From Craig Silverstein: Add support for --demangle.
[deliverable/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 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_space_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 do_set_address(uint64_t, off_t)
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_->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_space_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, Symbol* gsym,
656 const elfcpp::Rel<32, false>& rel)
657 {
658 Sized_symbol<32>* ssym;
659 ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym
660 SELECT_SIZE(32));
661
662 if (!Copy_relocs<32, false>::need_copy_reloc(options, object,
663 data_shndx, ssym))
664 {
665 // So far we do not need a COPY reloc. Save this relocation.
666 // If it turns out that we never need a COPY reloc for this
667 // symbol, then we will emit the relocation.
668 if (this->copy_relocs_ == NULL)
669 this->copy_relocs_ = new Copy_relocs<32, false>();
670 this->copy_relocs_->save(ssym, object, data_shndx, rel);
671 }
672 else
673 {
674 // Allocate space for this symbol in the .bss section.
675
676 elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize();
677
678 // There is no defined way to determine the required alignment
679 // of the symbol. We pick the alignment based on the size. We
680 // set an arbitrary maximum of 256.
681 unsigned int align;
682 for (align = 1; align < 512; align <<= 1)
683 if ((symsize & align) != 0)
684 break;
685
686 if (this->dynbss_ == NULL)
687 {
688 this->dynbss_ = new Output_data_space(align);
689 layout->add_output_section_data(".bss",
690 elfcpp::SHT_NOBITS,
691 (elfcpp::SHF_ALLOC
692 | elfcpp::SHF_WRITE),
693 this->dynbss_);
694 }
695
696 Output_data_space* dynbss = this->dynbss_;
697
698 if (align > dynbss->addralign())
699 dynbss->set_space_alignment(align);
700
701 off_t dynbss_size = dynbss->data_size();
702 dynbss_size = align_address(dynbss_size, align);
703 off_t offset = dynbss_size;
704 dynbss->set_space_size(dynbss_size + symsize);
705
706 symtab->define_with_copy_reloc(this, ssym, dynbss, offset);
707
708 // Add the COPY reloc.
709 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
710 rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset);
711 }
712 }
713
714 // Optimize the TLS relocation type based on what we know about the
715 // symbol. IS_FINAL is true if the final address of this symbol is
716 // known at link time.
717
718 tls::Tls_optimization
719 Target_i386::optimize_tls_reloc(bool is_final, int r_type)
720 {
721 // If we are generating a shared library, then we can't do anything
722 // in the linker.
723 if (parameters->output_is_shared())
724 return tls::TLSOPT_NONE;
725
726 switch (r_type)
727 {
728 case elfcpp::R_386_TLS_GD:
729 case elfcpp::R_386_TLS_GOTDESC:
730 case elfcpp::R_386_TLS_DESC_CALL:
731 // These are General-Dynamic which permits fully general TLS
732 // access. Since we know that we are generating an executable,
733 // we can convert this to Initial-Exec. If we also know that
734 // this is a local symbol, we can further switch to Local-Exec.
735 if (is_final)
736 return tls::TLSOPT_TO_LE;
737 return tls::TLSOPT_TO_IE;
738
739 case elfcpp::R_386_TLS_LDM:
740 // This is Local-Dynamic, which refers to a local symbol in the
741 // dynamic TLS block. Since we know that we generating an
742 // executable, we can switch to Local-Exec.
743 return tls::TLSOPT_TO_LE;
744
745 case elfcpp::R_386_TLS_LDO_32:
746 // Another type of Local-Dynamic relocation.
747 return tls::TLSOPT_TO_LE;
748
749 case elfcpp::R_386_TLS_IE:
750 case elfcpp::R_386_TLS_GOTIE:
751 case elfcpp::R_386_TLS_IE_32:
752 // These are Initial-Exec relocs which get the thread offset
753 // from the GOT. If we know that we are linking against the
754 // local symbol, we can switch to Local-Exec, which links the
755 // thread offset into the instruction.
756 if (is_final)
757 return tls::TLSOPT_TO_LE;
758 return tls::TLSOPT_NONE;
759
760 case elfcpp::R_386_TLS_LE:
761 case elfcpp::R_386_TLS_LE_32:
762 // When we already have Local-Exec, there is nothing further we
763 // can do.
764 return tls::TLSOPT_NONE;
765
766 default:
767 gold_unreachable();
768 }
769 }
770
771 // Report an unsupported relocation against a local symbol.
772
773 void
774 Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
775 unsigned int r_type)
776 {
777 gold_error(_("%s: unsupported reloc %u against local symbol"),
778 object->name().c_str(), r_type);
779 }
780
781 // Scan a relocation for a local symbol.
782
783 inline void
784 Target_i386::Scan::local(const General_options&,
785 Symbol_table* symtab,
786 Layout* layout,
787 Target_i386* target,
788 Sized_relobj<32, false>* object,
789 unsigned int data_shndx,
790 Output_section* output_section,
791 const elfcpp::Rel<32, false>& reloc,
792 unsigned int r_type,
793 const elfcpp::Sym<32, false>&)
794 {
795 switch (r_type)
796 {
797 case elfcpp::R_386_NONE:
798 case elfcpp::R_386_GNU_VTINHERIT:
799 case elfcpp::R_386_GNU_VTENTRY:
800 break;
801
802 case elfcpp::R_386_32:
803 // If building a shared library (or a position-independent
804 // executable), we need to create a dynamic relocation for
805 // this location. The relocation applied at link time will
806 // apply the link-time value, so we flag the location with
807 // an R_386_RELATIVE relocation so the dynamic loader can
808 // relocate it easily.
809 if (parameters->output_is_position_independent())
810 {
811 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
812 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx,
813 reloc.get_r_offset());
814 if (!output_section->is_section_flag_set(elfcpp::SHF_WRITE))
815 layout->set_have_textrel();
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, data_shndx,
831 reloc.get_r_offset());
832 if (!output_section->is_section_flag_set(elfcpp::SHF_WRITE))
833 layout->set_have_textrel();
834 }
835 break;
836
837 case elfcpp::R_386_PC32:
838 case elfcpp::R_386_PC16:
839 case elfcpp::R_386_PC8:
840 break;
841
842 case elfcpp::R_386_PLT32:
843 // Since we know this is a local symbol, we can handle this as a
844 // PC32 reloc.
845 break;
846
847 case elfcpp::R_386_GOTOFF:
848 case elfcpp::R_386_GOTPC:
849 // We need a GOT section.
