1 // reloc.cc -- relocate input files for gold.
3 // Copyright 2006, 2007 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
25 #include "workqueue.h"
34 // Read_relocs methods.
36 // These tasks just read the relocation information from the file.
37 // After reading it, the start another task to process the
38 // information. These tasks requires access to the file.
40 Task::Is_runnable_type
41 Read_relocs::is_runnable(Workqueue*)
43 return this->object_->is_locked() ? IS_LOCKED : IS_RUNNABLE;
49 Read_relocs::locks(Workqueue*)
51 return new Task_locker_obj<Object>(*this->object_);
54 // Read the relocations and then start a Scan_relocs_task.
57 Read_relocs::run(Workqueue* workqueue)
59 Read_relocs_data *rd = new Read_relocs_data;
60 this->object_->read_relocs(rd);
61 workqueue->queue_front(new Scan_relocs(this->options_, this->symtab_,
62 this->layout_, this->object_, rd,
63 this->symtab_lock_, this->blocker_));
66 // Scan_relocs methods.
68 // These tasks scan the relocations read by Read_relocs and mark up
69 // the symbol table to indicate which relocations are required. We
70 // use a lock on the symbol table to keep them from interfering with
73 Task::Is_runnable_type
74 Scan_relocs::is_runnable(Workqueue*)
76 if (!this->symtab_lock_->is_writable() || this->object_->is_locked())
81 // Return the locks we hold: one on the file, one on the symbol table
84 class Scan_relocs::Scan_relocs_locker : public Task_locker
87 Scan_relocs_locker(Object* object, Task_token& symtab_lock, Task* task,
88 Task_token& blocker, Workqueue* workqueue)
89 : objlock_(*object), symtab_locker_(symtab_lock, task),
90 blocker_(blocker, workqueue)
94 Task_locker_obj<Object> objlock_;
95 Task_locker_write symtab_locker_;
96 Task_locker_block blocker_;
100 Scan_relocs::locks(Workqueue* workqueue)
102 return new Scan_relocs_locker(this->object_, *this->symtab_lock_, this,
103 *this->blocker_, workqueue);
109 Scan_relocs::run(Workqueue*)
111 this->object_->scan_relocs(this->options_, this->symtab_, this->layout_,
117 // Relocate_task methods.
119 // These tasks are always runnable.
121 Task::Is_runnable_type
122 Relocate_task::is_runnable(Workqueue*)
127 // We want to lock the file while we run. We want to unblock
128 // FINAL_BLOCKER when we are done.
130 class Relocate_task::Relocate_locker : public Task_locker
133 Relocate_locker(Task_token& token, Workqueue* workqueue,
135 : blocker_(token, workqueue), objlock_(*object)
139 Task_locker_block blocker_;
140 Task_locker_obj<Object> objlock_;
144 Relocate_task::locks(Workqueue* workqueue)
146 return new Relocate_locker(*this->final_blocker_, workqueue,
153 Relocate_task::run(Workqueue*)
155 this->object_->relocate(this->options_, this->symtab_, this->layout_,
159 // Read the relocs and local symbols from the object file and store
160 // the information in RD.
162 template<int size, bool big_endian>
164 Sized_relobj<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
168 unsigned int shnum = this->shnum();
172 rd->relocs.reserve(shnum / 2);
174 const unsigned char *pshdrs = this->get_view(this->elf_file_.shoff(),
175 shnum * This::shdr_size,
177 // Skip the first, dummy, section.
178 const unsigned char *ps = pshdrs + This::shdr_size;
179 for (unsigned int i = 1; i < shnum; ++i, ps += This::shdr_size)
181 typename This::Shdr shdr(ps);
183 unsigned int sh_type = shdr.get_sh_type();
184 if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
187 unsigned int shndx = shdr.get_sh_info();
190 fprintf(stderr, _("%s: %s: relocation section %u has bad info %u\n"),
191 program_name, this->name().c_str(), i, shndx);
195 if (!this->is_section_included(shndx))
198 // We are scanning relocations in order to fill out the GOT and
199 // PLT sections. Relocations for sections which are not
200 // allocated (typically debugging sections) should not add new
201 // GOT and PLT entries. So we skip them.
