PR gold/12980
[deliverable/binutils-gdb.git] / gold / i386.cc
1 // i386.cc -- i386 target support for gold.
2
3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
5
6 // This file is part of gold.
7
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
12
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
17
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
22
23 #include "gold.h"
24
25 #include <cstring>
26
27 #include "elfcpp.h"
28 #include "dwarf.h"
29 #include "parameters.h"
30 #include "reloc.h"
31 #include "i386.h"
32 #include "object.h"
33 #include "symtab.h"
34 #include "layout.h"
35 #include "output.h"
36 #include "copy-relocs.h"
37 #include "target.h"
38 #include "target-reloc.h"
39 #include "target-select.h"
40 #include "tls.h"
41 #include "freebsd.h"
42 #include "gc.h"
43
44 namespace
45 {
46
47 using namespace gold;
48
49 // A class to handle the PLT data.
50
51 class Output_data_plt_i386 : public Output_section_data
52 {
53 public:
54 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
55
56 Output_data_plt_i386(Layout*, Output_data_space*, Output_data_space*);
57
58 // Add an entry to the PLT.
59 void
60 add_entry(Symbol_table*, Layout*, Symbol* gsym);
61
62 // Add an entry to the PLT for a local STT_GNU_IFUNC symbol.
63 unsigned int
64 add_local_ifunc_entry(Symbol_table*, Layout*,
65 Sized_relobj_file<32, false>* relobj,
66 unsigned int local_sym_index);
67
68 // Return the .rel.plt section data.
69 Reloc_section*
70 rel_plt() const
71 { return this->rel_; }
72
73 // Return where the TLS_DESC relocations should go.
74 Reloc_section*
75 rel_tls_desc(Layout*);
76
77 // Return where the IRELATIVE relocations should go.
78 Reloc_section*
79 rel_irelative(Symbol_table*, Layout*);
80
81 // Return whether we created a section for IRELATIVE relocations.
82 bool
83 has_irelative_section() const
84 { return this->irelative_rel_ != NULL; }
85
86 // Return the number of PLT entries.
87 unsigned int
88 entry_count() const
89 { return this->count_ + this->irelative_count_; }
90
91 // Return the offset of the first non-reserved PLT entry.
92 static unsigned int
93 first_plt_entry_offset()
94 { return plt_entry_size; }
95
96 // Return the size of a PLT entry.
97 static unsigned int
98 get_plt_entry_size()
99 { return plt_entry_size; }
100
101 // Return the PLT address to use for a global symbol.
102 uint64_t
103 address_for_global(const Symbol*);
104
105 // Return the PLT address to use for a local symbol.
106 uint64_t
107 address_for_local(const Relobj*, unsigned int symndx);
108
109 protected:
110 void
111 do_adjust_output_section(Output_section* os);
112
113 // Write to a map file.
114 void
115 do_print_to_mapfile(Mapfile* mapfile) const
116 { mapfile->print_output_data(this, _("** PLT")); }
117
118 private:
119 // The size of an entry in the PLT.
120 static const int plt_entry_size = 16;
121
122 // The first entry in the PLT for an executable.
123 static const unsigned char exec_first_plt_entry[plt_entry_size];
124
125 // The first entry in the PLT for a shared object.
126 static const unsigned char dyn_first_plt_entry[plt_entry_size];
127
128 // Other entries in the PLT for an executable.
129 static const unsigned char exec_plt_entry[plt_entry_size];
130
131 // Other entries in the PLT for a shared object.
132 static const unsigned char dyn_plt_entry[plt_entry_size];
133
134 // The .eh_frame unwind information for the PLT.
135 static const int plt_eh_frame_cie_size = 16;
136 static const int plt_eh_frame_fde_size = 32;
137 static const unsigned char plt_eh_frame_cie[plt_eh_frame_cie_size];
138 static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
139
140 // Set the final size.
141 void
142 set_final_data_size()
143 {
144 this->set_data_size((this->count_ + this->irelative_count_ + 1)
145 * plt_entry_size);
146 }
147
148 // Write out the PLT data.
149 void
150 do_write(Output_file*);
151
152 // We keep a list of global STT_GNU_IFUNC symbols, each with its
153 // offset in the GOT.
154 struct Global_ifunc
155 {
156 Symbol* sym;
157 unsigned int got_offset;
158 };
159
160 // We keep a list of local STT_GNU_IFUNC symbols, each with its
161 // offset in the GOT.
162 struct Local_ifunc
163 {
164 Sized_relobj_file<32, false>* object;
165 unsigned int local_sym_index;
166 unsigned int got_offset;
167 };
168
169 // The reloc section.
170 Reloc_section* rel_;
171 // The TLS_DESC relocations, if necessary. These must follow the
172 // regular PLT relocs.
173 Reloc_section* tls_desc_rel_;
174 // The IRELATIVE relocations, if necessary. These must follow the
175 // regular relocatoins and the TLS_DESC relocations.
176 Reloc_section* irelative_rel_;
177 // The .got.plt section.
178 Output_data_space* got_plt_;
179 // The part of the .got.plt section used for IRELATIVE relocs.
180 Output_data_space* got_irelative_;
181 // The number of PLT entries.
182 unsigned int count_;
183 // Number of PLT entries with R_386_IRELATIVE relocs. These follow
184 // the regular PLT entries.
185 unsigned int irelative_count_;
186 // Global STT_GNU_IFUNC symbols.
187 std::vector<Global_ifunc> global_ifuncs_;
188 // Local STT_GNU_IFUNC symbols.
189 std::vector<Local_ifunc> local_ifuncs_;
190 };
191
192 // The i386 target class.
193 // TLS info comes from
194 // http://people.redhat.com/drepper/tls.pdf
195 // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
196
197 class Target_i386 : public Sized_target<32, false>
198 {
199 public:
200 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
201
202 Target_i386()
203 : Sized_target<32, false>(&i386_info),
204 got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL),
205 got_tlsdesc_(NULL), global_offset_table_(NULL), rel_dyn_(NULL),
206 rel_irelative_(NULL), copy_relocs_(elfcpp::R_386_COPY), dynbss_(NULL),
207 got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
208 { }
209
210 // Process the relocations to determine unreferenced sections for
211 // garbage collection.
212 void
213 gc_process_relocs(Symbol_table* symtab,
214 Layout* layout,
215 Sized_relobj_file<32, false>* object,
216 unsigned int data_shndx,
217 unsigned int sh_type,
218 const unsigned char* prelocs,
219 size_t reloc_count,
220 Output_section* output_section,
221 bool needs_special_offset_handling,
222 size_t local_symbol_count,
223 const unsigned char* plocal_symbols);
224
225 // Scan the relocations to look for symbol adjustments.
226 void
227 scan_relocs(Symbol_table* symtab,
228 Layout* layout,
229 Sized_relobj_file<32, false>* object,
230 unsigned int data_shndx,
231 unsigned int sh_type,
232 const unsigned char* prelocs,
233 size_t reloc_count,
234 Output_section* output_section,
235 bool needs_special_offset_handling,
236 size_t local_symbol_count,
237 const unsigned char* plocal_symbols);
238
239 // Finalize the sections.
240 void
241 do_finalize_sections(Layout*, const Input_objects*, Symbol_table*);
242
243 // Return the value to use for a dynamic which requires special
244 // treatment.
245 uint64_t
246 do_dynsym_value(const Symbol*) const;
247
248 // Relocate a section.
249 void
250 relocate_section(const Relocate_info<32, false>*,
251 unsigned int sh_type,
252 const unsigned char* prelocs,
253 size_t reloc_count,
254 Output_section* output_section,
255 bool needs_special_offset_handling,
256 unsigned char* view,
257 elfcpp::Elf_types<32>::Elf_Addr view_address,
258 section_size_type view_size,
259 const Reloc_symbol_changes*);
260
261 // Scan the relocs during a relocatable link.
262 void
263 scan_relocatable_relocs(Symbol_table* symtab,
264 Layout* layout,
265 Sized_relobj_file<32, false>* object,
266 unsigned int data_shndx,
267 unsigned int sh_type,
268 const unsigned char* prelocs,
269 size_t reloc_count,
270 Output_section* output_section,
271 bool needs_special_offset_handling,
272 size_t local_symbol_count,
273 const unsigned char* plocal_symbols,
274 Relocatable_relocs*);
275
276 // Relocate a section during a relocatable link.
277 void
278 relocate_for_relocatable(const Relocate_info<32, false>*,
279 unsigned int sh_type,
280 const unsigned char* prelocs,
281 size_t reloc_count,
282 Output_section* output_section,
283 off_t offset_in_output_section,
284 const Relocatable_relocs*,
285 unsigned char* view,
286 elfcpp::Elf_types<32>::Elf_Addr view_address,
287 section_size_type view_size,
288 unsigned char* reloc_view,
289 section_size_type reloc_view_size);
290
291 // Return a string used to fill a code section with nops.
292 std::string
293 do_code_fill(section_size_type length) const;
294
295 // Return whether SYM is defined by the ABI.
296 bool
297 do_is_defined_by_abi(const Symbol* sym) const
298 { return strcmp(sym->name(), "___tls_get_addr") == 0; }
299
300 // Return whether a symbol name implies a local label. The UnixWare
301 // 2.1 cc generates temporary symbols that start with .X, so we
302 // recognize them here. FIXME: do other SVR4 compilers also use .X?.
303 // If so, we should move the .X recognition into
304 // Target::do_is_local_label_name.
305 bool
306 do_is_local_label_name(const char* name) const
307 {
308 if (name[0] == '.' && name[1] == 'X')
309 return true;
310 return Target::do_is_local_label_name(name);
311 }
312
313 // Return the PLT address to use for a global symbol.
314 uint64_t
315 do_plt_address_for_global(const Symbol* gsym) const
316 { return this->plt_section()->address_for_global(gsym); }
317
318 uint64_t
319 do_plt_address_for_local(const Relobj* relobj, unsigned int symndx) const
320 { return this->plt_section()->address_for_local(relobj, symndx); }
321
322 // We can tell whether we take the address of a function.
323 inline bool
324 do_can_check_for_function_pointers() const
325 { return true; }
326
327 // Return the base for a DW_EH_PE_datarel encoding.
328 uint64_t
329 do_ehframe_datarel_base() const;
330
331 // Return whether SYM is call to a non-split function.
332 bool
333 do_is_call_to_non_split(const Symbol* sym, unsigned int) const;
334
335 // Adjust -fsplit-stack code which calls non-split-stack code.
336 void
337 do_calls_non_split(Relobj* object, unsigned int shndx,
338 section_offset_type fnoffset, section_size_type fnsize,
339 unsigned char* view, section_size_type view_size,
340 std::string* from, std::string* to) const;
341
342 // Return the size of the GOT section.
343 section_size_type
344 got_size() const
345 {
346 gold_assert(this->got_ != NULL);
347 return this->got_->data_size();
348 }
349
350 // Return the number of entries in the GOT.
351 unsigned int
352 got_entry_count() const
353 {
354 if (this->got_ == NULL)
355 return 0;
356 return this->got_size() / 4;
357 }
358
359 // Return the number of entries in the PLT.
360 unsigned int
361 plt_entry_count() const;
362
363 // Return the offset of the first non-reserved PLT entry.
364 unsigned int
365 first_plt_entry_offset() const;
366
367 // Return the size of each PLT entry.
368 unsigned int
369 plt_entry_size() const;
370
371 private:
372 // The class which scans relocations.
373 struct Scan
374 {
375 static inline int
376
377 get_reference_flags(unsigned int r_type);
378
379 inline void
380 local(Symbol_table* symtab, Layout* layout, Target_i386* target,
381 Sized_relobj_file<32, false>* object,
382 unsigned int data_shndx,
383 Output_section* output_section,
384 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
385 const elfcpp::Sym<32, false>& lsym);
386
387 inline void
388 global(Symbol_table* symtab, Layout* layout, Target_i386* target,
389 Sized_relobj_file<32, false>* object,
390 unsigned int data_shndx,
391 Output_section* output_section,
392 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
393 Symbol* gsym);
394
395 inline bool
396 local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
397 Target_i386* target,
398 Sized_relobj_file<32, false>* object,
399 unsigned int data_shndx,
400 Output_section* output_section,
401 const elfcpp::Rel<32, false>& reloc,
402 unsigned int r_type,
403 const elfcpp::Sym<32, false>& lsym);
404
405 inline bool
406 global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
407 Target_i386* target,
408 Sized_relobj_file<32, false>* object,
409 unsigned int data_shndx,
410 Output_section* output_section,
411 const elfcpp::Rel<32, false>& reloc,
412 unsigned int r_type,
413 Symbol* gsym);
414
415 inline bool
416 possible_function_pointer_reloc(unsigned int r_type);
417
418 bool
419 reloc_needs_plt_for_ifunc(Sized_relobj_file<32, false>*,
420 unsigned int r_type);
421
422 static void
423 unsupported_reloc_local(Sized_relobj_file<32, false>*, unsigned int r_type);
424
425 static void
426 unsupported_reloc_global(Sized_relobj_file<32, false>*, unsigned int r_type,
427 Symbol*);
428 };
429
430 // The class which implements relocation.
431 class Relocate
432 {
433 public:
434 Relocate()
435 : skip_call_tls_get_addr_(false),
436 local_dynamic_type_(LOCAL_DYNAMIC_NONE)
437 { }
438
439 ~Relocate()
440 {
441 if (this->skip_call_tls_get_addr_)
442 {
443 // FIXME: This needs to specify the location somehow.
444 gold_error(_("missing expected TLS relocation"));
445 }
446 }
447
448 // Return whether the static relocation needs to be applied.
449 inline bool
450 should_apply_static_reloc(const Sized_symbol<32>* gsym,
451 unsigned int r_type,
452 bool is_32bit,
453 Output_section* output_section);
454
455 // Do a relocation. Return false if the caller should not issue
456 // any warnings about this relocation.
457 inline bool
458 relocate(const Relocate_info<32, false>*, Target_i386*, Output_section*,
459 size_t relnum, const elfcpp::Rel<32, false>&,
460 unsigned int r_type, const Sized_symbol<32>*,
461 const Symbol_value<32>*,
462 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
463 section_size_type);
464
465 private:
466 // Do a TLS relocation.
467 inline void
468 relocate_tls(const Relocate_info<32, false>*, Target_i386* target,
469 size_t relnum, const elfcpp::Rel<32, false>&,
470 unsigned int r_type, const Sized_symbol<32>*,
471 const Symbol_value<32>*,
472 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
473 section_size_type);
474
475 // Do a TLS General-Dynamic to Initial-Exec transition.
476 inline void
477 tls_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
478 Output_segment* tls_segment,
479 const elfcpp::Rel<32, false>&, unsigned int r_type,
480 elfcpp::Elf_types<32>::Elf_Addr value,
481 unsigned char* view,
482 section_size_type view_size);
483
484 // Do a TLS General-Dynamic to Local-Exec transition.
485 inline void
486 tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
487 Output_segment* tls_segment,
488 const elfcpp::Rel<32, false>&, unsigned int r_type,
489 elfcpp::Elf_types<32>::Elf_Addr value,
490 unsigned char* view,
491 section_size_type view_size);
492
493 // Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Initial-Exec
494 // transition.
495 inline void
496 tls_desc_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
497 Output_segment* tls_segment,
498 const elfcpp::Rel<32, false>&, unsigned int r_type,
499 elfcpp::Elf_types<32>::Elf_Addr value,
500 unsigned char* view,
501 section_size_type view_size);
502
503 // Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Local-Exec
504 // transition.
