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binutils-gdb/gold/object.cc
Doug Kwan ac33a407ac 2009-11-10 Doug Kwan <dougkwan@google.com> 
* i386.cc (Target_i386::do_calls_non_split): Add a cast to avoid
	a format warning.
	* incremental.cc (open_incremental_binary): Initialized local
	variables to avoid warnings.
	* object.cc (make_elf_object): Ditto.
	* x86_64.cc (Target_x86_64::do_calls_non_split): Add a cast to avoid
	a format warning.
2009-11-09 23:07:30 +00:00

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// object.cc -- support for an object file for linking in gold
// Copyright 2006, 2007, 2008, 2009 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.
#include "gold.h"
#include <cerrno>
#include <cstring>
#include <cstdarg>
#include "demangle.h"
#include "libiberty.h"
#include "gc.h"
#include "target-select.h"
#include "dwarf_reader.h"
#include "layout.h"
#include "output.h"
#include "symtab.h"
#include "cref.h"
#include "reloc.h"
#include "object.h"
#include "dynobj.h"
#include "plugin.h"
namespace gold
{
// Class Xindex.
// Initialize the symtab_xindex_ array. Find the SHT_SYMTAB_SHNDX
// section and read it in. SYMTAB_SHNDX is the index of the symbol
// table we care about.
template<int size, bool big_endian>
void
Xindex::initialize_symtab_xindex(Object* object, unsigned int symtab_shndx)
{
if (!this->symtab_xindex_.empty())
return;
gold_assert(symtab_shndx != 0);
// Look through the sections in reverse order, on the theory that it
// is more likely to be near the end than the beginning.
unsigned int i = object->shnum();
while (i > 0)
{
--i;
if (object->section_type(i) == elfcpp::SHT_SYMTAB_SHNDX
&& this->adjust_shndx(object->section_link(i)) == symtab_shndx)
{
this->read_symtab_xindex<size, big_endian>(object, i, NULL);
return;
}
}
object->error(_("missing SHT_SYMTAB_SHNDX section"));
}
// Read in the symtab_xindex_ array, given the section index of the
// SHT_SYMTAB_SHNDX section. If PSHDRS is not NULL, it points at the
// section headers.
template<int size, bool big_endian>
void
Xindex::read_symtab_xindex(Object* object, unsigned int xindex_shndx,
const unsigned char* pshdrs)
{
section_size_type bytecount;
const unsigned char* contents;
if (pshdrs == NULL)
contents = object->section_contents(xindex_shndx, &bytecount, false);
else
{
const unsigned char* p = (pshdrs
+ (xindex_shndx
* elfcpp::Elf_sizes<size>::shdr_size));
typename elfcpp::Shdr<size, big_endian> shdr(p);
bytecount = convert_to_section_size_type(shdr.get_sh_size());
contents = object->get_view(shdr.get_sh_offset(), bytecount, true, false);
}
gold_assert(this->symtab_xindex_.empty());
this->symtab_xindex_.reserve(bytecount / 4);
for (section_size_type i = 0; i < bytecount; i += 4)
{
unsigned int shndx = elfcpp::Swap<32, big_endian>::readval(contents + i);
// We preadjust the section indexes we save.
this->symtab_xindex_.push_back(this->adjust_shndx(shndx));
}
}
// Symbol symndx has a section of SHN_XINDEX; return the real section
// index.
unsigned int
Xindex::sym_xindex_to_shndx(Object* object, unsigned int symndx)
{
if (symndx >= this->symtab_xindex_.size())
{
object->error(_("symbol %u out of range for SHT_SYMTAB_SHNDX section"),
symndx);
return elfcpp::SHN_UNDEF;
}
unsigned int shndx = this->symtab_xindex_[symndx];
if (shndx < elfcpp::SHN_LORESERVE || shndx >= object->shnum())
{
object->error(_("extended index for symbol %u out of range: %u"),
symndx, shndx);
return elfcpp::SHN_UNDEF;
}
return shndx;
}
// Class Object.
// Report an error for this object file. This is used by the
// elfcpp::Elf_file interface, and also called by the Object code
// itself.
void
Object::error(const char* format, ...) const
{
va_list args;
va_start(args, format);
char* buf = NULL;
if (vasprintf(&buf, format, args) < 0)
gold_nomem();
va_end(args);
gold_error(_("%s: %s"), this->name().c_str(), buf);
free(buf);
}
// Return a view of the contents of a section.
const unsigned char*
Object::section_contents(unsigned int shndx, section_size_type* plen,
bool cache)
{
Location loc(this->do_section_contents(shndx));
*plen = convert_to_section_size_type(loc.data_size);
if (*plen == 0)
{
static const unsigned char empty[1] = { '\0' };
return empty;
}
return this->get_view(loc.file_offset, *plen, true, cache);
}
// Read the section data into SD. This is code common to Sized_relobj
// and Sized_dynobj, so we put it into Object.
template<int size, bool big_endian>
void
Object::read_section_data(elfcpp::Elf_file<size, big_endian, Object>* elf_file,
Read_symbols_data* sd)
{
const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
// Read the section headers.
const off_t shoff = elf_file->shoff();
const unsigned int shnum = this->shnum();
sd->section_headers = this->get_lasting_view(shoff, shnum * shdr_size,
true, true);
// Read the section names.
const unsigned char* pshdrs = sd->section_headers->data();
const unsigned char* pshdrnames = pshdrs + elf_file->shstrndx() * shdr_size;
typename elfcpp::Shdr<size, big_endian> shdrnames(pshdrnames);
if (shdrnames.get_sh_type() != elfcpp::SHT_STRTAB)
this->error(_("section name section has wrong type: %u"),
static_cast<unsigned int>(shdrnames.get_sh_type()));
sd->section_names_size =
convert_to_section_size_type(shdrnames.get_sh_size());
sd->section_names = this->get_lasting_view(shdrnames.get_sh_offset(),
sd->section_names_size, false,
false);
}
// 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
Object::handle_gnu_warning_section(const char* name, unsigned int shndx,
Symbol_table* symtab)
{
const char warn_prefix[] = ".gnu.warning.";
const int warn_prefix_len = sizeof warn_prefix - 1;
if (strncmp(name, warn_prefix, warn_prefix_len) == 0)
{
// Read the section contents to get the warning text. It would
// be nicer if we only did this if we have to actually issue a
// warning. Unfortunately, warnings are issued as we relocate
// sections. That means that we can not lock the object then,
// as we might try to issue the same warning multiple times
// simultaneously.
section_size_type len;
const unsigned char* contents = this->section_contents(shndx, &len,
false);
if (len == 0)
{
const char* warning = name + warn_prefix_len;
contents = reinterpret_cast<const unsigned char*>(warning);
len = strlen(warning);
}
std::string warning(reinterpret_cast<const char*>(contents), len);
symtab->add_warning(name + warn_prefix_len, this, warning);
return true;
}
return false;
}
// If NAME is the name of the special section which indicates that
// this object was compiled with -fstack-split, mark it accordingly.
bool
Object::handle_split_stack_section(const char* name)
{
if (strcmp(name, ".note.GNU-split-stack") == 0)
{
this->uses_split_stack_ = true;
return true;
}
if (strcmp(name, ".note.GNU-no-split-stack") == 0)
{
this->has_no_split_stack_ = true;
return true;
}
return false;
}
// Class Relobj
// To copy the symbols data read from the file to a local data structure.
