2001-02-28 Andreas Jaeger <aj@suse.de>
[deliverable/binutils-gdb.git] / bfd / elf64-x86-64.c
1 /* X86-64 specific support for 64-bit ELF
2 Copyright 2000, 2001 Free Software Foundation, Inc.
3 Contributed by Jan Hubicka <jh@suse.cz>.
4
5 This file is part of BFD, the Binary File Descriptor library.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
20
21 #include "bfd.h"
22 #include "sysdep.h"
23 #include "libbfd.h"
24 #include "elf-bfd.h"
25
26 #include "elf/x86-64.h"
27
28 /* We use only the RELA entries. */
29 #define USE_RELA
30
31 /* In case we're on a 32-bit machine, construct a 64-bit "-1" value. */
32 #define MINUS_ONE (~ (bfd_vma) 0)
33
34 /* The relocation "howto" table. Order of fields:
35 type, size, bitsize, pc_relative, complain_on_overflow,
36 special_function, name, partial_inplace, src_mask, dst_pack, pcrel_offset. */
37 static reloc_howto_type x86_64_elf_howto_table[] =
38 {
39 HOWTO(R_X86_64_NONE, 0, 0, 0, false, 0, complain_overflow_dont,
40 bfd_elf_generic_reloc, "R_X86_64_NONE", false, 0x00000000, 0x00000000, false),
41 HOWTO(R_X86_64_64, 0, 4, 64, false, 0, complain_overflow_bitfield,
42 bfd_elf_generic_reloc, "R_X86_64_64", false, MINUS_ONE, MINUS_ONE, false),
43 HOWTO(R_X86_64_PC32, 0, 4, 32, true, 0, complain_overflow_signed,
44 bfd_elf_generic_reloc, "R_X86_64_PC32", false, 0xffffffff, 0xffffffff, true),
45 HOWTO(R_X86_64_GOT32, 0, 4, 32, false, 0, complain_overflow_signed,
46 bfd_elf_generic_reloc, "R_X86_64_GOT32", false, 0xffffffff, 0xffffffff, false),
47 HOWTO(R_X86_64_PLT32, 0, 4, 32, true, 0, complain_overflow_signed,
48 bfd_elf_generic_reloc, "R_X86_64_PLT32", false, 0xffffffff, 0xffffffff, true),
49 HOWTO(R_X86_64_COPY, 0, 4, 32, false, 0, complain_overflow_bitfield,
50 bfd_elf_generic_reloc, "R_X86_64_COPY", false, 0xffffffff, 0xffffffff, false),
51 HOWTO(R_X86_64_GLOB_DAT, 0, 4, 64, false, 0, complain_overflow_bitfield,
52 bfd_elf_generic_reloc, "R_X86_64_GLOB_DAT", false, MINUS_ONE, MINUS_ONE, false),
53 HOWTO(R_X86_64_JUMP_SLOT, 0, 4, 64, false, 0, complain_overflow_bitfield,
54 bfd_elf_generic_reloc, "R_X86_64_JUMP_SLOT", false, MINUS_ONE, MINUS_ONE, false),
55 HOWTO(R_X86_64_RELATIVE, 0, 4, 64, false, 0, complain_overflow_bitfield,
56 bfd_elf_generic_reloc, "R_X86_64_RELATIVE", false, MINUS_ONE, MINUS_ONE, false),
57 HOWTO(R_X86_64_GOTPCREL, 0, 4, 32, true,0 , complain_overflow_signed,
58 bfd_elf_generic_reloc, "R_X86_64_GOTPCREL", false, 0xffffffff, 0xffffffff, true),
59 HOWTO(R_X86_64_32, 0, 4, 32, false, 0, complain_overflow_unsigned,
60 bfd_elf_generic_reloc, "R_X86_64_32", false, 0xffffffff, 0xffffffff, false),
61 HOWTO(R_X86_64_32S, 0, 4, 32, false, 0, complain_overflow_signed,
62 bfd_elf_generic_reloc, "R_X86_64_32S", false, 0xffffffff, 0xffffffff, false),
63 HOWTO(R_X86_64_16, 0, 1, 16, false, 0, complain_overflow_bitfield,
64 bfd_elf_generic_reloc, "R_X86_64_16", false, 0xffff, 0xffff, false),
65 HOWTO(R_X86_64_PC16,0, 1, 16, true, 0, complain_overflow_bitfield,
66 bfd_elf_generic_reloc, "R_X86_64_PC16", false, 0xffff, 0xffff, true),
67 HOWTO(R_X86_64_8, 0, 0, 8, false, 0, complain_overflow_signed,
68 bfd_elf_generic_reloc, "R_X86_64_8", false, 0xff, 0xff, false),
69 HOWTO(R_X86_64_PC8, 0, 0, 8, true, 0, complain_overflow_signed,
70 bfd_elf_generic_reloc, "R_X86_64_PC8", false, 0xff, 0xff, true)
71 };
72
73 /* Map BFD relocs to the x86_64 elf relocs. */
74 struct elf_reloc_map
75 {
76 bfd_reloc_code_real_type bfd_reloc_val;
77 unsigned char elf_reloc_val;
78 };
79
80 static CONST struct elf_reloc_map x86_64_reloc_map[] =
81 {
82 { BFD_RELOC_NONE, R_X86_64_NONE, },
83 { BFD_RELOC_64, R_X86_64_64, },
84 { BFD_RELOC_32_PCREL, R_X86_64_PC32, },
85 { BFD_RELOC_X86_64_GOT32, R_X86_64_GOT32,},
86 { BFD_RELOC_X86_64_PLT32, R_X86_64_PLT32,},
87 { BFD_RELOC_X86_64_COPY, R_X86_64_COPY, },
88 { BFD_RELOC_X86_64_GLOB_DAT, R_X86_64_GLOB_DAT, },
89 { BFD_RELOC_X86_64_JUMP_SLOT, R_X86_64_JUMP_SLOT, },
90 { BFD_RELOC_X86_64_RELATIVE, R_X86_64_RELATIVE, },
91 { BFD_RELOC_X86_64_GOTPCREL, R_X86_64_GOTPCREL, },
92 { BFD_RELOC_32, R_X86_64_32, },
93 { BFD_RELOC_X86_64_32S, R_X86_64_32S, },
94 { BFD_RELOC_16, R_X86_64_16, },
95 { BFD_RELOC_16_PCREL, R_X86_64_PC16, },
96 { BFD_RELOC_8, R_X86_64_8, },
97 { BFD_RELOC_8_PCREL, R_X86_64_PC8, },
98 };
99
100 static reloc_howto_type *elf64_x86_64_reloc_type_lookup
101 PARAMS ((bfd *, bfd_reloc_code_real_type));
102 static void elf64_x86_64_info_to_howto
103 PARAMS ((bfd *, arelent *, Elf64_Internal_Rela *));
104 static struct bfd_link_hash_table *elf64_x86_64_link_hash_table_create
105 PARAMS ((bfd *));
106
107 static struct bfd_hash_entry *elf64_x86_64_link_hash_newfunc
108 PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
109 static boolean elf64_x86_64_adjust_dynamic_symbol
110 PARAMS ((struct bfd_link_info *, struct elf_link_hash_entry *));
111
112 static boolean elf64_x86_64_size_dynamic_sections
113 PARAMS ((bfd *, struct bfd_link_info *));
114 static boolean elf64_x86_64_relocate_section
115 PARAMS ((bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
116 Elf_Internal_Rela *, Elf_Internal_Sym *, asection **));
117 static boolean elf64_x86_64_finish_dynamic_symbol
118 PARAMS ((bfd *, struct bfd_link_info *, struct elf_link_hash_entry *,
119 Elf_Internal_Sym *sym));
120 static boolean elf64_x86_64_finish_dynamic_sections
121 PARAMS ((bfd *, struct bfd_link_info *));
122
123 /* Given a BFD reloc type, return a HOWTO structure. */
124 static reloc_howto_type *
125 elf64_x86_64_reloc_type_lookup (abfd, code)
126 bfd *abfd ATTRIBUTE_UNUSED;
127 bfd_reloc_code_real_type code;
128 {
129 unsigned int i;
130 for (i = 0; i < sizeof (x86_64_reloc_map) / sizeof (struct elf_reloc_map);
131 i++)
132 {
133 if (x86_64_reloc_map[i].bfd_reloc_val == code)
134 return &x86_64_elf_howto_table[(int)
135 x86_64_reloc_map[i].elf_reloc_val];
136 }
137 return 0;
138 }
139
140 /* Given an x86_64 ELF reloc type, fill in an arelent structure. */
141
142 static void
143 elf64_x86_64_info_to_howto (abfd, cache_ptr, dst)
144 bfd *abfd ATTRIBUTE_UNUSED;
145 arelent *cache_ptr;
146 Elf64_Internal_Rela *dst;
147 {
148 unsigned r_type;
149
150 r_type = ELF64_R_TYPE (dst->r_info);
151 BFD_ASSERT (r_type < (unsigned int) R_X86_64_max);
152 cache_ptr->howto = &x86_64_elf_howto_table[r_type];
153 BFD_ASSERT (r_type == cache_ptr->howto->type);
154 }
155 \f
156 /* Functions for the x86-64 ELF linker. */
157
158 /* The name of the dynamic interpreter. This is put in the .interp
159 section. */
160
161 #define ELF_DYNAMIC_INTERPRETER "/lib/ld64.so.1"
162
163 /* The size in bytes of an entry in the global offset table. */
164
165 #define GOT_ENTRY_SIZE 8
166
167 /* The size in bytes of an entry in the procedure linkage table. */
168
169 #define PLT_ENTRY_SIZE 16
170
171 /* The first entry in a procedure linkage table looks like this. See the
172 SVR4 ABI i386 supplement and the x86-64 ABI to see how this works. */
173
174 static const bfd_byte elf64_x86_64_plt0_entry[PLT_ENTRY_SIZE] =
175 {
176 0xff, 0xb3, 8, 0, 0, 0, /* pushq GOT+8(%rip) */
177 0xff, 0xa3, 16, 0, 0, 0, /* jmp GOT+16(%rip) */
178 0, 0, 0, 0 /* pad out to 16 bytes. */
179 };
180
181 /* Subsequent entries in a procedure linkage table look like this. */
182
183 static const bfd_byte elf64_x86_64_plt_entry[PLT_ENTRY_SIZE] =
184 {
185 0xff, 0xa3, /* jmp *name@GOTPC(%rip) */
186 0, 0, 0, 0, /* replaced with offset to this symbol in .got. */
