/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "elf_file.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "utils.h"
namespace art {
ElfFile::ElfFile()
: file_(NULL),
writable_(false),
program_header_only_(false),
header_(NULL),
base_address_(NULL),
program_headers_start_(NULL),
section_headers_start_(NULL),
dynamic_program_header_(NULL),
dynamic_section_start_(NULL),
symtab_section_start_(NULL),
dynsym_section_start_(NULL),
strtab_section_start_(NULL),
dynstr_section_start_(NULL),
hash_section_start_(NULL),
symtab_symbol_table_(NULL),
dynsym_symbol_table_(NULL) {}
ElfFile* ElfFile::Open(File* file, bool writable, bool program_header_only) {
UniquePtr<ElfFile> elf_file(new ElfFile());
if (!elf_file->Setup(file, writable, program_header_only)) {
return NULL;
}
return elf_file.release();
}
bool ElfFile::Setup(File* file, bool writable, bool program_header_only) {
CHECK(file != NULL);
file_ = file;
writable_ = writable;
program_header_only_ = program_header_only;
int prot;
int flags;
if (writable_) {
prot = PROT_READ | PROT_WRITE;
flags = MAP_SHARED;
} else {
prot = PROT_READ;
flags = MAP_PRIVATE;
}
int64_t file_length = file_->GetLength();
if (file_length < 0) {
errno = -file_length;
PLOG(WARNING) << "Failed to get length of file: " << file_->GetPath() << " fd=" << file_->Fd();
return false;
}
if (file_length < sizeof(llvm::ELF::Elf32_Ehdr)) {
if (writable) {
LOG(WARNING) << "File size of " << file_length
<< " bytes not large enough to contain ELF header of "
<< sizeof(llvm::ELF::Elf32_Ehdr) << " bytes: " << file_->GetPath();
}
return false;
}
if (program_header_only) {
// first just map ELF header to get program header size information
size_t elf_header_size = sizeof(llvm::ELF::Elf32_Ehdr);
if (!SetMap(MemMap::MapFile(elf_header_size, prot, flags, file_->Fd(), 0))) {
return false;
}
// then remap to cover program header
size_t program_header_size = header_->e_phoff + (header_->e_phentsize * header_->e_phnum);
if (file_length < program_header_size) {
LOG(WARNING) << "File size of " << file_length
<< " bytes not large enough to contain ELF program header of "
<< program_header_size << " bytes: " << file_->GetPath();
return false;
}
if (!SetMap(MemMap::MapFile(program_header_size, prot, flags, file_->Fd(), 0))) {
LOG(WARNING) << "Failed to map ELF program headers: " << file_->GetPath();
return false;
}
} else {
// otherwise map entire file
if (!SetMap(MemMap::MapFile(file_->GetLength(), prot, flags, file_->Fd(), 0))) {
LOG(WARNING) << "Failed to map ELF file: " << file_->GetPath();
return false;
}
}
// Either way, the program header is relative to the elf header
program_headers_start_ = Begin() + GetHeader().e_phoff;
if (!program_header_only) {
// Setup section headers.
