* mapfile.cc (Mapfile::print_input_section): Change -1U to -1ULL.
[external/binutils.git] / gold / target-reloc.h
1 // target-reloc.h -- target specific relocation support  -*- C++ -*-
2
3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
5
6 // This file is part of gold.
7
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.
12
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.
17
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.
22
23 #ifndef GOLD_TARGET_RELOC_H
24 #define GOLD_TARGET_RELOC_H
25
26 #include "elfcpp.h"
27 #include "symtab.h"
28 #include "reloc.h"
29 #include "reloc-types.h"
30
31 namespace gold
32 {
33
34 // This function implements the generic part of reloc scanning.  The
35 // template parameter Scan must be a class type which provides two
36 // functions: local() and global().  Those functions implement the
37 // machine specific part of scanning.  We do it this way to
38 // avoidmaking a function call for each relocation, and to avoid
39 // repeating the generic code for each target.
40
41 template<int size, bool big_endian, typename Target_type, int sh_type,
42          typename Scan>
43 inline void
44 scan_relocs(
45     const General_options& options,
46     Symbol_table* symtab,
47     Layout* layout,
48     Target_type* target,
49     Sized_relobj<size, big_endian>* object,
50     unsigned int data_shndx,
51     const unsigned char* prelocs,
52     size_t reloc_count,
53     Output_section* output_section,
54     bool needs_special_offset_handling,
55     size_t local_count,
56     const unsigned char* plocal_syms)
57 {
58   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
59   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
60   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
61   Scan scan;
62
63   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
64     {
65       Reltype reloc(prelocs);
66
67       if (needs_special_offset_handling
68           && !output_section->is_input_address_mapped(object, data_shndx,
69                                                       reloc.get_r_offset()))
70         continue;
71
72       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
73       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
74       unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
75
76       if (r_sym < local_count)
77         {
78           gold_assert(plocal_syms != NULL);
79           typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
80                                                       + r_sym * sym_size);
81           unsigned int shndx = lsym.get_st_shndx();
82           bool is_ordinary;
83           shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
84           if (is_ordinary
85               && shndx != elfcpp::SHN_UNDEF
86               && !object->is_section_included(shndx))
87             {
88               // RELOC is a relocation against a local symbol in a
89               // section we are discarding.  We can ignore this
90               // relocation.  It will eventually become a reloc
91               // against the value zero.
92               //
93               // FIXME: We should issue a warning if this is an
94               // allocated section; is this the best place to do it?
95               // 
96               // FIXME: The old GNU linker would in some cases look
97               // for the linkonce section which caused this section to
98               // be discarded, and, if the other section was the same
99               // size, change the reloc to refer to the other section.
100               // That seems risky and weird to me, and I don't know of
101               // any case where it is actually required.
102
103               continue;
104             }
105
106           scan.local(options, symtab, layout, target, object, data_shndx,
107                      output_section, reloc, r_type, lsym);
108         }
109       else
110         {
111           Symbol* gsym = object->global_symbol(r_sym);
112           gold_assert(gsym != NULL);
113           if (gsym->is_forwarder())
114             gsym = symtab->resolve_forwards(gsym);
115
116           scan.global(options, symtab, layout, target, object, data_shndx,
117                       output_section, reloc, r_type, gsym);
118         }
119     }
120 }
121
122 // Behavior for relocations to discarded comdat sections.
123
124 enum Comdat_behavior
125 {
126   CB_UNDETERMINED,   // Not yet determined -- need to look at section name.
127   CB_PRETEND,        // Attempt to map to the corresponding kept section.
128   CB_IGNORE,         // Ignore the relocation.
129   CB_WARNING         // Print a warning.
130 };
131
132 // Decide what the linker should do for relocations that refer to discarded
133 // comdat sections.  This decision is based on the name of the section being
134 // relocated.
135
136 inline Comdat_behavior
137 get_comdat_behavior(const char* name)
138 {
139   if (Layout::is_debug_info_section(name))
140     return CB_PRETEND;
141   if (strcmp(name, ".eh_frame") == 0
142       || strcmp(name, ".gcc_except_table") == 0)
143     return CB_IGNORE;
144   return CB_WARNING;
145 }
146
147 // This function implements the generic part of relocation processing.
