llvm-project/lld/lib/ReaderWriter/ELF/HeaderChunks.h

357 lines
11 KiB
C++

//===- lib/ReaderWriter/ELF/HeaderChunks.h --------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLD_READER_WRITER_ELF_HEADER_CHUNKS_H
#define LLD_READER_WRITER_ELF_HEADER_CHUNKS_H
#include "SegmentChunks.h"
#include "llvm/Object/ELF.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Format.h"
/// \brief An Header represents the Elf[32/64]_Ehdr structure at the
/// start of an ELF executable file.
namespace lld {
namespace elf {
template <class ELFT> class ELFHeader : public Chunk<ELFT> {
public:
typedef llvm::object::Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
ELFHeader(const ELFLinkingContext &);
void e_ident(int I, unsigned char C) { _eh.e_ident[I] = C; }
void e_type(uint16_t type) { _eh.e_type = type; }
void e_machine(uint16_t machine) { _eh.e_machine = machine; }
void e_version(uint32_t version) { _eh.e_version = version; }
void e_entry(int64_t entry) { _eh.e_entry = entry; }
void e_phoff(int64_t phoff) { _eh.e_phoff = phoff; }
void e_shoff(int64_t shoff) { _eh.e_shoff = shoff; }
void e_flags(uint32_t flags) { _eh.e_flags = flags; }
void e_ehsize(uint16_t ehsize) { _eh.e_ehsize = ehsize; }
void e_phentsize(uint16_t phentsize) { _eh.e_phentsize = phentsize; }
void e_phnum(uint16_t phnum) { _eh.e_phnum = phnum; }
void e_shentsize(uint16_t shentsize) { _eh.e_shentsize = shentsize; }
void e_shnum(uint16_t shnum) { _eh.e_shnum = shnum; }
void e_shstrndx(uint16_t shstrndx) { _eh.e_shstrndx = shstrndx; }
uint64_t fileSize() { return sizeof (Elf_Ehdr); }
static inline bool classof(const Chunk<ELFT> *c) {
return c->Kind() == Chunk<ELFT>::Kind::ELFHeader;
}
inline int getContentType() const { return Chunk<ELFT>::ContentType::Header; }
void write(ELFWriter *writer, TargetLayout<ELFT> &layout,
llvm::FileOutputBuffer &buffer);
virtual void doPreFlight() {}
void finalize() {}
private:
Elf_Ehdr _eh;
};
template <class ELFT>
ELFHeader<ELFT>::ELFHeader(const ELFLinkingContext &context)
: Chunk<ELFT>("elfhdr", Chunk<ELFT>::Kind::ELFHeader, context) {
this->_align2 = ELFT::Is64Bits ? 8 : 4;
this->_fsize = sizeof(Elf_Ehdr);
this->_msize = sizeof(Elf_Ehdr);
memset(_eh.e_ident, 0, llvm::ELF::EI_NIDENT);
e_ident(llvm::ELF::EI_MAG0, 0x7f);
e_ident(llvm::ELF::EI_MAG1, 'E');
e_ident(llvm::ELF::EI_MAG2, 'L');
e_ident(llvm::ELF::EI_MAG3, 'F');
e_ehsize(sizeof(Elf_Ehdr));
e_flags(0);
}
template <class ELFT>
void ELFHeader<ELFT>::write(ELFWriter *writer, TargetLayout<ELFT> &layout,
llvm::FileOutputBuffer &buffer) {
uint8_t *chunkBuffer = buffer.getBufferStart();
uint8_t *atomContent = chunkBuffer + this->fileOffset();
memcpy(atomContent, &_eh, fileSize());
}
/// \brief An ProgramHeader represents the Elf[32/64]_Phdr structure at the
/// start of an ELF executable file.