section_headers_start_ = Begin() + GetHeader().e_shoff;
// Find .dynamic section info from program header
dynamic_program_header_ = FindProgamHeaderByType(llvm::ELF::PT_DYNAMIC);
if (dynamic_program_header_ == NULL) {
LOG(WARNING) << "Failed to find PT_DYNAMIC program header in ELF file: " << file_->GetPath();
return false;
}
dynamic_section_start_
= reinterpret_cast<llvm::ELF::Elf32_Dyn*>(Begin() + GetDynamicProgramHeader().p_offset);
// Find other sections from section headers
for (llvm::ELF::Elf32_Word i = 0; i < GetSectionHeaderNum(); i++) {
llvm::ELF::Elf32_Shdr& section_header = GetSectionHeader(i);
byte* section_addr = Begin() + section_header.sh_offset;
switch (section_header.sh_type) {
case llvm::ELF::SHT_SYMTAB: {
symtab_section_start_ = reinterpret_cast<llvm::ELF::Elf32_Sym*>(section_addr);
break;
}
case llvm::ELF::SHT_DYNSYM: {
dynsym_section_start_ = reinterpret_cast<llvm::ELF::Elf32_Sym*>(section_addr);
break;
}
case llvm::ELF::SHT_STRTAB: {
// TODO: base these off of sh_link from .symtab and .dynsym above
if ((section_header.sh_flags & llvm::ELF::SHF_ALLOC) != 0) {
dynstr_section_start_ = reinterpret_cast<char*>(section_addr);
} else {
strtab_section_start_ = reinterpret_cast<char*>(section_addr);
}
break;
}
case llvm::ELF::SHT_DYNAMIC: {
if (reinterpret_cast<byte*>(dynamic_section_start_) != section_addr) {
LOG(WARNING) << "Failed to find matching SHT_DYNAMIC for PT_DYNAMIC in "
<< file_->GetPath() << ": " << std::hex
<< reinterpret_cast<void*>(dynamic_section_start_)
<< " != " << reinterpret_cast<void*>(section_addr);
return false;
}
break;
}
case llvm::ELF::SHT_HASH: {
hash_section_start_ = reinterpret_cast<llvm::ELF::Elf32_Word*>(section_addr);
break;
}
}
}
}
return true;
}
ElfFile::~ElfFile() {
STLDeleteElements(&segments_);
delete symtab_symbol_table_;
delete dynsym_symbol_table_;
}
bool ElfFile::SetMap(MemMap* map) {
if (map == NULL) {
// MemMap::Open should have already logged
return false;
}
map_.reset(map);
CHECK(map_.get() != NULL) << file_->GetPath();
CHECK(map_->Begin() != NULL) << file_->GetPath();
header_ = reinterpret_cast<llvm::ELF::Elf32_Ehdr*>(map_->Begin());
if ((llvm::ELF::ElfMagic[0] != header_->e_ident[llvm::ELF::EI_MAG0])
|| (llvm::ELF::ElfMagic[1] != header_->e_ident[llvm::ELF::EI_MAG1])
|| (llvm::ELF::ElfMagic[2] != header_->e_ident[llvm::ELF::EI_MAG2])
|| (llvm::ELF::ElfMagic[3] != header_->e_ident[llvm::ELF::EI_MAG3])) {
LOG(WARNING) << "Failed to find ELF magic in " << file_->GetPath()
<< ": " << std::hex
<< static_cast<uint8_t>(header_->e_ident[llvm::ELF::EI_MAG0])
<< static_cast<uint8_t>(header_->e_ident[llvm::ELF::EI_MAG1])
<< static_cast<uint8_t>(header_->e_ident[llvm::ELF::EI_MAG2])
<< static_cast<uint8_t>(header_->e_ident[llvm::ELF::EI_MAG3]);
return false;
}
// TODO: remove these static_casts from enum when using -std=gnu++0x
CHECK_EQ(static_cast<unsigned char>(llvm::ELF::ELFCLASS32), header_->e_ident[llvm::ELF::EI_CLASS]) << file_->GetPath();
CHECK_EQ(static_cast<unsigned char>(llvm::ELF::ELFDATA2LSB), header_->e_ident[llvm::ELF::EI_DATA]) << file_->GetPath();
CHECK_EQ(static_cast<unsigned char>(llvm::ELF::EV_CURRENT), header_->e_ident[llvm::ELF::EI_VERSION]) << file_->GetPath();
// TODO: remove these static_casts from enum when using -std=gnu++0x
CHECK_EQ(static_cast<llvm::ELF::Elf32_Half>(llvm::ELF::ET_DYN), header_->e_type) << file_->GetPath();
CHECK_EQ(static_cast<llvm::ELF::Elf32_Word>(llvm::ELF::EV_CURRENT), header_->e_version) << file_->GetPath();
CHECK_EQ(0U, header_->e_entry) << file_->GetPath();
CHECK_NE(0U, header_->e_phoff) << file_->GetPath();
CHECK_NE(0U, header_->e_shoff) << file_->GetPath();
CHECK_NE(0U, header_->e_ehsize) << file_->GetPath();
CHECK_NE(0U, header_->e_phentsize) << file_->GetPath();
CHECK_NE(0U, header_->e_phnum) << file_->GetPath();
CHECK_NE(0U, header_->e_shentsize) << file_->GetPath();
CHECK_NE(0U, header_->e_shnum) << file_->GetPath();