202 typename This::Shdr secshdr(pshdrs + shndx * This::shdr_size);
203 if ((secshdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0)
206 if (shdr.get_sh_link() != this->symtab_shndx_)
209 _("%s: %s: relocation section %u uses unexpected "
210 "symbol table %u\n"),
211 program_name, this->name().c_str(), i, shdr.get_sh_link());
215 off_t sh_size = shdr.get_sh_size();
217 unsigned int reloc_size;
218 if (sh_type == elfcpp::SHT_REL)
219 reloc_size = elfcpp::Elf_sizes<size>::rel_size;
221 reloc_size = elfcpp::Elf_sizes<size>::rela_size;
222 if (reloc_size != shdr.get_sh_entsize())
225 _("%s: %s: unexpected entsize for reloc section %u: "
227 program_name, this->name().c_str(), i,
228 static_cast<unsigned long>(shdr.get_sh_entsize()),
233 size_t reloc_count = sh_size / reloc_size;
234 if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
236 fprintf(stderr, _("%s: %s: reloc section %u size %lu uneven"),
237 program_name, this->name().c_str(), i,
238 static_cast<unsigned long>(sh_size));
242 rd->relocs.push_back(Section_relocs());
243 Section_relocs& sr(rd->relocs.back());
245 sr.data_shndx = shndx;
246 sr.contents = this->get_lasting_view(shdr.get_sh_offset(), sh_size,
248 sr.sh_type = sh_type;
249 sr.reloc_count = reloc_count;
252 // Read the local symbols.
253 gold_assert(this->symtab_shndx_ != -1U);
254 if (this->symtab_shndx_ == 0 || this->local_symbol_count_ == 0)
255 rd->local_symbols = NULL;
258 typename This::Shdr symtabshdr(pshdrs
259 + this->symtab_shndx_ * This::shdr_size);
260 gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
261 const int sym_size = This::sym_size;
262 const unsigned int loccount = this->local_symbol_count_;
263 gold_assert(loccount == symtabshdr.get_sh_info());
264 off_t locsize = loccount * sym_size;
265 rd->local_symbols = this->get_lasting_view(symtabshdr.get_sh_offset(),
270 // Scan the relocs and adjust the symbol table. This looks for
271 // relocations which require GOT/PLT/COPY relocations.
273 template<int size, bool big_endian>
275 Sized_relobj<size, big_endian>::do_scan_relocs(const General_options& options,
276 Symbol_table* symtab,
278 Read_relocs_data* rd)
280 Sized_target<size, big_endian>* target = this->sized_target();
282 const unsigned char* local_symbols;
283 if (rd->local_symbols == NULL)
284 local_symbols = NULL;
286 local_symbols = rd->local_symbols->data();
288 for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
289 p != rd->relocs.end();
292 target->scan_relocs(options, symtab, layout, this, p->data_shndx,
293 p->sh_type, p->contents->data(), p->reloc_count,
294 this->local_symbol_count_,
301 if (rd->local_symbols != NULL)
303 delete rd->local_symbols;
304 rd->local_symbols = NULL;
308 // Relocate the input sections and write out the local symbols.
310 template<int size, bool big_endian>
312 Sized_relobj<size, big_endian>::do_relocate(const General_options& options,
313 const Symbol_table* symtab,
314 const Layout* layout,
317 unsigned int shnum = this->shnum();
319 // Read the section headers.
320 const unsigned char* pshdrs = this->get_view(this->elf_file_.shoff(),
321 shnum * This::shdr_size,
327 // Make two passes over the sections. The first one copies the
328 // section data to the output file. The second one applies
331 this->write_sections(pshdrs, of, &views);
333 // Apply relocations.
335 this->relocate_sections(options, symtab, layout, pshdrs, &views);
337 // Write out the accumulated views.
