1 // reloc.h -- relocate input files for gold -*- C++ -*-
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.
29 #include "workqueue.h"
34 class General_options;
37 class Read_relocs_data;
45 template<int size, bool big_endian>
51 template<int sh_type, bool dynamic, int size, bool big_endian>
52 class Output_data_reloc;
54 // A class to read the relocations for an object file, and then queue
55 // up a task to see if they require any GOT/PLT/COPY relocations in
58 class Read_relocs : public Task
61 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
62 // unblocked when the Scan_relocs task completes.
63 Read_relocs(const General_options& options, Symbol_table* symtab,
64 Layout* layout, Relobj* object, Task_token* symtab_lock,
66 : options_(options), symtab_(symtab), layout_(layout), object_(object),
67 symtab_lock_(symtab_lock), blocker_(blocker)
70 // The standard Task methods.
73 is_runnable(Workqueue*);
82 const General_options& options_;
83 Symbol_table* symtab_;
86 Task_token* symtab_lock_;
90 // Scan the relocations for an object to see if they require any
91 // GOT/PLT/COPY relocations.
93 class Scan_relocs : public Task
96 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
97 // unblocked when the task completes.
98 Scan_relocs(const General_options& options, Symbol_table* symtab,
99 Layout* layout, Relobj* object, Read_relocs_data* rd,
100 Task_token* symtab_lock, Task_token* blocker)
101 : options_(options), symtab_(symtab), layout_(layout), object_(object),
102 rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
105 // The standard Task methods.
108 is_runnable(Workqueue*);
117 class Scan_relocs_locker;
119 const General_options& options_;
120 Symbol_table* symtab_;
123 Read_relocs_data* rd_;
124 Task_token* symtab_lock_;
125 Task_token* blocker_;
128 // A class to perform all the relocations for an object file.
130 class Relocate_task : public Task
133 Relocate_task(const General_options& options, const Symbol_table* symtab,
134 const Layout* layout, Relobj* object, Output_file* of,
135 Task_token* input_sections_blocker,
136 Task_token* output_sections_blocker, Task_token* final_blocker)
137 : options_(options), symtab_(symtab), layout_(layout), object_(object),
138 of_(of), input_sections_blocker_(input_sections_blocker),
139 output_sections_blocker_(output_sections_blocker),
140 final_blocker_(final_blocker)
143 // The standard Task methods.
146 is_runnable(Workqueue*);
155 class Relocate_locker;
157 const General_options& options_;
158 const Symbol_table* symtab_;
159 const Layout* layout_;
162 Task_token* input_sections_blocker_;
163 Task_token* output_sections_blocker_;
164 Task_token* final_blocker_;
167 // Standard relocation routines which are used on many targets. Here
168 // SIZE and BIG_ENDIAN refer to the target, not the relocation type.
170 template<int size, bool big_endian>
171 class Relocate_functions
174 // Do a simple relocation with the addend in the section contents.
175 // VALSIZE is the size of the value.
176 template<int valsize>
178 rel(unsigned char* view,
179 typename elfcpp::Swap<valsize, big_endian>::Valtype value)
181 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
182 Valtype* wv = reinterpret_cast<Valtype*>(view);
183 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
184 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value);
187 // Do a simple relocation using a Symbol_value with the addend in
188 // the section contents. VALSIZE is the size of the value to
190 template<int valsize>
192 rel(unsigned char* view,
193 const Sized_relobj<size, big_endian>* object,
194 const Symbol_value<size>* psymval)
196 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
197 Valtype* wv = reinterpret_cast<Valtype*>(view);
198 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
199 x = psymval->value(object, x);
200 elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
203 // Do a simple relocation with the addend in the relocation.
204 // VALSIZE is the size of the value.
205 template<int valsize>
207 rela(unsigned char* view,
208 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
209 typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
211 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
212 Valtype* wv = reinterpret_cast<Valtype*>(view);
213 elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend);
216 // Do a simple relocation using a symbol value with the addend in
217 // the relocation. VALSIZE is the size of the value.
218 template<int valsize>
220 rela(unsigned char* view,
221 const Sized_relobj<size, big_endian>* object,
222 const Symbol_value<size>* psymval,
223 typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
225 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
226 Valtype* wv = reinterpret_cast<Valtype*>(view);
227 Valtype x = psymval->value(object, addend);
228 elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
231 // Do a simple PC relative relocation with the addend in the section
232 // contents. VALSIZE is the size of the value.
