1 //===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements ELF object file writer information.
12 //===----------------------------------------------------------------------===//
15 #include "llvm/ADT/OwningPtr.h"
16 #include "llvm/ADT/SmallPtrSet.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/Twine.h"
21 #include "llvm/MC/MCAsmBackend.h"
22 #include "llvm/MC/MCAsmLayout.h"
23 #include "llvm/MC/MCAssembler.h"
24 #include "llvm/MC/MCContext.h"
25 #include "llvm/MC/MCELFObjectWriter.h"
26 #include "llvm/MC/MCELFSymbolFlags.h"
27 #include "llvm/MC/MCExpr.h"
28 #include "llvm/MC/MCSectionELF.h"
29 #include "llvm/MC/MCValue.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/ELF.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/ADT/StringSwitch.h"
40 #define DEBUG_TYPE "reloc-info"
43 class ELFObjectWriter : public MCObjectWriter {
46 static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
47 static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant);
48 static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout);
49 static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
50 bool Used, bool Renamed);
51 static bool isLocal(const MCSymbolData &Data, bool isSignature,
53 static bool IsELFMetaDataSection(const MCSectionData &SD);
54 static uint64_t DataSectionSize(const MCSectionData &SD);
55 static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
56 const MCSectionData &SD);
57 static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
58 const MCSectionData &SD);
60 void WriteDataSectionData(MCAssembler &Asm,
61 const MCAsmLayout &Layout,
62 const MCSectionELF &Section);
64 /*static bool isFixupKindX86RIPRel(unsigned Kind) {
65 return Kind == X86::reloc_riprel_4byte ||
66 Kind == X86::reloc_riprel_4byte_movq_load;
69 /// ELFSymbolData - Helper struct for containing some precomputed
70 /// information on symbols.
71 struct ELFSymbolData {
72 MCSymbolData *SymbolData;
74 uint32_t SectionIndex;
76 // Support lexicographic sorting.
77 bool operator<(const ELFSymbolData &RHS) const {
78 if (MCELF::GetType(*SymbolData) == ELF::STT_FILE)
80 if (MCELF::GetType(*RHS.SymbolData) == ELF::STT_FILE)
82 return SymbolData->getSymbol().getName() <
83 RHS.SymbolData->getSymbol().getName();
87 /// The target specific ELF writer instance.
88 llvm::OwningPtr<MCELFObjectTargetWriter> TargetObjectWriter;
90 SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
91 SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
92 DenseMap<const MCSymbol *, const MCSymbol *> Renames;
94 llvm::DenseMap<const MCSectionData*,
95 std::vector<ELFRelocationEntry> > Relocations;
96 DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
99 /// @name Symbol Table Data
102 SmallString<256> StringTable;
103 std::vector<ELFSymbolData> LocalSymbolData;
104 std::vector<ELFSymbolData> ExternalSymbolData;
105 std::vector<ELFSymbolData> UndefinedSymbolData;
111 bool NeedsSymtabShndx;
113 // This holds the symbol table index of the last local symbol.
114 unsigned LastLocalSymbolIndex;
115 // This holds the .strtab section index.
116 unsigned StringTableIndex;
117 // This holds the .symtab section index.
118 unsigned SymbolTableIndex;
120 unsigned ShstrtabIndex;
123 const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
124 const MCValue &Target,
126 const MCFixup &Fixup,
129 // TargetObjectWriter wrappers.
130 const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
131 const MCValue &Target,
133 const MCFixup &Fixup,
134 bool IsPCRel) const {
135 return TargetObjectWriter->ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
138 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
139 bool hasRelocationAddend() const {
140 return TargetObjectWriter->hasRelocationAddend();
142 unsigned getEFlags() const {
143 return TargetObjectWriter->getEFlags();
145 unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
146 bool IsPCRel, bool IsRelocWithSymbol,
147 int64_t Addend) const {
148 return TargetObjectWriter->GetRelocType(Target, Fixup, IsPCRel,
149 IsRelocWithSymbol, Addend);
154 ELFObjectWriter(MCELFObjectTargetWriter *MOTW,
155 raw_ostream &_OS, bool IsLittleEndian)
156 : MCObjectWriter(_OS, IsLittleEndian),
157 TargetObjectWriter(MOTW),
158 NeedsGOT(false), NeedsSymtabShndx(false){
161 virtual ~ELFObjectWriter();
163 void WriteWord(uint64_t W) {
170 void StringLE16(char *buf, uint16_t Value) {
171 buf[0] = char(Value >> 0);
172 buf[1] = char(Value >> 8);
175 void StringLE32(char *buf, uint32_t Value) {
176 StringLE16(buf, uint16_t(Value >> 0));
177 StringLE16(buf + 2, uint16_t(Value >> 16));
180 void StringLE64(char *buf, uint64_t Value) {
181 StringLE32(buf, uint32_t(Value >> 0));
182 StringLE32(buf + 4, uint32_t(Value >> 32));
185 void StringBE16(char *buf ,uint16_t Value) {
186 buf[0] = char(Value >> 8);
187 buf[1] = char(Value >> 0);
190 void StringBE32(char *buf, uint32_t Value) {
191 StringBE16(buf, uint16_t(Value >> 16));
192 StringBE16(buf + 2, uint16_t(Value >> 0));
195 void StringBE64(char *buf, uint64_t Value) {
196 StringBE32(buf, uint32_t(Value >> 32));
197 StringBE32(buf + 4, uint32_t(Value >> 0));
