = MCELF::GetType(Data); 255 256 uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift); 257 uint8_t Other = Visibility; 258 259 uint64_t Value = SymbolValue(Data, Layout); 260 uint64_t Size = 0; 261 262 assert(!(Data.isCommon() && !Data.isExternal())); 263 264 const MCExpr *ESize = Data.getSize(); 265 if (ESize) { 266 int64_t Res; 267 if (!ESize->EvaluateAsAbsolute(Res, Layout)) 268 report_fatal_error("Size expression must be absolute."); 269 Size = Res; 270 } 271 272 // Write out the symbol table entry 273 WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value, 274 Size, Other, MSD.SectionIndex, IsReserved); 275 } 276 277 void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF, 278 MCDataFragment *ShndxF, 279 const MCAssembler &Asm, 280 const MCAsmLayout &Layout, 281 const SectionIndexMapTy &SectionIndexMap) { 282 // The string table must be emitted first because we need the index 283 // into the string table for all the symbol names. 284 assert(StringTable.size() && "Missing string table"); 285 286 // FIXME: Make sure the start of the symbol table is aligned. 287 288 // The first entry is the undefined symbol entry. 289 WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false); 290 291 // Write the symbol table entries. 292 LastLocalSymbolIndex = LocalSymbolData.size() + 1; 293 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) { 294 ELFSymbolData &MSD = LocalSymbolData[i]; 295 WriteSymbol(SymtabF, ShndxF, MSD, Layout); 296 } 297 298 // Write out a symbol table entry for each regular section. 299 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; 300 ++i) { 301 const MCSectionELF &Section = 302 static_cast<const MCSectionELF&>(i->getSection()); 303 if (Section.getType() == ELF::SHT_RELA || 304 Section.getType() == ELF::SHT_REL || 305 Section.getType() == ELF::SHT_STRTAB || 306 Section.getType() == ELF::SHT_SYMTAB || 307 Section.getType() == ELF::SHT_SYMTAB_SHNDX) 308 continue; 309 WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0, 310 ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section), 311 false); 312 LastLocalSymbolIndex++; 313 } 314 315 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) { 316 ELFSymbolData &MSD = ExternalSymbolData[i]; 317 MCSymbolData &Data = *MSD.SymbolData; 318 assert(((Data.getFlags() & ELF_STB_Global) || 319 (Data.getFlags() & ELF_STB_Weak)) && 320 "External symbol requires STB_GLOBAL or STB_WEAK flag"); 321 WriteSymbol(SymtabF, ShndxF, MSD, Layout); 322 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL) 323 LastLocalSymbolIndex++; 324 } 325 326 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) { 327 ELFSymbolData &MSD = UndefinedSymbolData[i]; 328 MCSymbolData &Data = *MSD.SymbolData; 329 WriteSymbol(SymtabF, ShndxF, MSD, Layout); 330 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL) 331 LastLocalSymbolIndex++; 332 } 333 } 334 335 const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm, 336 const MCValue &Target, 337 const MCFragment &F, 338 const MCFixup &Fixup, 339 bool IsPCRel) const { 340 const MCSymbol &Symbol = Target.getSymA()->getSymbol(); 341 const MCSymbol &ASymbol = Symbol.AliasedSymbol(); 342 const MCSymbol *Renamed = Renames.lookup(&Symbol); 343 const MCSymbolData &SD = Asm.getSymbolData(Symbol); 344 345 if (ASymbol.isUndefined()) { 346 if (Renamed) 347 return Renamed; 348 return &ASymbol; 349 } 350 351 if (SD.isExternal()) { 352 if (Renamed) 353 return Renamed; 354 return &Symbol; 355 } 356 357 const MCSectionELF &Section = 358 static_cast<const MCSectionELF&>(ASymbol.getSection()); 359 const SectionKind secKind = Section.getKind(); 360 361 if (secKind.isBSS()) 362 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); 363 364 if (secKind.isThreadLocal()) { 365 if (Renamed) 366 return Renamed; 367 return &Symbol; 368 } 369 370 MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind(); 371 const MCSectionELF &Sec2 = 372 static_cast<const MCSectionELF&>(F.getParent()->getSection()); 373 374 if (&Sec2 != &Section && 375 (Kind == MCSymbolRefExpr::VK_PLT || 376 Kind == MCSymbolRefExpr::VK_GOTPCREL || 377 Kind == MCSymbolRefExpr::VK_GOTOFF)) { 378 if (Renamed) 379 return Renamed; 380 return &Symbol; 381 } 382 383 if (Section.getFlags() & ELF::SHF_MERGE) { 384 if (Target.getConstant() == 0) 385 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); 386 if (Renamed) 387 return Renamed; 388 return &Symbol; 389 } 390 391 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel); 392 393 } 394 395 396 void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, 397 const MCAsmLayout &Layout, 398 const MCFragment *Fragment, 399 const MCFixup &Fixup, 400 MCValue Target, 401 uint64_t &FixedValue) { 402 int64_t Addend = 0; 403 int Index = 0; 404 int64_t Value = Target.getConstant(); 405 const MCSymbol *RelocSymbol = NULL; 406 407 bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind()); 408 if (!Target.isAbsolute()) { 409 const MCSymbol &Symbol = Target.getSymA()->getSymbol(); 410 const MCSymbol &ASymbol = Symbol.AliasedSymbol(); 411 RelocSymbol = SymbolToReloc(Asm, Target, *Fragment, Fixup, IsPCRel); 412 413 if (const MCSymbolRefExpr *RefB = Target.getSymB()) { 414 const MCSymbol &SymbolB = RefB->getSymbol(); 415 MCSymbolData &SDB = Asm.getSymbolData(SymbolB); 416 IsPCRel = true; 417 418 // Offset of the symbol in the section 419 int64_t a = Layout.getSymbolOffset(&SDB); 420 421 // Offset of the relocation in the section 422 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); 423 Value += b - a; 424 } 425 426 if (!RelocSymbol) { 427 MCSymbolData &SD = Asm.getSymbolData(ASymbol); 428 MCFragment *F = SD.getFragment(); 429 430 Index = F->getParent()->getOrdinal() + 1; 431 432 // Offset of the symbol in the section 433 Value += Layout.getSymbolOffset(&SD); 434 } else { 435 if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref) 436 WeakrefUsedInReloc.insert(RelocSymbol); 437 else 438 UsedInReloc.insert(RelocSymbol); 439 Index = -1; 440 } 441 Addend = Value; 442 // Compensate for the addend on i386. 