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/* .eh_frame section optimization.
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Copyright 2001, 2002 Free Software Foundation, Inc.
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Written by Jakub Jelinek <jakub@redhat.com>.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#include "elf/dwarf2.h"
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#define EH_FRAME_HDR_SIZE 8
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struct cie_header hdr;
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unsigned char version;
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unsigned char augmentation[20];
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unsigned int code_align;
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unsigned int ra_column;
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unsigned int augmentation_size;
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struct elf_link_hash_entry *personality;
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unsigned char per_encoding;
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unsigned char lsda_encoding;
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unsigned char fde_encoding;
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unsigned char initial_insn_length;
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unsigned char make_relative;
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unsigned char make_lsda_relative;
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unsigned char initial_instructions[50];
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unsigned int new_offset;
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unsigned char fde_encoding;
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unsigned char lsda_encoding;
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unsigned char lsda_offset;
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unsigned char cie : 1;
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unsigned char removed : 1;
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unsigned char make_relative : 1;
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unsigned char make_lsda_relative : 1;
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unsigned char per_encoding_relative : 1;
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struct eh_frame_sec_info
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struct eh_cie_fde entry[1];
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struct eh_frame_array_ent
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struct eh_frame_hdr_info
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asection *last_cie_sec;
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unsigned int last_cie_offset;
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unsigned int fde_count, array_count;
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struct eh_frame_array_ent *array;
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/* TRUE if .eh_frame_hdr should contain the sorted search table.
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We build it if we successfully read all .eh_frame input sections
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and recognize them. */
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static bfd_vma read_unsigned_leb128
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PARAMS ((bfd *, char *, unsigned int *));
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static bfd_signed_vma read_signed_leb128
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PARAMS ((bfd *, char *, unsigned int *));
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static int get_DW_EH_PE_width
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static bfd_vma read_value
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PARAMS ((bfd *, bfd_byte *, int));
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static void write_value
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PARAMS ((bfd *, bfd_byte *, bfd_vma, int));
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static int cie_compare
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PARAMS ((struct cie *, struct cie *));
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static int vma_compare
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PARAMS ((const PTR a, const PTR b));
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/* Helper function for reading uleb128 encoded data. */
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read_unsigned_leb128 (abfd, buf, bytes_read_ptr)
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bfd *abfd ATTRIBUTE_UNUSED;
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unsigned int *bytes_read_ptr;
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unsigned int num_read;
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byte = bfd_get_8 (abfd, (bfd_byte *) buf);
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result |= (((bfd_vma) byte & 0x7f) << shift);
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* bytes_read_ptr = num_read;
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/* Helper function for reading sleb128 encoded data. */
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static bfd_signed_vma
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read_signed_leb128 (abfd, buf, bytes_read_ptr)
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bfd *abfd ATTRIBUTE_UNUSED;
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unsigned int * bytes_read_ptr;
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byte = bfd_get_8 (abfd, (bfd_byte *) buf);
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result |= (((bfd_vma) byte & 0x7f) << shift);
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result |= (((bfd_vma) -1) << (shift - 7)) << 7;
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* bytes_read_ptr = num_read;
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#define read_uleb128(VAR, BUF) \
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(VAR) = read_unsigned_leb128 (abfd, buf, &leb128_tmp); \
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(BUF) += leb128_tmp; \
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#define read_sleb128(VAR, BUF) \
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(VAR) = read_signed_leb128 (abfd, buf, &leb128_tmp); \
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(BUF) += leb128_tmp; \
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/* Return 0 if either encoding is variable width, or not yet known to bfd. */
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int get_DW_EH_PE_width (encoding, ptr_size)
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int encoding, ptr_size;
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/* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame
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if ((encoding & 0x60) == 0x60)
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switch (encoding & 7)
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case DW_EH_PE_udata2: return 2;
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case DW_EH_PE_udata4: return 4;
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case DW_EH_PE_udata8: return 8;
