From Craig Silverstein: Support -o -.
[binutils-gdb.git] / gold / i386.cc
1 // i386.cc -- i386 target support for gold.
2
3 // Copyright 2006, 2007 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 "parameters.h"
29 #include "reloc.h"
30 #include "i386.h"
31 #include "object.h"
32 #include "symtab.h"
33 #include "layout.h"
34 #include "output.h"
35 #include "target.h"
36 #include "target-reloc.h"
37 #include "target-select.h"
38 #include "tls.h"
39
40 namespace
41 {
42
43 using namespace gold;
44
45 class Output_data_plt_i386;
46
47 // The i386 target class.
48 // TLS info comes from
49 // http://people.redhat.com/drepper/tls.pdf
50 // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
51
52 class Target_i386 : public Sized_target<32, false>
53 {
54 public:
55 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
56
57 Target_i386()
58 : Sized_target<32, false>(&i386_info),
59 got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
60 copy_relocs_(NULL), dynbss_(NULL)
61 { }
62
63 // Scan the relocations to look for symbol adjustments.
64 void
65 scan_relocs(const General_options& options,
66 Symbol_table* symtab,
67 Layout* layout,
68 Sized_relobj<32, false>* object,
69 unsigned int data_shndx,
70 unsigned int sh_type,
71 const unsigned char* prelocs,
72 size_t reloc_count,
73 Output_section* output_section,
74 bool needs_special_offset_handling,
75 size_t local_symbol_count,
76 const unsigned char* plocal_symbols);
77
78 // Finalize the sections.
79 void
80 do_finalize_sections(Layout*);
81
82 // Return the value to use for a dynamic which requires special
83 // treatment.
84 uint64_t
85 do_dynsym_value(const Symbol*) const;
86
87 // Relocate a section.
88 void
89 relocate_section(const Relocate_info<32, false>*,
90 unsigned int sh_type,
91 const unsigned char* prelocs,
92 size_t reloc_count,
93 Output_section* output_section,
94 bool needs_special_offset_handling,
95 unsigned char* view,
96 elfcpp::Elf_types<32>::Elf_Addr view_address,
97 off_t view_size);
98
99 // Return a string used to fill a code section with nops.
100 std::string
101 do_code_fill(off_t length);
102
103 // Return whether SYM is defined by the ABI.
104 bool
105 do_is_defined_by_abi(Symbol* sym) const
106 { return strcmp(sym->name(), "___tls_get_addr") == 0; }
107
108 // Return the size of the GOT section.
109 off_t
110 got_size()
111 {
112 gold_assert(this->got_ != NULL);
113 return this->got_->data_size();
114 }
115
116 private:
117 // The class which scans relocations.
118 struct Scan
119 {
120 inline void
121 local(const General_options& options, Symbol_table* symtab,
122 Layout* layout, Target_i386* target,
123 Sized_relobj<32, false>* object,
124 unsigned int data_shndx,
125 Output_section* output_section,
126 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
127 const elfcpp::Sym<32, false>& lsym);
128
129 inline void
130 global(const General_options& options, Symbol_table* symtab,
131 Layout* layout, Target_i386* target,
132 Sized_relobj<32, false>* object,
133 unsigned int data_shndx,
134 Output_section* output_section,
135 const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
136 Symbol* gsym);
137
138 static void
139 unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);
140
141 static void
142 unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type,
143 Symbol*);
144 };
145
146 // The class which implements relocation.
147 class Relocate
148 {
149 public:
150 Relocate()
151 : skip_call_tls_get_addr_(false),
152 local_dynamic_type_(LOCAL_DYNAMIC_NONE)
153 { }
154
155 ~Relocate()
156 {
157 if (this->skip_call_tls_get_addr_)
158 {
159 // FIXME: This needs to specify the location somehow.
160 gold_error(_("missing expected TLS relocation"));
161 }
162 }
163
164 // Return whether the static relocation needs to be applied.
165 inline bool
166 should_apply_static_reloc(const Sized_symbol<32>* gsym,
167 bool is_absolute_ref,
168 bool is_function_call,
169 bool is_32bit);
170
171 // Do a relocation. Return false if the caller should not issue
172 // any warnings about this relocation.
173 inline bool
174 relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum,
175 const elfcpp::Rel<32, false>&,
176 unsigned int r_type, const Sized_symbol<32>*,
177 const Symbol_value<32>*,
178 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
179 off_t);
180
181 private:
182 // Do a TLS relocation.
183 inline void
184 relocate_tls(const Relocate_info<32, false>*, Target_i386* target,
185 size_t relnum, const elfcpp::Rel<32, false>&,
186 unsigned int r_type, const Sized_symbol<32>*,
187 const Symbol_value<32>*,
188 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t);
189
190 // Do a TLS General-Dynamic to Initial-Exec transition.
191 inline void
192 tls_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
193 Output_segment* tls_segment,
194 const elfcpp::Rel<32, false>&, unsigned int r_type,
195 elfcpp::Elf_types<32>::Elf_Addr value,
196 unsigned char* view,
197 off_t view_size);
198
199 // Do a TLS General-Dynamic to Local-Exec transition.
200 inline void
201 tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
202 Output_segment* tls_segment,
203 const elfcpp::Rel<32, false>&, unsigned int r_type,
204 elfcpp::Elf_types<32>::Elf_Addr value,
205 unsigned char* view,
206 off_t view_size);
207
208 // Do a TLS Local-Dynamic to Local-Exec transition.
209 inline void
210 tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum,
211 Output_segment* tls_segment,
212 const elfcpp::Rel<32, false>&, unsigned int r_type,
213 elfcpp::Elf_types<32>::Elf_Addr value,
214 unsigned char* view,
215 off_t view_size);
216
217 // Do a TLS Initial-Exec to Local-Exec transition.
218 static inline void
219 tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum,
220 Output_segment* tls_segment,
221 const elfcpp::Rel<32, false>&, unsigned int r_type,
222 elfcpp::Elf_types<32>::Elf_Addr value,
223 unsigned char* view,
224 off_t view_size);
225
226 // We need to keep track of which type of local dynamic relocation
227 // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
228 enum Local_dynamic_type
229 {
230 LOCAL_DYNAMIC_NONE,
231 LOCAL_DYNAMIC_SUN,
232 LOCAL_DYNAMIC_GNU
233 };
234
235 // This is set if we should skip the next reloc, which should be a
236 // PLT32 reloc against ___tls_get_addr.
237 bool skip_call_tls_get_addr_;
238 // The type of local dynamic relocation we have seen in the section
239 // being relocated, if any.
240 Local_dynamic_type local_dynamic_type_;
241 };
242
243 // Adjust TLS relocation type based on the options and whether this
244 // is a local symbol.
245 static tls::Tls_optimization
246 optimize_tls_reloc(bool is_final, int r_type);
247
248 // Get the GOT section, creating it if necessary.
249 Output_data_got<32, false>*
250 got_section(Symbol_table*, Layout*);
251
252 // Get the GOT PLT section.
253 Output_data_space*
254 got_plt_section() const
255 {
256 gold_assert(this->got_plt_ != NULL);
257 return this->got_plt_;
258 }
259
260 // Create a PLT entry for a global symbol.
261 void
262 make_plt_entry(Symbol_table*, Layout*, Symbol*);
263
264 // Get the PLT section.
265 const Output_data_plt_i386*
266 plt_section() const
267 {
268 gold_assert(this->plt_ != NULL);
269 return this->plt_;
270 }
271
272 // Get the dynamic reloc section, creating it if necessary.
273 Reloc_section*
274 rel_dyn_section(Layout*);
275
276 // Return true if the symbol may need a COPY relocation.
277 // References from an executable object to non-function symbols
278 // defined in a dynamic object may need a COPY relocation.
279 bool
280 may_need_copy_reloc(Symbol* gsym)
281 {
282 return (!parameters->output_is_shared()
283 && gsym->is_from_dynobj()
284 && gsym->type() != elfcpp::STT_FUNC);
285 }
286
287 // Copy a relocation against a global symbol.
288 void
289 copy_reloc(const General_options*, Symbol_table*, Layout*,
290 Sized_relobj<32, false>*, unsigned int,
291 Output_section*, Symbol*, const elfcpp::Rel<32, false>&);
292
293 // Information about this specific target which we pass to the
294 // general Target structure.
295 static const Target::Target_info i386_info;
296
297 // The GOT section.
298 Output_data_got<32, false>* got_;
299 // The PLT section.
300 Output_data_plt_i386* plt_;
301 // The GOT PLT section.
302 Output_data_space* got_plt_;
303 // The dynamic reloc section.
304 Reloc_section* rel_dyn_;
305 // Relocs saved to avoid a COPY reloc.