187 0x68, /* pushq immediate */
188 0, 0, 0, 0, /* replaced with index into relocation table. */
189 0xe9, /* jmp relative */
190 0, 0, 0, 0 /* replaced with offset to start of .plt0. */
191 };
192
193 /* The x86-64 linker needs to keep track of the number of relocs that
194 it decides to copy in check_relocs for each symbol. This is so
195 that it can discard PC relative relocs if it doesn't need them when
196 linking with -Bsymbolic. We store the information in a field
197 extending the regular ELF linker hash table. */
198
199 /* This structure keeps track of the number of PC relative relocs we
200 have copied for a given symbol. */
201
202 struct elf64_x86_64_pcrel_relocs_copied
203 {
204 /* Next section. */
205 struct elf64_x86_64_pcrel_relocs_copied *next;
206 /* A section in dynobj. */
207 asection *section;
208 /* Number of relocs copied in this section. */
209 bfd_size_type count;
210 };
211
212 /* x86-64 ELF linker hash entry. */
213
214 struct elf64_x86_64_link_hash_entry
215 {
216 struct elf_link_hash_entry root;
217
218 /* Number of PC relative relocs copied for this symbol. */
219 struct elf64_x86_64_pcrel_relocs_copied *pcrel_relocs_copied;
220 };
221
222 /* x86-64 ELF linker hash table. */
223
224 struct elf64_x86_64_link_hash_table
225 {
226 struct elf_link_hash_table root;
227 };
228
229 /* Declare this now that the above structures are defined. */
230
231 static boolean elf64_x86_64_discard_copies
232 PARAMS ((struct elf64_x86_64_link_hash_entry *, PTR));
233
234 /* Traverse an x86-64 ELF linker hash table. */
235
236 #define elf64_x86_64_link_hash_traverse(table, func, info) \
237 (elf_link_hash_traverse \
238 (&(table)->root, \
239 (boolean (*) PARAMS ((struct elf_link_hash_entry *, PTR))) (func), \
240 (info)))
241
242 /* Get the x86-64 ELF linker hash table from a link_info structure. */
243
244 #define elf64_x86_64_hash_table(p) \
245 ((struct elf64_x86_64_link_hash_table *) ((p)->hash))
246
247 /* Create an entry in an x86-64 ELF linker hash table. */
248
249 static struct bfd_hash_entry *
250 elf64_x86_64_link_hash_newfunc (entry, table, string)
251 struct bfd_hash_entry *entry;
252 struct bfd_hash_table *table;
253 const char *string;
254 {
255 struct elf64_x86_64_link_hash_entry *ret =
256 (struct elf64_x86_64_link_hash_entry *) entry;
257
258 /* Allocate the structure if it has not already been allocated by a
259 subclass. */
260 if (ret == (struct elf64_x86_64_link_hash_entry *) NULL)
261 ret = ((struct elf64_x86_64_link_hash_entry *)
262 bfd_hash_allocate (table,
263 sizeof (struct elf64_x86_64_link_hash_entry)));
264 if (ret == (struct elf64_x86_64_link_hash_entry *) NULL)
265 return (struct bfd_hash_entry *) ret;
266
267 /* Call the allocation method of the superclass. */
268 ret = ((struct elf64_x86_64_link_hash_entry *)
269 _bfd_elf_link_hash_newfunc ((struct bfd_hash_entry *) ret,
270 table, string));
271 if (ret != (struct elf64_x86_64_link_hash_entry *) NULL)
272 {
273 ret->pcrel_relocs_copied = NULL;
274 }
275
276 return (struct bfd_hash_entry *) ret;
277 }
278
279 /* Create an X86-64 ELF linker hash table. */
280
281 static struct bfd_link_hash_table *
282 elf64_x86_64_link_hash_table_create (abfd)
283 bfd *abfd;
284 {
285 struct elf64_x86_64_link_hash_table *ret;
286
287 ret = ((struct elf64_x86_64_link_hash_table *)
288 bfd_alloc (abfd, sizeof (struct elf64_x86_64_link_hash_table)));
289 if (ret == (struct elf64_x86_64_link_hash_table *) NULL)
290 return NULL;
291
292 if (! _bfd_elf_link_hash_table_init (&ret->root, abfd,
293 elf64_x86_64_link_hash_newfunc))
294 {
295 bfd_release (abfd, ret);
296 return NULL;
297 }
298
299 return &ret->root.root;
300 }
301
302 boolean
303 elf64_x86_64_elf_object_p (abfd)
304 bfd *abfd;
305 {
306 /* Set the right machine number for an x86-64 elf64 file. */
307 bfd_default_set_arch_mach (abfd, bfd_arch_i386, bfd_mach_x86_64);
308 return true;
309 }
310
311 /* Look through the relocs for a section during the first phase, and
312 allocate space in the global offset table or procedure linkage
313 table. */
314
315 static boolean
316 elf64_x86_64_check_relocs (abfd, info, sec, relocs)
317 bfd *abfd;
318 struct bfd_link_info *info;
319 asection *sec;
320 const Elf_Internal_Rela *relocs;
321 {
322 bfd *dynobj;
323 Elf_Internal_Shdr *symtab_hdr;
324 struct elf_link_hash_entry **sym_hashes;
325 bfd_signed_vma *local_got_refcounts;
326 const Elf_Internal_Rela *rel;
327 const Elf_Internal_Rela *rel_end;
328 asection *sgot;
329 asection *srelgot;
330 asection *sreloc;
331
332 if (info->relocateable)
333 return true;
334
335 dynobj = elf_hash_table (info)->dynobj;
336 symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
337 sym_hashes = elf_sym_hashes (abfd);
338 local_got_refcounts = elf_local_got_refcounts (abfd);
339
340 sgot = srelgot = sreloc = NULL;
341 rel_end = relocs + sec->reloc_count;
342 for (rel = relocs; rel < rel_end; rel++)
343 {
344 unsigned long r_symndx;
345 struct elf_link_hash_entry *h;
346
347 r_symndx = ELF64_R_SYM (rel->r_info);
348 if (r_symndx < symtab_hdr->sh_info)
349 h = NULL;
350 else
351 h = sym_hashes[r_symndx - symtab_hdr->sh_info];
352
353 /* Some relocs require a global offset table. */
354 if (dynobj == NULL)
355 {
356 switch (ELF64_R_TYPE (rel->r_info))
357 {
358 case R_X86_64_GOT32:
359 case R_X86_64_GOTPCREL:
360 elf_hash_table (info)->dynobj = dynobj = abfd;
361 if (! _bfd_elf_create_got_section (dynobj, info))
362 return false;
363 break;
364 }
365 }
366
367 switch (ELF64_R_TYPE (rel->r_info))
368 {
369 case R_X86_64_GOTPCREL:
370 case R_X86_64_GOT32:
371 /* This symbol requires a global offset table entry. */
372
373 if (sgot == NULL)
374 {
375 sgot = bfd_get_section_by_name (dynobj, ".got");
376 BFD_ASSERT (sgot != NULL);
377 }
378
379 if (srelgot == NULL && (h != NULL || info->shared))
380 {
381 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
382 if (srelgot == NULL)
383 {
384 srelgot = bfd_make_section (dynobj, ".rela.got");
385 if (srelgot == NULL
386 || ! bfd_set_section_flags (dynobj, srelgot,
387 (SEC_ALLOC
388 | SEC_LOAD
389 | SEC_HAS_CONTENTS
390 | SEC_IN_MEMORY
391 | SEC_LINKER_CREATED
392 | SEC_READONLY))
393 || ! bfd_set_section_alignment (dynobj, srelgot, 3))
394 return false;
395 }
396 }
397
398 if (h != NULL)
399 {
400 if (h->got.refcount == -1)
401 {
402 h->got.refcount = 1;
403
404 /* Make sure this symbol is output as a dynamic symbol. */
405 if (h->dynindx == -1)
406 {
407 if (! bfd_elf64_link_record_dynamic_symbol (info, h))
408 return false;
409 }
410
411 sgot->_raw_size += GOT_ENTRY_SIZE;
412 srelgot->_raw_size += sizeof (Elf64_External_Rela);
413 }
414 else
415 h->got.refcount += 1;
416 }
417 else
418 {
419 /* This is a global offset table entry for a local symbol. */
420 if (local_got_refcounts == NULL)
421 {
422 size_t size;
423
424 size = symtab_hdr->sh_info * sizeof (bfd_signed_vma);
425 local_got_refcounts = ((bfd_signed_vma *)
426 bfd_alloc (abfd, size));
427 if (local_got_refcounts == NULL)
428 return false;
429 elf_local_got_refcounts (abfd) = local_got_refcounts;
430 memset (local_got_refcounts, -1, size);
431 }
432 if (local_got_refcounts[r_symndx] == -1)
433 {
434 local_got_refcounts[r_symndx] = 1;
435
436 sgot->_raw_size += GOT_ENTRY_SIZE;
437 if (info->shared)
438 {
439 /* If we are generating a shared object, we need to
