1219 lines
33 KiB
C
1219 lines
33 KiB
C
/* .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 "bfd.h"
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#include "sysdep.h"
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#include "libbfd.h"
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#include "elf-bfd.h"
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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
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{
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unsigned int length;
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unsigned int id;
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};
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struct cie
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{
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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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int data_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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};
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struct eh_cie_fde
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{
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unsigned int offset;
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unsigned int size;
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asection *sec;
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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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};
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struct eh_frame_sec_info
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{
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unsigned int count;
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unsigned int alloced;
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struct eh_cie_fde entry[1];
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};
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struct eh_frame_array_ent
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{
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bfd_vma initial_loc;
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bfd_vma fde;
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};
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struct eh_frame_hdr_info
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{
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struct cie last_cie;
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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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boolean table;
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boolean strip;
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};
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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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PARAMS ((int, int));
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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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static bfd_vma
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read_unsigned_leb128 (abfd, buf, bytes_read_ptr)
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bfd *abfd ATTRIBUTE_UNUSED;
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char *buf;
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unsigned int *bytes_read_ptr;
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{
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bfd_vma result;
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unsigned int num_read;
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int shift;
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unsigned char byte;
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result = 0;
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shift = 0;
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num_read = 0;
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do
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{
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byte = bfd_get_8 (abfd, (bfd_byte *) buf);
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buf ++;
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num_read ++;
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result |= (((bfd_vma) byte & 0x7f) << shift);
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shift += 7;
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}
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while (byte & 0x80);
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* bytes_read_ptr = num_read;
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return result;
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}
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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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char *buf;
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unsigned int * bytes_read_ptr;
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{
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bfd_vma result;
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int shift;
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int num_read;
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unsigned char byte;
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result = 0;
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shift = 0;
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num_read = 0;
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do
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{
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byte = bfd_get_8 (abfd, (bfd_byte *) buf);
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buf ++;
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num_read ++;
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result |= (((bfd_vma) byte & 0x7f) << shift);
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shift += 7;
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}
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while (byte & 0x80);
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if (byte & 0x40)
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result |= (((bfd_vma) -1) << (shift - 7)) << 7;
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* bytes_read_ptr = num_read;
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return result;
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}
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#define read_uleb128(VAR, BUF) \
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do \
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{ \
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(VAR) = read_unsigned_leb128 (abfd, buf, &leb128_tmp); \