306 Copy_relocs<32, false>* copy_relocs_;
307 // Space for variables copied with a COPY reloc.
308 Output_data_space* dynbss_;
309 };
310
311 const Target::Target_info Target_i386::i386_info =
312 {
313 32, // size
314 false, // is_big_endian
315 elfcpp::EM_386, // machine_code
316 false, // has_make_symbol
317 false, // has_resolve
318 true, // has_code_fill
319 true, // is_default_stack_executable
320 "/usr/lib/libc.so.1", // dynamic_linker
321 0x08048000, // default_text_segment_address
322 0x1000, // abi_pagesize
323 0x1000 // common_pagesize
324 };
325
326 // Get the GOT section, creating it if necessary.
327
328 Output_data_got<32, false>*
329 Target_i386::got_section(Symbol_table* symtab, Layout* layout)
330 {
331 if (this->got_ == NULL)
332 {
333 gold_assert(symtab != NULL && layout != NULL);
334
335 this->got_ = new Output_data_got<32, false>();
336
337 layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
338 elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
339 this->got_);
340
341 // The old GNU linker creates a .got.plt section. We just
342 // create another set of data in the .got section. Note that we
343 // always create a PLT if we create a GOT, although the PLT
344 // might be empty.
345 this->got_plt_ = new Output_data_space(4);
346 layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
347 elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
348 this->got_plt_);
349
350 // The first three entries are reserved.
351 this->got_plt_->set_current_data_size(3 * 4);
352
353 // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
354 symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL,
355 this->got_plt_,
356 0, 0, elfcpp::STT_OBJECT,
357 elfcpp::STB_LOCAL,
358 elfcpp::STV_HIDDEN, 0,
359 false, false);
360 }
361
362 return this->got_;
363 }
364
365 // Get the dynamic reloc section, creating it if necessary.
366
367 Target_i386::Reloc_section*
368 Target_i386::rel_dyn_section(Layout* layout)
369 {
370 if (this->rel_dyn_ == NULL)
371 {
372 gold_assert(layout != NULL);
373 this->rel_dyn_ = new Reloc_section();
374 layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
375 elfcpp::SHF_ALLOC, this->rel_dyn_);
376 }
377 return this->rel_dyn_;
378 }
379
380 // A class to handle the PLT data.
381
382 class Output_data_plt_i386 : public Output_section_data
383 {
384 public:
385 typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
386
387 Output_data_plt_i386(Layout*, Output_data_space*);
388
389 // Add an entry to the PLT.
390 void
391 add_entry(Symbol* gsym);
392
393 // Return the .rel.plt section data.
394 const Reloc_section*
395 rel_plt() const
396 { return this->rel_; }
397
398 protected:
399 void
400 do_adjust_output_section(Output_section* os);
401
402 private:
403 // The size of an entry in the PLT.
404 static const int plt_entry_size = 16;
405
406 // The first entry in the PLT for an executable.
407 static unsigned char exec_first_plt_entry[plt_entry_size];
408
409 // The first entry in the PLT for a shared object.
410 static unsigned char dyn_first_plt_entry[plt_entry_size];
411
412 // Other entries in the PLT for an executable.
413 static unsigned char exec_plt_entry[plt_entry_size];
414
415 // Other entries in the PLT for a shared object.
416 static unsigned char dyn_plt_entry[plt_entry_size];
417
418 // Set the final size.
419 void
420 set_final_data_size()
421 { this->set_data_size((this->count_ + 1) * plt_entry_size); }
422
423 // Write out the PLT data.
424 void
425 do_write(Output_file*);
426
427 // The reloc section.
428 Reloc_section* rel_;
429 // The .got.plt section.
430 Output_data_space* got_plt_;
431 // The number of PLT entries.
432 unsigned int count_;
433 };
434
435 // Create the PLT section. The ordinary .got section is an argument,
436 // since we need to refer to the start. We also create our own .got
437 // section just for PLT entries.
438
439 Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
440 Output_data_space* got_plt)
441 : Output_section_data(4), got_plt_(got_plt), count_(0)
442 {
443 this->rel_ = new Reloc_section();
444 layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
445 elfcpp::SHF_ALLOC, this->rel_);
446 }
447
448 void
449 Output_data_plt_i386::do_adjust_output_section(Output_section* os)
450 {
451 // UnixWare sets the entsize of .plt to 4, and so does the old GNU
452 // linker, and so do we.
453 os->set_entsize(4);
454 }
455
456 // Add an entry to the PLT.
457
458 void
459 Output_data_plt_i386::add_entry(Symbol* gsym)
460 {
461 gold_assert(!gsym->has_plt_offset());
462
463 // Note that when setting the PLT offset we skip the initial
464 // reserved PLT entry.
465 gsym->set_plt_offset((this->count_ + 1) * plt_entry_size);
466
467 ++this->count_;
468
469 off_t got_offset = this->got_plt_->current_data_size();
470
471 // Every PLT entry needs a GOT entry which points back to the PLT
472 // entry (this will be changed by the dynamic linker, normally
473 // lazily when the function is called).
474 this->got_plt_->set_current_data_size(got_offset + 4);
475
476 // Every PLT entry needs a reloc.
477 gsym->set_needs_dynsym_entry();
478 this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
479 got_offset);
480
481 // Note that we don't need to save the symbol. The contents of the
482 // PLT are independent of which symbols are used. The symbols only
483 // appear in the relocations.
484 }
485
486 // The first entry in the PLT for an executable.
487
488 unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] =
489 {
490 0xff, 0x35, // pushl contents of memory address
491 0, 0, 0, 0, // replaced with address of .got + 4
492 0xff, 0x25, // jmp indirect
493 0, 0, 0, 0, // replaced with address of .got + 8
494 0, 0, 0, 0 // unused
495 };
496
497 // The first entry in the PLT for a shared object.
498
499 unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] =
500 {
501 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
502 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx)
503 0, 0, 0, 0 // unused
504 };
505
506 // Subsequent entries in the PLT for an executable.
507
508 unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] =
509 {
510 0xff, 0x25, // jmp indirect
511 0, 0, 0, 0, // replaced with address of symbol in .got
512 0x68, // pushl immediate
513 0, 0, 0, 0, // replaced with offset into relocation table
514 0xe9, // jmp relative
515 0, 0, 0, 0 // replaced with offset to start of .plt
516 };
517
518 // Subsequent entries in the PLT for a shared object.
519
520 unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] =
521 {
522 0xff, 0xa3, // jmp *offset(%ebx)
523 0, 0, 0, 0, // replaced with offset of symbol in .got
524 0x68, // pushl immediate
525 0, 0, 0, 0, // replaced with offset into relocation table
526 0xe9, // jmp relative
527 0, 0, 0, 0 // replaced with offset to start of .plt
528 };
529
530 // Write out the PLT. This uses the hand-coded instructions above,
531 // and adjusts them as needed. This is all specified by the i386 ELF
532 // Processor Supplement.
533
534 void
535 Output_data_plt_i386::do_write(Output_file* of)
536 {
537 const off_t offset = this->offset();
538 const off_t oview_size = this->data_size();
539 unsigned char* const oview = of->get_output_view(offset, oview_size);
540
541 const off_t got_file_offset = this->got_plt_->offset();
542 const off_t got_size = this->got_plt_->data_size();
543 unsigned char* const got_view = of->get_output_view(got_file_offset,
544 got_size);
545
546 unsigned char* pov = oview;
547
548 elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
549 elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
550
551 if (parameters->output_is_shared())
552 memcpy(pov, dyn_first_plt_entry, plt_entry_size);
553 else
554 {
555 memcpy(pov, exec_first_plt_entry, plt_entry_size);
556 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
557 elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
558 }
559 pov += plt_entry_size;
560
561 unsigned char* got_pov = got_view;
562
563 memset(got_pov, 0, 12);
564 got_pov += 12;
565
566 const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
567
568 unsigned int plt_offset = plt_entry_size;
569 unsigned int plt_rel_offset = 0;
570 unsigned int got_offset = 12;
571 const unsigned int count = this->count_;
572 for (unsigned int i = 0;
573 i < count;
574 ++i,
575 pov += plt_entry_size,
576 got_pov += 4,
577 plt_offset += plt_entry_size,
578 plt_rel_offset += rel_size,
579 got_offset += 4)
580 {
581 // Set and adjust the PLT entry itself.
582
583 if (parameters->output_is_shared())
584 {
585 memcpy(pov, dyn_plt_entry, plt_entry_size);
586 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
587 }
588 else
589 {
590 memcpy(pov, exec_plt_entry, plt_entry_size);
591 elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
592 (got_address
593 + got_offset));
594 }
595
596 elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
597 elfcpp::Swap<32, false>::writeval(pov + 12,
598 - (plt_offset + plt_entry_size));
599
600 // Set the entry in the GOT.
