1 // i386.cc -- i386 target support for gold.
2
3 // Copyright (C) 2006-2014 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 "nacl.h"
43 #include "gc.h"
44
45 namespace
46 {
47
48 using namespace gold;
49
50 // A class to handle the .got.plt section.
51
52 class Output_data_got_plt_i386 : public Output_section_data_build
53 {
54 public:
Output_data_got_plt_i386(Layout * layout)55 Output_data_got_plt_i386(Layout* layout)
56 : Output_section_data_build(4),
57 layout_(layout)
58 { }
59
60 protected:
61 // Write out the PLT data.
62 void
63 do_write(Output_file*);
64
65 // Write to a map file.
66 void
do_print_to_mapfile(Mapfile * mapfile) const67 do_print_to_mapfile(Mapfile* mapfile) const
68 { mapfile->print_output_data(this, "** GOT PLT"); }
69
70 private:
71 // A pointer to the Layout class, so that we can find the .dynamic
72 // section when we write out the GOT PLT section.
73 Layout* layout_;
74 };
75
76 // A class to handle the PLT data.
77 // This is an abstract base class that handles most of the linker details
78 // but does not know the actual contents of PLT entries. The derived
79 // classes below fill in those details.
80
81 class Output_data_plt_i386 : public Output_section_data
82 {
83 public:
84 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
85
86 Output_data_plt_i386(Layout*, uint64_t addralign,
87 Output_data_got_plt_i386*, Output_data_space*);
88
89 // Add an entry to the PLT.
90 void
91 add_entry(Symbol_table*, Layout*, Symbol* gsym);
92
93 // Add an entry to the PLT for a local STT_GNU_IFUNC symbol.
94 unsigned int
95 add_local_ifunc_entry(Symbol_table*, Layout*,
96 Sized_relobj_file<32, false>* relobj,
97 unsigned int local_sym_index);
98
99 // Return the .rel.plt section data.
100 Reloc_section*
rel_plt() const101 rel_plt() const
102 { return this->rel_; }
103
104 // Return where the TLS_DESC relocations should go.
105 Reloc_section*
106 rel_tls_desc(Layout*);
107
108 // Return where the IRELATIVE relocations should go.
109 Reloc_section*
110 rel_irelative(Symbol_table*, Layout*);
111
112 // Return whether we created a section for IRELATIVE relocations.
113 bool
has_irelative_section() const114 has_irelative_section() const
115 { return this->irelative_rel_ != NULL; }
116
117 // Return the number of PLT entries.
118 unsigned int
entry_count() const119 entry_count() const
120 { return this->count_ + this->irelative_count_; }
121
122 // Return the offset of the first non-reserved PLT entry.
123 unsigned int
first_plt_entry_offset()124 first_plt_entry_offset()
125 { return this->get_plt_entry_size(); }
126
127 // Return the size of a PLT entry.
128 unsigned int
get_plt_entry_size() const129 get_plt_entry_size() const
130 { return this->do_get_plt_entry_size(); }
131
132 // Return the PLT address to use for a global symbol.
133 uint64_t
134 address_for_global(const Symbol*);
135
136 // Return the PLT address to use for a local symbol.
137 uint64_t
138 address_for_local(const Relobj*, unsigned int symndx);
139
140 // Add .eh_frame information for the PLT.
141 void
add_eh_frame(Layout * layout)142 add_eh_frame(Layout* layout)
143 { this->do_add_eh_frame(layout); }
144
145 protected:
146 // Fill the first PLT entry, given the pointer to the PLT section data
147 // and the runtime address of the GOT.
148 void
fill_first_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr got_address)149 fill_first_plt_entry(unsigned char* pov,
150 elfcpp::Elf_types<32>::Elf_Addr got_address)
151 { this->do_fill_first_plt_entry(pov, got_address); }
152
153 // Fill a normal PLT entry, given the pointer to the entry's data in the
154 // section, the runtime address of the GOT, the offset into the GOT of
155 // the corresponding slot, the offset into the relocation section of the
156 // corresponding reloc, and the offset of this entry within the whole
157 // PLT. Return the offset from this PLT entry's runtime address that
158 // should be used to compute the initial value of the GOT slot.
159 unsigned int
fill_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr got_address,unsigned int got_offset,unsigned int plt_offset,unsigned int plt_rel_offset)160 fill_plt_entry(unsigned char* pov,
161 elfcpp::Elf_types<32>::Elf_Addr got_address,
162 unsigned int got_offset,
163 unsigned int plt_offset,
164 unsigned int plt_rel_offset)
165 {
166 return this->do_fill_plt_entry(pov, got_address, got_offset,
167 plt_offset, plt_rel_offset);
168 }
169
170 virtual unsigned int
171 do_get_plt_entry_size() const = 0;
172
173 virtual void
174 do_fill_first_plt_entry(unsigned char* pov,
175 elfcpp::Elf_types<32>::Elf_Addr got_address) = 0;
176
177 virtual unsigned int
178 do_fill_plt_entry(unsigned char* pov,
179 elfcpp::Elf_types<32>::Elf_Addr got_address,
180 unsigned int got_offset,
181 unsigned int plt_offset,
182 unsigned int plt_rel_offset) = 0;
183
184 virtual void
185 do_add_eh_frame(Layout*) = 0;
186
187 void
188 do_adjust_output_section(Output_section* os);
189
190 // Write to a map file.
191 void
do_print_to_mapfile(Mapfile * mapfile) const192 do_print_to_mapfile(Mapfile* mapfile) const
193 { mapfile->print_output_data(this, _("** PLT")); }
194
195 // The .eh_frame unwind information for the PLT.
196 // The CIE is common across variants of the PLT format.
197 static const int plt_eh_frame_cie_size = 16;
198 static const unsigned char plt_eh_frame_cie[plt_eh_frame_cie_size];
199
200 private:
201 // Set the final size.
202 void
set_final_data_size()203 set_final_data_size()
204 {
205 this->set_data_size((this->count_ + this->irelative_count_ + 1)
206 * this->get_plt_entry_size());
207 }
208
209 // Write out the PLT data.
210 void
211 do_write(Output_file*);
212
213 // We keep a list of global STT_GNU_IFUNC symbols, each with its
214 // offset in the GOT.
215 struct Global_ifunc
216 {
217 Symbol* sym;
218 unsigned int got_offset;
219 };
220
221 // We keep a list of local STT_GNU_IFUNC symbols, each with its
222 // offset in the GOT.
223 struct Local_ifunc
224 {
225 Sized_relobj_file<32, false>* object;
226 unsigned int local_sym_index;
227 unsigned int got_offset;
228 };
229
230 // The reloc section.
231 Reloc_section* rel_;
232 // The TLS_DESC relocations, if necessary. These must follow the
233 // regular PLT relocs.
234 Reloc_section* tls_desc_rel_;
235 // The IRELATIVE relocations, if necessary. These must follow the
236 // regular relocatoins and the TLS_DESC relocations.
237 Reloc_section* irelative_rel_;
238 // The .got.plt section.
239 Output_data_got_plt_i386* got_plt_;
240 // The part of the .got.plt section used for IRELATIVE relocs.
241 Output_data_space* got_irelative_;
242 // The number of PLT entries.
243 unsigned int count_;
244 // Number of PLT entries with R_386_IRELATIVE relocs. These follow
245 // the regular PLT entries.
246 unsigned int irelative_count_;
247 // Global STT_GNU_IFUNC symbols.
248 std::vector<Global_ifunc> global_ifuncs_;
249 // Local STT_GNU_IFUNC symbols.
250 std::vector<Local_ifunc> local_ifuncs_;
251 };
252
253 // This is an abstract class for the standard PLT layout.
254 // The derived classes below handle the actual PLT contents
255 // for the executable (non-PIC) and shared-library (PIC) cases.
256 // The unwind information is uniform across those two, so it's here.
257
258 class Output_data_plt_i386_standard : public Output_data_plt_i386
259 {
260 public:
Output_data_plt_i386_standard(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)261 Output_data_plt_i386_standard(Layout* layout,
262 Output_data_got_plt_i386* got_plt,
263 Output_data_space* got_irelative)
264 : Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
265 { }
266
267 protected:
268 virtual unsigned int
do_get_plt_entry_size() const269 do_get_plt_entry_size() const
270 { return plt_entry_size; }
271
272 virtual void
do_add_eh_frame(Layout * layout)273 do_add_eh_frame(Layout* layout)
274 {
275 layout->add_eh_frame_for_plt(this, plt_eh_frame_cie, plt_eh_frame_cie_size,
276 plt_eh_frame_fde, plt_eh_frame_fde_size);
277 }
278
279 // The size of an entry in the PLT.
280 static const int plt_entry_size = 16;
281
282 // The .eh_frame unwind information for the PLT.
283 static const int plt_eh_frame_fde_size = 32;
284 static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
285 };
286
287 // Actually fill the PLT contents for an executable (non-PIC).
288
289 class Output_data_plt_i386_exec : public Output_data_plt_i386_standard
290 {
291 public:
Output_data_plt_i386_exec(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)292 Output_data_plt_i386_exec(Layout* layout,
293 Output_data_got_plt_i386* got_plt,
294 Output_data_space* got_irelative)
295 : Output_data_plt_i386_standard(layout, got_plt, got_irelative)
296 { }
297
298 protected:
299 virtual void
300 do_fill_first_plt_entry(unsigned char* pov,
301 elfcpp::Elf_types<32>::Elf_Addr got_address);
302
303 virtual unsigned int
304 do_fill_plt_entry(unsigned char* pov,
305 elfcpp::Elf_types<32>::Elf_Addr got_address,
306 unsigned int got_offset,
307 unsigned int plt_offset,
308 unsigned int plt_rel_offset);
309
310 private:
311 // The first entry in the PLT for an executable.
312 static const unsigned char first_plt_entry[plt_entry_size];
313
314 // Other entries in the PLT for an executable.
315 static const unsigned char plt_entry[plt_entry_size];
316 };
317
318 // Actually fill the PLT contents for a shared library (PIC).
319
320 class Output_data_plt_i386_dyn : public Output_data_plt_i386_standard
321 {
322 public:
Output_data_plt_i386_dyn(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)323 Output_data_plt_i386_dyn(Layout* layout,
324 Output_data_got_plt_i386* got_plt,
325 Output_data_space* got_irelative)
326 : Output_data_plt_i386_standard(layout, got_plt, got_irelative)
327 { }
328
329 protected:
330 virtual void
331 do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<32>::Elf_Addr);
332
333 virtual unsigned int
334 do_fill_plt_entry(unsigned char* pov,
335 elfcpp::Elf_types<32>::Elf_Addr,
336 unsigned int got_offset,
337 unsigned int plt_offset,
338 unsigned int plt_rel_offset);
339
340 private:
341 // The first entry in the PLT for a shared object.
342 static const unsigned char first_plt_entry[plt_entry_size];
343
344 // Other entries in the PLT for a shared object.
345 static const unsigned char plt_entry[plt_entry_size];
346 };
347
348 // The i386 target class.
349 // TLS info comes from
350 // http://people.redhat.com/drepper/tls.pdf
351 // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
352
353 class Target_i386 : public Sized_target<32, false>
354 {
355 public:
356 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
357
Target_i386(const Target::Target_info * info=& i386_info)358 Target_i386(const Target::Target_info* info = &i386_info)
359 : Sized_target<32, false>(info),
360 got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL),
361 got_tlsdesc_(NULL), global_offset_table_(NULL), rel_dyn_(NULL),
362 rel_irelative_(NULL), copy_relocs_(elfcpp::R_386_COPY),
363 got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
364 { }
365
366 // Process the relocations to determine unreferenced sections for
367 // garbage collection.
368 void
369 gc_process_relocs(Symbol_table* symtab,
370 Layout* layout,
371 Sized_relobj_file<32, false>* object,
372 unsigned int data_shndx,
373 unsigned int sh_type,
374 const unsigned char* prelocs,
375 size_t reloc_count,
376 Output_section* output_section,
377 bool needs_special_offset_handling,
378 size_t local_symbol_count,
379 const unsigned char* plocal_symbols);
380
381 // Scan the relocations to look for symbol adjustments.
382 void
383 scan_relocs(Symbol_table* symtab,
384 Layout* layout,
385 Sized_relobj_file<32, false>* object,
386 unsigned int data_shndx,
387 unsigned int sh_type,
388 const unsigned char* prelocs,
389 size_t reloc_count,
390 Output_section* output_section,
391 bool needs_special_offset_handling,
392 size_t local_symbol_count,
393 const unsigned char* plocal_symbols);
394
395 // Finalize the sections.
396 void
397 do_finalize_sections(Layout*, const Input_objects*, Symbol_table*);
398
399 // Return the value to use for a dynamic which requires special
400 // treatment.
401 uint64_t
402 do_dynsym_value(const Symbol*) const;
403
404 // Relocate a section.
405 void
406 relocate_section(const Relocate_info<32, false>*,
407 unsigned int sh_type,
408 const unsigned char* prelocs,
409 size_t reloc_count,
410 Output_section* output_section,
411 bool needs_special_offset_handling,
412 unsigned char* view,
413 elfcpp::Elf_types<32>::Elf_Addr view_address,
414 section_size_type view_size,
415 const Reloc_symbol_changes*);
416
417 // Scan the relocs during a relocatable link.
418 void
419 scan_relocatable_relocs(Symbol_table* symtab,
420 Layout* layout,
421 Sized_relobj_file<32, false>* object,
422 unsigned int data_shndx,
423 unsigned int sh_type,
424 const unsigned char* prelocs,
425 size_t reloc_count,
426 Output_section* output_section,
427 bool needs_special_offset_handling,
428 size_t local_symbol_count,
429 const unsigned char* plocal_symbols,
430 Relocatable_relocs*);
431
432 // Emit relocations for a section.
433 void
434 relocate_relocs(const Relocate_info<32, false>*,
435 unsigned int sh_type,
436 const unsigned char* prelocs,
437 size_t reloc_count,
438 Output_section* output_section,
439 elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,
440 const Relocatable_relocs*,
441 unsigned char* view,
442 elfcpp::Elf_types<32>::Elf_Addr view_address,
443 section_size_type view_size,
444 unsigned char* reloc_view,
445 section_size_type reloc_view_size);
446
447 // Return a string used to fill a code section with nops.
448 std::string
449 do_code_fill(section_size_type length) const;
450
451 // Return whether SYM is defined by the ABI.
452 bool
do_is_defined_by_abi(const Symbol * sym) const453 do_is_defined_by_abi(const Symbol* sym) const
454 { return strcmp(sym->name(), "___tls_get_addr") == 0; }
455
456 // Return whether a symbol name implies a local label. The UnixWare
457 // 2.1 cc generates temporary symbols that start with .X, so we
458 // recognize them here. FIXME: do other SVR4 compilers also use .X?.
459 // If so, we should move the .X recognition into
460 // Target::do_is_local_label_name.
461 bool
do_is_local_label_name(const char * name) const462 do_is_local_label_name(const char* name) const
463 {
464 if (name[0] == '.' && name[1] == 'X')
465 return true;
466 return Target::do_is_local_label_name(name);
467 }
468
469 // Return the PLT address to use for a global symbol.
470 uint64_t
do_plt_address_for_global(const Symbol * gsym) const471 do_plt_address_for_global(const Symbol* gsym) const
472 { return this->plt_section()->address_for_global(gsym); }
473
474 uint64_t
do_plt_address_for_local(const Relobj * relobj,unsigned int symndx) const475 do_plt_address_for_local(const Relobj* relobj, unsigned int symndx) const
476 { return this->plt_section()->address_for_local(relobj, symndx); }
477
478 // We can tell whether we take the address of a function.
479 inline bool
do_can_check_for_function_pointers() const480 do_can_check_for_function_pointers() const
481 { return true; }
482
483 // Return the base for a DW_EH_PE_datarel encoding.
484 uint64_t
485 do_ehframe_datarel_base() const;
486
487 // Return whether SYM is call to a non-split function.
488 bool
489 do_is_call_to_non_split(const Symbol* sym, unsigned int) const;
490
491 // Adjust -fsplit-stack code which calls non-split-stack code.
492 void
493 do_calls_non_split(Relobj* object, unsigned int shndx,
494 section_offset_type fnoffset, section_size_type fnsize,
495 unsigned char* view, section_size_type view_size,
496 std::string* from, std::string* to) const;
497
498 // Return the size of the GOT section.
499 section_size_type
got_size() const500 got_size() const
501 {
502 gold_assert(this->got_ != NULL);
503 return this->got_->data_size();
504 }
505
506 // Return the number of entries in the GOT.
507 unsigned int
got_entry_count() const508 got_entry_count() const
509 {
510 if (this->got_ == NULL)
511 return 0;
512 return this->got_size() / 4;
513 }
514
515 // Return the number of entries in the PLT.
516 unsigned int
517 plt_entry_count() const;
518
519 // Return the offset of the first non-reserved PLT entry.
520 unsigned int
521 first_plt_entry_offset() const;
522
523 // Return the size of each PLT entry.
524 unsigned int
525 plt_entry_size() const;
526
527 protected:
528 // Instantiate the plt_ member.
529 // This chooses the right PLT flavor for an executable or a shared object.
530 Output_data_plt_i386*
make_data_plt(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative,bool dyn)531 make_data_plt(Layout* layout,
532 Output_data_got_plt_i386* got_plt,
533 Output_data_space* got_irelative,
534 bool dyn)
535 { return this->do_make_data_plt(layout, got_plt, got_irelative, dyn); }
536
537 virtual Output_data_plt_i386*
do_make_data_plt(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative,bool dyn)538 do_make_data_plt(Layout* layout,
539 Output_data_got_plt_i386* got_plt,
540 Output_data_space* got_irelative,
541 bool dyn)
542 {
543 if (dyn)
544 return new Output_data_plt_i386_dyn(layout, got_plt, got_irelative);
545 else
546 return new Output_data_plt_i386_exec(layout, got_plt, got_irelative);
547 }
548
549 private:
550 // The class which scans relocations.
551 struct Scan
552 {
553 static inline int
554
555 get_reference_flags(unsigned int r_type);
556
557 inline void
558 local(Symbol_table* symtab, Layout* layout, Target_i386* target,
559 Sized_relobj_file<32, false>* object,
560 unsigned int data_shndx,
561 Output_section* output_section,
562 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
563 const elfcpp::Sym<32, false>& lsym,
564 bool is_discarded);
565
566 inline void
567 global(Symbol_table* symtab, Layout* layout, Target_i386* target,
568 Sized_relobj_file<32, false>* object,
569 unsigned int data_shndx,
570 Output_section* output_section,
571 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
572 Symbol* gsym);
573
574 inline bool
575 local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
576 Target_i386* target,
577 Sized_relobj_file<32, false>* object,
578 unsigned int data_shndx,
579 Output_section* output_section,
580 const elfcpp::Rel<32, false>& reloc,
581 unsigned int r_type,
582 const elfcpp::Sym<32, false>& lsym);
583
584 inline bool
585 global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
586 Target_i386* target,
587 Sized_relobj_file<32, false>* object,
588 unsigned int data_shndx,
589 Output_section* output_section,
590 const elfcpp::Rel<32, false>& reloc,
591 unsigned int r_type,
592 Symbol* gsym);
593
594 inline bool
595 possible_function_pointer_reloc(unsigned int r_type);
596
597 bool
598 reloc_needs_plt_for_ifunc(Sized_relobj_file<32, false>*,
599 unsigned int r_type);
600
601 static void
602 unsupported_reloc_local(Sized_relobj_file<32, false>*, unsigned int r_type);
603
604 static void
605 unsupported_reloc_global(Sized_relobj_file<32, false>*, unsigned int r_type,
606 Symbol*);
607 };
608
609 // The class which implements relocation.
610 class Relocate
611 {
612 public:
Relocate()613 Relocate()
614 : skip_call_tls_get_addr_(false),
615 local_dynamic_type_(LOCAL_DYNAMIC_NONE)
616 { }
617
~Relocate()618 ~Relocate()
619 {
620 if (this->skip_call_tls_get_addr_)
621 {
622 // FIXME: This needs to specify the location somehow.