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(BUF) += leb128_tmp; \
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} \
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while (0)
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#define read_sleb128(VAR, BUF) \
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do \
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{ \
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(VAR) = read_signed_leb128 (abfd, buf, &leb128_tmp); \
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(BUF) += leb128_tmp; \
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} \
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while (0)
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/* Return 0 if either encoding is variable width, or not yet known to bfd. */
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static
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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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{
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/* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame
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was added to bfd. */
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if ((encoding & 0x60) == 0x60)
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return 0;
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switch (encoding & 7)
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{
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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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default:
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break;
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}
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return 0;
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}
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/* Read a width sized value from memory. */
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static bfd_vma
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read_value (abfd, buf, width)
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bfd *abfd;
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bfd_byte *buf;
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int width;
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{
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bfd_vma value;
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switch (width)
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{
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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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}
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return value;
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}
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/* Store a width sized value to memory. */
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static void
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write_value (abfd, buf, value, width)
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bfd *abfd;
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bfd_byte *buf;
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bfd_vma value;
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int width;
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{
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switch (width)
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{
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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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}
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}
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/* Return zero if C1 and C2 CIEs can be merged. */
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static
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int cie_compare (c1, c2)
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struct cie *c1, *c2;
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{
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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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return 0;
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return 1;
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}
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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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deleted. */
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boolean
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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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bfd *abfd;
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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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{
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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 cie cie;
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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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{
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/* This file does not contain .eh_frame information. */
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return false;
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}
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if ((sec->output_section != NULL
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&& bfd_is_abs_section (sec->output_section)))
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{
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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. */
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return false;
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}
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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 (ehbuf == NULL)
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goto free_no_table;
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if (! bfd_get_section_contents (abfd, sec, ehbuf, (bfd_vma) 0,
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sec->_raw_size))
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goto free_no_table;
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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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{
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/* Empty .eh_frame section. */
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free (ehbuf);
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return false;
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}
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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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goto free_no_table;
