1 /* .eh_frame section optimization.
2 Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007
3 Free Software Foundation, Inc.
4 Written by Jakub Jelinek <jakub@redhat.com>.
6 This file is part of BFD, the Binary File Descriptor library.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
26 #include "elf/dwarf2.h"
28 #define EH_FRAME_HDR_SIZE 8
34 unsigned char version;
35 char augmentation[20];
37 bfd_signed_vma data_align;
39 bfd_vma augmentation_size;
42 struct eh_cie_fde *cie_inf;
43 unsigned char per_encoding;
44 unsigned char lsda_encoding;
45 unsigned char fde_encoding;
46 unsigned char initial_insn_length;
47 unsigned char make_relative;
48 unsigned char make_lsda_relative;
49 unsigned char initial_instructions[50];
54 /* If *ITER hasn't reached END yet, read the next byte into *RESULT and
55 move onto the next byte. Return true on success. */
57 static inline bfd_boolean
58 read_byte (bfd_byte **iter, bfd_byte *end, unsigned char *result)
62 *result = *((*iter)++);
66 /* Move *ITER over LENGTH bytes, or up to END, whichever is closer.
67 Return true it was possible to move LENGTH bytes. */
69 static inline bfd_boolean
70 skip_bytes (bfd_byte **iter, bfd_byte *end, bfd_size_type length)
72 if ((bfd_size_type) (end - *iter) < length)
81 /* Move *ITER over an leb128, stopping at END. Return true if the end
82 of the leb128 was found. */
85 skip_leb128 (bfd_byte **iter, bfd_byte *end)
89 if (!read_byte (iter, end, &byte))
95 /* Like skip_leb128, but treat the leb128 as an unsigned value and
96 store it in *VALUE. */
99 read_uleb128 (bfd_byte **iter, bfd_byte *end, bfd_vma *value)
104 if (!skip_leb128 (iter, end))
110 *value = (*value << 7) | (*--p & 0x7f);
115 /* Like read_uleb128, but for signed values. */
118 read_sleb128 (bfd_byte **iter, bfd_byte *end, bfd_signed_vma *value)
123 if (!skip_leb128 (iter, end))
127 *value = ((*--p & 0x7f) ^ 0x40) - 0x40;
129 *value = (*value << 7) | (*--p & 0x7f);
134 /* Return 0 if either encoding is variable width, or not yet known to bfd. */
137 int get_DW_EH_PE_width (int encoding, int ptr_size)
139 /* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame
141 if ((encoding & 0x60) == 0x60)
144 switch (encoding & 7)
146 case DW_EH_PE_udata2: return 2;
147 case DW_EH_PE_udata4: return 4;
148 case DW_EH_PE_udata8: return 8;
149 case DW_EH_PE_absptr: return ptr_size;
157 #define get_DW_EH_PE_signed(encoding) (((encoding) & DW_EH_PE_signed) != 0)
159 /* Read a width sized value from memory. */
162 read_value (bfd *abfd, bfd_byte *buf, int width, int is_signed)
170 value = bfd_get_signed_16 (abfd, buf);
172 value = bfd_get_16 (abfd, buf);
176 value = bfd_get_signed_32 (abfd, buf);
178 value = bfd_get_32 (abfd, buf);
182 value = bfd_get_signed_64 (abfd, buf);
184 value = bfd_get_64 (abfd, buf);
194 /* Store a width sized value to memory. */
197 write_value (bfd *abfd, bfd_byte *buf, bfd_vma value, int width)
201 case 2: bfd_put_16 (abfd, value, buf); break;
202 case 4: bfd_put_32 (abfd, value, buf); break;
203 case 8: bfd_put_64 (abfd, value, buf); break;
204 default: BFD_FAIL ();
208 /* Return one if C1 and C2 CIEs can be merged. */
211 cie_eq (const void *e1, const void *e2)
213 const struct cie *c1 = e1;
214 const struct cie *c2 = e2;
216 if (c1->hash == c2->hash
217 && c1->length == c2->length
218 && c1->version == c2->version
219 && strcmp (c1->augmentation, c2->augmentation) == 0
220 && strcmp (c1->augmentation, "eh") != 0
221 && c1->code_align == c2->code_align
222 && c1->data_align == c2->data_align
223 && c1->ra_column == c2->ra_column
224 && c1->augmentation_size == c2->augmentation_size
225 && c1->personality == c2->personality
226 && c1->output_sec == c2->output_sec
227 && c1->per_encoding == c2->per_encoding
228 && c1->lsda_encoding == c2->lsda_encoding
229 && c1->fde_encoding == c2->fde_encoding
230 && c1->initial_insn_length == c2->initial_insn_length
231 && memcmp (c1->initial_instructions,
232 c2->initial_instructions,
233 c1->initial_insn_length) == 0)
240 cie_hash (const void *e)
242 const struct cie *c = e;
247 cie_compute_hash (struct cie *c)
250 h = iterative_hash_object (c->length, h);
251 h = iterative_hash_object (c->version, h);
252 h = iterative_hash (c->augmentation, strlen (c->augmentation) + 1, h);
253 h = iterative_hash_object (c->code_align, h);
254 h = iterative_hash_object (c->data_align, h);
255 h = iterative_hash_object (c->ra_column, h);
256 h = iterative_hash_object (c->augmentation_size, h);
257 h = iterative_hash_object (c->personality, h);
258 h = iterative_hash_object (c->output_sec, h);
259 h = iterative_hash_object (c->per_encoding, h);
260 h = iterative_hash_object (c->lsda_encoding, h);
261 h = iterative_hash_object (c->fde_encoding, h);
262 h = iterative_hash_object (c->initial_insn_length, h);
263 h = iterative_hash (c->initial_instructions, c->initial_insn_length, h);
268 /* Return the number of extra bytes that we'll be inserting into
269 ENTRY's augmentation string. */
271 static INLINE unsigned int
272 extra_augmentation_string_bytes (struct eh_cie_fde *entry)
274 unsigned int size = 0;
277 if (entry->add_augmentation_size)
279 if (entry->add_fde_encoding)
285 /* Likewise ENTRY's augmentation data. */
287 static INLINE unsigned int
288 extra_augmentation_data_bytes (struct eh_cie_fde *entry)
290 unsigned int size = 0;
293 if (entry->add_augmentation_size)
295 if (entry->add_fde_encoding)
300 if (entry->cie_inf->add_augmentation_size)
306 /* Return the size that ENTRY will have in the output. ALIGNMENT is the
307 required alignment of ENTRY in bytes. */
310 size_of_output_cie_fde (struct eh_cie_fde *entry, unsigned int alignment)
314 if (entry->size == 4)
317 + extra_augmentation_string_bytes (entry)
318 + extra_augmentation_data_bytes (entry)
319 + alignment - 1) & -alignment;
322 /* Assume that the bytes between *ITER and END are CFA instructions.
