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// object.h -- support for an object file for linking in gold -*- C++ -*-
// Copyright 2006, 2007, 2008, 2009, 2010 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"
#include "archive.h"
namespace gold
{
class General_options;
class Task;
class Cref;
class Layout;
class Output_section;
class Output_file;
class Output_symtab_xindex;
class Pluginobj;
class Dynobj;
class Object_merge_map;
class Relocatable_relocs;
class Symbols_data;
template<typename Stringpool_char>
class Stringpool_template;
// Data to pass from read_symbols() to add_symbols().
struct Read_symbols_data
{
Read_symbols_data()
: section_headers(NULL), section_names(NULL), symbols(NULL),
symbol_names(NULL), versym(NULL), verdef(NULL), verneed(NULL)
{ }
~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
{
Section_relocs()
: contents(NULL)
{ }
~Section_relocs()
{ delete this->contents; }
// 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;
// Whether the data section is allocated (has the SHF_ALLOC flag set).
bool is_data_section_allocated;
};
// Relocations in an object file. This is read in read_relocs and
// processed in scan_relocs.
struct Read_relocs_data
{
Read_relocs_data()
: local_symbols(NULL)
{ }
~Read_relocs_data()
{ delete this->local_symbols; }
typedef std::vector<Section_relocs> Relocs_list;
// The relocations.
Relocs_list relocs;
// The local symbols.
File_view* local_symbols;
};
// The Xindex class manages section indexes for objects with more than
// 0xff00 sections.
class Xindex
{
public:
Xindex(int large_shndx_offset)
: large_shndx_offset_(large_shndx_offset), symtab_xindex_()
{ }
// Initialize the symtab_xindex_ array, given the object and the
// section index of the symbol table to use.
template<int size, bool big_endian>
void
initialize_symtab_xindex(Object*, unsigned int symtab_shndx);
// Read in the symtab_xindex_ array, given its section index.
// PSHDRS may optionally point to the section headers.
template<int size, bool big_endian>
void
read_symtab_xindex(Object*, unsigned int xindex_shndx,
const unsigned char* pshdrs);
// Symbol SYMNDX in OBJECT has a section of SHN_XINDEX; return the
// real section index.
unsigned int
sym_xindex_to_shndx(Object* object, unsigned int symndx);
private:
// The type of the array giving the real section index for symbols
// whose st_shndx field holds SHN_XINDEX.
typedef std::vector<unsigned int> Symtab_xindex;
// Adjust a section index if necessary. This should only be called
// for ordinary section indexes.
unsigned int
adjust_shndx(unsigned int shndx)
{
if (shndx >= elfcpp::SHN_LORESERVE)
shndx += this->large_shndx_offset_;
return shndx;
}
// Adjust to apply to large section indexes.
int large_shndx_offset_;
// The data from the SHT_SYMTAB_SHNDX section.
Symtab_xindex symtab_xindex_;
};
// 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:
typedef std::vector<Symbol*> Symbols;
// 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), is_needed_(false), uses_split_stack_(false),
has_no_split_stack_(false), no_export_(false), xindex_(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 whether this object is needed--true if it is a dynamic
// object which defines some symbol referenced by a regular object.
// We keep the flag here rather than in Dynobj for convenience when
// setting it.
bool
is_needed() const
{ return this->is_needed_; }
// Record that this object is needed.
void
set_is_needed()
{ this->is_needed_ = true; }
// Return whether this object was compiled with -fsplit-stack.
bool
uses_split_stack() const
{ return this->uses_split_stack_; }
// Return whether this object contains any functions compiled with
// the no_split_stack attribute.
bool
has_no_split_stack() const
{ return this->has_no_split_stack_; }
// Returns NULL for Objects that are not plugin objects. This method
// is overridden in the Pluginobj class.