601 elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
602 }
603
604 gold_assert(pov - oview == oview_size);
605 gold_assert(got_pov - got_view == got_size);
606
607 of->write_output_view(offset, oview_size, oview);
608 of->write_output_view(got_file_offset, got_size, got_view);
609 }
610
611 // Create a PLT entry for a global symbol.
612
613 void
614 Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym)
615 {
616 if (gsym->has_plt_offset())
617 return;
618
619 if (this->plt_ == NULL)
620 {
621 // Create the GOT sections first.
622 this->got_section(symtab, layout);
623
624 this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
625 layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
626 (elfcpp::SHF_ALLOC
627 | elfcpp::SHF_EXECINSTR),
628 this->plt_);
629 }
630
631 this->plt_->add_entry(gsym);
632 }
633
634 // Handle a relocation against a non-function symbol defined in a
635 // dynamic object. The traditional way to handle this is to generate
636 // a COPY relocation to copy the variable at runtime from the shared
637 // object into the executable's data segment. However, this is
638 // undesirable in general, as if the size of the object changes in the
639 // dynamic object, the executable will no longer work correctly. If
640 // this relocation is in a writable section, then we can create a
641 // dynamic reloc and the dynamic linker will resolve it to the correct
642 // address at runtime. However, we do not want do that if the
643 // relocation is in a read-only section, as it would prevent the
644 // readonly segment from being shared. And if we have to eventually
645 // generate a COPY reloc, then any dynamic relocations will be
646 // useless. So this means that if this is a writable section, we need
647 // to save the relocation until we see whether we have to create a
648 // COPY relocation for this symbol for any other relocation.
649
650 void
651 Target_i386::copy_reloc(const General_options* options,
652 Symbol_table* symtab,
653 Layout* layout,
654 Sized_relobj<32, false>* object,
655 unsigned int data_shndx,
656 Output_section* output_section,
657 Symbol* gsym,
658 const elfcpp::Rel<32, false>& rel)
659 {
660 Sized_symbol<32>* ssym;
661 ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
662 SELECT_SIZE(32));
663
664 if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
665 data_shndx, ssym))
666 {
667 // So far we do not need a COPY reloc. Save this relocation.
668 // If it turns out that we never need a COPY reloc for this
669 // symbol, then we will emit the relocation.
670 if (this->copy_relocs_ == NULL)
671 this->copy_relocs_ = new Copy_relocs<32, false>();
672 this->copy_relocs_->save(ssym, object, data_shndx, output_section, rel);
673 }
674 else
675 {
676 // Allocate space for this symbol in the .bss section.
677
678 elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
679
680 // There is no defined way to determine the required alignment
681 // of the symbol. We pick the alignment based on the size. We
682 // set an arbitrary maximum of 256.
683 unsigned int align;
684 for (align = 1; align < 512; align <<= 1)
685 if ((symsize & align) != 0)
686 break;
687
688 if (this->dynbss_ == NULL)
689 {
690 this->dynbss_ = new Output_data_space(align);
691 layout->add_output_section_data(".bss",
692 elfcpp::SHT_NOBITS,
693 (elfcpp::SHF_ALLOC
694 | elfcpp::SHF_WRITE),
695 this->dynbss_);
696 }
697
698 Output_data_space* dynbss = this->dynbss_;
699
700 if (align > dynbss->addralign())
701 dynbss->set_space_alignment(align);
702
703 off_t dynbss_size = dynbss->current_data_size();
704 dynbss_size = align_address(dynbss_size, align);
705 off_t offset = dynbss_size;
706 dynbss->set_current_data_size(dynbss_size + symsize);
707
708 symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
709
710 // Add the COPY reloc.
711 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
712 rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
713 }
714 }
715
716 // Optimize the TLS relocation type based on what we know about the
717 // symbol. IS_FINAL is true if the final address of this symbol is
718 // known at link time.
719
720 tls::Tls_optimization
721 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
722 {
723 // If we are generating a shared library, then we can't do anything
724 // in the linker.
725 if (parameters->output_is_shared())
726 return tls::TLSOPT_NONE;
727
728 switch (r_type)
729 {
730 case elfcpp::R_386_TLS_GD:
731 case elfcpp::R_386_TLS_GOTDESC:
732 case elfcpp::R_386_TLS_DESC_CALL:
733 // These are General-Dynamic which permits fully general TLS
734 // access. Since we know that we are generating an executable,
735 // we can convert this to Initial-Exec. If we also know that
736 // this is a local symbol, we can further switch to Local-Exec.
737 if (is_final)
738 return tls::TLSOPT_TO_LE;
739 return tls::TLSOPT_TO_IE;
740
741 case elfcpp::R_386_TLS_LDM:
742 // This is Local-Dynamic, which refers to a local symbol in the
743 // dynamic TLS block. Since we know that we generating an
744 // executable, we can switch to Local-Exec.
745 return tls::TLSOPT_TO_LE;
746
747 case elfcpp::R_386_TLS_LDO_32:
748 // Another type of Local-Dynamic relocation.
749 return tls::TLSOPT_TO_LE;
750
751 case elfcpp::R_386_TLS_IE:
752 case elfcpp::R_386_TLS_GOTIE:
753 case elfcpp::R_386_TLS_IE_32:
754 // These are Initial-Exec relocs which get the thread offset
755 // from the GOT. If we know that we are linking against the
756 // local symbol, we can switch to Local-Exec, which links the
757 // thread offset into the instruction.
758 if (is_final)
759 return tls::TLSOPT_TO_LE;
760 return tls::TLSOPT_NONE;
761
762 case elfcpp::R_386_TLS_LE:
763 case elfcpp::R_386_TLS_LE_32:
764 // When we already have Local-Exec, there is nothing further we
765 // can do.
766 return tls::TLSOPT_NONE;
767
768 default:
769 gold_unreachable();
770 }
771 }
772
773 // Report an unsupported relocation against a local symbol.
774
775 void
776 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
777 unsigned int r_type)
778 {
779 gold_error(_("%s: unsupported reloc %u against local symbol"),
780 object->name().c_str(), r_type);
781 }
782
783 // Scan a relocation for a local symbol.
784
785 inline void
786 Target_i386::Scan::local(const General_options&,
787 Symbol_table* symtab,
788 Layout* layout,
789 Target_i386* target,
790 Sized_relobj<32, false>* object,
791 unsigned int data_shndx,
792 Output_section* output_section,
793 const elfcpp::Rel<32, false>& reloc,
794 unsigned int r_type,
795 const elfcpp::Sym<32, false>&)
796 {
797 switch (r_type)
798 {
799 case elfcpp::R_386_NONE:
800 case elfcpp::R_386_GNU_VTINHERIT:
801 case elfcpp::R_386_GNU_VTENTRY:
802 break;
803
804 case elfcpp::R_386_32:
805 // If building a shared library (or a position-independent
806 // executable), we need to create a dynamic relocation for
807 // this location. The relocation applied at link time will
808 // apply the link-time value, so we flag the location with
809 // an R_386_RELATIVE relocation so the dynamic loader can
810 // relocate it easily.
811 if (parameters->output_is_position_independent())
812 {
813 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
814 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, output_section,
815 data_shndx, reloc.get_r_offset());
816 }
817 break;
818
819 case elfcpp::R_386_16:
820 case elfcpp::R_386_8:
821 // If building a shared library (or a position-independent
822 // executable), we need to create a dynamic relocation for
823 // this location. Because the addend needs to remain in the
824 // data section, we need to be careful not to apply this
825 // relocation statically.
826 if (parameters->output_is_position_independent())
827 {
828 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
829 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
830 rel_dyn->add_local(object, r_sym, r_type, output_section, data_shndx,
831 reloc.get_r_offset());
832 }
833 break;
834
835 case elfcpp::R_386_PC32:
836 case elfcpp::R_386_PC16:
837 case elfcpp::R_386_PC8:
838 break;
839
840 case elfcpp::R_386_PLT32:
841 // Since we know this is a local symbol, we can handle this as a
842 // PC32 reloc.
843 break;
844
845 case elfcpp::R_386_GOTOFF:
846 case elfcpp::R_386_GOTPC:
847 // We need a GOT section.
848 target->got_section(symtab, layout);
849 break;
850
851 case elfcpp::R_386_GOT32:
852 {
853 // The symbol requires a GOT entry.
854 Output_data_got<32, false>* got = target->got_section(symtab, layout);
855 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
856 if (got->add_local(object, r_sym))
857 {
858 // If we are generating a shared object, we need to add a
859 // dynamic RELATIVE relocation for this symbol.
860 if (parameters->output_is_position_independent())
861 {
862 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
863 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
864 output_section, data_shndx,
865 reloc.get_r_offset());
866 }
867 }
868 }
869 break;
870
871 // These are relocations which should only be seen by the
872 // dynamic linker, and should never be seen here.
