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.
28 #include "workqueue.h"
33 class General_options;
35 class Read_relocs_data;
42 template<int size, bool big_endian>
48 template<int sh_type, bool dynamic, int size, bool big_endian>
49 class Output_data_reloc;
51 // A class to read the relocations for an object file, and then queue
52 // up a task to see if they require any GOT/PLT/COPY relocations in
55 class Read_relocs : public Task
58 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
59 // unblocked when the Scan_relocs task completes.
60 Read_relocs(const General_options& options, Symbol_table* symtab,
61 Layout* layout, Relobj* object, Task_token* symtab_lock,
63 : options_(options), symtab_(symtab), layout_(layout), object_(object),
64 symtab_lock_(symtab_lock), blocker_(blocker)
67 // The standard Task methods.
70 is_runnable(Workqueue*);
79 const General_options& options_;
80 Symbol_table* symtab_;
83 Task_token* symtab_lock_;
87 // Scan the relocations for an object to see if they require any
88 // GOT/PLT/COPY relocations.
90 class Scan_relocs : public Task
93 // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
94 // unblocked when the task completes.
95 Scan_relocs(const General_options& options, Symbol_table* symtab,
96 Layout* layout, Relobj* object, Read_relocs_data* rd,
97 Task_token* symtab_lock, Task_token* blocker)
98 : options_(options), symtab_(symtab), layout_(layout), object_(object),
99 rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
102 // The standard Task methods.
105 is_runnable(Workqueue*);
114 class Scan_relocs_locker;
116 const General_options& options_;
117 Symbol_table* symtab_;
120 Read_relocs_data* rd_;
121 Task_token* symtab_lock_;
122 Task_token* blocker_;
125 // A class to perform all the relocations for an object file.
127 class Relocate_task : public Task
130 Relocate_task(const General_options& options, const Symbol_table* symtab,
131 const Layout* layout, Relobj* object, Output_file* of,
132 Task_token* input_sections_blocker,
133 Task_token* output_sections_blocker, Task_token* final_blocker)
134 : options_(options), symtab_(symtab), layout_(layout), object_(object),
135 of_(of), input_sections_blocker_(input_sections_blocker),
136 output_sections_blocker_(output_sections_blocker),
137 final_blocker_(final_blocker)
140 // The standard Task methods.
143 is_runnable(Workqueue*);
152 class Relocate_locker;
154 const General_options& options_;
155 const Symbol_table* symtab_;
156 const Layout* layout_;
159 Task_token* input_sections_blocker_;
160 Task_token* output_sections_blocker_;
161 Task_token* final_blocker_;
164 // Standard relocation routines which are used on many targets. Here
165 // SIZE and BIG_ENDIAN refer to the target, not the relocation type.
167 template<int size, bool big_endian>
168 class Relocate_functions
171 // Do a simple relocation with the addend in the section contents.
172 // VALSIZE is the size of the value.
173 template<int valsize>
175 rel(unsigned char* view,
176 typename elfcpp::Swap<valsize, big_endian>::Valtype value)
178 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
179 Valtype* wv = reinterpret_cast<Valtype*>(view);
180 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
181 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value);
184 // Do a simple relocation using a Symbol_value with the addend in
185 // the section contents. VALSIZE is the size of the value to
187 template<int valsize>
189 rel(unsigned char* view,
190 const Sized_relobj<size, big_endian>* object,
191 const Symbol_value<size>* psymval)
193 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
194 Valtype* wv = reinterpret_cast<Valtype*>(view);
195 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
196 x = psymval->value(object, x);
197 elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
200 // Do a simple relocation with the addend in the relocation.
201 // VALSIZE is the size of the value.
202 template<int valsize>
204 rela(unsigned char* view,
205 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
206 typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
208 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
209 Valtype* wv = reinterpret_cast<Valtype*>(view);
210 elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend);
213 // Do a simple relocation using a symbol value with the addend in
214 // the relocation. VALSIZE is the size of the value.
215 template<int valsize>
217 rela(unsigned char* view,
218 const Sized_relobj<size, big_endian>* object,
219 const Symbol_value<size>* psymval,
220 typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
222 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
223 Valtype* wv = reinterpret_cast<Valtype*>(view);
224 Valtype x = psymval->value(object, addend);
225 elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
228 // Do a simple PC relative relocation with the addend in the section
229 // contents. VALSIZE is the size of the value.
