//===- ELFReader.tcc ------------------------------------------------------===//
//
// The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is the template implemenation of ELFReaders
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// ELFReader<32, true>
#include <cstring>
#include <vector>
/// constructor
ELFReader<32, true>::ELFReader(GNULDBackend& pBackend)
: ELFReaderIF(pBackend) {
}
/// destructor
ELFReader<32, true>::~ELFReader()
{
}
/// isELF - is this a ELF file
bool ELFReader<32, true>::isELF(void* pELFHeader) const
{
llvm::ELF::Elf32_Ehdr* hdr =
reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(pELFHeader);
if (0 == memcmp(llvm::ELF::ElfMagic, hdr, 4))
return true;
return false;
}
/// isMyEndian - is this ELF file in the same endian to me?
bool ELFReader<32, true>::isMyEndian(void* pELFHeader) const
{
llvm::ELF::Elf32_Ehdr* hdr =
reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(pELFHeader);
return (hdr->e_ident[llvm::ELF::EI_DATA] == llvm::ELF::ELFDATA2LSB);
}
/// isMyMachine - is this ELF file generated for the same machine.
bool ELFReader<32, true>::isMyMachine(void* pELFHeader) const
{
llvm::ELF::Elf32_Ehdr* hdr =
reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(pELFHeader);
if (llvm::sys::isLittleEndianHost())
return (hdr->e_machine == target().machine());
return (bswap16(hdr->e_machine) == target().machine());
}
/// fileType - return the file type
MCLDFile::Type ELFReader<32, true>::fileType(void* pELFHeader) const
{
llvm::ELF::Elf32_Ehdr* hdr =
reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(pELFHeader);
uint32_t type = 0x0;
if (llvm::sys::isLittleEndianHost())
type = hdr->e_type;
else
type = bswap16(hdr->e_type);
switch(type) {
case llvm::ELF::ET_REL:
return MCLDFile::Object;
case llvm::ELF::ET_EXEC:
return MCLDFile::Exec;
case llvm::ELF::ET_DYN:
return MCLDFile::DynObj;
case llvm::ELF::ET_CORE:
return MCLDFile::CoreFile;
case llvm::ELF::ET_NONE:
default:
return MCLDFile::Unknown;
}
}
/// readSectionHeaders - read ELF section header table and create LDSections
bool ELFReader<32, true>::readSectionHeaders(Input& pInput,
MCLinker& pLinker,
void* pELFHeader) const
{
llvm::ELF::Elf32_Ehdr* ehdr =
reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(pELFHeader);
uint32_t shoff = 0x0;
uint16_t shentsize = 0x0;
uint16_t shnum = 0x0;
uint16_t shstrtab = 0x0;
if (llvm::sys::isLittleEndianHost()) {
shoff = ehdr->e_shoff;
shentsize = ehdr->e_shentsize;
shnum = ehdr->e_shnum;
shstrtab = ehdr->e_shstrndx;
}
else {
shoff = bswap32(ehdr->e_shoff);
shentsize = bswap16(ehdr->e_shentsize);
shnum = bswap16(ehdr->e_shnum);
shstrtab = bswap16(ehdr->e_shstrndx);
}
// If the file has no section header table, e_shoff holds zero.
