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;
44 template<int size, bool big_endian>
50 template<int sh_type, bool dynamic, int size, bool big_endian>
51 class Output_data_reloc;
53 // A class to read the relocations for an object file, and then queue
54 // up a task to see if they require any GOT/PLT/COPY relocations in
57 class Read_relocs : public Task
60 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
61 // unblocked when the Scan_relocs task completes.
62 Read_relocs(const General_options& options, Symbol_table* symtab,
63 Layout* layout, Relobj* object, Task_token* symtab_lock,
65 : options_(options), symtab_(symtab), layout_(layout), object_(object),
66 symtab_lock_(symtab_lock), blocker_(blocker)
69 // The standard Task methods.
72 is_runnable(Workqueue*);
81 const General_options& options_;
82 Symbol_table* symtab_;
85 Task_token* symtab_lock_;
89 // Scan the relocations for an object to see if they require any
90 // GOT/PLT/COPY relocations.
92 class Scan_relocs : public Task
95 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
96 // unblocked when the task completes.
97 Scan_relocs(const General_options& options, Symbol_table* symtab,
98 Layout* layout, Relobj* object, Read_relocs_data* rd,
99 Task_token* symtab_lock, Task_token* blocker)
100 : options_(options), symtab_(symtab), layout_(layout), object_(object),
101 rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
104 // The standard Task methods.
107 is_runnable(Workqueue*);
116 class Scan_relocs_locker;
118 const General_options& options_;
119 Symbol_table* symtab_;
122 Read_relocs_data* rd_;
123 Task_token* symtab_lock_;
124 Task_token* blocker_;
127 // A class to perform all the relocations for an object file.
129 class Relocate_task : public Task
132 Relocate_task(const General_options& options, const Symbol_table* symtab,
133 const Layout* layout, Relobj* object, Output_file* of,
134 Task_token* input_sections_blocker,
135 Task_token* output_sections_blocker, Task_token* final_blocker)
136 : options_(options), symtab_(symtab), layout_(layout), object_(object),
137 of_(of), input_sections_blocker_(input_sections_blocker),
138 output_sections_blocker_(output_sections_blocker),
139 final_blocker_(final_blocker)
142 // The standard Task methods.
145 is_runnable(Workqueue*);
154 class Relocate_locker;
156 const General_options& options_;
157 const Symbol_table* symtab_;
158 const Layout* layout_;
161 Task_token* input_sections_blocker_;
162 Task_token* output_sections_blocker_;
163 Task_token* final_blocker_;
166 // Standard relocation routines which are used on many targets. Here
167 // SIZE and BIG_ENDIAN refer to the target, not the relocation type.
169 template<int size, bool big_endian>
170 class Relocate_functions
173 // Do a simple relocation with the addend in the section contents.
174 // VALSIZE is the size of the value.
175 template<int valsize>
177 rel(unsigned char* view,
178 typename elfcpp::Swap<valsize, big_endian>::Valtype value)
180 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
181 Valtype* wv = reinterpret_cast<Valtype*>(view);
182 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
183 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value);
186 // Do a simple relocation using a Symbol_value with the addend in
187 // the section contents. VALSIZE is the size of the value to
189 template<int valsize>
191 rel(unsigned char* view,
192 const Sized_relobj<size, big_endian>* object,
193 const Symbol_value<size>* psymval)
195 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
196 Valtype* wv = reinterpret_cast<Valtype*>(view);
197 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
198 x = psymval->value(object, x);
199 elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
202 // Do a simple relocation with the addend in the relocation.
203 // VALSIZE is the size of the value.
204 template<int valsize>
206 rela(unsigned char* view,
207 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
208 typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
210 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
211 Valtype* wv = reinterpret_cast<Valtype*>(view);
212 elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend);
215 // Do a simple relocation using a symbol value with the addend in
216 // the relocation. VALSIZE is the size of the value.
217 template<int valsize>
219 rela(unsigned char* view,
220 const Sized_relobj<size, big_endian>* object,
221 const Symbol_value<size>* psymval,
222 typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
224 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
225 Valtype* wv = reinterpret_cast<Valtype*>(view);
226 Valtype x = psymval->value(object, addend);
227 elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
230 // Do a simple PC relative relocation with the addend in the section
231 // contents. VALSIZE is the size of the value.
