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/*
* 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_writer_quick.h"
#include "base/logging.h"
#include "base/unix_file/fd_file.h"
#include "buffered_output_stream.h"
#include "driver/compiler_driver.h"
#include "elf_utils.h"
#include "file_output_stream.h"
#include "globals.h"
#include "oat.h"
#include "oat_writer.h"
#include "utils.h"
namespace art {
static constexpr Elf32_Word NextOffset(const Elf32_Shdr& cur, const Elf32_Shdr& prev) {
return RoundUp(prev.sh_size + prev.sh_offset, cur.sh_addralign);
}
static uint8_t MakeStInfo(uint8_t binding, uint8_t type) {
return ((binding) << 4) + ((type) & 0xf);
}
bool ElfWriterQuick::ElfBuilder::Write() {
// The basic layout of the elf file. Order may be different in final output.
// +-------------------------+
// | Elf32_Ehdr |
// +-------------------------+
// | Elf32_Phdr PHDR |
// | Elf32_Phdr LOAD R | .dynsym .dynstr .hash .rodata
// | Elf32_Phdr LOAD R X | .text
// | Elf32_Phdr LOAD RW | .dynamic
// | Elf32_Phdr DYNAMIC | .dynamic
// +-------------------------+
// | .dynsym |
// | Elf32_Sym STN_UNDEF |
// | Elf32_Sym oatdata |
// | Elf32_Sym oatexec |
// | Elf32_Sym oatlastword |
// +-------------------------+
// | .dynstr |
// | \0 |
// | oatdata\0 |
// | oatexec\0 |
// | oatlastword\0 |
// | boot.oat\0 |
// +-------------------------+
// | .hash |
// | Elf32_Word nbucket = b |
// | Elf32_Word nchain = c |
// | Elf32_Word bucket[0] |
// | ... |
// | Elf32_Word bucket[b - 1]|
// | Elf32_Word chain[0] |
// | ... |
// | Elf32_Word chain[c - 1] |
// +-------------------------+
// | .rodata |
// | oatdata..oatexec-4 |
// +-------------------------+
// | .text |
// | oatexec..oatlastword |
// +-------------------------+
// | .dynamic |
// | Elf32_Dyn DT_SONAME |
// | Elf32_Dyn DT_HASH |
// | Elf32_Dyn DT_SYMTAB |
// | Elf32_Dyn DT_SYMENT |
// | Elf32_Dyn DT_STRTAB |
// | Elf32_Dyn DT_STRSZ |
// | Elf32_Dyn DT_NULL |
// +-------------------------+ (Optional)
// | .strtab | (Optional)
// | program symbol names | (Optional)
// +-------------------------+ (Optional)
// | .symtab | (Optional)
// | program symbols | (Optional)
// +-------------------------+
// | .shstrtab |
// | \0 |
// | .dynamic\0 |
// | .dynsym\0 |
// | .dynstr\0 |
// | .hash\0 |
// | .rodata\0 |
// | .text\0 |
// | .shstrtab\0 |
// | .symtab\0 | (Optional)
// | .strtab\0 | (Optional)
// | .debug_str\0 | (Optional)
// | .debug_info\0 | (Optional)
// | .debug_frame\0 | (Optional)
// | .debug_abbrev\0 | (Optional)
// +-------------------------+ (Optional)
// | .debug_str | (Optional)
// +-------------------------+ (Optional)
// | .debug_info | (Optional)
// +-------------------------+ (Optional)
// | .debug_frame | (Optional)
// +-------------------------+ (Optional)
// | .debug_abbrev | (Optional)
// +-------------------------+
// | Elf32_Shdr NULL |
// | Elf32_Shdr .dynsym |
// | Elf32_Shdr .dynstr |
// | Elf32_Shdr .hash |
// | Elf32_Shdr .text |
// | Elf32_Shdr .rodata |
// | Elf32_Shdr .dynamic |
// | Elf32_Shdr .shstrtab |
// | Elf32_Shdr .debug_str | (Optional)
// | Elf32_Shdr .debug_info | (Optional)
// | Elf32_Shdr .debug_frame | (Optional)
// | Elf32_Shdr .debug_abbrev| (Optional)
// +-------------------------+
if (fatal_error_) {
return false;
}
// Step 1. Figure out all the offsets.
// What phdr is.