200 void String8(MCDataFragment &F, uint8_t Value) {
203 F.getContents() += StringRef(buf, 1);
206 void String16(MCDataFragment &F, uint16_t Value) {
208 if (isLittleEndian())
209 StringLE16(buf, Value);
211 StringBE16(buf, Value);
212 F.getContents() += StringRef(buf, 2);
215 void String32(MCDataFragment &F, uint32_t Value) {
217 if (isLittleEndian())
218 StringLE32(buf, Value);
220 StringBE32(buf, Value);
221 F.getContents() += StringRef(buf, 4);
224 void String64(MCDataFragment &F, uint64_t Value) {
226 if (isLittleEndian())
227 StringLE64(buf, Value);
229 StringBE64(buf, Value);
230 F.getContents() += StringRef(buf, 8);
233 void WriteHeader(uint64_t SectionDataSize,
234 unsigned NumberOfSections);
236 void WriteSymbolEntry(MCDataFragment *SymtabF,
237 MCDataFragment *ShndxF,
238 uint64_t name, uint8_t info,
239 uint64_t value, uint64_t size,
240 uint8_t other, uint32_t shndx,
243 void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
245 const MCAsmLayout &Layout);
247 typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
248 void WriteSymbolTable(MCDataFragment *SymtabF,
249 MCDataFragment *ShndxF,
250 const MCAssembler &Asm,
251 const MCAsmLayout &Layout,
252 const SectionIndexMapTy &SectionIndexMap);
254 virtual void RecordRelocation(const MCAssembler &Asm,
255 const MCAsmLayout &Layout,
256 const MCFragment *Fragment,
257 const MCFixup &Fixup,
258 MCValue Target, uint64_t &FixedValue);
260 uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
263 // Map from a group section to the signature symbol
264 typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
265 // Map from a signature symbol to the group section
266 typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
267 // Map from a section to the section with the relocations
268 typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy;
269 // Map from a section to its offset
270 typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy;
272 /// ComputeSymbolTable - Compute the symbol table data
274 /// \param StringTable [out] - The string table data.
275 /// \param StringIndexMap [out] - Map from symbol names to offsets in the
277 void ComputeSymbolTable(MCAssembler &Asm,
278 const SectionIndexMapTy &SectionIndexMap,
279 RevGroupMapTy RevGroupMap,
280 unsigned NumRegularSections);
282 void ComputeIndexMap(MCAssembler &Asm,
283 SectionIndexMapTy &SectionIndexMap,
284 const RelMapTy &RelMap);
286 void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
289 void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
290 const RelMapTy &RelMap);
292 void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
293 SectionIndexMapTy &SectionIndexMap,
294 const RelMapTy &RelMap);
296 // Create the sections that show up in the symbol table. Currently
297 // those are the .note.GNU-stack section and the group sections.
298 void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
299 GroupMapTy &GroupMap,
300 RevGroupMapTy &RevGroupMap,
301 SectionIndexMapTy &SectionIndexMap,
302 const RelMapTy &RelMap);
304 virtual void ExecutePostLayoutBinding(MCAssembler &Asm,
305 const MCAsmLayout &Layout);
307 void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
308 const MCAsmLayout &Layout,
309 const SectionIndexMapTy &SectionIndexMap,
310 const SectionOffsetMapTy &SectionOffsetMap);
312 void ComputeSectionOrder(MCAssembler &Asm,
313 std::vector<const MCSectionELF*> &Sections);
315 void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
316 uint64_t Address, uint64_t Offset,
317 uint64_t Size, uint32_t Link, uint32_t Info,
318 uint64_t Alignment, uint64_t EntrySize);
320 void WriteRelocationsFragment(const MCAssembler &Asm,
322 const MCSectionData *SD);
325 IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
326 const MCSymbolData &DataA,
327 const MCFragment &FB,
331 virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
332 void WriteSection(MCAssembler &Asm,
333 const SectionIndexMapTy &SectionIndexMap,
334 uint32_t GroupSymbolIndex,
335 uint64_t Offset, uint64_t Size, uint64_t Alignment,
336 const MCSectionELF &Section);
340 bool ELFObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
341 const MCFixupKindInfo &FKI =
342 Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind);
344 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
347 bool ELFObjectWriter::RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
351 case MCSymbolRefExpr::VK_GOT:
352 case MCSymbolRefExpr::VK_PLT:
353 case MCSymbolRefExpr::VK_GOTPCREL:
354 case MCSymbolRefExpr::VK_GOTOFF:
355 case MCSymbolRefExpr::VK_TPOFF:
356 case MCSymbolRefExpr::VK_TLSGD:
357 case MCSymbolRefExpr::VK_GOTTPOFF:
358 case MCSymbolRefExpr::VK_INDNTPOFF:
359 case MCSymbolRefExpr::VK_NTPOFF:
360 case MCSymbolRefExpr::VK_GOTNTPOFF:
361 case MCSymbolRefExpr::VK_TLSLDM:
362 case MCSymbolRefExpr::VK_DTPOFF:
363 case MCSymbolRefExpr::VK_TLSLD:
368 ELFObjectWriter::~ELFObjectWriter()
371 // Emit the ELF header.
372 void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize,
373 unsigned NumberOfSections) {
379 // emitWord method behaves differently for ELF32 and ELF64, writing
380 // 4 bytes in the former and 8 in the latter.