338 for (unsigned int i = 1; i < shnum; ++i)
340 if (views[i].view != NULL)
341 of->write_output_view(views[i].offset, views[i].view_size,
345 // Write out the local symbols.
346 this->write_local_symbols(of, layout->sympool());
349 // Write section data to the output file. PSHDRS points to the
350 // section headers. Record the views in *PVIEWS for use when
353 template<int size, bool big_endian>
355 Sized_relobj<size, big_endian>::write_sections(const unsigned char* pshdrs,
359 unsigned int shnum = this->shnum();
360 std::vector<Map_to_output>& map_sections(this->map_to_output());
362 const unsigned char* p = pshdrs + This::shdr_size;
363 for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
365 View_size* pvs = &(*pviews)[i];
369 if (map_sections[i].offset == -1)
372 const Output_section* os = map_sections[i].output_section;
376 typename This::Shdr shdr(p);
378 if (shdr.get_sh_type() == elfcpp::SHT_NOBITS)
381 off_t start = os->offset() + map_sections[i].offset;
382 off_t sh_size = shdr.get_sh_size();
387 gold_assert(map_sections[i].offset >= 0
388 && map_sections[i].offset + sh_size <= os->data_size());
390 unsigned char* view = of->get_output_view(start, sh_size);
391 this->read(shdr.get_sh_offset(), sh_size, view);
394 pvs->address = os->address() + map_sections[i].offset;
396 pvs->view_size = sh_size;
400 // Relocate section data. VIEWS points to the section data as views
401 // in the output file.
403 template<int size, bool big_endian>
405 Sized_relobj<size, big_endian>::relocate_sections(
406 const General_options& options,
407 const Symbol_table* symtab,
408 const Layout* layout,
409 const unsigned char* pshdrs,
412 unsigned int shnum = this->shnum();
413 Sized_target<size, big_endian>* target = this->sized_target();
415 Relocate_info<size, big_endian> relinfo;
416 relinfo.options = &options;
417 relinfo.symtab = symtab;
418 relinfo.layout = layout;
419 relinfo.object = this;
420 relinfo.local_symbol_count = this->local_symbol_count_;
421 relinfo.local_values = &this->local_values_;
422 relinfo.symbols = this->symbols_;
424 const unsigned char* p = pshdrs + This::shdr_size;
425 for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
427 typename This::Shdr shdr(p);
429 unsigned int sh_type = shdr.get_sh_type();
430 if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
433 unsigned int index = shdr.get_sh_info();
434 if (index >= this->shnum())
436 fprintf(stderr, _("%s: %s: relocation section %u has bad info %u\n"),
437 program_name, this->name().c_str(), i, index);
441 if (!this->is_section_included(index))
443 // This relocation section is against a section which we
448 gold_assert((*pviews)[index].view != NULL);
450 if (shdr.get_sh_link() != this->symtab_shndx_)
453 _("%s: %s: relocation section %u uses unexpected "
454 "symbol table %u\n"),
455 program_name, this->name().c_str(), i, shdr.get_sh_link());
459 off_t sh_size = shdr.get_sh_size();
460 const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
463 unsigned int reloc_size;
464 if (sh_type == elfcpp::SHT_REL)
465 reloc_size = elfcpp::Elf_sizes<size>::rel_size;
467 reloc_size = elfcpp::Elf_sizes<size>::rela_size;
469 if (reloc_size != shdr.get_sh_entsize())
472 _("%s: %s: unexpected entsize for reloc section %u: "
474 program_name, this->name().c_str(), i,
475 static_cast<unsigned long>(shdr.get_sh_entsize()),
480 size_t reloc_count = sh_size / reloc_size;
481 if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
483 fprintf(stderr, _("%s: %s: reloc section %u size %lu uneven"),
484 program_name, this->name().c_str(), i,
485 static_cast<unsigned long>(sh_size));
489 relinfo.reloc_shndx = i;
490 relinfo.data_shndx = index;
491 target->relocate_section(&relinfo,
495 (*pviews)[index].view,
496 (*pviews)[index].address,
497 (*pviews)[index].view_size);
501 // Copy_relocs::Copy_reloc_entry methods.