uint32_t phdr_offset = sizeof(Elf32_Ehdr);
const uint8_t PH_PHDR = 0;
const uint8_t PH_LOAD_R__ = 1;
const uint8_t PH_LOAD_R_X = 2;
const uint8_t PH_LOAD_RW_ = 3;
const uint8_t PH_DYNAMIC = 4;
const uint8_t PH_NUM = 5;
uint32_t phdr_size = sizeof(Elf32_Phdr) * PH_NUM;
if (debug_logging_) {
LOG(INFO) << "phdr_offset=" << phdr_offset << std::hex << " " << phdr_offset;
LOG(INFO) << "phdr_size=" << phdr_size << std::hex << " " << phdr_size;
}
Elf32_Phdr program_headers[PH_NUM];
memset(&program_headers, 0, sizeof(program_headers));
program_headers[PH_PHDR].p_type = PT_PHDR;
program_headers[PH_PHDR].p_offset = phdr_offset;
program_headers[PH_PHDR].p_vaddr = phdr_offset;
program_headers[PH_PHDR].p_paddr = phdr_offset;
program_headers[PH_PHDR].p_filesz = sizeof(program_headers);
program_headers[PH_PHDR].p_memsz = sizeof(program_headers);
program_headers[PH_PHDR].p_flags = PF_R;
program_headers[PH_PHDR].p_align = sizeof(Elf32_Word);
program_headers[PH_LOAD_R__].p_type = PT_LOAD;
program_headers[PH_LOAD_R__].p_offset = 0;
program_headers[PH_LOAD_R__].p_vaddr = 0;
program_headers[PH_LOAD_R__].p_paddr = 0;
program_headers[PH_LOAD_R__].p_flags = PF_R;
program_headers[PH_LOAD_R_X].p_type = PT_LOAD;
program_headers[PH_LOAD_R_X].p_flags = PF_R | PF_X;
program_headers[PH_LOAD_RW_].p_type = PT_LOAD;
program_headers[PH_LOAD_RW_].p_flags = PF_R | PF_W;
program_headers[PH_DYNAMIC].p_type = PT_DYNAMIC;
program_headers[PH_DYNAMIC].p_flags = PF_R | PF_W;
// Get the dynstr string.
std::string dynstr(dynsym_builder_.GenerateStrtab());
// Add the SONAME to the dynstr.
uint32_t dynstr_soname_offset = dynstr.size();
std::string file_name(elf_file_->GetPath());
size_t directory_separator_pos = file_name.rfind('/');
if (directory_separator_pos != std::string::npos) {
file_name = file_name.substr(directory_separator_pos + 1);
}
dynstr += file_name;
dynstr += '\0';
if (debug_logging_) {
LOG(INFO) << "dynstr size (bytes) =" << dynstr.size()
<< std::hex << " " << dynstr.size();
LOG(INFO) << "dynsym size (elements)=" << dynsym_builder_.size()
<< std::hex << " " << dynsym_builder_.size();
}
// get the strtab
std::string strtab;
if (IncludingDebugSymbols()) {
strtab = symtab_builder_.GenerateStrtab();
if (debug_logging_) {
LOG(INFO) << "strtab size (bytes) =" << strtab.size()
<< std::hex << " " << strtab.size();
LOG(INFO) << "symtab size (elements) =" << symtab_builder_.size()
<< std::hex << " " << symtab_builder_.size();
}
}
// Get the section header string table.
std::vector<Elf32_Shdr*> section_ptrs;
std::string shstrtab;
shstrtab += '\0';
// Setup sym_undef
Elf32_Shdr null_hdr;
memset(&null_hdr, 0, sizeof(null_hdr));
null_hdr.sh_type = SHT_NULL;
null_hdr.sh_link = SHN_UNDEF;
section_ptrs.push_back(&null_hdr);
uint32_t section_index = 1;
// setup .dynsym
section_ptrs.push_back(&dynsym_builder_.section_);
AssignSectionStr(&dynsym_builder_, &shstrtab);
dynsym_builder_.section_index_ = section_index++;
// Setup .dynstr
section_ptrs.push_back(&dynsym_builder_.strtab_.section_);
AssignSectionStr(&dynsym_builder_.strtab_, &shstrtab);
dynsym_builder_.strtab_.section_index_ = section_index++;
// Setup .hash
section_ptrs.push_back(&hash_builder_.section_);
AssignSectionStr(&hash_builder_, &shstrtab);
hash_builder_.section_index_ = section_index++;
// Setup .rodata
section_ptrs.push_back(&rodata_builder_.section_);
AssignSectionStr(&rodata_builder_, &shstrtab);
rodata_builder_.section_index_ = section_index++;
// Setup .text
section_ptrs.push_back(&text_builder_.section_);
AssignSectionStr(&text_builder_, &shstrtab);
text_builder_.section_index_ = section_index++;
// Setup .dynamic
section_ptrs.push_back(&dynamic_builder_.section_);
AssignSectionStr(&dynamic_builder_, &shstrtab);
dynamic_builder_.section_index_ = section_index++;
if (IncludingDebugSymbols()) {
// Setup .symtab
section_ptrs.push_back(&symtab_builder_.section_);
AssignSectionStr(&symtab_builder_, &shstrtab);
symtab_builder_.section_index_ = section_index++;
// Setup .strtab
section_ptrs.push_back(&symtab_builder_.strtab_.section_);
AssignSectionStr(&symtab_builder_.strtab_, &shstrtab);
symtab_builder_.strtab_.section_index_ = section_index++;
}
ElfRawSectionBuilder* it = other_builders_.data();
for (uint32_t cnt = 0; cnt < other_builders_.size(); ++it, ++cnt) {
// Setup all the other sections.
section_ptrs.push_back(&it->section_);
AssignSectionStr(it, &shstrtab);
it->section_index_ = section_index++;
}
// Setup shstrtab
section_ptrs.push_back(&shstrtab_builder_.section_);
AssignSectionStr(&shstrtab_builder_, &shstrtab);
shstrtab_builder_.section_index_ = section_index++;
if (debug_logging_) {
LOG(INFO) << ".shstrtab size (bytes) =" << shstrtab.size()
<< std::hex << " " << shstrtab.size();
LOG(INFO) << "section list size (elements)=" << section_ptrs.size()
<< std::hex << " " << section_ptrs.size();
}
// Fill in the hash section.
std::vector<Elf32_Word> hash = dynsym_builder_.GenerateHashContents();
if (debug_logging_) {
LOG(INFO) << ".hash size (bytes)=" << hash.size() * sizeof(Elf32_Word)
<< std::hex << " " << hash.size() * sizeof(Elf32_Word);
}
Elf32_Word base_offset = sizeof(Elf32_Ehdr) + sizeof(program_headers);
std::vector<ElfFilePiece> pieces;
// Get the layout in the sections.
