1 /* .eh_frame section optimization.
2 Copyright (C) 2001-2017 Free Software Foundation, Inc.
3 Written by Jakub Jelinek <jakub@redhat.com>.
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 3 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., 51 Franklin Street - Fifth Floor, Boston,
20 MA 02110-1301, USA. */
28 #define EH_FRAME_HDR_SIZE 8
34 unsigned char version;
35 unsigned char local_personality;
36 char augmentation[20];
38 bfd_signed_vma data_align;
40 bfd_vma augmentation_size;
42 struct elf_link_hash_entry *h;
47 unsigned int reloc_index;
49 struct eh_cie_fde *cie_inf;
50 unsigned char per_encoding;
51 unsigned char lsda_encoding;
52 unsigned char fde_encoding;
53 unsigned char initial_insn_length;
54 unsigned char can_make_lsda_relative;
55 unsigned char initial_instructions[50];
60 /* If *ITER hasn't reached END yet, read the next byte into *RESULT and
61 move onto the next byte. Return true on success. */
63 static inline bfd_boolean
64 read_byte (bfd_byte **iter, bfd_byte *end, unsigned char *result)
68 *result = *((*iter)++);
72 /* Move *ITER over LENGTH bytes, or up to END, whichever is closer.
73 Return true it was possible to move LENGTH bytes. */
75 static inline bfd_boolean
76 skip_bytes (bfd_byte **iter, bfd_byte *end, bfd_size_type length)
78 if ((bfd_size_type) (end - *iter) < length)
87 /* Move *ITER over an leb128, stopping at END. Return true if the end
88 of the leb128 was found. */
91 skip_leb128 (bfd_byte **iter, bfd_byte *end)
95 if (!read_byte (iter, end, &byte))
101 /* Like skip_leb128, but treat the leb128 as an unsigned value and
102 store it in *VALUE. */
105 read_uleb128 (bfd_byte **iter, bfd_byte *end, bfd_vma *value)
110 if (!skip_leb128 (iter, end))
116 *value = (*value << 7) | (*--p & 0x7f);
121 /* Like read_uleb128, but for signed values. */
124 read_sleb128 (bfd_byte **iter, bfd_byte *end, bfd_signed_vma *value)
129 if (!skip_leb128 (iter, end))
133 *value = ((*--p & 0x7f) ^ 0x40) - 0x40;
135 *value = (*value << 7) | (*--p & 0x7f);
140 /* Return 0 if either encoding is variable width, or not yet known to bfd. */
143 int get_DW_EH_PE_width (int encoding, int ptr_size)
145 /* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame
147 if ((encoding & 0x60) == 0x60)
150 switch (encoding & 7)
152 case DW_EH_PE_udata2: return 2;
153 case DW_EH_PE_udata4: return 4;
154 case DW_EH_PE_udata8: return 8;
155 case DW_EH_PE_absptr: return ptr_size;
163 #define get_DW_EH_PE_signed(encoding) (((encoding) & DW_EH_PE_signed) != 0)
165 /* Read a width sized value from memory. */
168 read_value (bfd *abfd, bfd_byte *buf, int width, int is_signed)
176 value = bfd_get_signed_16 (abfd, buf);
178 value = bfd_get_16 (abfd, buf);
182 value = bfd_get_signed_32 (abfd, buf);
184 value = bfd_get_32 (abfd, buf);
188 value = bfd_get_signed_64 (abfd, buf);
190 value = bfd_get_64 (abfd, buf);
200 /* Store a width sized value to memory. */
203 write_value (bfd *abfd, bfd_byte *buf, bfd_vma value, int width)
207 case 2: bfd_put_16 (abfd, value, buf); break;
208 case 4: bfd_put_32 (abfd, value, buf); break;
209 case 8: bfd_put_64 (abfd, value, buf); break;
210 default: BFD_FAIL ();
214 /* Return one if C1 and C2 CIEs can be merged. */
217 cie_eq (const void *e1, const void *e2)
219 const struct cie *c1 = (const struct cie *) e1;
220 const struct cie *c2 = (const struct cie *) e2;
222 if (c1->hash == c2->hash
223 && c1->length == c2->length
224 && c1->version == c2->version
225 && c1->local_personality == c2->local_personality
226 && strcmp (c1->augmentation, c2->augmentation) == 0
227 && strcmp (c1->augmentation, "eh") != 0
228 && c1->code_align == c2->code_align
229 && c1->data_align == c2->data_align
230 && c1->ra_column == c2->ra_column
231 && c1->augmentation_size == c2->augmentation_size
232 && memcmp (&c1->personality, &c2->personality,
233 sizeof (c1->personality)) == 0
234 && (c1->cie_inf->u.cie.u.sec->output_section
235 == c2->cie_inf->u.cie.u.sec->output_section)
236 && c1->per_encoding == c2->per_encoding
237 && c1->lsda_encoding == c2->lsda_encoding
238 && c1->fde_encoding == c2->fde_encoding
239 && c1->initial_insn_length == c2->initial_insn_length
240 && c1->initial_insn_length <= sizeof (c1->initial_instructions)
241 && memcmp (c1->initial_instructions,
242 c2->initial_instructions,
243 c1->initial_insn_length) == 0)
250 cie_hash (const void *e)
252 const struct cie *c = (const struct cie *) e;
257 cie_compute_hash (struct cie *c)
261 h = iterative_hash_object (c->length, h);
262 h = iterative_hash_object (c->version, h);
263 h = iterative_hash (c->augmentation, strlen (c->augmentation) + 1, h);
264 h = iterative_hash_object (c->code_align, h);
265 h = iterative_hash_object (c->data_align, h);
266 h = iterative_hash_object (c->ra_column, h);
267 h = iterative_hash_object (c->augmentation_size, h);
268 h = iterative_hash_object (c->personality, h);
269 h = iterative_hash_object (c->cie_inf->u.cie.u.sec->output_section, h);
270 h = iterative_hash_object (c->per_encoding, h);
271 h = iterative_hash_object (c->lsda_encoding, h);
272 h = iterative_hash_object (c->fde_encoding, h);
273 h = iterative_hash_object (c->initial_insn_length, h);
274 len = c->initial_insn_length;
275 if (len > sizeof (c->initial_instructions))
276 len = sizeof (c->initial_instructions);
277 h = iterative_hash (c->initial_instructions, len, h);
282 /* Return the number of extra bytes that we'll be inserting into
283 ENTRY's augmentation string. */
285 static INLINE unsigned int
286 extra_augmentation_string_bytes (struct eh_cie_fde *entry)
288 unsigned int size = 0;
291 if (entry->add_augmentation_size)
293 if (entry->u.cie.add_fde_encoding)
299 /* Likewise ENTRY's augmentation data. */
301 static INLINE unsigned int
302 extra_augmentation_data_bytes (struct eh_cie_fde *entry)
304 unsigned int size = 0;
305 if (entry->add_augmentation_size)
307 if (entry->cie && entry->u.cie.add_fde_encoding)
312 /* Return the size that ENTRY will have in the output. ALIGNMENT is the
313 required alignment of ENTRY in bytes. */
316 size_of_output_cie_fde (struct eh_cie_fde *entry, unsigned int alignment)
320 if (entry->size == 4)
323 + extra_augmentation_string_bytes (entry)
324 + extra_augmentation_data_bytes (entry)
325 + alignment - 1) & -alignment;
328 /* Assume that the bytes between *ITER and END are CFA instructions.
329 Try to move *ITER past the first instruction and return true on
330 success. ENCODED_PTR_WIDTH gives the width of pointer entries. */
333 skip_cfa_op (bfd_byte **iter, bfd_byte *end, unsigned int encoded_ptr_width)
338 if (!read_byte (iter, end, &op))
341 switch (op & 0xc0 ? op & 0xc0 : op)
344 case DW_CFA_advance_loc:
346 case DW_CFA_remember_state:
347 case DW_CFA_restore_state:
348 case DW_CFA_GNU_window_save:
353 case DW_CFA_restore_extended:
354 case DW_CFA_undefined:
355 case DW_CFA_same_value:
356 case DW_CFA_def_cfa_register:
357 case DW_CFA_def_cfa_offset:
358 case DW_CFA_def_cfa_offset_sf:
359 case DW_CFA_GNU_args_size:
360 /* One leb128 argument. */
361 return skip_leb128 (iter, end);
363 case DW_CFA_val_offset:
364 case DW_CFA_val_offset_sf:
365 case DW_CFA_offset_extended:
366 case DW_CFA_register:
368 case DW_CFA_offset_extended_sf:
369 case DW_CFA_GNU_negative_offset_extended:
370 case DW_CFA_def_cfa_sf:
371 /* Two leb128 arguments. */
372 return (skip_leb128 (iter, end)
373 && skip_leb128 (iter, end));
375 case DW_CFA_def_cfa_expression:
376 /* A variable-length argument. */
377 return (read_uleb128 (iter, end, &length)
378 && skip_bytes (iter, end, length));
380 case DW_CFA_expression:
381 case DW_CFA_val_expression:
382 /* A leb128 followed by a variable-length argument. */
383 return (skip_leb128 (iter, end)
384 && read_uleb128 (iter, end, &length)
385 && skip_bytes (iter, end, length));
388 return skip_bytes (iter, end, encoded_ptr_width);
390 case DW_CFA_advance_loc1:
391 return skip_bytes (iter, end, 1);
393 case DW_CFA_advance_loc2:
394 return skip_bytes (iter, end, 2);
396 case DW_CFA_advance_loc4:
397 return skip_bytes (iter, end, 4);
399 case DW_CFA_MIPS_advance_loc8:
400 return skip_bytes (iter, end, 8);
407 /* Try to interpret the bytes between BUF and END as CFA instructions.
