diff options
Diffstat (limited to 'tools/llvm-objcopy/Object.cpp')
| -rw-r--r-- | tools/llvm-objcopy/Object.cpp | 1125 |
1 files changed, 790 insertions, 335 deletions
diff --git a/tools/llvm-objcopy/Object.cpp b/tools/llvm-objcopy/Object.cpp index d5dfcac40e4e..7e88f5263a39 100644 --- a/tools/llvm-objcopy/Object.cpp +++ b/tools/llvm-objcopy/Object.cpp @@ -18,6 +18,7 @@ #include "llvm/Object/ELFObjectFile.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/FileOutputBuffer.h" +#include "llvm/Support/Path.h" #include <algorithm> #include <cstddef> #include <cstdint> @@ -26,64 +27,117 @@ #include <vector> using namespace llvm; +using namespace llvm::objcopy; using namespace object; using namespace ELF; -template <class ELFT> void Segment::writeHeader(FileOutputBuffer &Out) const { - using Elf_Ehdr = typename ELFT::Ehdr; - using Elf_Phdr = typename ELFT::Phdr; +Buffer::~Buffer() {} - uint8_t *Buf = Out.getBufferStart(); - Buf += sizeof(Elf_Ehdr) + Index * sizeof(Elf_Phdr); - Elf_Phdr &Phdr = *reinterpret_cast<Elf_Phdr *>(Buf); - Phdr.p_type = Type; - Phdr.p_flags = Flags; - Phdr.p_offset = Offset; - Phdr.p_vaddr = VAddr; - Phdr.p_paddr = PAddr; - Phdr.p_filesz = FileSize; - Phdr.p_memsz = MemSize; - Phdr.p_align = Align; +void FileBuffer::allocate(size_t Size) { + Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr = + FileOutputBuffer::create(getName(), Size, FileOutputBuffer::F_executable); + handleAllErrors(BufferOrErr.takeError(), [this](const ErrorInfoBase &E) { + error("failed to open " + getName() + ": " + E.message()); + }); + Buf = std::move(*BufferOrErr); +} + +Error FileBuffer::commit() { return Buf->commit(); } + +uint8_t *FileBuffer::getBufferStart() { + return reinterpret_cast<uint8_t *>(Buf->getBufferStart()); } -void Segment::writeSegment(FileOutputBuffer &Out) const { - uint8_t *Buf = Out.getBufferStart() + Offset; - // We want to maintain segments' interstitial data and contents exactly. - // This lets us just copy segments directly. - std::copy(std::begin(Contents), std::end(Contents), Buf); +void MemBuffer::allocate(size_t Size) { + Buf = WritableMemoryBuffer::getNewMemBuffer(Size, getName()); +} + +Error MemBuffer::commit() { return Error::success(); } + +uint8_t *MemBuffer::getBufferStart() { + return reinterpret_cast<uint8_t *>(Buf->getBufferStart()); +} + +std::unique_ptr<WritableMemoryBuffer> MemBuffer::releaseMemoryBuffer() { + return std::move(Buf); +} + +template <class ELFT> void ELFWriter<ELFT>::writePhdr(const Segment &Seg) { + using Elf_Phdr = typename ELFT::Phdr; + + uint8_t *B = Buf.getBufferStart(); + B += Obj.ProgramHdrSegment.Offset + Seg.Index * sizeof(Elf_Phdr); + Elf_Phdr &Phdr = *reinterpret_cast<Elf_Phdr *>(B); + Phdr.p_type = Seg.Type; + Phdr.p_flags = Seg.Flags; + Phdr.p_offset = Seg.Offset; + Phdr.p_vaddr = Seg.VAddr; + Phdr.p_paddr = Seg.PAddr; + Phdr.p_filesz = Seg.FileSize; + Phdr.p_memsz = Seg.MemSize; + Phdr.p_align = Seg.Align; } void SectionBase::removeSectionReferences(const SectionBase *Sec) {} +void SectionBase::removeSymbols(function_ref<bool(const Symbol &)> ToRemove) {} void SectionBase::initialize(SectionTableRef SecTable) {} void SectionBase::finalize() {} +void SectionBase::markSymbols() {} + +template <class ELFT> void ELFWriter<ELFT>::writeShdr(const SectionBase &Sec) { + uint8_t *B = Buf.getBufferStart(); + B += Sec.HeaderOffset; + typename ELFT::Shdr &Shdr = *reinterpret_cast<typename ELFT::Shdr *>(B); + Shdr.sh_name = Sec.NameIndex; + Shdr.sh_type = Sec.Type; + Shdr.sh_flags = Sec.Flags; + Shdr.sh_addr = Sec.Addr; + Shdr.sh_offset = Sec.Offset; + Shdr.sh_size = Sec.Size; + Shdr.sh_link = Sec.Link; + Shdr.sh_info = Sec.Info; + Shdr.sh_addralign = Sec.Align; + Shdr.sh_entsize = Sec.EntrySize; +} -template <class ELFT> -void SectionBase::writeHeader(FileOutputBuffer &Out) const { - uint8_t *Buf = Out.getBufferStart(); - Buf += HeaderOffset; - typename ELFT::Shdr &Shdr = *reinterpret_cast<typename ELFT::Shdr *>(Buf); - Shdr.sh_name = NameIndex; - Shdr.sh_type = Type; - Shdr.sh_flags = Flags; - Shdr.sh_addr = Addr; - Shdr.sh_offset = Offset; - Shdr.sh_size = Size; - Shdr.sh_link = Link; - Shdr.sh_info = Info; - Shdr.sh_addralign = Align; - Shdr.sh_entsize = EntrySize; -} - -void Section::writeSection(FileOutputBuffer &Out) const { - if (Type == SHT_NOBITS) +SectionVisitor::~SectionVisitor() {} + +void BinarySectionWriter::visit(const SectionIndexSection &Sec) { + error("Cannot write symbol section index table '" + Sec.Name + "' "); +} + +void BinarySectionWriter::visit(const SymbolTableSection &Sec) { + error("Cannot write symbol table '" + Sec.Name + "' out to binary"); +} + +void BinarySectionWriter::visit(const RelocationSection &Sec) { + error("Cannot write relocation section '" + Sec.Name + "' out to binary"); +} + +void BinarySectionWriter::visit(const GnuDebugLinkSection &Sec) { + error("Cannot write '" + Sec.Name + "' out to binary"); +} + +void BinarySectionWriter::visit(const GroupSection &Sec) { + error("Cannot write '" + Sec.Name + "' out to binary"); +} + +void SectionWriter::visit(const Section &Sec) { + if (Sec.Type == SHT_NOBITS) return; - uint8_t *Buf = Out.getBufferStart() + Offset; - std::copy(std::begin(Contents), std::end(Contents), Buf); + uint8_t *Buf = Out.getBufferStart() + Sec.Offset; + std::copy(std::begin(Sec.Contents), std::end(Sec.Contents), Buf); } -void OwnedDataSection::writeSection(FileOutputBuffer &Out) const { - uint8_t *Buf = Out.getBufferStart() + Offset; - std::copy(std::begin(Data), std::end(Data), Buf); +void Section::accept(SectionVisitor &Visitor) const { Visitor.visit(*this); } + +void SectionWriter::visit(const OwnedDataSection &Sec) { + uint8_t *Buf = Out.getBufferStart() + Sec.Offset; + std::copy(std::begin(Sec.Data), std::end(Sec.Data), Buf); +} + +void OwnedDataSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); } void StringTableSection::addString(StringRef Name) { @@ -97,8 +151,35 @@ uint32_t StringTableSection::findIndex(StringRef Name) const { void StringTableSection::finalize() { StrTabBuilder.finalize(); } -void StringTableSection::writeSection(FileOutputBuffer &Out) const { - StrTabBuilder.write(Out.getBufferStart() + Offset); +void SectionWriter::visit(const StringTableSection &Sec) { + Sec.StrTabBuilder.write(Out.getBufferStart() + Sec.Offset); +} + +void StringTableSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); +} + +template <class ELFT> +void ELFSectionWriter<ELFT>::visit(const SectionIndexSection &Sec) { + uint8_t *Buf = Out.getBufferStart() + Sec.Offset; + auto *IndexesBuffer = reinterpret_cast<typename ELFT::Word *>(Buf); + std::copy(std::begin(Sec.Indexes), std::end(Sec.Indexes), IndexesBuffer); +} + +void SectionIndexSection::initialize(SectionTableRef SecTable) { + Size = 0; + setSymTab(SecTable.getSectionOfType<SymbolTableSection>( + Link, + "Link field value " + Twine(Link) + " in section " + Name + " is invalid", + "Link field value " + Twine(Link) + " in section " + Name + + " is not a symbol table")); + Symbols->setShndxTable(this); +} + +void SectionIndexSection::finalize() { Link = Symbols->Index; } + +void SectionIndexSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); } static