382 Write8(0x7f); // e_ident[EI_MAG0]
383 Write8('E'); // e_ident[EI_MAG1]
384 Write8('L'); // e_ident[EI_MAG2]
385 Write8('F'); // e_ident[EI_MAG3]
387 Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
390 Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
392 Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
394 Write8(TargetObjectWriter->getOSABI());
395 Write8(0); // e_ident[EI_ABIVERSION]
397 WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
399 Write16(ELF::ET_REL); // e_type
401 Write16(TargetObjectWriter->getEMachine()); // e_machine = target
403 Write32(ELF::EV_CURRENT); // e_version
404 WriteWord(0); // e_entry, no entry point in .o file
405 WriteWord(0); // e_phoff, no program header for .o
406 WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
407 sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes
409 // e_flags = whatever the target wants
410 Write32(getEFlags());
412 // e_ehsize = ELF header size
413 Write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
415 Write16(0); // e_phentsize = prog header entry size
416 Write16(0); // e_phnum = # prog header entries = 0
418 // e_shentsize = Section header entry size
419 Write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
421 // e_shnum = # of section header ents
422 if (NumberOfSections >= ELF::SHN_LORESERVE)
423 Write16(ELF::SHN_UNDEF);
425 Write16(NumberOfSections);
427 // e_shstrndx = Section # of '.shstrtab'
428 if (ShstrtabIndex >= ELF::SHN_LORESERVE)
429 Write16(ELF::SHN_XINDEX);
431 Write16(ShstrtabIndex);
434 void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
435 MCDataFragment *ShndxF,
437 uint8_t info, uint64_t value,
438 uint64_t size, uint8_t other,
442 if (shndx >= ELF::SHN_LORESERVE && !Reserved)
443 String32(*ShndxF, shndx);
445 String32(*ShndxF, 0);
448 uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
449 uint16_t(ELF::SHN_XINDEX) : shndx;
452 String32(*SymtabF, name); // st_name
453 String8(*SymtabF, info); // st_info
454 String8(*SymtabF, other); // st_other
455 String16(*SymtabF, Index); // st_shndx
456 String64(*SymtabF, value); // st_value
457 String64(*SymtabF, size); // st_size
459 String32(*SymtabF, name); // st_name
460 String32(*SymtabF, value); // st_value
461 String32(*SymtabF, size); // st_size
462 String8(*SymtabF, info); // st_info
463 String8(*SymtabF, other); // st_other
464 String16(*SymtabF, Index); // st_shndx
468 uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
469 const MCAsmLayout &Layout) {
470 if (Data.isCommon() && Data.isExternal())
471 return Data.getCommonAlignment();
473 const MCSymbol &Symbol = Data.getSymbol();
475 if (Symbol.isAbsolute() && Symbol.isVariable()) {
476 if (const MCExpr *Value = Symbol.getVariableValue()) {
478 if (Value->EvaluateAsAbsolute(IntValue, Layout))
479 return (uint64_t)IntValue;
483 if (!Symbol.isInSection())
487 if (Data.getFragment()) {
488 if (Data.getFlags() & ELF_Other_ThumbFunc)
489 return Layout.getSymbolOffset(&Data)+1;
491 return Layout.getSymbolOffset(&Data);
497 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
498 const MCAsmLayout &Layout) {
499 // The presence of symbol versions causes undefined symbols and
500 // versions declared with @@@ to be renamed.
502 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
503 ie = Asm.symbol_end(); it != ie; ++it) {
504 const MCSymbol &Alias = it->getSymbol();
505 const MCSymbol &Symbol = Alias.AliasedSymbol();
506 MCSymbolData &SD = Asm.getSymbolData(Symbol);
509 if (&Symbol == &Alias)
512 StringRef AliasName = Alias.getName();
513 size_t Pos = AliasName.find('@');
514 if (Pos == StringRef::npos)
517 // Aliases defined with .symvar copy the binding from the symbol they alias.
518 // This is the first place we are able to copy this information.
519 it->setExternal(SD.isExternal());
520 MCELF::SetBinding(*it, MCELF::GetBinding(SD));
522 StringRef Rest = AliasName.substr(Pos);
523 if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
526 // FIXME: produce a better error message.
527 if (Symbol.isUndefined() && Rest.startswith("@@") &&
528 !Rest.startswith("@@@"))
529 report_fatal_error("A @@ version cannot be undefined");
531 Renames.insert(std::make_pair(&Symbol, &Alias));
535 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
536 MCDataFragment *ShndxF,
538 const MCAsmLayout &Layout) {
539 MCSymbolData &OrigData = *MSD.SymbolData;
541 Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
543 bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
544 Data.getSymbol().isVariable();
546 uint8_t Binding = MCELF::GetBinding(OrigData);
547 uint8_t Visibility = MCELF::GetVisibility(OrigData);
548 uint8_t Type = MCELF::GetType(Data);
550 uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
551 uint8_t Other = Visibility;
553 uint64_t Value = SymbolValue(Data, Layout);
556 assert(!(Data.isCommon() && !Data.isExternal()));
558 const MCExpr *ESize = Data.getSize();
561 if (!ESize->EvaluateAsAbsolute(Res, Layout))
562 report_fatal_error("Size expression must be absolute.");
566 // Write out the symbol table entry
567 WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
568 Size, Other, MSD.SectionIndex, IsReserved);
571 void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
572 MCDataFragment *ShndxF,
573 const MCAssembler &Asm,
574 const MCAsmLayout &Layout,
575 const SectionIndexMapTy &SectionIndexMap) {
576 // The string table must be emitted first because we need the index
577 // into the string table for all the symbol names.
578 assert(StringTable.size() && "Missing string table");
580 // FIXME: Make sure the start of the symbol table is aligned.
582 // The first entry is the undefined symbol entry.
