2001-03-22 Philip Blundell <philb@gnu.org>
[binutils.git] / bfd / elf64-x86-64.c
blobd797165c3dbdc9882ec00e721be99c848c7bb883
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>.
5 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
21 #include "bfd.h"
22 #include "sysdep.h"
23 #include "libbfd.h"
24 #include "elf-bfd.h"
26 #include "elf/x86-64.h"
28 /* We use only the RELA entries. */
29 #define USE_RELA
31 /* In case we're on a 32-bit machine, construct a 64-bit "-1" value. */
32 #define MINUS_ONE (~ (bfd_vma) 0)
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[] =
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)
73 /* Map BFD relocs to the x86_64 elf relocs. */
74 struct elf_reloc_map
76 bfd_reloc_code_real_type bfd_reloc_val;
77 unsigned char elf_reloc_val;
80 static CONST struct elf_reloc_map x86_64_reloc_map[] =
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, },
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 *));
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 *));
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 *));
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;
129 unsigned int i;
130 for (i = 0; i < sizeof (x86_64_reloc_map) / sizeof (struct elf_reloc_map);
131 i++)
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];
137 return 0;
140 /* Given an x86_64 ELF reloc type, fill in an arelent structure. */
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;
148 unsigned r_type;
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);
156 /* Functions for the x86-64 ELF linker. */
158 /* The name of the dynamic interpreter. This is put in the .interp
159 section. */
161 #define ELF_DYNAMIC_INTERPRETER "/lib/ld64.so.1"
163 /* The size in bytes of an entry in the global offset table. */
165 #define GOT_ENTRY_SIZE 8
167 /* The size in bytes of an entry in the procedure linkage table. */
169 #define PLT_ENTRY_SIZE 16
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. */
174 static const bfd_byte elf64_x86_64_plt0_entry[PLT_ENTRY_SIZE] =
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. */
181 /* Subsequent entries in a procedure linkage table look like this. */
183 static const bfd_byte elf64_x86_64_plt_entry[PLT_ENTRY_SIZE] =
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. */
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. */
199 /* This structure keeps track of the number of PC relative relocs we
200 have copied for a given symbol. */
202 struct elf64_x86_64_pcrel_relocs_copied
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;
212 /* x86-64 ELF linker hash entry. */
214 struct elf64_x86_64_link_hash_entry
216 struct elf_link_hash_entry root;
218 /* Number of PC relative relocs copied for this symbol. */
219 struct elf64_x86_64_pcrel_relocs_copied *pcrel_relocs_copied;
222 /* x86-64 ELF linker hash table. */
224 struct elf64_x86_64_link_hash_table
226 struct elf_link_hash_table root;
229 /* Declare this now that the above structures are defined. */
231 static boolean elf64_x86_64_discard_copies
232 PARAMS ((struct elf64_x86_64_link_hash_entry *, PTR));
234 /* Traverse an x86-64 ELF linker hash table. */
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)))
242 /* Get the x86-64 ELF linker hash table from a link_info structure. */
244 #define elf64_x86_64_hash_table(p) \
245 ((struct elf64_x86_64_link_hash_table *) ((p)->hash))
247 /* Create an entry in an x86-64 ELF linker hash table. */
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;
255 struct elf64_x86_64_link_hash_entry *ret =
256 (struct elf64_x86_64_link_hash_entry *) entry;
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;
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)
273 ret->pcrel_relocs_copied = NULL;
276 return (struct bfd_hash_entry *) ret;
279 /* Create an X86-64 ELF linker hash table. */
281 static struct bfd_link_hash_table *
282 elf64_x86_64_link_hash_table_create (abfd)
283 bfd *abfd;
285 struct elf64_x86_64_link_hash_table *ret;
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;
292 if (! _bfd_elf_link_hash_table_init (&ret->root, abfd,
293 elf64_x86_64_link_hash_newfunc))
295 bfd_release (abfd, ret);
296 return NULL;
299 return &ret->root.root;
302 boolean
303 elf64_x86_64_elf_object_p (abfd)
304 bfd *abfd;
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;
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. */
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;
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;
332 if (info->relocateable)
333 return true;
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);
340 sgot = srelgot = sreloc = NULL;
341 rel_end = relocs + sec->reloc_count;
342 for (rel = relocs; rel < rel_end; rel++)
344 unsigned long r_symndx;
345 struct elf_link_hash_entry *h;
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];
353 /* Some relocs require a global offset table. */
354 if (dynobj == NULL)
356 switch (ELF64_R_TYPE (rel->r_info))
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;
367 switch (ELF64_R_TYPE (rel->r_info))
369 case R_X86_64_GOTPCREL:
370 case R_X86_64_GOT32:
371 /* This symbol requires a global offset table entry. */
373 if (sgot == NULL)
375 sgot = bfd_get_section_by_name (dynobj, ".got");