873 case elfcpp::R_386_COPY:
874 case elfcpp::R_386_GLOB_DAT:
875 case elfcpp::R_386_JUMP_SLOT:
876 case elfcpp::R_386_RELATIVE:
877 case elfcpp::R_386_TLS_TPOFF:
878 case elfcpp::R_386_TLS_DTPMOD32:
879 case elfcpp::R_386_TLS_DTPOFF32:
880 case elfcpp::R_386_TLS_TPOFF32:
881 case elfcpp::R_386_TLS_DESC:
882 gold_error(_("%s: unexpected reloc %u in object file"),
883 object->name().c_str(), r_type);
884 break;
885
886 // These are initial TLS relocs, which are expected when
887 // linking.
888 case elfcpp::R_386_TLS_GD: // Global-dynamic
889 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
890 case elfcpp::R_386_TLS_DESC_CALL:
891 case elfcpp::R_386_TLS_LDM: // Local-dynamic
892 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
893 case elfcpp::R_386_TLS_IE: // Initial-exec
894 case elfcpp::R_386_TLS_IE_32:
895 case elfcpp::R_386_TLS_GOTIE:
896 case elfcpp::R_386_TLS_LE: // Local-exec
897 case elfcpp::R_386_TLS_LE_32:
898 {
899 bool output_is_shared = parameters->output_is_shared();
900 const tls::Tls_optimization optimized_type
901 = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
902 switch (r_type)
903 {
904 case elfcpp::R_386_TLS_GD: // Global-dynamic
905 if (optimized_type == tls::TLSOPT_NONE)
906 {
907 // Create a pair of GOT entries for the module index and
908 // dtv-relative offset.
909 Output_data_got<32, false>* got
910 = target->got_section(symtab, layout);
911 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
912 if (got->add_local_tls(object, r_sym, true))
913 {
914 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
915 unsigned int got_off
916 = object->local_tls_got_offset(r_sym, true);
917 rel_dyn->add_local(object, r_sym,
918 elfcpp::R_386_TLS_DTPMOD32,
919 got, got_off);
920 rel_dyn->add_local(object, r_sym,
921 elfcpp::R_386_TLS_DTPOFF32,
922 got, got_off + 4);
923 }
924 }
925 else if (optimized_type != tls::TLSOPT_TO_LE)
926 unsupported_reloc_local(object, r_type);
927 break;
928
929 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva)
930 case elfcpp::R_386_TLS_DESC_CALL:
931 unsupported_reloc_local(object, r_type);
932 break;
933
934 case elfcpp::R_386_TLS_LDM: // Local-dynamic
935 if (optimized_type == tls::TLSOPT_NONE)
936 {
937 // Create a GOT entry for the module index.
938 Output_data_got<32, false>* got
939 = target->got_section(symtab, layout);
940 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
941 if (got->add_local_tls(object, r_sym, false))
942 {
943 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
944 unsigned int got_off
945 = object->local_tls_got_offset(r_sym, false);
946 rel_dyn->add_local(object, r_sym,
947 elfcpp::R_386_TLS_DTPMOD32, got,
948 got_off);
949 }
950 }
951 else if (optimized_type != tls::TLSOPT_TO_LE)
952 unsupported_reloc_local(object, r_type);
953 break;
954
955 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
956 break;
957
958 case elfcpp::R_386_TLS_IE: // Initial-exec
959 case elfcpp::R_386_TLS_IE_32:
960 case elfcpp::R_386_TLS_GOTIE:
961 if (optimized_type == tls::TLSOPT_NONE)
962 {
963 // Create a GOT entry for the tp-relative offset.
964 Output_data_got<32, false>* got
965 = target->got_section(symtab, layout);
966 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
967 if (got->add_local(object, r_sym))
968 {
969 unsigned int dyn_r_type
970 = (r_type == elfcpp::R_386_TLS_IE_32
971 ? elfcpp::R_386_TLS_TPOFF32
972 : elfcpp::R_386_TLS_TPOFF);
973 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
974 unsigned int got_off = object->local_got_offset(r_sym);
975 rel_dyn->add_local(object, r_sym, dyn_r_type, got,
976 got_off);
977 }
978 }
979 else if (optimized_type != tls::TLSOPT_TO_LE)
980 unsupported_reloc_local(object, r_type);
981 break;
982
983 case elfcpp::R_386_TLS_LE: // Local-exec
984 case elfcpp::R_386_TLS_LE_32:
985 if (output_is_shared)
986 unsupported_reloc_local(object, r_type);
987 break;
988
989 default:
990 gold_unreachable();
991 }
992 }
993 break;
994
995 case elfcpp::R_386_32PLT:
996 case elfcpp::R_386_TLS_GD_32:
997 case elfcpp::R_386_TLS_GD_PUSH:
998 case elfcpp::R_386_TLS_GD_CALL:
999 case elfcpp::R_386_TLS_GD_POP:
1000 case elfcpp::R_386_TLS_LDM_32:
1001 case elfcpp::R_386_TLS_LDM_PUSH:
1002 case elfcpp::R_386_TLS_LDM_CALL:
1003 case elfcpp::R_386_TLS_LDM_POP:
1004 case elfcpp::R_386_USED_BY_INTEL_200:
1005 default:
1006 unsupported_reloc_local(object, r_type);
1007 break;
1008 }
1009 }
1010
1011 // Report an unsupported relocation against a global symbol.
1012
1013 void
1014 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
1015 unsigned int r_type,
1016 Symbol* gsym)
1017 {
1018 gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1019 object->name().c_str(), r_type, gsym->demangled_name().c_str());
1020 }
1021
1022 // Scan a relocation for a global symbol.
1023
1024 inline void
1025 Target_i386::Scan::global(const General_options& options,
1026 Symbol_table* symtab,
1027 Layout* layout,
1028 Target_i386* target,
1029 Sized_relobj<32, false>* object,
1030 unsigned int data_shndx,
1031 Output_section* output_section,
1032 const elfcpp::Rel<32, false>& reloc,
1033 unsigned int r_type,
1034 Symbol* gsym)
1035 {
1036 switch (r_type)
1037 {
1038 case elfcpp::R_386_NONE:
1039 case elfcpp::R_386_GNU_VTINHERIT:
1040 case elfcpp::R_386_GNU_VTENTRY:
1041 break;
1042
1043 case elfcpp::R_386_32:
1044 case elfcpp::R_386_16:
1045 case elfcpp::R_386_8:
1046 {
1047 // Make a PLT entry if necessary.
1048 if (gsym->needs_plt_entry())
1049 {
1050 target->make_plt_entry(symtab, layout, gsym);
1051 // Since this is not a PC-relative relocation, we may be
1052 // taking the address of a function. In that case we need to
1053 // set the entry in the dynamic symbol table to the address of
1054 // the PLT entry.
1055 if (gsym->is_from_dynobj())
1056 gsym->set_needs_dynsym_value();
1057 }
1058 // Make a dynamic relocation if necessary.
1059 if (gsym->needs_dynamic_reloc(true, false))
1060 {
1061 if (target->may_need_copy_reloc(gsym))
1062 {
1063 target->copy_reloc(&options, symtab, layout, object,
1064 data_shndx, output_section, gsym, reloc);
1065 }
1066 else if (r_type == elfcpp::R_386_32
1067 && gsym->can_use_relative_reloc(false))
1068 {
1069 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1070 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
1071 output_section, data_shndx,
1072 reloc.get_r_offset());
1073 }
1074 else
1075 {
1076 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1077 rel_dyn->add_global(gsym, r_type, output_section, object,
1078 data_shndx, reloc.get_r_offset());
1079 }
1080 }
1081 }
1082 break;
1083
1084 case elfcpp::R_386_PC32:
1085 case elfcpp::R_386_PC16:
1086 case elfcpp::R_386_PC8:
1087 {
1088 // Make a PLT entry if necessary.
1089 if (gsym->needs_plt_entry())
1090 target->make_plt_entry(symtab, layout, gsym);
1091 // Make a dynamic relocation if necessary.
1092 bool is_function_call = (gsym->type() == elfcpp::STT_FUNC);
1093 if (gsym->needs_dynamic_reloc(false, is_function_call))
1094 {
1095 if (target->may_need_copy_reloc(gsym))
1096 {
1097 target->copy_reloc(&options, symtab, layout, object,
1098 data_shndx, output_section, gsym, reloc);
1099 }
1100 else
1101 {
1102 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1103 rel_dyn->add_global(gsym, r_type, output_section, object,
1104 data_shndx, reloc.get_r_offset());
1105 }
1106 }
1107 }
1108 break;
1109
1110 case elfcpp::R_386_GOT32:
1111 {
1112 // The symbol requires a GOT entry.