440 output a R_X86_64_RELATIVE reloc so that the dynamic
441 linker can adjust this GOT entry. */
442 srelgot->_raw_size += sizeof (Elf64_External_Rela);
443 }
444 }
445 else
446 local_got_refcounts[r_symndx] += 1;
447 }
448 break;
449
450 case R_X86_64_PLT32:
451 /* This symbol requires a procedure linkage table entry. We
452 actually build the entry in adjust_dynamic_symbol,
453 because this might be a case of linking PIC code which is
454 never referenced by a dynamic object, in which case we
455 don't need to generate a procedure linkage table entry
456 after all. */
457
458 /* If this is a local symbol, we resolve it directly without
459 creating a procedure linkage table entry. */
460 if (h == NULL)
461 continue;
462
463 if (h->plt.refcount == -1)
464 {
465 h->plt.refcount = 1;
466 h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
467 }
468 else
469 h->plt.refcount += 1;
470 break;
471
472 case R_X86_64_32:
473 case R_X86_64_32S:
474 case R_X86_64_PC32:
475 if (h != NULL)
476 h->elf_link_hash_flags |= ELF_LINK_NON_GOT_REF;
477
478 /* If we are creating a shared library, and this is a reloc
479 against a global symbol, or a non PC relative reloc
480 against a local symbol, then we need to copy the reloc
481 into the shared library. However, if we are linking with
482 -Bsymbolic, we do not need to copy a reloc against a
483 global symbol which is defined in an object we are
484 including in the link (i.e., DEF_REGULAR is set). At
485 this point we have not seen all the input files, so it is
486 possible that DEF_REGULAR is not set now but will be set
487 later (it is never cleared). We account for that
488 possibility below by storing information in the
489 pcrel_relocs_copied field of the hash table entry.
490 A similar situation occurs when creating shared libraries
491 and symbol visibility changes render the symbol local. */
492 if (info->shared
493 && (sec->flags & SEC_ALLOC) != 0
494 && (ELF64_R_TYPE (rel->r_info) != R_X86_64_PC32
495 || (h != NULL
496 && (! info->symbolic
497 || (h->elf_link_hash_flags
498 & ELF_LINK_HASH_DEF_REGULAR) == 0))))
499 {
500 /* When creating a shared object, we must copy these
501 reloc types into the output file. We create a reloc
502 section in dynobj and make room for this reloc. */
503 if (sreloc == NULL)
504 {
505 const char *name;
506
507 name = (bfd_elf_string_from_elf_section
508 (abfd,
509 elf_elfheader (abfd)->e_shstrndx,
510 elf_section_data (sec)->rel_hdr.sh_name));
511 if (name == NULL)
512 return false;
513
514 BFD_ASSERT (strncmp (name, ".rela", 5) == 0
515 && strcmp (bfd_get_section_name (abfd, sec),
516 name + 5) == 0);
517
518 sreloc = bfd_get_section_by_name (dynobj, name);
519 if (sreloc == NULL)
520 {
521 flagword flags;
522
523 sreloc = bfd_make_section (dynobj, name);
524 flags = (SEC_HAS_CONTENTS | SEC_READONLY
525 | SEC_IN_MEMORY | SEC_LINKER_CREATED);
526 if ((sec->flags & SEC_ALLOC) != 0)
527 flags |= SEC_ALLOC | SEC_LOAD;
528 if (sreloc == NULL
529 || ! bfd_set_section_flags (dynobj, sreloc, flags)
530 || ! bfd_set_section_alignment (dynobj, sreloc, 2))
531 return false;
532 }
533 }
534
535 sreloc->_raw_size += sizeof (Elf64_External_Rela);
536
537 /* If this is a global symbol, we count the number of PC
538 relative relocations we have entered for this symbol,
539 so that we can discard them later as necessary. Note
540 that this function is only called if we are using an
541 elf64_x86_64 linker hash table, which means that h is
542 really a pointer to an elf64_x86_64_link_hash_entry. */
543 if (h != NULL
544 && ELF64_R_TYPE (rel->r_info) == R_X86_64_PC32)
545 {
546 struct elf64_x86_64_link_hash_entry *eh;
547 struct elf64_x86_64_pcrel_relocs_copied *p;
548
549 eh = (struct elf64_x86_64_link_hash_entry *) h;
550
551 for (p = eh->pcrel_relocs_copied; p != NULL; p = p->next)
552 if (p->section == sreloc)
553 break;
554
555 if (p == NULL)
556 {
557 p = ((struct elf64_x86_64_pcrel_relocs_copied *)
558 bfd_alloc (dynobj, sizeof *p));
559 if (p == NULL)
560 return false;
561 p->next = eh->pcrel_relocs_copied;
562 eh->pcrel_relocs_copied = p;
563 p->section = sreloc;
564 p->count = 0;
565 }
566
567 ++p->count;
568 }
569 }
570 break;
571 }
572 }
573
574 return true;
575 }
576
577 /* Return the section that should be marked against GC for a given
578 relocation. */
579
580 static asection *
581 elf64_x86_64_gc_mark_hook (abfd, info, rel, h, sym)
582 bfd *abfd;
583 struct bfd_link_info *info ATTRIBUTE_UNUSED;
584 Elf_Internal_Rela *rel ATTRIBUTE_UNUSED;
585 struct elf_link_hash_entry *h;
586 Elf_Internal_Sym *sym;
587 {
588 if (h != NULL)
589 {
590 switch (h->root.type)
591 {
592 case bfd_link_hash_defined:
593 case bfd_link_hash_defweak:
594 return h->root.u.def.section;
595
596 case bfd_link_hash_common:
597 return h->root.u.c.p->section;
598
599 default:
600 break;
601 }
602 }
603 else
604 {
605 if (!(elf_bad_symtab (abfd)
606 && ELF_ST_BIND (sym->st_info) != STB_LOCAL)
607 && ! ((sym->st_shndx <= 0 || sym->st_shndx >= SHN_LORESERVE)
608 && sym->st_shndx != SHN_COMMON))
609 {
610 return bfd_section_from_elf_index (abfd, sym->st_shndx);
611 }
612 }
613
614 return NULL;
615 }
616
617 /* Update the got entry reference counts for the section being removed. */
618
619 static boolean
620 elf64_x86_64_gc_sweep_hook (abfd, info, sec, relocs)
621 bfd *abfd;
622 struct bfd_link_info *info ATTRIBUTE_UNUSED;
623 asection *sec;
624 const Elf_Internal_Rela *relocs;
625 {
626 Elf_Internal_Shdr *symtab_hdr;
627 struct elf_link_hash_entry **sym_hashes;
628 bfd_signed_vma *local_got_refcounts;
629 const Elf_Internal_Rela *rel, *relend;
630 unsigned long r_symndx;
631 struct elf_link_hash_entry *h;
632 bfd *dynobj;
633 asection *sgot;
634 asection *srelgot;
635
636 symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
637 sym_hashes = elf_sym_hashes (abfd);
638 local_got_refcounts = elf_local_got_refcounts (abfd);
639
640 dynobj = elf_hash_table (info)->dynobj;
641 if (dynobj == NULL)
642 return true;
643
644 sgot = bfd_get_section_by_name (dynobj, ".got");
645 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
646
647 relend = relocs + sec->reloc_count;
648 for (rel = relocs; rel < relend; rel++)
649 switch (ELF64_R_TYPE (rel->r_info))
650 {
651 case R_X86_64_GOT32:
652 case R_X86_64_GOTPCREL:
653 r_symndx = ELF64_R_SYM (rel->r_info);
654 if (r_symndx >= symtab_hdr->sh_info)
655 {
656 h = sym_hashes[r_symndx - symtab_hdr->sh_info];
657 if (h->got.refcount > 0)
658 {
659 h->got.refcount -= 1;
660 if (h->got.refcount == 0)
661 {
662 sgot->_raw_size -= GOT_ENTRY_SIZE;
663 srelgot->_raw_size -= sizeof (Elf64_External_Rela);
664 }
665 }
666 }
667 else if (local_got_refcounts != NULL)
668 {
669 if (local_got_refcounts[r_symndx] > 0)
670 {
671 local_got_refcounts[r_symndx] -= 1;
672 if (local_got_refcounts[r_symndx] == 0)
673 {
674 sgot->_raw_size -= GOT_ENTRY_SIZE;
675 if (info->shared)
676 srelgot->_raw_size -= sizeof (Elf64_External_Rela);
677 }
678 }
679 }
680 break;
681
682 case R_X86_64_PLT32:
683 r_symndx = ELF64_R_SYM (rel->r_info);
684 if (r_symndx >= symtab_hdr->sh_info)
685 {
686 h = sym_hashes[r_symndx - symtab_hdr->sh_info];
687 if (h->plt.refcount > 0)
688 h->plt.refcount -= 1;
689 }
690 break;
691
692 default:
693 break;
694 }
695
696 return true;
697 }
698
699 /* Adjust a symbol defined by a dynamic object and referenced by a
700 regular object. The current definition is in some section of the