233 template<int valsize>
235 pcrel(unsigned char* view,
236 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
237 typename elfcpp::Elf_types<size>::Elf_Addr address)
239 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
240 Valtype* wv = reinterpret_cast<Valtype*>(view);
241 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
242 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address);
245 // Do a simple PC relative relocation with a Symbol_value with the
246 // addend in the section contents. VALSIZE is the size of the
248 template<int valsize>
250 pcrel(unsigned char* view,
251 const Sized_relobj<size, big_endian>* object,
252 const Symbol_value<size>* psymval,
253 typename elfcpp::Elf_types<size>::Elf_Addr address)
255 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
256 Valtype* wv = reinterpret_cast<Valtype*>(view);
257 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
258 x = psymval->value(object, x);
259 elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
262 // Do a simple PC relative relocation with the addend in the
263 // relocation. VALSIZE is the size of the value.
264 template<int valsize>
266 pcrela(unsigned char* view,
267 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
268 typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
269 typename elfcpp::Elf_types<size>::Elf_Addr address)
271 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
272 Valtype* wv = reinterpret_cast<Valtype*>(view);
273 elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend - address);
276 // Do a simple PC relative relocation with a Symbol_value with the
277 // addend in the relocation. VALSIZE is the size of the value.
278 template<int valsize>
280 pcrela(unsigned char* view,
281 const Sized_relobj<size, big_endian>* object,
282 const Symbol_value<size>* psymval,
283 typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
284 typename elfcpp::Elf_types<size>::Elf_Addr address)
286 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
287 Valtype* wv = reinterpret_cast<Valtype*>(view);
288 Valtype x = psymval->value(object, addend);
289 elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
292 typedef Relocate_functions<size, big_endian> This;
295 // Do a simple 8-bit REL relocation with the addend in the section
298 rel8(unsigned char* view, unsigned char value)
299 { This::template rel<8>(view, value); }
302 rel8(unsigned char* view,
303 const Sized_relobj<size, big_endian>* object,
304 const Symbol_value<size>* psymval)
305 { This::template rel<8>(view, object, psymval); }
307 // Do an 8-bit RELA relocation with the addend in the relocation.
309 rela8(unsigned char* view, unsigned char value, unsigned char addend)
310 { This::template rela<8>(view, value, addend); }
313 rela8(unsigned char* view,
314 const Sized_relobj<size, big_endian>* object,
315 const Symbol_value<size>* psymval,
316 unsigned char addend)
317 { This::template rela<8>(view, object, psymval, addend); }
319 // Do a simple 8-bit PC relative relocation with the addend in the
322 pcrel8(unsigned char* view, unsigned char value,
323 typename elfcpp::Elf_types<size>::Elf_Addr address)
324 { This::template pcrel<8>(view, value, address); }
327 pcrel8(unsigned char* view,
328 const Sized_relobj<size, big_endian>* object,
329 const Symbol_value<size>* psymval,
330 typename elfcpp::Elf_types<size>::Elf_Addr address)
331 { This::template pcrel<8>(view, object, psymval, address); }
333 // Do a simple 8-bit PC relative RELA relocation with the addend in
336 pcrela8(unsigned char* view, unsigned char value, unsigned char addend,
337 typename elfcpp::Elf_types<size>::Elf_Addr address)
338 { This::template pcrela<8>(view, value, addend, address); }
341 pcrela8(unsigned char* view,
342 const Sized_relobj<size, big_endian>* object,
343 const Symbol_value<size>* psymval,
344 unsigned char addend,
345 typename elfcpp::Elf_types<size>::Elf_Addr address)
346 { This::template pcrela<8>(view, object, psymval, addend, address); }
348 // Do a simple 16-bit REL relocation with the addend in the section
351 rel16(unsigned char* view, elfcpp::Elf_Half value)
352 { This::template rel<16>(view, value); }
355 rel16(unsigned char* view,
356 const Sized_relobj<size, big_endian>* object,
357 const Symbol_value<size>* psymval)
358 { This::template rel<16>(view, object, psymval); }
360 // Do an 16-bit RELA relocation with the addend in the relocation.
362 rela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend)
363 { This::template rela<16>(view, value, addend); }
366 rela16(unsigned char* view,
367 const Sized_relobj<size, big_endian>* object,
368 const Symbol_value<size>* psymval,
369 elfcpp::Elf_Half addend)
370 { This::template rela<16>(view, object, psymval, addend); }
372 // Do a simple 16-bit PC relative REL relocation with the addend in
373 // the section contents.