503 // Return whether we should emit this reloc. We should emit it if the
504 // symbol is still defined in a dynamic object. If we should not emit
505 // it, we clear it, to save ourselves the test next time.
507 template<int size, bool big_endian>
509 Copy_relocs<size, big_endian>::Copy_reloc_entry::should_emit()
511 if (this->sym_ == NULL)
513 if (this->sym_->is_from_dynobj())
519 // Emit a reloc into a SHT_REL section.
521 template<int size, bool big_endian>
523 Copy_relocs<size, big_endian>::Copy_reloc_entry::emit(
524 Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>* reloc_data)
526 this->sym_->set_needs_dynsym_entry();
527 reloc_data->add_global(this->sym_, this->reloc_type_, this->relobj_,
528 this->shndx_, this->address_);
531 // Emit a reloc into a SHT_RELA section.
533 template<int size, bool big_endian>
535 Copy_relocs<size, big_endian>::Copy_reloc_entry::emit(
536 Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>* reloc_data)
538 this->sym_->set_needs_dynsym_entry();
539 reloc_data->add_global(this->sym_, this->reloc_type_, this->relobj_,
540 this->shndx_, this->address_, this->addend_);
543 // Copy_relocs methods.
545 // Return whether we need a COPY reloc for a relocation against GSYM.
546 // The relocation is being applied to section SHNDX in OBJECT.
548 template<int size, bool big_endian>
550 Copy_relocs<size, big_endian>::need_copy_reloc(
551 const General_options*,
554 Sized_symbol<size>* sym)
556 // FIXME: Handle -z nocopyrelocs.
558 if (sym->symsize() == 0)
561 // If this is a readonly section, then we need a COPY reloc.
562 // Otherwise we can use a dynamic reloc.
563 if ((object->section_flags(shndx) & elfcpp::SHF_WRITE) == 0)
571 template<int size, bool big_endian>
573 Copy_relocs<size, big_endian>::save(
577 const elfcpp::Rel<size, big_endian>& rel)
579 unsigned int reloc_type = elfcpp::elf_r_type<size>(rel.get_r_info());
580 this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, relobj, shndx,
581 rel.get_r_offset(), 0));
584 // Save a Rela reloc.
586 template<int size, bool big_endian>
588 Copy_relocs<size, big_endian>::save(
592 const elfcpp::Rela<size, big_endian>& rela)
594 unsigned int reloc_type = elfcpp::elf_r_type<size>(rela.get_r_info());
595 this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, relobj, shndx,
597 rela.get_r_addend()));
600 // Return whether there are any relocs to emit. We don't want to emit
601 // a reloc if the symbol is no longer defined in a dynamic object.
603 template<int size, bool big_endian>
605 Copy_relocs<size, big_endian>::any_to_emit()
607 for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
608 p != this->entries_.end();
611 if (p->should_emit())
619 template<int size, bool big_endian>
620 template<int sh_type>
622 Copy_relocs<size, big_endian>::emit(
623 Output_data_reloc<sh_type, true, size, big_endian>* reloc_data)
625 for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
626 p != this->entries_.end();
629 if (p->should_emit())
634 // Instantiate the templates we need. We could use the configure
635 // script to restrict this to only the ones for implemented targets.