1113 Output_data_got<32, false>* got = target->got_section(symtab, layout);
1114 if (got->add_global(gsym))
1115 {
1116 // If this symbol is not fully resolved, we need to add a
1117 // dynamic relocation for it.
1118 if (!gsym->final_value_is_known())
1119 {
1120 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1121 if (gsym->is_from_dynobj()
1122 || gsym->is_preemptible())
1123 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
1124 gsym->got_offset());
1125 else
1126 {
1127 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
1128 got, gsym->got_offset());
1129 // Make sure we write the link-time value to the GOT.
1130 gsym->set_needs_value_in_got();
1131 }
1132 }
1133 }
1134 }
1135 break;
1136
1137 case elfcpp::R_386_PLT32:
1138 // If the symbol is fully resolved, this is just a PC32 reloc.
1139 // Otherwise we need a PLT entry.
1140 if (gsym->final_value_is_known())
1141 break;
1142 // If building a shared library, we can also skip the PLT entry
1143 // if the symbol is defined in the output file and is protected
1144 // or hidden.
1145 if (gsym->is_defined()
1146 && !gsym->is_from_dynobj()
1147 && !gsym->is_preemptible())
1148 break;
1149 target->make_plt_entry(symtab, layout, gsym);
1150 break;
1151
1152 case elfcpp::R_386_GOTOFF:
1153 case elfcpp::R_386_GOTPC:
1154 // We need a GOT section.
1155 target->got_section(symtab, layout);
1156 break;
1157
1158 // These are relocations which should only be seen by the
1159 // dynamic linker, and should never be seen here.
1160 case elfcpp::R_386_COPY:
1161 case elfcpp::R_386_GLOB_DAT:
1162 case elfcpp::R_386_JUMP_SLOT:
1163 case elfcpp::R_386_RELATIVE:
1164 case elfcpp::R_386_TLS_TPOFF:
1165 case elfcpp::R_386_TLS_DTPMOD32:
1166 case elfcpp::R_386_TLS_DTPOFF32:
1167 case elfcpp::R_386_TLS_TPOFF32:
1168 case elfcpp::R_386_TLS_DESC:
1169 gold_error(_("%s: unexpected reloc %u in object file"),
1170 object->name().c_str(), r_type);
1171 break;
1172
1173 // These are initial tls relocs, which are expected when
1174 // linking.
1175 case elfcpp::R_386_TLS_GD: // Global-dynamic
1176 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1177 case elfcpp::R_386_TLS_DESC_CALL:
1178 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1179 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1180 case elfcpp::R_386_TLS_IE: // Initial-exec
1181 case elfcpp::R_386_TLS_IE_32:
1182 case elfcpp::R_386_TLS_GOTIE:
1183 case elfcpp::R_386_TLS_LE: // Local-exec
1184 case elfcpp::R_386_TLS_LE_32:
1185 {
1186 const bool is_final = gsym->final_value_is_known();
1187 const tls::Tls_optimization optimized_type
1188 = Target_i386::optimize_tls_reloc(is_final, r_type);
1189 switch (r_type)
1190 {
1191 case elfcpp::R_386_TLS_GD: // Global-dynamic
1192 if (optimized_type == tls::TLSOPT_NONE)
1193 {
1194 // Create a pair of GOT entries for the module index and
1195 // dtv-relative offset.
1196 Output_data_got<32, false>* got
1197 = target->got_section(symtab, layout);
1198 if (got->add_global_tls(gsym, true))
1199 {
1200 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1201 unsigned int got_off = gsym->tls_got_offset(true);
1202 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_DTPMOD32,
1203 got, got_off);
1204 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_DTPOFF32,
1205 got, got_off + 4);
1206 }
1207 }
1208 else if (optimized_type == tls::TLSOPT_TO_IE)
1209 {
1210 // Create a GOT entry for the tp-relative offset.
1211 Output_data_got<32, false>* got
1212 = target->got_section(symtab, layout);
1213 if (got->add_global(gsym))
1214 {
1215 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1216 unsigned int got_off = gsym->got_offset();
1217 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_TPOFF32,
1218 got, got_off);
1219 }
1220 }
1221 else if (optimized_type != tls::TLSOPT_TO_LE)
1222 unsupported_reloc_global(object, r_type, gsym);
1223 break;
1224
1225 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url)
1226 case elfcpp::R_386_TLS_DESC_CALL:
1227 unsupported_reloc_global(object, r_type, gsym);
1228 break;
1229
1230 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1231 // FIXME: If not relaxing to LE, we need to generate a
1232 // DTPMOD32 reloc.
1233 if (optimized_type == tls::TLSOPT_NONE)
1234 {
1235 // Create a GOT entry for the module index.
1236 Output_data_got<32, false>* got
1237 = target->got_section(symtab, layout);
1238 if (got->add_global_tls(gsym, false))
1239 {
1240 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1241 unsigned int got_off = gsym->tls_got_offset(false);
1242 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_DTPMOD32,
1243 got, got_off);
1244 }
1245 }
1246 else if (optimized_type != tls::TLSOPT_TO_LE)
1247 unsupported_reloc_global(object, r_type, gsym);
1248 break;
1249
1250 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1251 break;
1252
1253 case elfcpp::R_386_TLS_IE: // Initial-exec
1254 case elfcpp::R_386_TLS_IE_32:
1255 case elfcpp::R_386_TLS_GOTIE:
1256 if (optimized_type == tls::TLSOPT_NONE)
1257 {
1258 // Create a GOT entry for the tp-relative offset.
1259 Output_data_got<32, false>* got
1260 = target->got_section(symtab, layout);
1261 if (got->add_global(gsym))
1262 {
1263 unsigned int dyn_r_type
1264 = (r_type == elfcpp::R_386_TLS_IE_32
1265 ? elfcpp::R_386_TLS_TPOFF32
1266 : elfcpp::R_386_TLS_TPOFF);
1267 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1268 unsigned int got_off = gsym->got_offset();
1269 rel_dyn->add_global(gsym, dyn_r_type, got, got_off);
1270 }
1271 }
1272 else if (optimized_type != tls::TLSOPT_TO_LE)
1273 unsupported_reloc_global(object, r_type, gsym);
1274 break;
1275
1276 case elfcpp::R_386_TLS_LE: // Local-exec
1277 case elfcpp::R_386_TLS_LE_32:
1278 if (parameters->output_is_shared())
1279 unsupported_reloc_global(object, r_type, gsym);
1280 break;
1281
1282 default:
1283 gold_unreachable();
1284 }
1285 }
1286 break;
1287
1288 case elfcpp::R_386_32PLT:
1289 case elfcpp::R_386_TLS_GD_32:
1290 case elfcpp::R_386_TLS_GD_PUSH:
1291 case elfcpp::R_386_TLS_GD_CALL:
1292 case elfcpp::R_386_TLS_GD_POP:
1293 case elfcpp::R_386_TLS_LDM_32:
1294 case elfcpp::R_386_TLS_LDM_PUSH:
1295 case elfcpp::R_386_TLS_LDM_CALL:
1296 case elfcpp::R_386_TLS_LDM_POP:
1297 case elfcpp::R_386_USED_BY_INTEL_200:
1298 default:
1299 unsupported_reloc_global(object, r_type, gsym);
1300 break;
1301 }
1302 }
1303
1304 // Scan relocations for a section.
1305
1306 void
1307 Target_i386::scan_relocs(const General_options& options,
1308 Symbol_table* symtab,
1309 Layout* layout,
1310 Sized_relobj<32, false>* object,
1311 unsigned int data_shndx,
1312 unsigned int sh_type,
1313 const unsigned char* prelocs,
1314 size_t reloc_count,
1315 Output_section* output_section,
1316 bool needs_special_offset_handling,
1317 size_t local_symbol_count,
1318 const unsigned char* plocal_symbols)
1319 {
1320 if (sh_type == elfcpp::SHT_RELA)
1321 {
1322 gold_error(_("%s: unsupported RELA reloc section"),
1323 object->name().c_str());
1324 return;
1325 }
1326
1327 gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1328 Target_i386::Scan>(
1329 options,
1330 symtab,
1331 layout,
1332 this,
1333 object,
1334 data_shndx,
1335 prelocs,
1336 reloc_count,
1337 output_section,
1338 needs_special_offset_handling,
1339 local_symbol_count,
1340 plocal_symbols);
1341 }
1342
1343 // Finalize the sections.
1344
1345 void
1346 Target_i386::do_finalize_sections(Layout* layout)
1347 {
1348 // Fill in some more dynamic tags.