376 BFD_ASSERT (sgot != NULL);
379 if (srelgot == NULL && (h != NULL || info->shared))
381 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
382 if (srelgot == NULL)
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;
398 if (h != NULL)
400 if (h->got.refcount == -1)
402 h->got.refcount = 1;
404 /* Make sure this symbol is output as a dynamic symbol. */
405 if (h->dynindx == -1)
407 if (! bfd_elf64_link_record_dynamic_symbol (info, h))
408 return false;
411 sgot->_raw_size += GOT_ENTRY_SIZE;
412 srelgot->_raw_size += sizeof (Elf64_External_Rela);
414 else
415 h->got.refcount += 1;
417 else
419 /* This is a global offset table entry for a local symbol. */
420 if (local_got_refcounts == NULL)
422 size_t size;
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);
432 if (local_got_refcounts[r_symndx] == -1)
434 local_got_refcounts[r_symndx] = 1;
436 sgot->_raw_size += GOT_ENTRY_SIZE;
437 if (info->shared)
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);
445 else
446 local_got_refcounts[r_symndx] += 1;
448 break;
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. */
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;
463 if (h->plt.refcount == -1)
465 h->plt.refcount = 1;
466 h->elf_link_hash_flags |= ELF_LINK_HASH_NEEDS_PLT;
468 else
469 h->plt.refcount += 1;
470 break;
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;
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))))
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)
505 const char *name;
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;
514 BFD_ASSERT (strncmp (name, ".rela", 5) == 0
515 && strcmp (bfd_get_section_name (abfd, sec),
516 name + 5) == 0);
518 sreloc = bfd_get_section_by_name (dynobj, name);
519 if (sreloc == NULL)
521 flagword flags;
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;
535 sreloc->_raw_size += sizeof (Elf64_External_Rela);
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)
546 struct elf64_x86_64_link_hash_entry *eh;
547 struct elf64_x86_64_pcrel_relocs_copied *p;
549 eh = (struct elf64_x86_64_link_hash_entry *) h;
551 for (p = eh->pcrel_relocs_copied; p != NULL; p = p->next)
552 if (p->section == sreloc)
553 break;
555 if (p == NULL)
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;
567 ++p->count;
570 break;
574 return true;
577 /* Return the section that should be marked against GC for a given
578 relocation. */
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;
588 if (h != NULL)
590 switch (h->root.type)
592 case bfd_link_hash_defined:
593 case bfd_link_hash_defweak:
594 return h->root.u.def.section;
596 case bfd_link_hash_common:
597 return h->root.u.c.p->section;
599 default:
600 break;
603 else
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))
610 return bfd_section_from_elf_index (abfd, sym->st_shndx);
614 return NULL;
617 /* Update the got entry reference counts for the section being removed. */
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;
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;
636 symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
637 sym_hashes = elf_sym_hashes (abfd);
638 local_got_refcounts = elf_local_got_refcounts (abfd);
640 dynobj = elf_hash_table (info)->dynobj;
641 if (dynobj == NULL)
642 return true;
644 sgot = bfd_get_section_by_name (dynobj, ".got");
645 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
647 relend = relocs + sec->reloc_count;
648 for (rel = relocs; rel < relend; rel++)
649 switch (ELF64_R_TYPE (rel->r_info))
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)
656 h = sym_hashes[r_symndx - symtab_hdr->sh_info];
657 if (h->got.refcount > 0)
659 h->got.refcount -= 1;
660 if (h->got.refcount == 0)
662 sgot->_raw_size -= GOT_ENTRY_SIZE;
663 srelgot->_raw_size -= sizeof (Elf64_External_Rela);
667 else if (local_got_refcounts != NULL)
669 if (local_got_refcounts[r_symndx] > 0)
671 local_got_refcounts[r_symndx] -= 1;
672 if (local_got_refcounts[r_symndx] == 0)
674 sgot->_raw_size -= GOT_ENTRY_SIZE;
675 if (info->shared)
676 srelgot->_raw_size -= sizeof (Elf64_External_Rela);
680 break;
682 case R_X86_64_PLT32:
683 r_symndx = ELF64_R_SYM (rel->r_info);
684 if (r_symndx >= symtab_hdr->sh_info)
686 h = sym_hashes[r_symndx - symtab_hdr->sh_info];
687 if (h->plt.refcount > 0)
688 h->plt.refcount -= 1;
690 break;
692 default:
693 break;
696 return true;
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. */
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;
710 bfd *dynobj;
711 asection *s;
712 unsigned int power_of_two;
714 dynobj = elf_hash_table (info)->dynobj;
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)));
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)
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))
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;
748 /* Make sure this symbol is output as a dynamic symbol. */
749 if (h->dynindx == -1)
751 if (! bfd_elf64_link_record_dynamic_symbol (info, h))
752 return false;
755 s = bfd_get_section_by_name (dynobj, ".plt");
756 BFD_ASSERT (s != NULL);
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;
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)
771 h->root.u.def.section = s;
772 h->root.u.def.value = s->_raw_size;
775 h->plt.offset = s->_raw_size;