443 if (is64Bit()) 444 Value = 0; 445 } 446 447 FixedValue = Value; 448 unsigned Type = GetRelocType(Target, Fixup, IsPCRel, 449 (RelocSymbol != 0), Addend); 450 451 uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) + 452 Fixup.getOffset(); 453 454 adjustFixupOffset(Fixup, RelocOffset); 455 456 if (!hasRelocationAddend()) 457 Addend = 0; 458 459 if (is64Bit()) 460 assert(isInt<64>(Addend)); 461 else 462 assert(isInt<32>(Addend)); 463 464 ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend); 465 Relocations[Fragment->getParent()].push_back(ERE); 466 } 467 468 469 uint64_t 470 ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm, 471 const MCSymbol *S) { 472 MCSymbolData &SD = Asm.getSymbolData(*S); 473 return SD.getIndex(); 474 } 475 476 bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm, 477 const MCSymbolData &Data, 478 bool Used, bool Renamed) { 479 if (Data.getFlags() & ELF_Other_Weakref) 480 return false; 481 482 if (Used) 483 return true; 484 485 if (Renamed) 486 return false; 487 488 const MCSymbol &Symbol = Data.getSymbol(); 489 490 if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_") 491 return true; 492 493 const MCSymbol &A = Symbol.AliasedSymbol(); 494 if (Symbol.isVariable() && !A.isVariable() && A.isUndefined()) 495 return false; 496 497 bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL; 498 if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal) 499 return false; 500 501 if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined()) 502 return false; 503 504 if (Symbol.isTemporary()) 505 return false; 506 507 return true; 508 } 509 510 bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature, 511 bool isUsedInReloc) { 512 if (Data.isExternal()) 513 return false; 514 515 const MCSymbol &Symbol = Data.getSymbol(); 516 const MCSymbol &RefSymbol = Symbol.AliasedSymbol(); 517 518 if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) { 519 if (isSignature && !isUsedInReloc) 520 return true; 521 522 return false; 523 } 524 525 return true; 526 } 527 528 void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm, 529 SectionIndexMapTy &SectionIndexMap, 530 const RelMapTy &RelMap) { 531 unsigned Index = 1; 532 for (MCAssembler::iterator it = Asm.begin(), 533 ie = Asm.end(); it != ie; ++it) { 534 const MCSectionELF &Section = 535 static_cast<const MCSectionELF &>(it->getSection()); 536 if (Section.getType() != ELF::SHT_GROUP) 537 continue; 538 SectionIndexMap[&Section] = Index++; 539 } 540 541 for (MCAssembler::iterator it = Asm.begin(), 542 ie = Asm.end(); it != ie; ++it) { 543 const MCSectionELF &Section = 544 static_cast<const MCSectionELF &>(it->getSection()); 545 if (Section.getType() == ELF::SHT_GROUP || 546 Section.getType() == ELF::SHT_REL || 547 Section.getType() == ELF::SHT_RELA) 548 continue; 549 SectionIndexMap[&Section] = Index++; 550 const MCSectionELF *RelSection = RelMap.lookup(&Section); 551 if (RelSection) 552 SectionIndexMap[RelSection] = Index++; 553 } 554 } 555 556 void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm, 557 const SectionIndexMapTy &SectionIndexMap, 558 RevGroupMapTy RevGroupMap, 559 unsigned NumRegularSections) { 560 // FIXME: Is this the correct place to do this? 561 // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed? 562 if (NeedsGOT) { 563 llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_"; 564 MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name); 565 MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym); 566 Data.setExternal(true); 567 MCELF::SetBinding(Data, ELF::STB_GLOBAL); 568 } 569 570 // Index 0 is always the empty string. 571 StringMap<uint64_t> StringIndexMap; 572 StringTable += '\x00'; 573 574 // FIXME: We could optimize suffixes in strtab in the same way we 575 // optimize them in shstrtab. 576 577 // Add the data for the symbols. 578 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), 579 ie = Asm.symbol_end(); it != ie; ++it) { 580 const MCSymbol &Symbol = it->getSymbol(); 581 582 bool Used = UsedInReloc.count(&Symbol); 583 bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol); 584 bool isSignature = RevGroupMap.count(&Symbol); 585 586 if (!isInSymtab(Asm, *it, 587 Used || WeakrefUsed || isSignature, 588 Renames.count(&Symbol))) 589 continue; 590 591 ELFSymbolData MSD; 592 MSD.SymbolData = it; 593 const MCSymbol &RefSymbol = Symbol.AliasedSymbol(); 594 595 // Undefined symbols are global, but this is the first place we 596 // are able to set it. 597 bool Local = isLocal(*it, isSignature, Used); 598 if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) { 599 MCSymbolData &SD = Asm.getSymbolData(RefSymbol); 600 MCELF::SetBinding(*it, ELF::STB_GLOBAL); 601 MCELF::SetBinding(SD, ELF::STB_GLOBAL); 602 } 603 604 if (RefSymbol.isUndefined() && !Used && WeakrefUsed) 605 MCELF::SetBinding(*it, ELF::STB_WEAK); 606 607 if (it->isCommon()) { 608 assert(!Local); 609 MSD.SectionIndex = ELF::SHN_COMMON; 610 } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) { 611 MSD.SectionIndex = ELF::SHN_ABS; 612 } else if (RefSymbol.isUndefined()) { 613 if (isSignature && !Used) 614 MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]); 615 else 616 MSD.SectionIndex = ELF::SHN_UNDEF; 617 } else { 618 const MCSectionELF &Section = 619 static_cast<const MCSectionELF&>(RefSymbol.getSection()); 620 MSD.SectionIndex = SectionIndexMap.lookup(&Section); 621 if (MSD.SectionIndex >= ELF::SHN_LORESERVE) 622 NeedsSymtabShndx = true; 623 assert(MSD.SectionIndex && "Invalid section index!"); 624 } 625 626 // The @@@ in symbol version is replaced with @ in undefined symbols and 627 // @@ in defined ones. 628 StringRef Name = Symbol.getName(); 629 SmallString<32> Buf; 630 631 size_t Pos = Name.find("@@@"); 632 if (Pos != StringRef::npos) { 633 Buf += Name.substr(0, Pos); 634 unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1; 635 Buf += Name.substr(Pos + Skip); 636 Name = Buf; 637 } 638 639 uint64_t &Entry = StringIndexMap[Name]; 640 if (!Entry) { 641 Entry = StringTable.size(); 642 StringTable += Name; 643 StringTable += '\x00'; 644 } 645 MSD.StringIndex = Entry; 646 if (MSD.SectionIndex == ELF::SHN_UNDEF) 647 UndefinedSymbolData.push_back(MSD); 648 else if (Local) 649 LocalSymbolData.push_back(MSD); 650 else 651 ExternalSymbolData.push_back(MSD); 652 } 653 654 // Symbols are required to be in lexicographic order. 655 array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end()); 656 array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end()); 657 array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end()); 658 659 // Set the symbol indices. Local symbols must come before all other 660 // symbols with non-local bindings. 