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case DW_EH_PE_absptr: return ptr_size;
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/* Read a width sized value from memory. */
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read_value (abfd, buf, width)
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case 2: value = bfd_get_16 (abfd, buf); break;
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case 4: value = bfd_get_32 (abfd, buf); break;
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case 8: value = bfd_get_64 (abfd, buf); break;
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default: BFD_FAIL (); return 0;
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/* Store a width sized value to memory. */
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write_value (abfd, buf, value, width)
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case 2: bfd_put_16 (abfd, value, buf); break;
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case 4: bfd_put_32 (abfd, value, buf); break;
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case 8: bfd_put_64 (abfd, value, buf); break;
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default: BFD_FAIL ();
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/* Return zero if C1 and C2 CIEs can be merged. */
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int cie_compare (c1, c2)
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if (c1->hdr.length == c2->hdr.length
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&& c1->version == c2->version
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&& strcmp (c1->augmentation, c2->augmentation) == 0
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&& strcmp (c1->augmentation, "eh") != 0
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&& c1->code_align == c2->code_align
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&& c1->data_align == c2->data_align
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&& c1->ra_column == c2->ra_column
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&& c1->augmentation_size == c2->augmentation_size
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&& c1->personality == c2->personality
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&& c1->per_encoding == c2->per_encoding
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&& c1->lsda_encoding == c2->lsda_encoding
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&& c1->fde_encoding == c2->fde_encoding
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&& (c1->initial_insn_length
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== c2->initial_insn_length)
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&& memcmp (c1->initial_instructions,
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c2->initial_instructions,
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c1->initial_insn_length) == 0)
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/* This function is called for each input file before the .eh_frame
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section is relocated. It discards duplicate CIEs and FDEs for discarded
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functions. The function returns true iff any entries have been
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_bfd_elf_discard_section_eh_frame (abfd, info, sec, ehdrsec,
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reloc_symbol_deleted_p, cookie)
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struct bfd_link_info *info;
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asection *sec, *ehdrsec;
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boolean (*reloc_symbol_deleted_p) (bfd_vma, PTR);
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struct elf_reloc_cookie *cookie;
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bfd_byte *ehbuf = NULL, *buf;
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bfd_byte *last_cie, *last_fde;
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struct cie_header hdr;
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struct eh_frame_hdr_info *hdr_info;
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struct eh_frame_sec_info *sec_info = NULL;
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unsigned int leb128_tmp;
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unsigned int cie_usage_count, last_cie_ndx, i, offset;
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unsigned int make_relative, make_lsda_relative;
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Elf_Internal_Rela *rel;
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bfd_size_type new_size;
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unsigned int ptr_size;
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if (sec->_raw_size == 0)
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/* This file does not contain .eh_frame information. */
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if ((sec->output_section != NULL
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&& bfd_is_abs_section (sec->output_section)))
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/* At least one of the sections is being discarded from the
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link, so we should just ignore them. */
320
BFD_ASSERT (elf_section_data (ehdrsec)->sec_info_type
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== ELF_INFO_TYPE_EH_FRAME_HDR);
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hdr_info = (struct eh_frame_hdr_info *)
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elf_section_data (ehdrsec)->sec_info;
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/* Read the frame unwind information from abfd. */
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ehbuf = (bfd_byte *) bfd_malloc (sec->_raw_size);
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if (! bfd_get_section_contents (abfd, sec, ehbuf, (bfd_vma) 0,
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if (sec->_raw_size >= 4
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&& bfd_get_32 (abfd, ehbuf) == 0
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&& cookie->rel == cookie->relend)
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/* Empty .eh_frame section. */
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/* If .eh_frame section size doesn't fit into int, we cannot handle
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it (it would need to use 64-bit .eh_frame format anyway). */
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if (sec->_raw_size != (unsigned int) sec->_raw_size)
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ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS]
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== ELFCLASS64) ? 8 : 4;
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memset (&cie, 0, sizeof (cie));
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new_size = sec->_raw_size;
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make_relative = hdr_info->last_cie.make_relative;
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make_lsda_relative = hdr_info->last_cie.make_lsda_relative;
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sec_info = bfd_zmalloc (sizeof (struct eh_frame_sec_info)