637 #ifdef HAVE_TARGET_32_LITTLE
640 Sized_relobj<32, false>::do_read_relocs(Read_relocs_data* rd);
643 #ifdef HAVE_TARGET_32_BIG
646 Sized_relobj<32, true>::do_read_relocs(Read_relocs_data* rd);
649 #ifdef HAVE_TARGET_64_LITTLE
652 Sized_relobj<64, false>::do_read_relocs(Read_relocs_data* rd);
655 #ifdef HAVE_TARGET_64_BIG
658 Sized_relobj<64, true>::do_read_relocs(Read_relocs_data* rd);
661 #ifdef HAVE_TARGET_32_LITTLE
664 Sized_relobj<32, false>::do_scan_relocs(const General_options& options,
665 Symbol_table* symtab,
667 Read_relocs_data* rd);
670 #ifdef HAVE_TARGET_32_BIG
673 Sized_relobj<32, true>::do_scan_relocs(const General_options& options,
674 Symbol_table* symtab,
676 Read_relocs_data* rd);
679 #ifdef HAVE_TARGET_64_LITTLE
682 Sized_relobj<64, false>::do_scan_relocs(const General_options& options,
683 Symbol_table* symtab,
685 Read_relocs_data* rd);
688 #ifdef HAVE_TARGET_64_BIG
691 Sized_relobj<64, true>::do_scan_relocs(const General_options& options,
692 Symbol_table* symtab,
694 Read_relocs_data* rd);
697 #ifdef HAVE_TARGET_32_LITTLE
700 Sized_relobj<32, false>::do_relocate(const General_options& options,
701 const Symbol_table* symtab,
702 const Layout* layout,
706 #ifdef HAVE_TARGET_32_BIG
709 Sized_relobj<32, true>::do_relocate(const General_options& options,
710 const Symbol_table* symtab,
711 const Layout* layout,
715 #ifdef HAVE_TARGET_64_LITTLE
718 Sized_relobj<64, false>::do_relocate(const General_options& options,
719 const Symbol_table* symtab,
720 const Layout* layout,
724 #ifdef HAVE_TARGET_64_BIG
727 Sized_relobj<64, true>::do_relocate(const General_options& options,
728 const Symbol_table* symtab,
729 const Layout* layout,
733 #ifdef HAVE_TARGET_32_LITTLE
735 class Copy_relocs<32, false>;
738 #ifdef HAVE_TARGET_32_BIG
740 class Copy_relocs<32, true>;
743 #ifdef HAVE_TARGET_64_LITTLE
745 class Copy_relocs<64, false>;
748 #ifdef HAVE_TARGET_64_BIG
750 class Copy_relocs<64, true>;
753 #ifdef HAVE_TARGET_32_LITTLE
756 Copy_relocs<32, false>::emit<elfcpp::SHT_REL>(
757 Output_data_reloc<elfcpp::SHT_REL, true, 32, false>*);
760 #ifdef HAVE_TARGET_32_BIG
763 Copy_relocs<32, true>::emit<elfcpp::SHT_REL>(
764 Output_data_reloc<elfcpp::SHT_REL, true, 32, true>*);
767 #ifdef HAVE_TARGET_64_LITTLE
770 Copy_relocs<64, false>::emit<elfcpp::SHT_REL>(
771 Output_data_reloc<elfcpp::SHT_REL, true, 64, false>*);
774 #ifdef HAVE_TARGET_64_BIG
777 Copy_relocs<64, true>::emit<elfcpp::SHT_REL>(
778 Output_data_reloc<elfcpp::SHT_REL, true, 64, true>*);
781 #ifdef HAVE_TARGET_32_LITTLE
784 Copy_relocs<32, false>::emit<elfcpp::SHT_RELA>(
785 Output_data_reloc<elfcpp::SHT_RELA , true, 32, false>*);
788 #ifdef HAVE_TARGET_32_BIG
791 Copy_relocs<32, true>::emit<elfcpp::SHT_RELA>(
792 Output_data_reloc<elfcpp::SHT_RELA, true, 32, true>*);
795 #ifdef HAVE_TARGET_64_LITTLE
798 Copy_relocs<64, false>::emit<elfcpp::SHT_RELA>(
799 Output_data_reloc<elfcpp::SHT_RELA, true, 64, false>*);
802 #ifdef HAVE_TARGET_64_BIG
805 Copy_relocs<64, true>::emit<elfcpp::SHT_RELA>(
806 Output_data_reloc<elfcpp::SHT_RELA, true, 64, true>*);
809 } // End namespace gold.