gold/
[deliverable/binutils-gdb.git] / gold / i386.cc
1 // i386.cc -- i386 target support for gold.
2
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
4 // Free Software Foundation, Inc.
5 // Written by Ian Lance Taylor <iant@google.com>.
6
7 // This file is part of gold.
8
9 // This program is free software; you can redistribute it and/or modify
10 // it under the terms of the GNU General Public License as published by
11 // the Free Software Foundation; either version 3 of the License, or
12 // (at your option) any later version.
13
14 // This program is distributed in the hope that it will be useful,
15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 // GNU General Public License for more details.
18
19 // You should have received a copy of the GNU General Public License
20 // along with this program; if not, write to the Free Software
21 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
22 // MA 02110-1301, USA.
23
24 #include "gold.h"
25
26 #include <cstring>
27
28 #include "elfcpp.h"
29 #include "dwarf.h"
30 #include "parameters.h"
31 #include "reloc.h"
32 #include "i386.h"
33 #include "object.h"
34 #include "symtab.h"
35 #include "layout.h"
36 #include "output.h"
37 #include "copy-relocs.h"
38 #include "target.h"
39 #include "target-reloc.h"
40 #include "target-select.h"
41 #include "tls.h"
42 #include "freebsd.h"
43 #include "nacl.h"
44 #include "gc.h"
45
46 namespace
47 {
48
49 using namespace gold;
50
51 // A class to handle the PLT data.
52 // This is an abstract base class that handles most of the linker details
53 // but does not know the actual contents of PLT entries. The derived
54 // classes below fill in those details.
55
56 class Output_data_plt_i386 : public Output_section_data
57 {
58 public:
59 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
60
61 Output_data_plt_i386(Layout*, uint64_t addralign,
62 Output_data_space*, Output_data_space*);
63
64 // Add an entry to the PLT.
65 void
66 add_entry(Symbol_table*, Layout*, Symbol* gsym);
67
68 // Add an entry to the PLT for a local STT_GNU_IFUNC symbol.
69 unsigned int
70 add_local_ifunc_entry(Symbol_table*, Layout*,
71 Sized_relobj_file<32, false>* relobj,
72 unsigned int local_sym_index);
73
74 // Return the .rel.plt section data.
75 Reloc_section*
76 rel_plt() const
77 { return this->rel_; }
78
79 // Return where the TLS_DESC relocations should go.
80 Reloc_section*
81 rel_tls_desc(Layout*);
82
83 // Return where the IRELATIVE relocations should go.
84 Reloc_section*
85 rel_irelative(Symbol_table*, Layout*);
86
87 // Return whether we created a section for IRELATIVE relocations.
88 bool
89 has_irelative_section() const
90 { return this->irelative_rel_ != NULL; }
91
92 // Return the number of PLT entries.
93 unsigned int
94 entry_count() const
95 { return this->count_ + this->irelative_count_; }
96
97 // Return the offset of the first non-reserved PLT entry.
98 unsigned int
99 first_plt_entry_offset()
100 { return this->get_plt_entry_size(); }
101
102 // Return the size of a PLT entry.
103 unsigned int
104 get_plt_entry_size() const
105 { return this->do_get_plt_entry_size(); }
106
107 // Return the PLT address to use for a global symbol.
108 uint64_t
109 address_for_global(const Symbol*);
110
111 // Return the PLT address to use for a local symbol.
112 uint64_t
113 address_for_local(const Relobj*, unsigned int symndx);
114
115 // Add .eh_frame information for the PLT.
116 void
117 add_eh_frame(Layout* layout)
118 { this->do_add_eh_frame(layout); }
119
120 protected:
121 // Fill the first PLT entry, given the pointer to the PLT section data
122 // and the runtime address of the GOT.
123 void
124 fill_first_plt_entry(unsigned char* pov,
125 elfcpp::Elf_types<32>::Elf_Addr got_address)
126 { this->do_fill_first_plt_entry(pov, got_address); }
127
128 // Fill a normal PLT entry, given the pointer to the entry's data in the
129 // section, the runtime address of the GOT, the offset into the GOT of
130 // the corresponding slot, the offset into the relocation section of the
131 // corresponding reloc, and the offset of this entry within the whole
132 // PLT. Return the offset from this PLT entry's runtime address that
133 // should be used to compute the initial value of the GOT slot.
134 unsigned int
135 fill_plt_entry(unsigned char* pov,
136 elfcpp::Elf_types<32>::Elf_Addr got_address,
137 unsigned int got_offset,
138 unsigned int plt_offset,
139 unsigned int plt_rel_offset)
140 {
141 return this->do_fill_plt_entry(pov, got_address, got_offset,
142 plt_offset, plt_rel_offset);
143 }
144
145 virtual unsigned int
146 do_get_plt_entry_size() const = 0;
147
148 virtual void
149 do_fill_first_plt_entry(unsigned char* pov,
150 elfcpp::Elf_types<32>::Elf_Addr got_address) = 0;
151
152 virtual unsigned int
153 do_fill_plt_entry(unsigned char* pov,
154 elfcpp::Elf_types<32>::Elf_Addr got_address,
155 unsigned int got_offset,
156 unsigned int plt_offset,
157 unsigned int plt_rel_offset) = 0;
158
159 virtual void
160 do_add_eh_frame(Layout*) = 0;
161
162 void
163 do_adjust_output_section(Output_section* os);
164
165 // Write to a map file.
166 void
167 do_print_to_mapfile(Mapfile* mapfile) const
168 { mapfile->print_output_data(this, _("** PLT")); }
169
170 // The .eh_frame unwind information for the PLT.
171 // The CIE is common across variants of the PLT format.
172 static const int plt_eh_frame_cie_size = 16;
173 static const unsigned char plt_eh_frame_cie[plt_eh_frame_cie_size];
174
175 private:
176 // Set the final size.
177 void
178 set_final_data_size()
179 {
180 this->set_data_size((this->count_ + this->irelative_count_ + 1)
181 * this->get_plt_entry_size());
182 }
183
184 // Write out the PLT data.
185 void
186 do_write(Output_file*);
187
188 // We keep a list of global STT_GNU_IFUNC symbols, each with its
189 // offset in the GOT.
190 struct Global_ifunc
191 {
192 Symbol* sym;
193 unsigned int got_offset;
194 };
195
196 // We keep a list of local STT_GNU_IFUNC symbols, each with its
197 // offset in the GOT.
198 struct Local_ifunc
199 {
200 Sized_relobj_file<32, false>* object;
201 unsigned int local_sym_index;
202 unsigned int got_offset;
203 };
204
205 // A pointer to the Layout class, so that we can find the .dynamic
206 // section when we write out the GOT PLT section.
207 Layout* layout_;
208 // The reloc section.
209 Reloc_section* rel_;
210 // The TLS_DESC relocations, if necessary. These must follow the
211 // regular PLT relocs.
212 Reloc_section* tls_desc_rel_;
213 // The IRELATIVE relocations, if necessary. These must follow the
214 // regular relocatoins and the TLS_DESC relocations.
215 Reloc_section* irelative_rel_;
216 // The .got.plt section.
217 Output_data_space* got_plt_;
218 // The part of the .got.plt section used for IRELATIVE relocs.
219 Output_data_space* got_irelative_;
220 // The number of PLT entries.
221 unsigned int count_;
222 // Number of PLT entries with R_386_IRELATIVE relocs. These follow
223 // the regular PLT entries.
224 unsigned int irelative_count_;
225 // Global STT_GNU_IFUNC symbols.
226 std::vector<Global_ifunc> global_ifuncs_;
227 // Local STT_GNU_IFUNC symbols.
228 std::vector<Local_ifunc> local_ifuncs_;
229 };
230
231 // This is an abstract class for the standard PLT layout.
232 // The derived classes below handle the actual PLT contents
233 // for the executable (non-PIC) and shared-library (PIC) cases.
234 // The unwind information is uniform across those two, so it's here.
235
236 class Output_data_plt_i386_standard : public Output_data_plt_i386
237 {
238 public:
239 Output_data_plt_i386_standard(Layout* layout,
240 Output_data_space* got_plt,
241 Output_data_space* got_irelative)
242 : Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
243 { }
244
245 protected:
246 virtual unsigned int
247 do_get_plt_entry_size() const
248 { return plt_entry_size; }
249
250 virtual void
251 do_add_eh_frame(Layout* layout)
252 {
253 layout->add_eh_frame_for_plt(this, plt_eh_frame_cie, plt_eh_frame_cie_size,
254 plt_eh_frame_fde, plt_eh_frame_fde_size);
255 }
256
257 // The size of an entry in the PLT.
258 static const int plt_entry_size = 16;
259
260 // The .eh_frame unwind information for the PLT.
261 static const int plt_eh_frame_fde_size = 32;
262 static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
263 };
264
265 // Actually fill the PLT contents for an executable (non-PIC).
266
267 class Output_data_plt_i386_exec : public Output_data_plt_i386_standard
268 {
269 public:
270 Output_data_plt_i386_exec(Layout* layout,
271 Output_data_space* got_plt,
272 Output_data_space* got_irelative)
273 : Output_data_plt_i386_standard(layout, got_plt, got_irelative)
274 { }
275
276 protected:
277 virtual void
278 do_fill_first_plt_entry(unsigned char* pov,
279 elfcpp::Elf_types<32>::Elf_Addr got_address);
280
281 virtual unsigned int
282 do_fill_plt_entry(unsigned char* pov,
283 elfcpp::Elf_types<32>::Elf_Addr got_address,
284 unsigned int got_offset,
285 unsigned int plt_offset,
286 unsigned int plt_rel_offset);
287
288 private:
289 // The first entry in the PLT for an executable.
290 static const unsigned char first_plt_entry[plt_entry_size];
291
292 // Other entries in the PLT for an executable.
293 static const unsigned char plt_entry[plt_entry_size];
294 };
295
296 // Actually fill the PLT contents for a shared library (PIC).
297
298 class Output_data_plt_i386_dyn : public Output_data_plt_i386_standard
299 {
300 public:
301 Output_data_plt_i386_dyn(Layout* layout,
302 Output_data_space* got_plt,
303 Output_data_space* got_irelative)
304 : Output_data_plt_i386_standard(layout, got_plt, got_irelative)
305 { }
306
307 protected:
308 virtual void
309 do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<32>::Elf_Addr);
310
311 virtual unsigned int
312 do_fill_plt_entry(unsigned char* pov,
313 elfcpp::Elf_types<32>::Elf_Addr,
314 unsigned int got_offset,
315 unsigned int plt_offset,
316 unsigned int plt_rel_offset);
317
318 private:
319 // The first entry in the PLT for a shared object.
320 static const unsigned char first_plt_entry[plt_entry_size];
321
322 // Other entries in the PLT for a shared object.
323 static const unsigned char plt_entry[plt_entry_size];
324 };
325
326 // The i386 target class.
327 // TLS info comes from
328 // http://people.redhat.com/drepper/tls.pdf
329 // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
330
331 class Target_i386 : public Sized_target<32, false>
332 {
333 public:
334 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
335
336 Target_i386(const Target::Target_info* info = &i386_info)
337 : Sized_target<32, false>(info),
338 got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL),
339 got_tlsdesc_(NULL), global_offset_table_(NULL), rel_dyn_(NULL),
340 rel_irelative_(NULL), copy_relocs_(elfcpp::R_386_COPY), dynbss_(NULL),
341 got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
342 { }
343
344 // Process the relocations to determine unreferenced sections for
345 // garbage collection.
346 void
347 gc_process_relocs(Symbol_table* symtab,
348 Layout* layout,
349 Sized_relobj_file<32, false>* object,
350 unsigned int data_shndx,
351 unsigned int sh_type,
352 const unsigned char* prelocs,
353 size_t reloc_count,
354 Output_section* output_section,
355 bool needs_special_offset_handling,
356 size_t local_symbol_count,
357 const unsigned char* plocal_symbols);
358
359 // Scan the relocations to look for symbol adjustments.
360 void
361 scan_relocs(Symbol_table* symtab,
362 Layout* layout,
363 Sized_relobj_file<32, false>* object,
364 unsigned int data_shndx,
365 unsigned int sh_type,
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_symbols);
372
373 // Finalize the sections.
374 void
375 do_finalize_sections(Layout*, const Input_objects*, Symbol_table*);
376
377 // Return the value to use for a dynamic which requires special
378 // treatment.
379 uint64_t
380 do_dynsym_value(const Symbol*) const;
381
382 // Relocate a section.
383 void
384 relocate_section(const Relocate_info<32, false>*,
385 unsigned int sh_type,
386 const unsigned char* prelocs,
387 size_t reloc_count,
388 Output_section* output_section,
389 bool needs_special_offset_handling,
390 unsigned char* view,
391 elfcpp::Elf_types<32>::Elf_Addr view_address,
392 section_size_type view_size,
393 const Reloc_symbol_changes*);
394
395 // Scan the relocs during a relocatable link.
396 void
397 scan_relocatable_relocs(Symbol_table* symtab,
398 Layout* layout,
399 Sized_relobj_file<32, false>* object,
400 unsigned int data_shndx,
401 unsigned int sh_type,
402 const unsigned char* prelocs,
403 size_t reloc_count,
404 Output_section* output_section,
405 bool needs_special_offset_handling,
406 size_t local_symbol_count,
407 const unsigned char* plocal_symbols,
408 Relocatable_relocs*);
409
410 // Emit relocations for a section.
411 void
412 relocate_relocs(const Relocate_info<32, false>*,
413 unsigned int sh_type,
414 const unsigned char* prelocs,
415 size_t reloc_count,
416 Output_section* output_section,
417 elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,
418 const Relocatable_relocs*,
419 unsigned char* view,
420 elfcpp::Elf_types<32>::Elf_Addr view_address,
421 section_size_type view_size,
422 unsigned char* reloc_view,
423 section_size_type reloc_view_size);
424
425 // Return a string used to fill a code section with nops.
426 std::string
427 do_code_fill(section_size_type length) const;
428
429 // Return whether SYM is defined by the ABI.
430 bool
431 do_is_defined_by_abi(const Symbol* sym) const
432 { return strcmp(sym->name(), "___tls_get_addr") == 0; }
433
434 // Return whether a symbol name implies a local label. The UnixWare
435 // 2.1 cc generates temporary symbols that start with .X, so we
436 // recognize them here. FIXME: do other SVR4 compilers also use .X?.
437 // If so, we should move the .X recognition into
438 // Target::do_is_local_label_name.
439 bool
440 do_is_local_label_name(const char* name) const
441 {
442 if (name[0] == '.' && name[1] == 'X')
443 return true;
444 return Target::do_is_local_label_name(name);
445 }
446
447 // Return the PLT address to use for a global symbol.
448 uint64_t
449 do_plt_address_for_global(const Symbol* gsym) const
450 { return this->plt_section()->address_for_global(gsym); }
451
452 uint64_t
453 do_plt_address_for_local(const Relobj* relobj, unsigned int symndx) const
454 { return this->plt_section()->address_for_local(relobj, symndx); }
455
456 // We can tell whether we take the address of a function.
457 inline bool
458 do_can_check_for_function_pointers() const
459 { return true; }
460
461 // Return the base for a DW_EH_PE_datarel encoding.
462 uint64_t
463 do_ehframe_datarel_base() const;
464
465 // Return whether SYM is call to a non-split function.
466 bool
467 do_is_call_to_non_split(const Symbol* sym, unsigned int) const;
468
469 // Adjust -fsplit-stack code which calls non-split-stack code.
470 void
471 do_calls_non_split(Relobj* object, unsigned int shndx,
472 section_offset_type fnoffset, section_size_type fnsize,
473 unsigned char* view, section_size_type view_size,
474 std::string* from, std::string* to) const;
475
476 // Return the size of the GOT section.
477 section_size_type
478 got_size() const
479 {
480 gold_assert(this->got_ != NULL);
481 return this->got_->data_size();
482 }
483
484 // Return the number of entries in the GOT.
485 unsigned int
486 got_entry_count() const
487 {
488 if (this->got_ == NULL)
489 return 0;
490 return this->got_size() / 4;
491 }
492
493 // Return the number of entries in the PLT.
494 unsigned int
495 plt_entry_count() const;
496
497 // Return the offset of the first non-reserved PLT entry.
498 unsigned int
499 first_plt_entry_offset() const;
500
501 // Return the size of each PLT entry.
502 unsigned int
503 plt_entry_size() const;
504
505 protected:
506 // Instantiate the plt_ member.
507 // This chooses the right PLT flavor for an executable or a shared object.
508 Output_data_plt_i386*
509 make_data_plt(Layout* layout,
510 Output_data_space* got_plt,
511 Output_data_space* got_irelative,
512 bool dyn)
513 { return this->do_make_data_plt(layout, got_plt, got_irelative, dyn); }
514
515 virtual Output_data_plt_i386*
516 do_make_data_plt(Layout* layout,
517 Output_data_space* got_plt,
518 Output_data_space* got_irelative,
519 bool dyn)
520 {
521 if (dyn)
522 return new Output_data_plt_i386_dyn(layout, got_plt, got_irelative);
523 else
524 return new Output_data_plt_i386_exec(layout, got_plt, got_irelative);
525 }
526
527 private:
528 // The class which scans relocations.
529 struct Scan
530 {
531 static inline int
532
533 get_reference_flags(unsigned int r_type);
534
535 inline void
536 local(Symbol_table* symtab, Layout* layout, Target_i386* target,
537 Sized_relobj_file<32, false>* object,
538 unsigned int data_shndx,
539 Output_section* output_section,
540 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
541 const elfcpp::Sym<32, false>& lsym,
542 bool is_discarded);
543
544 inline void
545 global(Symbol_table* symtab, Layout* layout, Target_i386* target,
546 Sized_relobj_file<32, false>* object,
547 unsigned int data_shndx,
548 Output_section* output_section,
549 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
550 Symbol* gsym);
551
552 inline bool
553 local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
554 Target_i386* target,
555 Sized_relobj_file<32, false>* object,
556 unsigned int data_shndx,
557 Output_section* output_section,
558 const elfcpp::Rel<32, false>& reloc,
559 unsigned int r_type,
560 const elfcpp::Sym<32, false>& lsym);
561
562 inline bool
563 global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
564 Target_i386* target,
565 Sized_relobj_file<32, false>* object,
566 unsigned int data_shndx,
567 Output_section* output_section,
568 const elfcpp::Rel<32, false>& reloc,
569 unsigned int r_type,
570 Symbol* gsym);
571
572 inline bool
573 possible_function_pointer_reloc(unsigned int r_type);
574
575 bool
576 reloc_needs_plt_for_ifunc(Sized_relobj_file<32, false>*,
577 unsigned int r_type);
578
579 static void
580 unsupported_reloc_local(Sized_relobj_file<32, false>*, unsigned int r_type);
581
582 static void
583 unsupported_reloc_global(Sized_relobj_file<32, false>*, unsigned int r_type,
584 Symbol*);
585 };
586
587 // The class which implements relocation.