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+ 99 * sizeof (struct eh_cie_fde));
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if (sec_info == NULL)
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sec_info->alloced = 100;
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#define ENSURE_NO_RELOCS(buf) \
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if (cookie->rel < cookie->relend \
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&& (cookie->rel->r_offset \
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< (bfd_size_type) ((buf) - ehbuf))) \
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#define SKIP_RELOCS(buf) \
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while (cookie->rel < cookie->relend \
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&& (cookie->rel->r_offset \
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< (bfd_size_type) ((buf) - ehbuf))) \
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#define GET_RELOC(buf) \
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((cookie->rel < cookie->relend \
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&& (cookie->rel->r_offset \
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== (bfd_size_type) ((buf) - ehbuf))) \
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? cookie->rel : NULL)
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if (sec_info->count == sec_info->alloced)
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sec_info = bfd_realloc (sec_info,
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sizeof (struct eh_frame_sec_info)
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+ (sec_info->alloced + 99)
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* sizeof (struct eh_cie_fde));
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if (sec_info == NULL)
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memset (&sec_info->entry[sec_info->alloced], 0,
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100 * sizeof (struct eh_cie_fde));
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sec_info->alloced += 100;
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/* If we are at the end of the section, we still need to decide
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on whether to output or discard last encountered CIE (if any). */
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if ((bfd_size_type) (buf - ehbuf) == sec->_raw_size)
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hdr.id = (unsigned int) -1;
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if ((bfd_size_type) (buf + 4 - ehbuf) > sec->_raw_size)
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/* No space for CIE/FDE header length. */
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hdr.length = bfd_get_32 (abfd, buf);
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if (hdr.length == 0xffffffff)
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/* 64-bit .eh_frame is not supported. */
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if ((buf - ehbuf) + hdr.length > sec->_raw_size)
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/* CIE/FDE not contained fully in this .eh_frame input section. */
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sec_info->entry[sec_info->count].offset = last_fde - ehbuf;
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sec_info->entry[sec_info->count].size = 4 + hdr.length;
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/* CIE with length 0 must be only the last in the section. */
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if ((bfd_size_type) (buf - ehbuf) < sec->_raw_size)
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ENSURE_NO_RELOCS (buf);
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/* Now just finish last encountered CIE processing and break
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hdr.id = (unsigned int) -1;
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hdr.id = bfd_get_32 (abfd, buf);
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if (hdr.id == (unsigned int) -1)
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if (hdr.id == 0 || hdr.id == (unsigned int) -1)
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unsigned int initial_insn_length;
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if (last_cie != NULL)
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/* Now check if this CIE is identical to last CIE, in which case
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we can remove it, provided we adjust all FDEs.
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Also, it can be removed if we have removed all FDEs using
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if (cie_compare (&cie, &hdr_info->last_cie) == 0
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|| cie_usage_count == 0)
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new_size -= cie.hdr.length + 4;
459
sec_info->entry[last_cie_ndx].removed = 1;
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sec_info->entry[last_cie_ndx].sec = hdr_info->last_cie_sec;
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sec_info->entry[last_cie_ndx].new_offset
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= hdr_info->last_cie_offset;
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hdr_info->last_cie = cie;
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hdr_info->last_cie_sec = sec;
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hdr_info->last_cie_offset = last_cie - ehbuf;
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sec_info->entry[last_cie_ndx].make_relative
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sec_info->entry[last_cie_ndx].make_lsda_relative
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= cie.make_lsda_relative;
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sec_info->entry[last_cie_ndx].per_encoding_relative
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= (cie.per_encoding & 0x70) == DW_EH_PE_pcrel;
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if (hdr.id == (unsigned int) -1)
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last_cie_ndx = sec_info->count;
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sec_info->entry[sec_info->count].cie = 1;
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memset (&cie, 0, sizeof (cie));
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cie.version = *buf++;
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/* Cannot handle unknown versions. */
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if (cie.version != 1)
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if (strlen (buf) > sizeof (cie.augmentation) - 1)
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strcpy (cie.augmentation, buf);
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buf = strchr (buf, '\0') + 1;
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ENSURE_NO_RELOCS (buf);
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if (buf[0] == 'e' && buf[1] == 'h')
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/* GCC < 3.0 .eh_frame CIE */
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/* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__
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is private to each CIE, so we don't need it for anything.