623 gold_error(_("missing expected TLS relocation"));
624 }
625 }
626
627 // Return whether the static relocation needs to be applied.
628 inline bool
629 should_apply_static_reloc(const Sized_symbol<32>* gsym,
630 unsigned int r_type,
631 bool is_32bit,
632 Output_section* output_section);
633
634 // Do a relocation. Return false if the caller should not issue
635 // any warnings about this relocation.
636 inline bool
637 relocate(const Relocate_info<32, false>*, Target_i386*, Output_section*,
638 size_t relnum, const elfcpp::Rel<32, false>&,
639 unsigned int r_type, const Sized_symbol<32>*,
640 const Symbol_value<32>*,
641 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
642 section_size_type);
643
644 private:
645 // Do a TLS relocation.
646 inline void
647 relocate_tls(const Relocate_info<32, false>*, Target_i386* target,
648 size_t relnum, const elfcpp::Rel<32, false>&,
649 unsigned int r_type, const Sized_symbol<32>*,
650 const Symbol_value<32>*,
651 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
652 section_size_type);
653
654 // Do a TLS General-Dynamic to Initial-Exec transition.
655 inline void
656 tls_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
657 Output_segment* tls_segment,
658 const elfcpp::Rel<32, false>&, unsigned int r_type,
659 elfcpp::Elf_types<32>::Elf_Addr value,
660 unsigned char* view,
661 section_size_type view_size);
662
663 // Do a TLS General-Dynamic to Local-Exec transition.
664 inline void
665 tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
666 Output_segment* tls_segment,
667 const elfcpp::Rel<32, false>&, unsigned int r_type,
668 elfcpp::Elf_types<32>::Elf_Addr value,
669 unsigned char* view,
670 section_size_type view_size);
671
672 // Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Initial-Exec
673 // transition.
674 inline void
675 tls_desc_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
676 Output_segment* tls_segment,
677 const elfcpp::Rel<32, false>&, unsigned int r_type,
678 elfcpp::Elf_types<32>::Elf_Addr value,
679 unsigned char* view,
680 section_size_type view_size);
681
682 // Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Local-Exec
683 // transition.
684 inline void
685 tls_desc_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
686 Output_segment* tls_segment,
687 const elfcpp::Rel<32, false>&, unsigned int r_type,
688 elfcpp::Elf_types<32>::Elf_Addr value,
689 unsigned char* view,
690 section_size_type view_size);
691
692 // Do a TLS Local-Dynamic to Local-Exec transition.
693 inline void
694 tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
695 Output_segment* tls_segment,
696 const elfcpp::Rel<32, false>&, unsigned int r_type,
697 elfcpp::Elf_types<32>::Elf_Addr value,
698 unsigned char* view,
699 section_size_type view_size);
700
701 // Do a TLS Initial-Exec to Local-Exec transition.
702 static inline void
703 tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
704 Output_segment* tls_segment,
705 const elfcpp::Rel<32, false>&, unsigned int r_type,
706 elfcpp::Elf_types<32>::Elf_Addr value,
707 unsigned char* view,
708 section_size_type view_size);
709
710 // We need to keep track of which type of local dynamic relocation
711 // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
712 enum Local_dynamic_type
713 {
714 LOCAL_DYNAMIC_NONE,
715 LOCAL_DYNAMIC_SUN,
716 LOCAL_DYNAMIC_GNU
717 };
718
719 // This is set if we should skip the next reloc, which should be a
720 // PLT32 reloc against ___tls_get_addr.
721 bool skip_call_tls_get_addr_;
722 // The type of local dynamic relocation we have seen in the section
723 // being relocated, if any.
724 Local_dynamic_type local_dynamic_type_;
725 };
726
727 // A class which returns the size required for a relocation type,
728 // used while scanning relocs during a relocatable link.
729 class Relocatable_size_for_reloc
730 {
731 public:
732 unsigned int
733 get_size_for_reloc(unsigned int, Relobj*);
734 };
735
736 // Adjust TLS relocation type based on the options and whether this
737 // is a local symbol.
738 static tls::Tls_optimization
739 optimize_tls_reloc(bool is_final, int r_type);
740
741 // Check if relocation against this symbol is a candidate for
742 // conversion from
743 // mov foo@GOT(%reg), %reg
744 // to
745 // lea foo@GOTOFF(%reg), %reg.
746 static bool
can_convert_mov_to_lea(const Symbol * gsym)747 can_convert_mov_to_lea(const Symbol* gsym)
748 {
749 gold_assert(gsym != NULL);
750 return (gsym->type() != elfcpp::STT_GNU_IFUNC
751 && !gsym->is_undefined ()
752 && !gsym->is_from_dynobj()
753 && !gsym->is_preemptible()
754 && (!parameters->options().shared()
755 || (gsym->visibility() != elfcpp::STV_DEFAULT
756 && gsym->visibility() != elfcpp::STV_PROTECTED)
757 || parameters->options().Bsymbolic())
758 && strcmp(gsym->name(), "_DYNAMIC") != 0);
759 }
760
761 // Get the GOT section, creating it if necessary.
762 Output_data_got<32, false>*
763 got_section(Symbol_table*, Layout*);
764
765 // Get the GOT PLT section.
766 Output_data_got_plt_i386*
got_plt_section() const767 got_plt_section() const
768 {
769 gold_assert(this->got_plt_ != NULL);
770 return this->got_plt_;
771 }
772
773 // Get the GOT section for TLSDESC entries.
774 Output_data_got<32, false>*
got_tlsdesc_section() const775 got_tlsdesc_section() const
776 {
777 gold_assert(this->got_tlsdesc_ != NULL);
778 return this->got_tlsdesc_;
779 }
780
781 // Create the PLT section.
782 void
783 make_plt_section(Symbol_table* symtab, Layout* layout);
784
785 // Create a PLT entry for a global symbol.
786 void
787 make_plt_entry(Symbol_table*, Layout*, Symbol*);
788
789 // Create a PLT entry for a local STT_GNU_IFUNC symbol.
790 void
791 make_local_ifunc_plt_entry(Symbol_table*, Layout*,
792 Sized_relobj_file<32, false>* relobj,
793 unsigned int local_sym_index);
794
795 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
796 void
797 define_tls_base_symbol(Symbol_table*, Layout*);
798
799 // Create a GOT entry for the TLS module index.
800 unsigned int
801 got_mod_index_entry(Symbol_table* symtab, Layout* layout,
802 Sized_relobj_file<32, false>* object);
803
804 // Get the PLT section.
805 Output_data_plt_i386*
plt_section() const806 plt_section() const
807 {
808 gold_assert(this->plt_ != NULL);
809 return this->plt_;
810 }
811
812 // Get the dynamic reloc section, creating it if necessary.
813 Reloc_section*
814 rel_dyn_section(Layout*);
815
816 // Get the section to use for TLS_DESC relocations.
817 Reloc_section*
818 rel_tls_desc_section(Layout*) const;
819
820 // Get the section to use for IRELATIVE relocations.
821 Reloc_section*
822 rel_irelative_section(Layout*);
823
824 // Add a potential copy relocation.
825 void
copy_reloc(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * object,unsigned int shndx,Output_section * output_section,Symbol * sym,const elfcpp::Rel<32,false> & reloc)826 copy_reloc(Symbol_table* symtab, Layout* layout,
827 Sized_relobj_file<32, false>* object,
828 unsigned int shndx, Output_section* output_section,
829 Symbol* sym, const elfcpp::Rel<32, false>& reloc)
830 {
831 this->copy_relocs_.copy_reloc(symtab, layout,
832 symtab->get_sized_symbol<32>(sym),
833 object, shndx, output_section, reloc,
834 this->rel_dyn_section(layout));
835 }
836
837 // Information about this specific target which we pass to the
838 // general Target structure.
839 static const Target::Target_info i386_info;
840
841 // The types of GOT entries needed for this platform.
842 // These values are exposed to the ABI in an incremental link.
843 // Do not renumber existing values without changing the version
844 // number of the .gnu_incremental_inputs section.
845 enum Got_type
846 {
847 GOT_TYPE_STANDARD = 0, // GOT entry for a regular symbol
848 GOT_TYPE_TLS_NOFFSET = 1, // GOT entry for negative TLS offset
849 GOT_TYPE_TLS_OFFSET = 2, // GOT entry for positive TLS offset
850 GOT_TYPE_TLS_PAIR = 3, // GOT entry for TLS module/offset pair
851 GOT_TYPE_TLS_DESC = 4 // GOT entry for TLS_DESC pair
852 };
853
854 // The GOT section.
855 Output_data_got<32, false>* got_;
856 // The PLT section.
857 Output_data_plt_i386* plt_;
858 // The GOT PLT section.
859 Output_data_got_plt_i386* got_plt_;
860 // The GOT section for IRELATIVE relocations.
861 Output_data_space* got_irelative_;
862 // The GOT section for TLSDESC relocations.
863 Output_data_got<32, false>* got_tlsdesc_;
864 // The _GLOBAL_OFFSET_TABLE_ symbol.
865 Symbol* global_offset_table_;
866 // The dynamic reloc section.
867 Reloc_section* rel_dyn_;
868 // The section to use for IRELATIVE relocs.
869 Reloc_section* rel_irelative_;
870 // Relocs saved to avoid a COPY reloc.
871 Copy_relocs<elfcpp::SHT_REL, 32, false> copy_relocs_;
872 // Offset of the GOT entry for the TLS module index.
873 unsigned int got_mod_index_offset_;
874 // True if the _TLS_MODULE_BASE_ symbol has been defined.
875 bool tls_base_symbol_defined_;
876 };
877
878 const Target::Target_info Target_i386::i386_info =
879 {
880 32, // size
881 false, // is_big_endian
882 elfcpp::EM_386, // machine_code
883 false, // has_make_symbol
884 false, // has_resolve
885 true, // has_code_fill
886 true, // is_default_stack_executable
887 true, // can_icf_inline_merge_sections
888 '\0', // wrap_char
889 "/usr/lib/libc.so.1", // dynamic_linker
890 0x08048000, // default_text_segment_address
891 0x1000, // abi_pagesize (overridable by -z max-page-size)
892 0x1000, // common_pagesize (overridable by -z common-page-size)
893 false, // isolate_execinstr
894 0, // rosegment_gap
895 elfcpp::SHN_UNDEF, // small_common_shndx
896 elfcpp::SHN_UNDEF, // large_common_shndx
897 0, // small_common_section_flags
898 0, // large_common_section_flags
899 NULL, // attributes_section
900 NULL, // attributes_vendor
901 "_start" // entry_symbol_name
902 };
903
904 // Get the GOT section, creating it if necessary.
905
906 Output_data_got<32, false>*
got_section(Symbol_table * symtab,Layout * layout)907 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
908 {
909 if (this->got_ == NULL)
910 {
911 gold_assert(symtab != NULL && layout != NULL);
912
913 this->got_ = new Output_data_got<32, false>();
914
915 // When using -z now, we can treat .got.plt as a relro section.
916 // Without -z now, it is modified after program startup by lazy
917 // PLT relocations.
918 bool is_got_plt_relro = parameters->options().now();
919 Output_section_order got_order = (is_got_plt_relro
920 ? ORDER_RELRO
921 : ORDER_RELRO_LAST);
922 Output_section_order got_plt_order = (is_got_plt_relro
923 ? ORDER_RELRO
924 : ORDER_NON_RELRO_FIRST);
925
926 layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
927 (elfcpp::SHF_ALLOC
928 | elfcpp::SHF_WRITE),
929 this->got_, got_order, true);
930
931 this->got_plt_ = new Output_data_got_plt_i386(layout);
932 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
933 (elfcpp::SHF_ALLOC
934 | elfcpp::SHF_WRITE),
935 this->got_plt_, got_plt_order,
936 is_got_plt_relro);
937
938 // The first three entries are reserved.
939 this->got_plt_->set_current_data_size(3 * 4);
940
941 if (!is_got_plt_relro)
942 {
943 // Those bytes can go into the relro segment.
944 layout->increase_relro(3 * 4);
945 }
946
947 // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
948 this->global_offset_table_ =
949 symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
950 Symbol_table::PREDEFINED,
951 this->got_plt_,
952 0, 0, elfcpp::STT_OBJECT,
953 elfcpp::STB_LOCAL,
954 elfcpp::STV_HIDDEN, 0,
955 false, false);
956
957 // If there are any IRELATIVE relocations, they get GOT entries
958 // in .got.plt after the jump slot relocations.
959 this->got_irelative_ = new Output_data_space(4, "** GOT IRELATIVE PLT");
960 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
961 (elfcpp::SHF_ALLOC
962 | elfcpp::SHF_WRITE),
963 this->got_irelative_,
964 got_plt_order, is_got_plt_relro);
965
966 // If there are any TLSDESC relocations, they get GOT entries in
967 // .got.plt after the jump slot entries.
968 this->got_tlsdesc_ = new Output_data_got<32, false>();
969 layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
970 (elfcpp::SHF_ALLOC
971 | elfcpp::SHF_WRITE),
972 this->got_tlsdesc_,
973 got_plt_order, is_got_plt_relro);
974 }
975
976 return this->got_;
977 }
978
979 // Get the dynamic reloc section, creating it if necessary.
980
981 Target_i386::Reloc_section*
rel_dyn_section(Layout * layout)982 Target_i386::rel_dyn_section(Layout* layout)
983 {
984 if (this->rel_dyn_ == NULL)
985 {
986 gold_assert(layout != NULL);
987 this->rel_dyn_ = new Reloc_section(parameters->options().combreloc());
988 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
989 elfcpp::SHF_ALLOC, this->rel_dyn_,
990 ORDER_DYNAMIC_RELOCS, false);
991 }
992 return this->rel_dyn_;
993 }
994
995 // Get the section to use for IRELATIVE relocs, creating it if
996 // necessary. These go in .rel.dyn, but only after all other dynamic
997 // relocations. They need to follow the other dynamic relocations so
998 // that they can refer to global variables initialized by those
999 // relocs.
1000
1001 Target_i386::Reloc_section*
rel_irelative_section(Layout * layout)1002 Target_i386::rel_irelative_section(Layout* layout)
1003 {
1004 if (this->rel_irelative_ == NULL)
1005 {
1006 // Make sure we have already create the dynamic reloc section.
1007 this->rel_dyn_section(layout);
1008 this->rel_irelative_ = new Reloc_section(false);
1009 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
1010 elfcpp::SHF_ALLOC, this->rel_irelative_,
1011 ORDER_DYNAMIC_RELOCS, false);
1012 gold_assert(this->rel_dyn_->output_section()
1013 == this->rel_irelative_->output_section());
1014 }
1015 return this->rel_irelative_;
1016 }
1017
1018 // Write the first three reserved words of the .got.plt section.
1019 // The remainder of the section is written while writing the PLT
1020 // in Output_data_plt_i386::do_write.
1021
1022 void
do_write(Output_file * of)1023 Output_data_got_plt_i386::do_write(Output_file* of)
1024 {
1025 // The first entry in the GOT is the address of the .dynamic section
1026 // aka the PT_DYNAMIC segment. The next two entries are reserved.
1027 // We saved space for them when we created the section in
1028 // Target_i386::got_section.
1029 const off_t got_file_offset = this->offset();
1030 gold_assert(this->data_size() >= 12);
1031 unsigned char* const got_view = of->get_output_view(got_file_offset, 12);
1032 Output_section* dynamic = this->layout_->dynamic_section();
1033 uint32_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
1034 elfcpp::Swap<32, false>::writeval(got_view, dynamic_addr);
1035 memset(got_view + 4, 0, 8);
1036 of->write_output_view(got_file_offset, 12, got_view);
1037 }
1038
1039 // Create the PLT section. The ordinary .got section is an argument,
1040 // since we need to refer to the start. We also create our own .got
1041 // section just for PLT entries.
1042
Output_data_plt_i386(Layout * layout,uint64_t addralign,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)1043 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
1044 uint64_t addralign,
1045 Output_data_got_plt_i386* got_plt,
1046 Output_data_space* got_irelative)
1047 : Output_section_data(addralign),
1048 tls_desc_rel_(NULL), irelative_rel_(NULL), got_plt_(got_plt),
1049 got_irelative_(got_irelative), count_(0), irelative_count_(0),
1050 global_ifuncs_(), local_ifuncs_()
1051 {
1052 this->rel_ = new Reloc_section(false);
1053 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
1054 elfcpp::SHF_ALLOC, this->rel_,
1055 ORDER_DYNAMIC_PLT_RELOCS, false);
1056 }
1057
1058 void
do_adjust_output_section(Output_section * os)1059 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
1060 {
1061 // UnixWare sets the entsize of .plt to 4, and so does the old GNU
1062 // linker, and so do we.
1063 os->set_entsize(4);
1064 }
1065
1066 // Add an entry to the PLT.
1067
1068 void
add_entry(Symbol_table * symtab,Layout * layout,Symbol * gsym)1069 Output_data_plt_i386::add_entry(Symbol_table* symtab, Layout* layout,
1070 Symbol* gsym)
1071 {
1072 gold_assert(!gsym->has_plt_offset());
1073
1074 // Every PLT entry needs a reloc.
1075 if (gsym->type() == elfcpp::STT_GNU_IFUNC
1076 && gsym->can_use_relative_reloc(false))
1077 {
1078 gsym->set_plt_offset(this->irelative_count_ * this->get_plt_entry_size());
1079 ++this->irelative_count_;
1080 section_offset_type got_offset =
1081 this->got_irelative_->current_data_size();
1082 this->got_irelative_->set_current_data_size(got_offset + 4);
1083 Reloc_section* rel = this->rel_irelative(symtab, layout);
1084 rel->add_symbolless_global_addend(gsym, elfcpp::R_386_IRELATIVE,
1085 this->got_irelative_, got_offset);
1086 struct Global_ifunc gi;
1087 gi.sym = gsym;
1088 gi.got_offset = got_offset;
1089 this->global_ifuncs_.push_back(gi);
1090 }
1091 else
1092 {
1093 // When setting the PLT offset we skip the initial reserved PLT
1094 // entry.
1095 gsym->set_plt_offset((this->count_ + 1) * this->get_plt_entry_size());
1096
1097 ++this->count_;
1098
1099 section_offset_type got_offset = this->got_plt_->current_data_size();
1100
1101 // Every PLT entry needs a GOT entry which points back to the
1102 // PLT entry (this will be changed by the dynamic linker,
1103 // normally lazily when the function is called).
1104 this->got_plt_->set_current_data_size(got_offset + 4);
1105
1106 gsym->set_needs_dynsym_entry();
1107 this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
1108 got_offset);
1109 }
1110
1111 // Note that we don't need to save the symbol. The contents of the
1112 // PLT are independent of which symbols are used. The symbols only
1113 // appear in the relocations.
1114 }
1115
1116 // Add an entry to the PLT for a local STT_GNU_IFUNC symbol. Return
1117 // the PLT offset.
1118
1119 unsigned int
add_local_ifunc_entry(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * relobj,unsigned int local_sym_index)1120 Output_data_plt_i386::add_local_ifunc_entry(
1121 Symbol_table* symtab,
1122 Layout* layout,
1123 Sized_relobj_file<32, false>* relobj,
1124 unsigned int local_sym_index)
1125 {
1126 unsigned int plt_offset = this->irelative_count_ * this->get_plt_entry_size();
1127 ++this->irelative_count_;
1128
1129 section_offset_type got_offset = this->got_irelative_->current_data_size();
1130
1131 // Every PLT entry needs a GOT entry which points back to the PLT
1132 // entry.
1133 this->got_irelative_->set_current_data_size(got_offset + 4);
1134
1135 // Every PLT entry needs a reloc.
1136 Reloc_section* rel = this->rel_irelative(symtab, layout);
1137 rel->add_symbolless_local_addend(relobj, local_sym_index,
1138 elfcpp::R_386_IRELATIVE,
1139 this->got_irelative_, got_offset);
1140
1141 struct Local_ifunc li;
1142 li.object = relobj;
1143 li.local_sym_index = local_sym_index;
1144 li.got_offset = got_offset;
1145 this->local_ifuncs_.push_back(li);
1146
1147 return plt_offset;
1148 }
1149
1150 // Return where the TLS_DESC relocations should go, creating it if
1151 // necessary. These follow the JUMP_SLOT relocations.
