binutils-gdb/gold/object.h

1500 lines
46 KiB
C++

// object.h -- support for an object file for linking in 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_OBJECT_H
#define GOLD_OBJECT_H
#include <string>
#include <vector>
#include "elfcpp.h"
#include "elfcpp_file.h"
#include "fileread.h"
#include "target.h"
namespace gold
{
class General_options;
class Task;
class Layout;
class Output_section;
class Output_file;
class Dynobj;
class Object_merge_map;
class Relocatable_relocs;
template<typename Stringpool_char>
class Stringpool_template;
// Data to pass from read_symbols() to add_symbols().
struct Read_symbols_data
{
// Section headers.
File_view* section_headers;
// Section names.
File_view* section_names;
// Size of section name data in bytes.
section_size_type section_names_size;
// Symbol data.
File_view* symbols;
// Size of symbol data in bytes.
section_size_type symbols_size;
// Offset of external symbols within symbol data. This structure
// sometimes contains only external symbols, in which case this will
// be zero. Sometimes it contains all symbols.
section_offset_type external_symbols_offset;
// Symbol names.
File_view* symbol_names;
// Size of symbol name data in bytes.
section_size_type symbol_names_size;
// Version information. This is only used on dynamic objects.
// Version symbol data (from SHT_GNU_versym section).
File_view* versym;
section_size_type versym_size;
// Version definition data (from SHT_GNU_verdef section).
File_view* verdef;
section_size_type verdef_size;
unsigned int verdef_info;
// Needed version data (from SHT_GNU_verneed section).
File_view* verneed;
section_size_type verneed_size;
unsigned int verneed_info;
};
// Information used to print error messages.
struct Symbol_location_info
{
std::string source_file;
std::string enclosing_symbol_name;
int line_number;
};
// Data about a single relocation section. This is read in
// read_relocs and processed in scan_relocs.
struct Section_relocs
{
// Index of reloc section.
unsigned int reloc_shndx;
// Index of section that relocs apply to.
unsigned int data_shndx;
// Contents of reloc section.
File_view* contents;
// Reloc section type.
unsigned int sh_type;
// Number of reloc entries.
size_t reloc_count;
// Output section.
Output_section* output_section;
// Whether this section has special handling for offsets.
bool needs_special_offset_handling;
};
// Relocations in an object file. This is read in read_relocs and
// processed in scan_relocs.
struct Read_relocs_data
{
typedef std::vector<Section_relocs> Relocs_list;
// The relocations.
Relocs_list relocs;
// The local symbols.
File_view* local_symbols;
};
// Object is an abstract base class which represents either a 32-bit
// or a 64-bit input object. This can be a regular object file
// (ET_REL) or a shared object (ET_DYN).
class Object
{
public:
// NAME is the name of the object as we would report it to the user
// (e.g., libfoo.a(bar.o) if this is in an archive. INPUT_FILE is
// used to read the file. OFFSET is the offset within the input
// file--0 for a .o or .so file, something else for a .a file.
Object(const std::string& name, Input_file* input_file, bool is_dynamic,
off_t offset = 0)
: name_(name), input_file_(input_file), offset_(offset), shnum_(-1U),
is_dynamic_(is_dynamic), target_(NULL)
{ input_file->file().add_object(); }
virtual ~Object()
{ this->input_file_->file().remove_object(); }
// Return the name of the object as we would report it to the tuser.
const std::string&
name() const
{ return this->name_; }
// Get the offset into the file.
off_t
offset() const
{ return this->offset_; }
// Return whether this is a dynamic object.
bool
is_dynamic() const
{ return this->is_dynamic_; }
// Return the target structure associated with this object.
Target*
target() const
{ return this->target_; }
// Lock the underlying file.
void
lock(const Task* t)
{ this->input_file()->file().lock(t); }
// Unlock the underlying file.
void
unlock(const Task* t)
{ this->input_file()->file().unlock(t); }
// Return whether the underlying file is locked.
bool
is_locked() const
{ return this->input_file()->file().is_locked(); }
// Return the token, so that the task can be queued.
Task_token*
token()
{ return this->input_file()->file().token(); }
// Release the underlying file.
void
release()
{ this->input_file_->file().release(); }
// Return whether we should just read symbols from this file.
bool
just_symbols() const
{ return this->input_file()->just_symbols(); }
// Return the sized target structure associated with this object.
// This is like the target method but it returns a pointer of
// appropriate checked type.
template<int size, bool big_endian>
Sized_target<size, big_endian>*
sized_target(ACCEPT_SIZE_ENDIAN_ONLY) const;
// Get the number of sections.
unsigned int
shnum() const
{ return this->shnum_; }
// Return a view of the contents of a section. Set *PLEN to the
// size. CACHE is a hint as in File_read::get_view.
const unsigned char*
section_contents(unsigned int shndx, section_size_type* plen, bool cache);
// Return the size of a section given a section index.
uint64_t
section_size(unsigned int shndx)
{ return this->do_section_size(shndx); }
// Return the name of a section given a section index.
std::string
section_name(unsigned int shndx)
{ return this->do_section_name(shndx); }
// Return the section flags given a section index.