850 target->got_section(symtab, layout);
851 break;
852
853 case elfcpp::R_386_GOT32:
854 {
855 // The symbol requires a GOT entry.
856 Output_data_got<32, false>* got = target->got_section(symtab, layout);
857 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
858 if (got->add_local(object, r_sym))
859 {
860 // If we are generating a shared object, we need to add a
861 // dynamic RELATIVE relocation for this symbol.
862 if (parameters->output_is_position_independent())
863 {
864 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
865 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
866 data_shndx, reloc.get_r_offset());
867 if (!output_section->is_section_flag_set(elfcpp::SHF_WRITE))
868 layout->set_have_textrel();
869 }
870 }
871 }
872 break;
873
874 // These are relocations which should only be seen by the
875 // dynamic linker, and should never be seen here.
876 case elfcpp::R_386_COPY:
877 case elfcpp::R_386_GLOB_DAT:
878 case elfcpp::R_386_JUMP_SLOT:
879 case elfcpp::R_386_RELATIVE:
880 case elfcpp::R_386_TLS_TPOFF:
881 case elfcpp::R_386_TLS_DTPMOD32:
882 case elfcpp::R_386_TLS_DTPOFF32:
883 case elfcpp::R_386_TLS_TPOFF32:
884 case elfcpp::R_386_TLS_DESC:
885 gold_error(_("%s: unexpected reloc %u in object file"),
886 object->name().c_str(), r_type);
887 break;
888
889 // These are initial TLS relocs, which are expected when
890 // linking.
891 case elfcpp::R_386_TLS_GD: // Global-dynamic
892 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
893 case elfcpp::R_386_TLS_DESC_CALL:
894 case elfcpp::R_386_TLS_LDM: // Local-dynamic
895 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
896 case elfcpp::R_386_TLS_IE: // Initial-exec
897 case elfcpp::R_386_TLS_IE_32:
898 case elfcpp::R_386_TLS_GOTIE:
899 case elfcpp::R_386_TLS_LE: // Local-exec
900 case elfcpp::R_386_TLS_LE_32:
901 {
902 bool output_is_shared = parameters->output_is_shared();
903 const tls::Tls_optimization optimized_type
904 = Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
905 switch (r_type)
906 {
907 case elfcpp::R_386_TLS_GD: // Global-dynamic
908 if (optimized_type == tls::TLSOPT_NONE)
909 {
910 // Create a pair of GOT entries for the module index and
911 // dtv-relative offset.
912 Output_data_got<32, false>* got
913 = target->got_section(symtab, layout);
914 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
915 if (got->add_local_tls(object, r_sym, true))
916 {
917 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
918 unsigned int got_off
919 = object->local_tls_got_offset(r_sym, true);
920 rel_dyn->add_local(object, r_sym,
921 elfcpp::R_386_TLS_DTPMOD32,
922 got, got_off);
923 rel_dyn->add_local(object, r_sym,
924 elfcpp::R_386_TLS_DTPOFF32,
925 got, got_off + 4);
926 }
927 }
928 else if (optimized_type != tls::TLSOPT_TO_LE)
929 unsupported_reloc_local(object, r_type);
930 break;
931
932 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva)
933 case elfcpp::R_386_TLS_DESC_CALL:
934 unsupported_reloc_local(object, r_type);
935 break;
936
937 case elfcpp::R_386_TLS_LDM: // Local-dynamic
938 if (optimized_type == tls::TLSOPT_NONE)
939 {
940 // Create a GOT entry for the module index.
941 Output_data_got<32, false>* got
942 = target->got_section(symtab, layout);
943 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
944 if (got->add_local_tls(object, r_sym, false))
945 {
946 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
947 unsigned int got_off
948 = object->local_tls_got_offset(r_sym, false);
949 rel_dyn->add_local(object, r_sym,
950 elfcpp::R_386_TLS_DTPMOD32, got,
951 got_off);
952 }
953 }
954 else if (optimized_type != tls::TLSOPT_TO_LE)
955 unsupported_reloc_local(object, r_type);
956 break;
957
958 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
959 break;
960
961 case elfcpp::R_386_TLS_IE: // Initial-exec
962 case elfcpp::R_386_TLS_IE_32:
963 case elfcpp::R_386_TLS_GOTIE:
964 if (optimized_type == tls::TLSOPT_NONE)
965 {
966 // Create a GOT entry for the tp-relative offset.
967 Output_data_got<32, false>* got
968 = target->got_section(symtab, layout);
969 unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
970 if (got->add_local(object, r_sym))
971 {
972 unsigned int dyn_r_type
973 = (r_type == elfcpp::R_386_TLS_IE_32
974 ? elfcpp::R_386_TLS_TPOFF32
975 : elfcpp::R_386_TLS_TPOFF);
976 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
977 unsigned int got_off = object->local_got_offset(r_sym);
978 rel_dyn->add_local(object, r_sym, dyn_r_type, got,
979 got_off);
980 }
981 }
982 else if (optimized_type != tls::TLSOPT_TO_LE)
983 unsupported_reloc_local(object, r_type);
984 break;
985
986 case elfcpp::R_386_TLS_LE: // Local-exec
987 case elfcpp::R_386_TLS_LE_32:
988 if (output_is_shared)
989 unsupported_reloc_local(object, r_type);
990 break;
991
992 default:
993 gold_unreachable();
994 }
995 }
996 break;
997
998 case elfcpp::R_386_32PLT:
999 case elfcpp::R_386_TLS_GD_32:
1000 case elfcpp::R_386_TLS_GD_PUSH:
1001 case elfcpp::R_386_TLS_GD_CALL:
1002 case elfcpp::R_386_TLS_GD_POP:
1003 case elfcpp::R_386_TLS_LDM_32:
1004 case elfcpp::R_386_TLS_LDM_PUSH:
1005 case elfcpp::R_386_TLS_LDM_CALL:
1006 case elfcpp::R_386_TLS_LDM_POP:
1007 case elfcpp::R_386_USED_BY_INTEL_200:
1008 default:
1009 unsupported_reloc_local(object, r_type);
1010 break;
1011 }
1012 }
1013
1014 // Report an unsupported relocation against a global symbol.
1015
1016 void
1017 Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object,
1018 unsigned int r_type,
1019 Symbol* gsym)
1020 {
1021 gold_error(_("%s: unsupported reloc %u against global symbol %s"),
1022 object->name().c_str(), r_type, gsym->demangled_name().c_str());
1023 }
1024
1025 // Scan a relocation for a global symbol.