1152
1153 Output_data_plt_i386::Reloc_section*
rel_tls_desc(Layout * layout)1154 Output_data_plt_i386::rel_tls_desc(Layout* layout)
1155 {
1156 if (this->tls_desc_rel_ == NULL)
1157 {
1158 this->tls_desc_rel_ = new Reloc_section(false);
1159 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
1160 elfcpp::SHF_ALLOC, this->tls_desc_rel_,
1161 ORDER_DYNAMIC_PLT_RELOCS, false);
1162 gold_assert(this->tls_desc_rel_->output_section()
1163 == this->rel_->output_section());
1164 }
1165 return this->tls_desc_rel_;
1166 }
1167
1168 // Return where the IRELATIVE relocations should go in the PLT. These
1169 // follow the JUMP_SLOT and TLS_DESC relocations.
1170
1171 Output_data_plt_i386::Reloc_section*
rel_irelative(Symbol_table * symtab,Layout * layout)1172 Output_data_plt_i386::rel_irelative(Symbol_table* symtab, Layout* layout)
1173 {
1174 if (this->irelative_rel_ == NULL)
1175 {
1176 // Make sure we have a place for the TLS_DESC relocations, in
1177 // case we see any later on.
1178 this->rel_tls_desc(layout);
1179 this->irelative_rel_ = new Reloc_section(false);
1180 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
1181 elfcpp::SHF_ALLOC, this->irelative_rel_,
1182 ORDER_DYNAMIC_PLT_RELOCS, false);
1183 gold_assert(this->irelative_rel_->output_section()
1184 == this->rel_->output_section());
1185
1186 if (parameters->doing_static_link())
1187 {
1188 // A statically linked executable will only have a .rel.plt
1189 // section to hold R_386_IRELATIVE relocs for STT_GNU_IFUNC
1190 // symbols. The library will use these symbols to locate
1191 // the IRELATIVE relocs at program startup time.
1192 symtab->define_in_output_data("__rel_iplt_start", NULL,
1193 Symbol_table::PREDEFINED,
1194 this->irelative_rel_, 0, 0,
1195 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
1196 elfcpp::STV_HIDDEN, 0, false, true);
1197 symtab->define_in_output_data("__rel_iplt_end", NULL,
1198 Symbol_table::PREDEFINED,
1199 this->irelative_rel_, 0, 0,
1200 elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
1201 elfcpp::STV_HIDDEN, 0, true, true);
1202 }
1203 }
1204 return this->irelative_rel_;
1205 }
1206
1207 // Return the PLT address to use for a global symbol.
1208
1209 uint64_t
address_for_global(const Symbol * gsym)1210 Output_data_plt_i386::address_for_global(const Symbol* gsym)
1211 {
1212 uint64_t offset = 0;
1213 if (gsym->type() == elfcpp::STT_GNU_IFUNC
1214 && gsym->can_use_relative_reloc(false))
1215 offset = (this->count_ + 1) * this->get_plt_entry_size();
1216 return this->address() + offset + gsym->plt_offset();
1217 }
1218
1219 // Return the PLT address to use for a local symbol. These are always
1220 // IRELATIVE relocs.
1221
1222 uint64_t
address_for_local(const Relobj * object,unsigned int r_sym)1223 Output_data_plt_i386::address_for_local(const Relobj* object,
1224 unsigned int r_sym)
1225 {
1226 return (this->address()
1227 + (this->count_ + 1) * this->get_plt_entry_size()
1228 + object->local_plt_offset(r_sym));
1229 }
1230
1231 // The first entry in the PLT for an executable.
1232
1233 const unsigned char Output_data_plt_i386_exec::first_plt_entry[plt_entry_size] =
1234 {
1235 0xff, 0x35, // pushl contents of memory address
1236 0, 0, 0, 0, // replaced with address of .got + 4
1237 0xff, 0x25, // jmp indirect
1238 0, 0, 0, 0, // replaced with address of .got + 8
1239 0, 0, 0, 0 // unused
1240 };
1241
1242 void
do_fill_first_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr got_address)1243 Output_data_plt_i386_exec::do_fill_first_plt_entry(
1244 unsigned char* pov,
1245 elfcpp::Elf_types<32>::Elf_Addr got_address)
1246 {
1247 memcpy(pov, first_plt_entry, plt_entry_size);
1248 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
1249 elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
1250 }
1251
1252 // The first entry in the PLT for a shared object.
1253
1254 const unsigned char Output_data_plt_i386_dyn::first_plt_entry[plt_entry_size] =
1255 {
1256 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
1257 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx)
1258 0, 0, 0, 0 // unused
1259 };
1260
1261 void
do_fill_first_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr)1262 Output_data_plt_i386_dyn::do_fill_first_plt_entry(
1263 unsigned char* pov,
1264 elfcpp::Elf_types<32>::Elf_Addr)
1265 {
1266 memcpy(pov, first_plt_entry, plt_entry_size);
1267 }
1268
1269 // Subsequent entries in the PLT for an executable.
1270
1271 const unsigned char Output_data_plt_i386_exec::plt_entry[plt_entry_size] =
1272 {
1273 0xff, 0x25, // jmp indirect
1274 0, 0, 0, 0, // replaced with address of symbol in .got
1275 0x68, // pushl immediate
1276 0, 0, 0, 0, // replaced with offset into relocation table
1277 0xe9, // jmp relative
1278 0, 0, 0, 0 // replaced with offset to start of .plt
1279 };
1280
1281 unsigned int
do_fill_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr got_address,unsigned int got_offset,unsigned int plt_offset,unsigned int plt_rel_offset)1282 Output_data_plt_i386_exec::do_fill_plt_entry(
1283 unsigned char* pov,
1284 elfcpp::Elf_types<32>::Elf_Addr got_address,
1285 unsigned int got_offset,
1286 unsigned int plt_offset,
1287 unsigned int plt_rel_offset)
1288 {
1289 memcpy(pov, plt_entry, plt_entry_size);
1290 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
1291 got_address + got_offset);
1292 elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
1293 elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + 12 + 4));
1294 return 6;
1295 }
1296
1297 // Subsequent entries in the PLT for a shared object.
1298
1299 const unsigned char Output_data_plt_i386_dyn::plt_entry[plt_entry_size] =
1300 {
1301 0xff, 0xa3, // jmp *offset(%ebx)
1302 0, 0, 0, 0, // replaced with offset of symbol in .got
1303 0x68, // pushl immediate
1304 0, 0, 0, 0, // replaced with offset into relocation table
1305 0xe9, // jmp relative
1306 0, 0, 0, 0 // replaced with offset to start of .plt
1307 };
1308
1309 unsigned int
do_fill_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr,unsigned int got_offset,unsigned int plt_offset,unsigned int plt_rel_offset)1310 Output_data_plt_i386_dyn::do_fill_plt_entry(unsigned char* pov,
1311 elfcpp::Elf_types<32>::Elf_Addr,
1312 unsigned int got_offset,
1313 unsigned int plt_offset,
1314 unsigned int plt_rel_offset)
1315 {
1316 memcpy(pov, plt_entry, plt_entry_size);
1317 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
1318 elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
1319 elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + 12 + 4));
1320 return 6;
1321 }
1322
1323 // The .eh_frame unwind information for the PLT.
1324
1325 const unsigned char
1326 Output_data_plt_i386::plt_eh_frame_cie[plt_eh_frame_cie_size] =
1327 {
1328 1, // CIE version.
1329 'z', // Augmentation: augmentation size included.
1330 'R', // Augmentation: FDE encoding included.
1331 '\0', // End of augmentation string.
1332 1, // Code alignment factor.
1333 0x7c, // Data alignment factor.
1334 8, // Return address column.
1335 1, // Augmentation size.
1336 (elfcpp::DW_EH_PE_pcrel // FDE encoding.
1337 | elfcpp::DW_EH_PE_sdata4),
1338 elfcpp::DW_CFA_def_cfa, 4, 4, // DW_CFA_def_cfa: r4 (esp) ofs 4.
1339 elfcpp::DW_CFA_offset + 8, 1, // DW_CFA_offset: r8 (eip) at cfa-4.
1340 elfcpp::DW_CFA_nop, // Align to 16 bytes.
1341 elfcpp::DW_CFA_nop
1342 };
1343
1344 const unsigned char
1345 Output_data_plt_i386_standard::plt_eh_frame_fde[plt_eh_frame_fde_size] =
1346 {
1347 0, 0, 0, 0, // Replaced with offset to .plt.
1348 0, 0, 0, 0, // Replaced with size of .plt.
1349 0, // Augmentation size.
1350 elfcpp::DW_CFA_def_cfa_offset, 8, // DW_CFA_def_cfa_offset: 8.
1351 elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
1352 elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
1353 elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16.
1354 elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
1355 11, // Block length.
1356 elfcpp::DW_OP_breg4, 4, // Push %esp + 4.
1357 elfcpp::DW_OP_breg8, 0, // Push %eip.
1358 elfcpp::DW_OP_lit15, // Push 0xf.
1359 elfcpp::DW_OP_and, // & (%eip & 0xf).
1360 elfcpp::DW_OP_lit11, // Push 0xb.
1361 elfcpp::DW_OP_ge, // >= ((%eip & 0xf) >= 0xb)
1362 elfcpp::DW_OP_lit2, // Push 2.
1363 elfcpp::DW_OP_shl, // << (((%eip & 0xf) >= 0xb) << 2)
1364 elfcpp::DW_OP_plus, // + ((((%eip&0xf)>=0xb)<<2)+%esp+4
1365 elfcpp::DW_CFA_nop, // Align to 32 bytes.
1366 elfcpp::DW_CFA_nop,
1367 elfcpp::DW_CFA_nop,
1368 elfcpp::DW_CFA_nop
1369 };
1370
1371 // Write out the PLT. This uses the hand-coded instructions above,
1372 // and adjusts them as needed. This is all specified by the i386 ELF
1373 // Processor Supplement.
1374
1375 void
do_write(Output_file * of)1376 Output_data_plt_i386::do_write(Output_file* of)
1377 {
1378 const off_t offset = this->offset();
1379 const section_size_type oview_size =
1380 convert_to_section_size_type(this->data_size());
1381 unsigned char* const oview = of->get_output_view(offset, oview_size);
1382
1383 const off_t got_file_offset = this->got_plt_->offset();
1384 gold_assert(parameters->incremental_update()
1385 || (got_file_offset + this->got_plt_->data_size()
1386 == this->got_irelative_->offset()));
1387 const section_size_type got_size =
1388 convert_to_section_size_type(this->got_plt_->data_size()
1389 + this->got_irelative_->data_size());
1390
1391 unsigned char* const got_view = of->get_output_view(got_file_offset,
1392 got_size);
1393
1394 unsigned char* pov = oview;
1395
1396 elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
1397 elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
1398
1399 this->fill_first_plt_entry(pov, got_address);
1400 pov += this->get_plt_entry_size();
1401
1402 // The first three entries in the GOT are reserved, and are written
1403 // by Output_data_got_plt_i386::do_write.
1404 unsigned char* got_pov = got_view + 12;
1405
1406 const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
1407
1408 unsigned int plt_offset = this->get_plt_entry_size();
1409 unsigned int plt_rel_offset = 0;
1410 unsigned int got_offset = 12;
1411 const unsigned int count = this->count_ + this->irelative_count_;
1412 for (unsigned int i = 0;
1413 i < count;
1414 ++i,
1415 pov += this->get_plt_entry_size(),
1416 got_pov += 4,
1417 plt_offset += this->get_plt_entry_size(),
1418 plt_rel_offset += rel_size,
1419 got_offset += 4)
1420 {
1421 // Set and adjust the PLT entry itself.
1422 unsigned int lazy_offset = this->fill_plt_entry(pov,
1423 got_address,
1424 got_offset,
1425 plt_offset,
1426 plt_rel_offset);
1427
1428 // Set the entry in the GOT.
1429 elfcpp::Swap<32, false>::writeval(got_pov,
1430 plt_address + plt_offset + lazy_offset);
1431 }
1432
1433 // If any STT_GNU_IFUNC symbols have PLT entries, we need to change
1434 // the GOT to point to the actual symbol value, rather than point to
1435 // the PLT entry. That will let the dynamic linker call the right
1436 // function when resolving IRELATIVE relocations.
1437 unsigned char* got_irelative_view = got_view + this->got_plt_->data_size();
1438 for (std::vector<Global_ifunc>::const_iterator p =
1439 this->global_ifuncs_.begin();
1440 p != this->global_ifuncs_.end();
1441 ++p)
1442 {
1443 const Sized_symbol<32>* ssym =
1444 static_cast<const Sized_symbol<32>*>(p->sym);
1445 elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
1446 ssym->value());
1447 }
1448
1449 for (std::vector<Local_ifunc>::const_iterator p =
1450 this->local_ifuncs_.begin();
1451 p != this->local_ifuncs_.end();
1452 ++p)
1453 {
1454 const Symbol_value<32>* psymval =
1455 p->object->local_symbol(p->local_sym_index);
1456 elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
1457 psymval->value(p->object, 0));
1458 }
1459
1460 gold_assert(static_cast<section_size_type>(pov - oview) == oview_size);
1461 gold_assert(static_cast<section_size_type>(got_pov - got_view) == got_size);
1462
1463 of->write_output_view(offset, oview_size, oview);
1464 of->write_output_view(got_file_offset, got_size, got_view);
1465 }
1466
1467 // Create the PLT section.
1468
1469 void
make_plt_section(Symbol_table * symtab,Layout * layout)1470 Target_i386::make_plt_section(Symbol_table* symtab, Layout* layout)
1471 {
1472 if (this->plt_ == NULL)
1473 {
1474 // Create the GOT sections first.
1475 this->got_section(symtab, layout);
1476
1477 const bool dyn = parameters->options().output_is_position_independent();
1478 this->plt_ = this->make_data_plt(layout,
1479 this->got_plt_,
1480 this->got_irelative_,
1481 dyn);
1482
1483 // Add unwind information if requested.
1484 if (parameters->options().ld_generated_unwind_info())
1485 this->plt_->add_eh_frame(layout);
1486
1487 layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
1488 (elfcpp::SHF_ALLOC
1489 | elfcpp::SHF_EXECINSTR),
1490 this->plt_, ORDER_PLT, false);
1491
1492 // Make the sh_info field of .rel.plt point to .plt.
1493 Output_section* rel_plt_os = this->plt_->rel_plt()->output_section();
1494 rel_plt_os->set_info_section(this->plt_->output_section());
1495 }
1496 }
1497
1498 // Create a PLT entry for a global symbol.
1499
1500 void
make_plt_entry(Symbol_table * symtab,Layout * layout,Symbol * gsym)1501 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
1502 {
1503 if (gsym->has_plt_offset())
1504 return;
1505 if (this->plt_ == NULL)
1506 this->make_plt_section(symtab, layout);
1507 this->plt_->add_entry(symtab, layout, gsym);
1508 }
1509
1510 // Make a PLT entry for a local STT_GNU_IFUNC symbol.
1511
1512 void
make_local_ifunc_plt_entry(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * relobj,unsigned int local_sym_index)1513 Target_i386::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout,
1514 Sized_relobj_file<32, false>* relobj,
1515 unsigned int local_sym_index)
1516 {
1517 if (relobj->local_has_plt_offset(local_sym_index))
1518 return;
1519 if (this->plt_ == NULL)
1520 this->make_plt_section(symtab, layout);
1521 unsigned int plt_offset = this->plt_->add_local_ifunc_entry(symtab, layout,
1522 relobj,
1523 local_sym_index);
1524 relobj->set_local_plt_offset(local_sym_index, plt_offset);
1525 }
1526
1527 // Return the number of entries in the PLT.
1528
1529 unsigned int
plt_entry_count() const1530 Target_i386::plt_entry_count() const
1531 {
1532 if (this->plt_ == NULL)
1533 return 0;
1534 return this->plt_->entry_count();
1535 }
1536
1537 // Return the offset of the first non-reserved PLT entry.
1538
1539 unsigned int
first_plt_entry_offset() const1540 Target_i386::first_plt_entry_offset() const
1541 {
1542 return this->plt_->first_plt_entry_offset();
1543 }
1544
1545 // Return the size of each PLT entry.
1546
1547 unsigned int
plt_entry_size() const1548 Target_i386::plt_entry_size() const
1549 {
1550 return this->plt_->get_plt_entry_size();
1551 }
1552
1553 // Get the section to use for TLS_DESC relocations.
1554
1555 Target_i386::Reloc_section*
rel_tls_desc_section(Layout * layout) const1556 Target_i386::rel_tls_desc_section(Layout* layout) const
1557 {
1558 return this->plt_section()->rel_tls_desc(layout);
1559 }
1560
1561 // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
1562
1563 void
define_tls_base_symbol(Symbol_table * symtab,Layout * layout)1564 Target_i386::define_tls_base_symbol(Symbol_table* symtab, Layout* layout)
1565 {
1566 if (this->tls_base_symbol_defined_)
1567 return;
1568
1569 Output_segment* tls_segment = layout->tls_segment();
1570 if (tls_segment != NULL)
1571 {
1572 bool is_exec = parameters->options().output_is_executable();
1573 symtab->define_in_output_segment("_TLS_MODULE_BASE_", NULL,
1574 Symbol_table::PREDEFINED,
1575 tls_segment, 0, 0,
1576 elfcpp::STT_TLS,
1577 elfcpp::STB_LOCAL,
1578 elfcpp::STV_HIDDEN, 0,
1579 (is_exec
1580 ? Symbol::SEGMENT_END
1581 : Symbol::SEGMENT_START),
1582 true);
1583 }
1584 this->tls_base_symbol_defined_ = true;
1585 }
1586
1587 // Create a GOT entry for the TLS module index.
1588
1589 unsigned int
got_mod_index_entry(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * object)1590 Target_i386::got_mod_index_entry(Symbol_table* symtab, Layout* layout,
1591 Sized_relobj_file<32, false>* object)
1592 {
1593 if (this->got_mod_index_offset_ == -1U)
1594 {
1595 gold_assert(symtab != NULL && layout != NULL && object != NULL);
1596 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1597 Output_data_got<32, false>* got = this->got_section(symtab, layout);
1598 unsigned int got_offset = got->add_constant(0);
1599 rel_dyn->add_local(object, 0, elfcpp::R_386_TLS_DTPMOD32, got,
1600 got_offset);
1601 got->add_constant(0);
1602 this->got_mod_index_offset_ = got_offset;
1603 }
1604 return this->got_mod_index_offset_;
1605 }
1606
1607 // Optimize the TLS relocation type based on what we know about the
1608 // symbol. IS_FINAL is true if the final address of this symbol is
1609 // known at link time.
1610
1611 tls::Tls_optimization
optimize_tls_reloc(bool is_final,int r_type)1612 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
1613 {
1614 // If we are generating a shared library, then we can't do anything
1615 // in the linker.
1616 if (parameters->options().shared())
1617 return tls::TLSOPT_NONE;
1618
1619 switch (r_type)
1620 {
1621 case elfcpp::R_386_TLS_GD:
1622 case elfcpp::R_386_TLS_GOTDESC:
1623 case elfcpp::R_386_TLS_DESC_CALL:
1624 // These are General-Dynamic which permits fully general TLS
1625 // access. Since we know that we are generating an executable,
1626 // we can convert this to Initial-Exec. If we also know that
1627 // this is a local symbol, we can further switch to Local-Exec.
1628 if (is_final)
1629 return tls::TLSOPT_TO_LE;
1630 return tls::TLSOPT_TO_IE;
1631
1632 case elfcpp::R_386_TLS_LDM:
1633 // This is Local-Dynamic, which refers to a local symbol in the
1634 // dynamic TLS block. Since we know that we generating an
1635 // executable, we can switch to Local-Exec.
1636 return tls::TLSOPT_TO_LE;
1637
1638 case elfcpp::R_386_TLS_LDO_32:
1639 // Another type of Local-Dynamic relocation.
