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// layout.h -- lay out output file sections for gold -*- C++ -*-
// Copyright 2006, 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#ifndef GOLD_LAYOUT_H
#define GOLD_LAYOUT_H
#include <list>
#include <string>
#include <utility>
#include <vector>
#include "workqueue.h"
#include "object.h"
#include "dynobj.h"
#include "stringpool.h"
namespace gold
{
class General_options;
class Input_objects;
class Symbol_table;
class Output_section_data;
class Output_section;
class Output_section_headers;
class Output_segment;
class Output_data;
class Output_data_dynamic;
class Target;
// This task function handles mapping the input sections to output
// sections and laying them out in memory.
class Layout_task_runner : public Task_function_runner
{
public:
// OPTIONS is the command line options, INPUT_OBJECTS is the list of
// input objects, SYMTAB is the symbol table, LAYOUT is the layout
// object.
Layout_task_runner(const General_options& options,
const Input_objects* input_objects,
Symbol_table* symtab,
Layout* layout)
: options_(options), input_objects_(input_objects), symtab_(symtab),
layout_(layout)
{ }
// Run the operation.
void
run(Workqueue*);
private:
Layout_task_runner(const Layout_task_runner&);
Layout_task_runner& operator=(const Layout_task_runner&);
const General_options& options_;
const Input_objects* input_objects_;
Symbol_table* symtab_;
Layout* layout_;
};
// This class handles the details of laying out input sections.
class Layout
{
public:
Layout(const General_options& options);
// Given an input section SHNDX, named NAME, with data in SHDR, from
// the object file OBJECT, return the output section where this
// input section should go. Set *OFFSET to the offset within the
// output section.
template<int size, bool big_endian>
Output_section*
layout(Relobj *object, unsigned int shndx, const char* name,
const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
// Add an Output_section_data to the layout. This is used for
// special sections like the GOT section.
void
add_output_section_data(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags,
Output_section_data*);
// Create dynamic sections if necessary.
void
create_initial_dynamic_sections(const Input_objects*, Symbol_table*);
// Define __start and __stop symbols for output sections.
void
define_section_symbols(Symbol_table*, const Target*);
// Return the Stringpool used for symbol names.
const Stringpool*
sympool() const
{ return &this->sympool_; }
// Return the Stringpool used for dynamic symbol names and dynamic
// tags.
const Stringpool*
dynpool() const
{ return &this->dynpool_; }
// Return whether a section is a .gnu.linkonce section, given the
// section name.
static inline bool
is_linkonce(const char* name)
{ return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
// Record the signature of a comdat section, and return whether to
// include it in the link. The GROUP parameter is true for a
// section group signature, false for a signature derived from a
// .gnu.linkonce section.
bool
add_comdat(const char*, bool group);
// Finalize the layout after all the input sections have been added.
off_t
finalize(const Input_objects*, Symbol_table*);
// Return the TLS segment. This will return NULL if there isn't
// one.
Output_segment*
tls_segment() const
{ return this->tls_segment_; }
// Return the normal symbol table.
Output_section*
symtab_section() const
{
gold_assert(this->symtab_section_ != NULL);
return this->symtab_section_;
}
// Return the dynamic symbol table.
Output_section*
dynsym_section() const
{
gold_assert(this->dynsym_section_ != NULL);
return this->dynsym_section_;
}
// Return the dynamic tags.
Output_data_dynamic*
dynamic_data() const
{ return this->dynamic_data_; }
// Write out data not associated with an input file or the symbol
// table.
void
write_data(const Symbol_table*, Output_file*) const;
// Return an output section named NAME, or NULL if there is none.
Output_section*
find_output_section(const char* name) const;
// Return an output segment of type TYPE, with segment flags SET set
// and segment flags CLEAR clear. Return NULL if there is none.
Output_segment*
find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
elfcpp::Elf_Word clear) const;
// The list of segments.
typedef std::vector<Output_segment*> Segment_list;
// The list of sections not attached to a segment.
typedef std::vector<Output_section*> Section_list;
// The list of information to write out which is not attached to
// either a section or a segment.
typedef std::vector<Output_data*> Data_list;
private:
Layout(const Layout&);
Layout& operator=(const Layout&);
// Mapping from .gnu.linkonce section names to output section names.
struct Linkonce_mapping
{
const char* from;
int fromlen;
const char* to;
int tolen;
};
static const Linkonce_mapping linkonce_mapping[];
static const int linkonce_mapping_count;
// Handle an exception frame section.
template<int size, bool big_endian>
void
layout_eh_frame(Relobj*, unsigned int, const char*,
const elfcpp::Shdr<size, big_endian>&,
Output_section*, off_t*);
// Create a .note section for gold.
void
create_note_section();
// Find the first read-only PT_LOAD segment, creating one if
// necessary.
Output_segment*
find_first_load_seg();
// Create the output sections for the symbol table.
void
create_symtab_sections(const Input_objects*, Symbol_table*, off_t*);
// Create the .shstrtab section.
Output_section*
create_shstrtab();
// Create the section header table.