bool isValidReservedSectionIndex(uint16_t Index, uint16_t Machine) { @@ -119,8 +200,13 @@ static bool isValidReservedSectionIndex(uint16_t Index, uint16_t Machine) { return false; } +// Large indexes force us to clarify exactly what this function should do. This +// function should return the value that will appear in st_shndx when written +// out. uint16_t Symbol::getShndx() const { if (DefinedIn != nullptr) { + if (DefinedIn->Index >= SHN_LORESERVE) + return SHN_XINDEX; return DefinedIn->Index; } switch (ShndxType) { @@ -134,19 +220,29 @@ uint16_t Symbol::getShndx() const { case SYMBOL_HEXAGON_SCOMMON_2: case SYMBOL_HEXAGON_SCOMMON_4: case SYMBOL_HEXAGON_SCOMMON_8: + case SYMBOL_XINDEX: return static_cast<uint16_t>(ShndxType); } llvm_unreachable("Symbol with invalid ShndxType encountered"); } +void SymbolTableSection::assignIndices() { + uint32_t Index = 0; + for (auto &Sym : Symbols) + Sym->Index = Index++; +} + void SymbolTableSection::addSymbol(StringRef Name, uint8_t Bind, uint8_t Type, SectionBase *DefinedIn, uint64_t Value, - uint16_t Shndx, uint64_t Sz) { + uint8_t Visibility, uint16_t Shndx, + uint64_t Sz) { Symbol Sym; Sym.Name = Name; Sym.Binding = Bind; Sym.Type = Type; Sym.DefinedIn = DefinedIn; + if (DefinedIn != nullptr) + DefinedIn->HasSymbol = true; if (DefinedIn == nullptr) { if (Shndx >= SHN_LORESERVE) Sym.ShndxType = static_cast<SymbolShndxType>(Shndx); @@ -154,6 +250,7 @@ void SymbolTableSection::addSymbol(StringRef Name, uint8_t Bind, uint8_t Type, Sym.ShndxType = SYMBOL_SIMPLE_INDEX; } Sym.Value = Value; + Sym.Visibility = Visibility; Sym.Size = Sz; Sym.Index = Symbols.size(); Symbols.emplace_back(llvm::make_unique<Symbol>(Sym)); @@ -161,16 +258,33 @@ void SymbolTableSection::addSymbol(StringRef Name, uint8_t Bind, uint8_t Type, } void SymbolTableSection::removeSectionReferences(const SectionBase *Sec) { + if (SectionIndexTable == Sec) + SectionIndexTable = nullptr; if (SymbolNames == Sec) { error("String table " + SymbolNames->Name + " cannot be removed because it is referenced by the symbol table " + this->Name); } - auto Iter = - std::remove_if(std::begin(Symbols), std::end(Symbols), - [=](const SymPtr &Sym) { return Sym->DefinedIn == Sec; }); - Size -= (std::end(Symbols) - Iter) * this->EntrySize; - Symbols.erase(Iter, std::end(Symbols)); + removeSymbols([Sec](const Symbol &Sym) { return Sym.DefinedIn == Sec; }); +} + +void SymbolTableSection::updateSymbols(function_ref<void(Symbol &)> Callable) { + std::for_each(std::begin(Symbols) + 1, std::end(Symbols), + [Callable](SymPtr &Sym) { Callable(*Sym); }); + std::stable_partition( + std::begin(Symbols), std::end(Symbols), + [](const SymPtr &Sym) { return Sym->Binding == STB_LOCAL; }); + assignIndices(); +} + +void SymbolTableSection::removeSymbols( + function_ref<bool(const Symbol &)> ToRemove) { + Symbols.erase( + std::remove_if(std::begin(Symbols) + 1, std::end(Symbols), + [ToRemove](const SymPtr &Sym) { return ToRemove(*Sym); }), + std::end(Symbols)); + Size = Symbols.size() * EntrySize; + assignIndices(); } void SymbolTableSection::initialize(SectionTableRef SecTable) { @@ -198,7 +312,17 @@ void SymbolTableSection::finalize() { Info = MaxLocalIndex + 1; } -void SymbolTableSection::addSymbolNames() { +void SymbolTableSection::prepareForLayout() { + // Add all potential section indexes before file layout so that the section + // index section has the approprite size. + if (SectionIndexTable != nullptr) { + for (const auto &Sym : Symbols) { + if (Sym->DefinedIn != nullptr && Sym->DefinedIn->Index >= SHN_LORESERVE) + SectionIndexTable->addIndex(Sym->DefinedIn->Index); + else + SectionIndexTable->addIndex(SHN_UNDEF); + } + } // Add all of our strings to SymbolNames so that SymbolNames has the right // size before layout is decided. for (auto &Sym : Symbols) @@ -211,16 +335,22 @@ const Symbol *SymbolTableSection::getSymbolByIndex(uint32_t Index) const { return Symbols[Index].get(); } +Symbol *SymbolTableSection::getSymbolByIndex(uint32_t Index) { + return const_cast<Symbol *>( + static_cast<const SymbolTableSection *>(this)->getSymbolByIndex(Index)); +} + template <class ELFT> -void SymbolTableSectionImpl<ELFT>::writeSection(FileOutputBuffer &Out) const { +void ELFSectionWriter<ELFT>::visit(const SymbolTableSection &Sec) { uint8_t *Buf = Out.getBufferStart(); - Buf += Offset; + Buf += Sec.Offset; typename ELFT::Sym *Sym = reinterpret_cast<typename ELFT::Sym *>(Buf); // Loop though symbols setting each entry of the symbol table. - for (auto &Symbol : Symbols) { + for (auto &Symbol : Sec.Symbols) { Sym->st_name = Symbol->NameIndex; Sym->st_value = Symbol->Value; Sym->st_size = Symbol->Size; + Sym->st_other = Symbol->Visibility; Sym->setBinding(Symbol->Binding); Sym->setType(Symbol->Type); Sym->st_shndx = Symbol->getShndx(); @@ -228,13 +358,18 @@ void SymbolTableSectionImpl<ELFT>::writeSection(FileOutputBuffer &Out) const { } } +void SymbolTableSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); +} + template <class SymTabType> void RelocSectionWithSymtabBase<SymTabType>::removeSectionReferences( const SectionBase *Sec) { if (Symbols == Sec) { - error("Symbol table " + Symbols->Name + " cannot be removed because it is " - "referenced by the relocation " - "section " + + error("Symbol table " + Symbols->Name + + " cannot be removed because it is " + "referenced by the relocation " + "section " + this->Name); } } @@ -249,9 +384,9 @@ void RelocSectionWithSymtabBase<SymTabType>::initialize( " is not a symbol table")); if (Info != SHN_UNDEF) - setSection(SecTable.getSection(Info, - "Info field value " + Twine(Info) + - " in section " + Name + " is invalid")); + setSection(SecTable.getSection(Info, "Info field value " + Twine(Info) + + " in section " + Name + + " is invalid")); else setSection(nullptr); } @@ -264,16 +399,15 @@ void RelocSectionWithSymtabBase<SymTabType>::finalize() { } template <class ELFT> -void setAddend(Elf_Rel_Impl<ELFT, false> &Rel, uint64_t Addend) {} +static void setAddend(Elf_Rel_Impl<ELFT, false> &Rel, uint64_t Addend) {} template <class ELFT> -void setAddend(Elf_Rel_Impl<ELFT, true> &Rela, uint64_t Addend) { +static void setAddend(Elf_Rel_Impl<ELFT, true> &Rela, uint64_t Addend) { Rela.r_addend = Addend; } -template <class ELFT> -template <class T> -void RelocationSection<ELFT>::writeRel(T *Buf) const { +template <class RelRange, class T> +static void writeRel(const RelRange &Relocations, T *Buf) { for (const auto &Reloc : Relocations) { Buf->r_offset = Reloc.Offset; setAddend(*Buf, Reloc.Addend); @@ -283,43 +417,138 @@ void RelocationSection<ELFT>::writeRel(T *Buf) const { } template <class ELFT> -void RelocationSection<ELFT>::writeSection(FileOutputBuffer &Out) const { - uint8_t *Buf = Out.getBufferStart() + Offset; - if (Type == SHT_REL) - writeRel(reinterpret_cast<Elf_Rel *>(Buf)); +void ELFSectionWriter<ELFT>::visit(const RelocationSection &Sec) { + uint8_t *Buf = Out.getBufferStart() + Sec.Offset; + if (Sec.Type == SHT_REL) + writeRel(Sec.Relocations, reinterpret_cast<Elf_Rel *>(Buf)); else - writeRel(reinterpret_cast<Elf_Rela *>(Buf)); + writeRel(Sec.Relocations, reinterpret_cast<Elf_Rela *>(Buf)); } -void DynamicRelocationSection::writeSection(FileOutputBuffer &Out) const { - std::copy(std::begin(Contents), std::end(Contents), - Out.getBufferStart() + Offset); +void RelocationSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); } -void SectionWithStrTab::removeSectionReferences(const SectionBase *Sec) { - if (StrTab == Sec) { - error("String table " + StrTab->Name + " cannot be removed because it is " - "referenced by the section " + +void RelocationSection::removeSymbols( + function_ref<bool(const Symbol &)> ToRemove) { + for (const Relocation &Reloc : Relocations) + if (ToRemove(*Reloc.RelocSymbol)) + error("not stripping symbol `" + Reloc.RelocSymbol->Name + + "' because it is named in a relocation"); +} + +void RelocationSection::markSymbols() { + for (const Relocation &Reloc : Relocations) + Reloc.RelocSymbol->Referenced = true; +} + +void SectionWriter::visit(const DynamicRelocationSection &Sec) { + std::copy(std::begin(Sec.Contents), std::end(Sec.Contents), + Out.getBufferStart() + Sec.Offset); +} + +void DynamicRelocationSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); +} + +void Section::removeSectionReferences(const SectionBase *Sec) { + if (LinkSection == Sec) { + error("Section " + LinkSection->Name + + " cannot be removed because it is " + "referenced by the section " + this->Name); } } -bool SectionWithStrTab::classof(const SectionBase *S) { - return isa<DynamicSymbolTableSection>(S) || isa<DynamicSection>(S); +void GroupSection::finalize() { + this->Info = Sym->Index; + this->Link = SymTab->Index; } -void SectionWithStrTab::initialize(SectionTableRef SecTable) { - auto StrTab = SecTable.getSection(Link, - "Link field value " + Twine(Link) + - " in section " + Name + " is invalid"); - if (StrTab->Type != SHT_STRTAB) { - error("Link field value " + Twine(Link) + " in section " + Name + - " is not a string table"); +void GroupSection::removeSymbols(function_ref<bool(const Symbol &)> ToRemove) { + if (ToRemove(*Sym)) { + error("Symbol " + Sym->Name + + " cannot be removed because it is " + "referenced by the section " + + this->Name + "[" + Twine(this->Index) + "]"); } - setStrTab(StrTab); } -void SectionWithStrTab::finalize() { this->Link = StrTab->Index; } +void GroupSection::markSymbols() { + if (Sym) + Sym->Referenced = true; +} + +void Section::initialize(SectionTableRef SecTable) { + if (Link != ELF::SHN_UNDEF) { + LinkSection = + SecTable.getSection(Link, "Link field value " + Twine(Link) + + " in section " + Name + " is invalid"); + if (LinkSection->Type == ELF::SHT_SYMTAB) + LinkSection = nullptr; + } +} + +void Section::finalize() { this->Link = LinkSection ? LinkSection->Index : 0; } + +void GnuDebugLinkSection::init(StringRef File, StringRef Data) { + FileName = sys::path::filename(File); + // The format for the .gnu_debuglink starts with the file name and is + // followed by a null terminator and then the CRC32 of the file. The CRC32 + // should be 4 byte aligned. So we add the FileName size, a 1 for the null + // byte, and then finally push the size to alignment and add 4. + Size = alignTo(FileName.size() + 1, 4) + 4; + // The CRC32 will only be aligned if we align the whole section. + Align = 4; + Type = ELF::SHT_PROGBITS; + Name = ".gnu_debuglink"; + // For sections not found in segments, OriginalOffset is only used to + // establish the order that sections should go in. By using the maximum + // possible offset we cause this section to wind up at the end. + OriginalOffset = std::numeric_limits<uint64_t>::max(); + JamCRC crc; + crc.update(ArrayRef<char>(Data.data(), Data.size())); + // The CRC32 value needs to be complemented because the JamCRC dosn't + // finalize the CRC32 value. It also dosn't negate the initial CRC32 value + // but it starts by default at 0xFFFFFFFF which is the complement of zero. + CRC32 = ~crc.getCRC(); +} + +GnuDebugLinkSection::GnuDebugLinkSection(StringRef File) : FileName(File) { + // Read in the file to compute the CRC of it. + auto DebugOrErr = MemoryBuffer::getFile(File); + if (!DebugOrErr) + error("'" + File + "': " + DebugOrErr.getError().message()); + auto Debug = std::move(*DebugOrErr); + init(File, Debug->getBuffer()); +} + +template <class ELFT> +void ELFSectionWriter<ELFT>::visit(const GnuDebugLinkSection &Sec) { + auto Buf = Out.getBufferStart() + Sec.Offset; + char *File = reinterpret_cast<char *>(Buf); + Elf_Word *CRC = + reinterpret_cast<Elf_Word *>(Buf + Sec.Size - sizeof(Elf_Word)); + *CRC = Sec.CRC32; + std::copy(std::begin(Sec.FileName), std::end(Sec.FileName), File); +} + +void GnuDebugLinkSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); +} + +template <class ELFT> +void ELFSectionWriter<ELFT>::visit(const GroupSection &Sec) { + ELF::Elf32_Word *Buf = + reinterpret_cast<ELF::Elf32_Word *>(Out.getBufferStart() + Sec.Offset); + *Buf++ = Sec.FlagWord; + for (const auto *S : Sec.GroupMembers) + support::endian::write32<ELFT::TargetEndianness>(Buf++, S->Index); +} + +void GroupSection::accept(SectionVisitor &Visitor) const { + Visitor.visit(*this); +} // Returns true IFF a section is wholly inside the range of a segment static bool sectionWithinSegment(const SectionBase &Section, @@ -342,7 +571,7 @@ static bool segmentOverlapsSegment(const Segment &Child, Parent.OriginalOffset + Parent.FileSize > Child.OriginalOffset; } -static bool compareSegments(const Segment *A, const Segment *B) { +static bool compareSegmentsByOffset(const Segment *A, const Segment *B) { // Any segment without a parent segment should come before a segment // that has a parent segment. if (A->OriginalOffset < B->OriginalOffset) @@ -352,14 +581,36 @@ static bool compareSegments(const Segment *A, const Segment *B) { return A->Index < B->Index; } -template <class ELFT> -void Object<ELFT>::readProgramHeaders(const ELFFile<ELFT> &ElfFile) { +static bool compareSegmentsByPAddr(const Segment *A, const Segment *B) { + if (A->PAddr < B->PAddr) + return true; + if (A->PAddr > B->PAddr) + return false; + return A->Index < B->Index; +} + +template <class ELFT> void ELFBuilder<ELFT>::setParentSegment(Segment &Child) { + for (auto &Parent : Obj.segments()) { + // Every segment will overlap with itself but we don't want a segment to + // be it's own parent so we avoid that situation. + if (&Child != &Parent && segmentOverlapsSegment(Child, Parent)) { + // We want a canonical "most parental" segment but this requires + // inspecting the ParentSegment. + if (compareSegmentsByOffset(&Parent, &Child)) + if (Child.ParentSegment == nullptr || + compareSegmentsByOffset(&Parent, Child.ParentSegment)) { + Child.ParentSegment = &Parent; + } + } + } +} + +template <class ELFT> void ELFBuilder<ELFT>::readProgramHeaders() { uint32_t Index = 0; for (const auto &Phdr : unwrapOrError(ElfFile.program_headers())) { ArrayRef<uint8_t> Data{ElfFile.base() + Phdr.p_offset, (size_t)Phdr.p_filesz}; - Segments.emplace_back(llvm::make_unique<Segment>(Data)); - Segment &Seg = *Segments.back(); + Segment &Seg = Obj.addSegment(Data); Seg.Type = Phdr.p_type; Seg.Flags = Phdr.p_flags; Seg.OriginalOffset = Phdr.p_offset; @@ -370,62 +621,128 @@ void