// This function is called from do_layout only while doing garbage
// collection.
void
Relobj::copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
unsigned int section_header_size)
{
gc_sd->section_headers_data =
new unsigned char[(section_header_size)];
memcpy(gc_sd->section_headers_data, sd->section_headers->data(),
section_header_size);
gc_sd->section_names_data =
new unsigned char[sd->section_names_size];
memcpy(gc_sd->section_names_data, sd->section_names->data(),
sd->section_names_size);
gc_sd->section_names_size = sd->section_names_size;
if (sd->symbols != NULL)
{
gc_sd->symbols_data =
new unsigned char[sd->symbols_size];
memcpy(gc_sd->symbols_data, sd->symbols->data(),
sd->symbols_size);
}
else
{
gc_sd->symbols_data = NULL;
}
gc_sd->symbols_size = sd->symbols_size;
gc_sd->external_symbols_offset = sd->external_symbols_offset;
if (sd->symbol_names != NULL)
{
gc_sd->symbol_names_data =
new unsigned char[sd->symbol_names_size];
memcpy(gc_sd->symbol_names_data, sd->symbol_names->data(),
sd->symbol_names_size);
}
else
{
gc_sd->symbol_names_data = NULL;
}
gc_sd->symbol_names_size = sd->symbol_names_size;
}
// This function determines if a particular section name must be included
// in the link. This is used during garbage collection to determine the
// roots of the worklist.
bool
Relobj::is_section_name_included(const char* name)
{
if (is_prefix_of(".ctors", name)
|| is_prefix_of(".dtors", name)
|| is_prefix_of(".note", name)
|| is_prefix_of(".init", name)
|| is_prefix_of(".fini", name)
|| is_prefix_of(".gcc_except_table", name)
|| is_prefix_of(".jcr", name)
|| is_prefix_of(".preinit_array", name)
|| (is_prefix_of(".text", name)
&& strstr(name, "personality"))
|| (is_prefix_of(".data", name)
&& strstr(name, "personality"))
|| (is_prefix_of(".gnu.linkonce.d", name) &&
strstr(name, "personality")))
{
return true;
}
return false;
}
// Class Sized_relobj.
template<int size, bool big_endian>
Sized_relobj<size, big_endian>::Sized_relobj(
const std::string& name,
Input_file* input_file,
off_t offset,
const elfcpp::Ehdr<size, big_endian>& ehdr)
: Relobj(name, input_file, offset),
elf_file_(this, ehdr),
symtab_shndx_(-1U),
local_symbol_count_(0),
output_local_symbol_count_(0),
output_local_dynsym_count_(0),
symbols_(),
defined_count_(0),
local_symbol_offset_(0),
local_dynsym_offset_(0),
local_values_(),
local_got_offsets_(),
kept_comdat_sections_(),
has_eh_frame_(false),
discarded_eh_frame_shndx_(-1U)
{
}
template<int size, bool big_endian>
Sized_relobj<size, big_endian>::~Sized_relobj()
{
}
// Set up an object file based on the file header. This sets up the
// section information.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_setup()
{
const unsigned int shnum = this->elf_file_.shnum();
this->set_shnum(shnum);
}
// Find the SHT_SYMTAB section, given the section headers. The ELF
// standard says that maybe in the future there can be more than one
// SHT_SYMTAB section. Until somebody figures out how that could
// work, we assume there is only one.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::find_symtab(const unsigned char* pshdrs)
{
const unsigned int shnum = this->shnum();
this->symtab_shndx_ = 0;
if (shnum > 0)
{
// Look through the sections in reverse order, since gas tends
// to put the symbol table at the end.
const unsigned char* p = pshdrs + shnum * This::shdr_size;
unsigned int i = shnum;
unsigned int xindex_shndx = 0;
unsigned int xindex_link = 0;
while (i > 0)
{
--i;
p -= This::shdr_size;
typename This::Shdr shdr(p);
if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB)
{
this->symtab_shndx_ = i;
if (xindex_shndx > 0 && xindex_link == i)
{
Xindex* xindex =
new Xindex(this->elf_file_.large_shndx_offset());
xindex->read_symtab_xindex<size, big_endian>(this,
xindex_shndx,
pshdrs);
this->set_xindex(xindex);
}
break;
}
// Try to pick up the SHT_SYMTAB_SHNDX section, if there is
// one. This will work if it follows the SHT_SYMTAB
// section.
if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB_SHNDX)
{
xindex_shndx = i;
xindex_link = this->adjust_shndx(shdr.get_sh_link());
}
}
}
}
// Return the Xindex structure to use for object with lots of
// sections.
template<int size, bool big_endian>
Xindex*
Sized_relobj<size, big_endian>::do_initialize_xindex()
{
gold_assert(this->symtab_shndx_ != -1U);
Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
xindex->initialize_symtab_xindex<size, big_endian>(this, this->symtab_shndx_);
return xindex;
}
// Return whether SHDR has the right type and flags to be a GNU
// .eh_frame section.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::check_eh_frame_flags(
const elfcpp::Shdr<size, big_endian>* shdr) const
{
return (shdr->get_sh_type() == elfcpp::SHT_PROGBITS
&& (shdr->get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
}
// Return whether there is a GNU .eh_frame section, given the section
// headers and the section names.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::find_eh_frame(
const unsigned char* pshdrs,
const char* names,
section_size_type names_size) const
{
const unsigned int shnum = this->shnum();
const unsigned char* p = pshdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
{
typename This::Shdr shdr(p);
if (this->check_eh_frame_flags(&shdr))
{
if (shdr.get_sh_name() >= names_size)
{
this->error(_("bad section name offset for section %u: %lu"),
i, static_cast<unsigned long>(shdr.get_sh_name()));
continue;
}
const char* name = names + shdr.get_sh_name();
if (strcmp(name, ".eh_frame") == 0)
return true;
}
}
return false;
}
// Read the sections and symbols from an object file.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
{
this->read_section_data(&this->elf_file_, sd);
const unsigned char* const pshdrs = sd->section_headers->data();
this->find_symtab(pshdrs);
const unsigned char* namesu = sd->section_names->data();
const char* names = reinterpret_cast<const char*>(namesu);
if (memmem(names, sd->section_names_size, ".eh_frame", 10) != NULL)
{
if (this->find_eh_frame(pshdrs, names, sd->section_names_size))
this->has_eh_frame_ = true;
}
sd->symbols = NULL;
sd->symbols_size = 0;
sd->external_symbols_offset = 0;
sd->symbol_names = NULL;
sd->symbol_names_size = 0;
if (this->symtab_shndx_ == 0)
{
// No symbol table. Weird but legal.
return;
}
// Get the symbol table section header.
typename This::Shdr symtabshdr(pshdrs
+ this->symtab_shndx_ * This::shdr_size);
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
// If this object has a .eh_frame section, we need all the symbols.
// Otherwise we only need the external symbols. While it would be
// simpler to just always read all the symbols, I've seen object
// files with well over 2000 local symbols, which for a 64-bit
// object file format is over 5 pages that we don't need to read
// now.
const int sym_size = This::sym_size;
const unsigned int loccount = symtabshdr.get_sh_info();
this->local_symbol_count_ = loccount;
this->local_values_.resize(loccount);
section_offset_type locsize = loccount * sym_size;
off_t dataoff = symtabshdr.get_sh_offset();
section_size_type datasize =
convert_to_section_size_type(symtabshdr.get_sh_size());
off_t extoff = dataoff + locsize;
section_size_type extsize = datasize - locsize;
off_t readoff = this->has_eh_frame_ ? dataoff : extoff;
section_size_type readsize = this->has_eh_frame_ ? datasize : extsize;
if (readsize == 0)
{
// No external symbols. Also weird but also legal.
return;
}
File_view* fvsymtab = this->get_lasting_view(readoff, readsize, true, false);
// Read the section header for the symbol names.
unsigned int strtab_shndx = this->adjust_shndx(symtabshdr.get_sh_link());
if (strtab_shndx >= this->shnum())
{
this->error(_("invalid symbol table name index: %u"), strtab_shndx);
return;
}
typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
{
this->error(_("symbol table name section has wrong type: %u"),
static_cast<unsigned int>(strtabshdr.get_sh_type()));
return;
}
// Read the symbol names.
File_view* fvstrtab = this->get_lasting_view(strtabshdr.get_sh_offset(),
strtabshdr.get_sh_size(),
false, true);
sd->symbols = fvsymtab;
sd->symbols_size = readsize;
sd->external_symbols_offset = this->has_eh_frame_ ? locsize : 0;
sd->symbol_names = fvstrtab;
sd->symbol_names_size =
convert_to_section_size_type(strtabshdr.get_sh_size());
}
// 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 cod 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.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::symbol_section_and_value(unsigned int sym,
Address* value,
bool* is_ordinary)
{
section_size_type symbols_size;
const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
&symbols_size,
false);
const size_t count = symbols_size / This::sym_size;
gold_assert(sym < count);
elfcpp::Sym<size, big_endian> elfsym(symbols + sym * This::sym_size);
*value = elfsym.get_st_value();
return this->adjust_sym_shndx(sym, elfsym.get_st_shndx(), is_ordinary);
}
// Return whether to include a section group in the link. LAYOUT is
// used to keep track of which section groups we have already seen.