//
// Get the layout of the dynsym section.
dynsym_builder_.section_.sh_offset = RoundUp(base_offset, dynsym_builder_.section_.sh_addralign);
dynsym_builder_.section_.sh_addr = dynsym_builder_.section_.sh_offset;
dynsym_builder_.section_.sh_size = dynsym_builder_.size()*sizeof(Elf32_Sym);
dynsym_builder_.section_.sh_link = dynsym_builder_.GetLink();
// Get the layout of the dynstr section.
dynsym_builder_.strtab_.section_.sh_offset = NextOffset(dynsym_builder_.strtab_.section_,
dynsym_builder_.section_);
dynsym_builder_.strtab_.section_.sh_addr = dynsym_builder_.strtab_.section_.sh_offset;
dynsym_builder_.strtab_.section_.sh_size = dynstr.size();
dynsym_builder_.strtab_.section_.sh_link = dynsym_builder_.strtab_.GetLink();
// Get the layout of the hash section
hash_builder_.section_.sh_offset = NextOffset(hash_builder_.section_,
dynsym_builder_.strtab_.section_);
hash_builder_.section_.sh_addr = hash_builder_.section_.sh_offset;
hash_builder_.section_.sh_size = hash.size() * sizeof(Elf32_Word);
hash_builder_.section_.sh_link = hash_builder_.GetLink();
// Get the layout of the rodata section.
rodata_builder_.section_.sh_offset = NextOffset(rodata_builder_.section_,
hash_builder_.section_);
rodata_builder_.section_.sh_addr = rodata_builder_.section_.sh_offset;
rodata_builder_.section_.sh_size = rodata_builder_.size_;
rodata_builder_.section_.sh_link = rodata_builder_.GetLink();
// Get the layout of the text section.
text_builder_.section_.sh_offset = NextOffset(text_builder_.section_, rodata_builder_.section_);
text_builder_.section_.sh_addr = text_builder_.section_.sh_offset;
text_builder_.section_.sh_size = text_builder_.size_;
text_builder_.section_.sh_link = text_builder_.GetLink();
CHECK_ALIGNED(rodata_builder_.section_.sh_offset + rodata_builder_.section_.sh_size, kPageSize);
// Get the layout of the dynamic section.
dynamic_builder_.section_.sh_offset = NextOffset(dynamic_builder_.section_,
text_builder_.section_);
dynamic_builder_.section_.sh_addr = dynamic_builder_.section_.sh_offset;
dynamic_builder_.section_.sh_size = dynamic_builder_.size()*sizeof(Elf32_Dyn);
dynamic_builder_.section_.sh_link = dynamic_builder_.GetLink();
Elf32_Shdr prev = dynamic_builder_.section_;
if (IncludingDebugSymbols()) {
// Get the layout of the symtab section.
symtab_builder_.section_.sh_offset = NextOffset(symtab_builder_.section_,
dynamic_builder_.section_);
symtab_builder_.section_.sh_addr = 0;
// Add to leave space for the null symbol.
symtab_builder_.section_.sh_size = symtab_builder_.size()*sizeof(Elf32_Sym);
symtab_builder_.section_.sh_link = symtab_builder_.GetLink();
// Get the layout of the dynstr section.
symtab_builder_.strtab_.section_.sh_offset = NextOffset(symtab_builder_.strtab_.section_,
symtab_builder_.section_);
symtab_builder_.strtab_.section_.sh_addr = 0;
symtab_builder_.strtab_.section_.sh_size = strtab.size();
symtab_builder_.strtab_.section_.sh_link = symtab_builder_.strtab_.GetLink();
prev = symtab_builder_.strtab_.section_;
}
if (debug_logging_) {
LOG(INFO) << "dynsym off=" << dynsym_builder_.section_.sh_offset
<< " dynsym size=" << dynsym_builder_.section_.sh_size;
LOG(INFO) << "dynstr off=" << dynsym_builder_.strtab_.section_.sh_offset
<< " dynstr size=" << dynsym_builder_.strtab_.section_.sh_size;
LOG(INFO) << "hash off=" << hash_builder_.section_.sh_offset
<< " hash size=" << hash_builder_.section_.sh_size;
LOG(INFO) << "rodata off=" << rodata_builder_.section_.sh_offset
<< " rodata size=" << rodata_builder_.section_.sh_size;
LOG(INFO) << "text off=" << text_builder_.section_.sh_offset
<< " text size=" << text_builder_.section_.sh_size;
LOG(INFO) << "dynamic off=" << dynamic_builder_.section_.sh_offset
<< " dynamic size=" << dynamic_builder_.section_.sh_size;
if (IncludingDebugSymbols()) {
LOG(INFO) << "symtab off=" << symtab_builder_.section_.sh_offset
<< " symtab size=" << symtab_builder_.section_.sh_size;
LOG(INFO) << "strtab off=" << symtab_builder_.strtab_.section_.sh_offset
<< " strtab size=" << symtab_builder_.strtab_.section_.sh_size;
}
}
// Get the layout of the extra sections. (This will deal with the debug
// sections if they are there)
for (auto it = other_builders_.begin(); it != other_builders_.end(); ++it) {
it->section_.sh_offset = NextOffset(it->section_, prev);
it->section_.sh_addr = 0;
it->section_.sh_size = it->GetBuffer()->size();
it->section_.sh_link = it->GetLink();
pieces.push_back(ElfFilePiece(it->name_, it->section_.sh_offset,
it->GetBuffer()->data(), it->GetBuffer()->size()));
prev = it->section_;
if (debug_logging_) {
LOG(INFO) << it->name_ << " off=" << it->section_.sh_offset
<< " " << it->name_ << " size=" << it->section_.sh_size;
}
}
// Get the layout of the shstrtab section
shstrtab_builder_.section_.sh_offset = NextOffset(shstrtab_builder_.section_, prev);
shstrtab_builder_.section_.sh_addr = 0;
shstrtab_builder_.section_.sh_size = shstrtab.size();
shstrtab_builder_.section_.sh_link = shstrtab_builder_.GetLink();
if (debug_logging_) {
LOG(INFO) << "shstrtab off=" << shstrtab_builder_.section_.sh_offset
<< " shstrtab size=" << shstrtab_builder_.section_.sh_size;
}
// The section list comes after come after.