777 /* Make room for this entry. */
778 s->_raw_size += PLT_ENTRY_SIZE;
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;
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);
791 return true;
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)
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;
806 /* This is a reference to a symbol defined by a dynamic object which
807 is not a function. */
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;
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;
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. */
831 s = bfd_get_section_by_name (dynobj, ".dynbss");
832 BFD_ASSERT (s != NULL);
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)
840 asection *srel;
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;
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;
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))
861 if (! bfd_set_section_alignment (dynobj, s, power_of_two))
862 return false;
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;
869 /* Increment the section size to make room for the symbol. */
870 s->_raw_size += h->size;
872 return true;
875 /* Set the sizes of the dynamic sections. */
877 static boolean
878 elf64_x86_64_size_dynamic_sections (output_bfd, info)
879 bfd *output_bfd;
880 struct bfd_link_info *info;
882 bfd *dynobj;
883 asection *s;
884 boolean plt;
885 boolean relocs;
886 boolean reltext;
888 dynobj = elf_hash_table (info)->dynobj;
889 BFD_ASSERT (dynobj != NULL);
891 if (elf_hash_table (info)->dynamic_sections_created)
893 /* Set the contents of the .interp section to the interpreter. */
894 if (! info->shared)
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;
902 else
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;
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);
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)
929 const char *name;
930 boolean strip;
932 if ((s->flags & SEC_LINKER_CREATED) == 0)
933 continue;
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);
939 strip = false;
940 if (strcmp (name, ".plt") == 0)
942 if (s->_raw_size == 0)
944 /* Strip this section if we don't need it; see the
945 comment below. */
946 strip = true;
948 else
950 /* Remember whether there is a PLT. */
951 plt = true;
954 else if (strncmp (name, ".rela", 5) == 0)
956 if (s->_raw_size == 0)
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;
969 else
971 asection *target;
973 /* Remember whether there are any reloc sections other
974 than .rela.plt. */
975 if (strcmp (name, ".rela.plt") != 0)
977 const char *outname;
979 relocs = true;
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;
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;
1000 else if (strncmp (name, ".got", 4) != 0)
1002 /* It's not one of our sections, so don't allocate space. */
1003 continue;
1006 if (strip)
1008 _bfd_strip_section_from_output (info, s);
1009 continue;
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;
1022 if (elf_hash_table (info)->dynamic_sections_created)
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)
1031 if (! bfd_elf64_add_dynamic_entry (info, DT_DEBUG, 0))
1032 return false;
1035 if (plt)
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;
1044 if (relocs)
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;
1053 if (reltext)
1055 if (! bfd_elf64_add_dynamic_entry (info, DT_TEXTREL, 0))
1056 return false;
1057 info->flags |= DF_TEXTREL;
1061 return true;
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. */
1073 static boolean
1074 elf64_x86_64_discard_copies (h, inf)
1075 struct elf64_x86_64_link_hash_entry *h;
1076 PTR inf;
1078 struct elf64_x86_64_pcrel_relocs_copied *s;
1079 struct bfd_link_info *info = (struct bfd_link_info *) inf;
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))
1088 for (s = h->pcrel_relocs_copied; s != NULL; s = s->next)
1089 s->section->_raw_size -= s->count * sizeof (Elf64_External_Rela);
1092 return true;
1095 /* Relocate an x86_64 ELF section. */
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;
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;
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);
1124 sreloc = splt = sgot = NULL;
1125 if (dynobj != NULL)
1127 splt = bfd_get_section_by_name (dynobj, ".plt");
1128 sgot = bfd_get_section_by_name (dynobj, ".got");
1131 rela = relocs;
1132 relend = relocs + input_section->reloc_count;
1133 for (; rela < relend; rela++)
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;
1145 r_type = ELF64_R_TYPE (rela->r_info);
1147 if ((indx = (unsigned) r_type) >= R_X86_64_max)
1149 bfd_set_error (bfd_error_bad_value);
1150 return false;
1152 howto = x86_64_elf_howto_table + indx;
1154 r_symndx = ELF64_R_SYM (rela->r_info);
1156 if (info->relocateable)
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)
1164 sym = local_syms + r_symndx;
1165 if (ELF_ST_TYPE (sym->st_info) == STT_SECTION)
1167 sec = local_sections[r_symndx];
1168 rela->r_addend += sec->output_offset + sym->st_value;
1172 continue;
1175 /* This is a final link. */
1176 h = NULL;
1177 sym = NULL;
1178 sec = NULL;
1179 if (r_symndx < symtab_hdr->sh_info)
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);
1187 else
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)