408 If every byte makes sense, return a pointer to the first DW_CFA_nop
409 padding byte, or END if there is no padding. Return null otherwise.
410 ENCODED_PTR_WIDTH is as for skip_cfa_op. */
413 skip_non_nops (bfd_byte *buf, bfd_byte *end, unsigned int encoded_ptr_width,
414 unsigned int *set_loc_count)
420 if (*buf == DW_CFA_nop)
424 if (*buf == DW_CFA_set_loc)
426 if (!skip_cfa_op (&buf, end, encoded_ptr_width))
433 /* Convert absolute encoding ENCODING into PC-relative form.
434 SIZE is the size of a pointer. */
437 make_pc_relative (unsigned char encoding, unsigned int ptr_size)
439 if ((encoding & 0x7f) == DW_EH_PE_absptr)
443 encoding |= DW_EH_PE_sdata2;
446 encoding |= DW_EH_PE_sdata4;
449 encoding |= DW_EH_PE_sdata8;
452 return encoding | DW_EH_PE_pcrel;
455 /* Examine each .eh_frame_entry section and discard those
456 those that are marked SEC_EXCLUDE. */
459 bfd_elf_discard_eh_frame_entry (struct eh_frame_hdr_info *hdr_info)
462 for (i = 0; i < hdr_info->array_count; i++)
464 if (hdr_info->u.compact.entries[i]->flags & SEC_EXCLUDE)
467 for (j = i + 1; j < hdr_info->array_count; j++)
468 hdr_info->u.compact.entries[j-1] = hdr_info->u.compact.entries[j];
470 hdr_info->array_count--;
471 hdr_info->u.compact.entries[hdr_info->array_count] = NULL;
477 /* Add a .eh_frame_entry section. */
480 bfd_elf_record_eh_frame_entry (struct eh_frame_hdr_info *hdr_info,
483 if (hdr_info->array_count == hdr_info->u.compact.allocated_entries)
485 if (hdr_info->u.compact.allocated_entries == 0)
487 hdr_info->frame_hdr_is_compact = TRUE;
488 hdr_info->u.compact.allocated_entries = 2;
489 hdr_info->u.compact.entries =
490 bfd_malloc (hdr_info->u.compact.allocated_entries
491 * sizeof (hdr_info->u.compact.entries[0]));
495 hdr_info->u.compact.allocated_entries *= 2;
496 hdr_info->u.compact.entries =
497 bfd_realloc (hdr_info->u.compact.entries,
498 hdr_info->u.compact.allocated_entries
499 * sizeof (hdr_info->u.compact.entries[0]));
502 BFD_ASSERT (hdr_info->u.compact.entries);
505 hdr_info->u.compact.entries[hdr_info->array_count++] = sec;
508 /* Parse a .eh_frame_entry section. Figure out which text section it
512 _bfd_elf_parse_eh_frame_entry (struct bfd_link_info *info,
513 asection *sec, struct elf_reloc_cookie *cookie)
515 struct elf_link_hash_table *htab;
516 struct eh_frame_hdr_info *hdr_info;
517 unsigned long r_symndx;
520 htab = elf_hash_table (info);
521 hdr_info = &htab->eh_info;
524 || sec->sec_info_type != SEC_INFO_TYPE_NONE)
529 if (sec->output_section && bfd_is_abs_section (sec->output_section))
531 /* At least one of the sections is being discarded from the
532 link, so we should just ignore them. */
536 if (cookie->rel == cookie->relend)
539 /* The first relocation is the function start. */
540 r_symndx = cookie->rel->r_info >> cookie->r_sym_shift;
541 if (r_symndx == STN_UNDEF)
544 text_sec = _bfd_elf_section_for_symbol (cookie, r_symndx, FALSE);
546 if (text_sec == NULL)
549 elf_section_eh_frame_entry (text_sec) = sec;
550 if (text_sec->output_section
551 && bfd_is_abs_section (text_sec->output_section))
552 sec->flags |= SEC_EXCLUDE;
554 sec->sec_info_type = SEC_INFO_TYPE_EH_FRAME_ENTRY;
555 elf_section_data (sec)->sec_info = text_sec;
556 bfd_elf_record_eh_frame_entry (hdr_info, sec);
560 /* Try to parse .eh_frame section SEC, which belongs to ABFD. Store the
561 information in the section's sec_info field on success. COOKIE
562 describes the relocations in SEC. */
565 _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
566 asection *sec, struct elf_reloc_cookie *cookie)
568 #define REQUIRE(COND) \
571 goto free_no_table; \
574 bfd_byte *ehbuf = NULL, *buf, *end;
576 struct eh_cie_fde *this_inf;
577 unsigned int hdr_length, hdr_id;
578 unsigned int cie_count;
579 struct cie *cie, *local_cies = NULL;
580 struct elf_link_hash_table *htab;
581 struct eh_frame_hdr_info *hdr_info;
582 struct eh_frame_sec_info *sec_info = NULL;
583 unsigned int ptr_size;
584 unsigned int num_cies;
585 unsigned int num_entries;
586 elf_gc_mark_hook_fn gc_mark_hook;
588 htab = elf_hash_table (info);
589 hdr_info = &htab->eh_info;
592 || sec->sec_info_type != SEC_INFO_TYPE_NONE)
594 /* This file does not contain .eh_frame information. */
598 if (bfd_is_abs_section (sec->output_section))
600 /* At least one of the sections is being discarded from the
601 link, so we should just ignore them. */
605 /* Read the frame unwind information from abfd. */
607 REQUIRE (bfd_malloc_and_get_section (abfd, sec, &ehbuf));
610 && bfd_get_32 (abfd, ehbuf) == 0
611 && cookie->rel == cookie->relend)
613 /* Empty .eh_frame section. */
618 /* If .eh_frame section size doesn't fit into int, we cannot handle
619 it (it would need to use 64-bit .eh_frame format anyway). */
620 REQUIRE (sec->size == (unsigned int) sec->size);
622 ptr_size = (get_elf_backend_data (abfd)
623 ->elf_backend_eh_frame_address_size (abfd, sec));
624 REQUIRE (ptr_size != 0);
626 /* Go through the section contents and work out how many FDEs and
629 end = ehbuf + sec->size;
636 /* Read the length of the entry. */
637 REQUIRE (skip_bytes (&buf, end, 4));
638 hdr_length = bfd_get_32 (abfd, buf - 4);
640 /* 64-bit .eh_frame is not supported. */
641 REQUIRE (hdr_length != 0xffffffff);
645 REQUIRE (skip_bytes (&buf, end, 4));
646 hdr_id = bfd_get_32 (abfd, buf - 4);
650 REQUIRE (skip_bytes (&buf, end, hdr_length - 4));
653 sec_info = (struct eh_frame_sec_info *)
654 bfd_zmalloc (sizeof (struct eh_frame_sec_info)
655 + (num_entries - 1) * sizeof (struct eh_cie_fde));
658 /* We need to have a "struct cie" for each CIE in this section. */
659 local_cies = (struct cie *) bfd_zmalloc (num_cies * sizeof (*local_cies));
660 REQUIRE (local_cies);
662 /* FIXME: octets_per_byte. */
663 #define ENSURE_NO_RELOCS(buf) \
664 while (cookie->rel < cookie->relend \
665 && (cookie->rel->r_offset \
666 < (bfd_size_type) ((buf) - ehbuf))) \
668 REQUIRE (cookie->rel->r_info == 0); \
672 /* FIXME: octets_per_byte. */
673 #define SKIP_RELOCS(buf) \
674 while (cookie->rel < cookie->relend \
675 && (cookie->rel->r_offset \
676 < (bfd_size_type) ((buf) - ehbuf))) \
679 /* FIXME: octets_per_byte. */
680 #define GET_RELOC(buf) \
681 ((cookie->rel < cookie->relend \
682 && (cookie->rel->r_offset \
683 == (bfd_size_type) ((buf) - ehbuf))) \
684 ? cookie->rel : NULL)
688 gc_mark_hook = get_elf_backend_data (abfd)->gc_mark_hook;
689 while ((bfd_size_type) (buf - ehbuf) != sec->size)
692 bfd_byte *start, *insns, *insns_end;
693 bfd_size_type length;
694 unsigned int set_loc_count;
696 this_inf = sec_info->entry + sec_info->count;
699 /* Read the length of the entry. */
700 REQUIRE (skip_bytes (&buf, ehbuf + sec->size, 4));
701 hdr_length = bfd_get_32 (abfd, buf - 4);
703 /* The CIE/FDE must be fully contained in this input section. */
704 REQUIRE ((bfd_size_type) (buf - ehbuf) + hdr_length <= sec->size);
705 end = buf + hdr_length;
707 this_inf->offset = last_fde - ehbuf;
708 this_inf->size = 4 + hdr_length;
709 this_inf->reloc_index = cookie->rel - cookie->rels;
713 /* A zero-length CIE should only be found at the end of
715 REQUIRE ((bfd_size_type) (buf - ehbuf) == sec->size);
716 ENSURE_NO_RELOCS (buf);
721 REQUIRE (skip_bytes (&buf, end, 4));
722 hdr_id = bfd_get_32 (abfd, buf - 4);
726 unsigned int initial_insn_length;
731 /* Point CIE to one of the section-local cie structures. */
732 cie = local_cies + cie_count++;
734 cie->cie_inf = this_inf;
735 cie->length = hdr_length;
737 REQUIRE (read_byte (&buf, end, &cie->version));
739 /* Cannot handle unknown versions. */
740 REQUIRE (cie->version == 1
742 || cie->version == 4);
743 REQUIRE (strlen ((char *) buf) < sizeof (cie->augmentation));
745 strcpy (cie->augmentation, (char *) buf);
746 buf = (bfd_byte *) strchr ((char *) buf, '\0') + 1;
747 ENSURE_NO_RELOCS (buf);
748 if (buf[0] == 'e' && buf[1] == 'h')
750 /* GCC < 3.0 .eh_frame CIE */
751 /* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__
752 is private to each CIE, so we don't need it for anything.