Object<ELFT>::readProgramHeaders(const ELFFile<ELFT> &ElfFile) { Seg.MemSize = Phdr.p_memsz; Seg.Align = Phdr.p_align; Seg.Index = Index++; - for (auto &Section : Sections) { - if (sectionWithinSegment(*Section, Seg)) { - Seg.addSection(&*Section); - if (!Section->ParentSegment || - Section->ParentSegment->Offset > Seg.Offset) { - Section->ParentSegment = &Seg; + for (auto &Section : Obj.sections()) { + if (sectionWithinSegment(Section, Seg)) { + Seg.addSection(&Section); + if (!Section.ParentSegment || + Section.ParentSegment->Offset > Seg.Offset) { + Section.ParentSegment = &Seg; } } } } + + auto &ElfHdr = Obj.ElfHdrSegment; + // Creating multiple PT_PHDR segments technically is not valid, but PT_LOAD + // segments must not overlap, and other types fit even less. + ElfHdr.Type = PT_PHDR; + ElfHdr.Flags = 0; + ElfHdr.OriginalOffset = ElfHdr.Offset = 0; + ElfHdr.VAddr = 0; + ElfHdr.PAddr = 0; + ElfHdr.FileSize = ElfHdr.MemSize = sizeof(Elf_Ehdr); + ElfHdr.Align = 0; + ElfHdr.Index = Index++; + + const auto &Ehdr = *ElfFile.getHeader(); + auto &PrHdr = Obj.ProgramHdrSegment; + PrHdr.Type = PT_PHDR; + PrHdr.Flags = 0; + // The spec requires us to have p_vaddr % p_align == p_offset % p_align. + // Whereas this works automatically for ElfHdr, here OriginalOffset is + // always non-zero and to ensure the equation we assign the same value to + // VAddr as well. + PrHdr.OriginalOffset = PrHdr.Offset = PrHdr.VAddr = Ehdr.e_phoff; + PrHdr.PAddr = 0; + PrHdr.FileSize = PrHdr.MemSize = Ehdr.e_phentsize * Ehdr.e_phnum; + // The spec requires us to naturally align all the fields. + PrHdr.Align = sizeof(Elf_Addr); + PrHdr.Index = Index++; + // Now we do an O(n^2) loop through the segments in order to match up // segments. - for (auto &Child : Segments) { - for (auto &Parent : Segments) { - // Every segment will overlap with itself but we don't want a segment to - // be it's own parent so we avoid that situation. - if (&Child != &Parent && segmentOverlapsSegment(*Child, *Parent)) { - // We want a canonical "most parental" segment but this requires - // inspecting the ParentSegment. - if (compareSegments(Parent.get(), Child.get())) - if (Child->ParentSegment == nullptr || - compareSegments(Parent.get(), Child->ParentSegment)) { - Child->ParentSegment = Parent.get(); - } - } - } + for (auto &Child : Obj.segments()) + setParentSegment(Child); + setParentSegment(ElfHdr); + setParentSegment(PrHdr); +} + +template <class ELFT> +void ELFBuilder<ELFT>::initGroupSection(GroupSection *GroupSec) { + auto SecTable = Obj.sections(); + auto SymTab = SecTable.template getSectionOfType<SymbolTableSection>( + GroupSec->Link, + "Link field value " + Twine(GroupSec->Link) + " in section " + + GroupSec->Name + " is invalid", + "Link field value " + Twine(GroupSec->Link) + " in section " + + GroupSec->Name + " is not a symbol table"); + auto Sym = SymTab->getSymbolByIndex(GroupSec->Info); + if (!Sym) + error("Info field value " + Twine(GroupSec->Info) + " in section " + + GroupSec->Name + " is not a valid symbol index"); + GroupSec->setSymTab(SymTab); + GroupSec->setSymbol(Sym); + if (GroupSec->Contents.size() % sizeof(ELF::Elf32_Word) || + GroupSec->Contents.empty()) + error("The content of the section " + GroupSec->Name + " is malformed"); + const ELF::Elf32_Word *Word = + reinterpret_cast<const ELF::Elf32_Word *>(GroupSec->Contents.data()); + const ELF::Elf32_Word *End = + Word + GroupSec->Contents.size() / sizeof(ELF::Elf32_Word); + GroupSec->setFlagWord(*Word++); + for (; Word != End; ++Word) { + uint32_t Index = support::endian::read32<ELFT::TargetEndianness>(Word); + GroupSec->addMember(SecTable.getSection( + Index, "Group member index " + Twine(Index) + " in section " + + GroupSec->Name + " is invalid")); } } template <class ELFT> -void Object<ELFT>::initSymbolTable(const object::ELFFile<ELFT> &ElfFile, - SymbolTableSection *SymTab, - SectionTableRef SecTable) { +void ELFBuilder<ELFT>::initSymbolTable(SymbolTableSection *SymTab) { const Elf_Shdr &Shdr = *unwrapOrError(ElfFile.getSection(SymTab->Index)); StringRef StrTabData = unwrapOrError(ElfFile.getStringTableForSymtab(Shdr)); + ArrayRef<Elf_Word> ShndxData; - for (const auto &Sym : unwrapOrError(ElfFile.symbols(&Shdr))) { + auto Symbols = unwrapOrError(ElfFile.symbols(&Shdr)); + for (const auto &Sym : Symbols) { SectionBase *DefSection = nullptr; StringRef Name = unwrapOrError(Sym.getName(StrTabData)); - if (Sym.st_shndx >= SHN_LORESERVE) { - if (!isValidReservedSectionIndex(Sym.st_shndx, Machine)) { + if (Sym.st_shndx == SHN_XINDEX) { + if (SymTab->getShndxTable() == nullptr) + error("Symbol '" + Name + + "' has index SHN_XINDEX but no SHT_SYMTAB_SHNDX section exists."); + if (ShndxData.data() == nullptr) { + const Elf_Shdr &ShndxSec = + *unwrapOrError(ElfFile.getSection(SymTab->getShndxTable()->Index)); + ShndxData = unwrapOrError( + ElfFile.template getSectionContentsAsArray<Elf_Word>(&ShndxSec)); + if (ShndxData.size() != Symbols.size()) + error("Symbol section index table does not have the same number of " + "entries as the symbol table."); + } + Elf_Word Index = ShndxData[&Sym - Symbols.begin()]; + DefSection = Obj.sections().getSection( + Index, + "Symbol '" + Name + "' has invalid section index " + + Twine(Index)); + } else if (Sym.st_shndx >= SHN_LORESERVE) { + if (!isValidReservedSectionIndex(Sym.st_shndx, Obj.Machine)) { error( "Symbol '" + Name + "' has unsupported value greater than or equal to SHN_LORESERVE: " + Twine(Sym.st_shndx)); } } else if (Sym.st_shndx != SHN_UNDEF) { - DefSection = SecTable.getSection( - Sym.st_shndx, - "Symbol '" + Name + "' is defined in invalid section with index " + - Twine(Sym.st_shndx)); + DefSection = Obj.sections().getSection( + Sym.st_shndx, "Symbol '" + Name + + "' is defined has invalid section index " + + Twine(Sym.st_shndx)); } SymTab->addSymbol(Name, Sym.getBinding(), Sym.getType(), DefSection, - Sym.getValue(), Sym.st_shndx, Sym.st_size); + Sym.getValue(), Sym.st_other, Sym.st_shndx, Sym.st_size); } } @@ -437,9 +754,9 @@ static void getAddend(uint64_t &ToSet, const Elf_Rel_Impl<ELFT, true> &Rela) { ToSet = Rela.r_addend; } -template <class ELFT, class T> -void initRelocations(RelocationSection<ELFT> *Relocs, - SymbolTableSection *SymbolTable, T RelRange) { +template <class T> +static void initRelocations(RelocationSection *Relocs, + SymbolTableSection *SymbolTable, T RelRange) { for (const auto &Rel : RelRange) { Relocation ToAdd; ToAdd.Offset = Rel.r_offset; @@ -450,14 +767,14 @@ void initRelocations(RelocationSection<ELFT> *Relocs, } } -SectionBase *SectionTableRef::getSection(uint16_t Index, Twine ErrMsg) { +SectionBase *SectionTableRef::getSection(uint32_t Index, Twine ErrMsg) { if (Index == SHN_UNDEF || Index > Sections.size()) error(ErrMsg); return Sections[Index - 1].get(); } template <class T> -T *SectionTableRef::getSectionOfType(uint16_t Index, Twine IndexErrMsg, +T *SectionTableRef::getSectionOfType(uint32_t Index, Twine IndexErrMsg, Twine TypeErrMsg) { if (T *Sec = dyn_cast<T>(getSection(Index, IndexErrMsg))) return Sec; @@ -465,147 +782,221 @@ T *SectionTableRef::getSectionOfType(uint16_t Index, Twine IndexErrMsg, } template <class