CHECK_NE(0U, header_->e_shstrndx) << file_->GetPath();
CHECK_GE(header_->e_shnum, header_->e_shstrndx) << file_->GetPath();
if (!program_header_only_) {
CHECK_GT(Size(), header_->e_phoff) << file_->GetPath();
CHECK_GT(Size(), header_->e_shoff) << file_->GetPath();
}
return true;
}
llvm::ELF::Elf32_Ehdr& ElfFile::GetHeader() {
CHECK(header_ != NULL);
return *header_;
}
byte* ElfFile::GetProgramHeadersStart() {
CHECK(program_headers_start_ != NULL);
return program_headers_start_;
}
byte* ElfFile::GetSectionHeadersStart() {
CHECK(section_headers_start_ != NULL);
return section_headers_start_;
}
llvm::ELF::Elf32_Phdr& ElfFile::GetDynamicProgramHeader() {
CHECK(dynamic_program_header_ != NULL);
return *dynamic_program_header_;
}
llvm::ELF::Elf32_Dyn* ElfFile::GetDynamicSectionStart() {
CHECK(dynamic_section_start_ != NULL);
return dynamic_section_start_;
}
llvm::ELF::Elf32_Sym* ElfFile::GetSymbolSectionStart(llvm::ELF::Elf32_Word section_type) {
CHECK(IsSymbolSectionType(section_type)) << file_->GetPath() << " " << section_type;
llvm::ELF::Elf32_Sym* symbol_section_start;
switch (section_type) {
case llvm::ELF::SHT_SYMTAB: {
symbol_section_start = symtab_section_start_;
break;
}
case llvm::ELF::SHT_DYNSYM: {
symbol_section_start = dynsym_section_start_;
break;
}
default: {
LOG(FATAL) << section_type;
symbol_section_start = NULL;
}
}
CHECK(symbol_section_start != NULL);
return symbol_section_start;
}
const char* ElfFile::GetStringSectionStart(llvm::ELF::Elf32_Word section_type) {
CHECK(IsSymbolSectionType(section_type)) << file_->GetPath() << " " << section_type;
const char* string_section_start;
switch (section_type) {
case llvm::ELF::SHT_SYMTAB: {
string_section_start = strtab_section_start_;
break;
}
case llvm::ELF::SHT_DYNSYM: {
string_section_start = dynstr_section_start_;
break;
}
default: {
LOG(FATAL) << section_type;
string_section_start = NULL;
}
}
CHECK(string_section_start != NULL);
return string_section_start;
}
const char* ElfFile::GetString(llvm::ELF::Elf32_Word section_type, llvm::ELF::Elf32_Word i) {
CHECK(IsSymbolSectionType(section_type)) << file_->GetPath() << " " << section_type;
if (i == 0) {
return NULL;
}
const char* string_section_start = GetStringSectionStart(section_type);
const char* string = string_section_start + i;
return string;
}
llvm::ELF::Elf32_Word* ElfFile::GetHashSectionStart() {
CHECK(hash_section_start_ != NULL);
return hash_section_start_;
}
llvm::ELF::Elf32_Word ElfFile::GetHashBucketNum() {
return GetHashSectionStart()[0];
}
llvm::ELF::Elf32_Word ElfFile::GetHashChainNum() {
return GetHashSectionStart()[1];
}
llvm::ELF::Elf32_Word ElfFile::GetHashBucket(size_t i) {
CHECK_LT(i, GetHashBucketNum());
// 0 is nbucket, 1 is nchain
return GetHashSectionStart()[2 + i];
}
llvm::ELF::Elf32_Word ElfFile::GetHashChain(size_t i) {
CHECK_LT(i, GetHashChainNum());
// 0 is nbucket, 1 is nchain, & chains are after buckets
return GetHashSectionStart()[2 + GetHashBucketNum() + i];
}
llvm::ELF::Elf32_Word ElfFile::GetProgramHeaderNum() {
return GetHeader().e_phnum;
}
llvm::ELF::Elf32_Phdr& ElfFile::GetProgramHeader(llvm::ELF::Elf32_Word i) {
CHECK_LT(i, GetProgramHeaderNum()) << file_->GetPath();
byte* program_header = GetProgramHeadersStart() + (i * GetHeader().e_phentsize);
CHECK_LT(program_header, End()) << file_->GetPath();
return *reinterpret_cast<llvm::ELF::Elf32_Phdr*>(program_header);
}
llvm::ELF::Elf32_Phdr* ElfFile::FindProgamHeaderByType(llvm::ELF::Elf32_Word type) {
for (llvm::ELF::Elf32_Word i = 0; i < GetProgramHeaderNum(); i++) {
llvm::ELF::Elf32_Phdr& program_header = GetProgramHeader(i);
if (program_header.p_type == type) {
return &program_header;
}
}
return NULL;
}
llvm::ELF::Elf32_Word ElfFile::GetSectionHeaderNum() {
return GetHeader().e_shnum;
}
llvm::ELF::Elf32_Shdr& ElfFile::GetSectionHeader(llvm::ELF::Elf32_Word i) {
// Can only access arbitrary sections when we have the whole file, not just program header.