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ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS]
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== ELFCLASS64) ? 8 : 4;
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buf = ehbuf;
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last_cie = NULL;
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last_cie_ndx = 0;
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memset (&cie, 0, sizeof (cie));
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cie_usage_count = 0;
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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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goto free_no_table;
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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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goto free_no_table
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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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cookie->rel++
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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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for (;;)
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{
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unsigned char *aug;
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if (sec_info->count == sec_info->alloced)
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{
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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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goto free_no_table;
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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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}
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last_fde = buf;
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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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else
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{
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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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goto free_no_table;
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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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goto free_no_table;
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buf += 4;
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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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goto free_no_table;
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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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|
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if (hdr.length == 0)
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{
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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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goto free_no_table;
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ENSURE_NO_RELOCS (buf);
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sec_info->count++;
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/* Now just finish last encountered CIE processing and break
|
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the loop. */
|
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hdr.id = (unsigned int) -1;
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}
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else
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{
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hdr.id = bfd_get_32 (abfd, buf);
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buf += 4;
|
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if (hdr.id == (unsigned int) -1)
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goto free_no_table;
|
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}
|
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}
|
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|
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if (hdr.id == 0 || hdr.id == (unsigned int) -1)
|
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{
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unsigned int initial_insn_length;
|
|
|
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/* CIE */
|
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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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that. */
|
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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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{
|
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new_size -= cie.hdr.length + 4;
|
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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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}
|
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else
|
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{
|
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hdr_info->last_cie = cie;
|
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hdr_info->last_cie_sec = sec;
|
|
hdr_info->last_cie_offset = last_cie - ehbuf;
|
|
sec_info->entry[last_cie_ndx].make_relative
|
|
= cie.make_relative;
|
|
sec_info->entry[last_cie_ndx].make_lsda_relative
|
|
= cie.make_lsda_relative;
|
|
}
|
|
}
|
|
|
|
if (hdr.id == (unsigned int) -1)
|
|
break;
|
|
|
|
last_cie_ndx = sec_info->count;
|
|
sec_info->entry[sec_info->count].cie = 1;
|
|
|
|
cie_usage_count = 0;
|
|
memset (&cie, 0, sizeof (cie));
|
|
cie.hdr = hdr;
|
|
cie.version = *buf++;
|
|
|
|
/* Cannot handle unknown versions. */
|
|
if (cie.version != 1)
|
|
goto free_no_table;
|
|
if (strlen (buf) > sizeof (cie.augmentation) - 1)
|
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goto free_no_table;
|
|
|
|
strcpy (cie.augmentation, buf);
|
|
buf = strchr (buf, '\0') + 1;
|
|
ENSURE_NO_RELOCS (buf);
|
|
if (buf[0] == 'e' && buf[1] == 'h')
|
|
{
|
|
/* GCC < 3.0 .eh_frame CIE */
|
|
/* We cannot merge "eh" CIEs because __EXCEPTION_TABLE__
|
|
is private to each CIE, so we don't need it for anything.
|
|
Just skip it. */
|
|
buf += ptr_size;
|
|
SKIP_RELOCS (buf);
|
|
}
|
|
read_uleb128 (cie.code_align, buf);
|
|
read_sleb128 (cie.data_align, buf);
|
|
read_uleb128 (cie.ra_column, buf);
|
|
ENSURE_NO_RELOCS (buf);
|
|
cie.lsda_encoding = DW_EH_PE_omit;
|
|
cie.fde_encoding = DW_EH_PE_omit;
|
|
cie.per_encoding = DW_EH_PE_omit;
|
|
aug = cie.augmentation;
|
|
if (aug[0] != 'e' || aug[1] != 'h')
|
|
{
|
|
if (*aug == 'z')
|
|
{
|
|
aug++;
|
|
read_uleb128 (cie.augmentation_size, buf);
|
|
ENSURE_NO_RELOCS (buf);
|