1196 sec = h->root.u.def.section;
1197 if (r_type == R_X86_64_GOTPCREL
1198 || (r_type = R_X86_64_PLT32
1199 && splt != NULL
1200 && h->plt.offset != (bfd_vma) -1)
1201 || (r_type = R_X86_64_GOT32
1202 && elf_hash_table (info)->dynamic_sections_created
1203 && (!info->shared
1204 || (! info->symbolic && h->dynindx != -1)
1205 || (h->elf_link_hash_flags
1206 & ELF_LINK_HASH_DEF_REGULAR) == 0))
1207 || (info->shared
1208 && ((! info->symbolic && h->dynindx != -1)
1209 || (h->elf_link_hash_flags
1210 & ELF_LINK_HASH_DEF_REGULAR) == 0)
1211 && ( r_type == R_X86_64_8 ||
1212 r_type == R_X86_64_16 ||
1213 r_type == R_X86_64_32 ||
1214 r_type == R_X86_64_64 ||
1215 r_type == R_X86_64_PC16 ||
1216 r_type == R_X86_64_PC32)
1217 && ((input_section->flags & SEC_ALLOC) != 0
1218 /* DWARF will emit R_X86_64_32 relocations in its
1219 sections against symbols defined externally
1220 in shared libraries. We can't do anything
1221 with them here. */
1222 || ((input_section->flags & SEC_DEBUGGING) != 0
1223 && (h->elf_link_hash_flags
1224 & ELF_LINK_HASH_DEF_DYNAMIC) != 0))))
1226 /* In these cases, we don't need the relocation
1227 value. We check specially because in some
1228 obscure cases sec->output_section will be NULL. */
1229 relocation = 0;
1231 else if (sec->output_section == NULL)
1233 (*_bfd_error_handler)
1234 (_("%s: warning: unresolvable relocation against symbol `%s' from %s section"),
1235 bfd_get_filename (input_bfd), h->root.root.string,
1236 bfd_get_section_name (input_bfd, input_section));
1237 relocation = 0;
1239 else
1240 relocation = (h->root.u.def.value
1241 + sec->output_section->vma
1242 + sec->output_offset);
1244 else if (h->root.type == bfd_link_hash_undefweak)
1245 relocation = 0;
1246 else if (info->shared && !info->symbolic && !info->no_undefined
1247 && ELF_ST_VISIBILITY (h->other) == STV_DEFAULT)
1248 relocation = 0;
1249 else
1251 if (! ((*info->callbacks->undefined_symbol)
1252 (info, h->root.root.string, input_bfd,
1253 input_section, rela->r_offset,
1254 (!info->shared || info->no_undefined
1255 || ELF_ST_VISIBILITY (h->other)))))
1256 return false;
1257 relocation = 0;
1261 /* When generating a shared object, the relocations handled here are
1262 copied into the output file to be resolved at run time. */
1263 switch (r_type)
1265 case R_X86_64_GOT32:
1266 /* Relocation is to the entry for this symbol in the global
1267 offset table. */
1268 BFD_ASSERT (sgot != NULL);
1270 if (h != NULL)
1272 bfd_vma off = h->got.offset;
1273 BFD_ASSERT (off != (bfd_vma) -1);
1275 if (! elf_hash_table (info)->dynamic_sections_created
1276 || (info->shared
1277 && (info->symbolic || h->dynindx == -1)
1278 && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
1280 /* This is actually a static link, or it is a -Bsymbolic
1281 link and the symbol is defined locally, or the symbol
1282 was forced to be local because of a version file. We
1283 must initialize this entry in the global offset table.
1284 Since the offset must always be a multiple of 8, we
1285 use the least significant bit to record whether we
1286 have initialized it already.
1288 When doing a dynamic link, we create a .rela.got
1289 relocation entry to initialize the value. This is
1290 done in the finish_dynamic_symbol routine. */
1291 if ((off & 1) != 0)
1292 off &= ~1;
1293 else
1295 bfd_put_64 (output_bfd, relocation,
1296 sgot->contents + off);
1297 h->got.offset |= 1;
1300 relocation = sgot->output_offset + off;
1302 else
1304 bfd_vma off;
1306 BFD_ASSERT (local_got_offsets != NULL
1307 && local_got_offsets[r_symndx] != (bfd_vma) -1);
1309 off = local_got_offsets[r_symndx];
1311 /* The offset must always be a multiple of 8. We use
1312 the least significant bit to record whether we have
1313 already generated the necessary reloc. */
1314 if ((off & 1) != 0)
1315 off &= ~1;
1316 else
1318 bfd_put_64 (output_bfd, relocation, sgot->contents + off);
1320 if (info->shared)
1322 asection *srelgot;
1323 Elf_Internal_Rela outrel;
1325 /* We need to generate a R_X86_64_RELATIVE reloc
1326 for the dynamic linker. */
1327 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
1328 BFD_ASSERT (srelgot != NULL);
1330 outrel.r_offset = (sgot->output_section->vma
1331 + sgot->output_offset
1332 + off);
1333 outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
1334 outrel.r_addend = relocation;
1335 bfd_elf64_swap_reloca_out (output_bfd, &outrel,
1336 (((Elf64_External_Rela *)
1337 srelgot->contents)
1338 + srelgot->reloc_count));
1339 ++srelgot->reloc_count;
1342 local_got_offsets[r_symndx] |= 1;
1345 relocation = sgot->output_offset + off;
1348 break;
1350 case R_X86_64_GOTPCREL:
1351 /* Use global offset table as symbol value. */
1353 BFD_ASSERT (sgot != NULL);
1354 if (h != NULL)
1356 bfd_vma off = h->got.offset;
1357 BFD_ASSERT (off != (bfd_vma) -1);
1359 if (! elf_hash_table (info)->dynamic_sections_created
1360 || (info->shared
1361 && (info->symbolic || h->dynindx == -1)
1362 && (h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR)))
1364 /* This is actually a static link, or it is a -Bsymbolic
1365 link and the symbol is defined locally, or the symbol
1366 was forced to be local because of a version file. We
1367 must initialize this entry in the global offset table.