1026
1027 inline void
1028 Target_i386::Scan::global(const General_options& options,
1029 Symbol_table* symtab,
1030 Layout* layout,
1031 Target_i386* target,
1032 Sized_relobj<32, false>* object,
1033 unsigned int data_shndx,
1034 Output_section* output_section,
1035 const elfcpp::Rel<32, false>& reloc,
1036 unsigned int r_type,
1037 Symbol* gsym)
1038 {
1039 switch (r_type)
1040 {
1041 case elfcpp::R_386_NONE:
1042 case elfcpp::R_386_GNU_VTINHERIT:
1043 case elfcpp::R_386_GNU_VTENTRY:
1044 break;
1045
1046 case elfcpp::R_386_32:
1047 case elfcpp::R_386_16:
1048 case elfcpp::R_386_8:
1049 {
1050 // Make a PLT entry if necessary.
1051 if (gsym->needs_plt_entry())
1052 {
1053 target->make_plt_entry(symtab, layout, gsym);
1054 // Since this is not a PC-relative relocation, we may be
1055 // taking the address of a function. In that case we need to
1056 // set the entry in the dynamic symbol table to the address of
1057 // the PLT entry.
1058 if (gsym->is_from_dynobj())
1059 gsym->set_needs_dynsym_value();
1060 }
1061 // Make a dynamic relocation if necessary.
1062 if (gsym->needs_dynamic_reloc(true, false))
1063 {
1064 if (target->may_need_copy_reloc(gsym))
1065 {
1066 target->copy_reloc(&options, symtab, layout, object,
1067 data_shndx, gsym, reloc);
1068 }
1069 else if (r_type == elfcpp::R_386_32
1070 && gsym->can_use_relative_reloc(false))
1071 {
1072 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1073 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
1074 data_shndx, reloc.get_r_offset());
1075 if (!output_section->is_section_flag_set(elfcpp::SHF_WRITE))
1076 layout->set_have_textrel();
1077 }
1078 else
1079 {
1080 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1081 rel_dyn->add_global(gsym, r_type, object, data_shndx,
1082 reloc.get_r_offset());
1083 if (!output_section->is_section_flag_set(elfcpp::SHF_WRITE))
1084 layout->set_have_textrel();
1085 }
1086 }
1087 }
1088 break;
1089
1090 case elfcpp::R_386_PC32:
1091 case elfcpp::R_386_PC16:
1092 case elfcpp::R_386_PC8:
1093 {
1094 // Make a PLT entry if necessary.
1095 if (gsym->needs_plt_entry())
1096 target->make_plt_entry(symtab, layout, gsym);
1097 // Make a dynamic relocation if necessary.
1098 bool is_function_call = (gsym->type() == elfcpp::STT_FUNC);
1099 if (gsym->needs_dynamic_reloc(false, is_function_call))
1100 {
1101 if (target->may_need_copy_reloc(gsym))
1102 {
1103 target->copy_reloc(&options, symtab, layout, object,
1104 data_shndx, gsym, reloc);
1105 }
1106 else
1107 {
1108 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1109 rel_dyn->add_global(gsym, r_type, object, data_shndx,
1110 reloc.get_r_offset());
1111 if (!output_section->is_section_flag_set(elfcpp::SHF_WRITE))
1112 layout->set_have_textrel();
1113 }
1114 }
1115 }
1116 break;
1117
1118 case elfcpp::R_386_GOT32:
1119 {
1120 // The symbol requires a GOT entry.
1121 Output_data_got<32, false>* got = target->got_section(symtab, layout);
1122 if (got->add_global(gsym))
1123 {
1124 // If this symbol is not fully resolved, we need to add a
1125 // dynamic relocation for it.
1126 if (!gsym->final_value_is_known())
1127 {
1128 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1129 if (gsym->is_from_dynobj()
1130 || gsym->is_preemptible())
1131 rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got,
1132 gsym->got_offset());
1133 else
1134 {
1135 rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE,
1136 got, gsym->got_offset());
1137 // Make sure we write the link-time value to the GOT.
1138 gsym->set_needs_value_in_got();
1139 }
1140 }
1141 }
1142 }
1143 break;
1144
1145 case elfcpp::R_386_PLT32:
1146 // If the symbol is fully resolved, this is just a PC32 reloc.
1147 // Otherwise we need a PLT entry.
1148 if (gsym->final_value_is_known())
1149 break;
1150 // If building a shared library, we can also skip the PLT entry
1151 // if the symbol is defined in the output file and is protected
1152 // or hidden.
1153 if (gsym->is_defined()
1154 && !gsym->is_from_dynobj()
1155 && !gsym->is_preemptible())
1156 break;
1157 target->make_plt_entry(symtab, layout, gsym);
1158 break;
1159
1160 case elfcpp::R_386_GOTOFF:
1161 case elfcpp::R_386_GOTPC:
1162 // We need a GOT section.
1163 target->got_section(symtab, layout);
1164 break;
1165
1166 // These are relocations which should only be seen by the
1167 // dynamic linker, and should never be seen here.
1168 case elfcpp::R_386_COPY:
1169 case elfcpp::R_386_GLOB_DAT:
1170 case elfcpp::R_386_JUMP_SLOT:
1171 case elfcpp::R_386_RELATIVE:
1172 case elfcpp::R_386_TLS_TPOFF:
1173 case elfcpp::R_386_TLS_DTPMOD32:
1174 case elfcpp::R_386_TLS_DTPOFF32:
1175 case elfcpp::R_386_TLS_TPOFF32:
1176 case elfcpp::R_386_TLS_DESC:
1177 gold_error(_("%s: unexpected reloc %u in object file"),
1178 object->name().c_str(), r_type);
1179 break;
1180
1181 // These are initial tls relocs, which are expected when
1182 // linking.
1183 case elfcpp::R_386_TLS_GD: // Global-dynamic
1184 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1185 case elfcpp::R_386_TLS_DESC_CALL:
1186 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1187 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1188 case elfcpp::R_386_TLS_IE: // Initial-exec
1189 case elfcpp::R_386_TLS_IE_32:
1190 case elfcpp::R_386_TLS_GOTIE:
1191 case elfcpp::R_386_TLS_LE: // Local-exec
1192 case elfcpp::R_386_TLS_LE_32:
1193 {
1194 const bool is_final = gsym->final_value_is_known();
1195 const tls::Tls_optimization optimized_type
1196 = Target_i386::optimize_tls_reloc(is_final, r_type);
1197 switch (r_type)
1198 {
1199 case elfcpp::R_386_TLS_GD: // Global-dynamic
1200 if (optimized_type == tls::TLSOPT_NONE)
1201 {
1202 // Create a pair of GOT entries for the module index and
1203 // dtv-relative offset.