505 inline void
506 tls_desc_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
507 Output_segment* tls_segment,
508 const elfcpp::Rel<32, false>&, unsigned int r_type,
509 elfcpp::Elf_types<32>::Elf_Addr value,
510 unsigned char* view,
511 section_size_type view_size);
512
513 // Do a TLS Local-Dynamic to Local-Exec transition.
514 inline void
515 tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
516 Output_segment* tls_segment,
517 const elfcpp::Rel<32, false>&, unsigned int r_type,
518 elfcpp::Elf_types<32>::Elf_Addr value,
519 unsigned char* view,
520 section_size_type view_size);
521
522 // Do a TLS Initial-Exec to Local-Exec transition.
523 static inline void
524 tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
525 Output_segment* tls_segment,
526 const elfcpp::Rel<32, false>&, unsigned int r_type,
527 elfcpp::Elf_types<32>::Elf_Addr value,
528 unsigned char* view,
529 section_size_type view_size);
530
531 // We need to keep track of which type of local dynamic relocation
532 // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
533 enum Local_dynamic_type
534 {
535 LOCAL_DYNAMIC_NONE,
536 LOCAL_DYNAMIC_SUN,
537 LOCAL_DYNAMIC_GNU
538 };
539
540 // This is set if we should skip the next reloc, which should be a
541 // PLT32 reloc against ___tls_get_addr.
542 bool skip_call_tls_get_addr_;
543 // The type of local dynamic relocation we have seen in the section
544 // being relocated, if any.
545 Local_dynamic_type local_dynamic_type_;
546 };
547
548 // A class which returns the size required for a relocation type,
549 // used while scanning relocs during a relocatable link.
550 class Relocatable_size_for_reloc
551 {
552 public:
553 unsigned int
554 get_size_for_reloc(unsigned int, Relobj*);
555 };
556
557 // Adjust TLS relocation type based on the options and whether this
558 // is a local symbol.
559 static tls::Tls_optimization
560 optimize_tls_reloc(bool is_final, int r_type);
561
562 // Get the GOT section, creating it if necessary.
563 Output_data_got<32, false>*
564 got_section(Symbol_table*, Layout*);
565
566 // Get the GOT PLT section.
567 Output_data_space*
568 got_plt_section() const
569 {
570 gold_assert(this->got_plt_ != NULL);
571 return this->got_plt_;
572 }
573
574 // Get the GOT section for TLSDESC entries.
575 Output_data_got<32, false>*
576 got_tlsdesc_section() const
577 {
578 gold_assert(this->got_tlsdesc_ != NULL);
579 return this->got_tlsdesc_;
580 }
581
582 // Create the PLT section.
583 void
584 make_plt_section(Symbol_table* symtab, Layout* layout);
585
586 // Create a PLT entry for a global symbol.
587 void
588 make_plt_entry(Symbol_table*, Layout*, Symbol*);
589
590 // Create a PLT entry for a local STT_GNU_IFUNC symbol.
591 void
592 make_local_ifunc_plt_entry(Symbol_table*, Layout*,
593 Sized_relobj_file<32, false>* relobj,
594 unsigned int local_sym_index);
595
596 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
597 void
598 define_tls_base_symbol(Symbol_table*, Layout*);
599
600 // Create a GOT entry for the TLS module index.
601 unsigned int
602 got_mod_index_entry(Symbol_table* symtab, Layout* layout,
603 Sized_relobj_file<32, false>* object);
604
605 // Get the PLT section.
606 Output_data_plt_i386*
607 plt_section() const
608 {
609 gold_assert(this->plt_ != NULL);
610 return this->plt_;
611 }
612
613 // Get the dynamic reloc section, creating it if necessary.
614 Reloc_section*
615 rel_dyn_section(Layout*);
616
617 // Get the section to use for TLS_DESC relocations.
618 Reloc_section*
619 rel_tls_desc_section(Layout*) const;
620
621 // Get the section to use for IRELATIVE relocations.
622 Reloc_section*
623 rel_irelative_section(Layout*);
624
625 // Add a potential copy relocation.
626 void
627 copy_reloc(Symbol_table* symtab, Layout* layout,
628 Sized_relobj_file<32, false>* object,
629 unsigned int shndx, Output_section* output_section,
630 Symbol* sym, const elfcpp::Rel<32, false>& reloc)
631 {
632 this->copy_relocs_.copy_reloc(symtab, layout,
633 symtab->get_sized_symbol<32>(sym),
634 object, shndx, output_section, reloc,
635 this->rel_dyn_section(layout));
636 }
637
638 // Information about this specific target which we pass to the
639 // general Target structure.
640 static const Target::Target_info i386_info;
641
642 // The types of GOT entries needed for this platform.
643 // These values are exposed to the ABI in an incremental link.
644 // Do not renumber existing values without changing the version
645 // number of the .gnu_incremental_inputs section.
646 enum Got_type
647 {
648 GOT_TYPE_STANDARD = 0, // GOT entry for a regular symbol
649 GOT_TYPE_TLS_NOFFSET = 1, // GOT entry for negative TLS offset
650 GOT_TYPE_TLS_OFFSET = 2, // GOT entry for positive TLS offset
651 GOT_TYPE_TLS_PAIR = 3, // GOT entry for TLS module/offset pair
652 GOT_TYPE_TLS_DESC = 4 // GOT entry for TLS_DESC pair
653 };
654
655 // The GOT section.
656 Output_data_got<32, false>* got_;
657 // The PLT section.
658 Output_data_plt_i386* plt_;
659 // The GOT PLT section.
660 Output_data_space* got_plt_;
661 // The GOT section for IRELATIVE relocations.
662 Output_data_space* got_irelative_;
663 // The GOT section for TLSDESC relocations.
664 Output_data_got<32, false>* got_tlsdesc_;
665 // The _GLOBAL_OFFSET_TABLE_ symbol.
666 Symbol* global_offset_table_;
667 // The dynamic reloc section.
668 Reloc_section* rel_dyn_;
669 // The section to use for IRELATIVE relocs.
670 Reloc_section* rel_irelative_;
671 // Relocs saved to avoid a COPY reloc.
672 Copy_relocs<elfcpp::SHT_REL, 32, false> copy_relocs_;
673 // Space for variables copied with a COPY reloc.
674 Output_data_space* dynbss_;
675 // Offset of the GOT entry for the TLS module index.
676 unsigned int got_mod_index_offset_;
677 // True if the _TLS_MODULE_BASE_ symbol has been defined.
678 bool tls_base_symbol_defined_;
679 };
680
681 const Target::Target_info Target_i386::i386_info =
682 {
683 32, // size
684 false, // is_big_endian
685 elfcpp::EM_386, // machine_code
686 false, // has_make_symbol
687 false, // has_resolve
688 true, // has_code_fill
689 true, // is_default_stack_executable
690 true, // can_icf_inline_merge_sections
691 '\0', // wrap_char
692 "/usr/lib/libc.so.1", // dynamic_linker
693 0x08048000, // default_text_segment_address
694 0x1000, // abi_pagesize (overridable by -z max-page-size)
695 0x1000, // common_pagesize (overridable by -z common-page-size)
696 elfcpp::SHN_UNDEF, // small_common_shndx
697 elfcpp::SHN_UNDEF, // large_common_shndx
698 0, // small_common_section_flags
699 0, // large_common_section_flags
700 NULL, // attributes_section
701 NULL // attributes_vendor
702 };
703
704 // Get the GOT section, creating it if necessary.
705
706 Output_data_got<32, false>*
707 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
708 {
709 if (this->got_ == NULL)
710 {
711 gold_assert(symtab != NULL && layout != NULL);
712
713 this->got_ = new Output_data_got<32, false>();
714
715 layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
716 (elfcpp::SHF_ALLOC
717 | elfcpp::SHF_WRITE),
718 this->got_, ORDER_RELRO_LAST, true);
719
720 this->got_plt_ = new Output_data_space(4, "** GOT PLT");
721 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
722 (elfcpp::SHF_ALLOC
723 | elfcpp::SHF_WRITE),
724 this->got_plt_, ORDER_NON_RELRO_FIRST,
725 false);
726
727 // The first three entries are reserved.
728 this->got_plt_->set_current_data_size(3 * 4);
729
730 // Those bytes can go into the relro segment.
731 layout->increase_relro(3 * 4);
732
733 // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
734 this->global_offset_table_ =
735 symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
736 Symbol_table::PREDEFINED,
737 this->got_plt_,
738 0, 0, elfcpp::STT_OBJECT,
739 elfcpp::STB_LOCAL,
740 elfcpp::STV_HIDDEN, 0,
741 false, false);
742
743 // If there are any IRELATIVE relocations, they get GOT entries
744 // in .got.plt after the jump slot relocations.
745 this->got_irelative_ = new Output_data_space(4, "** GOT IRELATIVE PLT");
746 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
747 (elfcpp::SHF_ALLOC
748 | elfcpp::SHF_WRITE),
749 this->got_irelative_,
750 ORDER_NON_RELRO_FIRST, false);
751
752 // If there are any TLSDESC relocations, they get GOT entries in
753 // .got.plt after the jump slot entries.
754 this->got_tlsdesc_ = new Output_data_got<32, false>();
755 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
756 (elfcpp::SHF_ALLOC
757 | elfcpp::SHF_WRITE),
758 this->got_tlsdesc_,
759 ORDER_NON_RELRO_FIRST, false);
760 }
761
762 return this->got_;
763 }
764
765 // Get the dynamic reloc section, creating it if necessary.
766
767 Target_i386::Reloc_section*
768 Target_i386::rel_dyn_section(Layout* layout)
769 {
770 if (this->rel_dyn_ == NULL)
771 {
772 gold_assert(layout != NULL);
773 this->rel_dyn_ = new Reloc_section(parameters->options().combreloc());
774 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
775 elfcpp::SHF_ALLOC, this->rel_dyn_,
776 ORDER_DYNAMIC_RELOCS, false);
777 }
778 return this->rel_dyn_;
779 }
780
781 // Get the section to use for IRELATIVE relocs, creating it if
782 // necessary. These go in .rel.dyn, but only after all other dynamic
783 // relocations. They need to follow the other dynamic relocations so
784 // that they can refer to global variables initialized by those
785 // relocs.
786
787 Target_i386::Reloc_section*
788 Target_i386::rel_irelative_section(Layout* layout)
789 {
790 if (this->rel_irelative_ == NULL)
791 {
792 // Make sure we have already create the dynamic reloc section.
793 this->rel_dyn_section(layout);
794 this->rel_irelative_ = new Reloc_section(false);
795 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
796 elfcpp::SHF_ALLOC, this->rel_irelative_,
797 ORDER_DYNAMIC_RELOCS, false);
798 gold_assert(this->rel_dyn_->output_section()
799 == this->rel_irelative_->output_section());
800 }
801 return this->rel_irelative_;
802 }
803
804 // Create the PLT section. The ordinary .got section is an argument,
805 // since we need to refer to the start. We also create our own .got
806 // section just for PLT entries.
807
808 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
809 Output_data_space* got_plt,
810 Output_data_space* got_irelative)
811 : Output_section_data(16), tls_desc_rel_(NULL), irelative_rel_(NULL),
812 got_plt_(got_plt), got_irelative_(got_irelative), count_(0),
813 irelative_count_(0), global_ifuncs_(), local_ifuncs_()
814 {
815 this->rel_ = new Reloc_section(false);
816 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
817 elfcpp::SHF_ALLOC, this->rel_,
818 ORDER_DYNAMIC_PLT_RELOCS, false);
819
820 // Add unwind information if requested.
821 if (parameters->options().ld_generated_unwind_info())
822 layout->add_eh_frame_for_plt(this, plt_eh_frame_cie, plt_eh_frame_cie_size,
823 plt_eh_frame_fde, plt_eh_frame_fde_size);
824 }
825
826 void
827 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
828 {
829 // UnixWare sets the entsize of .plt to 4, and so does the old GNU
830 // linker, and so do we.
831 os->set_entsize(4);
832 }
833
834 // Add an entry to the PLT.
835
836 void
837 Output_data_plt_i386::add_entry(Symbol_table* symtab, Layout* layout,
838 Symbol* gsym)
839 {
840 gold_assert(!gsym->has_plt_offset());
841
842 // Every PLT entry needs a reloc.
843 if (gsym->type() == elfcpp::STT_GNU_IFUNC
844 && gsym->can_use_relative_reloc(false))
845 {
846 gsym->set_plt_offset(this->irelative_count_ * plt_entry_size);
847 ++this->irelative_count_;
848 section_offset_type got_offset =
849 this->got_irelative_->current_data_size();
850 this->got_irelative_->set_current_data_size(got_offset + 4);
851 Reloc_section* rel = this->rel_irelative(symtab, layout);
852 rel->add_symbolless_global_addend(gsym, elfcpp::R_386_IRELATIVE,
853 this->got_irelative_, got_offset);
854 struct Global_ifunc gi;
855 gi.sym = gsym;
856 gi.got_offset = got_offset;
857 this->global_ifuncs_.push_back(gi);
858 }
859 else
860 {
861 // When setting the PLT offset we skip the initial reserved PLT
862 // entry.
863 gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
864
865 ++this->count_;
866
867 section_offset_type got_offset = this->got_plt_->current_data_size();
868
869 // Every PLT entry needs a GOT entry which points back to the
870 // PLT entry (this will be changed by the dynamic linker,
871 // normally lazily when the function is called).
872 this->got_plt_->set_current_data_size(got_offset + 4);
873
874 gsym->set_needs_dynsym_entry();
875 this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
876 got_offset);
877 }
878
879 // Note that we don't need to save the symbol. The contents of the
880 // PLT are independent of which symbols are used. The symbols only
881 // appear in the relocations.
882 }
883
884 // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. Return
885 // the PLT offset.
886
887 unsigned int
888 Output_data_plt_i386::add_local_ifunc_entry(
889 Symbol_table* symtab,
890 Layout* layout,
891 Sized_relobj_file<32, false>* relobj,
892 unsigned int local_sym_index)
893 {
894 unsigned int plt_offset = this->irelative_count_ * plt_entry_size;
895 ++this->irelative_count_;
896
897 section_offset_type got_offset = this->got_irelative_->current_data_size();
898
899 // Every PLT entry needs a GOT entry which points back to the PLT
900 // entry.
901 this->got_irelative_->set_current_data_size(got_offset + 4);
902
903 // Every PLT entry needs a reloc.
904 Reloc_section* rel = this->rel_irelative(symtab, layout);
905 rel->add_symbolless_local_addend(relobj, local_sym_index,
906 elfcpp::R_386_IRELATIVE,
907 this->got_irelative_, got_offset);
908
909 struct Local_ifunc li;
910 li.object = relobj;
911 li.local_sym_index = local_sym_index;
912 li.got_offset = got_offset;
913 this->local_ifuncs_.push_back(li);
914
915 return plt_offset;
916 }
917
918 // Return where the TLS_DESC relocations should go, creating it if
919 // necessary. These follow the JUMP_SLOT relocations.
920
921 Output_data_plt_i386::Reloc_section*
922 Output_data_plt_i386::rel_tls_desc(Layout* layout)
923 {
924 if (this->tls_desc_rel_ == NULL)
925 {
926 this->tls_desc_rel_ = new Reloc_section(false);
927 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
928 elfcpp::SHF_ALLOC, this->tls_desc_rel_,
929 ORDER_DYNAMIC_PLT_RELOCS, false);
930 gold_assert(this->tls_desc_rel_->output_section()
931 == this->rel_->output_section());
932 }
933 return this->tls_desc_rel_;
934 }
935
936 // Return where the IRELATIVE relocations should go in the PLT. These
937 // follow the JUMP_SLOT and TLS_DESC relocations.