323 Try to move *ITER past the first instruction and return true on
324 success. ENCODED_PTR_WIDTH gives the width of pointer entries. */
327 skip_cfa_op (bfd_byte **iter, bfd_byte *end, unsigned int encoded_ptr_width)
332 if (!read_byte (iter, end, &op))
335 switch (op & 0xc0 ? op & 0xc0 : op)
338 case DW_CFA_advance_loc:
340 case DW_CFA_remember_state:
341 case DW_CFA_restore_state:
342 case DW_CFA_GNU_window_save:
347 case DW_CFA_restore_extended:
348 case DW_CFA_undefined:
349 case DW_CFA_same_value:
350 case DW_CFA_def_cfa_register:
351 case DW_CFA_def_cfa_offset:
352 case DW_CFA_def_cfa_offset_sf:
353 case DW_CFA_GNU_args_size:
354 /* One leb128 argument. */
355 return skip_leb128 (iter, end);
357 case DW_CFA_val_offset:
358 case DW_CFA_val_offset_sf:
359 case DW_CFA_offset_extended:
360 case DW_CFA_register:
362 case DW_CFA_offset_extended_sf:
363 case DW_CFA_GNU_negative_offset_extended:
364 case DW_CFA_def_cfa_sf:
365 /* Two leb128 arguments. */
366 return (skip_leb128 (iter, end)
367 && skip_leb128 (iter, end));
369 case DW_CFA_def_cfa_expression:
370 /* A variable-length argument. */
371 return (read_uleb128 (iter, end, &length)
372 && skip_bytes (iter, end, length));
374 case DW_CFA_expression:
375 case DW_CFA_val_expression:
376 /* A leb128 followed by a variable-length argument. */
377 return (skip_leb128 (iter, end)
378 && read_uleb128 (iter, end, &length)
379 && skip_bytes (iter, end, length));
382 return skip_bytes (iter, end, encoded_ptr_width);
384 case DW_CFA_advance_loc1:
385 return skip_bytes (iter, end, 1);
387 case DW_CFA_advance_loc2:
388 return skip_bytes (iter, end, 2);
390 case DW_CFA_advance_loc4:
391 return skip_bytes (iter, end, 4);
393 case DW_CFA_MIPS_advance_loc8:
394 return skip_bytes (iter, end, 8);
401 /* Try to interpret the bytes between BUF and END as CFA instructions.
402 If every byte makes sense, return a pointer to the first DW_CFA_nop
403 padding byte, or END if there is no padding. Return null otherwise.
404 ENCODED_PTR_WIDTH is as for skip_cfa_op. */
407 skip_non_nops (bfd_byte *buf, bfd_byte *end, unsigned int encoded_ptr_width,
408 unsigned int *set_loc_count)
414 if (*buf == DW_CFA_nop)
418 if (*buf == DW_CFA_set_loc)
420 if (!skip_cfa_op (&buf, end, encoded_ptr_width))
427 /* This function is called for each input file before the .eh_frame
428 section is relocated. It discards duplicate CIEs and FDEs for discarded
429 functions. The function returns TRUE iff any entries have been
433 _bfd_elf_discard_section_eh_frame
434 (bfd *abfd, struct bfd_link_info *info, asection *sec,
435 bfd_boolean (*reloc_symbol_deleted_p) (bfd_vma, void *),
436 struct elf_reloc_cookie *cookie)
438 #define REQUIRE(COND) \
441 goto free_no_table; \
444 bfd_byte *ehbuf = NULL, *buf;
446 struct eh_cie_fde *ent, *this_inf;
447 unsigned int hdr_length, hdr_id;
452 unsigned int usage_count;
454 } *ecies = NULL, *ecie;
455 unsigned int ecie_count = 0, ecie_alloced = 0;
457 struct elf_link_hash_table *htab;
458 struct eh_frame_hdr_info *hdr_info;
459 struct eh_frame_sec_info *sec_info = NULL;
461 unsigned int ptr_size;
462 unsigned int entry_alloced;
466 /* This file does not contain .eh_frame information. */
470 if (bfd_is_abs_section (sec->output_section))
472 /* At least one of the sections is being discarded from the
473 link, so we should just ignore them. */
477 htab = elf_hash_table (info);
478 hdr_info = &htab->eh_info;
480 if (hdr_info->cies == NULL && !info->relocatable)
481 hdr_info->cies = htab_try_create (1, cie_hash, cie_eq, free);
483 /* Read the frame unwind information from abfd. */
485 REQUIRE (bfd_malloc_and_get_section (abfd, sec, &ehbuf));
488 && bfd_get_32 (abfd, ehbuf) == 0
489 && cookie->rel == cookie->relend)
491 /* Empty .eh_frame section. */
496 /* If .eh_frame section size doesn't fit into int, we cannot handle
497 it (it would need to use 64-bit .eh_frame format anyway). */
498 REQUIRE (sec->size == (unsigned int) sec->size);
500 ptr_size = (get_elf_backend_data (abfd)
501 ->elf_backend_eh_frame_address_size (abfd, sec));
502 REQUIRE (ptr_size != 0);
505 sec_info = bfd_zmalloc (sizeof (struct eh_frame_sec_info)
506 + 99 * sizeof (struct eh_cie_fde));