1349 Output_data_dynamic* const odyn = layout->dynamic_data();
1350 if (odyn != NULL)
1351 {
1352 if (this->got_plt_ != NULL)
1353 odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1354
1355 if (this->plt_ != NULL)
1356 {
1357 const Output_data* od = this->plt_->rel_plt();
1358 odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1359 odyn->add_section_address(elfcpp::DT_JMPREL, od);
1360 odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1361 }
1362
1363 if (this->rel_dyn_ != NULL)
1364 {
1365 const Output_data* od = this->rel_dyn_;
1366 odyn->add_section_address(elfcpp::DT_REL, od);
1367 odyn->add_section_size(elfcpp::DT_RELSZ, od);
1368 odyn->add_constant(elfcpp::DT_RELENT,
1369 elfcpp::Elf_sizes<32>::rel_size);
1370 }
1371
1372 if (!parameters->output_is_shared())
1373 {
1374 // The value of the DT_DEBUG tag is filled in by the dynamic
1375 // linker at run time, and used by the debugger.
1376 odyn->add_constant(elfcpp::DT_DEBUG, 0);
1377 }
1378 }
1379
1380 // Emit any relocs we saved in an attempt to avoid generating COPY
1381 // relocs.
1382 if (this->copy_relocs_ == NULL)
1383 return;
1384 if (this->copy_relocs_->any_to_emit())
1385 {
1386 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1387 this->copy_relocs_->emit(rel_dyn);
1388 }
1389 delete this->copy_relocs_;
1390 this->copy_relocs_ = NULL;
1391 }
1392
1393 // Return whether a direct absolute static relocation needs to be applied.
1394 // In cases where Scan::local() or Scan::global() has created
1395 // a dynamic relocation other than R_386_RELATIVE, the addend
1396 // of the relocation is carried in the data, and we must not
1397 // apply the static relocation.
1398
1399 inline bool
1400 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
1401 bool is_absolute_ref,
1402 bool is_function_call,
1403 bool is_32bit)
1404 {
1405 // For local symbols, we will have created a non-RELATIVE dynamic
1406 // relocation only if (a) the output is position independent,
1407 // (b) the relocation is absolute (not pc- or segment-relative), and
1408 // (c) the relocation is not 32 bits wide.
1409 if (gsym == NULL)
1410 return !(parameters->output_is_position_independent()
1411 && is_absolute_ref
1412 && !is_32bit);
1413
1414 // For global symbols, we use the same helper routines used in the scan pass.
1415 return !(gsym->needs_dynamic_reloc(is_absolute_ref, is_function_call)
1416 && !gsym->can_use_relative_reloc(is_function_call));
1417 }
1418
1419 // Perform a relocation.
1420
1421 inline bool
1422 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1423 Target_i386* target,
1424 size_t relnum,
1425 const elfcpp::Rel<32, false>& rel,
1426 unsigned int r_type,
1427 const Sized_symbol<32>* gsym,
1428 const Symbol_value<32>* psymval,
1429 unsigned char* view,
1430 elfcpp::Elf_types<32>::Elf_Addr address,
1431 off_t view_size)
1432 {
1433 if (this->skip_call_tls_get_addr_)
1434 {
1435 if (r_type != elfcpp::R_386_PLT32
1436 || gsym == NULL
1437 || strcmp(gsym->name(), "___tls_get_addr") != 0)
1438 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1439 _("missing expected TLS relocation"));
1440 else
1441 {
1442 this->skip_call_tls_get_addr_ = false;
1443 return false;
1444 }
1445 }
1446
1447 // Pick the value to use for symbols defined in shared objects.
1448 Symbol_value<32> symval;
1449 if (gsym != NULL
1450 && (gsym->is_from_dynobj()
1451 || (parameters->output_is_shared()
1452 && gsym->is_preemptible()))
1453 && gsym->has_plt_offset())
1454 {
1455 symval.set_output_value(target->plt_section()->address()
1456 + gsym->plt_offset());
1457 psymval = &symval;
1458 }
1459
1460 const Sized_relobj<32, false>* object = relinfo->object;
1461
1462 // Get the GOT offset if needed.
1463 // The GOT pointer points to the end of the GOT section.
1464 // We need to subtract the size of the GOT section to get
1465 // the actual offset to use in the relocation.
1466 bool have_got_offset = false;
1467 unsigned int got_offset = 0;
1468 switch (r_type)
1469 {
1470 case elfcpp::R_386_GOT32:
1471 if (gsym != NULL)
1472 {
1473 gold_assert(gsym->has_got_offset());
1474 got_offset = gsym->got_offset() - target->got_size();
1475 }
1476 else
1477 {
1478 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1479 gold_assert(object->local_has_got_offset(r_sym));
1480 got_offset = object->local_got_offset(r_sym) - target->got_size();
1481 }
1482 have_got_offset = true;
1483 break;
1484
1485 default:
1486 break;
1487 }
1488
1489 switch (r_type)
1490 {
1491 case elfcpp::R_386_NONE:
1492 case elfcpp::R_386_GNU_VTINHERIT:
1493 case elfcpp::R_386_GNU_VTENTRY:
1494 break;
1495
1496 case elfcpp::R_386_32:
1497 if (should_apply_static_reloc(gsym, true, false, true))
1498 Relocate_functions<32, false>::rel32(view, object, psymval);
1499 break;
1500
1501 case elfcpp::R_386_PC32:
1502 {
1503 bool is_function_call = (gsym != NULL
1504 && gsym->type() == elfcpp::STT_FUNC);
1505 if (should_apply_static_reloc(gsym, false, is_function_call, true))
1506 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1507 }
1508 break;
1509
1510 case elfcpp::R_386_16:
1511 if (should_apply_static_reloc(gsym, true, false, false))
1512 Relocate_functions<32, false>::rel16(view, object, psymval);
1513 break;
1514
1515 case elfcpp::R_386_PC16:
1516 {
1517 bool is_function_call = (gsym != NULL
1518 && gsym->type() == elfcpp::STT_FUNC);
1519 if (should_apply_static_reloc(gsym, false, is_function_call, false))
1520 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1521 }
1522 break;
1523
1524 case elfcpp::R_386_8:
1525 if (should_apply_static_reloc(gsym, true, false, false))
1526 Relocate_functions<32, false>::rel8(view, object, psymval);
1527 break;
1528
1529 case elfcpp::R_386_PC8:
1530 {
1531 bool is_function_call = (gsym != NULL
1532 && gsym->type() == elfcpp::STT_FUNC);
1533 if (should_apply_static_reloc(gsym, false, is_function_call, false))
1534 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1535 }
1536 break;
1537
1538 case elfcpp::R_386_PLT32:
1539 gold_assert(gsym == NULL
1540 || gsym->has_plt_offset()
1541 || gsym->final_value_is_known());
1542 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1543 break;
1544
1545 case elfcpp::R_386_GOT32:
1546 gold_assert(have_got_offset);
1547 Relocate_functions<32, false>::rel32(view, got_offset);
1548 break;
1549
1550 case elfcpp::R_386_GOTOFF:
1551 {
1552 elfcpp::Elf_types<32>::Elf_Addr value;
1553 value = (psymval->value(object, 0)
1554 - target->got_plt_section()->address());
1555 Relocate_functions<32, false>::rel32(view, value);
1556 }
1557 break;
1558
1559 case elfcpp::R_386_GOTPC:
1560 {
1561 elfcpp::Elf_types<32>::Elf_Addr value;
1562 value = target->got_plt_section()->address();
1563 Relocate_functions<32, false>::pcrel32(view, value, address);
1564 }
1565 break;
1566
1567 case elfcpp::R_386_COPY:
1568 case elfcpp::R_386_GLOB_DAT:
1569 case elfcpp::R_386_JUMP_SLOT:
1570 case elfcpp::R_386_RELATIVE:
1571 // These are outstanding tls relocs, which are unexpected when
1572 // linking.
1573 case elfcpp::R_386_TLS_TPOFF:
1574 case elfcpp::R_386_TLS_DTPMOD32:
1575 case elfcpp::R_386_TLS_DTPOFF32:
1576 case elfcpp::R_386_TLS_TPOFF32:
1577 case elfcpp::R_386_TLS_DESC:
1578 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1579 _("unexpected reloc %u in object file"),
1580 r_type);
1581 break;
1582
1583 // These are initial tls relocs, which are expected when
1584 // linking.