Elf32_Word sections_offset = RoundUp(
shstrtab_builder_.section_.sh_offset + shstrtab_builder_.section_.sh_size,
sizeof(Elf32_Word));
// Setup the actual symbol arrays.
std::vector<Elf32_Sym> dynsym = dynsym_builder_.GenerateSymtab();
CHECK_EQ(dynsym.size()*sizeof(Elf32_Sym), dynsym_builder_.section_.sh_size);
std::vector<Elf32_Sym> symtab;
if (IncludingDebugSymbols()) {
symtab = symtab_builder_.GenerateSymtab();
CHECK_EQ(symtab.size()*sizeof(Elf32_Sym), symtab_builder_.section_.sh_size);
}
// Setup the dynamic section.
// This will add the 2 values we cannot know until now time, namely the size
// and the soname_offset.
std::vector<Elf32_Dyn> dynamic = dynamic_builder_.GetDynamics(dynstr.size(),
dynstr_soname_offset);
CHECK_EQ(dynamic.size()*sizeof(Elf32_Dyn), dynamic_builder_.section_.sh_size);
// Finish setup of the program headers now that we know the layout of the
// whole file.
Elf32_Word load_r_size = rodata_builder_.section_.sh_offset + rodata_builder_.section_.sh_size;
program_headers[PH_LOAD_R__].p_filesz = load_r_size;
program_headers[PH_LOAD_R__].p_memsz = load_r_size;
program_headers[PH_LOAD_R__].p_align = rodata_builder_.section_.sh_addralign;
Elf32_Word load_rx_size = text_builder_.section_.sh_size;
program_headers[PH_LOAD_R_X].p_offset = text_builder_.section_.sh_offset;
program_headers[PH_LOAD_R_X].p_vaddr = text_builder_.section_.sh_offset;
program_headers[PH_LOAD_R_X].p_paddr = text_builder_.section_.sh_offset;
program_headers[PH_LOAD_R_X].p_filesz = load_rx_size;
program_headers[PH_LOAD_R_X].p_memsz = load_rx_size;
program_headers[PH_LOAD_R_X].p_align = text_builder_.section_.sh_addralign;
program_headers[PH_LOAD_RW_].p_offset = dynamic_builder_.section_.sh_offset;
program_headers[PH_LOAD_RW_].p_vaddr = dynamic_builder_.section_.sh_offset;
program_headers[PH_LOAD_RW_].p_paddr = dynamic_builder_.section_.sh_offset;
program_headers[PH_LOAD_RW_].p_filesz = dynamic_builder_.section_.sh_size;
program_headers[PH_LOAD_RW_].p_memsz = dynamic_builder_.section_.sh_size;
program_headers[PH_LOAD_RW_].p_align = dynamic_builder_.section_.sh_addralign;
program_headers[PH_DYNAMIC].p_offset = dynamic_builder_.section_.sh_offset;
program_headers[PH_DYNAMIC].p_vaddr = dynamic_builder_.section_.sh_offset;
program_headers[PH_DYNAMIC].p_paddr = dynamic_builder_.section_.sh_offset;
program_headers[PH_DYNAMIC].p_filesz = dynamic_builder_.section_.sh_size;
program_headers[PH_DYNAMIC].p_memsz = dynamic_builder_.section_.sh_size;
program_headers[PH_DYNAMIC].p_align = dynamic_builder_.section_.sh_addralign;
// Finish setup of the Ehdr values.
elf_header_.e_phoff = phdr_offset;
elf_header_.e_shoff = sections_offset;
elf_header_.e_phnum = PH_NUM;
elf_header_.e_shnum = section_ptrs.size();
elf_header_.e_shstrndx = shstrtab_builder_.section_index_;
// Add the rest of the pieces to the list.