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read_uleb128 (cie.code_align, buf);
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read_sleb128 (cie.data_align, buf);
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read_uleb128 (cie.ra_column, buf);
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ENSURE_NO_RELOCS (buf);
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cie.lsda_encoding = DW_EH_PE_omit;
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cie.fde_encoding = DW_EH_PE_omit;
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cie.per_encoding = DW_EH_PE_omit;
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aug = cie.augmentation;
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if (aug[0] != 'e' || aug[1] != 'h')
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read_uleb128 (cie.augmentation_size, buf);
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ENSURE_NO_RELOCS (buf);
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cie.lsda_encoding = *buf++;
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ENSURE_NO_RELOCS (buf);
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if (get_DW_EH_PE_width (cie.lsda_encoding, ptr_size) == 0)
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cie.fde_encoding = *buf++;
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ENSURE_NO_RELOCS (buf);
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if (get_DW_EH_PE_width (cie.fde_encoding, ptr_size) == 0)
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cie.per_encoding = *buf++;
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per_width = get_DW_EH_PE_width (cie.per_encoding,
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if ((cie.per_encoding & 0xf0) == DW_EH_PE_aligned)
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+ ((buf - ehbuf + per_width - 1)
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& ~((bfd_size_type) per_width - 1)));
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ENSURE_NO_RELOCS (buf);
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rel = GET_RELOC (buf);
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/* Ensure we have a reloc here, against
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unsigned long r_symndx;
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r_symndx = ELF64_R_SYM (cookie->rel->r_info);
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r_symndx = ELF32_R_SYM (cookie->rel->r_info);
566
if (r_symndx >= cookie->locsymcount)
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struct elf_link_hash_entry *h;
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r_symndx -= cookie->extsymoff;
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h = cookie->sym_hashes[r_symndx];
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while (h->root.type == bfd_link_hash_indirect
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|| h->root.type == bfd_link_hash_warning)
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h = (struct elf_link_hash_entry *)
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/* Unrecognized augmentation. Better bail out. */
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/* For shared libraries, try to get rid of as many RELATIVE relocs
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&& (cie.fde_encoding & 0xf0) == DW_EH_PE_absptr)
595
cie.make_relative = 1;
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&& (cie.lsda_encoding & 0xf0) == DW_EH_PE_absptr)
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cie.make_lsda_relative = 1;
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/* If FDE encoding was not specified, it defaults to
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if (cie.fde_encoding == DW_EH_PE_omit)
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cie.fde_encoding = DW_EH_PE_absptr;
606
initial_insn_length = cie.hdr.length - (buf - last_fde - 4);
607
if (initial_insn_length <= 50)
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cie.initial_insn_length = initial_insn_length;
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memcpy (cie.initial_instructions, buf, initial_insn_length);
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buf += initial_insn_length;
613
ENSURE_NO_RELOCS (buf);
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/* Ensure this FDE uses the last CIE encountered. */
620
|| hdr.id != (unsigned int) (buf - 4 - last_cie))
623
ENSURE_NO_RELOCS (buf);