230 template<int valsize>
232 pcrel(unsigned char* view,
233 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
234 typename elfcpp::Elf_types<size>::Elf_Addr address)
236 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
237 Valtype* wv = reinterpret_cast<Valtype*>(view);
238 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
239 elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address);
242 // Do a simple PC relative relocation with a Symbol_value with the
243 // addend in the section contents. VALSIZE is the size of the
245 template<int valsize>
247 pcrel(unsigned char* view,
248 const Sized_relobj<size, big_endian>* object,
249 const Symbol_value<size>* psymval,
250 typename elfcpp::Elf_types<size>::Elf_Addr address)
252 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
253 Valtype* wv = reinterpret_cast<Valtype*>(view);
254 Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
255 x = psymval->value(object, x);
256 elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
259 // Do a simple PC relative relocation with the addend in the
260 // relocation. VALSIZE is the size of the value.
261 template<int valsize>
263 pcrela(unsigned char* view,
264 typename elfcpp::Swap<valsize, big_endian>::Valtype value,
265 typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
266 typename elfcpp::Elf_types<size>::Elf_Addr address)
268 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
269 Valtype* wv = reinterpret_cast<Valtype*>(view);
270 elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend - address);
273 // Do a simple PC relative relocation with a Symbol_value with the
274 // addend in the relocation. VALSIZE is the size of the value.
275 template<int valsize>
277 pcrela(unsigned char* view,
278 const Sized_relobj<size, big_endian>* object,
279 const Symbol_value<size>* psymval,
280 typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
281 typename elfcpp::Elf_types<size>::Elf_Addr address)
283 typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
284 Valtype* wv = reinterpret_cast<Valtype*>(view);
285 Valtype x = psymval->value(object, addend);
286 elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
289 typedef Relocate_functions<size, big_endian> This;
292 // Do a simple 8-bit REL relocation with the addend in the section
295 rel8(unsigned char* view, unsigned char value)
296 { This::template rel<8>(view, value); }
299 rel8(unsigned char* view,
300 const Sized_relobj<size, big_endian>* object,
301 const Symbol_value<size>* psymval)
302 { This::template rel<8>(view, object, psymval); }
304 // Do an 8-bit RELA relocation with the addend in the relocation.
306 rela8(unsigned char* view, unsigned char value, unsigned char addend)
307 { This::template rela<8>(view, value, addend); }
310 rela8(unsigned char* view,
311 const Sized_relobj<size, big_endian>* object,
312 const Symbol_value<size>* psymval,
313 unsigned char addend)
314 { This::template rela<8>(view, object, psymval, addend); }
316 // Do a simple 8-bit PC relative relocation with the addend in the
319 pcrel8(unsigned char* view, unsigned char value,
320 typename elfcpp::Elf_types<size>::Elf_Addr address)
321 { This::template pcrel<8>(view, value, address); }
324 pcrel8(unsigned char* view,
325 const Sized_relobj<size, big_endian>* object,
326 const Symbol_value<size>* psymval,
327 typename elfcpp::Elf_types<size>::Elf_Addr address)
328 { This::template pcrel<8>(view, object, psymval, address); }
330 // Do a simple 8-bit PC relative RELA relocation with the addend in
333 pcrela8(unsigned char* view, unsigned char value, unsigned char addend,
334 typename elfcpp::Elf_types<size>::Elf_Addr address)
335 { This::template pcrela<8>(view, value, addend, address); }
338 pcrela8(unsigned char* view,
339 const Sized_relobj<size, big_endian>* object,
340 const Symbol_value<size>* psymval,
341 unsigned char addend,
342 typename elfcpp::Elf_types<size>::Elf_Addr address)
343 { This::template pcrela<8>(view, object, psymval, addend, address); }
345 // Do a simple 16-bit REL relocation with the addend in the section
348 rel16(unsigned char* view, elfcpp::Elf_Half value)
349 { This::template rel<16>(view, value); }
352 rel16(unsigned char* view,
353 const Sized_relobj<size, big_endian>* object,
354 const Symbol_value<size>* psymval)
355 { This::template rel<16>(view, object, psymval); }
357 // Do an 16-bit RELA relocation with the addend in the relocation.
359 rela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend)
360 { This::template rela<16>(view, value, addend); }
363 rela16(unsigned char* view,
364 const Sized_relobj<size, big_endian>* object,
365 const Symbol_value<size>* psymval,
366 elfcpp::Elf_Half addend)
367 { This::template rela<16>(view, object, psymval, addend); }
369 // Do a simple 16-bit PC relative REL relocation with the addend in
370 // the section contents.