588 class Relocate
589 {
590 public:
591 Relocate()
592 : skip_call_tls_get_addr_(false),
593 local_dynamic_type_(LOCAL_DYNAMIC_NONE)
594 { }
595
596 ~Relocate()
597 {
598 if (this->skip_call_tls_get_addr_)
599 {
600 // FIXME: This needs to specify the location somehow.
601 gold_error(_("missing expected TLS relocation"));
602 }
603 }
604
605 // Return whether the static relocation needs to be applied.
606 inline bool
607 should_apply_static_reloc(const Sized_symbol<32>* gsym,
608 unsigned int r_type,
609 bool is_32bit,
610 Output_section* output_section);
611
612 // Do a relocation. Return false if the caller should not issue
613 // any warnings about this relocation.
614 inline bool
615 relocate(const Relocate_info<32, false>*, Target_i386*, Output_section*,
616 size_t relnum, const elfcpp::Rel<32, false>&,
617 unsigned int r_type, const Sized_symbol<32>*,
618 const Symbol_value<32>*,
619 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
620 section_size_type);
621
622 private:
623 // Do a TLS relocation.
624 inline void
625 relocate_tls(const Relocate_info<32, false>*, Target_i386* target,
626 size_t relnum, const elfcpp::Rel<32, false>&,
627 unsigned int r_type, const Sized_symbol<32>*,
628 const Symbol_value<32>*,
629 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
630 section_size_type);
631
632 // Do a TLS General-Dynamic to Initial-Exec transition.
633 inline void
634 tls_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
635 Output_segment* tls_segment,
636 const elfcpp::Rel<32, false>&, unsigned int r_type,
637 elfcpp::Elf_types<32>::Elf_Addr value,
638 unsigned char* view,
639 section_size_type view_size);
640
641 // Do a TLS General-Dynamic to Local-Exec transition.
642 inline void
643 tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
644 Output_segment* tls_segment,
645 const elfcpp::Rel<32, false>&, unsigned int r_type,
646 elfcpp::Elf_types<32>::Elf_Addr value,
647 unsigned char* view,
648 section_size_type view_size);
649
650 // Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Initial-Exec
651 // transition.
652 inline void
653 tls_desc_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
654 Output_segment* tls_segment,
655 const elfcpp::Rel<32, false>&, unsigned int r_type,
656 elfcpp::Elf_types<32>::Elf_Addr value,
657 unsigned char* view,
658 section_size_type view_size);
659
660 // Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Local-Exec
661 // transition.
662 inline void
663 tls_desc_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
664 Output_segment* tls_segment,
665 const elfcpp::Rel<32, false>&, unsigned int r_type,
666 elfcpp::Elf_types<32>::Elf_Addr value,
667 unsigned char* view,
668 section_size_type view_size);
669
670 // Do a TLS Local-Dynamic to Local-Exec transition.
671 inline void
672 tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
673 Output_segment* tls_segment,
674 const elfcpp::Rel<32, false>&, unsigned int r_type,
675 elfcpp::Elf_types<32>::Elf_Addr value,
676 unsigned char* view,
677 section_size_type view_size);
678
679 // Do a TLS Initial-Exec to Local-Exec transition.
680 static inline void
681 tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
682 Output_segment* tls_segment,
683 const elfcpp::Rel<32, false>&, unsigned int r_type,
684 elfcpp::Elf_types<32>::Elf_Addr value,
685 unsigned char* view,
686 section_size_type view_size);
687
688 // We need to keep track of which type of local dynamic relocation
689 // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
690 enum Local_dynamic_type
691 {
692 LOCAL_DYNAMIC_NONE,
693 LOCAL_DYNAMIC_SUN,
694 LOCAL_DYNAMIC_GNU
695 };
696
697 // This is set if we should skip the next reloc, which should be a
698 // PLT32 reloc against ___tls_get_addr.
699 bool skip_call_tls_get_addr_;
700 // The type of local dynamic relocation we have seen in the section
701 // being relocated, if any.
702 Local_dynamic_type local_dynamic_type_;
703 };
704
705 // A class which returns the size required for a relocation type,
706 // used while scanning relocs during a relocatable link.
707 class Relocatable_size_for_reloc
708 {
709 public:
710 unsigned int
711 get_size_for_reloc(unsigned int, Relobj*);
712 };
713
714 // Adjust TLS relocation type based on the options and whether this
715 // is a local symbol.
716 static tls::Tls_optimization
717 optimize_tls_reloc(bool is_final, int r_type);
718
719 // Get the GOT section, creating it if necessary.
720 Output_data_got<32, false>*
721 got_section(Symbol_table*, Layout*);
722
723 // Get the GOT PLT section.
724 Output_data_space*
725 got_plt_section() const
726 {
727 gold_assert(this->got_plt_ != NULL);
728 return this->got_plt_;
729 }
730
731 // Get the GOT section for TLSDESC entries.
732 Output_data_got<32, false>*
733 got_tlsdesc_section() const
734 {
735 gold_assert(this->got_tlsdesc_ != NULL);
736 return this->got_tlsdesc_;
737 }
738
739 // Create the PLT section.
740 void
741 make_plt_section(Symbol_table* symtab, Layout* layout);
742
743 // Create a PLT entry for a global symbol.
744 void
745 make_plt_entry(Symbol_table*, Layout*, Symbol*);
746
747 // Create a PLT entry for a local STT_GNU_IFUNC symbol.
748 void
749 make_local_ifunc_plt_entry(Symbol_table*, Layout*,
750 Sized_relobj_file<32, false>* relobj,
751 unsigned int local_sym_index);
752
753 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
754 void
755 define_tls_base_symbol(Symbol_table*, Layout*);
756
757 // Create a GOT entry for the TLS module index.
758 unsigned int
759 got_mod_index_entry(Symbol_table* symtab, Layout* layout,
760 Sized_relobj_file<32, false>* object);
761
762 // Get the PLT section.
763 Output_data_plt_i386*
764 plt_section() const
765 {
766 gold_assert(this->plt_ != NULL);
767 return this->plt_;
768 }
769
770 // Get the dynamic reloc section, creating it if necessary.
771 Reloc_section*
772 rel_dyn_section(Layout*);
773
774 // Get the section to use for TLS_DESC relocations.
775 Reloc_section*
776 rel_tls_desc_section(Layout*) const;
777
778 // Get the section to use for IRELATIVE relocations.
779 Reloc_section*
780 rel_irelative_section(Layout*);
781
782 // Add a potential copy relocation.
783 void
784 copy_reloc(Symbol_table* symtab, Layout* layout,
785 Sized_relobj_file<32, false>* object,
786 unsigned int shndx, Output_section* output_section,
787 Symbol* sym, const elfcpp::Rel<32, false>& reloc)
788 {
789 this->copy_relocs_.copy_reloc(symtab, layout,
790 symtab->get_sized_symbol<32>(sym),
791 object, shndx, output_section, reloc,
792 this->rel_dyn_section(layout));
793 }
794
795 // Information about this specific target which we pass to the
796 // general Target structure.
797 static const Target::Target_info i386_info;
798
799 // The types of GOT entries needed for this platform.
800 // These values are exposed to the ABI in an incremental link.
801 // Do not renumber existing values without changing the version
802 // number of the .gnu_incremental_inputs section.
803 enum Got_type
804 {
805 GOT_TYPE_STANDARD = 0, // GOT entry for a regular symbol
806 GOT_TYPE_TLS_NOFFSET = 1, // GOT entry for negative TLS offset
807 GOT_TYPE_TLS_OFFSET = 2, // GOT entry for positive TLS offset
808 GOT_TYPE_TLS_PAIR = 3, // GOT entry for TLS module/offset pair
809 GOT_TYPE_TLS_DESC = 4 // GOT entry for TLS_DESC pair
810 };
811
812 // The GOT section.
813 Output_data_got<32, false>* got_;
814 // The PLT section.
815 Output_data_plt_i386* plt_;
816 // The GOT PLT section.
817 Output_data_space* got_plt_;
818 // The GOT section for IRELATIVE relocations.
819 Output_data_space* got_irelative_;
820 // The GOT section for TLSDESC relocations.
821 Output_data_got<32, false>* got_tlsdesc_;
822 // The _GLOBAL_OFFSET_TABLE_ symbol.
823 Symbol* global_offset_table_;
824 // The dynamic reloc section.
825 Reloc_section* rel_dyn_;
826 // The section to use for IRELATIVE relocs.
827 Reloc_section* rel_irelative_;
828 // Relocs saved to avoid a COPY reloc.
829 Copy_relocs<elfcpp::SHT_REL, 32, false> copy_relocs_;
830 // Space for variables copied with a COPY reloc.
831 Output_data_space* dynbss_;
832 // Offset of the GOT entry for the TLS module index.
833 unsigned int got_mod_index_offset_;
834 // True if the _TLS_MODULE_BASE_ symbol has been defined.
835 bool tls_base_symbol_defined_;
836 };
837
838 const Target::Target_info Target_i386::i386_info =
839 {
840 32, // size
841 false, // is_big_endian
842 elfcpp::EM_386, // machine_code
843 false, // has_make_symbol
844 false, // has_resolve
845 true, // has_code_fill
846 true, // is_default_stack_executable
847 true, // can_icf_inline_merge_sections
848 '\0', // wrap_char
849 "/usr/lib/libc.so.1", // dynamic_linker
850 0x08048000, // default_text_segment_address
851 0x1000, // abi_pagesize (overridable by -z max-page-size)
852 0x1000, // common_pagesize (overridable by -z common-page-size)
853 false, // isolate_execinstr
854 0, // rosegment_gap
855 elfcpp::SHN_UNDEF, // small_common_shndx
856 elfcpp::SHN_UNDEF, // large_common_shndx
857 0, // small_common_section_flags
858 0, // large_common_section_flags
859 NULL, // attributes_section
860 NULL, // attributes_vendor
861 "_start" // entry_symbol_name
862 };
863
864 // Get the GOT section, creating it if necessary.
865
866 Output_data_got<32, false>*
867 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
868 {
869 if (this->got_ == NULL)
870 {
871 gold_assert(symtab != NULL && layout != NULL);
872
873 this->got_ = new Output_data_got<32, false>();
874
875 // When using -z now, we can treat .got.plt as a relro section.
876 // Without -z now, it is modified after program startup by lazy
877 // PLT relocations.
878 bool is_got_plt_relro = parameters->options().now();
879 Output_section_order got_order = (is_got_plt_relro
880 ? ORDER_RELRO
881 : ORDER_RELRO_LAST);
882 Output_section_order got_plt_order = (is_got_plt_relro
883 ? ORDER_RELRO
884 : ORDER_NON_RELRO_FIRST);
885
886 layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
887 (elfcpp::SHF_ALLOC
888 | elfcpp::SHF_WRITE),
889 this->got_, got_order, true);
890
891 this->got_plt_ = new Output_data_space(4, "** GOT PLT");
892 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
893 (elfcpp::SHF_ALLOC
894 | elfcpp::SHF_WRITE),
895 this->got_plt_, got_plt_order,
896 is_got_plt_relro);
897
898 // The first three entries are reserved.
899 this->got_plt_->set_current_data_size(3 * 4);
900
901 if (!is_got_plt_relro)
902 {
903 // Those bytes can go into the relro segment.
904 layout->increase_relro(3 * 4);
905 }
906
907 // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
908 this->global_offset_table_ =
909 symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
910 Symbol_table::PREDEFINED,
911 this->got_plt_,
912 0, 0, elfcpp::STT_OBJECT,
913 elfcpp::STB_LOCAL,
914 elfcpp::STV_HIDDEN, 0,
915 false, false);
916
917 // If there are any IRELATIVE relocations, they get GOT entries
918 // in .got.plt after the jump slot relocations.
919 this->got_irelative_ = new Output_data_space(4, "** GOT IRELATIVE PLT");
920 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
921 (elfcpp::SHF_ALLOC
922 | elfcpp::SHF_WRITE),
923 this->got_irelative_,
924 got_plt_order, is_got_plt_relro);
925
926 // If there are any TLSDESC relocations, they get GOT entries in
927 // .got.plt after the jump slot entries.
928 this->got_tlsdesc_ = new Output_data_got<32, false>();
929 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
930 (elfcpp::SHF_ALLOC
931 | elfcpp::SHF_WRITE),
932 this->got_tlsdesc_,
933 got_plt_order, is_got_plt_relro);
934 }
935
936 return this->got_;
937 }
938
939 // Get the dynamic reloc section, creating it if necessary.
940
941 Target_i386::Reloc_section*
942 Target_i386::rel_dyn_section(Layout* layout)
943 {
944 if (this->rel_dyn_ == NULL)
945 {
946 gold_assert(layout != NULL);
947 this->rel_dyn_ = new Reloc_section(parameters->options().combreloc());
948 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
949 elfcpp::SHF_ALLOC, this->rel_dyn_,
950 ORDER_DYNAMIC_RELOCS, false);
951 }
952 return this->rel_dyn_;
953 }
954
955 // Get the section to use for IRELATIVE relocs, creating it if
956 // necessary. These go in .rel.dyn, but only after all other dynamic
957 // relocations. They need to follow the other dynamic relocations so
958 // that they can refer to global variables initialized by those
959 // relocs.
960
961 Target_i386::Reloc_section*
962 Target_i386::rel_irelative_section(Layout* layout)
963 {
964 if (this->rel_irelative_ == NULL)
965 {
966 // Make sure we have already create the dynamic reloc section.
967 this->rel_dyn_section(layout);
968 this->rel_irelative_ = new Reloc_section(false);
969 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
970 elfcpp::SHF_ALLOC, this->rel_irelative_,
971 ORDER_DYNAMIC_RELOCS, false);
972 gold_assert(this->rel_dyn_->output_section()
973 == this->rel_irelative_->output_section());
974 }
975 return this->rel_irelative_;
976 }
977
978 // Create the PLT section. The ordinary .got section is an argument,
979 // since we need to refer to the start. We also create our own .got
980 // section just for PLT entries.
981
982 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
983 uint64_t addralign,
984 Output_data_space* got_plt,
985 Output_data_space* got_irelative)
986 : Output_section_data(addralign),
987 layout_(layout), tls_desc_rel_(NULL),
988 irelative_rel_(NULL), got_plt_(got_plt), got_irelative_(got_irelative),
989 count_(0), irelative_count_(0), global_ifuncs_(), local_ifuncs_()
990 {
991 this->rel_ = new Reloc_section(false);
992 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
993 elfcpp::SHF_ALLOC, this->rel_,
994 ORDER_DYNAMIC_PLT_RELOCS, false);
995 }
996
997 void
998 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
999 {
1000 // UnixWare sets the entsize of .plt to 4, and so does the old GNU
1001 // linker, and so do we.
1002 os->set_entsize(4);
1003 }
1004
1005 // Add an entry to the PLT.
1006
1007 void
1008 Output_data_plt_i386::add_entry(Symbol_table* symtab, Layout* layout,
1009 Symbol* gsym)
1010 {
1011 gold_assert(!gsym->has_plt_offset());
1012
1013 // Every PLT entry needs a reloc.
1014 if (gsym->type() == elfcpp::STT_GNU_IFUNC
1015 && gsym->can_use_relative_reloc(false))
1016 {
1017 gsym->set_plt_offset(this->irelative_count_ * this->get_plt_entry_size());
1018 ++this->irelative_count_;
1019 section_offset_type got_offset =
1020 this->got_irelative_->current_data_size();
1021 this->got_irelative_->set_current_data_size(got_offset + 4);
1022 Reloc_section* rel = this->rel_irelative(symtab, layout);
1023 rel->add_symbolless_global_addend(gsym, elfcpp::R_386_IRELATIVE,
1024 this->got_irelative_, got_offset);
1025 struct Global_ifunc gi;
1026 gi.sym = gsym;
1027 gi.got_offset = got_offset;
1028 this->global_ifuncs_.push_back(gi);
1029 }
1030 else
1031 {
1032 // When setting the PLT offset we skip the initial reserved PLT
1033 // entry.
1034 gsym->set_plt_offset((this->count_ + 1) * this->get_plt_entry_size());
1035
1036 ++this->count_;
1037
1038 section_offset_type got_offset = this->got_plt_->current_data_size();
1039
1040 // Every PLT entry needs a GOT entry which points back to the
1041 // PLT entry (this will be changed by the dynamic linker,
1042 // normally lazily when the function is called).
1043 this->got_plt_->set_current_data_size(got_offset + 4);
1044
1045 gsym->set_needs_dynsym_entry();
1046 this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
1047 got_offset);
1048 }
1049
1050 // Note that we don't need to save the symbol. The contents of the
1051 // PLT are independent of which symbols are used. The symbols only
1052 // appear in the relocations.
1053 }
1054
1055 // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. Return
1056 // the PLT offset.
1057
1058 unsigned int
1059 Output_data_plt_i386::add_local_ifunc_entry(
1060 Symbol_table* symtab,
1061 Layout* layout,
1062 Sized_relobj_file<32, false>* relobj,
1063 unsigned int local_sym_index)
1064 {
1065 unsigned int plt_offset = this->irelative_count_ * this->get_plt_entry_size();
1066 ++this->irelative_count_;
1067
1068 section_offset_type got_offset = this->got_irelative_->current_data_size();
1069
1070 // Every PLT entry needs a GOT entry which points back to the PLT
1071 // entry.
1072 this->got_irelative_->set_current_data_size(got_offset + 4);
1073
1074 // Every PLT entry needs a reloc.
1075 Reloc_section* rel = this->rel_irelative(symtab, layout);
1076 rel->add_symbolless_local_addend(relobj, local_sym_index,
1077 elfcpp::R_386_IRELATIVE,
1078 this->got_irelative_, got_offset);
1079
1080 struct Local_ifunc li;
1081 li.object = relobj;
1082 li.local_sym_index = local_sym_index;
1083 li.got_offset = got_offset;
1084 this->local_ifuncs_.push_back(li);
1085
1086 return plt_offset;
1087 }
1088
1089 // Return where the TLS_DESC relocations should go, creating it if
1090 // necessary. These follow the JUMP_SLOT relocations.