701 dynamic object, but we're not including those sections. We have to
702 change the definition to something the rest of the link can
703 understand. */
704
705 static boolean
706 elf64_x86_64_adjust_dynamic_symbol (info, h)
707 struct bfd_link_info *info;
708 struct elf_link_hash_entry *h;
709 {
710 bfd *dynobj;
711 asection *s;
712 unsigned int power_of_two;
713
714 dynobj = elf_hash_table (info)->dynobj;
715
716 /* Make sure we know what is going on here. */
717 BFD_ASSERT (dynobj != NULL
718 && ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT)
719 || h->weakdef != NULL
720 || ((h->elf_link_hash_flags
721 & ELF_LINK_HASH_DEF_DYNAMIC) != 0
722 && (h->elf_link_hash_flags
723 & ELF_LINK_HASH_REF_REGULAR) != 0
724 && (h->elf_link_hash_flags
725 & ELF_LINK_HASH_DEF_REGULAR) == 0)));
726
727 /* If this is a function, put it in the procedure linkage table. We
728 will fill in the contents of the procedure linkage table later,
729 when we know the address of the .got section. */
730 if (h->type == STT_FUNC
731 || (h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_PLT) != 0)
732 {
733 if ((! info->shared
734 && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_DYNAMIC) == 0
735 && (h->elf_link_hash_flags & ELF_LINK_HASH_REF_DYNAMIC) == 0)
736 || (info->shared && h->plt.refcount <= 0))
737 {
738 /* This case can occur if we saw a PLT32 reloc in an input
739 file, but the symbol was never referred to by a dynamic
740 object, or if all references were garbage collected. In
741 such a case, we don't actually need to build a procedure
742 linkage table, and we can just do a PC32 reloc instead. */
743 h->plt.offset = (bfd_vma) -1;
744 h->elf_link_hash_flags &= ~ELF_LINK_HASH_NEEDS_PLT;
745 return true;
746 }
747
748 /* Make sure this symbol is output as a dynamic symbol. */
749 if (h->dynindx == -1)
750 {
751 if (! bfd_elf64_link_record_dynamic_symbol (info, h))
752 return false;
753 }
754
755 s = bfd_get_section_by_name (dynobj, ".plt");
756 BFD_ASSERT (s != NULL);
757
758 /* If this is the first .plt entry, make room for the special
759 first entry. */
760 if (s->_raw_size == 0)
761 s->_raw_size = PLT_ENTRY_SIZE;
762
763 /* If this symbol is not defined in a regular file, and we are
764 not generating a shared library, then set the symbol to this
765 location in the .plt. This is required to make function
766 pointers compare as equal between the normal executable and
767 the shared library. */
768 if (! info->shared
769 && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0)
770 {
771 h->root.u.def.section = s;
772 h->root.u.def.value = s->_raw_size;
773 }
774
775 h->plt.offset = s->_raw_size;
776
777 /* Make room for this entry. */
778 s->_raw_size += PLT_ENTRY_SIZE;
779
780 /* We also need to make an entry in the .got.plt section, which
781 will be placed in the .got section by the linker script. */
782 s = bfd_get_section_by_name (dynobj, ".got.plt");
783 BFD_ASSERT (s != NULL);
784 s->_raw_size += GOT_ENTRY_SIZE;
785
786 /* We also need to make an entry in the .rela.plt section. */
787 s = bfd_get_section_by_name (dynobj, ".rela.plt");
788 BFD_ASSERT (s != NULL);
789 s->_raw_size += sizeof (Elf64_External_Rela);
790
791 return true;
792 }
793
794 /* If this is a weak symbol, and there is a real definition, the
795 processor independent code will have arranged for us to see the
796 real definition first, and we can just use the same value. */
797 if (h->weakdef != NULL)
798 {
799 BFD_ASSERT (h->weakdef->root.type == bfd_link_hash_defined
800 || h->weakdef->root.type == bfd_link_hash_defweak);
801 h->root.u.def.section = h->weakdef->root.u.def.section;
802 h->root.u.def.value = h->weakdef->root.u.def.value;
803 return true;
804 }
805
806 /* This is a reference to a symbol defined by a dynamic object which
807 is not a function. */
808
809 /* If we are creating a shared library, we must presume that the
810 only references to the symbol are via the global offset table.
811 For such cases we need not do anything here; the relocations will
812 be handled correctly by relocate_section. */
813 if (info->shared)
814 return true;
815
816 /* If there are no references to this symbol that do not use the
817 GOT, we don't need to generate a copy reloc. */
818 if ((h->elf_link_hash_flags & ELF_LINK_NON_GOT_REF) == 0)
819 return true;
820
821 /* We must allocate the symbol in our .dynbss section, which will
822 become part of the .bss section of the executable. There will be
823 an entry for this symbol in the .dynsym section. The dynamic
824 object will contain position independent code, so all references
825 from the dynamic object to this symbol will go through the global
826 offset table. The dynamic linker will use the .dynsym entry to
827 determine the address it must put in the global offset table, so
828 both the dynamic object and the regular object will refer to the
829 same memory location for the variable. */
830
831 s = bfd_get_section_by_name (dynobj, ".dynbss");
832 BFD_ASSERT (s != NULL);
833
834 /* We must generate a R_X86_64_COPY reloc to tell the dynamic linker
835 to copy the initial value out of the dynamic object and into the
836 runtime process image. We need to remember the offset into the
837 .rela.bss section we are going to use. */
838 if ((h->root.u.def.section->flags & SEC_ALLOC) != 0)
839 {
840 asection *srel;
841
842 srel = bfd_get_section_by_name (dynobj, ".rela.bss");
843 BFD_ASSERT (srel != NULL);
844 srel->_raw_size += sizeof (Elf64_External_Rela);
845 h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_COPY;
846 }
847
848 /* We need to figure out the alignment required for this symbol. I
849 have no idea how ELF linkers handle this. 16-bytes is the size
850 of the largest type that requires hard alignment -- long double. */
851 /* FIXME: This is VERY ugly. Should be fixed for all architectures using
852 this construct. */
853 power_of_two = bfd_log2 (h->size);
854 if (power_of_two > 4)
855 power_of_two = 4;
856
857 /* Apply the required alignment. */
858 s->_raw_size = BFD_ALIGN (s->_raw_size, (bfd_size_type) (1 << power_of_two));
859 if (power_of_two > bfd_get_section_alignment (dynobj, s))
860 {
861 if (! bfd_set_section_alignment (dynobj, s, power_of_two))
862 return false;
863 }
864
865 /* Define the symbol as being at this point in the section. */
866 h->root.u.def.section = s;
867 h->root.u.def.value = s->_raw_size;
868
869 /* Increment the section size to make room for the symbol. */
870 s->_raw_size += h->size;
871
872 return true;
873 }
874
875 /* Set the sizes of the dynamic sections. */
876
877 static boolean
878 elf64_x86_64_size_dynamic_sections (output_bfd, info)
879 bfd *output_bfd;
880 struct bfd_link_info *info;
881 {
882 bfd *dynobj;
883 asection *s;
884 boolean plt;
885 boolean relocs;
886 boolean reltext;
887
888 dynobj = elf_hash_table (info)->dynobj;
889 BFD_ASSERT (dynobj != NULL);
890
891 if (elf_hash_table (info)->dynamic_sections_created)
892 {
893 /* Set the contents of the .interp section to the interpreter. */
894 if (! info->shared)
895 {
896 s = bfd_get_section_by_name (dynobj, ".interp");
897 BFD_ASSERT (s != NULL);
898 s->_raw_size = sizeof ELF_DYNAMIC_INTERPRETER;
899 s->contents = (unsigned char *) ELF_DYNAMIC_INTERPRETER;
900 }
901 }
902 else
903 {
904 /* We may have created entries in the .rela.got section.