1204 Output_data_got<32, false>* got
1205 = target->got_section(symtab, layout);
1206 if (got->add_global_tls(gsym, true))
1207 {
1208 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1209 unsigned int got_off = gsym->tls_got_offset(true);
1210 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_DTPMOD32,
1211 got, got_off);
1212 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_DTPOFF32,
1213 got, got_off + 4);
1214 }
1215 }
1216 else if (optimized_type == tls::TLSOPT_TO_IE)
1217 {
1218 // Create a GOT entry for the tp-relative offset.
1219 Output_data_got<32, false>* got
1220 = target->got_section(symtab, layout);
1221 if (got->add_global(gsym))
1222 {
1223 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1224 unsigned int got_off = gsym->got_offset();
1225 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_TPOFF32,
1226 got, got_off);
1227 }
1228 }
1229 else if (optimized_type != tls::TLSOPT_TO_LE)
1230 unsupported_reloc_global(object, r_type, gsym);
1231 break;
1232
1233 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url)
1234 case elfcpp::R_386_TLS_DESC_CALL:
1235 unsupported_reloc_global(object, r_type, gsym);
1236 break;
1237
1238 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1239 // FIXME: If not relaxing to LE, we need to generate a
1240 // DTPMOD32 reloc.
1241 if (optimized_type == tls::TLSOPT_NONE)
1242 {
1243 // Create a GOT entry for the module index.
1244 Output_data_got<32, false>* got
1245 = target->got_section(symtab, layout);
1246 if (got->add_global_tls(gsym, false))
1247 {
1248 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1249 unsigned int got_off = gsym->tls_got_offset(false);
1250 rel_dyn->add_global(gsym, elfcpp::R_386_TLS_DTPMOD32,
1251 got, got_off);
1252 }
1253 }
1254 else if (optimized_type != tls::TLSOPT_TO_LE)
1255 unsupported_reloc_global(object, r_type, gsym);
1256 break;
1257
1258 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1259 break;
1260
1261 case elfcpp::R_386_TLS_IE: // Initial-exec
1262 case elfcpp::R_386_TLS_IE_32:
1263 case elfcpp::R_386_TLS_GOTIE:
1264 if (optimized_type == tls::TLSOPT_NONE)
1265 {
1266 // Create a GOT entry for the tp-relative offset.
1267 Output_data_got<32, false>* got
1268 = target->got_section(symtab, layout);
1269 if (got->add_global(gsym))
1270 {
1271 unsigned int dyn_r_type
1272 = (r_type == elfcpp::R_386_TLS_IE_32
1273 ? elfcpp::R_386_TLS_TPOFF32
1274 : elfcpp::R_386_TLS_TPOFF);
1275 Reloc_section* rel_dyn = target->rel_dyn_section(layout);
1276 unsigned int got_off = gsym->got_offset();
1277 rel_dyn->add_global(gsym, dyn_r_type, got, got_off);
1278 }
1279 }
1280 else if (optimized_type != tls::TLSOPT_TO_LE)
1281 unsupported_reloc_global(object, r_type, gsym);
1282 break;
1283
1284 case elfcpp::R_386_TLS_LE: // Local-exec
1285 case elfcpp::R_386_TLS_LE_32:
1286 if (parameters->output_is_shared())
1287 unsupported_reloc_global(object, r_type, gsym);
1288 break;
1289
1290 default:
1291 gold_unreachable();
1292 }
1293 }
1294 break;
1295
1296 case elfcpp::R_386_32PLT:
1297 case elfcpp::R_386_TLS_GD_32:
1298 case elfcpp::R_386_TLS_GD_PUSH:
1299 case elfcpp::R_386_TLS_GD_CALL:
1300 case elfcpp::R_386_TLS_GD_POP:
1301 case elfcpp::R_386_TLS_LDM_32:
1302 case elfcpp::R_386_TLS_LDM_PUSH:
1303 case elfcpp::R_386_TLS_LDM_CALL:
1304 case elfcpp::R_386_TLS_LDM_POP:
1305 case elfcpp::R_386_USED_BY_INTEL_200:
1306 default:
1307 unsupported_reloc_global(object, r_type, gsym);
1308 break;
1309 }
1310 }
1311
1312 // Scan relocations for a section.
1313
1314 void
1315 Target_i386::scan_relocs(const General_options& options,
1316 Symbol_table* symtab,
1317 Layout* layout,
1318 Sized_relobj<32, false>* object,
1319 unsigned int data_shndx,
1320 unsigned int sh_type,
1321 const unsigned char* prelocs,
1322 size_t reloc_count,
1323 Output_section* output_section,
1324 bool needs_special_offset_handling,
1325 size_t local_symbol_count,
1326 const unsigned char* plocal_symbols)
1327 {
1328 if (sh_type == elfcpp::SHT_RELA)
1329 {
1330 gold_error(_("%s: unsupported RELA reloc section"),
1331 object->name().c_str());
1332 return;
1333 }
1334
1335 gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
1336 Target_i386::Scan>(
1337 options,
1338 symtab,
1339 layout,
1340 this,
1341 object,
1342 data_shndx,
1343 prelocs,
1344 reloc_count,
1345 output_section,
1346 needs_special_offset_handling,
1347 local_symbol_count,
1348 plocal_symbols);
1349 }
1350
1351 // Finalize the sections.
1352
1353 void
1354 Target_i386::do_finalize_sections(Layout* layout)
1355 {
1356 // Fill in some more dynamic tags.
1357 Output_data_dynamic* const odyn = layout->dynamic_data();
1358 if (odyn != NULL)
1359 {
1360 if (this->got_plt_ != NULL)
1361 odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
1362
1363 if (this->plt_ != NULL)
1364 {
1365 const Output_data* od = this->plt_->rel_plt();
1366 odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
1367 odyn->add_section_address(elfcpp::DT_JMPREL, od);
1368 odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
1369 }
1370
1371 if (this->rel_dyn_ != NULL)
1372 {
1373 const Output_data* od = this->rel_dyn_;
1374 odyn->add_section_address(elfcpp::DT_REL, od);
1375 odyn->add_section_size(elfcpp::DT_RELSZ, od);
1376 odyn->add_constant(elfcpp::DT_RELENT,
1377 elfcpp::Elf_sizes<32>::rel_size);
1378 }
1379
1380 if (!parameters->output_is_shared())
1381 {
1382 // The value of the DT_DEBUG tag is filled in by the dynamic
1383 // linker at run time, and used by the debugger.
