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 //===----------------------------------------------------------------------===//
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/ADT/OwningPtr.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/SmallPtrSet.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/MC/MCAsmBackend.h"
21 #include "llvm/MC/MCAsmLayout.h"
22 #include "llvm/MC/MCAssembler.h"
23 #include "llvm/MC/MCContext.h"
24 #include "llvm/MC/MCELF.h"
25 #include "llvm/MC/MCELFSymbolFlags.h"
26 #include "llvm/MC/MCExpr.h"
27 #include "llvm/MC/MCFixupKindInfo.h"
28 #include "llvm/MC/MCObjectWriter.h"
29 #include "llvm/MC/MCSectionELF.h"
30 #include "llvm/MC/MCValue.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/ELF.h"
33 #include "llvm/Support/ErrorHandling.h"
38 #define DEBUG_TYPE "reloc-info"
41 class ELFObjectWriter : public MCObjectWriter {
44 static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
45 static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant);
46 static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout);
47 static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
48 bool Used, bool Renamed);
49 static bool isLocal(const MCSymbolData &Data, bool isSignature,
51 static bool IsELFMetaDataSection(const MCSectionData &SD);
52 static uint64_t DataSectionSize(const MCSectionData &SD);
53 static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
54 const MCSectionData &SD);
55 static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
56 const MCSectionData &SD);
58 void WriteDataSectionData(MCAssembler &Asm,
59 const MCAsmLayout &Layout,
60 const MCSectionELF &Section);
62 /*static bool isFixupKindX86RIPRel(unsigned Kind) {
63 return Kind == X86::reloc_riprel_4byte ||
64 Kind == X86::reloc_riprel_4byte_movq_load;
67 /// ELFSymbolData - Helper struct for containing some precomputed
68 /// information on symbols.
69 struct ELFSymbolData {
70 MCSymbolData *SymbolData;
72 uint32_t SectionIndex;
74 // Support lexicographic sorting.
75 bool operator<(const ELFSymbolData &RHS) const {
76 if (MCELF::GetType(*SymbolData) == ELF::STT_FILE)
78 if (MCELF::GetType(*RHS.SymbolData) == ELF::STT_FILE)
80 return SymbolData->getSymbol().getName() <
81 RHS.SymbolData->getSymbol().getName();
85 /// The target specific ELF writer instance.
86 llvm::OwningPtr<MCELFObjectTargetWriter> TargetObjectWriter;
88 SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
89 SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
90 DenseMap<const MCSymbol *, const MCSymbol *> Renames;
92 llvm::DenseMap<const MCSectionData*,
93 std::vector<ELFRelocationEntry> > Relocations;
94 DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
97 /// @name Symbol Table Data
100 SmallString<256> StringTable;
101 std::vector<ELFSymbolData> LocalSymbolData;
102 std::vector<ELFSymbolData> ExternalSymbolData;
103 std::vector<ELFSymbolData> UndefinedSymbolData;
109 bool NeedsSymtabShndx;
111 // This holds the symbol table index of the last local symbol.
112 unsigned LastLocalSymbolIndex;
113 // This holds the .strtab section index.
114 unsigned StringTableIndex;
115 // This holds the .symtab section index.
116 unsigned SymbolTableIndex;
118 unsigned ShstrtabIndex;
121 const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
122 const MCValue &Target,
124 const MCFixup &Fixup,
127 // TargetObjectWriter wrappers.
128 const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
129 const MCValue &Target,
131 const MCFixup &Fixup,
132 bool IsPCRel) const {
133 return TargetObjectWriter->ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
135 const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
136 const MCFixup &Fixup,
137 bool IsPCRel) const {
138 return TargetObjectWriter->undefinedExplicitRelSym(Target, Fixup,
142 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
143 bool hasRelocationAddend() const {
144 return TargetObjectWriter->hasRelocationAddend();
146 unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
147 bool IsPCRel, bool IsRelocWithSymbol,
148 int64_t Addend) const {
149 return TargetObjectWriter->GetRelocType(Target, Fixup, IsPCRel,
150 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().append(&buf[0], &buf[1]);
206 void String16(MCDataFragment &F, uint16_t Value) {
208 if (isLittleEndian())
209 StringLE16(buf, Value);
211 StringBE16(buf, Value);
212 F.getContents().append(&buf[0], &buf[2]);
215 void String32(MCDataFragment &F, uint32_t Value) {
217 if (isLittleEndian())
218 StringLE32(buf, Value);
220 StringBE32(buf, Value);
221 F.getContents().append(&buf[0], &buf[4]);
224 void String64(MCDataFragment &F, uint64_t Value) {
226 if (isLittleEndian())
227 StringLE64(buf, Value);
229 StringBE64(buf, Value);
230 F.getContents().append(&buf[0], &buf[8]);
233 void WriteHeader(const MCAssembler &Asm,
234 uint64_t SectionDataSize,
235 unsigned NumberOfSections);
237 void WriteSymbolEntry(MCDataFragment *SymtabF,
238 MCDataFragment *ShndxF,
239 uint64_t name, uint8_t info,
240 uint64_t value, uint64_t size,
241 uint8_t other, uint32_t shndx,
244 void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
246 const MCAsmLayout &Layout);
248 typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
249 void WriteSymbolTable(MCDataFragment *SymtabF,
250 MCDataFragment *ShndxF,
251 const MCAssembler &Asm,
252 const MCAsmLayout &Layout,
253 const SectionIndexMapTy &SectionIndexMap);
255 virtual void RecordRelocation(const MCAssembler &Asm,
256 const MCAsmLayout &Layout,
257 const MCFragment *Fragment,
258 const MCFixup &Fixup,
259 MCValue Target, uint64_t &FixedValue);
261 uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
264 // Map from a group section to the signature symbol
265 typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
266 // Map from a signature symbol to the group section
267 typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
268 // Map from a section to the section with the relocations
269 typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy;
270 // Map from a section to its offset
271 typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy;
273 /// ComputeSymbolTable - Compute the symbol table data
275 /// \param Asm - The assembler.