Pluginobj*
pluginobj()
{ return this->do_pluginobj(); }
// 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_; }
// 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(); }
// 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);
// Adjust a symbol's section index as needed. SYMNDX is the index
// of the symbol and SHNDX is the symbol's section from
// get_st_shndx. This returns the section index. It sets
// *IS_ORDINARY to indicate whether this is a normal section index,
// rather than a special code between SHN_LORESERVE and
// SHN_HIRESERVE.
unsigned int
adjust_sym_shndx(unsigned int symndx, unsigned int shndx, bool* is_ordinary)
{
if (shndx < elfcpp::SHN_LORESERVE)
*is_ordinary = true;
else if (shndx == elfcpp::SHN_XINDEX)
{
if (this->xindex_ == NULL)
this->xindex_ = this->do_initialize_xindex();
shndx = this->xindex_->sym_xindex_to_shndx(this, symndx);
*is_ordinary = true;
}
else
*is_ordinary = false;
return shndx;
}
// 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 entsize given a section index.
uint64_t
section_entsize(unsigned int shndx)
{ return this->do_section_entsize(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, Layout *layout)
{ this->do_add_symbols(symtab, sd, layout); }
// Add symbol information to the global symbol table.
Archive::Should_include
should_include_member(Symbol_table* symtab, Layout* layout,
Read_symbols_data* sd, std::string* why)
{ return this->do_should_include_member(symtab, layout, sd, why); }
// 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, 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, true)); }
// Get a view into the underlying file.
const unsigned char*
get_view(off_t start, section_size_type size, bool aligned, bool cache)
{
return this->input_file()->file().get_view(this->offset_, start, size,
aligned, cache);
}
// Get a lasting view into the underlying file.
File_view*
get_lasting_view(off_t start, section_size_type size, bool aligned,
bool cache)
{
return this->input_file()->file().get_lasting_view(this->offset_, start,
size, aligned, cache);
}
// Read data from the underlying file.
void
read(off_t start, section_size_type size, void* p)
{ 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(); }
// Get the number of global symbols defined by this object, and the
// number of the symbols whose final definition came from this
// object.
void
get_global_symbol_counts(const Symbol_table* symtab, size_t* defined,
size_t* used) const
{ this->do_get_global_symbol_counts(symtab, defined, used); }
// Get the symbols defined in this object.
const Symbols*
get_global_symbols() const
{ return this->do_get_global_symbols(); }
// Return whether this object was found in a system directory.
bool
is_in_system_directory() const
{ return this->input_file()->is_in_system_directory(); }
// Return whether we found this object by searching a directory.
bool
searched_for() const
{ return this->input_file()->will_search_for(); }
bool
no_export() const
{ return this->no_export_; }
void
set_no_export(bool value)
{ this->no_export_ = value; }
// Return TRUE if the section is a compressed debug section, and set
// *UNCOMPRESSED_SIZE to the size of the uncompressed data.
bool
section_is_compressed(unsigned int shndx,
section_size_type* uncompressed_size) const
{ return this->do_section_is_compressed(shndx, uncompressed_size); }
protected:
// Returns NULL for Objects that are not plugin objects. This method
// is overridden in the Pluginobj class.
virtual Pluginobj*
do_pluginobj()
{ return NULL; }
// 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*, Layout*) = 0;
virtual Archive::Should_include
do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
std::string* why) = 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 entsize--implemented by child class.
virtual uint64_t
do_section_entsize(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;
// Return the Xindex structure to use.
virtual Xindex*
do_initialize_xindex() = 0;
// Implement get_global_symbol_counts--implemented by child class.
virtual void
do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const = 0;
virtual const Symbols*
do_get_global_symbols() const = 0;
// 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*);
// Let the child class initialize the xindex object directly.
void
set_xindex(Xindex* xindex)
{
gold_assert(this->xindex_ == NULL);
this->xindex_ = xindex;
}
// 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*);
// If NAME is the name of the special section which indicates that
// this object was compiled with -fstack-split, mark it accordingly,
// and return true. Otherwise return false.
bool
handle_split_stack_section(const char* name);
// Return TRUE if the section is a compressed debug section, and set
// *UNCOMPRESSED_SIZE to the size of the uncompressed data.
virtual bool
do_section_is_compressed(unsigned int, section_size_type*) const
{ return false; }
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_ : 1;
// Whether this object is needed. This is only set for dynamic
// objects, and means that the object defined a symbol which was
// used by a reference from a regular object.
bool is_needed_ : 1;
// Whether this object was compiled with -fsplit-stack.
bool uses_split_stack_ : 1;
// Whether this object contains any functions compiled with the
// no_split_stack attribute.
bool has_no_split_stack_ : 1;
// True if exclude this object from automatic symbol export.