938
939 Output_data_plt_i386::Reloc_section*
940 Output_data_plt_i386::rel_irelative(Symbol_table* symtab, Layout* layout)
941 {
942 if (this->irelative_rel_ == NULL)
943 {
944 // Make sure we have a place for the TLS_DESC relocations, in
945 // case we see any later on.
946 this->rel_tls_desc(layout);
947 this->irelative_rel_ = new Reloc_section(false);
948 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
949 elfcpp::SHF_ALLOC, this->irelative_rel_,
950 ORDER_DYNAMIC_PLT_RELOCS, false);
951 gold_assert(this->irelative_rel_->output_section()
952 == this->rel_->output_section());
953
954 if (parameters->doing_static_link())
955 {
956 // A statically linked executable will only have a .rel.plt
957 // section to hold R_386_IRELATIVE relocs for STT_GNU_IFUNC
958 // symbols. The library will use these symbols to locate
959 // the IRELATIVE relocs at program startup time.
960 symtab->define_in_output_data("__rel_iplt_start", NULL,
961 Symbol_table::PREDEFINED,
962 this->irelative_rel_, 0, 0,
963 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
964 elfcpp::STV_HIDDEN, 0, false, true);
965 symtab->define_in_output_data("__rel_iplt_end", NULL,
966 Symbol_table::PREDEFINED,
967 this->irelative_rel_, 0, 0,
968 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
969 elfcpp::STV_HIDDEN, 0, true, true);
970 }
971 }
972 return this->irelative_rel_;
973 }
974
975 // Return the PLT address to use for a global symbol.
976
977 uint64_t
978 Output_data_plt_i386::address_for_global(const Symbol* gsym)
979 {
980 uint64_t offset = 0;
981 if (gsym->type() == elfcpp::STT_GNU_IFUNC
982 && gsym->can_use_relative_reloc(false))
983 offset = (this->count_ + 1) * plt_entry_size;
984 return this->address() + offset;
985 }
986
987 // Return the PLT address to use for a local symbol. These are always
988 // IRELATIVE relocs.
989
990 uint64_t
991 Output_data_plt_i386::address_for_local(const Relobj*, unsigned int)
992 {
993 return this->address() + (this->count_ + 1) * plt_entry_size;
994 }
995
996 // The first entry in the PLT for an executable.
997
998 const unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
999 {
1000 0xff, 0x35, // pushl contents of memory address
1001 0, 0, 0, 0, // replaced with address of .got + 4
1002 0xff, 0x25, // jmp indirect
1003 0, 0, 0, 0, // replaced with address of .got + 8
1004 0, 0, 0, 0 // unused
1005 };
1006
1007 // The first entry in the PLT for a shared object.
1008
1009 const unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
1010 {
1011 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
1012 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx)
1013 0, 0, 0, 0 // unused
1014 };
1015
1016 // Subsequent entries in the PLT for an executable.
1017
1018 const unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
1019 {
1020 0xff, 0x25, // jmp indirect
1021 0, 0, 0, 0, // replaced with address of symbol in .got
1022 0x68, // pushl immediate
1023 0, 0, 0, 0, // replaced with offset into relocation table
1024 0xe9, // jmp relative
1025 0, 0, 0, 0 // replaced with offset to start of .plt
1026 };
1027
1028 // Subsequent entries in the PLT for a shared object.
1029
1030 const unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
1031 {
1032 0xff, 0xa3, // jmp *offset(%ebx)
1033 0, 0, 0, 0, // replaced with offset of symbol in .got
1034 0x68, // pushl immediate
1035 0, 0, 0, 0, // replaced with offset into relocation table
1036 0xe9, // jmp relative
1037 0, 0, 0, 0 // replaced with offset to start of .plt
1038 };
1039
1040 // The .eh_frame unwind information for the PLT.
1041
1042 const unsigned char
1043 Output_data_plt_i386::plt_eh_frame_cie[plt_eh_frame_cie_size] =
1044 {
1045 1, // CIE version.
1046 'z', // Augmentation: augmentation size included.
1047 'R', // Augmentation: FDE encoding included.
1048 '\0', // End of augmentation string.
1049 1, // Code alignment factor.
1050 0x7c, // Data alignment factor.
1051 8, // Return address column.
1052 1, // Augmentation size.
1053 (elfcpp::DW_EH_PE_pcrel // FDE encoding.
1054 | elfcpp::DW_EH_PE_sdata4),
1055 elfcpp::DW_CFA_def_cfa, 4, 4, // DW_CFA_def_cfa: r4 (esp) ofs 4.
1056 elfcpp::DW_CFA_offset + 8, 1, // DW_CFA_offset: r8 (eip) at cfa-4.
1057 elfcpp::DW_CFA_nop, // Align to 16 bytes.
1058 elfcpp::DW_CFA_nop
1059 };
1060
1061 const unsigned char
1062 Output_data_plt_i386::plt_eh_frame_fde[plt_eh_frame_fde_size] =
1063 {
1064 0, 0, 0, 0, // Replaced with offset to .plt.
1065 0, 0, 0, 0, // Replaced with size of .plt.
1066 0, // Augmentation size.
1067 elfcpp::DW_CFA_def_cfa_offset, 8, // DW_CFA_def_cfa_offset: 8.
1068 elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
1069 elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
1070 elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16.
1071 elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
1072 11, // Block length.
1073 elfcpp::DW_OP_breg4, 4, // Push %esp + 4.
1074 elfcpp::DW_OP_breg8, 0, // Push %eip.
1075 elfcpp::DW_OP_lit15, // Push 0xf.
1076 elfcpp::DW_OP_and, // & (%eip & 0xf).
1077 elfcpp::DW_OP_lit11, // Push 0xb.
1078 elfcpp::DW_OP_ge, // >= ((%eip & 0xf) >= 0xb)
1079 elfcpp::DW_OP_lit2, // Push 2.
1080 elfcpp::DW_OP_shl, // << (((%eip & 0xf) >= 0xb) << 2)
1081 elfcpp::DW_OP_plus, // + ((((%eip&0xf)>=0xb)<<2)+%esp+4
1082 elfcpp::DW_CFA_nop, // Align to 32 bytes.
1083 elfcpp::DW_CFA_nop,
1084 elfcpp::DW_CFA_nop,
1085 elfcpp::DW_CFA_nop
1086 };
1087
1088 // Write out the PLT. This uses the hand-coded instructions above,
1089 // and adjusts them as needed. This is all specified by the i386 ELF
1090 // Processor Supplement.
1091
1092 void
1093 Output_data_plt_i386::do_write(Output_file* of)
1094 {
1095 const off_t offset = this->offset();
1096 const section_size_type oview_size =
1097 convert_to_section_size_type(this->data_size());
1098 unsigned char* const oview = of->get_output_view(offset, oview_size);
1099
1100 const off_t got_file_offset = this->got_plt_->offset();
1101 gold_assert(parameters->incremental_update()
1102 || (got_file_offset + this->got_plt_->data_size()
1103 == this->got_irelative_->offset()));
1104 const section_size_type got_size =
1105 convert_to_section_size_type(this->got_plt_->data_size()
1106 + this->got_irelative_->data_size());
1107 unsigned char* const got_view = of->get_output_view(got_file_offset,
1108 got_size);
1109
1110 unsigned char* pov = oview;
1111
1112 elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
1113 elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
1114
1115 if (parameters->options().output_is_position_independent())
1116 memcpy(pov, dyn_first_plt_entry, plt_entry_size);
1117 else
1118 {
1119 memcpy(pov, exec_first_plt_entry, plt_entry_size);
1120 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
1121 elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
1122 }
1123 pov += plt_entry_size;
1124
1125 unsigned char* got_pov = got_view;
1126
1127 memset(got_pov, 0, 12);
1128 got_pov += 12;
1129
1130 const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
1131
1132 unsigned int plt_offset = plt_entry_size;
1133 unsigned int plt_rel_offset = 0;
1134 unsigned int got_offset = 12;
1135 const unsigned int count = this->count_ + this->irelative_count_;
1136 for (unsigned int i = 0;
1137 i < count;
1138 ++i,
1139 pov += plt_entry_size,
1140 got_pov += 4,
1141 plt_offset += plt_entry_size,
1142 plt_rel_offset += rel_size,
1143 got_offset += 4)
1144 {
1145 // Set and adjust the PLT entry itself.
1146
1147 if (parameters->options().output_is_position_independent())
1148 {
1149 memcpy(pov, dyn_plt_entry, plt_entry_size);
1150 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
1151 }
1152 else
1153 {
1154 memcpy(pov, exec_plt_entry, plt_entry_size);
1155 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
1156 (got_address
1157 + got_offset));
1158 }
1159
1160 elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
1161 elfcpp::Swap<32, false>::writeval(pov + 12,
1162 - (plt_offset + plt_entry_size));
1163
1164 // Set the entry in the GOT.
1165 elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
1166 }
1167
1168 // If any STT_GNU_IFUNC symbols have PLT entries, we need to change
1169 // the GOT to point to the actual symbol value, rather than point to
1170 // the PLT entry. That will let the dynamic linker call the right
1171 // function when resolving IRELATIVE relocations.
1172 unsigned char* got_irelative_view = got_view + this->got_plt_->data_size();
1173 for (std::vector<Global_ifunc>::const_iterator p =
1174 this->global_ifuncs_.begin();
1175 p != this->global_ifuncs_.end();
1176 ++p)
1177 {
1178 const Sized_symbol<32>* ssym =
1179 static_cast<const Sized_symbol<32>*>(p->sym);
1180 elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
1181 ssym->value());
1182 }
1183
1184 for (std::vector<Local_ifunc>::const_iterator p =
1185 this->local_ifuncs_.begin();
1186 p != this->local_ifuncs_.end();
1187 ++p)
1188 {
1189 const Symbol_value<32>* psymval =
1190 p->object->local_symbol(p->local_sym_index);
1191 elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
1192 psymval->value(p->object, 0));
1193 }
1194
1195 gold_assert(static_cast<section_size_type>(pov - oview) == oview_size);
1196 gold_assert(static_cast<section_size_type>(got_pov - got_view) == got_size);
1197
1198 of->write_output_view(offset, oview_size, oview);
1199 of->write_output_view(got_file_offset, got_size, got_view);
1200 }
1201
1202 // Create the PLT section.
1203
1204 void
1205 Target_i386::make_plt_section(Symbol_table* symtab, Layout* layout)
1206 {
1207 if (this->plt_ == NULL)
1208 {
1209 // Create the GOT sections first.
1210 this->got_section(symtab, layout);
1211
1212 this->plt_ = new Output_data_plt_i386(layout, this->got_plt_,
1213 this->got_irelative_);
1214 layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
1215 (elfcpp::SHF_ALLOC
1216 | elfcpp::SHF_EXECINSTR),
1217 this->plt_, ORDER_PLT, false);
1218
1219 // Make the sh_info field of .rel.plt point to .plt.
1220 Output_section* rel_plt_os = this->plt_->rel_plt()->output_section();
1221 rel_plt_os->set_info_section(this->plt_->output_section());
1222 }
1223 }
1224
1225 // Create a PLT entry for a global symbol.
1226
1227 void
1228 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
1229 {
1230 if (gsym->has_plt_offset())
1231 return;
1232 if (this->plt_ == NULL)
1233 this->make_plt_section(symtab, layout);
1234 this->plt_->add_entry(symtab, layout, gsym);
1235 }
1236
1237 // Make a PLT entry for a local STT_GNU_IFUNC symbol.
1238
1239 void
1240 Target_i386::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout,
1241 Sized_relobj_file<32, false>* relobj,
1242 unsigned int local_sym_index)
1243 {
1244 if (relobj->local_has_plt_offset(local_sym_index))
1245 return;
1246 if (this->plt_ == NULL)
1247 this->make_plt_section(symtab, layout);
1248 unsigned int plt_offset = this->plt_->add_local_ifunc_entry(symtab, layout,
1249 relobj,
1250 local_sym_index);
1251 relobj->set_local_plt_offset(local_sym_index, plt_offset);
1252 }
1253
1254 // Return the number of entries in the PLT.
1255
1256 unsigned int
1257 Target_i386::plt_entry_count() const
1258 {
1259 if (this->plt_ == NULL)
1260 return 0;
1261 return this->plt_->entry_count();
1262 }
1263
1264 // Return the offset of the first non-reserved PLT entry.
1265
1266 unsigned int
1267 Target_i386::first_plt_entry_offset() const
1268 {
1269 return Output_data_plt_i386::first_plt_entry_offset();
1270 }
1271
1272 // Return the size of each PLT entry.
1273
1274 unsigned int
1275 Target_i386::plt_entry_size() const
1276 {
1277 return Output_data_plt_i386::get_plt_entry_size();
1278 }
1279
1280 // Get the section to use for TLS_DESC relocations.
1281
1282 Target_i386::Reloc_section*
1283 Target_i386::rel_tls_desc_section(Layout* layout) const
1284 {
1285 return this->plt_section()->rel_tls_desc(layout);
1286 }
1287
1288 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
1289
1290 void
1291 Target_i386::define_tls_base_symbol(Symbol_table* symtab, Layout* layout)
1292 {
1293 if (this->tls_base_symbol_defined_)
1294 return;
1295
1296 Output_segment* tls_segment = layout->tls_segment();
1297 if (tls_segment != NULL)
1298 {
1299 bool is_exec = parameters->options().output_is_executable();
1300 symtab->define_in_output_segment("_TLS_MODULE_BASE_", NULL,
1301 Symbol_table::PREDEFINED,
1302 tls_segment, 0, 0,
1303 elfcpp::STT_TLS,
1304 elfcpp::STB_LOCAL,
1305 elfcpp::STV_HIDDEN, 0,
1306 (is_exec
1307 ? Symbol::SEGMENT_END
1308 : Symbol::SEGMENT_START),
1309 true);
1310 }
1311 this->tls_base_symbol_defined_ = true;
1312 }
1313
1314 // Create a GOT entry for the TLS module index.
1315
1316 unsigned int
1317 Target_i386::got_mod_index_entry(Symbol_table* symtab, Layout* layout,
1318 Sized_relobj_file<32, false>* object)
1319 {
1320 if (this->got_mod_index_offset_ == -1U)
1321 {
1322 gold_assert(symtab != NULL && layout != NULL && object != NULL);
1323 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1324 Output_data_got<32, false>* got = this->got_section(symtab, layout);
1325 unsigned int got_offset = got->add_constant(0);
1326 rel_dyn->add_local(object, 0, elfcpp::R_386_TLS_DTPMOD32, got,
1327 got_offset);
1328 got->add_constant(0);
1329 this->got_mod_index_offset_ = got_offset;
1330 }
1331 return this->got_mod_index_offset_;
1332 }
1333
1334 // Optimize the TLS relocation type based on what we know about the
1335 // symbol. IS_FINAL is true if the final address of this symbol is
1336 // known at link time.
1337
1338 tls::Tls_optimization
1339 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
1340 {
1341 // If we are generating a shared library, then we can't do anything
1342 // in the linker.
1343 if (parameters->options().shared())
1344 return tls::TLSOPT_NONE;
1345
1346 switch (r_type)
1347 {
1348 case elfcpp::R_386_TLS_GD:
1349 case elfcpp::R_386_TLS_GOTDESC:
1350 case elfcpp::R_386_TLS_DESC_CALL:
1351 // These are General-Dynamic which permits fully general TLS
1352 // access. Since we know that we are generating an executable,
1353 // we can convert this to Initial-Exec. If we also know that
1354 // this is a local symbol, we can further switch to Local-Exec.
1355 if (is_final)
1356 return tls::TLSOPT_TO_LE;
1357 return tls::TLSOPT_TO_IE;
1358
1359 case elfcpp::R_386_TLS_LDM:
1360 // This is Local-Dynamic, which refers to a local symbol in the
1361 // dynamic TLS block. Since we know that we generating an
1362 // executable, we can switch to Local-Exec.