232 template<int valsize>
234 pcrel(unsigned char* view,
235 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
236 typename elfcpp::Elf_types<size>::Elf_Addr address)
238 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
239 Valtype* wv = reinterpret_cast<Valtype*>(view);
240 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
241 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address);
244 // Do a simple PC relative relocation with a Symbol_value with the
245 // addend in the section contents. VALSIZE is the size of the
247 template<int valsize>
249 pcrel(unsigned char* view,
250 const Sized_relobj<size, big_endian>* object,
251 const Symbol_value<size>* psymval,
252 typename elfcpp::Elf_types<size>::Elf_Addr address)
254 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
255 Valtype* wv = reinterpret_cast<Valtype*>(view);
256 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
257 x = psymval->value(object, x);
258 elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
261 // Do a simple PC relative relocation with the addend in the
262 // relocation. VALSIZE is the size of the value.
263 template<int valsize>
265 pcrela(unsigned char* view,
266 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
267 typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
268 typename elfcpp::Elf_types<size>::Elf_Addr address)
270 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
271 Valtype* wv = reinterpret_cast<Valtype*>(view);
272 elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend - address);
275 // Do a simple PC relative relocation with a Symbol_value with the
276 // addend in the relocation. VALSIZE is the size of the value.
277 template<int valsize>
279 pcrela(unsigned char* view,
280 const Sized_relobj<size, big_endian>* object,
281 const Symbol_value<size>* psymval,
282 typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
283 typename elfcpp::Elf_types<size>::Elf_Addr address)
285 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
286 Valtype* wv = reinterpret_cast<Valtype*>(view);
287 Valtype x = psymval->value(object, addend);
288 elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
291 typedef Relocate_functions<size, big_endian> This;
294 // Do a simple 8-bit REL relocation with the addend in the section
297 rel8(unsigned char* view, unsigned char value)
298 { This::template rel<8>(view, value); }
301 rel8(unsigned char* view,
302 const Sized_relobj<size, big_endian>* object,
303 const Symbol_value<size>* psymval)
304 { This::template rel<8>(view, object, psymval); }
306 // Do an 8-bit RELA relocation with the addend in the relocation.
308 rela8(unsigned char* view, unsigned char value, unsigned char addend)
309 { This::template rela<8>(view, value, addend); }
312 rela8(unsigned char* view,
313 const Sized_relobj<size, big_endian>* object,
314 const Symbol_value<size>* psymval,
315 unsigned char addend)
316 { This::template rela<8>(view, object, psymval, addend); }
318 // Do a simple 8-bit PC relative relocation with the addend in the
321 pcrel8(unsigned char* view, unsigned char value,
322 typename elfcpp::Elf_types<size>::Elf_Addr address)
323 { This::template pcrel<8>(view, value, address); }
326 pcrel8(unsigned char* view,
327 const Sized_relobj<size, big_endian>* object,
328 const Symbol_value<size>* psymval,
329 typename elfcpp::Elf_types<size>::Elf_Addr address)
330 { This::template pcrel<8>(view, object, psymval, address); }
332 // Do a simple 8-bit PC relative RELA relocation with the addend in
335 pcrela8(unsigned char* view, unsigned char value, unsigned char addend,
336 typename elfcpp::Elf_types<size>::Elf_Addr address)
337 { This::template pcrela<8>(view, value, addend, address); }
340 pcrela8(unsigned char* view,
341 const Sized_relobj<size, big_endian>* object,
342 const Symbol_value<size>* psymval,
343 unsigned char addend,
344 typename elfcpp::Elf_types<size>::Elf_Addr address)
345 { This::template pcrela<8>(view, object, psymval, addend, address); }
347 // Do a simple 16-bit REL relocation with the addend in the section
350 rel16(unsigned char* view, elfcpp::Elf_Half value)
351 { This::template rel<16>(view, value); }
354 rel16(unsigned char* view,
355 const Sized_relobj<size, big_endian>* object,
356 const Symbol_value<size>* psymval)
357 { This::template rel<16>(view, object, psymval); }
359 // Do an 16-bit RELA relocation with the addend in the relocation.
361 rela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend)
362 { This::template rela<16>(view, value, addend); }
365 rela16(unsigned char* view,
366 const Sized_relobj<size, big_endian>* object,
367 const Symbol_value<size>* psymval,
368 elfcpp::Elf_Half addend)
369 { This::template rela<16>(view, object, psymval, addend); }
371 // Do a simple 16-bit PC relative REL relocation with the addend in
372 // the section contents.