if (0x0 == shoff)
return true;
MemoryRegion* shdr_region = pInput.memArea()->request(
pInput.fileOffset() + shoff, shnum*shentsize);
llvm::ELF::Elf32_Shdr* shdrTab =
reinterpret_cast<llvm::ELF::Elf32_Shdr*>(shdr_region->start());
uint32_t sh_name = 0x0;
uint32_t sh_type = 0x0;
uint32_t sh_flags = 0x0;
uint32_t sh_offset = 0x0;
uint32_t sh_size = 0x0;
uint32_t sh_link = 0x0;
uint32_t sh_info = 0x0;
uint32_t sh_addralign = 0x0;
// get .shstrtab first
llvm::ELF::Elf32_Shdr* shdr = &shdrTab[shstrtab];
if (llvm::sys::isLittleEndianHost()) {
sh_offset = shdr->sh_offset;
sh_size = shdr->sh_size;
}
else {
sh_offset = bswap32(shdr->sh_offset);
sh_size = bswap32(shdr->sh_size);
}
MemoryRegion* sect_name_region = pInput.memArea()->request(
pInput.fileOffset() + sh_offset, sh_size);
const char* sect_name =
reinterpret_cast<const char*>(sect_name_region->start());
LinkInfoList link_info_list;
// create all LDSections
for (size_t idx = 0; idx < shnum; ++idx) {
if (llvm::sys::isLittleEndianHost()) {
sh_name = shdrTab[idx].sh_name;
sh_type = shdrTab[idx].sh_type;
sh_flags = shdrTab[idx].sh_flags;
sh_offset = shdrTab[idx].sh_offset;
sh_size = shdrTab[idx].sh_size;
sh_link = shdrTab[idx].sh_link;
sh_info = shdrTab[idx].sh_info;
sh_addralign = shdrTab[idx].sh_addralign;
}
else {
sh_name = bswap32(shdrTab[idx].sh_name);
sh_type = bswap32(shdrTab[idx].sh_type);
sh_flags = bswap32(shdrTab[idx].sh_flags);
sh_offset = bswap32(shdrTab[idx].sh_offset);
sh_size = bswap32(shdrTab[idx].sh_size);
sh_link = bswap32(shdrTab[idx].sh_link);
sh_info = bswap32(shdrTab[idx].sh_info);
sh_addralign = bswap32(shdrTab[idx].sh_addralign);
}
LDFileFormat::Kind kind = getLDSectionKind(sh_type,
sect_name+sh_name);
LDSection& section = pLinker.createSectHdr(sect_name+sh_name,
kind,
sh_type,
sh_flags);
section.setSize(sh_size);
section.setOffset(sh_offset);
section.setIndex(pInput.context()->numOfSections());
section.setInfo(sh_info);
section.setAlign(sh_addralign);
if (sh_link != 0x0 || sh_info != 0x0) {
LinkInfo link_info = { §ion, sh_link, sh_info };
link_info_list.push_back(link_info);
}
pInput.context()->getSectionTable().push_back(§ion);
} // end of for
// set up InfoLink
LinkInfoList::iterator info, infoEnd = link_info_list.end();
for (info = link_info_list.begin(); info != infoEnd; ++info) {
if (LDFileFormat::NamePool == info->section->kind() ||
LDFileFormat::Group == info->section->kind() ||
LDFileFormat::Note == info->section->kind()) {
info->section->setLink(pInput.context()->getSection(info->sh_link));
continue;
}
if (LDFileFormat::Relocation == info->section->kind()) {
info->section->setLink(pInput.context()->getSection(info->sh_info));
continue;
}
}
pInput.memArea()->release(shdr_region);
pInput.memArea()->release(sect_name_region);
return true;
}
/// readRegularSection - read a regular section and create fragments.
bool ELFReader<32, true>::readRegularSection(Input& pInput,
MCLinker& pLinker,
LDSection& pInputSectHdr) const
{
LDSection& out_sect = pLinker.getOrCreateOutputSectHdr(pInputSectHdr.name(),
pInputSectHdr.kind(),
pInputSectHdr.type(),
pInputSectHdr.flag());
MemoryRegion* region = pInput.memArea()->request(
pInput.fileOffset() + pInputSectHdr.offset(), pInputSectHdr.size());
SectionData& sect_data = pLinker.getOrCreateSectData(pInputSectHdr);
Fragment* frag = NULL;
if (NULL == region) {
// If the input section's size is zero, we got a NULL region.