372 pcrel16(unsigned char* view, elfcpp::Elf_Half value,
373 typename elfcpp::Elf_types<size>::Elf_Addr address)
374 { This::template pcrel<16>(view, value, address); }
377 pcrel16(unsigned char* view,
378 const Sized_relobj<size, big_endian>* object,
379 const Symbol_value<size>* psymval,
380 typename elfcpp::Elf_types<size>::Elf_Addr address)
381 { This::template pcrel<16>(view, object, psymval, address); }
383 // Do a simple 16-bit PC relative RELA relocation with the addend in
386 pcrela16(unsigned char* view, elfcpp::Elf_Half value,
387 elfcpp::Elf_Half addend,
388 typename elfcpp::Elf_types<size>::Elf_Addr address)
389 { This::template pcrela<16>(view, value, addend, address); }
392 pcrela16(unsigned char* view,
393 const Sized_relobj<size, big_endian>* object,
394 const Symbol_value<size>* psymval,
395 elfcpp::Elf_Half addend,
396 typename elfcpp::Elf_types<size>::Elf_Addr address)
397 { This::template pcrela<16>(view, object, psymval, addend, address); }
399 // Do a simple 32-bit REL relocation with the addend in the section
402 rel32(unsigned char* view, elfcpp::Elf_Word value)
403 { This::template rel<32>(view, value); }
406 rel32(unsigned char* view,
407 const Sized_relobj<size, big_endian>* object,
408 const Symbol_value<size>* psymval)
409 { This::template rel<32>(view, object, psymval); }
411 // Do an 32-bit RELA relocation with the addend in the relocation.
413 rela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend)
414 { This::template rela<32>(view, value, addend); }
417 rela32(unsigned char* view,
418 const Sized_relobj<size, big_endian>* object,
419 const Symbol_value<size>* psymval,
420 elfcpp::Elf_Word addend)
421 { This::template rela<32>(view, object, psymval, addend); }
423 // Do a simple 32-bit PC relative REL relocation with the addend in
424 // the section contents.
426 pcrel32(unsigned char* view, elfcpp::Elf_Word value,
427 typename elfcpp::Elf_types<size>::Elf_Addr address)
428 { This::template pcrel<32>(view, value, address); }
431 pcrel32(unsigned char* view,
432 const Sized_relobj<size, big_endian>* object,
433 const Symbol_value<size>* psymval,
434 typename elfcpp::Elf_types<size>::Elf_Addr address)
435 { This::template pcrel<32>(view, object, psymval, address); }
437 // Do a simple 32-bit PC relative RELA relocation with the addend in
440 pcrela32(unsigned char* view, elfcpp::Elf_Word value,
441 elfcpp::Elf_Word addend,
442 typename elfcpp::Elf_types<size>::Elf_Addr address)
443 { This::template pcrela<32>(view, value, addend, address); }
446 pcrela32(unsigned char* view,
447 const Sized_relobj<size, big_endian>* object,
448 const Symbol_value<size>* psymval,
449 elfcpp::Elf_Word addend,
450 typename elfcpp::Elf_types<size>::Elf_Addr address)
451 { This::template pcrela<32>(view, object, psymval, addend, address); }
453 // Do a simple 64-bit REL relocation with the addend in the section
456 rel64(unsigned char* view, elfcpp::Elf_Xword value)
457 { This::template rel<64>(view, value); }
460 rel64(unsigned char* view,
461 const Sized_relobj<size, big_endian>* object,
462 const Symbol_value<size>* psymval)
463 { This::template rel<64>(view, object, psymval); }
465 // Do a 64-bit RELA relocation with the addend in the relocation.
467 rela64(unsigned char* view, elfcpp::Elf_Xword value,
468 elfcpp::Elf_Xword addend)
469 { This::template rela<64>(view, value, addend); }
472 rela64(unsigned char* view,
473 const Sized_relobj<size, big_endian>* object,
474 const Symbol_value<size>* psymval,
475 elfcpp::Elf_Xword addend)
476 { This::template rela<64>(view, object, psymval, addend); }
478 // Do a simple 64-bit PC relative REL relocation with the addend in
479 // the section contents.
