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
);
176 // Skip the first, dummy, section.
177 const unsigned char *ps
= pshdrs
+ This::shdr_size
;
178 for (unsigned int i
= 1; i
< shnum
; ++i
, ps
+= This::shdr_size
)
180 typename
This::Shdr
shdr(ps
);
182 unsigned int sh_type
= shdr
.get_sh_type();
183 if (sh_type
!= elfcpp::SHT_REL
&& sh_type
!= elfcpp::SHT_RELA
)
186 unsigned int shndx
= shdr
.get_sh_info();
189 fprintf(stderr
, _("%s: %s: relocation section %u has bad info %u\n"),
190 program_name
, this->name().c_str(), i
, shndx
);
194 if (!this->is_section_included(shndx
))
197 // We are scanning relocations in order to fill out the GOT and
198 // PLT sections. Relocations for sections which are not
199 // allocated (typically debugging sections) should not add new
200 // GOT and PLT entries. So we skip them.
201 typename
This::Shdr
secshdr(pshdrs
+ shndx
* This::shdr_size
);
202 if ((secshdr
.get_sh_flags() & elfcpp::SHF_ALLOC
) == 0)
205 if (shdr
.get_sh_link() != this->symtab_shndx_
)
208 _("%s: %s: relocation section %u uses unexpected "
209 "symbol table %u\n"),
210 program_name
, this->name().c_str(), i
, shdr
.get_sh_link());
214 off_t sh_size
= shdr
.get_sh_size();
216 unsigned int reloc_size
;
217 if (sh_type
== elfcpp::SHT_REL
)
218 reloc_size
= elfcpp::Elf_sizes
<size
>::rel_size
;
220 reloc_size
= elfcpp::Elf_sizes
<size
>::rela_size
;
221 if (reloc_size
!= shdr
.get_sh_entsize())
224 _("%s: %s: unexpected entsize for reloc section %u: "
226 program_name
, this->name().c_str(), i
,
227 static_cast<unsigned long>(shdr
.get_sh_entsize()),
232 size_t reloc_count
= sh_size
/ reloc_size
;
233 if (reloc_count
* reloc_size
!= sh_size
)
235 fprintf(stderr
, _("%s: %s: reloc section %u size %lu uneven"),
236 program_name
, this->name().c_str(), i
,
237 static_cast<unsigned long>(sh_size
));
241 rd
->relocs
.push_back(Section_relocs());
242 Section_relocs
& sr(rd
->relocs
.back());
244 sr
.data_shndx
= shndx
;
245 sr
.contents
= this->get_lasting_view(shdr
.get_sh_offset(), sh_size
);
246 sr
.sh_type
= sh_type
;
247 sr
.reloc_count
= reloc_count
;
250 // Read the local symbols.
251 gold_assert(this->symtab_shndx_
!= -1U);
252 if (this->symtab_shndx_
== 0 || this->local_symbol_count_
== 0)
253 rd
->local_symbols
= NULL
;
256 typename
This::Shdr
symtabshdr(pshdrs
257 + this->symtab_shndx_
* This::shdr_size
);
258 gold_assert(symtabshdr
.get_sh_type() == elfcpp::SHT_SYMTAB
);
259 const int sym_size
= This::sym_size
;
260 const unsigned int loccount
= this->local_symbol_count_
;
261 gold_assert(loccount
== symtabshdr
.get_sh_info());
262 off_t locsize
= loccount
* sym_size
;
263 rd
->local_symbols
= this->get_lasting_view(symtabshdr
.get_sh_offset(),
268 // Scan the relocs and adjust the symbol table. This looks for
269 // relocations which require GOT/PLT/COPY relocations.
271 template<int size
, bool big_endian
>
273 Sized_relobj
<size
, big_endian
>::do_scan_relocs(const General_options
& options
,
274 Symbol_table
* symtab
,
276 Read_relocs_data
* rd
)
278 Sized_target
<size
, big_endian
>* target
= this->sized_target();
280 const unsigned char* local_symbols
;
281 if (rd
->local_symbols
== NULL
)
282 local_symbols
= NULL
;
284 local_symbols
= rd
->local_symbols
->data();
286 for (Read_relocs_data::Relocs_list::iterator p
= rd
->relocs
.begin();
287 p
!= rd
->relocs
.end();
290 target
->scan_relocs(options
, symtab
, layout
, this, p
->data_shndx
,
291 p
->sh_type
, p
->contents
->data(), p
->reloc_count
,
292 this->local_symbol_count_
,
299 if (rd
->local_symbols
!= NULL
)
301 delete rd
->local_symbols
;
302 rd
->local_symbols
= NULL
;
306 // Relocate the input sections and write out the local symbols.