276 /// \param SectionIndexMap - Maps a section to its index.
277 /// \param RevGroupMap - Maps a signature symbol to the group section.
278 /// \param NumRegularSections - Number of non-relocation sections.
279 void ComputeSymbolTable(MCAssembler &Asm,
280 const SectionIndexMapTy &SectionIndexMap,
281 RevGroupMapTy RevGroupMap,
282 unsigned NumRegularSections);
284 void ComputeIndexMap(MCAssembler &Asm,
285 SectionIndexMapTy &SectionIndexMap,
286 const RelMapTy &RelMap);
288 void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
291 void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
292 const RelMapTy &RelMap);
294 void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
295 SectionIndexMapTy &SectionIndexMap,
296 const RelMapTy &RelMap);
298 // Create the sections that show up in the symbol table. Currently
299 // those are the .note.GNU-stack section and the group sections.
300 void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
301 GroupMapTy &GroupMap,
302 RevGroupMapTy &RevGroupMap,
303 SectionIndexMapTy &SectionIndexMap,
304 const RelMapTy &RelMap);
306 virtual void ExecutePostLayoutBinding(MCAssembler &Asm,
307 const MCAsmLayout &Layout);
309 void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
310 const MCAsmLayout &Layout,
311 const SectionIndexMapTy &SectionIndexMap,
312 const SectionOffsetMapTy &SectionOffsetMap);
314 void ComputeSectionOrder(MCAssembler &Asm,
315 std::vector<const MCSectionELF*> &Sections);
317 void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
318 uint64_t Address, uint64_t Offset,
319 uint64_t Size, uint32_t Link, uint32_t Info,
320 uint64_t Alignment, uint64_t EntrySize);
322 void WriteRelocationsFragment(const MCAssembler &Asm,
324 const MCSectionData *SD);
327 IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
328 const MCSymbolData &DataA,
329 const MCFragment &FB,
333 virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
334 void WriteSection(MCAssembler &Asm,
335 const SectionIndexMapTy &SectionIndexMap,
336 uint32_t GroupSymbolIndex,
337 uint64_t Offset, uint64_t Size, uint64_t Alignment,
338 const MCSectionELF &Section);
342 bool ELFObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
343 const MCFixupKindInfo &FKI =
344 Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind);
346 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
349 bool ELFObjectWriter::RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
353 case MCSymbolRefExpr::VK_GOT:
354 case MCSymbolRefExpr::VK_PLT:
355 case MCSymbolRefExpr::VK_GOTPCREL:
356 case MCSymbolRefExpr::VK_GOTOFF:
357 case MCSymbolRefExpr::VK_TPOFF:
358 case MCSymbolRefExpr::VK_TLSGD:
359 case MCSymbolRefExpr::VK_GOTTPOFF:
360 case MCSymbolRefExpr::VK_INDNTPOFF:
361 case MCSymbolRefExpr::VK_NTPOFF:
362 case MCSymbolRefExpr::VK_GOTNTPOFF:
363 case MCSymbolRefExpr::VK_TLSLDM:
364 case MCSymbolRefExpr::VK_DTPOFF:
365 case MCSymbolRefExpr::VK_TLSLD:
370 ELFObjectWriter::~ELFObjectWriter()
373 // Emit the ELF header.
374 void ELFObjectWriter::WriteHeader(const MCAssembler &Asm,
375 uint64_t SectionDataSize,
376 unsigned NumberOfSections) {
382 // emitWord method behaves differently for ELF32 and ELF64, writing
383 // 4 bytes in the former and 8 in the latter.
