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-rw-r--r--llvm/tools/llvm-objcopy/Object.cpp341
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diff --git a/llvm/tools/llvm-objcopy/Object.cpp b/llvm/tools/llvm-objcopy/Object.cpp
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-//===- Object.cpp -----------------------------------------------*- C++ -*-===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-#include "Object.h"
-#include "llvm-objcopy.h"
-
-using namespace llvm;
-using namespace object;
-using namespace ELF;
-
-template <class ELFT> void Segment::writeHeader(FileOutputBuffer &Out) const {
- typedef typename ELFT::Ehdr Elf_Ehdr;
- typedef typename ELFT::Phdr Elf_Phdr;
-
- 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 Segment::finalize() {
- auto FirstSec = firstSection();
- if (FirstSec) {
- // It is possible for a gap to be at the begining of a segment. Because of
- // this we need to compute the new offset based on how large this gap was
- // in the source file. Section layout should have already ensured that this
- // space is not used for something else.
- uint64_t OriginalOffset = Offset;
- Offset = FirstSec->Offset - (FirstSec->OriginalOffset - OriginalOffset);
- }
-}
-
-void SectionBase::finalize() {}
-
-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)
- return;
- uint8_t *Buf = Out.getBufferStart() + Offset;
- std::copy(std::begin(Contents), std::end(Contents), Buf);
-}
-
-void StringTableSection::addString(StringRef Name) {
- StrTabBuilder.add(Name);
- Size = StrTabBuilder.getSize();
-}
-
-uint32_t StringTableSection::findIndex(StringRef Name) const {
- return StrTabBuilder.getOffset(Name);
-}
-
-void StringTableSection::finalize() { StrTabBuilder.finalize(); }
-
-void StringTableSection::writeSection(FileOutputBuffer &Out) const {
- StrTabBuilder.write(Out.getBufferStart() + Offset);
-}
-
-// Returns true IFF a section is wholly inside the range of a segment
-static bool sectionWithinSegment(const SectionBase &Section,
- const Segment &Segment) {
- // If a section is empty it should be treated like it has a size of 1. This is
- // to clarify the case when an empty section lies on a boundary between two
- // segments and ensures that the section "belongs" to the second segment and
- // not the first.
- uint64_t SecSize = Section.Size ? Section.Size : 1;
- return Segment.Offset <= Section.OriginalOffset &&
- Segment.Offset + Segment.FileSize >= Section.OriginalOffset + SecSize;
-}
-
-template <class ELFT>
-void Object<ELFT>::readProgramHeaders(const ELFFile<ELFT> &ElfFile) {
- uint32_t Index = 0;
- for (const auto &Phdr : unwrapOrError(ElfFile.program_headers())) {
- Segments.emplace_back(make_unique<Segment>());
- Segment &Seg = *Segments.back();
- Seg.Type = Phdr.p_type;
- Seg.Flags = Phdr.p_flags;
- Seg.Offset = Phdr.p_offset;
- Seg.VAddr = Phdr.p_vaddr;
- Seg.PAddr = Phdr.p_paddr;
- Seg.FileSize = Phdr.p_filesz;
- 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;
- }
- }
- }
- }
-}
-
-template <class ELFT>
-std::unique_ptr<SectionBase>
-Object<ELFT>::makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
- const Elf_Shdr &Shdr) {
- ArrayRef<uint8_t> Data;
- switch (Shdr.sh_type) {
- case SHT_STRTAB:
- return make_unique<StringTableSection>();
- case SHT_NOBITS:
- return make_unique<Section>(Data);
- default:
- Data = unwrapOrError(ElfFile.getSectionContents(&Shdr));
- return make_unique<Section>(Data);
- };
-}
-
-template <class ELFT>
-void Object<ELFT>::readSectionHeaders(const ELFFile<ELFT> &ElfFile) {
- 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));
- }
-}
-
-template <class ELFT> size_t Object<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.
- return SHOffset + Sections.size() * sizeof(Elf_Shdr) + sizeof(Elf_Shdr);
-}
-
-template <class ELFT> Object<ELFT>::Object(const ELFObjectFile<ELFT> &Obj) {
- const auto &ElfFile = *Obj.getELFFile();
- 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;
-
- readSectionHeaders(ElfFile);
- readProgramHeaders(ElfFile);
-
- SectionNames =
- dyn_cast<StringTableSection>(Sections[Ehdr.e_shstrndx - 1].get());
-}
-
-template <class ELFT> void Object<ELFT>::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) {
- return A->OriginalOffset < B->OriginalOffset;
- };
- std::stable_sort(std::begin(Sections), std::end(Sections), CompareSections);
-}
-
-template <class ELFT> void Object<ELFT>::assignOffsets() {
- // Decide file offsets and indexes.
- size_t PhdrSize = Segments.size() * sizeof(Elf_Phdr);
- // We can put section data after the ELF header and the program headers.
- uint64_t Offset = sizeof(Elf_Ehdr) + PhdrSize;
- uint64_t Index = 1;
- for (auto &Section : Sections) {
- // The segment can have a different alignment than the section. In the case
- // that there is a parent segment then as long as we satisfy the alignment
- // of the segment it should follow that that the section is aligned.