661 unsigned Index = 1; 662 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) 663 LocalSymbolData[i].SymbolData->setIndex(Index++); 664 665 Index += NumRegularSections; 666 667 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) 668 ExternalSymbolData[i].SymbolData->setIndex(Index++); 669 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) 670 UndefinedSymbolData[i].SymbolData->setIndex(Index++); 671 672 if (NumRegularSections > ELF::SHN_LORESERVE) 673 NeedsSymtabShndx = true; 674 } 675 676 void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm, 677 MCAsmLayout &Layout, 678 RelMapTy &RelMap) { 679 for (MCAssembler::const_iterator it = Asm.begin(), 680 ie = Asm.end(); it != ie; ++it) { 681 const MCSectionData &SD = *it; 682 if (Relocations[&SD].empty()) 683 continue; 684 685 MCContext &Ctx = Asm.getContext(); 686 const MCSectionELF &Section = 687 static_cast<const MCSectionELF&>(SD.getSection()); 688 689 const StringRef SectionName = Section.getSectionName(); 690 std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel"; 691 RelaSectionName += SectionName; 692 693 unsigned EntrySize; 694 if (hasRelocationAddend()) 695 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela); 696 else 697 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel); 698 699 const MCSectionELF *RelaSection = 700 Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ? 701 ELF::SHT_RELA : ELF::SHT_REL, 0, 702 SectionKind::getReadOnly(), 703 EntrySize, ""); 704 RelMap[&Section] = RelaSection; 705 Asm.getOrCreateSectionData(*RelaSection); 706 } 707 } 708 709 void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout, 710 const RelMapTy &RelMap) { 711 for (MCAssembler::const_iterator it = Asm.begin(), 712 ie = Asm.end(); it != ie; ++it) { 713 const MCSectionData &SD = *it; 714 const MCSectionELF &Section = 715 static_cast<const MCSectionELF&>(SD.getSection()); 716 717 const MCSectionELF *RelaSection = RelMap.lookup(&Section); 718 if (!RelaSection) 719 continue; 720 MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection); 721 RelaSD.setAlignment(is64Bit() ? 8 : 4); 722 723 MCDataFragment *F = new MCDataFragment(&RelaSD); 724 WriteRelocationsFragment(Asm, F, &*it); 725 } 726 } 727 728 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type, 729 uint64_t Flags, uint64_t Address, 730 uint64_t Offset, uint64_t Size, 731 uint32_t Link, uint32_t Info, 732 uint64_t Alignment, 733 uint64_t EntrySize) { 734 Write32(Name); // sh_name: index into string table 735 Write32(Type); // sh_type 736 WriteWord(Flags); // sh_flags 737 WriteWord(Address); // sh_addr 738 WriteWord(Offset); // sh_offset 739 WriteWord(Size); // sh_size 740 Write32(Link); // sh_link 741 Write32(Info); // sh_info 742 WriteWord(Alignment); // sh_addralign 743 WriteWord(EntrySize); // sh_entsize 744 } 745 746 void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm, 747 MCDataFragment *F, 748 const MCSectionData *SD) { 749 std::vector<ELFRelocationEntry> &Relocs = Relocations[SD]; 750 // sort by the r_offset just like gnu as does 751 array_pod_sort(Relocs.begin(), Relocs.end()); 752 753 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) { 754 ELFRelocationEntry entry = Relocs[e - i - 1]; 755 756 if (!entry.Index) 757 ; 758 else if (entry.Index < 0) 759 entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol); 760 else 761 entry.Index += LocalSymbolData.size(); 762 if (is64Bit()) { 763 String64(*F, entry.r_offset); 764 765 struct ELF::Elf64_Rela ERE64; 766 ERE64.setSymbolAndType(entry.Index, entry.Type); 767 String64(*F, ERE64.r_info); 768 769 if (hasRelocationAddend()) 770 String64(*F, entry.r_addend); 771 } else { 772 String32(*F, entry.r_offset); 773 774 struct ELF::Elf32_Rela ERE32; 775 ERE32.setSymbolAndType(entry.Index, entry.Type); 776 String32(*F, ERE32.r_info); 777 778 if (hasRelocationAddend()) 779 String32(*F, entry.r_addend); 780 } 781 } 782 } 783 784 static int compareBySuffix(const void *a, const void *b) { 785 const MCSectionELF *secA = *static_cast<const MCSectionELF* const *>(a); 786 const MCSectionELF *secB = *static_cast<const MCSectionELF* const *>(b); 787 const StringRef &NameA = secA->getSectionName(); 788 const StringRef &NameB = secB->getSectionName(); 789 const unsigned sizeA = NameA.size(); 790 const unsigned sizeB = NameB.size(); 791 const unsigned len = std::min(sizeA, sizeB); 792 for (unsigned int i = 0; i < len; ++i) { 793 char ca = NameA[sizeA - i - 1]; 794 char cb = NameB[sizeB - i - 1]; 795 if (ca != cb) 796 return cb - ca; 797 } 798 799 return sizeB - sizeA; 800 } 801 802 void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm, 803 MCAsmLayout &Layout, 804 SectionIndexMapTy &SectionIndexMap, 805 const RelMapTy &RelMap) { 806 MCContext &Ctx = Asm.getContext(); 807 MCDataFragment *F; 808 809 unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32; 810 811 // We construct .shstrtab, .symtab and .strtab in this order to match gnu as. 812 const MCSectionELF *ShstrtabSection = 813 Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0, 814 SectionKind::getReadOnly()); 815 MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection); 816 ShstrtabSD.setAlignment(1); 817 818 const MCSectionELF *SymtabSection = 819 Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, 820 SectionKind::getReadOnly(), 821 EntrySize, ""); 822 MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection); 823 SymtabSD.setAlignment(is64Bit() ? 8 : 4); 824 825 MCSectionData *SymtabShndxSD = NULL; 826 827 if (NeedsSymtabShndx) { 828 const MCSectionELF *SymtabShndxSection = 829 Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0, 830 SectionKind::getReadOnly(), 4, ""); 831 SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection); 832 SymtabShndxSD->setAlignment(4); 833 } 834 835 const MCSectionELF *StrtabSection; 836 StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0, 837 SectionKind::getReadOnly()); 838 MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection); 839 StrtabSD.setAlignment(1); 840 841 ComputeIndexMap(Asm, SectionIndexMap, RelMap); 842 843 ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection); 844 SymbolTableIndex = SectionIndexMap.lookup(SymtabSection); 845 StringTableIndex = SectionIndexMap.lookup(StrtabSection); 846 847 // Symbol table 848 F = new MCDataFragment(&SymtabSD); 849 MCDataFragment *ShndxF = NULL; 850 if (NeedsSymtabShndx) { 851 ShndxF = new MCDataFragment(SymtabShndxSD); 852 } 853 WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap); 854 855 F = new MCDataFragment(&StrtabSD); 856 F->getContents().append(StringTable.begin(), StringTable.end()); 857 858 F = new MCDataFragment(&ShstrtabSD); 859 860 std::vector<const MCSectionELF*> Sections; 861 for (MCAssembler::const_iterator it = Asm.begin(), 862 ie = Asm.end(); it != ie; ++it) { 863 const MCSectionELF &Section = 864 static_cast<const MCSectionELF&>(it->getSection()); 865 Sections.push_back(&Section); 866 } 867 array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix); 868 869 // Section header string table. 