// use a virtual fill fragment
frag = new FillFragment(0x0, 0, 0);
}
else
frag = new RegionFragment(*region);
uint64_t size = pLinker.getLayout().appendFragment(*frag,
sect_data,
pInputSectHdr.align());
out_sect.setSize(out_sect.size() + size);
return true;
}
/// readRegularSection - read a target section and create fragments.
bool ELFReader<32, true>::readTargetSection(Input& pInput,
MCLinker& pLinker,
LDSection& pInputSectHdr)
{
return target().readSection(pInput, pLinker, pInputSectHdr);
}
/// readSymbols - read ELF symbols and create LDSymbol
bool ELFReader<32, true>::readSymbols(Input& pInput,
MCLinker& pLinker,
const MemoryRegion& pRegion,
const char* pStrTab) const
{
// get number of symbols
size_t entsize = pRegion.size()/sizeof(llvm::ELF::Elf32_Sym);
const llvm::ELF::Elf32_Sym* symtab =
reinterpret_cast<const llvm::ELF::Elf32_Sym*>(pRegion.start());
uint32_t st_name = 0x0;
uint32_t st_value = 0x0;
uint32_t st_size = 0x0;
uint8_t st_info = 0x0;
uint8_t st_other = 0x0;
uint16_t st_shndx = 0x0;
// skip the first NULL symbol
pInput.context()->addSymbol(NULL);
for (size_t idx = 1; idx < entsize; ++idx) {
st_info = symtab[idx].st_info;
st_other = symtab[idx].st_other;
if (llvm::sys::isLittleEndianHost()) {
st_name = symtab[idx].st_name;
st_value = symtab[idx].st_value;
st_size = symtab[idx].st_size;
st_shndx = symtab[idx].st_shndx;
}
else {
st_name = bswap32(symtab[idx].st_name);
st_value = bswap32(symtab[idx].st_value);
st_size = bswap32(symtab[idx].st_size);
st_shndx = bswap16(symtab[idx].st_shndx);
}
// If the section should not be included, set the st_shndx SHN_UNDEF
// - A section in interrelated groups are not included.
if (pInput.type() == Input::Object &&
st_shndx < llvm::ELF::SHN_LORESERVE &&
st_shndx != llvm::ELF::SHN_UNDEF) {
if (NULL == pInput.context()->getSection(st_shndx))
st_shndx = llvm::ELF::SHN_UNDEF;
}
// get ld_type
ResolveInfo::Type ld_type = getSymType(st_info, st_shndx);
// get ld_desc
ResolveInfo::Desc ld_desc = getSymDesc(st_shndx, pInput);
// get ld_binding
ResolveInfo::Binding ld_binding = getSymBinding((st_info >> 4), st_shndx, st_other);
// get ld_value - ld_value must be section relative.
uint64_t ld_value = getSymValue(st_value, st_shndx, pInput);
// get the input fragment
FragmentRef* ld_frag_ref = getSymFragmentRef(pInput,
pLinker,
st_shndx,
ld_value);
// get ld_vis
ResolveInfo::Visibility ld_vis = getSymVisibility(st_other);
// get ld_name
llvm::StringRef ld_name;
if (ResolveInfo::Section == ld_type) {
// Section symbol's st_name is the section index.
LDSection* section = pInput.context()->getSection(st_shndx);
assert(NULL != section && "get a invalid section");
ld_name = llvm::StringRef(section->name());
}
else {
ld_name = llvm::StringRef(pStrTab + st_name);
}
// push into MCLinker
LDSymbol* input_sym = NULL;
if (pInput.type() == Input::Object) {
input_sym = pLinker.addSymbol<Input::Object>(ld_name,
ld_type,
ld_desc,
ld_binding,
st_size,
ld_value,
ld_frag_ref,
ld_vis);
// push into the input file
pInput.context()->addSymbol(input_sym);
continue;
}
else if (pInput.type() == Input::DynObj) {
input_sym = pLinker.addSymbol<Input::DynObj>(ld_name,
ld_type,
ld_desc,
ld_binding,
st_size,
ld_value,
ld_frag_ref,
ld_vis);
continue;
}
} // end of for loop
return true;
}
/// readSymbol - read a symbol from the given Input and index in symtab
/// This is used to get the signature of a group section.