385 Write8(0x7f); // e_ident[EI_MAG0]
386 Write8('E'); // e_ident[EI_MAG1]
387 Write8('L'); // e_ident[EI_MAG2]
388 Write8('F'); // e_ident[EI_MAG3]
390 Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
393 Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
395 Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
397 Write8(TargetObjectWriter->getOSABI());
398 Write8(0); // e_ident[EI_ABIVERSION]
400 WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
402 Write16(ELF::ET_REL); // e_type
404 Write16(TargetObjectWriter->getEMachine()); // e_machine = target
406 Write32(ELF::EV_CURRENT); // e_version
407 WriteWord(0); // e_entry, no entry point in .o file
408 WriteWord(0); // e_phoff, no program header for .o
409 WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
410 sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes
412 // e_flags = whatever the target wants
413 Write32(Asm.getELFHeaderEFlags());
415 // e_ehsize = ELF header size
416 Write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
418 Write16(0); // e_phentsize = prog header entry size
419 Write16(0); // e_phnum = # prog header entries = 0
421 // e_shentsize = Section header entry size
422 Write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
424 // e_shnum = # of section header ents
425 if (NumberOfSections >= ELF::SHN_LORESERVE)
426 Write16(ELF::SHN_UNDEF);
428 Write16(NumberOfSections);
430 // e_shstrndx = Section # of '.shstrtab'
431 if (ShstrtabIndex >= ELF::SHN_LORESERVE)
432 Write16(ELF::SHN_XINDEX);
434 Write16(ShstrtabIndex);
437 void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
438 MCDataFragment *ShndxF,
440 uint8_t info, uint64_t value,
441 uint64_t size, uint8_t other,
445 if (shndx >= ELF::SHN_LORESERVE && !Reserved)
446 String32(*ShndxF, shndx);
448 String32(*ShndxF, 0);
451 uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
452 uint16_t(ELF::SHN_XINDEX) : shndx;
455 String32(*SymtabF, name); // st_name
456 String8(*SymtabF, info); // st_info
457 String8(*SymtabF, other); // st_other
458 String16(*SymtabF, Index); // st_shndx
459 String64(*SymtabF, value); // st_value
460 String64(*SymtabF, size); // st_size
462 String32(*SymtabF, name); // st_name
463 String32(*SymtabF, value); // st_value
464 String32(*SymtabF, size); // st_size
465 String8(*SymtabF, info); // st_info
466 String8(*SymtabF, other); // st_other
467 String16(*SymtabF, Index); // st_shndx
471 uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
472 const MCAsmLayout &Layout) {
473 if (Data.isCommon() && Data.isExternal())
474 return Data.getCommonAlignment();
476 const MCSymbol &Symbol = Data.getSymbol();
478 if (Symbol.isAbsolute() && Symbol.isVariable()) {
479 if (const MCExpr *Value = Symbol.getVariableValue()) {
481 if (Value->EvaluateAsAbsolute(IntValue, Layout))
482 return (uint64_t)IntValue;
486 if (!Symbol.isInSection())
490 if (Data.getFragment()) {
491 if (Data.getFlags() & ELF_Other_ThumbFunc)
492 return Layout.getSymbolOffset(&Data)+1;
494 return Layout.getSymbolOffset(&Data);
500 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
501 const MCAsmLayout &Layout) {
502 // The presence of symbol versions causes undefined symbols and
503 // versions declared with @@@ to be renamed.
505 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
506 ie = Asm.symbol_end(); it != ie; ++it) {
507 const MCSymbol &Alias = it->getSymbol();
508 const MCSymbol &Symbol = Alias.AliasedSymbol();
509 MCSymbolData &SD = Asm.getSymbolData(Symbol);
512 if (&Symbol == &Alias)
515 StringRef AliasName = Alias.getName();
516 size_t Pos = AliasName.find('@');
517 if (Pos == StringRef::npos)
520 // Aliases defined with .symvar copy the binding from the symbol they alias.
521 // This is the first place we are able to copy this information.
522 it->setExternal(SD.isExternal());
523 MCELF::SetBinding(*it, MCELF::GetBinding(SD));
525 StringRef Rest = AliasName.substr(Pos);
526 if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
529 // FIXME: produce a better error message.
530 if (Symbol.isUndefined() && Rest.startswith("@@") &&
531 !Rest.startswith("@@@"))
532 report_fatal_error("A @@ version cannot be undefined");
534 Renames.insert(std::make_pair(&Symbol, &Alias));
538 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
539 MCDataFragment *ShndxF,
541 const MCAsmLayout &Layout) {
542 MCSymbolData &OrigData = *MSD.SymbolData;
544 Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
546 bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
547 Data.getSymbol().isVariable();
549 uint8_t Binding = MCELF::GetBinding(OrigData);
550 uint8_t Visibility = MCELF::GetVisibility(OrigData);
551 uint8_t Type = MCELF::GetType(Data);
553 uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
554 uint8_t Other = Visibility;
556 uint64_t Value = SymbolValue(Data, Layout);
559 assert(!(Data.isCommon() && !Data.isExternal()));
561 const MCExpr *ESize = Data.getSize();
564 if (!ESize->EvaluateAsAbsolute(Res, Layout))
565 report_fatal_error("Size expression must be absolute.");
569 // Write out the symbol table entry
570 WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
571 Size, Other, MSD.SectionIndex, IsReserved);
574 void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
575 MCDataFragment *ShndxF,
576 const MCAssembler &Asm,
577 const MCAsmLayout &Layout,
578 const SectionIndexMapTy &SectionIndexMap) {
579 // The string table must be emitted first because we need the index
580 // into the string table for all the symbol names.
581 assert(StringTable.size() && "Missing string table");
583 // FIXME: Make sure the start of the symbol table is aligned.
585 // The first entry is the undefined symbol entry.
586 WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
588 // Write the symbol table entries.
589 LastLocalSymbolIndex = LocalSymbolData.size() + 1;
590 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
591 ELFSymbolData &MSD = LocalSymbolData[i];
592 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
595 // Write out a symbol table entry for each regular section.