// INDEX is the index of the section group and SHDR is the section
// header. If we do not want to include this group, we set bits in
// OMIT for each section which should be discarded.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::include_section_group(
Symbol_table* symtab,
Layout* layout,
unsigned int index,
const char* name,
const unsigned char* shdrs,
const char* section_names,
section_size_type section_names_size,
std::vector<bool>* omit)
{
// Read the section contents.
typename This::Shdr shdr(shdrs + index * This::shdr_size);
const unsigned char* pcon = this->get_view(shdr.get_sh_offset(),
shdr.get_sh_size(), true, false);
const elfcpp::Elf_Word* pword =
reinterpret_cast<const elfcpp::Elf_Word*>(pcon);
// The first word contains flags. We only care about COMDAT section
// groups. Other section groups are always included in the link
// just like ordinary sections.
elfcpp::Elf_Word flags = elfcpp::Swap<32, big_endian>::readval(pword);
// Look up the group signature, which is the name of a symbol. This
// is a lot of effort to go to to read a string. Why didn't they
// just have the group signature point into the string table, rather
// than indirect through a symbol?
// Get the appropriate symbol table header (this will normally be
// the single SHT_SYMTAB section, but in principle it need not be).
const unsigned int link = this->adjust_shndx(shdr.get_sh_link());
typename This::Shdr symshdr(this, this->elf_file_.section_header(link));
// Read the symbol table entry.
unsigned int symndx = shdr.get_sh_info();
if (symndx >= symshdr.get_sh_size() / This::sym_size)
{
this->error(_("section group %u info %u out of range"),
index, symndx);
return false;
}
off_t symoff = symshdr.get_sh_offset() + symndx * This::sym_size;
const unsigned char* psym = this->get_view(symoff, This::sym_size, true,
false);
elfcpp::Sym<size, big_endian> sym(psym);
// Read the symbol table names.
section_size_type symnamelen;
const unsigned char* psymnamesu;
psymnamesu = this->section_contents(this->adjust_shndx(symshdr.get_sh_link()),
&symnamelen, true);
const char* psymnames = reinterpret_cast<const char*>(psymnamesu);
// Get the section group signature.
if (sym.get_st_name() >= symnamelen)
{
this->error(_("symbol %u name offset %u out of range"),
symndx, sym.get_st_name());
return false;
}
std::string signature(psymnames + sym.get_st_name());
// It seems that some versions of gas will create a section group
// associated with a section symbol, and then fail to give a name to
// the section symbol. In such a case, use the name of the section.
if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION)
{
bool is_ordinary;
unsigned int sym_shndx = this->adjust_sym_shndx(symndx,
sym.get_st_shndx(),
&is_ordinary);
if (!is_ordinary || sym_shndx >= this->shnum())
{
this->error(_("symbol %u invalid section index %u"),
symndx, sym_shndx);
return false;
}
typename This::Shdr member_shdr(shdrs + sym_shndx * This::shdr_size);
if (member_shdr.get_sh_name() < section_names_size)
signature = section_names + member_shdr.get_sh_name();
}
// Record this section group in the layout, and see whether we've already
// seen one with the same signature.
bool include_group;
bool is_comdat;
Kept_section* kept_section = NULL;
if ((flags & elfcpp::GRP_COMDAT) == 0)
{
include_group = true;
is_comdat = false;
}
else
{
include_group = layout->find_or_add_kept_section(signature,
this, index, true,
true, &kept_section);
is_comdat = true;
}
size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word);
std::vector<unsigned int> shndxes;
bool relocate_group = include_group && parameters->options().relocatable();
if (relocate_group)
shndxes.reserve(count - 1);
for (size_t i = 1; i < count; ++i)
{
elfcpp::Elf_Word shndx =
this->adjust_shndx(elfcpp::Swap<32, big_endian>::readval(pword + i));
if (relocate_group)
shndxes.push_back(shndx);
if (shndx >= this->shnum())
{
this->error(_("section %u in section group %u out of range"),
shndx, index);
continue;
}
// Check for an earlier section number, since we're going to get
// it wrong--we may have already decided to include the section.
if (shndx < index)
this->error(_("invalid section group %u refers to earlier section %u"),
index, shndx);
// Get the name of the member section.
typename This::Shdr member_shdr(shdrs + shndx * This::shdr_size);
if (member_shdr.get_sh_name() >= section_names_size)
{
// This is an error, but it will be diagnosed eventually
// in do_layout, so we don't need to do anything here but
// ignore it.
continue;
}
std::string mname(section_names + member_shdr.get_sh_name());
if (include_group)
{
if (is_comdat)
kept_section->add_comdat_section(mname, shndx,
member_shdr.get_sh_size());
}
else
{
(*omit)[shndx] = true;
if (is_comdat)
{
Relobj* kept_object = kept_section->object();
if (kept_section->is_comdat())
{
// Find the corresponding kept section, and store
// that info in the discarded section table.
unsigned int kept_shndx;
uint64_t kept_size;
if (kept_section->find_comdat_section(mname, &kept_shndx,
&kept_size))
{
// We don't keep a mapping for this section if
// it has a different size. The mapping is only
// used for relocation processing, and we don't
// want to treat the sections as similar if the
// sizes are different. Checking the section
// size is the approach used by the GNU linker.
if (kept_size == member_shdr.get_sh_size())
this->set_kept_comdat_section(shndx, kept_object,
kept_shndx);
}
}
else
{
// The existing section is a linkonce section. Add
// a mapping if there is exactly one section in the
// group (which is true when COUNT == 2) and if it
// is the same size.
if (count == 2
&& (kept_section->linkonce_size()
== member_shdr.get_sh_size()))
this->set_kept_comdat_section(shndx, kept_object,
kept_section->shndx());
}
}
}
}
if (relocate_group)
layout->layout_group(symtab, this, index, name, signature.c_str(),
shdr, flags, &shndxes);
return include_group;
}
// Whether to include a linkonce section in the link. NAME is the
// name of the section and SHDR is the section header.
// Linkonce sections are a GNU extension implemented in the original
// GNU linker before section groups were defined. The semantics are
// that we only include one linkonce section with a given name. The
// name of a linkonce section is normally .gnu.linkonce.T.SYMNAME,
// where T is the type of section and SYMNAME is the name of a symbol.
// In an attempt to make linkonce sections interact well with section
// groups, we try to identify SYMNAME and use it like a section group
// signature. We want to block section groups with that signature,
// but not other linkonce sections with that signature. We also use
// the full name of the linkonce section as a normal section group
// signature.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::include_linkonce_section(
Layout* layout,
unsigned int index,
const char* name,
const elfcpp::Shdr<size, big_endian>& shdr)
{
typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
// In general the symbol name we want will be the string following
// the last '.'. However, we have to handle the case of
// .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by
// some versions of gcc. So we use a heuristic: if the name starts
// with ".gnu.linkonce.t.", we use everything after that. Otherwise
// we look for the last '.'. We can't always simply skip
// ".gnu.linkonce.X", because we have to deal with cases like
// ".gnu.linkonce.d.rel.ro.local".
const char* const linkonce_t = ".gnu.linkonce.t.";
const char* symname;
if (strncmp(name, linkonce_t, strlen(linkonce_t)) == 0)
symname = name + strlen(linkonce_t);
else
symname = strrchr(name, '.') + 1;
std::string sig1(symname);
std::string sig2(name);
Kept_section* kept1;
Kept_section* kept2;
bool include1 = layout->find_or_add_kept_section(sig1, this, index, false,
false, &kept1);
bool include2 = layout->find_or_add_kept_section(sig2, this, index, false,
true, &kept2);
if (!include2)
{
// We are not including this section because we already saw the
// name of the section as a signature. This normally implies
// that the kept section is another linkonce section. If it is
// the same size, record it as the section which corresponds to
// this one.
if (kept2->object() != NULL
&& !kept2->is_comdat()
&& kept2->linkonce_size() == sh_size)
this->set_kept_comdat_section(index, kept2->object(), kept2->shndx());
}
else if (!include1)
{
// The section is being discarded on the basis of its symbol
// name. This means that the corresponding kept section was
// part of a comdat group, and it will be difficult to identify
// the specific section within that group that corresponds to
// this linkonce section. We'll handle the simple case where
// the group has only one member section. Otherwise, it's not
// worth the effort.
unsigned int kept_shndx;
uint64_t kept_size;
if (kept1->object() != NULL
&& kept1->is_comdat()
&& kept1->find_single_comdat_section(&kept_shndx, &kept_size)
&& kept_size == sh_size)
this->set_kept_comdat_section(index, kept1->object(), kept_shndx);
}
else
{
kept1->set_linkonce_size(sh_size);
kept2->set_linkonce_size(sh_size);
}
return include1 && include2;
}
// Layout an input section.
template<int size, bool big_endian>
inline void
Sized_relobj<size, big_endian>::layout_section(Layout* layout,
unsigned int shndx,
const char* name,
typename This::Shdr& shdr,
unsigned int reloc_shndx,
unsigned int reloc_type)
{
off_t offset;
Output_section* os = layout->layout(this, shndx, name, shdr,
reloc_shndx, reloc_type, &offset);
this->output_sections()[shndx] = os;
if (offset == -1)
this->section_offsets_[shndx] = invalid_address;
else
this->section_offsets_[shndx] = convert_types<Address, off_t>(offset);
// If this section requires special handling, and if there are
// relocs that apply to it, then we must do the special handling
// before we apply the relocs.
if (offset == -1 && reloc_shndx != 0)
this->set_relocs_must_follow_section_writes();
}
// Lay out the input sections. We walk through the sections and check
// whether they should be included in the link. If they should, we
// pass them to the Layout object, which will return an output section
// and an offset.