1640 return tls::TLSOPT_TO_LE;
1641
1642 case elfcpp::R_386_TLS_IE:
1643 case elfcpp::R_386_TLS_GOTIE:
1644 case elfcpp::R_386_TLS_IE_32:
1645 // These are Initial-Exec relocs which get the thread offset
1646 // from the GOT. If we know that we are linking against the
1647 // local symbol, we can switch to Local-Exec, which links the
1648 // thread offset into the instruction.
1649 if (is_final)
1650 return tls::TLSOPT_TO_LE;
1651 return tls::TLSOPT_NONE;
1652
1653 case elfcpp::R_386_TLS_LE:
1654 case elfcpp::R_386_TLS_LE_32:
1655 // When we already have Local-Exec, there is nothing further we
1656 // can do.
1657 return tls::TLSOPT_NONE;
1658
1659 default:
1660 gold_unreachable();
1661 }
1662 }
1663
1664 // Get the Reference_flags for a particular relocation.
1665
1666 int
get_reference_flags(unsigned int r_type)1667 Target_i386::Scan::get_reference_flags(unsigned int r_type)
1668 {
1669 switch (r_type)
1670 {
1671 case elfcpp::R_386_NONE:
1672 case elfcpp::R_386_GNU_VTINHERIT:
1673 case elfcpp::R_386_GNU_VTENTRY:
1674 case elfcpp::R_386_GOTPC:
1675 // No symbol reference.
1676 return 0;
1677
1678 case elfcpp::R_386_32:
1679 case elfcpp::R_386_16:
1680 case elfcpp::R_386_8:
1681 return Symbol::ABSOLUTE_REF;
1682
1683 case elfcpp::R_386_PC32:
1684 case elfcpp::R_386_PC16:
1685 case elfcpp::R_386_PC8:
1686 case elfcpp::R_386_GOTOFF:
1687 return Symbol::RELATIVE_REF;
1688
1689 case elfcpp::R_386_PLT32:
1690 return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF;
1691
1692 case elfcpp::R_386_GOT32:
1693 // Absolute in GOT.
1694 return Symbol::ABSOLUTE_REF;
1695
1696 case elfcpp::R_386_TLS_GD: // Global-dynamic
1697 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1698 case elfcpp::R_386_TLS_DESC_CALL:
1699 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1700 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1701 case elfcpp::R_386_TLS_IE: // Initial-exec
1702 case elfcpp::R_386_TLS_IE_32:
1703 case elfcpp::R_386_TLS_GOTIE:
1704 case elfcpp::R_386_TLS_LE: // Local-exec
1705 case elfcpp::R_386_TLS_LE_32:
1706 return Symbol::TLS_REF;
1707
1708 case elfcpp::R_386_COPY:
1709 case elfcpp::R_386_GLOB_DAT:
1710 case elfcpp::R_386_JUMP_SLOT:
1711 case elfcpp::R_386_RELATIVE:
1712 case elfcpp::R_386_IRELATIVE:
1713 case elfcpp::R_386_TLS_TPOFF:
1714 case elfcpp::R_386_TLS_DTPMOD32:
1715 case elfcpp::R_386_TLS_DTPOFF32:
1716 case elfcpp::R_386_TLS_TPOFF32:
1717 case elfcpp::R_386_TLS_DESC:
1718 case elfcpp::R_386_32PLT:
1719 case elfcpp::R_386_TLS_GD_32:
1720 case elfcpp::R_386_TLS_GD_PUSH:
1721 case elfcpp::R_386_TLS_GD_CALL:
1722 case elfcpp::R_386_TLS_GD_POP:
1723 case elfcpp::R_386_TLS_LDM_32:
1724 case elfcpp::R_386_TLS_LDM_PUSH:
1725 case elfcpp::R_386_TLS_LDM_CALL:
1726 case elfcpp::R_386_TLS_LDM_POP:
1727 case elfcpp::R_386_USED_BY_INTEL_200:
1728 default:
1729 // Not expected. We will give an error later.
1730 return 0;
1731 }
1732 }
1733
1734 // Report an unsupported relocation against a local symbol.
1735
1736 void
unsupported_reloc_local(Sized_relobj_file<32,false> * object,unsigned int r_type)1737 Target_i386::Scan::unsupported_reloc_local(Sized_relobj_file<32, false>* object,
1738 unsigned int r_type)
1739 {
1740 gold_error(_("%s: unsupported reloc %u against local symbol"),
1741 object->name().c_str(), r_type);
1742 }
1743
1744 // Return whether we need to make a PLT entry for a relocation of a
1745 // given type against a STT_GNU_IFUNC symbol.
1746
1747 bool
reloc_needs_plt_for_ifunc(Sized_relobj_file<32,false> * object,unsigned int r_type)1748 Target_i386::Scan::reloc_needs_plt_for_ifunc(
1749 Sized_relobj_file<32, false>* object,
1750 unsigned int r_type)
1751 {
1752 int flags = Scan::get_reference_flags(r_type);
1753 if (flags & Symbol::TLS_REF)
1754 gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"),
1755 object->name().c_str(), r_type);
1756 return flags != 0;
1757 }
1758
1759 // Scan a relocation for a local symbol.
1760
1761 inline void
local(Symbol_table * symtab,Layout * layout,Target_i386 * target,Sized_relobj_file<32,false> * object,unsigned int data_shndx,Output_section * output_section,const elfcpp::Rel<32,false> & reloc,unsigned int r_type,const elfcpp::Sym<32,false> & lsym,bool is_discarded)1762 Target_i386::Scan::local(Symbol_table* symtab,
1763 Layout* layout,
1764 Target_i386* target,
1765 Sized_relobj_file<32, false>* object,
1766 unsigned int data_shndx,
1767 Output_section* output_section,
1768 const elfcpp::Rel<32, false>& reloc,
1769 unsigned int r_type,
1770 const elfcpp::Sym<32, false>& lsym,
1771 bool is_discarded)
1772 {
1773 if (is_discarded)
1774 return;
1775
1776 // A local STT_GNU_IFUNC symbol may require a PLT entry.
1777 if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC
1778 && this->reloc_needs_plt_for_ifunc(object, r_type))
1779 {
1780 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1781 target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym);
1782 }
1783
1784 switch (r_type)
1785 {
1786 case elfcpp::R_386_NONE:
1787 case elfcpp::R_386_GNU_VTINHERIT:
1788 case elfcpp::R_386_GNU_VTENTRY:
1789 break;
1790
1791 case elfcpp::R_386_32:
1792 // If building a shared library (or a position-independent
1793 // executable), we need to create a dynamic relocation for
1794 // this location. The relocation applied at link time will
1795 // apply the link-time value, so we flag the location with
1796 // an R_386_RELATIVE relocation so the dynamic loader can
1797 // relocate it easily.
1798 if (parameters->options().output_is_position_independent())
1799 {
1800 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1801 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1802 rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE,
1803 output_section, data_shndx,
1804 reloc.get_r_offset());
1805 }
1806 break;
1807
1808 case elfcpp::R_386_16:
1809 case elfcpp::R_386_8:
1810 // If building a shared library (or a position-independent
1811 // executable), we need to create a dynamic relocation for
1812 // this location. Because the addend needs to remain in the
1813 // data section, we need to be careful not to apply this
1814 // relocation statically.
1815 if (parameters->options().output_is_position_independent())
1816 {
1817 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1818 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1819 if (lsym.get_st_type() != elfcpp::STT_SECTION)
1820 rel_dyn->add_local(object, r_sym, r_type, output_section,
1821 data_shndx, reloc.get_r_offset());
1822 else
1823 {
1824 gold_assert(lsym.get_st_value() == 0);
1825 unsigned int shndx = lsym.get_st_shndx();
1826 bool is_ordinary;
1827 shndx = object->adjust_sym_shndx(r_sym, shndx,
1828 &is_ordinary);
1829 if (!is_ordinary)
1830 object->error(_("section symbol %u has bad shndx %u"),
1831 r_sym, shndx);
1832 else
1833 rel_dyn->add_local_section(object, shndx,
1834 r_type, output_section,
1835 data_shndx, reloc.get_r_offset());
1836 }
1837 }
1838 break;
1839
1840 case elfcpp::R_386_PC32:
1841 case elfcpp::R_386_PC16:
1842 case elfcpp::R_386_PC8:
1843 break;
1844
1845 case elfcpp::R_386_PLT32:
1846 // Since we know this is a local symbol, we can handle this as a
1847 // PC32 reloc.
1848 break;
1849
1850 case elfcpp::R_386_GOTOFF:
1851 case elfcpp::R_386_GOTPC:
1852 // We need a GOT section.
1853 target->got_section(symtab, layout);
1854 break;
1855
1856 case elfcpp::R_386_GOT32:
1857 {
1858 // We need GOT section.
1859 Output_data_got<32, false>* got = target->got_section(symtab, layout);
1860
1861 // If the relocation symbol isn't IFUNC,
1862 // and is local, then we will convert
1863 // mov foo@GOT(%reg), %reg
1864 // to
1865 // lea foo@GOTOFF(%reg), %reg
1866 // in Relocate::relocate.
1867 if (reloc.get_r_offset() >= 2
1868 && lsym.get_st_type() != elfcpp::STT_GNU_IFUNC)
1869 {
1870 section_size_type stype;
1871 const unsigned char* view = object->section_contents(data_shndx,
1872 &stype, true);
1873 if (view[reloc.get_r_offset() - 2] == 0x8b)
1874 break;
1875 }
1876
1877 // Otherwise, the symbol requires a GOT entry.
1878 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1879
1880 // For a STT_GNU_IFUNC symbol we want the PLT offset. That
1881 // lets function pointers compare correctly with shared
1882 // libraries. Otherwise we would need an IRELATIVE reloc.
1883 bool is_new;
1884 if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC)
1885 is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD);
1886 else
1887 is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD);
1888 if (is_new)
1889 {
1890 // If we are generating a shared object, we need to add a
1891 // dynamic RELATIVE relocation for this symbol's GOT entry.
1892 if (parameters->options().output_is_position_independent())
1893 {
1894 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1895 unsigned int got_offset =
1896 object->local_got_offset(r_sym, GOT_TYPE_STANDARD);
1897 rel_dyn->add_local_relative(object, r_sym,
1898 elfcpp::R_386_RELATIVE,
1899 got, got_offset);
1900 }
1901 }
1902 }
1903 break;
1904
1905 // These are relocations which should only be seen by the
1906 // dynamic linker, and should never be seen here.
1907 case elfcpp::R_386_COPY:
1908 case elfcpp::R_386_GLOB_DAT:
1909 case elfcpp::R_386_JUMP_SLOT:
1910 case elfcpp::R_386_RELATIVE:
1911 case elfcpp::R_386_IRELATIVE:
1912 case elfcpp::R_386_TLS_TPOFF:
1913 case elfcpp::R_386_TLS_DTPMOD32:
1914 case elfcpp::R_386_TLS_DTPOFF32:
1915 case elfcpp::R_386_TLS_TPOFF32:
1916 case elfcpp::R_386_TLS_DESC:
1917 gold_error(_("%s: unexpected reloc %u in object file"),
1918 object->name().c_str(), r_type);
1919 break;
1920
1921 // These are initial TLS relocs, which are expected when
1922 // linking.
1923 case elfcpp::R_386_TLS_GD: // Global-dynamic
1924 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1925 case elfcpp::R_386_TLS_DESC_CALL:
1926 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1927 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1928 case elfcpp::R_386_TLS_IE: // Initial-exec
1929 case elfcpp::R_386_TLS_IE_32:
1930 case elfcpp::R_386_TLS_GOTIE:
1931 case elfcpp::R_386_TLS_LE: // Local-exec
1932 case elfcpp::R_386_TLS_LE_32:
1933 {
1934 bool output_is_shared = parameters->options().shared();
1935 const tls::Tls_optimization optimized_type
1936 = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
1937 switch (r_type)
1938 {
1939 case elfcpp::R_386_TLS_GD: // Global-dynamic
1940 if (optimized_type == tls::TLSOPT_NONE)
1941 {
1942 // Create a pair of GOT entries for the module index and
1943 // dtv-relative offset.
1944 Output_data_got<32, false>* got
1945 = target->got_section(symtab, layout);
1946 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1947 unsigned int shndx = lsym.get_st_shndx();
1948 bool is_ordinary;
1949 shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
1950 if (!is_ordinary)
1951 object->error(_("local symbol %u has bad shndx %u"),
1952 r_sym, shndx);
1953 else
1954 got->add_local_pair_with_rel(object, r_sym, shndx,
1955 GOT_TYPE_TLS_PAIR,
1956 target->rel_dyn_section(layout),
1957 elfcpp::R_386_TLS_DTPMOD32);
1958 }
1959 else if (optimized_type != tls::TLSOPT_TO_LE)
1960 unsupported_reloc_local(object, r_type);
1961 break;
1962
1963 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva)
1964 target->define_tls_base_symbol(symtab, layout);
1965 if (optimized_type == tls::TLSOPT_NONE)
1966 {
1967 // Create a double GOT entry with an R_386_TLS_DESC
1968 // reloc. The R_386_TLS_DESC reloc is resolved
1969 // lazily, so the GOT entry needs to be in an area in
1970 // .got.plt, not .got. Call got_section to make sure
1971 // the section has been created.
1972 target->got_section(symtab, layout);
1973 Output_data_got<32, false>* got = target->got_tlsdesc_section();
1974 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
1975 if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC))
1976 {
1977 unsigned int got_offset = got->add_constant(0);
1978 // The local symbol value is stored in the second
1979 // GOT entry.
1980 got->add_local(object, r_sym, GOT_TYPE_TLS_DESC);
1981 // That set the GOT offset of the local symbol to
1982 // point to the second entry, but we want it to
1983 // point to the first.
1984 object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC,
1985 got_offset);
1986 Reloc_section* rt = target->rel_tls_desc_section(layout);
1987 rt->add_absolute(elfcpp::R_386_TLS_DESC, got, got_offset);
1988 }
1989 }
1990 else if (optimized_type != tls::TLSOPT_TO_LE)
1991 unsupported_reloc_local(object, r_type);
1992 break;
1993
1994 case elfcpp::R_386_TLS_DESC_CALL:
1995 break;
1996
1997 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1998 if (optimized_type == tls::TLSOPT_NONE)
1999 {
2000 // Create a GOT entry for the module index.
2001 target->got_mod_index_entry(symtab, layout, object);
2002 }
2003 else if (optimized_type != tls::TLSOPT_TO_LE)
2004 unsupported_reloc_local(object, r_type);
2005 break;
2006
2007 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2008 break;
2009
2010 case elfcpp::R_386_TLS_IE: // Initial-exec
2011 case elfcpp::R_386_TLS_IE_32:
2012 case elfcpp::R_386_TLS_GOTIE:
2013 layout->set_has_static_tls();
2014 if (optimized_type == tls::TLSOPT_NONE)
2015 {
2016 // For the R_386_TLS_IE relocation, we need to create a
2017 // dynamic relocation when building a shared library.
2018 if (r_type == elfcpp::R_386_TLS_IE
2019 && parameters->options().shared())
2020 {
2021 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2022 unsigned int r_sym
2023 = elfcpp::elf_r_sym<32>(reloc.get_r_info());
2024 rel_dyn->add_local_relative(object, r_sym,
2025 elfcpp::R_386_RELATIVE,
2026 output_section, data_shndx,
2027 reloc.get_r_offset());
2028 }
2029 // Create a GOT entry for the tp-relative offset.
2030 Output_data_got<32, false>* got
2031 = target->got_section(symtab, layout);
2032 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
2033 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
2034 ? elfcpp::R_386_TLS_TPOFF32
2035 : elfcpp::R_386_TLS_TPOFF);
2036 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
2037 ? GOT_TYPE_TLS_OFFSET
2038 : GOT_TYPE_TLS_NOFFSET);
2039 got->add_local_with_rel(object, r_sym, got_type,
2040 target->rel_dyn_section(layout),
2041 dyn_r_type);
2042 }
2043 else if (optimized_type != tls::TLSOPT_TO_LE)
2044 unsupported_reloc_local(object, r_type);
2045 break;
2046
2047 case elfcpp::R_386_TLS_LE: // Local-exec
2048 case elfcpp::R_386_TLS_LE_32:
2049 layout->set_has_static_tls();
2050 if (output_is_shared)
2051 {
2052 // We need to create a dynamic relocation.
2053 gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION);
2054 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
2055 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
2056 ? elfcpp::R_386_TLS_TPOFF32
2057 : elfcpp::R_386_TLS_TPOFF);
2058 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2059 rel_dyn->add_local(object, r_sym, dyn_r_type, output_section,
2060 data_shndx, reloc.get_r_offset());
2061 }
2062 break;
2063
2064 default:
2065 gold_unreachable();
2066 }
2067 }
2068 break;
2069
2070 case elfcpp::R_386_32PLT:
2071 case elfcpp::R_386_TLS_GD_32:
2072 case elfcpp::R_386_TLS_GD_PUSH:
2073 case elfcpp::R_386_TLS_GD_CALL:
2074 case elfcpp::R_386_TLS_GD_POP:
2075 case elfcpp::R_386_TLS_LDM_32:
2076 case elfcpp::R_386_TLS_LDM_PUSH:
2077 case elfcpp::R_386_TLS_LDM_CALL:
2078 case elfcpp::R_386_TLS_LDM_POP:
2079 case elfcpp::R_386_USED_BY_INTEL_200:
2080 default:
2081 unsupported_reloc_local(object, r_type);
2082 break;
2083 }
2084 }
2085
2086 // Report an unsupported relocation against a global symbol.
2087
2088 void
unsupported_reloc_global(Sized_relobj_file<32,false> * object,unsigned int r_type,Symbol * gsym)2089 Target_i386::Scan::unsupported_reloc_global(
2090 Sized_relobj_file<32, false>* object,
2091 unsigned int r_type,
2092 Symbol* gsym)
2093 {
2094 gold_error(_("%s: unsupported reloc %u against global symbol %s"),
2095 object->name().c_str(), r_type, gsym->demangled_name().c_str());
2096 }
2097
2098 inline bool
possible_function_pointer_reloc(unsigned int r_type)2099 Target_i386::Scan::possible_function_pointer_reloc(unsigned int r_type)
2100 {
2101 switch (r_type)
2102 {
2103 case elfcpp::R_386_32:
2104 case elfcpp::R_386_16:
2105 case elfcpp::R_386_8:
2106 case elfcpp::R_386_GOTOFF:
2107 case elfcpp::R_386_GOT32:
2108 {
2109 return true;
2110 }
2111 default:
2112 return false;
2113 }
2114 return false;
2115 }
2116
2117 inline bool
local_reloc_may_be_function_pointer(Symbol_table *,Layout *,Target_i386 *,Sized_relobj_file<32,false> *,unsigned int,Output_section *,const elfcpp::Rel<32,false> &,unsigned int r_type,const elfcpp::Sym<32,false> &)2118 Target_i386::Scan::local_reloc_may_be_function_pointer(
2119 Symbol_table* ,
2120 Layout* ,
2121 Target_i386* ,
2122 Sized_relobj_file<32, false>* ,
2123 unsigned int ,
2124 Output_section* ,
2125 const elfcpp::Rel<32, false>& ,
2126 unsigned int r_type,
2127 const elfcpp::Sym<32, false>&)
2128 {
2129 return possible_function_pointer_reloc(r_type);
2130 }
2131
2132 inline bool
global_reloc_may_be_function_pointer(Symbol_table *,Layout *,Target_i386 *,Sized_relobj_file<32,false> *,unsigned int,Output_section *,const elfcpp::Rel<32,false> &,unsigned int r_type,Symbol *)2133 Target_i386::Scan::global_reloc_may_be_function_pointer(
2134 Symbol_table* ,
2135 Layout* ,
2136 Target_i386* ,
2137 Sized_relobj_file<32, false>* ,
2138 unsigned int ,
2139 Output_section* ,
2140 const elfcpp::Rel<32, false>& ,
2141 unsigned int r_type,
2142 Symbol*)
2143 {
2144 return possible_function_pointer_reloc(r_type);
2145 }
2146
2147 // Scan a relocation for a global symbol.