596 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
598 const MCSectionELF &Section =
599 static_cast<const MCSectionELF&>(i->getSection());
600 if (Section.getType() == ELF::SHT_RELA ||
601 Section.getType() == ELF::SHT_REL ||
602 Section.getType() == ELF::SHT_STRTAB ||
603 Section.getType() == ELF::SHT_SYMTAB ||
604 Section.getType() == ELF::SHT_SYMTAB_SHNDX)
606 WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0,
607 ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section),
609 LastLocalSymbolIndex++;
612 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
613 ELFSymbolData &MSD = ExternalSymbolData[i];
614 MCSymbolData &Data = *MSD.SymbolData;
615 assert(((Data.getFlags() & ELF_STB_Global) ||
616 (Data.getFlags() & ELF_STB_Weak)) &&
617 "External symbol requires STB_GLOBAL or STB_WEAK flag");
618 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
619 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
620 LastLocalSymbolIndex++;
623 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
624 ELFSymbolData &MSD = UndefinedSymbolData[i];
625 MCSymbolData &Data = *MSD.SymbolData;
626 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
627 if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
628 LastLocalSymbolIndex++;
632 const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
633 const MCValue &Target,
635 const MCFixup &Fixup,
636 bool IsPCRel) const {
637 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
638 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
639 const MCSymbol *Renamed = Renames.lookup(&Symbol);
640 const MCSymbolData &SD = Asm.getSymbolData(Symbol);
642 if (ASymbol.isUndefined()) {
645 return undefinedExplicitRelSym(Target, Fixup, IsPCRel);
648 if (SD.isExternal()) {
654 const MCSectionELF &Section =
655 static_cast<const MCSectionELF&>(ASymbol.getSection());
656 const SectionKind secKind = Section.getKind();
659 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
661 if (secKind.isThreadLocal()) {
667 MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
668 const MCSectionELF &Sec2 =
669 static_cast<const MCSectionELF&>(F.getParent()->getSection());
671 if (&Sec2 != &Section &&
672 (Kind == MCSymbolRefExpr::VK_PLT ||
673 Kind == MCSymbolRefExpr::VK_GOTPCREL ||
674 Kind == MCSymbolRefExpr::VK_GOTOFF)) {
680 if (Section.getFlags() & ELF::SHF_MERGE) {
681 if (Target.getConstant() == 0)
682 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
688 return ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
693 void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
694 const MCAsmLayout &Layout,
695 const MCFragment *Fragment,
696 const MCFixup &Fixup,
698 uint64_t &FixedValue) {
701 int64_t Value = Target.getConstant();
702 const MCSymbol *RelocSymbol = NULL;
704 bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
705 if (!Target.isAbsolute()) {
706 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
707 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
708 RelocSymbol = SymbolToReloc(Asm, Target, *Fragment, Fixup, IsPCRel);
710 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
711 const MCSymbol &SymbolB = RefB->getSymbol();
712 MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
715 // Offset of the symbol in the section
716 int64_t a = Layout.getSymbolOffset(&SDB);
718 // Offset of the relocation in the section
719 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
724 MCSymbolData &SD = Asm.getSymbolData(ASymbol);
725 MCFragment *F = SD.getFragment();
728 Index = F->getParent()->getOrdinal() + 1;
729 // Offset of the symbol in the section
730 Value += Layout.getSymbolOffset(&SD);
735 if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
736 WeakrefUsedInReloc.insert(RelocSymbol);
738 UsedInReloc.insert(RelocSymbol);
742 if (hasRelocationAddend())
747 unsigned Type = GetRelocType(Target, Fixup, IsPCRel,
748 (RelocSymbol != 0), Addend);
749 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
750 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
751 if (RelocNeedsGOT(Modifier))
754 uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) +
757 // FIXME: no tests cover this. Is adjustFixupOffset dead code?
758 TargetObjectWriter->adjustFixupOffset(Fixup, RelocOffset);
760 if (!hasRelocationAddend())
764 assert(isInt<64>(Addend));
766 assert(isInt<32>(Addend));
768 ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend, Fixup);
769 Relocations[Fragment->getParent()].push_back(ERE);
774 ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
776 MCSymbolData &SD = Asm.getSymbolData(*S);
777 return SD.getIndex();
780 bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm,
781 const MCSymbolData &Data,
782 bool Used, bool Renamed) {
783 if (Data.getFlags() & ELF_Other_Weakref)
792 const MCSymbol &Symbol = Data.getSymbol();
794 if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
797 const MCSymbol &A = Symbol.AliasedSymbol();
798 if (Symbol.isVariable() && !A.isVariable() && A.isUndefined())
801 bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL;
802 if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal)
805 if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
808 if (Symbol.isTemporary())
814 bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature,
815 bool isUsedInReloc) {
816 if (Data.isExternal())
819 const MCSymbol &Symbol = Data.getSymbol();
820 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
822 if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
823 if (isSignature && !isUsedInReloc)
832 void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
833 SectionIndexMapTy &SectionIndexMap,
834 const RelMapTy &RelMap) {
836 for (MCAssembler::iterator it = Asm.begin(),
837 ie = Asm.end(); it != ie; ++it) {
838 const MCSectionELF &Section =
839 static_cast<const MCSectionELF &>(it->getSection());
840 if (Section.getType() != ELF::SHT_GROUP)
842 SectionIndexMap[&Section] = Index++;
845 for (MCAssembler::iterator it = Asm.begin(),
846 ie = Asm.end(); it != ie; ++it) {
847 const MCSectionELF &Section =
848 static_cast<const MCSectionELF &>(it->getSection());
849 if (Section.getType() == ELF::SHT_GROUP ||
850 Section.getType() == ELF::SHT_REL ||
851 Section.getType() == ELF::SHT_RELA)
853 SectionIndexMap[&Section] = Index++;
854 const MCSectionELF *RelSection = RelMap.lookup(&Section);
856 SectionIndexMap[RelSection] = Index++;
860 void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
861 const SectionIndexMapTy &SectionIndexMap,
862 RevGroupMapTy RevGroupMap,
863 unsigned NumRegularSections) {
864 // FIXME: Is this the correct place to do this?
865 // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed?
867 StringRef Name = "_GLOBAL_OFFSET_TABLE_";
868 MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
869 MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
870 Data.setExternal(true);
871 MCELF::SetBinding(Data, ELF::STB_GLOBAL);
874 // Index 0 is always the empty string.
875 StringMap<uint64_t> StringIndexMap;
876 StringTable += '\x00';
878 // FIXME: We could optimize suffixes in strtab in the same way we
879 // optimize them in shstrtab.