- if (Section->ParentSegment) {
- auto FirstInSeg = Section->ParentSegment->firstSection();
- if (FirstInSeg == Section.get()) {
- Offset = alignTo(Offset, Section->ParentSegment->Align);
- // There can be gaps at the start of a segment before the first section.
- // So first we assign the alignment of the segment and then assign the
- // location of the section from there
- Section->Offset =
- Offset + Section->OriginalOffset - Section->ParentSegment->Offset;
- }
- // We should respect interstitial gaps of allocated sections. We *must*
- // maintain the memory image so that addresses are preserved. As, with the
- // exception of SHT_NOBITS sections at the end of segments, the memory
- // image is a copy of the file image, we preserve the file image as well.
- // There's a strange case where a thread local SHT_NOBITS can cause the
- // memory image and file image to not be the same. This occurs, on some
- // systems, when a thread local SHT_NOBITS is between two SHT_PROGBITS
- // and the thread local SHT_NOBITS section is at the end of a TLS segment.
- // In this case to faithfully copy the segment file image we must use
- // relative offsets. In any other case this would be the same as using the
- // relative addresses so this should maintian the memory image as desired.
- Offset = FirstInSeg->Offset + Section->OriginalOffset -
- FirstInSeg->OriginalOffset;
- }
- // Alignment should have already been handled by the above if statement if
- // this if this section is in a segment. Technically this shouldn't do
- // anything bad if the alignments of the sections are all correct and the
- // file image isn't corrupted. Still in sticking with the motto "maintain
- // the file image" we should avoid messing up the file image if the
- // alignment disagrees with the file image.
- if (!Section->ParentSegment && Section->Align)
- Offset = alignTo(Offset, Section->Align);
- Section->Offset = Offset;
- Section->Index = Index++;
- if (Section->Type != SHT_NOBITS)
- Offset += Section->Size;
- }
- // 'offset' should now be just after all the section data so we should set the
- // section header table offset to be exactly here. This spot might not be
- // aligned properly however so we should align it as needed. For 32-bit ELF
- // this needs to be 4-byte aligned and on 64-bit it needs to be 8-byte aligned
- // so the size of ELFT::Addr is used to ensure this.
- Offset = alignTo(Offset, sizeof(typename ELFT::Addr));
- SHOffset = Offset;
-}
-
-template <class ELFT> void Object<ELFT>::finalize() {
- for (auto &Section : Sections)
- SectionNames->addString(Section->Name);
-
- sortSections();
- assignOffsets();
-
- // Finalize SectionNames first so that we can assign name indexes.
- SectionNames->finalize();
- // Finally now that all offsets and indexes have been set we can finalize any
- // remaining issues.
- uint64_t Offset = SHOffset + sizeof(Elf_Shdr);
- for (auto &Section : Sections) {
- Section->HeaderOffset = Offset;
- Offset += sizeof(Elf_Shdr);
- Section->NameIndex = SectionNames->findIndex(Section->Name);
- Section->finalize();
- }
-
- for (auto &Segment : Segments)
- Segment->finalize();
-}
-
-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_shoff = SHOffset;
- Ehdr.e_flags = Flags;
- Ehdr.e_ehsize = sizeof(Elf_Ehdr);
- Ehdr.e_phentsize = sizeof(Elf_Phdr);
- Ehdr.e_phnum = Segments.size();
- Ehdr.e_shentsize = sizeof(Elf_Shdr);
- Ehdr.e_shnum = Sections.size() + 1;
- Ehdr.e_shstrndx = SectionNames->Index;
-}
-
-template <class ELFT>
-void Object<ELFT>::writeProgramHeaders(FileOutputBuffer &Out) const {
- for (auto &Phdr : Segments)
- Phdr->template writeHeader<ELFT>(Out);
-}
-
-template <class ELFT>
-void Object<ELFT>::writeSectionHeaders(FileOutputBuffer &Out) const {
- uint8_t *Buf = Out.getBufferStart() + SHOffset;
- // This reference serves to write the dummy section header at the begining
- // of the file.
- Elf_Shdr &Shdr = *reinterpret_cast<Elf_Shdr *>(Buf);
- 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;
- Shdr.sh_info = 0;
- Shdr.sh_addralign = 0;
- Shdr.sh_entsize = 0;
-
- for (auto &Section : Sections)
- Section->template writeHeader<ELFT>(Out);
-}
-
-template <class ELFT>
-void Object<ELFT>::writeSectionData(FileOutputBuffer &Out) const {
- for (auto &Section : Sections)
- Section->writeSection(Out);
-}
-
-template <class ELFT> void Object<ELFT>::write(FileOutputBuffer &Out) {
- writeHeader(Out);
- writeProgramHeaders(Out);
- writeSectionData(Out);
- writeSectionHeaders(Out);
-}
-
-template class Object<ELF64LE>;
-template class Object<ELF64BE>;
-template class Object<ELF32LE>;
-template class Object<ELF32BE>;
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