Output_section_headers*
create_shdrs(off_t*);
// Create the dynamic symbol table.
void
create_dynamic_symtab(const Target*, Symbol_table*, Output_section** pdynstr,
unsigned int* plocal_dynamic_count,
std::vector<Symbol*>* pdynamic_symbols,
Versions* versions);
// Finish the .dynamic section and PT_DYNAMIC segment.
void
finish_dynamic_section(const Input_objects*, const Symbol_table*);
// Create the .interp section and PT_INTERP segment.
void
create_interp(const Target* target);
// Create the version sections.
void
create_version_sections(const Versions*,
unsigned int local_symcount,
const std::vector<Symbol*>& dynamic_symbols,
const Output_section* dynstr);
template<int size, bool big_endian>
void
sized_create_version_sections(const Versions* versions,
unsigned int local_symcount,
const std::vector<Symbol*>& dynamic_symbols,
const Output_section* dynstr
ACCEPT_SIZE_ENDIAN);
// Return whether to include this section in the link.
template<int size, bool big_endian>
bool
include_section(Object* object, const char* name,
const elfcpp::Shdr<size, big_endian>&);
// Return the output section name to use given an input section
// name. Set *PLEN to the length of the name. *PLEN must be
// initialized to the length of NAME.
static const char*
output_section_name(const char* name, size_t* plen);
// Return the output section name to use for a linkonce section
// name. PLEN is as for output_section_name.
static const char*
linkonce_output_name(const char* name, size_t* plen);
// Return the output section for NAME, TYPE and FLAGS.
Output_section*
get_output_section(const char* name, Stringpool::Key name_key,
elfcpp::Elf_Word type, elfcpp::Elf_Xword flags);
// Create a new Output_section.
Output_section*
make_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags);
// Set the final file offsets of all the segments.
off_t
set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx);
// Set the final file offsets and section indexes of all the
// sections not associated with a segment.
off_t
set_section_offsets(off_t, unsigned int *pshndx);
// Return whether SEG1 comes before SEG2 in the output file.
static bool
segment_precedes(const Output_segment* seg1, const Output_segment* seg2);
// Map from section flags to segment flags.
static elfcpp::Elf_Word
section_flags_to_segment(elfcpp::Elf_Xword flags);
// A mapping used for group signatures.
typedef Unordered_map<std::string, bool> Signatures;
// Mapping from input section name/type/flags to output section. We
// use canonicalized strings here.
typedef std::pair<Stringpool::Key,
std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
struct Hash_key
{
size_t
operator()(const Key& k) const;
};
typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
// A comparison class for segments.
struct Compare_segments
{
bool
operator()(const Output_segment* seg1, const Output_segment* seg2)
{ return Layout::segment_precedes(seg1, seg2); }
};
// A reference to the options on the command line.
const General_options& options_;
// The output section names.
Stringpool namepool_;
// The output symbol names.
Stringpool sympool_;
// The dynamic strings, if needed.
Stringpool dynpool_;
// The list of group sections and linkonce sections which we have seen.
Signatures signatures_;
// The mapping from input section name/type/flags to output sections.
Section_name_map section_name_map_;
// The list of output segments.
Segment_list segment_list_;
// The list of output sections.
Section_list section_list_;
// The list of output sections which are not attached to any output
// segment.
Section_list unattached_section_list_;
// The list of unattached Output_data objects which require special
// handling because they are not Output_sections.
Data_list special_output_list_;
// A pointer to the PT_TLS segment if there is one.
Output_segment* tls_segment_;
// The SHT_SYMTAB output section.
Output_section* symtab_section_;
// The SHT_DYNSYM output section if there is one.
Output_section* dynsym_section_;
// The SHT_DYNAMIC output section if there is one.
Output_section* dynamic_section_;
// The dynamic data which goes into dynamic_section_.
Output_data_dynamic* dynamic_data_;
// The exception frame section.
Output_section* eh_frame_section_;
};
// This task handles writing out data which is not part of a section
// or segment.
class Write_data_task : public Task
{
public:
Write_data_task(const Layout* layout, const Symbol_table* symtab,
Output_file* of, Task_token* final_blocker)
: layout_(layout), symtab_(symtab), of_(of), final_blocker_(final_blocker)
{ }
// The standard Task methods.
Is_runnable_type
is_runnable(Workqueue*);
Task_locker*
locks(Workqueue*);
void
run(Workqueue*);
private:
const Layout* layout_;
const Symbol_table* symtab_;
Output_file* of_;
Task_token* final_blocker_;
};
// This task handles writing out the global symbols.
class Write_symbols_task : public Task
{
public:
Write_symbols_task(const Symbol_table* symtab, const Target* target,
const Stringpool* sympool, const Stringpool* dynpool,
Output_file* of, Task_token* final_blocker)
: symtab_(symtab), target_(target), sympool_(sympool), dynpool_(dynpool),
of_(of), final_blocker_(final_blocker)
{ }
// The standard Task methods.
Is_runnable_type
is_runnable(Workqueue*);
Task_locker*
locks(Workqueue*);
void
run(Workqueue*);
private:
const Symbol_table* symtab_;
const Target* target_;
const Stringpool* sympool_;
const Stringpool* dynpool_;
Output_file* of_;
Task_token* final_blocker_;
};
// This task function handles closing the file.
class Close_task_runner : public Task_function_runner
{
public:
Close_task_runner(Output_file* of)
: of_(of)
{ }
// Run the operation.
void
run(Workqueue*);
private:
Output_file* of_;
};
// A small helper function to align an address.
inline uint64_t
align_address(uint64_t address, uint64_t addralign)
{
if (addralign != 0)
address = (address + addralign - 1) &~ (addralign - 1);
return address;
}
} // End namespace gold.
#endif // !defined(GOLD_LAYOUT_H)
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