2148
2149 inline void
global(Symbol_table * symtab,Layout * layout,Target_i386 * target,Sized_relobj_file<32,false> * object,unsigned int data_shndx,Output_section * output_section,const elfcpp::Rel<32,false> & reloc,unsigned int r_type,Symbol * gsym)2150 Target_i386::Scan::global(Symbol_table* symtab,
2151 Layout* layout,
2152 Target_i386* target,
2153 Sized_relobj_file<32, false>* object,
2154 unsigned int data_shndx,
2155 Output_section* output_section,
2156 const elfcpp::Rel<32, false>& reloc,
2157 unsigned int r_type,
2158 Symbol* gsym)
2159 {
2160 // A STT_GNU_IFUNC symbol may require a PLT entry.
2161 if (gsym->type() == elfcpp::STT_GNU_IFUNC
2162 && this->reloc_needs_plt_for_ifunc(object, r_type))
2163 target->make_plt_entry(symtab, layout, gsym);
2164
2165 switch (r_type)
2166 {
2167 case elfcpp::R_386_NONE:
2168 case elfcpp::R_386_GNU_VTINHERIT:
2169 case elfcpp::R_386_GNU_VTENTRY:
2170 break;
2171
2172 case elfcpp::R_386_32:
2173 case elfcpp::R_386_16:
2174 case elfcpp::R_386_8:
2175 {
2176 // Make a PLT entry if necessary.
2177 if (gsym->needs_plt_entry())
2178 {
2179 target->make_plt_entry(symtab, layout, gsym);
2180 // Since this is not a PC-relative relocation, we may be
2181 // taking the address of a function. In that case we need to
2182 // set the entry in the dynamic symbol table to the address of
2183 // the PLT entry.
2184 if (gsym->is_from_dynobj() && !parameters->options().shared())
2185 gsym->set_needs_dynsym_value();
2186 }
2187 // Make a dynamic relocation if necessary.
2188 if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
2189 {
2190 if (!parameters->options().output_is_position_independent()
2191 && gsym->may_need_copy_reloc())
2192 {
2193 target->copy_reloc(symtab, layout, object,
2194 data_shndx, output_section, gsym, reloc);
2195 }
2196 else if (r_type == elfcpp::R_386_32
2197 && gsym->type() == elfcpp::STT_GNU_IFUNC
2198 && gsym->can_use_relative_reloc(false)
2199 && !gsym->is_from_dynobj()
2200 && !gsym->is_undefined()
2201 && !gsym->is_preemptible())
2202 {
2203 // Use an IRELATIVE reloc for a locally defined
2204 // STT_GNU_IFUNC symbol. This makes a function
2205 // address in a PIE executable match the address in a
2206 // shared library that it links against.
2207 Reloc_section* rel_dyn = target->rel_irelative_section(layout);
2208 rel_dyn->add_symbolless_global_addend(gsym,
2209 elfcpp::R_386_IRELATIVE,
2210 output_section,
2211 object, data_shndx,
2212 reloc.get_r_offset());
2213 }
2214 else if (r_type == elfcpp::R_386_32
2215 && gsym->can_use_relative_reloc(false))
2216 {
2217 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2218 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2219 output_section, object,
2220 data_shndx, reloc.get_r_offset());
2221 }
2222 else
2223 {
2224 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2225 rel_dyn->add_global(gsym, r_type, output_section, object,
2226 data_shndx, reloc.get_r_offset());
2227 }
2228 }
2229 }
2230 break;
2231
2232 case elfcpp::R_386_PC32:
2233 case elfcpp::R_386_PC16:
2234 case elfcpp::R_386_PC8:
2235 {
2236 // Make a PLT entry if necessary.
2237 if (gsym->needs_plt_entry())
2238 {
2239 // These relocations are used for function calls only in
2240 // non-PIC code. For a 32-bit relocation in a shared library,
2241 // we'll need a text relocation anyway, so we can skip the
2242 // PLT entry and let the dynamic linker bind the call directly
2243 // to the target. For smaller relocations, we should use a
2244 // PLT entry to ensure that the call can reach.
2245 if (!parameters->options().shared()
2246 || r_type != elfcpp::R_386_PC32)
2247 target->make_plt_entry(symtab, layout, gsym);
2248 }
2249 // Make a dynamic relocation if necessary.
2250 if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
2251 {
2252 if (parameters->options().output_is_executable()
2253 && gsym->may_need_copy_reloc())
2254 {
2255 target->copy_reloc(symtab, layout, object,
2256 data_shndx, output_section, gsym, reloc);
2257 }
2258 else
2259 {
2260 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2261 rel_dyn->add_global(gsym, r_type, output_section, object,
2262 data_shndx, reloc.get_r_offset());
2263 }
2264 }
2265 }
2266 break;
2267
2268 case elfcpp::R_386_GOT32:
2269 {
2270 // The symbol requires a GOT section.
2271 Output_data_got<32, false>* got = target->got_section(symtab, layout);
2272
2273 // If we convert this from
2274 // mov foo@GOT(%reg), %reg
2275 // to
2276 // lea foo@GOTOFF(%reg), %reg
2277 // in Relocate::relocate, then there is nothing to do here.
2278 if (reloc.get_r_offset() >= 2
2279 && Target_i386::can_convert_mov_to_lea(gsym))
2280 {
2281 section_size_type stype;
2282 const unsigned char* view = object->section_contents(data_shndx,
2283 &stype, true);
2284 if (view[reloc.get_r_offset() - 2] == 0x8b)
2285 break;
2286 }
2287
2288 if (gsym->final_value_is_known())
2289 {
2290 // For a STT_GNU_IFUNC symbol we want the PLT address.
2291 if (gsym->type() == elfcpp::STT_GNU_IFUNC)
2292 got->add_global_plt(gsym, GOT_TYPE_STANDARD);
2293 else
2294 got->add_global(gsym, GOT_TYPE_STANDARD);
2295 }
2296 else
2297 {
2298 // If this symbol is not fully resolved, we need to add a
2299 // GOT entry with a dynamic relocation.
2300 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2301
2302 // Use a GLOB_DAT rather than a RELATIVE reloc if:
2303 //
2304 // 1) The symbol may be defined in some other module.
2305 //
2306 // 2) We are building a shared library and this is a
2307 // protected symbol; using GLOB_DAT means that the dynamic
2308 // linker can use the address of the PLT in the main
2309 // executable when appropriate so that function address
2310 // comparisons work.
2311 //
2312 // 3) This is a STT_GNU_IFUNC symbol in position dependent
2313 // code, again so that function address comparisons work.
2314 if (gsym->is_from_dynobj()
2315 || gsym->is_undefined()
2316 || gsym->is_preemptible()
2317 || (gsym->visibility() == elfcpp::STV_PROTECTED
2318 && parameters->options().shared())
2319 || (gsym->type() == elfcpp::STT_GNU_IFUNC
2320 && parameters->options().output_is_position_independent()))
2321 got->add_global_with_rel(gsym, GOT_TYPE_STANDARD,
2322 rel_dyn, elfcpp::R_386_GLOB_DAT);
2323 else
2324 {
2325 // For a STT_GNU_IFUNC symbol we want to write the PLT
2326 // offset into the GOT, so that function pointer
2327 // comparisons work correctly.
2328 bool is_new;
2329 if (gsym->type() != elfcpp::STT_GNU_IFUNC)
2330 is_new = got->add_global(gsym, GOT_TYPE_STANDARD);
2331 else
2332 {
2333 is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD);
2334 // Tell the dynamic linker to use the PLT address
2335 // when resolving relocations.
2336 if (gsym->is_from_dynobj()
2337 && !parameters->options().shared())
2338 gsym->set_needs_dynsym_value();
2339 }
2340 if (is_new)
2341 {
2342 unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD);
2343 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2344 got, got_off);
2345 }
2346 }
2347 }
2348 }
2349 break;
2350
2351 case elfcpp::R_386_PLT32:
2352 // If the symbol is fully resolved, this is just a PC32 reloc.
2353 // Otherwise we need a PLT entry.
2354 if (gsym->final_value_is_known())
2355 break;
2356 // If building a shared library, we can also skip the PLT entry
2357 // if the symbol is defined in the output file and is protected
2358 // or hidden.
2359 if (gsym->is_defined()
2360 && !gsym->is_from_dynobj()
2361 && !gsym->is_preemptible())
2362 break;
2363 target->make_plt_entry(symtab, layout, gsym);
2364 break;
2365
2366 case elfcpp::R_386_GOTOFF:
2367 case elfcpp::R_386_GOTPC:
2368 // We need a GOT section.
2369 target->got_section(symtab, layout);
2370 break;
2371
2372 // These are relocations which should only be seen by the
2373 // dynamic linker, and should never be seen here.
2374 case elfcpp::R_386_COPY:
2375 case elfcpp::R_386_GLOB_DAT:
2376 case elfcpp::R_386_JUMP_SLOT:
2377 case elfcpp::R_386_RELATIVE:
2378 case elfcpp::R_386_IRELATIVE:
2379 case elfcpp::R_386_TLS_TPOFF:
2380 case elfcpp::R_386_TLS_DTPMOD32:
2381 case elfcpp::R_386_TLS_DTPOFF32:
2382 case elfcpp::R_386_TLS_TPOFF32:
2383 case elfcpp::R_386_TLS_DESC:
2384 gold_error(_("%s: unexpected reloc %u in object file"),
2385 object->name().c_str(), r_type);
2386 break;
2387
2388 // These are initial tls relocs, which are expected when
2389 // linking.
2390 case elfcpp::R_386_TLS_GD: // Global-dynamic
2391 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2392 case elfcpp::R_386_TLS_DESC_CALL:
2393 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2394 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2395 case elfcpp::R_386_TLS_IE: // Initial-exec
2396 case elfcpp::R_386_TLS_IE_32:
2397 case elfcpp::R_386_TLS_GOTIE:
2398 case elfcpp::R_386_TLS_LE: // Local-exec
2399 case elfcpp::R_386_TLS_LE_32:
2400 {
2401 const bool is_final = gsym->final_value_is_known();
2402 const tls::Tls_optimization optimized_type
2403 = Target_i386::optimize_tls_reloc(is_final, r_type);
2404 switch (r_type)
2405 {
2406 case elfcpp::R_386_TLS_GD: // Global-dynamic
2407 if (optimized_type == tls::TLSOPT_NONE)
2408 {
2409 // Create a pair of GOT entries for the module index and
2410 // dtv-relative offset.
2411 Output_data_got<32, false>* got
2412 = target->got_section(symtab, layout);
2413 got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR,
2414 target->rel_dyn_section(layout),
2415 elfcpp::R_386_TLS_DTPMOD32,
2416 elfcpp::R_386_TLS_DTPOFF32);
2417 }
2418 else if (optimized_type == tls::TLSOPT_TO_IE)
2419 {
2420 // Create a GOT entry for the tp-relative offset.
2421 Output_data_got<32, false>* got
2422 = target->got_section(symtab, layout);
2423 got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
2424 target->rel_dyn_section(layout),
2425 elfcpp::R_386_TLS_TPOFF);
2426 }
2427 else if (optimized_type != tls::TLSOPT_TO_LE)
2428 unsupported_reloc_global(object, r_type, gsym);
2429 break;
2430
2431 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url)
2432 target->define_tls_base_symbol(symtab, layout);
2433 if (optimized_type == tls::TLSOPT_NONE)
2434 {
2435 // Create a double GOT entry with an R_386_TLS_DESC
2436 // reloc. The R_386_TLS_DESC reloc is resolved
2437 // lazily, so the GOT entry needs to be in an area in
2438 // .got.plt, not .got. Call got_section to make sure
2439 // the section has been created.
2440 target->got_section(symtab, layout);
2441 Output_data_got<32, false>* got = target->got_tlsdesc_section();
2442 Reloc_section* rt = target->rel_tls_desc_section(layout);
2443 got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt,
2444 elfcpp::R_386_TLS_DESC, 0);
2445 }
2446 else if (optimized_type == tls::TLSOPT_TO_IE)
2447 {
2448 // Create a GOT entry for the tp-relative offset.
2449 Output_data_got<32, false>* got
2450 = target->got_section(symtab, layout);
2451 got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
2452 target->rel_dyn_section(layout),
2453 elfcpp::R_386_TLS_TPOFF);
2454 }
2455 else if (optimized_type != tls::TLSOPT_TO_LE)
2456 unsupported_reloc_global(object, r_type, gsym);
2457 break;
2458
2459 case elfcpp::R_386_TLS_DESC_CALL:
2460 break;
2461
2462 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2463 if (optimized_type == tls::TLSOPT_NONE)
2464 {
2465 // Create a GOT entry for the module index.
2466 target->got_mod_index_entry(symtab, layout, object);
2467 }
2468 else if (optimized_type != tls::TLSOPT_TO_LE)
2469 unsupported_reloc_global(object, r_type, gsym);
2470 break;
2471
2472 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2473 break;
2474
2475 case elfcpp::R_386_TLS_IE: // Initial-exec
2476 case elfcpp::R_386_TLS_IE_32:
2477 case elfcpp::R_386_TLS_GOTIE:
2478 layout->set_has_static_tls();
2479 if (optimized_type == tls::TLSOPT_NONE)
2480 {
2481 // For the R_386_TLS_IE relocation, we need to create a
2482 // dynamic relocation when building a shared library.
2483 if (r_type == elfcpp::R_386_TLS_IE
2484 && parameters->options().shared())
2485 {
2486 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2487 rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
2488 output_section, object,
2489 data_shndx,
2490 reloc.get_r_offset());
2491 }
2492 // Create a GOT entry for the tp-relative offset.
2493 Output_data_got<32, false>* got
2494 = target->got_section(symtab, layout);
2495 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
2496 ? elfcpp::R_386_TLS_TPOFF32
2497 : elfcpp::R_386_TLS_TPOFF);
2498 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
2499 ? GOT_TYPE_TLS_OFFSET
2500 : GOT_TYPE_TLS_NOFFSET);
2501 got->add_global_with_rel(gsym, got_type,
2502 target->rel_dyn_section(layout),
2503 dyn_r_type);
2504 }
2505 else if (optimized_type != tls::TLSOPT_TO_LE)
2506 unsupported_reloc_global(object, r_type, gsym);
2507 break;
2508
2509 case elfcpp::R_386_TLS_LE: // Local-exec
2510 case elfcpp::R_386_TLS_LE_32:
2511 layout->set_has_static_tls();
2512 if (parameters->options().shared())
2513 {
2514 // We need to create a dynamic relocation.
2515 unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
2516 ? elfcpp::R_386_TLS_TPOFF32
2517 : elfcpp::R_386_TLS_TPOFF);
2518 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
2519 rel_dyn->add_global(gsym, dyn_r_type, output_section, object,
2520 data_shndx, reloc.get_r_offset());
2521 }
2522 break;
2523
2524 default:
2525 gold_unreachable();
2526 }
2527 }
2528 break;
2529
2530 case elfcpp::R_386_32PLT:
2531 case elfcpp::R_386_TLS_GD_32:
2532 case elfcpp::R_386_TLS_GD_PUSH:
2533 case elfcpp::R_386_TLS_GD_CALL:
2534 case elfcpp::R_386_TLS_GD_POP:
2535 case elfcpp::R_386_TLS_LDM_32:
2536 case elfcpp::R_386_TLS_LDM_PUSH:
2537 case elfcpp::R_386_TLS_LDM_CALL:
2538 case elfcpp::R_386_TLS_LDM_POP:
2539 case elfcpp::R_386_USED_BY_INTEL_200:
2540 default:
2541 unsupported_reloc_global(object, r_type, gsym);
2542 break;
2543 }
2544 }
2545
2546 // Process relocations for gc.
2547
2548 void
gc_process_relocs(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * object,unsigned int data_shndx,unsigned int,const unsigned char * prelocs,size_t reloc_count,Output_section * output_section,bool needs_special_offset_handling,size_t local_symbol_count,const unsigned char * plocal_symbols)2549 Target_i386::gc_process_relocs(Symbol_table* symtab,
2550 Layout* layout,
2551 Sized_relobj_file<32, false>* object,
2552 unsigned int data_shndx,
2553 unsigned int,
2554 const unsigned char* prelocs,
2555 size_t reloc_count,
2556 Output_section* output_section,
2557 bool needs_special_offset_handling,
2558 size_t local_symbol_count,
2559 const unsigned char* plocal_symbols)
2560 {
2561 gold::gc_process_relocs<32, false, Target_i386, elfcpp::SHT_REL,
2562 Target_i386::Scan,
2563 Target_i386::Relocatable_size_for_reloc>(
2564 symtab,
2565 layout,
2566 this,
2567 object,
2568 data_shndx,
2569 prelocs,
2570 reloc_count,
2571 output_section,
2572 needs_special_offset_handling,
2573 local_symbol_count,
2574 plocal_symbols);
2575 }
2576
2577 // Scan relocations for a section.
2578
2579 void
scan_relocs(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * object,unsigned int data_shndx,unsigned int sh_type,const unsigned char * prelocs,size_t reloc_count,Output_section * output_section,bool needs_special_offset_handling,size_t local_symbol_count,const unsigned char * plocal_symbols)2580 Target_i386::scan_relocs(Symbol_table* symtab,
2581 Layout* layout,
2582 Sized_relobj_file<32, false>* object,
2583 unsigned int data_shndx,
2584 unsigned int sh_type,
2585 const unsigned char* prelocs,
2586 size_t reloc_count,
2587 Output_section* output_section,
2588 bool needs_special_offset_handling,
2589 size_t local_symbol_count,
2590 const unsigned char* plocal_symbols)
2591 {
2592 if (sh_type == elfcpp::SHT_RELA)
2593 {
2594 gold_error(_("%s: unsupported RELA reloc section"),
2595 object->name().c_str());
2596 return;
2597 }
2598
2599 gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
2600 Target_i386::Scan>(
2601 symtab,
2602 layout,
2603 this,
2604 object,
2605 data_shndx,
2606 prelocs,
2607 reloc_count,
2608 output_section,
2609 needs_special_offset_handling,
2610 local_symbol_count,
2611 plocal_symbols);
2612 }
2613
2614 // Finalize the sections.
2615
2616 void
do_finalize_sections(Layout * layout,const Input_objects *,Symbol_table * symtab)2617 Target_i386::do_finalize_sections(
2618 Layout* layout,
2619 const Input_objects*,
2620 Symbol_table* symtab)
2621 {
2622 const Reloc_section* rel_plt = (this->plt_ == NULL
2623 ? NULL
2624 : this->plt_->rel_plt());
2625 layout->add_target_dynamic_tags(true, this->got_plt_, rel_plt,
2626 this->rel_dyn_, true, false);
2627
2628 // Emit any relocs we saved in an attempt to avoid generating COPY
2629 // relocs.
2630 if (this->copy_relocs_.any_saved_relocs())
2631 this->copy_relocs_.emit(this->rel_dyn_section(layout));
2632
2633 // Set the size of the _GLOBAL_OFFSET_TABLE_ symbol to the size of
2634 // the .got.plt section.
2635 Symbol* sym = this->global_offset_table_;
2636 if (sym != NULL)
2637 {
2638 uint32_t data_size = this->got_plt_->current_data_size();
2639 symtab->get_sized_symbol<32>(sym)->set_symsize(data_size);
2640 }
2641
2642 if (parameters->doing_static_link()
2643 && (this->plt_ == NULL || !this->plt_->has_irelative_section()))
2644 {
2645 // If linking statically, make sure that the __rel_iplt symbols
2646 // were defined if necessary, even if we didn't create a PLT.