624
rel = GET_RELOC (buf);
626
/* This should not happen. */
628
if ((*reloc_symbol_deleted_p) (buf - ehbuf, cookie))
631
/* This is a FDE against discarded section, it should
633
new_size -= hdr.length + 4;
634
sec_info->entry[sec_info->count].removed = 1;
639
&& (((cie.fde_encoding & 0xf0) == DW_EH_PE_absptr
640
&& cie.make_relative == 0)
641
|| (cie.fde_encoding & 0xf0) == DW_EH_PE_aligned))
643
/* If shared library uses absolute pointers
644
which we cannot turn into PC relative,
645
don't create the binary search table,
646
since it is affected by runtime relocations. */
647
hdr_info->table = false;
650
hdr_info->fde_count++;
653
if (cie.lsda_encoding != DW_EH_PE_omit)
658
buf += 2 * get_DW_EH_PE_width (cie.fde_encoding, ptr_size);
659
if (cie.augmentation[0] == 'z')
660
read_uleb128 (dummy, buf);
661
/* If some new augmentation data is added before LSDA
662
in FDE augmentation area, this need to be adjusted. */
663
sec_info->entry[sec_info->count].lsda_offset = (buf - aug);
665
buf = last_fde + 4 + hdr.length;
669
sec_info->entry[sec_info->count].fde_encoding = cie.fde_encoding;
670
sec_info->entry[sec_info->count].lsda_encoding = cie.lsda_encoding;
674
elf_section_data (sec)->sec_info = sec_info;
675
elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME;
677
/* Ok, now we can assign new offsets. */
680
for (i = 0; i < sec_info->count; i++)
682
if (! sec_info->entry[i].removed)
684
sec_info->entry[i].new_offset = offset;
685
offset += sec_info->entry[i].size;
686
if (sec_info->entry[i].cie)
689
make_relative = sec_info->entry[i].make_relative;
690
make_lsda_relative = sec_info->entry[i].make_lsda_relative;
694
sec_info->entry[i].make_relative = make_relative;
695
sec_info->entry[i].make_lsda_relative = make_lsda_relative;
696
sec_info->entry[i].per_encoding_relative = 0;
699
else if (sec_info->entry[i].cie && sec_info->entry[i].sec == sec)
701
/* Need to adjust new_offset too. */
702
BFD_ASSERT (sec_info->entry[last_cie_ndx].offset
703
== sec_info->entry[i].new_offset);
704
sec_info->entry[i].new_offset
705
= sec_info->entry[last_cie_ndx].new_offset;
708
if (hdr_info->last_cie_sec == sec)
710
BFD_ASSERT (sec_info->entry[last_cie_ndx].offset
711
== hdr_info->last_cie_offset);
712
hdr_info->last_cie_offset = sec_info->entry[last_cie_ndx].new_offset;
715
/* FIXME: Currently it is not possible to shrink sections to zero size at
716
this point, so build a fake minimal CIE. */
720
/* Shrink the sec as needed. */
721
sec->_cooked_size = new_size;
722
if (sec->_cooked_size == 0)
723
sec->flags |= SEC_EXCLUDE;
726
return new_size != sec->_raw_size;
733
hdr_info->table = false;
734
hdr_info->last_cie.hdr.length = 0;
738
/* This function is called for .eh_frame_hdr section after
739
_bfd_elf_discard_section_eh_frame has been called on all .eh_frame
740
input sections. It finalizes the size of .eh_frame_hdr section. */
743
_bfd_elf_discard_section_eh_frame_hdr (abfd, info, sec)
745
struct bfd_link_info *info;
748
struct eh_frame_hdr_info *hdr_info;
749
unsigned int ptr_size;
751
ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS]
752
== ELFCLASS64) ? 8 : 4;
754
if ((elf_section_data (sec)->sec_info_type
755
!= ELF_INFO_TYPE_EH_FRAME_HDR)
756
|| ! info->eh_frame_hdr)
758
_bfd_strip_section_from_output (info, sec);
762
hdr_info = (struct eh_frame_hdr_info *)
763
elf_section_data (sec)->sec_info;
766
sec->_cooked_size = EH_FRAME_HDR_SIZE;
768
sec->_cooked_size += 4 + hdr_info->fde_count * 8;
770
/* Request program headers to be recalculated. */
771
elf_tdata (abfd)->program_header_size = 0;
772
elf_tdata (abfd)->eh_frame_hdr = true;
776
/* This function is called from size_dynamic_sections.
777
It needs to decide whether .eh_frame_hdr should be output or not,
778
because later on it is too late for calling _bfd_strip_section_from_output,
779
since dynamic symbol table has been sized. */
782
_bfd_elf_maybe_strip_eh_frame_hdr (info)
783
struct bfd_link_info *info;
787
struct eh_frame_hdr_info *hdr_info;
789
sec = bfd_get_section_by_name (elf_hash_table (info)->dynobj, ".eh_frame_hdr");
790
if (sec == NULL || bfd_is_abs_section (sec->output_section))
794
= bfd_zmalloc (sizeof (struct eh_frame_hdr_info));
795
if (hdr_info == NULL)
798
elf_section_data (sec)->sec_info = hdr_info;
799
elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME_HDR;
802
if (info->eh_frame_hdr)
803
for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
805
/* Count only sections which have at least a single CIE or FDE.