pieces.push_back(ElfFilePiece("Elf Header", 0, &elf_header_, sizeof(elf_header_)));
pieces.push_back(ElfFilePiece("Program headers", phdr_offset,
&program_headers, sizeof(program_headers)));
pieces.push_back(ElfFilePiece(".dynamic", dynamic_builder_.section_.sh_offset,
dynamic.data(), dynamic_builder_.section_.sh_size));
pieces.push_back(ElfFilePiece(".dynsym", dynsym_builder_.section_.sh_offset,
dynsym.data(), dynsym.size()*sizeof(Elf32_Sym)));
pieces.push_back(ElfFilePiece(".dynstr", dynsym_builder_.strtab_.section_.sh_offset,
dynstr.c_str(), dynstr.size()));
pieces.push_back(ElfFilePiece(".hash", hash_builder_.section_.sh_offset,
hash.data(), hash.size() * sizeof(Elf32_Word)));
pieces.push_back(ElfFilePiece(".rodata", rodata_builder_.section_.sh_offset,
NULL, rodata_builder_.section_.sh_size));
pieces.push_back(ElfFilePiece(".text", text_builder_.section_.sh_offset,
NULL, text_builder_.section_.sh_size));
if (IncludingDebugSymbols()) {
pieces.push_back(ElfFilePiece(".symtab", symtab_builder_.section_.sh_offset,
symtab.data(), symtab.size() * sizeof(Elf32_Sym)));
pieces.push_back(ElfFilePiece(".strtab", symtab_builder_.strtab_.section_.sh_offset,
strtab.c_str(), strtab.size()));
}
pieces.push_back(ElfFilePiece(".shstrtab", shstrtab_builder_.section_.sh_offset,
&shstrtab[0], shstrtab.size()));
for (uint32_t i = 0; i < section_ptrs.size(); ++i) {
// Just add all the sections in induvidually since they are all over the
// place on the heap/stack.
Elf32_Word cur_off = sections_offset + i * sizeof(Elf32_Shdr);
pieces.push_back(ElfFilePiece("section table piece", cur_off,
section_ptrs[i], sizeof(Elf32_Shdr)));
}
if (!WriteOutFile(pieces)) {
LOG(ERROR) << "Unable to write to file " << elf_file_->GetPath();
return false;
}
// write out the actual oat file data.
Elf32_Word oat_data_offset = rodata_builder_.section_.sh_offset;
if (static_cast<off_t>(oat_data_offset) != lseek(elf_file_->Fd(), oat_data_offset, SEEK_SET)) {
PLOG(ERROR) << "Failed to seek to .rodata offset " << oat_data_offset
<< " for " << elf_file_->GetPath();
return false;
}
std::unique_ptr<BufferedOutputStream> output_stream(
new BufferedOutputStream(new FileOutputStream(elf_file_)));
if (!oat_writer_->Write(output_stream.get())) {
PLOG(ERROR) << "Failed to write .rodata and .text for " << elf_file_->GetPath();
return false;
}
return true;
}
bool ElfWriterQuick::ElfBuilder::WriteOutFile(const std::vector<ElfFilePiece>& pieces) {
// TODO It would be nice if this checked for overlap.
for (auto it = pieces.begin(); it != pieces.end(); ++it) {
if (it->data_) {
if (static_cast<off_t>(it->offset_) != lseek(elf_file_->Fd(), it->offset_, SEEK_SET)) {
PLOG(ERROR) << "Failed to seek to " << it->dbg_name_ << " offset location "
<< it->offset_ << " for " << elf_file_->GetPath();
return false;
}
if (!elf_file_->WriteFully(it->data_, it->size_)) {
PLOG(ERROR) << "Failed to write " << it->dbg_name_ << " for " << elf_file_->GetPath();
return false;
}
}
}
return true;
}
void ElfWriterQuick::ElfBuilder::SetupDynamic() {
dynamic_builder_.AddDynamicTag(DT_HASH, 0, &hash_builder_);
dynamic_builder_.AddDynamicTag(DT_STRTAB, 0, &dynsym_builder_.strtab_);
dynamic_builder_.AddDynamicTag(DT_SYMTAB, 0, &dynsym_builder_);
dynamic_builder_.AddDynamicTag(DT_SYMENT, sizeof(Elf32_Sym));
}
void ElfWriterQuick::ElfBuilder::SetupRequiredSymbols() {
dynsym_builder_.AddSymbol("oatdata", &rodata_builder_, 0, true,
rodata_builder_.size_, STB_GLOBAL, STT_OBJECT);
dynsym_builder_.AddSymbol("oatexec", &text_builder_, 0, true,
text_builder_.size_, STB_GLOBAL, STT_OBJECT);
dynsym_builder_.AddSymbol("oatlastword", &text_builder_, text_builder_.size_ - 4,
true, 4, STB_GLOBAL, STT_OBJECT);
}
void ElfWriterQuick::ElfDynamicBuilder::AddDynamicTag(Elf32_Sword tag, Elf32_Sword d_un) {
if (tag == DT_NULL) {
return;
}
dynamics_.push_back({NULL, tag, d_un});
}
void ElfWriterQuick::ElfDynamicBuilder::AddDynamicTag(Elf32_Sword tag, Elf32_Sword d_un,
ElfSectionBuilder* section) {
if (tag == DT_NULL) {
return;
}
dynamics_.push_back({section, tag, d_un});
}
std::vector<Elf32_Dyn> ElfWriterQuick::ElfDynamicBuilder::GetDynamics(Elf32_Sword strsz,
Elf32_Sword soname) {
std::vector<Elf32_Dyn> ret;
for (auto it = dynamics_.cbegin(); it != dynamics_.cend(); ++it) {
if (it->section_) {
// We are adding an address relative to a section.