1091
1092 Output_data_plt_i386::Reloc_section*
1093 Output_data_plt_i386::rel_tls_desc(Layout* layout)
1094 {
1095 if (this->tls_desc_rel_ == NULL)
1096 {
1097 this->tls_desc_rel_ = new Reloc_section(false);
1098 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
1099 elfcpp::SHF_ALLOC, this->tls_desc_rel_,
1100 ORDER_DYNAMIC_PLT_RELOCS, false);
1101 gold_assert(this->tls_desc_rel_->output_section()
1102 == this->rel_->output_section());
1103 }
1104 return this->tls_desc_rel_;
1105 }
1106
1107 // Return where the IRELATIVE relocations should go in the PLT. These
1108 // follow the JUMP_SLOT and TLS_DESC relocations.
1109
1110 Output_data_plt_i386::Reloc_section*
1111 Output_data_plt_i386::rel_irelative(Symbol_table* symtab, Layout* layout)
1112 {
1113 if (this->irelative_rel_ == NULL)
1114 {
1115 // Make sure we have a place for the TLS_DESC relocations, in
1116 // case we see any later on.
1117 this->rel_tls_desc(layout);
1118 this->irelative_rel_ = new Reloc_section(false);
1119 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
1120 elfcpp::SHF_ALLOC, this->irelative_rel_,
1121 ORDER_DYNAMIC_PLT_RELOCS, false);
1122 gold_assert(this->irelative_rel_->output_section()
1123 == this->rel_->output_section());
1124
1125 if (parameters->doing_static_link())
1126 {
1127 // A statically linked executable will only have a .rel.plt
1128 // section to hold R_386_IRELATIVE relocs for STT_GNU_IFUNC
1129 // symbols. The library will use these symbols to locate
1130 // the IRELATIVE relocs at program startup time.
1131 symtab->define_in_output_data("__rel_iplt_start", NULL,
1132 Symbol_table::PREDEFINED,
1133 this->irelative_rel_, 0, 0,
1134 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
1135 elfcpp::STV_HIDDEN, 0, false, true);
1136 symtab->define_in_output_data("__rel_iplt_end", NULL,
1137 Symbol_table::PREDEFINED,
1138 this->irelative_rel_, 0, 0,
1139 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
1140 elfcpp::STV_HIDDEN, 0, true, true);
1141 }
1142 }
1143 return this->irelative_rel_;
1144 }
1145
1146 // Return the PLT address to use for a global symbol.
1147
1148 uint64_t
1149 Output_data_plt_i386::address_for_global(const Symbol* gsym)
1150 {
1151 uint64_t offset = 0;
1152 if (gsym->type() == elfcpp::STT_GNU_IFUNC
1153 && gsym->can_use_relative_reloc(false))
1154 offset = (this->count_ + 1) * this->get_plt_entry_size();
1155 return this->address() + offset + gsym->plt_offset();
1156 }
1157
1158 // Return the PLT address to use for a local symbol. These are always
1159 // IRELATIVE relocs.
1160
1161 uint64_t
1162 Output_data_plt_i386::address_for_local(const Relobj* object,
1163 unsigned int r_sym)
1164 {
1165 return (this->address()
1166 + (this->count_ + 1) * this->get_plt_entry_size()
1167 + object->local_plt_offset(r_sym));
1168 }
1169
1170 // The first entry in the PLT for an executable.
1171
1172 const unsigned char Output_data_plt_i386_exec::first_plt_entry[plt_entry_size] =
1173 {
1174 0xff, 0x35, // pushl contents of memory address
1175 0, 0, 0, 0, // replaced with address of .got + 4
1176 0xff, 0x25, // jmp indirect
1177 0, 0, 0, 0, // replaced with address of .got + 8
1178 0, 0, 0, 0 // unused
1179 };
1180
1181 void
1182 Output_data_plt_i386_exec::do_fill_first_plt_entry(
1183 unsigned char* pov,
1184 elfcpp::Elf_types<32>::Elf_Addr got_address)
1185 {
1186 memcpy(pov, first_plt_entry, plt_entry_size);
1187 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
1188 elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
1189 }
1190
1191 // The first entry in the PLT for a shared object.
1192
1193 const unsigned char Output_data_plt_i386_dyn::first_plt_entry[plt_entry_size] =
1194 {
1195 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
1196 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx)
1197 0, 0, 0, 0 // unused
1198 };
1199
1200 void
1201 Output_data_plt_i386_dyn::do_fill_first_plt_entry(
1202 unsigned char* pov,
1203 elfcpp::Elf_types<32>::Elf_Addr)
1204 {
1205 memcpy(pov, first_plt_entry, plt_entry_size);
1206 }
1207
1208 // Subsequent entries in the PLT for an executable.
1209
1210 const unsigned char Output_data_plt_i386_exec::plt_entry[plt_entry_size] =
1211 {
1212 0xff, 0x25, // jmp indirect
1213 0, 0, 0, 0, // replaced with address of symbol in .got
1214 0x68, // pushl immediate
1215 0, 0, 0, 0, // replaced with offset into relocation table
1216 0xe9, // jmp relative
1217 0, 0, 0, 0 // replaced with offset to start of .plt
1218 };
1219
1220 unsigned int
1221 Output_data_plt_i386_exec::do_fill_plt_entry(
1222 unsigned char* pov,
1223 elfcpp::Elf_types<32>::Elf_Addr got_address,
1224 unsigned int got_offset,
1225 unsigned int plt_offset,
1226 unsigned int plt_rel_offset)
1227 {
1228 memcpy(pov, plt_entry, plt_entry_size);
1229 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
1230 got_address + got_offset);
1231 elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
1232 elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + 12 + 4));
1233 return 6;
1234 }
1235
1236 // Subsequent entries in the PLT for a shared object.
1237
1238 const unsigned char Output_data_plt_i386_dyn::plt_entry[plt_entry_size] =
1239 {
1240 0xff, 0xa3, // jmp *offset(%ebx)
1241 0, 0, 0, 0, // replaced with offset of symbol in .got
1242 0x68, // pushl immediate
1243 0, 0, 0, 0, // replaced with offset into relocation table
1244 0xe9, // jmp relative
1245 0, 0, 0, 0 // replaced with offset to start of .plt
1246 };
1247
1248 unsigned int
1249 Output_data_plt_i386_dyn::do_fill_plt_entry(unsigned char* pov,
1250 elfcpp::Elf_types<32>::Elf_Addr,
1251 unsigned int got_offset,
1252 unsigned int plt_offset,
1253 unsigned int plt_rel_offset)
1254 {
1255 memcpy(pov, plt_entry, plt_entry_size);
1256 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
1257 elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
1258 elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + 12 + 4));
1259 return 6;
1260 }
1261
1262 // The .eh_frame unwind information for the PLT.
1263
1264 const unsigned char
1265 Output_data_plt_i386::plt_eh_frame_cie[plt_eh_frame_cie_size] =
1266 {
1267 1, // CIE version.
1268 'z', // Augmentation: augmentation size included.
1269 'R', // Augmentation: FDE encoding included.
1270 '\0', // End of augmentation string.
1271 1, // Code alignment factor.
1272 0x7c, // Data alignment factor.
1273 8, // Return address column.
1274 1, // Augmentation size.
1275 (elfcpp::DW_EH_PE_pcrel // FDE encoding.
1276 | elfcpp::DW_EH_PE_sdata4),
1277 elfcpp::DW_CFA_def_cfa, 4, 4, // DW_CFA_def_cfa: r4 (esp) ofs 4.
1278 elfcpp::DW_CFA_offset + 8, 1, // DW_CFA_offset: r8 (eip) at cfa-4.
1279 elfcpp::DW_CFA_nop, // Align to 16 bytes.
1280 elfcpp::DW_CFA_nop
1281 };
1282
1283 const unsigned char
1284 Output_data_plt_i386_standard::plt_eh_frame_fde[plt_eh_frame_fde_size] =
1285 {
1286 0, 0, 0, 0, // Replaced with offset to .plt.
1287 0, 0, 0, 0, // Replaced with size of .plt.
1288 0, // Augmentation size.
1289 elfcpp::DW_CFA_def_cfa_offset, 8, // DW_CFA_def_cfa_offset: 8.
1290 elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
1291 elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
1292 elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16.
1293 elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
1294 11, // Block length.
1295 elfcpp::DW_OP_breg4, 4, // Push %esp + 4.
1296 elfcpp::DW_OP_breg8, 0, // Push %eip.
1297 elfcpp::DW_OP_lit15, // Push 0xf.
1298 elfcpp::DW_OP_and, // & (%eip & 0xf).
1299 elfcpp::DW_OP_lit11, // Push 0xb.
1300 elfcpp::DW_OP_ge, // >= ((%eip & 0xf) >= 0xb)
1301 elfcpp::DW_OP_lit2, // Push 2.
1302 elfcpp::DW_OP_shl, // << (((%eip & 0xf) >= 0xb) << 2)
1303 elfcpp::DW_OP_plus, // + ((((%eip&0xf)>=0xb)<<2)+%esp+4
1304 elfcpp::DW_CFA_nop, // Align to 32 bytes.
1305 elfcpp::DW_CFA_nop,
1306 elfcpp::DW_CFA_nop,
1307 elfcpp::DW_CFA_nop
1308 };
1309
1310 // Write out the PLT. This uses the hand-coded instructions above,
1311 // and adjusts them as needed. This is all specified by the i386 ELF
1312 // Processor Supplement.
1313
1314 void
1315 Output_data_plt_i386::do_write(Output_file* of)
1316 {
1317 const off_t offset = this->offset();
1318 const section_size_type oview_size =
1319 convert_to_section_size_type(this->data_size());
1320 unsigned char* const oview = of->get_output_view(offset, oview_size);
1321
1322 const off_t got_file_offset = this->got_plt_->offset();
1323 gold_assert(parameters->incremental_update()
1324 || (got_file_offset + this->got_plt_->data_size()
1325 == this->got_irelative_->offset()));
1326 const section_size_type got_size =
1327 convert_to_section_size_type(this->got_plt_->data_size()
1328 + this->got_irelative_->data_size());
1329 unsigned char* const got_view = of->get_output_view(got_file_offset,
1330 got_size);
1331
1332 unsigned char* pov = oview;
1333
1334 elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
1335 elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
1336
1337 this->fill_first_plt_entry(pov, got_address);
1338 pov += this->get_plt_entry_size();
1339
1340 unsigned char* got_pov = got_view;
1341
1342 // The first entry in the GOT is the address of the .dynamic section
1343 // aka the PT_DYNAMIC segment. The next two entries are reserved.
1344 // We saved space for them when we created the section in
1345 // Target_i386::got_section.
1346 Output_section* dynamic = this->layout_->dynamic_section();
1347 uint32_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
1348 elfcpp::Swap<32, false>::writeval(got_pov, dynamic_addr);
1349 got_pov += 4;
1350 memset(got_pov, 0, 8);
1351 got_pov += 8;
1352
1353 const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
1354
1355 unsigned int plt_offset = this->get_plt_entry_size();
1356 unsigned int plt_rel_offset = 0;
1357 unsigned int got_offset = 12;
1358 const unsigned int count = this->count_ + this->irelative_count_;
1359 for (unsigned int i = 0;
1360 i < count;
1361 ++i,
1362 pov += this->get_plt_entry_size(),
1363 got_pov += 4,
1364 plt_offset += this->get_plt_entry_size(),
1365 plt_rel_offset += rel_size,
1366 got_offset += 4)
1367 {
1368 // Set and adjust the PLT entry itself.
1369 unsigned int lazy_offset = this->fill_plt_entry(pov,
1370 got_address,
1371 got_offset,
1372 plt_offset,
1373 plt_rel_offset);
1374
1375 // Set the entry in the GOT.
1376 elfcpp::Swap<32, false>::writeval(got_pov,
1377 plt_address + plt_offset + lazy_offset);
1378 }
1379
1380 // If any STT_GNU_IFUNC symbols have PLT entries, we need to change
1381 // the GOT to point to the actual symbol value, rather than point to
1382 // the PLT entry. That will let the dynamic linker call the right
1383 // function when resolving IRELATIVE relocations.
1384 unsigned char* got_irelative_view = got_view + this->got_plt_->data_size();
1385 for (std::vector<Global_ifunc>::const_iterator p =
1386 this->global_ifuncs_.begin();
1387 p != this->global_ifuncs_.end();
1388 ++p)
1389 {
1390 const Sized_symbol<32>* ssym =
1391 static_cast<const Sized_symbol<32>*>(p->sym);
1392 elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
1393 ssym->value());
1394 }
1395
1396 for (std::vector<Local_ifunc>::const_iterator p =
1397 this->local_ifuncs_.begin();
1398 p != this->local_ifuncs_.end();
1399 ++p)
1400 {
1401 const Symbol_value<32>* psymval =
1402 p->object->local_symbol(p->local_sym_index);
1403 elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
1404 psymval->value(p->object, 0));
1405 }
1406
1407 gold_assert(static_cast<section_size_type>(pov - oview) == oview_size);
1408 gold_assert(static_cast<section_size_type>(got_pov - got_view) == got_size);
1409
1410 of->write_output_view(offset, oview_size, oview);
1411 of->write_output_view(got_file_offset, got_size, got_view);
1412 }
1413
1414 // Create the PLT section.
1415
1416 void
1417 Target_i386::make_plt_section(Symbol_table* symtab, Layout* layout)
1418 {
1419 if (this->plt_ == NULL)
1420 {
1421 // Create the GOT sections first.
1422 this->got_section(symtab, layout);
1423
1424 const bool dyn = parameters->options().output_is_position_independent();
1425 this->plt_ = this->make_data_plt(layout,
1426 this->got_plt_,
1427 this->got_irelative_,
1428 dyn);
1429
1430 // Add unwind information if requested.
1431 if (parameters->options().ld_generated_unwind_info())
1432 this->plt_->add_eh_frame(layout);
1433
1434 layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
1435 (elfcpp::SHF_ALLOC
1436 | elfcpp::SHF_EXECINSTR),
1437 this->plt_, ORDER_PLT, false);
1438
1439 // Make the sh_info field of .rel.plt point to .plt.
1440 Output_section* rel_plt_os = this->plt_->rel_plt()->output_section();
1441 rel_plt_os->set_info_section(this->plt_->output_section());
1442 }
1443 }
1444
1445 // Create a PLT entry for a global symbol.
1446
1447 void
1448 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
1449 {
1450 if (gsym->has_plt_offset())
1451 return;
1452 if (this->plt_ == NULL)
1453 this->make_plt_section(symtab, layout);
1454 this->plt_->add_entry(symtab, layout, gsym);
1455 }
1456
1457 // Make a PLT entry for a local STT_GNU_IFUNC symbol.
1458
1459 void
1460 Target_i386::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout,
1461 Sized_relobj_file<32, false>* relobj,
1462 unsigned int local_sym_index)
1463 {
1464 if (relobj->local_has_plt_offset(local_sym_index))
1465 return;
1466 if (this->plt_ == NULL)
1467 this->make_plt_section(symtab, layout);
1468 unsigned int plt_offset = this->plt_->add_local_ifunc_entry(symtab, layout,
1469 relobj,
1470 local_sym_index);
1471 relobj->set_local_plt_offset(local_sym_index, plt_offset);
1472 }
1473
1474 // Return the number of entries in the PLT.
1475
1476 unsigned int
1477 Target_i386::plt_entry_count() const
1478 {
1479 if (this->plt_ == NULL)
1480 return 0;
1481 return this->plt_->entry_count();
1482 }
1483
1484 // Return the offset of the first non-reserved PLT entry.
1485
1486 unsigned int
1487 Target_i386::first_plt_entry_offset() const
1488 {
1489 return this->plt_->first_plt_entry_offset();
1490 }
1491
1492 // Return the size of each PLT entry.
1493
1494 unsigned int
1495 Target_i386::plt_entry_size() const
1496 {
1497 return this->plt_->get_plt_entry_size();
1498 }
1499
1500 // Get the section to use for TLS_DESC relocations.
1501
1502 Target_i386::Reloc_section*
1503 Target_i386::rel_tls_desc_section(Layout* layout) const
1504 {
1505 return this->plt_section()->rel_tls_desc(layout);
1506 }
1507
1508 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
1509
1510 void
1511 Target_i386::define_tls_base_symbol(Symbol_table* symtab, Layout* layout)
1512 {
1513 if (this->tls_base_symbol_defined_)
1514 return;
1515
1516 Output_segment* tls_segment = layout->tls_segment();
1517 if (tls_segment != NULL)
1518 {
1519 bool is_exec = parameters->options().output_is_executable();
1520 symtab->define_in_output_segment("_TLS_MODULE_BASE_", NULL,
1521 Symbol_table::PREDEFINED,
1522 tls_segment, 0, 0,
1523 elfcpp::STT_TLS,
1524 elfcpp::STB_LOCAL,
1525 elfcpp::STV_HIDDEN, 0,
1526 (is_exec
1527 ? Symbol::SEGMENT_END
1528 : Symbol::SEGMENT_START),
1529 true);
1530 }
1531 this->tls_base_symbol_defined_ = true;
1532 }
1533
1534 // Create a GOT entry for the TLS module index.
1535
1536 unsigned int
1537 Target_i386::got_mod_index_entry(Symbol_table* symtab, Layout* layout,
1538 Sized_relobj_file<32, false>* object)
1539 {
1540 if (this->got_mod_index_offset_ == -1U)
1541 {
1542 gold_assert(symtab != NULL && layout != NULL && object != NULL);
1543 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1544 Output_data_got<32, false>* got = this->got_section(symtab, layout);
1545 unsigned int got_offset = got->add_constant(0);
1546 rel_dyn->add_local(object, 0, elfcpp::R_386_TLS_DTPMOD32, got,
1547 got_offset);
1548 got->add_constant(0);
1549 this->got_mod_index_offset_ = got_offset;
1550 }
1551 return this->got_mod_index_offset_;
1552 }
1553
1554 // Optimize the TLS relocation type based on what we know about the
1555 // symbol. IS_FINAL is true if the final address of this symbol is
1556 // known at link time.
1557
1558 tls::Tls_optimization
1559 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
1560 {
1561 // If we are generating a shared library, then we can't do anything
1562 // in the linker.