754 REQUIRE (skip_bytes (&buf, end, ptr_size));
757 if (cie->version >= 4)
759 REQUIRE (buf + 1 < end);
760 REQUIRE (buf[0] == ptr_size);
761 REQUIRE (buf[1] == 0);
764 REQUIRE (read_uleb128 (&buf, end, &cie->code_align));
765 REQUIRE (read_sleb128 (&buf, end, &cie->data_align));
766 if (cie->version == 1)
769 cie->ra_column = *buf++;
772 REQUIRE (read_uleb128 (&buf, end, &cie->ra_column));
773 ENSURE_NO_RELOCS (buf);
774 cie->lsda_encoding = DW_EH_PE_omit;
775 cie->fde_encoding = DW_EH_PE_omit;
776 cie->per_encoding = DW_EH_PE_omit;
777 aug = cie->augmentation;
778 if (aug[0] != 'e' || aug[1] != 'h')
783 REQUIRE (read_uleb128 (&buf, end, &cie->augmentation_size));
784 ENSURE_NO_RELOCS (buf);
791 REQUIRE (read_byte (&buf, end, &cie->lsda_encoding));
792 ENSURE_NO_RELOCS (buf);
793 REQUIRE (get_DW_EH_PE_width (cie->lsda_encoding, ptr_size));
796 REQUIRE (read_byte (&buf, end, &cie->fde_encoding));
797 ENSURE_NO_RELOCS (buf);
798 REQUIRE (get_DW_EH_PE_width (cie->fde_encoding, ptr_size));
806 REQUIRE (read_byte (&buf, end, &cie->per_encoding));
807 per_width = get_DW_EH_PE_width (cie->per_encoding,
810 if ((cie->per_encoding & 0x70) == DW_EH_PE_aligned)
812 length = -(buf - ehbuf) & (per_width - 1);
813 REQUIRE (skip_bytes (&buf, end, length));
815 this_inf->u.cie.personality_offset = buf - start;
816 ENSURE_NO_RELOCS (buf);
817 /* Ensure we have a reloc here. */
818 REQUIRE (GET_RELOC (buf));
819 cie->personality.reloc_index
820 = cookie->rel - cookie->rels;
821 /* Cope with MIPS-style composite relocations. */
824 while (GET_RELOC (buf) != NULL);
825 REQUIRE (skip_bytes (&buf, end, per_width));
829 /* Unrecognized augmentation. Better bail out. */
834 /* For shared libraries, try to get rid of as many RELATIVE relocs
836 if (bfd_link_pic (info)
837 && (get_elf_backend_data (abfd)
838 ->elf_backend_can_make_relative_eh_frame
841 if ((cie->fde_encoding & 0x70) == DW_EH_PE_absptr)
842 this_inf->make_relative = 1;
843 /* If the CIE doesn't already have an 'R' entry, it's fairly
844 easy to add one, provided that there's no aligned data
845 after the augmentation string. */
846 else if (cie->fde_encoding == DW_EH_PE_omit
847 && (cie->per_encoding & 0x70) != DW_EH_PE_aligned)
849 if (*cie->augmentation == 0)
850 this_inf->add_augmentation_size = 1;
851 this_inf->u.cie.add_fde_encoding = 1;
852 this_inf->make_relative = 1;
855 if ((cie->lsda_encoding & 0x70) == DW_EH_PE_absptr)
856 cie->can_make_lsda_relative = 1;
859 /* If FDE encoding was not specified, it defaults to
861 if (cie->fde_encoding == DW_EH_PE_omit)
862 cie->fde_encoding = DW_EH_PE_absptr;
864 initial_insn_length = end - buf;
865 cie->initial_insn_length = initial_insn_length;
866 memcpy (cie->initial_instructions, buf,
867 initial_insn_length <= sizeof (cie->initial_instructions)
868 ? initial_insn_length : sizeof (cie->initial_instructions));
870 buf += initial_insn_length;
871 ENSURE_NO_RELOCS (buf);
873 if (!bfd_link_relocatable (info))
875 /* Keep info for merging cies. */
876 this_inf->u.cie.u.full_cie = cie;
877 this_inf->u.cie.per_encoding_relative
878 = (cie->per_encoding & 0x70) == DW_EH_PE_pcrel;
883 /* Find the corresponding CIE. */
884 unsigned int cie_offset = this_inf->offset + 4 - hdr_id;
885 for (cie = local_cies; cie < local_cies + cie_count; cie++)
886 if (cie_offset == cie->cie_inf->offset)
889 /* Ensure this FDE references one of the CIEs in this input
891 REQUIRE (cie != local_cies + cie_count);
892 this_inf->u.fde.cie_inf = cie->cie_inf;
893 this_inf->make_relative = cie->cie_inf->make_relative;
894 this_inf->add_augmentation_size
895 = cie->cie_inf->add_augmentation_size;
897 ENSURE_NO_RELOCS (buf);
898 if ((sec->flags & SEC_LINKER_CREATED) == 0 || cookie->rels != NULL)
902 REQUIRE (GET_RELOC (buf));
904 /* Chain together the FDEs for each section. */
905 rsec = _bfd_elf_gc_mark_rsec (info, sec, gc_mark_hook,
907 /* RSEC will be NULL if FDE was cleared out as it was belonging to
908 a discarded SHT_GROUP. */
911 REQUIRE (rsec->owner == abfd);
912 this_inf->u.fde.next_for_section = elf_fde_list (rsec);
913 elf_fde_list (rsec) = this_inf;
917 /* Skip the initial location and address range. */
919 length = get_DW_EH_PE_width (cie->fde_encoding, ptr_size);
920 REQUIRE (skip_bytes (&buf, end, 2 * length));
922 SKIP_RELOCS (buf - length);
923 if (!GET_RELOC (buf - length)
924 && read_value (abfd, buf - length, length, FALSE) == 0)
926 (*info->callbacks->minfo)
927 /* xgettext:c-format */
928 (_("discarding zero address range FDE in %B(%A).\n"),
930 this_inf->u.fde.cie_inf = NULL;
933 /* Skip the augmentation size, if present. */
934 if (cie->augmentation[0] == 'z')
935 REQUIRE (read_uleb128 (&buf, end, &length));
939 /* Of the supported augmentation characters above, only 'L'
940 adds augmentation data to the FDE. This code would need to
941 be adjusted if any future augmentations do the same thing. */
942 if (cie->lsda_encoding != DW_EH_PE_omit)
945 if (cie->can_make_lsda_relative && GET_RELOC (buf))
946 cie->cie_inf->u.cie.make_lsda_relative = 1;
947 this_inf->lsda_offset = buf - start;
948 /* If there's no 'z' augmentation, we don't know where the
949 CFA insns begin. Assume no padding. */
950 if (cie->augmentation[0] != 'z')
954 /* Skip over the augmentation data. */
955 REQUIRE (skip_bytes (&buf, end, length));
958 buf = last_fde + 4 + hdr_length;
960 /* For NULL RSEC (cleared FDE belonging to a discarded section)
961 the relocations are commonly cleared. We do not sanity check if
962 all these relocations are cleared as (1) relocations to
963 .gcc_except_table will remain uncleared (they will get dropped
964 with the drop of this unused FDE) and (2) BFD already safely drops
965 relocations of any type to .eh_frame by
966 elf_section_ignore_discarded_relocs.