2647 static const Define_symbol_in_segment syms[] =
2648 {
2649 {
2650 "__rel_iplt_start", // name
2651 elfcpp::PT_LOAD, // segment_type
2652 elfcpp::PF_W, // segment_flags_set
2653 elfcpp::PF(0), // segment_flags_clear
2654 0, // value
2655 0, // size
2656 elfcpp::STT_NOTYPE, // type
2657 elfcpp::STB_GLOBAL, // binding
2658 elfcpp::STV_HIDDEN, // visibility
2659 0, // nonvis
2660 Symbol::SEGMENT_START, // offset_from_base
2661 true // only_if_ref
2662 },
2663 {
2664 "__rel_iplt_end", // name
2665 elfcpp::PT_LOAD, // segment_type
2666 elfcpp::PF_W, // segment_flags_set
2667 elfcpp::PF(0), // segment_flags_clear
2668 0, // value
2669 0, // size
2670 elfcpp::STT_NOTYPE, // type
2671 elfcpp::STB_GLOBAL, // binding
2672 elfcpp::STV_HIDDEN, // visibility
2673 0, // nonvis
2674 Symbol::SEGMENT_START, // offset_from_base
2675 true // only_if_ref
2676 }
2677 };
2678
2679 symtab->define_symbols(layout, 2, syms,
2680 layout->script_options()->saw_sections_clause());
2681 }
2682 }
2683
2684 // Return whether a direct absolute static relocation needs to be applied.
2685 // In cases where Scan::local() or Scan::global() has created
2686 // a dynamic relocation other than R_386_RELATIVE, the addend
2687 // of the relocation is carried in the data, and we must not
2688 // apply the static relocation.
2689
2690 inline bool
should_apply_static_reloc(const Sized_symbol<32> * gsym,unsigned int r_type,bool is_32bit,Output_section * output_section)2691 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
2692 unsigned int r_type,
2693 bool is_32bit,
2694 Output_section* output_section)
2695 {
2696 // If the output section is not allocated, then we didn't call
2697 // scan_relocs, we didn't create a dynamic reloc, and we must apply
2698 // the reloc here.
2699 if ((output_section->flags() & elfcpp::SHF_ALLOC) == 0)
2700 return true;
2701
2702 int ref_flags = Scan::get_reference_flags(r_type);
2703
2704 // For local symbols, we will have created a non-RELATIVE dynamic
2705 // relocation only if (a) the output is position independent,
2706 // (b) the relocation is absolute (not pc- or segment-relative), and
2707 // (c) the relocation is not 32 bits wide.
2708 if (gsym == NULL)
2709 return !(parameters->options().output_is_position_independent()
2710 && (ref_flags & Symbol::ABSOLUTE_REF)
2711 && !is_32bit);
2712
2713 // For global symbols, we use the same helper routines used in the
2714 // scan pass. If we did not create a dynamic relocation, or if we
2715 // created a RELATIVE dynamic relocation, we should apply the static
2716 // relocation.
2717 bool has_dyn = gsym->needs_dynamic_reloc(ref_flags);
2718 bool is_rel = (ref_flags & Symbol::ABSOLUTE_REF)
2719 && gsym->can_use_relative_reloc(ref_flags
2720 & Symbol::FUNCTION_CALL);
2721 return !has_dyn || is_rel;
2722 }
2723
2724 // Perform a relocation.
2725
2726 inline bool
relocate(const Relocate_info<32,false> * relinfo,Target_i386 * target,Output_section * output_section,size_t relnum,const elfcpp::Rel<32,false> & rel,unsigned int r_type,const Sized_symbol<32> * gsym,const Symbol_value<32> * psymval,unsigned char * view,elfcpp::Elf_types<32>::Elf_Addr address,section_size_type view_size)2727 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
2728 Target_i386* target,
2729 Output_section* output_section,
2730 size_t relnum,
2731 const elfcpp::Rel<32, false>& rel,
2732 unsigned int r_type,
2733 const Sized_symbol<32>* gsym,
2734 const Symbol_value<32>* psymval,
2735 unsigned char* view,
2736 elfcpp::Elf_types<32>::Elf_Addr address,
2737 section_size_type view_size)
2738 {
2739 if (this->skip_call_tls_get_addr_)
2740 {
2741 if ((r_type != elfcpp::R_386_PLT32
2742 && r_type != elfcpp::R_386_PC32)
2743 || gsym == NULL
2744 || strcmp(gsym->name(), "___tls_get_addr") != 0)
2745 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2746 _("missing expected TLS relocation"));
2747 else
2748 {
2749 this->skip_call_tls_get_addr_ = false;
2750 return false;
2751 }
2752 }
2753
2754 if (view == NULL)
2755 return true;
2756
2757 const Sized_relobj_file<32, false>* object = relinfo->object;
2758
2759 // Pick the value to use for symbols defined in shared objects.
2760 Symbol_value<32> symval;
2761 if (gsym != NULL
2762 && gsym->type() == elfcpp::STT_GNU_IFUNC
2763 && r_type == elfcpp::R_386_32
2764 && gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type))
2765 && gsym->can_use_relative_reloc(false)
2766 && !gsym->is_from_dynobj()
2767 && !gsym->is_undefined()
2768 && !gsym->is_preemptible())
2769 {
2770 // In this case we are generating a R_386_IRELATIVE reloc. We
2771 // want to use the real value of the symbol, not the PLT offset.
2772 }
2773 else if (gsym != NULL
2774 && gsym->use_plt_offset(Scan::get_reference_flags(r_type)))
2775 {
2776 symval.set_output_value(target->plt_address_for_global(gsym));
2777 psymval = &symval;
2778 }
2779 else if (gsym == NULL && psymval->is_ifunc_symbol())
2780 {
2781 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2782 if (object->local_has_plt_offset(r_sym))
2783 {
2784 symval.set_output_value(target->plt_address_for_local(object, r_sym));
2785 psymval = &symval;
2786 }
2787 }
2788
2789 switch (r_type)
2790 {
2791 case elfcpp::R_386_NONE:
2792 case elfcpp::R_386_GNU_VTINHERIT:
2793 case elfcpp::R_386_GNU_VTENTRY:
2794 break;
2795
2796 case elfcpp::R_386_32:
2797 if (should_apply_static_reloc(gsym, r_type, true, output_section))
2798 Relocate_functions<32, false>::rel32(view, object, psymval);
2799 break;
2800
2801 case elfcpp::R_386_PC32:
2802 if (should_apply_static_reloc(gsym, r_type, true, output_section))
2803 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
2804 break;
2805
2806 case elfcpp::R_386_16:
2807 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2808 Relocate_functions<32, false>::rel16(view, object, psymval);
2809 break;
2810
2811 case elfcpp::R_386_PC16:
2812 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2813 Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
2814 break;
2815
2816 case elfcpp::R_386_8:
2817 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2818 Relocate_functions<32, false>::rel8(view, object, psymval);
2819 break;
2820
2821 case elfcpp::R_386_PC8:
2822 if (should_apply_static_reloc(gsym, r_type, false, output_section))
2823 Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
2824 break;
2825
2826 case elfcpp::R_386_PLT32:
2827 gold_assert(gsym == NULL
2828 || gsym->has_plt_offset()
2829 || gsym->final_value_is_known()
2830 || (gsym->is_defined()
2831 && !gsym->is_from_dynobj()
2832 && !gsym->is_preemptible()));
2833 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
2834 break;
2835
2836 case elfcpp::R_386_GOT32:
2837 // Convert
2838 // mov foo@GOT(%reg), %reg
2839 // to
2840 // lea foo@GOTOFF(%reg), %reg
2841 // if possible.
2842 if (rel.get_r_offset() >= 2
2843 && view[-2] == 0x8b
2844 && ((gsym == NULL && !psymval->is_ifunc_symbol())
2845 || (gsym != NULL
2846 && Target_i386::can_convert_mov_to_lea(gsym))))
2847 {
2848 view[-2] = 0x8d;
2849 elfcpp::Elf_types<32>::Elf_Addr value;
2850 value = (psymval->value(object, 0)
2851 - target->got_plt_section()->address());
2852 Relocate_functions<32, false>::rel32(view, value);
2853 }
2854 else
2855 {
2856 // The GOT pointer points to the end of the GOT section.
2857 // We need to subtract the size of the GOT section to get
2858 // the actual offset to use in the relocation.
2859 unsigned int got_offset = 0;
2860 if (gsym != NULL)
2861 {
2862 gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD));
2863 got_offset = (gsym->got_offset(GOT_TYPE_STANDARD)
2864 - target->got_size());
2865 }
2866 else
2867 {
2868 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
2869 gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD));
2870 got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD)
2871 - target->got_size());
2872 }
2873 Relocate_functions<32, false>::rel32(view, got_offset);
2874 }
2875 break;
2876
2877 case elfcpp::R_386_GOTOFF:
2878 {
2879 elfcpp::Elf_types<32>::Elf_Addr value;
2880 value = (psymval->value(object, 0)
2881 - target->got_plt_section()->address());
2882 Relocate_functions<32, false>::rel32(view, value);
2883 }
2884 break;
2885
2886 case elfcpp::R_386_GOTPC:
2887 {
2888 elfcpp::Elf_types<32>::Elf_Addr value;
2889 value = target->got_plt_section()->address();
2890 Relocate_functions<32, false>::pcrel32(view, value, address);
2891 }
2892 break;
2893
2894 case elfcpp::R_386_COPY:
2895 case elfcpp::R_386_GLOB_DAT:
2896 case elfcpp::R_386_JUMP_SLOT:
2897 case elfcpp::R_386_RELATIVE:
2898 case elfcpp::R_386_IRELATIVE:
2899 // These are outstanding tls relocs, which are unexpected when
2900 // linking.
2901 case elfcpp::R_386_TLS_TPOFF:
2902 case elfcpp::R_386_TLS_DTPMOD32:
2903 case elfcpp::R_386_TLS_DTPOFF32:
2904 case elfcpp::R_386_TLS_TPOFF32:
2905 case elfcpp::R_386_TLS_DESC:
2906 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2907 _("unexpected reloc %u in object file"),
2908 r_type);
2909 break;
2910
2911 // These are initial tls relocs, which are expected when
2912 // linking.
2913 case elfcpp::R_386_TLS_GD: // Global-dynamic
2914 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
2915 case elfcpp::R_386_TLS_DESC_CALL:
2916 case elfcpp::R_386_TLS_LDM: // Local-dynamic
2917 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
2918 case elfcpp::R_386_TLS_IE: // Initial-exec
2919 case elfcpp::R_386_TLS_IE_32:
2920 case elfcpp::R_386_TLS_GOTIE:
2921 case elfcpp::R_386_TLS_LE: // Local-exec
2922 case elfcpp::R_386_TLS_LE_32:
2923 this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval,
2924 view, address, view_size);
2925 break;
2926
2927 case elfcpp::R_386_32PLT:
2928 case elfcpp::R_386_TLS_GD_32:
2929 case elfcpp::R_386_TLS_GD_PUSH:
2930 case elfcpp::R_386_TLS_GD_CALL:
2931 case elfcpp::R_386_TLS_GD_POP:
2932 case elfcpp::R_386_TLS_LDM_32:
2933 case elfcpp::R_386_TLS_LDM_PUSH:
2934 case elfcpp::R_386_TLS_LDM_CALL:
2935 case elfcpp::R_386_TLS_LDM_POP:
2936 case elfcpp::R_386_USED_BY_INTEL_200:
2937 default:
2938 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
2939 _("unsupported reloc %u"),
2940 r_type);
2941 break;
2942 }
2943
2944 return true;
2945 }
2946
2947 // Perform a TLS relocation.
2948
2949 inline void
relocate_tls(const Relocate_info<32,false> * relinfo,Target_i386 * target,size_t relnum,const elfcpp::Rel<32,false> & rel,unsigned int r_type,const Sized_symbol<32> * gsym,const Symbol_value<32> * psymval,unsigned char * view,elfcpp::Elf_types<32>::Elf_Addr,section_size_type view_size)2950 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
2951 Target_i386* target,
2952 size_t relnum,
2953 const elfcpp::Rel<32, false>& rel,
2954 unsigned int r_type,
2955 const Sized_symbol<32>* gsym,
2956 const Symbol_value<32>* psymval,
2957 unsigned char* view,
2958 elfcpp::Elf_types<32>::Elf_Addr,
2959 section_size_type view_size)
2960 {
2961 Output_segment* tls_segment = relinfo->layout->tls_segment();
2962
2963 const Sized_relobj_file<32, false>* object = relinfo->object;
2964
2965 elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0);
2966
2967 const bool is_final = (gsym == NULL
2968 ? !parameters->options().shared()
2969 : gsym->final_value_is_known());
2970 const tls::Tls_optimization optimized_type
2971 = Target_i386::optimize_tls_reloc(is_final, r_type);
2972 switch (r_type)
2973 {
2974 case elfcpp::R_386_TLS_GD: // Global-dynamic
2975 if (optimized_type == tls::TLSOPT_TO_LE)
2976 {
2977 if (tls_segment == NULL)
2978 {
2979 gold_assert(parameters->errors()->error_count() > 0
2980 || issue_undefined_symbol_error(gsym));
2981 return;
2982 }
2983 this->tls_gd_to_le(relinfo, relnum, tls_segment,
2984 rel, r_type, value, view,
2985 view_size);
2986 break;
2987 }
2988 else
2989 {
2990 unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
2991 ? GOT_TYPE_TLS_NOFFSET
2992 : GOT_TYPE_TLS_PAIR);
2993 unsigned int got_offset;
2994 if (gsym != NULL)
2995 {
2996 gold_assert(gsym->has_got_offset(got_type));
2997 got_offset = gsym->got_offset(got_type) - target->got_size();
2998 }
2999 else
3000 {
3001 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
3002 gold_assert(object->local_has_got_offset(r_sym, got_type));
3003 got_offset = (object->local_got_offset(r_sym, got_type)
3004 - target->got_size());
3005 }
3006 if (optimized_type == tls::TLSOPT_TO_IE)
3007 {
3008 this->tls_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
3009 got_offset, view, view_size);
3010 break;
3011 }
3012 else if (optimized_type == tls::TLSOPT_NONE)
3013 {
3014 // Relocate the field with the offset of the pair of GOT
3015 // entries.
3016 Relocate_functions<32, false>::rel32(view, got_offset);
3017 break;
3018 }
3019 }
3020 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3021 _("unsupported reloc %u"),
3022 r_type);
3023 break;
3024
3025 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
3026 case elfcpp::R_386_TLS_DESC_CALL:
3027 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
3028 if (optimized_type == tls::TLSOPT_TO_LE)
3029 {
3030 if (tls_segment == NULL)
3031 {
3032 gold_assert(parameters->errors()->error_count() > 0
3033 || issue_undefined_symbol_error(gsym));
3034 return;
3035 }
3036 this->tls_desc_gd_to_le(relinfo, relnum, tls_segment,
3037 rel, r_type, value, view,
3038 view_size);
3039 break;
3040 }
3041 else
3042 {
3043 unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
3044 ? GOT_TYPE_TLS_NOFFSET
3045 : GOT_TYPE_TLS_DESC);
3046 unsigned int got_offset = 0;
3047 if (r_type == elfcpp::R_386_TLS_GOTDESC
3048 && optimized_type == tls::TLSOPT_NONE)
3049 {
3050 // We created GOT entries in the .got.tlsdesc portion of
3051 // the .got.plt section, but the offset stored in the
3052 // symbol is the offset within .got.tlsdesc.
3053 got_offset = (target->got_size()
3054 + target->got_plt_section()->data_size());
3055 }
3056 if (gsym != NULL)
3057 {
3058 gold_assert(gsym->has_got_offset(got_type));
3059 got_offset += gsym->got_offset(got_type) - target->got_size();
3060 }
3061 else
3062 {
3063 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
3064 gold_assert(object->local_has_got_offset(r_sym, got_type));
3065 got_offset += (object->local_got_offset(r_sym, got_type)
3066 - target->got_size());
3067 }
3068 if (optimized_type == tls::TLSOPT_TO_IE)
3069 {
3070 if (tls_segment == NULL)
3071 {
3072 gold_assert(parameters->errors()->error_count() > 0
3073 || issue_undefined_symbol_error(gsym));
3074 return;
3075 }
3076 this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
3077 got_offset, view, view_size);
3078 break;
3079 }
3080 else if (optimized_type == tls::TLSOPT_NONE)
3081 {
3082 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3083 {
3084 // Relocate the field with the offset of the pair of GOT
3085 // entries.
3086 Relocate_functions<32, false>::rel32(view, got_offset);
3087 }
3088 break;
3089 }
3090 }
3091 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3092 _("unsupported reloc %u"),
3093 r_type);
3094 break;
3095
3096 case elfcpp::R_386_TLS_LDM: // Local-dynamic
3097 if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
3098 {
3099 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3100 _("both SUN and GNU model "
3101 "TLS relocations"));
3102 break;
3103 }
3104 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
3105 if (optimized_type == tls::TLSOPT_TO_LE)
3106 {
3107 if (tls_segment == NULL)
3108 {
3109 gold_assert(parameters->errors()->error_count() > 0
3110 || issue_undefined_symbol_error(gsym));
3111 return;
3112 }
3113 this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
3114 value, view, view_size);
3115 break;
3116 }
3117 else if (optimized_type == tls::TLSOPT_NONE)
3118 {
3119 // Relocate the field with the offset of the GOT entry for
3120 // the module index.
3121 unsigned int got_offset;
3122 got_offset = (target->got_mod_index_entry(NULL, NULL, NULL)
3123 - target->got_size());
3124 Relocate_functions<32, false>::rel32(view, got_offset);
3125 break;
3126 }
3127 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3128 _("unsupported reloc %u"),
3129 r_type);
3130 break;
3131
3132 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
3133 if (optimized_type == tls::TLSOPT_TO_LE)
3134 {
3135 // This reloc can appear in debugging sections, in which
3136 // case we must not convert to local-exec. We decide what
3137 // to do based on whether the section is marked as
3138 // containing executable code. That is what the GNU linker
3139 // does as well.
3140 elfcpp::Shdr<32, false> shdr(relinfo->data_shdr);
3141 if ((shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0)
3142 {
3143 if (tls_segment == NULL)
3144 {
3145 gold_assert(parameters->errors()->error_count() > 0
3146 || issue_undefined_symbol_error(gsym));
3147 return;
3148 }
3149 value -= tls_segment->memsz();
3150 }
3151 }
3152 Relocate_functions<32, false>::rel32(view, value);
3153 break;
3154
3155 case elfcpp::R_386_TLS_IE: // Initial-exec
3156 case elfcpp::R_386_TLS_GOTIE:
3157 case elfcpp::R_386_TLS_IE_32:
3158 if (optimized_type == tls::TLSOPT_TO_LE)
3159 {
3160 if (tls_segment == NULL)
3161 {
3162 gold_assert(parameters->errors()->error_count() > 0
3163 || issue_undefined_symbol_error(gsym));
3164 return;
3165 }
3166 Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
3167 rel, r_type, value, view,
3168 view_size);
3169 break;
3170 }
3171 else if (optimized_type == tls::TLSOPT_NONE)
3172 {
3173 // Relocate the field with the offset of the GOT entry for
3174 // the tp-relative offset of the symbol.
3175 unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
3176 ? GOT_TYPE_TLS_OFFSET
3177 : GOT_TYPE_TLS_NOFFSET);
3178 unsigned int got_offset;
3179 if (gsym != NULL)
3180 {
3181 gold_assert(gsym->has_got_offset(got_type));
3182 got_offset = gsym->got_offset(got_type);
3183 }
3184 else
3185 {
3186 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
3187 gold_assert(object->local_has_got_offset(r_sym, got_type));
3188 got_offset = object->local_got_offset(r_sym, got_type);
3189 }
3190 // For the R_386_TLS_IE relocation, we need to apply the
3191 // absolute address of the GOT entry.
3192 if (r_type == elfcpp::R_386_TLS_IE)
3193 got_offset += target->got_plt_section()->address();
3194 // All GOT offsets are relative to the end of the GOT.
3195 got_offset -= target->got_size();
3196 Relocate_functions<32, false>::rel32(view, got_offset);
3197 break;
3198 }
3199 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
3200 _("unsupported reloc %u"),
3201 r_type);
3202 break;
3203
3204 case elfcpp::R_386_TLS_LE: // Local-exec
3205 // If we're creating a shared library, a dynamic relocation will
3206 // have been created for this location, so do not apply it now.