// This is used only for archive objects.
bool no_export_ : 1;
// Many sections for objects with more than SHN_LORESERVE sections.
Xindex* xindex_;
};
// 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),
output_sections_(),
map_to_relocatable_relocs_(NULL),
object_merge_map_(NULL),
relocs_must_follow_section_writes_(false),
sd_(NULL)
{ }
// During garbage collection, the Read_symbols_data pass for
// each object is stored as layout needs to be done after
// reloc processing.
Symbols_data*
get_symbols_data()
{ return this->sd_; }
// Decides which section names have to be included in the worklist
// as roots.
bool
is_section_name_included(const char *name);
void
copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
unsigned int section_header_size);
void
set_symbols_data(Symbols_data* sd)
{ this->sd_ = sd; }
// During garbage collection, the Read_relocs pass for all objects
// is done before scanning the relocs. In that case, this->rd_ is
// used to store the information from Read_relocs for each object.
// This data is also used to compute the list of relevant sections.
Read_relocs_data*
get_relocs_data()
{ return this->rd_; }
void
set_relocs_data(Read_relocs_data* rd)
{ this->rd_ = rd; }
virtual bool
is_output_section_offset_invalid(unsigned int shndx) const = 0;
// Read the relocs.
void
read_relocs(Read_relocs_data* rd)
{ return this->do_read_relocs(rd); }
// Process the relocs, during garbage collection only.
void
gc_process_relocs(Symbol_table* symtab, Layout* layout, Read_relocs_data* rd)
{ return this->do_gc_process_relocs(symtab, layout, rd); }
// Scan the relocs and adjust the symbol table.
void
scan_relocs(Symbol_table* symtab, Layout* layout, Read_relocs_data* rd)
{ return this->do_scan_relocs(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, Symbol_table* symtab)
{ return this->do_finalize_local_symbols(index, off, symtab); }
// 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 Symbol_table* symtab, const Layout* layout, Output_file* of)
{ return this->do_relocate(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->output_sections_.size());
return this->output_sections_[shndx] != NULL;
}
// Given a section index, return the corresponding Output_section.
// The return value will be NULL if the section is not included in
// the link.
Output_section*
output_section(unsigned int shndx) const
{
gold_assert(shndx < this->output_sections_.size());
return this->output_sections_[shndx];
}
// The the output section of the input section with index SHNDX.
// This is only used currently to remove a section from the link in
// relaxation.
void
set_output_section(unsigned int shndx, Output_section* os)
{
gold_assert(shndx < this->output_sections_.size());
this->output_sections_[shndx] = os;
}
// Given a section index, return the offset in the Output_section.
// The return value will be -1U if the section is specially mapped,
// such as a merge section.
uint64_t
output_section_offset(unsigned int shndx) const
{ return this->do_output_section_offset(shndx); }
// Set the offset of an input section within its output section.
void
set_section_offset(unsigned int shndx, uint64_t off)
{ this->do_set_section_offset(shndx, 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];
}
// Layout sections whose layout was deferred while waiting for
// input files from a plugin.
void
layout_deferred_sections(Layout* layout)
{ this->do_layout_deferred_sections(layout); }
protected:
// The output section to be used for each input section, indexed by
// the input section number. The output section is NULL if the
// input section is to be discarded.
typedef std::vector<Output_section*> Output_sections;
// Read the relocs--implemented by child class.
virtual void
do_read_relocs(Read_relocs_data*) = 0;
// Process the relocs--implemented by child class.
virtual void
do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*) = 0;
// Scan the relocs--implemented by child class.
virtual void
do_scan_relocs(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, Symbol_table*) = 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 Symbol_table* symtab, const Layout*, Output_file* of) = 0;
// Get the offset of a section--implemented by child class.
virtual uint64_t
do_output_section_offset(unsigned int shndx) const = 0;
// Set the offset of a section--implemented by child class.
virtual void
do_set_section_offset(unsigned int shndx, uint64_t off) = 0;
// Layout sections whose layout was deferred while waiting for
// input files from a plugin--implemented by child class.
virtual void
do_layout_deferred_sections(Layout*) = 0;
// Return the vector mapping input sections to output sections.
Output_sections&
output_sections()
{ return this->output_sections_; }
const Output_sections&
output_sections() const
{ return this->output_sections_; }
// 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.