905 However, if we are not creating the dynamic sections, we will
906 not actually use these entries. Reset the size of .rela.got,
907 which will cause it to get stripped from the output file
908 below. */
909 s = bfd_get_section_by_name (dynobj, ".rela.got");
910 if (s != NULL)
911 s->_raw_size = 0;
912 }
913
914 /* If this is a -Bsymbolic shared link, then we need to discard all
915 PC relative relocs against symbols defined in a regular object.
916 We allocated space for them in the check_relocs routine, but we
917 will not fill them in in the relocate_section routine. */
918 if (info->shared)
919 elf64_x86_64_link_hash_traverse (elf64_x86_64_hash_table (info),
920 elf64_x86_64_discard_copies,
921 (PTR) info);
922
923 /* The check_relocs and adjust_dynamic_symbol entry points have
924 determined the sizes of the various dynamic sections. Allocate
925 memory for them. */
926 plt = relocs = reltext = false;
927 for (s = dynobj->sections; s != NULL; s = s->next)
928 {
929 const char *name;
930 boolean strip;
931
932 if ((s->flags & SEC_LINKER_CREATED) == 0)
933 continue;
934
935 /* It's OK to base decisions on the section name, because none
936 of the dynobj section names depend upon the input files. */
937 name = bfd_get_section_name (dynobj, s);
938
939 strip = false;
940 if (strcmp (name, ".plt") == 0)
941 {
942 if (s->_raw_size == 0)
943 {
944 /* Strip this section if we don't need it; see the
945 comment below. */
946 strip = true;
947 }
948 else
949 {
950 /* Remember whether there is a PLT. */
951 plt = true;
952 }
953 }
954 else if (strncmp (name, ".rela", 5) == 0)
955 {
956 if (s->_raw_size == 0)
957 {
958 /* If we don't need this section, strip it from the
959 output file. This is mostly to handle .rela.bss and
960 .rela.plt. We must create both sections in
961 create_dynamic_sections, because they must be created
962 before the linker maps input sections to output
963 sections. The linker does that before
964 adjust_dynamic_symbol is called, and it is that
965 function which decides whether anything needs to go
966 into these sections. */
967 strip = true;
968 }
969 else
970 {
971 asection *target;
972
973 /* Remember whether there are any reloc sections other
974 than .rela.plt. */
975 if (strcmp (name, ".rela.plt") != 0)
976 {
977 const char *outname;
978
979 relocs = true;
980
981 /* If this relocation section applies to a read only
982 section, then we probably need a DT_TEXTREL
983 entry. The entries in the .rela.plt section
984 really apply to the .got section, which we
985 created ourselves and so know is not readonly. */
986 outname = bfd_get_section_name (output_bfd,
987 s->output_section);
988 target = bfd_get_section_by_name (output_bfd, outname + 5);
989 if (target != NULL
990 && (target->flags & SEC_READONLY) != 0
991 && (target->flags & SEC_ALLOC) != 0)
992 reltext = true;
993 }
994
995 /* We use the reloc_count field as a counter if we need
996 to copy relocs into the output file. */
997 s->reloc_count = 0;
998 }
999 }
1000 else if (strncmp (name, ".got", 4) != 0)
1001 {
1002 /* It's not one of our sections, so don't allocate space. */
1003 continue;
1004 }
1005
1006 if (strip)
1007 {
1008 _bfd_strip_section_from_output (info, s);
1009 continue;
1010 }
1011
1012 /* Allocate memory for the section contents. We use bfd_zalloc
1013 here in case unused entries are not reclaimed before the
1014 section's contents are written out. This should not happen,
1015 but this way if it does, we get a R_X86_64_NONE reloc instead
1016 of garbage. */
1017 s->contents = (bfd_byte *) bfd_zalloc (dynobj, s->_raw_size);
1018 if (s->contents == NULL && s->_raw_size != 0)
1019 return false;
1020 }
1021
1022 if (elf_hash_table (info)->dynamic_sections_created)
1023 {
1024 /* Add some entries to the .dynamic section. We fill in the
1025 values later, in elf64_x86_64_finish_dynamic_sections, but we
1026 must add the entries now so that we get the correct size for
1027 the .dynamic section. The DT_DEBUG entry is filled in by the
1028 dynamic linker and used by the debugger. */
1029 if (! info->shared)
1030 {
1031 if (! bfd_elf64_add_dynamic_entry (info, DT_DEBUG, 0))
1032 return false;
1033 }
1034
1035 if (plt)
1036 {
1037 if (! bfd_elf64_add_dynamic_entry (info, DT_PLTGOT, 0)
1038 || ! bfd_elf64_add_dynamic_entry (info, DT_PLTRELSZ, 0)
1039 || ! bfd_elf64_add_dynamic_entry (info, DT_PLTREL, DT_RELA)
1040 || ! bfd_elf64_add_dynamic_entry (info, DT_JMPREL, 0))
1041 return false;
1042 }
1043
1044 if (relocs)
1045 {
1046 if (! bfd_elf64_add_dynamic_entry (info, DT_RELA, 0)
1047 || ! bfd_elf64_add_dynamic_entry (info, DT_RELASZ, 0)
1048 || ! bfd_elf64_add_dynamic_entry (info, DT_RELAENT,
1049 sizeof (Elf64_External_Rela)))
1050 return false;
1051 }
1052
1053 if (reltext)
1054 {
1055 if (! bfd_elf64_add_dynamic_entry (info, DT_TEXTREL, 0))
1056 return false;
1057 info->flags |= DF_TEXTREL;
1058 }
1059 }
1060
1061 return true;
1062 }
1063
1064 /* This function is called via elf64_x86_64_link_hash_traverse if we are
1065 creating a shared object. In the -Bsymbolic case, it discards the
1066 space allocated to copy PC relative relocs against symbols which
1067 are defined in regular objects. For the normal non-symbolic case,
1068 we also discard space for relocs that have become local due to
1069 symbol visibility changes. We allocated space for them in the
1070 check_relocs routine, but we won't fill them in in the
1071 relocate_section routine. */
1072
1073 static boolean
1074 elf64_x86_64_discard_copies (h, inf)
1075 struct elf64_x86_64_link_hash_entry *h;
1076 PTR inf;
1077 {
1078 struct elf64_x86_64_pcrel_relocs_copied *s;
1079 struct bfd_link_info *info = (struct bfd_link_info *) inf;
1080
1081 /* If a symbol has been forced local or we have found a regular
1082 definition for the symbolic link case, then we won't be needing
1083 any relocs. */
1084 if ((h->root.elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) != 0
1085 && ((h->root.elf_link_hash_flags & ELF_LINK_FORCED_LOCAL) != 0
1086 || info->symbolic))
1087 {
1088 for (s = h->pcrel_relocs_copied; s != NULL; s = s->next)
1089 s->section->_raw_size -= s->count * sizeof (Elf64_External_Rela);
1090 }
1091
1092 return true;
1093 }
1094
1095 /* Relocate an x86_64 ELF section. */
1096
1097 static boolean
1098 elf64_x86_64_relocate_section (output_bfd, info, input_bfd, input_section,
1099 contents, relocs, local_syms, local_sections)
1100 bfd *output_bfd;
1101 struct bfd_link_info *info;
1102 bfd *input_bfd;
1103 asection *input_section;
1104 bfd_byte *contents;
1105 Elf_Internal_Rela *relocs;
1106 Elf_Internal_Sym *local_syms;
1107 asection **local_sections;
1108 {
1109 bfd *dynobj;
1110 Elf_Internal_Shdr *symtab_hdr;
1111 struct elf_link_hash_entry **sym_hashes;
1112 bfd_vma *local_got_offsets;
1113 asection *sgot;
1114 asection *splt;
1115 asection *sreloc;
1116 Elf_Internal_Rela *rela;
1117 Elf_Internal_Rela *relend;
1118
1119 dynobj = elf_hash_table (info)->dynobj;
1120 symtab_hdr = &elf_tdata (input_bfd)->symtab_hdr;
1121 sym_hashes = elf_sym_hashes (input_bfd);
1122 local_got_offsets = elf_local_got_offsets (input_bfd);
1123
1124 sreloc = splt = sgot = NULL;
1125 if (dynobj != NULL)
1126 {
1127 splt = bfd_get_section_by_name (dynobj, ".plt");
1128 sgot = bfd_get_section_by_name (dynobj, ".got");
1129 }
1130
1131 rela = relocs;
1132 relend = relocs + input_section->reloc_count;
1133 for (; rela < relend; rela++)
1134 {
1135 int r_type;
1136 reloc_howto_type *howto;
1137 unsigned long r_symndx;
1138 struct elf_link_hash_entry *h;
1139 Elf_Internal_Sym *sym;
1140 asection *sec;
1141 bfd_vma relocation;
1142 bfd_reloc_status_type r;