3207 if (!parameters->options().shared())
3208 {
3209 if (tls_segment == NULL)
3210 {
3211 gold_assert(parameters->errors()->error_count() > 0
3212 || issue_undefined_symbol_error(gsym));
3213 return;
3214 }
3215 value -= tls_segment->memsz();
3216 Relocate_functions<32, false>::rel32(view, value);
3217 }
3218 break;
3219
3220 case elfcpp::R_386_TLS_LE_32:
3221 // If we're creating a shared library, a dynamic relocation will
3222 // have been created for this location, so do not apply it now.
3223 if (!parameters->options().shared())
3224 {
3225 if (tls_segment == NULL)
3226 {
3227 gold_assert(parameters->errors()->error_count() > 0
3228 || issue_undefined_symbol_error(gsym));
3229 return;
3230 }
3231 value = tls_segment->memsz() - value;
3232 Relocate_functions<32, false>::rel32(view, value);
3233 }
3234 break;
3235 }
3236 }
3237
3238 // Do a relocation in which we convert a TLS General-Dynamic to a
3239 // Local-Exec.
3240
3241 inline void
tls_gd_to_le(const Relocate_info<32,false> * relinfo,size_t relnum,Output_segment * tls_segment,const elfcpp::Rel<32,false> & rel,unsigned int,elfcpp::Elf_types<32>::Elf_Addr value,unsigned char * view,section_size_type view_size)3242 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
3243 size_t relnum,
3244 Output_segment* tls_segment,
3245 const elfcpp::Rel<32, false>& rel,
3246 unsigned int,
3247 elfcpp::Elf_types<32>::Elf_Addr value,
3248 unsigned char* view,
3249 section_size_type view_size)
3250 {
3251 // leal foo(,%reg,1),%eax; call ___tls_get_addr
3252 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
3253 // leal foo(%reg),%eax; call ___tls_get_addr
3254 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
3255
3256 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3257 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3258
3259 unsigned char op1 = view[-1];
3260 unsigned char op2 = view[-2];
3261
3262 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3263 op2 == 0x8d || op2 == 0x04);
3264 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3265
3266 int roff = 5;
3267
3268 if (op2 == 0x04)
3269 {
3270 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
3271 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
3272 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3273 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
3274 memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3275 }
3276 else
3277 {
3278 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3279 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
3280 if (rel.get_r_offset() + 9 < view_size
3281 && view[9] == 0x90)
3282 {
3283 // There is a trailing nop. Use the size byte subl.
3284 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3285 roff = 6;
3286 }
3287 else
3288 {
3289 // Use the five byte subl.
3290 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
3291 }
3292 }
3293
3294 value = tls_segment->memsz() - value;
3295 Relocate_functions<32, false>::rel32(view + roff, value);
3296
3297 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3298 // We can skip it.
3299 this->skip_call_tls_get_addr_ = true;
3300 }
3301
3302 // Do a relocation in which we convert a TLS General-Dynamic to an
3303 // Initial-Exec.
3304
3305 inline void
tls_gd_to_ie(const Relocate_info<32,false> * relinfo,size_t relnum,Output_segment *,const elfcpp::Rel<32,false> & rel,unsigned int,elfcpp::Elf_types<32>::Elf_Addr value,unsigned char * view,section_size_type view_size)3306 Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
3307 size_t relnum,
3308 Output_segment*,
3309 const elfcpp::Rel<32, false>& rel,
3310 unsigned int,
3311 elfcpp::Elf_types<32>::Elf_Addr value,
3312 unsigned char* view,
3313 section_size_type view_size)
3314 {
3315 // leal foo(,%ebx,1),%eax; call ___tls_get_addr
3316 // ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
3317
3318 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3319 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3320
3321 unsigned char op1 = view[-1];
3322 unsigned char op2 = view[-2];
3323
3324 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3325 op2 == 0x8d || op2 == 0x04);
3326 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3327
3328 int roff = 5;
3329
3330 // FIXME: For now, support only the first (SIB) form.
3331 tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x04);
3332
3333 if (op2 == 0x04)
3334 {
3335 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
3336 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
3337 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3338 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
3339 memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
3340 }
3341 else
3342 {
3343 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3344 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
3345 if (rel.get_r_offset() + 9 < view_size
3346 && view[9] == 0x90)
3347 {
3348 // FIXME: This is not the right instruction sequence.
3349 // There is a trailing nop. Use the size byte subl.
3350 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
3351 roff = 6;
3352 }
3353 else
3354 {
3355 // FIXME: This is not the right instruction sequence.
3356 // Use the five byte subl.
3357 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
3358 }
3359 }
3360
3361 Relocate_functions<32, false>::rel32(view + roff, value);
3362
3363 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3364 // We can skip it.
3365 this->skip_call_tls_get_addr_ = true;
3366 }
3367
3368 // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
3369 // General-Dynamic to a Local-Exec.
3370
3371 inline void
tls_desc_gd_to_le(const Relocate_info<32,false> * relinfo,size_t relnum,Output_segment * tls_segment,const elfcpp::Rel<32,false> & rel,unsigned int r_type,elfcpp::Elf_types<32>::Elf_Addr value,unsigned char * view,section_size_type view_size)3372 Target_i386::Relocate::tls_desc_gd_to_le(
3373 const Relocate_info<32, false>* relinfo,
3374 size_t relnum,
3375 Output_segment* tls_segment,
3376 const elfcpp::Rel<32, false>& rel,
3377 unsigned int r_type,
3378 elfcpp::Elf_types<32>::Elf_Addr value,
3379 unsigned char* view,
3380 section_size_type view_size)
3381 {
3382 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3383 {
3384 // leal foo@TLSDESC(%ebx), %eax
3385 // ==> leal foo@NTPOFF, %eax
3386 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3387 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3388 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3389 view[-2] == 0x8d && view[-1] == 0x83);
3390 view[-1] = 0x05;
3391 value -= tls_segment->memsz();
3392 Relocate_functions<32, false>::rel32(view, value);
3393 }
3394 else
3395 {
3396 // call *foo@TLSCALL(%eax)
3397 // ==> nop; nop
3398 gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
3399 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
3400 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3401 view[0] == 0xff && view[1] == 0x10);
3402 view[0] = 0x66;
3403 view[1] = 0x90;
3404 }
3405 }
3406
3407 // Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
3408 // General-Dynamic to an Initial-Exec.
3409
3410 inline void
tls_desc_gd_to_ie(const Relocate_info<32,false> * relinfo,size_t relnum,Output_segment *,const elfcpp::Rel<32,false> & rel,unsigned int r_type,elfcpp::Elf_types<32>::Elf_Addr value,unsigned char * view,section_size_type view_size)3411 Target_i386::Relocate::tls_desc_gd_to_ie(
3412 const Relocate_info<32, false>* relinfo,
3413 size_t relnum,
3414 Output_segment*,
3415 const elfcpp::Rel<32, false>& rel,
3416 unsigned int r_type,
3417 elfcpp::Elf_types<32>::Elf_Addr value,
3418 unsigned char* view,
3419 section_size_type view_size)
3420 {
3421 if (r_type == elfcpp::R_386_TLS_GOTDESC)
3422 {
3423 // leal foo@TLSDESC(%ebx), %eax
3424 // ==> movl foo@GOTNTPOFF(%ebx), %eax
3425 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3426 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3427 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3428 view[-2] == 0x8d && view[-1] == 0x83);
3429 view[-2] = 0x8b;
3430 Relocate_functions<32, false>::rel32(view, value);
3431 }
3432 else
3433 {
3434 // call *foo@TLSCALL(%eax)
3435 // ==> nop; nop
3436 gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
3437 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
3438 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3439 view[0] == 0xff && view[1] == 0x10);
3440 view[0] = 0x66;
3441 view[1] = 0x90;
3442 }
3443 }
3444
3445 // Do a relocation in which we convert a TLS Local-Dynamic to a
3446 // Local-Exec.
3447
3448 inline void
tls_ld_to_le(const Relocate_info<32,false> * relinfo,size_t relnum,Output_segment *,const elfcpp::Rel<32,false> & rel,unsigned int,elfcpp::Elf_types<32>::Elf_Addr,unsigned char * view,section_size_type view_size)3449 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
3450 size_t relnum,
3451 Output_segment*,
3452 const elfcpp::Rel<32, false>& rel,
3453 unsigned int,
3454 elfcpp::Elf_types<32>::Elf_Addr,
3455 unsigned char* view,
3456 section_size_type view_size)
3457 {
3458 // leal foo(%reg), %eax; call ___tls_get_addr
3459 // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
3460
3461 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3462 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
3463
3464 // FIXME: Does this test really always pass?
3465 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3466 view[-2] == 0x8d && view[-1] == 0x83);
3467
3468 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
3469
3470 memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
3471
3472 // The next reloc should be a PLT32 reloc against __tls_get_addr.
3473 // We can skip it.
3474 this->skip_call_tls_get_addr_ = true;
3475 }
3476
3477 // Do a relocation in which we convert a TLS Initial-Exec to a
3478 // Local-Exec.
3479
3480 inline void
tls_ie_to_le(const Relocate_info<32,false> * relinfo,size_t relnum,Output_segment * tls_segment,const elfcpp::Rel<32,false> & rel,unsigned int r_type,elfcpp::Elf_types<32>::Elf_Addr value,unsigned char * view,section_size_type view_size)3481 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
3482 size_t relnum,
3483 Output_segment* tls_segment,
3484 const elfcpp::Rel<32, false>& rel,
3485 unsigned int r_type,
3486 elfcpp::Elf_types<32>::Elf_Addr value,
3487 unsigned char* view,
3488 section_size_type view_size)
3489 {
3490 // We have to actually change the instructions, which means that we
3491 // need to examine the opcodes to figure out which instruction we
3492 // are looking at.
3493 if (r_type == elfcpp::R_386_TLS_IE)
3494 {
3495 // movl %gs:XX,%eax ==> movl $YY,%eax
3496 // movl %gs:XX,%reg ==> movl $YY,%reg
3497 // addl %gs:XX,%reg ==> addl $YY,%reg
3498 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
3499 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3500
3501 unsigned char op1 = view[-1];
3502 if (op1 == 0xa1)
3503 {
3504 // movl XX,%eax ==> movl $YY,%eax
3505 view[-1] = 0xb8;
3506 }
3507 else
3508 {
3509 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3510
3511 unsigned char op2 = view[-2];
3512 if (op2 == 0x8b)
3513 {
3514 // movl XX,%reg ==> movl $YY,%reg
3515 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3516 (op1 & 0xc7) == 0x05);
3517 view[-2] = 0xc7;
3518 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3519 }
3520 else if (op2 == 0x03)
3521 {
3522 // addl XX,%reg ==> addl $YY,%reg
3523 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3524 (op1 & 0xc7) == 0x05);
3525 view[-2] = 0x81;
3526 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3527 }
3528 else
3529 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
3530 }
3531 }
3532 else
3533 {
3534 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
3535 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
3536 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
3537 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
3538 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
3539
3540 unsigned char op1 = view[-1];
3541 unsigned char op2 = view[-2];
3542 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
3543 (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
3544 if (op2 == 0x8b)
3545 {
3546 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
3547 view[-2] = 0xc7;
3548 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3549 }
3550 else if (op2 == 0x2b)
3551 {
3552 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
3553 view[-2] = 0x81;
3554 view[-1] = 0xe8 | ((op1 >> 3) & 7);
3555 }
3556 else if (op2 == 0x03)
3557 {
3558 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
3559 view[-2] = 0x81;
3560 view[-1] = 0xc0 | ((op1 >> 3) & 7);
3561 }
3562 else
3563 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
3564 }
3565
3566 value = tls_segment->memsz() - value;
3567 if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
3568 value = - value;
3569
3570 Relocate_functions<32, false>::rel32(view, value);
3571 }
3572
3573 // Relocate section data.
3574
3575 void
relocate_section(const Relocate_info<32,false> * relinfo,unsigned int sh_type,const unsigned char * prelocs,size_t reloc_count,Output_section * output_section,bool needs_special_offset_handling,unsigned char * view,elfcpp::Elf_types<32>::Elf_Addr address,section_size_type view_size,const Reloc_symbol_changes * reloc_symbol_changes)3576 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
3577 unsigned int sh_type,
3578 const unsigned char* prelocs,
3579 size_t reloc_count,
3580 Output_section* output_section,
3581 bool needs_special_offset_handling,
3582 unsigned char* view,
3583 elfcpp::Elf_types<32>::Elf_Addr address,
3584 section_size_type view_size,
3585 const Reloc_symbol_changes* reloc_symbol_changes)
3586 {
3587 gold_assert(sh_type == elfcpp::SHT_REL);
3588
3589 gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
3590 Target_i386::Relocate, gold::Default_comdat_behavior>(
3591 relinfo,
3592 this,
3593 prelocs,
3594 reloc_count,
3595 output_section,
3596 needs_special_offset_handling,
3597 view,
3598 address,
3599 view_size,
3600 reloc_symbol_changes);
3601 }
3602
3603 // Return the size of a relocation while scanning during a relocatable
3604 // link.
3605
3606 unsigned int
get_size_for_reloc(unsigned int r_type,Relobj * object)3607 Target_i386::Relocatable_size_for_reloc::get_size_for_reloc(
3608 unsigned int r_type,
3609 Relobj* object)
3610 {
3611 switch (r_type)
3612 {
3613 case elfcpp::R_386_NONE:
3614 case elfcpp::R_386_GNU_VTINHERIT:
3615 case elfcpp::R_386_GNU_VTENTRY:
3616 case elfcpp::R_386_TLS_GD: // Global-dynamic
3617 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
3618 case elfcpp::R_386_TLS_DESC_CALL:
3619 case elfcpp::R_386_TLS_LDM: // Local-dynamic
3620 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
3621 case elfcpp::R_386_TLS_IE: // Initial-exec
3622 case elfcpp::R_386_TLS_IE_32:
3623 case elfcpp::R_386_TLS_GOTIE:
3624 case elfcpp::R_386_TLS_LE: // Local-exec
3625 case elfcpp::R_386_TLS_LE_32:
3626 return 0;
3627
3628 case elfcpp::R_386_32:
3629 case elfcpp::R_386_PC32:
3630 case elfcpp::R_386_GOT32:
3631 case elfcpp::R_386_PLT32:
3632 case elfcpp::R_386_GOTOFF:
3633 case elfcpp::R_386_GOTPC:
3634 return 4;
3635
3636 case elfcpp::R_386_16:
3637 case elfcpp::R_386_PC16:
3638 return 2;
3639
3640 case elfcpp::R_386_8:
3641 case elfcpp::R_386_PC8:
3642 return 1;
3643
3644 // These are relocations which should only be seen by the
3645 // dynamic linker, and should never be seen here.
3646 case elfcpp::R_386_COPY:
3647 case elfcpp::R_386_GLOB_DAT:
3648 case elfcpp::R_386_JUMP_SLOT:
3649 case elfcpp::R_386_RELATIVE:
3650 case elfcpp::R_386_IRELATIVE:
3651 case elfcpp::R_386_TLS_TPOFF:
3652 case elfcpp::R_386_TLS_DTPMOD32:
3653 case elfcpp::R_386_TLS_DTPOFF32:
3654 case elfcpp::R_386_TLS_TPOFF32:
3655 case elfcpp::R_386_TLS_DESC:
3656 object->error(_("unexpected reloc %u in object file"), r_type);
3657 return 0;
3658
3659 case elfcpp::R_386_32PLT:
3660 case elfcpp::R_386_TLS_GD_32:
3661 case elfcpp::R_386_TLS_GD_PUSH:
3662 case elfcpp::R_386_TLS_GD_CALL:
3663 case elfcpp::R_386_TLS_GD_POP:
3664 case elfcpp::R_386_TLS_LDM_32:
3665 case elfcpp::R_386_TLS_LDM_PUSH:
3666 case elfcpp::R_386_TLS_LDM_CALL:
3667 case elfcpp::R_386_TLS_LDM_POP:
3668 case elfcpp::R_386_USED_BY_INTEL_200:
3669 default:
3670 object->error(_("unsupported reloc %u in object file"), r_type);
3671 return 0;
3672 }
3673 }
3674
3675 // Scan the relocs during a relocatable link.
3676
3677 void
scan_relocatable_relocs(Symbol_table * symtab,Layout * layout,Sized_relobj_file<32,false> * object,unsigned int data_shndx,unsigned int sh_type,const unsigned char * prelocs,size_t reloc_count,Output_section * output_section,bool needs_special_offset_handling,size_t local_symbol_count,const unsigned char * plocal_symbols,Relocatable_relocs * rr)3678 Target_i386::scan_relocatable_relocs(Symbol_table* symtab,
3679 Layout* layout,
3680 Sized_relobj_file<32, false>* object,
3681 unsigned int data_shndx,
3682 unsigned int sh_type,
3683 const unsigned char* prelocs,
3684 size_t reloc_count,
3685 Output_section* output_section,
3686 bool needs_special_offset_handling,
3687 size_t local_symbol_count,
3688 const unsigned char* plocal_symbols,
3689 Relocatable_relocs* rr)
3690 {
3691 gold_assert(sh_type == elfcpp::SHT_REL);
3692
3693 typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_REL,
3694 Relocatable_size_for_reloc> Scan_relocatable_relocs;
3695
3696 gold::scan_relocatable_relocs<32, false, elfcpp::SHT_REL,
3697 Scan_relocatable_relocs>(
3698 symtab,
3699 layout,
3700 object,
3701 data_shndx,
3702 prelocs,
3703 reloc_count,
3704 output_section,
3705 needs_special_offset_handling,
3706 local_symbol_count,
3707 plocal_symbols,
3708 rr);
3709 }
3710
3711 // Emit relocations for a section.
3712
3713 void
relocate_relocs(const Relocate_info<32,false> * relinfo,unsigned int sh_type,const unsigned char * prelocs,size_t reloc_count,Output_section * output_section,elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,const Relocatable_relocs * rr,unsigned char * view,elfcpp::Elf_types<32>::Elf_Addr view_address,section_size_type view_size,unsigned char * reloc_view,section_size_type reloc_view_size)3714 Target_i386::relocate_relocs(
3715 const Relocate_info<32, false>* relinfo,
3716 unsigned int sh_type,
3717 const unsigned char* prelocs,
3718 size_t reloc_count,
3719 Output_section* output_section,
3720 elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,
3721 const Relocatable_relocs* rr,
3722 unsigned char* view,
3723 elfcpp::Elf_types<32>::Elf_Addr view_address,
3724 section_size_type view_size,
3725 unsigned char* reloc_view,
3726 section_size_type reloc_view_size)
3727 {
3728 gold_assert(sh_type == elfcpp::SHT_REL);
3729
3730 gold::relocate_relocs<32, false, elfcpp::SHT_REL>(
3731 relinfo,
3732 prelocs,
3733 reloc_count,
3734 output_section,
3735 offset_in_output_section,
3736 rr,
3737 view,
3738 view_address,
3739 view_size,
3740 reloc_view,
3741 reloc_view_size);
3742 }
3743
3744 // Return the value to use for a dynamic which requires special
3745 // treatment. This is how we support equality comparisons of function
3746 // pointers across shared library boundaries, as described in the
3747 // processor specific ABI supplement.
3748
3749 uint64_t
do_dynsym_value(const Symbol * gsym) const3750 Target_i386::do_dynsym_value(const Symbol* gsym) const
3751 {
3752 gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
3753 return this->plt_address_for_global(gsym);
3754 }
3755
3756 // Return a string used to fill a code section with nops to take up
3757 // the specified length.
3758
3759 std::string
do_code_fill(section_size_type length) const3760 Target_i386::do_code_fill(section_size_type length) const
3761 {
3762 if (length >= 16)
3763 {
3764 // Build a jmp instruction to skip over the bytes.
3765 unsigned char jmp[5];
3766 jmp[0] = 0xe9;
3767 elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
3768 return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
3769 + std::string(length - 5, static_cast<char>(0x90)));
3770 }
3771
3772 // Nop sequences of various lengths.