Output_sections output_sections_;
// 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_;
// Used to store the relocs data computed by the Read_relocs pass.
// Used during garbage collection of unused sections.
Read_relocs_data* rd_;
// Used to store the symbols data computed by the Read_symbols pass.
// Again used during garbage collection when laying out referenced
// sections.
gold::Symbols_data *sd_;
};
// 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
{
// This is a relocation against a section symbol. ADDEND is the
// offset in the section. The result should be the start of some
// merge area. If the object file wants something else, it should
// use a regular symbol rather than a section symbol.
// Unfortunately, PR 6658 shows a case in which the object file
// refers to the section symbol, but uses a negative ADDEND to
// compensate for a PC relative reloc. We can't handle the
// general case. However, we can handle the special case of a
// negative addend, by assuming that it refers to the start of the
// section. Of course, that means that we have to guess when
// ADDEND is negative. It is normal to see a 32-bit value here
// even when the template parameter size is 64, as 64-bit object
// file formats have 32-bit relocations. We know this is a merge
// section, so we know it has to fit into memory. So we assume
// that we won't see a value larger than a large 32-bit unsigned
// value. This will break objects with very very large merge
// sections; they probably break in other ways anyhow.
Value input_offset = this->input_value_;
if (addend < 0xffffff00)
{
input_offset += addend;
addend = 0;
}
typename Output_addresses::const_iterator p =
this->output_addresses_.find(input_offset);
if (p != this->output_addresses_.end())
return p->second + addend;
return (this->value_from_output_section(object, input_shndx, input_offset)
+ addend);
}
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_ordinary_shndx_(false), 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
{
gold_assert(this->is_ordinary_shndx_);
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_ && this->is_ordinary_shndx_);
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 and (in special cases) relocate_section.
Value
input_value() const
{ return this->u_.value; }
// Return whether we have set the index in the output symbol table
// yet.
bool
is_output_symtab_index_set() const
{
return (this->output_symtab_index_ != 0
&& this->output_symtab_index_ != -2U);
}
// Return whether this symbol may be discarded from the normal
// symbol table.
bool
may_be_discarded_from_output_symtab() const
{
gold_assert(!this->is_output_symtab_index_set());
return this->output_symtab_index_ != -2U;
}
// Return whether this symbol has an entry in the output symbol
// table.
bool
has_output_symtab_entry() const
{
gold_assert(this->is_output_symtab_index_set());
return this->output_symtab_index_ != -1U;
}
// Return the index in the output symbol table.
unsigned int
output_symtab_index() const
{
gold_assert(this->is_output_symtab_index_set()
&& this->output_symtab_index_ != -1U);
return this->output_symtab_index_;
}
// Set the index in the output symbol table.
void
set_output_symtab_index(unsigned int i)
{
gold_assert(!this->is_output_symtab_index_set());
gold_assert(i != 0 && i != -1U && i != -2U);
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;
}
// Record that this symbol must go into the output symbol table,
// because it there is a relocation that uses it.
void
set_must_have_output_symtab_entry()
{
gold_assert(!this->is_output_symtab_index_set());
this->output_symtab_index_ = -2U;
}
// 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 dynamic symbol
// table.
bool
needs_output_dynsym_entry() const
{
return this->output_dynsym_index_ != -1U;
}
// Return whether this symbol has an entry in the dynamic symbol
// table.
bool
has_output_dynsym_entry() const
{
gold_assert(this->output_dynsym_index_ != 0);
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);
gold_assert(i != 0 && i != -1U);
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, bool is_ordinary)
{
this->input_shndx_ = i;
// input_shndx_ field is a bitfield, so make sure that the value
// fits.
gold_assert(this->input_shndx_ == i);
this->is_ordinary_shndx_ = is_ordinary;
}
// Return the index of the input section in the input file.
unsigned int
input_shndx(bool* is_ordinary) const
{
*is_ordinary = this->is_ordinary_shndx_;
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 0 if no value has been assigned yet, and the symbol may
// be omitted. This will be -1U if the symbol should not go into
// the symbol table. This will be -2U if the symbol must go into
// the symbol table, but no index has been assigned yet.
unsigned int output_symtab_index_;
// The index of this local symbol in the dynamic symbol table. This
// will be -1U 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_ : 28;
// Whether the section index is an ordinary index, not a special
// value.
