binutils-gdb/gold/reloc.cc

810 lines
21 KiB
C++

// reloc.cc -- relocate input files for gold.
// Copyright 2006, 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include "gold.h"
#include "workqueue.h"
#include "object.h"
#include "symtab.h"
#include "output.h"
#include "reloc.h"
namespace gold
{
// Read_relocs methods.
// These tasks just read the relocation information from the file.
// After reading it, the start another task to process the
// information. These tasks requires access to the file.
Task::Is_runnable_type
Read_relocs::is_runnable(Workqueue*)
{
return this->object_->is_locked() ? IS_LOCKED : IS_RUNNABLE;
}
// Lock the file.
Task_locker*
Read_relocs::locks(Workqueue*)
{
return new Task_locker_obj<Object>(*this->object_);
}
// Read the relocations and then start a Scan_relocs_task.
void
Read_relocs::run(Workqueue* workqueue)
{
Read_relocs_data *rd = new Read_relocs_data;
this->object_->read_relocs(rd);
workqueue->queue_front(new Scan_relocs(this->options_, this->symtab_,
this->layout_, this->object_, rd,
this->symtab_lock_, this->blocker_));
}
// Scan_relocs methods.
// These tasks scan the relocations read by Read_relocs and mark up
// the symbol table to indicate which relocations are required. We
// use a lock on the symbol table to keep them from interfering with
// each other.
Task::Is_runnable_type
Scan_relocs::is_runnable(Workqueue*)
{
if (!this->symtab_lock_->is_writable() || this->object_->is_locked())
return IS_LOCKED;
return IS_RUNNABLE;
}
// Return the locks we hold: one on the file, one on the symbol table
// and one blocker.
class Scan_relocs::Scan_relocs_locker : public Task_locker
{
public:
Scan_relocs_locker(Object* object, Task_token& symtab_lock, Task* task,
Task_token& blocker, Workqueue* workqueue)
: objlock_(*object), symtab_locker_(symtab_lock, task),
blocker_(blocker, workqueue)
{ }
private:
Task_locker_obj<Object> objlock_;
Task_locker_write symtab_locker_;
Task_locker_block blocker_;
};
Task_locker*
Scan_relocs::locks(Workqueue* workqueue)
{
return new Scan_relocs_locker(this->object_, *this->symtab_lock_, this,
*this->blocker_, workqueue);
}
// Scan the relocs.
void
Scan_relocs::run(Workqueue*)
{
this->object_->scan_relocs(this->options_, this->symtab_, this->layout_,
this->rd_);
delete this->rd_;
this->rd_ = NULL;
}
// Relocate_task methods.
// These tasks are always runnable.
Task::Is_runnable_type
Relocate_task::is_runnable(Workqueue*)
{
return IS_RUNNABLE;
}
// We want to lock the file while we run. We want to unblock
// FINAL_BLOCKER when we are done.
class Relocate_task::Relocate_locker : public Task_locker
{
public:
Relocate_locker(Task_token& token, Workqueue* workqueue,
Object* object)
: blocker_(token, workqueue), objlock_(*object)
{ }
private:
Task_locker_block blocker_;
Task_locker_obj<Object> objlock_;
};
Task_locker*
Relocate_task::locks(Workqueue* workqueue)
{
return new Relocate_locker(*this->final_blocker_, workqueue,
this->object_);
}
// Run the task.
void
Relocate_task::run(Workqueue*)
{
this->object_->relocate(this->options_, this->symtab_, this->layout_,
this->of_);
}
// Read the relocs and local symbols from the object file and store
// the information in RD.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
{
rd->relocs.clear();
unsigned int shnum = this->shnum();
if (shnum == 0)
return;
rd->relocs.reserve(shnum / 2);
const unsigned char *pshdrs = this->get_view(this->elf_file_.shoff(),
shnum * This::shdr_size,
true);
// Skip the first, dummy, section.
const unsigned char *ps = pshdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, ps += This::shdr_size)
{
typename This::Shdr shdr(ps);
unsigned int sh_type = shdr.get_sh_type();
if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
continue;
unsigned int shndx = shdr.get_sh_info();
if (shndx >= shnum)
{
fprintf(stderr, _("%s: %s: relocation section %u has bad info %u\n"),
program_name, this->name().c_str(), i, shndx);
gold_exit(false);
}
if (!this->is_section_included(shndx))
continue;
// We are scanning relocations in order to fill out the GOT and
// PLT sections. Relocations for sections which are not
// allocated (typically debugging sections) should not add new
// GOT and PLT entries. So we skip them.