375 pcrel16(unsigned char* view, elfcpp::Elf_Half value,
376 typename elfcpp::Elf_types<size>::Elf_Addr address)
377 { This::template pcrel<16>(view, value, address); }
380 pcrel16(unsigned char* view,
381 const Sized_relobj<size, big_endian>* object,
382 const Symbol_value<size>* psymval,
383 typename elfcpp::Elf_types<size>::Elf_Addr address)
384 { This::template pcrel<16>(view, object, psymval, address); }
386 // Do a simple 16-bit PC relative RELA relocation with the addend in
389 pcrela16(unsigned char* view, elfcpp::Elf_Half value,
390 elfcpp::Elf_Half addend,
391 typename elfcpp::Elf_types<size>::Elf_Addr address)
392 { This::template pcrela<16>(view, value, addend, address); }
395 pcrela16(unsigned char* view,
396 const Sized_relobj<size, big_endian>* object,
397 const Symbol_value<size>* psymval,
398 elfcpp::Elf_Half addend,
399 typename elfcpp::Elf_types<size>::Elf_Addr address)
400 { This::template pcrela<16>(view, object, psymval, addend, address); }
402 // Do a simple 32-bit REL relocation with the addend in the section
405 rel32(unsigned char* view, elfcpp::Elf_Word value)
406 { This::template rel<32>(view, value); }
409 rel32(unsigned char* view,
410 const Sized_relobj<size, big_endian>* object,
411 const Symbol_value<size>* psymval)
412 { This::template rel<32>(view, object, psymval); }
414 // Do an 32-bit RELA relocation with the addend in the relocation.
416 rela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend)
417 { This::template rela<32>(view, value, addend); }
420 rela32(unsigned char* view,
421 const Sized_relobj<size, big_endian>* object,
422 const Symbol_value<size>* psymval,
423 elfcpp::Elf_Word addend)
424 { This::template rela<32>(view, object, psymval, addend); }
426 // Do a simple 32-bit PC relative REL relocation with the addend in
427 // the section contents.
429 pcrel32(unsigned char* view, elfcpp::Elf_Word value,
430 typename elfcpp::Elf_types<size>::Elf_Addr address)
431 { This::template pcrel<32>(view, value, address); }
434 pcrel32(unsigned char* view,
435 const Sized_relobj<size, big_endian>* object,
436 const Symbol_value<size>* psymval,
437 typename elfcpp::Elf_types<size>::Elf_Addr address)
438 { This::template pcrel<32>(view, object, psymval, address); }
440 // Do a simple 32-bit PC relative RELA relocation with the addend in
443 pcrela32(unsigned char* view, elfcpp::Elf_Word value,
444 elfcpp::Elf_Word addend,
445 typename elfcpp::Elf_types<size>::Elf_Addr address)
446 { This::template pcrela<32>(view, value, addend, address); }
449 pcrela32(unsigned char* view,
450 const Sized_relobj<size, big_endian>* object,
451 const Symbol_value<size>* psymval,
452 elfcpp::Elf_Word addend,
453 typename elfcpp::Elf_types<size>::Elf_Addr address)
454 { This::template pcrela<32>(view, object, psymval, addend, address); }
456 // Do a simple 64-bit REL relocation with the addend in the section
459 rel64(unsigned char* view, elfcpp::Elf_Xword value)
460 { This::template rel<64>(view, value); }
463 rel64(unsigned char* view,
464 const Sized_relobj<size, big_endian>* object,
465 const Symbol_value<size>* psymval)
466 { This::template rel<64>(view, object, psymval); }
468 // Do a 64-bit RELA relocation with the addend in the relocation.
470 rela64(unsigned char* view, elfcpp::Elf_Xword value,
471 elfcpp::Elf_Xword addend)
472 { This::template rela<64>(view, value, addend); }
475 rela64(unsigned char* view,
476 const Sized_relobj<size, big_endian>* object,
477 const Symbol_value<size>* psymval,
478 elfcpp::Elf_Xword addend)
479 { This::template rela<64>(view, object, psymval, addend); }
481 // Do a simple 64-bit PC relative REL relocation with the addend in
482 // the section contents.