881 // Add the data for the symbols.
882 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
883 ie = Asm.symbol_end(); it != ie; ++it) {
884 const MCSymbol &Symbol = it->getSymbol();
886 bool Used = UsedInReloc.count(&Symbol);
887 bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
888 bool isSignature = RevGroupMap.count(&Symbol);
890 if (!isInSymtab(Asm, *it,
891 Used || WeakrefUsed || isSignature,
892 Renames.count(&Symbol)))
897 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
899 // Undefined symbols are global, but this is the first place we
900 // are able to set it.
901 bool Local = isLocal(*it, isSignature, Used);
902 if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) {
903 MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
904 MCELF::SetBinding(*it, ELF::STB_GLOBAL);
905 MCELF::SetBinding(SD, ELF::STB_GLOBAL);
908 if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
909 MCELF::SetBinding(*it, ELF::STB_WEAK);
911 if (it->isCommon()) {
913 MSD.SectionIndex = ELF::SHN_COMMON;
914 } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
915 MSD.SectionIndex = ELF::SHN_ABS;
916 } else if (RefSymbol.isUndefined()) {
917 if (isSignature && !Used)
918 MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
920 MSD.SectionIndex = ELF::SHN_UNDEF;
922 const MCSectionELF &Section =
923 static_cast<const MCSectionELF&>(RefSymbol.getSection());
924 MSD.SectionIndex = SectionIndexMap.lookup(&Section);
925 if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
926 NeedsSymtabShndx = true;
927 assert(MSD.SectionIndex && "Invalid section index!");
930 // The @@@ in symbol version is replaced with @ in undefined symbols and
931 // @@ in defined ones.
932 StringRef Name = Symbol.getName();
935 size_t Pos = Name.find("@@@");
936 if (Pos != StringRef::npos) {
937 Buf += Name.substr(0, Pos);
938 unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
939 Buf += Name.substr(Pos + Skip);
943 uint64_t &Entry = StringIndexMap[Name];
945 Entry = StringTable.size();
947 StringTable += '\x00';
949 MSD.StringIndex = Entry;
950 if (MSD.SectionIndex == ELF::SHN_UNDEF)
951 UndefinedSymbolData.push_back(MSD);
953 LocalSymbolData.push_back(MSD);
955 ExternalSymbolData.push_back(MSD);
958 // Symbols are required to be in lexicographic order.
959 array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
960 array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
961 array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
963 // Set the symbol indices. Local symbols must come before all other
964 // symbols with non-local bindings.
966 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
967 LocalSymbolData[i].SymbolData->setIndex(Index++);
969 Index += NumRegularSections;
971 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
972 ExternalSymbolData[i].SymbolData->setIndex(Index++);
973 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
974 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
976 if (NumRegularSections > ELF::SHN_LORESERVE)
977 NeedsSymtabShndx = true;
980 void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm,
983 for (MCAssembler::const_iterator it = Asm.begin(),
984 ie = Asm.end(); it != ie; ++it) {
985 const MCSectionData &SD = *it;
986 if (Relocations[&SD].empty())
989 MCContext &Ctx = Asm.getContext();
990 const MCSectionELF &Section =
991 static_cast<const MCSectionELF&>(SD.getSection());
993 const StringRef SectionName = Section.getSectionName();
994 std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel";
995 RelaSectionName += SectionName;
998 if (hasRelocationAddend())
999 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
1001 EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
1003 const MCSectionELF *RelaSection =
1004 Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ?
1005 ELF::SHT_RELA : ELF::SHT_REL, 0,
1006 SectionKind::getReadOnly(),
1008 RelMap[&Section] = RelaSection;
1009 Asm.getOrCreateSectionData(*RelaSection);
1013 void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
1014 const RelMapTy &RelMap) {
1015 for (MCAssembler::const_iterator it = Asm.begin(),
1016 ie = Asm.end(); it != ie; ++it) {
1017 const MCSectionData &SD = *it;
1018 const MCSectionELF &Section =
1019 static_cast<const MCSectionELF&>(SD.getSection());
1021 const MCSectionELF *RelaSection = RelMap.lookup(&Section);
1024 MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
1025 RelaSD.setAlignment(is64Bit() ? 8 : 4);
1027 MCDataFragment *F = new MCDataFragment(&RelaSD);
1028 WriteRelocationsFragment(Asm, F, &*it);
1032 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
1033 uint64_t Flags, uint64_t Address,
1034 uint64_t Offset, uint64_t Size,
1035 uint32_t Link, uint32_t Info,
1037 uint64_t EntrySize) {
1038 Write32(Name); // sh_name: index into string table
1039 Write32(Type); // sh_type
1040 WriteWord(Flags); // sh_flags
1041 WriteWord(Address); // sh_addr
1042 WriteWord(Offset); // sh_offset
1043 WriteWord(Size); // sh_size
1044 Write32(Link); // sh_link
1045 Write32(Info); // sh_info
1046 WriteWord(Alignment); // sh_addralign
1047 WriteWord(EntrySize); // sh_entsize
1050 void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
1052 const MCSectionData *SD) {
1053 std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
1055 // Sort the relocation entries. Most targets just sort by r_offset, but some
1056 // (e.g., MIPS) have additional constraints.