typename This::Shdr secshdr(pshdrs + shndx * This::shdr_size);
if ((secshdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
continue;
if (shdr.get_sh_link() != this->symtab_shndx_)
{
fprintf(stderr,
_("%s: %s: relocation section %u uses unexpected "
"symbol table %u\n"),
program_name, this->name().c_str(), i, shdr.get_sh_link());
gold_exit(false);
}
off_t sh_size = shdr.get_sh_size();
unsigned int reloc_size;
if (sh_type == elfcpp::SHT_REL)
reloc_size = elfcpp::Elf_sizes<size>::rel_size;
else
reloc_size = elfcpp::Elf_sizes<size>::rela_size;
if (reloc_size != shdr.get_sh_entsize())
{
fprintf(stderr,
_("%s: %s: unexpected entsize for reloc section %u: "
"%lu != %u"),
program_name, this->name().c_str(), i,
static_cast<unsigned long>(shdr.get_sh_entsize()),
reloc_size);
gold_exit(false);
}
size_t reloc_count = sh_size / reloc_size;
if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
{
fprintf(stderr, _("%s: %s: reloc section %u size %lu uneven"),
program_name, this->name().c_str(), i,
static_cast<unsigned long>(sh_size));
gold_exit(false);
}
rd->relocs.push_back(Section_relocs());
Section_relocs& sr(rd->relocs.back());
sr.reloc_shndx = i;
sr.data_shndx = shndx;
sr.contents = this->get_lasting_view(shdr.get_sh_offset(), sh_size,
true);
sr.sh_type = sh_type;
sr.reloc_count = reloc_count;
}
// Read the local symbols.
gold_assert(this->symtab_shndx_ != -1U);
if (this->symtab_shndx_ == 0 || this->local_symbol_count_ == 0)
rd->local_symbols = NULL;
else
{
typename This::Shdr symtabshdr(pshdrs
+ this->symtab_shndx_ * This::shdr_size);
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
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;
rd->local_symbols = this->get_lasting_view(symtabshdr.get_sh_offset(),
locsize, true);
}
}
// Scan the relocs and adjust the symbol table. This looks for
// relocations which require GOT/PLT/COPY relocations.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
Read_relocs_data* rd)
{
Sized_target<size, big_endian>* target = this->sized_target();
const unsigned char* local_symbols;
if (rd->local_symbols == NULL)
local_symbols = NULL;
else
local_symbols = rd->local_symbols->data();
for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
p != rd->relocs.end();
++p)
{
target->scan_relocs(options, symtab, layout, this, p->data_shndx,
p->sh_type, p->contents->data(), p->reloc_count,
this->local_symbol_count_,
local_symbols,
this->symbols_);
delete p->contents;
p->contents = NULL;
}
if (rd->local_symbols != NULL)
{
delete rd->local_symbols;
rd->local_symbols = NULL;
}
}
// Relocate the input sections and write out the local symbols.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::do_relocate(const General_options& options,
const Symbol_table* symtab,
const Layout* layout,
Output_file* of)
{
unsigned int shnum = this->shnum();
// Read the section headers.
const unsigned char* pshdrs = this->get_view(this->elf_file_.shoff(),
shnum * This::shdr_size,
true);
Views views;
views.resize(shnum);
// Make two passes over the sections. The first one copies the
// section data to the output file. The second one applies
// relocations.
this->write_sections(pshdrs, of, &views);
// Apply relocations.
this->relocate_sections(options, symtab, layout, pshdrs, &views);
// Write out the accumulated views.
for (unsigned int i = 1; i < shnum; ++i)
{
if (views[i].view != NULL)
of->write_output_view(views[i].offset, views[i].view_size,
views[i].view);
}
// Write out the local symbols.
this->write_local_symbols(of, layout->sympool());
}
// Write section data to the output file. PSHDRS points to the
// section headers. Record the views in *PVIEWS for use when
// relocating.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::write_sections(const unsigned char* pshdrs,
Output_file* of,
Views* pviews)
{
unsigned int shnum = this->shnum();
std::vector<Map_to_output>& map_sections(this->map_to_output());
const unsigned char* p = pshdrs + This::shdr_size;
for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
{
View_size* pvs = &(*pviews)[i];
pvs->view = NULL;
if (map_sections[i].offset == -1)
continue;
const Output_section* os = map_sections[i].output_section;
if (os == NULL)
continue;
typename This::Shdr shdr(p);
if (shdr.get_sh_type() == elfcpp::SHT_NOBITS)
continue;
off_t start = os->offset() + map_sections[i].offset;
off_t sh_size = shdr.get_sh_size();
if (sh_size == 0)
continue;
gold_assert(map_sections[i].offset >= 0
&& map_sections[i].offset + sh_size <= os->data_size());
unsigned char* view = of->get_output_view(start, sh_size);
this->read(shdr.get_sh_offset(), sh_size, view);
pvs->view = view;
pvs->address = os->address() + map_sections[i].offset;
pvs->offset = start;
pvs->view_size = sh_size;
}
}
// Relocate section data. VIEWS points to the section data as views
// in the output file.