967 TODO: The .gcc_except_table entries should be also filtered as
968 .eh_frame entries; or GCC could rather use COMDAT for them. */
972 /* Try to interpret the CFA instructions and find the first
973 padding nop. Shrink this_inf's size so that it doesn't
974 include the padding. */
975 length = get_DW_EH_PE_width (cie->fde_encoding, ptr_size);
977 insns_end = skip_non_nops (insns, end, length, &set_loc_count);
978 /* If we don't understand the CFA instructions, we can't know
979 what needs to be adjusted there. */
980 if (insns_end == NULL
981 /* For the time being we don't support DW_CFA_set_loc in
983 || (set_loc_count && this_inf->cie))
985 this_inf->size -= end - insns_end;
986 if (insns_end != end && this_inf->cie)
988 cie->initial_insn_length -= end - insns_end;
989 cie->length -= end - insns_end;
992 && ((cie->fde_encoding & 0x70) == DW_EH_PE_pcrel
993 || this_inf->make_relative))
998 this_inf->set_loc = (unsigned int *)
999 bfd_malloc ((set_loc_count + 1) * sizeof (unsigned int));
1000 REQUIRE (this_inf->set_loc);
1001 this_inf->set_loc[0] = set_loc_count;
1006 if (*p == DW_CFA_set_loc)
1007 this_inf->set_loc[++cnt] = p + 1 - start;
1008 REQUIRE (skip_cfa_op (&p, end, length));
1012 this_inf->removed = 1;
1013 this_inf->fde_encoding = cie->fde_encoding;
1014 this_inf->lsda_encoding = cie->lsda_encoding;
1017 BFD_ASSERT (sec_info->count == num_entries);
1018 BFD_ASSERT (cie_count == num_cies);
1020 elf_section_data (sec)->sec_info = sec_info;
1021 sec->sec_info_type = SEC_INFO_TYPE_EH_FRAME;
1022 if (!bfd_link_relocatable (info))
1024 /* Keep info for merging cies. */
1025 sec_info->cies = local_cies;
1031 (*info->callbacks->einfo)
1032 /* xgettext:c-format */
1033 (_("%P: error in %B(%A); no .eh_frame_hdr table will be created.\n"),
1035 hdr_info->u.dwarf.table = FALSE;
1046 /* Order eh_frame_hdr entries by the VMA of their text section. */
1049 cmp_eh_frame_hdr (const void *a, const void *b)
1055 sec = *(asection *const *)a;
1056 sec = (asection *) elf_section_data (sec)->sec_info;
1057 text_a = sec->output_section->vma + sec->output_offset;
1058 sec = *(asection *const *)b;
1059 sec = (asection *) elf_section_data (sec)->sec_info;
1060 text_b = sec->output_section->vma + sec->output_offset;
1062 if (text_a < text_b)
1064 return text_a > text_b;
1068 /* Add space for a CANTUNWIND terminator to SEC if the text sections
1069 referenced by it and NEXT are not contiguous, or NEXT is NULL. */
1072 add_eh_frame_hdr_terminator (asection *sec,
1081 /* See if there is a gap (presumably a text section without unwind info)
1082 between these two entries. */
1083 text_sec = (asection *) elf_section_data (sec)->sec_info;
1084 end = text_sec->output_section->vma + text_sec->output_offset
1086 text_sec = (asection *) elf_section_data (next)->sec_info;
1087 next_start = text_sec->output_section->vma + text_sec->output_offset;
1088 if (end == next_start)
1092 /* Add space for a CANTUNWIND terminator. */
1094 sec->rawsize = sec->size;
1096 bfd_set_section_size (sec->owner, sec, sec->size + 8);
1099 /* Finish a pass over all .eh_frame_entry sections. */
1102 _bfd_elf_end_eh_frame_parsing (struct bfd_link_info *info)
1104 struct eh_frame_hdr_info *hdr_info;
1107 hdr_info = &elf_hash_table (info)->eh_info;
1109 if (info->eh_frame_hdr_type != COMPACT_EH_HDR
1110 || hdr_info->array_count == 0)
1113 bfd_elf_discard_eh_frame_entry (hdr_info);
1115 qsort (hdr_info->u.compact.entries, hdr_info->array_count,
1116 sizeof (asection *), cmp_eh_frame_hdr);
1118 for (i = 0; i < hdr_info->array_count - 1; i++)
1120 add_eh_frame_hdr_terminator (hdr_info->u.compact.entries[i],
1121 hdr_info->u.compact.entries[i + 1]);
1124 /* Add a CANTUNWIND terminator after the last entry. */
1125 add_eh_frame_hdr_terminator (hdr_info->u.compact.entries[i], NULL);
1129 /* Mark all relocations against CIE or FDE ENT, which occurs in
1130 .eh_frame section SEC. COOKIE describes the relocations in SEC;
1131 its "rel" field can be changed freely. */
1134 mark_entry (struct bfd_link_info *info, asection *sec,
1135 struct eh_cie_fde *ent, elf_gc_mark_hook_fn gc_mark_hook,
1136 struct elf_reloc_cookie *cookie)
1138 /* FIXME: octets_per_byte. */
1139 for (cookie->rel = cookie->rels + ent->reloc_index;
1140 cookie->rel < cookie->relend
1141 && cookie->rel->r_offset < ent->offset + ent->size;
1143 if (!_bfd_elf_gc_mark_reloc (info, sec, gc_mark_hook, cookie))
1149 /* Mark all the relocations against FDEs that relate to code in input
1150 section SEC. The FDEs belong to .eh_frame section EH_FRAME, whose
1151 relocations are described by COOKIE. */
1154 _bfd_elf_gc_mark_fdes (struct bfd_link_info *info, asection *sec,
1155 asection *eh_frame, elf_gc_mark_hook_fn gc_mark_hook,
1156 struct elf_reloc_cookie *cookie)
1158 struct eh_cie_fde *fde, *cie;
1160 for (fde = elf_fde_list (sec); fde; fde = fde->u.fde.next_for_section)
1162 if (!mark_entry (info, eh_frame, fde, gc_mark_hook, cookie))
1165 /* At this stage, all cie_inf fields point to local CIEs, so we
1166 can use the same cookie to refer to them. */
1167 cie = fde->u.fde.cie_inf;
1168 if (cie != NULL && !cie->u.cie.gc_mark)
1170 cie->u.cie.gc_mark = 1;
1171 if (!mark_entry (info, eh_frame, cie, gc_mark_hook, cookie))
1178 /* Input section SEC of ABFD is an .eh_frame section that contains the
1179 CIE described by CIE_INF. Return a version of CIE_INF that is going
1180 to be kept in the output, adding CIE_INF to the output if necessary.