583 WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
585 // Write the symbol table entries.
586 LastLocalSymbolIndex = LocalSymbolData.size() + 1;
587 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
588 ELFSymbolData &MSD = LocalSymbolData[i];
589 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
592 // Write out a symbol table entry for each regular section.
593 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
595 const MCSectionELF &Section =
596 static_cast<const MCSectionELF&>(i->getSection());
597 if (Section.getType() == ELF::SHT_RELA ||
598 Section.getType() == ELF::SHT_REL ||
599 Section.getType() == ELF::SHT_STRTAB ||
600 Section.getType() == ELF::SHT_SYMTAB ||
601 Section.getType() == ELF::SHT_SYMTAB_SHNDX)
603 WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0,
604 ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section),
606 LastLocalSymbolIndex++;
609 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
610 ELFSymbolData &MSD = ExternalSymbolData[i];
611 MCSymbolData &Data = *MSD.SymbolData;
612 assert(((Data.getFlags() & ELF_STB_Global) ||
613 (Data.getFlags() & ELF_STB_Weak)) &&
614 "External symbol requires STB_GLOBAL or STB_WEAK flag");
615 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
616 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
617 LastLocalSymbolIndex++;
620 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
621 ELFSymbolData &MSD = UndefinedSymbolData[i];
622 MCSymbolData &Data = *MSD.SymbolData;
623 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
624 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
625 LastLocalSymbolIndex++;
629 const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
630 const MCValue &Target,
632 const MCFixup &Fixup,
633 bool IsPCRel) const {
634 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
635 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
636 const MCSymbol *Renamed = Renames.lookup(&Symbol);
637 const MCSymbolData &SD = Asm.getSymbolData(Symbol);
639 if (ASymbol.isUndefined()) {
645 if (SD.isExternal()) {
651 const MCSectionELF &Section =
652 static_cast<const MCSectionELF&>(ASymbol.getSection());
653 const SectionKind secKind = Section.getKind();
656 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
658 if (secKind.isThreadLocal()) {
664 MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
665 const MCSectionELF &Sec2 =
666 static_cast<const MCSectionELF&>(F.getParent()->getSection());
668 if (&Sec2 != &Section &&
669 (Kind == MCSymbolRefExpr::VK_PLT ||
670 Kind == MCSymbolRefExpr::VK_GOTPCREL ||
671 Kind == MCSymbolRefExpr::VK_GOTOFF)) {
677 if (Section.getFlags() & ELF::SHF_MERGE) {
678 if (Target.getConstant() == 0)
679 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
685 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
690 void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
691 const MCAsmLayout &Layout,
692 const MCFragment *Fragment,
693 const MCFixup &Fixup,
695 uint64_t &FixedValue) {
698 int64_t Value = Target.getConstant();
699 const MCSymbol *RelocSymbol = NULL;
701 bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
702 if (!Target.isAbsolute()) {
703 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
704 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
705 RelocSymbol = SymbolToReloc(Asm, Target, *Fragment, Fixup, IsPCRel);
707 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
708 const MCSymbol &SymbolB = RefB->getSymbol();
709 MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
712 // Offset of the symbol in the section
713 int64_t a = Layout.getSymbolOffset(&SDB);
715 // Offset of the relocation in the section
716 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
721 MCSymbolData &SD = Asm.getSymbolData(ASymbol);
722 MCFragment *F = SD.getFragment();
724 Index = F->getParent()->getOrdinal() + 1;
726 // Offset of the symbol in the section
727 Value += Layout.getSymbolOffset(&SD);
729 if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
730 WeakrefUsedInReloc.insert(RelocSymbol);
732 UsedInReloc.insert(RelocSymbol);
736 // Compensate for the addend on i386.
742 unsigned Type = GetRelocType(Target, Fixup, IsPCRel,
743 (RelocSymbol != 0), Addend);
744 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
745 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
746 if (RelocNeedsGOT(Modifier))
749 uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) +
752 // FIXME: no tests cover this. Is adjustFixupOffset dead code?
753 TargetObjectWriter->adjustFixupOffset(Fixup, RelocOffset);
755 if (!hasRelocationAddend())
759 assert(isInt<64>(Addend));
761 assert(isInt<32>(Addend));
763 ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend, Fixup);
764 Relocations[Fragment->getParent()].push_back(ERE);
769 ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
771 MCSymbolData &SD = Asm.getSymbolData(*S);
772 return SD.getIndex();
775 bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm,
776 const MCSymbolData &Data,
777 bool Used, bool Renamed) {
778 if (Data.getFlags() & ELF_Other_Weakref)
787 const MCSymbol &Symbol = Data.getSymbol();
789 if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
792 const MCSymbol &A = Symbol.AliasedSymbol();
793 if (Symbol.isVariable() && !A.isVariable() && A.isUndefined())
796 bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL;
797 if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal)
800 if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
803 if (Symbol.isTemporary())
809 bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature,
810 bool isUsedInReloc) {
811 if (Data.isExternal())
814 const MCSymbol &Symbol = Data.getSymbol();
815 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
817 if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
818 if (isSignature && !isUsedInReloc)
827 void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
828 SectionIndexMapTy &SectionIndexMap,
829 const RelMapTy &RelMap) {
831 for (MCAssembler::iterator it = Asm.begin(),
832 ie = Asm.end(); it != ie; ++it) {
833 const MCSectionELF &Section =
834 static_cast<const MCSectionELF &>(it->getSection());
835 if (Section.getType() != ELF::SHT_GROUP)
837 SectionIndexMap[&Section] = Index++;
840 for (MCAssembler::iterator it = Asm.begin(),
841 ie = Asm.end(); it != ie; ++it) {
842 const MCSectionELF &Section =
843 static_cast<const MCSectionELF &>(it->getSection());
844 if (Section.getType() == ELF::SHT_GROUP ||
845 Section.getType() == ELF::SHT_REL ||
846 Section.getType() == ELF::SHT_RELA)
848 SectionIndexMap[&Section] = Index++;
849 const MCSectionELF *RelSection = RelMap.lookup(&Section);
851 SectionIndexMap[RelSection] = Index++;
855 void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
856 const SectionIndexMapTy &SectionIndexMap,
857 RevGroupMapTy RevGroupMap,
858 unsigned NumRegularSections) {
859 // FIXME: Is this the correct place to do this?
