diff options
Diffstat (limited to 'llvm/lib/MC/ELFObjectWriter.cpp')
| -rw-r--r-- | llvm/lib/MC/ELFObjectWriter.cpp | 236 |
1 files changed, 93 insertions, 143 deletions
diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp index ae57f9521e0..725461d76c6 100644 --- a/llvm/lib/MC/ELFObjectWriter.cpp +++ b/llvm/lib/MC/ELFObjectWriter.cpp @@ -78,10 +78,6 @@ class ELFObjectWriter : public MCObjectWriter { static bool isInSymtab(const MCAsmLayout &Layout, const MCSymbolData &Data, bool Used, bool Renamed); static bool isLocal(const MCSymbolData &Data, bool isUsedInReloc); - static bool IsELFMetaDataSection(const MCSectionData &SD); - - void writeDataSectionData(MCAssembler &Asm, const MCAsmLayout &Layout, - const MCSectionData &SD); /// Helper struct for containing some precomputed information on symbols. struct ELFSymbolData { @@ -193,7 +189,8 @@ class ELFObjectWriter : public MCObjectWriter { const MCAsmLayout &Layout); // Start and end offset of each section - typedef std::vector<std::pair<uint64_t, uint64_t>> SectionOffsetsTy; + typedef std::map<const MCSectionELF *, std::pair<uint64_t, uint64_t>> + SectionOffsetsTy; void WriteSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, std::vector<const MCSectionELF *> &Sections, @@ -224,32 +221,17 @@ class ELFObjectWriter : public MCObjectWriter { const SectionIndexMapTy &SectionIndexMap, const RevGroupMapTy &RevGroupMap); - void maybeAddToGroup(MCAssembler &Asm, - ArrayRef<const MCSectionELF *> Sections, - const RevGroupMapTy &RevGroupMap, - const MCSectionELF &Section, unsigned Index); - - void computeIndexMap(MCAssembler &Asm, - std::vector<const MCSectionELF *> &Sections, - SectionIndexMapTy &SectionIndexMap, - const RevGroupMapTy &RevGroupMap); - - void createRelocationSection(MCAssembler &Asm, const MCSectionELF &Sec); + const MCSectionELF *createRelocationSection(MCAssembler &Asm, + const MCSectionELF &Sec); void CompressDebugSections(MCAssembler &Asm, MCAsmLayout &Layout); - void + const MCSectionELF * createSectionHeaderStringTable(MCAssembler &Asm, std::vector<const MCSectionELF *> &Sections); - void createStringTable(MCAssembler &Asm, - std::vector<const MCSectionELF *> &Sections); - - // Create the sections that show up in the symbol table. Currently - // those are the .note.GNU-stack section and the group sections. - void createIndexedSections(MCAssembler &Asm, const MCAsmLayout &Layout, - RevGroupMapTy &RevGroupMap, - std::vector<const MCSectionELF *> &Sections, - SectionIndexMapTy &SectionIndexMap); + const MCSectionELF * + createStringTable(MCAssembler &Asm, + std::vector<const MCSectionELF *> &Sections); void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout) override; @@ -628,7 +610,7 @@ void ELFObjectWriter::WriteSymbolTable( } uint64_t SecEnd = OS.tell(); - SectionOffsets.push_back(std::make_pair(SecStart, SecEnd)); + SectionOffsets[SymtabSection] = std::make_pair(SecStart, SecEnd); ArrayRef<uint32_t> ShndxIndexes = Writer.getShndxIndexes(); if (ShndxIndexes.empty()) @@ -644,7 +626,7 @@ void ELFObjectWriter::WriteSymbolTable( for (uint32_t Index : ShndxIndexes) write(Index); SecEnd = OS.tell(); - SectionOffsets.push_back(std::make_pair(SecStart, SecEnd)); + SectionOffsets[SymtabShndxSection] = std::make_pair(SecStart, SecEnd); } // It is always valid to create