484 pcrel64(unsigned char* view, elfcpp::Elf_Xword value,
485 typename elfcpp::Elf_types<size>::Elf_Addr address)
486 { This::template pcrel<64>(view, value, address); }
489 pcrel64(unsigned char* view,
490 const Sized_relobj<size, big_endian>* object,
491 const Symbol_value<size>* psymval,
492 typename elfcpp::Elf_types<size>::Elf_Addr address)
493 { This::template pcrel<64>(view, object, psymval, address); }
495 // Do a simple 64-bit PC relative RELA relocation with the addend in
498 pcrela64(unsigned char* view, elfcpp::Elf_Xword value,
499 elfcpp::Elf_Xword addend,
500 typename elfcpp::Elf_types<size>::Elf_Addr address)
501 { This::template pcrela<64>(view, value, addend, address); }
504 pcrela64(unsigned char* view,
505 const Sized_relobj<size, big_endian>* object,
506 const Symbol_value<size>* psymval,
507 elfcpp::Elf_Xword addend,
508 typename elfcpp::Elf_types<size>::Elf_Addr address)
509 { This::template pcrela<64>(view, object, psymval, addend, address); }
512 // We try to avoid COPY relocations when possible. A COPY relocation
513 // may be required when an executable refers to a variable defined in
514 // a shared library. COPY relocations are problematic because they
515 // tie the executable to the exact size of the variable in the shared
516 // library. We can avoid them if all the references to the variable
517 // are in a writeable section. In that case we can simply use dynamic
518 // relocations. However, when scanning relocs, we don't know when we
519 // see the relocation whether we will be forced to use a COPY
520 // relocation or not. So we have to save the relocation during the
521 // reloc scanning, and then emit it as a dynamic relocation if
522 // necessary. This class implements that. It is used by the target
525 template<int size, bool big_endian>
533 // Return whether we need a COPY reloc for a reloc against GSYM,
534 // which is being applied to section SHNDX in OBJECT.
536 need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx,
537 Sized_symbol<size>* gsym);
539 // Save a Rel against SYM for possible emission later. SHNDX is the
540 // index of the section to which the reloc is being applied.
542 save(Symbol* sym, Relobj*, unsigned int shndx,
543 Output_section* output_section, const elfcpp::Rel<size, big_endian>&);
545 // Save a Rela against SYM for possible emission later.
547 save(Symbol* sym, Relobj*, unsigned int shndx,
548 Output_section* output_section, const elfcpp::Rela<size, big_endian>&);
550 // Return whether there are any relocs to emit. This also discards
551 // entries which need not be emitted.
555 // Emit relocs for each symbol which did not get a COPY reloc (i.e.,
556 // is still defined in the dynamic object).
557 template<int sh_type>
559 emit(Output_data_reloc<sh_type, true, size, big_endian>*);
562 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
563 typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
565 // This POD class holds the entries we are saving.
566 class Copy_reloc_entry
569 Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
570 Relobj* relobj, unsigned int shndx,
571 Output_section* output_section,
572 Address address, Addend addend)
573 : sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
574 shndx_(shndx), output_section_(output_section),
575 address_(address), addend_(addend)
578 // Return whether we should emit this reloc. If we should not
579 // emit, we clear it.
586 emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*);
589 emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*);
593 unsigned int reloc_type_;
596 Output_section* output_section_;
601 // A list of relocs to be saved.
602 typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
604 // The list of relocs we are saving.
605 Copy_reloc_entries entries_;
608 // Track relocations while reading a section. This lets you ask for
609 // the relocation at a certain offset, and see how relocs occur
610 // between points of interest.
612 template<int size, bool big_endian>
617 : prelocs_(NULL), len_(0), pos_(0), reloc_size_(0)
620 // Initialize the Track_relocs object. OBJECT is the object holding
621 // the reloc section, RELOC_SHNDX is the section index of the reloc
622 // section, and RELOC_TYPE is the type of the reloc section
623 // (elfcpp::SHT_REL or elfcpp::SHT_RELA). This returns false if
624 // something went wrong.
626 initialize(Object* object, unsigned int reloc_shndx,
627 unsigned int reloc_type);
629 // Return the offset in the data section to which the next reloc
630 // applies. THis returns -1 if there is no next reloc.
634 // Return the symbol index of the next reloc. This returns -1U if
635 // there is no next reloc.
639 // Advance to OFFSET within the data section, and return the number
640 // of relocs which would be skipped.
642 advance(off_t offset);
645 // The contents of the input object's reloc section.
646 const unsigned char* prelocs_;
647 // The length of the reloc section.
649 // Our current position in the reloc section.
651 // The size of the relocs in the section.
655 } // End namespace gold.
657 #endif // !defined(GOLD_RELOC_H)