ret.push_back(
{it->tag_, {it->off_ + static_cast<Elf32_Sword>(it->section_->section_.sh_addr)}});
} else {
ret.push_back({it->tag_, {it->off_}});
}
}
ret.push_back({DT_STRSZ, {strsz}});
ret.push_back({DT_SONAME, {soname}});
ret.push_back({DT_NULL, {0}});
return ret;
}
std::vector<Elf32_Sym> ElfWriterQuick::ElfSymtabBuilder::GenerateSymtab() {
std::vector<Elf32_Sym> ret;
Elf32_Sym undef_sym;
memset(&undef_sym, 0, sizeof(undef_sym));
undef_sym.st_shndx = SHN_UNDEF;
ret.push_back(undef_sym);
for (auto it = symbols_.cbegin(); it != symbols_.cend(); ++it) {
Elf32_Sym sym;
memset(&sym, 0, sizeof(sym));
sym.st_name = it->name_idx_;
if (it->is_relative_) {
sym.st_value = it->addr_ + it->section_->section_.sh_offset;
} else {
sym.st_value = it->addr_;
}
sym.st_size = it->size_;
sym.st_other = it->other_;
sym.st_shndx = it->section_->section_index_;
sym.st_info = it->info_;
ret.push_back(sym);
}
return ret;
}
std::string ElfWriterQuick::ElfSymtabBuilder::GenerateStrtab() {
std::string tab;
tab += '\0';
for (auto it = symbols_.begin(); it != symbols_.end(); ++it) {
it->name_idx_ = tab.size();
tab += it->name_;
tab += '\0';
}
strtab_.section_.sh_size = tab.size();
return tab;
}
void ElfWriterQuick::ElfBuilder::AssignSectionStr(
ElfSectionBuilder* builder, std::string* strtab) {
builder->section_.sh_name = strtab->size();
*strtab += builder->name_;
*strtab += '\0';
if (debug_logging_) {
LOG(INFO) << "adding section name \"" << builder->name_ << "\" "
<< "to shstrtab at offset " << builder->section_.sh_name;
}
}
// 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;
}
std::vector<Elf32_Word> ElfWriterQuick::ElfSymtabBuilder::GenerateHashContents() {
// Here is how The ELF hash table works.
// There are 3 arrays to worry about.
// * The symbol table where the symbol information is.
// * The bucket array which is an array of indexes into the symtab and chain.
// * The chain array which is also an array of indexes into the symtab and chain.
//
// Lets say the state is something like this.
// +--------+ +--------+ +-----------+
// | symtab | | bucket | | chain |
// | NULL | | 1 | | STN_UNDEF |
// | <sym1> | | 4 | | 2 |
// | <sym2> | | | | 5 |
// | <sym3> | | | | STN_UNDEF |
// | <sym4> | | | | 3 |
// | <sym5> | | | | STN_UNDEF |
// +--------+ +--------+ +-----------+
//
// The lookup process (in python psudocode) is
//
// def GetSym(name):
// # NB STN_UNDEF == 0
// indx = bucket[elfhash(name) % num_buckets]
// while indx != STN_UNDEF:
// if GetSymbolName(symtab[indx]) == name:
// return symtab[indx]
// indx = chain[indx]
// return SYMBOL_NOT_FOUND
//
// Between bucket and chain arrays every symtab index must be present exactly
// once (except for STN_UNDEF, which must be present 1 + num_bucket times).
// Select number of buckets.
// This is essentially arbitrary.
Elf32_Word nbuckets;
Elf32_Word chain_size = size();
if (symbols_.size() < 8) {
nbuckets = 2;
} else if (symbols_.size() < 32) {
nbuckets = 4;
} else if (symbols_.size() < 256) {
nbuckets = 16;
} else {
// Have about 32 ids per bucket.
nbuckets = RoundUp(symbols_.size()/32, 2);
}
std::vector<Elf32_Word> hash;
hash.push_back(nbuckets);
hash.push_back(chain_size);
uint32_t bucket_offset = hash.size();
uint32_t chain_offset = bucket_offset + nbuckets;
hash.resize(hash.size() + nbuckets + chain_size, 0);
Elf32_Word* buckets = hash.data() + bucket_offset;
Elf32_Word* chain = hash.data() + chain_offset;
// Set up the actual hash table.
for (Elf32_Word i = 0; i < symbols_.size(); i++) {
// Add 1 since we need to have the null symbol that is not in the symbols
// list.
Elf32_Word index = i + 1;
Elf32_Word hash_val = static_cast<Elf32_Word>(elfhash(symbols_[i].name_.c_str())) % nbuckets;
if (buckets[hash_val] == 0) {
buckets[hash_val] = index;
} else {
hash_val = buckets[hash_val];
CHECK_LT(hash_val, chain_size);
while (chain[hash_val] != 0) {
hash_val = chain[hash_val];
CHECK_LT(hash_val, chain_size);
}
chain[hash_val] = index;
// Check for loops. Works because if this is non-empty then there must be
// another cell which already contains the same symbol index as this one,
// which means some symbol has more then one name, which isn't allowed.