870 // 871 // The first entry of a string table holds a null character so skip 872 // section 0. 873 uint64_t Index = 1; 874 F->getContents() += '\x00'; 875 876 for (unsigned int I = 0, E = Sections.size(); I != E; ++I) { 877 const MCSectionELF &Section = *Sections[I]; 878 879 StringRef Name = Section.getSectionName(); 880 if (I != 0) { 881 StringRef PreviousName = Sections[I - 1]->getSectionName(); 882 if (PreviousName.endswith(Name)) { 883 SectionStringTableIndex[&Section] = Index - Name.size() - 1; 884 continue; 885 } 886 } 887 // Remember the index into the string table so we can write it 888 // into the sh_name field of the section header table. 889 SectionStringTableIndex[&Section] = Index; 890 891 Index += Name.size() + 1; 892 F->getContents() += Name; 893 F->getContents() += '\x00'; 894 } 895 } 896 897 void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, 898 MCAsmLayout &Layout, 899 GroupMapTy &GroupMap, 900 RevGroupMapTy &RevGroupMap, 901 SectionIndexMapTy &SectionIndexMap, 902 const RelMapTy &RelMap) { 903 // Create the .note.GNU-stack section if needed. 904 MCContext &Ctx = Asm.getContext(); 905 if (Asm.getNoExecStack()) { 906 const MCSectionELF *GnuStackSection = 907 Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0, 908 SectionKind::getReadOnly()); 909 Asm.getOrCreateSectionData(*GnuStackSection); 910 } 911 912 // Build the groups 913 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); 914 it != ie; ++it) { 915 const MCSectionELF &Section = 916 static_cast<const MCSectionELF&>(it->getSection()); 917 if (!(Section.getFlags() & ELF::SHF_GROUP)) 918 continue; 919 920 const MCSymbol *SignatureSymbol = Section.getGroup(); 921 Asm.getOrCreateSymbolData(*SignatureSymbol); 922 const MCSectionELF *&Group = RevGroupMap[SignatureSymbol]; 923 if (!Group) { 924 Group = Ctx.CreateELFGroupSection(); 925 MCSectionData &Data = Asm.getOrCreateSectionData(*Group); 926 Data.setAlignment(4); 927 MCDataFragment *F = new MCDataFragment(&Data); 928 String32(*F, ELF::GRP_COMDAT); 929 } 930 GroupMap[Group] = SignatureSymbol; 931 } 932 933 ComputeIndexMap(Asm, SectionIndexMap, RelMap); 934 935 // Add sections to the groups 936 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); 937 it != ie; ++it) { 938 const MCSectionELF &Section = 939 static_cast<const MCSectionELF&>(it->getSection()); 940 if (!(Section.getFlags() & ELF::SHF_GROUP)) 941 continue; 942 const MCSectionELF *Group = RevGroupMap[Section.getGroup()]; 943 MCSectionData &Data = Asm.getOrCreateSectionData(*Group); 944 // FIXME: we could use the previous fragment 945 MCDataFragment *F = new MCDataFragment(&Data); 946 unsigned Index = SectionIndexMap.lookup(&Section); 947 String32(*F, Index); 948 } 949 } 950 951 void ELFObjectWriter::WriteSection(MCAssembler &Asm, 952 const SectionIndexMapTy &SectionIndexMap, 953 uint32_t GroupSymbolIndex, 954 uint64_t Offset, uint64_t Size, 955 uint64_t Alignment, 956 const MCSectionELF &Section) { 957 uint64_t sh_link = 0; 958 uint64_t sh_info = 0; 959 960 switch(Section.getType()) { 961 case ELF::SHT_DYNAMIC: 962 sh_link = SectionStringTableIndex[&Section]; 963 sh_info = 0; 964 break; 965 966 case ELF::SHT_REL: 967 case ELF::SHT_RELA: { 968 const MCSectionELF *SymtabSection; 969 const MCSectionELF *InfoSection; 970 SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB, 971 0, 972 SectionKind::getReadOnly()); 973 sh_link = SectionIndexMap.lookup(SymtabSection); 974 assert(sh_link && ".symtab not found"); 975 976 // Remove ".rel" and ".rela" prefixes. 977 unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5; 978 StringRef SectionName = Section.getSectionName().substr(SecNameLen); 979 980 InfoSection = Asm.getContext().getELFSection(SectionName, 981 ELF::SHT_PROGBITS, 0, 982 SectionKind::getReadOnly()); 983 sh_info = SectionIndexMap.lookup(InfoSection); 984 break; 985 } 986 987 case ELF::SHT_SYMTAB: 988 case ELF::SHT_DYNSYM: 989 sh_link = StringTableIndex; 990 sh_info = LastLocalSymbolIndex; 991 break; 992 993 case ELF::SHT_SYMTAB_SHNDX: 994 sh_link = SymbolTableIndex; 995 break; 996 997 case ELF::SHT_PROGBITS: 998 case ELF::SHT_STRTAB: 999 case ELF::SHT_NOBITS: 1000 case ELF::SHT_NOTE: 1001 case ELF::SHT_NULL: 1002 case ELF::SHT_ARM_ATTRIBUTES: 1003 case ELF::SHT_INIT_ARRAY: 1004 case ELF::SHT_FINI_ARRAY: 1005 case ELF::SHT_PREINIT_ARRAY: 1006 case ELF::SHT_X86_64_UNWIND: 1007 // Nothing to do. 1008 break; 1009 1010 case ELF::SHT_GROUP: 1011 sh_link = SymbolTableIndex; 1012 sh_info = GroupSymbolIndex; 1013 break; 1014 1015 default: 1016 assert(0 && "FIXME: sh_type value not supported!"); 1017 break; 1018 } 1019 1020 WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(), 1021 Section.getFlags(), 0, Offset, Size, sh_link, sh_info, 1022 Alignment, Section.getEntrySize()); 1023 } 1024 1025 bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) { 1026 return SD.getOrdinal() == ~UINT32_C(0) && 1027 !SD.getSection().isVirtualSection(); 1028 } 1029 1030 uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) { 1031 uint64_t Ret = 0; 1032 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e; 1033 ++i) { 1034 const MCFragment &F = *i; 1035 assert(F.getKind() == MCFragment::FT_Data); 1036 Ret += cast<MCDataFragment>(F).getContents().size(); 1037 } 1038 return Ret; 1039 } 1040 1041 uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout, 1042 const MCSectionData &SD) { 1043 if (IsELFMetaDataSection(SD)) 1044 return DataSectionSize(SD); 1045 return Layout.getSectionFileSize(&SD); 1046 } 1047 1048 uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout, 1049 const MCSectionData &SD) { 1050 if (IsELFMetaDataSection(SD)) 1051 return DataSectionSize(SD); 1052 return Layout.getSectionAddressSize(&SD); 1053 } 1054 1055 void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm, 1056 const MCAsmLayout &Layout, 1057 const MCSectionELF &Section) { 1058 uint64_t FileOff = OS.tell(); 1059 const MCSectionData &SD = Asm.getOrCreateSectionData(Section); 1060 1061 uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment()); 