// During garbage collection (--gc-sections) and identical code folding
// (--icf), this function is called twice. When it is called the first
// time, it is for setting up some sections as roots to a work-list for
// --gc-sections and to do comdat processing. Actual layout happens the
// second time around after all the relevant sections have been determined.
// The first time, is_worklist_ready or is_icf_ready is false. It is then
// set to true after the garbage collection worklist or identical code
// folding is processed and the relevant sections to be kept are
// determined. Then, this function is called again to layout the sections.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
Layout* layout,
Read_symbols_data* sd)
{
const unsigned int shnum = this->shnum();
bool is_gc_pass_one = ((parameters->options().gc_sections()
&& !symtab->gc()->is_worklist_ready())
|| (parameters->options().icf_enabled()
&& !symtab->icf()->is_icf_ready()));
bool is_gc_pass_two = ((parameters->options().gc_sections()
&& symtab->gc()->is_worklist_ready())
|| (parameters->options().icf_enabled()
&& symtab->icf()->is_icf_ready()));
bool is_gc_or_icf = (parameters->options().gc_sections()
|| parameters->options().icf_enabled());
// Both is_gc_pass_one and is_gc_pass_two should not be true.
gold_assert(!(is_gc_pass_one && is_gc_pass_two));
if (shnum == 0)
return;
Symbols_data* gc_sd = NULL;
if (is_gc_pass_one)
{
// During garbage collection save the symbols data to use it when
// re-entering this function.
gc_sd = new Symbols_data;
this->copy_symbols_data(gc_sd, sd, This::shdr_size * shnum);
this->set_symbols_data(gc_sd);
}
else if (is_gc_pass_two)
{
gc_sd = this->get_symbols_data();
}
const unsigned char* section_headers_data = NULL;
section_size_type section_names_size;
const unsigned char* symbols_data = NULL;
section_size_type symbols_size;
section_offset_type external_symbols_offset;
const unsigned char* symbol_names_data = NULL;
section_size_type symbol_names_size;
if (is_gc_or_icf)
{
section_headers_data = gc_sd->section_headers_data;
section_names_size = gc_sd->section_names_size;
symbols_data = gc_sd->symbols_data;
symbols_size = gc_sd->symbols_size;
external_symbols_offset = gc_sd->external_symbols_offset;
symbol_names_data = gc_sd->symbol_names_data;
symbol_names_size = gc_sd->symbol_names_size;
}
else
{
section_headers_data = sd->section_headers->data();
section_names_size = sd->section_names_size;
if (sd->symbols != NULL)
symbols_data = sd->symbols->data();
symbols_size = sd->symbols_size;
external_symbols_offset = sd->external_symbols_offset;
if (sd->symbol_names != NULL)
symbol_names_data = sd->symbol_names->data();
symbol_names_size = sd->symbol_names_size;
}
// Get the section headers.
const unsigned char* shdrs = section_headers_data;
const unsigned char* pshdrs;
// Get the section names.
const unsigned char* pnamesu = (is_gc_or_icf)
? gc_sd->section_names_data
: sd->section_names->data();
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// If any input files have been claimed by plugins, we need to defer
// actual layout until the replacement files have arrived.
const bool should_defer_layout =
(parameters->options().has_plugins()
&& parameters->options().plugins()->should_defer_layout());
unsigned int num_sections_to_defer = 0;
// For each section, record the index of the reloc section if any.
// Use 0 to mean that there is no reloc section, -1U to mean that
// there is more than one.
std::vector<unsigned int> reloc_shndx(shnum, 0);
std::vector<unsigned int> reloc_type(shnum, elfcpp::SHT_NULL);
// Skip the first, dummy, section.
pshdrs = shdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
{
typename This::Shdr shdr(pshdrs);
// Count the number of sections whose layout will be deferred.
if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
++num_sections_to_defer;
unsigned int sh_type = shdr.get_sh_type();
if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA)
{
unsigned int target_shndx = this->adjust_shndx(shdr.get_sh_info());
if (target_shndx == 0 || target_shndx >= shnum)
{
this->error(_("relocation section %u has bad info %u"),
i, target_shndx);
continue;
}
if (reloc_shndx[target_shndx] != 0)
reloc_shndx[target_shndx] = -1U;
else
{
reloc_shndx[target_shndx] = i;
reloc_type[target_shndx] = sh_type;
}
}
}
Output_sections& out_sections(this->output_sections());
std::vector<Address>& out_section_offsets(this->section_offsets_);
if (!is_gc_pass_two)
{
out_sections.resize(shnum);
out_section_offsets.resize(shnum);
}
// If we are only linking for symbols, then there is nothing else to
// do here.
if (this->input_file()->just_symbols())
{
if (!is_gc_pass_two)
{
delete sd->section_headers;
sd->section_headers = NULL;
delete sd->section_names;
sd->section_names = NULL;
}
return;
}
if (num_sections_to_defer > 0)
{
parameters->options().plugins()->add_deferred_layout_object(this);
this->deferred_layout_.reserve(num_sections_to_defer);
}
// Whether we've seen a .note.GNU-stack section.
bool seen_gnu_stack = false;
// The flags of a .note.GNU-stack section.
uint64_t gnu_stack_flags = 0;
// Keep track of which sections to omit.
std::vector<bool> omit(shnum, false);
// Keep track of reloc sections when emitting relocations.
const bool relocatable = parameters->options().relocatable();
const bool emit_relocs = (relocatable
|| parameters->options().emit_relocs());
std::vector<unsigned int> reloc_sections;
// Keep track of .eh_frame sections.
std::vector<unsigned int> eh_frame_sections;
// Skip the first, dummy, section.
pshdrs = shdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
{
typename This::Shdr shdr(pshdrs);
if (shdr.get_sh_name() >= section_names_size)
{
this->error(_("bad section name offset for section %u: %lu"),
i, static_cast<unsigned long>(shdr.get_sh_name()));
return;
}
const char* name = pnames + shdr.get_sh_name();
if (!is_gc_pass_two)
{
if (this->handle_gnu_warning_section(name, i, symtab))
{
if (!relocatable)
omit[i] = true;
}
// The .note.GNU-stack section is special. It gives the
// protection flags that this object file requires for the stack
// in memory.
if (strcmp(name, ".note.GNU-stack") == 0)
{
seen_gnu_stack = true;
gnu_stack_flags |= shdr.get_sh_flags();
omit[i] = true;
}
// The .note.GNU-split-stack section is also special. It
// indicates that the object was compiled with
// -fsplit-stack.
if (this->handle_split_stack_section(name))
{
if (!parameters->options().relocatable()
&& !parameters->options().shared())
omit[i] = true;
}
bool discard = omit[i];
if (!discard)
{
if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
{
if (!this->include_section_group(symtab, layout, i, name,
shdrs, pnames,
section_names_size,
&omit))
discard = true;
}
else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
&& Layout::is_linkonce(name))
{
if (!this->include_linkonce_section(layout, i, name, shdr))
discard = true;
}
}
if (discard)
{
// Do not include this section in the link.
out_sections[i] = NULL;
out_section_offsets[i] = invalid_address;
continue;
}
}
if (is_gc_pass_one && parameters->options().gc_sections())
{
if (is_section_name_included(name)
|| shdr.get_sh_type() == elfcpp::SHT_INIT_ARRAY
|| shdr.get_sh_type() == elfcpp::SHT_FINI_ARRAY)
{
symtab->gc()->worklist().push(Section_id(this, i));
}
}
// When doing a relocatable link we are going to copy input
// reloc sections into the output. We only want to copy the
// ones associated with sections which are not being discarded.