148 // The template parameter Relocate must be a class type which provides
149 // a single function, relocate(), which implements the machine
150 // specific part of a relocation.
151
152 // SIZE is the ELF size: 32 or 64.  BIG_ENDIAN is the endianness of
153 // the data.  SH_TYPE is the section type: SHT_REL or SHT_RELA.
154 // RELOCATE implements operator() to do a relocation.
155
156 // PRELOCS points to the relocation data.  RELOC_COUNT is the number
157 // of relocs.  OUTPUT_SECTION is the output section.
158 // NEEDS_SPECIAL_OFFSET_HANDLING is true if input offsets need to be
159 // mapped to output offsets.
160
161 // VIEW is the section data, VIEW_ADDRESS is its memory address, and
162 // VIEW_SIZE is the size.  These refer to the input section, unless
163 // NEEDS_SPECIAL_OFFSET_HANDLING is true, in which case they refer to
164 // the output section.
165
166 template<int size, bool big_endian, typename Target_type, int sh_type,
167          typename Relocate>
168 inline void
169 relocate_section(
170     const Relocate_info<size, big_endian>* relinfo,
171     Target_type* target,
172     const unsigned char* prelocs,
173     size_t reloc_count,
174     Output_section* output_section,
175     bool needs_special_offset_handling,
176     unsigned char* view,
177     typename elfcpp::Elf_types<size>::Elf_Addr view_address,
178     section_size_type view_size)
179 {
180   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
181   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
182   Relocate relocate;
183
184   Sized_relobj<size, big_endian>* object = relinfo->object;
185   unsigned int local_count = object->local_symbol_count();
186
187   Comdat_behavior comdat_behavior = CB_UNDETERMINED;
188
189   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
190     {
191       Reltype reloc(prelocs);
192
193       section_offset_type offset =
194         convert_to_section_size_type(reloc.get_r_offset());
195
196       if (needs_special_offset_handling)
197         {
198           offset = output_section->output_offset(relinfo->object,
199                                                  relinfo->data_shndx,
200                                                  offset);
201           if (offset == -1)
202             continue;
203         }
204
205       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
206       unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
207       unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
208
209       const Sized_symbol<size>* sym;
210
211       Symbol_value<size> symval;
212       const Symbol_value<size> *psymval;
213       if (r_sym < local_count)
214         {
215           sym = NULL;
216           psymval = object->local_symbol(r_sym);
217
218           // If the local symbol belongs to a section we are discarding,
219           // and that section is a debug section, try to find the
220           // corresponding kept section and map this symbol to its
221           // counterpart in the kept section.
222           bool is_ordinary;
223           unsigned int shndx = psymval->input_shndx(&is_ordinary);
224           if (is_ordinary
225               && shndx != elfcpp::SHN_UNDEF
226               && !object->is_section_included(shndx))
227             {
228               if (comdat_behavior == CB_UNDETERMINED)
229                 {
230                   std::string name = object->section_name(relinfo->data_shndx);
231                   comdat_behavior = get_comdat_behavior(name.c_str());
232                 }
233               if (comdat_behavior == CB_PRETEND)
234                 {
235                   bool found;
236                   typename elfcpp::Elf_types<size>::Elf_Addr value =
237                     object->map_to_kept_section(shndx, &found);
238                   if (found)
239                     symval.set_output_value(value + psymval->input_value());
240                   else
241                     symval.set_output_value(0);
242                 }
243               else
244                 {
245                   if (comdat_behavior == CB_WARNING)
246                     gold_warning_at_location(relinfo, i, offset,
247                                              _("Relocation refers to discarded "
248                                                "comdat section"));
249                   symval.set_output_value(0);
250                 }