1368 Since the offset must always be a multiple of 8, we
1369 use the least significant bit to record whether we
1370 have initialized it already.
1372 When doing a dynamic link, we create a .rela.got
1373 relocation entry to initialize the value. This is
1374 done in the finish_dynamic_symbol routine. */
1375 if ((off & 1) != 0)
1376 off &= ~1;
1377 else
1379 bfd_put_64 (output_bfd, relocation,
1380 sgot->contents + off);
1381 h->got.offset |= 1;
1384 relocation = sgot->output_offset + off;
1386 else
1388 bfd_vma off;
1390 BFD_ASSERT (local_got_offsets != NULL
1391 && local_got_offsets[r_symndx] != (bfd_vma) -1);
1393 off = local_got_offsets[r_symndx];
1395 /* The offset must always be a multiple of 8. We use
1396 the least significant bit to record whether we have
1397 already generated the necessary reloc. */
1398 if ((off & 1) != 0)
1399 off &= ~1;
1400 else
1402 bfd_put_64 (output_bfd, relocation, sgot->contents + off);
1404 if (info->shared)
1406 asection *srelgot;
1407 Elf_Internal_Rela outrel;
1409 /* We need to generate a R_X86_64_RELATIVE reloc
1410 for the dynamic linker. */
1411 srelgot = bfd_get_section_by_name (dynobj, ".rela.got");
1412 BFD_ASSERT (srelgot != NULL);
1414 outrel.r_offset = (sgot->output_section->vma
1415 + sgot->output_offset
1416 + off);
1417 outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
1418 outrel.r_addend = relocation;
1419 bfd_elf64_swap_reloca_out (output_bfd, &outrel,
1420 (((Elf64_External_Rela *)
1421 srelgot->contents)
1422 + srelgot->reloc_count));
1423 ++srelgot->reloc_count;
1426 local_got_offsets[r_symndx] |= 1;
1429 relocation = sgot->output_section->vma + off;
1431 break;
1433 case R_X86_64_PLT32:
1434 /* Relocation is to the entry for this symbol in the
1435 procedure linkage table. */
1437 /* Resolve a PLT32 reloc against a local symbol directly,
1438 without using the procedure linkage table. */
1439 if (h == NULL)
1440 break;
1442 if (h->plt.offset == (bfd_vma) -1 || splt == NULL)
1444 /* We didn't make a PLT entry for this symbol. This
1445 happens when statically linking PIC code, or when
1446 using -Bsymbolic. */
1447 break;
1450 relocation = (splt->output_section->vma
1451 + splt->output_offset
1452 + h->plt.offset);
1453 break;
1455 case R_X86_64_8:
1456 case R_X86_64_16:
1457 case R_X86_64_32:
1458 case R_X86_64_PC8:
1459 case R_X86_64_PC16:
1460 case R_X86_64_PC32:
1461 /* FIXME: The abi says the linker should make sure the value is
1462 the same when it's zeroextended to 64 bit. */
1463 if (info->shared
1464 && (input_section->flags & SEC_ALLOC) != 0
1465 && ((r_type != R_X86_64_PC8 && r_type != R_X86_64_PC16
1466 && r_type != R_X86_64_PC32)
1467 || (h != NULL
1468 && h->dynindx != -1
1469 && (! info->symbolic
1470 || (h->elf_link_hash_flags
1471 & ELF_LINK_HASH_DEF_REGULAR) == 0))))
1473 Elf_Internal_Rela outrel;
1474 boolean skip, relocate;
1476 /* When generating a shared object, these relocations
1477 are copied into the output file to be resolved at run
1478 time. */
1480 if (sreloc == NULL)
1482 const char *name;
1484 name = (bfd_elf_string_from_elf_section
1485 (input_bfd,
1486 elf_elfheader (input_bfd)->e_shstrndx,
1487 elf_section_data (input_section)->rel_hdr.sh_name));
1488 if (name == NULL)
1489 return false;
1491 BFD_ASSERT (strncmp (name, ".rela", 5) == 0
1492 && strcmp (bfd_get_section_name (input_bfd,
1493 input_section),
1494 name + 5) == 0);
1496 sreloc = bfd_get_section_by_name (dynobj, name);
1497 BFD_ASSERT (sreloc != NULL);
1500 skip = false;
1502 if (elf_section_data (input_section)->stab_info == NULL)
1503 outrel.r_offset = rela->r_offset;
1504 else
1506 bfd_vma off;
1508 off = (_bfd_stab_section_offset
1509 (output_bfd, &elf_hash_table (info)->stab_info,
1510 input_section,
1511 &elf_section_data (input_section)->stab_info,
1512 rela->r_offset));
1513 if (off == (bfd_vma) -1)
1514 skip = true;
1515 outrel.r_offset = off;
1518 outrel.r_offset += (input_section->output_section->vma
1519 + input_section->output_offset);
1521 if (skip)
1523 memset (&outrel, 0, sizeof outrel);
1524 relocate = false;
1526 else if ((r_type == R_X86_64_PC8) || (r_type == R_X86_64_PC16)
1527 || (r_type == R_X86_64_PC32))
1529 BFD_ASSERT (h != NULL && h->dynindx != -1);
1530 relocate = false;
1531 outrel.r_info = ELF64_R_INFO (h->dynindx, r_type);
1532 outrel.r_addend = relocation + rela->r_addend;
1534 else
1536 /* h->dynindx may be -1 if this symbol was marked to
1537 become local. */
1538 if (h == NULL
1539 || ((info->symbolic || h->dynindx == -1)