// Even if we Load(), it doesn't bring in all the sections.
CHECK(!program_header_only_) << file_->GetPath();
CHECK_LT(i, GetSectionHeaderNum()) << file_->GetPath();
byte* section_header = GetSectionHeadersStart() + (i * GetHeader().e_shentsize);
CHECK_LT(section_header, End()) << file_->GetPath();
return *reinterpret_cast<llvm::ELF::Elf32_Shdr*>(section_header);
}
llvm::ELF::Elf32_Shdr* ElfFile::FindSectionByType(llvm::ELF::Elf32_Word type) {
// Can only access arbitrary sections when we have the whole file, not just program header.
// We could change this to switch on known types if they were detected during loading.
CHECK(!program_header_only_) << file_->GetPath();
for (llvm::ELF::Elf32_Word i = 0; i < GetSectionHeaderNum(); i++) {
llvm::ELF::Elf32_Shdr& section_header = GetSectionHeader(i);
if (section_header.sh_type == type) {
return §ion_header;
}
}
return NULL;
}
// from bionic
static unsigned elfhash(const char *_name) {
const unsigned char *name = (const unsigned char *) _name;
unsigned h = 0, g;
while (*name) {
h = (h << 4) + *name++;
g = h & 0xf0000000;
h ^= g;
h ^= g >> 24;
}
return h;
}
llvm::ELF::Elf32_Shdr& ElfFile::GetSectionNameStringSection() {
return GetSectionHeader(GetHeader().e_shstrndx);
}
byte* ElfFile::FindDynamicSymbolAddress(const std::string& symbol_name) {
llvm::ELF::Elf32_Word hash = elfhash(symbol_name.c_str());
llvm::ELF::Elf32_Word bucket_index = hash % GetHashBucketNum();
llvm::ELF::Elf32_Word symbol_and_chain_index = GetHashBucket(bucket_index);
while (symbol_and_chain_index != 0 /* STN_UNDEF */) {
llvm::ELF::Elf32_Sym& symbol = GetSymbol(llvm::ELF::SHT_DYNSYM, symbol_and_chain_index);
const char* name = GetString(llvm::ELF::SHT_DYNSYM, symbol.st_name);
if (symbol_name == name) {
return base_address_ + symbol.st_value;
}
symbol_and_chain_index = GetHashChain(symbol_and_chain_index);
}
return NULL;
}
bool ElfFile::IsSymbolSectionType(llvm::ELF::Elf32_Word section_type) {
return ((section_type == llvm::ELF::SHT_SYMTAB) || (section_type == llvm::ELF::SHT_DYNSYM));
}
llvm::ELF::Elf32_Word ElfFile::GetSymbolNum(llvm::ELF::Elf32_Shdr& section_header) {
CHECK(IsSymbolSectionType(section_header.sh_type)) << file_->GetPath() << " " << section_header.sh_type;
CHECK_NE(0U, section_header.sh_entsize) << file_->GetPath();
return section_header.sh_size / section_header.sh_entsize;
}
llvm::ELF::Elf32_Sym& ElfFile::GetSymbol(llvm::ELF::Elf32_Word section_type,
llvm::ELF::Elf32_Word i) {
return *(GetSymbolSectionStart(section_type) + i);
}
ElfFile::SymbolTable** ElfFile::GetSymbolTable(llvm::ELF::Elf32_Word section_type) {
CHECK(IsSymbolSectionType(section_type)) << file_->GetPath() << " " << section_type;
switch (section_type) {
case llvm::ELF::SHT_SYMTAB: {
return &symtab_symbol_table_;
}
case llvm::ELF::SHT_DYNSYM: {
return &dynsym_symbol_table_;
}
default: {
LOG(FATAL) << section_type;
return NULL;
}
}
}
llvm::ELF::Elf32_Sym* ElfFile::FindSymbolByName(llvm::ELF::Elf32_Word section_type,
const std::string& symbol_name,
bool build_map) {
CHECK(!program_header_only_) << file_->GetPath();
CHECK(IsSymbolSectionType(section_type)) << file_->GetPath() << " " << section_type;