ELFT> -std::unique_ptr<SectionBase> -Object<ELFT>::makeSection(const object::ELFFile<ELFT> &ElfFile, - const Elf_Shdr &Shdr) { +SectionBase &ELFBuilder<ELFT>::makeSection(const Elf_Shdr &Shdr) { ArrayRef<uint8_t> Data; switch (Shdr.sh_type) { case SHT_REL: case SHT_RELA: if (Shdr.sh_flags & SHF_ALLOC) { Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); - return llvm::make_unique<DynamicRelocationSection>(Data); + return Obj.addSection<DynamicRelocationSection>(Data); } - return llvm::make_unique<RelocationSection<ELFT>>(); + return Obj.addSection<RelocationSection>(); case SHT_STRTAB: // If a string table is allocated we don't want to mess with it. That would // mean altering the memory image. There are no special link types or // anything so we can just use a Section. if (Shdr.sh_flags & SHF_ALLOC) { Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); - return llvm::make_unique<Section>(Data); + return Obj.addSection<Section>(Data); } - return llvm::make_unique<StringTableSection>(); + return Obj.addSection<StringTableSection>(); case SHT_HASH: case SHT_GNU_HASH: // Hash tables should refer to SHT_DYNSYM which we're not going to change. // Because of this we don't need to mess with the hash tables either. Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); - return llvm::make_unique<Section>(Data); + return Obj.addSection<Section>(Data); + case SHT_GROUP: + Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); + return Obj.addSection<GroupSection>(Data); case SHT_DYNSYM: Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); - return llvm::make_unique<DynamicSymbolTableSection>(Data); + return Obj.addSection<DynamicSymbolTableSection>(Data); case SHT_DYNAMIC: Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); - return llvm::make_unique<DynamicSection>(Data); + return Obj.addSection<DynamicSection>(Data); case SHT_SYMTAB: { - auto SymTab = llvm::make_unique<SymbolTableSectionImpl<ELFT>>(); - SymbolTable = SymTab.get(); - return std::move(SymTab); + auto &SymTab = Obj.addSection<SymbolTableSection>(); + Obj.SymbolTable = &SymTab; + return SymTab; + } + case SHT_SYMTAB_SHNDX: { + auto &ShndxSection = Obj.addSection<SectionIndexSection>(); + Obj.SectionIndexTable = &ShndxSection; + return ShndxSection; } case SHT_NOBITS: - return llvm::make_unique<Section>(Data); + return Obj.addSection<Section>(Data); default: Data = unwrapOrError(ElfFile.getSectionContents(&Shdr)); - return llvm::make_unique<Section>(Data); + return Obj.addSection<Section>(Data); } } -template <class ELFT> -SectionTableRef Object<ELFT>::readSectionHeaders(const ELFFile<ELFT> &ElfFile) { +template <class ELFT> void ELFBuilder<ELFT>::readSectionHeaders() { uint32_t Index = 0; for (const auto &Shdr : unwrapOrError(ElfFile.sections())) { if (Index == 0) { ++Index; continue; } - SecPtr Sec = makeSection(ElfFile, Shdr); - Sec->Name = unwrapOrError(ElfFile.getSectionName(&Shdr)); - Sec->Type = Shdr.sh_type; - Sec->Flags = Shdr.sh_flags; - Sec->Addr = Shdr.sh_addr; - Sec->Offset = Shdr.sh_offset; - Sec->OriginalOffset = Shdr.sh_offset; - Sec->Size = Shdr.sh_size; - Sec->Link = Shdr.sh_link; - Sec->Info = Shdr.sh_info; - Sec->Align = Shdr.sh_addralign; - Sec->EntrySize = Shdr.sh_entsize; - Sec->Index = Index++; - Sections.push_back(std::move(Sec)); - } - - SectionTableRef SecTable(Sections); + auto &Sec = makeSection(Shdr); + Sec.Name = unwrapOrError(ElfFile.getSectionName(&Shdr)); + Sec.Type = Shdr.sh_type; + Sec.Flags = Shdr.sh_flags; + Sec.Addr = Shdr.sh_addr; + Sec.Offset = Shdr.sh_offset; + Sec.OriginalOffset = Shdr.sh_offset; + Sec.Size = Shdr.sh_size; + Sec.Link = Shdr.sh_link; + Sec.Info = Shdr.sh_info; + Sec.Align = Shdr.sh_addralign; + Sec.EntrySize = Shdr.sh_entsize; + Sec.Index = Index++; + } + + // If a section index table exists we'll need to initialize it before we + // initialize the symbol table because the symbol table might need to + // reference it. + if (Obj.SectionIndexTable) + Obj.SectionIndexTable->initialize(Obj.sections()); // Now that all of the sections have been added we can fill out some extra // details about symbol tables. We need the symbol table filled out before // any relocations. - if (SymbolTable) { - SymbolTable->initialize(SecTable); - initSymbolTable(ElfFile, SymbolTable, SecTable); + if (Obj.SymbolTable) { + Obj.SymbolTable->initialize(Obj.sections()); + initSymbolTable(Obj.SymbolTable); } // Now that all sections and symbols have been added we can add // relocations that reference symbols and set the link and info fields for // relocation sections. - for (auto &Section : Sections) { - if (Section.get() == SymbolTable) + for (auto &Section : Obj.sections()) { + if (&Section == Obj.SymbolTable) continue; - Section->initialize(SecTable); - if (auto RelSec = dyn_cast<RelocationSection<ELFT>>(Section.get())) { + Section.initialize(Obj.sections()); + if (auto RelSec = dyn_cast<RelocationSection>(&Section)) { auto Shdr = unwrapOrError(ElfFile.sections()).begin() + RelSec->Index; if (RelSec->Type == SHT_REL) - initRelocations(RelSec, SymbolTable, unwrapOrError(ElfFile.rels(Shdr))); + initRelocations(RelSec, Obj.SymbolTable, + unwrapOrError(ElfFile.rels(Shdr))); else - initRelocations(RelSec, SymbolTable, + initRelocations(RelSec, Obj.SymbolTable, unwrapOrError(ElfFile.relas(Shdr))); + } else if (auto GroupSec = dyn_cast<GroupSection>(&Section)) { + initGroupSection(GroupSec); } } - - return SecTable; } -template <class ELFT> Object<ELFT>::Object(const ELFObjectFile<ELFT> &Obj) { - const auto &ElfFile = *Obj.getELFFile(); +template <class ELFT> void ELFBuilder<ELFT>::build() { const auto &Ehdr = *ElfFile.getHeader(); - std::copy(Ehdr.e_ident, Ehdr.e_ident + 16, Ident); - Type = Ehdr.e_type; - Machine = Ehdr.e_machine; - Version = Ehdr.e_version; - Entry = Ehdr.e_entry; - Flags = Ehdr.e_flags; + std::copy(Ehdr.e_ident, Ehdr.e_ident + 16, Obj.Ident); + Obj.Type = Ehdr.e_type; + Obj.Machine = Ehdr.e_machine; + Obj.Version = Ehdr.e_version; + Obj.Entry = Ehdr.e_entry; + Obj.Flags = Ehdr.e_flags; + + readSectionHeaders(); + readProgramHeaders(); + + uint32_t ShstrIndex = Ehdr.e_shstrndx; + if (ShstrIndex == SHN_XINDEX) + ShstrIndex = unwrapOrError(ElfFile.getSection(0))->sh_link; + + Obj.SectionNames = + Obj.sections().template getSectionOfType<StringTableSection>( + ShstrIndex, + "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) + + " in elf header " + " is invalid", + "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) + + " in elf header " + " is not a string table"); +} + +// A generic size function which computes sizes of any random access range. +template <class R> size_t size(R &&Range) { + return static_cast<size_t>(std::end(Range) - std::begin(Range)); +} + +Writer::~Writer() {} - SectionTableRef SecTable = readSectionHeaders(ElfFile); - readProgramHeaders(ElfFile); +Reader::~Reader() {} - SectionNames = SecTable.getSectionOfType<StringTableSection>( - Ehdr.e_shstrndx, - "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) + " in elf header " + - " is invalid", - "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) + " in elf header " + - " is not a string table"); +ElfType