1540 && (h->elf_link_hash_flags
1541 & ELF_LINK_HASH_DEF_REGULAR) != 0))
1543 relocate = true;
1544 outrel.r_info = ELF64_R_INFO (0, R_X86_64_RELATIVE);
1545 outrel.r_addend = relocation + rela->r_addend;
1547 else
1549 BFD_ASSERT (h->dynindx != -1);
1550 relocate = false;
1551 outrel.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_32);
1552 outrel.r_addend = relocation + rela->r_addend;
1556 bfd_elf64_swap_reloca_out (output_bfd, &outrel,
1557 (((Elf64_External_Rela *)
1558 sreloc->contents)
1559 + sreloc->reloc_count));
1560 ++sreloc->reloc_count;
1562 /* If this reloc is against an external symbol, we do
1563 not want to fiddle with the addend. Otherwise, we
1564 need to include the symbol value so that it becomes
1565 an addend for the dynamic reloc. */
1566 if (! relocate)
1567 continue;
1570 break;
1572 default:
1573 break;
1576 r = _bfd_final_link_relocate (howto, input_bfd, input_section,
1577 contents, rela->r_offset,
1578 relocation, rela->r_addend);
1580 if (r != bfd_reloc_ok)
1582 switch (r)
1584 default:
1585 case bfd_reloc_outofrange:
1586 abort ();
1587 case bfd_reloc_overflow:
1589 const char *name;
1591 if (h != NULL)
1592 name = h->root.root.string;
1593 else
1595 name = bfd_elf_string_from_elf_section (input_bfd,
1596 symtab_hdr->sh_link,
1597 sym->st_name);
1598 if (name == NULL)
1599 return false;
1600 if (*name == '\0')
1601 name = bfd_section_name (input_bfd, sec);
1603 if (! ((*info->callbacks->reloc_overflow)
1604 (info, name, howto->name, (bfd_vma) 0,
1605 input_bfd, input_section, rela->r_offset)))
1606 return false;
1608 break;
1613 return true;
1616 /* Finish up dynamic symbol handling. We set the contents of various
1617 dynamic sections here. */
1619 static boolean
1620 elf64_x86_64_finish_dynamic_symbol (output_bfd, info, h, sym)
1621 bfd *output_bfd;
1622 struct bfd_link_info *info;
1623 struct elf_link_hash_entry *h;
1624 Elf_Internal_Sym *sym;
1626 bfd *dynobj;
1628 dynobj = elf_hash_table (info)->dynobj;
1630 if (h->plt.offset != (bfd_vma) -1)
1632 asection *splt;
1633 asection *sgot;
1634 asection *srela;
1635 bfd_vma plt_index;
1636 bfd_vma got_offset;
1637 Elf_Internal_Rela rela;
1639 /* This symbol has an entry in the procedure linkage table. Set
1640 it up. */
1642 BFD_ASSERT (h->dynindx != -1);
1644 splt = bfd_get_section_by_name (dynobj, ".plt");
1645 sgot = bfd_get_section_by_name (dynobj, ".got.plt");
1646 srela = bfd_get_section_by_name (dynobj, ".rela.plt");
1647 BFD_ASSERT (splt != NULL && sgot != NULL && srela != NULL);
1649 /* Get the index in the procedure linkage table which
1650 corresponds to this symbol. This is the index of this symbol
1651 in all the symbols for which we are making plt entries. The
1652 first entry in the procedure linkage table is reserved. */
1653 plt_index = h->plt.offset / PLT_ENTRY_SIZE - 1;
1655 /* Get the offset into the .got table of the entry that
1656 corresponds to this function. Each .got entry is GOT_ENTRY_SIZE
1657 bytes. The first three are reserved. */
1658 got_offset = (plt_index + 3) * GOT_ENTRY_SIZE;
1660 /* Fill in the entry in the procedure linkage table. */
1661 memcpy (splt->contents + h->plt.offset, elf64_x86_64_plt_entry,
1662 PLT_ENTRY_SIZE);
1664 /* Insert the relocation positions of the plt section. The magic
1665 numbers at the end of the statements are the positions of the
1666 relocations in the plt section. */
1667 bfd_put_64 (output_bfd, got_offset, splt->contents + h->plt.offset + 2);
1668 bfd_put_64 (output_bfd, plt_index * sizeof (Elf64_External_Rela),
1669 splt->contents + h->plt.offset + 7);
1670 bfd_put_64 (output_bfd, - (h->plt.offset + PLT_ENTRY_SIZE),
1671 splt->contents + h->plt.offset + 12);
1673 /* Fill in the entry in the global offset table. */
1674 bfd_put_64 (output_bfd, (splt->output_section->vma + splt->output_offset
1675 + h->plt.offset + 6),
1676 sgot->contents + got_offset);
1678 /* Fill in the entry in the .rela.plt section. */
1679 rela.r_offset = (sgot->output_section->vma
1680 + sgot->output_offset
1681 + got_offset);
1682 rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_JUMP_SLOT);
1683 rela.r_addend = 0;
1684 bfd_elf64_swap_reloca_out (output_bfd, &rela,
1685 ((Elf64_External_Rela *) srela->contents
1686 + plt_index));
1688 if ((h->elf_link_hash_flags & ELF_LINK_HASH_DEF_REGULAR) == 0)
1690 /* Mark the symbol as undefined, rather than as defined in
1691 the .plt section. Leave the value alone. */
1692 sym->st_shndx = SHN_UNDEF;
1693 /* If the symbol is weak, we do need to clear the value.