// However, we don't know that yet for all sections. So save
// reloc sections and process them later. Garbage collection is
// not triggered when relocatable code is desired.
if (emit_relocs
&& (shdr.get_sh_type() == elfcpp::SHT_REL
|| shdr.get_sh_type() == elfcpp::SHT_RELA))
{
reloc_sections.push_back(i);
continue;
}
if (relocatable && shdr.get_sh_type() == elfcpp::SHT_GROUP)
continue;
// The .eh_frame section is special. It holds exception frame
// information that we need to read in order to generate the
// exception frame header. We process these after all the other
// sections so that the exception frame reader can reliably
// determine which sections are being discarded, and discard the
// corresponding information.
if (!relocatable
&& strcmp(name, ".eh_frame") == 0
&& this->check_eh_frame_flags(&shdr))
{
if (is_gc_pass_one)
{
out_sections[i] = reinterpret_cast<Output_section*>(1);
out_section_offsets[i] = invalid_address;
}
else
eh_frame_sections.push_back(i);
continue;
}
if (is_gc_pass_two && parameters->options().gc_sections())
{
// This is executed during the second pass of garbage
// collection. do_layout has been called before and some
// sections have been already discarded. Simply ignore
// such sections this time around.
if (out_sections[i] == NULL)
{
gold_assert(out_section_offsets[i] == invalid_address);
continue;
}
if (((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
&& symtab->gc()->is_section_garbage(this, i))
{
if (parameters->options().print_gc_sections())
gold_info(_("%s: removing unused section from '%s'"
" in file '%s'"),
program_name, this->section_name(i).c_str(),
this->name().c_str());
out_sections[i] = NULL;
out_section_offsets[i] = invalid_address;
continue;
}
}
if (is_gc_pass_two && parameters->options().icf_enabled())
{
if (out_sections[i] == NULL)
{
gold_assert(out_section_offsets[i] == invalid_address);
continue;
}
if (((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
&& symtab->icf()->is_section_folded(this, i))
{
if (parameters->options().print_icf_sections())
{
Section_id folded =
symtab->icf()->get_folded_section(this, i);
Relobj* folded_obj =
reinterpret_cast<Relobj*>(folded.first);
gold_info(_("%s: ICF folding section '%s' in file '%s'"
"into '%s' in file '%s'"),
program_name, this->section_name(i).c_str(),
this->name().c_str(),
folded_obj->section_name(folded.second).c_str(),
folded_obj->name().c_str());
}
out_sections[i] = NULL;
out_section_offsets[i] = invalid_address;
continue;
}
}
// Defer layout here if input files are claimed by plugins. When gc
// is turned on this function is called twice. For the second call
// should_defer_layout should be false.
if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
{
gold_assert(!is_gc_pass_two);
this->deferred_layout_.push_back(Deferred_layout(i, name,
pshdrs,
reloc_shndx[i],
reloc_type[i]));
// Put dummy values here; real values will be supplied by
// do_layout_deferred_sections.
out_sections[i] = reinterpret_cast<Output_section*>(2);
out_section_offsets[i] = invalid_address;
continue;
}
// During gc_pass_two if a section that was previously deferred is
// found, do not layout the section as layout_deferred_sections will
// do it later from gold.cc.
if (is_gc_pass_two
&& (out_sections[i] == reinterpret_cast<Output_section*>(2)))
continue;
if (is_gc_pass_one)
{
// This is during garbage collection. The out_sections are
// assigned in the second call to this function.
out_sections[i] = reinterpret_cast<Output_section*>(1);
out_section_offsets[i] = invalid_address;
}
else
{
// When garbage collection is switched on the actual layout
// only happens in the second call.
this->layout_section(layout, i, name, shdr, reloc_shndx[i],
reloc_type[i]);
}
}
if (!is_gc_pass_one)
layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
// When doing a relocatable link handle the reloc sections at the
// end. Garbage collection and Identical Code Folding is not
// turned on for relocatable code.
if (emit_relocs)
this->size_relocatable_relocs();
gold_assert(!(is_gc_or_icf) || reloc_sections.empty());
for (std::vector<unsigned int>::const_iterator p = reloc_sections.begin();
p != reloc_sections.end();
++p)
{
unsigned int i = *p;
const unsigned char* pshdr;
pshdr = section_headers_data + i * This::shdr_size;
typename This::Shdr shdr(pshdr);
unsigned int data_shndx = this->adjust_shndx(shdr.get_sh_info());
if (data_shndx >= shnum)
{
// We already warned about this above.
continue;
}
Output_section* data_section = out_sections[data_shndx];
if (data_section == NULL)
{
out_sections[i] = NULL;
out_section_offsets[i] = invalid_address;
continue;
}
Relocatable_relocs* rr = new Relocatable_relocs();
this->set_relocatable_relocs(i, rr);
Output_section* os = layout->layout_reloc(this, i, shdr, data_section,
rr);
out_sections[i] = os;
out_section_offsets[i] = invalid_address;
}
// Handle the .eh_frame sections at the end.
gold_assert(!is_gc_pass_one || eh_frame_sections.empty());
for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
p != eh_frame_sections.end();
++p)
{
gold_assert(this->has_eh_frame_);
gold_assert(external_symbols_offset != 0);
unsigned int i = *p;
const unsigned char *pshdr;
pshdr = section_headers_data + i * This::shdr_size;
typename This::Shdr shdr(pshdr);
off_t offset;
Output_section* os = layout->layout_eh_frame(this,
symbols_data,
symbols_size,
symbol_names_data,
symbol_names_size,
i, shdr,
reloc_shndx[i],
reloc_type[i],
&offset);
out_sections[i] = os;
if (offset == -1)
{
// An object can contain at most one section holding exception
// frame information.
gold_assert(this->discarded_eh_frame_shndx_ == -1U);
this->discarded_eh_frame_shndx_ = i;
out_section_offsets[i] = invalid_address;
}
else
out_section_offsets[i] = convert_types<Address, off_t>(offset);
// If this section requires special handling, and if there are
// relocs that apply to it, then we must do the special handling
// before we apply the relocs.
if (offset == -1 && reloc_shndx[i] != 0)
this->set_relocs_must_follow_section_writes();
}
if (is_gc_pass_two)
{
delete[] gc_sd->section_headers_data;
delete[] gc_sd->section_names_data;
delete[] gc_sd->symbols_data;
delete[] gc_sd->symbol_names_data;
this->set_symbols_data(NULL);
}
else
{
delete sd->section_headers;
sd->section_headers = NULL;
delete sd->section_names;
sd->section_names = NULL;
}
}
// Layout sections whose layout was deferred while waiting for
// input files from a plugin.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_layout_deferred_sections(Layout* layout)
{
typename std::vector<Deferred_layout>::iterator deferred;
for (deferred = this->deferred_layout_.begin();
deferred != this->deferred_layout_.end();
++deferred)
{
typename This::Shdr shdr(deferred->shdr_data_);
this->layout_section(layout, deferred->shndx_, deferred->name_.c_str(),
shdr, deferred->reloc_shndx_, deferred->reloc_type_);
}
this->deferred_layout_.clear();
}
// Add the symbols to the symbol table.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
Read_symbols_data* sd,
Layout*)
{
if (sd->symbols == NULL)
{
gold_assert(sd->symbol_names == NULL);
return;
}
const int sym_size = This::sym_size;
size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
/ sym_size);
if (symcount * sym_size != sd->symbols_size - sd->external_symbols_offset)
{
this->error(_("size of symbols is not multiple of symbol size"));
return;
}
this->symbols_.resize(symcount);
const char* sym_names =
reinterpret_cast<const char*>(sd->symbol_names->data());
symtab->add_from_relobj(this,
sd->symbols->data() + sd->external_symbols_offset,
symcount, this->local_symbol_count_,
sym_names, sd->symbol_names_size,
&this->symbols_,
&this->defined_count_);
delete sd->symbols;
sd->symbols = NULL;
delete sd->symbol_names;
sd->symbol_names = NULL;
}
// First pass over the local symbols. Here we add their names to
// *POOL and *DYNPOOL, and we store the symbol value in
// THIS->LOCAL_VALUES_. This function is always called from a
// singleton thread. This is followed by a call to
// finalize_local_symbols.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
Stringpool* dynpool)
{
gold_assert(this->symtab_shndx_ != -1U);
if (this->symtab_shndx_ == 0)
{
// This object has no symbols. Weird but legal.