1384 odyn->add_constant(elfcpp::DT_DEBUG, 0);
1385 }
1386 }
1387
1388 // Emit any relocs we saved in an attempt to avoid generating COPY
1389 // relocs.
1390 if (this->copy_relocs_ == NULL)
1391 return;
1392 if (this->copy_relocs_->any_to_emit())
1393 {
1394 Reloc_section* rel_dyn = this->rel_dyn_section(layout);
1395 this->copy_relocs_->emit(rel_dyn);
1396 }
1397 delete this->copy_relocs_;
1398 this->copy_relocs_ = NULL;
1399 }
1400
1401 // Return whether a direct absolute static relocation needs to be applied.
1402 // In cases where Scan::local() or Scan::global() has created
1403 // a dynamic relocation other than R_386_RELATIVE, the addend
1404 // of the relocation is carried in the data, and we must not
1405 // apply the static relocation.
1406
1407 inline bool
1408 Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
1409 bool is_absolute_ref,
1410 bool is_function_call,
1411 bool is_32bit)
1412 {
1413 // For local symbols, we will have created a non-RELATIVE dynamic
1414 // relocation only if (a) the output is position independent,
1415 // (b) the relocation is absolute (not pc- or segment-relative), and
1416 // (c) the relocation is not 32 bits wide.
1417 if (gsym == NULL)
1418 return !(parameters->output_is_position_independent()
1419 && is_absolute_ref
1420 && !is_32bit);
1421
1422 // For global symbols, we use the same helper routines used in the scan pass.
1423 return !(gsym->needs_dynamic_reloc(is_absolute_ref, is_function_call)
1424 && !gsym->can_use_relative_reloc(is_function_call));
1425 }
1426
1427 // Perform a relocation.
1428
1429 inline bool
1430 Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
1431 Target_i386* target,
1432 size_t relnum,
1433 const elfcpp::Rel<32, false>& rel,
1434 unsigned int r_type,
1435 const Sized_symbol<32>* gsym,
1436 const Symbol_value<32>* psymval,
1437 unsigned char* view,
1438 elfcpp::Elf_types<32>::Elf_Addr address,
1439 off_t view_size)
1440 {
1441 if (this->skip_call_tls_get_addr_)
1442 {
1443 if (r_type != elfcpp::R_386_PLT32
1444 || gsym == NULL
1445 || strcmp(gsym->name(), "___tls_get_addr") != 0)
1446 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1447 _("missing expected TLS relocation"));
1448 else
1449 {
1450 this->skip_call_tls_get_addr_ = false;
1451 return false;
1452 }
1453 }
1454
1455 // Pick the value to use for symbols defined in shared objects.
1456 Symbol_value<32> symval;
1457 if (gsym != NULL
1458 && (gsym->is_from_dynobj()
1459 || (parameters->output_is_shared()
1460 && gsym->is_preemptible()))
1461 && gsym->has_plt_offset())
1462 {
1463 symval.set_output_value(target->plt_section()->address()
1464 + gsym->plt_offset());
1465 psymval = &symval;
1466 }
1467
1468 const Sized_relobj<32, false>* object = relinfo->object;
1469
1470 // Get the GOT offset if needed.
1471 // The GOT pointer points to the end of the GOT section.
1472 // We need to subtract the size of the GOT section to get
1473 // the actual offset to use in the relocation.
1474 bool have_got_offset = false;
1475 unsigned int got_offset = 0;
1476 switch (r_type)
1477 {
1478 case elfcpp::R_386_GOT32:
1479 if (gsym != NULL)
1480 {
1481 gold_assert(gsym->has_got_offset());
1482 got_offset = gsym->got_offset() - target->got_size();
1483 }
1484 else
1485 {
1486 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1487 gold_assert(object->local_has_got_offset(r_sym));
1488 got_offset = object->local_got_offset(r_sym) - target->got_size();
1489 }
1490 have_got_offset = true;
1491 break;
1492
1493 default:
1494 break;
1495 }
1496
1497 switch (r_type)
1498 {
1499 case elfcpp::R_386_NONE:
1500 case elfcpp::R_386_GNU_VTINHERIT:
1501 case elfcpp::R_386_GNU_VTENTRY:
1502 break;
1503
1504 case elfcpp::R_386_32:
1505 if (should_apply_static_reloc(gsym, true, false, true))
1506 Relocate_functions<32, false>::rel32(view, object, psymval);
1507 break;
1508
1509 case elfcpp::R_386_PC32:
1510 {
1511 bool is_function_call = (gsym != NULL
1512 && gsym->type() == elfcpp::STT_FUNC);
1513 if (should_apply_static_reloc(gsym, false, is_function_call, true))
1514 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1515 }
1516 break;
1517
1518 case elfcpp::R_386_16:
1519 if (should_apply_static_reloc(gsym, true, false, false))
1520 Relocate_functions<32, false>::rel16(view, object, psymval);
1521 break;
1522
1523 case elfcpp::R_386_PC16:
1524 {
1525 bool is_function_call = (gsym != NULL
1526 && gsym->type() == elfcpp::STT_FUNC);
1527 if (should_apply_static_reloc(gsym, false, is_function_call, false))
1528 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1529 }
1530 break;
1531
1532 case elfcpp::R_386_8:
1533 if (should_apply_static_reloc(gsym, true, false, false))
1534 Relocate_functions<32, false>::rel8(view, object, psymval);
1535 break;
1536
1537 case elfcpp::R_386_PC8:
1538 {
1539 bool is_function_call = (gsym != NULL
1540 && gsym->type() == elfcpp::STT_FUNC);
1541 if (should_apply_static_reloc(gsym, false, is_function_call, false))
1542 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1543 }
1544 break;
1545
1546 case elfcpp::R_386_PLT32:
1547 gold_assert(gsym == NULL
1548 || gsym->has_plt_offset()
1549 || gsym->final_value_is_known());
1550 Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
1551 break;
1552
1553 case elfcpp::R_386_GOT32:
1554 gold_assert(have_got_offset);
1555 Relocate_functions<32, false>::rel32(view, got_offset);
1556 break;
1557
1558 case elfcpp::R_386_GOTOFF:
1559 {
1560 elfcpp::Elf_types<32>::Elf_Addr value;
1561 value = (psymval->value(object, 0)
1562 - target->got_plt_section()->address());
1563 Relocate_functions<32, false>::rel32(view, value);
1564 }
1565 break;
1566
1567 case elfcpp::R_386_GOTPC:
1568 {
1569 elfcpp::Elf_types<32>::Elf_Addr value;
1570 value = target->got_plt_section()->address();
1571 Relocate_functions<32, false>::pcrel32(view, value, address);
1572 }
1573 break;
1574
1575 case elfcpp::R_386_COPY:
1576 case elfcpp::R_386_GLOB_DAT:
1577 case elfcpp::R_386_JUMP_SLOT:
1578 case elfcpp::R_386_RELATIVE:
1579 // These are outstanding tls relocs, which are unexpected when
1580 // linking.