1363 return tls::TLSOPT_TO_LE;
1364
1365 case elfcpp::R_386_TLS_LDO_32:
1366 // Another type of Local-Dynamic relocation.
1367 return tls::TLSOPT_TO_LE;
1368
1369 case elfcpp::R_386_TLS_IE:
1370 case elfcpp::R_386_TLS_GOTIE:
1371 case elfcpp::R_386_TLS_IE_32:
1372 // These are Initial-Exec relocs which get the thread offset
1373 // from the GOT. If we know that we are linking against the
1374 // local symbol, we can switch to Local-Exec, which links the
1375 // thread offset into the instruction.
1376 if (is_final)
1377 return tls::TLSOPT_TO_LE;
1378 return tls::TLSOPT_NONE;
1379
1380 case elfcpp::R_386_TLS_LE:
1381 case elfcpp::R_386_TLS_LE_32:
1382 // When we already have Local-Exec, there is nothing further we
1383 // can do.
1384 return tls::TLSOPT_NONE;
1385
1386 default:
1387 gold_unreachable();
1388 }
1389 }
1390
1391 // Get the Reference_flags for a particular relocation.
1392
1393 int
1394 Target_i386::Scan::get_reference_flags(unsigned int r_type)
1395 {
1396 switch (r_type)
1397 {
1398 case elfcpp::R_386_NONE:
1399 case elfcpp::R_386_GNU_VTINHERIT:
1400 case elfcpp::R_386_GNU_VTENTRY:
1401 case elfcpp::R_386_GOTPC:
1402 // No symbol reference.
1403 return 0;
1404
1405 case elfcpp::R_386_32:
1406 case elfcpp::R_386_16:
1407 case elfcpp::R_386_8:
1408 return Symbol::ABSOLUTE_REF;
1409
1410 case elfcpp::R_386_PC32:
1411 case elfcpp::R_386_PC16:
1412 case elfcpp::R_386_PC8:
1413 case elfcpp::R_386_GOTOFF:
1414 return Symbol::RELATIVE_REF;
1415
1416 case elfcpp::R_386_PLT32:
1417 return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF;
1418
1419 case elfcpp::R_386_GOT32:
1420 // Absolute in GOT.
1421 return Symbol::ABSOLUTE_REF;
1422
1423 case elfcpp::R_386_TLS_GD: // Global-dynamic
1424 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1425 case elfcpp::R_386_TLS_DESC_CALL:
1426 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1427 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1428 case elfcpp::R_386_TLS_IE: // Initial-exec
1429 case elfcpp::R_386_TLS_IE_32:
1430 case elfcpp::R_386_TLS_GOTIE:
1431 case elfcpp::R_386_TLS_LE: // Local-exec
1432 case elfcpp::R_386_TLS_LE_32:
1433 return Symbol::TLS_REF;
1434
1435 case elfcpp::R_386_COPY:
1436 case elfcpp::R_386_GLOB_DAT:
1437 case elfcpp::R_386_JUMP_SLOT:
1438 case elfcpp::R_386_RELATIVE:
1439 case elfcpp::R_386_IRELATIVE:
1440 case elfcpp::R_386_TLS_TPOFF:
1441 case elfcpp::R_386_TLS_DTPMOD32:
1442 case elfcpp::R_386_TLS_DTPOFF32:
1443 case elfcpp::R_386_TLS_TPOFF32:
1444 case elfcpp::R_386_TLS_DESC:
1445 case elfcpp::R_386_32PLT:
1446 case elfcpp::R_386_TLS_GD_32:
1447 case elfcpp::R_386_TLS_GD_PUSH:
1448 case elfcpp::R_386_TLS_GD_CALL:
1449 case elfcpp::R_386_TLS_GD_POP:
1450 case elfcpp::R_386_TLS_LDM_32:
1451 case elfcpp::R_386_TLS_LDM_PUSH:
1452 case elfcpp::R_386_TLS_LDM_CALL:
1453 case elfcpp::R_386_TLS_LDM_POP:
1454 case elfcpp::R_386_USED_BY_INTEL_200:
1455 default:
1456 // Not expected. We will give an error later.
1457 return 0;
1458 }
1459 }
1460
1461 // Report an unsupported relocation against a local symbol.
1462
1463 void
1464 Target_i386::Scan::unsupported_reloc_local(Sized_relobj_file<32, false>* object,
1465 unsigned int r_type)
1466 {
1467 gold_error(_("%s: unsupported reloc %u against local symbol"),
1468 object->name().c_str(), r_type);
1469 }
1470
1471 // Return whether we need to make a PLT entry for a relocation of a
1472 // given type against a STT_GNU_IFUNC symbol.
1473
1474 bool
1475 Target_i386::Scan::reloc_needs_plt_for_ifunc(
1476 Sized_relobj_file<32, false>* object,
1477 unsigned int r_type)
1478 {
1479 int flags = Scan::get_reference_flags(r_type);
1480 if (flags & Symbol::TLS_REF)
1481 gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"),
1482 object->name().c_str(), r_type);
1483 return flags != 0;
1484 }
1485
1486 // Scan a relocation for a local symbol.
1487
1488 inline void
1489 Target_i386::Scan::local(Symbol_table* symtab,
1490 Layout* layout,
1491 Target_i386* target,
1492 Sized_relobj_file<32, false>* object,
1493 unsigned int data_shndx,
1494 Output_section* output_section,
1495 const elfcpp::Rel<32, false>& reloc,
1496 unsigned int r_type,
1497 const elfcpp::Sym<32, false>& lsym)
1498 {
1499 // A local STT_GNU_IFUNC symbol may require a PLT entry.
1500 if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC
1501 && this->reloc_needs_plt_for_ifunc(object, r_type))
1502 {
1503 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1504 target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym);
1505 }
1506
1507 switch (r_type)
1508 {
1509 case elfcpp::R_386_NONE:
1510 case elfcpp::R_386_GNU_VTINHERIT:
1511 case elfcpp::R_386_GNU_VTENTRY:
1512 break;
1513
1514 case elfcpp::R_386_32:
1515 // If building a shared library (or a position-independent
1516 // executable), we need to create a dynamic relocation for
1517 // this location. The relocation applied at link time will
1518 // apply the link-time value, so we flag the location with
1519 // an R_386_RELATIVE relocation so the dynamic loader can
1520 // relocate it easily.
1521 if (parameters->options().output_is_position_independent())
1522 {
1523 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1524 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1525 rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE,
1526 output_section, data_shndx,
1527 reloc.get_r_offset());
1528 }
1529 break;
1530
1531 case elfcpp::R_386_16:
1532 case elfcpp::R_386_8:
1533 // If building a shared library (or a position-independent
1534 // executable), we need to create a dynamic relocation for
1535 // this location. Because the addend needs to remain in the
1536 // data section, we need to be careful not to apply this
1537 // relocation statically.
1538 if (parameters->options().output_is_position_independent())
1539 {
1540 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1541 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1542 if (lsym.get_st_type() != elfcpp::STT_SECTION)
1543 rel_dyn->add_local(object, r_sym, r_type, output_section,
1544 data_shndx, reloc.get_r_offset());
1545 else
1546 {
1547 gold_assert(lsym.get_st_value() == 0);
1548 unsigned int shndx = lsym.get_st_shndx();
1549 bool is_ordinary;
1550 shndx = object->adjust_sym_shndx(r_sym, shndx,
1551 &is_ordinary);
1552 if (!is_ordinary)
1553 object->error(_("section symbol %u has bad shndx %u"),
1554 r_sym, shndx);
1555 else
1556 rel_dyn->add_local_section(object, shndx,
1557 r_type, output_section,
1558 data_shndx, reloc.get_r_offset());
1559 }
1560 }
1561 break;
1562
1563 case elfcpp::R_386_PC32:
1564 case elfcpp::R_386_PC16:
1565 case elfcpp::R_386_PC8:
1566 break;
1567
1568 case elfcpp::R_386_PLT32:
1569 // Since we know this is a local symbol, we can handle this as a
1570 // PC32 reloc.
1571 break;
1572
1573 case elfcpp::R_386_GOTOFF:
1574 case elfcpp::R_386_GOTPC:
1575 // We need a GOT section.
1576 target->got_section(symtab, layout);
1577 break;
1578
1579 case elfcpp::R_386_GOT32:
1580 {
1581 // The symbol requires a GOT entry.
1582 Output_data_got<32, false>* got = target->got_section(symtab, layout);
1583 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1584
1585 // For a STT_GNU_IFUNC symbol we want the PLT offset. That
1586 // lets function pointers compare correctly with shared
1587 // libraries. Otherwise we would need an IRELATIVE reloc.
1588 bool is_new;
1589 if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC)
1590 is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD);
1591 else
1592 is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD);
1593 if (is_new)
1594 {
1595 // If we are generating a shared object, we need to add a
1596 // dynamic RELATIVE relocation for this symbol's GOT entry.
1597 if (parameters->options().output_is_position_independent())
1598 {
1599 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1600 unsigned int got_offset =
1601 object->local_got_offset(r_sym, GOT_TYPE_STANDARD);
1602 rel_dyn->add_local_relative(object, r_sym,
1603 elfcpp::R_386_RELATIVE,
1604 got, got_offset);
1605 }
1606 }
1607 }
1608 break;
1609
1610 // These are relocations which should only be seen by the
1611 // dynamic linker, and should never be seen here.
1612 case elfcpp::R_386_COPY:
1613 case elfcpp::R_386_GLOB_DAT:
1614 case elfcpp::R_386_JUMP_SLOT:
1615 case elfcpp::R_386_RELATIVE:
1616 case elfcpp::R_386_IRELATIVE:
1617 case elfcpp::R_386_TLS_TPOFF:
1618 case elfcpp::R_386_TLS_DTPMOD32:
1619 case elfcpp::R_386_TLS_DTPOFF32:
1620 case elfcpp::R_386_TLS_TPOFF32:
1621 case elfcpp::R_386_TLS_DESC:
1622 gold_error(_("%s: unexpected reloc %u in object file"),
1623 object->name().c_str(), r_type);
1624 break;
1625
1626 // These are initial TLS relocs, which are expected when
1627 // linking.
1628 case elfcpp::R_386_TLS_GD: // Global-dynamic
1629 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1630 case elfcpp::R_386_TLS_DESC_CALL:
1631 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1632 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1633 case elfcpp::R_386_TLS_IE: // Initial-exec
1634 case elfcpp::R_386_TLS_IE_32:
1635 case elfcpp::R_386_TLS_GOTIE:
1636 case elfcpp::R_386_TLS_LE: // Local-exec
1637 case elfcpp::R_386_TLS_LE_32:
1638 {
1639 bool output_is_shared = parameters->options().shared();
1640 const tls::Tls_optimization optimized_type
1641 = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
1642 switch (r_type)
1643 {
1644 case elfcpp::R_386_TLS_GD: // Global-dynamic
1645 if (optimized_type == tls::TLSOPT_NONE)
1646 {
1647 // Create a pair of GOT entries for the module index and
1648 // dtv-relative offset.
1649 Output_data_got<32, false>* got
1650 = target->got_section(symtab, layout);
1651 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1652 unsigned int shndx = lsym.get_st_shndx();
1653 bool is_ordinary;
1654 shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
1655 if (!is_ordinary)
1656 object->error(_("local symbol %u has bad shndx %u"),
1657 r_sym, shndx);
1658 else
1659 got->add_local_pair_with_rel(object, r_sym, shndx,
1660 GOT_TYPE_TLS_PAIR,
1661 target->rel_dyn_section(layout),
1662 elfcpp::R_386_TLS_DTPMOD32, 0);
1663 }
1664 else if (optimized_type != tls::TLSOPT_TO_LE)
1665 unsupported_reloc_local(object, r_type);
1666 break;
1667
1668 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva)
1669 target->define_tls_base_symbol(symtab, layout);
1670 if (optimized_type == tls::TLSOPT_NONE)
1671 {
1672 // Create a double GOT entry with an R_386_TLS_DESC
1673 // reloc. The R_386_TLS_DESC reloc is resolved
1674 // lazily, so the GOT entry needs to be in an area in
1675 // .got.plt, not .got. Call got_section to make sure
1676 // the section has been created.
1677 target->got_section(symtab, layout);
1678 Output_data_got<32, false>* got = target->got_tlsdesc_section();
1679 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1680 if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC))
1681 {
1682 unsigned int got_offset = got->add_constant(0);
1683 // The local symbol value is stored in the second
1684 // GOT entry.
1685 got->add_local(object, r_sym, GOT_TYPE_TLS_DESC);
1686 // That set the GOT offset of the local symbol to
1687 // point to the second entry, but we want it to
1688 // point to the first.
1689 object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC,
1690 got_offset);
1691 Reloc_section* rt = target->rel_tls_desc_section(layout);
1692 rt->add_absolute(elfcpp::R_386_TLS_DESC, got, got_offset);
1693 }
1694 }
1695 else if (optimized_type != tls::TLSOPT_TO_LE)
1696 unsupported_reloc_local(object, r_type);
1697 break;
1698
1699 case elfcpp::R_386_TLS_DESC_CALL:
1700 break;
1701
1702 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1703 if (optimized_type == tls::TLSOPT_NONE)
1704 {
1705 // Create a GOT entry for the module index.
1706 target->got_mod_index_entry(symtab, layout, object);
1707 }
1708 else if (optimized_type != tls::TLSOPT_TO_LE)
1709 unsupported_reloc_local(object, r_type);
1710 break;
1711
1712 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1713 break;
1714
1715 case elfcpp::R_386_TLS_IE: // Initial-exec
1716 case elfcpp::R_386_TLS_IE_32:
1717 case elfcpp::R_386_TLS_GOTIE:
1718 layout->set_has_static_tls();
1719 if (optimized_type == tls::TLSOPT_NONE)
1720 {
1721 // For the R_386_TLS_IE relocation, we need to create a
1722 // dynamic relocation when building a shared library.
1723 if (r_type == elfcpp::R_386_TLS_IE
1724 && parameters->options().shared())
1725 {
1726 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1727 unsigned int r_sym
1728 = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1729 rel_dyn->add_local_relative(object, r_sym,
1730 elfcpp::R_386_RELATIVE,
1731 output_section, data_shndx,
1732 reloc.get_r_offset());
1733 }
1734 // Create a GOT entry for the tp-relative offset.
1735 Output_data_got<32, false>* got
1736 = target->got_section(symtab, layout);
1737 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1738 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
1739 ? elfcpp::R_386_TLS_TPOFF32
1740 : elfcpp::R_386_TLS_TPOFF);
1741 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
1742 ? GOT_TYPE_TLS_OFFSET
1743 : GOT_TYPE_TLS_NOFFSET);
1744 got->add_local_with_rel(object, r_sym, got_type,
1745 target->rel_dyn_section(layout),
1746 dyn_r_type);
1747 }
1748 else if (optimized_type != tls::TLSOPT_TO_LE)
1749 unsupported_reloc_local(object, r_type);
1750 break;
1751
1752 case elfcpp::R_386_TLS_LE: // Local-exec
1753 case elfcpp::R_386_TLS_LE_32:
1754 layout->set_has_static_tls();
1755 if (output_is_shared)
1756 {
1757 // We need to create a dynamic relocation.