template<class ELFT>
class ProgramHeader : public Chunk<ELFT> {
public:
typedef llvm::object::Elf_Phdr_Impl<ELFT> Elf_Phdr;
typedef typename std::vector<Elf_Phdr *>::iterator PhIterT;
typedef typename std::reverse_iterator<PhIterT> ReversePhIterT;
/// \brief Find a program header entry, given the type of entry that
/// we are looking for
class FindPhdr {
public:
FindPhdr(uint64_t type, uint64_t flags, uint64_t flagsClear)
: _type(type)
, _flags(flags)
, _flagsClear(flagsClear) {
}
bool operator()(const llvm::object::Elf_Phdr_Impl<ELFT> *j) const {
return ((j->p_type == _type) &&
((j->p_flags & _flags) == _flags) &&
(!(j->p_flags & _flagsClear)));
}
private:
uint64_t _type;
uint64_t _flags;
uint64_t _flagsClear;
};
ProgramHeader(const ELFLinkingContext &context)
: Chunk<ELFT>("elfphdr", Chunk<ELFT>::Kind::ProgramHeader, context) {
this->_align2 = ELFT::Is64Bits ? 8 : 4;
resetProgramHeaders();
}
bool addSegment(Segment<ELFT> *segment);
void resetProgramHeaders() { _phi = _ph.begin(); }
uint64_t fileSize() {
return sizeof(Elf_Phdr) * _ph.size();
}
static inline bool classof(const Chunk<ELFT> *c) {
return c->Kind() == Chunk<ELFT>::Kind::ProgramHeader;
}
void write(ELFWriter *writer, TargetLayout<ELFT> &layout,
llvm::FileOutputBuffer &buffer);
/// \brief find a program header entry in the list of program headers
ReversePhIterT
findProgramHeader(uint64_t type, uint64_t flags, uint64_t flagClear) {
return std::find_if(_ph.rbegin(), _ph.rend(),
FindPhdr(type, flags, flagClear));
}
PhIterT begin() {
return _ph.begin();
}
PhIterT end() {
return _ph.end();
}
ReversePhIterT rbegin() { return _ph.rbegin(); }
ReversePhIterT rend() { return _ph.rend(); }
virtual void doPreFlight() {}
void finalize() {}
int64_t entsize() { return sizeof(Elf_Phdr); }
int64_t numHeaders() {
return _ph.size();
}
inline int getContentType() const { return Chunk<ELFT>::ContentType::Header; }
private:
Elf_Phdr *allocateProgramHeader(bool &allocatedNew) {
Elf_Phdr *phdr;
if (_phi == _ph.end()) {
phdr = new (_allocator) Elf_Phdr;
_ph.push_back(phdr);
_phi = _ph.end();
allocatedNew = true;
} else {
phdr = (*_phi);
++_phi;
}
return phdr;
}
std::vector<Elf_Phdr *> _ph;
PhIterT _phi;
llvm::BumpPtrAllocator _allocator;
};
template <class ELFT>
bool ProgramHeader<ELFT>::addSegment(Segment<ELFT> *segment) {
bool allocatedNew = false;
ELFLinkingContext::OutputMagic outputMagic = this->_context.getOutputMagic();
// For segments that are not a loadable segment, we
// just pick the values directly from the segment as there
// wouldnt be any slices within that
if (segment->segmentType() != llvm::ELF::PT_LOAD) {
Elf_Phdr *phdr = allocateProgramHeader(allocatedNew);
phdr->p_type = segment->segmentType();
phdr->p_offset = segment->fileOffset();
phdr->p_vaddr = segment->virtualAddr();
phdr->p_paddr = segment->virtualAddr();
phdr->p_filesz = segment->fileSize();
phdr->p_memsz = segment->memSize();
phdr->p_flags = segment->flags();
phdr->p_align = segment->align2();
this->_fsize = fileSize();
this->_msize = this->_fsize;
return allocatedNew;
}
// For all other segments, use the slice
// to derive program headers
for (auto slice : segment->slices()) {
Elf_Phdr *phdr = allocateProgramHeader(allocatedNew);
phdr->p_type = segment->segmentType();
phdr->p_offset = slice->fileOffset();
phdr->p_vaddr = slice->virtualAddr();
phdr->p_paddr = slice->virtualAddr();
phdr->p_filesz = slice->fileSize();
phdr->p_memsz = slice->memSize();
phdr->p_flags = segment->flags();
if (outputMagic != ELFLinkingContext::OutputMagic::NMAGIC &&
outputMagic != ELFLinkingContext::OutputMagic::OMAGIC)
phdr->p_align = (phdr->p_type == llvm::ELF::PT_LOAD) ? segment->pageSize()