1182 HDR_INFO is the .eh_frame_hdr information and COOKIE describes the
1183 relocations in REL. */
1185 static struct eh_cie_fde *
1186 find_merged_cie (bfd *abfd, struct bfd_link_info *info, asection *sec,
1187 struct eh_frame_hdr_info *hdr_info,
1188 struct elf_reloc_cookie *cookie,
1189 struct eh_cie_fde *cie_inf)
1191 unsigned long r_symndx;
1192 struct cie *cie, *new_cie;
1193 Elf_Internal_Rela *rel;
1196 /* Use CIE_INF if we have already decided to keep it. */
1197 if (!cie_inf->removed)
1200 /* If we have merged CIE_INF with another CIE, use that CIE instead. */
1201 if (cie_inf->u.cie.merged)
1202 return cie_inf->u.cie.u.merged_with;
1204 cie = cie_inf->u.cie.u.full_cie;
1206 /* Assume we will need to keep CIE_INF. */
1207 cie_inf->removed = 0;
1208 cie_inf->u.cie.u.sec = sec;
1210 /* If we are not merging CIEs, use CIE_INF. */
1214 if (cie->per_encoding != DW_EH_PE_omit)
1216 bfd_boolean per_binds_local;
1218 /* Work out the address of personality routine, or at least
1219 enough info that we could calculate the address had we made a
1220 final section layout. The symbol on the reloc is enough,
1221 either the hash for a global, or (bfd id, index) pair for a
1222 local. The assumption here is that no one uses addends on
1224 rel = cookie->rels + cie->personality.reloc_index;
1225 memset (&cie->personality, 0, sizeof (cie->personality));
1227 if (elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64)
1228 r_symndx = ELF64_R_SYM (rel->r_info);
1231 r_symndx = ELF32_R_SYM (rel->r_info);
1232 if (r_symndx >= cookie->locsymcount
1233 || ELF_ST_BIND (cookie->locsyms[r_symndx].st_info) != STB_LOCAL)
1235 struct elf_link_hash_entry *h;
1237 r_symndx -= cookie->extsymoff;
1238 h = cookie->sym_hashes[r_symndx];
1240 while (h->root.type == bfd_link_hash_indirect
1241 || h->root.type == bfd_link_hash_warning)
1242 h = (struct elf_link_hash_entry *) h->root.u.i.link;
1244 cie->personality.h = h;
1245 per_binds_local = SYMBOL_REFERENCES_LOCAL (info, h);
1249 Elf_Internal_Sym *sym;
1252 sym = &cookie->locsyms[r_symndx];
1253 sym_sec = bfd_section_from_elf_index (abfd, sym->st_shndx);
1254 if (sym_sec == NULL)
1257 if (sym_sec->kept_section != NULL)
1258 sym_sec = sym_sec->kept_section;
1259 if (sym_sec->output_section == NULL)
1262 cie->local_personality = 1;
1263 cie->personality.sym.bfd_id = abfd->id;
1264 cie->personality.sym.index = r_symndx;
1265 per_binds_local = TRUE;
1269 && bfd_link_pic (info)
1270 && (cie->per_encoding & 0x70) == DW_EH_PE_absptr
1271 && (get_elf_backend_data (abfd)
1272 ->elf_backend_can_make_relative_eh_frame (abfd, info, sec)))
1274 cie_inf->u.cie.make_per_encoding_relative = 1;
1275 cie_inf->u.cie.per_encoding_relative = 1;
1279 /* See if we can merge this CIE with an earlier one. */
1280 cie_compute_hash (cie);
1281 if (hdr_info->u.dwarf.cies == NULL)
1283 hdr_info->u.dwarf.cies = htab_try_create (1, cie_hash, cie_eq, free);
1284 if (hdr_info->u.dwarf.cies == NULL)
1287 loc = htab_find_slot_with_hash (hdr_info->u.dwarf.cies, cie,
1292 new_cie = (struct cie *) *loc;
1293 if (new_cie == NULL)
1295 /* Keep CIE_INF and record it in the hash table. */
1296 new_cie = (struct cie *) malloc (sizeof (struct cie));
1297 if (new_cie == NULL)
1300 memcpy (new_cie, cie, sizeof (struct cie));
1305 /* Merge CIE_INF with NEW_CIE->CIE_INF. */
1306 cie_inf->removed = 1;
1307 cie_inf->u.cie.merged = 1;
1308 cie_inf->u.cie.u.merged_with = new_cie->cie_inf;
1309 if (cie_inf->u.cie.make_lsda_relative)
1310 new_cie->cie_inf->u.cie.make_lsda_relative = 1;
1312 return new_cie->cie_inf;
1315 /* This function is called for each input file before the .eh_frame
1316 section is relocated. It discards duplicate CIEs and FDEs for discarded
1317 functions. The function returns TRUE iff any entries have been
1321 _bfd_elf_discard_section_eh_frame
1322 (bfd *abfd, struct bfd_link_info *info, asection *sec,
1323 bfd_boolean (*reloc_symbol_deleted_p) (bfd_vma, void *),
1324 struct elf_reloc_cookie *cookie)
1326 struct eh_cie_fde *ent;
1327 struct eh_frame_sec_info *sec_info;
1328 struct eh_frame_hdr_info *hdr_info;
1329 unsigned int ptr_size, offset;
1331 if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
1334 sec_info = (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
1335 if (sec_info == NULL)
1338 ptr_size = (get_elf_backend_data (sec->owner)
1339 ->elf_backend_eh_frame_address_size (sec->owner, sec));
1341 hdr_info = &elf_hash_table (info)->eh_info;
1342 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
1344 /* There should only be one zero terminator, on the last input
1345 file supplying .eh_frame (crtend.o). Remove any others. */
1346 ent->removed = sec->map_head.s != NULL;
1347 else if (!ent->cie && ent->u.fde.cie_inf != NULL)
1350 if ((sec->flags & SEC_LINKER_CREATED) != 0 && cookie->rels == NULL)
1353 = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
1355 = read_value (abfd, sec->contents + ent->offset + 8 + width,
1356 width, get_DW_EH_PE_signed (ent->fde_encoding));
1361 cookie->rel = cookie->rels + ent->reloc_index;
1362 /* FIXME: octets_per_byte. */
1363 BFD_ASSERT (cookie->rel < cookie->relend
1364 && cookie->rel->r_offset == ent->offset + 8);
1365 keep = !(*reloc_symbol_deleted_p) (ent->offset + 8, cookie);
1369 if (bfd_link_pic (info)
1370 && (((ent->fde_encoding & 0x70) == DW_EH_PE_absptr
1371 && ent->make_relative == 0)
1372 || (ent->fde_encoding & 0x70) == DW_EH_PE_aligned))
1374 static int num_warnings_issued = 0;
1376 /* If a shared library uses absolute pointers
1377 which we cannot turn into PC relative,
1378 don't create the binary search table,
1379 since it is affected by runtime relocations. */
1380 hdr_info->u.dwarf.table = FALSE;
1381 if (num_warnings_issued < 10)
1383 (*info->callbacks->einfo)
1384 /* xgettext:c-format */
1385 (_("%P: FDE encoding in %B(%A) prevents .eh_frame_hdr"
1386 " table being created.\n"), abfd, sec);
1387 num_warnings_issued ++;
1389 else if (num_warnings_issued == 10)
1391 (*info->callbacks->einfo)
1392 (_("%P: Further warnings about FDE encoding preventing .eh_frame_hdr generation dropped.\n"));
1393 num_warnings_issued ++;
1397 hdr_info->u.dwarf.fde_count++;
1398 ent->u.fde.cie_inf = find_merged_cie (abfd, info, sec, hdr_info,
1399 cookie, ent->u.fde.cie_inf);
1405 free (sec_info->cies);
1406 sec_info->cies = NULL;
1410 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
1413 ent->new_offset = offset;
1414 offset += size_of_output_cie_fde (ent, ptr_size);
1417 sec->rawsize = sec->size;
1419 return offset != sec->rawsize;
1422 /* This function is called for .eh_frame_hdr section after
1423 _bfd_elf_discard_section_eh_frame has been called on all .eh_frame
1424 input sections. It finalizes the size of .eh_frame_hdr section. */
1427 _bfd_elf_discard_section_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
1429 struct elf_link_hash_table *htab;
1430 struct eh_frame_hdr_info *hdr_info;
1433 htab = elf_hash_table (info);
1434 hdr_info = &htab->eh_info;
1436 if (!hdr_info->frame_hdr_is_compact && hdr_info->u.dwarf.cies != NULL)
1438 htab_delete (hdr_info->u.dwarf.cies);
1439 hdr_info->u.dwarf.cies = NULL;
1442 sec = hdr_info->hdr_sec;
1446 if (info->eh_frame_hdr_type == COMPACT_EH_HDR)
1448 /* For compact frames we only add the header. The actual table comes
1449 from the .eh_frame_entry sections. */
1454 sec->size = EH_FRAME_HDR_SIZE;
1455 if (hdr_info->u.dwarf.table)
1456 sec->size += 4 + hdr_info->u.dwarf.fde_count * 8;
1459 elf_eh_frame_hdr (abfd) = sec;
1463 /* Return true if there is at least one non-empty .eh_frame section in
1464 input files. Can only be called after ld has mapped input to
1465 output sections, and before sections are stripped. */
1468 _bfd_elf_eh_frame_present (struct bfd_link_info *info)
1470 asection *eh = bfd_get_section_by_name (info->output_bfd, ".eh_frame");
1475 /* Count only sections which have at least a single CIE or FDE.
1476 There cannot be any CIE or FDE <= 8 bytes. */
1477 for (eh = eh->map_head.s; eh != NULL; eh = eh->map_head.s)
1484 /* Return true if there is at least one .eh_frame_entry section in
1488 _bfd_elf_eh_frame_entry_present (struct bfd_link_info *info)
1493 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link.next)
1495 for (o = abfd->sections; o; o = o->next)
1497 const char *name = bfd_get_section_name (abfd, o);
1499 if (strcmp (name, ".eh_frame_entry")
1500 && !bfd_is_abs_section (o->output_section))
1507 /* This function is called from size_dynamic_sections.