SymbolTable** symbol_table = GetSymbolTable(section_type);
if (*symbol_table != NULL || build_map) {
if (*symbol_table == NULL) {
DCHECK(build_map);
*symbol_table = new SymbolTable;
llvm::ELF::Elf32_Shdr* symbol_section = FindSectionByType(section_type);
CHECK(symbol_section != NULL) << file_->GetPath();
llvm::ELF::Elf32_Shdr& string_section = GetSectionHeader(symbol_section->sh_link);
for (uint32_t i = 0; i < GetSymbolNum(*symbol_section); i++) {
llvm::ELF::Elf32_Sym& symbol = GetSymbol(section_type, i);
unsigned char type = symbol.getType();
if (type == llvm::ELF::STT_NOTYPE) {
continue;
}
const char* name = GetString(string_section, symbol.st_name);
if (name == NULL) {
continue;
}
std::pair<SymbolTable::iterator, bool> result = (*symbol_table)->insert(std::make_pair(name, &symbol));
if (!result.second) {
// If a duplicate, make sure it has the same logical value. Seen on x86.
CHECK_EQ(symbol.st_value, result.first->second->st_value);
CHECK_EQ(symbol.st_size, result.first->second->st_size);
CHECK_EQ(symbol.st_info, result.first->second->st_info);
CHECK_EQ(symbol.st_other, result.first->second->st_other);
CHECK_EQ(symbol.st_shndx, result.first->second->st_shndx);
}
}
}
CHECK(*symbol_table != NULL);
SymbolTable::const_iterator it = (*symbol_table)->find(symbol_name);
if (it == (*symbol_table)->end()) {
return NULL;
}
return it->second;
}
// Fall back to linear search
llvm::ELF::Elf32_Shdr* symbol_section = FindSectionByType(section_type);
CHECK(symbol_section != NULL) << file_->GetPath();
llvm::ELF::Elf32_Shdr& string_section = GetSectionHeader(symbol_section->sh_link);
for (uint32_t i = 0; i < GetSymbolNum(*symbol_section); i++) {
llvm::ELF::Elf32_Sym& symbol = GetSymbol(section_type, i);
const char* name = GetString(string_section, symbol.st_name);
if (name == NULL) {
continue;
}
if (symbol_name == name) {
return &symbol;
}
}
return NULL;
}
llvm::ELF::Elf32_Addr ElfFile::FindSymbolAddress(llvm::ELF::Elf32_Word section_type,
const std::string& symbol_name,
bool build_map) {
llvm::ELF::Elf32_Sym* symbol = FindSymbolByName(section_type, symbol_name, build_map);
if (symbol == NULL) {
return 0;
}
return symbol->st_value;
}
const char* ElfFile::GetString(llvm::ELF::Elf32_Shdr& string_section, llvm::ELF::Elf32_Word i) {
CHECK(!program_header_only_) << file_->GetPath();
// TODO: remove this static_cast from enum when using -std=gnu++0x
CHECK_EQ(static_cast<llvm::ELF::Elf32_Word>(llvm::ELF::SHT_STRTAB), string_section.sh_type) << file_->GetPath();
CHECK_LT(i, string_section.sh_size) << file_->GetPath();
if (i == 0) {
return NULL;
}
byte* strings = Begin() + string_section.sh_offset;
byte* string = strings + i;
CHECK_LT(string, End()) << file_->GetPath();
return reinterpret_cast<const char*>(string);
}
llvm::ELF::Elf32_Word ElfFile::GetDynamicNum() {
return GetDynamicProgramHeader().p_filesz / sizeof(llvm::ELF::Elf32_Dyn);
}
llvm::ELF::Elf32_Dyn& ElfFile::GetDynamic(llvm::ELF::Elf32_Word i) {
CHECK_LT(i, GetDynamicNum()) << file_->GetPath();
return *(GetDynamicSectionStart() + i);
}
llvm::ELF::Elf32_Word ElfFile::FindDynamicValueByType(llvm::ELF::Elf32_Sword type) {
for (llvm::ELF::Elf32_Word i = 0; i < GetDynamicNum(); i++) {