bool is_ordinary_shndx_ : 1;
// 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 GOT offset list. A symbol may have more than one GOT offset
// (e.g., when mixing modules compiled with two different TLS models),
// but will usually have at most one. GOT_TYPE identifies the type of
// GOT entry; its values are specific to each target.
class Got_offset_list
{
public:
Got_offset_list()
: got_type_(-1U), got_offset_(0), got_next_(NULL)
{ }
Got_offset_list(unsigned int got_type, unsigned int got_offset)
: got_type_(got_type), got_offset_(got_offset), got_next_(NULL)
{ }
~Got_offset_list()
{
if (this->got_next_ != NULL)
{
delete this->got_next_;
this->got_next_ = NULL;
}
}
// Initialize the fields to their default values.
void
init()
{
this->got_type_ = -1U;
this->got_offset_ = 0;
this->got_next_ = NULL;
}
// Set the offset for the GOT entry of type GOT_TYPE.
void
set_offset(unsigned int got_type, unsigned int got_offset)
{
if (this->got_type_ == -1U)
{
this->got_type_ = got_type;
this->got_offset_ = got_offset;
}
else
{
for (Got_offset_list* g = this; g != NULL; g = g->got_next_)
{
if (g->got_type_ == got_type)
{
g->got_offset_ = got_offset;
return;
}
}
Got_offset_list* g = new Got_offset_list(got_type, got_offset);
g->got_next_ = this->got_next_;
this->got_next_ = g;
}
}
// Return the offset for a GOT entry of type GOT_TYPE.
unsigned int
get_offset(unsigned int got_type) const
{
for (const Got_offset_list* g = this; g != NULL; g = g->got_next_)
{
if (g->got_type_ == got_type)
return g->got_offset_;
}
return -1U;
}
private:
unsigned int got_type_;
unsigned int got_offset_;
Got_offset_list* got_next_;
};
// This type is used to modify relocations for -fsplit-stack. It is
// indexed by relocation index, and means that the relocation at that
// index should use the symbol from the vector, rather than the one
// indicated by the relocation.
class Reloc_symbol_changes
{
public:
Reloc_symbol_changes(size_t count)
: vec_(count, NULL)
{ }
void
set(size_t i, Symbol* sym)
{ this->vec_[i] = sym; }
const Symbol*
operator[](size_t i) const
{ return this->vec_[i]; }
private:
std::vector<Symbol*> vec_;
};
// Type for mapping section index to uncompressed size.
typedef std::map<unsigned int, section_size_type> Compressed_section_map;
// 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;
static const Address invalid_address = static_cast<Address>(0) - 1;
Sized_relobj(const std::string& name, Input_file* input_file, off_t offset,
const typename elfcpp::Ehdr<size, big_endian>&);
~Sized_relobj();
// Checks if the offset of input section SHNDX within its output
// section is invalid.
bool
is_output_section_offset_invalid(unsigned int shndx) const
{ return this->get_output_section_offset(shndx) == invalid_address; }
// Set up the object file based on TARGET.
void
setup()
{ this->do_setup(); }
// Return the number of symbols. This is only valid after
// Object::add_symbols has been called.
unsigned int
symbol_count() const
{ return this->local_symbol_count_ + this->symbols_.size(); }
// 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. Set *IS_ORDINARY if this is an ordinary
// section index, not a special code between SHN_LORESERVE and
// SHN_HIRESERVE. 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, bool* is_ordinary);
// 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, bool* is_ordinary) const
{
gold_assert(sym < this->local_values_.size());
return this->local_values_[sym].input_shndx(is_ordinary);
}
// Record that local symbol SYM must be in the output symbol table.
void
set_must_have_output_symtab_entry(unsigned int sym)
{
gold_assert(sym < this->local_values_.size());
this->local_values_[sym].set_must_have_output_symtab_entry();
}
// Record that local symbol SYM needs a dynamic symbol entry.