1062 WriteZeros(Padding); 1063 FileOff += Padding; 1064 1065 FileOff += GetSectionFileSize(Layout, SD); 1066 1067 if (IsELFMetaDataSection(SD)) { 1068 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e; 1069 ++i) { 1070 const MCFragment &F = *i; 1071 assert(F.getKind() == MCFragment::FT_Data); 1072 WriteBytes(cast<MCDataFragment>(F).getContents().str()); 1073 } 1074 } else { 1075 Asm.writeSectionData(&SD, Layout); 1076 } 1077 } 1078 1079 void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm, 1080 const GroupMapTy &GroupMap, 1081 const MCAsmLayout &Layout, 1082 const SectionIndexMapTy &SectionIndexMap, 1083 const SectionOffsetMapTy &SectionOffsetMap) { 1084 const unsigned NumSections = Asm.size() + 1; 1085 1086 std::vector<const MCSectionELF*> Sections; 1087 Sections.resize(NumSections - 1); 1088 1089 for (SectionIndexMapTy::const_iterator i= 1090 SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) { 1091 const std::pair<const MCSectionELF*, uint32_t> &p = *i; 1092 Sections[p.second - 1] = p.first; 1093 } 1094 1095 // Null section first. 1096 uint64_t FirstSectionSize = 1097 NumSections >= ELF::SHN_LORESERVE ? NumSections : 0; 1098 uint32_t FirstSectionLink = 1099 ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0; 1100 WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0); 1101 1102 for (unsigned i = 0; i < NumSections - 1; ++i) { 1103 const MCSectionELF &Section = *Sections[i]; 1104 const MCSectionData &SD = Asm.getOrCreateSectionData(Section); 1105 uint32_t GroupSymbolIndex; 1106 if (Section.getType() != ELF::SHT_GROUP) 1107 GroupSymbolIndex = 0; 1108 else 1109 GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, 1110 GroupMap.lookup(&Section)); 1111 1112 uint64_t Size = GetSectionAddressSize(Layout, SD); 1113 1114 WriteSection(Asm, SectionIndexMap, GroupSymbolIndex, 1115 SectionOffsetMap.lookup(&Section), Size, 1116 SD.getAlignment(), Section); 1117 } 1118 } 1119 1120 void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm, 1121 std::vector<const MCSectionELF*> &Sections) { 1122 for (MCAssembler::iterator it = Asm.begin(), 1123 ie = Asm.end(); it != ie; ++it) { 1124 const MCSectionELF &Section = 1125 static_cast<const MCSectionELF &>(it->getSection()); 1126 if (Section.getType() == ELF::SHT_GROUP) 1127 Sections.push_back(&Section); 1128 } 1129 1130 for (MCAssembler::iterator it = Asm.begin(), 1131 ie = Asm.end(); it != ie; ++it) { 1132 const MCSectionELF &Section = 1133 static_cast<const MCSectionELF &>(it->getSection()); 1134 if (Section.getType() != ELF::SHT_GROUP && 1135 Section.getType() != ELF::SHT_REL && 1136 Section.getType() != ELF::SHT_RELA) 1137 Sections.push_back(&Section); 1138 } 1139 1140 for (MCAssembler::iterator it = Asm.begin(), 1141 ie = Asm.end(); it != ie; ++it) { 1142 const MCSectionELF &Section = 1143 static_cast<const MCSectionELF &>(it->getSection()); 1144 if (Section.getType() == ELF::SHT_REL || 1145 Section.getType() == ELF::SHT_RELA) 1146 Sections.push_back(&Section); 1147 } 1148 } 1149 1150 void ELFObjectWriter::WriteObject(MCAssembler &Asm, 1151 const MCAsmLayout &Layout) { 1152 GroupMapTy GroupMap; 1153 RevGroupMapTy RevGroupMap; 1154 SectionIndexMapTy SectionIndexMap; 1155 1156 unsigned NumUserSections = Asm.size(); 1157 1158 DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap; 1159 CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap); 1160 1161 const unsigned NumUserAndRelocSections = Asm.size(); 1162 CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap, 1163 RevGroupMap, SectionIndexMap, RelMap); 1164 const unsigned AllSections = Asm.size(); 1165 const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections; 1166 1167 unsigned NumRegularSections = NumUserSections + NumIndexedSections; 1168 1169 // Compute symbol table information. 1170 ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections); 1171 1172 1173 WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap); 1174 1175 CreateMetadataSections(const_cast<MCAssembler&>(Asm), 1176 const_cast<MCAsmLayout&>(Layout), 1177 SectionIndexMap, 1178 RelMap); 1179 1180 uint64_t NaturalAlignment = is64Bit() ? 8 : 4; 1181 uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) : 1182 sizeof(ELF::Elf32_Ehdr); 1183 uint64_t FileOff = HeaderSize; 1184 1185 std::vector<const MCSectionELF*> Sections; 1186 ComputeSectionOrder(Asm, Sections); 1187 unsigned NumSections = Sections.size(); 1188 SectionOffsetMapTy SectionOffsetMap; 1189 for (unsigned i = 0; i < NumRegularSections + 1; ++i) { 1190 const MCSectionELF &Section = *Sections[i]; 1191 const MCSectionData &SD = Asm.getOrCreateSectionData(Section); 1192 1193 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); 1194 1195 // Remember the offset into the file for this section. 1196 SectionOffsetMap[&Section] = FileOff; 1197 1198 // Get the size of the section in the output file (including padding). 1199 FileOff += GetSectionFileSize(Layout, SD); 1200 } 1201 1202 FileOff = RoundUpToAlignment(FileOff, NaturalAlignment); 1203 1204 const unsigned SectionHeaderOffset = FileOff - HeaderSize; 1205 1206 uint64_t SectionHeaderEntrySize = is64Bit() ? 1207 sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr); 1208 FileOff += (NumSections + 1) * SectionHeaderEntrySize; 1209 1210 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) { 1211 const MCSectionELF &Section = *Sections[i]; 1212 const MCSectionData &SD = Asm.getOrCreateSectionData(Section); 1213 1214 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); 1215 1216 // Remember the offset into the file for this section. 1217 SectionOffsetMap[&Section] = FileOff; 1218 1219 // Get the size of the section in the output file (including padding). 1220 FileOff += GetSectionFileSize(Layout, SD); 1221 } 1222 1223 // Write out the ELF header ... 1224 WriteHeader(SectionHeaderOffset, NumSections + 1); 1225 1226 // ... then the regular sections ... 1227 // + because of .shstrtab 1228 for (unsigned i = 0; i < NumRegularSections + 1; ++i) 1229 WriteDataSectionData(Asm, Layout, *Sections[i]); 1230 1231 FileOff = OS.tell(); 1232 uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment); 1233 WriteZeros(Padding); 1234 1235 // ... then the section header table ... 1236 WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, 1237 SectionOffsetMap); 1238 1239 FileOff = OS.tell(); 1240 1241 // ... and then the remaining sections ... 