1758 gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION);
1759 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1760 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
1761 ? elfcpp::R_386_TLS_TPOFF32
1762 : elfcpp::R_386_TLS_TPOFF);
1763 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1764 rel_dyn->add_local(object, r_sym, dyn_r_type, output_section,
1765 data_shndx, reloc.get_r_offset());
1766 }
1767 break;
1768
1769 default:
1770 gold_unreachable();
1771 }
1772 }
1773 break;
1774
1775 case elfcpp::R_386_32PLT:
1776 case elfcpp::R_386_TLS_GD_32:
1777 case elfcpp::R_386_TLS_GD_PUSH:
1778 case elfcpp::R_386_TLS_GD_CALL:
1779 case elfcpp::R_386_TLS_GD_POP:
1780 case elfcpp::R_386_TLS_LDM_32:
1781 case elfcpp::R_386_TLS_LDM_PUSH:
1782 case elfcpp::R_386_TLS_LDM_CALL:
1783 case elfcpp::R_386_TLS_LDM_POP:
1784 case elfcpp::R_386_USED_BY_INTEL_200:
1785 default:
1786 unsupported_reloc_local(object, r_type);
1787 break;
1788 }
1789 }
1790
1791 // Report an unsupported relocation against a global symbol.
1792
1793 void
1794 Target_i386::Scan::unsupported_reloc_global(
1795 Sized_relobj_file<32, false>* object,
1796 unsigned int r_type,
1797 Symbol* gsym)
1798 {
1799 gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1800 object->name().c_str(), r_type, gsym->demangled_name().c_str());
1801 }
1802
1803 inline bool
1804 Target_i386::Scan::possible_function_pointer_reloc(unsigned int r_type)
1805 {
1806 switch (r_type)
1807 {
1808 case elfcpp::R_386_32:
1809 case elfcpp::R_386_16:
1810 case elfcpp::R_386_8:
1811 case elfcpp::R_386_GOTOFF:
1812 case elfcpp::R_386_GOT32:
1813 {
1814 return true;
1815 }
1816 default:
1817 return false;
1818 }
1819 return false;
1820 }
1821
1822 inline bool
1823 Target_i386::Scan::local_reloc_may_be_function_pointer(
1824 Symbol_table* ,
1825 Layout* ,
1826 Target_i386* ,
1827 Sized_relobj_file<32, false>* ,
1828 unsigned int ,
1829 Output_section* ,
1830 const elfcpp::Rel<32, false>& ,
1831 unsigned int r_type,
1832 const elfcpp::Sym<32, false>&)
1833 {
1834 return possible_function_pointer_reloc(r_type);
1835 }
1836
1837 inline bool
1838 Target_i386::Scan::global_reloc_may_be_function_pointer(
1839 Symbol_table* ,
1840 Layout* ,
1841 Target_i386* ,
1842 Sized_relobj_file<32, false>* ,
1843 unsigned int ,
1844 Output_section* ,
1845 const elfcpp::Rel<32, false>& ,
1846 unsigned int r_type,
1847 Symbol*)
1848 {
1849 return possible_function_pointer_reloc(r_type);
1850 }
1851
1852 // Scan a relocation for a global symbol.
1853
1854 inline void
1855 Target_i386::Scan::global(Symbol_table* symtab,
1856 Layout* layout,
1857 Target_i386* target,
1858 Sized_relobj_file<32, false>* object,
1859 unsigned int data_shndx,
1860 Output_section* output_section,
1861 const elfcpp::Rel<32, false>& reloc,
1862 unsigned int r_type,
1863 Symbol* gsym)
1864 {
1865 // A STT_GNU_IFUNC symbol may require a PLT entry.
1866 if (gsym->type() == elfcpp::STT_GNU_IFUNC
1867 && this->reloc_needs_plt_for_ifunc(object, r_type))
1868 target->make_plt_entry(symtab, layout, gsym);
1869
1870 switch (r_type)
1871 {
1872 case elfcpp::R_386_NONE:
1873 case elfcpp::R_386_GNU_VTINHERIT:
1874 case elfcpp::R_386_GNU_VTENTRY:
1875 break;
1876
1877 case elfcpp::R_386_32:
1878 case elfcpp::R_386_16:
1879 case elfcpp::R_386_8:
1880 {
1881 // Make a PLT entry if necessary.
1882 if (gsym->needs_plt_entry())
1883 {
1884 target->make_plt_entry(symtab, layout, gsym);
1885 // Since this is not a PC-relative relocation, we may be
1886 // taking the address of a function. In that case we need to
1887 // set the entry in the dynamic symbol table to the address of
1888 // the PLT entry.
1889 if (gsym->is_from_dynobj() && !parameters->options().shared())
1890 gsym->set_needs_dynsym_value();
1891 }
1892 // Make a dynamic relocation if necessary.
1893 if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
1894 {
1895 if (gsym->may_need_copy_reloc())
1896 {
1897 target->copy_reloc(symtab, layout, object,
1898 data_shndx, output_section, gsym, reloc);
1899 }
1900 else if (r_type == elfcpp::R_386_32
1901 && gsym->type() == elfcpp::STT_GNU_IFUNC
1902 && gsym->can_use_relative_reloc(false)
1903 && !gsym->is_from_dynobj()
1904 && !gsym->is_undefined()
1905 && !gsym->is_preemptible())
1906 {
1907 // Use an IRELATIVE reloc for a locally defined
1908 // STT_GNU_IFUNC symbol. This makes a function
1909 // address in a PIE executable match the address in a
1910 // shared library that it links against.
1911 Reloc_section* rel_dyn = target->rel_irelative_section(layout);
1912 rel_dyn->add_symbolless_global_addend(gsym,
1913 elfcpp::R_386_IRELATIVE,
1914 output_section,
1915 object, data_shndx,
1916 reloc.get_r_offset());
1917 }
1918 else if (r_type == elfcpp::R_386_32
1919 && gsym->can_use_relative_reloc(false))
1920 {
1921 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1922 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
1923 output_section, object,
1924 data_shndx, reloc.get_r_offset());
1925 }
1926 else
1927 {
1928 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1929 rel_dyn->add_global(gsym, r_type, output_section, object,
1930 data_shndx, reloc.get_r_offset());
1931 }
1932 }
1933 }
1934 break;
1935
1936 case elfcpp::R_386_PC32:
1937 case elfcpp::R_386_PC16:
1938 case elfcpp::R_386_PC8:
1939 {
1940 // Make a PLT entry if necessary.
1941 if (gsym->needs_plt_entry())
1942 {
1943 // These relocations are used for function calls only in
1944 // non-PIC code. For a 32-bit relocation in a shared library,
1945 // we'll need a text relocation anyway, so we can skip the
1946 // PLT entry and let the dynamic linker bind the call directly
1947 // to the target. For smaller relocations, we should use a
1948 // PLT entry to ensure that the call can reach.
1949 if (!parameters->options().shared()
1950 || r_type != elfcpp::R_386_PC32)
1951 target->make_plt_entry(symtab, layout, gsym);
1952 }
1953 // Make a dynamic relocation if necessary.
1954 if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
1955 {
1956 if (gsym->may_need_copy_reloc())
1957 {
1958 target->copy_reloc(symtab, layout, object,
1959 data_shndx, output_section, gsym, reloc);
1960 }
1961 else
1962 {
1963 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1964 rel_dyn->add_global(gsym, r_type, output_section, object,
1965 data_shndx, reloc.get_r_offset());
1966 }
1967 }
1968 }
1969 break;
1970
1971 case elfcpp::R_386_GOT32:
1972 {
1973 // The symbol requires a GOT entry.
1974 Output_data_got<32, false>* got = target->got_section(symtab, layout);
1975 if (gsym->final_value_is_known())
1976 {
1977 // For a STT_GNU_IFUNC symbol we want the PLT address.
1978 if (gsym->type() == elfcpp::STT_GNU_IFUNC)
1979 got->add_global_plt(gsym, GOT_TYPE_STANDARD);
1980 else
1981 got->add_global(gsym, GOT_TYPE_STANDARD);
1982 }
1983 else
1984 {
1985 // If this symbol is not fully resolved, we need to add a
1986 // GOT entry with a dynamic relocation.
1987 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1988
1989 // Use a GLOB_DAT rather than a RELATIVE reloc if:
1990 //
1991 // 1) The symbol may be defined in some other module.
1992 //
1993 // 2) We are building a shared library and this is a
1994 // protected symbol; using GLOB_DAT means that the dynamic
1995 // linker can use the address of the PLT in the main
1996 // executable when appropriate so that function address
1997 // comparisons work.
1998 //
1999 // 3) This is a STT_GNU_IFUNC symbol in position dependent
2000 // code, again so that function address comparisons work.
2001 if (gsym->is_from_dynobj()
2002 || gsym->is_undefined()
2003 || gsym->is_preemptible()
2004 || (gsym->visibility() == elfcpp::STV_PROTECTED
2005 && parameters->options().shared())
2006 || (gsym->type() == elfcpp::STT_GNU_IFUNC
2007 && parameters->options().output_is_position_independent()))
2008 got->add_global_with_rel(gsym, GOT_TYPE_STANDARD,
2009 rel_dyn, elfcpp::R_386_GLOB_DAT);
2010 else
2011 {
2012 // For a STT_GNU_IFUNC symbol we want to write the PLT
2013 // offset into the GOT, so that function pointer
2014 // comparisons work correctly.
2015 bool is_new;
2016 if (gsym->type() != elfcpp::STT_GNU_IFUNC)
2017 is_new = got->add_global(gsym, GOT_TYPE_STANDARD);
2018 else
2019 {
2020 is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD);
2021 // Tell the dynamic linker to use the PLT address
2022 // when resolving relocations.
2023 if (gsym->is_from_dynobj()
2024 && !parameters->options().shared())
2025 gsym->set_needs_dynsym_value();
2026 }
2027 if (is_new)
2028 {
2029 unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD);
2030 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2031 got, got_off);
2032 }
2033 }
2034 }
2035 }
2036 break;
2037
2038 case elfcpp::R_386_PLT32:
2039 // If the symbol is fully resolved, this is just a PC32 reloc.
2040 // Otherwise we need a PLT entry.
2041 if (gsym->final_value_is_known())
2042 break;
2043 // If building a shared library, we can also skip the PLT entry
2044 // if the symbol is defined in the output file and is protected
2045 // or hidden.
2046 if (gsym->is_defined()
2047 && !gsym->is_from_dynobj()
2048 && !gsym->is_preemptible())
2049 break;
2050 target->make_plt_entry(symtab, layout, gsym);
2051 break;
2052
2053 case elfcpp::R_386_GOTOFF:
2054 case elfcpp::R_386_GOTPC:
2055 // We need a GOT section.
2056 target->got_section(symtab, layout);
2057 break;
2058
2059 // These are relocations which should only be seen by the
2060 // dynamic linker, and should never be seen here.
2061 case elfcpp::R_386_COPY:
2062 case elfcpp::R_386_GLOB_DAT:
2063 case elfcpp::R_386_JUMP_SLOT:
2064 case elfcpp::R_386_RELATIVE:
2065 case elfcpp::R_386_IRELATIVE:
2066 case elfcpp::R_386_TLS_TPOFF:
2067 case elfcpp::R_386_TLS_DTPMOD32:
2068 case elfcpp::R_386_TLS_DTPOFF32:
2069 case elfcpp::R_386_TLS_TPOFF32:
2070 case elfcpp::R_386_TLS_DESC:
2071 gold_error(_("%s: unexpected reloc %u in object file"),
2072 object->name().c_str(), r_type);
2073 break;
2074
2075 // These are initial tls relocs, which are expected when
2076 // linking.
2077 case elfcpp::R_386_TLS_GD: // Global-dynamic
2078 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2079 case elfcpp::R_386_TLS_DESC_CALL:
2080 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2081 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2082 case elfcpp::R_386_TLS_IE: // Initial-exec
2083 case elfcpp::R_386_TLS_IE_32:
2084 case elfcpp::R_386_TLS_GOTIE:
2085 case elfcpp::R_386_TLS_LE: // Local-exec
2086 case elfcpp::R_386_TLS_LE_32:
2087 {
2088 const bool is_final = gsym->final_value_is_known();
2089 const tls::Tls_optimization optimized_type
2090 = Target_i386::optimize_tls_reloc(is_final, r_type);
2091 switch (r_type)
2092 {
2093 case elfcpp::R_386_TLS_GD: // Global-dynamic
2094 if (optimized_type == tls::TLSOPT_NONE)
2095 {
2096 // Create a pair of GOT entries for the module index and
2097 // dtv-relative offset.
2098 Output_data_got<32, false>* got
2099 = target->got_section(symtab, layout);
2100 got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR,
2101 target->rel_dyn_section(layout),
2102 elfcpp::R_386_TLS_DTPMOD32,
2103 elfcpp::R_386_TLS_DTPOFF32);
2104 }
2105 else if (optimized_type == tls::TLSOPT_TO_IE)
2106 {
2107 // Create a GOT entry for the tp-relative offset.
2108 Output_data_got<32, false>* got
2109 = target->got_section(symtab, layout);
2110 got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
2111 target->rel_dyn_section(layout),
2112 elfcpp::R_386_TLS_TPOFF);
2113 }
2114 else if (optimized_type != tls::TLSOPT_TO_LE)
2115 unsupported_reloc_global(object, r_type, gsym);
2116 break;
2117
2118 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url)
2119 target->define_tls_base_symbol(symtab, layout);
2120 if (optimized_type == tls::TLSOPT_NONE)
2121 {
2122 // Create a double GOT entry with an R_386_TLS_DESC
2123 // reloc. The R_386_TLS_DESC reloc is resolved
2124 // lazily, so the GOT entry needs to be in an area in
2125 // .got.plt, not .got. Call got_section to make sure
2126 // the section has been created.
2127 target->got_section(symtab, layout);
2128 Output_data_got<32, false>* got = target->got_tlsdesc_section();
2129 Reloc_section* rt = target->rel_tls_desc_section(layout);
2130 got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt,
2131 elfcpp::R_386_TLS_DESC, 0);
2132 }
2133 else if (optimized_type == tls::TLSOPT_TO_IE)
2134 {
2135 // Create a GOT entry for the tp-relative offset.
2136 Output_data_got<32, false>* got
2137 = target->got_section(symtab, layout);
2138 got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
2139 target->rel_dyn_section(layout),
2140 elfcpp::R_386_TLS_TPOFF);
2141 }
2142 else if (optimized_type != tls::TLSOPT_TO_LE)
2143 unsupported_reloc_global(object, r_type, gsym);
2144 break;
2145
2146 case elfcpp::R_386_TLS_DESC_CALL:
2147 break;
2148
2149 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2150 if (optimized_type == tls::TLSOPT_NONE)
2151 {
2152 // Create a GOT entry for the module index.
2153 target->got_mod_index_entry(symtab, layout, object);
2154 }
2155 else if (optimized_type != tls::TLSOPT_TO_LE)
2156 unsupported_reloc_global(object, r_type, gsym);
2157 break;
2158
2159 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2160 break;
2161
2162 case elfcpp::R_386_TLS_IE: // Initial-exec
2163 case elfcpp::R_386_TLS_IE_32:
2164 case elfcpp::R_386_TLS_GOTIE:
2165 layout->set_has_static_tls();
2166 if (optimized_type == tls::TLSOPT_NONE)
2167 {
2168 // For the R_386_TLS_IE relocation, we need to create a
2169 // dynamic relocation when building a shared library.
2170 if (r_type == elfcpp::R_386_TLS_IE
2171 && parameters->options().shared())
2172 {
2173 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2174 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2175 output_section, object,
2176 data_shndx,
2177 reloc.get_r_offset());
2178 }
2179 // Create a GOT entry for the tp-relative offset.