|
}
|
|
|
|
while (*aug != '\0')
|
|
switch (*aug++)
|
|
{
|
|
case 'L':
|
|
cie.lsda_encoding = *buf++;
|
|
ENSURE_NO_RELOCS (buf);
|
|
if (get_DW_EH_PE_width (cie.lsda_encoding, ptr_size) == 0)
|
|
goto free_no_table;
|
|
break;
|
|
case 'R':
|
|
cie.fde_encoding = *buf++;
|
|
ENSURE_NO_RELOCS (buf);
|
|
if (get_DW_EH_PE_width (cie.fde_encoding, ptr_size) == 0)
|
|
goto free_no_table;
|
|
break;
|
|
case 'P':
|
|
{
|
|
int per_width;
|
|
|
|
cie.per_encoding = *buf++;
|
|
per_width = get_DW_EH_PE_width (cie.per_encoding,
|
|
ptr_size);
|
|
if (per_width == 0)
|
|
goto free_no_table;
|
|
if ((cie.per_encoding & 0xf0) == DW_EH_PE_aligned)
|
|
buf = (ehbuf
|
|
+ ((buf - ehbuf + per_width - 1)
|
|
& ~((bfd_size_type) per_width - 1)));
|
|
ENSURE_NO_RELOCS (buf);
|
|
rel = GET_RELOC (buf);
|
|
/* Ensure we have a reloc here, against
|
|
a global symbol. */
|
|
if (rel != NULL)
|
|
{
|
|
unsigned long r_symndx;
|
|
|
|
#ifdef BFD64
|
|
if (ptr_size == 8)
|
|
r_symndx = ELF64_R_SYM (cookie->rel->r_info);
|
|
else
|
|
#endif
|
|
r_symndx = ELF32_R_SYM (cookie->rel->r_info);
|
|
if (r_symndx >= cookie->locsymcount)
|
|
{
|
|
struct elf_link_hash_entry *h;
|
|
|
|
r_symndx -= cookie->extsymoff;
|
|
h = cookie->sym_hashes[r_symndx];
|
|
|
|
while (h->root.type == bfd_link_hash_indirect
|
|
|| h->root.type == bfd_link_hash_warning)
|
|
h = (struct elf_link_hash_entry *)
|
|
h->root.u.i.link;
|
|
|
|
cie.personality = h;
|
|
}
|
|
cookie->rel++;
|
|
}
|
|
buf += per_width;
|
|
}
|
|
break;
|
|
default:
|
|
/* Unrecognized augmentation. Better bail out. */
|
|
goto free_no_table;
|
|
}
|
|
}
|
|
|
|
/* For shared libraries, try to get rid of as many RELATIVE relocs
|
|
as possible. */
|
|
if (info->shared
|
|
&& (cie.fde_encoding & 0xf0) == DW_EH_PE_absptr)
|
|
cie.make_relative = 1;
|
|
|
|
if (info->shared
|
|
&& (cie.lsda_encoding & 0xf0) == DW_EH_PE_absptr)
|
|
cie.make_lsda_relative = 1;
|
|
|
|
/* If FDE encoding was not specified, it defaults to
|
|
DW_EH_absptr. */
|
|
if (cie.fde_encoding == DW_EH_PE_omit)
|
|
cie.fde_encoding = DW_EH_PE_absptr;
|
|
|
|
initial_insn_length = cie.hdr.length - (buf - last_fde - 4);
|
|
if (initial_insn_length <= 50)
|
|
{
|
|
cie.initial_insn_length = initial_insn_length;
|
|
memcpy (cie.initial_instructions, buf, initial_insn_length);
|
|
}
|
|
buf += initial_insn_length;
|
|
ENSURE_NO_RELOCS (buf);
|
|
last_cie = last_fde;
|
|
}
|
|
else
|
|
{
|
|
/* Ensure this FDE uses the last CIE encountered. */
|
|
if (last_cie == NULL
|
|
|| hdr.id != (unsigned int) (buf - 4 - last_cie))
|
|
goto free_no_table;
|
|
|
|
ENSURE_NO_RELOCS (buf);
|
|
rel = GET_RELOC (buf);
|
|
if (rel == NULL)
|
|
/* This should not happen. */
|
|
goto free_no_table;
|
|
if ((*reloc_symbol_deleted_p) (buf - ehbuf, cookie))
|
|
{
|
|
cookie->rel = rel;
|
|
/* This is a FDE against discarded section, it should
|
|
be deleted. */
|
|
new_size -= hdr.length + 4;
|
|
sec_info->entry[sec_info->count].removed = 1;
|
|
}
|
|
else
|
|
{
|
|
if (info->shared
|
|
&& (cie.fde_encoding & 0xf0) == DW_EH_PE_absptr
|
|
&& cie.make_relative == 0)
|
|
{
|
|
/* If shared library uses absolute pointers
|
|
which we cannot turn into PC relative,
|
|
don't create the binary search table,
|
|
since it is affected by runtime relocations. */
|
|
hdr_info->table = false;
|
|
}
|
|
cie_usage_count++;
|
|
hdr_info->fde_count++;
|
|
}
|
|
cookie->rel = rel;
|
|
if (cie.lsda_encoding != DW_EH_PE_omit)
|
|
{
|
|
unsigned int dummy;
|
|
|
|
aug = buf;
|
|
buf += 2 * get_DW_EH_PE_width (cie.fde_encoding, ptr_size);
|
|
if (cie.augmentation[0] == 'z')
|
|
read_uleb128 (dummy, buf);
|
|
/* If some new augmentation data is added before LSDA
|
|
in FDE augmentation area, this need to be adjusted. */
|
|
sec_info->entry[sec_info->count].lsda_offset = (buf - aug);
|
|
}
|
|
buf = last_fde + 4 + hdr.length;
|
|
SKIP_RELOCS (buf);
|
|
}
|
|
|
|
sec_info->entry[sec_info->count].fde_encoding = cie.fde_encoding;
|
|
sec_info->entry[sec_info->count].lsda_encoding = cie.lsda_encoding;
|
|
sec_info->count++;
|
|
}
|
|
|
|
elf_section_data (sec)->sec_info = sec_info;
|
|
elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME;
|
|
|
|
/* Ok, now we can assign new offsets. */
|
|
offset = 0;
|
|
last_cie_ndx = 0;
|
|
for (i = 0; i < sec_info->count; i++)
|
|
{
|
|
if (! sec_info->entry[i].removed)
|
|
{
|
|
sec_info->entry[i].new_offset = offset;
|
|
offset += sec_info->entry[i].size;
|
|
if (sec_info->entry[i].cie)
|
|
{
|
|
last_cie_ndx = i;
|
|
make_relative = sec_info->entry[i].make_relative;
|
|
make_lsda_relative = sec_info->entry[i].make_lsda_relative;
|
|
}
|
|
else
|
|
{
|
|
sec_info->entry[i].make_relative = make_relative;
|
|
sec_info->entry[i].make_lsda_relative = make_lsda_relative;
|
|
}
|
|
}
|
|
else if (sec_info->entry[i].cie && sec_info->entry[i].sec == sec)
|
|
{
|
|
/* Need to adjust new_offset too. */
|
|
BFD_ASSERT (sec_info->entry[last_cie_ndx].offset
|
|
== sec_info->entry[i].new_offset);
|
|
sec_info->entry[i].new_offset
|
|
= sec_info->entry[last_cie_ndx].new_offset;
|
|
}
|
|
}
|
|
if (hdr_info->last_cie_sec == sec)
|
|
{
|
|
BFD_ASSERT (sec_info->entry[last_cie_ndx].offset
|
|
== hdr_info->last_cie_offset);
|
|
hdr_info->last_cie_offset = sec_info->entry[last_cie_ndx].new_offset;
|
|
}
|
|
|
|
/* FIXME: Currently it is not possible to shrink sections to zero size at
|
|
this point, so build a fake minimal CIE. */
|
|
if (new_size == 0)
|
|
new_size = 16;
|
|
|
|
/* Shrink the sec as needed. */
|
|
sec->_cooked_size = new_size;
|
|
if (sec->_cooked_size == 0)
|
|
sec->flags |= SEC_EXCLUDE;
|
|
|
|
free (ehbuf);
|
|
return new_size != sec->_raw_size;
|
|
|
|
free_no_table:
|
|
if (ehbuf)
|
|
free (ehbuf);
|
|
if (sec_info)
|
|
free (sec_info);
|
|
hdr_info->table = false;
|
|
hdr_info->last_cie.hdr.length = 0;
|
|
return false;
|
|
}
|
|
|
|
/* This function is called for .eh_frame_hdr section after
|
|
_bfd_elf_discard_section_eh_frame has been called on all .eh_frame
|
|
input sections. It finalizes the size of .eh_frame_hdr section. */
|
|
|
|
boolean
|
|
_bfd_elf_discard_section_eh_frame_hdr (abfd, info, sec)
|
|
bfd *abfd;
|
|
struct bfd_link_info *info;
|
|
asection *sec;
|
|
{
|
|
struct eh_frame_hdr_info *hdr_info;
|
|
unsigned int ptr_size;
|
|
|
|
ptr_size = (elf_elfheader (abfd)->e_ident[EI_CLASS]
|
|
== ELFCLASS64) ? 8 : 4;
|
|
|
|
if ((elf_section_data (sec)->sec_info_type
|
|
!= ELF_INFO_TYPE_EH_FRAME_HDR)
|
|
|| ! info->eh_frame_hdr)
|
|
{
|
|
_bfd_strip_section_from_output (info, sec);
|
|
return false;
|
|
}
|
|
|
|
hdr_info = (struct eh_frame_hdr_info *)
|
|
elf_section_data (sec)->sec_info;
|
|
if (hdr_info->strip)
|
|
return false;
|
|
sec->_cooked_size = EH_FRAME_HDR_SIZE;
|
|
if (hdr_info->table)
|
|
sec->_cooked_size += 4 + hdr_info->fde_count * 8;
|
|
|
|
/* Request program headers to be recalculated. */
|
|
elf_tdata (abfd)->program_header_size = 0;
|
|
elf_tdata (abfd)->eh_frame_hdr = true;
|
|
return true;
|
|
}
|
|
|
|
/* This function is called from size_dynamic_sections.