1242 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) 1243 WriteDataSectionData(Asm, Layout, *Sections[i]); 1244 } 1245 1246 bool 1247 ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, 1248 const MCSymbolData &DataA, 1249 const MCFragment &FB, 1250 bool InSet, 1251 bool IsPCRel) const { 1252 if (DataA.getFlags() & ELF_STB_Weak) 1253 return false; 1254 return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl( 1255 Asm, DataA, FB,InSet, IsPCRel); 1256 } 1257 1258 MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW, 1259 raw_ostream &OS, 1260 bool IsLittleEndian) { 1261 switch (MOTW->getEMachine()) { 1262 case ELF::EM_386: 1263 case ELF::EM_X86_64: 1264 return new X86ELFObjectWriter(MOTW, OS, IsLittleEndian); break; 1265 case ELF::EM_ARM: 1266 return new ARMELFObjectWriter(MOTW, OS, IsLittleEndian); break; 1267 case ELF::EM_MBLAZE: 1268 return new MBlazeELFObjectWriter(MOTW, OS, IsLittleEndian); break; 1269 case ELF::EM_PPC: 1270 case ELF::EM_PPC64: 1271 return new PPCELFObjectWriter(MOTW, OS, IsLittleEndian); break; 1272 case ELF::EM_MIPS: 1273 return new MipsELFObjectWriter(MOTW, OS, IsLittleEndian); break; 1274 default: llvm_unreachable("Unsupported architecture"); break; 1275 } 1276 } 1277 1278 /// START OF SUBCLASSES for ELFObjectWriter 1279 //===- ARMELFObjectWriter -------------------------------------------===// 1280 1281 ARMELFObjectWriter::ARMELFObjectWriter(MCELFObjectTargetWriter *MOTW, 1282 raw_ostream &_OS, 1283 bool IsLittleEndian) 1284 : ELFObjectWriter(MOTW, _OS, IsLittleEndian) 1285 {} 1286 1287 ARMELFObjectWriter::~ARMELFObjectWriter() 1288 {} 1289 1290 // FIXME: get the real EABI Version from the Triple. 1291 void ARMELFObjectWriter::WriteEFlags() { 1292 Write32(ELF::EF_ARM_EABIMASK & DefaultEABIVersion); 1293 } 1294 1295 // In ARM, _MergedGlobals and other most symbols get emitted directly. 1296 // I.e. not as an offset to a section symbol. 1297 // This code is an approximation of what ARM/gcc does. 1298 1299 STATISTIC(PCRelCount, "Total number of PIC Relocations"); 1300 STATISTIC(NonPCRelCount, "Total number of non-PIC relocations"); 1301 1302 const MCSymbol *ARMELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm, 1303 const MCValue &Target, 1304 const MCFragment &F, 1305 const MCFixup &Fixup, 1306 bool IsPCRel) const { 1307 const MCSymbol &Symbol = Target.getSymA()->getSymbol(); 1308 bool EmitThisSym = false; 1309 1310 const MCSectionELF &Section = 1311 static_cast<const MCSectionELF&>(Symbol.getSection()); 1312 bool InNormalSection = true; 1313 unsigned RelocType = 0; 1314 RelocType = GetRelocTypeInner(Target, Fixup, IsPCRel); 1315 1316 DEBUG( 1317 const MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind(); 1318 MCSymbolRefExpr::VariantKind Kind2; 1319 Kind2 = Target.getSymB() ? Target.getSymB()->getKind() : 1320 MCSymbolRefExpr::VK_None; 1321 dbgs() << "considering symbol " 1322 << Section.getSectionName() << "/" 1323 << Symbol.getName() << "/" 1324 << " Rel:" << (unsigned)RelocType 1325 << " Kind: " << (int)Kind << "/" << (int)Kind2 1326 << " Tmp:" 1327 << Symbol.isAbsolute() << "/" << Symbol.isDefined() << "/" 1328 << Symbol.isVariable() << "/" << Symbol.isTemporary() 1329 << " Counts:" << PCRelCount << "/" << NonPCRelCount << "\n"); 1330 1331 if (IsPCRel) { ++PCRelCount; 1332 switch (RelocType) { 1333 default: 1334 // Most relocation types are emitted as explicit symbols 1335 InNormalSection = 1336 StringSwitch<bool>(Section.getSectionName()) 1337 .Case(".data.rel.ro.local", false) 1338 .Case(".data.rel", false) 1339 .Case(".bss", false) 1340 .Default(true); 1341 EmitThisSym = true; 1342 break; 1343 case ELF::R_ARM_ABS32: 1344 // But things get strange with R_ARM_ABS32 1345 // In this case, most things that go in .rodata show up 1346 // as section relative relocations 1347 InNormalSection = 1348 StringSwitch<bool>(Section.getSectionName()) 1349 .Case(".data.rel.ro.local", false) 1350 .Case(".data.rel", false) 1351 .Case(".rodata", false) 1352 .Case(".bss", false) 1353 .Default(true); 1354 EmitThisSym = false; 1355 break; 1356 } 1357 } else { 1358 NonPCRelCount++; 1359 InNormalSection = 1360 StringSwitch<bool>(Section.getSectionName()) 1361 .Case(".data.rel.ro.local", false) 1362 .Case(".rodata", false) 1363 .Case(".data.rel", false) 1364 .Case(".bss", false) 1365 .Default(true); 1366 1367 switch (RelocType) { 1368 default: EmitThisSym = true; break; 1369 case ELF::R_ARM_ABS32: EmitThisSym = false; break; 1370 } 1371 } 1372 1373 if (EmitThisSym) 1374 return &Symbol; 1375 if (! Symbol.isTemporary() && InNormalSection) { 1376 return &Symbol; 1377 } 1378 return NULL; 1379 } 1380 1381 // Need to examine the Fixup when determining whether to 1382 // emit the relocation as an explicit symbol or as a section relative 1383 // offset 1384 unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target, 1385 const MCFixup &Fixup, 1386 bool IsPCRel, 1387 bool IsRelocWithSymbol, 1388 int64_t Addend) { 1389 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? 1390 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); 1391 1392 unsigned Type = GetRelocTypeInner(Target, Fixup, IsPCRel); 1393 1394 if (RelocNeedsGOT(Modifier)) 1395 NeedsGOT = true; 1396 1397 return Type; 1398 } 1399 1400 unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target, 1401 const MCFixup &Fixup, 1402 bool IsPCRel) const { 1403 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? 1404 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); 1405 1406 unsigned Type = 0; 1407 if (IsPCRel) { 1408 switch ((unsigned)Fixup.getKind()) { 1409 default: assert(0 && "Unimplemented"); 1410 case FK_Data_4: 1411 switch (Modifier) { 1412 default: llvm_unreachable("Unsupported Modifier"); 1413 case MCSymbolRefExpr::VK_None: 1414 Type = ELF::R_ARM_REL32; 1415 break; 1416 case MCSymbolRefExpr::VK_ARM_TLSGD: 1417 assert(0 && "unimplemented"); 1418 break; 1419 case MCSymbolRefExpr::VK_ARM_GOTTPOFF: 1420 Type = ELF::R_ARM_TLS_IE32; 1421 break; 1422 } 1423 break; 1424 case ARM::fixup_arm_uncondbranch: 1425 switch (Modifier) { 1426 case MCSymbolRefExpr::VK_ARM_PLT: 1427 Type = ELF::R_ARM_PLT32; 1428 break; 1429 default: 1430 Type = ELF::R_ARM_CALL; 1431 break; 1432 } 1433 break; 1434 case ARM::fixup_arm_condbranch: 1435 Type = ELF::R_ARM_JUMP24; 1436 break; 1437 case ARM::fixup_arm_movt_hi16: 1438 case ARM::fixup_arm_movt_hi16_pcrel: 1439 Type = ELF::R_ARM_MOVT_PREL; 1440 break; 1441 case ARM::fixup_arm_movw_lo16: 1442 case ARM::fixup_arm_movw_lo16_pcrel: 1443 Type = ELF::R_ARM_MOVW_PREL_NC; 1444 break; 1445 case ARM::fixup_t2_movt_hi16: 1446 case ARM::fixup_t2_movt_hi16_pcrel: 1447 Type = ELF::R_ARM_THM_MOVT_PREL; 1448 break; 1449 case ARM::fixup_t2_movw_lo16: 1450 case ARM::fixup_t2_movw_lo16_pcrel: 1451 Type = ELF::R_ARM_THM_MOVW_PREL_NC; 1452 break; 1453 case ARM::fixup_arm_thumb_bl: 1454 case ARM::fixup_arm_thumb_blx: 1455 switch (Modifier) { 1456 case MCSymbolRefExpr::VK_ARM_PLT: 1457 Type = ELF::R_ARM_THM_CALL; 1458 break; 1459 default: 1460 Type = ELF::R_ARM_NONE; 1461 break; 1462 } 1463 break; 1464 } 1465 } else { 1466 switch ((unsigned)Fixup.getKind()) { 1467 default: llvm_unreachable("invalid fixup kind!"); 1468 case FK_Data_4: 1469 switch (Modifier) { 1470 default: llvm_unreachable("Unsupported Modifier"); break; 1471 case MCSymbolRefExpr::VK_ARM_GOT: 1472 Type = ELF::R_ARM_GOT_BREL; 1473 break; 1474 case MCSymbolRefExpr::VK_ARM_TLSGD: 1475 Type = ELF::R_ARM_TLS_GD32; 1476 break; 1477 case MCSymbolRefExpr::VK_ARM_TPOFF: 1478 Type = ELF::R_ARM_TLS_LE32; 1479 break; 1480 case MCSymbolRefExpr::VK_ARM_GOTTPOFF: 1481 Type = ELF::R_ARM_TLS_IE32; 1482 break; 1483 case MCSymbolRefExpr::VK_None: 1484 Type = ELF::R_ARM_ABS32; 1485 break; 1486 case MCSymbolRefExpr::VK_ARM_GOTOFF: 1487 Type = ELF::R_ARM_GOTOFF32; 1488 break; 1489 } 1490 break; 1491 case ARM::fixup_arm_ldst_pcrel_12: 1492 case ARM::fixup_arm_pcrel_10: 1493 case ARM::fixup_arm_adr_pcrel_12: 1494 case ARM::fixup_arm_thumb_bl: 1495 case ARM::fixup_arm_thumb_cb: 1496 case ARM::fixup_arm_thumb_cp: 1497 case ARM::fixup_arm_thumb_br: 1498 assert(0 && "Unimplemented"); 1499 break; 1500 case ARM::fixup_arm_uncondbranch: 1501 Type = ELF::R_ARM_CALL; 1502 break; 1503 case ARM::fixup_arm_condbranch: 1504 Type = ELF::R_ARM_JUMP24; 1505 break; 1506 case ARM::fixup_arm_movt_hi16: 1507 Type = ELF::R_ARM_MOVT_ABS; 1508 break; 1509 case ARM::fixup_arm_movw_lo16: 1510 Type = ELF::R_ARM_MOVW_ABS_NC; 1511 break; 1512 case ARM::fixup_t2_movt_hi16: 1513 Type = ELF::R_ARM_THM_MOVT_ABS; 1514 break; 1515 case ARM::fixup_t2_movw_lo16: 1516 Type = ELF::R_ARM_THM_MOVW_ABS_NC; 1517 break; 1518 } 1519 } 1520 1521 return Type; 1522 } 1523 1524 //===- PPCELFObjectWriter -------------------------------------------===// 1525 1526 PPCELFObjectWriter::PPCELFObjectWriter(MCELFObjectTargetWriter *MOTW, 1527 raw_ostream &_OS, 1528 bool IsLittleEndian) 1529 : ELFObjectWriter(MOTW, _OS, IsLittleEndian) { 1530 } 1531 1532 PPCELFObjectWriter::~PPCELFObjectWriter() { 1533 } 1534 1535 unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target, 1536 const MCFixup &Fixup, 1537 bool IsPCRel, 1538 bool IsRelocWithSymbol, 1539 int64_t Addend) { 1540 // determine the type of the relocation 1541 unsigned Type; 1542 if (IsPCRel) { 1543 switch ((unsigned)Fixup.getKind()) { 1544 default: 1545 llvm_unreachable("Unimplemented"); 1546 case PPC::fixup_ppc_br24: 1547 Type = ELF::R_PPC_REL24; 1548 break; 1549 case FK_PCRel_4: 1550 Type = ELF::R_PPC_REL32; 1551 break; 1552 } 1553 } else { 1554 switch ((unsigned)Fixup.getKind()) { 1555 default: llvm_unreachable("invalid fixup kind!"); 1556 case PPC::fixup_ppc_br24: 1557 Type = ELF::R_PPC_ADDR24; 1558 break; 1559 case PPC::fixup_ppc_brcond14: 1560 Type = ELF::R_PPC_ADDR14_BRTAKEN; // XXX: or BRNTAKEN?_ 1561 break; 1562 case PPC::fixup_ppc_ha16: 1563 Type = ELF::R_PPC_ADDR16_HA; 1564 break; 1565 case PPC::fixup_ppc_lo16: 1566 Type = ELF::R_PPC_ADDR16_LO; 1567 break; 1568 case PPC::fixup_ppc_lo14: 1569 Type = ELF::R_PPC_ADDR14; 1570 break; 1571 case FK_Data_4: 1572 Type = ELF::R_PPC_ADDR32; 1573 break; 1574 case FK_Data_2: 1575 Type = ELF::R_PPC_ADDR16; 1576 break; 1577 } 1578 } 1579 return Type; 1580 } 1581 1582 void PPCELFObjectWriter:: 1583 adjustFixupOffset(const MCFixup &Fixup, uint64_t &RelocOffset) { 1584 switch ((unsigned)Fixup.getKind()) { 1585 case PPC::fixup_ppc_ha16: 1586 case PPC::fixup_ppc_lo16: 1587 RelocOffset += 2; 1588 break; 1589 default: 1590 break; 1591 } 1592 } 1593 1594 //===- MBlazeELFObjectWriter -------------------------------------------===// 1595 1596 MBlazeELFObjectWriter::MBlazeELFObjectWriter(MCELFObjectTargetWriter *MOTW, 1597 raw_ostream &_OS, 1598 bool IsLittleEndian) 1599 : ELFObjectWriter(MOTW, _OS, IsLittleEndian) { 1600 } 1601 1602 MBlazeELFObjectWriter::~MBlazeELFObjectWriter() { 1603 } 1604 1605 unsigned MBlazeELFObjectWriter::GetRelocType(const MCValue &Target, 1606 const MCFixup &Fixup, 1607 bool IsPCRel, 1608 bool IsRelocWithSymbol, 1609 int64_t Addend) { 1610 // determine the type of the relocation 1611 unsigned Type; 1612 if (IsPCRel) { 1613 switch ((unsigned)Fixup.getKind()) { 1614 default: 1615 llvm_unreachable("Unimplemented"); 1616 case FK_PCRel_4: 1617 Type = ELF::R_MICROBLAZE_64_PCREL; 1618 break; 1619 case FK_PCRel_2: 1620 Type = ELF::R_MICROBLAZE_32_PCREL; 1621 break; 1622 } 1623 } else { 1624 switch ((unsigned)Fixup.getKind()) { 1625 default: llvm_unreachable("invalid fixup kind!"); 1626 case FK_Data_4: 1627 Type = ((IsRelocWithSymbol || Addend !=0) 1628 ? ELF::R_MICROBLAZE_32 1629 : ELF::R_MICROBLAZE_64); 1630 break; 1631 case FK_Data_2: 1632 Type = ELF::R_MICROBLAZE_32; 1633 break; 1634 } 1635 } 1636 return Type; 1637 } 1638 1639 //===- X86ELFObjectWriter -------------------------------------------===// 1640 1641 1642 X86ELFObjectWriter::X86ELFObjectWriter(MCELFObjectTargetWriter *MOTW, 1643 raw_ostream &_OS, 1644 bool IsLittleEndian) 1645 : ELFObjectWriter(MOTW, _OS, IsLittleEndian) 1646 {} 1647 1648 X86ELFObjectWriter::~X86ELFObjectWriter() 1649 {} 1650 1651 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target, 1652 const MCFixup &Fixup, 1653 bool IsPCRel, 1654 bool IsRelocWithSymbol, 1655 int64_t Addend) { 1656 // determine the type of the relocation 1657 1658 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ? 