806
There cannot be any CIE or FDE <= 8 bytes. */
807
o = bfd_get_section_by_name (abfd, ".eh_frame");
808
if (o && o->_raw_size > 8 && !bfd_is_abs_section (o->output_section))
814
_bfd_strip_section_from_output (info, sec);
815
hdr_info->strip = true;
818
hdr_info->table = true;
822
/* Adjust an address in the .eh_frame section. Given OFFSET within
823
SEC, this returns the new offset in the adjusted .eh_frame section,
824
or -1 if the address refers to a CIE/FDE which has been removed
825
or to offset with dynamic relocation which is no longer needed. */
828
_bfd_elf_eh_frame_section_offset (output_bfd, sec, offset)
829
bfd *output_bfd ATTRIBUTE_UNUSED;
833
struct eh_frame_sec_info *sec_info;
834
unsigned int lo, hi, mid;
836
if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
838
sec_info = (struct eh_frame_sec_info *)
839
elf_section_data (sec)->sec_info;
841
if (offset >= sec->_raw_size)
842
return offset - (sec->_cooked_size - sec->_raw_size);
845
hi = sec_info->count;
850
if (offset < sec_info->entry[mid].offset)
853
>= sec_info->entry[mid].offset + sec_info->entry[mid].size)
859
BFD_ASSERT (lo < hi);
861
/* FDE or CIE was removed. */
862
if (sec_info->entry[mid].removed)
865
/* If converting to DW_EH_PE_pcrel, there will be no need for run-time
866
relocation against FDE's initial_location field. */
867
if (sec_info->entry[mid].make_relative
868
&& ! sec_info->entry[mid].cie
869
&& offset == sec_info->entry[mid].offset + 8)
872
/* If converting LSDA pointers to DW_EH_PE_pcrel, there will be no need
873
for run-time relocation against LSDA field. */
874
if (sec_info->entry[mid].make_lsda_relative
875
&& ! sec_info->entry[mid].cie
877
== (sec_info->entry[mid].offset + 8
878
+ sec_info->entry[mid].lsda_offset)))
881
return (offset + sec_info->entry[mid].new_offset
882
- sec_info->entry[mid].offset);
885
/* Write out .eh_frame section. This is called with the relocated
889
_bfd_elf_write_section_eh_frame (abfd, sec, ehdrsec, contents)
891
asection *sec, *ehdrsec;
894
struct eh_frame_sec_info *sec_info;
895
struct eh_frame_hdr_info *hdr_info;
898
unsigned int leb128_tmp;
899
unsigned int cie_offset = 0;
900
unsigned int ptr_size;
902
ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS]
903
== ELFCLASS64) ? 8 : 4;
905
if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
906
return bfd_set_section_contents (abfd, sec->output_section,
908
(file_ptr) sec->output_offset,
910
sec_info = (struct eh_frame_sec_info *)
911
elf_section_data (sec)->sec_info;
914
&& (elf_section_data (ehdrsec)->sec_info_type
915
== ELF_INFO_TYPE_EH_FRAME_HDR))
917
hdr_info = (struct eh_frame_hdr_info *)
918
elf_section_data (ehdrsec)->sec_info;
919
if (hdr_info->table && hdr_info->array == NULL)
921
= bfd_malloc (hdr_info->fde_count * sizeof(*hdr_info->array));
922
if (hdr_info->array == NULL)
927
for (i = 0; i < sec_info->count; ++i)
929
if (sec_info->entry[i].removed)
931
if (sec_info->entry[i].cie)
933
/* If CIE is removed due to no remaining FDEs referencing it
934
and there were no CIEs kept before it, sec_info->entry[i].sec
936
if (sec_info->entry[i].sec == NULL)
940
cie_offset = sec_info->entry[i].new_offset;
941
cie_offset += (sec_info->entry[i].sec->output_section->vma
942
+ sec_info->entry[i].sec->output_offset
943
- sec->output_section->vma
944
- sec->output_offset);
950
if (sec_info->entry[i].cie)
953
cie_offset = sec_info->entry[i].new_offset;
954
if (sec_info->entry[i].make_relative
955
|| sec_info->entry[i].make_lsda_relative
956
|| sec_info->entry[i].per_encoding_relative)
960