2180 Output_data_got<32, false>* got
2181 = target->got_section(symtab, layout);
2182 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
2183 ? elfcpp::R_386_TLS_TPOFF32
2184 : elfcpp::R_386_TLS_TPOFF);
2185 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
2186 ? GOT_TYPE_TLS_OFFSET
2187 : GOT_TYPE_TLS_NOFFSET);
2188 got->add_global_with_rel(gsym, got_type,
2189 target->rel_dyn_section(layout),
2190 dyn_r_type);
2191 }
2192 else if (optimized_type != tls::TLSOPT_TO_LE)
2193 unsupported_reloc_global(object, r_type, gsym);
2194 break;
2195
2196 case elfcpp::R_386_TLS_LE: // Local-exec
2197 case elfcpp::R_386_TLS_LE_32:
2198 layout->set_has_static_tls();
2199 if (parameters->options().shared())
2200 {
2201 // We need to create a dynamic relocation.
2202 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
2203 ? elfcpp::R_386_TLS_TPOFF32
2204 : elfcpp::R_386_TLS_TPOFF);
2205 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2206 rel_dyn->add_global(gsym, dyn_r_type, output_section, object,
2207 data_shndx, reloc.get_r_offset());
2208 }
2209 break;
2210
2211 default:
2212 gold_unreachable();
2213 }
2214 }
2215 break;
2216
2217 case elfcpp::R_386_32PLT:
2218 case elfcpp::R_386_TLS_GD_32:
2219 case elfcpp::R_386_TLS_GD_PUSH:
2220 case elfcpp::R_386_TLS_GD_CALL:
2221 case elfcpp::R_386_TLS_GD_POP:
2222 case elfcpp::R_386_TLS_LDM_32:
2223 case elfcpp::R_386_TLS_LDM_PUSH:
2224 case elfcpp::R_386_TLS_LDM_CALL:
2225 case elfcpp::R_386_TLS_LDM_POP:
2226 case elfcpp::R_386_USED_BY_INTEL_200:
2227 default:
2228 unsupported_reloc_global(object, r_type, gsym);
2229 break;
2230 }
2231 }
2232
2233 // Process relocations for gc.
2234
2235 void
2236 Target_i386::gc_process_relocs(Symbol_table* symtab,
2237 Layout* layout,
2238 Sized_relobj_file<32, false>* object,
2239 unsigned int data_shndx,
2240 unsigned int,
2241 const unsigned char* prelocs,
2242 size_t reloc_count,
2243 Output_section* output_section,
2244 bool needs_special_offset_handling,
2245 size_t local_symbol_count,
2246 const unsigned char* plocal_symbols)
2247 {
2248 gold::gc_process_relocs<32, false, Target_i386, elfcpp::SHT_REL,
2249 Target_i386::Scan,
2250 Target_i386::Relocatable_size_for_reloc>(
2251 symtab,
2252 layout,
2253 this,
2254 object,
2255 data_shndx,
2256 prelocs,
2257 reloc_count,
2258 output_section,
2259 needs_special_offset_handling,
2260 local_symbol_count,
2261 plocal_symbols);
2262 }
2263
2264 // Scan relocations for a section.
2265
2266 void
2267 Target_i386::scan_relocs(Symbol_table* symtab,
2268 Layout* layout,
2269 Sized_relobj_file<32, false>* object,
2270 unsigned int data_shndx,
2271 unsigned int sh_type,
2272 const unsigned char* prelocs,
2273 size_t reloc_count,
2274 Output_section* output_section,
2275 bool needs_special_offset_handling,
2276 size_t local_symbol_count,
2277 const unsigned char* plocal_symbols)
2278 {
2279 if (sh_type == elfcpp::SHT_RELA)
2280 {
2281 gold_error(_("%s: unsupported RELA reloc section"),
2282 object->name().c_str());
2283 return;
2284 }
2285
2286 gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
2287 Target_i386::Scan>(
2288 symtab,
2289 layout,
2290 this,
2291 object,
2292 data_shndx,
2293 prelocs,
2294 reloc_count,
2295 output_section,
2296 needs_special_offset_handling,
2297 local_symbol_count,
2298 plocal_symbols);
2299 }
2300
2301 // Finalize the sections.
2302
2303 void
2304 Target_i386::do_finalize_sections(
2305 Layout* layout,
2306 const Input_objects*,
2307 Symbol_table* symtab)
2308 {
2309 const Reloc_section* rel_plt = (this->plt_ == NULL
2310 ? NULL
2311 : this->plt_->rel_plt());
2312 layout->add_target_dynamic_tags(true, this->got_plt_, rel_plt,
2313 this->rel_dyn_, true, false);
2314
2315 // Emit any relocs we saved in an attempt to avoid generating COPY
2316 // relocs.
2317 if (this->copy_relocs_.any_saved_relocs())
2318 this->copy_relocs_.emit(this->rel_dyn_section(layout));
2319
2320 // Set the size of the _GLOBAL_OFFSET_TABLE_ symbol to the size of
2321 // the .got.plt section.
2322 Symbol* sym = this->global_offset_table_;
2323 if (sym != NULL)
2324 {
2325 uint32_t data_size = this->got_plt_->current_data_size();
2326 symtab->get_sized_symbol<32>(sym)->set_symsize(data_size);
2327 }
2328
2329 if (parameters->doing_static_link()
2330 && (this->plt_ == NULL || !this->plt_->has_irelative_section()))
2331 {
2332 // If linking statically, make sure that the __rel_iplt symbols
2333 // were defined if necessary, even if we didn't create a PLT.
2334 static const Define_symbol_in_segment syms[] =
2335 {
2336 {
2337 "__rel_iplt_start", // name
2338 elfcpp::PT_LOAD, // segment_type
2339 elfcpp::PF_W, // segment_flags_set
2340 elfcpp::PF(0), // segment_flags_clear
2341 0, // value
2342 0, // size
2343 elfcpp::STT_NOTYPE, // type
2344 elfcpp::STB_GLOBAL, // binding
2345 elfcpp::STV_HIDDEN, // visibility
2346 0, // nonvis
2347 Symbol::SEGMENT_START, // offset_from_base
2348 true // only_if_ref
2349 },
2350 {
2351 "__rel_iplt_end", // name
2352 elfcpp::PT_LOAD, // segment_type
2353 elfcpp::PF_W, // segment_flags_set
2354 elfcpp::PF(0), // segment_flags_clear
2355 0, // value
2356 0, // size
2357 elfcpp::STT_NOTYPE, // type
2358 elfcpp::STB_GLOBAL, // binding
2359 elfcpp::STV_HIDDEN, // visibility
2360 0, // nonvis
2361 Symbol::SEGMENT_START, // offset_from_base
2362 true // only_if_ref
2363 }
2364 };
2365
2366 symtab->define_symbols(layout, 2, syms,
2367 layout->script_options()->saw_sections_clause());
2368 }
2369 }
2370
2371 // Return whether a direct absolute static relocation needs to be applied.
2372 // In cases where Scan::local() or Scan::global() has created
2373 // a dynamic relocation other than R_386_RELATIVE, the addend
2374 // of the relocation is carried in the data, and we must not
2375 // apply the static relocation.
2376
2377 inline bool
2378 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
2379 unsigned int r_type,
2380 bool is_32bit,
2381 Output_section* output_section)
2382 {
2383 // If the output section is not allocated, then we didn't call
2384 // scan_relocs, we didn't create a dynamic reloc, and we must apply
2385 // the reloc here.
2386 if ((output_section->flags() & elfcpp::SHF_ALLOC) == 0)
2387 return true;
2388
2389 int ref_flags = Scan::get_reference_flags(r_type);
2390
2391 // For local symbols, we will have created a non-RELATIVE dynamic
2392 // relocation only if (a) the output is position independent,
2393 // (b) the relocation is absolute (not pc- or segment-relative), and
2394 // (c) the relocation is not 32 bits wide.
2395 if (gsym == NULL)
2396 return !(parameters->options().output_is_position_independent()
2397 && (ref_flags & Symbol::ABSOLUTE_REF)
2398 && !is_32bit);
2399
2400 // For global symbols, we use the same helper routines used in the
2401 // scan pass. If we did not create a dynamic relocation, or if we
2402 // created a RELATIVE dynamic relocation, we should apply the static
2403 // relocation.
2404 bool has_dyn = gsym->needs_dynamic_reloc(ref_flags);
2405 bool is_rel = (ref_flags & Symbol::ABSOLUTE_REF)
2406 && gsym->can_use_relative_reloc(ref_flags
2407 & Symbol::FUNCTION_CALL);
2408 return !has_dyn || is_rel;
2409 }
2410
2411 // Perform a relocation.
2412
2413 inline bool
2414 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
2415 Target_i386* target,
2416 Output_section* output_section,
2417 size_t relnum,
2418 const elfcpp::Rel<32, false>& rel,
2419 unsigned int r_type,
2420 const Sized_symbol<32>* gsym,
2421 const Symbol_value<32>* psymval,
2422 unsigned char* view,
2423 elfcpp::Elf_types<32>::Elf_Addr address,
2424 section_size_type view_size)
2425 {
2426 if (this->skip_call_tls_get_addr_)
2427 {
2428 if ((r_type != elfcpp::R_386_PLT32
2429 && r_type != elfcpp::R_386_PC32)
2430 || gsym == NULL
2431 || strcmp(gsym->name(), "___tls_get_addr") != 0)
2432 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2433 _("missing expected TLS relocation"));
2434 else
2435 {
2436 this->skip_call_tls_get_addr_ = false;
2437 return false;
2438 }
2439 }
2440
2441 const Sized_relobj_file<32, false>* object = relinfo->object;
2442
2443 // Pick the value to use for symbols defined in shared objects.
2444 Symbol_value<32> symval;
2445 if (gsym != NULL
2446 && gsym->type() == elfcpp::STT_GNU_IFUNC
2447 && r_type == elfcpp::R_386_32
2448 && gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type))
2449 && gsym->can_use_relative_reloc(false)
2450 && !gsym->is_from_dynobj()
2451 && !gsym->is_undefined()
2452 && !gsym->is_preemptible())
2453 {
2454 // In this case we are generating a R_386_IRELATIVE reloc. We
2455 // want to use the real value of the symbol, not the PLT offset.
2456 }
2457 else if (gsym != NULL
2458 && gsym->use_plt_offset(Scan::get_reference_flags(r_type)))
2459 {
2460 symval.set_output_value(target->plt_address_for_global(gsym)
2461 + gsym->plt_offset());
2462 psymval = &symval;
2463 }
2464 else if (gsym == NULL && psymval->is_ifunc_symbol())
2465 {
2466 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2467 if (object->local_has_plt_offset(r_sym))
2468 {
2469 symval.set_output_value(target->plt_address_for_local(object, r_sym)
2470 + object->local_plt_offset(r_sym));
2471 psymval = &symval;
2472 }
2473 }
2474
2475 // Get the GOT offset if needed.
2476 // The GOT pointer points to the end of the GOT section.
2477 // We need to subtract the size of the GOT section to get
2478 // the actual offset to use in the relocation.
2479 bool have_got_offset = false;
2480 unsigned int got_offset = 0;
2481 switch (r_type)
2482 {
2483 case elfcpp::R_386_GOT32:
2484 if (gsym != NULL)
2485 {
2486 gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD));
2487 got_offset = (gsym->got_offset(GOT_TYPE_STANDARD)
2488 - target->got_size());
2489 }
2490 else
2491 {
2492 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2493 gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD));
2494 got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD)
2495 - target->got_size());
2496 }
2497 have_got_offset = true;
2498 break;
2499
2500 default:
2501 break;
2502 }
2503
2504 switch (r_type)
2505 {
2506 case elfcpp::R_386_NONE:
2507 case elfcpp::R_386_GNU_VTINHERIT:
2508 case elfcpp::R_386_GNU_VTENTRY:
2509 break;
2510
2511 case elfcpp::R_386_32:
2512 if (should_apply_static_reloc(gsym, r_type, true, output_section))
2513 Relocate_functions<32, false>::rel32(view, object, psymval);
2514 break;
2515
2516 case elfcpp::R_386_PC32:
2517 if (should_apply_static_reloc(gsym, r_type, true, output_section))
2518 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
2519 break;
2520
2521 case elfcpp::R_386_16:
2522 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2523 Relocate_functions<32, false>::rel16(view, object, psymval);
2524 break;
2525
2526 case elfcpp::R_386_PC16:
2527 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2528 Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
2529 break;
2530
2531 case elfcpp::R_386_8:
2532 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2533 Relocate_functions<32, false>::rel8(view, object, psymval);
2534 break;
2535
2536 case elfcpp::R_386_PC8:
2537 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2538 Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
2539 break;
2540
2541 case elfcpp::R_386_PLT32:
2542 gold_assert(gsym == NULL
2543 || gsym->has_plt_offset()
2544 || gsym->final_value_is_known()
2545 || (gsym->is_defined()
2546 && !gsym->is_from_dynobj()
2547 && !gsym->is_preemptible()));
2548 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
2549 break;
2550
2551 case elfcpp::R_386_GOT32:
2552 gold_assert(have_got_offset);
2553 Relocate_functions<32, false>::rel32(view, got_offset);
2554 break;
2555
2556 case elfcpp::R_386_GOTOFF:
2557 {
2558 elfcpp::Elf_types<32>::Elf_Addr value;
2559 value = (psymval->value(object, 0)
2560 - target->got_plt_section()->address());
2561 Relocate_functions<32, false>::rel32(view, value);
2562 }
2563 break;
2564
2565 case elfcpp::R_386_GOTPC:
2566 {
2567 elfcpp::Elf_types<32>::Elf_Addr value;
2568 value = target->got_plt_section()->address();
2569 Relocate_functions<32, false>::pcrel32(view, value, address);
2570 }
2571 break;
2572
2573 case elfcpp::R_386_COPY:
2574 case elfcpp::R_386_GLOB_DAT:
2575 case elfcpp::R_386_JUMP_SLOT:
2576 case elfcpp::R_386_RELATIVE:
2577 case elfcpp::R_386_IRELATIVE:
2578 // These are outstanding tls relocs, which are unexpected when
2579 // linking.
2580 case elfcpp::R_386_TLS_TPOFF:
2581 case elfcpp::R_386_TLS_DTPMOD32:
2582 case elfcpp::R_386_TLS_DTPOFF32:
2583 case elfcpp::R_386_TLS_TPOFF32:
2584 case elfcpp::R_386_TLS_DESC:
2585 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2586 _("unexpected reloc %u in object file"),
2587 r_type);
2588 break;
2589
2590 // These are initial tls relocs, which are expected when
2591 // linking.
2592 case elfcpp::R_386_TLS_GD: // Global-dynamic
2593 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2594 case elfcpp::R_386_TLS_DESC_CALL:
2595 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2596 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2597 case elfcpp::R_386_TLS_IE: // Initial-exec
2598 case elfcpp::R_386_TLS_IE_32:
2599 case elfcpp::R_386_TLS_GOTIE:
2600 case elfcpp::R_386_TLS_LE: // Local-exec
2601 case elfcpp::R_386_TLS_LE_32:
2602 this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval,
2603 view, address, view_size);
2604 break;
2605
2606 case elfcpp::R_386_32PLT:
2607 case elfcpp::R_386_TLS_GD_32:
2608 case elfcpp::R_386_TLS_GD_PUSH:
2609 case elfcpp::R_386_TLS_GD_CALL:
2610 case elfcpp::R_386_TLS_GD_POP:
2611 case elfcpp::R_386_TLS_LDM_32:
2612 case elfcpp::R_386_TLS_LDM_PUSH:
2613 case elfcpp::R_386_TLS_LDM_CALL:
2614 case elfcpp::R_386_TLS_LDM_POP:
2615 case elfcpp::R_386_USED_BY_INTEL_200:
2616 default:
2617 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2618 _("unsupported reloc %u"),
2619 r_type);
2620 break;
2621 }
2622
2623 return true;
2624 }
2625
2626 // Perform a TLS relocation.