1659 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind(); 1660 unsigned Type; 1661 if (is64Bit()) { 1662 if (IsPCRel) { 1663 switch ((unsigned)Fixup.getKind()) { 1664 default: llvm_unreachable("invalid fixup kind!"); 1665 1666 case FK_Data_8: Type = ELF::R_X86_64_PC64; break; 1667 case FK_Data_4: Type = ELF::R_X86_64_PC32; break; 1668 case FK_Data_2: Type = ELF::R_X86_64_PC16; break; 1669 1670 case FK_PCRel_8: 1671 assert(Modifier == MCSymbolRefExpr::VK_None); 1672 Type = ELF::R_X86_64_PC64; 1673 break; 1674 case X86::reloc_signed_4byte: 1675 case X86::reloc_riprel_4byte_movq_load: 1676 case X86::reloc_riprel_4byte: 1677 case FK_PCRel_4: 1678 switch (Modifier) { 1679 default: 1680 llvm_unreachable("Unimplemented"); 1681 case MCSymbolRefExpr::VK_None: 1682 Type = ELF::R_X86_64_PC32; 1683 break; 1684 case MCSymbolRefExpr::VK_PLT: 1685 Type = ELF::R_X86_64_PLT32; 1686 break; 1687 case MCSymbolRefExpr::VK_GOTPCREL: 1688 Type = ELF::R_X86_64_GOTPCREL; 1689 break; 1690 case MCSymbolRefExpr::VK_GOTTPOFF: 1691 Type = ELF::R_X86_64_GOTTPOFF; 1692 break; 1693 case MCSymbolRefExpr::VK_TLSGD: 1694 Type = ELF::R_X86_64_TLSGD; 1695 break; 1696 case MCSymbolRefExpr::VK_TLSLD: 1697 Type = ELF::R_X86_64_TLSLD; 1698 break; 1699 } 1700 break; 1701 case FK_PCRel_2: 1702 assert(Modifier == MCSymbolRefExpr::VK_None); 1703 Type = ELF::R_X86_64_PC16; 1704 break; 1705 case FK_PCRel_1: 1706 assert(Modifier == MCSymbolRefExpr::VK_None); 1707 Type = ELF::R_X86_64_PC8; 1708 break; 1709 } 1710 } else { 1711 switch ((unsigned)Fixup.getKind()) { 1712 default: llvm_unreachable("invalid fixup kind!"); 1713 case FK_Data_8: Type = ELF::R_X86_64_64; break; 1714 case X86::reloc_signed_4byte: 1715 switch (Modifier) { 1716 default: 1717 llvm_unreachable("Unimplemented"); 1718 case MCSymbolRefExpr::VK_None: 1719 Type = ELF::R_X86_64_32S; 1720 break; 1721 case MCSymbolRefExpr::VK_GOT: 1722 Type = ELF::R_X86_64_GOT32; 1723 break; 1724 case MCSymbolRefExpr::VK_GOTPCREL: 1725 Type = ELF::R_X86_64_GOTPCREL; 1726 break; 1727 case MCSymbolRefExpr::VK_TPOFF: 1728 Type = ELF::R_X86_64_TPOFF32; 1729 break; 1730 case MCSymbolRefExpr::VK_DTPOFF: 1731 Type = ELF::R_X86_64_DTPOFF32; 1732 break; 1733 } 1734 break; 1735 case FK_Data_4: 1736 Type = ELF::R_X86_64_32; 1737 break; 1738 case FK_Data_2: Type = ELF::R_X86_64_16; break; 1739 case FK_PCRel_1: 1740 case FK_Data_1: Type = ELF::R_X86_64_8; break; 1741 } 1742 } 1743 } else { 1744 if (IsPCRel) { 1745 switch ((unsigned)Fixup.getKind()) { 1746 default: llvm_unreachable("invalid fixup kind!"); 1747 1748 case X86::reloc_global_offset_table: 1749 Type = ELF::R_386_GOTPC; 1750 break; 1751 1752 case X86::reloc_signed_4byte: 1753 case FK_PCRel_4: 1754 case FK_Data_4: 1755 switch (Modifier) { 1756 default: 1757 llvm_unreachable("Unimplemented"); 1758 case MCSymbolRefExpr::VK_None: 1759 Type = ELF::R_386_PC32; 1760 break; 1761 case MCSymbolRefExpr::VK_PLT: 1762 Type = ELF::R_386_PLT32; 1763 break; 1764 } 1765 break; 1766 } 1767 } else { 1768 switch ((unsigned)Fixup.getKind()) { 1769 default: llvm_unreachable("invalid fixup kind!"); 1770 1771 case X86::reloc_global_offset_table: 1772 Type = ELF::R_386_GOTPC; 1773 break; 1774 1775 // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode 1776 // instead? 1777 case X86::reloc_signed_4byte: 1778 case FK_PCRel_4: 1779 case FK_Data_4: 1780 switch (Modifier) { 1781 default: 1782 llvm_unreachable("Unimplemented"); 1783 case MCSymbolRefExpr::VK_None: 1784 Type = ELF::R_386_32; 1785 break; 1786 case MCSymbolRefExpr::VK_GOT: 1787 Type = ELF::R_386_GOT32; 1788 break; 1789 case MCSymbolRefExpr::VK_GOTOFF: 1790 Type = ELF::R_386_GOTOFF; 1791 break; 1792 case MCSymbolRefExpr::VK_TLSGD: 1793 Type = ELF::R_386_TLS_GD; 1794 break; 1795 case MCSymbolRefExpr::VK_TPOFF: 1796 Type = ELF::R_386_TLS_LE_32; 1797 break; 1798 case MCSymbolRefExpr::VK_INDNTPOFF: 1799 Type = ELF::R_386_TLS_IE; 1800 break; 1801 case MCSymbolRefExpr::VK_NTPOFF: 1802 Type = ELF::R_386_TLS_LE; 1803 break; 1804 case MCSymbolRefExpr::VK_GOTNTPOFF: 1805 Type = ELF::R_386_TLS_GOTIE; 1806 break; 1807 case MCSymbolRefExpr::VK_TLSLDM: 1808 Type = ELF::R_386_TLS_LDM; 1809 break; 1810 case MCSymbolRefExpr::VK_DTPOFF: 1811 Type = ELF::R_386_TLS_LDO_32; 1812 break; 1813 case MCSymbolRefExpr::VK_GOTTPOFF: 1814 Type = ELF::R_386_TLS_IE_32; 1815 break; 1816 } 1817 break; 1818 case FK_Data_2: Type = ELF::R_386_16; break; 1819 case FK_PCRel_1: 1820 case FK_Data_1: Type = ELF::R_386_8; break; 1821 } 1822 } 1823 } 1824 1825 if (RelocNeedsGOT(Modifier)) 1826 NeedsGOT = true; 1827 1828 return Type; 1829 } 1830 1831 //===- MipsELFObjectWriter -------------------------------------------===// 1832 1833 MipsELFObjectWriter::MipsELFObjectWriter(MCELFObjectTargetWriter *MOTW, 1834 raw_ostream &_OS, 1835 bool IsLittleEndian) 1836 : ELFObjectWriter(MOTW, _OS, IsLittleEndian) {} 1837 1838 MipsELFObjectWriter::~MipsELFObjectWriter() {} 1839 1840 // FIXME: get the real EABI Version from the Triple. 1841 void MipsELFObjectWriter::WriteEFlags() { 1842 Write32(ELF::EF_MIPS_NOREORDER | 1843 ELF::EF_MIPS_ARCH_32R2); 1844 } 1845 1846 const MCSymbol *MipsELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm, 1847 const MCValue &Target, 1848 const MCFragment &F, 1849 const MCFixup &Fixup, 1850 bool IsPCRel) const { 1851 assert(Target.getSymA() && "SymA cannot be 0."); 1852 const MCSymbol &Sym = Target.getSymA()->getSymbol(); 1853 1854 if (Sym.getSection().getKind().isMergeableCString() || 1855 Sym.getSection().getKind().isMergeableConst()) 1856 return &Sym; 1857 1858 return NULL; 1859 } 1860 1861 unsigned MipsELFObjectWriter::GetRelocType(const MCValue &Target, 1862 const MCFixup &Fixup, 1863 bool IsPCRel, 1864 bool IsRelocWithSymbol, 1865 int64_t Addend) { 1866 // determine the type of the relocation 1867 unsigned Type = (unsigned)ELF::R_MIPS_NONE; 1868 unsigned Kind = (unsigned)Fixup.getKind(); 1869 1870 switch (Kind) { 1871 default: 1872 llvm_unreachable("invalid fixup kind!"); 1873 case FK_Data_4: 1874 Type = ELF::R_MIPS_32; 1875 break; 1876 case FK_GPRel_4: 1877 Type = ELF::R_MIPS_GPREL32; 1878 break; 1879 case Mips::fixup_Mips_GPREL16: 1880 Type = ELF::R_MIPS_GPREL16; 1881 break; 1882 case Mips::fixup_Mips_26: 1883 Type = ELF::R_MIPS_26; 1884 break; 1885 case Mips::fixup_Mips_CALL16: 1886 Type = ELF::R_MIPS_CALL16; 1887 break; 1888 case Mips::fixup_Mips_GOT_Global: 1889 case Mips::fixup_Mips_GOT_Local: 1890 Type = ELF::R_MIPS_GOT16; 1891 break; 1892 case Mips::fixup_Mips_HI16: 1893 Type = ELF::R_MIPS_HI16; 1894 break; 1895 case Mips::fixup_Mips_LO16: 1896 Type = ELF::R_MIPS_LO16; 1897 break; 1898 case Mips::fixup_Mips_TLSGD: 1899 Type = ELF::R_MIPS_TLS_GD; 1900 break; 1901 case Mips::fixup_Mips_GOTTPREL: 1902 Type = ELF::R_MIPS_TLS_GOTTPREL; 1903 break; 1904 case Mips::fixup_Mips_TPREL_HI: 1905 Type = ELF::R_MIPS_TLS_TPREL_HI16; 1906 break; 1907 case Mips::fixup_Mips_TPREL_LO: 1908 Type = ELF::R_MIPS_TLS_TPREL_LO16; 1909 break; 1910 case Mips::fixup_Mips_Branch_PCRel: 1911 case Mips::fixup_Mips_PC16: 1912 Type = ELF::R_MIPS_PC16; 1913 break; 1914 } 1915 1916 return Type; 1917 } 1918