1563 if (parameters->options().shared())
1564 return tls::TLSOPT_NONE;
1565
1566 switch (r_type)
1567 {
1568 case elfcpp::R_386_TLS_GD:
1569 case elfcpp::R_386_TLS_GOTDESC:
1570 case elfcpp::R_386_TLS_DESC_CALL:
1571 // These are General-Dynamic which permits fully general TLS
1572 // access. Since we know that we are generating an executable,
1573 // we can convert this to Initial-Exec. If we also know that
1574 // this is a local symbol, we can further switch to Local-Exec.
1575 if (is_final)
1576 return tls::TLSOPT_TO_LE;
1577 return tls::TLSOPT_TO_IE;
1578
1579 case elfcpp::R_386_TLS_LDM:
1580 // This is Local-Dynamic, which refers to a local symbol in the
1581 // dynamic TLS block. Since we know that we generating an
1582 // executable, we can switch to Local-Exec.
1583 return tls::TLSOPT_TO_LE;
1584
1585 case elfcpp::R_386_TLS_LDO_32:
1586 // Another type of Local-Dynamic relocation.
1587 return tls::TLSOPT_TO_LE;
1588
1589 case elfcpp::R_386_TLS_IE:
1590 case elfcpp::R_386_TLS_GOTIE:
1591 case elfcpp::R_386_TLS_IE_32:
1592 // These are Initial-Exec relocs which get the thread offset
1593 // from the GOT. If we know that we are linking against the
1594 // local symbol, we can switch to Local-Exec, which links the
1595 // thread offset into the instruction.
1596 if (is_final)
1597 return tls::TLSOPT_TO_LE;
1598 return tls::TLSOPT_NONE;
1599
1600 case elfcpp::R_386_TLS_LE:
1601 case elfcpp::R_386_TLS_LE_32:
1602 // When we already have Local-Exec, there is nothing further we
1603 // can do.
1604 return tls::TLSOPT_NONE;
1605
1606 default:
1607 gold_unreachable();
1608 }
1609 }
1610
1611 // Get the Reference_flags for a particular relocation.
1612
1613 int
1614 Target_i386::Scan::get_reference_flags(unsigned int r_type)
1615 {
1616 switch (r_type)
1617 {
1618 case elfcpp::R_386_NONE:
1619 case elfcpp::R_386_GNU_VTINHERIT:
1620 case elfcpp::R_386_GNU_VTENTRY:
1621 case elfcpp::R_386_GOTPC:
1622 // No symbol reference.
1623 return 0;
1624
1625 case elfcpp::R_386_32:
1626 case elfcpp::R_386_16:
1627 case elfcpp::R_386_8:
1628 return Symbol::ABSOLUTE_REF;
1629
1630 case elfcpp::R_386_PC32:
1631 case elfcpp::R_386_PC16:
1632 case elfcpp::R_386_PC8:
1633 case elfcpp::R_386_GOTOFF:
1634 return Symbol::RELATIVE_REF;
1635
1636 case elfcpp::R_386_PLT32:
1637 return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF;
1638
1639 case elfcpp::R_386_GOT32:
1640 // Absolute in GOT.
1641 return Symbol::ABSOLUTE_REF;
1642
1643 case elfcpp::R_386_TLS_GD: // Global-dynamic
1644 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1645 case elfcpp::R_386_TLS_DESC_CALL:
1646 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1647 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1648 case elfcpp::R_386_TLS_IE: // Initial-exec
1649 case elfcpp::R_386_TLS_IE_32:
1650 case elfcpp::R_386_TLS_GOTIE:
1651 case elfcpp::R_386_TLS_LE: // Local-exec
1652 case elfcpp::R_386_TLS_LE_32:
1653 return Symbol::TLS_REF;
1654
1655 case elfcpp::R_386_COPY:
1656 case elfcpp::R_386_GLOB_DAT:
1657 case elfcpp::R_386_JUMP_SLOT:
1658 case elfcpp::R_386_RELATIVE:
1659 case elfcpp::R_386_IRELATIVE:
1660 case elfcpp::R_386_TLS_TPOFF:
1661 case elfcpp::R_386_TLS_DTPMOD32:
1662 case elfcpp::R_386_TLS_DTPOFF32:
1663 case elfcpp::R_386_TLS_TPOFF32:
1664 case elfcpp::R_386_TLS_DESC:
1665 case elfcpp::R_386_32PLT:
1666 case elfcpp::R_386_TLS_GD_32:
1667 case elfcpp::R_386_TLS_GD_PUSH:
1668 case elfcpp::R_386_TLS_GD_CALL:
1669 case elfcpp::R_386_TLS_GD_POP:
1670 case elfcpp::R_386_TLS_LDM_32:
1671 case elfcpp::R_386_TLS_LDM_PUSH:
1672 case elfcpp::R_386_TLS_LDM_CALL:
1673 case elfcpp::R_386_TLS_LDM_POP:
1674 case elfcpp::R_386_USED_BY_INTEL_200:
1675 default:
1676 // Not expected. We will give an error later.
1677 return 0;
1678 }
1679 }
1680
1681 // Report an unsupported relocation against a local symbol.
1682
1683 void
1684 Target_i386::Scan::unsupported_reloc_local(Sized_relobj_file<32, false>* object,
1685 unsigned int r_type)
1686 {
1687 gold_error(_("%s: unsupported reloc %u against local symbol"),
1688 object->name().c_str(), r_type);
1689 }
1690
1691 // Return whether we need to make a PLT entry for a relocation of a
1692 // given type against a STT_GNU_IFUNC symbol.
1693
1694 bool
1695 Target_i386::Scan::reloc_needs_plt_for_ifunc(
1696 Sized_relobj_file<32, false>* object,
1697 unsigned int r_type)
1698 {
1699 int flags = Scan::get_reference_flags(r_type);
1700 if (flags & Symbol::TLS_REF)
1701 gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"),
1702 object->name().c_str(), r_type);
1703 return flags != 0;
1704 }
1705
1706 // Scan a relocation for a local symbol.
1707
1708 inline void
1709 Target_i386::Scan::local(Symbol_table* symtab,
1710 Layout* layout,
1711 Target_i386* target,
1712 Sized_relobj_file<32, false>* object,
1713 unsigned int data_shndx,
1714 Output_section* output_section,
1715 const elfcpp::Rel<32, false>& reloc,
1716 unsigned int r_type,
1717 const elfcpp::Sym<32, false>& lsym,
1718 bool is_discarded)
1719 {
1720 if (is_discarded)
1721 return;
1722
1723 // A local STT_GNU_IFUNC symbol may require a PLT entry.
1724 if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC
1725 && this->reloc_needs_plt_for_ifunc(object, r_type))
1726 {
1727 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1728 target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym);
1729 }
1730
1731 switch (r_type)
1732 {
1733 case elfcpp::R_386_NONE:
1734 case elfcpp::R_386_GNU_VTINHERIT:
1735 case elfcpp::R_386_GNU_VTENTRY:
1736 break;
1737
1738 case elfcpp::R_386_32:
1739 // If building a shared library (or a position-independent
1740 // executable), we need to create a dynamic relocation for
1741 // this location. The relocation applied at link time will
1742 // apply the link-time value, so we flag the location with
1743 // an R_386_RELATIVE relocation so the dynamic loader can
1744 // relocate it easily.
1745 if (parameters->options().output_is_position_independent())
1746 {
1747 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1748 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1749 rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE,
1750 output_section, data_shndx,
1751 reloc.get_r_offset());
1752 }
1753 break;
1754
1755 case elfcpp::R_386_16:
1756 case elfcpp::R_386_8:
1757 // If building a shared library (or a position-independent
1758 // executable), we need to create a dynamic relocation for
1759 // this location. Because the addend needs to remain in the
1760 // data section, we need to be careful not to apply this
1761 // relocation statically.
1762 if (parameters->options().output_is_position_independent())
1763 {
1764 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1765 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1766 if (lsym.get_st_type() != elfcpp::STT_SECTION)
1767 rel_dyn->add_local(object, r_sym, r_type, output_section,
1768 data_shndx, reloc.get_r_offset());
1769 else
1770 {
1771 gold_assert(lsym.get_st_value() == 0);
1772 unsigned int shndx = lsym.get_st_shndx();
1773 bool is_ordinary;
1774 shndx = object->adjust_sym_shndx(r_sym, shndx,
1775 &is_ordinary);
1776 if (!is_ordinary)
1777 object->error(_("section symbol %u has bad shndx %u"),
1778 r_sym, shndx);
1779 else
1780 rel_dyn->add_local_section(object, shndx,
1781 r_type, output_section,
1782 data_shndx, reloc.get_r_offset());
1783 }
1784 }
1785 break;
1786
1787 case elfcpp::R_386_PC32:
1788 case elfcpp::R_386_PC16:
1789 case elfcpp::R_386_PC8:
1790 break;
1791
1792 case elfcpp::R_386_PLT32:
1793 // Since we know this is a local symbol, we can handle this as a
1794 // PC32 reloc.
1795 break;
1796
1797 case elfcpp::R_386_GOTOFF:
1798 case elfcpp::R_386_GOTPC:
1799 // We need a GOT section.
1800 target->got_section(symtab, layout);
1801 break;
1802
1803 case elfcpp::R_386_GOT32:
1804 {
1805 // The symbol requires a GOT entry.
1806 Output_data_got<32, false>* got = target->got_section(symtab, layout);
1807 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1808
1809 // For a STT_GNU_IFUNC symbol we want the PLT offset. That
1810 // lets function pointers compare correctly with shared
1811 // libraries. Otherwise we would need an IRELATIVE reloc.
1812 bool is_new;
1813 if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC)
1814 is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD);
1815 else
1816 is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD);
1817 if (is_new)
1818 {
1819 // If we are generating a shared object, we need to add a
1820 // dynamic RELATIVE relocation for this symbol's GOT entry.
1821 if (parameters->options().output_is_position_independent())
1822 {
1823 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1824 unsigned int got_offset =
1825 object->local_got_offset(r_sym, GOT_TYPE_STANDARD);
1826 rel_dyn->add_local_relative(object, r_sym,
1827 elfcpp::R_386_RELATIVE,
1828 got, got_offset);
1829 }
1830 }
1831 }
1832 break;
1833
1834 // These are relocations which should only be seen by the
1835 // dynamic linker, and should never be seen here.
1836 case elfcpp::R_386_COPY:
1837 case elfcpp::R_386_GLOB_DAT:
1838 case elfcpp::R_386_JUMP_SLOT:
1839 case elfcpp::R_386_RELATIVE:
1840 case elfcpp::R_386_IRELATIVE:
1841 case elfcpp::R_386_TLS_TPOFF:
1842 case elfcpp::R_386_TLS_DTPMOD32:
1843 case elfcpp::R_386_TLS_DTPOFF32:
1844 case elfcpp::R_386_TLS_TPOFF32:
1845 case elfcpp::R_386_TLS_DESC:
1846 gold_error(_("%s: unexpected reloc %u in object file"),
1847 object->name().c_str(), r_type);
1848 break;
1849
1850 // These are initial TLS relocs, which are expected when
1851 // linking.
1852 case elfcpp::R_386_TLS_GD: // Global-dynamic
1853 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1854 case elfcpp::R_386_TLS_DESC_CALL:
1855 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1856 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1857 case elfcpp::R_386_TLS_IE: // Initial-exec
1858 case elfcpp::R_386_TLS_IE_32:
1859 case elfcpp::R_386_TLS_GOTIE:
1860 case elfcpp::R_386_TLS_LE: // Local-exec
1861 case elfcpp::R_386_TLS_LE_32:
1862 {
1863 bool output_is_shared = parameters->options().shared();
1864 const tls::Tls_optimization optimized_type
1865 = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
1866 switch (r_type)
1867 {
1868 case elfcpp::R_386_TLS_GD: // Global-dynamic
1869 if (optimized_type == tls::TLSOPT_NONE)
1870 {
1871 // Create a pair of GOT entries for the module index and
1872 // dtv-relative offset.
1873 Output_data_got<32, false>* got
1874 = target->got_section(symtab, layout);
1875 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1876 unsigned int shndx = lsym.get_st_shndx();
1877 bool is_ordinary;
1878 shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
1879 if (!is_ordinary)
1880 object->error(_("local symbol %u has bad shndx %u"),
1881 r_sym, shndx);
1882 else
1883 got->add_local_pair_with_rel(object, r_sym, shndx,
1884 GOT_TYPE_TLS_PAIR,
1885 target->rel_dyn_section(layout),
1886 elfcpp::R_386_TLS_DTPMOD32);
1887 }
1888 else if (optimized_type != tls::TLSOPT_TO_LE)
1889 unsupported_reloc_local(object, r_type);
1890 break;
1891
1892 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva)
1893 target->define_tls_base_symbol(symtab, layout);
1894 if (optimized_type == tls::TLSOPT_NONE)
1895 {
1896 // Create a double GOT entry with an R_386_TLS_DESC
1897 // reloc. The R_386_TLS_DESC reloc is resolved
1898 // lazily, so the GOT entry needs to be in an area in
1899 // .got.plt, not .got. Call got_section to make sure
1900 // the section has been created.
1901 target->got_section(symtab, layout);
1902 Output_data_got<32, false>* got = target->got_tlsdesc_section();
1903 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1904 if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC))
1905 {
1906 unsigned int got_offset = got->add_constant(0);
1907 // The local symbol value is stored in the second
1908 // GOT entry.
1909 got->add_local(object, r_sym, GOT_TYPE_TLS_DESC);
1910 // That set the GOT offset of the local symbol to
1911 // point to the second entry, but we want it to
1912 // point to the first.
1913 object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC,
1914 got_offset);
1915 Reloc_section* rt = target->rel_tls_desc_section(layout);
1916 rt->add_absolute(elfcpp::R_386_TLS_DESC, got, got_offset);
1917 }
1918 }
1919 else if (optimized_type != tls::TLSOPT_TO_LE)
1920 unsupported_reloc_local(object, r_type);
1921 break;
1922
1923 case elfcpp::R_386_TLS_DESC_CALL:
1924 break;
1925
1926 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1927 if (optimized_type == tls::TLSOPT_NONE)
1928 {
1929 // Create a GOT entry for the module index.
1930 target->got_mod_index_entry(symtab, layout, object);
1931 }
1932 else if (optimized_type != tls::TLSOPT_TO_LE)
1933 unsupported_reloc_local(object, r_type);
1934 break;
1935
1936 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1937 break;
1938
1939 case elfcpp::R_386_TLS_IE: // Initial-exec
1940 case elfcpp::R_386_TLS_IE_32:
1941 case elfcpp::R_386_TLS_GOTIE:
1942 layout->set_has_static_tls();
1943 if (optimized_type == tls::TLSOPT_NONE)
1944 {
1945 // For the R_386_TLS_IE relocation, we need to create a
1946 // dynamic relocation when building a shared library.
1947 if (r_type == elfcpp::R_386_TLS_IE
1948 && parameters->options().shared())
1949 {
1950 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1951 unsigned int r_sym
1952 = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1953 rel_dyn->add_local_relative(object, r_sym,
1954 elfcpp::R_386_RELATIVE,
1955 output_section, data_shndx,
1956 reloc.get_r_offset());
1957 }
1958 // Create a GOT entry for the tp-relative offset.
1959 Output_data_got<32, false>* got
1960 = target->got_section(symtab, layout);
1961 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1962 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
1963 ? elfcpp::R_386_TLS_TPOFF32
1964 : elfcpp::R_386_TLS_TPOFF);
1965 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
1966 ? GOT_TYPE_TLS_OFFSET
1967 : GOT_TYPE_TLS_NOFFSET);
1968 got->add_local_with_rel(object, r_sym, got_type,
1969 target->rel_dyn_section(layout),
1970 dyn_r_type);
1971 }
1972 else if (optimized_type != tls::TLSOPT_TO_LE)
1973 unsupported_reloc_local(object, r_type);
1974 break;
1975
1976 case elfcpp::R_386_TLS_LE: // Local-exec
1977 case elfcpp::R_386_TLS_LE_32:
1978 layout->set_has_static_tls();
1979 if (output_is_shared)
1980 {
1981 // We need to create a dynamic relocation.
1982 gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION);
1983 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1984 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
1985 ? elfcpp::R_386_TLS_TPOFF32
1986 : elfcpp::R_386_TLS_TPOFF);
1987 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1988 rel_dyn->add_local(object, r_sym, dyn_r_type, output_section,
1989 data_shndx, reloc.get_r_offset());
1990 }
1991 break;
1992
1993 default:
1994 gold_unreachable();
1995 }
1996 }
1997 break;
1998
1999 case elfcpp::R_386_32PLT:
2000 case elfcpp::R_386_TLS_GD_32:
2001 case elfcpp::R_386_TLS_GD_PUSH:
2002 case elfcpp::R_386_TLS_GD_CALL:
2003 case elfcpp::R_386_TLS_GD_POP:
2004 case elfcpp::R_386_TLS_LDM_32:
2005 case elfcpp::R_386_TLS_LDM_PUSH:
2006 case elfcpp::R_386_TLS_LDM_CALL:
2007 case elfcpp::R_386_TLS_LDM_POP:
2008 case elfcpp::R_386_USED_BY_INTEL_200:
2009 default:
2010 unsupported_reloc_local(object, r_type);
2011 break;
2012 }
2013 }
2014
2015 // Report an unsupported relocation against a global symbol.
2016
2017 void
2018 Target_i386::Scan::unsupported_reloc_global(
2019 Sized_relobj_file<32, false>* object,
2020 unsigned int r_type,
2021 Symbol* gsym)
2022 {
2023 gold_error(_("%s: unsupported reloc %u against global symbol %s"),
2024 object->name().c_str(), r_type, gsym->demangled_name().c_str());
2025 }
2026
2027 inline bool
2028 Target_i386::Scan::possible_function_pointer_reloc(unsigned int r_type)
2029 {
2030 switch (r_type)
2031 {
2032 case elfcpp::R_386_32:
2033 case elfcpp::R_386_16:
2034 case elfcpp::R_386_8:
2035 case elfcpp::R_386_GOTOFF:
2036 case elfcpp::R_386_GOT32:
2037 {
2038 return true;
2039 }
2040 default:
2041 return false;
2042 }
2043 return false;
2044 }
2045
2046 inline bool
2047 Target_i386::Scan::local_reloc_may_be_function_pointer(
2048 Symbol_table* ,
2049 Layout* ,
2050 Target_i386* ,
2051 Sized_relobj_file<32, false>* ,
2052 unsigned int ,
2053 Output_section* ,
2054 const elfcpp::Rel<32, false>& ,
2055 unsigned int r_type,
2056 const elfcpp::Sym<32, false>&)
2057 {
2058 return possible_function_pointer_reloc(r_type);
2059 }
2060
2061 inline bool
2062 Target_i386::Scan::global_reloc_may_be_function_pointer(
2063 Symbol_table* ,
2064 Layout* ,
2065 Target_i386* ,
2066 Sized_relobj_file<32, false>* ,
2067 unsigned int ,
2068 Output_section* ,
2069 const elfcpp::Rel<32, false>& ,
2070 unsigned int r_type,
2071 Symbol*)
2072 {
2073 return possible_function_pointer_reloc(r_type);
2074 }
2075
2076 // Scan a relocation for a global symbol.