1057 TargetObjectWriter->sortRelocs(Asm, Relocs);
1059 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1060 ELFRelocationEntry entry = Relocs[e - i - 1];
1064 else if (entry.Index < 0)
1065 entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
1067 entry.Index += LocalSymbolData.size();
1069 String64(*F, entry.r_offset);
1070 if (TargetObjectWriter->isN64()) {
1071 String32(*F, entry.Index);
1073 String8(*F, TargetObjectWriter->getRSsym(entry.Type));
1074 String8(*F, TargetObjectWriter->getRType3(entry.Type));
1075 String8(*F, TargetObjectWriter->getRType2(entry.Type));
1076 String8(*F, TargetObjectWriter->getRType(entry.Type));
1079 struct ELF::Elf64_Rela ERE64;
1080 ERE64.setSymbolAndType(entry.Index, entry.Type);
1081 String64(*F, ERE64.r_info);
1083 if (hasRelocationAddend())
1084 String64(*F, entry.r_addend);
1086 String32(*F, entry.r_offset);
1088 struct ELF::Elf32_Rela ERE32;
1089 ERE32.setSymbolAndType(entry.Index, entry.Type);
1090 String32(*F, ERE32.r_info);
1092 if (hasRelocationAddend())
1093 String32(*F, entry.r_addend);
1098 static int compareBySuffix(const void *a, const void *b) {
1099 const MCSectionELF *secA = *static_cast<const MCSectionELF* const *>(a);
1100 const MCSectionELF *secB = *static_cast<const MCSectionELF* const *>(b);
1101 const StringRef &NameA = secA->getSectionName();
1102 const StringRef &NameB = secB->getSectionName();
1103 const unsigned sizeA = NameA.size();
1104 const unsigned sizeB = NameB.size();
1105 const unsigned len = std::min(sizeA, sizeB);
1106 for (unsigned int i = 0; i < len; ++i) {
1107 char ca = NameA[sizeA - i - 1];
1108 char cb = NameB[sizeB - i - 1];
1113 return sizeB - sizeA;
1116 void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
1117 MCAsmLayout &Layout,
1118 SectionIndexMapTy &SectionIndexMap,
1119 const RelMapTy &RelMap) {
1120 MCContext &Ctx = Asm.getContext();
1123 unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
1125 // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
1126 const MCSectionELF *ShstrtabSection =
1127 Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
1128 SectionKind::getReadOnly());
1129 MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
1130 ShstrtabSD.setAlignment(1);
1132 const MCSectionELF *SymtabSection =
1133 Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
1134 SectionKind::getReadOnly(),
1136 MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
1137 SymtabSD.setAlignment(is64Bit() ? 8 : 4);
1139 MCSectionData *SymtabShndxSD = NULL;
1141 if (NeedsSymtabShndx) {
1142 const MCSectionELF *SymtabShndxSection =
1143 Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
1144 SectionKind::getReadOnly(), 4, "");
1145 SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
1146 SymtabShndxSD->setAlignment(4);
1149 const MCSectionELF *StrtabSection;
1150 StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
1151 SectionKind::getReadOnly());
1152 MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
1153 StrtabSD.setAlignment(1);
1155 ComputeIndexMap(Asm, SectionIndexMap, RelMap);
1157 ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection);
1158 SymbolTableIndex = SectionIndexMap.lookup(SymtabSection);
1159 StringTableIndex = SectionIndexMap.lookup(StrtabSection);
1162 F = new MCDataFragment(&SymtabSD);
1163 MCDataFragment *ShndxF = NULL;
1164 if (NeedsSymtabShndx) {
1165 ShndxF = new MCDataFragment(SymtabShndxSD);
1167 WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
1169 F = new MCDataFragment(&StrtabSD);
1170 F->getContents().append(StringTable.begin(), StringTable.end());
1172 F = new MCDataFragment(&ShstrtabSD);
1174 std::vector<const MCSectionELF*> Sections;
1175 for (MCAssembler::const_iterator it = Asm.begin(),
1176 ie = Asm.end(); it != ie; ++it) {
1177 const MCSectionELF &Section =
1178 static_cast<const MCSectionELF&>(it->getSection());
1179 Sections.push_back(&Section);
1181 array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix);
1183 // Section header string table.
1185 // The first entry of a string table holds a null character so skip
1188 F->getContents().push_back('\x00');
1190 for (unsigned int I = 0, E = Sections.size(); I != E; ++I) {
1191 const MCSectionELF &Section = *Sections[I];
1193 StringRef Name = Section.getSectionName();
1195 StringRef PreviousName = Sections[I - 1]->getSectionName();
1196 if (PreviousName.endswith(Name)) {
1197 SectionStringTableIndex[&Section] = Index - Name.size() - 1;
1201 // Remember the index into the string table so we can write it
1202 // into the sh_name field of the section header table.
1203 SectionStringTableIndex[&Section] = Index;
1205 Index += Name.size() + 1;
1206 F->getContents().append(Name.begin(), Name.end());
1207 F->getContents().push_back('\x00');
1211 void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
1212 MCAsmLayout &Layout,
1213 GroupMapTy &GroupMap,
1214 RevGroupMapTy &RevGroupMap,
1215 SectionIndexMapTy &SectionIndexMap,
1216 const RelMapTy &RelMap) {
1217 // Create the .note.GNU-stack section if needed.