uint64_t
section_flags(unsigned int shndx)
{ return this->do_section_flags(shndx); }
// Return the section address given a section index.
uint64_t
section_address(unsigned int shndx)
{ return this->do_section_address(shndx); }
// Return the section type given a section index.
unsigned int
section_type(unsigned int shndx)
{ return this->do_section_type(shndx); }
// Return the section link field given a section index.
unsigned int
section_link(unsigned int shndx)
{ return this->do_section_link(shndx); }
// Return the section info field given a section index.
unsigned int
section_info(unsigned int shndx)
{ return this->do_section_info(shndx); }
// Return the required section alignment given a section index.
uint64_t
section_addralign(unsigned int shndx)
{ return this->do_section_addralign(shndx); }
// Read the symbol information.
void
read_symbols(Read_symbols_data* sd)
{ return this->do_read_symbols(sd); }
// Pass sections which should be included in the link to the Layout
// object, and record where the sections go in the output file.
void
layout(Symbol_table* symtab, Layout* layout, Read_symbols_data* sd)
{ this->do_layout(symtab, layout, sd); }
// Add symbol information to the global symbol table.
void
add_symbols(Symbol_table* symtab, Read_symbols_data* sd)
{ this->do_add_symbols(symtab, sd); }
// Functions and types for the elfcpp::Elf_file interface. This
// permit us to use Object as the File template parameter for
// elfcpp::Elf_file.
// The View class is returned by view. It must support a single
// method, data(). This is trivial, because get_view does what we
// need.
class View
{
public:
View(const unsigned char* p)
: p_(p)
{ }
const unsigned char*
data() const
{ return this->p_; }
private:
const unsigned char* p_;
};
// Return a View.
View
view(off_t file_offset, section_size_type data_size)
{ return View(this->get_view(file_offset, data_size, true)); }
// Report an error.
void
error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
// A location in the file.
struct Location
{
off_t file_offset;
off_t data_size;
Location(off_t fo, section_size_type ds)
: file_offset(fo), data_size(ds)
{ }
};
// Get a View given a Location.
View view(Location loc)
{ return View(this->get_view(loc.file_offset, loc.data_size, true)); }
// Get a view into the underlying file.
const unsigned char*
get_view(off_t start, section_size_type size, bool cache)
{
return this->input_file()->file().get_view(start + this->offset_, size,
cache);
}
// Get a lasting view into the underlying file.
File_view*
get_lasting_view(off_t start, section_size_type size, bool cache)
{
return this->input_file()->file().get_lasting_view(start + this->offset_,
size, cache);
}
// Read data from the underlying file.
void
read(off_t start, section_size_type size, void* p) const
{ this->input_file()->file().read(start + this->offset_, size, p); }
// Read multiple data from the underlying file.
void
read_multiple(const File_read::Read_multiple& rm)
{ this->input_file()->file().read_multiple(this->offset_, rm); }
// Stop caching views in the underlying file.
void
clear_view_cache_marks()
{ this->input_file()->file().clear_view_cache_marks(); }
protected:
// Read the symbols--implemented by child class.
virtual void
do_read_symbols(Read_symbols_data*) = 0;
// Lay out sections--implemented by child class.
virtual void
do_layout(Symbol_table*, Layout*, Read_symbols_data*) = 0;
// Add symbol information to the global symbol table--implemented by
// child class.
virtual void
do_add_symbols(Symbol_table*, Read_symbols_data*) = 0;
// Return the location of the contents of a section. Implemented by
// child class.
virtual Location
do_section_contents(unsigned int shndx) = 0;
// Get the size of a section--implemented by child class.
virtual uint64_t
do_section_size(unsigned int shndx) = 0;
// Get the name of a section--implemented by child class.
virtual std::string
do_section_name(unsigned int shndx) = 0;
// Get section flags--implemented by child class.
virtual uint64_t
do_section_flags(unsigned int shndx) = 0;
// Get section address--implemented by child class.
virtual uint64_t
do_section_address(unsigned int shndx) = 0;
// Get section type--implemented by child class.
virtual unsigned int
do_section_type(unsigned int shndx) = 0;
// Get section link field--implemented by child class.
virtual unsigned int
do_section_link(unsigned int shndx) = 0;
// Get section info field--implemented by child class.
virtual unsigned int
do_section_info(unsigned int shndx) = 0;
// Get section alignment--implemented by child class.
virtual uint64_t
do_section_addralign(unsigned int shndx) = 0;
// Get the file. We pass on const-ness.
Input_file*
input_file()
{ return this->input_file_; }
const Input_file*
input_file() const
{ return this->input_file_; }
// Set the target.
void
set_target(int machine, int size, bool big_endian, int osabi,
int abiversion);
// Set the number of sections.
void
set_shnum(int shnum)
{ this->shnum_ = shnum; }
// Functions used by both Sized_relobj and Sized_dynobj.
// Read the section data into a Read_symbols_data object.
template<int size, bool big_endian>
void
read_section_data(elfcpp::Elf_file<size, big_endian, Object>*,
Read_symbols_data*);
// If NAME is the name of a special .gnu.warning section, arrange
// for the warning to be issued. SHNDX is the section index.
// Return whether it is a warning section.
bool
handle_gnu_warning_section(const char* name, unsigned int shndx,
Symbol_table*);
private:
// This class may not be copied.