llvm::ELF::Elf32_Dyn& elf_dyn = GetDynamic(i);
if (elf_dyn.d_tag == type) {
return elf_dyn.d_un.d_val;
}
}
return 0;
}
llvm::ELF::Elf32_Rel* ElfFile::GetRelSectionStart(llvm::ELF::Elf32_Shdr& section_header) {
CHECK(llvm::ELF::SHT_REL == section_header.sh_type) << file_->GetPath() << " " << section_header.sh_type;
return reinterpret_cast<llvm::ELF::Elf32_Rel*>(Begin() + section_header.sh_offset);
}
llvm::ELF::Elf32_Word ElfFile::GetRelNum(llvm::ELF::Elf32_Shdr& section_header) {
CHECK(llvm::ELF::SHT_REL == section_header.sh_type) << file_->GetPath() << " " << section_header.sh_type;
CHECK_NE(0U, section_header.sh_entsize) << file_->GetPath();
return section_header.sh_size / section_header.sh_entsize;
}
llvm::ELF::Elf32_Rel& ElfFile::GetRel(llvm::ELF::Elf32_Shdr& section_header, llvm::ELF::Elf32_Word i) {
CHECK(llvm::ELF::SHT_REL == section_header.sh_type) << file_->GetPath() << " " << section_header.sh_type;
CHECK_LT(i, GetRelNum(section_header)) << file_->GetPath();
return *(GetRelSectionStart(section_header) + i);
}
llvm::ELF::Elf32_Rela* ElfFile::GetRelaSectionStart(llvm::ELF::Elf32_Shdr& section_header) {
CHECK(llvm::ELF::SHT_RELA == section_header.sh_type) << file_->GetPath() << " " << section_header.sh_type;
return reinterpret_cast<llvm::ELF::Elf32_Rela*>(Begin() + section_header.sh_offset);
}
llvm::ELF::Elf32_Word ElfFile::GetRelaNum(llvm::ELF::Elf32_Shdr& section_header) {
CHECK(llvm::ELF::SHT_RELA == section_header.sh_type) << file_->GetPath() << " " << section_header.sh_type;
return section_header.sh_size / section_header.sh_entsize;
}
llvm::ELF::Elf32_Rela& ElfFile::GetRela(llvm::ELF::Elf32_Shdr& section_header,
llvm::ELF::Elf32_Word i) {
CHECK(llvm::ELF::SHT_RELA == section_header.sh_type) << file_->GetPath() << " " << section_header.sh_type;
CHECK_LT(i, GetRelaNum(section_header)) << file_->GetPath();
return *(GetRelaSectionStart(section_header) + i);
}
// Base on bionic phdr_table_get_load_size
size_t ElfFile::GetLoadedSize() {
llvm::ELF::Elf32_Addr min_vaddr = 0xFFFFFFFFu;
llvm::ELF::Elf32_Addr max_vaddr = 0x00000000u;
for (llvm::ELF::Elf32_Word i = 0; i < GetProgramHeaderNum(); i++) {
llvm::ELF::Elf32_Phdr& program_header = GetProgramHeader(i);
if (program_header.p_type != llvm::ELF::PT_LOAD) {
continue;
}
llvm::ELF::Elf32_Addr begin_vaddr = program_header.p_vaddr;
if (begin_vaddr < min_vaddr) {
min_vaddr = begin_vaddr;
}
llvm::ELF::Elf32_Addr end_vaddr = program_header.p_vaddr + program_header.p_memsz;
if (end_vaddr > max_vaddr) {
max_vaddr = end_vaddr;
}
}
min_vaddr = RoundDown(min_vaddr, kPageSize);
max_vaddr = RoundUp(max_vaddr, kPageSize);
CHECK_LT(min_vaddr, max_vaddr) << file_->GetPath();
size_t loaded_size = max_vaddr - min_vaddr;
return loaded_size;
}
bool ElfFile::Load(bool executable) {
// TODO: actually return false error
CHECK(program_header_only_) << file_->GetPath();
for (llvm::ELF::Elf32_Word i = 0; i < GetProgramHeaderNum(); i++) {
llvm::ELF::Elf32_Phdr& program_header = GetProgramHeader(i);
// Record .dynamic header information for later use
if (program_header.p_type == llvm::ELF::PT_DYNAMIC) {
dynamic_program_header_ = &program_header;
continue;
}
// Not something to load, move on.