860 // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed?
862 llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
863 MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
864 MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
865 Data.setExternal(true);
866 MCELF::SetBinding(Data, ELF::STB_GLOBAL);
869 // Index 0 is always the empty string.
870 StringMap<uint64_t> StringIndexMap;
871 StringTable += '\x00';
873 // FIXME: We could optimize suffixes in strtab in the same way we
874 // optimize them in shstrtab.
876 // Add the data for the symbols.
877 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
878 ie = Asm.symbol_end(); it != ie; ++it) {
879 const MCSymbol &Symbol = it->getSymbol();
881 bool Used = UsedInReloc.count(&Symbol);
882 bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
883 bool isSignature = RevGroupMap.count(&Symbol);
885 if (!isInSymtab(Asm, *it,
886 Used || WeakrefUsed || isSignature,
887 Renames.count(&Symbol)))
892 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
894 // Undefined symbols are global, but this is the first place we
895 // are able to set it.
896 bool Local = isLocal(*it, isSignature, Used);
897 if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) {
898 MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
899 MCELF::SetBinding(*it, ELF::STB_GLOBAL);
900 MCELF::SetBinding(SD, ELF::STB_GLOBAL);
903 if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
904 MCELF::SetBinding(*it, ELF::STB_WEAK);
906 if (it->isCommon()) {
908 MSD.SectionIndex = ELF::SHN_COMMON;
909 } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
910 MSD.SectionIndex = ELF::SHN_ABS;
911 } else if (RefSymbol.isUndefined()) {
912 if (isSignature && !Used)
913 MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
915 MSD.SectionIndex = ELF::SHN_UNDEF;
917 const MCSectionELF &Section =
918 static_cast<const MCSectionELF&>(RefSymbol.getSection());
919 MSD.SectionIndex = SectionIndexMap.lookup(&Section);
920 if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
921 NeedsSymtabShndx = true;
922 assert(MSD.SectionIndex && "Invalid section index!");
925 // The @@@ in symbol version is replaced with @ in undefined symbols and
926 // @@ in defined ones.
927 StringRef Name = Symbol.getName();
930 size_t Pos = Name.find("@@@");
931 if (Pos != StringRef::npos) {
932 Buf += Name.substr(0, Pos);
933 unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
934 Buf += Name.substr(Pos + Skip);
938 uint64_t &Entry = StringIndexMap[Name];
940 Entry = StringTable.size();
942 StringTable += '\x00';
944 MSD.StringIndex = Entry;
945 if (MSD.SectionIndex == ELF::SHN_UNDEF)
946 UndefinedSymbolData.push_back(MSD);
948 LocalSymbolData.push_back(MSD);
950 ExternalSymbolData.push_back(MSD);
953 // Symbols are required to be in lexicographic order.
954 array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
955 array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
956 array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
958 // Set the symbol indices. Local symbols must come before all other
959 // symbols with non-local bindings.
961 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
962 LocalSymbolData[i].SymbolData->setIndex(Index++);
964 Index += NumRegularSections;
966 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
967 ExternalSymbolData[i].SymbolData->setIndex(Index++);
968 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
969 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
971 if (NumRegularSections > ELF::SHN_LORESERVE)
972 NeedsSymtabShndx = true;
975 void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm,
978 for (MCAssembler::const_iterator it = Asm.begin(),
979 ie = Asm.end(); it != ie; ++it) {
980 const MCSectionData &SD = *it;
981 if (Relocations[&SD].empty())
984 MCContext &Ctx = Asm.getContext();
985 const MCSectionELF &Section =
986 static_cast<const MCSectionELF&>(SD.getSection());
988 const StringRef SectionName = Section.getSectionName();
989 std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel";
990 RelaSectionName += SectionName;
993 if (hasRelocationAddend())
994 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
996 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
998 const MCSectionELF *RelaSection =
999 Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ?
1000 ELF::SHT_RELA : ELF::SHT_REL, 0,
1001 SectionKind::getReadOnly(),
1003 RelMap[&Section] = RelaSection;
1004 Asm.getOrCreateSectionData(*RelaSection);
1008 void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
1009 const RelMapTy &RelMap) {
1010 for (MCAssembler::const_iterator it = Asm.begin(),
1011 ie = Asm.end(); it != ie; ++it) {
1012 const MCSectionData &SD = *it;
1013 const MCSectionELF &Section =
1014 static_cast<const MCSectionELF&>(SD.getSection());
1016 const MCSectionELF *RelaSection = RelMap.lookup(&Section);
1019 MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
1020 RelaSD.setAlignment(is64Bit() ? 8 : 4);
1022 MCDataFragment *F = new MCDataFragment(&RelaSD);
1023 WriteRelocationsFragment(Asm, F, &*it);
1027 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
1028 uint64_t Flags, uint64_t Address,
1029 uint64_t Offset, uint64_t Size,
1030 uint32_t Link, uint32_t Info,
1032 uint64_t EntrySize) {
1033 Write32(Name); // sh_name: index into string table
1034 Write32(Type); // sh_type
1035 WriteWord(Flags); // sh_flags
1036 WriteWord(Address); // sh_addr
1037 WriteWord(Offset); // sh_offset
1038 WriteWord(Size); // sh_size
1039 Write32(Link); // sh_link
1040 Write32(Info); // sh_info
1041 WriteWord(Alignment); // sh_addralign
1042 WriteWord(EntrySize); // sh_entsize
1045 void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
1047 const MCSectionData *SD) {
1048 std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
1050 // Sort the relocation entries. Most targets just sort by r_offset, but some
1051 // (e.g., MIPS) have additional constraints.