1694 Otherwise, the PLT entry would provide a definition for
1695 the symbol even if the symbol wasn't defined anywhere,
1696 and so the symbol would never be NULL. */
1697 if ((h->elf_link_hash_flags & ELF_LINK_HASH_REF_REGULAR_NONWEAK)
1698 == 0)
1699 sym->st_value = 0;
1703 if ((h->elf_link_hash_flags & ELF_LINK_HASH_NEEDS_COPY) != 0)
1705 asection *s;
1706 Elf_Internal_Rela rela;
1708 /* This symbol needs a copy reloc. Set it up. */
1710 BFD_ASSERT (h->dynindx != -1
1711 && (h->root.type == bfd_link_hash_defined
1712 || h->root.type == bfd_link_hash_defweak));
1714 s = bfd_get_section_by_name (h->root.u.def.section->owner,
1715 ".rela.bss");
1716 BFD_ASSERT (s != NULL);
1718 rela.r_offset = (h->root.u.def.value
1719 + h->root.u.def.section->output_section->vma
1720 + h->root.u.def.section->output_offset);
1721 rela.r_info = ELF64_R_INFO (h->dynindx, R_X86_64_COPY);
1722 rela.r_addend = 0;
1723 bfd_elf64_swap_reloca_out (output_bfd, &rela,
1724 ((Elf64_External_Rela *) s->contents
1725 + s->reloc_count));
1726 ++s->reloc_count;
1729 /* Mark _DYNAMIC and _GLOBAL_OFFSET_TABLE_ as absolute. */
1730 if (strcmp (h->root.root.string, "_DYNAMIC") == 0
1731 || strcmp (h->root.root.string, "_GLOBAL_OFFSET_TABLE_") == 0)
1732 sym->st_shndx = SHN_ABS;
1734 return true;
1737 /* Finish up the dynamic sections. */
1739 static boolean
1740 elf64_x86_64_finish_dynamic_sections (output_bfd, info)
1741 bfd *output_bfd;
1742 struct bfd_link_info *info;
1744 bfd *dynobj;
1745 asection *sdyn;
1746 asection *sgot;
1748 dynobj = elf_hash_table (info)->dynobj;
1750 sdyn = bfd_get_section_by_name (dynobj, ".dynamic");
1752 if (elf_hash_table (info)->dynamic_sections_created)
1754 asection *splt;
1755 Elf64_External_Dyn *dyncon, *dynconend;
1757 BFD_ASSERT (sdyn != NULL);
1759 dyncon = (Elf64_External_Dyn *) sdyn->contents;
1760 dynconend = (Elf64_External_Dyn *) (sdyn->contents + sdyn->_raw_size);
1761 for (; dyncon < dynconend; dyncon++)
1763 Elf_Internal_Dyn dyn;
1764 const char *name;
1765 asection *s;
1767 bfd_elf64_swap_dyn_in (dynobj, dyncon, &dyn);
1769 switch (dyn.d_tag)
1771 default:
1772 break;
1774 case DT_PLTGOT:
1775 name = ".got";
1776 goto get_vma;
1778 case DT_JMPREL:
1779 name = ".rela.plt";
1781 get_vma:
1782 s = bfd_get_section_by_name (output_bfd, name);
1783 BFD_ASSERT (s != NULL);
1784 dyn.d_un.d_ptr = s->vma;
1785 break;
1787 case DT_RELASZ:
1788 /* FIXME: This comment and code is from elf64-alpha.c: */
1789 /* My interpretation of the TIS v1.1 ELF document indicates
1790 that RELASZ should not include JMPREL. This is not what
1791 the rest of the BFD does. It is, however, what the
1792 glibc ld.so wants. Do this fixup here until we found
1793 out who is right. */
1794 s = bfd_get_section_by_name (output_bfd, ".rela.plt");
1795 if (s)
1797 /* Subtract JMPREL size from RELASZ. */
1798 dyn.d_un.d_val -=
1799 (s->_cooked_size ? s->_cooked_size : s->_raw_size);
1801 break;
1803 case DT_PLTRELSZ:
1804 s = bfd_get_section_by_name (output_bfd, ".rela.plt");
1805 BFD_ASSERT (s != NULL);
1806 dyn.d_un.d_val =
1807 (s->_cooked_size != 0 ? s->_cooked_size : s->_raw_size);
1808 break;
1811 bfd_elf64_swap_dyn_out (output_bfd, &dyn, dyncon);
1814 /* Initialize the contents of the .plt section. */
1815 splt = bfd_get_section_by_name (dynobj, ".plt");
1816 BFD_ASSERT (splt != NULL);
1817 if (splt->_raw_size > 0)
1819 memcpy (splt->contents, elf64_x86_64_plt0_entry, PLT_ENTRY_SIZE);