511 #define ENSURE_NO_RELOCS(buf) \
512 REQUIRE (!(cookie->rel < cookie->relend \
513 && (cookie->rel->r_offset \
514 < (bfd_size_type) ((buf) - ehbuf)) \
515 && cookie->rel->r_info != 0))
517 #define SKIP_RELOCS(buf) \
518 while (cookie->rel < cookie->relend \
519 && (cookie->rel->r_offset \
520 < (bfd_size_type) ((buf) - ehbuf))) \
523 #define GET_RELOC(buf) \
524 ((cookie->rel < cookie->relend \
525 && (cookie->rel->r_offset \
526 == (bfd_size_type) ((buf) - ehbuf))) \
527 ? cookie->rel : NULL)
532 bfd_byte *start, *end, *insns, *insns_end;
533 bfd_size_type length;
534 unsigned int set_loc_count;
536 if (sec_info->count == entry_alloced)
538 sec_info = bfd_realloc (sec_info,
539 sizeof (struct eh_frame_sec_info)
540 + ((entry_alloced + 99)
541 * sizeof (struct eh_cie_fde)));
544 memset (&sec_info->entry[entry_alloced], 0,
545 100 * sizeof (struct eh_cie_fde));
546 entry_alloced += 100;
549 this_inf = sec_info->entry + sec_info->count;
552 if ((bfd_size_type) (buf - ehbuf) == sec->size)
555 /* Read the length of the entry. */
556 REQUIRE (skip_bytes (&buf, ehbuf + sec->size, 4));
557 hdr_length = bfd_get_32 (abfd, buf - 4);
559 /* 64-bit .eh_frame is not supported. */
560 REQUIRE (hdr_length != 0xffffffff);
562 /* The CIE/FDE must be fully contained in this input section. */
563 REQUIRE ((bfd_size_type) (buf - ehbuf) + hdr_length <= sec->size);
564 end = buf + hdr_length;
566 this_inf->offset = last_fde - ehbuf;
567 this_inf->size = 4 + hdr_length;
571 /* A zero-length CIE should only be found at the end of
573 REQUIRE ((bfd_size_type) (buf - ehbuf) == sec->size);
574 ENSURE_NO_RELOCS (buf);
579 REQUIRE (skip_bytes (&buf, end, 4));
580 hdr_id = bfd_get_32 (abfd, buf - 4);
584 unsigned int initial_insn_length;
589 if (ecie_count == ecie_alloced)
591 ecies = bfd_realloc (ecies,
592 (ecie_alloced + 20) * sizeof (*ecies));
594 memset (&ecies[ecie_alloced], 0, 20 * sizeof (*ecies));
598 cie = &ecies[ecie_count].cie;
599 ecies[ecie_count].offset = this_inf->offset;
600 ecies[ecie_count++].entry = sec_info->count;
601 cie->length = hdr_length;
603 REQUIRE (read_byte (&buf, end, &cie->version));
605 /* Cannot handle unknown versions. */
606 REQUIRE (cie->version == 1 || cie->version == 3);
607 REQUIRE (strlen ((char *) buf) < sizeof (cie->augmentation));
609 strcpy (cie->augmentation, (char *) buf);
610 buf = (bfd_byte *) strchr ((char *) buf, '\0') + 1;
611 ENSURE_NO_RELOCS (buf);
612 if (buf[0] == 'e' && buf[1] == 'h')
614 /* GCC < 3.0 .eh_frame CIE */
615 /* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__
616 is private to each CIE, so we don't need it for anything.
618 REQUIRE (skip_bytes (&buf, end, ptr_size));
621 REQUIRE (read_uleb128 (&buf, end, &cie->code_align));
622 REQUIRE (read_sleb128 (&buf, end, &cie->data_align));
623 if (cie->version == 1)
626 cie->ra_column = *buf++;
629 REQUIRE (read_uleb128 (&buf, end, &cie->ra_column));
630 ENSURE_NO_RELOCS (buf);
631 cie->lsda_encoding = DW_EH_PE_omit;
632 cie->fde_encoding = DW_EH_PE_omit;
633 cie->per_encoding = DW_EH_PE_omit;
634 aug = cie->augmentation;
635 if (aug[0] != 'e' || aug[1] != 'h')
640 REQUIRE (read_uleb128 (&buf, end, &cie->augmentation_size));
641 ENSURE_NO_RELOCS (buf);
648 REQUIRE (read_byte (&buf, end, &cie->lsda_encoding));
649 ENSURE_NO_RELOCS (buf);
650 REQUIRE (get_DW_EH_PE_width (cie->lsda_encoding, ptr_size));
653 REQUIRE (read_byte (&buf, end, &cie->fde_encoding));
654 ENSURE_NO_RELOCS (buf);
655 REQUIRE (get_DW_EH_PE_width (cie->fde_encoding, ptr_size));
663 REQUIRE (read_byte (&buf, end, &cie->per_encoding));
664 per_width = get_DW_EH_PE_width (cie->per_encoding,
667 if ((cie->per_encoding & 0xf0) == DW_EH_PE_aligned)
669 length = -(buf - ehbuf) & (per_width - 1);
670 REQUIRE (skip_bytes (&buf, end, length));
672 ENSURE_NO_RELOCS (buf);
673 /* Ensure we have a reloc here, against
675 if (GET_RELOC (buf) != NULL)
677 unsigned long r_symndx;
678 asection *sym_sec = NULL;
682 r_symndx = ELF64_R_SYM (cookie->rel->r_info);
685 r_symndx = ELF32_R_SYM (cookie->rel->r_info);
686 if (r_symndx >= cookie->locsymcount)
688 struct elf_link_hash_entry *h;
690 r_symndx -= cookie->extsymoff;
691 h = cookie->sym_hashes[r_symndx];