unsigned int dummy, per_width, per_encoding;
962
/* Need to find 'R' or 'L' augmentation's argument and modify
964
action = (sec_info->entry[i].make_relative ? 1 : 0)
965
| (sec_info->entry[i].make_lsda_relative ? 2 : 0)
966
| (sec_info->entry[i].per_encoding_relative ? 4 : 0);
967
buf = contents + sec_info->entry[i].offset;
968
/* Skip length, id and version. */
971
buf = strchr (buf, '\0') + 1;
972
read_uleb128 (dummy, buf);
973
read_sleb128 (dummy, buf);
974
read_uleb128 (dummy, buf);
977
read_uleb128 (dummy, buf);
987
BFD_ASSERT (*buf == sec_info->entry[i].lsda_encoding);
988
*buf |= DW_EH_PE_pcrel;
994
per_encoding = *buf++;
995
per_width = get_DW_EH_PE_width (per_encoding,
997
BFD_ASSERT (per_width != 0);
998
BFD_ASSERT (((per_encoding & 0x70) == DW_EH_PE_pcrel)
999
== sec_info->entry[i].per_encoding_relative);
1000
if ((per_encoding & 0xf0) == DW_EH_PE_aligned)
1002
+ ((buf - contents + per_width - 1)
1003
& ~((bfd_size_type) per_width - 1)));
1008
value = read_value (abfd, buf, per_width);
1009
value += (sec_info->entry[i].offset
1010
- sec_info->entry[i].new_offset);
1011
write_value (abfd, buf, value, per_width);
1019
BFD_ASSERT (*buf == sec_info->entry[i].fde_encoding);
1020
*buf |= DW_EH_PE_pcrel;
1030
else if (sec_info->entry[i].size > 4)
1033
bfd_vma value = 0, address;
1036
buf = contents + sec_info->entry[i].offset;
1040
sec_info->entry[i].new_offset + 4 - cie_offset, buf);
1042
width = get_DW_EH_PE_width (sec_info->entry[i].fde_encoding,
1044
address = value = read_value (abfd, buf, width);
1047
switch (sec_info->entry[i].fde_encoding & 0xf0)
1049
case DW_EH_PE_indirect:
1050
case DW_EH_PE_textrel:
1051
BFD_ASSERT (hdr_info == NULL);
1053
case DW_EH_PE_datarel:
1055
asection *got = bfd_get_section_by_name (abfd, ".got");
1057
BFD_ASSERT (got != NULL);
1058
address += got->vma;
1061
case DW_EH_PE_pcrel:
1062
value += (sec_info->entry[i].offset
1063
- sec_info->entry[i].new_offset);
1064
address += (sec->output_section->vma + sec->output_offset
1065
+ sec_info->entry[i].offset + 8);
1068
if (sec_info->entry[i].make_relative)
1069
value -= (sec->output_section->vma + sec->output_offset
1070
+ sec_info->entry[i].new_offset + 8);
1071
write_value (abfd, buf, value, width);
1076
hdr_info->array[hdr_info->array_count].initial_loc = address;
1077
hdr_info->array[hdr_info->array_count++].fde
1078
= (sec->output_section->vma + sec->output_offset
1079
+ sec_info->entry[i].new_offset);
1082
if ((sec_info->entry[i].lsda_encoding & 0xf0) == DW_EH_PE_pcrel
1083
|| sec_info->entry[i].make_lsda_relative)
1085
buf += sec_info->entry[i].lsda_offset;
1086
width = get_DW_EH_PE_width (sec_info->entry[i].lsda_encoding,
1088
value = read_value (abfd, buf, width);
1091
if ((sec_info->entry[i].lsda_encoding & 0xf0)
1093
value += (sec_info->entry[i].offset
1094
- sec_info->entry[i].new_offset);
1095
else if (sec_info->entry[i].make_lsda_relative)
1096
value -= (sec->output_section->vma + sec->output_offset
1097
+ sec_info->entry[i].new_offset + 8
1098
+ sec_info->entry[i].lsda_offset);
1099
write_value (abfd, buf, value, width);
1104
/* Terminating FDE must be at the end of .eh_frame section only. */
1105
BFD_ASSERT (i == sec_info->count - 1);
1107
BFD_ASSERT (p == contents + sec_info->entry[i].new_offset);
1108
memmove (p, contents + sec_info->entry[i].offset,
1109
sec_info->entry[i].size);
1110
p += sec_info->entry[i].size;
1113
/* FIXME: Once _bfd_elf_discard_section_eh_frame will be able to
1114
shrink sections to zero size, this won't be needed any more. */
1115