return;
}
// Read the symbol table section header.
const unsigned int symtab_shndx = this->symtab_shndx_;
typename This::Shdr symtabshdr(this,
this->elf_file_.section_header(symtab_shndx));
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
// Read the local symbols.
const int sym_size = This::sym_size;
const unsigned int loccount = this->local_symbol_count_;
gold_assert(loccount == symtabshdr.get_sh_info());
off_t locsize = loccount * sym_size;
const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
locsize, true, true);
// Read the symbol names.
const unsigned int strtab_shndx =
this->adjust_shndx(symtabshdr.get_sh_link());
section_size_type strtab_size;
const unsigned char* pnamesu = this->section_contents(strtab_shndx,
&strtab_size,
true);
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// Loop over the local symbols.
const Output_sections& out_sections(this->output_sections());
unsigned int shnum = this->shnum();
unsigned int count = 0;
unsigned int dyncount = 0;
// Skip the first, dummy, symbol.
psyms += sym_size;
bool discard_locals = parameters->options().discard_locals();
for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
{
elfcpp::Sym<size, big_endian> sym(psyms);
Symbol_value<size>& lv(this->local_values_[i]);
bool is_ordinary;
unsigned int shndx = this->adjust_sym_shndx(i, sym.get_st_shndx(),
&is_ordinary);
lv.set_input_shndx(shndx, is_ordinary);
if (sym.get_st_type() == elfcpp::STT_SECTION)
lv.set_is_section_symbol();
else if (sym.get_st_type() == elfcpp::STT_TLS)
lv.set_is_tls_symbol();
// Save the input symbol value for use in do_finalize_local_symbols().
lv.set_input_value(sym.get_st_value());
// Decide whether this symbol should go into the output file.
if ((shndx < shnum && out_sections[shndx] == NULL)
|| (shndx == this->discarded_eh_frame_shndx_))
{
lv.set_no_output_symtab_entry();
gold_assert(!lv.needs_output_dynsym_entry());
continue;
}
if (sym.get_st_type() == elfcpp::STT_SECTION)
{
lv.set_no_output_symtab_entry();
gold_assert(!lv.needs_output_dynsym_entry());
continue;
}
if (sym.get_st_name() >= strtab_size)
{
this->error(_("local symbol %u section name out of range: %u >= %u"),
i, sym.get_st_name(),
static_cast<unsigned int>(strtab_size));
lv.set_no_output_symtab_entry();
continue;
}
// If --discard-locals option is used, discard all temporary local
// symbols. These symbols start with system-specific local label
// prefixes, typically .L for ELF system. We want to be compatible
// with GNU ld so here we essentially use the same check in
// bfd_is_local_label(). The code is different because we already
// know that:
//
// - the symbol is local and thus cannot have global or weak binding.
// - the symbol is not a section symbol.
// - the symbol has a name.
//
// We do not discard a symbol if it needs a dynamic symbol entry.
const char* name = pnames + sym.get_st_name();
if (discard_locals
&& sym.get_st_type() != elfcpp::STT_FILE
&& !lv.needs_output_dynsym_entry()
&& parameters->target().is_local_label_name(name))
{
lv.set_no_output_symtab_entry();
continue;
}
// Discard the local symbol if -retain_symbols_file is specified
// and the local symbol is not in that file.
if (!parameters->options().should_retain_symbol(name))
{
lv.set_no_output_symtab_entry();
continue;
}
// Add the symbol to the symbol table string pool.
pool->add(name, true, NULL);
++count;
// If needed, add the symbol to the dynamic symbol table string pool.
if (lv.needs_output_dynsym_entry())
{
dynpool->add(name, true, NULL);
++dyncount;
}
}
this->output_local_symbol_count_ = count;
this->output_local_dynsym_count_ = dyncount;
}
// Finalize the local symbols. Here we set the final value in
// THIS->LOCAL_VALUES_ and set their output symbol table indexes.
// This function is always called from a singleton thread. The actual
// output of the local symbols will occur in a separate task.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::do_finalize_local_symbols(unsigned int index,
off_t off,
Symbol_table* symtab)
{
gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
const unsigned int loccount = this->local_symbol_count_;
this->local_symbol_offset_ = off;
const bool relocatable = parameters->options().relocatable();
const Output_sections& out_sections(this->output_sections());
const std::vector<Address>& out_offsets(this->section_offsets_);
unsigned int shnum = this->shnum();
for (unsigned int i = 1; i < loccount; ++i)
{
Symbol_value<size>& lv(this->local_values_[i]);
bool is_ordinary;
unsigned int shndx = lv.input_shndx(&is_ordinary);
// Set the output symbol value.
if (!is_ordinary)
{
if (shndx == elfcpp::SHN_ABS || Symbol::is_common_shndx(shndx))
lv.set_output_value(lv.input_value());
else
{
this->error(_("unknown section index %u for local symbol %u"),
shndx, i);
lv.set_output_value(0);
}
}
else
{
if (shndx >= shnum)
{
this->error(_("local symbol %u section index %u out of range"),
i, shndx);
shndx = 0;
}
Output_section* os = out_sections[shndx];
Address secoffset = out_offsets[shndx];
if (symtab->is_section_folded(this, shndx))
{
gold_assert (os == NULL && secoffset == invalid_address);
// Get the os of the section it is folded onto.
Section_id folded = symtab->icf()->get_folded_section(this,
shndx);
gold_assert(folded.first != NULL);
Sized_relobj<size, big_endian>* folded_obj = reinterpret_cast
<Sized_relobj<size, big_endian>*>(folded.first);
os = folded_obj->output_section(folded.second);
gold_assert(os != NULL);
secoffset = folded_obj->get_output_section_offset(folded.second);
gold_assert(secoffset != invalid_address);
}
if (os == NULL)
{
// This local symbol belongs to a section we are discarding.
// In some cases when applying relocations later, we will
// attempt to match it to the corresponding kept section,
// so we leave the input value unchanged here.
continue;
}
else if (secoffset == invalid_address)
{
uint64_t start;
// This is a SHF_MERGE section or one which otherwise
// requires special handling.
if (shndx == this->discarded_eh_frame_shndx_)
{
// This local symbol belongs to a discarded .eh_frame
// section. Just treat it like the case in which
// os == NULL above.
gold_assert(this->has_eh_frame_);
continue;
}
else if (!lv.is_section_symbol())
{
// This is not a section symbol. We can determine
// the final value now.
lv.set_output_value(os->output_address(this, shndx,
lv.input_value()));
}
else if (!os->find_starting_output_address(this, shndx, &start))
{
// This is a section symbol, but apparently not one in a
// merged section. First check to see if this is a relaxed
// input section. If so, use its address. Otherwise just
// use the start of the output section. This happens with
// relocatable links when the input object has section
// symbols for arbitrary non-merge sections.
const Output_section_data* posd =
os->find_relaxed_input_section(this, shndx);
if (posd != NULL)
lv.set_output_value(posd->address());
else
lv.set_output_value(os->address());
}
else
{
// We have to consider the addend to determine the
// value to use in a relocation. START is the start
// of this input section.
Merged_symbol_value<size>* msv =
new Merged_symbol_value<size>(lv.input_value(), start);
lv.set_merged_symbol_value(msv);
}
}
else if (lv.is_tls_symbol())
lv.set_output_value(os->tls_offset()
+ secoffset
+ lv.input_value());
else
lv.set_output_value((relocatable ? 0 : os->address())
+ secoffset
+ lv.input_value());
}
if (lv.needs_output_symtab_entry())
{
lv.set_output_symtab_index(index);
++index;
}
}
return index;
}
// Set the output dynamic symbol table indexes for the local variables.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::do_set_local_dynsym_indexes(unsigned int index)
{
const unsigned int loccount = this->local_symbol_count_;
for (unsigned int i = 1; i < loccount; ++i)
{
Symbol_value<size>& lv(this->local_values_[i]);
if (lv.needs_output_dynsym_entry())
{
lv.set_output_dynsym_index(index);
++index;
}
}
return index;
}
// Set the offset where local dynamic symbol information will be stored.