2077
2078 inline void
2079 Target_i386::Scan::global(Symbol_table* symtab,
2080 Layout* layout,
2081 Target_i386* target,
2082 Sized_relobj_file<32, false>* object,
2083 unsigned int data_shndx,
2084 Output_section* output_section,
2085 const elfcpp::Rel<32, false>& reloc,
2086 unsigned int r_type,
2087 Symbol* gsym)
2088 {
2089 // A STT_GNU_IFUNC symbol may require a PLT entry.
2090 if (gsym->type() == elfcpp::STT_GNU_IFUNC
2091 && this->reloc_needs_plt_for_ifunc(object, r_type))
2092 target->make_plt_entry(symtab, layout, gsym);
2093
2094 switch (r_type)
2095 {
2096 case elfcpp::R_386_NONE:
2097 case elfcpp::R_386_GNU_VTINHERIT:
2098 case elfcpp::R_386_GNU_VTENTRY:
2099 break;
2100
2101 case elfcpp::R_386_32:
2102 case elfcpp::R_386_16:
2103 case elfcpp::R_386_8:
2104 {
2105 // Make a PLT entry if necessary.
2106 if (gsym->needs_plt_entry())
2107 {
2108 target->make_plt_entry(symtab, layout, gsym);
2109 // Since this is not a PC-relative relocation, we may be
2110 // taking the address of a function. In that case we need to
2111 // set the entry in the dynamic symbol table to the address of
2112 // the PLT entry.
2113 if (gsym->is_from_dynobj() && !parameters->options().shared())
2114 gsym->set_needs_dynsym_value();
2115 }
2116 // Make a dynamic relocation if necessary.
2117 if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
2118 {
2119 if (gsym->may_need_copy_reloc())
2120 {
2121 target->copy_reloc(symtab, layout, object,
2122 data_shndx, output_section, gsym, reloc);
2123 }
2124 else if (r_type == elfcpp::R_386_32
2125 && gsym->type() == elfcpp::STT_GNU_IFUNC
2126 && gsym->can_use_relative_reloc(false)
2127 && !gsym->is_from_dynobj()
2128 && !gsym->is_undefined()
2129 && !gsym->is_preemptible())
2130 {
2131 // Use an IRELATIVE reloc for a locally defined
2132 // STT_GNU_IFUNC symbol. This makes a function
2133 // address in a PIE executable match the address in a
2134 // shared library that it links against.
2135 Reloc_section* rel_dyn = target->rel_irelative_section(layout);
2136 rel_dyn->add_symbolless_global_addend(gsym,
2137 elfcpp::R_386_IRELATIVE,
2138 output_section,
2139 object, data_shndx,
2140 reloc.get_r_offset());
2141 }
2142 else if (r_type == elfcpp::R_386_32
2143 && gsym->can_use_relative_reloc(false))
2144 {
2145 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2146 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2147 output_section, object,
2148 data_shndx, reloc.get_r_offset());
2149 }
2150 else
2151 {
2152 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2153 rel_dyn->add_global(gsym, r_type, output_section, object,
2154 data_shndx, reloc.get_r_offset());
2155 }
2156 }
2157 }
2158 break;
2159
2160 case elfcpp::R_386_PC32:
2161 case elfcpp::R_386_PC16:
2162 case elfcpp::R_386_PC8:
2163 {
2164 // Make a PLT entry if necessary.
2165 if (gsym->needs_plt_entry())
2166 {
2167 // These relocations are used for function calls only in
2168 // non-PIC code. For a 32-bit relocation in a shared library,
2169 // we'll need a text relocation anyway, so we can skip the
2170 // PLT entry and let the dynamic linker bind the call directly
2171 // to the target. For smaller relocations, we should use a
2172 // PLT entry to ensure that the call can reach.
2173 if (!parameters->options().shared()
2174 || r_type != elfcpp::R_386_PC32)
2175 target->make_plt_entry(symtab, layout, gsym);
2176 }
2177 // Make a dynamic relocation if necessary.
2178 if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
2179 {
2180 if (gsym->may_need_copy_reloc())
2181 {
2182 target->copy_reloc(symtab, layout, object,
2183 data_shndx, output_section, gsym, reloc);
2184 }
2185 else
2186 {
2187 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2188 rel_dyn->add_global(gsym, r_type, output_section, object,
2189 data_shndx, reloc.get_r_offset());
2190 }
2191 }
2192 }
2193 break;
2194
2195 case elfcpp::R_386_GOT32:
2196 {
2197 // The symbol requires a GOT entry.
2198 Output_data_got<32, false>* got = target->got_section(symtab, layout);
2199 if (gsym->final_value_is_known())
2200 {
2201 // For a STT_GNU_IFUNC symbol we want the PLT address.
2202 if (gsym->type() == elfcpp::STT_GNU_IFUNC)
2203 got->add_global_plt(gsym, GOT_TYPE_STANDARD);
2204 else
2205 got->add_global(gsym, GOT_TYPE_STANDARD);
2206 }
2207 else
2208 {
2209 // If this symbol is not fully resolved, we need to add a
2210 // GOT entry with a dynamic relocation.
2211 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2212
2213 // Use a GLOB_DAT rather than a RELATIVE reloc if:
2214 //
2215 // 1) The symbol may be defined in some other module.
2216 //
2217 // 2) We are building a shared library and this is a
2218 // protected symbol; using GLOB_DAT means that the dynamic
2219 // linker can use the address of the PLT in the main
2220 // executable when appropriate so that function address
2221 // comparisons work.
2222 //
2223 // 3) This is a STT_GNU_IFUNC symbol in position dependent
2224 // code, again so that function address comparisons work.
2225 if (gsym->is_from_dynobj()
2226 || gsym->is_undefined()
2227 || gsym->is_preemptible()
2228 || (gsym->visibility() == elfcpp::STV_PROTECTED
2229 && parameters->options().shared())
2230 || (gsym->type() == elfcpp::STT_GNU_IFUNC
2231 && parameters->options().output_is_position_independent()))
2232 got->add_global_with_rel(gsym, GOT_TYPE_STANDARD,
2233 rel_dyn, elfcpp::R_386_GLOB_DAT);
2234 else
2235 {
2236 // For a STT_GNU_IFUNC symbol we want to write the PLT
2237 // offset into the GOT, so that function pointer
2238 // comparisons work correctly.
2239 bool is_new;
2240 if (gsym->type() != elfcpp::STT_GNU_IFUNC)
2241 is_new = got->add_global(gsym, GOT_TYPE_STANDARD);
2242 else
2243 {
2244 is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD);
2245 // Tell the dynamic linker to use the PLT address
2246 // when resolving relocations.
2247 if (gsym->is_from_dynobj()
2248 && !parameters->options().shared())
2249 gsym->set_needs_dynsym_value();
2250 }
2251 if (is_new)
2252 {
2253 unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD);
2254 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2255 got, got_off);
2256 }
2257 }
2258 }
2259 }
2260 break;
2261
2262 case elfcpp::R_386_PLT32:
2263 // If the symbol is fully resolved, this is just a PC32 reloc.
2264 // Otherwise we need a PLT entry.
2265 if (gsym->final_value_is_known())
2266 break;
2267 // If building a shared library, we can also skip the PLT entry
2268 // if the symbol is defined in the output file and is protected
2269 // or hidden.
2270 if (gsym->is_defined()
2271 && !gsym->is_from_dynobj()
2272 && !gsym->is_preemptible())
2273 break;
2274 target->make_plt_entry(symtab, layout, gsym);
2275 break;
2276
2277 case elfcpp::R_386_GOTOFF:
2278 case elfcpp::R_386_GOTPC:
2279 // We need a GOT section.
2280 target->got_section(symtab, layout);
2281 break;
2282
2283 // These are relocations which should only be seen by the
2284 // dynamic linker, and should never be seen here.
2285 case elfcpp::R_386_COPY:
2286 case elfcpp::R_386_GLOB_DAT:
2287 case elfcpp::R_386_JUMP_SLOT:
2288 case elfcpp::R_386_RELATIVE:
2289 case elfcpp::R_386_IRELATIVE:
2290 case elfcpp::R_386_TLS_TPOFF:
2291 case elfcpp::R_386_TLS_DTPMOD32:
2292 case elfcpp::R_386_TLS_DTPOFF32:
2293 case elfcpp::R_386_TLS_TPOFF32:
2294 case elfcpp::R_386_TLS_DESC:
2295 gold_error(_("%s: unexpected reloc %u in object file"),
2296 object->name().c_str(), r_type);
2297 break;
2298
2299 // These are initial tls relocs, which are expected when
2300 // linking.
2301 case elfcpp::R_386_TLS_GD: // Global-dynamic
2302 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2303 case elfcpp::R_386_TLS_DESC_CALL:
2304 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2305 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2306 case elfcpp::R_386_TLS_IE: // Initial-exec
2307 case elfcpp::R_386_TLS_IE_32:
2308 case elfcpp::R_386_TLS_GOTIE:
2309 case elfcpp::R_386_TLS_LE: // Local-exec
2310 case elfcpp::R_386_TLS_LE_32:
2311 {
2312 const bool is_final = gsym->final_value_is_known();
2313 const tls::Tls_optimization optimized_type
2314 = Target_i386::optimize_tls_reloc(is_final, r_type);
2315 switch (r_type)
2316 {
2317 case elfcpp::R_386_TLS_GD: // Global-dynamic
2318 if (optimized_type == tls::TLSOPT_NONE)
2319 {
2320 // Create a pair of GOT entries for the module index and
2321 // dtv-relative offset.
2322 Output_data_got<32, false>* got
2323 = target->got_section(symtab, layout);
2324 got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR,
2325 target->rel_dyn_section(layout),
2326 elfcpp::R_386_TLS_DTPMOD32,
2327 elfcpp::R_386_TLS_DTPOFF32);
2328 }
2329 else if (optimized_type == tls::TLSOPT_TO_IE)
2330 {
2331 // Create a GOT entry for the tp-relative offset.
2332 Output_data_got<32, false>* got
2333 = target->got_section(symtab, layout);
2334 got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
2335 target->rel_dyn_section(layout),
2336 elfcpp::R_386_TLS_TPOFF);
2337 }
2338 else if (optimized_type != tls::TLSOPT_TO_LE)
2339 unsupported_reloc_global(object, r_type, gsym);
2340 break;
2341
2342 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url)
2343 target->define_tls_base_symbol(symtab, layout);
2344 if (optimized_type == tls::TLSOPT_NONE)
2345 {
2346 // Create a double GOT entry with an R_386_TLS_DESC
2347 // reloc. The R_386_TLS_DESC reloc is resolved
2348 // lazily, so the GOT entry needs to be in an area in
2349 // .got.plt, not .got. Call got_section to make sure
2350 // the section has been created.
2351 target->got_section(symtab, layout);
2352 Output_data_got<32, false>* got = target->got_tlsdesc_section();
2353 Reloc_section* rt = target->rel_tls_desc_section(layout);
2354 got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt,
2355 elfcpp::R_386_TLS_DESC, 0);
2356 }
2357 else if (optimized_type == tls::TLSOPT_TO_IE)
2358 {
2359 // Create a GOT entry for the tp-relative offset.
2360 Output_data_got<32, false>* got
2361 = target->got_section(symtab, layout);
2362 got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
2363 target->rel_dyn_section(layout),
2364 elfcpp::R_386_TLS_TPOFF);
2365 }
2366 else if (optimized_type != tls::TLSOPT_TO_LE)
2367 unsupported_reloc_global(object, r_type, gsym);
2368 break;
2369
2370 case elfcpp::R_386_TLS_DESC_CALL:
2371 break;
2372
2373 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2374 if (optimized_type == tls::TLSOPT_NONE)
2375 {
2376 // Create a GOT entry for the module index.
2377 target->got_mod_index_entry(symtab, layout, object);
2378 }
2379 else if (optimized_type != tls::TLSOPT_TO_LE)
2380 unsupported_reloc_global(object, r_type, gsym);
2381 break;
2382
2383 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2384 break;
2385
2386 case elfcpp::R_386_TLS_IE: // Initial-exec
2387 case elfcpp::R_386_TLS_IE_32:
2388 case elfcpp::R_386_TLS_GOTIE:
2389 layout->set_has_static_tls();
2390 if (optimized_type == tls::TLSOPT_NONE)
2391 {
2392 // For the R_386_TLS_IE relocation, we need to create a
2393 // dynamic relocation when building a shared library.
2394 if (r_type == elfcpp::R_386_TLS_IE
2395 && parameters->options().shared())
2396 {
2397 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2398 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2399 output_section, object,
2400 data_shndx,
2401 reloc.get_r_offset());
2402 }
2403 // Create a GOT entry for the tp-relative offset.
2404 Output_data_got<32, false>* got
2405 = target->got_section(symtab, layout);
2406 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
2407 ? elfcpp::R_386_TLS_TPOFF32
2408 : elfcpp::R_386_TLS_TPOFF);
2409 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
2410 ? GOT_TYPE_TLS_OFFSET
2411 : GOT_TYPE_TLS_NOFFSET);
2412 got->add_global_with_rel(gsym, got_type,
2413 target->rel_dyn_section(layout),
2414 dyn_r_type);
2415 }
2416 else if (optimized_type != tls::TLSOPT_TO_LE)
2417 unsupported_reloc_global(object, r_type, gsym);
2418 break;
2419
2420 case elfcpp::R_386_TLS_LE: // Local-exec
2421 case elfcpp::R_386_TLS_LE_32:
2422 layout->set_has_static_tls();
2423 if (parameters->options().shared())
2424 {
2425 // We need to create a dynamic relocation.
2426 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
2427 ? elfcpp::R_386_TLS_TPOFF32
2428 : elfcpp::R_386_TLS_TPOFF);
2429 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2430 rel_dyn->add_global(gsym, dyn_r_type, output_section, object,
2431 data_shndx, reloc.get_r_offset());
2432 }
2433 break;
2434
2435 default:
2436 gold_unreachable();
2437 }
2438 }
2439 break;
2440
2441 case elfcpp::R_386_32PLT:
2442 case elfcpp::R_386_TLS_GD_32:
2443 case elfcpp::R_386_TLS_GD_PUSH:
2444 case elfcpp::R_386_TLS_GD_CALL:
2445 case elfcpp::R_386_TLS_GD_POP:
2446 case elfcpp::R_386_TLS_LDM_32:
2447 case elfcpp::R_386_TLS_LDM_PUSH:
2448 case elfcpp::R_386_TLS_LDM_CALL:
2449 case elfcpp::R_386_TLS_LDM_POP:
2450 case elfcpp::R_386_USED_BY_INTEL_200:
2451 default:
2452 unsupported_reloc_global(object, r_type, gsym);
2453 break;
2454 }
2455 }
2456
2457 // Process relocations for gc.
2458
2459 void
2460 Target_i386::gc_process_relocs(Symbol_table* symtab,
2461 Layout* layout,
2462 Sized_relobj_file<32, false>* object,
2463 unsigned int data_shndx,
2464 unsigned int,
2465 const unsigned char* prelocs,
2466 size_t reloc_count,
2467 Output_section* output_section,
2468 bool needs_special_offset_handling,
2469 size_t local_symbol_count,
2470 const unsigned char* plocal_symbols)
2471 {
2472 gold::gc_process_relocs<32, false, Target_i386, elfcpp::SHT_REL,
2473 Target_i386::Scan,
2474 Target_i386::Relocatable_size_for_reloc>(
2475 symtab,
2476 layout,
2477 this,
2478 object,
2479 data_shndx,
2480 prelocs,
2481 reloc_count,
2482 output_section,
2483 needs_special_offset_handling,
2484 local_symbol_count,
2485 plocal_symbols);
2486 }
2487
2488 // Scan relocations for a section.
2489
2490 void
2491 Target_i386::scan_relocs(Symbol_table* symtab,
2492 Layout* layout,
2493 Sized_relobj_file<32, false>* object,
2494 unsigned int data_shndx,
2495 unsigned int sh_type,
2496 const unsigned char* prelocs,
2497 size_t reloc_count,
2498 Output_section* output_section,
2499 bool needs_special_offset_handling,
2500 size_t local_symbol_count,
2501 const unsigned char* plocal_symbols)
2502 {
2503 if (sh_type == elfcpp::SHT_RELA)
2504 {
2505 gold_error(_("%s: unsupported RELA reloc section"),
2506 object->name().c_str());
2507 return;
2508 }
2509
2510 gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
2511 Target_i386::Scan>(
2512 symtab,
2513 layout,
2514 this,
2515 object,
2516 data_shndx,
2517 prelocs,
2518 reloc_count,
2519 output_section,
2520 needs_special_offset_handling,
2521 local_symbol_count,
2522 plocal_symbols);
2523 }
2524
2525 // Finalize the sections.
2526
2527 void
2528 Target_i386::do_finalize_sections(
2529 Layout* layout,
2530 const Input_objects*,
2531 Symbol_table* symtab)
2532 {
2533 const Reloc_section* rel_plt = (this->plt_ == NULL
2534 ? NULL
2535 : this->plt_->rel_plt());
2536 layout->add_target_dynamic_tags(true, this->got_plt_, rel_plt,
2537 this->rel_dyn_, true, false);
2538
2539 // Emit any relocs we saved in an attempt to avoid generating COPY
2540 // relocs.
2541 if (this->copy_relocs_.any_saved_relocs())
2542 this->copy_relocs_.emit(this->rel_dyn_section(layout));
2543
2544 // Set the size of the _GLOBAL_OFFSET_TABLE_ symbol to the size of
2545 // the .got.plt section.