693 while (h->root.type == bfd_link_hash_indirect
694 || h->root.type == bfd_link_hash_warning)
695 h = (struct elf_link_hash_entry *)
698 if (h->root.type == bfd_link_hash_defined
699 || h->root.type == bfd_link_hash_defweak)
701 cie->personality = h->root.u.def.value;
702 sym_sec = h->root.u.def.section;
707 Elf_Internal_Shdr *symtab_hdr;
708 Elf_Internal_Sym *sym;
710 symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
711 sym = bfd_elf_get_elf_syms (abfd, symtab_hdr,
716 cie->personality = sym->st_value;
717 sym_sec = (bfd_section_from_elf_index
718 (abfd, sym->st_shndx));
723 cie->personality += (sym_sec->output_section->vma
724 + sym_sec->output_offset);
726 /* Cope with MIPS-style composite relocations. */
729 while (GET_RELOC (buf) != NULL);
731 REQUIRE (skip_bytes (&buf, end, per_width));
732 REQUIRE (cie->personality);
736 /* Unrecognized augmentation. Better bail out. */
741 /* For shared libraries, try to get rid of as many RELATIVE relocs
744 && (get_elf_backend_data (abfd)
745 ->elf_backend_can_make_relative_eh_frame
748 if ((cie->fde_encoding & 0xf0) == DW_EH_PE_absptr)
749 cie->make_relative = 1;
750 /* If the CIE doesn't already have an 'R' entry, it's fairly
751 easy to add one, provided that there's no aligned data
752 after the augmentation string. */
753 else if (cie->fde_encoding == DW_EH_PE_omit
754 && (cie->per_encoding & 0xf0) != DW_EH_PE_aligned)
756 if (*cie->augmentation == 0)
757 this_inf->add_augmentation_size = 1;
758 this_inf->add_fde_encoding = 1;
759 cie->make_relative = 1;
764 && (get_elf_backend_data (abfd)
765 ->elf_backend_can_make_lsda_relative_eh_frame
767 && (cie->lsda_encoding & 0xf0) == DW_EH_PE_absptr)
768 cie->make_lsda_relative = 1;
770 /* If FDE encoding was not specified, it defaults to
772 if (cie->fde_encoding == DW_EH_PE_omit)
773 cie->fde_encoding = DW_EH_PE_absptr;
775 initial_insn_length = end - buf;
776 if (initial_insn_length <= sizeof (cie->initial_instructions))
778 cie->initial_insn_length = initial_insn_length;
779 memcpy (cie->initial_instructions, buf, initial_insn_length);
782 buf += initial_insn_length;
783 ENSURE_NO_RELOCS (buf);
787 /* Find the corresponding CIE. */
788 unsigned int cie_offset = this_inf->offset + 4 - hdr_id;
789 for (ecie = ecies; ecie < ecies + ecie_count; ++ecie)
790 if (cie_offset == ecie->offset)
793 /* Ensure this FDE references one of the CIEs in this input
795 REQUIRE (ecie != ecies + ecie_count);
798 ENSURE_NO_RELOCS (buf);
799 REQUIRE (GET_RELOC (buf));
801 if ((*reloc_symbol_deleted_p) (buf - ehbuf, cookie))
802 /* This is a FDE against a discarded section. It should
804 this_inf->removed = 1;
808 && (((cie->fde_encoding & 0xf0) == DW_EH_PE_absptr
809 && cie->make_relative == 0)
810 || (cie->fde_encoding & 0xf0) == DW_EH_PE_aligned))
812 /* If a shared library uses absolute pointers
813 which we cannot turn into PC relative,
814 don't create the binary search table,
815 since it is affected by runtime relocations. */
816 hdr_info->table = FALSE;
817 (*info->callbacks->einfo)
818 (_("%P: fde encoding in %B(%A) prevents .eh_frame_hdr"
819 " table being created.\n"), abfd, sec);
822 hdr_info->fde_count++;
823 this_inf->cie_inf = (void *) (ecie - ecies);
826 /* Skip the initial location and address range. */
828 length = get_DW_EH_PE_width (cie->fde_encoding, ptr_size);
829 REQUIRE (skip_bytes (&buf, end, 2 * length));
831 /* Skip the augmentation size, if present. */
832 if (cie->augmentation[0] == 'z')
833 REQUIRE (read_uleb128 (&buf, end, &length));
837 /* Of the supported augmentation characters above, only 'L'
838 adds augmentation data to the FDE. This code would need to
839 be adjusted if any future augmentations do the same thing. */
840 if (cie->lsda_encoding != DW_EH_PE_omit)
842 this_inf->lsda_offset = buf - start;
843 /* If there's no 'z' augmentation, we don't know where the
844 CFA insns begin. Assume no padding. */
845 if (cie->augmentation[0] != 'z')
849 /* Skip over the augmentation data. */
850 REQUIRE (skip_bytes (&buf, end, length));
853 buf = last_fde + 4 + hdr_length;
857 /* Try to interpret the CFA instructions and find the first
858 padding nop. Shrink this_inf's size so that it doesn't