2627
2628 inline void
2629 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
2630 Target_i386* target,
2631 size_t relnum,
2632 const elfcpp::Rel<32, false>& rel,
2633 unsigned int r_type,
2634 const Sized_symbol<32>* gsym,
2635 const Symbol_value<32>* psymval,
2636 unsigned char* view,
2637 elfcpp::Elf_types<32>::Elf_Addr,
2638 section_size_type view_size)
2639 {
2640 Output_segment* tls_segment = relinfo->layout->tls_segment();
2641
2642 const Sized_relobj_file<32, false>* object = relinfo->object;
2643
2644 elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0);
2645
2646 const bool is_final = (gsym == NULL
2647 ? !parameters->options().shared()
2648 : gsym->final_value_is_known());
2649 const tls::Tls_optimization optimized_type
2650 = Target_i386::optimize_tls_reloc(is_final, r_type);
2651 switch (r_type)
2652 {
2653 case elfcpp::R_386_TLS_GD: // Global-dynamic
2654 if (optimized_type == tls::TLSOPT_TO_LE)
2655 {
2656 if (tls_segment == NULL)
2657 {
2658 gold_assert(parameters->errors()->error_count() > 0
2659 || issue_undefined_symbol_error(gsym));
2660 return;
2661 }
2662 this->tls_gd_to_le(relinfo, relnum, tls_segment,
2663 rel, r_type, value, view,
2664 view_size);
2665 break;
2666 }
2667 else
2668 {
2669 unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
2670 ? GOT_TYPE_TLS_NOFFSET
2671 : GOT_TYPE_TLS_PAIR);
2672 unsigned int got_offset;
2673 if (gsym != NULL)
2674 {
2675 gold_assert(gsym->has_got_offset(got_type));
2676 got_offset = gsym->got_offset(got_type) - target->got_size();
2677 }
2678 else
2679 {
2680 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2681 gold_assert(object->local_has_got_offset(r_sym, got_type));
2682 got_offset = (object->local_got_offset(r_sym, got_type)
2683 - target->got_size());
2684 }
2685 if (optimized_type == tls::TLSOPT_TO_IE)
2686 {
2687 if (tls_segment == NULL)
2688 {
2689 gold_assert(parameters->errors()->error_count() > 0
2690 || issue_undefined_symbol_error(gsym));
2691 return;
2692 }
2693 this->tls_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
2694 got_offset, view, view_size);
2695 break;
2696 }
2697 else if (optimized_type == tls::TLSOPT_NONE)
2698 {
2699 // Relocate the field with the offset of the pair of GOT
2700 // entries.
2701 Relocate_functions<32, false>::rel32(view, got_offset);
2702 break;
2703 }
2704 }
2705 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2706 _("unsupported reloc %u"),
2707 r_type);
2708 break;
2709
2710 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2711 case elfcpp::R_386_TLS_DESC_CALL:
2712 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
2713 if (optimized_type == tls::TLSOPT_TO_LE)
2714 {
2715 if (tls_segment == NULL)
2716 {
2717 gold_assert(parameters->errors()->error_count() > 0
2718 || issue_undefined_symbol_error(gsym));
2719 return;
2720 }
2721 this->tls_desc_gd_to_le(relinfo, relnum, tls_segment,
2722 rel, r_type, value, view,
2723 view_size);
2724 break;
2725 }
2726 else
2727 {
2728 unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
2729 ? GOT_TYPE_TLS_NOFFSET
2730 : GOT_TYPE_TLS_DESC);
2731 unsigned int got_offset = 0;
2732 if (r_type == elfcpp::R_386_TLS_GOTDESC
2733 && optimized_type == tls::TLSOPT_NONE)
2734 {
2735 // We created GOT entries in the .got.tlsdesc portion of
2736 // the .got.plt section, but the offset stored in the
2737 // symbol is the offset within .got.tlsdesc.
2738 got_offset = (target->got_size()
2739 + target->got_plt_section()->data_size());
2740 }
2741 if (gsym != NULL)
2742 {
2743 gold_assert(gsym->has_got_offset(got_type));
2744 got_offset += gsym->got_offset(got_type) - target->got_size();
2745 }
2746 else
2747 {
2748 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2749 gold_assert(object->local_has_got_offset(r_sym, got_type));
2750 got_offset += (object->local_got_offset(r_sym, got_type)
2751 - target->got_size());
2752 }
2753 if (optimized_type == tls::TLSOPT_TO_IE)
2754 {
2755 if (tls_segment == NULL)
2756 {
2757 gold_assert(parameters->errors()->error_count() > 0
2758 || issue_undefined_symbol_error(gsym));
2759 return;
2760 }
2761 this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
2762 got_offset, view, view_size);
2763 break;
2764 }
2765 else if (optimized_type == tls::TLSOPT_NONE)
2766 {
2767 if (r_type == elfcpp::R_386_TLS_GOTDESC)
2768 {
2769 // Relocate the field with the offset of the pair of GOT
2770 // entries.
2771 Relocate_functions<32, false>::rel32(view, got_offset);
2772 }
2773 break;
2774 }
2775 }
2776 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2777 _("unsupported reloc %u"),
2778 r_type);
2779 break;
2780
2781 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2782 if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
2783 {
2784 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2785 _("both SUN and GNU model "
2786 "TLS relocations"));
2787 break;
2788 }
2789 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
2790 if (optimized_type == tls::TLSOPT_TO_LE)
2791 {
2792 if (tls_segment == NULL)
2793 {
2794 gold_assert(parameters->errors()->error_count() > 0
2795 || issue_undefined_symbol_error(gsym));
2796 return;
2797 }
2798 this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
2799 value, view, view_size);
2800 break;
2801 }
2802 else if (optimized_type == tls::TLSOPT_NONE)
2803 {
2804 // Relocate the field with the offset of the GOT entry for
2805 // the module index.
2806 unsigned int got_offset;
2807 got_offset = (target->got_mod_index_entry(NULL, NULL, NULL)
2808 - target->got_size());
2809 Relocate_functions<32, false>::rel32(view, got_offset);
2810 break;
2811 }
2812 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2813 _("unsupported reloc %u"),
2814 r_type);
2815 break;
2816
2817 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2818 if (optimized_type == tls::TLSOPT_TO_LE)
2819 {
2820 // This reloc can appear in debugging sections, in which
2821 // case we must not convert to local-exec. We decide what
2822 // to do based on whether the section is marked as
2823 // containing executable code. That is what the GNU linker
2824 // does as well.
2825 elfcpp::Shdr<32, false> shdr(relinfo->data_shdr);
2826 if ((shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0)
2827 {
2828 if (tls_segment == NULL)
2829 {
2830 gold_assert(parameters->errors()->error_count() > 0
2831 || issue_undefined_symbol_error(gsym));
2832 return;
2833 }
2834 value -= tls_segment->memsz();
2835 }
2836 }
2837 Relocate_functions<32, false>::rel32(view, value);
2838 break;
2839
2840 case elfcpp::R_386_TLS_IE: // Initial-exec
2841 case elfcpp::R_386_TLS_GOTIE:
2842 case elfcpp::R_386_TLS_IE_32:
2843 if (optimized_type == tls::TLSOPT_TO_LE)
2844 {
2845 if (tls_segment == NULL)
2846 {
2847 gold_assert(parameters->errors()->error_count() > 0
2848 || issue_undefined_symbol_error(gsym));
2849 return;
2850 }
2851 Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
2852 rel, r_type, value, view,
2853 view_size);
2854 break;
2855 }
2856 else if (optimized_type == tls::TLSOPT_NONE)
2857 {
2858 // Relocate the field with the offset of the GOT entry for
2859 // the tp-relative offset of the symbol.
2860 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
2861 ? GOT_TYPE_TLS_OFFSET
2862 : GOT_TYPE_TLS_NOFFSET);
2863 unsigned int got_offset;
2864 if (gsym != NULL)
2865 {
2866 gold_assert(gsym->has_got_offset(got_type));
2867 got_offset = gsym->got_offset(got_type);
2868 }
2869 else
2870 {
2871 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2872 gold_assert(object->local_has_got_offset(r_sym, got_type));
2873 got_offset = object->local_got_offset(r_sym, got_type);
2874 }
2875 // For the R_386_TLS_IE relocation, we need to apply the
2876 // absolute address of the GOT entry.
2877 if (r_type == elfcpp::R_386_TLS_IE)
2878 got_offset += target->got_plt_section()->address();
2879 // All GOT offsets are relative to the end of the GOT.
2880 got_offset -= target->got_size();
2881 Relocate_functions<32, false>::rel32(view, got_offset);
2882 break;
2883 }
2884 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2885 _("unsupported reloc %u"),
2886 r_type);
2887 break;
2888
2889 case elfcpp::R_386_TLS_LE: // Local-exec
2890 // If we're creating a shared library, a dynamic relocation will
2891 // have been created for this location, so do not apply it now.
2892 if (!parameters->options().shared())
2893 {
2894 if (tls_segment == NULL)
2895 {
2896 gold_assert(parameters->errors()->error_count() > 0
2897 || issue_undefined_symbol_error(gsym));
2898 return;
2899 }
2900 value -= tls_segment->memsz();
2901 Relocate_functions<32, false>::rel32(view, value);
2902 }
2903 break;
2904
2905 case elfcpp::R_386_TLS_LE_32:
2906 // If we're creating a shared library, a dynamic relocation will
2907 // have been created for this location, so do not apply it now.
2908 if (!parameters->options().shared())
2909 {
2910 if (tls_segment == NULL)
2911 {
2912 gold_assert(parameters->errors()->error_count() > 0
2913 || issue_undefined_symbol_error(gsym));
2914 return;
2915 }
2916 value = tls_segment->memsz() - value;
2917 Relocate_functions<32, false>::rel32(view, value);
2918 }
2919 break;
2920 }
2921 }
2922
2923 // Do a relocation in which we convert a TLS General-Dynamic to a
2924 // Local-Exec.
2925
2926 inline void
2927 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
2928 size_t relnum,
2929 Output_segment* tls_segment,
2930 const elfcpp::Rel<32, false>& rel,
2931 unsigned int,
2932 elfcpp::Elf_types<32>::Elf_Addr value,
2933 unsigned char* view,
2934 section_size_type view_size)
2935 {
2936 // leal foo(,%reg,1),%eax; call ___tls_get_addr
2937 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
2938 // leal foo(%reg),%eax; call ___tls_get_addr
2939 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
2940
2941 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
2942 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
2943
2944 unsigned char op1 = view[-1];
2945 unsigned char op2 = view[-2];
2946
2947 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2948 op2 == 0x8d || op2 == 0x04);
2949 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
2950
2951 int roff = 5;
2952
2953 if (op2 == 0x04)
2954 {
2955 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
2956 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
2957 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2958 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
2959 memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
2960 }
2961 else
2962 {
2963 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2964 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
2965 if (rel.get_r_offset() + 9 < view_size
2966 && view[9] == 0x90)
2967 {
2968 // There is a trailing nop. Use the size byte subl.
2969 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
2970 roff = 6;
2971 }
2972 else
2973 {
2974 // Use the five byte subl.
2975 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
2976 }
2977 }
2978
2979 value = tls_segment->memsz() - value;
2980 Relocate_functions<32, false>::rel32(view + roff, value);
2981
2982 // The next reloc should be a PLT32 reloc against __tls_get_addr.
2983 // We can skip it.
2984 this->skip_call_tls_get_addr_ = true;
2985 }
2986
2987 // Do a relocation in which we convert a TLS General-Dynamic to an
2988 // Initial-Exec.
2989
2990 inline void
2991 Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
2992 size_t relnum,
2993 Output_segment*,
2994 const elfcpp::Rel<32, false>& rel,
2995 unsigned int,
2996 elfcpp::Elf_types<32>::Elf_Addr value,
2997 unsigned char* view,
2998 section_size_type view_size)
2999 {
3000 // leal foo(,%ebx,1),%eax; call ___tls_get_addr
3001 // ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
3002
3003 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3004 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3005
3006 unsigned char op1 = view[-1];
3007 unsigned char op2 = view[-2];
3008
3009 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3010 op2 == 0x8d || op2 == 0x04);
3011 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3012
3013 int roff = 5;
3014
3015 // FIXME: For now, support only the first (SIB) form.
3016 tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x04);
3017
3018 if (op2 == 0x04)
3019 {
3020 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
3021 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
3022 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3023 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
3024 memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
3025 }
3026 else
3027 {
3028 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3029 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
3030 if (rel.get_r_offset() + 9 < view_size
3031 && view[9] == 0x90)
3032 {
3033 // FIXME: This is not the right instruction sequence.
3034 // There is a trailing nop. Use the size byte subl.
3035 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3036 roff = 6;
3037 }
3038 else
3039 {
3040 // FIXME: This is not the right instruction sequence.
3041 // Use the five byte subl.
3042 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
3043 }
3044 }
3045
3046 Relocate_functions<32, false>::rel32(view + roff, value);
3047
3048 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3049 // We can skip it.
3050 this->skip_call_tls_get_addr_ = true;
3051 }
3052
3053 // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
3054 // General-Dynamic to a Local-Exec.
3055
3056 inline void
3057 Target_i386::Relocate::tls_desc_gd_to_le(
3058 const Relocate_info<32, false>* relinfo,
3059 size_t relnum,
3060 Output_segment* tls_segment,
3061 const elfcpp::Rel<32, false>& rel,
3062 unsigned int r_type,
3063 elfcpp::Elf_types<32>::Elf_Addr value,
3064 unsigned char* view,
3065 section_size_type view_size)
3066 {
3067 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3068 {
3069 // leal foo@TLSDESC(%ebx), %eax
3070 // ==> leal foo@NTPOFF, %eax
3071 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3072 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3073 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3074 view[-2] == 0x8d && view[-1] == 0x83);
3075 view[-1] = 0x05;
3076 value -= tls_segment->memsz();
3077 Relocate_functions<32, false>::rel32(view, value);
3078 }
3079 else
3080 {
3081 // call *foo@TLSCALL(%eax)
3082 // ==> nop; nop
3083 gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
3084 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
3085 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3086 view[0] == 0xff && view[1] == 0x10);
3087 view[0] = 0x66;
3088 view[1] = 0x90;
3089 }
3090 }
3091
3092 // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
3093 // General-Dynamic to an Initial-Exec.
3094
3095 inline void
3096 Target_i386::Relocate::tls_desc_gd_to_ie(
3097 const Relocate_info<32, false>* relinfo,
3098 size_t relnum,
3099 Output_segment*,
3100 const elfcpp::Rel<32, false>& rel,
3101 unsigned int r_type,
3102 elfcpp::Elf_types<32>::Elf_Addr value,
3103 unsigned char* view,
3104 section_size_type view_size)
3105 {
3106 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3107 {
3108 // leal foo@TLSDESC(%ebx), %eax
3109 // ==> movl foo@GOTNTPOFF(%ebx), %eax
3110 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3111 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3112 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3113 view[-2] == 0x8d && view[-1] == 0x83);
3114 view[-2] = 0x8b;
3115 Relocate_functions<32, false>::rel32(view, value);
3116 }
3117 else
3118 {
3119 // call *foo@TLSCALL(%eax)
3120 // ==> nop; nop
3121 gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
3122 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
3123 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3124 view[0] == 0xff && view[1] == 0x10);
3125 view[0] = 0x66;
3126 view[1] = 0x90;
3127 }
3128 }
3129
3130 // Do a relocation in which we convert a TLS Local-Dynamic to a
3131 // Local-Exec.