2546 Symbol* sym = this->global_offset_table_;
2547 if (sym != NULL)
2548 {
2549 uint32_t data_size = this->got_plt_->current_data_size();
2550 symtab->get_sized_symbol<32>(sym)->set_symsize(data_size);
2551 }
2552
2553 if (parameters->doing_static_link()
2554 && (this->plt_ == NULL || !this->plt_->has_irelative_section()))
2555 {
2556 // If linking statically, make sure that the __rel_iplt symbols
2557 // were defined if necessary, even if we didn't create a PLT.
2558 static const Define_symbol_in_segment syms[] =
2559 {
2560 {
2561 "__rel_iplt_start", // name
2562 elfcpp::PT_LOAD, // segment_type
2563 elfcpp::PF_W, // segment_flags_set
2564 elfcpp::PF(0), // segment_flags_clear
2565 0, // value
2566 0, // size
2567 elfcpp::STT_NOTYPE, // type
2568 elfcpp::STB_GLOBAL, // binding
2569 elfcpp::STV_HIDDEN, // visibility
2570 0, // nonvis
2571 Symbol::SEGMENT_START, // offset_from_base
2572 true // only_if_ref
2573 },
2574 {
2575 "__rel_iplt_end", // name
2576 elfcpp::PT_LOAD, // segment_type
2577 elfcpp::PF_W, // segment_flags_set
2578 elfcpp::PF(0), // segment_flags_clear
2579 0, // value
2580 0, // size
2581 elfcpp::STT_NOTYPE, // type
2582 elfcpp::STB_GLOBAL, // binding
2583 elfcpp::STV_HIDDEN, // visibility
2584 0, // nonvis
2585 Symbol::SEGMENT_START, // offset_from_base
2586 true // only_if_ref
2587 }
2588 };
2589
2590 symtab->define_symbols(layout, 2, syms,
2591 layout->script_options()->saw_sections_clause());
2592 }
2593 }
2594
2595 // Return whether a direct absolute static relocation needs to be applied.
2596 // In cases where Scan::local() or Scan::global() has created
2597 // a dynamic relocation other than R_386_RELATIVE, the addend
2598 // of the relocation is carried in the data, and we must not
2599 // apply the static relocation.
2600
2601 inline bool
2602 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
2603 unsigned int r_type,
2604 bool is_32bit,
2605 Output_section* output_section)
2606 {
2607 // If the output section is not allocated, then we didn't call
2608 // scan_relocs, we didn't create a dynamic reloc, and we must apply
2609 // the reloc here.
2610 if ((output_section->flags() & elfcpp::SHF_ALLOC) == 0)
2611 return true;
2612
2613 int ref_flags = Scan::get_reference_flags(r_type);
2614
2615 // For local symbols, we will have created a non-RELATIVE dynamic
2616 // relocation only if (a) the output is position independent,
2617 // (b) the relocation is absolute (not pc- or segment-relative), and
2618 // (c) the relocation is not 32 bits wide.
2619 if (gsym == NULL)
2620 return !(parameters->options().output_is_position_independent()
2621 && (ref_flags & Symbol::ABSOLUTE_REF)
2622 && !is_32bit);
2623
2624 // For global symbols, we use the same helper routines used in the
2625 // scan pass. If we did not create a dynamic relocation, or if we
2626 // created a RELATIVE dynamic relocation, we should apply the static
2627 // relocation.
2628 bool has_dyn = gsym->needs_dynamic_reloc(ref_flags);
2629 bool is_rel = (ref_flags & Symbol::ABSOLUTE_REF)
2630 && gsym->can_use_relative_reloc(ref_flags
2631 & Symbol::FUNCTION_CALL);
2632 return !has_dyn || is_rel;
2633 }
2634
2635 // Perform a relocation.
2636
2637 inline bool
2638 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
2639 Target_i386* target,
2640 Output_section* output_section,
2641 size_t relnum,
2642 const elfcpp::Rel<32, false>& rel,
2643 unsigned int r_type,
2644 const Sized_symbol<32>* gsym,
2645 const Symbol_value<32>* psymval,
2646 unsigned char* view,
2647 elfcpp::Elf_types<32>::Elf_Addr address,
2648 section_size_type view_size)
2649 {
2650 if (this->skip_call_tls_get_addr_)
2651 {
2652 if ((r_type != elfcpp::R_386_PLT32
2653 && r_type != elfcpp::R_386_PC32)
2654 || gsym == NULL
2655 || strcmp(gsym->name(), "___tls_get_addr") != 0)
2656 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2657 _("missing expected TLS relocation"));
2658 else
2659 {
2660 this->skip_call_tls_get_addr_ = false;
2661 return false;
2662 }
2663 }
2664
2665 if (view == NULL)
2666 return true;
2667
2668 const Sized_relobj_file<32, false>* object = relinfo->object;
2669
2670 // Pick the value to use for symbols defined in shared objects.
2671 Symbol_value<32> symval;
2672 if (gsym != NULL
2673 && gsym->type() == elfcpp::STT_GNU_IFUNC
2674 && r_type == elfcpp::R_386_32
2675 && gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type))
2676 && gsym->can_use_relative_reloc(false)
2677 && !gsym->is_from_dynobj()
2678 && !gsym->is_undefined()
2679 && !gsym->is_preemptible())
2680 {
2681 // In this case we are generating a R_386_IRELATIVE reloc. We
2682 // want to use the real value of the symbol, not the PLT offset.
2683 }
2684 else if (gsym != NULL
2685 && gsym->use_plt_offset(Scan::get_reference_flags(r_type)))
2686 {
2687 symval.set_output_value(target->plt_address_for_global(gsym));
2688 psymval = &symval;
2689 }
2690 else if (gsym == NULL && psymval->is_ifunc_symbol())
2691 {
2692 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2693 if (object->local_has_plt_offset(r_sym))
2694 {
2695 symval.set_output_value(target->plt_address_for_local(object, r_sym));
2696 psymval = &symval;
2697 }
2698 }
2699
2700 // Get the GOT offset if needed.
2701 // The GOT pointer points to the end of the GOT section.
2702 // We need to subtract the size of the GOT section to get
2703 // the actual offset to use in the relocation.
2704 bool have_got_offset = false;
2705 unsigned int got_offset = 0;
2706 switch (r_type)
2707 {
2708 case elfcpp::R_386_GOT32:
2709 if (gsym != NULL)
2710 {
2711 gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD));
2712 got_offset = (gsym->got_offset(GOT_TYPE_STANDARD)
2713 - target->got_size());
2714 }
2715 else
2716 {
2717 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2718 gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD));
2719 got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD)
2720 - target->got_size());
2721 }
2722 have_got_offset = true;
2723 break;
2724
2725 default:
2726 break;
2727 }
2728
2729 switch (r_type)
2730 {
2731 case elfcpp::R_386_NONE:
2732 case elfcpp::R_386_GNU_VTINHERIT:
2733 case elfcpp::R_386_GNU_VTENTRY:
2734 break;
2735
2736 case elfcpp::R_386_32:
2737 if (should_apply_static_reloc(gsym, r_type, true, output_section))
2738 Relocate_functions<32, false>::rel32(view, object, psymval);
2739 break;
2740
2741 case elfcpp::R_386_PC32:
2742 if (should_apply_static_reloc(gsym, r_type, true, output_section))
2743 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
2744 break;
2745
2746 case elfcpp::R_386_16:
2747 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2748 Relocate_functions<32, false>::rel16(view, object, psymval);
2749 break;
2750
2751 case elfcpp::R_386_PC16:
2752 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2753 Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
2754 break;
2755
2756 case elfcpp::R_386_8:
2757 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2758 Relocate_functions<32, false>::rel8(view, object, psymval);
2759 break;
2760
2761 case elfcpp::R_386_PC8:
2762 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2763 Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
2764 break;
2765
2766 case elfcpp::R_386_PLT32:
2767 gold_assert(gsym == NULL
2768 || gsym->has_plt_offset()
2769 || gsym->final_value_is_known()
2770 || (gsym->is_defined()
2771 && !gsym->is_from_dynobj()
2772 && !gsym->is_preemptible()));
2773 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
2774 break;
2775
2776 case elfcpp::R_386_GOT32:
2777 gold_assert(have_got_offset);
2778 Relocate_functions<32, false>::rel32(view, got_offset);
2779 break;
2780
2781 case elfcpp::R_386_GOTOFF:
2782 {
2783 elfcpp::Elf_types<32>::Elf_Addr value;
2784 value = (psymval->value(object, 0)
2785 - target->got_plt_section()->address());
2786 Relocate_functions<32, false>::rel32(view, value);
2787 }
2788 break;
2789
2790 case elfcpp::R_386_GOTPC:
2791 {
2792 elfcpp::Elf_types<32>::Elf_Addr value;
2793 value = target->got_plt_section()->address();
2794 Relocate_functions<32, false>::pcrel32(view, value, address);
2795 }
2796 break;
2797
2798 case elfcpp::R_386_COPY:
2799 case elfcpp::R_386_GLOB_DAT:
2800 case elfcpp::R_386_JUMP_SLOT:
2801 case elfcpp::R_386_RELATIVE:
2802 case elfcpp::R_386_IRELATIVE:
2803 // These are outstanding tls relocs, which are unexpected when
2804 // linking.
2805 case elfcpp::R_386_TLS_TPOFF:
2806 case elfcpp::R_386_TLS_DTPMOD32:
2807 case elfcpp::R_386_TLS_DTPOFF32:
2808 case elfcpp::R_386_TLS_TPOFF32:
2809 case elfcpp::R_386_TLS_DESC:
2810 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2811 _("unexpected reloc %u in object file"),
2812 r_type);
2813 break;
2814
2815 // These are initial tls relocs, which are expected when
2816 // linking.
2817 case elfcpp::R_386_TLS_GD: // Global-dynamic
2818 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2819 case elfcpp::R_386_TLS_DESC_CALL:
2820 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2821 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2822 case elfcpp::R_386_TLS_IE: // Initial-exec
2823 case elfcpp::R_386_TLS_IE_32:
2824 case elfcpp::R_386_TLS_GOTIE:
2825 case elfcpp::R_386_TLS_LE: // Local-exec
2826 case elfcpp::R_386_TLS_LE_32:
2827 this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval,
2828 view, address, view_size);
2829 break;
2830
2831 case elfcpp::R_386_32PLT:
2832 case elfcpp::R_386_TLS_GD_32:
2833 case elfcpp::R_386_TLS_GD_PUSH:
2834 case elfcpp::R_386_TLS_GD_CALL:
2835 case elfcpp::R_386_TLS_GD_POP:
2836 case elfcpp::R_386_TLS_LDM_32:
2837 case elfcpp::R_386_TLS_LDM_PUSH:
2838 case elfcpp::R_386_TLS_LDM_CALL:
2839 case elfcpp::R_386_TLS_LDM_POP:
2840 case elfcpp::R_386_USED_BY_INTEL_200:
2841 default:
2842 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2843 _("unsupported reloc %u"),
2844 r_type);
2845 break;
2846 }
2847
2848 return true;
2849 }
2850
2851 // Perform a TLS relocation.
2852
2853 inline void
2854 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
2855 Target_i386* target,
2856 size_t relnum,
2857 const elfcpp::Rel<32, false>& rel,
2858 unsigned int r_type,
2859 const Sized_symbol<32>* gsym,
2860 const Symbol_value<32>* psymval,
2861 unsigned char* view,
2862 elfcpp::Elf_types<32>::Elf_Addr,
2863 section_size_type view_size)
2864 {
2865 Output_segment* tls_segment = relinfo->layout->tls_segment();
2866
2867 const Sized_relobj_file<32, false>* object = relinfo->object;
2868
2869 elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0);
2870
2871 const bool is_final = (gsym == NULL
2872 ? !parameters->options().shared()
2873 : gsym->final_value_is_known());
2874 const tls::Tls_optimization optimized_type
2875 = Target_i386::optimize_tls_reloc(is_final, r_type);
2876 switch (r_type)
2877 {
2878 case elfcpp::R_386_TLS_GD: // Global-dynamic
2879 if (optimized_type == tls::TLSOPT_TO_LE)
2880 {
2881 if (tls_segment == NULL)
2882 {
2883 gold_assert(parameters->errors()->error_count() > 0
2884 || issue_undefined_symbol_error(gsym));
2885 return;
2886 }
2887 this->tls_gd_to_le(relinfo, relnum, tls_segment,
2888 rel, r_type, value, view,
2889 view_size);
2890 break;
2891 }
2892 else
2893 {
2894 unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
2895 ? GOT_TYPE_TLS_NOFFSET
2896 : GOT_TYPE_TLS_PAIR);
2897 unsigned int got_offset;
2898 if (gsym != NULL)
2899 {
2900 gold_assert(gsym->has_got_offset(got_type));
2901 got_offset = gsym->got_offset(got_type) - target->got_size();
2902 }
2903 else
2904 {
2905 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2906 gold_assert(object->local_has_got_offset(r_sym, got_type));
2907 got_offset = (object->local_got_offset(r_sym, got_type)
2908 - target->got_size());
2909 }
2910 if (optimized_type == tls::TLSOPT_TO_IE)
2911 {
2912 this->tls_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
2913 got_offset, view, view_size);
2914 break;
2915 }
2916 else if (optimized_type == tls::TLSOPT_NONE)
2917 {
2918 // Relocate the field with the offset of the pair of GOT
2919 // entries.
2920 Relocate_functions<32, false>::rel32(view, got_offset);
2921 break;
2922 }
2923 }
2924 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2925 _("unsupported reloc %u"),
2926 r_type);
2927 break;
2928
2929 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2930 case elfcpp::R_386_TLS_DESC_CALL:
2931 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
2932 if (optimized_type == tls::TLSOPT_TO_LE)
2933 {
2934 if (tls_segment == NULL)
2935 {
2936 gold_assert(parameters->errors()->error_count() > 0
2937 || issue_undefined_symbol_error(gsym));
2938 return;
2939 }
2940 this->tls_desc_gd_to_le(relinfo, relnum, tls_segment,
2941 rel, r_type, value, view,
2942 view_size);
2943 break;
2944 }
2945 else
2946 {
2947 unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
2948 ? GOT_TYPE_TLS_NOFFSET
2949 : GOT_TYPE_TLS_DESC);
2950 unsigned int got_offset = 0;
2951 if (r_type == elfcpp::R_386_TLS_GOTDESC
2952 && optimized_type == tls::TLSOPT_NONE)
2953 {
2954 // We created GOT entries in the .got.tlsdesc portion of
2955 // the .got.plt section, but the offset stored in the
2956 // symbol is the offset within .got.tlsdesc.
2957 got_offset = (target->got_size()
2958 + target->got_plt_section()->data_size());
2959 }
2960 if (gsym != NULL)
2961 {
2962 gold_assert(gsym->has_got_offset(got_type));
2963 got_offset += gsym->got_offset(got_type) - target->got_size();
2964 }
2965 else
2966 {
2967 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2968 gold_assert(object->local_has_got_offset(r_sym, got_type));
2969 got_offset += (object->local_got_offset(r_sym, got_type)
2970 - target->got_size());
2971 }
2972 if (optimized_type == tls::TLSOPT_TO_IE)
2973 {
2974 if (tls_segment == NULL)
2975 {
2976 gold_assert(parameters->errors()->error_count() > 0
2977 || issue_undefined_symbol_error(gsym));
2978 return;
2979 }
2980 this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
2981 got_offset, view, view_size);
2982 break;
2983 }
2984 else if (optimized_type == tls::TLSOPT_NONE)
2985 {
2986 if (r_type == elfcpp::R_386_TLS_GOTDESC)
2987 {
2988 // Relocate the field with the offset of the pair of GOT
2989 // entries.
2990 Relocate_functions<32, false>::rel32(view, got_offset);
2991 }
2992 break;
2993 }
2994 }
2995 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2996 _("unsupported reloc %u"),
2997 r_type);
2998 break;
2999
3000 case elfcpp::R_386_TLS_LDM: // Local-dynamic
3001 if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
3002 {
3003 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3004 _("both SUN and GNU model "
3005 "TLS relocations"));
3006 break;
3007 }
3008 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
3009 if (optimized_type == tls::TLSOPT_TO_LE)
3010 {
3011 if (tls_segment == NULL)
3012 {
3013 gold_assert(parameters->errors()->error_count() > 0
3014 || issue_undefined_symbol_error(gsym));
3015 return;
3016 }
3017 this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
3018 value, view, view_size);
3019 break;
3020 }
3021 else if (optimized_type == tls::TLSOPT_NONE)
3022 {
3023 // Relocate the field with the offset of the GOT entry for
3024 // the module index.
3025 unsigned int got_offset;
3026 got_offset = (target->got_mod_index_entry(NULL, NULL, NULL)
3027 - target->got_size());
3028 Relocate_functions<32, false>::rel32(view, got_offset);
3029 break;
3030 }
3031 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3032 _("unsupported reloc %u"),
3033 r_type);
3034 break;
3035
3036 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
3037 if (optimized_type == tls::TLSOPT_TO_LE)
3038 {
3039 // This reloc can appear in debugging sections, in which
3040 // case we must not convert to local-exec. We decide what
3041 // to do based on whether the section is marked as
3042 // containing executable code. That is what the GNU linker
3043 // does as well.
3044 elfcpp::Shdr<32, false> shdr(relinfo->data_shdr);
3045 if ((shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0)
3046 {
3047 if (tls_segment == NULL)
3048 {
3049 gold_assert(parameters->errors()->error_count() > 0
3050 || issue_undefined_symbol_error(gsym));
3051 return;
3052 }
3053 value -= tls_segment->memsz();
3054 }
3055 }
3056 Relocate_functions<32, false>::rel32(view, value);
3057 break;
3058
3059 case elfcpp::R_386_TLS_IE: // Initial-exec
3060 case elfcpp::R_386_TLS_GOTIE:
3061 case elfcpp::R_386_TLS_IE_32:
3062 if (optimized_type == tls::TLSOPT_TO_LE)
3063 {
3064 if (tls_segment == NULL)
3065 {
3066 gold_assert(parameters->errors()->error_count() > 0
3067 || issue_undefined_symbol_error(gsym));
3068 return;
3069 }
3070 Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
3071 rel, r_type, value, view,
3072 view_size);
3073 break;
3074 }
3075 else if (optimized_type == tls::TLSOPT_NONE)
3076 {
3077 // Relocate the field with the offset of the GOT entry for
3078 // the tp-relative offset of the symbol.