1585 case elfcpp::R_386_TLS_GD: // Global-dynamic
1586 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1587 case elfcpp::R_386_TLS_DESC_CALL:
1588 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1589 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1590 case elfcpp::R_386_TLS_IE: // Initial-exec
1591 case elfcpp::R_386_TLS_IE_32:
1592 case elfcpp::R_386_TLS_GOTIE:
1593 case elfcpp::R_386_TLS_LE: // Local-exec
1594 case elfcpp::R_386_TLS_LE_32:
1595 this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval,
1596 view, address, view_size);
1597 break;
1598
1599 case elfcpp::R_386_32PLT:
1600 case elfcpp::R_386_TLS_GD_32:
1601 case elfcpp::R_386_TLS_GD_PUSH:
1602 case elfcpp::R_386_TLS_GD_CALL:
1603 case elfcpp::R_386_TLS_GD_POP:
1604 case elfcpp::R_386_TLS_LDM_32:
1605 case elfcpp::R_386_TLS_LDM_PUSH:
1606 case elfcpp::R_386_TLS_LDM_CALL:
1607 case elfcpp::R_386_TLS_LDM_POP:
1608 case elfcpp::R_386_USED_BY_INTEL_200:
1609 default:
1610 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1611 _("unsupported reloc %u"),
1612 r_type);
1613 break;
1614 }
1615
1616 return true;
1617 }
1618
1619 // Perform a TLS relocation.
1620
1621 inline void
1622 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1623 Target_i386* target,
1624 size_t relnum,
1625 const elfcpp::Rel<32, false>& rel,
1626 unsigned int r_type,
1627 const Sized_symbol<32>* gsym,
1628 const Symbol_value<32>* psymval,
1629 unsigned char* view,
1630 elfcpp::Elf_types<32>::Elf_Addr,
1631 off_t view_size)
1632 {
1633 Output_segment* tls_segment = relinfo->layout->tls_segment();
1634
1635 const Sized_relobj<32, false>* object = relinfo->object;
1636
1637 elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0);
1638
1639 const bool is_final = (gsym == NULL
1640 ? !parameters->output_is_position_independent()
1641 : gsym->final_value_is_known());
1642 const tls::Tls_optimization optimized_type
1643 = Target_i386::optimize_tls_reloc(is_final, r_type);
1644 switch (r_type)
1645 {
1646 case elfcpp::R_386_TLS_GD: // Global-dynamic
1647 if (optimized_type == tls::TLSOPT_TO_LE)
1648 {
1649 gold_assert(tls_segment != NULL);
1650 this->tls_gd_to_le(relinfo, relnum, tls_segment,
1651 rel, r_type, value, view,
1652 view_size);
1653 break;
1654 }
1655 else
1656 {
1657 unsigned int got_offset;
1658 if (gsym != NULL)
1659 {
1660 gold_assert(gsym->has_tls_got_offset(true));
1661 got_offset = gsym->tls_got_offset(true) - target->got_size();
1662 }
1663 else
1664 {
1665 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1666 gold_assert(object->local_has_tls_got_offset(r_sym, true));
1667 got_offset = (object->local_tls_got_offset(r_sym, true)
1668 - target->got_size());
1669 }
1670 if (optimized_type == tls::TLSOPT_TO_IE)
1671 {
1672 gold_assert(tls_segment != NULL);
1673 this->tls_gd_to_ie(relinfo, relnum, tls_segment,
1674 rel, r_type, got_offset, view,
1675 view_size);
1676 break;
1677 }
1678 else if (optimized_type == tls::TLSOPT_NONE)
1679 {
1680 // Relocate the field with the offset of the pair of GOT
1681 // entries.
1682 Relocate_functions<32, false>::rel32(view, got_offset);
1683 break;
1684 }
1685 }
1686 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1687 _("unsupported reloc %u"),
1688 r_type);
1689 break;
1690
1691 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1692 case elfcpp::R_386_TLS_DESC_CALL:
1693 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1694 _("unsupported reloc %u"),
1695 r_type);
1696 break;
1697
1698 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1699 if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1700 {
1701 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1702 _("both SUN and GNU model "
1703 "TLS relocations"));
1704 break;
1705 }
1706 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1707 if (optimized_type == tls::TLSOPT_TO_LE)
1708 {
1709 gold_assert(tls_segment != NULL);
1710 this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1711 value, view, view_size);
1712 break;
1713 }
1714 else if (optimized_type == tls::TLSOPT_NONE)
1715 {
1716 // Relocate the field with the offset of the GOT entry for
1717 // the module index.
1718 unsigned int got_offset;
1719 if (gsym != NULL)
1720 {
1721 gold_assert(gsym->has_tls_got_offset(false));
1722 got_offset = gsym->tls_got_offset(false) - target->got_size();
1723 }
1724 else
1725 {
1726 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1727 gold_assert(object->local_has_tls_got_offset(r_sym, false));
1728 got_offset = (object->local_tls_got_offset(r_sym, false)
1729 - target->got_size());
1730 }
1731 Relocate_functions<32, false>::rel32(view, got_offset);
1732 break;
1733 }
1734 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1735 _("unsupported reloc %u"),
1736 r_type);
1737 break;
1738
1739 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1740 // This reloc can appear in debugging sections, in which case we
1741 // won't see the TLS_LDM reloc. The local_dynamic_type field
1742 // tells us this.
1743 gold_assert(tls_segment != NULL);
1744 if (optimized_type != tls::TLSOPT_TO_LE
1745 || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1746 value = value - tls_segment->vaddr();
1747 else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1748 value = value - (tls_segment->vaddr() + tls_segment->memsz());
1749 else
1750 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1751 Relocate_functions<32, false>::rel32(view, value);
1752 break;
1753
1754 case elfcpp::R_386_TLS_IE: // Initial-exec
1755 case elfcpp::R_386_TLS_GOTIE:
1756 case elfcpp::R_386_TLS_IE_32:
1757 if (optimized_type == tls::TLSOPT_TO_LE)
1758 {
1759 gold_assert(tls_segment != NULL);
1760 Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1761 rel, r_type, value, view,
1762 view_size);
1763 break;
1764 }
1765 else if (optimized_type == tls::TLSOPT_NONE)
1766 {
1767 // Relocate the field with the offset of the GOT entry for
1768 // the tp-relative offset of the symbol.
1769 unsigned int got_offset;
1770 if (gsym != NULL)
1771 {
1772 gold_assert(gsym->has_got_offset());
1773 got_offset = gsym->got_offset();
1774 }
1775 else
1776 {
1777 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1778 gold_assert(object->local_has_got_offset(r_sym));
1779 got_offset = object->local_got_offset(r_sym);
1780 }
1781 // For the R_386_TLS_IE relocation, we need to apply the
1782 // absolute address of the GOT entry.
1783 if (r_type == elfcpp::R_386_TLS_IE)
1784 got_offset += target->got_plt_section()->address();
1785 // All GOT offsets are relative to the end of the GOT.
1786 got_offset -= target->got_size();
1787 Relocate_functions<32, false>::rel32(view, got_offset);
1788 break;
1789 }
1790 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1791 _("unsupported reloc %u"),
1792 r_type);
1793 break;
1794
1795 case elfcpp::R_386_TLS_LE: // Local-exec
1796 gold_assert(tls_segment != NULL);
1797 value = value - (tls_segment->vaddr() + tls_segment->memsz());
1798 Relocate_functions<32, false>::rel32(view, value);
1799 break;
1800
1801 case elfcpp::R_386_TLS_LE_32:
1802 gold_assert(tls_segment != NULL);
1803 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1804 Relocate_functions<32, false>::rel32(view, value);
1805 break;
1806 }
1807 }
1808
1809 // Do a relocation in which we convert a TLS General-Dynamic to a
1810 // Local-Exec.
1811
1812 inline void
1813 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1814 size_t relnum,
1815 Output_segment* tls_segment,
1816 const elfcpp::Rel<32, false>& rel,
1817 unsigned int,
1818 elfcpp::Elf_types<32>::Elf_Addr value,
1819 unsigned char* view,
1820 off_t view_size)
1821 {
1822 // leal foo(,%reg,1),%eax; call ___tls_get_addr
1823 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1824 // leal foo(%reg),%eax; call ___tls_get_addr
1825 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1826
1827 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1828 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1829
1830 unsigned char op1 = view[-1];
1831 unsigned char op2 = view[-2];
1832
1833 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1834 op2 == 0x8d || op2 == 0x04);
1835 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1836
1837 int roff = 5;
1838
1839 if (op2 == 0x04)
1840 {
1841 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1842 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1843 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1844 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1845 memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1846 }
1847 else
1848 {
1849 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1850 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1851 if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1852 && view[9] == 0x90)
1853 {
1854 // There is a trailing nop. Use the size byte subl.
1855 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1856 roff = 6;
1857 }
1858 else
1859 {
1860 // Use the five byte subl.
1861 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1862 }
1863 }
1864
1865 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1866 Relocate_functions<32, false>::rel32(view + roff, value);
1867
1868 // The next reloc should be a PLT32 reloc against __tls_get_addr.
1869 // We can skip it.
1870 this->skip_call_tls_get_addr_ = true;
1871 }
1872
1873 // Do a relocation in which we convert a TLS General-Dynamic to a
1874 // Initial-Exec.