1508 It needs to decide whether .eh_frame_hdr should be output or not,
1509 because when the dynamic symbol table has been sized it is too late
1510 to strip sections. */
1513 _bfd_elf_maybe_strip_eh_frame_hdr (struct bfd_link_info *info)
1515 struct elf_link_hash_table *htab;
1516 struct eh_frame_hdr_info *hdr_info;
1517 struct bfd_link_hash_entry *bh = NULL;
1518 struct elf_link_hash_entry *h;
1520 htab = elf_hash_table (info);
1521 hdr_info = &htab->eh_info;
1522 if (hdr_info->hdr_sec == NULL)
1525 if (bfd_is_abs_section (hdr_info->hdr_sec->output_section)
1526 || info->eh_frame_hdr_type == 0
1527 || (info->eh_frame_hdr_type == DWARF2_EH_HDR
1528 && !_bfd_elf_eh_frame_present (info))
1529 || (info->eh_frame_hdr_type == COMPACT_EH_HDR
1530 && !_bfd_elf_eh_frame_entry_present (info)))
1532 hdr_info->hdr_sec->flags |= SEC_EXCLUDE;
1533 hdr_info->hdr_sec = NULL;
1537 /* Add a hidden symbol so that systems without access to PHDRs can
1539 if (! (_bfd_generic_link_add_one_symbol
1540 (info, info->output_bfd, "__GNU_EH_FRAME_HDR", BSF_LOCAL,
1541 hdr_info->hdr_sec, 0, NULL, FALSE, FALSE, &bh)))
1544 h = (struct elf_link_hash_entry *) bh;
1546 h->other = STV_HIDDEN;
1547 get_elf_backend_data
1548 (info->output_bfd)->elf_backend_hide_symbol (info, h, TRUE);
1550 if (!hdr_info->frame_hdr_is_compact)
1551 hdr_info->u.dwarf.table = TRUE;
1555 /* Adjust an address in the .eh_frame section. Given OFFSET within
1556 SEC, this returns the new offset in the adjusted .eh_frame section,
1557 or -1 if the address refers to a CIE/FDE which has been removed
1558 or to offset with dynamic relocation which is no longer needed. */
1561 _bfd_elf_eh_frame_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED,
1562 struct bfd_link_info *info ATTRIBUTE_UNUSED,
1566 struct eh_frame_sec_info *sec_info;
1567 unsigned int lo, hi, mid;
1569 if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
1571 sec_info = (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
1573 if (offset >= sec->rawsize)
1574 return offset - sec->rawsize + sec->size;
1577 hi = sec_info->count;
1581 mid = (lo + hi) / 2;
1582 if (offset < sec_info->entry[mid].offset)
1585 >= sec_info->entry[mid].offset + sec_info->entry[mid].size)
1591 BFD_ASSERT (lo < hi);
1593 /* FDE or CIE was removed. */
1594 if (sec_info->entry[mid].removed)
1595 return (bfd_vma) -1;
1597 /* If converting personality pointers to DW_EH_PE_pcrel, there will be
1598 no need for run-time relocation against the personality field. */
1599 if (sec_info->entry[mid].cie
1600 && sec_info->entry[mid].u.cie.make_per_encoding_relative
1601 && offset == (sec_info->entry[mid].offset + 8
1602 + sec_info->entry[mid].u.cie.personality_offset))
1603 return (bfd_vma) -2;
1605 /* If converting to DW_EH_PE_pcrel, there will be no need for run-time
1606 relocation against FDE's initial_location field. */
1607 if (!sec_info->entry[mid].cie
1608 && sec_info->entry[mid].make_relative
1609 && offset == sec_info->entry[mid].offset + 8)
1610 return (bfd_vma) -2;
1612 /* If converting LSDA pointers to DW_EH_PE_pcrel, there will be no need
1613 for run-time relocation against LSDA field. */
1614 if (!sec_info->entry[mid].cie
1615 && sec_info->entry[mid].u.fde.cie_inf->u.cie.make_lsda_relative
1616 && offset == (sec_info->entry[mid].offset + 8
1617 + sec_info->entry[mid].lsda_offset))
1618 return (bfd_vma) -2;
1620 /* If converting to DW_EH_PE_pcrel, there will be no need for run-time
1621 relocation against DW_CFA_set_loc's arguments. */
1622 if (sec_info->entry[mid].set_loc
1623 && sec_info->entry[mid].make_relative
1624 && (offset >= sec_info->entry[mid].offset + 8
1625 + sec_info->entry[mid].set_loc[1]))
1629 for (cnt = 1; cnt <= sec_info->entry[mid].set_loc[0]; cnt++)
1630 if (offset == sec_info->entry[mid].offset + 8
1631 + sec_info->entry[mid].set_loc[cnt])
1632 return (bfd_vma) -2;
1635 /* Any new augmentation bytes go before the first relocation. */
1636 return (offset + sec_info->entry[mid].new_offset
1637 - sec_info->entry[mid].offset
1638 + extra_augmentation_string_bytes (sec_info->entry + mid)
1639 + extra_augmentation_data_bytes (sec_info->entry + mid));
1642 /* Write out .eh_frame_entry section. Add CANTUNWIND terminator if needed.
1643 Also check that the contents look sane. */
1646 _bfd_elf_write_section_eh_frame_entry (bfd *abfd, struct bfd_link_info *info,
1647 asection *sec, bfd_byte *contents)
1649 const struct elf_backend_data *bed;
1650 bfd_byte cantunwind[8];
1654 asection *text_sec = (asection *) elf_section_data (sec)->sec_info;
1657 sec->rawsize = sec->size;
1659 BFD_ASSERT (sec->sec_info_type == SEC_INFO_TYPE_EH_FRAME_ENTRY);
1661 /* Check to make sure that the text section corresponding to this eh_frame_entry
1662 section has not been excluded. In particular, mips16 stub entries will be
1663 excluded outside of the normal process. */
1664 if (sec->flags & SEC_EXCLUDE
1665 || text_sec->flags & SEC_EXCLUDE)
1668 if (!bfd_set_section_contents (abfd, sec->output_section, contents,
1669 sec->output_offset, sec->rawsize))
1672 last_addr = bfd_get_signed_32 (abfd, contents);
1673 /* Check that all the entries are in order. */
1674 for (offset = 8; offset < sec->rawsize; offset += 8)
1676 addr = bfd_get_signed_32 (abfd, contents + offset) + offset;
1677 if (addr <= last_addr)
1679 /* xgettext:c-format */
1680 _bfd_error_handler (_("%B: %s not in order"), sec->owner, sec->name);
1687 addr = text_sec->output_section->vma + text_sec->output_offset
1690 addr -= (sec->output_section->vma + sec->output_offset + sec->rawsize);
1693 /* xgettext:c-format */
1694 _bfd_error_handler (_("%B: %s invalid input section size"),
1695 sec->owner, sec->name);
1696 bfd_set_error (bfd_error_bad_value);
1699 if (last_addr >= addr + sec->rawsize)
1701 /* xgettext:c-format */
1702 _bfd_error_handler (_("%B: %s points past end of text section"),
1703 sec->owner, sec->name);
1704 bfd_set_error (bfd_error_bad_value);
1708 if (sec->size == sec->rawsize)
1711 bed = get_elf_backend_data (abfd);
1712 BFD_ASSERT (sec->size == sec->rawsize + 8);
1713 BFD_ASSERT ((addr & 1) == 0);
1714 BFD_ASSERT (bed->cant_unwind_opcode);
1716 bfd_put_32 (abfd, addr, cantunwind);
1717 bfd_put_32 (abfd, (*bed->cant_unwind_opcode) (info), cantunwind + 4);
1718 return bfd_set_section_contents (abfd, sec->output_section, cantunwind,
1719 sec->output_offset + sec->rawsize, 8);
1722 /* Write out .eh_frame section. This is called with the relocated
1726 _bfd_elf_write_section_eh_frame (bfd *abfd,
1727 struct bfd_link_info *info,
1731 struct eh_frame_sec_info *sec_info;
1732 struct elf_link_hash_table *htab;
1733 struct eh_frame_hdr_info *hdr_info;
1734 unsigned int ptr_size;
1735 struct eh_cie_fde *ent;
1736 bfd_size_type sec_size;
1738 if (sec->sec_info_type != SEC_INFO_TYPE_EH_FRAME)
1739 /* FIXME: octets_per_byte. */
1740 return bfd_set_section_contents (abfd, sec->output_section, contents,
1741 sec->output_offset, sec->size);
1743 ptr_size = (get_elf_backend_data (abfd)
1744 ->elf_backend_eh_frame_address_size (abfd, sec));
1745 BFD_ASSERT (ptr_size != 0);
1747 sec_info = (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
1748 htab = elf_hash_table (info);
1749 hdr_info = &htab->eh_info;
1751 if (hdr_info->u.dwarf.table && hdr_info->u.dwarf.array == NULL)
1753 hdr_info->frame_hdr_is_compact = FALSE;
1754 hdr_info->u.dwarf.array = (struct eh_frame_array_ent *)
1755 bfd_malloc (hdr_info->u.dwarf.fde_count
1756 * sizeof (*hdr_info->u.dwarf.array));
1758 if (hdr_info->u.dwarf.array == NULL)
1761 /* The new offsets can be bigger or smaller than the original offsets.
1762 We therefore need to make two passes over the section: one backward
1763 pass to move entries up and one forward pass to move entries down.