481 pcrel64(unsigned char* view, elfcpp::Elf_Xword value,
482 typename elfcpp::Elf_types<size>::Elf_Addr address)
483 { This::template pcrel<64>(view, value, address); }
486 pcrel64(unsigned char* view,
487 const Sized_relobj<size, big_endian>* object,
488 const Symbol_value<size>* psymval,
489 typename elfcpp::Elf_types<size>::Elf_Addr address)
490 { This::template pcrel<64>(view, object, psymval, address); }
492 // Do a simple 64-bit PC relative RELA relocation with the addend in
495 pcrela64(unsigned char* view, elfcpp::Elf_Xword value,
496 elfcpp::Elf_Xword addend,
497 typename elfcpp::Elf_types<size>::Elf_Addr address)
498 { This::template pcrela<64>(view, value, addend, address); }
501 pcrela64(unsigned char* view,
502 const Sized_relobj<size, big_endian>* object,
503 const Symbol_value<size>* psymval,
504 elfcpp::Elf_Xword addend,
505 typename elfcpp::Elf_types<size>::Elf_Addr address)
506 { This::template pcrela<64>(view, object, psymval, addend, address); }
509 // We try to avoid COPY relocations when possible. A COPY relocation
510 // may be required when an executable refers to a variable defined in
511 // a shared library. COPY relocations are problematic because they
512 // tie the executable to the exact size of the variable in the shared
513 // library. We can avoid them if all the references to the variable
514 // are in a writeable section. In that case we can simply use dynamic
515 // relocations. However, when scanning relocs, we don't know when we
516 // see the relocation whether we will be forced to use a COPY
517 // relocation or not. So we have to save the relocation during the
518 // reloc scanning, and then emit it as a dynamic relocation if
519 // necessary. This class implements that. It is used by the target
522 template<int size, bool big_endian>
530 // Return whether we need a COPY reloc for a reloc against GSYM,
531 // which is being applied to section SHNDX in OBJECT.
533 need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx,
534 Sized_symbol<size>* gsym);
536 // Save a Rel against SYM for possible emission later. SHNDX is the
537 // index of the section to which the reloc is being applied.
539 save(Symbol* sym, Relobj*, unsigned int shndx,
540 const elfcpp::Rel<size, big_endian>&);
542 // Save a Rela against SYM for possible emission later.
544 save(Symbol* sym, Relobj*, unsigned int shndx,
545 const elfcpp::Rela<size, big_endian>&);
547 // Return whether there are any relocs to emit. This also discards
548 // entries which need not be emitted.
552 // Emit relocs for each symbol which did not get a COPY reloc (i.e.,
553 // is still defined in the dynamic object).
554 template<int sh_type>
556 emit(Output_data_reloc<sh_type, true, size, big_endian>*);
559 typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
560 typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
562 // This POD class holds the entries we are saving.
563 class Copy_reloc_entry
566 Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
567 Relobj* relobj, unsigned int shndx,
568 Address address, Addend addend)
569 : sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
570 shndx_(shndx), address_(address), addend_(addend)
573 // Return whether we should emit this reloc. If we should not
574 // emit, we clear it.
581 emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*);
584 emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*);
588 unsigned int reloc_type_;
595 // A list of relocs to be saved.
596 typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
598 // The list of relocs we are saving.
599 Copy_reloc_entries entries_;
602 // Track relocations while reading a section. This lets you ask for
603 // the relocation at a certain offset, and see how relocs occur
604 // between points of interest.
606 template<int size, bool big_endian>
611 : object_(NULL), prelocs_(NULL), len_(0), pos_(0), reloc_size_(0)
614 // Initialize the Track_relocs object. OBJECT is the object holding
615 // the reloc section, RELOC_SHNDX is the section index of the reloc
616 // section, and RELOC_TYPE is the type of the reloc section
617 // (elfcpp::SHT_REL or elfcpp::SHT_RELA). This returns false if
618 // something went wrong.
620 initialize(Sized_relobj<size, big_endian>* object, unsigned int reloc_shndx,
621 unsigned int reloc_type);
623 // Return the offset in the data section to which the next reloc
624 // applies. THis returns -1 if there is no next reloc.
628 // Return the symbol index of the next reloc. This returns -1U if
629 // there is no next reloc.
633 // Advance to OFFSET within the data section, and return the number
634 // of relocs which would be skipped.
636 advance(off_t offset);
640 Sized_relobj<size, big_endian>* object_;
641 // The contents of the 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)