if (p == contents && sec->_cooked_size == 16)
1117
bfd_put_32 (abfd, 12, p); /* Fake CIE length */
1118
bfd_put_32 (abfd, 0, p + 4); /* Fake CIE id */
1119
p[8] = 1; /* Fake CIE version */
1120
memset (p + 9, 0, 7); /* Fake CIE augmentation, 3xleb128
1121
and 3xDW_CFA_nop as pad */
1125
BFD_ASSERT ((bfd_size_type) (p - contents) == sec->_cooked_size);
1127
return bfd_set_section_contents (abfd, sec->output_section,
1128
contents, (file_ptr) sec->output_offset,
1132
/* Helper function used to sort .eh_frame_hdr search table by increasing
1133
VMA of FDE initial location. */
1140
struct eh_frame_array_ent *p = (struct eh_frame_array_ent *) a;
1141
struct eh_frame_array_ent *q = (struct eh_frame_array_ent *) b;
1142
if (p->initial_loc > q->initial_loc)
1144
if (p->initial_loc < q->initial_loc)
1149
/* Write out .eh_frame_hdr section. This must be called after
1150
_bfd_elf_write_section_eh_frame has been called on all input
1152
.eh_frame_hdr format:
1153
ubyte version (currently 1)
1154
ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of
1156
ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count
1157
number (or DW_EH_PE_omit if there is no
1158
binary search table computed))
1159
ubyte table_enc (DW_EH_PE_* encoding of binary search table,
1160
or DW_EH_PE_omit if not present.
1161
DW_EH_PE_datarel is using address of
1162
.eh_frame_hdr section start as base)
1163
[encoded] eh_frame_ptr (pointer to start of .eh_frame section)
1164
optionally followed by:
1165
[encoded] fde_count (total number of FDEs in .eh_frame section)
1166
fde_count x [encoded] initial_loc, fde
1167
(array of encoded pairs containing
1168
FDE initial_location field and FDE address,
1169
sorted by increasing initial_loc) */
1172
_bfd_elf_write_section_eh_frame_hdr (abfd, sec)
1176
struct eh_frame_hdr_info *hdr_info;
1177
unsigned int ptr_size;
1179
asection *eh_frame_sec;
1182
ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS]
1183
== ELFCLASS64) ? 8 : 4;
1185
BFD_ASSERT (elf_section_data (sec)->sec_info_type
1186
== ELF_INFO_TYPE_EH_FRAME_HDR);
1187
hdr_info = (struct eh_frame_hdr_info *)
1188
elf_section_data (sec)->sec_info;
1189
if (hdr_info->strip)
1192
size = EH_FRAME_HDR_SIZE;
1193
if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
1194
size += 4 + hdr_info->fde_count * 8;
1195
contents = bfd_malloc (size);
1196
if (contents == NULL)
1199
eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame");
1200
if (eh_frame_sec == NULL)
1203
memset (contents, 0, EH_FRAME_HDR_SIZE);
1204
contents[0] = 1; /* Version */
1205
contents[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4; /* .eh_frame offset */
1206
if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
1208
contents[2] = DW_EH_PE_udata4; /* FDE count encoding */
1209
contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4; /* search table enc */
1213
contents[2] = DW_EH_PE_omit;
1214
contents[3] = DW_EH_PE_omit;
1216
bfd_put_32 (abfd, eh_frame_sec->vma - sec->output_section->vma - 4,
1218
if (contents[2] != DW_EH_PE_omit)
1222
bfd_put_32 (abfd, hdr_info->fde_count, contents + EH_FRAME_HDR_SIZE);
1223
qsort (hdr_info->array, hdr_info->fde_count, sizeof (*hdr_info->array),
1225
for (i = 0; i < hdr_info->fde_count; i++)
1228
hdr_info->array[i].initial_loc
1229
- sec->output_section->vma,
1230
contents + EH_FRAME_HDR_SIZE + i * 8 + 4);
1232
hdr_info->array[i].fde - sec->output_section->vma,
1233
contents + EH_FRAME_HDR_SIZE + i * 8 + 8);
1237
return bfd_set_section_contents (abfd, sec->output_section,
1238
contents, (file_ptr) sec->output_offset,