3079 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
3080 ? GOT_TYPE_TLS_OFFSET
3081 : GOT_TYPE_TLS_NOFFSET);
3082 unsigned int got_offset;
3083 if (gsym != NULL)
3084 {
3085 gold_assert(gsym->has_got_offset(got_type));
3086 got_offset = gsym->got_offset(got_type);
3087 }
3088 else
3089 {
3090 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
3091 gold_assert(object->local_has_got_offset(r_sym, got_type));
3092 got_offset = object->local_got_offset(r_sym, got_type);
3093 }
3094 // For the R_386_TLS_IE relocation, we need to apply the
3095 // absolute address of the GOT entry.
3096 if (r_type == elfcpp::R_386_TLS_IE)
3097 got_offset += target->got_plt_section()->address();
3098 // All GOT offsets are relative to the end of the GOT.
3099 got_offset -= target->got_size();
3100 Relocate_functions<32, false>::rel32(view, got_offset);
3101 break;
3102 }
3103 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3104 _("unsupported reloc %u"),
3105 r_type);
3106 break;
3107
3108 case elfcpp::R_386_TLS_LE: // Local-exec
3109 // If we're creating a shared library, a dynamic relocation will
3110 // have been created for this location, so do not apply it now.
3111 if (!parameters->options().shared())
3112 {
3113 if (tls_segment == NULL)
3114 {
3115 gold_assert(parameters->errors()->error_count() > 0
3116 || issue_undefined_symbol_error(gsym));
3117 return;
3118 }
3119 value -= tls_segment->memsz();
3120 Relocate_functions<32, false>::rel32(view, value);
3121 }
3122 break;
3123
3124 case elfcpp::R_386_TLS_LE_32:
3125 // If we're creating a shared library, a dynamic relocation will
3126 // have been created for this location, so do not apply it now.
3127 if (!parameters->options().shared())
3128 {
3129 if (tls_segment == NULL)
3130 {
3131 gold_assert(parameters->errors()->error_count() > 0
3132 || issue_undefined_symbol_error(gsym));
3133 return;
3134 }
3135 value = tls_segment->memsz() - value;
3136 Relocate_functions<32, false>::rel32(view, value);
3137 }
3138 break;
3139 }
3140 }
3141
3142 // Do a relocation in which we convert a TLS General-Dynamic to a
3143 // Local-Exec.
3144
3145 inline void
3146 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
3147 size_t relnum,
3148 Output_segment* tls_segment,
3149 const elfcpp::Rel<32, false>& rel,
3150 unsigned int,
3151 elfcpp::Elf_types<32>::Elf_Addr value,
3152 unsigned char* view,
3153 section_size_type view_size)
3154 {
3155 // leal foo(,%reg,1),%eax; call ___tls_get_addr
3156 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
3157 // leal foo(%reg),%eax; call ___tls_get_addr
3158 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
3159
3160 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3161 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3162
3163 unsigned char op1 = view[-1];
3164 unsigned char op2 = view[-2];
3165
3166 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3167 op2 == 0x8d || op2 == 0x04);
3168 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3169
3170 int roff = 5;
3171
3172 if (op2 == 0x04)
3173 {
3174 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
3175 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
3176 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3177 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
3178 memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3179 }
3180 else
3181 {
3182 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3183 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
3184 if (rel.get_r_offset() + 9 < view_size
3185 && view[9] == 0x90)
3186 {
3187 // There is a trailing nop. Use the size byte subl.
3188 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3189 roff = 6;
3190 }
3191 else
3192 {
3193 // Use the five byte subl.
3194 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
3195 }
3196 }
3197
3198 value = tls_segment->memsz() - value;
3199 Relocate_functions<32, false>::rel32(view + roff, value);
3200
3201 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3202 // We can skip it.
3203 this->skip_call_tls_get_addr_ = true;
3204 }
3205
3206 // Do a relocation in which we convert a TLS General-Dynamic to an
3207 // Initial-Exec.
3208
3209 inline void
3210 Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
3211 size_t relnum,
3212 Output_segment*,
3213 const elfcpp::Rel<32, false>& rel,
3214 unsigned int,
3215 elfcpp::Elf_types<32>::Elf_Addr value,
3216 unsigned char* view,
3217 section_size_type view_size)
3218 {
3219 // leal foo(,%ebx,1),%eax; call ___tls_get_addr
3220 // ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
3221
3222 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3223 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3224
3225 unsigned char op1 = view[-1];
3226 unsigned char op2 = view[-2];
3227
3228 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3229 op2 == 0x8d || op2 == 0x04);
3230 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3231
3232 int roff = 5;
3233
3234 // FIXME: For now, support only the first (SIB) form.
3235 tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x04);
3236
3237 if (op2 == 0x04)
3238 {
3239 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
3240 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
3241 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3242 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
3243 memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
3244 }
3245 else
3246 {
3247 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3248 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
3249 if (rel.get_r_offset() + 9 < view_size
3250 && view[9] == 0x90)
3251 {
3252 // FIXME: This is not the right instruction sequence.
3253 // There is a trailing nop. Use the size byte subl.
3254 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3255 roff = 6;
3256 }
3257 else
3258 {
3259 // FIXME: This is not the right instruction sequence.
3260 // Use the five byte subl.
3261 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
3262 }
3263 }
3264
3265 Relocate_functions<32, false>::rel32(view + roff, value);
3266
3267 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3268 // We can skip it.
3269 this->skip_call_tls_get_addr_ = true;
3270 }
3271
3272 // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
3273 // General-Dynamic to a Local-Exec.
3274
3275 inline void
3276 Target_i386::Relocate::tls_desc_gd_to_le(
3277 const Relocate_info<32, false>* relinfo,
3278 size_t relnum,
3279 Output_segment* tls_segment,
3280 const elfcpp::Rel<32, false>& rel,
3281 unsigned int r_type,
3282 elfcpp::Elf_types<32>::Elf_Addr value,
3283 unsigned char* view,
3284 section_size_type view_size)
3285 {
3286 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3287 {
3288 // leal foo@TLSDESC(%ebx), %eax
3289 // ==> leal foo@NTPOFF, %eax
3290 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3291 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3292 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3293 view[-2] == 0x8d && view[-1] == 0x83);
3294 view[-1] = 0x05;
3295 value -= tls_segment->memsz();
3296 Relocate_functions<32, false>::rel32(view, value);
3297 }
3298 else
3299 {
3300 // call *foo@TLSCALL(%eax)
3301 // ==> nop; nop
3302 gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
3303 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
3304 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3305 view[0] == 0xff && view[1] == 0x10);
3306 view[0] = 0x66;
3307 view[1] = 0x90;
3308 }
3309 }
3310
3311 // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
3312 // General-Dynamic to an Initial-Exec.
3313
3314 inline void
3315 Target_i386::Relocate::tls_desc_gd_to_ie(
3316 const Relocate_info<32, false>* relinfo,
3317 size_t relnum,
3318 Output_segment*,
3319 const elfcpp::Rel<32, false>& rel,
3320 unsigned int r_type,
3321 elfcpp::Elf_types<32>::Elf_Addr value,
3322 unsigned char* view,
3323 section_size_type view_size)
3324 {
3325 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3326 {
3327 // leal foo@TLSDESC(%ebx), %eax
3328 // ==> movl foo@GOTNTPOFF(%ebx), %eax
3329 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3330 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3331 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3332 view[-2] == 0x8d && view[-1] == 0x83);
3333 view[-2] = 0x8b;
3334 Relocate_functions<32, false>::rel32(view, value);
3335 }
3336 else
3337 {
3338 // call *foo@TLSCALL(%eax)
3339 // ==> nop; nop
3340 gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
3341 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
3342 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3343 view[0] == 0xff && view[1] == 0x10);
3344 view[0] = 0x66;
3345 view[1] = 0x90;
3346 }
3347 }
3348
3349 // Do a relocation in which we convert a TLS Local-Dynamic to a
3350 // Local-Exec.
3351
3352 inline void
3353 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
3354 size_t relnum,
3355 Output_segment*,
3356 const elfcpp::Rel<32, false>& rel,
3357 unsigned int,
3358 elfcpp::Elf_types<32>::Elf_Addr,
3359 unsigned char* view,
3360 section_size_type view_size)
3361 {
3362 // leal foo(%reg), %eax; call ___tls_get_addr
3363 // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
3364
3365 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3366 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3367
3368 // FIXME: Does this test really always pass?
3369 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3370 view[-2] == 0x8d && view[-1] == 0x83);
3371
3372 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3373
3374 memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
3375
3376 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3377 // We can skip it.
3378 this->skip_call_tls_get_addr_ = true;
3379 }
3380
3381 // Do a relocation in which we convert a TLS Initial-Exec to a
3382 // Local-Exec.
3383
3384 inline void
3385 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
3386 size_t relnum,
3387 Output_segment* tls_segment,
3388 const elfcpp::Rel<32, false>& rel,
3389 unsigned int r_type,
3390 elfcpp::Elf_types<32>::Elf_Addr value,
3391 unsigned char* view,
3392 section_size_type view_size)
3393 {
3394 // We have to actually change the instructions, which means that we
3395 // need to examine the opcodes to figure out which instruction we
3396 // are looking at.
3397 if (r_type == elfcpp::R_386_TLS_IE)
3398 {
3399 // movl %gs:XX,%eax ==> movl $YY,%eax
3400 // movl %gs:XX,%reg ==> movl $YY,%reg
3401 // addl %gs:XX,%reg ==> addl $YY,%reg
3402 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
3403 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3404
3405 unsigned char op1 = view[-1];
3406 if (op1 == 0xa1)
3407 {
3408 // movl XX,%eax ==> movl $YY,%eax
3409 view[-1] = 0xb8;
3410 }
3411 else
3412 {
3413 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3414
3415 unsigned char op2 = view[-2];
3416 if (op2 == 0x8b)
3417 {
3418 // movl XX,%reg ==> movl $YY,%reg
3419 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3420 (op1 & 0xc7) == 0x05);
3421 view[-2] = 0xc7;
3422 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3423 }
3424 else if (op2 == 0x03)
3425 {
3426 // addl XX,%reg ==> addl $YY,%reg
3427 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3428 (op1 & 0xc7) == 0x05);
3429 view[-2] = 0x81;
3430 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3431 }
3432 else
3433 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
3434 }
3435 }
3436 else
3437 {
3438 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
3439 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
3440 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
3441 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3442 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3443
3444 unsigned char op1 = view[-1];
3445 unsigned char op2 = view[-2];
3446 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3447 (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
3448 if (op2 == 0x8b)
3449 {
3450 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
3451 view[-2] = 0xc7;
3452 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3453 }
3454 else if (op2 == 0x2b)
3455 {
3456 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
3457 view[-2] = 0x81;
3458 view[-1] = 0xe8 | ((op1 >> 3) & 7);
3459 }
3460 else if (op2 == 0x03)
3461 {
3462 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
3463 view[-2] = 0x81;
3464 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3465 }
3466 else
3467 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
3468 }
3469
3470 value = tls_segment->memsz() - value;
3471 if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
3472 value = - value;
3473
3474 Relocate_functions<32, false>::rel32(view, value);
3475 }
3476
3477 // Relocate section data.
3478
3479 void
3480 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
3481 unsigned int sh_type,
3482 const unsigned char* prelocs,
3483 size_t reloc_count,
3484 Output_section* output_section,
3485 bool needs_special_offset_handling,
3486 unsigned char* view,
3487 elfcpp::Elf_types<32>::Elf_Addr address,
3488 section_size_type view_size,
3489 const Reloc_symbol_changes* reloc_symbol_changes)
3490 {
3491 gold_assert(sh_type == elfcpp::SHT_REL);
3492
3493 gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
3494 Target_i386::Relocate, gold::Default_comdat_behavior>(
3495 relinfo,
3496 this,
3497 prelocs,
3498 reloc_count,
3499 output_section,
3500 needs_special_offset_handling,
3501 view,
3502 address,
3503 view_size,
3504 reloc_symbol_changes);
3505 }
3506
3507 // Return the size of a relocation while scanning during a relocatable
3508 // link.
3509
3510 unsigned int
3511 Target_i386::Relocatable_size_for_reloc::get_size_for_reloc(
3512 unsigned int r_type,
3513 Relobj* object)
3514 {
3515 switch (r_type)
3516 {
3517 case elfcpp::R_386_NONE:
3518 case elfcpp::R_386_GNU_VTINHERIT:
3519 case elfcpp::R_386_GNU_VTENTRY:
3520 case elfcpp::R_386_TLS_GD: // Global-dynamic
3521 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
3522 case elfcpp::R_386_TLS_DESC_CALL:
3523 case elfcpp::R_386_TLS_LDM: // Local-dynamic
3524 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
3525 case elfcpp::R_386_TLS_IE: // Initial-exec
3526 case elfcpp::R_386_TLS_IE_32:
3527 case elfcpp::R_386_TLS_GOTIE:
3528 case elfcpp::R_386_TLS_LE: // Local-exec
3529 case elfcpp::R_386_TLS_LE_32:
3530 return 0;
3531
3532 case elfcpp::R_386_32:
3533 case elfcpp::R_386_PC32:
3534 case elfcpp::R_386_GOT32:
3535 case elfcpp::R_386_PLT32:
3536 case elfcpp::R_386_GOTOFF:
3537 case elfcpp::R_386_GOTPC:
3538 return 4;
3539
3540 case elfcpp::R_386_16:
3541 case elfcpp::R_386_PC16:
3542 return 2;
3543
3544 case elfcpp::R_386_8:
3545 case elfcpp::R_386_PC8:
3546 return 1;
3547
3548 // These are relocations which should only be seen by the
3549 // dynamic linker, and should never be seen here.
3550 case elfcpp::R_386_COPY:
3551 case elfcpp::R_386_GLOB_DAT:
3552 case elfcpp::R_386_JUMP_SLOT:
3553 case elfcpp::R_386_RELATIVE:
3554 case elfcpp::R_386_IRELATIVE:
3555 case elfcpp::R_386_TLS_TPOFF:
3556 case elfcpp::R_386_TLS_DTPMOD32:
3557 case elfcpp::R_386_TLS_DTPOFF32:
3558 case elfcpp::R_386_TLS_TPOFF32:
3559 case elfcpp::R_386_TLS_DESC:
3560 object->error(_("unexpected reloc %u in object file"), r_type);
3561 return 0;
3562
3563 case elfcpp::R_386_32PLT:
3564 case elfcpp::R_386_TLS_GD_32:
3565 case elfcpp::R_386_TLS_GD_PUSH:
3566 case elfcpp::R_386_TLS_GD_CALL:
3567 case elfcpp::R_386_TLS_GD_POP:
3568 case elfcpp::R_386_TLS_LDM_32:
3569 case elfcpp::R_386_TLS_LDM_PUSH:
3570 case elfcpp::R_386_TLS_LDM_CALL:
3571 case elfcpp::R_386_TLS_LDM_POP:
3572 case elfcpp::R_386_USED_BY_INTEL_200:
3573 default:
3574 object->error(_("unsupported reloc %u in object file"), r_type);
3575 return 0;
3576 }
3577 }
3578
3579 // Scan the relocs during a relocatable link.
3580
3581 void
3582 Target_i386::scan_relocatable_relocs(Symbol_table* symtab,
3583 Layout* layout,
3584 Sized_relobj_file<32, false>* object,
3585 unsigned int data_shndx,
3586 unsigned int sh_type,
3587 const unsigned char* prelocs,
3588 size_t reloc_count,
3589 Output_section* output_section,
3590 bool needs_special_offset_handling,
3591 size_t local_symbol_count,
3592 const unsigned char* plocal_symbols,
3593 Relocatable_relocs* rr)
3594 {
3595 gold_assert(sh_type == elfcpp::SHT_REL);
3596
3597 typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_REL,
3598 Relocatable_size_for_reloc> Scan_relocatable_relocs;
3599
3600 gold::scan_relocatable_relocs<32, false, elfcpp::SHT_REL,
3601 Scan_relocatable_relocs>(
3602 symtab,
3603 layout,
3604 object,
3605 data_shndx,
3606 prelocs,
3607 reloc_count,
3608 output_section,
3609 needs_special_offset_handling,
3610 local_symbol_count,
3611 plocal_symbols,
3612 rr);
3613 }
3614
3615 // Emit relocations for a section.
3616
3617 void
3618 Target_i386::relocate_relocs(
3619 const Relocate_info<32, false>* relinfo,
3620 unsigned int sh_type,
3621 const unsigned char* prelocs,
3622 size_t reloc_count,
3623 Output_section* output_section,
3624 elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,
3625 const Relocatable_relocs* rr,
3626 unsigned char* view,
3627 elfcpp::Elf_types<32>::Elf_Addr view_address,
3628 section_size_type view_size,
3629 unsigned char* reloc_view,
3630 section_size_type reloc_view_size)
3631 {
3632 gold_assert(sh_type == elfcpp::SHT_REL);
3633
3634 gold::relocate_relocs<32, false, elfcpp::SHT_REL>(
3635 relinfo,
3636 prelocs,
3637 reloc_count,
3638 output_section,
3639 offset_in_output_section,
3640 rr,
3641 view,
3642 view_address,
3643 view_size,
3644 reloc_view,
3645 reloc_view_size);
3646 }
3647
3648 // Return the value to use for a dynamic which requires special
3649 // treatment. This is how we support equality comparisons of function
3650 // pointers across shared library boundaries, as described in the
3651 // processor specific ABI supplement.
3652
3653 uint64_t
3654 Target_i386::do_dynsym_value(const Symbol* gsym) const
3655 {
3656 gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
3657 return this->plt_address_for_global(gsym);
3658 }
3659
3660 // Return a string used to fill a code section with nops to take up
3661 // the specified length.
3662
3663 std::string
3664 Target_i386::do_code_fill(section_size_type length) const
3665 {
3666 if (length >= 16)
3667 {
3668 // Build a jmp instruction to skip over the bytes.
3669 unsigned char jmp[5];
3670 jmp[0] = 0xe9;
3671 elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
3672 return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
3673 + std::string(length - 5, static_cast<char>(0x90)));
3674 }
3675
3676 // Nop sequences of various lengths.