251               symval.set_no_output_symtab_entry();
252               psymval = &symval;
253             }
254         }
255       else
256         {
257           const Symbol* gsym = object->global_symbol(r_sym);
258           gold_assert(gsym != NULL);
259           if (gsym->is_forwarder())
260             gsym = relinfo->symtab->resolve_forwards(gsym);
261
262           sym = static_cast<const Sized_symbol<size>*>(gsym);
263           if (sym->has_symtab_index())
264             symval.set_output_symtab_index(sym->symtab_index());
265           else
266             symval.set_no_output_symtab_entry();
267           symval.set_output_value(sym->value());
268           psymval = &symval;
269         }
270
271       if (!relocate.relocate(relinfo, target, i, reloc, r_type, sym, psymval,
272                              view + offset, view_address + offset, view_size))
273         continue;
274
275       if (offset < 0 || static_cast<section_size_type>(offset) >= view_size)
276         {
277           gold_error_at_location(relinfo, i, offset,
278                                  _("reloc has bad offset %zu"),
279                                  static_cast<size_t>(offset));
280           continue;
281         }
282
283       if (sym != NULL
284           && sym->is_undefined()
285           && sym->binding() != elfcpp::STB_WEAK
286           && !target->is_defined_by_abi(sym)
287           && (!parameters->options().shared()       // -shared
288               || parameters->options().defs()))     // -z defs
289         gold_undefined_symbol(sym, relinfo, i, offset);
290
291       if (sym != NULL && sym->has_warning())
292         relinfo->symtab->issue_warning(sym, relinfo, i, offset);
293     }
294 }
295
296 // This class may be used as a typical class for the
297 // Scan_relocatable_reloc parameter to scan_relocatable_relocs.  The
298 // template parameter Classify_reloc must be a class type which
299 // provides a function get_size_for_reloc which returns the number of
300 // bytes to which a reloc applies.  This class is intended to capture
301 // the most typical target behaviour, while still permitting targets
302 // to define their own independent class for Scan_relocatable_reloc.
303
304 template<int sh_type, typename Classify_reloc>
305 class Default_scan_relocatable_relocs
306 {
307  public:
308   // Return the strategy to use for a local symbol which is not a
309   // section symbol, given the relocation type.
310   inline Relocatable_relocs::Reloc_strategy
311   local_non_section_strategy(unsigned int, Relobj*)
312   { return Relocatable_relocs::RELOC_COPY; }
313
314   // Return the strategy to use for a local symbol which is a section
315   // symbol, given the relocation type.
316   inline Relocatable_relocs::Reloc_strategy
317   local_section_strategy(unsigned int r_type, Relobj* object)
318   {
319     if (sh_type == elfcpp::SHT_RELA)
320       return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA;
321     else
322       {
323         Classify_reloc classify;
324         switch (classify.get_size_for_reloc(r_type, object))
325           {
326           case 0:
327             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0;
328           case 1:
329             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1;
330           case 2:
331             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2;
332           case 4:
333             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4;
334           case 8:
335             return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8;
336           default:
337             gold_unreachable();
338           }
339       }
340   }
341
342   // Return the strategy to use for a global symbol, given the
343   // relocation type, the object, and the symbol index.
344   inline Relocatable_relocs::Reloc_strategy
345   global_strategy(unsigned int, Relobj*, unsigned int)
346   { return Relocatable_relocs::RELOC_COPY; }
347 };
348
349 // Scan relocs during a relocatable link.  This is a default
350 // definition which should work for most targets.
351 // Scan_relocatable_reloc must name a class type which provides three
352 // functions which return a Relocatable_relocs::Reloc_strategy code:
353 // global_strategy, local_non_section_strategy, and
354 // local_section_strategy.  Most targets should be able to use
355 // Default_scan_relocatable_relocs as this class.