1143 unsigned int indx;
1144
1145 r_type = ELF64_R_TYPE (rela->r_info);
1146
1147 if ((indx = (unsigned) r_type) >= R_X86_64_max)
1148 {
1149 bfd_set_error (bfd_error_bad_value);
1150 return false;
1151 }
1152 howto = x86_64_elf_howto_table + indx;
1153
1154 r_symndx = ELF64_R_SYM (rela->r_info);
1155
1156 if (info->relocateable)
1157 {
1158 /* This is a relocateable link. We don't have to change
1159 anything, unless the reloc is against a section symbol,
1160 in which case we have to adjust according to where the
1161 section symbol winds up in the output section. */
1162 if (r_symndx < symtab_hdr->sh_info)
1163 {
1164 sym = local_syms + r_symndx;
1165 if (ELF_ST_TYPE (sym->st_info) == STT_SECTION)
1166 {
1167 sec = local_sections[r_symndx];
1168 rela->r_addend += sec->output_offset + sym->st_value;
1169 }
1170 }
1171
1172 continue;
1173 }
1174
1175 /* This is a final link. */
1176 h = NULL;
1177 sym = NULL;
1178 sec = NULL;
1179 if (r_symndx < symtab_hdr->sh_info)
1180 {
1181 sym = local_syms + r_symndx;
1182 sec = local_sections[r_symndx];
1183 relocation = (sec->output_section->vma
1184 + sec->output_offset
1185 + sym->st_value);
1186 }
1187 else
1188 {
1189 h = sym_hashes[r_symndx - symtab_hdr->sh_info];
1190 while (h->root.type == bfd_link_hash_indirect
1191 || h->root.type == bfd_link_hash_warning)
1192 h = (struct elf_link_hash_entry *) h->root.u.i.link;
1193 if (h->root.type == bfd_link_hash_defined
1194 || h->root.type == bfd_link_hash_defweak)
1195 {
1196 sec = h->root.u.def.section;
1197 if (sec->output_section == NULL)
1198 {
1199 (*_bfd_error_handler)
1200 (_("%s: warning: unresolvable relocation against symbol `%s' from %s section"),
1201 bfd_get_filename (input_bfd), h->root.root.string,
1202 bfd_get_section_name (input_bfd, input_section));
1203 relocation = 0;
1204 }
1205 else
1206 relocation = (h->root.u.def.value
1207 + sec->output_section->vma
1208 + sec->output_offset);
1209 }
1210 else if (h->root.type == bfd_link_hash_undefweak)
1211 relocation = 0;
1212 else if (info->shared && !info->symbolic && !info->no_undefined
1213 && ELF_ST_VISIBILITY (h->other) == STV_DEFAULT)
1214 relocation = 0;
1215 else
1216 {
1217 if (! ((*info->callbacks->undefined_symbol)
1218 (info, h->root.root.string, input_bfd,
1219 input_section, rela->r_offset,
1220 (!info->shared || info->no_undefined
1221 || ELF_ST_VISIBILITY (h->other)))))
1222 return false;
1223 relocation = 0;
1224 }
1225 }
1226
1227 /* When generating a shared object, the relocations handled here are
1228 copied into the output file to be resolved at run time. */
1229 switch (r_type)
1230 {
1231 case R_X86_64_GOT32:
1232 /* Relocation is to the entry for this symbol in the global
1233 offset table. */
1234 BFD_ASSERT (sgot != NULL);
1235
1236 if (h != NULL)
1237 {
1238 bfd_vma off = h->got.offset;
1239 BFD_ASSERT (off != (bfd_vma) -1);
1240
1241 if (! elf_hash_table (info)->dynamic_sections_created
1242 || (info->shared
1243 && (info->symbolic || h->dynindx == -1)
1244 && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
1245 {
1246 /* This is actually a static link, or it is a -Bsymbolic
1247 link and the symbol is defined locally, or the symbol
1248 was forced to be local because of a version file. We
1249 must initialize this entry in the global offset table.
1250 Since the offset must always be a multiple of 8, we
1251 use the least significant bit to record whether we
1252 have initialized it already.
1253
1254 When doing a dynamic link, we create a .rela.got
1255 relocation entry to initialize the value. This is
1256 done in the finish_dynamic_symbol routine. */
1257 if ((off & 1) != 0)
1258 off &= ~1;
1259 else
1260 {
1261 bfd_put_64 (output_bfd, relocation,
1262 sgot->contents + off);
1263 h->got.offset |= 1;
1264 }
1265 }
1266 relocation = sgot->output_offset + off;
1267 }
1268 else
1269 {
1270 bfd_vma off;
1271
1272 BFD_ASSERT (local_got_offsets != NULL
1273 && local_got_offsets[r_symndx] != (bfd_vma) -1);
1274
1275 off = local_got_offsets[r_symndx];
1276
1277 /* The offset must always be a multiple of 8. We use
1278 the least significant bit to record whether we have
1279 already generated the necessary reloc. */
1280 if ((off & 1) != 0)
1281 off &= ~1;
1282 else
1283 {
1284 bfd_put_64 (output_bfd, relocation, sgot->contents + off);
1285
1286 if (info->shared)
1287 {
1288 asection *srelgot;
1289 Elf_Internal_Rela outrel;
1290
1291 /* We need to generate a R_X86_64_RELATIVE reloc
1292 for the dynamic linker. */
1293 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
1294 BFD_ASSERT (srelgot != NULL);
1295
1296 outrel.r_offset = (sgot->output_section->vma
1297 + sgot->output_offset
1298 + off);
1299 outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
1300 outrel.r_addend = relocation;
1301 bfd_elf64_swap_reloca_out (output_bfd, &outrel,
1302 (((Elf64_External_Rela *)
1303 srelgot->contents)
1304 + srelgot->reloc_count));
1305 ++srelgot->reloc_count;
1306 }
1307
1308 local_got_offsets[r_symndx] |= 1;
1309 }
1310
1311 relocation = sgot->output_offset + off;
1312 }
1313
1314 break;
1315
1316 case R_X86_64_GOTPCREL:
1317 /* Use global offset table as symbol value. */
1318
1319 BFD_ASSERT (sgot != NULL);
1320 if (h != NULL)
1321 {
1322 bfd_vma off = h->got.offset;
1323 BFD_ASSERT (off != (bfd_vma) -1);
1324
1325 if (! elf_hash_table (info)->dynamic_sections_created
1326 || (info->shared
1327 && (info->symbolic || h->dynindx == -1)
1328 && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
1329 {
1330 /* This is actually a static link, or it is a -Bsymbolic
1331 link and the symbol is defined locally, or the symbol
1332 was forced to be local because of a version file. We
1333 must initialize this entry in the global offset table.
1334 Since the offset must always be a multiple of 8, we
1335 use the least significant bit to record whether we
1336 have initialized it already.
1337
1338 When doing a dynamic link, we create a .rela.got
1339 relocation entry to initialize the value. This is
1340 done in the finish_dynamic_symbol routine. */
1341 if ((off & 1) != 0)
1342 off &= ~1;
1343 else
1344 {
1345 bfd_put_64 (output_bfd, relocation,
1346 sgot->contents + off);
1347 h->got.offset |= 1;
1348 }
1349 }
1350 relocation = sgot->output_offset + off;
1351 }
1352 else
1353 {
1354 bfd_vma off;
1355
1356 BFD_ASSERT (local_got_offsets != NULL
1357 && local_got_offsets[r_symndx] != (bfd_vma) -1);
1358
1359 off = local_got_offsets[r_symndx];
1360
1361 /* The offset must always be a multiple of 8. We use
1362 the least significant bit to record whether we have
1363 already generated the necessary reloc. */
1364 if ((off & 1) != 0)
1365 off &= ~1;
1366 else
1367 {
1368 bfd_put_64 (output_bfd, relocation, sgot->contents + off);
1369
1370 if (info->shared)
1371 {
1372 asection *srelgot;
1373 Elf_Internal_Rela outrel;
1374
1375 /* We need to generate a R_X86_64_RELATIVE reloc
1376 for the dynamic linker. */
1377 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
1378 BFD_ASSERT (srelgot != NULL);
1379
1380 outrel.r_offset = (sgot->output_section->vma
1381 + sgot->output_offset
1382 + off);
1383 outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
1384 outrel.r_addend = relocation;
1385 bfd_elf64_swap_reloca_out (output_bfd, &outrel,
1386 (((Elf64_External_Rela *)
1387 srelgot->contents)
1388 + srelgot->reloc_count));
1389 ++srelgot->reloc_count;
1390 }
1391
1392 local_got_offsets[r_symndx] |= 1;
1393 }
1394
1395 relocation = sgot->output_section->vma + off;
1396 }
1397 break;
1398
1399 case R_X86_64_PLT32:
1400 /* Relocation is to the entry for this symbol in the
1401 procedure linkage table. */
1402