1218 MCContext &Ctx = Asm.getContext();
1219 if (Asm.getNoExecStack()) {
1220 const MCSectionELF *GnuStackSection =
1221 Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0,
1222 SectionKind::getReadOnly());
1223 Asm.getOrCreateSectionData(*GnuStackSection);
1227 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1229 const MCSectionELF &Section =
1230 static_cast<const MCSectionELF&>(it->getSection());
1231 if (!(Section.getFlags() & ELF::SHF_GROUP))
1234 const MCSymbol *SignatureSymbol = Section.getGroup();
1235 Asm.getOrCreateSymbolData(*SignatureSymbol);
1236 const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
1238 Group = Ctx.CreateELFGroupSection();
1239 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1240 Data.setAlignment(4);
1241 MCDataFragment *F = new MCDataFragment(&Data);
1242 String32(*F, ELF::GRP_COMDAT);
1244 GroupMap[Group] = SignatureSymbol;
1247 ComputeIndexMap(Asm, SectionIndexMap, RelMap);
1249 // Add sections to the groups
1250 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1252 const MCSectionELF &Section =
1253 static_cast<const MCSectionELF&>(it->getSection());
1254 if (!(Section.getFlags() & ELF::SHF_GROUP))
1256 const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
1257 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1258 // FIXME: we could use the previous fragment
1259 MCDataFragment *F = new MCDataFragment(&Data);
1260 unsigned Index = SectionIndexMap.lookup(&Section);
1261 String32(*F, Index);
1265 void ELFObjectWriter::WriteSection(MCAssembler &Asm,
1266 const SectionIndexMapTy &SectionIndexMap,
1267 uint32_t GroupSymbolIndex,
1268 uint64_t Offset, uint64_t Size,
1270 const MCSectionELF &Section) {
1271 uint64_t sh_link = 0;
1272 uint64_t sh_info = 0;
1274 switch(Section.getType()) {
1275 case ELF::SHT_DYNAMIC:
1276 sh_link = SectionStringTableIndex[&Section];
1281 case ELF::SHT_RELA: {
1282 const MCSectionELF *SymtabSection;
1283 const MCSectionELF *InfoSection;
1284 SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
1286 SectionKind::getReadOnly());
1287 sh_link = SectionIndexMap.lookup(SymtabSection);
1288 assert(sh_link && ".symtab not found");
1290 // Remove ".rel" and ".rela" prefixes.
1291 unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
1292 StringRef SectionName = Section.getSectionName().substr(SecNameLen);
1294 InfoSection = Asm.getContext().getELFSection(SectionName,
1295 ELF::SHT_PROGBITS, 0,
1296 SectionKind::getReadOnly());
1297 sh_info = SectionIndexMap.lookup(InfoSection);
1301 case ELF::SHT_SYMTAB:
1302 case ELF::SHT_DYNSYM:
1303 sh_link = StringTableIndex;
1304 sh_info = LastLocalSymbolIndex;
1307 case ELF::SHT_SYMTAB_SHNDX:
1308 sh_link = SymbolTableIndex;
1311 case ELF::SHT_PROGBITS:
1312 case ELF::SHT_STRTAB:
1313 case ELF::SHT_NOBITS:
1316 case ELF::SHT_ARM_ATTRIBUTES:
1317 case ELF::SHT_INIT_ARRAY:
1318 case ELF::SHT_FINI_ARRAY:
1319 case ELF::SHT_PREINIT_ARRAY:
1320 case ELF::SHT_X86_64_UNWIND:
1321 case ELF::SHT_MIPS_REGINFO:
1322 case ELF::SHT_MIPS_OPTIONS:
1326 case ELF::SHT_GROUP:
1327 sh_link = SymbolTableIndex;
1328 sh_info = GroupSymbolIndex;
1332 assert(0 && "FIXME: sh_type value not supported!");
1336 if (TargetObjectWriter->getEMachine() == ELF::EM_ARM &&
1337 Section.getType() == ELF::SHT_ARM_EXIDX) {
1338 StringRef SecName(Section.getSectionName());
1339 if (SecName == ".ARM.exidx") {
1340 sh_link = SectionIndexMap.lookup(
1341 Asm.getContext().getELFSection(".text",
1343 ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
1344 SectionKind::getText()));
1345 } else if (SecName.startswith(".ARM.exidx")) {
1346 sh_link = SectionIndexMap.lookup(
1347 Asm.getContext().getELFSection(SecName.substr(sizeof(".ARM.exidx") - 1),
1349 ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
1350 SectionKind::getText()));
1354 WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
1355 Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
1356 Alignment, Section.getEntrySize());
1359 bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) {
1360 return SD.getOrdinal() == ~UINT32_C(0) &&
1361 !SD.getSection().isVirtualSection();
1364 uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) {
1366 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1368 const MCFragment &F = *i;
1369 assert(F.getKind() == MCFragment::FT_Data);
1370 Ret += cast<MCDataFragment>(F).getContents().size();
1375 uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout,
1376 const MCSectionData &SD) {
1377 if (IsELFMetaDataSection(SD))
1378 return DataSectionSize(SD);
1379 return Layout.getSectionFileSize(&SD);
1382 uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout,
1383 const MCSectionData &SD) {
1384 if (IsELFMetaDataSection(SD))
1385 return DataSectionSize(SD);
1386 return Layout.getSectionAddressSize(&SD);
1389 void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
1390 const MCAsmLayout &Layout,
1391 const MCSectionELF &Section) {
1392 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1394 uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment());
1395 WriteZeros(Padding);
1397 if (IsELFMetaDataSection(SD)) {
1398 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1400 const MCFragment &F = *i;
1401 assert(F.getKind() == MCFragment::FT_Data);
1402 WriteBytes(cast<MCDataFragment>(F).getContents());
1405 Asm.writeSectionData(&SD, Layout);
1409 void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm,
1410 const GroupMapTy &GroupMap,
1411 const MCAsmLayout &Layout,
1412 const SectionIndexMapTy &SectionIndexMap,
1413 const SectionOffsetMapTy &SectionOffsetMap) {
1414 const unsigned NumSections = Asm.size() + 1;
1416 std::vector<const MCSectionELF*> Sections;
1417 Sections.resize(NumSections - 1);
1419 for (SectionIndexMapTy::const_iterator i=
1420 SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
1421 const std::pair<const MCSectionELF*, uint32_t> &p = *i;
1422 Sections[p.second - 1] = p.first;
1425 // Null section first.