859 include the padding. */
860 length = get_DW_EH_PE_width (cie->fde_encoding, ptr_size);
862 insns_end = skip_non_nops (insns, end, length, &set_loc_count);
863 /* If we don't understand the CFA instructions, we can't know
864 what needs to be adjusted there. */
865 if (insns_end == NULL
866 /* For the time being we don't support DW_CFA_set_loc in
868 || (set_loc_count && this_inf->cie))
870 this_inf->size -= end - insns_end;
871 if (insns_end != end && this_inf->cie)
873 cie->initial_insn_length -= end - insns_end;
874 cie->length -= end - insns_end;
877 && ((cie->fde_encoding & 0xf0) == DW_EH_PE_pcrel
878 || cie->make_relative))
883 this_inf->set_loc = bfd_malloc ((set_loc_count + 1)
884 * sizeof (unsigned int));
885 REQUIRE (this_inf->set_loc);
886 this_inf->set_loc[0] = set_loc_count;
891 if (*p == DW_CFA_set_loc)
892 this_inf->set_loc[++cnt] = p + 1 - start;
893 REQUIRE (skip_cfa_op (&p, end, length));
897 this_inf->fde_encoding = cie->fde_encoding;
898 this_inf->lsda_encoding = cie->lsda_encoding;
902 elf_section_data (sec)->sec_info = sec_info;
903 sec->sec_info_type = ELF_INFO_TYPE_EH_FRAME;
905 /* Look at all CIEs in this section and determine which can be
906 removed as unused, which can be merged with previous duplicate
907 CIEs and which need to be kept. */
908 for (ecie = ecies; ecie < ecies + ecie_count; ++ecie)
910 if (ecie->usage_count == 0)
912 sec_info->entry[ecie->entry].removed = 1;
915 ecie->cie.output_sec = sec->output_section;
916 ecie->cie.cie_inf = sec_info->entry + ecie->entry;
917 cie_compute_hash (&ecie->cie);
918 if (hdr_info->cies != NULL)
920 void **loc = htab_find_slot_with_hash (hdr_info->cies, &ecie->cie,
921 ecie->cie.hash, INSERT);
924 if (*loc != HTAB_EMPTY_ENTRY)
926 sec_info->entry[ecie->entry].removed = 1;
927 ecie->cie.cie_inf = ((struct cie *) *loc)->cie_inf;
931 *loc = malloc (sizeof (struct cie));
933 *loc = HTAB_DELETED_ENTRY;
935 memcpy (*loc, &ecie->cie, sizeof (struct cie));
938 ecie->cie.cie_inf->make_relative = ecie->cie.make_relative;
939 ecie->cie.cie_inf->make_lsda_relative = ecie->cie.make_lsda_relative;
940 ecie->cie.cie_inf->per_encoding_relative
941 = (ecie->cie.per_encoding & 0x70) == DW_EH_PE_pcrel;
944 /* Ok, now we can assign new offsets. */
946 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
951 ecie = ecies + (unsigned long) ent->cie_inf;
952 ent->cie_inf = ecie->cie.cie_inf;
954 ent->new_offset = offset;
955 offset += size_of_output_cie_fde (ent, ptr_size);
958 /* Resize the sec as needed. */
959 sec->rawsize = sec->size;
965 return offset != sec->rawsize;
968 (*info->callbacks->einfo)
969 (_("%P: error in %B(%A); no .eh_frame_hdr table will be created.\n"),
977 hdr_info->table = FALSE;
983 /* This function is called for .eh_frame_hdr section after
984 _bfd_elf_discard_section_eh_frame has been called on all .eh_frame
985 input sections. It finalizes the size of .eh_frame_hdr section. */
988 _bfd_elf_discard_section_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
990 struct elf_link_hash_table *htab;
991 struct eh_frame_hdr_info *hdr_info;
994 htab = elf_hash_table (info);
995 hdr_info = &htab->eh_info;
997 if (hdr_info->cies != NULL)
999 htab_delete (hdr_info->cies);
1000 hdr_info->cies = NULL;
1003 sec = hdr_info->hdr_sec;
1007 sec->size = EH_FRAME_HDR_SIZE;
1008 if (hdr_info->table)
1009 sec->size += 4 + hdr_info->fde_count * 8;
1011 elf_tdata (abfd)->eh_frame_hdr = sec;
1015 /* This function is called from size_dynamic_sections.
1016 It needs to decide whether .eh_frame_hdr should be output or not,
1017 because when the dynamic symbol table has been sized it is too late
1018 to strip sections. */
1021 _bfd_elf_maybe_strip_eh_frame_hdr (struct bfd_link_info *info)
1025 struct elf_link_hash_table *htab;
1026 struct eh_frame_hdr_info *hdr_info;
1028 htab = elf_hash_table (info);
1029 hdr_info = &htab->eh_info;
1030 if (hdr_info->hdr_sec == NULL)
1033 if (bfd_is_abs_section (hdr_info->hdr_sec->output_section))
1035 hdr_info->hdr_sec = NULL;
1040 if (info->eh_frame_hdr)
1041 for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
1043 /* Count only sections which have at least a single CIE or FDE.