: slice->align2();
else
phdr->p_align = slice->align2();
}
this->_fsize = fileSize();
this->_msize = this->_fsize;
return allocatedNew;
}
template <class ELFT>
void ProgramHeader<ELFT>::write(ELFWriter *writer, TargetLayout<ELFT> &layout,
llvm::FileOutputBuffer &buffer) {
uint8_t *chunkBuffer = buffer.getBufferStart();
uint8_t *dest = chunkBuffer + this->fileOffset();
for (auto phi : _ph) {
memcpy(dest, phi, sizeof(Elf_Phdr));
dest += sizeof(Elf_Phdr);
}
}
/// \brief An SectionHeader represents the Elf[32/64]_Shdr structure
/// at the end of the file
template<class ELFT>
class SectionHeader : public Chunk<ELFT> {
public:
typedef llvm::object::Elf_Shdr_Impl<ELFT> Elf_Shdr;
SectionHeader(const ELFLinkingContext &, int32_t order);
void appendSection(MergedSections<ELFT> *section);
void updateSection(Section<ELFT> *section);
static inline bool classof(const Chunk<ELFT> *c) {
return c->getChunkKind() == Chunk<ELFT>::Kind::SectionHeader;
}
void setStringSection(StringTable<ELFT> *s) {
_stringSection = s;
}
void write(ELFWriter *writer, TargetLayout<ELFT> &layout,
llvm::FileOutputBuffer &buffer);
virtual void doPreFlight() {}
void finalize() {}
inline uint64_t fileSize() { return sizeof(Elf_Shdr) * _sectionInfo.size(); }
inline uint64_t entsize() {
return sizeof(Elf_Shdr);
}
inline int getContentType() const { return Chunk<ELFT>::ContentType::Header; }
inline uint64_t numHeaders() {
return _sectionInfo.size();
}
private:
StringTable<ELFT> *_stringSection;
std::vector<Elf_Shdr*> _sectionInfo;
llvm::BumpPtrAllocator _sectionAllocate;
};
template <class ELFT>
SectionHeader<ELFT>::SectionHeader(const ELFLinkingContext &context,
int32_t order)
: Chunk<ELFT>("shdr", Chunk<ELFT>::Kind::SectionHeader, context) {
this->_fsize = 0;
this->_align2 = 8;
this->setOrder(order);
// The first element in the list is always NULL
Elf_Shdr *nullshdr = new (_sectionAllocate.Allocate<Elf_Shdr>()) Elf_Shdr;
::memset(nullshdr, 0, sizeof (Elf_Shdr));
_sectionInfo.push_back(nullshdr);
this->_fsize += sizeof (Elf_Shdr);
}
template<class ELFT>
void
SectionHeader<ELFT>::appendSection(MergedSections<ELFT> *section) {
Elf_Shdr *shdr = new (_sectionAllocate.Allocate<Elf_Shdr>()) Elf_Shdr;
shdr->sh_name = _stringSection->addString(section->name());
shdr->sh_type = section->type();
shdr->sh_flags = section->flags();
shdr->sh_offset = section->fileOffset();
shdr->sh_addr = section->virtualAddr();
if (section->isLoadableSection())
shdr->sh_size = section->memSize();
else
shdr->sh_size = section->fileSize();
shdr->sh_link = section->link();
shdr->sh_info = section->shinfo();
shdr->sh_addralign = section->align2();
shdr->sh_entsize = section->entsize();
_sectionInfo.push_back(shdr);
}
template<class ELFT>
void
SectionHeader<ELFT>::updateSection(Section<ELFT> *section) {
Elf_Shdr *shdr = _sectionInfo[section->ordinal()];
shdr->sh_type = section->getType();
shdr->sh_flags = section->getFlags();
shdr->sh_offset = section->fileOffset();
shdr->sh_addr = section->virtualAddr();
shdr->sh_size = section->fileSize();
shdr->sh_link = section->getLink();
shdr->sh_info = section->getInfo();
shdr->sh_addralign = section->align2();
shdr->sh_entsize = section->getEntSize();
}
template <class ELFT>
void SectionHeader<ELFT>::write(ELFWriter *writer, TargetLayout<ELFT> &layout,
llvm::FileOutputBuffer &buffer) {
uint8_t *chunkBuffer = buffer.getBufferStart();
uint8_t *dest = chunkBuffer + this->fileOffset();
for (auto shi : _sectionInfo) {
memcpy(dest, shi, sizeof(Elf_Shdr));
dest += sizeof(Elf_Shdr);
}
_stringSection->write(writer, layout, buffer);
}
} // end namespace elf
} // end namespace lld
#endif