// Returns the count of local symbols contributed to the symbol table by
// this object.
template<int size, bool big_endian>
unsigned int
Sized_relobj<size, big_endian>::do_set_local_dynsym_offset(off_t off)
{
gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
this->local_dynsym_offset_ = off;
return this->output_local_dynsym_count_;
}
// If Symbols_data is not NULL get the section flags from here otherwise
// get it from the file.
template<int size, bool big_endian>
uint64_t
Sized_relobj<size, big_endian>::do_section_flags(unsigned int shndx)
{
Symbols_data* sd = this->get_symbols_data();
if (sd != NULL)
{
const unsigned char* pshdrs = sd->section_headers_data
+ This::shdr_size * shndx;
typename This::Shdr shdr(pshdrs);
return shdr.get_sh_flags();
}
// If sd is NULL, read the section header from the file.
return this->elf_file_.section_flags(shndx);
}
// Get the section's ent size from Symbols_data. Called by get_section_contents
// in icf.cc
template<int size, bool big_endian>
uint64_t
Sized_relobj<size, big_endian>::do_section_entsize(unsigned int shndx)
{
Symbols_data* sd = this->get_symbols_data();
gold_assert (sd != NULL);
const unsigned char* pshdrs = sd->section_headers_data
+ This::shdr_size * shndx;
typename This::Shdr shdr(pshdrs);
return shdr.get_sh_entsize();
}
// Write out the local symbols.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::write_local_symbols(
Output_file* of,
const Stringpool* sympool,
const Stringpool* dynpool,
Output_symtab_xindex* symtab_xindex,
Output_symtab_xindex* dynsym_xindex)
{
const bool strip_all = parameters->options().strip_all();
if (strip_all)
{
if (this->output_local_dynsym_count_ == 0)
return;
this->output_local_symbol_count_ = 0;
}
gold_assert(this->symtab_shndx_ != -1U);
if (this->symtab_shndx_ == 0)
{
// This object has no symbols. Weird but legal.
return;
}
// Read the symbol table section header.
const unsigned int symtab_shndx = this->symtab_shndx_;
typename This::Shdr symtabshdr(this,
this->elf_file_.section_header(symtab_shndx));
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
const unsigned int loccount = this->local_symbol_count_;
gold_assert(loccount == symtabshdr.get_sh_info());
// Read the local symbols.
const int sym_size = This::sym_size;
off_t locsize = loccount * sym_size;
const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
locsize, true, false);
// Read the symbol names.
const unsigned int strtab_shndx =
this->adjust_shndx(symtabshdr.get_sh_link());
section_size_type strtab_size;
const unsigned char* pnamesu = this->section_contents(strtab_shndx,
&strtab_size,
false);
const char* pnames = reinterpret_cast<const char*>(pnamesu);
// Get views into the output file for the portions of the symbol table
// and the dynamic symbol table that we will be writing.
off_t output_size = this->output_local_symbol_count_ * sym_size;
unsigned char* oview = NULL;
if (output_size > 0)
oview = of->get_output_view(this->local_symbol_offset_, output_size);
off_t dyn_output_size = this->output_local_dynsym_count_ * sym_size;
unsigned char* dyn_oview = NULL;
if (dyn_output_size > 0)
dyn_oview = of->get_output_view(this->local_dynsym_offset_,
dyn_output_size);
const Output_sections out_sections(this->output_sections());
gold_assert(this->local_values_.size() == loccount);
unsigned char* ov = oview;
unsigned char* dyn_ov = dyn_oview;
psyms += sym_size;
for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
{
elfcpp::Sym<size, big_endian> isym(psyms);
Symbol_value<size>& lv(this->local_values_[i]);
bool is_ordinary;
unsigned int st_shndx = this->adjust_sym_shndx(i, isym.get_st_shndx(),
&is_ordinary);
if (is_ordinary)
{
gold_assert(st_shndx < out_sections.size());
if (out_sections[st_shndx] == NULL)
continue;
st_shndx = out_sections[st_shndx]->out_shndx();
if (st_shndx >= elfcpp::SHN_LORESERVE)
{
if (lv.needs_output_symtab_entry() && !strip_all)
symtab_xindex->add(lv.output_symtab_index(), st_shndx);
if (lv.needs_output_dynsym_entry())
dynsym_xindex->add(lv.output_dynsym_index(), st_shndx);
st_shndx = elfcpp::SHN_XINDEX;
}
}
// Write the symbol to the output symbol table.
if (!strip_all && lv.needs_output_symtab_entry())
{
elfcpp::Sym_write<size, big_endian> osym(ov);
gold_assert(isym.get_st_name() < strtab_size);
const char* name = pnames + isym.get_st_name();
osym.put_st_name(sympool->get_offset(name));
osym.put_st_value(this->local_values_[i].value(this, 0));
osym.put_st_size(isym.get_st_size());
osym.put_st_info(isym.get_st_info());
osym.put_st_other(isym.get_st_other());
osym.put_st_shndx(st_shndx);
ov += sym_size;
}
// Write the symbol to the output dynamic symbol table.
if (lv.needs_output_dynsym_entry())
{
gold_assert(dyn_ov < dyn_oview + dyn_output_size);
elfcpp::Sym_write<size, big_endian> osym(dyn_ov);
gold_assert(isym.get_st_name() < strtab_size);
const char* name = pnames + isym.get_st_name();
osym.put_st_name(dynpool->get_offset(name));
osym.put_st_value(this->local_values_[i].value(this, 0));
osym.put_st_size(isym.get_st_size());
osym.put_st_info(isym.get_st_info());
osym.put_st_other(isym.get_st_other());
osym.put_st_shndx(st_shndx);
dyn_ov += sym_size;
}
}
if (output_size > 0)
{
gold_assert(ov - oview == output_size);
of->write_output_view(this->local_symbol_offset_, output_size, oview);
}
if (dyn_output_size > 0)
{
gold_assert(dyn_ov - dyn_oview == dyn_output_size);
of->write_output_view(this->local_dynsym_offset_, dyn_output_size,
dyn_oview);
}
}
// Set *INFO to symbolic information about the offset OFFSET in the
// section SHNDX. Return true if we found something, false if we
// found nothing.
template<int size, bool big_endian>
bool
Sized_relobj<size, big_endian>::get_symbol_location_info(
unsigned int shndx,
off_t offset,
Symbol_location_info* info)
{
if (this->symtab_shndx_ == 0)
return false;
section_size_type symbols_size;
const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
&symbols_size,
false);
unsigned int symbol_names_shndx =
this->adjust_shndx(this->section_link(this->symtab_shndx_));
section_size_type names_size;
const unsigned char* symbol_names_u =
this->section_contents(symbol_names_shndx, &names_size, false);
const char* symbol_names = reinterpret_cast<const char*>(symbol_names_u);
const int sym_size = This::sym_size;
const size_t count = symbols_size / sym_size;
const unsigned char* p = symbols;
for (size_t i = 0; i < count; ++i, p += sym_size)
{
elfcpp::Sym<size, big_endian> sym(p);
if (sym.get_st_type() == elfcpp::STT_FILE)
{
if (sym.get_st_name() >= names_size)
info->source_file = "(invalid)";
else
info->source_file = symbol_names + sym.get_st_name();
continue;
}
bool is_ordinary;
unsigned int st_shndx = this->adjust_sym_shndx(i, sym.get_st_shndx(),
&is_ordinary);
if (is_ordinary
&& st_shndx == shndx
&& static_cast<off_t>(sym.get_st_value()) <= offset
&& (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
> offset))
{
if (sym.get_st_name() > names_size)
info->enclosing_symbol_name = "(invalid)";
else
{
info->enclosing_symbol_name = symbol_names + sym.get_st_name();
if (parameters->options().do_demangle())
{
char* demangled_name = cplus_demangle(
info->enclosing_symbol_name.c_str(),
DMGL_ANSI | DMGL_PARAMS);
if (demangled_name != NULL)
{
info->enclosing_symbol_name.assign(demangled_name);
free(demangled_name);
}
}
}
return true;
}
}
return false;
}
// 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. If we can't find the kept section, return 0.
template<int size, bool big_endian>
typename Sized_relobj<size, big_endian>::Address
Sized_relobj<size, big_endian>::map_to_kept_section(
unsigned int shndx,
bool* found) const
{
Relobj* kept_object;
unsigned int kept_shndx;
if (this->get_kept_comdat_section(shndx, &kept_object, &kept_shndx))
{
Sized_relobj<size, big_endian>* kept_relobj =
static_cast<Sized_relobj<size, big_endian>*>(kept_object);
Output_section* os = kept_relobj->output_section(kept_shndx);
Address offset = kept_relobj->get_output_section_offset(kept_shndx);
if (os != NULL && offset != invalid_address)
{
*found = true;
return os->address() + offset;
}
}
*found = false;
return 0;
}
// Get symbol counts.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_get_global_symbol_counts(
const Symbol_table*,
size_t* defined,
size_t* used) const
{
*defined = this->defined_count_;
size_t count = 0;
for (Symbols::const_iterator p = this->symbols_.begin();
p != this->symbols_.end();
++p)
if (*p != NULL
&& (*p)->source() == Symbol::FROM_OBJECT
&& (*p)->object() == this
&& (*p)->is_defined())
++count;
*used = count;
}
// Input_objects methods.