a relocation with a symbol. It is preferable @@ -948,37 +930,6 @@ bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isUsedInReloc) { return true; } -void ELFObjectWriter::maybeAddToGroup(MCAssembler &Asm, - ArrayRef<const MCSectionELF *> Sections, - const RevGroupMapTy &RevGroupMap, - const MCSectionELF &Section, - unsigned Index) { - const MCSymbol *Sym = Section.getGroup(); - if (!Sym) - return; - const MCSectionELF *Group = Sections[RevGroupMap.lookup(Sym) - 1]; - MCSectionData &Data = Asm.getOrCreateSectionData(*Group); - // FIXME: we could use the previous fragment - MCDataFragment *F = new MCDataFragment(&Data); - write(*F, Index); -} - -void ELFObjectWriter::computeIndexMap( - MCAssembler &Asm, std::vector<const MCSectionELF *> &Sections, - SectionIndexMapTy &SectionIndexMap, const RevGroupMapTy &RevGroupMap) { - for (const MCSectionData &SD : Asm) { - const MCSectionELF &Section = - static_cast<const MCSectionELF &>(SD.getSection()); - if (Section.getType() == ELF::SHT_GROUP) - continue; - Sections.push_back(&Section); - unsigned Index = Sections.size(); - SectionIndexMap[&Section] = Index; - maybeAddToGroup(Asm, Sections, RevGroupMap, Section, Index); - createRelocationSection(Asm, Section); - } -} - void ELFObjectWriter::computeSymbolTable( MCAssembler &Asm, const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap, @@ -1124,10 +1075,11 @@ void ELFObjectWriter::computeSymbolTable( UndefinedSymbolData[i].SymbolData->setIndex(Index++); } -void ELFObjectWriter::createRelocationSection(MCAssembler &Asm, - const MCSectionELF &Sec) { +const MCSectionELF * +ELFObjectWriter::createRelocationSection(MCAssembler &Asm, + const MCSectionELF &Sec) { if (Relocations[&Sec].empty()) - return; + return nullptr; MCContext &Ctx = Asm.getContext(); const StringRef SectionName = Sec.getSectionName(); @@ -1149,6 +1101,7 @@ void ELFObjectWriter::createRelocationSection(MCAssembler &Asm, Flags, EntrySize, Sec.getGroup(), &Sec); MCSectionData &RelSD = Asm.getOrCreateSectionData(*RelaSection); RelSD.setAlignment(is64Bit() ? 8 : 4); + return RelaSection; } static SmallVector<char, 128> @@ -1356,7 +1309,7 @@ void ELFObjectWriter::writeRelocations(const MCAssembler &Asm, } } -void ELFObjectWriter::createSectionHeaderStringTable( +const MCSectionELF *ELFObjectWriter::createSectionHeaderStringTable( MCAssembler &Asm, std::vector<const MCSectionELF *> &Sections) { const MCSectionELF *ShstrtabSection = Sections[ShstrtabIndex - 1]; @@ -1369,9 +1322,10 @@ void ELFObjectWriter::createSectionHeaderStringTable( } ShStrTabBuilder.finalize(StringTableBuilder::ELF); OS << ShStrTabBuilder.data(); + return ShstrtabSection; } -void ELFObjectWriter::createStringTable( +const MCSectionELF *ELFObjectWriter::createStringTable( MCAssembler &Asm, std::vector<const MCSectionELF *> &Sections) { MCContext &Ctx = Asm.getContext(); const MCSectionELF *StrtabSection = @@ -1380,43 +1334,7 @@ void ELFObjectWriter::createStringTable( Sections.push_back(StrtabSection); StringTableIndex = Sections.size(); OS << StrTabBuilder.data(); -} - -void ELFObjectWriter::createIndexedSections( - MCAssembler &Asm, const MCAsmLayout &Layout, RevGroupMapTy &RevGroupMap, - std::vector<const MCSectionELF *> &Sections, - SectionIndexMapTy &SectionIndexMap) { - MCContext &Ctx = Asm.getContext(); - - const MCSectionELF *ShstrtabSection = - Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0); - Sections.push_back(ShstrtabSection); - ShstrtabIndex = Sections.size(); - assert(ShstrtabIndex == 1); - - // Build the groups - for (const MCSectionData &SD : Asm) { - const MCSectionELF &Section = - static_cast<const MCSectionELF &>(SD.getSection()); - if (!