|
|
It needs to decide whether .eh_frame_hdr should be output or not,
|
|
because later on it is too late for calling _bfd_strip_section_from_output,
|
|
since dynamic symbol table has been sized. */
|
|
|
|
boolean
|
|
_bfd_elf_maybe_strip_eh_frame_hdr (info)
|
|
struct bfd_link_info *info;
|
|
{
|
|
asection *sec, *o;
|
|
bfd *abfd;
|
|
struct eh_frame_hdr_info *hdr_info;
|
|
|
|
sec = bfd_get_section_by_name (elf_hash_table (info)->dynobj, ".eh_frame_hdr");
|
|
if (sec == NULL)
|
|
return true;
|
|
|
|
hdr_info
|
|
= bfd_zmalloc (sizeof (struct eh_frame_hdr_info));
|
|
if (hdr_info == NULL)
|
|
return false;
|
|
|
|
elf_section_data (sec)->sec_info = hdr_info;
|
|
elf_section_data (sec)->sec_info_type = ELF_INFO_TYPE_EH_FRAME_HDR;
|
|
|
|
abfd = NULL;
|
|
if (info->eh_frame_hdr)
|
|
for (abfd = info->input_bfds; abfd != NULL; abfd = abfd->link_next)
|
|
{
|
|
/* Count only sections which have at least a single CIE or FDE.
|
|
There cannot be any CIE or FDE <= 8 bytes. */
|
|
o = bfd_get_section_by_name (abfd, ".eh_frame");
|
|
if (o && o->_raw_size > 8)
|
|
break;
|
|
}
|
|
|
|
if (abfd == NULL)
|
|
{
|
|
_bfd_strip_section_from_output (info, sec);
|
|
hdr_info->strip = true;
|
|
}
|
|
else
|
|
hdr_info->table = true;
|
|
return true;
|
|
}
|
|
|
|
/* Adjust an address in the .eh_frame section. Given OFFSET within
|
|
SEC, this returns the new offset in the adjusted .eh_frame section,
|
|
or -1 if the address refers to a CIE/FDE which has been removed
|
|
or to offset with dynamic relocation which is no longer needed. */
|
|
|
|
bfd_vma
|
|
_bfd_elf_eh_frame_section_offset (output_bfd, sec, offset)
|
|
bfd *output_bfd ATTRIBUTE_UNUSED;
|
|
asection *sec;
|
|
bfd_vma offset;
|
|
{
|
|
struct eh_frame_sec_info *sec_info;
|
|
unsigned int lo, hi, mid;
|
|
|
|
if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
|
|
return offset;
|
|
sec_info = (struct eh_frame_sec_info *)
|
|
elf_section_data (sec)->sec_info;
|
|
|
|
if (offset >= sec->_raw_size)
|
|
return offset - (sec->_cooked_size - sec->_raw_size);
|
|
|
|
lo = 0;
|
|
hi = sec_info->count;
|
|
mid = 0;
|
|
while (lo < hi)
|
|
{
|
|
mid = (lo + hi) / 2;
|
|
if (offset < sec_info->entry[mid].offset)
|
|
hi = mid;
|
|
else if (offset
|
|
>= sec_info->entry[mid].offset + sec_info->entry[mid].size)
|
|
lo = mid + 1;
|
|
else
|
|
break;
|
|
}
|
|
|
|
BFD_ASSERT (lo < hi);
|
|
|
|
/* FDE or CIE was removed. */
|
|
if (sec_info->entry[mid].removed)
|
|
return (bfd_vma) -1;
|
|
|
|
/* If converting to DW_EH_PE_pcrel, there will be no need for run-time
|
|
relocation against FDE's initial_location field. */
|
|
if (sec_info->entry[mid].make_relative
|
|
&& ! sec_info->entry[mid].cie
|
|
&& offset == sec_info->entry[mid].offset + 8)
|
|
return (bfd_vma) -2;
|
|
|
|
/* If converting LSDA pointers to DW_EH_PE_pcrel, there will be no need
|
|
for run-time relocation against LSDA field. */
|
|
if (sec_info->entry[mid].make_lsda_relative
|
|
&& ! sec_info->entry[mid].cie
|
|
&& (offset
|
|
== (sec_info->entry[mid].offset + 8
|
|
+ sec_info->entry[mid].lsda_offset)))
|
|
return (bfd_vma) -2;
|
|
|
|
return (offset + sec_info->entry[mid].new_offset
|
|
- sec_info->entry[mid].offset);
|
|
}
|
|
|
|
/* Write out .eh_frame section. This is called with the relocated
|
|
contents. */
|
|
|
|
boolean
|
|
_bfd_elf_write_section_eh_frame (abfd, sec, ehdrsec, contents)
|
|
bfd *abfd;
|
|
asection *sec, *ehdrsec;
|
|
bfd_byte *contents;