1581 case elfcpp::R_386_TLS_TPOFF:
1582 case elfcpp::R_386_TLS_DTPMOD32:
1583 case elfcpp::R_386_TLS_DTPOFF32:
1584 case elfcpp::R_386_TLS_TPOFF32:
1585 case elfcpp::R_386_TLS_DESC:
1586 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1587 _("unexpected reloc %u in object file"),
1588 r_type);
1589 break;
1590
1591 // These are initial tls relocs, which are expected when
1592 // linking.
1593 case elfcpp::R_386_TLS_GD: // Global-dynamic
1594 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1595 case elfcpp::R_386_TLS_DESC_CALL:
1596 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1597 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1598 case elfcpp::R_386_TLS_IE: // Initial-exec
1599 case elfcpp::R_386_TLS_IE_32:
1600 case elfcpp::R_386_TLS_GOTIE:
1601 case elfcpp::R_386_TLS_LE: // Local-exec
1602 case elfcpp::R_386_TLS_LE_32:
1603 this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval,
1604 view, address, view_size);
1605 break;
1606
1607 case elfcpp::R_386_32PLT:
1608 case elfcpp::R_386_TLS_GD_32:
1609 case elfcpp::R_386_TLS_GD_PUSH:
1610 case elfcpp::R_386_TLS_GD_CALL:
1611 case elfcpp::R_386_TLS_GD_POP:
1612 case elfcpp::R_386_TLS_LDM_32:
1613 case elfcpp::R_386_TLS_LDM_PUSH:
1614 case elfcpp::R_386_TLS_LDM_CALL:
1615 case elfcpp::R_386_TLS_LDM_POP:
1616 case elfcpp::R_386_USED_BY_INTEL_200:
1617 default:
1618 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1619 _("unsupported reloc %u"),
1620 r_type);
1621 break;
1622 }
1623
1624 return true;
1625 }
1626
1627 // Perform a TLS relocation.
1628
1629 inline void
1630 Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
1631 Target_i386* target,
1632 size_t relnum,
1633 const elfcpp::Rel<32, false>& rel,
1634 unsigned int r_type,
1635 const Sized_symbol<32>* gsym,
1636 const Symbol_value<32>* psymval,
1637 unsigned char* view,
1638 elfcpp::Elf_types<32>::Elf_Addr,
1639 off_t view_size)
1640 {
1641 Output_segment* tls_segment = relinfo->layout->tls_segment();
1642
1643 const Sized_relobj<32, false>* object = relinfo->object;
1644
1645 elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0);
1646
1647 const bool is_final = (gsym == NULL
1648 ? !parameters->output_is_position_independent()
1649 : gsym->final_value_is_known());
1650 const tls::Tls_optimization optimized_type
1651 = Target_i386::optimize_tls_reloc(is_final, r_type);
1652 switch (r_type)
1653 {
1654 case elfcpp::R_386_TLS_GD: // Global-dynamic
1655 if (optimized_type == tls::TLSOPT_TO_LE)
1656 {
1657 gold_assert(tls_segment != NULL);
1658 this->tls_gd_to_le(relinfo, relnum, tls_segment,
1659 rel, r_type, value, view,
1660 view_size);
1661 break;
1662 }
1663 else
1664 {
1665 unsigned int got_offset;
1666 if (gsym != NULL)
1667 {
1668 gold_assert(gsym->has_tls_got_offset(true));
1669 got_offset = gsym->tls_got_offset(true) - target->got_size();
1670 }
1671 else
1672 {
1673 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1674 gold_assert(object->local_has_tls_got_offset(r_sym, true));
1675 got_offset = (object->local_tls_got_offset(r_sym, true)
1676 - target->got_size());
1677 }
1678 if (optimized_type == tls::TLSOPT_TO_IE)
1679 {
1680 gold_assert(tls_segment != NULL);
1681 this->tls_gd_to_ie(relinfo, relnum, tls_segment,
1682 rel, r_type, got_offset, view,
1683 view_size);
1684 break;
1685 }
1686 else if (optimized_type == tls::TLSOPT_NONE)
1687 {
1688 // Relocate the field with the offset of the pair of GOT
1689 // entries.
1690 Relocate_functions<32, false>::rel32(view, got_offset);
1691 break;
1692 }
1693 }
1694 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1695 _("unsupported reloc %u"),
1696 r_type);
1697 break;
1698
1699 case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
1700 case elfcpp::R_386_TLS_DESC_CALL:
1701 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1702 _("unsupported reloc %u"),
1703 r_type);
1704 break;
1705
1706 case elfcpp::R_386_TLS_LDM: // Local-dynamic
1707 if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
1708 {
1709 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1710 _("both SUN and GNU model "
1711 "TLS relocations"));
1712 break;
1713 }
1714 this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
1715 if (optimized_type == tls::TLSOPT_TO_LE)
1716 {
1717 gold_assert(tls_segment != NULL);
1718 this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type,
1719 value, view, view_size);
1720 break;
1721 }
1722 else if (optimized_type == tls::TLSOPT_NONE)
1723 {
1724 // Relocate the field with the offset of the GOT entry for
1725 // the module index.
1726 unsigned int got_offset;
1727 if (gsym != NULL)
1728 {
1729 gold_assert(gsym->has_tls_got_offset(false));
1730 got_offset = gsym->tls_got_offset(false) - target->got_size();
1731 }
1732 else
1733 {
1734 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1735 gold_assert(object->local_has_tls_got_offset(r_sym, false));
1736 got_offset = (object->local_tls_got_offset(r_sym, false)
1737 - target->got_size());
1738 }
1739 Relocate_functions<32, false>::rel32(view, got_offset);
1740 break;
1741 }
1742 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1743 _("unsupported reloc %u"),
1744 r_type);
1745 break;
1746
1747 case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
1748 // This reloc can appear in debugging sections, in which case we
1749 // won't see the TLS_LDM reloc. The local_dynamic_type field
1750 // tells us this.