Object(const Object&);
Object& operator=(const Object&);
// Name of object as printed to user.
std::string name_;
// For reading the file.
Input_file* input_file_;
// Offset within the file--0 for an object file, non-0 for an
// archive.
off_t offset_;
// Number of input sections.
unsigned int shnum_;
// Whether this is a dynamic object.
bool is_dynamic_;
// Target functions--may be NULL if the target is not known.
Target* target_;
};
// Implement sized_target inline for efficiency. This approach breaks
// static type checking, but is made safe using asserts.
template<int size, bool big_endian>
inline Sized_target<size, big_endian>*
Object::sized_target(ACCEPT_SIZE_ENDIAN_ONLY) const
{
gold_assert(this->target_->get_size() == size);
gold_assert(this->target_->is_big_endian() ? big_endian : !big_endian);
return static_cast<Sized_target<size, big_endian>*>(this->target_);
}
// A regular object (ET_REL). This is an abstract base class itself.
// The implementation is the template class Sized_relobj.
class Relobj : public Object
{
public:
Relobj(const std::string& name, Input_file* input_file, off_t offset = 0)
: Object(name, input_file, false, offset),
map_to_output_(),
map_to_relocatable_relocs_(NULL),
object_merge_map_(NULL),
relocs_must_follow_section_writes_(false)
{ }
// Read the relocs.
void
read_relocs(Read_relocs_data* rd)
{ return this->do_read_relocs(rd); }
// Scan the relocs and adjust the symbol table.
void
scan_relocs(const General_options& options, Symbol_table* symtab,
Layout* layout, Read_relocs_data* rd)
{ return this->do_scan_relocs(options, symtab, layout, rd); }
// The number of local symbols in the input symbol table.
virtual unsigned int
local_symbol_count() const
{ return this->do_local_symbol_count(); }
// Initial local symbol processing: count the number of local symbols
// in the output symbol table and dynamic symbol table; add local symbol
// names to *POOL and *DYNPOOL.
void
count_local_symbols(Stringpool_template<char>* pool,
Stringpool_template<char>* dynpool)
{ return this->do_count_local_symbols(pool, dynpool); }
// Set the values of the local symbols, set the output symbol table
// indexes for the local variables, and set the offset where local
// symbol information will be stored. Returns the new local symbol index.
unsigned int
finalize_local_symbols(unsigned int index, off_t off)
{ return this->do_finalize_local_symbols(index, off); }
// Set the output dynamic symbol table indexes for the local variables.
unsigned int
set_local_dynsym_indexes(unsigned int index)
{ return this->do_set_local_dynsym_indexes(index); }
// Set the offset where local dynamic symbol information will be stored.
unsigned int
set_local_dynsym_offset(off_t off)
{ return this->do_set_local_dynsym_offset(off); }
// Relocate the input sections and write out the local symbols.
void
relocate(const General_options& options, const Symbol_table* symtab,
const Layout* layout, Output_file* of)
{ return this->do_relocate(options, symtab, layout, of); }
// Return whether an input section is being included in the link.
bool
is_section_included(unsigned int shndx) const
{
gold_assert(shndx < this->map_to_output_.size());
return this->map_to_output_[shndx].output_section != NULL;
}
// Return whether an input section requires special
// handling--whether it is not simply mapped from the input file to
// the output file.
bool
is_section_specially_mapped(unsigned int shndx) const
{
gold_assert(shndx < this->map_to_output_.size());
return (this->map_to_output_[shndx].output_section != NULL
&& this->map_to_output_[shndx].offset == -1);
}
// Given a section index, return the corresponding Output_section
// (which will be NULL if the section is not included in the link)
// and set *POFF to the offset within that section. *POFF will be
// set to -1 if the section requires special handling.
inline Output_section*
output_section(unsigned int shndx, section_offset_type* poff) const;
// Set the offset of an input section within its output section.
void
set_section_offset(unsigned int shndx, section_offset_type off)
{
gold_assert(shndx < this->map_to_output_.size());
this->map_to_output_[shndx].offset = off;
}
// Return true if we need to wait for output sections to be written
// before we can apply relocations. This is true if the object has
// any relocations for sections which require special handling, such
// as the exception frame section.
bool
relocs_must_follow_section_writes() const
{ return this->relocs_must_follow_section_writes_; }
// Return the object merge map.
Object_merge_map*
merge_map() const
{ return this->object_merge_map_; }
// Set the object merge map.
void
set_merge_map(Object_merge_map* object_merge_map)
{
gold_assert(this->object_merge_map_ == NULL);
this->object_merge_map_ = object_merge_map;
}
// Record the relocatable reloc info for an input reloc section.
void
set_relocatable_relocs(unsigned int reloc_shndx, Relocatable_relocs* rr)
{
gold_assert(reloc_shndx < this->shnum());
(*this->map_to_relocatable_relocs_)[reloc_shndx] = rr;
}
// Get the relocatable reloc info for an input reloc section.