1044 There cannot be any CIE or FDE <= 8 bytes. */
1045 o = bfd_get_section_by_name (abfd, ".eh_frame");
1046 if (o && o->size > 8 && !bfd_is_abs_section (o->output_section))
1052 hdr_info->hdr_sec->flags |= SEC_EXCLUDE;
1053 hdr_info->hdr_sec = NULL;
1057 hdr_info->table = TRUE;
1061 /* Adjust an address in the .eh_frame section. Given OFFSET within
1062 SEC, this returns the new offset in the adjusted .eh_frame section,
1063 or -1 if the address refers to a CIE/FDE which has been removed
1064 or to offset with dynamic relocation which is no longer needed. */
1067 _bfd_elf_eh_frame_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED,
1068 struct bfd_link_info *info,
1072 struct eh_frame_sec_info *sec_info;
1073 struct elf_link_hash_table *htab;
1074 struct eh_frame_hdr_info *hdr_info;
1075 unsigned int lo, hi, mid;
1077 if (sec->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
1079 sec_info = elf_section_data (sec)->sec_info;
1081 if (offset >= sec->rawsize)
1082 return offset - sec->rawsize + sec->size;
1084 htab = elf_hash_table (info);
1085 hdr_info = &htab->eh_info;
1086 if (hdr_info->offsets_adjusted)
1087 offset += sec->output_offset;
1090 hi = sec_info->count;
1094 mid = (lo + hi) / 2;
1095 if (offset < sec_info->entry[mid].offset)
1098 >= sec_info->entry[mid].offset + sec_info->entry[mid].size)
1104 BFD_ASSERT (lo < hi);
1106 /* FDE or CIE was removed. */
1107 if (sec_info->entry[mid].removed)
1108 return (bfd_vma) -1;
1110 /* If converting to DW_EH_PE_pcrel, there will be no need for run-time
1111 relocation against FDE's initial_location field. */
1112 if (!sec_info->entry[mid].cie
1113 && sec_info->entry[mid].cie_inf->make_relative
1114 && offset == sec_info->entry[mid].offset + 8)
1115 return (bfd_vma) -2;
1117 /* If converting LSDA pointers to DW_EH_PE_pcrel, there will be no need
1118 for run-time relocation against LSDA field. */
1119 if (!sec_info->entry[mid].cie
1120 && sec_info->entry[mid].cie_inf->make_lsda_relative
1121 && (offset == (sec_info->entry[mid].offset + 8
1122 + sec_info->entry[mid].lsda_offset))
1123 && (sec_info->entry[mid].cie_inf->need_lsda_relative
1124 || !hdr_info->offsets_adjusted))
1126 sec_info->entry[mid].cie_inf->need_lsda_relative = 1;
1127 return (bfd_vma) -2;
1130 /* If converting to DW_EH_PE_pcrel, there will be no need for run-time
1131 relocation against DW_CFA_set_loc's arguments. */
1132 if (sec_info->entry[mid].set_loc
1133 && (sec_info->entry[mid].cie
1134 ? sec_info->entry[mid].make_relative
1135 : sec_info->entry[mid].cie_inf->make_relative)
1136 && (offset >= sec_info->entry[mid].offset + 8
1137 + sec_info->entry[mid].set_loc[1]))
1141 for (cnt = 1; cnt <= sec_info->entry[mid].set_loc[0]; cnt++)
1142 if (offset == sec_info->entry[mid].offset + 8
1143 + sec_info->entry[mid].set_loc[cnt])
1144 return (bfd_vma) -2;
1147 if (hdr_info->offsets_adjusted)
1148 offset -= sec->output_offset;
1149 /* Any new augmentation bytes go before the first relocation. */
1150 return (offset + sec_info->entry[mid].new_offset
1151 - sec_info->entry[mid].offset
1152 + extra_augmentation_string_bytes (sec_info->entry + mid)
1153 + extra_augmentation_data_bytes (sec_info->entry + mid));
1156 /* Write out .eh_frame section. This is called with the relocated
1160 _bfd_elf_write_section_eh_frame (bfd *abfd,
1161 struct bfd_link_info *info,
1165 struct eh_frame_sec_info *sec_info;
1166 struct elf_link_hash_table *htab;
1167 struct eh_frame_hdr_info *hdr_info;
1168 unsigned int ptr_size;
1169 struct eh_cie_fde *ent;
1171 if (sec->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
1172 return bfd_set_section_contents (abfd, sec->output_section, contents,
1173 sec->output_offset, sec->size);
1175 ptr_size = (get_elf_backend_data (abfd)
1176 ->elf_backend_eh_frame_address_size (abfd, sec));
1177 BFD_ASSERT (ptr_size != 0);
1179 sec_info = elf_section_data (sec)->sec_info;
1180 htab = elf_hash_table (info);
1181 hdr_info = &htab->eh_info;
1183 /* First convert all offsets to output section offsets, so that a
1184 CIE offset is valid if the CIE is used by a FDE from some other
1185 section. This can happen when duplicate CIEs are deleted in
1186 _bfd_elf_discard_section_eh_frame. We do all sections here because
1187 this function might not be called on sections in the same order as
1188 _bfd_elf_discard_section_eh_frame. */
1189 if (!hdr_info->offsets_adjusted)
1193 struct eh_frame_sec_info *eh_inf;
1195 for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link_next)
1197 if (bfd_get_flavour (ibfd) != bfd_target_elf_flavour
1198 || (ibfd->flags & DYNAMIC) != 0)
1201 eh = bfd_get_section_by_name (ibfd, ".eh_frame");
1202 if (eh == NULL || eh->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
1205 eh_inf = elf_section_data (eh)->sec_info;
1206 for (ent = eh_inf->entry; ent < eh_inf->entry + eh_inf->count; ++ent)
1208 ent->offset += eh->output_offset;
1209 ent->new_offset += eh->output_offset;
1212 hdr_info->offsets_adjusted = TRUE;
1215 if (hdr_info->table && hdr_info->array == NULL)
1217 = bfd_malloc (hdr_info->fde_count * sizeof(*hdr_info->array));
1218 if (hdr_info->array == NULL)
1221 /* The new offsets can be bigger or smaller than the original offsets.
1222 We therefore need to make two passes over the section: one backward
1223 pass to move entries up and one forward pass to move entries down.