1751 gold_assert(tls_segment != NULL);
1752 if (optimized_type != tls::TLSOPT_TO_LE
1753 || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE)
1754 value = value - tls_segment->vaddr();
1755 else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU)
1756 value = value - (tls_segment->vaddr() + tls_segment->memsz());
1757 else
1758 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1759 Relocate_functions<32, false>::rel32(view, value);
1760 break;
1761
1762 case elfcpp::R_386_TLS_IE: // Initial-exec
1763 case elfcpp::R_386_TLS_GOTIE:
1764 case elfcpp::R_386_TLS_IE_32:
1765 if (optimized_type == tls::TLSOPT_TO_LE)
1766 {
1767 gold_assert(tls_segment != NULL);
1768 Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
1769 rel, r_type, value, view,
1770 view_size);
1771 break;
1772 }
1773 else if (optimized_type == tls::TLSOPT_NONE)
1774 {
1775 // Relocate the field with the offset of the GOT entry for
1776 // the tp-relative offset of the symbol.
1777 unsigned int got_offset;
1778 if (gsym != NULL)
1779 {
1780 gold_assert(gsym->has_got_offset());
1781 got_offset = gsym->got_offset();
1782 }
1783 else
1784 {
1785 unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
1786 gold_assert(object->local_has_got_offset(r_sym));
1787 got_offset = object->local_got_offset(r_sym);
1788 }
1789 // For the R_386_TLS_IE relocation, we need to apply the
1790 // absolute address of the GOT entry.
1791 if (r_type == elfcpp::R_386_TLS_IE)
1792 got_offset += target->got_plt_section()->address();
1793 // All GOT offsets are relative to the end of the GOT.
1794 got_offset -= target->got_size();
1795 Relocate_functions<32, false>::rel32(view, got_offset);
1796 break;
1797 }
1798 gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
1799 _("unsupported reloc %u"),
1800 r_type);
1801 break;
1802
1803 case elfcpp::R_386_TLS_LE: // Local-exec
1804 gold_assert(tls_segment != NULL);
1805 value = value - (tls_segment->vaddr() + tls_segment->memsz());
1806 Relocate_functions<32, false>::rel32(view, value);
1807 break;
1808
1809 case elfcpp::R_386_TLS_LE_32:
1810 gold_assert(tls_segment != NULL);
1811 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1812 Relocate_functions<32, false>::rel32(view, value);
1813 break;
1814 }
1815 }
1816
1817 // Do a relocation in which we convert a TLS General-Dynamic to a
1818 // Local-Exec.
1819
1820 inline void
1821 Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
1822 size_t relnum,
1823 Output_segment* tls_segment,
1824 const elfcpp::Rel<32, false>& rel,
1825 unsigned int,
1826 elfcpp::Elf_types<32>::Elf_Addr value,
1827 unsigned char* view,
1828 off_t view_size)
1829 {
1830 // leal foo(,%reg,1),%eax; call ___tls_get_addr
1831 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1832 // leal foo(%reg),%eax; call ___tls_get_addr
1833 // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
1834
1835 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1836 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1837
1838 unsigned char op1 = view[-1];
1839 unsigned char op2 = view[-2];
1840
1841 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1842 op2 == 0x8d || op2 == 0x04);
1843 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1844
1845 int roff = 5;
1846
1847 if (op2 == 0x04)
1848 {
1849 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1850 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1851 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1852 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1853 memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1854 }
1855 else
1856 {
1857 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1858 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1859 if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1860 && view[9] == 0x90)
1861 {
1862 // There is a trailing nop. Use the size byte subl.
1863 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1864 roff = 6;
1865 }
1866 else
1867 {
1868 // Use the five byte subl.
1869 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1870 }
1871 }
1872
1873 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1874 Relocate_functions<32, false>::rel32(view + roff, value);
1875
1876 // The next reloc should be a PLT32 reloc against __tls_get_addr.
1877 // We can skip it.
1878 this->skip_call_tls_get_addr_ = true;
1879 }
1880
1881 // Do a relocation in which we convert a TLS General-Dynamic to a
1882 // Initial-Exec.
1883
1884 inline void
1885 Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
1886 size_t relnum,
1887 Output_segment* tls_segment,
1888 const elfcpp::Rel<32, false>& rel,
1889 unsigned int,
1890 elfcpp::Elf_types<32>::Elf_Addr value,
1891 unsigned char* view,
1892 off_t view_size)
1893 {
1894 // leal foo(,%ebx,1),%eax; call ___tls_get_addr
1895 // ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
1896
1897 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1898 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1899
1900 unsigned char op1 = view[-1];
1901 unsigned char op2 = view[-2];
1902
1903 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1904 op2 == 0x8d || op2 == 0x04);
1905 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1906
1907 int roff = 5;
1908
1909 // FIXME: For now, support only one form.
1910 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1911 op1 == 0x8d && op2 == 0x04);
1912
1913 if (op2 == 0x04)
1914 {
1915 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
1916 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
1917 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1918 ((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
1919 memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
1920 }
1921 else
1922 {
1923 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1924 (op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
1925 if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size
1926 && view[9] == 0x90)
1927 {
1928 // FIXME: This is not the right instruction sequence.
1929 // There is a trailing nop. Use the size byte subl.
1930 memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
1931 roff = 6;
1932 }
1933 else
1934 {
1935 // FIXME: This is not the right instruction sequence.
1936 // Use the five byte subl.
1937 memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
1938 }
1939 }
1940
1941 value = tls_segment->vaddr() + tls_segment->memsz() - value;
1942 Relocate_functions<32, false>::rel32(view + roff, value);
1943
1944 // The next reloc should be a PLT32 reloc against __tls_get_addr.
1945 // We can skip it.
1946 this->skip_call_tls_get_addr_ = true;
1947 }
1948
1949 // Do a relocation in which we convert a TLS Local-Dynamic to a
1950 // Local-Exec.
1951
1952 inline void
1953 Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
1954 size_t relnum,
1955 Output_segment*,
1956 const elfcpp::Rel<32, false>& rel,
1957 unsigned int,
1958 elfcpp::Elf_types<32>::Elf_Addr,
1959 unsigned char* view,
1960 off_t view_size)
1961 {
1962 // leal foo(%reg), %eax; call ___tls_get_addr
1963 // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
1964
1965 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
1966 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
1967
1968 // FIXME: Does this test really always pass?
1969 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
1970 view[-2] == 0x8d && view[-1] == 0x83);
1971
1972 tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
1973
1974 memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
1975
1976 // The next reloc should be a PLT32 reloc against __tls_get_addr.
1977 // We can skip it.