1875
1876 inline void
1877 Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
1878 size_t relnum,
1879 Output_segment* tls_segment,
1880 const elfcpp::Rel<32, false>& rel,
1881 unsigned int,
1882 elfcpp::Elf_types<32>::Elf_Addr value,
1883 unsigned char* view,
1884 off_t view_size)
1885 {
1886 // leal foo(,%ebx,1),%eax; call ___tls_get_addr
1887 // ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
1888
1889 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1890 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1891
1892 unsigned char op1 = view[-1];
1893 unsigned char op2 = view[-2];
1894
1895 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1896 op2 == 0x8d || op2 == 0x04);
1897 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1898
1899 int roff = 5;
1900
1901 // FIXME: For now, support only one form.
1902 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1903 op1 == 0x8d && op2 == 0x04);
1904
1905 if (op2 == 0x04)
1906 {
1907 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1908 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1909 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1910 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1911 memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
1912 }
1913 else
1914 {
1915 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1916 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1917 if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1918 && view[9] == 0x90)
1919 {
1920 // FIXME: This is not the right instruction sequence.
1921 // There is a trailing nop. Use the size byte subl.
1922 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1923 roff = 6;
1924 }
1925 else
1926 {
1927 // FIXME: This is not the right instruction sequence.
1928 // Use the five byte subl.
1929 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1930 }
1931 }
1932
1933 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1934 Relocate_functions<32, false>::rel32(view + roff, value);
1935
1936 // The next reloc should be a PLT32 reloc against __tls_get_addr.
1937 // We can skip it.
1938 this->skip_call_tls_get_addr_ = true;
1939 }
1940
1941 // Do a relocation in which we convert a TLS Local-Dynamic to a
1942 // Local-Exec.
1943
1944 inline void
1945 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1946 size_t relnum,
1947 Output_segment*,
1948 const elfcpp::Rel<32, false>& rel,
1949 unsigned int,
1950 elfcpp::Elf_types<32>::Elf_Addr,
1951 unsigned char* view,
1952 off_t view_size)
1953 {
1954 // leal foo(%reg), %eax; call ___tls_get_addr
1955 // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1956
1957 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1958 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1959
1960 // FIXME: Does this test really always pass?
1961 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1962 view[-2] == 0x8d && view[-1] == 0x83);
1963
1964 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1965
1966 memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1967
1968 // The next reloc should be a PLT32 reloc against __tls_get_addr.
1969 // We can skip it.
1970 this->skip_call_tls_get_addr_ = true;
1971 }
1972
1973 // Do a relocation in which we convert a TLS Initial-Exec to a
1974 // Local-Exec.
1975
1976 inline void
1977 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1978 size_t relnum,
1979 Output_segment* tls_segment,
1980 const elfcpp::Rel<32, false>& rel,
1981 unsigned int r_type,
1982 elfcpp::Elf_types<32>::Elf_Addr value,
1983 unsigned char* view,
1984 off_t view_size)
1985 {
1986 // We have to actually change the instructions, which means that we
1987 // need to examine the opcodes to figure out which instruction we
1988 // are looking at.
1989 if (r_type == elfcpp::R_386_TLS_IE)
1990 {
1991 // movl %gs:XX,%eax ==> movl $YY,%eax
1992 // movl %gs:XX,%reg ==> movl $YY,%reg
1993 // addl %gs:XX,%reg ==> addl $YY,%reg
1994 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
1995 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
1996
1997 unsigned char op1 = view[-1];
1998 if (op1 == 0xa1)
1999 {
2000 // movl XX,%eax ==> movl $YY,%eax
2001 view[-1] = 0xb8;
2002 }
2003 else
2004 {
2005 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
2006
2007 unsigned char op2 = view[-2];
2008 if (op2 == 0x8b)
2009 {
2010 // movl XX,%reg ==> movl $YY,%reg
2011 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2012 (op1 & 0xc7) == 0x05);
2013 view[-2] = 0xc7;
2014 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2015 }
2016 else if (op2 == 0x03)
2017 {
2018 // addl XX,%reg ==> addl $YY,%reg
2019 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2020 (op1 & 0xc7) == 0x05);
2021 view[-2] = 0x81;
2022 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2023 }
2024 else
2025 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
2026 }
2027 }
2028 else
2029 {
2030 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
2031 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
2032 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
2033 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
2034 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
2035
2036 unsigned char op1 = view[-1];
2037 unsigned char op2 = view[-2];
2038 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2039 (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
2040 if (op2 == 0x8b)
2041 {
2042 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
2043 view[-2] = 0xc7;
2044 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2045 }
2046 else if (op2 == 0x2b)
2047 {
2048 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
2049 view[-2] = 0x81;
2050 view[-1] = 0xe8 | ((op1 >> 3) & 7);
2051 }
2052 else if (op2 == 0x03)
2053 {
2054 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
2055 view[-2] = 0x81;
2056 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2057 }
2058 else
2059 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
2060 }
2061
2062 value = tls_segment->vaddr() + tls_segment->memsz() - value;
2063 if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
2064 value = - value;
2065
2066 Relocate_functions<32, false>::rel32(view, value);
2067 }
2068
2069 // Relocate section data.
2070
2071 void
2072 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
2073 unsigned int sh_type,
2074 const unsigned char* prelocs,
2075 size_t reloc_count,
2076 Output_section* output_section,
2077 bool needs_special_offset_handling,
2078 unsigned char* view,
2079 elfcpp::Elf_types<32>::Elf_Addr address,
2080 off_t view_size)
2081 {
2082 gold_assert(sh_type == elfcpp::SHT_REL);
2083
2084 gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
2085 Target_i386::Relocate>(
2086 relinfo,
2087 this,
2088 prelocs,
2089 reloc_count,
2090 output_section,
2091 needs_special_offset_handling,
2092 view,
2093 address,
2094 view_size);
2095 }
2096
2097 // Return the value to use for a dynamic which requires special
2098 // treatment. This is how we support equality comparisons of function
2099 // pointers across shared library boundaries, as described in the
2100 // processor specific ABI supplement.
2101
2102 uint64_t
2103 Target_i386::do_dynsym_value(const Symbol* gsym) const
2104 {
2105 gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
2106 return this->plt_section()->address() + gsym->plt_offset();
2107 }
2108
2109 // Return a string used to fill a code section with nops to take up
2110 // the specified length.
2111
2112 std::string
2113 Target_i386::do_code_fill(off_t length)
2114 {
2115 if (length >= 16)
2116 {
2117 // Build a jmp instruction to skip over the bytes.
2118 unsigned char jmp[5];
2119 jmp[0] = 0xe9;
2120 elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
2121 return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
2122 + std::string(length - 5, '\0'));
2123 }
2124
2125 // Nop sequences of various lengths.
2126 const char nop1[1] = { 0x90 }; // nop
2127 const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax
2128 const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi
2129 const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi
2130 const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop
2131 0x00 }; // leal 0(%esi,1),%esi
2132 const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
2133 0x00, 0x00 };
2134 const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
2135 0x00, 0x00, 0x00 };
2136 const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop
2137 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
2138 const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi
2139 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi
2140 0x00 };
2141 const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
2142 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
2143 0x00, 0x00 };
2144 const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
2145 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
2146 0x00, 0x00, 0x00 };
2147 const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
2148 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
2149 0x00, 0x00, 0x00, 0x00 };
2150 const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
2151 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
2152 0x27, 0x00, 0x00, 0x00,
2153 0x00 };
2154 const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
2155 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
2156 0xbc, 0x27, 0x00, 0x00,
2157 0x00, 0x00 };
2158 const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
2159 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
2160 0x90, 0x90, 0x90, 0x90,
2161 0x90, 0x90, 0x90 };
2162
2163 const char* nops[16] = {
2164 NULL,
2165 nop1, nop2, nop3, nop4, nop5, nop6, nop7,
2166 nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
2167 };
2168
2169 return std::string(nops[length], length);
2170 }
2171
2172 // The selector for i386 object files.
2173
2174 class Target_selector_i386 : public Target_selector
2175 {
2176 public:
2177 Target_selector_i386()
2178 : Target_selector(elfcpp::EM_386, 32, false)
2179 { }
2180
2181 Target*
2182 recognize(int machine, int osabi, int abiversion);
2183
2184 private:
2185 Target_i386* target_;
2186 };
2187
2188 // Recognize an i386 object file when we already know that the machine
2189 // number is EM_386.
2190
2191 Target*
2192 Target_selector_i386::recognize(int, int, int)
2193 {
2194 if (this->target_ == NULL)
2195 this->target_ = new Target_i386();
2196 return this->target_;
2197 }
2198
2199 Target_selector_i386 target_selector_i386;
2200
2201 } // End anonymous namespace.