1052 TargetObjectWriter->sortRelocs(Asm, Relocs);
1054 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1055 ELFRelocationEntry entry = Relocs[e - i - 1];
1059 else if (entry.Index < 0)
1060 entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
1062 entry.Index += LocalSymbolData.size();
1064 String64(*F, entry.r_offset);
1066 struct ELF::Elf64_Rela ERE64;
1067 ERE64.setSymbolAndType(entry.Index, entry.Type);
1068 String64(*F, ERE64.r_info);
1070 if (hasRelocationAddend())
1071 String64(*F, entry.r_addend);
1073 String32(*F, entry.r_offset);
1075 struct ELF::Elf32_Rela ERE32;
1076 ERE32.setSymbolAndType(entry.Index, entry.Type);
1077 String32(*F, ERE32.r_info);
1079 if (hasRelocationAddend())
1080 String32(*F, entry.r_addend);
1085 static int compareBySuffix(const void *a, const void *b) {
1086 const MCSectionELF *secA = *static_cast<const MCSectionELF* const *>(a);
1087 const MCSectionELF *secB = *static_cast<const MCSectionELF* const *>(b);
1088 const StringRef &NameA = secA->getSectionName();
1089 const StringRef &NameB = secB->getSectionName();
1090 const unsigned sizeA = NameA.size();
1091 const unsigned sizeB = NameB.size();
1092 const unsigned len = std::min(sizeA, sizeB);
1093 for (unsigned int i = 0; i < len; ++i) {
1094 char ca = NameA[sizeA - i - 1];
1095 char cb = NameB[sizeB - i - 1];
1100 return sizeB - sizeA;
1103 void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
1104 MCAsmLayout &Layout,
1105 SectionIndexMapTy &SectionIndexMap,
1106 const RelMapTy &RelMap) {
1107 MCContext &Ctx = Asm.getContext();
1110 unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
1112 // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
1113 const MCSectionELF *ShstrtabSection =
1114 Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
1115 SectionKind::getReadOnly());
1116 MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
1117 ShstrtabSD.setAlignment(1);
1119 const MCSectionELF *SymtabSection =
1120 Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
1121 SectionKind::getReadOnly(),
1123 MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
1124 SymtabSD.setAlignment(is64Bit() ? 8 : 4);
1126 MCSectionData *SymtabShndxSD = NULL;
1128 if (NeedsSymtabShndx) {
1129 const MCSectionELF *SymtabShndxSection =
1130 Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
1131 SectionKind::getReadOnly(), 4, "");
1132 SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
1133 SymtabShndxSD->setAlignment(4);
1136 const MCSectionELF *StrtabSection;
1137 StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
1138 SectionKind::getReadOnly());
1139 MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
1140 StrtabSD.setAlignment(1);
1142 ComputeIndexMap(Asm, SectionIndexMap, RelMap);
1144 ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection);
1145 SymbolTableIndex = SectionIndexMap.lookup(SymtabSection);
1146 StringTableIndex = SectionIndexMap.lookup(StrtabSection);
1149 F = new MCDataFragment(&SymtabSD);
1150 MCDataFragment *ShndxF = NULL;
1151 if (NeedsSymtabShndx) {
1152 ShndxF = new MCDataFragment(SymtabShndxSD);
1154 WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
1156 F = new MCDataFragment(&StrtabSD);
1157 F->getContents().append(StringTable.begin(), StringTable.end());
1159 F = new MCDataFragment(&ShstrtabSD);
1161 std::vector<const MCSectionELF*> Sections;
1162 for (MCAssembler::const_iterator it = Asm.begin(),
1163 ie = Asm.end(); it != ie; ++it) {
1164 const MCSectionELF &Section =
1165 static_cast<const MCSectionELF&>(it->getSection());
1166 Sections.push_back(&Section);
1168 array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix);
1170 // Section header string table.
1172 // The first entry of a string table holds a null character so skip
1175 F->getContents() += '\x00';
1177 for (unsigned int I = 0, E = Sections.size(); I != E; ++I) {
1178 const MCSectionELF &Section = *Sections[I];
1180 StringRef Name = Section.getSectionName();
1182 StringRef PreviousName = Sections[I - 1]->getSectionName();
1183 if (PreviousName.endswith(Name)) {
1184 SectionStringTableIndex[&Section] = Index - Name.size() - 1;
1188 // Remember the index into the string table so we can write it
1189 // into the sh_name field of the section header table.
1190 SectionStringTableIndex[&Section] = Index;
1192 Index += Name.size() + 1;
1193 F->getContents() += Name;
1194 F->getContents() += '\x00';
1198 void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
1199 MCAsmLayout &Layout,
1200 GroupMapTy &GroupMap,
1201 RevGroupMapTy &RevGroupMap,
1202 SectionIndexMapTy &SectionIndexMap,
1203 const RelMapTy &RelMap) {
1204 // Create the .note.GNU-stack section if needed.