1403 /* Resolve a PLT32 reloc against a local symbol directly,
1404 without using the procedure linkage table. */
1405 if (h == NULL)
1406 break;
1407
1408 if (h->plt.offset == (bfd_vma) -1 || splt == NULL)
1409 {
1410 /* We didn't make a PLT entry for this symbol. This
1411 happens when statically linking PIC code, or when
1412 using -Bsymbolic. */
1413 break;
1414 }
1415
1416 relocation = (splt->output_section->vma
1417 + splt->output_offset
1418 + h->plt.offset);
1419 break;
1420
1421 case R_X86_64_8:
1422 case R_X86_64_16:
1423 case R_X86_64_32:
1424 case R_X86_64_PC8:
1425 case R_X86_64_PC16:
1426 case R_X86_64_PC32:
1427 /* FIXME: The abi says the linker should make sure the value is
1428 the same when it's zeroextended to 64 bit. */
1429 if (info->shared
1430 && (input_section->flags & SEC_ALLOC) != 0
1431 && ((r_type != R_X86_64_PC8 && r_type != R_X86_64_PC16
1432 && r_type != R_X86_64_PC32)
1433 || (h != NULL
1434 && h->dynindx != -1
1435 && (! info->symbolic
1436 || (h->elf_link_hash_flags
1437 & ELF_LINK_HASH_DEF_REGULAR) == 0))))
1438 {
1439 Elf_Internal_Rela outrel;
1440 boolean skip, relocate;
1441
1442 /* When generating a shared object, these relocations
1443 are copied into the output file to be resolved at run
1444 time. */
1445
1446 if (sreloc == NULL)
1447 {
1448 const char *name;
1449
1450 name = (bfd_elf_string_from_elf_section
1451 (input_bfd,
1452 elf_elfheader (input_bfd)->e_shstrndx,
1453 elf_section_data (input_section)->rel_hdr.sh_name));
1454 if (name == NULL)
1455 return false;
1456
1457 BFD_ASSERT (strncmp (name, ".rela", 5) == 0
1458 && strcmp (bfd_get_section_name (input_bfd,
1459 input_section),
1460 name + 5) == 0);
1461
1462 sreloc = bfd_get_section_by_name (dynobj, name);
1463 BFD_ASSERT (sreloc != NULL);
1464 }
1465
1466 skip = false;
1467
1468 if (elf_section_data (input_section)->stab_info == NULL)
1469 outrel.r_offset = rela->r_offset;
1470 else
1471 {
1472 bfd_vma off;
1473
1474 off = (_bfd_stab_section_offset
1475 (output_bfd, &elf_hash_table (info)->stab_info,
1476 input_section,
1477 &elf_section_data (input_section)->stab_info,
1478 rela->r_offset));
1479 if (off == (bfd_vma) -1)
1480 skip = true;
1481 outrel.r_offset = off;
1482 }
1483
1484 outrel.r_offset += (input_section->output_section->vma
1485 + input_section->output_offset);
1486
1487 if (skip)
1488 {
1489 memset (&outrel, 0, sizeof outrel);
1490 relocate = false;
1491 }
1492 else if ((r_type == R_X86_64_PC8) || (r_type == R_X86_64_PC16)
1493 || (r_type == R_X86_64_PC32))
1494 {
1495 BFD_ASSERT (h != NULL && h->dynindx != -1);
1496 relocate = false;
1497 outrel.r_info = ELF64_R_INFO (h->dynindx, r_type);
1498 outrel.r_addend = relocation + rela->r_addend;
1499 }
1500 else
1501 {
1502 /* h->dynindx may be -1 if this symbol was marked to
1503 become local. */
1504 if (h == NULL
1505 || ((info->symbolic || h->dynindx == -1)
1506 && (h->elf_link_hash_flags
1507 & ELF_LINK_HASH_DEF_REGULAR) != 0))
1508 {
1509 relocate = true;
1510 outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
1511 outrel.r_addend = relocation + rela->r_addend;
1512 }
1513 else
1514 {
1515 BFD_ASSERT (h->dynindx != -1);
1516 relocate = false;
1517 outrel.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_32);
1518 outrel.r_addend = relocation + rela->r_addend;
1519 }
1520 }
1521
1522 bfd_elf64_swap_reloca_out (output_bfd, &outrel,
1523 (((Elf64_External_Rela *)
1524 sreloc->contents)
1525 + sreloc->reloc_count));
1526 ++sreloc->reloc_count;
1527
1528 /* If this reloc is against an external symbol, we do
1529 not want to fiddle with the addend. Otherwise, we
1530 need to include the symbol value so that it becomes
1531 an addend for the dynamic reloc. */
1532 if (! relocate)
1533 continue;
1534 }
1535
1536 break;
1537
1538 default:
1539 break;
1540 }
1541
1542 r = _bfd_final_link_relocate (howto, input_bfd, input_section,
1543 contents, rela->r_offset,
1544 relocation, rela->r_addend);
1545
1546 if (r != bfd_reloc_ok)
1547 {
1548 switch (r)
1549 {
1550 default:
1551 case bfd_reloc_outofrange:
1552 abort ();
1553 case bfd_reloc_overflow:
1554 {
1555 const char *name;
1556
1557 if (h != NULL)
1558 name = h->root.root.string;
1559 else
1560 {
1561 name = bfd_elf_string_from_elf_section (input_bfd,
1562 symtab_hdr->sh_link,
1563 sym->st_name);
1564 if (name == NULL)
1565 return false;
1566 if (*name == '\0')
1567 name = bfd_section_name (input_bfd, sec);
1568 }
1569 if (! ((*info->callbacks->reloc_overflow)
1570 (info, name, howto->name, (bfd_vma) 0,
1571 input_bfd, input_section, rela->r_offset)))
1572 return false;
1573 }
1574 break;
1575 }
1576 }
1577 }
1578
1579 return true;
1580 }
1581
1582 /* Finish up dynamic symbol handling. We set the contents of various
1583 dynamic sections here. */
1584
1585 static boolean
1586 elf64_x86_64_finish_dynamic_symbol (output_bfd, info, h, sym)
1587 bfd *output_bfd;
1588 struct bfd_link_info *info;
1589 struct elf_link_hash_entry *h;
1590 Elf_Internal_Sym *sym;
1591 {
1592 bfd *dynobj;
1593
1594 dynobj = elf_hash_table (info)->dynobj;
1595
1596 if (h->plt.offset != (bfd_vma) -1)
1597 {
1598 asection *splt;
1599 asection *sgot;
1600 asection *srela;
1601 bfd_vma plt_index;
1602 bfd_vma got_offset;
1603 Elf_Internal_Rela rela;
1604
1605 /* This symbol has an entry in the procedure linkage table. Set
1606 it up. */
1607
1608 BFD_ASSERT (h->dynindx != -1);
1609
1610 splt = bfd_get_section_by_name (dynobj, ".plt");
1611 sgot = bfd_get_section_by_name (dynobj, ".got.plt");
1612 srela = bfd_get_section_by_name (dynobj, ".rela.plt");
1613 BFD_ASSERT (splt != NULL && sgot != NULL && srela != NULL);
1614
1615 /* Get the index in the procedure linkage table which
1616 corresponds to this symbol. This is the index of this symbol
1617 in all the symbols for which we are making plt entries. The
1618 first entry in the procedure linkage table is reserved. */
1619 plt_index = h->plt.offset / PLT_ENTRY_SIZE - 1;
1620
1621 /* Get the offset into the .got table of the entry that
1622 corresponds to this function. Each .got entry is GOT_ENTRY_SIZE
1623 bytes. The first three are reserved. */
1624 got_offset = (plt_index + 3) * GOT_ENTRY_SIZE;
1625
1626 /* Fill in the entry in the procedure linkage table. */
1627 memcpy (splt->contents + h->plt.offset, elf64_x86_64_plt_entry,
1628 PLT_ENTRY_SIZE);
1629
1630 /* Insert the relocation positions of the plt section. The magic
1631 numbers at the end of the statements are the positions of the
1632 relocations in the plt section. */
1633 bfd_put_64 (output_bfd, got_offset, splt->contents + h->plt.offset + 2);
1634 bfd_put_64 (output_bfd, plt_index * sizeof (Elf64_External_Rela),
1635 splt->contents + h->plt.offset + 7);
1636 bfd_put_64 (output_bfd, - (h->plt.offset + PLT_ENTRY_SIZE),
1637 splt->contents + h->plt.offset + 12);
1638
1639 /* Fill in the entry in the global offset table. */
1640 bfd_put_64 (output_bfd, (splt->output_section->vma + splt->output_offset
1641 + h->plt.offset + 6),
1642 sgot->contents + got_offset);
1643
1644 /* Fill in the entry in the .rela.plt section. */
1645 rela.r_offset = (sgot->output_section->vma
1646 + sgot->output_offset
1647 + got_offset);
1648 rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_JUMP_SLOT);
1649 rela.r_addend = 0;
1650 bfd_elf64_swap_reloca_out (output_bfd, &rela,
1651 ((Elf64_External_Rela *) srela->contents
1652 + plt_index));
1653
1654 if ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0)
1655 {
1656 /* Mark the symbol as undefined, rather than as defined in
1657 the .plt section. Leave the value alone. */
1658 sym->st_shndx = SHN_UNDEF;
1659 /* If the symbol is weak, we do need to clear the value.