Relocatable_relocs*
relocatable_relocs(unsigned int reloc_shndx)
{
gold_assert(reloc_shndx < this->shnum());
return (*this->map_to_relocatable_relocs_)[reloc_shndx];
}
protected:
// What we need to know to map an input section to an output
// section. We keep an array of these, one for each input section,
// indexed by the input section number.
struct Map_to_output
{
// The output section. This is NULL if the input section is to be
// discarded.
Output_section* output_section;
// The offset within the output section. This is -1 if the
// section requires special handling.
section_offset_type offset;
};
// Read the relocs--implemented by child class.
virtual void
do_read_relocs(Read_relocs_data*) = 0;
// Scan the relocs--implemented by child class.
virtual void
do_scan_relocs(const General_options&, Symbol_table*, Layout*,
Read_relocs_data*) = 0;
// Return the number of local symbols--implemented by child class.
virtual unsigned int
do_local_symbol_count() const = 0;
// Count local symbols--implemented by child class.
virtual void
do_count_local_symbols(Stringpool_template<char>*,
Stringpool_template<char>*) = 0;
// Finalize the local symbols. Set the output symbol table indexes
// for the local variables, and set the offset where local symbol
// information will be stored.
virtual unsigned int
do_finalize_local_symbols(unsigned int, off_t) = 0;
// Set the output dynamic symbol table indexes for the local variables.
virtual unsigned int
do_set_local_dynsym_indexes(unsigned int) = 0;
// Set the offset where local dynamic symbol information will be stored.
virtual unsigned int
do_set_local_dynsym_offset(off_t) = 0;
// Relocate the input sections and write out the local
// symbols--implemented by child class.
virtual void
do_relocate(const General_options& options, const Symbol_table* symtab,
const Layout*, Output_file* of) = 0;
// Return the vector mapping input sections to output sections.
std::vector<Map_to_output>&
map_to_output()
{ return this->map_to_output_; }
const std::vector<Map_to_output>&
map_to_output() const
{ return this->map_to_output_; }
// Set the size of the relocatable relocs array.
void
size_relocatable_relocs()
{
this->map_to_relocatable_relocs_ =
new std::vector<Relocatable_relocs*>(this->shnum());
}
// Record that we must wait for the output sections to be written
// before applying relocations.
void
set_relocs_must_follow_section_writes()
{ this->relocs_must_follow_section_writes_ = true; }
private:
// Mapping from input sections to output section.
std::vector<Map_to_output> map_to_output_;
// Mapping from input section index to the information recorded for
// the relocations. This is only used for a relocatable link.
std::vector<Relocatable_relocs*>* map_to_relocatable_relocs_;
// Mappings for merge sections. This is managed by the code in the
// Merge_map class.
Object_merge_map* object_merge_map_;
// Whether we need to wait for output sections to be written before
// we can apply relocations.
bool relocs_must_follow_section_writes_;
};
// Implement Object::output_section inline for efficiency.
inline Output_section*
Relobj::output_section(unsigned int shndx, section_offset_type* poff) const
{
gold_assert(shndx < this->map_to_output_.size());
const Map_to_output& mo(this->map_to_output_[shndx]);
*poff = mo.offset;
return mo.output_section;
}
// This class is used to handle relocations against a section symbol
// in an SHF_MERGE section. For such a symbol, we need to know the
// addend of the relocation before we can determine the final value.
// The addend gives us the location in the input section, and we can
// determine how it is mapped to the output section. For a
// non-section symbol, we apply the addend to the final value of the
// symbol; that is done in finalize_local_symbols, and does not use
// this class.
template<int size>
class Merged_symbol_value
{
public:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
// We use a hash table to map offsets in the input section to output
// addresses.
typedef Unordered_map<section_offset_type, Value> Output_addresses;
Merged_symbol_value(Value input_value, Value output_start_address)
: input_value_(input_value), output_start_address_(output_start_address),
output_addresses_()
{ }
// Initialize the hash table.
void
initialize_input_to_output_map(const Relobj*, unsigned int input_shndx);
// Release the hash table to save space.
void
free_input_to_output_map()
{ this->output_addresses_.clear(); }
// Get the output value corresponding to an addend. The object and
// input section index are passed in because the caller will have
// them; otherwise we could store them here.
Value
value(const Relobj* object, unsigned int input_shndx, Value addend) const
{
Value input_offset = this->input_value_ + addend;
typename Output_addresses::const_iterator p =
this->output_addresses_.find(input_offset);
if (p != this->output_addresses_.end())
return p->second;
return this->value_from_output_section(object, input_shndx, input_offset);
}
private:
// Get the output value for an input offset if we couldn't find it
// in the hash table.
Value
value_from_output_section(const Relobj*, unsigned int input_shndx,
Value input_offset) const;
// The value of the section symbol in the input file. This is
// normally zero, but could in principle be something else.
Value input_value_;
// The start address of this merged section in the output file.
Value output_start_address_;
// A hash table which maps offsets in the input section to output
// addresses. This only maps specific offsets, not all offsets.
Output_addresses output_addresses_;
};
// This POD class is holds the value of a symbol. This is used for
// local symbols, and for all symbols during relocation processing.