1426 uint64_t FirstSectionSize =
1427 NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
1428 uint32_t FirstSectionLink =
1429 ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
1430 WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
1432 for (unsigned i = 0; i < NumSections - 1; ++i) {
1433 const MCSectionELF &Section = *Sections[i];
1434 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1435 uint32_t GroupSymbolIndex;
1436 if (Section.getType() != ELF::SHT_GROUP)
1437 GroupSymbolIndex = 0;
1439 GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm,
1440 GroupMap.lookup(&Section));
1442 uint64_t Size = GetSectionAddressSize(Layout, SD);
1444 WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
1445 SectionOffsetMap.lookup(&Section), Size,
1446 SD.getAlignment(), Section);
1450 void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm,
1451 std::vector<const MCSectionELF*> &Sections) {
1452 for (MCAssembler::iterator it = Asm.begin(),
1453 ie = Asm.end(); it != ie; ++it) {
1454 const MCSectionELF &Section =
1455 static_cast<const MCSectionELF &>(it->getSection());
1456 if (Section.getType() == ELF::SHT_GROUP)
1457 Sections.push_back(&Section);
1460 for (MCAssembler::iterator it = Asm.begin(),
1461 ie = Asm.end(); it != ie; ++it) {
1462 const MCSectionELF &Section =
1463 static_cast<const MCSectionELF &>(it->getSection());
1464 if (Section.getType() != ELF::SHT_GROUP &&
1465 Section.getType() != ELF::SHT_REL &&
1466 Section.getType() != ELF::SHT_RELA)
1467 Sections.push_back(&Section);
1470 for (MCAssembler::iterator it = Asm.begin(),
1471 ie = Asm.end(); it != ie; ++it) {
1472 const MCSectionELF &Section =
1473 static_cast<const MCSectionELF &>(it->getSection());
1474 if (Section.getType() == ELF::SHT_REL ||
1475 Section.getType() == ELF::SHT_RELA)
1476 Sections.push_back(&Section);
1480 void ELFObjectWriter::WriteObject(MCAssembler &Asm,
1481 const MCAsmLayout &Layout) {
1482 GroupMapTy GroupMap;
1483 RevGroupMapTy RevGroupMap;
1484 SectionIndexMapTy SectionIndexMap;
1486 unsigned NumUserSections = Asm.size();
1488 DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
1489 CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
1491 const unsigned NumUserAndRelocSections = Asm.size();
1492 CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
1493 RevGroupMap, SectionIndexMap, RelMap);
1494 const unsigned AllSections = Asm.size();
1495 const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
1497 unsigned NumRegularSections = NumUserSections + NumIndexedSections;
1499 // Compute symbol table information.
1500 ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap, NumRegularSections);
1503 WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
1505 CreateMetadataSections(const_cast<MCAssembler&>(Asm),
1506 const_cast<MCAsmLayout&>(Layout),
1510 uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
1511 uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
1512 sizeof(ELF::Elf32_Ehdr);
1513 uint64_t FileOff = HeaderSize;
1515 std::vector<const MCSectionELF*> Sections;
1516 ComputeSectionOrder(Asm, Sections);
1517 unsigned NumSections = Sections.size();
1518 SectionOffsetMapTy SectionOffsetMap;
1519 for (unsigned i = 0; i < NumRegularSections + 1; ++i) {
1520 const MCSectionELF &Section = *Sections[i];
1521 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1523 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1525 // Remember the offset into the file for this section.
1526 SectionOffsetMap[&Section] = FileOff;
1528 // Get the size of the section in the output file (including padding).
1529 FileOff += GetSectionFileSize(Layout, SD);
1532 FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
1534 const unsigned SectionHeaderOffset = FileOff - HeaderSize;
1536 uint64_t SectionHeaderEntrySize = is64Bit() ?
1537 sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr);
1538 FileOff += (NumSections + 1) * SectionHeaderEntrySize;
1540 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) {
1541 const MCSectionELF &Section = *Sections[i];
1542 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1544 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1546 // Remember the offset into the file for this section.
1547 SectionOffsetMap[&Section] = FileOff;
1549 // Get the size of the section in the output file (including padding).
1550 FileOff += GetSectionFileSize(Layout, SD);
1553 // Write out the ELF header ...
1554 WriteHeader(Asm, SectionHeaderOffset, NumSections + 1);
1556 // ... then the regular sections ...
1557 // + because of .shstrtab
1558 for (unsigned i = 0; i < NumRegularSections + 1; ++i)
1559 WriteDataSectionData(Asm, Layout, *Sections[i]);
1561 uint64_t Padding = OffsetToAlignment(OS.tell(), NaturalAlignment);
1562 WriteZeros(Padding);
1564 // ... then the section header table ...
1565 WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap,
1568 // ... and then the remaining sections ...
1569 for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)
1570 WriteDataSectionData(Asm, Layout, *Sections[i]);
1574 ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
1575 const MCSymbolData &DataA,
1576 const MCFragment &FB,
1578 bool IsPCRel) const {
1579 if (DataA.getFlags() & ELF_STB_Weak)
1581 return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
1582 Asm, DataA, FB,InSet, IsPCRel);
1585 MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
1587 bool IsLittleEndian) {
1588 return new ELFObjectWriter(MOTW, OS, IsLittleEndian);