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, unsigned int got_type) const
{
Local_got_offsets::const_iterator p =
this->local_got_offsets_.find(symndx);
return (p != this->local_got_offsets_.end()
&& p->second->get_offset(got_type) != -1U);
}
// Return the GOT offset of the local symbol SYMNDX.
unsigned int
local_got_offset(unsigned int symndx, unsigned int got_type) const
{
Local_got_offsets::const_iterator p =
this->local_got_offsets_.find(symndx);
gold_assert(p != this->local_got_offsets_.end());
unsigned int off = p->second->get_offset(got_type);
gold_assert(off != -1U);
return off;
}
// Set the GOT offset of the local symbol SYMNDX to GOT_OFFSET.
void
set_local_got_offset(unsigned int symndx, unsigned int got_type,
unsigned int got_offset)
{
Local_got_offsets::const_iterator p =
this->local_got_offsets_.find(symndx);
if (p != this->local_got_offsets_.end())
p->second->set_offset(got_type, got_offset);
else
{
Got_offset_list* g = new Got_offset_list(got_type, got_offset);
std::pair<Local_got_offsets::iterator, bool> ins =
this->local_got_offsets_.insert(std::make_pair(symndx, g));
gold_assert(ins.second);
}
}
// Get the offset of input section SHNDX within its output section.
// This is -1 if the input section requires a special mapping, such
// as a merge section. The output section can be found in the
// output_sections_ field of the parent class Relobj.
Address
get_output_section_offset(unsigned int shndx) const
{
gold_assert(shndx < this->section_offsets_.size());
return this->section_offsets_[shndx];
}
// 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);
// Look for a kept section corresponding to the given discarded section,
// and return its output address. This is used only for relocations in
// debugging sections.
Address
map_to_kept_section(unsigned int shndx, bool* found) const;
protected:
// Set up.
virtual void
do_setup();
// 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*);
// Layout sections whose layout was deferred while waiting for
// input files from a plugin.
void
do_layout_deferred_sections(Layout*);
// Add the symbols to the symbol table.
void
do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*);
Archive::Should_include
do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
std::string* why);
// Read the relocs.
void
do_read_relocs(Read_relocs_data*);
// Process the relocs to find list of referenced sections. Used only
// during garbage collection.
void
do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*);
// Scan the relocs and adjust the symbol table.
void
do_scan_relocs(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, Symbol_table*);
// 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 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 section entsize.
uint64_t
do_section_entsize(unsigned int 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); }
// Return the Xindex structure to use.
Xindex*
do_initialize_xindex();
// Get symbol counts.
void
do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
// Get the global symbols.
const Symbols*
do_get_global_symbols() const
{ return &this->symbols_; }
// Get the offset of a section.
uint64_t
do_output_section_offset(unsigned int shndx) const
{
Address off = this->get_output_section_offset(shndx);
if (off == invalid_address)
return -1ULL;
return off;
}
// Set the offset of a section.
void
do_set_section_offset(unsigned int shndx, uint64_t off)
{
gold_assert(shndx < this->section_offsets_.size());
this->section_offsets_[shndx] =
(off == static_cast<uint64_t>(-1)
? invalid_address
: convert_types<Address, uint64_t>(off));
}
// Adjust a section index if necessary.
unsigned int
adjust_shndx(unsigned int shndx)
{
if (shndx >= elfcpp::SHN_LORESERVE)
shndx += this->elf_file_.large_shndx_offset();
return shndx;
}
// 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();
// Return symbol table section index.
unsigned int
symtab_shndx() const
{ return this->symtab_shndx_; }
// Allow a child class to access the ELF file.
elfcpp::Elf_file<size, big_endian, Object>*
elf_file()
{ return &this->elf_file_; }
// Allow a child class to access the local values.
Local_values*
local_values()
{ return &this->local_values_; }
// 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;
// This may be overriden by a child class.
virtual void
do_relocate_sections(const Symbol_table* symtab, const Layout* layout,
const unsigned char* pshdrs, Views* pviews);
// Allow a child to set output local symbol count.
void
set_output_local_symbol_count(unsigned int value)
{ this->output_local_symbol_count_ = value; }
// Return TRUE if the section is a compressed debug section, and set
// *UNCOMPRESSED_SIZE to the size of the uncompressed data.
bool
do_section_is_compressed(unsigned int shndx,
section_size_type* uncompressed_size) const
{
if (this->compressed_sections_ == NULL)
return false;
Compressed_section_map::const_iterator p =
this->compressed_sections_->find(shndx);
if (p != this->compressed_sections_->end())
{
if (uncompressed_size != NULL)
*uncompressed_size = p->second;
return true;
}
return false;
}
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;
// To keep track of discarded comdat sections, we need to map a member
// section index to the object and section index of the corresponding
// kept section.