// For special sections, such as SHF_MERGE sections, this calls a
// function to get the final symbol value.
template<int size>
class Symbol_value
{
public:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
Symbol_value()
: output_symtab_index_(0), output_dynsym_index_(-1U), input_shndx_(0),
is_section_symbol_(false), is_tls_symbol_(false),
has_output_value_(true)
{ this->u_.value = 0; }
// Get the value of this symbol. OBJECT is the object in which this
// symbol is defined, and ADDEND is an addend to add to the value.
template<bool big_endian>
Value
value(const Sized_relobj<size, big_endian>* object, Value addend) const
{
if (this->has_output_value_)
return this->u_.value + addend;
else
return this->u_.merged_symbol_value->value(object, this->input_shndx_,
addend);
}
// Set the value of this symbol in the output symbol table.
void
set_output_value(Value value)
{ this->u_.value = value; }
// For a section symbol in a merged section, we need more
// information.
void
set_merged_symbol_value(Merged_symbol_value<size>* msv)
{
gold_assert(this->is_section_symbol_);
this->has_output_value_ = false;
this->u_.merged_symbol_value = msv;
}
// Initialize the input to output map for a section symbol in a
// merged section. We also initialize the value of a non-section
// symbol in a merged section.
void
initialize_input_to_output_map(const Relobj* object)
{
if (!this->has_output_value_)
{
gold_assert(this->is_section_symbol_);
Merged_symbol_value<size>* msv = this->u_.merged_symbol_value;
msv->initialize_input_to_output_map(object, this->input_shndx_);
}
}
// Free the input to output map for a section symbol in a merged
// section.
void
free_input_to_output_map()
{
if (!this->has_output_value_)
this->u_.merged_symbol_value->free_input_to_output_map();
}
// Set the value of the symbol from the input file. This is only
// called by count_local_symbols, to communicate the value to
// finalize_local_symbols.
void
set_input_value(Value value)
{ this->u_.value = value; }
// Return the input value. This is only called by
// finalize_local_symbols.
Value
input_value() const
{ return this->u_.value; }
// Return whether this symbol should go into the output symbol
// table.
bool
needs_output_symtab_entry() const
{ return this->output_symtab_index_ != -1U; }
// Return the index in the output symbol table.
unsigned int
output_symtab_index() const
{
gold_assert(this->output_symtab_index_ != 0);
return this->output_symtab_index_;
}
// Set the index in the output symbol table.
void
set_output_symtab_index(unsigned int i)
{
gold_assert(this->output_symtab_index_ == 0);
this->output_symtab_index_ = i;
}
// Record that this symbol should not go into the output symbol
// table.
void
set_no_output_symtab_entry()
{
gold_assert(this->output_symtab_index_ == 0);
this->output_symtab_index_ = -1U;
}
// Set the index in the output dynamic symbol table.
void
set_needs_output_dynsym_entry()
{
gold_assert(!this->is_section_symbol());
this->output_dynsym_index_ = 0;
}
// Return whether this symbol should go into the output symbol
// table.
bool
needs_output_dynsym_entry() const
{
return this->output_dynsym_index_ != -1U;
}
// Record that this symbol should go into the dynamic symbol table.
void
set_output_dynsym_index(unsigned int i)
{
gold_assert(this->output_dynsym_index_ == 0);
this->output_dynsym_index_ = i;
}
// Return the index in the output dynamic symbol table.
unsigned int
output_dynsym_index() const
{
gold_assert(this->output_dynsym_index_ != 0
&& this->output_dynsym_index_ != -1U);
return this->output_dynsym_index_;
}
// Set the index of the input section in the input file.
void
set_input_shndx(unsigned int i)
{
this->input_shndx_ = i;
// input_shndx_ field is a bitfield, so make sure that the value
// fits.
gold_assert(this->input_shndx_ == i);
}
// Return the index of the input section in the input file.
unsigned int
input_shndx() const
{ return this->input_shndx_; }
// Whether this is a section symbol.
bool
is_section_symbol() const
{ return this->is_section_symbol_; }
// Record that this is a section symbol.
void
set_is_section_symbol()
{
gold_assert(!this->needs_output_dynsym_entry());
this->is_section_symbol_ = true;
}
// Record that this is a TLS symbol.
void
set_is_tls_symbol()
{ this->is_tls_symbol_ = true; }
// Return TRUE if this is a TLS symbol.
bool
is_tls_symbol() const
{ return this->is_tls_symbol_; }
private:
// The index of this local symbol in the output symbol table. This
// will be -1 if the symbol should not go into the symbol table.
unsigned int output_symtab_index_;
// The index of this local symbol in the dynamic symbol table. This
// will be -1 if the symbol should not go into the symbol table.
unsigned int output_dynsym_index_;
// The section index in the input file in which this symbol is
// defined.
unsigned int input_shndx_ : 29;
// Whether this is a STT_SECTION symbol.
bool is_section_symbol_ : 1;
// Whether this is a STT_TLS symbol.
bool is_tls_symbol_ : 1;
// Whether this symbol has a value for the output file. This is
// normally set to true during Layout::finalize, by
// finalize_local_symbols. It will be false for a section symbol in
// a merge section, as for such symbols we can not determine the
// value to use in a relocation until we see the addend.
bool has_output_value_ : 1;
union
{
// This is used if has_output_value_ is true. Between
// count_local_symbols and finalize_local_symbols, this is the
// value in the input file. After finalize_local_symbols, it is
// the value in the output file.