ResolveInfo* ELFReader<32, true>::readSymbol(Input& pInput,
LDSection& pSymTab,
MCLDInfo& pLDInfo,
uint32_t pSymIdx) const
{
LDSection* symtab = &pSymTab;
LDSection* strtab = symtab->getLink();
assert(NULL != symtab && NULL != strtab);
uint32_t offset = pInput.fileOffset() + symtab->offset() +
sizeof(llvm::ELF::Elf32_Sym) * pSymIdx;
MemoryRegion* symbol_region =
pInput.memArea()->request(offset, sizeof(llvm::ELF::Elf32_Sym));
llvm::ELF::Elf32_Sym* entry =
reinterpret_cast<llvm::ELF::Elf32_Sym*>(symbol_region->start());
uint32_t st_name = 0x0;
uint32_t st_size = 0x0;
uint8_t st_info = 0x0;
uint8_t st_other = 0x0;
uint16_t st_shndx = 0x0;
st_info = entry->st_info;
st_other = entry->st_other;
if (llvm::sys::isLittleEndianHost()) {
st_name = entry->st_name;
st_size = entry->st_size;
st_shndx = entry->st_shndx;
}
else {
st_name = bswap32(entry->st_name);
st_size = bswap32(entry->st_size);
st_shndx = bswap16(entry->st_shndx);
}
MemoryRegion* strtab_region = pInput.memArea()->request(
pInput.fileOffset() + strtab->offset(), strtab->size());
// get ld_name
llvm::StringRef ld_name(
reinterpret_cast<char*>(strtab_region->start() + st_name));
// get ld_type
ResolveInfo::Type ld_type = static_cast<ResolveInfo::Type>(st_info & 0xF);
// get ld_desc
ResolveInfo::Desc ld_desc = getSymDesc(st_shndx, pInput);
// get ld_binding
ResolveInfo::Binding ld_binding =
getSymBinding((st_info >> 4), st_shndx, st_other);
// get ld_vis
ResolveInfo::Visibility ld_vis = getSymVisibility(st_other);
ResolveInfo* result =
pLDInfo.getNamePool().createSymbol(ld_name,
(pInput.type() == Input::DynObj),
ld_type,
ld_desc,
ld_binding,
st_size,
ld_vis);
// release regions
pInput.memArea()->release(symbol_region);
pInput.memArea()->release(strtab_region);
return result;
}
/// readRela - read ELF rela and create Relocation
bool ELFReader<32, true>::readRela(Input& pInput,
MCLinker& pLinker,
LDSection& pSection,
const MemoryRegion& pRegion) const
{
// get the number of rela
size_t entsize = pRegion.size() / sizeof(llvm::ELF::Elf32_Rela);
const llvm::ELF::Elf32_Rela* relaTab =
reinterpret_cast<const llvm::ELF::Elf32_Rela*>(pRegion.start());
for (size_t idx=0; idx < entsize; ++idx) {
uint32_t r_offset = 0x0;
uint32_t r_info = 0x0;
int32_t r_addend = 0;
if (llvm::sys::isLittleEndianHost()) {
r_offset = relaTab[idx].r_offset;
r_info = relaTab[idx].r_info;
r_addend = relaTab[idx].r_addend;
}
else {
r_offset = bswap32(relaTab[idx].r_offset);
r_info = bswap32(relaTab[idx].r_info);
r_addend = bswap32(relaTab[idx].r_addend);
}
uint8_t r_type = static_cast<unsigned char>(r_info);
uint32_t r_sym = (r_info >> 8);
LDSymbol* symbol = pInput.context()->getSymbol(r_sym);
if (NULL == symbol)
fatal(diag::err_cannot_read_symbol) << r_sym << pInput.path();
ResolveInfo* resolve_info = symbol->resolveInfo();
FragmentRef* frag_ref =
pLinker.getLayout().getFragmentRef(*pSection.getLink(), r_offset);
if (NULL == frag_ref) {
fatal(diag::err_cannot_read_relocated_section)
<< pSection.name()
<< pSection.getLink()->index()
<< pInput.path();
}
pLinker.addRelocation(r_type, *symbol, *resolve_info, *frag_ref, pSection, r_addend);