3132
3133 inline void
3134 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
3135 size_t relnum,
3136 Output_segment*,
3137 const elfcpp::Rel<32, false>& rel,
3138 unsigned int,
3139 elfcpp::Elf_types<32>::Elf_Addr,
3140 unsigned char* view,
3141 section_size_type view_size)
3142 {
3143 // leal foo(%reg), %eax; call ___tls_get_addr
3144 // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
3145
3146 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3147 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3148
3149 // FIXME: Does this test really always pass?
3150 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3151 view[-2] == 0x8d && view[-1] == 0x83);
3152
3153 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3154
3155 memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
3156
3157 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3158 // We can skip it.
3159 this->skip_call_tls_get_addr_ = true;
3160 }
3161
3162 // Do a relocation in which we convert a TLS Initial-Exec to a
3163 // Local-Exec.
3164
3165 inline void
3166 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
3167 size_t relnum,
3168 Output_segment* tls_segment,
3169 const elfcpp::Rel<32, false>& rel,
3170 unsigned int r_type,
3171 elfcpp::Elf_types<32>::Elf_Addr value,
3172 unsigned char* view,
3173 section_size_type view_size)
3174 {
3175 // We have to actually change the instructions, which means that we
3176 // need to examine the opcodes to figure out which instruction we
3177 // are looking at.
3178 if (r_type == elfcpp::R_386_TLS_IE)
3179 {
3180 // movl %gs:XX,%eax ==> movl $YY,%eax
3181 // movl %gs:XX,%reg ==> movl $YY,%reg
3182 // addl %gs:XX,%reg ==> addl $YY,%reg
3183 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
3184 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3185
3186 unsigned char op1 = view[-1];
3187 if (op1 == 0xa1)
3188 {
3189 // movl XX,%eax ==> movl $YY,%eax
3190 view[-1] = 0xb8;
3191 }
3192 else
3193 {
3194 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3195
3196 unsigned char op2 = view[-2];
3197 if (op2 == 0x8b)
3198 {
3199 // movl XX,%reg ==> movl $YY,%reg
3200 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3201 (op1 & 0xc7) == 0x05);
3202 view[-2] = 0xc7;
3203 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3204 }
3205 else if (op2 == 0x03)
3206 {
3207 // addl XX,%reg ==> addl $YY,%reg
3208 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3209 (op1 & 0xc7) == 0x05);
3210 view[-2] = 0x81;
3211 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3212 }
3213 else
3214 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
3215 }
3216 }
3217 else
3218 {
3219 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
3220 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
3221 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
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, 4);
3224
3225 unsigned char op1 = view[-1];
3226 unsigned char op2 = view[-2];
3227 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3228 (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
3229 if (op2 == 0x8b)
3230 {
3231 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
3232 view[-2] = 0xc7;
3233 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3234 }
3235 else if (op2 == 0x2b)
3236 {
3237 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
3238 view[-2] = 0x81;
3239 view[-1] = 0xe8 | ((op1 >> 3) & 7);
3240 }
3241 else if (op2 == 0x03)
3242 {
3243 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
3244 view[-2] = 0x81;
3245 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3246 }
3247 else
3248 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
3249 }
3250
3251 value = tls_segment->memsz() - value;
3252 if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
3253 value = - value;
3254
3255 Relocate_functions<32, false>::rel32(view, value);
3256 }
3257
3258 // Relocate section data.
3259
3260 void
3261 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
3262 unsigned int sh_type,
3263 const unsigned char* prelocs,
3264 size_t reloc_count,
3265 Output_section* output_section,
3266 bool needs_special_offset_handling,
3267 unsigned char* view,
3268 elfcpp::Elf_types<32>::Elf_Addr address,
3269 section_size_type view_size,
3270 const Reloc_symbol_changes* reloc_symbol_changes)
3271 {
3272 gold_assert(sh_type == elfcpp::SHT_REL);
3273
3274 gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
3275 Target_i386::Relocate>(
3276 relinfo,
3277 this,
3278 prelocs,
3279 reloc_count,
3280 output_section,
3281 needs_special_offset_handling,
3282 view,
3283 address,
3284 view_size,
3285 reloc_symbol_changes);
3286 }
3287
3288 // Return the size of a relocation while scanning during a relocatable
3289 // link.
3290
3291 unsigned int
3292 Target_i386::Relocatable_size_for_reloc::get_size_for_reloc(
3293 unsigned int r_type,
3294 Relobj* object)
3295 {
3296 switch (r_type)
3297 {
3298 case elfcpp::R_386_NONE:
3299 case elfcpp::R_386_GNU_VTINHERIT:
3300 case elfcpp::R_386_GNU_VTENTRY:
3301 case elfcpp::R_386_TLS_GD: // Global-dynamic
3302 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
3303 case elfcpp::R_386_TLS_DESC_CALL:
3304 case elfcpp::R_386_TLS_LDM: // Local-dynamic
3305 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
3306 case elfcpp::R_386_TLS_IE: // Initial-exec
3307 case elfcpp::R_386_TLS_IE_32:
3308 case elfcpp::R_386_TLS_GOTIE:
3309 case elfcpp::R_386_TLS_LE: // Local-exec
3310 case elfcpp::R_386_TLS_LE_32:
3311 return 0;
3312
3313 case elfcpp::R_386_32:
3314 case elfcpp::R_386_PC32:
3315 case elfcpp::R_386_GOT32:
3316 case elfcpp::R_386_PLT32:
3317 case elfcpp::R_386_GOTOFF:
3318 case elfcpp::R_386_GOTPC:
3319 return 4;
3320
3321 case elfcpp::R_386_16:
3322 case elfcpp::R_386_PC16:
3323 return 2;
3324
3325 case elfcpp::R_386_8:
3326 case elfcpp::R_386_PC8:
3327 return 1;
3328
3329 // These are relocations which should only be seen by the
3330 // dynamic linker, and should never be seen here.
3331 case elfcpp::R_386_COPY:
3332 case elfcpp::R_386_GLOB_DAT:
3333 case elfcpp::R_386_JUMP_SLOT:
3334 case elfcpp::R_386_RELATIVE:
3335 case elfcpp::R_386_IRELATIVE:
3336 case elfcpp::R_386_TLS_TPOFF:
3337 case elfcpp::R_386_TLS_DTPMOD32:
3338 case elfcpp::R_386_TLS_DTPOFF32:
3339 case elfcpp::R_386_TLS_TPOFF32:
3340 case elfcpp::R_386_TLS_DESC:
3341 object->error(_("unexpected reloc %u in object file"), r_type);
3342 return 0;
3343
3344 case elfcpp::R_386_32PLT:
3345 case elfcpp::R_386_TLS_GD_32:
3346 case elfcpp::R_386_TLS_GD_PUSH:
3347 case elfcpp::R_386_TLS_GD_CALL:
3348 case elfcpp::R_386_TLS_GD_POP:
3349 case elfcpp::R_386_TLS_LDM_32:
3350 case elfcpp::R_386_TLS_LDM_PUSH:
3351 case elfcpp::R_386_TLS_LDM_CALL:
3352 case elfcpp::R_386_TLS_LDM_POP:
3353 case elfcpp::R_386_USED_BY_INTEL_200:
3354 default:
3355 object->error(_("unsupported reloc %u in object file"), r_type);
3356 return 0;
3357 }
3358 }
3359
3360 // Scan the relocs during a relocatable link.
3361
3362 void
3363 Target_i386::scan_relocatable_relocs(Symbol_table* symtab,
3364 Layout* layout,
3365 Sized_relobj_file<32, false>* object,
3366 unsigned int data_shndx,
3367 unsigned int sh_type,
3368 const unsigned char* prelocs,
3369 size_t reloc_count,
3370 Output_section* output_section,
3371 bool needs_special_offset_handling,
3372 size_t local_symbol_count,
3373 const unsigned char* plocal_symbols,
3374 Relocatable_relocs* rr)
3375 {
3376 gold_assert(sh_type == elfcpp::SHT_REL);
3377
3378 typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_REL,
3379 Relocatable_size_for_reloc> Scan_relocatable_relocs;
3380
3381 gold::scan_relocatable_relocs<32, false, elfcpp::SHT_REL,
3382 Scan_relocatable_relocs>(
3383 symtab,
3384 layout,
3385 object,
3386 data_shndx,
3387 prelocs,
3388 reloc_count,
3389 output_section,
3390 needs_special_offset_handling,
3391 local_symbol_count,
3392 plocal_symbols,
3393 rr);
3394 }
3395
3396 // Relocate a section during a relocatable link.
3397
3398 void
3399 Target_i386::relocate_for_relocatable(
3400 const Relocate_info<32, false>* relinfo,
3401 unsigned int sh_type,
3402 const unsigned char* prelocs,
3403 size_t reloc_count,
3404 Output_section* output_section,
3405 off_t offset_in_output_section,
3406 const Relocatable_relocs* rr,
3407 unsigned char* view,
3408 elfcpp::Elf_types<32>::Elf_Addr view_address,
3409 section_size_type view_size,
3410 unsigned char* reloc_view,
3411 section_size_type reloc_view_size)
3412 {
3413 gold_assert(sh_type == elfcpp::SHT_REL);
3414
3415 gold::relocate_for_relocatable<32, false, elfcpp::SHT_REL>(
3416 relinfo,
3417 prelocs,
3418 reloc_count,
3419 output_section,
3420 offset_in_output_section,
3421 rr,
3422 view,
3423 view_address,
3424 view_size,
3425 reloc_view,
3426 reloc_view_size);
3427 }
3428
3429 // Return the value to use for a dynamic which requires special
3430 // treatment. This is how we support equality comparisons of function
3431 // pointers across shared library boundaries, as described in the
3432 // processor specific ABI supplement.
3433
3434 uint64_t
3435 Target_i386::do_dynsym_value(const Symbol* gsym) const
3436 {
3437 gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
3438 return this->plt_address_for_global(gsym) + gsym->plt_offset();
3439 }
3440
3441 // Return a string used to fill a code section with nops to take up
3442 // the specified length.
3443
3444 std::string
3445 Target_i386::do_code_fill(section_size_type length) const
3446 {
3447 if (length >= 16)
3448 {
3449 // Build a jmp instruction to skip over the bytes.
3450 unsigned char jmp[5];
3451 jmp[0] = 0xe9;
3452 elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
3453 return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
3454 + std::string(length - 5, '\0'));
3455 }
3456
3457 // Nop sequences of various lengths.
3458 const char nop1[1] = { 0x90 }; // nop
3459 const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax
3460 const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi
3461 const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi
3462 const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop
3463 0x00 }; // leal 0(%esi,1),%esi
3464 const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
3465 0x00, 0x00 };
3466 const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
3467 0x00, 0x00, 0x00 };
3468 const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop
3469 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
3470 const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi
3471 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi
3472 0x00 };
3473 const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
3474 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
3475 0x00, 0x00 };
3476 const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
3477 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
3478 0x00, 0x00, 0x00 };
3479 const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
3480 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
3481 0x00, 0x00, 0x00, 0x00 };
3482 const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
3483 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
3484 0x27, 0x00, 0x00, 0x00,
3485 0x00 };
3486 const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
3487 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
3488 0xbc, 0x27, 0x00, 0x00,
3489 0x00, 0x00 };
3490 const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
3491 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
3492 0x90, 0x90, 0x90, 0x90,
3493 0x90, 0x90, 0x90 };
3494
3495 const char* nops[16] = {
3496 NULL,
3497 nop1, nop2, nop3, nop4, nop5, nop6, nop7,
3498 nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
3499 };
3500
3501 return std::string(nops[length], length);
3502 }
3503
3504 // Return the value to use for the base of a DW_EH_PE_datarel offset
3505 // in an FDE. Solaris and SVR4 use DW_EH_PE_datarel because their
3506 // assembler can not write out the difference between two labels in
3507 // different sections, so instead of using a pc-relative value they
3508 // use an offset from the GOT.
3509
3510 uint64_t
3511 Target_i386::do_ehframe_datarel_base() const
3512 {
3513 gold_assert(this->global_offset_table_ != NULL);
3514 Symbol* sym = this->global_offset_table_;
3515 Sized_symbol<32>* ssym = static_cast<Sized_symbol<32>*>(sym);
3516 return ssym->value();
3517 }
3518
3519 // Return whether SYM should be treated as a call to a non-split
3520 // function. We don't want that to be true of a call to a
3521 // get_pc_thunk function.
3522
3523 bool
3524 Target_i386::do_is_call_to_non_split(const Symbol* sym, unsigned int) const
3525 {
3526 return (sym->type() == elfcpp::STT_FUNC
3527 && !is_prefix_of("__i686.get_pc_thunk.", sym->name()));
3528 }
3529
3530 // FNOFFSET in section SHNDX in OBJECT is the start of a function
3531 // compiled with -fsplit-stack. The function calls non-split-stack
3532 // code. We have to change the function so that it always ensures
3533 // that it has enough stack space to run some random function.
3534
3535 void
3536 Target_i386::do_calls_non_split(Relobj* object, unsigned int shndx,
3537 section_offset_type fnoffset,
3538 section_size_type fnsize,
3539 unsigned char* view,
3540 section_size_type view_size,
3541 std::string* from,
3542 std::string* to) const
3543 {
3544 // The function starts with a comparison of the stack pointer and a
3545 // field in the TCB. This is followed by a jump.
3546
3547 // cmp %gs:NN,%esp
3548 if (this->match_view(view, view_size, fnoffset, "\x65\x3b\x25", 3)
3549 && fnsize > 7)
3550 {
3551 // We will call __morestack if the carry flag is set after this
3552 // comparison. We turn the comparison into an stc instruction
3553 // and some nops.
3554 view[fnoffset] = '\xf9';
3555 this->set_view_to_nop(view, view_size, fnoffset + 1, 6);
3556 }
3557 // lea NN(%esp),%ecx
3558 // lea NN(%esp),%edx
3559 else if ((this->match_view(view, view_size, fnoffset, "\x8d\x8c\x24", 3)
3560 || this->match_view(view, view_size, fnoffset, "\x8d\x94\x24", 3))
3561 && fnsize > 7)
3562 {
3563 // This is loading an offset from the stack pointer for a
3564 // comparison. The offset is negative, so we decrease the
3565 // offset by the amount of space we need for the stack. This
3566 // means we will avoid calling __morestack if there happens to
3567 // be plenty of space on the stack already.
3568 unsigned char* pval = view + fnoffset + 3;
3569 uint32_t val = elfcpp::Swap_unaligned<32, false>::readval(pval);
3570 val -= parameters->options().split_stack_adjust_size();
3571 elfcpp::Swap_unaligned<32, false>::writeval(pval, val);
3572 }
3573 else
3574 {
3575 if (!object->has_no_split_stack())
3576 object->error(_("failed to match split-stack sequence at "
3577 "section %u offset %0zx"),
3578 shndx, static_cast<size_t>(fnoffset));
3579 return;
3580 }
3581
3582 // We have to change the function so that it calls
3583 // __morestack_non_split instead of __morestack. The former will
3584 // allocate additional stack space.
3585 *from = "__morestack";
3586 *to = "__morestack_non_split";
3587 }
3588
3589 // The selector for i386 object files.
3590
3591 class Target_selector_i386 : public Target_selector_freebsd
3592 {
3593 public:
3594 Target_selector_i386()
3595 : Target_selector_freebsd(elfcpp::EM_386, 32, false,
3596 "elf32-i386", "elf32-i386-freebsd",
3597 "elf_i386")
3598 { }
3599
3600 Target*
3601 do_instantiate_target()
3602 { return new Target_i386(); }
3603 };
3604
3605 Target_selector_i386 target_selector_i386;
3606
3607 } // End anonymous namespace.
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