Value value;
// This is used if has_output_value_ is false. It points to the
// information we need to get the value for a merge section.
Merged_symbol_value<size>* merged_symbol_value;
} u_;
};
// A regular object file. This is size and endian specific.
template<int size, bool big_endian>
class Sized_relobj : public Relobj
{
public:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
typedef std::vector<Symbol*> Symbols;
typedef std::vector<Symbol_value<size> > Local_values;
Sized_relobj(const std::string& name, Input_file* input_file, off_t offset,
const typename elfcpp::Ehdr<size, big_endian>&);
~Sized_relobj();
// Set up the object file based on the ELF header.
void
setup(const typename elfcpp::Ehdr<size, big_endian>&);
// If SYM is the index of a global symbol in the object file's
// symbol table, return the Symbol object. Otherwise, return NULL.
Symbol*
global_symbol(unsigned int sym) const
{
if (sym >= this->local_symbol_count_)
{
gold_assert(sym - this->local_symbol_count_ < this->symbols_.size());
return this->symbols_[sym - this->local_symbol_count_];
}
return NULL;
}
// Return the section index of symbol SYM. Set *VALUE to its value
// in the object file. Note that for a symbol which is not defined
// in this object file, this will set *VALUE to 0 and return
// SHN_UNDEF; it will not return the final value of the symbol in
// the link.
unsigned int
symbol_section_and_value(unsigned int sym, Address* value);
// Return a pointer to the Symbol_value structure which holds the
// value of a local symbol.
const Symbol_value<size>*
local_symbol(unsigned int sym) const
{
gold_assert(sym < this->local_values_.size());
return &this->local_values_[sym];
}
// Return the index of local symbol SYM in the ordinary symbol
// table. A value of -1U means that the symbol is not being output.
unsigned int
symtab_index(unsigned int sym) const
{
gold_assert(sym < this->local_values_.size());
return this->local_values_[sym].output_symtab_index();
}
// Return the index of local symbol SYM in the dynamic symbol
// table. A value of -1U means that the symbol is not being output.
unsigned int
dynsym_index(unsigned int sym) const
{
gold_assert(sym < this->local_values_.size());
return this->local_values_[sym].output_dynsym_index();
}
// Return the input section index of local symbol SYM.
unsigned int
local_symbol_input_shndx(unsigned int sym) const
{
gold_assert(sym < this->local_values_.size());
return this->local_values_[sym].input_shndx();
}
// Return the appropriate Sized_target structure.
Sized_target<size, big_endian>*
sized_target()
{
return this->Object::sized_target
SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
SELECT_SIZE_ENDIAN_ONLY(size, big_endian));
}
// Return the value of the local symbol symndx.
Address
local_symbol_value(unsigned int symndx) const;
void
set_needs_output_dynsym_entry(unsigned int sym)
{
gold_assert(sym < this->local_values_.size());
this->local_values_[sym].set_needs_output_dynsym_entry();
}
// Return whether the local symbol SYMNDX has a GOT offset.
// For TLS symbols, the GOT entry will hold its tp-relative offset.
bool
local_has_got_offset(unsigned int symndx) const
{
return (this->local_got_offsets_.find(symndx)
!= this->local_got_offsets_.end());
}
// Return the GOT offset of the local symbol SYMNDX.
unsigned int
local_got_offset(unsigned int symndx) const
{
Local_got_offsets::const_iterator p =
this->local_got_offsets_.find(symndx);
gold_assert(p != this->local_got_offsets_.end());
return p->second;
}
// Set the GOT offset of the local symbol SYMNDX to GOT_OFFSET.
void
set_local_got_offset(unsigned int symndx, unsigned int got_offset)
{
std::pair<Local_got_offsets::iterator, bool> ins =
this->local_got_offsets_.insert(std::make_pair(symndx, got_offset));
gold_assert(ins.second);
}
// Return whether the local TLS symbol SYMNDX has a GOT offset.
// The GOT entry at this offset will contain a module index. If
// NEED_PAIR is true, a second entry immediately following the first
// will contain the dtv-relative offset.
bool
local_has_tls_got_offset(unsigned int symndx, bool need_pair) const
{
typename Local_tls_got_offsets::const_iterator p =
this->local_tls_got_offsets_.find(symndx);
if (p == this->local_tls_got_offsets_.end()
|| (need_pair && !p->second.have_pair_))
return false;
return true;
}
// Return the offset of the GOT entry for the local TLS symbol SYMNDX.