1224 The two passes won't interfere with each other because entries are
1226 for (ent = sec_info->entry + sec_info->count; ent-- != sec_info->entry;)
1227 if (!ent->removed && ent->new_offset > ent->offset)
1228 memmove (contents + ent->new_offset - sec->output_offset,
1229 contents + ent->offset - sec->output_offset, ent->size);
1231 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
1232 if (!ent->removed && ent->new_offset < ent->offset)
1233 memmove (contents + ent->new_offset - sec->output_offset,
1234 contents + ent->offset - sec->output_offset, ent->size);
1236 for (ent = sec_info->entry; ent < sec_info->entry + sec_info->count; ++ent)
1238 unsigned char *buf, *end;
1239 unsigned int new_size;
1246 /* Any terminating FDE must be at the end of the section. */
1247 BFD_ASSERT (ent == sec_info->entry + sec_info->count - 1);
1251 buf = contents + ent->new_offset - sec->output_offset;
1252 end = buf + ent->size;
1253 new_size = size_of_output_cie_fde (ent, ptr_size);
1255 /* Update the size. It may be shrinked. */
1256 bfd_put_32 (abfd, new_size - 4, buf);
1258 /* Filling the extra bytes with DW_CFA_nops. */
1259 if (new_size != ent->size)
1260 memset (end, 0, new_size - ent->size);
1265 if (ent->make_relative
1266 || ent->need_lsda_relative
1267 || ent->per_encoding_relative)
1270 unsigned int action, extra_string, extra_data;
1271 unsigned int per_width, per_encoding;
1273 /* Need to find 'R' or 'L' augmentation's argument and modify
1274 DW_EH_PE_* value. */
1275 action = ((ent->make_relative ? 1 : 0)
1276 | (ent->need_lsda_relative ? 2 : 0)
1277 | (ent->per_encoding_relative ? 4 : 0));
1278 extra_string = extra_augmentation_string_bytes (ent);
1279 extra_data = extra_augmentation_data_bytes (ent);
1281 /* Skip length, id and version. */
1284 buf += strlen (aug) + 1;
1285 skip_leb128 (&buf, end);
1286 skip_leb128 (&buf, end);
1287 skip_leb128 (&buf, end);
1290 /* The uleb128 will always be a single byte for the kind
1291 of augmentation strings that we're prepared to handle. */
1292 *buf++ += extra_data;
1296 /* Make room for the new augmentation string and data bytes. */
1297 memmove (buf + extra_string + extra_data, buf, end - buf);
1298 memmove (aug + extra_string, aug, buf - (bfd_byte *) aug);
1299 buf += extra_string;
1300 end += extra_string + extra_data;
1302 if (ent->add_augmentation_size)
1305 *buf++ = extra_data - 1;
1307 if (ent->add_fde_encoding)
1309 BFD_ASSERT (action & 1);
1311 *buf++ = DW_EH_PE_pcrel;
1321 BFD_ASSERT (*buf == ent->lsda_encoding);
1322 *buf |= DW_EH_PE_pcrel;
1328 per_encoding = *buf++;
1329 per_width = get_DW_EH_PE_width (per_encoding, ptr_size);
1330 BFD_ASSERT (per_width != 0);
1331 BFD_ASSERT (((per_encoding & 0x70) == DW_EH_PE_pcrel)
1332 == ent->per_encoding_relative);
1333 if ((per_encoding & 0xf0) == DW_EH_PE_aligned)
1335 + ((buf - contents + per_width - 1)
1336 & ~((bfd_size_type) per_width - 1)));
1341 val = read_value (abfd, buf, per_width,
1342 get_DW_EH_PE_signed (per_encoding));
1343 val += ent->offset - ent->new_offset;
1344 val -= extra_string + extra_data;
1345 write_value (abfd, buf, val, per_width);
1353 BFD_ASSERT (*buf == ent->fde_encoding);
1354 *buf |= DW_EH_PE_pcrel;
1369 bfd_vma value, address;
1375 value = ent->new_offset + 4 - ent->cie_inf->new_offset;
1376 bfd_put_32 (abfd, value, buf);
1378 width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
1379 value = read_value (abfd, buf, width,
1380 get_DW_EH_PE_signed (ent->fde_encoding));
1384 switch (ent->fde_encoding & 0xf0)
1386 case DW_EH_PE_indirect:
1387 case DW_EH_PE_textrel:
1388 BFD_ASSERT (hdr_info == NULL);
1390 case DW_EH_PE_datarel:
1392 asection *got = bfd_get_section_by_name (abfd, ".got");
1394 BFD_ASSERT (got != NULL);
1395 address += got->vma;
1398 case DW_EH_PE_pcrel:
1399 value += ent->offset - ent->new_offset;
1400 address += sec->output_section->vma + ent->offset + 8;
1403 if (ent->cie_inf->make_relative)
1404 value -= sec->output_section->vma + ent->new_offset + 8;
1405 write_value (abfd, buf, value, width);
1412 hdr_info->array[hdr_info->array_count].initial_loc = address;
1413 hdr_info->array[hdr_info->array_count++].fde
1414 = sec->output_section->vma + ent->new_offset;
1417 if ((ent->lsda_encoding & 0xf0) == DW_EH_PE_pcrel
1418 || ent->cie_inf->need_lsda_relative)
1420 buf += ent->lsda_offset;
1421 width = get_DW_EH_PE_width (ent->lsda_encoding, ptr_size);
1422 value = read_value (abfd, buf, width,
1423 get_DW_EH_PE_signed (ent->lsda_encoding));
1426 if ((ent->lsda_encoding & 0xf0) == DW_EH_PE_pcrel)
1427 value += ent->offset - ent->new_offset;
1428 else if (ent->cie_inf->need_lsda_relative)
1429 value -= (sec->output_section->vma + ent->new_offset + 8
1430 + ent->lsda_offset);
1431 write_value (abfd, buf, value, width);
1434 else if (ent->cie_inf->add_augmentation_size)
1436 /* Skip the PC and length and insert a zero byte for the
1437 augmentation size. */
1439 memmove (buf + 1, buf, end - buf);
1445 /* Adjust DW_CFA_set_loc. */
1446 unsigned int cnt, width;
1449 width = get_DW_EH_PE_width (ent->fde_encoding, ptr_size);