356
357 template<int size, bool big_endian, int sh_type,
358          typename Scan_relocatable_reloc>
359 void
360 scan_relocatable_relocs(
361     const General_options&,
362     Symbol_table*,
363     Layout*,
364     Sized_relobj<size, big_endian>* object,
365     unsigned int data_shndx,
366     const unsigned char* prelocs,
367     size_t reloc_count,
368     Output_section* output_section,
369     bool needs_special_offset_handling,
370     size_t local_symbol_count,
371     const unsigned char* plocal_syms,
372     Relocatable_relocs* rr)
373 {
374   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
375   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
376   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
377   Scan_relocatable_reloc scan;
378
379   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
380     {
381       Reltype reloc(prelocs);
382
383       Relocatable_relocs::Reloc_strategy strategy;
384
385       if (needs_special_offset_handling
386           && !output_section->is_input_address_mapped(object, data_shndx,
387                                                       reloc.get_r_offset()))
388         strategy = Relocatable_relocs::RELOC_DISCARD;
389       else
390         {
391           typename elfcpp::Elf_types<size>::Elf_WXword r_info =
392             reloc.get_r_info();
393           const unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
394           const unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
395
396           if (r_sym >= local_symbol_count)
397             strategy = scan.global_strategy(r_type, object, r_sym);
398           else
399             {
400               gold_assert(plocal_syms != NULL);
401               typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
402                                                           + r_sym * sym_size);
403               unsigned int shndx = lsym.get_st_shndx();
404               bool is_ordinary;
405               shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
406               if (is_ordinary
407                   && shndx != elfcpp::SHN_UNDEF
408                   && !object->is_section_included(shndx))
409                 {
410                   // RELOC is a relocation against a local symbol
411                   // defined in a section we are discarding.  Discard
412                   // the reloc.  FIXME: Should we issue a warning?
413                   strategy = Relocatable_relocs::RELOC_DISCARD;
414                 }
415               else if (lsym.get_st_type() != elfcpp::STT_SECTION)
416                 strategy = scan.local_non_section_strategy(r_type, object);
417               else
418                 {
419                   strategy = scan.local_section_strategy(r_type, object);
420                   if (strategy != Relocatable_relocs::RELOC_DISCARD)
421                     object->output_section(shndx)->set_needs_symtab_index();
422                 }
423             }
424         }
425
426       rr->set_next_reloc_strategy(strategy);
427     }
428 }
429
430 // Relocate relocs during a relocatable link.  This is a default
431 // definition which should work for most targets.
432
433 template<int size, bool big_endian, int sh_type>
434 void
435 relocate_for_relocatable(
436     const Relocate_info<size, big_endian>* relinfo,
437     const unsigned char* prelocs,
438     size_t reloc_count,
439     Output_section* output_section,
440     typename elfcpp::Elf_types<size>::Elf_Addr offset_in_output_section,
441     const Relocatable_relocs* rr,
442     unsigned char* view,
443     typename elfcpp::Elf_types<size>::Elf_Addr view_address,
444     section_size_type,
445     unsigned char* reloc_view,
446     section_size_type reloc_view_size)
447 {
448   typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
449   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
450   typedef typename Reloc_types<sh_type, size, big_endian>::Reloc_write
451     Reltype_write;
452   const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
453   const Address invalid_address = static_cast<Address>(0) - 1;
454
455   Sized_relobj<size, big_endian>* const object = relinfo->object;
456   const unsigned int local_count = object->local_symbol_count();
457
458   unsigned char* pwrite = reloc_view;
459
460   for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
461     {
462       Relocatable_relocs::Reloc_strategy strategy = rr->strategy(i);
463       if (strategy == Relocatable_relocs::RELOC_DISCARD)
464         continue;
465
466       Reltype reloc(prelocs);
467       Reltype_write reloc_write(pwrite);
468
469       typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
470       const unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
471       const unsigned int r_type = elfcpp::elf_r_type<size>(r_info);
472
473       // Get the new symbol index.
474
475       unsigned int new_symndx;
476       if (r_sym < local_count)
477         {
478           switch (strategy)
479             {
480             case Relocatable_relocs::RELOC_COPY:
481               new_symndx = object->symtab_index(r_sym);
482               gold_assert(new_symndx != -1U);
483               break;
484
485             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA:
486             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0:
487             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1:
488             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2:
489             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4:
490             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8:
491               {
492                 // We are adjusting a section symbol.  We need to find
493                 // the symbol table index of the section symbol for
494                 // the output section corresponding to input section
495                 // in which this symbol is defined.