// If NEED_PAIR is true, we need the offset of a pair of GOT entries;
// otherwise we need the offset of the GOT entry for the module index.
unsigned int
local_tls_got_offset(unsigned int symndx, bool need_pair) const
{
typename Local_tls_got_offsets::const_iterator p =
this->local_tls_got_offsets_.find(symndx);
gold_assert(p != this->local_tls_got_offsets_.end());
gold_assert(!need_pair || p->second.have_pair_);
return p->second.got_offset_;
}
// Set the offset of the GOT entry for the local TLS symbol SYMNDX
// to GOT_OFFSET. If HAVE_PAIR is true, we have a pair of GOT entries;
// otherwise, we have just a single entry for the module index.
void
set_local_tls_got_offset(unsigned int symndx, unsigned int got_offset,
bool have_pair)
{
typename Local_tls_got_offsets::iterator p =
this->local_tls_got_offsets_.find(symndx);
if (p != this->local_tls_got_offsets_.end())
{
// An entry already existed for this symbol. This can happen
// if we see a relocation asking for the module index before
// a relocation asking for the pair. In that case, the original
// GOT entry will remain, but won't get used by any further
// relocations.
p->second.got_offset_ = got_offset;
gold_assert(have_pair);
p->second.have_pair_ = true;
}
else
{
std::pair<typename Local_tls_got_offsets::iterator, bool> ins =
this->local_tls_got_offsets_.insert(
std::make_pair(symndx, Tls_got_entry(got_offset, have_pair)));
gold_assert(ins.second);
}
}
// Return the name of the symbol that spans the given offset in the
// specified section in this object. This is used only for error
// messages and is not particularly efficient.
bool
get_symbol_location_info(unsigned int shndx, off_t offset,
Symbol_location_info* info);
protected:
// Read the symbols.
void
do_read_symbols(Read_symbols_data*);
// Return the number of local symbols.
unsigned int
do_local_symbol_count() const
{ return this->local_symbol_count_; }
// Lay out the input sections.
void
do_layout(Symbol_table*, Layout*, Read_symbols_data*);
// Add the symbols to the symbol table.
void
do_add_symbols(Symbol_table*, Read_symbols_data*);
// Read the relocs.
void
do_read_relocs(Read_relocs_data*);
// Scan the relocs and adjust the symbol table.
void
do_scan_relocs(const General_options&, Symbol_table*, Layout*,
Read_relocs_data*);
// Count the local symbols.
void
do_count_local_symbols(Stringpool_template<char>*,
Stringpool_template<char>*);
// Finalize the local symbols.
unsigned int
do_finalize_local_symbols(unsigned int, off_t);
// Set the offset where local dynamic symbol information will be stored.
unsigned int
do_set_local_dynsym_indexes(unsigned int);
// Set the offset where local dynamic symbol information will be stored.
unsigned int
do_set_local_dynsym_offset(off_t);
// Relocate the input sections and write out the local symbols.
void
do_relocate(const General_options& options, const Symbol_table* symtab,
const Layout*, Output_file* of);
// Get the size of a section.
uint64_t
do_section_size(unsigned int shndx)
{ return this->elf_file_.section_size(shndx); }
// Get the name of a section.
std::string
do_section_name(unsigned int shndx)
{ return this->elf_file_.section_name(shndx); }
// Return the location of the contents of a section.
Object::Location
do_section_contents(unsigned int shndx)
{ return this->elf_file_.section_contents(shndx); }
// Return section flags.
uint64_t
do_section_flags(unsigned int shndx)
{ return this->elf_file_.section_flags(shndx); }
// Return section address.
uint64_t
do_section_address(unsigned int shndx)
{ return this->elf_file_.section_addr(shndx); }
// Return section type.
unsigned int
do_section_type(unsigned int shndx)
{ return this->elf_file_.section_type(shndx); }
// Return the section link field.
unsigned int
do_section_link(unsigned int shndx)
{ return this->elf_file_.section_link(shndx); }
// Return the section info field.
unsigned int
do_section_info(unsigned int shndx)
{ return this->elf_file_.section_info(shndx); }
// Return the section alignment.
uint64_t
do_section_addralign(unsigned int shndx)
{ return this->elf_file_.section_addralign(shndx); }
private:
// For convenience.
typedef Sized_relobj<size, big_endian> This;
static const int ehdr_size = elfcpp::Elf_sizes<size>::ehdr_size;
static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
typedef elfcpp::Shdr<size, big_endian> Shdr;
// Find the SHT_SYMTAB section, given the section headers.
void
find_symtab(const unsigned char* pshdrs);
// Return whether SHDR has the right flags for a GNU style exception
// frame section.
bool
check_eh_frame_flags(const elfcpp::Shdr<size, big_endian>* shdr) const;
// Return whether there is a section named .eh_frame which might be
// a GNU style exception frame section.
bool
find_eh_frame(const unsigned char* pshdrs, const char* names,
section_size_type names_size) const;
// Whether to include a section group in the link.
bool
include_section_group(Symbol_table*, Layout*, unsigned int, const char*,
const elfcpp::Shdr<size, big_endian>&,
std::vector<bool>*);
// Whether to include a linkonce section in the link.
bool
include_linkonce_section(Layout*, const char*,
const elfcpp::Shdr<size, big_endian>&);
// Views and sizes when relocating.
struct View_size
{
unsigned char* view;
typename elfcpp::Elf_types<size>::Elf_Addr address;
off_t offset;
section_size_type view_size;
bool is_input_output_view;
bool is_postprocessing_view;
};
typedef std::vector<View_size> Views;
// Write section data to the output file. Record the views and
// sizes in VIEWS for use when relocating.
void
write_sections(const unsigned char* pshdrs, Output_file*, Views*);
// Relocate the sections in the output file.