1764 The two passes won't interfere with each other because entries are
1766 for (ent = sec_info->entry + sec_info->count; ent-- != sec_info->entry;)
1767 if (!ent->removed && ent->new_offset > ent->offset)
1768 memmove (contents + ent->new_offset, contents + ent->offset, ent->size);
1770 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
1771 if (!ent->removed && ent->new_offset < ent->offset)
1772 memmove (contents + ent->new_offset, contents + ent->offset, ent->size);
1774 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
1776 unsigned char *buf, *end;
1777 unsigned int new_size;
1784 /* Any terminating FDE must be at the end of the section. */
1785 BFD_ASSERT (ent == sec_info->entry + sec_info->count - 1);
1789 buf = contents + ent->new_offset;
1790 end = buf + ent->size;
1791 new_size = size_of_output_cie_fde (ent, ptr_size);
1793 /* Update the size. It may be shrinked. */
1794 bfd_put_32 (abfd, new_size - 4, buf);
1796 /* Filling the extra bytes with DW_CFA_nops. */
1797 if (new_size != ent->size)
1798 memset (end, 0, new_size - ent->size);
1803 if (ent->make_relative
1804 || ent->u.cie.make_lsda_relative
1805 || ent->u.cie.per_encoding_relative)
1808 unsigned int action, extra_string, extra_data;
1809 unsigned int per_width, per_encoding;
1811 /* Need to find 'R' or 'L' augmentation's argument and modify
1812 DW_EH_PE_* value. */
1813 action = ((ent->make_relative ? 1 : 0)
1814 | (ent->u.cie.make_lsda_relative ? 2 : 0)
1815 | (ent->u.cie.per_encoding_relative ? 4 : 0));
1816 extra_string = extra_augmentation_string_bytes (ent);
1817 extra_data = extra_augmentation_data_bytes (ent);
1819 /* Skip length, id and version. */
1822 buf += strlen (aug) + 1;
1823 skip_leb128 (&buf, end);
1824 skip_leb128 (&buf, end);
1825 skip_leb128 (&buf, end);
1828 /* The uleb128 will always be a single byte for the kind
1829 of augmentation strings that we're prepared to handle. */
1830 *buf++ += extra_data;
1834 /* Make room for the new augmentation string and data bytes. */
1835 memmove (buf + extra_string + extra_data, buf, end - buf);
1836 memmove (aug + extra_string, aug, buf - (bfd_byte *) aug);
1837 buf += extra_string;
1838 end += extra_string + extra_data;
1840 if (ent->add_augmentation_size)
1843 *buf++ = extra_data - 1;
1845 if (ent->u.cie.add_fde_encoding)
1847 BFD_ASSERT (action & 1);
1849 *buf++ = make_pc_relative (DW_EH_PE_absptr, ptr_size);
1859 BFD_ASSERT (*buf == ent->lsda_encoding);
1860 *buf = make_pc_relative (*buf, ptr_size);
1866 if (ent->u.cie.make_per_encoding_relative)
1867 *buf = make_pc_relative (*buf, ptr_size);
1868 per_encoding = *buf++;
1869 per_width = get_DW_EH_PE_width (per_encoding, ptr_size);
1870 BFD_ASSERT (per_width != 0);
1871 BFD_ASSERT (((per_encoding & 0x70) == DW_EH_PE_pcrel)
1872 == ent->u.cie.per_encoding_relative);
1873 if ((per_encoding & 0x70) == DW_EH_PE_aligned)
1875 + ((buf - contents + per_width - 1)
1876 & ~((bfd_size_type) per_width - 1)));
1881 val = read_value (abfd, buf, per_width,
1882 get_DW_EH_PE_signed (per_encoding));
1883 if (ent->u.cie.make_per_encoding_relative)
1884 val -= (sec->output_section->vma
1885 + sec->output_offset
1886 + (buf - contents));
1889 val += (bfd_vma) ent->offset - ent->new_offset;
1890 val -= extra_string + extra_data;
1892 write_value (abfd, buf, val, per_width);
1900 BFD_ASSERT (*buf == ent->fde_encoding);
1901 *buf = make_pc_relative (*buf, ptr_size);
1916 bfd_vma value, address;
1919 struct eh_cie_fde *cie;
1922 cie = ent->u.fde.cie_inf;
1924 value = ((ent->new_offset + sec->output_offset + 4)
1925 - (cie->new_offset + cie->u.cie.u.sec->output_offset));
1926 bfd_put_32 (abfd, value, buf);
1927 if (bfd_link_relocatable (info))
1930 width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
1931 value = read_value (abfd, buf, width,
1932 get_DW_EH_PE_signed (ent->fde_encoding));
1936 switch (ent->fde_encoding & 0x70)
1938 case DW_EH_PE_textrel:
1939 BFD_ASSERT (hdr_info == NULL);
1941 case DW_EH_PE_datarel:
1943 switch (abfd->arch_info->arch)
1946 BFD_ASSERT (elf_gp (abfd) != 0);
1947 address += elf_gp (abfd);
1950 (*info->callbacks->einfo)
1951 (_("%P: DW_EH_PE_datarel unspecified"
1952 " for this architecture.\n"));
1956 BFD_ASSERT (htab->hgot != NULL
1957 && ((htab->hgot->root.type
1958 == bfd_link_hash_defined)
1959 || (htab->hgot->root.type
1960 == bfd_link_hash_defweak)));
1962 += (htab->hgot->root.u.def.value
1963 + htab->hgot->root.u.def.section->output_offset
1964 + (htab->hgot->root.u.def.section->output_section
1970 case DW_EH_PE_pcrel:
1971 value += (bfd_vma) ent->offset - ent->new_offset;
1972 address += (sec->output_section->vma
1973 + sec->output_offset
1977 if (ent->make_relative)
1978 value -= (sec->output_section->vma
1979 + sec->output_offset
1980 + ent->new_offset + 8);
1981 write_value (abfd, buf, value, width);
1988 /* The address calculation may overflow, giving us a
1989 value greater than 4G on a 32-bit target when
1990 dwarf_vma is 64-bit. */
1991 if (sizeof (address) > 4 && ptr_size == 4)
1992 address &= 0xffffffff;
1993 hdr_info->u.dwarf.array[hdr_info->array_count].initial_loc
1995 hdr_info->u.dwarf.array[hdr_info->array_count].range
1996 = read_value (abfd, buf + width, width, FALSE);
1997 hdr_info->u.dwarf.array[hdr_info->array_count++].fde
1998 = (sec->output_section->vma
1999 + sec->output_offset
2003 if ((ent->lsda_encoding & 0x70) == DW_EH_PE_pcrel
2004 || cie->u.cie.make_lsda_relative)
2006 buf += ent->lsda_offset;
2007 width = get_DW_EH_PE_width (ent->lsda_encoding, ptr_size);
2008 value = read_value (abfd, buf, width,
2009 get_DW_EH_PE_signed (ent->lsda_encoding));
2012 if ((ent->lsda_encoding & 0x70) == DW_EH_PE_pcrel)
2013 value += (bfd_vma) ent->offset - ent->new_offset;
2014 else if (cie->u.cie.make_lsda_relative)
2015 value -= (sec->output_section->vma
2016 + sec->output_offset
2017 + ent->new_offset + 8 + ent->lsda_offset);
2018 write_value (abfd, buf, value, width);
2021 else if (ent->add_augmentation_size)
2023 /* Skip the PC and length and insert a zero byte for the
2024 augmentation size. */
2026 memmove (buf + 1, buf, end - buf);
2032 /* Adjust DW_CFA_set_loc. */
2036 width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
2037 new_offset = ent->new_offset + 8
2038 + extra_augmentation_string_bytes (ent)
2039 + extra_augmentation_data_bytes (ent);
2041 for (cnt = 1; cnt <= ent->set_loc[0]; cnt++)
2043 buf = start + ent->set_loc[cnt];
2045 value = read_value (abfd, buf, width,
2046 get_DW_EH_PE_signed (ent->fde_encoding));
2050 if ((ent->fde_encoding & 0x70) == DW_EH_PE_pcrel)
2051 value += (bfd_vma) ent->offset + 8 - new_offset;
2052 if (ent->make_relative)
2053 value -= (sec->output_section->vma
2054 + sec->output_offset
2055 + new_offset + ent->set_loc[cnt]);
2056 write_value (abfd, buf, value, width);
2062 /* We don't align the section to its section alignment since the
2063 runtime library only expects all CIE/FDE records aligned at
2064 the pointer size. _bfd_elf_discard_section_eh_frame should
2065 have padded CIE/FDE records to multiple of pointer size with
2066 size_of_output_cie_fde. */
2067 sec_size = sec->size;
2068 if (sec_info->count != 0
2069 && sec_info->entry[sec_info->count - 1].size == 4)
2071 if ((sec_size % ptr_size) != 0)
2074 /* FIXME: octets_per_byte. */
2075 return bfd_set_section_contents (abfd, sec->output_section,
2076 contents, (file_ptr) sec->output_offset,
2080 /* Helper function used to sort .eh_frame_hdr search table by increasing
2081 VMA of FDE initial location. */
2084 vma_compare (const void *a, const void *b)
2086 const struct eh_frame_array_ent *p = (const struct eh_frame_array_ent *) a;
2087 const struct eh_frame_array_ent *q = (const struct eh_frame_array_ent *) b;
2088 if (p->initial_loc > q->initial_loc)
2090 if (p->initial_loc < q->initial_loc)
2092 if (p->range > q->range)
2094 if (p->range < q->range)
2099 /* Reorder .eh_frame_entry sections to match the associated text sections.