1822 elf_section_data (splt->output_section)->this_hdr.sh_entsize =
1823 PLT_ENTRY_SIZE;
1826 /* Set the first entry in the global offset table to the address of
1827 the dynamic section. */
1828 sgot = bfd_get_section_by_name (dynobj, ".got.plt");
1829 BFD_ASSERT (sgot != NULL);
1830 if (sgot->_raw_size > 0)
1832 if (sdyn == NULL)
1833 bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents);
1834 else
1835 bfd_put_64 (output_bfd,
1836 sdyn->output_section->vma + sdyn->output_offset,
1837 sgot->contents);
1838 /* Write GOT[1] and GOT[2], needed for the linker. */
1839 bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + GOT_ENTRY_SIZE);
1840 bfd_put_64 (output_bfd, (bfd_vma) 0, sgot->contents + GOT_ENTRY_SIZE*2);
1843 elf_section_data (sgot->output_section)->this_hdr.sh_entsize =
1844 GOT_ENTRY_SIZE;
1846 return true;
1850 * Why was the hash table entry size definition changed from
1851 * ARCH_SIZE/8 to 4? This breaks the 64 bit dynamic linker and
1852 * this is the only reason for the elf64_x86_64_size_info structure.
1855 const struct elf_size_info elf64_86_64_size_info =
1857 sizeof (Elf64_External_Ehdr),
1858 sizeof (Elf64_External_Phdr),
1859 sizeof (Elf64_External_Shdr),
1860 sizeof (Elf64_External_Rel),
1861 sizeof (Elf64_External_Rela),
1862 sizeof (Elf64_External_Sym),
1863 sizeof (Elf64_External_Dyn),
1864 sizeof (Elf_External_Note),
1865 8, /* hash-table entry size */
1866 1, /* internal relocations per external relocations */
1867 64, /* arch_size */
1868 8, /* file_align */
1869 ELFCLASS64, EV_CURRENT,
1870 bfd_elf64_write_out_phdrs,
1871 bfd_elf64_write_shdrs_and_ehdr,
1872 bfd_elf64_write_relocs,
1873 bfd_elf64_swap_symbol_out,
1874 bfd_elf64_slurp_reloc_table,
1875 bfd_elf64_slurp_symbol_table,
1876 bfd_elf64_swap_dyn_in,
1877 bfd_elf64_swap_dyn_out,
1878 NULL,
1879 NULL,
1880 NULL,
1881 NULL
1884 #define TARGET_LITTLE_SYM bfd_elf64_x86_64_vec
1885 #define TARGET_LITTLE_NAME "elf64-x86-64"
1886 #define ELF_ARCH bfd_arch_i386
1887 #define ELF_MACHINE_CODE EM_X86_64
1888 #define ELF_MAXPAGESIZE 0x100000
1890 #define elf_backend_size_info elf64_86_64_size_info
1892 #define elf_backend_can_gc_sections 1
1893 #define elf_backend_want_got_plt 1
1894 #define elf_backend_plt_readonly 1
1895 #define elf_backend_want_plt_sym 0
1896 #define elf_backend_got_header_size (GOT_ENTRY_SIZE*3)
1897 #define elf_backend_plt_header_size PLT_ENTRY_SIZE
1899 #define elf_info_to_howto elf64_x86_64_info_to_howto
1901 #define bfd_elf64_bfd_final_link _bfd_elf64_gc_common_final_link
1902 #define bfd_elf64_bfd_link_hash_table_create \
1903 elf64_x86_64_link_hash_table_create
1904 #define bfd_elf64_bfd_reloc_type_lookup elf64_x86_64_reloc_type_lookup
1906 #define elf_backend_adjust_dynamic_symbol elf64_x86_64_adjust_dynamic_symbol
1907 #define elf_backend_check_relocs elf64_x86_64_check_relocs
1908 #define elf_backend_create_dynamic_sections _bfd_elf_create_dynamic_sections
1909 #define elf_backend_finish_dynamic_sections \
1910 elf64_x86_64_finish_dynamic_sections
1911 #define elf_backend_finish_dynamic_symbol elf64_x86_64_finish_dynamic_symbol
1912 #define elf_backend_gc_mark_hook elf64_x86_64_gc_mark_hook
1913 #define elf_backend_gc_sweep_hook elf64_x86_64_gc_sweep_hook
1914 #define elf_backend_relocate_section elf64_x86_64_relocate_section
1915 #define elf_backend_size_dynamic_sections elf64_x86_64_size_dynamic_sections
1916 #define elf_backend_object_p elf64_x86_64_elf_object_p
1918 #include "elf64-target.h"