1205 MCContext &Ctx = Asm.getContext();
1206 if (Asm.getNoExecStack()) {
1207 const MCSectionELF *GnuStackSection =
1208 Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0,
1209 SectionKind::getReadOnly());
1210 Asm.getOrCreateSectionData(*GnuStackSection);
1214 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1216 const MCSectionELF &Section =
1217 static_cast<const MCSectionELF&>(it->getSection());
1218 if (!(Section.getFlags() & ELF::SHF_GROUP))
1221 const MCSymbol *SignatureSymbol = Section.getGroup();
1222 Asm.getOrCreateSymbolData(*SignatureSymbol);
1223 const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
1225 Group = Ctx.CreateELFGroupSection();
1226 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1227 Data.setAlignment(4);
1228 MCDataFragment *F = new MCDataFragment(&Data);
1229 String32(*F, ELF::GRP_COMDAT);
1231 GroupMap[Group] = SignatureSymbol;
1234 ComputeIndexMap(Asm, SectionIndexMap, RelMap);
1236 // Add sections to the groups
1237 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1239 const MCSectionELF &Section =
1240 static_cast<const MCSectionELF&>(it->getSection());
1241 if (!(Section.getFlags() & ELF::SHF_GROUP))
1243 const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
1244 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1245 // FIXME: we could use the previous fragment
1246 MCDataFragment *F = new MCDataFragment(&Data);
1247 unsigned Index = SectionIndexMap.lookup(&Section);
1248 String32(*F, Index);
1252 void ELFObjectWriter::WriteSection(MCAssembler &Asm,
1253 const SectionIndexMapTy &SectionIndexMap,
1254 uint32_t GroupSymbolIndex,
1255 uint64_t Offset, uint64_t Size,
1257 const MCSectionELF &Section) {
1258 uint64_t sh_link = 0;
1259 uint64_t sh_info = 0;
1261 switch(Section.getType()) {
1262 case ELF::SHT_DYNAMIC:
1263 sh_link = SectionStringTableIndex[&Section];
1268 case ELF::SHT_RELA: {
1269 const MCSectionELF *SymtabSection;
1270 const MCSectionELF *InfoSection;
1271 SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
1273 SectionKind::getReadOnly());
1274 sh_link = SectionIndexMap.lookup(SymtabSection);
1275 assert(sh_link && ".symtab not found");
1277 // Remove ".rel" and ".rela" prefixes.
1278 unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
1279 StringRef SectionName = Section.getSectionName().substr(SecNameLen);
1281 InfoSection = Asm.getContext().getELFSection(SectionName,
1282 ELF::SHT_PROGBITS, 0,
1283 SectionKind::getReadOnly());
1284 sh_info = SectionIndexMap.lookup(InfoSection);
1288 case ELF::SHT_SYMTAB:
1289 case ELF::SHT_DYNSYM:
1290 sh_link = StringTableIndex;
1291 sh_info = LastLocalSymbolIndex;
1294 case ELF::SHT_SYMTAB_SHNDX:
1295 sh_link = SymbolTableIndex;
1298 case ELF::SHT_PROGBITS:
1299 case ELF::SHT_STRTAB:
1300 case ELF::SHT_NOBITS:
1303 case ELF::SHT_ARM_ATTRIBUTES:
1304 case ELF::SHT_INIT_ARRAY:
1305 case ELF::SHT_FINI_ARRAY:
1306 case ELF::SHT_PREINIT_ARRAY:
1307 case ELF::SHT_X86_64_UNWIND:
1311 case ELF::SHT_GROUP:
1312 sh_link = SymbolTableIndex;
1313 sh_info = GroupSymbolIndex;
1317 assert(0 && "FIXME: sh_type value not supported!");
1321 WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
1322 Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
1323 Alignment, Section.getEntrySize());
1326 bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) {
1327 return SD.getOrdinal() == ~UINT32_C(0) &&
1328 !SD.getSection().isVirtualSection();
1331 uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) {
1333 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1335 const MCFragment &F = *i;
1336 assert(F.getKind() == MCFragment::FT_Data);
1337 Ret += cast<MCDataFragment>(F).getContents().size();
1342 uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout,
1343 const MCSectionData &SD) {
1344 if (IsELFMetaDataSection(SD))
1345 return DataSectionSize(SD);
1346 return Layout.getSectionFileSize(&SD);
1349 uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout,
1350 const MCSectionData &SD) {
1351 if (IsELFMetaDataSection(SD))
1352 return DataSectionSize(SD);
1353 return Layout.getSectionAddressSize(&SD);
1356 void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
1357 const MCAsmLayout &Layout,
1358 const MCSectionELF &Section) {
1359 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1361 uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment());
1362 WriteZeros(Padding);
1364 if (IsELFMetaDataSection(SD)) {
1365 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1367 const MCFragment &F = *i;
1368 assert(F.getKind() == MCFragment::FT_Data);
1369 WriteBytes(cast<MCDataFragment>(F).getContents().str());
1372 Asm.writeSectionData(&SD, Layout);
1376 void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm,
1377 const GroupMapTy &GroupMap,
1378 const MCAsmLayout &Layout,
1379 const SectionIndexMapTy &SectionIndexMap,
1380 const SectionOffsetMapTy &SectionOffsetMap) {
1381 const unsigned NumSections = Asm.size() + 1;
1383 std::vector<const MCSectionELF*> Sections;
1384 Sections.resize(NumSections - 1);
1386 for (SectionIndexMapTy::const_iterator i=
1387 SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
1388 const std::pair<const MCSectionELF*, uint32_t> &p = *i;
1389 Sections[p.second - 1] = p.first;
1392 // Null section first.