CHECK_EQ(chain[index], static_cast<Elf32_Word>(0));
}
}
return hash;
}
void ElfWriterQuick::ElfBuilder::SetupEhdr() {
memset(&elf_header_, 0, sizeof(elf_header_));
elf_header_.e_ident[EI_MAG0] = ELFMAG0;
elf_header_.e_ident[EI_MAG1] = ELFMAG1;
elf_header_.e_ident[EI_MAG2] = ELFMAG2;
elf_header_.e_ident[EI_MAG3] = ELFMAG3;
elf_header_.e_ident[EI_CLASS] = ELFCLASS32;
elf_header_.e_ident[EI_DATA] = ELFDATA2LSB;
elf_header_.e_ident[EI_VERSION] = EV_CURRENT;
elf_header_.e_ident[EI_OSABI] = ELFOSABI_LINUX;
elf_header_.e_ident[EI_ABIVERSION] = 0;
elf_header_.e_type = ET_DYN;
elf_header_.e_version = 1;
elf_header_.e_entry = 0;
elf_header_.e_ehsize = sizeof(Elf32_Ehdr);
elf_header_.e_phentsize = sizeof(Elf32_Phdr);
elf_header_.e_shentsize = sizeof(Elf32_Shdr);
elf_header_.e_phoff = sizeof(Elf32_Ehdr);
}
void ElfWriterQuick::ElfBuilder::SetISA(InstructionSet isa) {
switch (isa) {
case kArm:
// Fall through.
case kThumb2: {
elf_header_.e_machine = EM_ARM;
elf_header_.e_flags = EF_ARM_EABI_VER5;
break;
}
case kArm64: {
elf_header_.e_machine = EM_AARCH64;
elf_header_.e_flags = 0;
break;
}
case kX86: {
elf_header_.e_machine = EM_386;
elf_header_.e_flags = 0;
break;
}
case kX86_64: {
elf_header_.e_machine = EM_X86_64;
elf_header_.e_flags = 0;
break;
}
case kMips: {
elf_header_.e_machine = EM_MIPS;
elf_header_.e_flags = (EF_MIPS_NOREORDER |
EF_MIPS_PIC |
EF_MIPS_CPIC |
EF_MIPS_ABI_O32 |
EF_MIPS_ARCH_32R2);
break;
}
default: {
fatal_error_ = true;
LOG(FATAL) << "Unknown instruction set: " << isa;
break;
}
}
}
void ElfWriterQuick::ElfSymtabBuilder::AddSymbol(
const std::string& name, const ElfSectionBuilder* section, Elf32_Addr addr,
bool is_relative, Elf32_Word size, uint8_t binding, uint8_t type, uint8_t other) {
CHECK(section);
ElfSymtabBuilder::ElfSymbolState state {name, section, addr, size, is_relative,
MakeStInfo(binding, type), other, 0};
symbols_.push_back(state);
}
bool ElfWriterQuick::Create(File* elf_file,
OatWriter* oat_writer,
const std::vector<const DexFile*>& dex_files,
const std::string& android_root,
bool is_host,
const CompilerDriver& driver) {
ElfWriterQuick elf_writer(driver, elf_file);
return elf_writer.Write(oat_writer, dex_files, android_root, is_host);
}
bool ElfWriterQuick::Write(OatWriter* oat_writer,
const std::vector<const DexFile*>& dex_files_unused,
const std::string& android_root_unused,
bool is_host_unused) {
const bool debug = false;
const OatHeader& oat_header = oat_writer->GetOatHeader();
Elf32_Word oat_data_size = oat_header.GetExecutableOffset();
uint32_t oat_exec_size = oat_writer->GetSize() - oat_data_size;
ElfBuilder builder(oat_writer, elf_file_, compiler_driver_->GetInstructionSet(), 0,
oat_data_size, oat_data_size, oat_exec_size, false, debug);
bool generateDebugInformation = compiler_driver_->GetCallFrameInformation() != nullptr;
if (generateDebugInformation) {
ElfRawSectionBuilder debug_info(".debug_info", SHT_PROGBITS, 0, NULL, 0, 1, 0);
ElfRawSectionBuilder debug_abbrev(".debug_abbrev", SHT_PROGBITS, 0, NULL, 0, 1, 0);
ElfRawSectionBuilder debug_str(".debug_str", SHT_PROGBITS, 0, NULL, 0, 1, 0);
ElfRawSectionBuilder debug_frame(".debug_frame", SHT_PROGBITS, 0, NULL, 0, 4, 0);
debug_frame.SetBuffer(*compiler_driver_->GetCallFrameInformation());
FillInCFIInformation(oat_writer, debug_info.GetBuffer(),
debug_abbrev.GetBuffer(), debug_str.GetBuffer());
builder.RegisterRawSection(debug_info);
builder.RegisterRawSection(debug_abbrev);
builder.RegisterRawSection(debug_frame);
builder.RegisterRawSection(debug_str);
}
return builder.Write();
}
static void UpdateWord(std::vector<uint8_t>*buf, int offset, int data) {
(*buf)[offset+0] = data;
(*buf)[offset+1] = data >> 8;
(*buf)[offset+2] = data >> 16;
(*buf)[offset+3] = data >> 24;
}
static void PushWord(std::vector<uint8_t>*buf, int data) {
buf->push_back(data & 0xff);
buf->push_back((data >> 8) & 0xff);
buf->push_back((data >> 16) & 0xff);
buf->push_back((data >> 24) & 0xff);
}
static void PushHalf(std::vector<uint8_t>*buf, int data) {
buf->push_back(data & 0xff);
buf->push_back((data >> 8) & 0xff);
}
// DWARF constants needed to generate CFI information.
enum {
// Tag encodings.