308 template<int size
, bool big_endian
>
310 Sized_relobj
<size
, big_endian
>::do_relocate(const General_options
& options
,
311 const Symbol_table
* symtab
,
312 const Layout
* layout
,
315 unsigned int shnum
= this->shnum();
317 // Read the section headers.
318 const unsigned char* pshdrs
= this->get_view(this->elf_file_
.shoff(),
319 shnum
* This::shdr_size
);
324 // Make two passes over the sections. The first one copies the
325 // section data to the output file. The second one applies
328 this->write_sections(pshdrs
, of
, &views
);
330 // Apply relocations.
332 this->relocate_sections(options
, symtab
, layout
, pshdrs
, &views
);
334 // Write out the accumulated views.
335 for (unsigned int i
= 1; i
< shnum
; ++i
)
337 if (views
[i
].view
!= NULL
)
338 of
->write_output_view(views
[i
].offset
, views
[i
].view_size
,
342 // Write out the local symbols.
343 this->write_local_symbols(of
, layout
->sympool());
346 // Write section data to the output file. PSHDRS points to the
347 // section headers. Record the views in *PVIEWS for use when
350 template<int size
, bool big_endian
>
352 Sized_relobj
<size
, big_endian
>::write_sections(const unsigned char* pshdrs
,
356 unsigned int shnum
= this->shnum();
357 std::vector
<Map_to_output
>& map_sections(this->map_to_output());
359 const unsigned char* p
= pshdrs
+ This::shdr_size
;
360 for (unsigned int i
= 1; i
< shnum
; ++i
, p
+= This::shdr_size
)
362 View_size
* pvs
= &(*pviews
)[i
];
366 if (map_sections
[i
].offset
== -1)
369 const Output_section
* os
= map_sections
[i
].output_section
;
373 typename
This::Shdr
shdr(p
);
375 if (shdr
.get_sh_type() == elfcpp::SHT_NOBITS
)
378 off_t start
= os
->offset() + map_sections
[i
].offset
;
379 off_t sh_size
= shdr
.get_sh_size();
384 gold_assert(map_sections
[i
].offset
>= 0
385 && map_sections
[i
].offset
+ sh_size
<= os
->data_size());
387 unsigned char* view
= of
->get_output_view(start
, sh_size
);
388 this->read(shdr
.get_sh_offset(), sh_size
, view
);
391 pvs
->address
= os
->address() + map_sections
[i
].offset
;
393 pvs
->view_size
= sh_size
;
397 // Relocate section data. VIEWS points to the section data as views
398 // in the output file.
400 template<int size
, bool big_endian
>
402 Sized_relobj
<size
, big_endian
>::relocate_sections(
403 const General_options
& options
,
404 const Symbol_table
* symtab
,
405 const Layout
* layout
,
406 const unsigned char* pshdrs
,
409 unsigned int shnum
= this->shnum();
410 Sized_target
<size
, big_endian
>* target
= this->sized_target();
412 Relocate_info
<size
, big_endian
> relinfo
;
413 relinfo
.options
= &options
;
414 relinfo
.symtab
= symtab
;
415 relinfo
.layout
= layout
;
416 relinfo
.object
= this;
417 relinfo
.local_symbol_count
= this->local_symbol_count_
;
418 relinfo
.local_values
= &this->local_values_
;
419 relinfo
.symbols
= this->symbols_
;
421 const unsigned char* p
= pshdrs
+ This::shdr_size
;
422 for (unsigned int i
= 1; i
< shnum
; ++i
, p
+= This::shdr_size
)
424 typename
This::Shdr
shdr(p
);
426 unsigned int sh_type
= shdr
.get_sh_type();
427 if (sh_type
!= elfcpp::SHT_REL
&& sh_type
!= elfcpp::SHT_RELA
)
430 unsigned int index
= shdr
.get_sh_info();
431 if (index
>= this->shnum())
433 fprintf(stderr
, _("%s: %s: relocation section %u has bad info %u\n"),
434 program_name
, this->name().c_str(), i
, index
);
438 if (!this->is_section_included(index
))
440 // This relocation section is against a section which we
445 gold_assert((*pviews
)[index
].view
!= NULL
);
447 if (shdr
.get_sh_link() != this->symtab_shndx_
)
450 _("%s: %s: relocation section %u uses unexpected "
451 "symbol table %u\n"),
452 program_name
, this->name().c_str(), i
, shdr
.get_sh_link());
456 off_t sh_size
= shdr
.get_sh_size();
457 const unsigned char* prelocs
= this->get_view(shdr
.get_sh_offset(),
460 unsigned int reloc_size
;
461 if (sh_type
== elfcpp::SHT_REL
)
462 reloc_size
= elfcpp::Elf_sizes
<size
>::rel_size
;
464 reloc_size
= elfcpp::Elf_sizes
<size
>::rela_size
;
466 if (reloc_size
!= shdr
.get_sh_entsize())
469 _("%s: %s: unexpected entsize for reloc section %u: "
471 program_name
, this->name().c_str(), i
,
472 static_cast<unsigned long>(shdr
.get_sh_entsize()),
477 size_t reloc_count
= sh_size
/ reloc_size
;
478 if (reloc_count
* reloc_size
!= sh_size
)
480 fprintf(stderr
, _("%s: %s: reloc section %u size %lu uneven"),
481 program_name
, this->name().c_str(), i
,
482 static_cast<unsigned long>(sh_size
));
486 relinfo
.reloc_shndx
= i
;
487 relinfo
.data_shndx
= index
;
488 target
->relocate_section(&relinfo
,
492 (*pviews
)[index
].view
,
493 (*pviews
)[index
].address
,
494 (*pviews
)[index
].view_size
);
498 // Copy_relocs::Copy_reloc_entry methods.