void
relocate_sections(const General_options& options, const Symbol_table*,
const Layout*, const unsigned char* pshdrs, Views*);
// Initialize input to output maps for section symbols in merged
// sections.
void
initialize_input_to_output_maps();
// Free the input to output maps for section symbols in merged
// sections.
void
free_input_to_output_maps();
// Write out the local symbols.
void
write_local_symbols(Output_file*,
const Stringpool_template<char>*,
const Stringpool_template<char>*);
// Clear the local symbol information.
void
clear_local_symbols()
{
this->local_values_.clear();
this->local_got_offsets_.clear();
this->local_tls_got_offsets_.clear();
}
// The GOT offsets of local symbols. This map also stores GOT offsets
// for tp-relative offsets for TLS symbols.
typedef Unordered_map<unsigned int, unsigned int> Local_got_offsets;
// The TLS GOT offsets of local symbols. The map stores the offsets
// for either a single GOT entry that holds the module index of a TLS
// symbol, or a pair of GOT entries containing the module index and
// dtv-relative offset.
struct Tls_got_entry
{
Tls_got_entry(int got_offset, bool have_pair)
: got_offset_(got_offset),
have_pair_(have_pair)
{ }
int got_offset_;
bool have_pair_;
};
typedef Unordered_map<unsigned int, Tls_got_entry> Local_tls_got_offsets;
// General access to the ELF file.
elfcpp::Elf_file<size, big_endian, Object> elf_file_;
// Index of SHT_SYMTAB section.
unsigned int symtab_shndx_;
// The number of local symbols.
unsigned int local_symbol_count_;
// The number of local symbols which go into the output file.
unsigned int output_local_symbol_count_;
// The number of local symbols which go into the output file's dynamic
// symbol table.
unsigned int output_local_dynsym_count_;
// The entries in the symbol table for the external symbols.
Symbols symbols_;
// File offset for local symbols.
off_t local_symbol_offset_;
// File offset for local dynamic symbols.
off_t local_dynsym_offset_;
// Values of local symbols.
Local_values local_values_;
// GOT offsets for local non-TLS symbols, and tp-relative offsets
// for TLS symbols, indexed by symbol number.
Local_got_offsets local_got_offsets_;
// GOT offsets for local TLS symbols, indexed by symbol number
// and GOT entry type.
Local_tls_got_offsets local_tls_got_offsets_;
// Whether this object has a GNU style .eh_frame section.
bool has_eh_frame_;
};
// A class to manage the list of all objects.
class Input_objects
{
public:
Input_objects()
: relobj_list_(), dynobj_list_(), sonames_(), system_library_directory_()
{ }
// The type of the list of input relocateable objects.
typedef std::vector<Relobj*> Relobj_list;
typedef Relobj_list::const_iterator Relobj_iterator;
// The type of the list of input dynamic objects.
typedef std::vector<Dynobj*> Dynobj_list;
typedef Dynobj_list::const_iterator Dynobj_iterator;
// Add an object to the list. Return true if all is well, or false
// if this object should be ignored.
bool
add_object(Object*);
// For each dynamic object, check whether we've seen all of its
// explicit dependencies.
void
check_dynamic_dependencies() const;
// Return whether an object was found in the system library
// directory.
bool
found_in_system_library_directory(const Object*) const;
// Iterate over all regular objects.
Relobj_iterator
relobj_begin() const
{ return this->relobj_list_.begin(); }
Relobj_iterator
relobj_end() const
{ return this->relobj_list_.end(); }
// Iterate over all dynamic objects.
Dynobj_iterator
dynobj_begin() const
{ return this->dynobj_list_.begin(); }
Dynobj_iterator
dynobj_end() const
{ return this->dynobj_list_.end(); }
// Return whether we have seen any dynamic objects.
bool
any_dynamic() const
{ return !this->dynobj_list_.empty(); }
// Return the number of input objects.
int
number_of_input_objects() const
{ return this->relobj_list_.size() + this->dynobj_list_.size(); }
private:
Input_objects(const Input_objects&);
Input_objects& operator=(const Input_objects&);
// The list of ordinary objects included in the link.
Relobj_list relobj_list_;
// The list of dynamic objects included in the link.
Dynobj_list dynobj_list_;
// SONAMEs that we have seen.
Unordered_set<std::string> sonames_;
// The directory in which we find the libc.so.
std::string system_library_directory_;
};
// Some of the information we pass to the relocation routines. We
// group this together to avoid passing a dozen different arguments.
template<int size, bool big_endian>
struct Relocate_info
{
// Command line options.
const General_options* options;
// Symbol table.
const Symbol_table* symtab;
// Layout.
const Layout* layout;
// Object being relocated.
Sized_relobj<size, big_endian>* object;
// Section index of relocation section.
unsigned int reloc_shndx;
// Section index of section being relocated.
unsigned int data_shndx;
// Return a string showing the location of a relocation. This is
// only used for error messages.
std::string
location(size_t relnum, off_t reloffset) const;
};
// Return an Object appropriate for the input file. P is BYTES long,
// and holds the ELF header.
extern Object*
make_elf_object(const std::string& name, Input_file*,
off_t offset, const unsigned char* p,
section_offset_type bytes);
} // end namespace gold
#endif // !defined(GOLD_OBJECT_H)