|
|
{
|
|
struct eh_frame_sec_info *sec_info;
|
|
struct eh_frame_hdr_info *hdr_info;
|
|
unsigned int i;
|
|
bfd_byte *p, *buf;
|
|
unsigned int leb128_tmp;
|
|
unsigned int cie_offset = 0;
|
|
unsigned int ptr_size;
|
|
|
|
ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS]
|
|
== ELFCLASS64) ? 8 : 4;
|
|
|
|
if (elf_section_data (sec)->sec_info_type != ELF_INFO_TYPE_EH_FRAME)
|
|
return bfd_set_section_contents (abfd, sec->output_section,
|
|
contents,
|
|
(file_ptr) sec->output_offset,
|
|
sec->_raw_size);
|
|
sec_info = (struct eh_frame_sec_info *)
|
|
elf_section_data (sec)->sec_info;
|
|
hdr_info = NULL;
|
|
if (ehdrsec
|
|
&& (elf_section_data (ehdrsec)->sec_info_type
|
|
== ELF_INFO_TYPE_EH_FRAME_HDR))
|
|
{
|
|
hdr_info = (struct eh_frame_hdr_info *)
|
|
elf_section_data (ehdrsec)->sec_info;
|
|
if (hdr_info->table && hdr_info->array == NULL)
|
|
hdr_info->array
|
|
= bfd_malloc (hdr_info->fde_count * sizeof(*hdr_info->array));
|
|
if (hdr_info->array == NULL)
|
|
hdr_info = NULL;
|
|
}
|
|
|
|
p = contents;
|
|
for (i = 0; i < sec_info->count; ++i)
|
|
{
|
|
if (sec_info->entry[i].removed)
|
|
{
|
|
if (sec_info->entry[i].cie)
|
|
{
|
|
/* If CIE is removed due to no remaining FDEs referencing it
|
|
and there were no CIEs kept before it, sec_info->entry[i].sec
|
|
will be zero. */
|
|
if (sec_info->entry[i].sec == NULL)
|
|
cie_offset = 0;
|
|
else
|
|
{
|
|
cie_offset = sec_info->entry[i].new_offset;
|
|
cie_offset += (sec_info->entry[i].sec->output_section->vma
|
|
+ sec_info->entry[i].sec->output_offset
|
|
- sec->output_section->vma
|
|
- sec->output_offset);
|
|
}
|
|
}
|
|
continue;
|
|
}
|
|
|
|
if (sec_info->entry[i].cie)
|
|
{
|
|
/* CIE */
|
|
cie_offset = sec_info->entry[i].new_offset;
|
|
if (sec_info->entry[i].make_relative
|
|
|| sec_info->entry[i].make_lsda_relative)
|
|
{
|
|
unsigned char *aug;
|
|
unsigned int action;
|
|
unsigned int dummy, per_width, per_encoding;
|
|
|
|
/* Need to find 'R' or 'L' augmentation's argument and modify
|
|
DW_EH_PE_* value. */
|
|
action = (sec_info->entry[i].make_relative ? 1 : 0)
|
|
| (sec_info->entry[i].make_lsda_relative ? 2 : 0);
|
|
buf = contents + sec_info->entry[i].offset;
|
|
/* Skip length, id and version. */
|
|
buf += 9;
|
|
aug = buf;
|
|
buf = strchr (buf, '\0') + 1;
|
|
read_uleb128 (dummy, buf);
|
|
read_sleb128 (dummy, buf);
|
|
read_uleb128 (dummy, buf);
|
|
if (*aug == 'z')
|
|
{
|
|
read_uleb128 (dummy, buf);
|
|
aug++;
|
|
}
|
|
|
|
while (action)
|
|
switch (*aug++)
|
|
{
|
|
case 'L':
|
|
if (action & 2)
|
|
{
|
|
BFD_ASSERT (*buf == sec_info->entry[i].lsda_encoding);
|
|
*buf |= DW_EH_PE_pcrel;
|
|
action &= ~2;
|
|
}
|
|
buf++;
|
|
break;
|
|
case 'P':
|
|
per_encoding = *buf++;
|
|
per_width = get_DW_EH_PE_width (per_encoding,
|
|
ptr_size);
|
|
BFD_ASSERT (per_width != 0);
|
|
if ((per_encoding & 0xf0) == DW_EH_PE_aligned)
|
|
buf = (contents
|
|
+ ((buf - contents + per_width - 1)
|
|
& ~((bfd_size_type) per_width - 1)));
|
|
buf += per_width;
|
|
break;
|
|
case 'R':
|
|
if (action & 1)
|
|
{
|
|
BFD_ASSERT (*buf == sec_info->entry[i].fde_encoding);
|
|
*buf |= DW_EH_PE_pcrel;
|
|
action &= ~1;
|
|
}
|
|
buf++;
|
|
break;
|
|
default:
|
|
BFD_FAIL ();
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* FDE */
|
|
bfd_vma value = 0, address;
|
|
unsigned int width;
|
|
|
|
buf = contents + sec_info->entry[i].offset;
|
|
/* Skip length. */
|
|
buf += 4;
|