500 // Return whether we should emit this reloc. We should emit it if the
501 // symbol is still defined in a dynamic object. If we should not emit
502 // it, we clear it, to save ourselves the test next time.
504 template<int size
, bool big_endian
>
506 Copy_relocs
<size
, big_endian
>::Copy_reloc_entry::should_emit()
508 if (this->sym_
== NULL
)
510 if (this->sym_
->is_from_dynobj())
516 // Emit a reloc into a SHT_REL section.
518 template<int size
, bool big_endian
>
520 Copy_relocs
<size
, big_endian
>::Copy_reloc_entry::emit(
521 Output_data_reloc
<elfcpp::SHT_REL
, true, size
, big_endian
>* reloc_data
)
523 this->sym_
->set_needs_dynsym_entry();
524 reloc_data
->add_global(this->sym_
, this->reloc_type_
, this->relobj_
,
525 this->shndx_
, this->address_
);
528 // Emit a reloc into a SHT_RELA section.
530 template<int size
, bool big_endian
>
532 Copy_relocs
<size
, big_endian
>::Copy_reloc_entry::emit(
533 Output_data_reloc
<elfcpp::SHT_RELA
, true, size
, big_endian
>* reloc_data
)
535 this->sym_
->set_needs_dynsym_entry();
536 reloc_data
->add_global(this->sym_
, this->reloc_type_
, this->relobj_
,
537 this->shndx_
, this->address_
, this->addend_
);
540 // Copy_relocs methods.
542 // Return whether we need a COPY reloc for a relocation against GSYM.
543 // The relocation is being applied to section SHNDX in OBJECT.
545 template<int size
, bool big_endian
>
547 Copy_relocs
<size
, big_endian
>::need_copy_reloc(
548 const General_options
*,
551 Sized_symbol
<size
>* sym
)
553 // FIXME: Handle -z nocopyrelocs.
555 if (sym
->symsize() == 0)
558 // If this is a readonly section, then we need a COPY reloc.
559 // Otherwise we can use a dynamic reloc.
560 if ((object
->section_flags(shndx
) & elfcpp::SHF_WRITE
) == 0)
568 template<int size
, bool big_endian
>
570 Copy_relocs
<size
, big_endian
>::save(
574 const elfcpp::Rel
<size
, big_endian
>& rel
)
576 unsigned int reloc_type
= elfcpp::elf_r_type
<size
>(rel
.get_r_info());
577 this->entries_
.push_back(Copy_reloc_entry(sym
, reloc_type
, relobj
, shndx
,
578 rel
.get_r_offset(), 0));
581 // Save a Rela reloc.
583 template<int size
, bool big_endian
>
585 Copy_relocs
<size
, big_endian
>::save(
589 const elfcpp::Rela
<size
, big_endian
>& rela
)
591 unsigned int reloc_type
= elfcpp::elf_r_type
<size
>(rela
.get_r_info());
592 this->entries_
.push_back(Copy_reloc_entry(sym
, reloc_type
, relobj
, shndx
,
594 rela
.get_r_addend()));
597 // Return whether there are any relocs to emit. We don't want to emit
598 // a reloc if the symbol is no longer defined in a dynamic object.
600 template<int size
, bool big_endian
>
602 Copy_relocs
<size
, big_endian
>::any_to_emit()
604 for (typename
Copy_reloc_entries::iterator p
= this->entries_
.begin();
605 p
!= this->entries_
.end();
608 if (p
->should_emit())
616 template<int size
, bool big_endian
>
617 template<int sh_type
>
619 Copy_relocs
<size
, big_endian
>::emit(
620 Output_data_reloc
<sh_type
, true, size
, big_endian
>* reloc_data
)
622 for (typename
Copy_reloc_entries::iterator p
= this->entries_
.begin();
623 p
!= this->entries_
.end();
626 if (p
->should_emit())
631 // Instantiate the templates we need. We could use the configure
632 // script to restrict this to only the ones for implemented targets.