3773 const char nop1[1] = { '\x90' }; // nop
3774 const char nop2[2] = { '\x66', '\x90' }; // xchg %ax %ax
3775 const char nop3[3] = { '\x8d', '\x76', '\x00' }; // leal 0(%esi),%esi
3776 const char nop4[4] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
3777 '\x00'};
3778 const char nop5[5] = { '\x90', '\x8d', '\x74', // nop
3779 '\x26', '\x00' }; // leal 0(%esi,1),%esi
3780 const char nop6[6] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
3781 '\x00', '\x00', '\x00' };
3782 const char nop7[7] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
3783 '\x00', '\x00', '\x00',
3784 '\x00' };
3785 const char nop8[8] = { '\x90', '\x8d', '\xb4', // nop
3786 '\x26', '\x00', '\x00', // leal 0L(%esi,1),%esi
3787 '\x00', '\x00' };
3788 const char nop9[9] = { '\x89', '\xf6', '\x8d', // movl %esi,%esi
3789 '\xbc', '\x27', '\x00', // leal 0L(%edi,1),%edi
3790 '\x00', '\x00', '\x00' };
3791 const char nop10[10] = { '\x8d', '\x76', '\x00', // leal 0(%esi),%esi
3792 '\x8d', '\xbc', '\x27', // leal 0L(%edi,1),%edi
3793 '\x00', '\x00', '\x00',
3794 '\x00' };
3795 const char nop11[11] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
3796 '\x00', '\x8d', '\xbc', // leal 0L(%edi,1),%edi
3797 '\x27', '\x00', '\x00',
3798 '\x00', '\x00' };
3799 const char nop12[12] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
3800 '\x00', '\x00', '\x00', // leal 0L(%edi),%edi
3801 '\x8d', '\xbf', '\x00',
3802 '\x00', '\x00', '\x00' };
3803 const char nop13[13] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
3804 '\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
3805 '\x8d', '\xbc', '\x27',
3806 '\x00', '\x00', '\x00',
3807 '\x00' };
3808 const char nop14[14] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
3809 '\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
3810 '\x00', '\x8d', '\xbc',
3811 '\x27', '\x00', '\x00',
3812 '\x00', '\x00' };
3813 const char nop15[15] = { '\xeb', '\x0d', '\x90', // jmp .+15
3814 '\x90', '\x90', '\x90', // nop,nop,nop,...
3815 '\x90', '\x90', '\x90',
3816 '\x90', '\x90', '\x90',
3817 '\x90', '\x90', '\x90' };
3818
3819 const char* nops[16] = {
3820 NULL,
3821 nop1, nop2, nop3, nop4, nop5, nop6, nop7,
3822 nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
3823 };
3824
3825 return std::string(nops[length], length);
3826 }
3827
3828 // Return the value to use for the base of a DW_EH_PE_datarel offset
3829 // in an FDE. Solaris and SVR4 use DW_EH_PE_datarel because their
3830 // assembler can not write out the difference between two labels in
3831 // different sections, so instead of using a pc-relative value they
3832 // use an offset from the GOT.
3833
3834 uint64_t
do_ehframe_datarel_base() const3835 Target_i386::do_ehframe_datarel_base() const
3836 {
3837 gold_assert(this->global_offset_table_ != NULL);
3838 Symbol* sym = this->global_offset_table_;
3839 Sized_symbol<32>* ssym = static_cast<Sized_symbol<32>*>(sym);
3840 return ssym->value();
3841 }
3842
3843 // Return whether SYM should be treated as a call to a non-split
3844 // function. We don't want that to be true of a call to a
3845 // get_pc_thunk function.
3846
3847 bool
do_is_call_to_non_split(const Symbol * sym,unsigned int) const3848 Target_i386::do_is_call_to_non_split(const Symbol* sym, unsigned int) const
3849 {
3850 return (sym->type() == elfcpp::STT_FUNC
3851 && !is_prefix_of("__i686.get_pc_thunk.", sym->name()));
3852 }
3853
3854 // FNOFFSET in section SHNDX in OBJECT is the start of a function
3855 // compiled with -fsplit-stack. The function calls non-split-stack
3856 // code. We have to change the function so that it always ensures
3857 // that it has enough stack space to run some random function.
3858
3859 void
do_calls_non_split(Relobj * object,unsigned int shndx,section_offset_type fnoffset,section_size_type fnsize,unsigned char * view,section_size_type view_size,std::string * from,std::string * to) const3860 Target_i386::do_calls_non_split(Relobj* object, unsigned int shndx,
3861 section_offset_type fnoffset,
3862 section_size_type fnsize,
3863 unsigned char* view,
3864 section_size_type view_size,
3865 std::string* from,
3866 std::string* to) const
3867 {
3868 // The function starts with a comparison of the stack pointer and a
3869 // field in the TCB. This is followed by a jump.
3870
3871 // cmp %gs:NN,%esp
3872 if (this->match_view(view, view_size, fnoffset, "\x65\x3b\x25", 3)
3873 && fnsize > 7)
3874 {
3875 // We will call __morestack if the carry flag is set after this
3876 // comparison. We turn the comparison into an stc instruction
3877 // and some nops.
3878 view[fnoffset] = '\xf9';
3879 this->set_view_to_nop(view, view_size, fnoffset + 1, 6);
3880 }
3881 // lea NN(%esp),%ecx
3882 // lea NN(%esp),%edx
3883 else if ((this->match_view(view, view_size, fnoffset, "\x8d\x8c\x24", 3)
3884 || this->match_view(view, view_size, fnoffset, "\x8d\x94\x24", 3))
3885 && fnsize > 7)
3886 {
3887 // This is loading an offset from the stack pointer for a
3888 // comparison. The offset is negative, so we decrease the
3889 // offset by the amount of space we need for the stack. This
3890 // means we will avoid calling __morestack if there happens to
3891 // be plenty of space on the stack already.
3892 unsigned char* pval = view + fnoffset + 3;
3893 uint32_t val = elfcpp::Swap_unaligned<32, false>::readval(pval);
3894 val -= parameters->options().split_stack_adjust_size();
3895 elfcpp::Swap_unaligned<32, false>::writeval(pval, val);
3896 }
3897 else
3898 {
3899 if (!object->has_no_split_stack())
3900 object->error(_("failed to match split-stack sequence at "
3901 "section %u offset %0zx"),
3902 shndx, static_cast<size_t>(fnoffset));
3903 return;
3904 }
3905
3906 // We have to change the function so that it calls
3907 // __morestack_non_split instead of __morestack. The former will
3908 // allocate additional stack space.
3909 *from = "__morestack";
3910 *to = "__morestack_non_split";
3911 }
3912
3913 // The selector for i386 object files. Note this is never instantiated
3914 // directly. It's only used in Target_selector_i386_nacl, below.
3915
3916 class Target_selector_i386 : public Target_selector_freebsd
3917 {
3918 public:
Target_selector_i386()3919 Target_selector_i386()
3920 : Target_selector_freebsd(elfcpp::EM_386, 32, false,
3921 "elf32-i386", "elf32-i386-freebsd",
3922 "elf_i386")
3923 { }
3924
3925 Target*
do_instantiate_target()3926 do_instantiate_target()
3927 { return new Target_i386(); }
3928 };
3929
3930 // NaCl variant. It uses different PLT contents.
3931
3932 class Output_data_plt_i386_nacl : public Output_data_plt_i386
3933 {
3934 public:
Output_data_plt_i386_nacl(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)3935 Output_data_plt_i386_nacl(Layout* layout,
3936 Output_data_got_plt_i386* got_plt,
3937 Output_data_space* got_irelative)
3938 : Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
3939 { }
3940
3941 protected:
3942 virtual unsigned int
do_get_plt_entry_size() const3943 do_get_plt_entry_size() const
3944 { return plt_entry_size; }
3945
3946 virtual void
do_add_eh_frame(Layout * layout)3947 do_add_eh_frame(Layout* layout)
3948 {
3949 layout->add_eh_frame_for_plt(this, plt_eh_frame_cie, plt_eh_frame_cie_size,
3950 plt_eh_frame_fde, plt_eh_frame_fde_size);
3951 }
3952
3953 // The size of an entry in the PLT.
3954 static const int plt_entry_size = 64;
3955
3956 // The .eh_frame unwind information for the PLT.
3957 static const int plt_eh_frame_fde_size = 32;
3958 static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
3959 };
3960
3961 class Output_data_plt_i386_nacl_exec : public Output_data_plt_i386_nacl
3962 {
3963 public:
Output_data_plt_i386_nacl_exec(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)3964 Output_data_plt_i386_nacl_exec(Layout* layout,
3965 Output_data_got_plt_i386* got_plt,
3966 Output_data_space* got_irelative)
3967 : Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
3968 { }
3969
3970 protected:
3971 virtual void
3972 do_fill_first_plt_entry(unsigned char* pov,
3973 elfcpp::Elf_types<32>::Elf_Addr got_address);
3974
3975 virtual unsigned int
3976 do_fill_plt_entry(unsigned char* pov,
3977 elfcpp::Elf_types<32>::Elf_Addr got_address,
3978 unsigned int got_offset,
3979 unsigned int plt_offset,
3980 unsigned int plt_rel_offset);
3981
3982 private:
3983 // The first entry in the PLT for an executable.
3984 static const unsigned char first_plt_entry[plt_entry_size];
3985
3986 // Other entries in the PLT for an executable.
3987 static const unsigned char plt_entry[plt_entry_size];
3988 };
3989
3990 class Output_data_plt_i386_nacl_dyn : public Output_data_plt_i386_nacl
3991 {
3992 public:
Output_data_plt_i386_nacl_dyn(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative)3993 Output_data_plt_i386_nacl_dyn(Layout* layout,
3994 Output_data_got_plt_i386* got_plt,
3995 Output_data_space* got_irelative)
3996 : Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
3997 { }
3998
3999 protected:
4000 virtual void
4001 do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<32>::Elf_Addr);
4002
4003 virtual unsigned int
4004 do_fill_plt_entry(unsigned char* pov,
4005 elfcpp::Elf_types<32>::Elf_Addr,
4006 unsigned int got_offset,
4007 unsigned int plt_offset,
4008 unsigned int plt_rel_offset);
4009
4010 private:
4011 // The first entry in the PLT for a shared object.
4012 static const unsigned char first_plt_entry[plt_entry_size];
4013
4014 // Other entries in the PLT for a shared object.
4015 static const unsigned char plt_entry[plt_entry_size];
4016 };
4017
4018 class Target_i386_nacl : public Target_i386
4019 {
4020 public:
Target_i386_nacl()4021 Target_i386_nacl()
4022 : Target_i386(&i386_nacl_info)
4023 { }
4024
4025 protected:
4026 virtual Output_data_plt_i386*
do_make_data_plt(Layout * layout,Output_data_got_plt_i386 * got_plt,Output_data_space * got_irelative,bool dyn)4027 do_make_data_plt(Layout* layout,
4028 Output_data_got_plt_i386* got_plt,
4029 Output_data_space* got_irelative,
4030 bool dyn)
4031 {
4032 if (dyn)
4033 return new Output_data_plt_i386_nacl_dyn(layout, got_plt, got_irelative);
4034 else
4035 return new Output_data_plt_i386_nacl_exec(layout, got_plt, got_irelative);
4036 }
4037
4038 virtual std::string
4039 do_code_fill(section_size_type length) const;
4040
4041 private:
4042 static const Target::Target_info i386_nacl_info;
4043 };
4044
4045 const Target::Target_info Target_i386_nacl::i386_nacl_info =
4046 {
4047 32, // size
4048 false, // is_big_endian
4049 elfcpp::EM_386, // machine_code
4050 false, // has_make_symbol
4051 false, // has_resolve
4052 true, // has_code_fill
4053 true, // is_default_stack_executable
4054 true, // can_icf_inline_merge_sections
4055 '\0', // wrap_char
4056 "/lib/ld-nacl-x86-32.so.1", // dynamic_linker
4057 0x20000, // default_text_segment_address
4058 0x10000, // abi_pagesize (overridable by -z max-page-size)
4059 0x10000, // common_pagesize (overridable by -z common-page-size)
4060 true, // isolate_execinstr
4061 0x10000000, // rosegment_gap
4062 elfcpp::SHN_UNDEF, // small_common_shndx
4063 elfcpp::SHN_UNDEF, // large_common_shndx
4064 0, // small_common_section_flags
4065 0, // large_common_section_flags
4066 NULL, // attributes_section
4067 NULL, // attributes_vendor
4068 "_start" // entry_symbol_name
4069 };
4070
4071 #define NACLMASK 0xe0 // 32-byte alignment mask
4072
4073 const unsigned char
4074 Output_data_plt_i386_nacl_exec::first_plt_entry[plt_entry_size] =
4075 {
4076 0xff, 0x35, // pushl contents of memory address
4077 0, 0, 0, 0, // replaced with address of .got + 4
4078 0x8b, 0x0d, // movl contents of address, %ecx
4079 0, 0, 0, 0, // replaced with address of .got + 8
4080 0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
4081 0xff, 0xe1, // jmp *%ecx
4082 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4083 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4084 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4085 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4086 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4087 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4088 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4089 0x90, 0x90, 0x90, 0x90, 0x90
4090 };
4091
4092 void
do_fill_first_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr got_address)4093 Output_data_plt_i386_nacl_exec::do_fill_first_plt_entry(
4094 unsigned char* pov,
4095 elfcpp::Elf_types<32>::Elf_Addr got_address)
4096 {
4097 memcpy(pov, first_plt_entry, plt_entry_size);
4098 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
4099 elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
4100 }
4101
4102 // The first entry in the PLT for a shared object.
4103
4104 const unsigned char
4105 Output_data_plt_i386_nacl_dyn::first_plt_entry[plt_entry_size] =
4106 {
4107 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
4108 0x8b, 0x4b, 0x08, // mov 0x8(%ebx), %ecx
4109 0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
4110 0xff, 0xe1, // jmp *%ecx
4111 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4112 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4113 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4114 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4115 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4116 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4117 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4118 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4119 0x90, 0x90, 0x90, 0x90, 0x90, // nops
4120 0x90, 0x90, 0x90, 0x90, 0x90 // nops
4121 };
4122
4123 void
do_fill_first_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr)4124 Output_data_plt_i386_nacl_dyn::do_fill_first_plt_entry(
4125 unsigned char* pov,
4126 elfcpp::Elf_types<32>::Elf_Addr)
4127 {
4128 memcpy(pov, first_plt_entry, plt_entry_size);
4129 }
4130
4131 // Subsequent entries in the PLT for an executable.
4132
4133 const unsigned char
4134 Output_data_plt_i386_nacl_exec::plt_entry[plt_entry_size] =
4135 {
4136 0x8b, 0x0d, // movl contents of address, %ecx */
4137 0, 0, 0, 0, // replaced with address of symbol in .got
4138 0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
4139 0xff, 0xe1, // jmp *%ecx
4140
4141 // Pad to the next 32-byte boundary with nop instructions.
4142 0x90,
4143 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4144 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4145
4146 // Lazy GOT entries point here (32-byte aligned).
4147 0x68, // pushl immediate
4148 0, 0, 0, 0, // replaced with offset into relocation table
4149 0xe9, // jmp relative
4150 0, 0, 0, 0, // replaced with offset to start of .plt
4151
4152 // Pad to the next 32-byte boundary with nop instructions.
4153 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4154 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4155 0x90, 0x90
4156 };
4157
4158 unsigned int
do_fill_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr got_address,unsigned int got_offset,unsigned int plt_offset,unsigned int plt_rel_offset)4159 Output_data_plt_i386_nacl_exec::do_fill_plt_entry(
4160 unsigned char* pov,
4161 elfcpp::Elf_types<32>::Elf_Addr got_address,
4162 unsigned int got_offset,
4163 unsigned int plt_offset,
4164 unsigned int plt_rel_offset)
4165 {
4166 memcpy(pov, plt_entry, plt_entry_size);
4167 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
4168 got_address + got_offset);
4169 elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_rel_offset);
4170 elfcpp::Swap<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4));
4171 return 32;
4172 }
4173
4174 // Subsequent entries in the PLT for a shared object.
4175
4176 const unsigned char
4177 Output_data_plt_i386_nacl_dyn::plt_entry[plt_entry_size] =
4178 {
4179 0x8b, 0x8b, // movl offset(%ebx), %ecx
4180 0, 0, 0, 0, // replaced with offset of symbol in .got
4181 0x83, 0xe1, 0xe0, // andl $NACLMASK, %ecx
4182 0xff, 0xe1, // jmp *%ecx
4183
4184 // Pad to the next 32-byte boundary with nop instructions.
4185 0x90,
4186 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4187 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4188
4189 // Lazy GOT entries point here (32-byte aligned).
4190 0x68, // pushl immediate
4191 0, 0, 0, 0, // replaced with offset into relocation table.
4192 0xe9, // jmp relative
4193 0, 0, 0, 0, // replaced with offset to start of .plt.
4194
4195 // Pad to the next 32-byte boundary with nop instructions.
4196 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4197 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
4198 0x90, 0x90
4199 };
4200
4201 unsigned int
do_fill_plt_entry(unsigned char * pov,elfcpp::Elf_types<32>::Elf_Addr,unsigned int got_offset,unsigned int plt_offset,unsigned int plt_rel_offset)4202 Output_data_plt_i386_nacl_dyn::do_fill_plt_entry(
4203 unsigned char* pov,
4204 elfcpp::Elf_types<32>::Elf_Addr,
4205 unsigned int got_offset,
4206 unsigned int plt_offset,
4207 unsigned int plt_rel_offset)
4208 {
4209 memcpy(pov, plt_entry, plt_entry_size);
4210 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
4211 elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_rel_offset);
4212 elfcpp::Swap<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4));
4213 return 32;
4214 }
4215
4216 const unsigned char
4217 Output_data_plt_i386_nacl::plt_eh_frame_fde[plt_eh_frame_fde_size] =
4218 {
4219 0, 0, 0, 0, // Replaced with offset to .plt.
4220 0, 0, 0, 0, // Replaced with size of .plt.
4221 0, // Augmentation size.
4222 elfcpp::DW_CFA_def_cfa_offset, 8, // DW_CFA_def_cfa_offset: 8.
4223 elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
4224 elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
4225 elfcpp::DW_CFA_advance_loc + 58, // Advance 58 to __PLT__ + 64.
4226 elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
4227 13, // Block length.
4228 elfcpp::DW_OP_breg4, 4, // Push %esp + 4.
4229 elfcpp::DW_OP_breg8, 0, // Push %eip.
4230 elfcpp::DW_OP_const1u, 63, // Push 0x3f.
4231 elfcpp::DW_OP_and, // & (%eip & 0x3f).
4232 elfcpp::DW_OP_const1u, 37, // Push 0x25.
4233 elfcpp::DW_OP_ge, // >= ((%eip & 0x3f) >= 0x25)
4234 elfcpp::DW_OP_lit2, // Push 2.
4235 elfcpp::DW_OP_shl, // << (((%eip & 0x3f) >= 0x25) << 2)
4236 elfcpp::DW_OP_plus, // + ((((%eip&0x3f)>=0x25)<<2)+%esp+4
4237 elfcpp::DW_CFA_nop, // Align to 32 bytes.
4238 elfcpp::DW_CFA_nop
4239 };
4240
4241 // Return a string used to fill a code section with nops.
4242 // For NaCl, long NOPs are only valid if they do not cross
4243 // bundle alignment boundaries, so keep it simple with one-byte NOPs.
4244 std::string
do_code_fill(section_size_type length) const4245 Target_i386_nacl::do_code_fill(section_size_type length) const
4246 {
4247 return std::string(length, static_cast<char>(0x90));
4248 }
4249
4250 // The selector for i386-nacl object files.
4251
4252 class Target_selector_i386_nacl
4253 : public Target_selector_nacl<Target_selector_i386, Target_i386_nacl>
4254 {
4255 public:
Target_selector_i386_nacl()4256 Target_selector_i386_nacl()
4257 : Target_selector_nacl<Target_selector_i386,
4258 Target_i386_nacl>("x86-32",
4259 "elf32-i386-nacl",
4260 "elf_i386_nacl")
4261 { }
4262 };
4263
4264 Target_selector_i386_nacl target_selector_i386;
4265
4266 } // End anonymous namespace.
4267