1393 uint64_t FirstSectionSize =
1394 NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
1395 uint32_t FirstSectionLink =
1396 ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
1397 WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
1399 for (unsigned i = 0; i < NumSections - 1; ++i) {
1400 const MCSectionELF &Section = *Sections[i];
1401 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1402 uint32_t GroupSymbolIndex;
1403 if (Section.getType() != ELF::SHT_GROUP)
1404 GroupSymbolIndex = 0;
1406 GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm,
1407 GroupMap.lookup(&Section));
1409 uint64_t Size = GetSectionAddressSize(Layout, SD);
1411 WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
1412 SectionOffsetMap.lookup(&Section), Size,
1413 SD.getAlignment(), Section);
1417 void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm,
1418 std::vector<const MCSectionELF*> &Sections) {
1419 for (MCAssembler::iterator it = Asm.begin(),
1420 ie = Asm.end(); it != ie; ++it) {
1421 const MCSectionELF &Section =
1422 static_cast<const MCSectionELF &>(it->getSection());
1423 if (Section.getType() == ELF::SHT_GROUP)
1424 Sections.push_back(&Section);
1427 for (MCAssembler::iterator it = Asm.begin(),
1428 ie = Asm.end(); it != ie; ++it) {
1429 const MCSectionELF &Section =
1430 static_cast<const MCSectionELF &>(it->getSection());
1431 if (Section.getType() != ELF::SHT_GROUP &&
1432 Section.getType() != ELF::SHT_REL &&
1433 Section.getType() != ELF::SHT_RELA)
1434 Sections.push_back(&Section);
1437 for (MCAssembler::iterator it = Asm.begin(),
1438 ie = Asm.end(); it != ie; ++it) {
1439 const MCSectionELF &Section =
1440 static_cast<const MCSectionELF &>(it->getSection());
1441 if (Section.getType() == ELF::SHT_REL ||
1442 Section.getType() == ELF::SHT_RELA)
1443 Sections.push_back(&Section);
1447 void ELFObjectWriter::WriteObject(MCAssembler &Asm,
1448 const MCAsmLayout &Layout) {
1449 GroupMapTy GroupMap;
1450 RevGroupMapTy RevGroupMap;
1451 SectionIndexMapTy SectionIndexMap;
1453 unsigned NumUserSections = Asm.size();
1455 DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
1456 CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
1458 const unsigned NumUserAndRelocSections = Asm.size();
1459 CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
1460 RevGroupMap, SectionIndexMap, RelMap);
1461 const unsigned AllSections = Asm.size();
1462 const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
1464 unsigned NumRegularSections = NumUserSections + NumIndexedSections;
1466 // Compute symbol table information.
1467 ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections);
1470 WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
1472 CreateMetadataSections(const_cast<MCAssembler&>(Asm),
1473 const_cast<MCAsmLayout&>(Layout),
1477 uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
1478 uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
1479 sizeof(ELF::Elf32_Ehdr);
1480 uint64_t FileOff = HeaderSize;
1482 std::vector<const MCSectionELF*> Sections;
1483 ComputeSectionOrder(Asm, Sections);
1484 unsigned NumSections = Sections.size();
1485 SectionOffsetMapTy SectionOffsetMap;
1486 for (unsigned i = 0; i < NumRegularSections + 1; ++i) {
1487 const MCSectionELF &Section = *Sections[i];
1488 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1490 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1492 // Remember the offset into the file for this section.
1493 SectionOffsetMap[&Section] = FileOff;
1495 // Get the size of the section in the output file (including padding).
1496 FileOff += GetSectionFileSize(Layout, SD);
1499 FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
1501 const unsigned SectionHeaderOffset = FileOff - HeaderSize;
1503 uint64_t SectionHeaderEntrySize = is64Bit() ?
1504 sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr);
1505 FileOff += (NumSections + 1) * SectionHeaderEntrySize;
1507 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) {
1508 const MCSectionELF &Section = *Sections[i];
1509 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1511 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1513 // Remember the offset into the file for this section.
1514 SectionOffsetMap[&Section] = FileOff;
1516 // Get the size of the section in the output file (including padding).
1517 FileOff += GetSectionFileSize(Layout, SD);
1520 // Write out the ELF header ...
1521 WriteHeader(SectionHeaderOffset, NumSections + 1);
1523 // ... then the regular sections ...
1524 // + because of .shstrtab
1525 for (unsigned i = 0; i < NumRegularSections + 1; ++i)
1526 WriteDataSectionData(Asm, Layout, *Sections[i]);
1528 uint64_t Padding = OffsetToAlignment(OS.tell(), NaturalAlignment);
1529 WriteZeros(Padding);
1531 // ... then the section header table ...
1532 WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap,
1535 // ... and then the remaining sections ...
1536 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)
1537 WriteDataSectionData(Asm, Layout, *Sections[i]);
1541 ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
1542 const MCSymbolData &DataA,
1543 const MCFragment &FB,
1545 bool IsPCRel) const {
1546 if (DataA.getFlags() & ELF_STB_Weak)
1548 return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
1549 Asm, DataA, FB,InSet, IsPCRel);
1552 MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
1554 bool IsLittleEndian) {
1555 return new ELFObjectWriter(MOTW, OS, IsLittleEndian);