struct Kept_comdat_section
{
Kept_comdat_section(Relobj* a_object, unsigned int a_shndx)
: object(a_object), shndx(a_shndx)
{ }
Relobj* object;
unsigned int shndx;
};
typedef std::map<unsigned int, Kept_comdat_section>
Kept_comdat_section_table;
// 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 unsigned char*, const char *, section_size_type,
std::vector<bool>*);
// Whether to include a linkonce section in the link.
bool
include_linkonce_section(Layout*, unsigned int, const char*,
const elfcpp::Shdr<size, big_endian>&);
// Layout an input section.
void
layout_section(Layout* layout, unsigned int shndx, const char* name,
typename This::Shdr& shdr, unsigned int reloc_shndx,
unsigned int reloc_type);
// 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 Symbol_table* symtab, const Layout* layout,
const unsigned char* pshdrs, Views* pviews)
{ this->do_relocate_sections(symtab, layout, pshdrs, pviews); }
// Scan the input relocations for --emit-relocs.
void
emit_relocs_scan(Symbol_table*, Layout*, const unsigned char* plocal_syms,
const Read_relocs_data::Relocs_list::iterator&);
// Scan the input relocations for --emit-relocs, templatized on the
// type of the relocation section.
template<int sh_type>
void
emit_relocs_scan_reltype(Symbol_table*, Layout*,
const unsigned char* plocal_syms,
const Read_relocs_data::Relocs_list::iterator&,
Relocatable_relocs*);
// Emit the relocs for --emit-relocs.
void
emit_relocs(const Relocate_info<size, big_endian>*, unsigned int,
unsigned int sh_type, const unsigned char* prelocs,
size_t reloc_count, Output_section*, Address output_offset,
unsigned char* view, Address address,
section_size_type view_size,
unsigned char* reloc_view, section_size_type reloc_view_size);
// Emit the relocs for --emit-relocs, templatized on the type of the
// relocation section.
template<int sh_type>
void
emit_relocs_reltype(const Relocate_info<size, big_endian>*, unsigned int,
const unsigned char* prelocs, size_t reloc_count,
Output_section*, Address output_offset,
unsigned char* view, Address address,
section_size_type view_size,
unsigned char* reloc_view,
section_size_type reloc_view_size);
// A type shared by split_stack_adjust_reltype and find_functions.
typedef std::map<section_offset_type, section_size_type> Function_offsets;
// Check for -fsplit-stack routines calling non-split-stack routines.
void
split_stack_adjust(const Symbol_table*, const unsigned char* pshdrs,
unsigned int sh_type, unsigned int shndx,
const unsigned char* prelocs, size_t reloc_count,
unsigned char* view, section_size_type view_size,
Reloc_symbol_changes** reloc_map);
template<int sh_type>
void
split_stack_adjust_reltype(const Symbol_table*, const unsigned char* pshdrs,
unsigned int shndx, const unsigned char* prelocs,
size_t reloc_count, unsigned char* view,
section_size_type view_size,
Reloc_symbol_changes** reloc_map);
// Find all functions in a section.
void
find_functions(const unsigned char* pshdrs, unsigned int shndx,
Function_offsets*);
// Write out the local symbols.
void
write_local_symbols(Output_file*,
const Stringpool_template<char>*,
const Stringpool_template<char>*,
Output_symtab_xindex*,
Output_symtab_xindex*);
// Clear the local symbol information.
void
clear_local_symbols()
{
this->local_values_.clear();
this->local_got_offsets_.clear();
}
// Record a mapping from discarded section SHNDX to the corresponding
// kept section.
void
set_kept_comdat_section(unsigned int shndx, Relobj* kept_object,
unsigned int kept_shndx)
{
Kept_comdat_section kept(kept_object, kept_shndx);
this->kept_comdat_sections_.insert(std::make_pair(shndx, kept));
}
// Find the kept section corresponding to the discarded section
// SHNDX. Return true if found.