template<int size, bool big_endian>
void
Sized_relobj<size, big_endian>::relocate_sections(
const General_options& options,
const Symbol_table* symtab,
const Layout* layout,
const unsigned char* pshdrs,
Views* pviews)
{
unsigned int shnum = this->shnum();
Sized_target<size, big_endian>* target = this->sized_target();
Relocate_info<size, big_endian> relinfo;
relinfo.options = &options;
relinfo.symtab = symtab;
relinfo.layout = layout;
relinfo.object = this;
relinfo.local_symbol_count = this->local_symbol_count_;
relinfo.local_values = &this->local_values_;
relinfo.symbols = this->symbols_;
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);
unsigned int sh_type = shdr.get_sh_type();
if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
continue;
unsigned int index = shdr.get_sh_info();
if (index >= this->shnum())
{
fprintf(stderr, _("%s: %s: relocation section %u has bad info %u\n"),
program_name, this->name().c_str(), i, index);
gold_exit(false);
}
if (!this->is_section_included(index))
{
// This relocation section is against a section which we
// discarded.
continue;
}
gold_assert((*pviews)[index].view != NULL);
if (shdr.get_sh_link() != this->symtab_shndx_)
{
fprintf(stderr,
_("%s: %s: relocation section %u uses unexpected "
"symbol table %u\n"),
program_name, this->name().c_str(), i, shdr.get_sh_link());
gold_exit(false);
}
off_t sh_size = shdr.get_sh_size();
const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
sh_size, false);
unsigned int reloc_size;
if (sh_type == elfcpp::SHT_REL)
reloc_size = elfcpp::Elf_sizes<size>::rel_size;
else
reloc_size = elfcpp::Elf_sizes<size>::rela_size;
if (reloc_size != shdr.get_sh_entsize())
{
fprintf(stderr,
_("%s: %s: unexpected entsize for reloc section %u: "
"%lu != %u"),
program_name, this->name().c_str(), i,
static_cast<unsigned long>(shdr.get_sh_entsize()),
reloc_size);
gold_exit(false);
}
size_t reloc_count = sh_size / reloc_size;
if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
{
fprintf(stderr, _("%s: %s: reloc section %u size %lu uneven"),
program_name, this->name().c_str(), i,
static_cast<unsigned long>(sh_size));
gold_exit(false);
}
relinfo.reloc_shndx = i;
relinfo.data_shndx = index;
target->relocate_section(&relinfo,
sh_type,
prelocs,
reloc_count,
(*pviews)[index].view,
(*pviews)[index].address,
(*pviews)[index].view_size);
}
}
// Copy_relocs::Copy_reloc_entry methods.
// Return whether we should emit this reloc. We should emit it if the
// symbol is still defined in a dynamic object. If we should not emit
// it, we clear it, to save ourselves the test next time.
template<int size, bool big_endian>
bool
Copy_relocs<size, big_endian>::Copy_reloc_entry::should_emit()
{
if (this->sym_ == NULL)
return false;
if (this->sym_->is_from_dynobj())
return true;
this->sym_ = NULL;
return false;
}
// Emit a reloc into a SHT_REL section.
template<int size, bool big_endian>
void
Copy_relocs<size, big_endian>::Copy_reloc_entry::emit(
Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>* reloc_data)
{
this->sym_->set_needs_dynsym_entry();
reloc_data->add_global(this->sym_, this->reloc_type_, this->relobj_,
this->shndx_, this->address_);
}
// Emit a reloc into a SHT_RELA section.
template<int size, bool big_endian>
void
Copy_relocs<size, big_endian>::Copy_reloc_entry::emit(
Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>* reloc_data)
{
this->sym_->set_needs_dynsym_entry();
reloc_data->add_global(this->sym_, this->reloc_type_, this->relobj_,
this->shndx_, this->address_, this->addend_);
}
// Copy_relocs methods.
// Return whether we need a COPY reloc for a relocation against GSYM.
// The relocation is being applied to section SHNDX in OBJECT.
template<int size, bool big_endian>
bool
Copy_relocs<size, big_endian>::need_copy_reloc(
const General_options*,
Relobj* object,
unsigned int shndx,
Sized_symbol<size>* sym)
{
// FIXME: Handle -z nocopyrelocs.
if (sym->symsize() == 0)
return false;
// If this is a readonly section, then we need a COPY reloc.