(Section.getFlags() & ELF::SHF_GROUP)) - continue; - - const MCSymbol *SignatureSymbol = Section.getGroup(); - Asm.getOrCreateSymbolData(*SignatureSymbol); - unsigned &GroupIdx = RevGroupMap[SignatureSymbol]; - if (!GroupIdx) { - const MCSectionELF *Group = Ctx.createELFGroupSection(SignatureSymbol); - Sections.push_back(Group); - GroupIdx = Sections.size(); - - MCSectionData &Data = Asm.getOrCreateSectionData(*Group); - Data.setAlignment(4); - MCDataFragment *F = new MCDataFragment(&Data); - write(*F, uint32_t(ELF::GRP_COMDAT)); - } - } - - computeIndexMap(Asm, Sections, SectionIndexMap, RevGroupMap); + return StrtabSection; } void ELFObjectWriter::writeSection(MCAssembler &Asm, @@ -1472,26 +1390,6 @@ void ELFObjectWriter::writeSection(MCAssembler &Asm, Alignment, Section.getEntrySize()); } -bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) { - return SD.getOrdinal() == ~UINT32_C(0) && - !SD.getSection().isVirtualSection(); -} - -void ELFObjectWriter::writeDataSectionData(MCAssembler &Asm, - const MCAsmLayout &Layout, - const MCSectionData &SD) { - if (IsELFMetaDataSection(SD)) { - for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e; - ++i) { - const MCFragment &F = *i; - assert(F.getKind() == MCFragment::FT_Data); - WriteBytes(cast<MCDataFragment>(F).getContents()); - } - } else { - Asm.writeSectionData(&SD, Layout); - } -} - void ELFObjectWriter::writeSectionHeader( ArrayRef<const MCSectionELF *> Sections, MCAssembler &Asm, const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap, @@ -1512,7 +1410,8 @@ void ELFObjectWriter::writeSectionHeader( else GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, Section.getGroup()); - const std::pair<uint64_t, uint64_t> &Offsets = SectionOffsets[i]; + const std::pair<uint64_t, uint64_t> &Offsets = + SectionOffsets.find(&Section)->second; uint64_t Size = Section.getType() == ELF::SHT_NOBITS ? Layout.getSectionAddressSize(&SD) : Offsets.second - Offsets.first; @@ -1524,56 +1423,107 @@ void ELFObjectWriter::writeSectionHeader( void ELFObjectWriter::WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) { - RevGroupMapTy RevGroupMap; - SectionIndexMapTy SectionIndexMap; - CompressDebugSections(Asm, const_cast<MCAsmLayout &>(Layout)); + std::vector<const MCSectionELF *> Sections; - createIndexedSections(Asm, Layout, RevGroupMap, Sections, SectionIndexMap); + MCContext &Ctx = Asm.getContext(); + const MCSectionELF *ShstrtabSection = + Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0); + Sections.push_back(ShstrtabSection); + ShstrtabIndex = Sections.size(); - // Compute symbol table information. - computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap); + RevGroupMapTy RevGroupMap; + SectionIndexMapTy SectionIndexMap; - SectionOffsetsTy SectionOffsets; + std::map<const MCSymbol *, std::vector<const MCSectionELF *>> GroupMembers; // Write out the ELF header ... writeHeader(Asm); // ... then the sections ... - SectionOffsets.push_back(std::make_pair(0, 0)); - for (auto I = ++Sections.begin(), E = Sections.end(); I != E; ++I) { - const MCSectionELF &Sec = **I; - const MCSectionData &SD = Asm.getOrCreateSectionData(Sec); + SectionOffsetsTy SectionOffsets; + bool ComputedSymtab = false; + for (const MCSectionData &SD : Asm) { + const MCSectionELF &Section = + static_cast<const MCSectionELF &>(SD.getSection()); + uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment()); WriteZeros(Padding); // Remember the offset into the file for this section. uint64_t SecStart = OS.tell(); - unsigned Type = Sec.getType(); - if (Type != ELF::SHT_REL && Type != ELF::SHT_RELA) - writeDataSectionData(Asm, Layout, SD); - else - writeRelocations(Asm, *Sec.getAssociatedSection()); + const MCSymbol *SignatureSymbol = Section.getGroup(); + unsigned Type = Section.getType(); + if (Type == ELF::SHT_GROUP) { + assert(SignatureSymbol); + write(uint32_t(ELF::GRP_COMDAT)); + for (const MCSectionELF *Member : GroupMembers[SignatureSymbol]) { + uint32_t SecIndex = SectionIndexMap.lookup(Member); + write(SecIndex); + } + } else if (Type == ELF::SHT_REL || Type == ELF::SHT_RELA) { + if (!ComputedSymtab) { + // Compute symbol table information. + computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap); + ComputedSymtab = true; + } + writeRelocations(Asm, *Section.getAssociatedSection()); + } else { + Asm.writeSectionData(&SD, Layout); + } uint64_t SecEnd = OS.tell(); - SectionOffsets.push_back(std::make_pair(SecStart, SecEnd)); + SectionOffsets[&Section] = std::make_pair(SecStart, SecEnd); + + if (Type == ELF::SHT_GROUP || Type == ELF::SHT_REL || Type == ELF::SHT_RELA) + continue; + + const MCSectionELF *RelSection = createRelocationSection(Asm, Section); + + if (SignatureSymbol) { + Asm.getOrCreateSymbolData(*SignatureSymbol); + unsigned &GroupIdx = RevGroupMap[SignatureSymbol]; + if (!GroupIdx) { + const MCSectionELF *Group = Ctx.createELFGroupSection(SignatureSymbol); + Sections.push_back(Group); + GroupIdx = Sections.size(); + MCSectionData *GroupD = &Asm.getOrCreateSectionData(*Group); + GroupD->setAlignment(4); + } + GroupMembers[SignatureSymbol].push_back(&Section); + if (RelSection) + GroupMembers[SignatureSymbol].push_back(RelSection); + } + + Sections.push_back(&Section); + SectionIndexMap[&Section] = Sections.size(); + if (RelSection) { + Sections.push_back(RelSection); + SectionIndexMap[RelSection] = Sections.size(); + } + } + + if (!ComputedSymtab) { + // Compute symbol table information. + computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap); + ComputedSymtab = true; } WriteSymbolTable(Asm, Layout, Sections, SectionOffsets); { uint64_t SecStart = OS.tell(); - createStringTable(Asm, Sections); + const MCSectionELF *Sec = createStringTable(Asm, Sections); uint64_t SecEnd = OS.tell(); - SectionOffsets.push_back(std::make_pair(SecStart, SecEnd)); + SectionOffsets[Sec] = std::make_pair(SecStart, SecEnd); } { uint64_t SecStart = OS.tell(); - createSectionHeaderStringTable(Asm, Sections); + const MCSectionELF *Sec = createSectionHeaderStringTable(Asm, Sections); uint64_t SecEnd = OS.tell(); - SectionOffsets[0] = std::make_pair(SecStart, SecEnd); + SectionOffsets[Sec] = std::make_pair(SecStart, SecEnd); } uint64_t NaturalAlignment = is64Bit() ? 8 : 4; |