2100 This routine is called during the final linking step, just before writing
2101 the contents. At this stage, sections in the eh_frame_hdr_info are already
2102 sorted in order of increasing text section address and so we simply need
2103 to make the .eh_frame_entrys follow that same order. Note that it is
2104 invalid for a linker script to try to force a particular order of
2105 .eh_frame_entry sections. */
2108 _bfd_elf_fixup_eh_frame_hdr (struct bfd_link_info *info)
2110 asection *sec = NULL;
2112 struct eh_frame_hdr_info *hdr_info;
2115 struct bfd_link_order *p;
2117 hdr_info = &elf_hash_table (info)->eh_info;
2119 if (hdr_info->hdr_sec == NULL
2120 || info->eh_frame_hdr_type != COMPACT_EH_HDR
2121 || hdr_info->array_count == 0)
2124 /* Change section output offsets to be in text section order. */
2126 osec = hdr_info->u.compact.entries[0]->output_section;
2127 for (i = 0; i < hdr_info->array_count; i++)
2129 sec = hdr_info->u.compact.entries[i];
2130 if (sec->output_section != osec)
2133 (_("Invalid output section for .eh_frame_entry: %s"),
2134 sec->output_section->name);
2137 sec->output_offset = offset;
2138 offset += sec->size;
2142 /* Fix the link_order to match. */
2143 for (p = sec->output_section->map_head.link_order; p != NULL; p = p->next)
2145 if (p->type != bfd_indirect_link_order)
2148 p->offset = p->u.indirect.section->output_offset;
2149 if (p->next != NULL)
2156 (_("Invalid contents in %s section"), osec->name);
2163 /* The .eh_frame_hdr format for Compact EH frames:
2165 ubyte eh_ref_enc (DW_EH_PE_* encoding of typinfo references)
2166 uint32_t count (Number of entries in table)
2167 [array from .eh_frame_entry sections] */
2170 write_compact_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
2172 struct elf_link_hash_table *htab;
2173 struct eh_frame_hdr_info *hdr_info;
2175 const struct elf_backend_data *bed;
2177 bfd_byte contents[8];
2180 htab = elf_hash_table (info);
2181 hdr_info = &htab->eh_info;
2182 sec = hdr_info->hdr_sec;
2187 for (i = 0; i < sizeof (contents); i++)
2190 contents[0] = COMPACT_EH_HDR;
2191 bed = get_elf_backend_data (abfd);
2193 BFD_ASSERT (bed->compact_eh_encoding);
2194 contents[1] = (*bed->compact_eh_encoding) (info);
2196 count = (sec->output_section->size - 8) / 8;
2197 bfd_put_32 (abfd, count, contents + 4);
2198 return bfd_set_section_contents (abfd, sec->output_section, contents,
2199 (file_ptr) sec->output_offset, sec->size);
2202 /* The .eh_frame_hdr format for DWARF frames:
2204 ubyte version (currently 1)
2205 ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of
2207 ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count
2208 number (or DW_EH_PE_omit if there is no
2209 binary search table computed))
2210 ubyte table_enc (DW_EH_PE_* encoding of binary search table,
2211 or DW_EH_PE_omit if not present.
2212 DW_EH_PE_datarel is using address of
2213 .eh_frame_hdr section start as base)
2214 [encoded] eh_frame_ptr (pointer to start of .eh_frame section)
2215 optionally followed by:
2216 [encoded] fde_count (total number of FDEs in .eh_frame section)
2217 fde_count x [encoded] initial_loc, fde
2218 (array of encoded pairs containing
2219 FDE initial_location field and FDE address,
2220 sorted by increasing initial_loc). */
2223 write_dwarf_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
2225 struct elf_link_hash_table *htab;
2226 struct eh_frame_hdr_info *hdr_info;
2228 bfd_boolean retval = TRUE;
2230 htab = elf_hash_table (info);
2231 hdr_info = &htab->eh_info;
2232 sec = hdr_info->hdr_sec;
2234 asection *eh_frame_sec;
2236 bfd_vma encoded_eh_frame;
2238 size = EH_FRAME_HDR_SIZE;
2239 if (hdr_info->u.dwarf.array
2240 && hdr_info->array_count == hdr_info->u.dwarf.fde_count)
2241 size += 4 + hdr_info->u.dwarf.fde_count * 8;
2242 contents = (bfd_byte *) bfd_malloc (size);
2243 if (contents == NULL)
2246 eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame");
2247 if (eh_frame_sec == NULL)
2253 memset (contents, 0, EH_FRAME_HDR_SIZE);
2256 /* .eh_frame offset. */
2257 contents[1] = get_elf_backend_data (abfd)->elf_backend_encode_eh_address
2258 (abfd, info, eh_frame_sec, 0, sec, 4, &encoded_eh_frame);
2260 if (hdr_info->u.dwarf.array
2261 && hdr_info->array_count == hdr_info->u.dwarf.fde_count)
2263 /* FDE count encoding. */
2264 contents[2] = DW_EH_PE_udata4;
2265 /* Search table encoding. */
2266 contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
2270 contents[2] = DW_EH_PE_omit;
2271 contents[3] = DW_EH_PE_omit;
2273 bfd_put_32 (abfd, encoded_eh_frame, contents + 4);
2275 if (contents[2] != DW_EH_PE_omit)
2278 bfd_boolean overlap, overflow;
2280 bfd_put_32 (abfd, hdr_info->u.dwarf.fde_count,
2281 contents + EH_FRAME_HDR_SIZE);
2282 qsort (hdr_info->u.dwarf.array, hdr_info->u.dwarf.fde_count,
2283 sizeof (*hdr_info->u.dwarf.array), vma_compare);
2286 for (i = 0; i < hdr_info->u.dwarf.fde_count; i++)
2290 val = hdr_info->u.dwarf.array[i].initial_loc
2291 - sec->output_section->vma;
2292 val = ((val & 0xffffffff) ^ 0x80000000) - 0x80000000;
2293 if (elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64
2294 && (hdr_info->u.dwarf.array[i].initial_loc
2295 != sec->output_section->vma + val))
2297 bfd_put_32 (abfd, val, contents + EH_FRAME_HDR_SIZE + i * 8 + 4);
2298 val = hdr_info->u.dwarf.array[i].fde - sec->output_section->vma;
2299 val = ((val & 0xffffffff) ^ 0x80000000) - 0x80000000;
2300 if (elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64
2301 && (hdr_info->u.dwarf.array[i].fde
2302 != sec->output_section->vma + val))
2304 bfd_put_32 (abfd, val, contents + EH_FRAME_HDR_SIZE + i * 8 + 8);
2306 && (hdr_info->u.dwarf.array[i].initial_loc
2307 < (hdr_info->u.dwarf.array[i - 1].initial_loc
2308 + hdr_info->u.dwarf.array[i - 1].range)))
2312 (*info->callbacks->einfo) (_("%P: .eh_frame_hdr entry overflow.\n"));
2314 (*info->callbacks->einfo)
2315 (_("%P: .eh_frame_hdr refers to overlapping FDEs.\n"));
2316 if (overflow || overlap)
2318 bfd_set_error (bfd_error_bad_value);
2323 /* FIXME: octets_per_byte. */
2324 if (!bfd_set_section_contents (abfd, sec->output_section, contents,
2325 (file_ptr) sec->output_offset,
2330 if (hdr_info->u.dwarf.array != NULL)
2331 free (hdr_info->u.dwarf.array);
2335 /* Write out .eh_frame_hdr section. This must be called after
2336 _bfd_elf_write_section_eh_frame has been called on all input
2337 .eh_frame sections. */
2340 _bfd_elf_write_section_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
2342 struct elf_link_hash_table *htab;
2343 struct eh_frame_hdr_info *hdr_info;
2346 htab = elf_hash_table (info);
2347 hdr_info = &htab->eh_info;
2348 sec = hdr_info->hdr_sec;
2350 if (info->eh_frame_hdr_type == 0 || sec == NULL)
2353 if (info->eh_frame_hdr_type == COMPACT_EH_HDR)
2354 return write_compact_eh_frame_hdr (abfd, info);
2356 return write_dwarf_eh_frame_hdr (abfd, info);
2359 /* Return the width of FDE addresses. This is the default implementation. */
2362 _bfd_elf_eh_frame_address_size (bfd *abfd, asection *sec ATTRIBUTE_UNUSED)
2364 return elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64 ? 8 : 4;
2367 /* Decide whether we can use a PC-relative encoding within the given
2368 EH frame section. This is the default implementation. */
2371 _bfd_elf_can_make_relative (bfd *input_bfd ATTRIBUTE_UNUSED,
2372 struct bfd_link_info *info ATTRIBUTE_UNUSED,
2373 asection *eh_frame_section ATTRIBUTE_UNUSED)
2378 /* Select an encoding for the given address. Preference is given to
2379 PC-relative addressing modes. */
2382 _bfd_elf_encode_eh_address (bfd *abfd ATTRIBUTE_UNUSED,
2383 struct bfd_link_info *info ATTRIBUTE_UNUSED,
2384 asection *osec, bfd_vma offset,
2385 asection *loc_sec, bfd_vma loc_offset,
2388 *encoded = osec->vma + offset -
2389 (loc_sec->output_section->vma + loc_sec->output_offset + loc_offset);
2390 return DW_EH_PE_pcrel | DW_EH_PE_sdata4;