1978 this->skip_call_tls_get_addr_ = true;
1979 }
1980
1981 // Do a relocation in which we convert a TLS Initial-Exec to a
1982 // Local-Exec.
1983
1984 inline void
1985 Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
1986 size_t relnum,
1987 Output_segment* tls_segment,
1988 const elfcpp::Rel<32, false>& rel,
1989 unsigned int r_type,
1990 elfcpp::Elf_types<32>::Elf_Addr value,
1991 unsigned char* view,
1992 off_t view_size)
1993 {
1994 // We have to actually change the instructions, which means that we
1995 // need to examine the opcodes to figure out which instruction we
1996 // are looking at.
1997 if (r_type == elfcpp::R_386_TLS_IE)
1998 {
1999 // movl %gs:XX,%eax ==> movl $YY,%eax
2000 // movl %gs:XX,%reg ==> movl $YY,%reg
2001 // addl %gs:XX,%reg ==> addl $YY,%reg
2002 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
2003 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
2004
2005 unsigned char op1 = view[-1];
2006 if (op1 == 0xa1)
2007 {
2008 // movl XX,%eax ==> movl $YY,%eax
2009 view[-1] = 0xb8;
2010 }
2011 else
2012 {
2013 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
2014
2015 unsigned char op2 = view[-2];
2016 if (op2 == 0x8b)
2017 {
2018 // movl XX,%reg ==> movl $YY,%reg
2019 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2020 (op1 & 0xc7) == 0x05);
2021 view[-2] = 0xc7;
2022 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2023 }
2024 else if (op2 == 0x03)
2025 {
2026 // addl XX,%reg ==> addl $YY,%reg
2027 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2028 (op1 & 0xc7) == 0x05);
2029 view[-2] = 0x81;
2030 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2031 }
2032 else
2033 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
2034 }
2035 }
2036 else
2037 {
2038 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
2039 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
2040 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
2041 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
2042 tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
2043
2044 unsigned char op1 = view[-1];
2045 unsigned char op2 = view[-2];
2046 tls::check_tls(relinfo, relnum, rel.get_r_offset(),
2047 (op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
2048 if (op2 == 0x8b)
2049 {
2050 // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
2051 view[-2] = 0xc7;
2052 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2053 }
2054 else if (op2 == 0x2b)
2055 {
2056 // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
2057 view[-2] = 0x81;
2058 view[-1] = 0xe8 | ((op1 >> 3) & 7);
2059 }
2060 else if (op2 == 0x03)
2061 {
2062 // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
2063 view[-2] = 0x81;
2064 view[-1] = 0xc0 | ((op1 >> 3) & 7);
2065 }
2066 else
2067 tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
2068 }
2069
2070 value = tls_segment->vaddr() + tls_segment->memsz() - value;
2071 if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
2072 value = - value;
2073
2074 Relocate_functions<32, false>::rel32(view, value);
2075 }
2076
2077 // Relocate section data.
2078
2079 void
2080 Target_i386::relocate_section(const Relocate_info<32, false>* relinfo,
2081 unsigned int sh_type,
2082 const unsigned char* prelocs,
2083 size_t reloc_count,
2084 Output_section* output_section,
2085 bool needs_special_offset_handling,
2086 unsigned char* view,
2087 elfcpp::Elf_types<32>::Elf_Addr address,
2088 off_t view_size)
2089 {
2090 gold_assert(sh_type == elfcpp::SHT_REL);
2091
2092 gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
2093 Target_i386::Relocate>(
2094 relinfo,
2095 this,
2096 prelocs,
2097 reloc_count,
2098 output_section,
2099 needs_special_offset_handling,
2100 view,
2101 address,
2102 view_size);
2103 }
2104
2105 // Return the value to use for a dynamic which requires special
2106 // treatment. This is how we support equality comparisons of function
2107 // pointers across shared library boundaries, as described in the
2108 // processor specific ABI supplement.
2109
2110 uint64_t
2111 Target_i386::do_dynsym_value(const Symbol* gsym) const
2112 {
2113 gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
2114 return this->plt_section()->address() + gsym->plt_offset();
2115 }
2116
2117 // Return a string used to fill a code section with nops to take up
2118 // the specified length.
2119
2120 std::string
2121 Target_i386::do_code_fill(off_t length)
2122 {
2123 if (length >= 16)
2124 {
2125 // Build a jmp instruction to skip over the bytes.
2126 unsigned char jmp[5];
2127 jmp[0] = 0xe9;
2128 elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
2129 return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
2130 + std::string(length - 5, '\0'));
2131 }
2132
2133 // Nop sequences of various lengths.
2134 const char nop1[1] = { 0x90 }; // nop
2135 const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax
2136 const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi
2137 const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi
2138 const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop
2139 0x00 }; // leal 0(%esi,1),%esi
2140 const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
2141 0x00, 0x00 };
2142 const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
2143 0x00, 0x00, 0x00 };
2144 const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop
2145 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
2146 const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi
2147 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi
2148 0x00 };
2149 const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
2150 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
2151 0x00, 0x00 };
2152 const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
2153 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
2154 0x00, 0x00, 0x00 };
2155 const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
2156 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
2157 0x00, 0x00, 0x00, 0x00 };
2158 const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
2159 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
2160 0x27, 0x00, 0x00, 0x00,
2161 0x00 };
2162 const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
2163 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
2164 0xbc, 0x27, 0x00, 0x00,
2165 0x00, 0x00 };
2166 const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
2167 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
2168 0x90, 0x90, 0x90, 0x90,
2169 0x90, 0x90, 0x90 };
2170
2171 const char* nops[16] = {
2172 NULL,
2173 nop1, nop2, nop3, nop4, nop5, nop6, nop7,
2174 nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
2175 };
2176
2177 return std::string(nops[length], length);
2178 }
2179
2180 // The selector for i386 object files.
2181
2182 class Target_selector_i386 : public Target_selector
2183 {
2184 public:
2185 Target_selector_i386()
2186 : Target_selector(elfcpp::EM_386, 32, false)
2187 { }
2188
2189 Target*
2190 recognize(int machine, int osabi, int abiversion);
2191
2192 private:
2193 Target_i386* target_;
2194 };
2195
2196 // Recognize an i386 object file when we already know that the machine
2197 // number is EM_386.
2198
2199 Target*
2200 Target_selector_i386::recognize(int, int, int)
2201 {
2202 if (this->target_ == NULL)
2203 this->target_ = new Target_i386();
2204 return this->target_;
2205 }
2206
2207 Target_selector_i386 target_selector_i386;
2208
2209 } // End anonymous namespace.
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