}
return true;
}
/// readRel - read ELF rel and create Relocation
bool ELFReader<32, true>::readRel(Input& pInput,
MCLinker& pLinker,
LDSection& pSection,
const MemoryRegion& pRegion) const
{
// get the number of rel
size_t entsize = pRegion.size() / sizeof(llvm::ELF::Elf32_Rel);
const llvm::ELF::Elf32_Rel* relTab =
reinterpret_cast<const llvm::ELF::Elf32_Rel*>(pRegion.start());
for (size_t idx=0; idx < entsize; ++idx) {
uint32_t r_offset = 0x0;
uint32_t r_info = 0x0;
if (llvm::sys::isLittleEndianHost()) {
r_offset = relTab[idx].r_offset;
r_info = relTab[idx].r_info;
}
else {
r_offset = bswap32(relTab[idx].r_offset);
r_info = bswap32(relTab[idx].r_info);
}
uint8_t r_type = static_cast<unsigned char>(r_info);
uint32_t r_sym = (r_info >> 8);
LDSymbol* symbol = pInput.context()->getSymbol(r_sym);
if (NULL == symbol) {
fatal(diag::err_cannot_read_symbol) << r_sym << pInput.path();
}
ResolveInfo* resolve_info = symbol->resolveInfo();
FragmentRef* frag_ref =
pLinker.getLayout().getFragmentRef(*pSection.getLink(), r_offset);
if (NULL == frag_ref) {
fatal(diag::err_cannot_read_relocated_section)
<< pSection.name()
<< pSection.getLink()->index()
<< pInput.path();
}
pLinker.addRelocation(r_type, *symbol, *resolve_info, *frag_ref, pSection);
}
return true;
}
/// readDynamic - read ELF .dynamic in input dynobj
bool ELFReader<32, true>::readDynamic(Input& pInput) const
{
assert(pInput.type() == Input::DynObj);
const LDSection* dynamic_sect = pInput.context()->getSection(".dynamic");
if (NULL == dynamic_sect) {
fatal(diag::err_cannot_read_section) << ".dynamic";
}
const LDSection* dynstr_sect = dynamic_sect->getLink();
if (NULL == dynstr_sect) {
fatal(diag::err_cannot_read_section) << ".dynstr";
}
MemoryRegion* dynamic_region = pInput.memArea()->request(
pInput.fileOffset() + dynamic_sect->offset(), dynamic_sect->size());
MemoryRegion* dynstr_region = pInput.memArea()->request(
pInput.fileOffset() + dynstr_sect->offset(), dynstr_sect->size());
assert(NULL != dynamic_region && NULL != dynstr_region);
const llvm::ELF::Elf32_Dyn* dynamic =
(llvm::ELF::Elf32_Dyn*) dynamic_region->start();
const char* dynstr = (const char*) dynstr_region->start();
bool hasSOName = false;
size_t numOfEntries = dynamic_sect->size() / sizeof(llvm::ELF::Elf32_Dyn);
for (size_t idx = 0; idx < numOfEntries; ++idx) {
llvm::ELF::Elf32_Sword d_tag = 0x0;
llvm::ELF::Elf32_Word d_val = 0x0;
if (llvm::sys::isLittleEndianHost()) {
d_tag = dynamic[idx].d_tag;
d_val = dynamic[idx].d_un.d_val;
} else {
d_tag = bswap32(dynamic[idx].d_tag);
d_val = bswap32(dynamic[idx].d_un.d_val);
}
switch (d_tag) {
case llvm::ELF::DT_SONAME:
assert(d_val < dynstr_sect->size());
pInput.setSOName(dynstr + d_val);
hasSOName = true;
break;
case llvm::ELF::DT_NEEDED:
// TODO:
break;
case llvm::ELF::DT_NULL:
default:
break;
}
}
// if there is no SONAME in .dynamic, then set it from input path
if (!hasSOName)
pInput.setSOName(pInput.path().native());
pInput.memArea()->release(dynamic_region);
pInput.memArea()->release(dynstr_region);
return true;
}