|
bfd_put_32 (abfd,
|
|
sec_info->entry[i].new_offset + 4 - cie_offset, buf);
|
|
buf += 4;
|
|
width = get_DW_EH_PE_width (sec_info->entry[i].fde_encoding,
|
|
ptr_size);
|
|
address = value = read_value (abfd, buf, width);
|
|
if (value)
|
|
{
|
|
switch (sec_info->entry[i].fde_encoding & 0xf0)
|
|
{
|
|
case DW_EH_PE_indirect:
|
|
case DW_EH_PE_textrel:
|
|
BFD_ASSERT (hdr_info == NULL);
|
|
break;
|
|
case DW_EH_PE_datarel:
|
|
{
|
|
asection *got = bfd_get_section_by_name (abfd, ".got");
|
|
|
|
BFD_ASSERT (got != NULL);
|
|
address += got->vma;
|
|
}
|
|
break;
|
|
case DW_EH_PE_pcrel:
|
|
value += (sec_info->entry[i].offset
|
|
- sec_info->entry[i].new_offset);
|
|
address += (sec->output_section->vma + sec->output_offset
|
|
+ sec_info->entry[i].offset + 8);
|
|
break;
|
|
}
|
|
if (sec_info->entry[i].make_relative)
|
|
value -= (sec->output_section->vma + sec->output_offset
|
|
+ sec_info->entry[i].new_offset + 8);
|
|
write_value (abfd, buf, value, width);
|
|
}
|
|
|
|
if (hdr_info)
|
|
{
|
|
hdr_info->array[hdr_info->array_count].initial_loc = address;
|
|
hdr_info->array[hdr_info->array_count++].fde
|
|
= (sec->output_section->vma + sec->output_offset
|
|
+ sec_info->entry[i].new_offset);
|
|
}
|
|
|
|
if ((sec_info->entry[i].lsda_encoding & 0xf0) == DW_EH_PE_pcrel
|
|
|| sec_info->entry[i].make_lsda_relative)
|
|
{
|
|
buf += sec_info->entry[i].lsda_offset;
|
|
width = get_DW_EH_PE_width (sec_info->entry[i].lsda_encoding,
|
|
ptr_size);
|
|
value = read_value (abfd, buf, width);
|
|
if (value)
|
|
{
|
|
if ((sec_info->entry[i].lsda_encoding & 0xf0)
|
|
== DW_EH_PE_pcrel)
|
|
value += (sec_info->entry[i].offset
|
|
- sec_info->entry[i].new_offset);
|
|
else if (sec_info->entry[i].make_lsda_relative)
|
|
value -= (sec->output_section->vma + sec->output_offset
|
|
+ sec_info->entry[i].new_offset + 8
|
|
+ sec_info->entry[i].lsda_offset);
|
|
write_value (abfd, buf, value, width);
|
|
}
|
|
}
|
|
}
|
|
|
|
BFD_ASSERT (p == contents + sec_info->entry[i].new_offset);
|
|
memmove (p, contents + sec_info->entry[i].offset,
|
|
sec_info->entry[i].size);
|
|
p += sec_info->entry[i].size;
|
|
}
|
|
|
|
/* FIXME: Once _bfd_elf_discard_section_eh_frame will be able to
|
|
shrink sections to zero size, this won't be needed any more. */
|
|
if (p == contents && sec->_cooked_size == 16)
|
|
{
|
|
bfd_put_32 (abfd, 12, p); /* Fake CIE length */
|
|
bfd_put_32 (abfd, 0, p + 4); /* Fake CIE id */
|
|
p[8] = 1; /* Fake CIE version */
|
|
memset (p + 9, 0, 7); /* Fake CIE augmentation, 3xleb128
|
|
and 3xDW_CFA_nop as pad */
|
|
p += 16;
|
|
}
|
|
|
|
BFD_ASSERT ((bfd_size_type) (p - contents) == sec->_cooked_size);
|
|
|
|
return bfd_set_section_contents (abfd, sec->output_section,
|
|
contents, (file_ptr) sec->output_offset,
|
|
sec->_cooked_size);
|
|
}
|
|
|
|
/* Helper function used to sort .eh_frame_hdr search table by increasing
|
|
VMA of FDE initial location. */
|
|
|
|
static int
|
|
vma_compare (a, b)
|
|
const PTR a;
|
|
const PTR b;
|
|
{
|
|
struct eh_frame_array_ent *p = (struct eh_frame_array_ent *) a;
|
|
struct eh_frame_array_ent *q = (struct eh_frame_array_ent *) b;
|
|
if (p->initial_loc > q->initial_loc)
|
|
return 1;
|
|
if (p->initial_loc < q->initial_loc)
|
|
return -1;
|
|
return 0;
|
|
}
|
|
|
|
/* Write out .eh_frame_hdr section. This must be called after
|
|
_bfd_elf_write_section_eh_frame has been called on all input
|
|
.eh_frame sections.