ELFReader::getElfType() const { + if (isa<ELFObjectFile<ELF32LE>>(Bin)) + return ELFT_ELF32LE; + if (isa<ELFObjectFile<ELF64LE>>(Bin)) + return ELFT_ELF64LE; + if (isa<ELFObjectFile<ELF32BE>>(Bin)) + return ELFT_ELF32BE; + if (isa<ELFObjectFile<ELF64BE>>(Bin)) + return ELFT_ELF64BE; + llvm_unreachable("Invalid ELFType"); } -template <class ELFT> -void Object<ELFT>::writeHeader(FileOutputBuffer &Out) const { - uint8_t *Buf = Out.getBufferStart(); - Elf_Ehdr &Ehdr = *reinterpret_cast<Elf_Ehdr *>(Buf); - std::copy(Ident, Ident + 16, Ehdr.e_ident); - Ehdr.e_type = Type; - Ehdr.e_machine = Machine; - Ehdr.e_version = Version; - Ehdr.e_entry = Entry; - Ehdr.e_phoff = sizeof(Elf_Ehdr); - Ehdr.e_flags = Flags; +std::unique_ptr<Object> ELFReader::create() const { + auto Obj = llvm::make_unique<Object>(); + if (auto *o = dyn_cast<ELFObjectFile<ELF32LE>>(Bin)) { + ELFBuilder<ELF32LE> Builder(*o, *Obj); + Builder.build(); + return Obj; + } else if (auto *o = dyn_cast<ELFObjectFile<ELF64LE>>(Bin)) { + ELFBuilder<ELF64LE> Builder(*o, *Obj); + Builder.build(); + return Obj; + } else if (auto *o = dyn_cast<ELFObjectFile<ELF32BE>>(Bin)) { + ELFBuilder<ELF32BE> Builder(*o, *Obj); + Builder.build(); + return Obj; + } else if (auto *o = dyn_cast<ELFObjectFile<ELF64BE>>(Bin)) { + ELFBuilder<ELF64BE> Builder(*o, *Obj); + Builder.build(); + return Obj; + } + error("Invalid file type"); +} + +template <class ELFT> void ELFWriter<ELFT>::writeEhdr() { + uint8_t *B = Buf.getBufferStart(); + Elf_Ehdr &Ehdr = *reinterpret_cast<Elf_Ehdr *>(B); + std::copy(Obj.Ident, Obj.Ident + 16, Ehdr.e_ident); + Ehdr.e_type = Obj.Type; + Ehdr.e_machine = Obj.Machine; + Ehdr.e_version = Obj.Version; + Ehdr.e_entry = Obj.Entry; + Ehdr.e_phoff = Obj.ProgramHdrSegment.Offset; + Ehdr.e_flags = Obj.Flags; Ehdr.e_ehsize = sizeof(Elf_Ehdr); Ehdr.e_phentsize = sizeof(Elf_Phdr); - Ehdr.e_phnum = Segments.size(); + Ehdr.e_phnum = size(Obj.segments()); Ehdr.e_shentsize = sizeof(Elf_Shdr); if (WriteSectionHeaders) { - Ehdr.e_shoff = SHOffset; - Ehdr.e_shnum = Sections.size() + 1; - Ehdr.e_shstrndx = SectionNames->Index; + Ehdr.e_shoff = Obj.SHOffset; + // """ + // If the number of sections is greater than or equal to + // SHN_LORESERVE (0xff00), this member has the value zero and the actual + // number of section header table entries is contained in the sh_size field + // of the section header at index 0. + // """ + auto Shnum = size(Obj.sections()) + 1; + if (Shnum >= SHN_LORESERVE) + Ehdr.e_shnum = 0; + else + Ehdr.e_shnum = Shnum; + // """ + // If the section name string table section index is greater than or equal + // to SHN_LORESERVE (0xff00), this member has the value SHN_XINDEX (0xffff) + // and the actual index of the section name string table section is + // contained in the sh_link field of the section header at index 0. + // """ + if (Obj.SectionNames->Index >= SHN_LORESERVE) + Ehdr.e_shstrndx = SHN_XINDEX; + else + Ehdr.e_shstrndx = Obj.SectionNames->Index; } else { Ehdr.e_shoff = 0; Ehdr.e_shnum = 0; @@ -613,42 +1004,46 @@ void Object<ELFT>::writeHeader(FileOutputBuffer &Out) const { } } -template <class ELFT> -void Object<ELFT>::writeProgramHeaders(FileOutputBuffer &Out) const { - for (auto &Phdr : Segments) - Phdr->template writeHeader<ELFT>(Out); +template <class ELFT> void ELFWriter<ELFT>::writePhdrs() { + for (auto &Seg : Obj.segments()) + writePhdr(Seg); } -template <class ELFT> -void Object<ELFT>::writeSectionHeaders(FileOutputBuffer &Out) const { - uint8_t *Buf = Out.getBufferStart() + SHOffset; +template <class ELFT> void ELFWriter<ELFT>::writeShdrs() { + uint8_t *B = Buf.getBufferStart() + Obj.SHOffset; // This reference serves to write the dummy section header at the begining // of the file. It is not used for anything else - Elf_Shdr &Shdr = *reinterpret_cast<Elf_Shdr *>(Buf); + Elf_Shdr &Shdr = *reinterpret_cast<Elf_Shdr *>(B); Shdr.sh_name = 0; Shdr.sh_type = SHT_NULL; Shdr.sh_flags = 0; Shdr.sh_addr = 0; Shdr.sh_offset = 0; - Shdr.sh_size = 0; - Shdr.sh_link = 0; + // See writeEhdr for why we do this. + uint64_t Shnum = size(Obj.sections()) + 1; + if (Shnum >= SHN_LORESERVE) + Shdr.sh_size = Shnum; + else + Shdr.sh_size = 0; + // See writeEhdr for why we do this. + if (Obj.SectionNames != nullptr && Obj.SectionNames->Index >= SHN_LORESERVE) + Shdr.sh_link = Obj.SectionNames->Index; + else + Shdr.sh_link = 0; Shdr.sh_info = 0; Shdr.sh_addralign = 0; Shdr.sh_entsize = 0; - for (auto &Section : Sections) - Section->template writeHeader<ELFT>(Out); + for (auto &Sec : Obj.sections()) + writeShdr(Sec); } -template <class ELFT> -void Object<ELFT>::writeSectionData(FileOutputBuffer &Out) const { - for (auto &Section : Sections) - Section->writeSection(Out); +template <class ELFT> void ELFWriter<ELFT>::writeSectionData() { + for (auto &Sec : Obj.sections()) + Sec.accept(*SecWriter); } -template <class ELFT> -void Object<ELFT>::removeSections( - std::function<bool(const SectionBase &)> ToRemove) { +void Object::removeSections(std::function<bool(const SectionBase &)> ToRemove) { auto Iter = std::stable_partition( std::begin(Sections), std::end(Sections), [=](const SecPtr &Sec) { @@ -662,12 +1057,10 @@ void Object<ELFT>::removeSections( }); if (SymbolTable != nullptr && ToRemove(*SymbolTable)) SymbolTable = nullptr; - if (ToRemove(*SectionNames)) { - if (WriteSectionHeaders) - error("Cannot remove " + SectionNames->Name + - " because it is the section header string table."); + if (SectionNames != nullptr && ToRemove(*SectionNames)) SectionNames = nullptr; - } + if (SectionIndexTable != nullptr && ToRemove(*SectionIndexTable)) + SectionIndexTable = nullptr; // Now make sure there are no remaining references to the sections that will // be removed. Sometimes it is impossible to remove a reference so we emit // an error here instead. @@ -681,14 +1074,15 @@ void Object<ELFT>::removeSections( Sections.erase(Iter, std::end(Sections)); } -template <class ELFT> -void Object<ELFT>::addSection(StringRef SecName, ArrayRef<uint8_t> Data) { - auto Sec = llvm::make_unique<OwnedDataSection>(SecName, Data); - Sec->OriginalOffset = ~0ULL; - Sections.push_back(std::move(Sec)); +void Object::removeSymbols(function_ref<bool(const Symbol &)> ToRemove) { + if (!SymbolTable) + return; + + for (const SecPtr &Sec : Sections) + Sec->removeSymbols(ToRemove); } -template <class ELFT> void ELFObject<ELFT>::sortSections() { +void Object::sortSections() { // Put all sections in offset order. Maintain the ordering as closely as // possible while meeting that demand however. auto CompareSections = [](const SecPtr &A, const SecPtr &B) { @@ -713,7 +1107,8 @@ static uint64_t alignToAddr(uint64_t Offset, uint64_t Addr, uint64_t Align) { // Orders segments such that if x = y->ParentSegment then y comes before x. static void OrderSegments(std::vector<Segment *> &Segments) { - std::stable_sort(std::begin(Segments), std::end(Segments), compareSegments); + std::stable_sort(std::begin(Segments), std::end(Segments), + compareSegmentsByOffset); } // This function finds a consistent layout for a list of segments starting from @@ -722,7 +1117,7 @@ static void OrderSegments(std::vector<Segment *> &Segments) { static uint64_t LayoutSegments(std::vector<Segment *> &Segments, uint64_t Offset) { assert(std::is_sorted(std::begin(Segments), std::end(Segments), - compareSegments)); + compareSegmentsByOffset)); // The only way a segment should move is if a section was between two // segments and that section was removed. If that section isn't in a segment // then it's acceptable, but not ideal, to simply move it to after the @@ -752,8 +1147,8 @@ static uint64_t LayoutSegments(std::vector<Segment *> &Segments, // does not have a ParentSegment. It returns either the offset given if all // sections had a ParentSegment or an offset one past the last section if there // was a section that didn't have a ParentSegment. -template <class SecPtr> -static uint64_t LayoutSections(std::vector<SecPtr> &Sections, uint64_t Offset) { +template <class Range> +static uint64_t LayoutSections(Range Sections, uint64_t Offset) { // Now the offset of every segment has been set we can assign the offsets // of each section. For sections that are covered by a segment we should use // the segment's original offset and the section's original offset to compute @@ -762,106 +1157,154 @@ static uint64_t LayoutSections(std::vector<SecPtr> &Sections, uint64_t Offset) { // covered by segments we can just bump Offset to the next valid location. uint32_t Index = 1; for (auto &Section : Sections) { - Section->Index = Index++; - if (Section->ParentSegment != nullptr) { - auto Segment = Section->ParentSegment; - Section->Offset = - Segment->Offset + (Section->OriginalOffset - Segment->OriginalOffset); + Section.Index = Index++; + if (Section.ParentSegment != nullptr) { + auto Segment = *Section.ParentSegment; + Section.Offset = + Segment.Offset + (Section.OriginalOffset - Segment.OriginalOffset); } else { - Offset = alignTo(Offset, Section->Align == 0 ? 1 : Section->Align); - Section->Offset = Offset; - if (Section->Type != SHT_NOBITS) - Offset += Section->Size; + Offset = alignTo(Offset, Section.Align == 0 ? 1 : Section.Align); + Section.Offset = Offset; + if (Section.Type != SHT_NOBITS) + Offset += Section.Size; } } return Offset; } -template <class ELFT> void ELFObject<ELFT>::assignOffsets() { +template <class ELFT> void ELFWriter<ELFT>::assignOffsets() { // We need a temporary list of segments that has a special order to it // so that we know that anytime ->ParentSegment is set that segment has // already had its offset properly set. std::vector<Segment *> OrderedSegments; - for (auto &Segment : this->Segments) - OrderedSegments.push_back(Segment.get()); + for (auto &Segment : Obj.segments()) + OrderedSegments.push_back(&Segment); + OrderedSegments.push_back(&Obj.ElfHdrSegment); + OrderedSegments.push_back(&Obj.ProgramHdrSegment); OrderSegments(OrderedSegments); - // The size of ELF + program headers will not change so it is ok to assume - // that the first offset of the first segment is a good place to start - // outputting sections. This covers both the standard case and the PT_PHDR - // case. - uint64_t Offset; - if (!OrderedSegments.empty()) { - Offset = OrderedSegments[0]->Offset; - } else { - Offset = sizeof(Elf_Ehdr); - } + // Offset is used as the start offset of the first segment to be laid out. + // Since the ELF Header (ElfHdrSegment) must be at the start of the file, + // we start at offset 0. + uint64_t Offset = 0; Offset = LayoutSegments(OrderedSegments, Offset); - Offset = LayoutSections(this->Sections, Offset); + Offset = LayoutSections(Obj.sections(), Offset); // If we need to write the section header table out then we need to align the // Offset so that SHOffset is valid. - if (this->WriteSectionHeaders) + if (WriteSectionHeaders) Offset = alignTo(Offset, sizeof(typename ELFT::Addr)); - this->SHOffset = Offset; + Obj.SHOffset = Offset; } -template <class ELFT> size_t ELFObject<ELFT>::totalSize() const { +template <class ELFT> size_t ELFWriter<ELFT>::totalSize() const { // We already have the section header offset so we can calculate the total // size by just adding up the size of each section header. - auto NullSectionSize = this->WriteSectionHeaders ? sizeof(Elf_Shdr) : 0; - return this->SHOffset + this->Sections.size() * sizeof(Elf_Shdr) + + auto NullSectionSize = WriteSectionHeaders ? sizeof(Elf_Shdr) : 0; + return Obj.SHOffset + size(Obj.sections()) * sizeof(Elf_Shdr) + NullSectionSize; } -template <class ELFT> void ELFObject<ELFT>::write(FileOutputBuffer &Out) const { - this->writeHeader(Out); - this->writeProgramHeaders(Out); - this->writeSectionData(Out); - if (this->WriteSectionHeaders) - this->writeSectionHeaders(Out); +template <class ELFT> void ELFWriter<ELFT>::write() { + writeEhdr(); + writePhdrs(); + writeSectionData(); + if (WriteSectionHeaders) + writeShdrs(); + if (auto E = Buf.commit()) + reportError(Buf.getName(), errorToErrorCode(std::move(E))); } -template <class ELFT> void ELFObject<ELFT>::finalize() { - // Make sure we add the names of all the sections. - if (this->SectionNames != nullptr) - for (const auto &Section : this->Sections) { - this->SectionNames->addString(Section->Name); +template <class ELFT> void ELFWriter<ELFT>::finalize() { + // It could happen that SectionNames has been removed and yet the user wants + // a section header table output. We need to throw an error if a user tries + // to do that. + if (Obj.SectionNames == nullptr && WriteSectionHeaders) + error("Cannot write section header table because section header string " + "table was removed."); + + Obj.sortSections(); + + // We need to assign indexes before we perform layout because we need to know + // if we need large indexes or not. We can assign indexes first and check as + // we go to see if we will actully need large indexes. + bool NeedsLargeIndexes = false; + if (size(Obj.sections()) >= SHN_LORESERVE) { + auto Sections = Obj.sections(); + NeedsLargeIndexes = + std::any_of(Sections.begin() + SHN_LORESERVE, Sections.end(), + [](const SectionBase &Sec) { return Sec.HasSymbol; }); + // TODO: handle case where only one section needs the large index table but + // only needs it because the large index table hasn't been removed yet. + } + + if (NeedsLargeIndexes) { + // This means we definitely need to have a section index table but if we + // already have one then we should use it instead of making a new one. + if (Obj.SymbolTable != nullptr && Obj.SectionIndexTable == nullptr) { + // Addition of a section to the end does not invalidate the indexes of + // other sections and assigns the correct index to the new section. + auto &Shndx = Obj.addSection<SectionIndexSection>(); + Obj.SymbolTable->setShndxTable(&Shndx); + Shndx.setSymTab(Obj.SymbolTable); + } + } else { + // Since we don't need SectionIndexTable we should remove it and all + // references to it. + if (Obj.SectionIndexTable != nullptr) { + Obj.removeSections([this](const SectionBase &Sec) { + return &Sec == Obj.SectionIndexTable; + }); + } + } + + // Make sure we add the names of all the sections. Importantly this must be + // done after we decide to add or remove SectionIndexes. + if (Obj.SectionNames != nullptr) + for (const auto &Section : Obj.sections()) { + Obj.SectionNames->addString(Section.Name); } - // Make sure we add the names of all the symbols. - if (this->SymbolTable != nullptr) - this->SymbolTable->addSymbolNames(); - sortSections(); + // Before we can prepare for layout the indexes need to be finalized. + uint64_t Index = 0; + for (auto &Sec : Obj.sections()) + Sec.Index = Index++; + + // The symbol table does not update all other sections on update. For + // instance, symbol names are not added as new symbols are added. This means + // that some sections, like .strtab, don't yet have their final size. + if (Obj.SymbolTable != nullptr) + Obj.SymbolTable->prepareForLayout(); + assignOffsets(); // Finalize SectionNames first so that we can assign name indexes. - if (this->SectionNames != nullptr) - this->SectionNames->finalize(); + if (Obj.SectionNames != nullptr) + Obj.SectionNames->finalize(); // Finally now that all offsets and indexes have been set we can finalize any // remaining issues. - uint64_t Offset = this->SHOffset + sizeof(Elf_Shdr); - for (auto &Section : this->Sections) { - Section->HeaderOffset = Offset; + uint64_t Offset = Obj.SHOffset + sizeof(Elf_Shdr); + for (auto &Section : Obj.sections()) { + Section.HeaderOffset = Offset; Offset += sizeof(Elf_Shdr); - if (this->WriteSectionHeaders) - Section->NameIndex = this->SectionNames->findIndex(Section->Name); - Section->finalize(); + if (WriteSectionHeaders) + Section.NameIndex = Obj.SectionNames->findIndex(Section.Name); + Section.finalize(); } -} -template <class ELFT> size_t BinaryObject<ELFT>::totalSize() const { - return TotalSize; + Buf.allocate(totalSize()); + SecWriter = llvm::make_unique<ELFSectionWriter<ELFT>>(Buf); } -template <class ELFT> -void BinaryObject<ELFT>::write(FileOutputBuffer &Out) const { - for (auto &Section : this->Sections) { - if ((Section->Flags & SHF_ALLOC) == 0) +void BinaryWriter::write() { + for (auto &Section : Obj.sections()) { + if ((Section.Flags & SHF_ALLOC) == 0) continue; - Section->writeSection(Out); + Section.accept(*SecWriter); } + if (auto E = Buf.commit()) + reportError(Buf.getName(), errorToErrorCode(std::move(E))); } -template <class ELFT> void BinaryObject<ELFT>::finalize() { +void BinaryWriter::finalize() { // TODO: Create a filter range to construct OrderedSegments from so that this // code can be deduped with assignOffsets above. This should also solve the // todo below for LayoutSections. @@ -870,13 +1313,25 @@ template <class ELFT> void BinaryObject<ELFT>::finalize() { // already had it's offset properly set. We only want to consider the segments // that will affect layout of allocated sections so we only add those. std::vector<Segment *> OrderedSegments; - for (auto &Section : this->Sections) { - if ((Section->Flags & SHF_ALLOC) != 0 && - Section->ParentSegment != nullptr) { - OrderedSegments.push_back(Section->ParentSegment); + for (auto &Section : Obj.sections()) { + if ((Section.Flags & SHF_ALLOC) != 0 && Section.ParentSegment != nullptr) { + OrderedSegments.push_back(Section.ParentSegment); } } - OrderSegments(OrderedSegments); + + // For binary output, we're going to use physical addresses instead of + // virtual addresses, since a binary output is used for cases like ROM + // loading and physical addresses are intended for ROM loading. + // However, if no segment has a physical address, we'll fallback to using + // virtual addresses for all. + if (std::all_of(std::begin(OrderedSegments), std::end(OrderedSegments), + [](const Segment *Segment) { return Segment->PAddr == 0; })) + for (const auto &Segment : OrderedSegments) + Segment->PAddr = Segment->VAddr; + + std::stable_sort(std::begin(OrderedSegments), std::end(OrderedSegments), + compareSegmentsByPAddr); + // Because we add a ParentSegment for each section we might have duplicate // segments in OrderedSegments. If there were duplicates then LayoutSegments // would do very strange things. @@ -884,6 +1339,8 @@ template <class ELFT> void BinaryObject<ELFT>::finalize() { std::unique(std::begin(OrderedSegments), std::end(OrderedSegments)); OrderedSegments.erase(End, std::end(OrderedSegments)); + uint64_t Offset = 0; + // Modify the first segment so that there is no gap at the start. This allows // our layout algorithm to proceed as expected while not out writing out the // gap at the start. @@ -892,30 +1349,29 @@ template <class ELFT> void BinaryObject<ELFT>::finalize() { auto Sec = Seg->firstSection(); auto Diff = Sec->OriginalOffset - Seg->OriginalOffset; Seg->OriginalOffset += Diff; - // The size needs to be shrunk as well + // The size needs to be shrunk as well. Seg->FileSize -= Diff; - Seg->MemSize -= Diff; - // The VAddr needs to be adjusted so that the alignment is correct as well - Seg->VAddr += Diff; - Seg->PAddr = Seg->VAddr; - // We don't want this to be shifted by alignment so we need to set the - // alignment to zero. - Seg->Align = 0; + // The PAddr needs to be increased to remove the gap before the first + // section. + Seg->PAddr += Diff; + uint64_t LowestPAddr = Seg->PAddr; + for (auto &Segment : OrderedSegments) { + Segment->Offset = Segment->PAddr - LowestPAddr; + Offset = std::max(Offset, Segment->Offset + Segment->FileSize); + } } - uint64_t Offset = LayoutSegments(OrderedSegments, 0); - // TODO: generalize LayoutSections to take a range. Pass a special range // constructed from an iterator that skips values for which a predicate does // not hold. Then pass such a range to LayoutSections instead of constructing // AllocatedSections here. std::vector<SectionBase *> AllocatedSections; - for (auto &Section : this->Sections) { - if ((Section->Flags & SHF_ALLOC) == 0) + for (auto &Section : Obj.sections()) { + if ((Section.Flags & SHF_ALLOC) == 0) continue; - AllocatedSections.push_back(Section.get()); + AllocatedSections.push_back(&Section); } - LayoutSections(AllocatedSections, Offset); + LayoutSections(make_pointee_range(AllocatedSections), Offset); // Now that every section has been laid out we just need to compute the total // file size. This might not be the same as the offset returned by @@ -926,23 +1382,22 @@ template <class ELFT> void BinaryObject<ELFT>::finalize() { if (Section->Type != SHT_NOBITS) TotalSize = std::max(TotalSize, Section->Offset + Section->Size); } + + Buf.allocate(TotalSize); + SecWriter = llvm::make_unique<BinarySectionWriter>(Buf); } namespace llvm { - -template class Object<ELF64LE>; -template class Object<ELF64BE>; -template class Object<ELF32LE>; -template class Object<ELF32BE>; - -template class ELFObject<ELF64LE>; -template class ELFObject<ELF64BE>; -template class ELFObject<ELF32LE>; -template class ELFObject<ELF32BE>; - -template class BinaryObject<ELF64LE>; -template class BinaryObject<ELF64BE>; -template class BinaryObject<ELF32LE>; -template class BinaryObject<ELF32BE>; - +namespace objcopy { + +template class ELFBuilder<ELF64LE>; +template class ELFBuilder<ELF64BE>; +template class ELFBuilder<ELF32LE>; +template class ELFBuilder<ELF32BE>; + +template class ELFWriter<ELF64LE>; +template class ELFWriter<ELF64BE>; +template class ELFWriter<ELF32LE>; +template class ELFWriter<ELF32BE>; +} // end namespace objcopy } // end namespace llvm |