if (program_header.p_type != llvm::ELF::PT_LOAD) {
continue;
}
// Found something to load.
// If p_vaddr is zero, it must be the first loadable segment,
// since they must be in order. Since it is zero, there isn't a
// specific address requested, so first request a contiguous chunk
// of required size for all segments, but with no
// permissions. We'll then carve that up with the proper
// permissions as we load the actual segments. If p_vaddr is
// non-zero, the segments require the specific address specified,
// which either was specified in the file because we already set
// base_address_ after the first zero segment).
int64_t file_length = file_->GetLength();
if (program_header.p_vaddr == 0) {
std::string reservation_name("ElfFile reservation for ");
reservation_name += file_->GetPath();
UniquePtr<MemMap> reserve(MemMap::MapAnonymous(reservation_name.c_str(),
NULL, GetLoadedSize(), PROT_NONE));
CHECK(reserve.get() != NULL) << file_->GetPath();
base_address_ = reserve->Begin();
segments_.push_back(reserve.release());
}
// empty segment, nothing to map
if (program_header.p_memsz == 0) {
continue;
}
byte* p_vaddr = base_address_ + program_header.p_vaddr;
int prot = 0;
if (executable && ((program_header.p_flags & llvm::ELF::PF_X) != 0)) {
prot |= PROT_EXEC;
}
if ((program_header.p_flags & llvm::ELF::PF_W) != 0) {
prot |= PROT_WRITE;
}
if ((program_header.p_flags & llvm::ELF::PF_R) != 0) {
prot |= PROT_READ;
}
int flags = MAP_FIXED;
if (writable_) {
prot |= PROT_WRITE;
flags |= MAP_SHARED;
} else {
flags |= MAP_PRIVATE;
}
if (file_length < (program_header.p_offset + program_header.p_memsz)) {
LOG(WARNING) << "File size of " << file_length
<< " bytes not large enough to contain ELF segment " << i
<< " of " << (program_header.p_offset + program_header.p_memsz)
<< " bytes: " << file_->GetPath();
return false;
}
UniquePtr<MemMap> segment(MemMap::MapFileAtAddress(p_vaddr,
program_header.p_memsz,
prot, flags, file_->Fd(),
program_header.p_offset,
true));
CHECK(segment.get() != NULL) << file_->GetPath();
CHECK_EQ(segment->Begin(), p_vaddr) << file_->GetPath();
segments_.push_back(segment.release());
}
// Now that we are done loading, .dynamic should be in memory to find .dynstr, .dynsym, .hash
dynamic_section_start_
= reinterpret_cast<llvm::ELF::Elf32_Dyn*>(base_address_ + GetDynamicProgramHeader().p_vaddr);
for (llvm::ELF::Elf32_Word i = 0; i < GetDynamicNum(); i++) {
llvm::ELF::Elf32_Dyn& elf_dyn = GetDynamic(i);
byte* d_ptr = base_address_ + elf_dyn.d_un.d_ptr;
switch (elf_dyn.d_tag) {
case llvm::ELF::DT_HASH: {
hash_section_start_ = reinterpret_cast<llvm::ELF::Elf32_Word*>(d_ptr);
break;
}
case llvm::ELF::DT_STRTAB: {
dynstr_section_start_ = reinterpret_cast<char*>(d_ptr);
break;
}
case llvm::ELF::DT_SYMTAB: {
dynsym_section_start_ = reinterpret_cast<llvm::ELF::Elf32_Sym*>(d_ptr);
break;
}
case llvm::ELF::DT_NULL: {
CHECK_EQ(GetDynamicNum(), i+1);
break;
}
}
}
return true;
}
} // namespace art