bool
get_kept_comdat_section(unsigned int shndx, Relobj** kept_object,
unsigned int* kept_shndx) const
{
typename Kept_comdat_section_table::const_iterator p =
this->kept_comdat_sections_.find(shndx);
if (p == this->kept_comdat_sections_.end())
return false;
*kept_object = p->second.object;
*kept_shndx = p->second.shndx;
return true;
}
// The GOT offsets of local symbols. This map also stores GOT offsets
// for tp-relative offsets for TLS symbols.
typedef Unordered_map<unsigned int, Got_offset_list*> 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;
// Saved information for sections whose layout was deferred.
struct Deferred_layout
{
static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
Deferred_layout(unsigned int shndx, const char* name,
const unsigned char* pshdr,
unsigned int reloc_shndx, unsigned int reloc_type)
: shndx_(shndx), name_(name), reloc_shndx_(reloc_shndx),
reloc_type_(reloc_type)
{
memcpy(this->shdr_data_, pshdr, shdr_size);
}
unsigned int shndx_;
std::string name_;
unsigned int reloc_shndx_;
unsigned int reloc_type_;
unsigned char shdr_data_[shdr_size];
};
// 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_;
// Number of symbols defined in object file itself.
size_t defined_count_;
// 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_;
// For each input section, the offset of the input section in its
// output section. This is INVALID_ADDRESS if the input section requires a
// special mapping.
std::vector<Address> section_offsets_;
// Table mapping discarded comdat sections to corresponding kept sections.
Kept_comdat_section_table kept_comdat_sections_;
// Whether this object has a GNU style .eh_frame section.
bool has_eh_frame_;
// If this object has a GNU style .eh_frame section that is discarded in
// output, record the index here. Otherwise it is -1U.
unsigned int discarded_eh_frame_shndx_;
// The list of sections whose layout was deferred.
std::vector<Deferred_layout> deferred_layout_;
// The list of relocation sections whose layout was deferred.
std::vector<Deferred_layout> deferred_layout_relocs_;
// For compressed debug sections, map section index to uncompressed size.
Compressed_section_map* compressed_sections_;
};
// A class to manage the list of all objects.
class Input_objects
{
public:
Input_objects()
: relobj_list_(), dynobj_list_(), sonames_(), cref_(NULL)
{ }
// 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*);
// Start processing an archive.
void
archive_start(Archive*);
// Stop processing an archive.
void
archive_stop(Archive*);
// 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;
// Print symbol counts.
void
print_symbol_counts(const Symbol_table*) const;
// Print a cross reference table.
void
print_cref(const Symbol_table*, FILE*) 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 non dynamic objects.
int
number_of_relobjs() const
{ return this->relobj_list_.size(); }
// 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_;
// Manage cross-references if requested.
Cref* cref_;
};
// 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
{
// 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 header of relocation section.
const unsigned char* reloc_shdr;
// Section index of section being relocated.
unsigned int data_shndx;
// Section header of data section.
const unsigned char* data_shdr;
// 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;
};
// This is used to represent a section in an object and is used as the
// key type for various section maps.
typedef std::pair<Object*, unsigned int> Section_id;
// This is similar to Section_id but is used when the section
// pointers are const.
typedef std::pair<const Object*, unsigned int> Const_section_id;
// The hash value is based on the address of an object in memory during
// linking. It is okay to use this for looking up sections but never use
// this in an unordered container that we want to traverse in a repeatable
// manner.
struct Section_id_hash
{
size_t operator()(const Section_id& loc) const
{ return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
};
struct Const_section_id_hash
{
size_t operator()(const Const_section_id& loc) const
{ return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
};
// Return whether INPUT_FILE contains an ELF object start at file
// offset OFFSET. This sets *START to point to a view of the start of
// the file. It sets *READ_SIZE to the number of bytes in the view.
extern bool
is_elf_object(Input_file* input_file, off_t offset,
const unsigned char** start, int *read_size);
// Return an Object appropriate for the input file. P is BYTES long,
// and holds the ELF header. If PUNCONFIGURED is not NULL, then if
// this sees an object the linker is not configured to support, it
// sets *PUNCONFIGURED to true and returns NULL without giving an
// error message.
extern Object*
make_elf_object(const std::string& name, Input_file*,
off_t offset, const unsigned char* p,
section_offset_type bytes, bool* punconfigured);
} // end namespace gold
#endif // !defined(GOLD_OBJECT_H)
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