634 #ifdef HAVE_TARGET_32_LITTLE
637 Sized_relobj
<32, false>::do_read_relocs(Read_relocs_data
* rd
);
640 #ifdef HAVE_TARGET_32_BIG
643 Sized_relobj
<32, true>::do_read_relocs(Read_relocs_data
* rd
);
646 #ifdef HAVE_TARGET_64_LITTLE
649 Sized_relobj
<64, false>::do_read_relocs(Read_relocs_data
* rd
);
652 #ifdef HAVE_TARGET_64_BIG
655 Sized_relobj
<64, true>::do_read_relocs(Read_relocs_data
* rd
);
658 #ifdef HAVE_TARGET_32_LITTLE
661 Sized_relobj
<32, false>::do_scan_relocs(const General_options
& options
,
662 Symbol_table
* symtab
,
664 Read_relocs_data
* rd
);
667 #ifdef HAVE_TARGET_32_BIG
670 Sized_relobj
<32, true>::do_scan_relocs(const General_options
& options
,
671 Symbol_table
* symtab
,
673 Read_relocs_data
* rd
);
676 #ifdef HAVE_TARGET_64_LITTLE
679 Sized_relobj
<64, false>::do_scan_relocs(const General_options
& options
,
680 Symbol_table
* symtab
,
682 Read_relocs_data
* rd
);
685 #ifdef HAVE_TARGET_64_BIG
688 Sized_relobj
<64, true>::do_scan_relocs(const General_options
& options
,
689 Symbol_table
* symtab
,
691 Read_relocs_data
* rd
);
694 #ifdef HAVE_TARGET_32_LITTLE
697 Sized_relobj
<32, false>::do_relocate(const General_options
& options
,
698 const Symbol_table
* symtab
,
699 const Layout
* layout
,
703 #ifdef HAVE_TARGET_32_BIG
706 Sized_relobj
<32, true>::do_relocate(const General_options
& options
,
707 const Symbol_table
* symtab
,
708 const Layout
* layout
,
712 #ifdef HAVE_TARGET_64_LITTLE
715 Sized_relobj
<64, false>::do_relocate(const General_options
& options
,
716 const Symbol_table
* symtab
,
717 const Layout
* layout
,
721 #ifdef HAVE_TARGET_64_BIG
724 Sized_relobj
<64, true>::do_relocate(const General_options
& options
,
725 const Symbol_table
* symtab
,
726 const Layout
* layout
,
730 #ifdef HAVE_TARGET_32_LITTLE
732 class Copy_relocs
<32, false>;
735 #ifdef HAVE_TARGET_32_BIG
737 class Copy_relocs
<32, true>;
740 #ifdef HAVE_TARGET_64_LITTLE
742 class Copy_relocs
<64, false>;
745 #ifdef HAVE_TARGET_64_BIG
747 class Copy_relocs
<64, true>;
750 #ifdef HAVE_TARGET_32_LITTLE
753 Copy_relocs
<32, false>::emit
<elfcpp::SHT_REL
>(
754 Output_data_reloc
<elfcpp::SHT_REL
, true, 32, false>*);
757 #ifdef HAVE_TARGET_32_BIG
760 Copy_relocs
<32, true>::emit
<elfcpp::SHT_REL
>(
761 Output_data_reloc
<elfcpp::SHT_REL
, true, 32, true>*);
764 #ifdef HAVE_TARGET_64_LITTLE
767 Copy_relocs
<64, false>::emit
<elfcpp::SHT_REL
>(
768 Output_data_reloc
<elfcpp::SHT_REL
, true, 64, false>*);
771 #ifdef HAVE_TARGET_64_BIG
774 Copy_relocs
<64, true>::emit
<elfcpp::SHT_REL
>(
775 Output_data_reloc
<elfcpp::SHT_REL
, true, 64, true>*);
778 #ifdef HAVE_TARGET_32_LITTLE
781 Copy_relocs
<32, false>::emit
<elfcpp::SHT_RELA
>(
782 Output_data_reloc
<elfcpp::SHT_RELA
, true, 32, false>*);
785 #ifdef HAVE_TARGET_32_BIG
788 Copy_relocs
<32, true>::emit
<elfcpp::SHT_RELA
>(
789 Output_data_reloc
<elfcpp::SHT_RELA
, true, 32, true>*);
792 #ifdef HAVE_TARGET_64_LITTLE
795 Copy_relocs
<64, false>::emit
<elfcpp::SHT_RELA
>(
796 Output_data_reloc
<elfcpp::SHT_RELA
, true, 64, false>*);
799 #ifdef HAVE_TARGET_64_BIG
802 Copy_relocs
<64, true>::emit
<elfcpp::SHT_RELA
>(
803 Output_data_reloc
<elfcpp::SHT_RELA
, true, 64, true>*);
806 } // End namespace gold.