|
|
.eh_frame_hdr format:
|
|
ubyte version (currently 1)
|
|
ubyte eh_frame_ptr_enc (DW_EH_PE_* encoding of pointer to start of
|
|
.eh_frame section)
|
|
ubyte fde_count_enc (DW_EH_PE_* encoding of total FDE count
|
|
number (or DW_EH_PE_omit if there is no
|
|
binary search table computed))
|
|
ubyte table_enc (DW_EH_PE_* encoding of binary search table,
|
|
or DW_EH_PE_omit if not present.
|
|
DW_EH_PE_datarel is using address of
|
|
.eh_frame_hdr section start as base)
|
|
[encoded] eh_frame_ptr (pointer to start of .eh_frame section)
|
|
optionally followed by:
|
|
[encoded] fde_count (total number of FDEs in .eh_frame section)
|
|
fde_count x [encoded] initial_loc, fde
|
|
(array of encoded pairs containing
|
|
FDE initial_location field and FDE address,
|
|
sorted by increasing initial_loc) */
|
|
|
|
boolean
|
|
_bfd_elf_write_section_eh_frame_hdr (abfd, sec)
|
|
bfd *abfd;
|
|
asection *sec;
|
|
{
|
|
struct eh_frame_hdr_info *hdr_info;
|
|
unsigned int ptr_size;
|
|
bfd_byte *contents;
|
|
asection *eh_frame_sec;
|
|
bfd_size_type size;
|
|
|
|
ptr_size = (elf_elfheader (sec->owner)->e_ident[EI_CLASS]
|
|
== ELFCLASS64) ? 8 : 4;
|
|
|
|
BFD_ASSERT (elf_section_data (sec)->sec_info_type
|
|
== ELF_INFO_TYPE_EH_FRAME_HDR);
|
|
hdr_info = (struct eh_frame_hdr_info *)
|
|
elf_section_data (sec)->sec_info;
|
|
if (hdr_info->strip)
|
|
return true;
|
|
|
|
size = EH_FRAME_HDR_SIZE;
|
|
if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
|
|
size += 4 + hdr_info->fde_count * 8;
|
|
contents = bfd_malloc (size);
|
|
if (contents == NULL)
|
|
return false;
|
|
|
|
eh_frame_sec = bfd_get_section_by_name (abfd, ".eh_frame");
|
|
if (eh_frame_sec == NULL)
|
|
return false;
|
|
|
|
memset (contents, 0, EH_FRAME_HDR_SIZE);
|
|
contents[0] = 1; /* Version */
|
|
contents[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4; /* .eh_frame offset */
|
|
if (hdr_info->array && hdr_info->array_count == hdr_info->fde_count)
|
|
{
|
|
contents[2] = DW_EH_PE_udata4; /* FDE count encoding */
|
|
contents[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4; /* search table enc */
|
|
}
|
|
else
|
|
{
|
|
contents[2] = DW_EH_PE_omit;
|
|
contents[3] = DW_EH_PE_omit;
|
|
}
|
|
bfd_put_32 (abfd, eh_frame_sec->vma - sec->output_section->vma - 4,
|
|
contents + 4);
|
|
if (contents[2] != DW_EH_PE_omit)
|
|
{
|
|
unsigned int i;
|
|
|
|
bfd_put_32 (abfd, hdr_info->fde_count, contents + EH_FRAME_HDR_SIZE);
|
|
qsort (hdr_info->array, hdr_info->fde_count, sizeof (*hdr_info->array),
|
|
vma_compare);
|
|
for (i = 0; i < hdr_info->fde_count; i++)
|
|
{
|
|
bfd_put_32 (abfd,
|
|
hdr_info->array[i].initial_loc
|
|
- sec->output_section->vma,
|
|
contents + EH_FRAME_HDR_SIZE + i * 8 + 4);
|
|
bfd_put_32 (abfd,
|
|
hdr_info->array[i].fde - sec->output_section->vma,
|
|
contents + EH_FRAME_HDR_SIZE + i * 8 + 8);
|
|
}
|
|
}
|
|
|
|
return bfd_set_section_contents (abfd, sec->output_section,
|
|
contents, (file_ptr) sec->output_offset,
|
|
sec->_cooked_size);
|
|
}
|