// Otherwise we can use a dynamic reloc.
if ((object->section_flags(shndx) & elfcpp::SHF_WRITE) == 0)
return true;
return false;
}
// Save a Rel reloc.
template<int size, bool big_endian>
void
Copy_relocs<size, big_endian>::save(
Symbol* sym,
Relobj* relobj,
unsigned int shndx,
const elfcpp::Rel<size, big_endian>& rel)
{
unsigned int reloc_type = elfcpp::elf_r_type<size>(rel.get_r_info());
this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, relobj, shndx,
rel.get_r_offset(), 0));
}
// Save a Rela reloc.
template<int size, bool big_endian>
void
Copy_relocs<size, big_endian>::save(
Symbol* sym,
Relobj* relobj,
unsigned int shndx,
const elfcpp::Rela<size, big_endian>& rela)
{
unsigned int reloc_type = elfcpp::elf_r_type<size>(rela.get_r_info());
this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, relobj, shndx,
rela.get_r_offset(),
rela.get_r_addend()));
}
// Return whether there are any relocs to emit. We don't want to emit
// a reloc if the symbol is no longer defined in a dynamic object.
template<int size, bool big_endian>
bool
Copy_relocs<size, big_endian>::any_to_emit()
{
for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
p != this->entries_.end();
++p)
{
if (p->should_emit())
return true;
}
return false;
}
// Emit relocs.
template<int size, bool big_endian>
template<int sh_type>
void
Copy_relocs<size, big_endian>::emit(
Output_data_reloc<sh_type, true, size, big_endian>* reloc_data)
{
for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
p != this->entries_.end();
++p)
{
if (p->should_emit())
p->emit(reloc_data);
}
}
// Instantiate the templates we need. We could use the configure
// script to restrict this to only the ones for implemented targets.
#ifdef HAVE_TARGET_32_LITTLE
template
void
Sized_relobj<32, false>::do_read_relocs(Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_32_BIG
template
void
Sized_relobj<32, true>::do_read_relocs(Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
void
Sized_relobj<64, false>::do_read_relocs(Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_64_BIG
template
void
Sized_relobj<64, true>::do_read_relocs(Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
void
Sized_relobj<32, false>::do_scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_32_BIG
template
void
Sized_relobj<32, true>::do_scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
void
Sized_relobj<64, false>::do_scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_64_BIG
template
void
Sized_relobj<64, true>::do_scan_relocs(const General_options& options,
Symbol_table* symtab,
Layout* layout,
Read_relocs_data* rd);
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
void
Sized_relobj<32, false>::do_relocate(const General_options& options,
const Symbol_table* symtab,
const Layout* layout,
Output_file* of);
#endif
#ifdef HAVE_TARGET_32_BIG
template
void
Sized_relobj<32, true>::do_relocate(const General_options& options,
const Symbol_table* symtab,
const Layout* layout,
Output_file* of);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
void
Sized_relobj<64, false>::do_relocate(const General_options& options,
const Symbol_table* symtab,
const Layout* layout,
Output_file* of);
#endif
#ifdef HAVE_TARGET_64_BIG
template
void
Sized_relobj<64, true>::do_relocate(const General_options& options,
const Symbol_table* symtab,
const Layout* layout,
Output_file* of);
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
class Copy_relocs<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Copy_relocs<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Copy_relocs<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Copy_relocs<64, true>;
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
void
Copy_relocs<32, false>::emit<elfcpp::SHT_REL>(
Output_data_reloc<elfcpp::SHT_REL, true, 32, false>*);
#endif
#ifdef HAVE_TARGET_32_BIG
template
void
Copy_relocs<32, true>::emit<elfcpp::SHT_REL>(
Output_data_reloc<elfcpp::SHT_REL, true, 32, true>*);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
void
Copy_relocs<64, false>::emit<elfcpp::SHT_REL>(
Output_data_reloc<elfcpp::SHT_REL, true, 64, false>*);
#endif
#ifdef HAVE_TARGET_64_BIG
template
void
Copy_relocs<64, true>::emit<elfcpp::SHT_REL>(
Output_data_reloc<elfcpp::SHT_REL, true, 64, true>*);
#endif
#ifdef HAVE_TARGET_32_LITTLE
template
void
Copy_relocs<32, false>::emit<elfcpp::SHT_RELA>(
Output_data_reloc<elfcpp::SHT_RELA , true, 32, false>*);
#endif
#ifdef HAVE_TARGET_32_BIG
template
void
Copy_relocs<32, true>::emit<elfcpp::SHT_RELA>(
Output_data_reloc<elfcpp::SHT_RELA, true, 32, true>*);
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
void
Copy_relocs<64, false>::emit<elfcpp::SHT_RELA>(
Output_data_reloc<elfcpp::SHT_RELA, true, 64, false>*);
#endif
#ifdef HAVE_TARGET_64_BIG
template
void
Copy_relocs<64, true>::emit<elfcpp::SHT_RELA>(
Output_data_reloc<elfcpp::SHT_RELA, true, 64, true>*);
#endif
} // End namespace gold.