496                 gold_assert(r_sym < local_count);
497                 bool is_ordinary;
498                 unsigned int shndx =
499                   object->local_symbol_input_shndx(r_sym, &is_ordinary);
500                 gold_assert(is_ordinary);
501                 Output_section* os = object->output_section(shndx);
502                 gold_assert(os != NULL);
503                 gold_assert(os->needs_symtab_index());
504                 new_symndx = os->symtab_index();
505               }
506               break;
507
508             default:
509               gold_unreachable();
510             }
511         }
512       else
513         {
514           const Symbol* gsym = object->global_symbol(r_sym);
515           gold_assert(gsym != NULL);
516           if (gsym->is_forwarder())
517             gsym = relinfo->symtab->resolve_forwards(gsym);
518
519           gold_assert(gsym->has_symtab_index());
520           new_symndx = gsym->symtab_index();
521         }
522
523       // Get the new offset--the location in the output section where
524       // this relocation should be applied.
525
526       Address offset = reloc.get_r_offset();
527       Address new_offset;
528       if (offset_in_output_section != invalid_address)
529         new_offset = offset + offset_in_output_section;
530       else
531         {
532           section_offset_type sot_offset =
533               convert_types<section_offset_type, Address>(offset);
534           section_offset_type new_sot_offset =
535               output_section->output_offset(object, relinfo->data_shndx,
536                                             sot_offset);
537           gold_assert(new_sot_offset != -1);
538           new_offset = new_sot_offset;
539         }
540
541       // In an object file, r_offset is an offset within the section.
542       // In an executable or dynamic object, generated by
543       // --emit-relocs, r_offset is an absolute address.
544       if (!parameters->options().relocatable())
545         {
546           new_offset += view_address;
547           if (offset_in_output_section != invalid_address)
548             new_offset -= offset_in_output_section;
549         }
550
551       reloc_write.put_r_offset(new_offset);
552       reloc_write.put_r_info(elfcpp::elf_r_info<size>(new_symndx, r_type));
553
554       // Handle the reloc addend based on the strategy.
555
556       if (strategy == Relocatable_relocs::RELOC_COPY)
557         {
558           if (sh_type == elfcpp::SHT_RELA)
559             Reloc_types<sh_type, size, big_endian>::
560               copy_reloc_addend(&reloc_write,
561                                 &reloc);
562         }
563       else
564         {
565           // The relocation uses a section symbol in the input file.
566           // We are adjusting it to use a section symbol in the output
567           // file.  The input section symbol refers to some address in
568           // the input section.  We need the relocation in the output
569           // file to refer to that same address.  This adjustment to
570           // the addend is the same calculation we use for a simple
571           // absolute relocation for the input section symbol.
572
573           const Symbol_value<size>* psymval = object->local_symbol(r_sym);
574
575           unsigned char* padd = view + offset;
576           switch (strategy)
577             {
578             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA:
579               {
580                 typename elfcpp::Elf_types<size>::Elf_Swxword addend;
581                 addend = Reloc_types<sh_type, size, big_endian>::
582                            get_reloc_addend(&reloc);
583                 addend = psymval->value(object, addend);
584                 Reloc_types<sh_type, size, big_endian>::
585                   set_reloc_addend(&reloc_write, addend);
586               }
587               break;
588
589             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0:
590               break;
591
592             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_1:
593               Relocate_functions<size, big_endian>::rel8(padd, object,
594                                                          psymval);
595               break;
596
597             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_2:
598               Relocate_functions<size, big_endian>::rel16(padd, object,
599                                                           psymval);
600               break;
601
602             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4:
603               Relocate_functions<size, big_endian>::rel32(padd, object,
604                                                           psymval);
605               break;
606
607             case Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_8:
608               Relocate_functions<size, big_endian>::rel64(padd, object,
609                                                           psymval);
610               break;
611
612             default:
613               gold_unreachable();
614             }
615         }
616
617       pwrite += reloc_size;
618     }
619
620   gold_assert(static_cast<section_size_type>(pwrite - reloc_view)
621               == reloc_view_size);
622 }
623
624 } // End namespace gold.
625
626 #endif // !defined(GOLD_TARGET_RELOC_H)