374 pcrel16(unsigned char* view, elfcpp::Elf_Half value,
375 typename elfcpp::Elf_types<size>::Elf_Addr address)
376 { This::template pcrel<16>(view, value, address); }
379 pcrel16(unsigned char* view,
380 const Sized_relobj<size, big_endian>* object,
381 const Symbol_value<size>* psymval,
382 typename elfcpp::Elf_types<size>::Elf_Addr address)
383 { This::template pcrel<16>(view, object, psymval, address); }
385 // Do a simple 16-bit PC relative RELA relocation with the addend in
388 pcrela16(unsigned char* view, elfcpp::Elf_Half value,
389 elfcpp::Elf_Half addend,
390 typename elfcpp::Elf_types<size>::Elf_Addr address)
391 { This::template pcrela<16>(view, value, addend, address); }
394 pcrela16(unsigned char* view,
395 const Sized_relobj<size, big_endian>* object,
396 const Symbol_value<size>* psymval,
397 elfcpp::Elf_Half addend,
398 typename elfcpp::Elf_types<size>::Elf_Addr address)
399 { This::template pcrela<16>(view, object, psymval, addend, address); }
401 // Do a simple 32-bit REL relocation with the addend in the section
404 rel32(unsigned char* view, elfcpp::Elf_Word value)
405 { This::template rel<32>(view, value); }
408 rel32(unsigned char* view,
409 const Sized_relobj<size, big_endian>* object,
410 const Symbol_value<size>* psymval)
411 { This::template rel<32>(view, object, psymval); }
413 // Do an 32-bit RELA relocation with the addend in the relocation.
415 rela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend)
416 { This::template rela<32>(view, value, addend); }
419 rela32(unsigned char* view,
420 const Sized_relobj<size, big_endian>* object,
421 const Symbol_value<size>* psymval,
422 elfcpp::Elf_Word addend)
423 { This::template rela<32>(view, object, psymval, addend); }
425 // Do a simple 32-bit PC relative REL relocation with the addend in
426 // the section contents.
428 pcrel32(unsigned char* view, elfcpp::Elf_Word value,
429 typename elfcpp::Elf_types<size>::Elf_Addr address)
430 { This::template pcrel<32>(view, value, address); }
433 pcrel32(unsigned char* view,
434 const Sized_relobj<size, big_endian>* object,
435 const Symbol_value<size>* psymval,
436 typename elfcpp::Elf_types<size>::Elf_Addr address)
437 { This::template pcrel<32>(view, object, psymval, address); }
439 // Do a simple 32-bit PC relative RELA relocation with the addend in
442 pcrela32(unsigned char* view, elfcpp::Elf_Word value,
443 elfcpp::Elf_Word addend,
444 typename elfcpp::Elf_types<size>::Elf_Addr address)
445 { This::template pcrela<32>(view, value, addend, address); }
448 pcrela32(unsigned char* view,
449 const Sized_relobj<size, big_endian>* object,
450 const Symbol_value<size>* psymval,
451 elfcpp::Elf_Word addend,
452 typename elfcpp::Elf_types<size>::Elf_Addr address)
453 { This::template pcrela<32>(view, object, psymval, addend, address); }
455 // Do a simple 64-bit REL relocation with the addend in the section
458 rel64(unsigned char* view, elfcpp::Elf_Xword value)
459 { This::template rel<64>(view, value); }
462 rel64(unsigned char* view,
463 const Sized_relobj<size, big_endian>* object,
464 const Symbol_value<size>* psymval)
465 { This::template rel<64>(view, object, psymval); }
467 // Do a 64-bit RELA relocation with the addend in the relocation.
469 rela64(unsigned char* view, elfcpp::Elf_Xword value,
470 elfcpp::Elf_Xword addend)
471 { This::template rela<64>(view, value, addend); }
474 rela64(unsigned char* view,
475 const Sized_relobj<size, big_endian>* object,
476 const Symbol_value<size>* psymval,
477 elfcpp::Elf_Xword addend)
478 { This::template rela<64>(view, object, psymval, addend); }
480 // Do a simple 64-bit PC relative REL relocation with the addend in
481 // the section contents.