1450 new_offset = ent->new_offset + 8
1451 + extra_augmentation_string_bytes (ent)
1452 + extra_augmentation_data_bytes (ent);
1454 for (cnt = 1; cnt <= ent->set_loc[0]; cnt++)
1457 buf = start + ent->set_loc[cnt];
1459 value = read_value (abfd, buf, width,
1460 get_DW_EH_PE_signed (ent->fde_encoding));
1464 if ((ent->fde_encoding & 0xf0) == DW_EH_PE_pcrel)
1465 value += ent->offset + 8 - new_offset;
1466 if (ent->cie_inf->make_relative)
1467 value -= sec->output_section->vma + new_offset
1468 + ent->set_loc[cnt];
1469 write_value (abfd, buf, value, width);
1475 /* We don't align the section to its section alignment since the
1476 runtime library only expects all CIE/FDE records aligned at
1477 the pointer size. _bfd_elf_discard_section_eh_frame should
1478 have padded CIE/FDE records to multiple of pointer size with
1479 size_of_output_cie_fde. */
1480 if ((sec->size % ptr_size) != 0)
1483 return bfd_set_section_contents (abfd, sec->output_section,
1484 contents, (file_ptr) sec->output_offset,
1488 /* Helper function used to sort .eh_frame_hdr search table by increasing
1489 VMA of FDE initial location. */
1492 vma_compare (const void *a, const void *b)
1494 const struct eh_frame_array_ent *p = a;
1495 const struct eh_frame_array_ent *q = b;
1496 if (p->initial_loc > q->initial_loc)
1498 if (p->initial_loc < q->initial_loc)
1503 /* Write out .eh_frame_hdr section. This must be called after
1504 _bfd_elf_write_section_eh_frame has been called on all input
1506 .eh_frame_hdr format:
1507 ubyte version (currently 1)
1508 ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of
1510 ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count
1511 number (or DW_EH_PE_omit if there is no
1512 binary search table computed))
1513 ubyte table_enc (DW_EH_PE_* encoding of binary search table,
1514 or DW_EH_PE_omit if not present.
1515 DW_EH_PE_datarel is using address of
1516 .eh_frame_hdr section start as base)
1517 [encoded] eh_frame_ptr (pointer to start of .eh_frame section)
1518 optionally followed by:
1519 [encoded] fde_count (total number of FDEs in .eh_frame section)
1520 fde_count x [encoded] initial_loc, fde
1521 (array of encoded pairs containing
1522 FDE initial_location field and FDE address,
1523 sorted by increasing initial_loc). */
1526 _bfd_elf_write_section_eh_frame_hdr (bfd *abfd, struct bfd_link_info *info)
1528 struct elf_link_hash_table *htab;
1529 struct eh_frame_hdr_info *hdr_info;
1532 asection *eh_frame_sec;
1535 bfd_vma encoded_eh_frame;
1537 htab = elf_hash_table (info);
1538 hdr_info = &htab->eh_info;
1539 sec = hdr_info->hdr_sec;
1543 size = EH_FRAME_HDR_SIZE;
1544 if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
1545 size += 4 + hdr_info->fde_count * 8;
1546 contents = bfd_malloc (size);
1547 if (contents == NULL)
1550 eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame");
1551 if (eh_frame_sec == NULL)
1557 memset (contents, 0, EH_FRAME_HDR_SIZE);
1558 contents[0] = 1; /* Version. */
1559 contents[1] = get_elf_backend_data (abfd)->elf_backend_encode_eh_address
1560 (abfd, info, eh_frame_sec, 0, sec, 4,
1561 &encoded_eh_frame); /* .eh_frame offset. */
1563 if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
1565 contents[2] = DW_EH_PE_udata4; /* FDE count encoding. */
1566 contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4; /* Search table enc. */
1570 contents[2] = DW_EH_PE_omit;
1571 contents[3] = DW_EH_PE_omit;
1573 bfd_put_32 (abfd, encoded_eh_frame, contents + 4);
1575 if (contents[2] != DW_EH_PE_omit)
1579 bfd_put_32 (abfd, hdr_info->fde_count, contents + EH_FRAME_HDR_SIZE);
1580 qsort (hdr_info->array, hdr_info->fde_count, sizeof (*hdr_info->array),
1582 for (i = 0; i < hdr_info->fde_count; i++)
1585 hdr_info->array[i].initial_loc
1586 - sec->output_section->vma,
1587 contents + EH_FRAME_HDR_SIZE + i * 8 + 4);
1589 hdr_info->array[i].fde - sec->output_section->vma,
1590 contents + EH_FRAME_HDR_SIZE + i * 8 + 8);
1594 retval = bfd_set_section_contents (abfd, sec->output_section,
1595 contents, (file_ptr) sec->output_offset,
1601 /* Return the width of FDE addresses. This is the default implementation. */
1604 _bfd_elf_eh_frame_address_size (bfd *abfd, asection *sec ATTRIBUTE_UNUSED)
1606 return elf_elfheader (abfd)->e_ident[EI_CLASS] == ELFCLASS64 ? 8 : 4;
1609 /* Decide whether we can use a PC-relative encoding within the given
1610 EH frame section. This is the default implementation. */
1613 _bfd_elf_can_make_relative (bfd *input_bfd ATTRIBUTE_UNUSED,
1614 struct bfd_link_info *info ATTRIBUTE_UNUSED,
1615 asection *eh_frame_section ATTRIBUTE_UNUSED)
1620 /* Select an encoding for the given address. Preference is given to
1621 PC-relative addressing modes. */
1624 _bfd_elf_encode_eh_address (bfd *abfd ATTRIBUTE_UNUSED,
1625 struct bfd_link_info *info ATTRIBUTE_UNUSED,
1626 asection *osec, bfd_vma offset,
1627 asection *loc_sec, bfd_vma loc_offset,
1630 *encoded = osec->vma + offset -
1631 (loc_sec->output_section->vma + loc_sec->output_offset + loc_offset);
1632 return DW_EH_PE_pcrel | DW_EH_PE_sdata4;