DW_TAG_compile_unit = 0x11,
DW_TAG_subprogram = 0X2e,
// Attribute encodings.
DW_AT_name = 0x03,
DW_AT_low_pc = 0x11,
DW_AT_high_pc = 0x12,
DW_AT_language = 0x13,
// Constant encoding.
DW_CHILDREN_no = 0x00,
DW_CHILDREN_yes = 0x01,
// Attribute form encodings.
DW_FORM_addr = 0x01,
DW_FORM_data1 = 0x0b,
DW_FORM_strp = 0x0e,
// Language encoding.
DW_LANG_Java = 0x000b
};
void ElfWriterQuick::FillInCFIInformation(OatWriter* oat_writer,
std::vector<uint8_t>* dbg_info,
std::vector<uint8_t>* dbg_abbrev,
std::vector<uint8_t>* dbg_str) {
// Create the debug_abbrev section with boilerplate information.
// We only care about low_pc and high_pc right now for the compilation
// unit and methods.
// Tag 1: Compilation unit: DW_TAG_compile_unit.
dbg_abbrev->push_back(1);
dbg_abbrev->push_back(DW_TAG_compile_unit);
// There are children (the methods).
dbg_abbrev->push_back(DW_CHILDREN_yes);
// DW_LANG_Java DW_FORM_data1.
dbg_abbrev->push_back(DW_AT_language);
dbg_abbrev->push_back(DW_FORM_data1);
// DW_AT_low_pc DW_FORM_addr.
dbg_abbrev->push_back(DW_AT_low_pc);
dbg_abbrev->push_back(DW_FORM_addr);
// DW_AT_high_pc DW_FORM_addr.
dbg_abbrev->push_back(DW_AT_high_pc);
dbg_abbrev->push_back(DW_FORM_addr);
// End of DW_TAG_compile_unit.
PushHalf(dbg_abbrev, 0);
// Tag 2: Compilation unit: DW_TAG_subprogram.
dbg_abbrev->push_back(2);
dbg_abbrev->push_back(DW_TAG_subprogram);
// There are no children.
dbg_abbrev->push_back(DW_CHILDREN_no);
// Name of the method.
dbg_abbrev->push_back(DW_AT_name);
dbg_abbrev->push_back(DW_FORM_strp);
// DW_AT_low_pc DW_FORM_addr.
dbg_abbrev->push_back(DW_AT_low_pc);
dbg_abbrev->push_back(DW_FORM_addr);
// DW_AT_high_pc DW_FORM_addr.
dbg_abbrev->push_back(DW_AT_high_pc);
dbg_abbrev->push_back(DW_FORM_addr);
// End of DW_TAG_subprogram.
PushHalf(dbg_abbrev, 0);
// Start the debug_info section with the header information
// 'unit_length' will be filled in later.
PushWord(dbg_info, 0);
// 'version' - 3.
PushHalf(dbg_info, 3);
// Offset into .debug_abbrev section (always 0).
PushWord(dbg_info, 0);
// Address size: 4.
dbg_info->push_back(4);
// Start the description for the compilation unit.
// This uses tag 1.
dbg_info->push_back(1);
// The language is Java.
dbg_info->push_back(DW_LANG_Java);
// Leave space for low_pc and high_pc.
int low_pc_offset = dbg_info->size();
PushWord(dbg_info, 0);
PushWord(dbg_info, 0);
// Walk through the information in the method table, and enter into dbg_info.
const std::vector<OatWriter::DebugInfo>& dbg = oat_writer->GetCFIMethodInfo();
uint32_t low_pc = 0xFFFFFFFFU;
uint32_t high_pc = 0;
for (uint32_t i = 0; i < dbg.size(); i++) {
const OatWriter::DebugInfo& info = dbg[i];
if (info.low_pc_ < low_pc) {
low_pc = info.low_pc_;
}
if (info.high_pc_ > high_pc) {
high_pc = info.high_pc_;
}
// Start a new TAG: subroutine (2).
dbg_info->push_back(2);
// Enter the name into the string table (and NUL terminate).
uint32_t str_offset = dbg_str->size();
dbg_str->insert(dbg_str->end(), info.method_name_.begin(), info.method_name_.end());
dbg_str->push_back('\0');
// Enter name, low_pc, high_pc.
PushWord(dbg_info, str_offset);
PushWord(dbg_info, info.low_pc_);
PushWord(dbg_info, info.high_pc_);
}
// One byte terminator
dbg_info->push_back(0);
// We have now walked all the methods. Fill in lengths and low/high PCs.
UpdateWord(dbg_info, 0, dbg_info->size() - 4);
UpdateWord(dbg_info, low_pc_offset, low_pc);
UpdateWord(dbg_info, low_pc_offset + 4, high_pc);
}
} // namespace art