1660 Otherwise, the PLT entry would provide a definition for
1661 the symbol even if the symbol wasn't defined anywhere,
1662 and so the symbol would never be NULL. */
1663 if ((h->elf_link_hash_flags & ELF_LINK_HASH_REF_REGULAR_NONWEAK)
1664 == 0)
1665 sym->st_value = 0;
1666 }
1667 }
1668
1669 if ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_COPY) != 0)
1670 {
1671 asection *s;
1672 Elf_Internal_Rela rela;
1673
1674 /* This symbol needs a copy reloc. Set it up. */
1675
1676 BFD_ASSERT (h->dynindx != -1
1677 && (h->root.type == bfd_link_hash_defined
1678 || h->root.type == bfd_link_hash_defweak));
1679
1680 s = bfd_get_section_by_name (h->root.u.def.section->owner,
1681 ".rela.bss");
1682 BFD_ASSERT (s != NULL);
1683
1684 rela.r_offset = (h->root.u.def.value
1685 + h->root.u.def.section->output_section->vma
1686 + h->root.u.def.section->output_offset);
1687 rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_COPY);
1688 rela.r_addend = 0;
1689 bfd_elf64_swap_reloca_out (output_bfd, &rela,
1690 ((Elf64_External_Rela *) s->contents
1691 + s->reloc_count));
1692 ++s->reloc_count;
1693 }
1694
1695 /* Mark _DYNAMIC and _GLOBAL_OFFSET_TABLE_ as absolute. */
1696 if (strcmp (h->root.root.string, "_DYNAMIC") == 0
1697 || strcmp (h->root.root.string, "_GLOBAL_OFFSET_TABLE_") == 0)
1698 sym->st_shndx = SHN_ABS;
1699
1700 return true;
1701 }
1702
1703 /* Finish up the dynamic sections. */
1704
1705 static boolean
1706 elf64_x86_64_finish_dynamic_sections (output_bfd, info)
1707 bfd *output_bfd;
1708 struct bfd_link_info *info;
1709 {
1710 bfd *dynobj;
1711 asection *sdyn;
1712 asection *sgot;
1713
1714 dynobj = elf_hash_table (info)->dynobj;
1715
1716 sdyn = bfd_get_section_by_name (dynobj, ".dynamic");
1717
1718 if (elf_hash_table (info)->dynamic_sections_created)
1719 {
1720 asection *splt;
1721 Elf64_External_Dyn *dyncon, *dynconend;
1722
1723 BFD_ASSERT (sdyn != NULL);
1724
1725 dyncon = (Elf64_External_Dyn *) sdyn->contents;
1726 dynconend = (Elf64_External_Dyn *) (sdyn->contents + sdyn->_raw_size);
1727 for (; dyncon < dynconend; dyncon++)
1728 {
1729 Elf_Internal_Dyn dyn;
1730 const char *name;
1731 asection *s;
1732
1733 bfd_elf64_swap_dyn_in (dynobj, dyncon, &dyn);
1734
1735 switch (dyn.d_tag)
1736 {
1737 default:
1738 break;
1739
1740 case DT_PLTGOT:
1741 name = ".got";
1742 goto get_vma;
1743
1744 case DT_JMPREL:
1745 name = ".rela.plt";
1746
1747 get_vma:
1748 s = bfd_get_section_by_name (output_bfd, name);
1749 BFD_ASSERT (s != NULL);
1750 dyn.d_un.d_ptr = s->vma;
1751 break;
1752
1753 case DT_RELASZ:
1754 /* FIXME: This comment and code is from elf64-alpha.c: */
1755 /* My interpretation of the TIS v1.1 ELF document indicates
1756 that RELASZ should not include JMPREL. This is not what
1757 the rest of the BFD does. It is, however, what the
1758 glibc ld.so wants. Do this fixup here until we found
1759 out who is right. */
1760 s = bfd_get_section_by_name (output_bfd, ".rela.plt");
1761 if (s)
1762 {
1763 /* Subtract JMPREL size from RELASZ. */
1764 dyn.d_un.d_val -=
1765 (s->_cooked_size ? s->_cooked_size : s->_raw_size);
1766 }
1767 break;
1768
1769 case DT_PLTRELSZ:
1770 s = bfd_get_section_by_name (output_bfd, ".rela.plt");
1771 BFD_ASSERT (s != NULL);
1772 dyn.d_un.d_val =
1773 (s->_cooked_size != 0 ? s->_cooked_size : s->_raw_size);
1774 break;
1775 }
1776
1777 bfd_elf64_swap_dyn_out (output_bfd, &dyn, dyncon);
1778 }
1779
1780 /* Initialize the contents of the .plt section. */
1781 splt = bfd_get_section_by_name (dynobj, ".plt");
1782 BFD_ASSERT (splt != NULL);
1783 if (splt->_raw_size > 0)
1784 {
1785 memcpy (splt->contents, elf64_x86_64_plt0_entry, PLT_ENTRY_SIZE);
1786 }
1787
1788 elf_section_data (splt->output_section)->this_hdr.sh_entsize =
1789 PLT_ENTRY_SIZE;
1790 }
1791
1792 /* Set the first entry in the global offset table to the address of
1793 the dynamic section. */
1794 sgot = bfd_get_section_by_name (dynobj, ".got.plt");
1795 BFD_ASSERT (sgot != NULL);
1796 if (sgot->_raw_size > 0)
1797 {
1798 if (sdyn == NULL)
1799 bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents);
1800 else
1801 bfd_put_64 (output_bfd,
1802 sdyn->output_section->vma + sdyn->output_offset,
1803 sgot->contents);
1804 /* Write GOT[1] and GOT[2], needed for the linker. */
1805 bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + GOT_ENTRY_SIZE);
1806 bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + GOT_ENTRY_SIZE*2);
1807 }
1808
1809 elf_section_data (sgot->output_section)->this_hdr.sh_entsize =
1810 GOT_ENTRY_SIZE;
1811
1812 return true;
1813 }
1814
1815 /*
1816 * Why was the hash table entry size definition changed from
1817 * ARCH_SIZE/8 to 4? This breaks the 64 bit dynamic linker and
1818 * this is the only reason for the elf64_x86_64_size_info structure.
1819 */
1820
1821 const struct elf_size_info elf64_86_64_size_info =
1822 {
1823 sizeof (Elf64_External_Ehdr),
1824 sizeof (Elf64_External_Phdr),
1825 sizeof (Elf64_External_Shdr),
1826 sizeof (Elf64_External_Rel),
1827 sizeof (Elf64_External_Rela),
1828 sizeof (Elf64_External_Sym),
1829 sizeof (Elf64_External_Dyn),
1830 sizeof (Elf_External_Note),
1831 8, /* hash-table entry size */
1832 1, /* internal relocations per external relocations */
1833 64, /* arch_size */
1834 8, /* file_align */
1835 ELFCLASS64, EV_CURRENT,
1836 bfd_elf64_write_out_phdrs,
1837 bfd_elf64_write_shdrs_and_ehdr,
1838 bfd_elf64_write_relocs,
1839 bfd_elf64_swap_symbol_out,
1840 bfd_elf64_slurp_reloc_table,
1841 bfd_elf64_slurp_symbol_table,
1842 bfd_elf64_swap_dyn_in,
1843 bfd_elf64_swap_dyn_out,
1844 NULL,
1845 NULL,
1846 NULL,
1847 NULL
1848 };
1849
1850 #define TARGET_LITTLE_SYM bfd_elf64_x86_64_vec
1851 #define TARGET_LITTLE_NAME "elf64-x86-64"
1852 #define ELF_ARCH bfd_arch_i386
1853 #define ELF_MACHINE_CODE EM_X86_64
1854 #define ELF_MAXPAGESIZE 0x100000
1855
1856 #define elf_backend_size_info elf64_86_64_size_info
1857
1858 #define elf_backend_can_gc_sections 1
1859 #define elf_backend_want_got_plt 1
1860 #define elf_backend_plt_readonly 1
1861 #define elf_backend_want_plt_sym 0
1862 #define elf_backend_got_header_size (GOT_ENTRY_SIZE*3)
1863 #define elf_backend_plt_header_size PLT_ENTRY_SIZE
1864
1865 #define elf_info_to_howto elf64_x86_64_info_to_howto
1866
1867 #define bfd_elf64_bfd_final_link _bfd_elf64_gc_common_final_link
1868 #define bfd_elf64_bfd_link_hash_table_create \
1869 elf64_x86_64_link_hash_table_create
1870 #define bfd_elf64_bfd_reloc_type_lookup elf64_x86_64_reloc_type_lookup
1871
1872 #define elf_backend_adjust_dynamic_symbol elf64_x86_64_adjust_dynamic_symbol
1873 #define elf_backend_check_relocs elf64_x86_64_check_relocs
1874 #define elf_backend_create_dynamic_sections _bfd_elf_create_dynamic_sections
1875 #define elf_backend_finish_dynamic_sections \
1876 elf64_x86_64_finish_dynamic_sections
1877 #define elf_backend_finish_dynamic_symbol elf64_x86_64_finish_dynamic_symbol
1878 #define elf_backend_gc_mark_hook elf64_x86_64_gc_mark_hook
1879 #define elf_backend_gc_sweep_hook elf64_x86_64_gc_sweep_hook
1880 #define elf_backend_relocate_section elf64_x86_64_relocate_section
1881 #define elf_backend_size_dynamic_sections elf64_x86_64_size_dynamic_sections
1882 #define elf_backend_object_p elf64_x86_64_elf_object_p
1883
1884 #include "elf64-target.h"
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