// Add a regular relocatable object to the list. Return false if this
// object should be ignored.
bool
Input_objects::add_object(Object* obj)
{
// Print the filename if the -t/--trace option is selected.
if (parameters->options().trace())
gold_info("%s", obj->name().c_str());
if (!obj->is_dynamic())
this->relobj_list_.push_back(static_cast<Relobj*>(obj));
else
{
// See if this is a duplicate SONAME.
Dynobj* dynobj = static_cast<Dynobj*>(obj);
const char* soname = dynobj->soname();
std::pair<Unordered_set<std::string>::iterator, bool> ins =
this->sonames_.insert(soname);
if (!ins.second)
{
// We have already seen a dynamic object with this soname.
return false;
}
this->dynobj_list_.push_back(dynobj);
}
// Add this object to the cross-referencer if requested.
if (parameters->options().user_set_print_symbol_counts())
{
if (this->cref_ == NULL)
this->cref_ = new Cref();
this->cref_->add_object(obj);
}
return true;
}
// For each dynamic object, record whether we've seen all of its
// explicit dependencies.
void
Input_objects::check_dynamic_dependencies() const
{
for (Dynobj_list::const_iterator p = this->dynobj_list_.begin();
p != this->dynobj_list_.end();
++p)
{
const Dynobj::Needed& needed((*p)->needed());
bool found_all = true;
for (Dynobj::Needed::const_iterator pneeded = needed.begin();
pneeded != needed.end();
++pneeded)
{
if (this->sonames_.find(*pneeded) == this->sonames_.end())
{
found_all = false;
break;
}
}
(*p)->set_has_unknown_needed_entries(!found_all);
}
}
// Start processing an archive.
void
Input_objects::archive_start(Archive* archive)
{
if (parameters->options().user_set_print_symbol_counts())
{
if (this->cref_ == NULL)
this->cref_ = new Cref();
this->cref_->add_archive_start(archive);
}
}
// Stop processing an archive.
void
Input_objects::archive_stop(Archive* archive)
{
if (parameters->options().user_set_print_symbol_counts())
this->cref_->add_archive_stop(archive);
}
// Print symbol counts
void
Input_objects::print_symbol_counts(const Symbol_table* symtab) const
{
if (parameters->options().user_set_print_symbol_counts()
&& this->cref_ != NULL)
this->cref_->print_symbol_counts(symtab);
}
// Relocate_info methods.
// Return a string describing the location of a relocation. This is
// only used in error messages.
template<int size, bool big_endian>
std::string
Relocate_info<size, big_endian>::location(size_t, off_t offset) const
{
// See if we can get line-number information from debugging sections.
std::string filename;
std::string file_and_lineno; // Better than filename-only, if available.
Sized_dwarf_line_info<size, big_endian> line_info(this->object);
// This will be "" if we failed to parse the debug info for any reason.
file_and_lineno = line_info.addr2line(this->data_shndx, offset);
std::string ret(this->object->name());
ret += ':';
Symbol_location_info info;
if (this->object->get_symbol_location_info(this->data_shndx, offset, &info))
{
ret += " in function ";
ret += info.enclosing_symbol_name;
ret += ":";
filename = info.source_file;
}
if (!file_and_lineno.empty())
ret += file_and_lineno;
else
{
if (!filename.empty())
ret += filename;
ret += "(";
ret += this->object->section_name(this->data_shndx);
char buf[100];
// Offsets into sections have to be positive.
snprintf(buf, sizeof(buf), "+0x%lx", static_cast<long>(offset));
ret += buf;
ret += ")";
}
return ret;
}
} // End namespace gold.
namespace
{
using namespace gold;
// Read an ELF file with the header and return the appropriate
// instance of Object.
template<int size, bool big_endian>
Object*
make_elf_sized_object(const std::string& name, Input_file* input_file,
off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr,
bool* punconfigured)
{
Target* target = select_target(ehdr.get_e_machine(), size, big_endian,
ehdr.get_e_ident()[elfcpp::EI_OSABI],
ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
if (target == NULL)
gold_fatal(_("%s: unsupported ELF machine number %d"),
name.c_str(), ehdr.get_e_machine());
if (!parameters->target_valid())
set_parameters_target(target);
else if (target != &parameters->target())
{
if (punconfigured != NULL)
*punconfigured = true;
else
gold_error(_("%s: incompatible target"), name.c_str());
return NULL;
}
return target->make_elf_object<size, big_endian>(name, input_file, offset,
ehdr);
}
} // End anonymous namespace.
namespace gold
{
// Return whether INPUT_FILE is an ELF object.
bool
is_elf_object(Input_file* input_file, off_t offset,
const unsigned char** start, int *read_size)
{
off_t filesize = input_file->file().filesize();
int want = elfcpp::Elf_recognizer::max_header_size;
if (filesize - offset < want)
want = filesize - offset;
const unsigned char* p = input_file->file().get_view(offset, 0, want,
true, false);
*start = p;
*read_size = want;
return elfcpp::Elf_recognizer::is_elf_file(p, want);
}
// Read an ELF file and return the appropriate instance of Object.
Object*
make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
const unsigned char* p, section_offset_type bytes,
bool* punconfigured)
{
if (punconfigured != NULL)
*punconfigured = false;
std::string error;
bool big_endian = false;
int size = 0;
if (!elfcpp::Elf_recognizer::is_valid_header(p, bytes, &size,
&big_endian, &error))
{
gold_error(_("%s: %s"), name.c_str(), error.c_str());
return NULL;
}
if (size == 32)
{
if (big_endian)
{
#ifdef HAVE_TARGET_32_BIG
elfcpp::Ehdr<32, true> ehdr(p);
return make_elf_sized_object<32, true>(name, input_file,
offset, ehdr, punconfigured);
#else
if (punconfigured != NULL)
*punconfigured = true;
else
gold_error(_("%s: not configured to support "
"32-bit big-endian object"),
name.c_str());
return NULL;
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
elfcpp::Ehdr<32, false> ehdr(p);
return make_elf_sized_object<32, false>(name, input_file,
offset, ehdr, punconfigured);
#else
if (punconfigured != NULL)
*punconfigured = true;
else
gold_error(_("%s: not configured to support "
"32-bit little-endian object"),
name.c_str());
return NULL;
#endif
}
}
else if (size == 64)
{
if (big_endian)
{
#ifdef HAVE_TARGET_64_BIG
elfcpp::Ehdr<64, true> ehdr(p);
return make_elf_sized_object<64, true>(name, input_file,
offset, ehdr, punconfigured);
#else
if (punconfigured != NULL)
*punconfigured = true;
else
gold_error(_("%s: not configured to support "
"64-bit big-endian object"),
name.c_str());
return NULL;
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
elfcpp::Ehdr<64, false> ehdr(p);
return make_elf_sized_object<64, false>(name, input_file,
offset, ehdr, punconfigured);
#else
if (punconfigured != NULL)
*punconfigured = true;
else
gold_error(_("%s: not configured to support "
"64-bit little-endian object"),
name.c_str());
return NULL;
#endif
}
}
else
gold_unreachable();
}
// Instantiate the templates we need.
#ifdef HAVE_TARGET_32_LITTLE
template
void
Object::read_section_data<32, false>(elfcpp::Elf_file<32, false, Object>*,
Read_symbols_data*);
#endif
#ifdef HAVE_TARGET_32_BIG
template
void
Object::read_section_data<32, true>(elfcpp::Elf_file<32, true, Object>*,
Read_symbols_data*);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
void
Object::read_section_data<64, false>(elfcpp::Elf_file<64, false, Object>*,
Read_symbols_data*);
#endif
#ifdef HAVE_TARGET_64_BIG
template
void
Object::read_section_data<64, true>(elfcpp::Elf_file<64, true, Object>*,
Read_symbols_data*);
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Sized_relobj<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Sized_relobj<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Sized_relobj<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Sized_relobj<64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
struct Relocate_info<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
struct Relocate_info<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
struct Relocate_info<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
struct Relocate_info<64, true>;
#endif
} // End namespace gold.
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