483 pcrel64(unsigned char* view, elfcpp::Elf_Xword value,
484 typename elfcpp::Elf_types<size>::Elf_Addr address)
485 { This::template pcrel<64>(view, value, address); }
488 pcrel64(unsigned char* view,
489 const Sized_relobj<size, big_endian>* object,
490 const Symbol_value<size>* psymval,
491 typename elfcpp::Elf_types<size>::Elf_Addr address)
492 { This::template pcrel<64>(view, object, psymval, address); }
494 // Do a simple 64-bit PC relative RELA relocation with the addend in
497 pcrela64(unsigned char* view, elfcpp::Elf_Xword value,
498 elfcpp::Elf_Xword addend,
499 typename elfcpp::Elf_types<size>::Elf_Addr address)
500 { This::template pcrela<64>(view, value, addend, address); }
503 pcrela64(unsigned char* view,
504 const Sized_relobj<size, big_endian>* object,
505 const Symbol_value<size>* psymval,
506 elfcpp::Elf_Xword addend,
507 typename elfcpp::Elf_types<size>::Elf_Addr address)
508 { This::template pcrela<64>(view, object, psymval, addend, address); }
511 // We try to avoid COPY relocations when possible. A COPY relocation
512 // may be required when an executable refers to a variable defined in
513 // a shared library. COPY relocations are problematic because they
514 // tie the executable to the exact size of the variable in the shared
515 // library. We can avoid them if all the references to the variable
516 // are in a writeable section. In that case we can simply use dynamic
517 // relocations. However, when scanning relocs, we don't know when we
518 // see the relocation whether we will be forced to use a COPY
519 // relocation or not. So we have to save the relocation during the
520 // reloc scanning, and then emit it as a dynamic relocation if
521 // necessary. This class implements that. It is used by the target
524 template<int size, bool big_endian>
532 // Return whether we need a COPY reloc for a reloc against GSYM,
533 // which is being applied to section SHNDX in OBJECT.
535 need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx,
536 Sized_symbol<size>* gsym);
538 // Save a Rel against SYM for possible emission later. SHNDX is the
539 // index of the section to which the reloc is being applied.
541 save(Symbol* sym, Relobj*, unsigned int shndx,
542 const elfcpp::Rel<size, big_endian>&);
544 // Save a Rela against SYM for possible emission later.
546 save(Symbol* sym, Relobj*, unsigned int shndx,
547 const elfcpp::Rela<size, big_endian>&);
549 // Return whether there are any relocs to emit. This also discards
550 // entries which need not be emitted.
554 // Emit relocs for each symbol which did not get a COPY reloc (i.e.,
555 // is still defined in the dynamic object).
556 template<int sh_type>
558 emit(Output_data_reloc<sh_type, true, size, big_endian>*);
561 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
562 typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
564 // This POD class holds the entries we are saving.
565 class Copy_reloc_entry
568 Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
569 Relobj* relobj, unsigned int shndx,
570 Address address, Addend addend)
571 : sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
572 shndx_(shndx), address_(address), addend_(addend)
575 // Return whether we should emit this reloc. If we should not
576 // emit, we clear it.
583 emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*);
586 emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*);
590 unsigned int reloc_type_;
597 // A list of relocs to be saved.
598 typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
600 // The list of relocs we are saving.
601 Copy_reloc_entries entries_;
604 // Track relocations while reading a section. This lets you ask for
605 // the relocation at a certain offset, and see how relocs occur
606 // between points of interest.
608 template<int size, bool big_endian>
613 : prelocs_(NULL), len_(0), pos_(0), reloc_size_(0)
616 // Initialize the Track_relocs object. OBJECT is the object holding
617 // the reloc section, RELOC_SHNDX is the section index of the reloc
618 // section, and RELOC_TYPE is the type of the reloc section
619 // (elfcpp::SHT_REL or elfcpp::SHT_RELA). This returns false if
620 // something went wrong.
622 initialize(Object* object, unsigned int reloc_shndx,
623 unsigned int reloc_type);
625 // Return the offset in the data section to which the next reloc
626 // applies. THis returns -1 if there is no next reloc.
630 // Return the symbol index of the next reloc. This returns -1U if
631 // there is no next reloc.
635 // Advance to OFFSET within the data section, and return the number
636 // of relocs which would be skipped.
638 advance(off_t offset);
641 // The contents of the input object's reloc section.
642 const unsigned char* prelocs_;
643 // The length of the reloc section.
645 // Our current position in the reloc section.
647 // The size of the relocs in the section.
651 } // End namespace gold.
653 #endif // !defined(GOLD_RELOC_H)