3677 const char nop1[1] = { '\x90' }; // nop
3678 const char nop2[2] = { '\x66', '\x90' }; // xchg %ax %ax
3679 const char nop3[3] = { '\x8d', '\x76', '\x00' }; // leal 0(%esi),%esi
3680 const char nop4[4] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
3681 '\x00'};
3682 const char nop5[5] = { '\x90', '\x8d', '\x74', // nop
3683 '\x26', '\x00' }; // leal 0(%esi,1),%esi
3684 const char nop6[6] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
3685 '\x00', '\x00', '\x00' };
3686 const char nop7[7] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
3687 '\x00', '\x00', '\x00',
3688 '\x00' };
3689 const char nop8[8] = { '\x90', '\x8d', '\xb4', // nop
3690 '\x26', '\x00', '\x00', // leal 0L(%esi,1),%esi
3691 '\x00', '\x00' };
3692 const char nop9[9] = { '\x89', '\xf6', '\x8d', // movl %esi,%esi
3693 '\xbc', '\x27', '\x00', // leal 0L(%edi,1),%edi
3694 '\x00', '\x00', '\x00' };
3695 const char nop10[10] = { '\x8d', '\x76', '\x00', // leal 0(%esi),%esi
3696 '\x8d', '\xbc', '\x27', // leal 0L(%edi,1),%edi
3697 '\x00', '\x00', '\x00',
3698 '\x00' };
3699 const char nop11[11] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
3700 '\x00', '\x8d', '\xbc', // leal 0L(%edi,1),%edi
3701 '\x27', '\x00', '\x00',
3702 '\x00', '\x00' };
3703 const char nop12[12] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
3704 '\x00', '\x00', '\x00', // leal 0L(%edi),%edi
3705 '\x8d', '\xbf', '\x00',
3706 '\x00', '\x00', '\x00' };
3707 const char nop13[13] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
3708 '\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
3709 '\x8d', '\xbc', '\x27',
3710 '\x00', '\x00', '\x00',
3711 '\x00' };
3712 const char nop14[14] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
3713 '\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
3714 '\x00', '\x8d', '\xbc',
3715 '\x27', '\x00', '\x00',
3716 '\x00', '\x00' };
3717 const char nop15[15] = { '\xeb', '\x0d', '\x90', // jmp .+15
3718 '\x90', '\x90', '\x90', // nop,nop,nop,...
3719 '\x90', '\x90', '\x90',
3720 '\x90', '\x90', '\x90',
3721 '\x90', '\x90', '\x90' };
3722
3723 const char* nops[16] = {
3724 NULL,
3725 nop1, nop2, nop3, nop4, nop5, nop6, nop7,
3726 nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
3727 };
3728
3729 return std::string(nops[length], length);
3730 }
3731
3732 // Return the value to use for the base of a DW_EH_PE_datarel offset
3733 // in an FDE. Solaris and SVR4 use DW_EH_PE_datarel because their
3734 // assembler can not write out the difference between two labels in
3735 // different sections, so instead of using a pc-relative value they
3736 // use an offset from the GOT.
3737
3738 uint64_t
3739 Target_i386::do_ehframe_datarel_base() const
3740 {
3741 gold_assert(this->global_offset_table_ != NULL);
3742 Symbol* sym = this->global_offset_table_;
3743 Sized_symbol<32>* ssym = static_cast<Sized_symbol<32>*>(sym);
3744 return ssym->value();
3745 }
3746
3747 // Return whether SYM should be treated as a call to a non-split
3748 // function. We don't want that to be true of a call to a
3749 // get_pc_thunk function.
3750
3751 bool
3752 Target_i386::do_is_call_to_non_split(const Symbol* sym, unsigned int) const
3753 {
3754 return (sym->type() == elfcpp::STT_FUNC
3755 && !is_prefix_of("__i686.get_pc_thunk.", sym->name()));
3756 }
3757
3758 // FNOFFSET in section SHNDX in OBJECT is the start of a function
3759 // compiled with -fsplit-stack. The function calls non-split-stack
3760 // code. We have to change the function so that it always ensures
3761 // that it has enough stack space to run some random function.
3762
3763 void
3764 Target_i386::do_calls_non_split(Relobj* object, unsigned int shndx,
3765 section_offset_type fnoffset,
3766 section_size_type fnsize,
3767 unsigned char* view,
3768 section_size_type view_size,
3769 std::string* from,
3770 std::string* to) const
3771 {
3772 // The function starts with a comparison of the stack pointer and a
3773 // field in the TCB. This is followed by a jump.
3774
3775 // cmp %gs:NN,%esp
3776 if (this->match_view(view, view_size, fnoffset, "\x65\x3b\x25", 3)
3777 && fnsize > 7)
3778 {
3779 // We will call __morestack if the carry flag is set after this
3780 // comparison. We turn the comparison into an stc instruction
3781 // and some nops.
3782 view[fnoffset] = '\xf9';
3783 this->set_view_to_nop(view, view_size, fnoffset + 1, 6);
3784 }
3785 // lea NN(%esp),%ecx
3786 // lea NN(%esp),%edx
3787 else if ((this->match_view(view, view_size, fnoffset, "\x8d\x8c\x24", 3)
3788 || this->match_view(view, view_size, fnoffset, "\x8d\x94\x24", 3))
3789 && fnsize > 7)
3790 {
3791 // This is loading an offset from the stack pointer for a
3792 // comparison. The offset is negative, so we decrease the
3793 // offset by the amount of space we need for the stack. This
3794 // means we will avoid calling __morestack if there happens to
3795 // be plenty of space on the stack already.
3796 unsigned char* pval = view + fnoffset + 3;
3797 uint32_t val = elfcpp::Swap_unaligned<32, false>::readval(pval);
3798 val -= parameters->options().split_stack_adjust_size();
3799 elfcpp::Swap_unaligned<32, false>::writeval(pval, val);
3800 }
3801 else
3802 {
3803 if (!object->has_no_split_stack())
3804 object->error(_("failed to match split-stack sequence at "
3805 "section %u offset %0zx"),
3806 shndx, static_cast<size_t>(fnoffset));
3807 return;
3808 }
3809
3810 // We have to change the function so that it calls
3811 // __morestack_non_split instead of __morestack. The former will
3812 // allocate additional stack space.
3813 *from = "__morestack";
3814 *to = "__morestack_non_split";
3815 }
3816
3817 // The selector for i386 object files. Note this is never instantiated
3818 // directly. It's only used in Target_selector_i386_nacl, below.
3819
3820 class Target_selector_i386 : public Target_selector_freebsd
3821 {
3822 public:
3823 Target_selector_i386()
3824 : Target_selector_freebsd(elfcpp::EM_386, 32, false,
3825 "elf32-i386", "elf32-i386-freebsd",
3826 "elf_i386")
3827 { }
3828
3829 Target*
3830 do_instantiate_target()
3831 { return new Target_i386(); }
3832 };
3833
3834 // NaCl variant. It uses different PLT contents.
3835
3836 class Output_data_plt_i386_nacl : public Output_data_plt_i386
3837 {
3838 public:
3839 Output_data_plt_i386_nacl(Layout* layout,
3840 Output_data_space* got_plt,
3841 Output_data_space* got_irelative)
3842 : Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
3843 { }
3844
3845 protected:
3846 virtual unsigned int
3847 do_get_plt_entry_size() const
3848 { return plt_entry_size; }
3849
3850 virtual void
3851 do_add_eh_frame(Layout* layout)
3852 {
3853 layout->add_eh_frame_for_plt(this, plt_eh_frame_cie, plt_eh_frame_cie_size,
3854 plt_eh_frame_fde, plt_eh_frame_fde_size);
3855 }
3856
3857 // The size of an entry in the PLT.
3858 static const int plt_entry_size = 64;
3859
3860 // The .eh_frame unwind information for the PLT.
3861 static const int plt_eh_frame_fde_size = 32;
3862 static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
3863 };
3864
3865 class Output_data_plt_i386_nacl_exec : public Output_data_plt_i386_nacl
3866 {
3867 public:
3868 Output_data_plt_i386_nacl_exec(Layout* layout,
3869 Output_data_space* got_plt,
3870 Output_data_space* got_irelative)
3871 : Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
3872 { }
3873
3874 protected:
3875 virtual void
3876 do_fill_first_plt_entry(unsigned char* pov,
3877 elfcpp::Elf_types<32>::Elf_Addr got_address);
3878
3879 virtual unsigned int
3880 do_fill_plt_entry(unsigned char* pov,
3881 elfcpp::Elf_types<32>::Elf_Addr got_address,
3882 unsigned int got_offset,
3883 unsigned int plt_offset,
3884 unsigned int plt_rel_offset);
3885
3886 private:
3887 // The first entry in the PLT for an executable.
3888 static const unsigned char first_plt_entry[plt_entry_size];
3889
3890 // Other entries in the PLT for an executable.
3891 static const unsigned char plt_entry[plt_entry_size];
3892 };
3893
3894 class Output_data_plt_i386_nacl_dyn : public Output_data_plt_i386_nacl
3895 {
3896 public:
3897 Output_data_plt_i386_nacl_dyn(Layout* layout,
3898 Output_data_space* got_plt,
3899 Output_data_space* got_irelative)
3900 : Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
3901 { }
3902
3903 protected:
3904 virtual void
3905 do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<32>::Elf_Addr);
3906
3907 virtual unsigned int
3908 do_fill_plt_entry(unsigned char* pov,
3909 elfcpp::Elf_types<32>::Elf_Addr,
3910 unsigned int got_offset,
3911 unsigned int plt_offset,
3912 unsigned int plt_rel_offset);
3913
3914 private:
3915 // The first entry in the PLT for a shared object.
3916 static const unsigned char first_plt_entry[plt_entry_size];
3917
3918 // Other entries in the PLT for a shared object.
3919 static const unsigned char plt_entry[plt_entry_size];
3920 };
3921
3922 class Target_i386_nacl : public Target_i386
3923 {
3924 public:
3925 Target_i386_nacl()
3926 : Target_i386(&i386_nacl_info)
3927 { }
3928
3929 protected:
3930 virtual Output_data_plt_i386*
3931 do_make_data_plt(Layout* layout,
3932 Output_data_space* got_plt,
3933 Output_data_space* got_irelative,
3934 bool dyn)
3935 {
3936 if (dyn)
3937 return new Output_data_plt_i386_nacl_dyn(layout, got_plt, got_irelative);
3938 else
3939 return new Output_data_plt_i386_nacl_exec(layout, got_plt, got_irelative);
3940 }
3941
3942 private:
3943 static const Target::Target_info i386_nacl_info;
3944 };
3945
3946 const Target::Target_info Target_i386_nacl::i386_nacl_info =
3947 {
3948 32, // size
3949 false, // is_big_endian
3950 elfcpp::EM_386, // machine_code
3951 false, // has_make_symbol
3952 false, // has_resolve
3953 true, // has_code_fill
3954 true, // is_default_stack_executable
3955 true, // can_icf_inline_merge_sections
3956 '\0', // wrap_char
3957 "/lib/ld-nacl-x86-32.so.1", // dynamic_linker
3958 0x20000, // default_text_segment_address
3959 0x10000, // abi_pagesize (overridable by -z max-page-size)
3960 0x10000, // common_pagesize (overridable by -z common-page-size)
3961 true, // isolate_execinstr
3962 0x10000000, // rosegment_gap
3963 elfcpp::SHN_UNDEF, // small_common_shndx
3964 elfcpp::SHN_UNDEF, // large_common_shndx
3965 0, // small_common_section_flags
3966 0, // large_common_section_flags
3967 NULL, // attributes_section
3968 NULL, // attributes_vendor
3969 "_start" // entry_symbol_name
3970 };
3971
3972 #define NACLMASK 0xe0 // 32-byte alignment mask
3973
3974 const unsigned char
3975 Output_data_plt_i386_nacl_exec::first_plt_entry[plt_entry_size] =
3976 {
3977 0xff, 0x35, // pushl contents of memory address
3978 0, 0, 0, 0, // replaced with address of .got + 4
3979 0x8b, 0x0d, // movl contents of address, %ecx
3980 0, 0, 0, 0, // replaced with address of .got + 8
3981 0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
3982 0xff, 0xe1, // jmp *%ecx
3983 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3984 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3985 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3986 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3987 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3988 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3989 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
3990 0x90, 0x90, 0x90, 0x90, 0x90
3991 };
3992
3993 void
3994 Output_data_plt_i386_nacl_exec::do_fill_first_plt_entry(
3995 unsigned char* pov,
3996 elfcpp::Elf_types<32>::Elf_Addr got_address)
3997 {
3998 memcpy(pov, first_plt_entry, plt_entry_size);
3999 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
4000 elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
4001 }
4002
4003 // The first entry in the PLT for a shared object.
4004
4005 const unsigned char
4006 Output_data_plt_i386_nacl_dyn::first_plt_entry[plt_entry_size] =
4007 {
4008 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
4009 0x8b, 0x4b, 0x08, // mov 0x8(%ebx), %ecx
4010 0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
4011 0xff, 0xe1, // jmp *%ecx
4012 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4013 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4014 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4015 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4016 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4017 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4018 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4019 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4020 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4021 0x90, 0x90, 0x90, 0x90, 0x90 // nops
4022 };
4023
4024 void
4025 Output_data_plt_i386_nacl_dyn::do_fill_first_plt_entry(
4026 unsigned char* pov,
4027 elfcpp::Elf_types<32>::Elf_Addr)
4028 {
4029 memcpy(pov, first_plt_entry, plt_entry_size);
4030 }
4031
4032 // Subsequent entries in the PLT for an executable.
4033
4034 const unsigned char
4035 Output_data_plt_i386_nacl_exec::plt_entry[plt_entry_size] =
4036 {
4037 0x8b, 0x0d, // movl contents of address, %ecx */
4038 0, 0, 0, 0, // replaced with address of symbol in .got
4039 0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
4040 0xff, 0xe1, // jmp *%ecx
4041
4042 // Pad to the next 32-byte boundary with nop instructions.
4043 0x90,
4044 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4045 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4046
4047 // Lazy GOT entries point here (32-byte aligned).
4048 0x68, // pushl immediate
4049 0, 0, 0, 0, // replaced with offset into relocation table
4050 0xe9, // jmp relative
4051 0, 0, 0, 0, // replaced with offset to start of .plt
4052
4053 // Pad to the next 32-byte boundary with nop instructions.
4054 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4055 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4056 0x90, 0x90
4057 };
4058
4059 unsigned int
4060 Output_data_plt_i386_nacl_exec::do_fill_plt_entry(
4061 unsigned char* pov,
4062 elfcpp::Elf_types<32>::Elf_Addr got_address,
4063 unsigned int got_offset,
4064 unsigned int plt_offset,
4065 unsigned int plt_rel_offset)
4066 {
4067 memcpy(pov, plt_entry, plt_entry_size);
4068 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
4069 got_address + got_offset);
4070 elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_rel_offset);
4071 elfcpp::Swap<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4));
4072 return 32;
4073 }
4074
4075 // Subsequent entries in the PLT for a shared object.
4076
4077 const unsigned char
4078 Output_data_plt_i386_nacl_dyn::plt_entry[plt_entry_size] =
4079 {
4080 0x8b, 0x8b, // movl offset(%ebx), %ecx
4081 0, 0, 0, 0, // replaced with offset of symbol in .got
4082 0x83, 0xe1, 0xe0, // andl $NACLMASK, %ecx
4083 0xff, 0xe1, // jmp *%ecx
4084
4085 // Pad to the next 32-byte boundary with nop instructions.
4086 0x90,
4087 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4088 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4089
4090 // Lazy GOT entries point here (32-byte aligned).
4091 0x68, // pushl immediate
4092 0, 0, 0, 0, // replaced with offset into relocation table.
4093 0xe9, // jmp relative
4094 0, 0, 0, 0, // replaced with offset to start of .plt.
4095
4096 // Pad to the next 32-byte boundary with nop instructions.
4097 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4098 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4099 0x90, 0x90
4100 };
4101
4102 unsigned int
4103 Output_data_plt_i386_nacl_dyn::do_fill_plt_entry(
4104 unsigned char* pov,
4105 elfcpp::Elf_types<32>::Elf_Addr,
4106 unsigned int got_offset,
4107 unsigned int plt_offset,
4108 unsigned int plt_rel_offset)
4109 {
4110 memcpy(pov, plt_entry, plt_entry_size);
4111 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
4112 elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_rel_offset);
4113 elfcpp::Swap<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4));
4114 return 32;
4115 }
4116
4117 const unsigned char
4118 Output_data_plt_i386_nacl::plt_eh_frame_fde[plt_eh_frame_fde_size] =
4119 {
4120 0, 0, 0, 0, // Replaced with offset to .plt.
4121 0, 0, 0, 0, // Replaced with size of .plt.
4122 0, // Augmentation size.
4123 elfcpp::DW_CFA_def_cfa_offset, 8, // DW_CFA_def_cfa_offset: 8.
4124 elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
4125 elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
4126 elfcpp::DW_CFA_advance_loc + 58, // Advance 58 to __PLT__ + 64.
4127 elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
4128 13, // Block length.
4129 elfcpp::DW_OP_breg4, 4, // Push %esp + 4.
4130 elfcpp::DW_OP_breg8, 0, // Push %eip.
4131 elfcpp::DW_OP_const1u, 63, // Push 0x3f.
4132 elfcpp::DW_OP_and, // & (%eip & 0x3f).
4133 elfcpp::DW_OP_const1u, 37, // Push 0x25.
4134 elfcpp::DW_OP_ge, // >= ((%eip & 0x3f) >= 0x25)
4135 elfcpp::DW_OP_lit2, // Push 2.
4136 elfcpp::DW_OP_shl, // << (((%eip & 0x3f) >= 0x25) << 2)
4137 elfcpp::DW_OP_plus, // + ((((%eip&0x3f)>=0x25)<<2)+%esp+4
4138 elfcpp::DW_CFA_nop, // Align to 32 bytes.
4139 elfcpp::DW_CFA_nop
4140 };
4141
4142 // The selector for i386-nacl object files.
4143
4144 class Target_selector_i386_nacl
4145 : public Target_selector_nacl<Target_selector_i386, Target_i386_nacl>
4146 {
4147 public:
4148 Target_selector_i386_nacl()
4149 : Target_selector_nacl<Target_selector_i386,
4150 Target_i386_nacl>("x86-32",
4151 "elf32-i386-nacl",
4152 "elf_i386_nacl")
4153 { }
4154 };
4155
4156 Target_selector_i386_nacl target_selector_i386;
4157
4158 } // End anonymous namespace.
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