source: branches/GNU/src/binutils/bfd/elf-eh-frame.c@ 1467

/* .eh_frame section optimization.
   Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
   Written by Jakub Jelinek <[email protected]>.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "elf/dwarf2.h"

#define EH_FRAME_HDR_SIZE 8

static bfd_vma read_unsigned_leb128
  PARAMS ((bfd *, char *, unsigned int *));
static bfd_signed_vma read_signed_leb128
  PARAMS ((bfd *, char *, unsigned int *));
static int get_DW_EH_PE_width
  PARAMS ((int, int));
static bfd_vma read_value
  PARAMS ((bfd *, bfd_byte *, int, int));
static void write_value
  PARAMS ((bfd *, bfd_byte *, bfd_vma, int));
static int cie_compare
  PARAMS ((struct cie *, struct cie *));
static int vma_compare
  PARAMS ((const PTR, const PTR));

/* Helper function for reading uleb128 encoded data.  */

static bfd_vma
read_unsigned_leb128 (abfd, buf, bytes_read_ptr)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
     unsigned int *bytes_read_ptr;
{
  bfd_vma  result;
  unsigned int  num_read;
  int           shift;
  unsigned char byte;

  result   = 0;
  shift    = 0;
  num_read = 0;
  do
    {
      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
      buf ++;
      num_read ++;
      result |= (((bfd_vma) byte & 0x7f) << shift);
      shift += 7;
    }
  while (byte & 0x80);
  * bytes_read_ptr = num_read;
  return result;
}

/* Helper function for reading sleb128 encoded data.  */

static bfd_signed_vma
read_signed_leb128 (abfd, buf, bytes_read_ptr)
     bfd *abfd ATTRIBUTE_UNUSED;
     char *buf;
     unsigned int * bytes_read_ptr;
{
  bfd_vma       result;
  int           shift;
  int           num_read;
  unsigned char byte;

  result = 0;
  shift = 0;
  num_read = 0;
  do
    {
      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
      buf ++;
      num_read ++;
      result |= (((bfd_vma) byte & 0x7f) << shift);
      shift += 7;
    }
  while (byte & 0x80);
  if (byte & 0x40)
    result |= (((bfd_vma) -1) << (shift - 7)) << 7;
  * bytes_read_ptr = num_read;
  return result;
}

#define read_uleb128(VAR, BUF)                                  \
do                                                              \
  {                                                             \
    (VAR) = read_unsigned_leb128 (abfd, buf, &leb128_tmp);      \
    (BUF) += leb128_tmp;                                        \
  }                                                             \
while (0)

#define read_sleb128(VAR, BUF)                                  \
do                                                              \
  {                                                             \
    (VAR) = read_signed_leb128 (abfd, buf, &leb128_tmp);        \
    (BUF) += leb128_tmp;                                        \
  }                                                             \
while (0)

/* Return 0 if either encoding is variable width, or not yet known to bfd.  */

static
int get_DW_EH_PE_width (encoding, ptr_size)
     int encoding, ptr_size;
{
  /* DW_EH_PE_ values of 0x60 and 0x70 weren't defined at the time .eh_frame
     was added to bfd.  */
  if ((encoding & 0x60) == 0x60)
    return 0;

  switch (encoding & 7)
    {
    case DW_EH_PE_udata2: return 2;
    case DW_EH_PE_udata4: return 4;
    case DW_EH_PE_udata8: return 8;
    case DW_EH_PE_absptr: return ptr_size;
    default:
      break;
    }

  return 0;
}

#define get_DW_EH_PE_signed(encoding) (((encoding) & DW_EH_PE_signed) != 0)

/* Read a width sized value from memory.  */

static bfd_vma
read_value (abfd, buf, width, is_signed)
     bfd *abfd;
     bfd_byte *buf;
     int width;
     int is_signed;
{
  bfd_vma value;

  switch (width)
    {
    case 2:
      if (is_signed)
        value = bfd_get_signed_16 (abfd, buf);
      else
        value = bfd_get_16 (abfd, buf);
      break;
    case 4:
      if (is_signed)
        value = bfd_get_signed_32 (abfd, buf);
      else
        value = bfd_get_32 (abfd, buf);
      break;
    case 8:
      if (is_signed)
        value = bfd_get_signed_64 (abfd, buf);
      else
        value = bfd_get_64 (abfd, buf);
      break;
    default:
      BFD_FAIL ();
      return 0;
    }

  return value;
}

/* Store a width sized value to memory.  */

static void
write_value (abfd, buf, value, width)
     bfd *abfd;
     bfd_byte *buf;
     bfd_vma value;
     int width;
{
  switch (width)
    {
    case 2: bfd_put_16 (abfd, value, buf); break;
    case 4: bfd_put_32 (abfd, value, buf); break;
    case 8: bfd_put_64 (abfd, value, buf); break;
    default: BFD_FAIL ();
    }
}

/* Return zero if C1 and C2 CIEs can be merged.  */

static
int cie_compare (c1, c2)
     struct cie *c1, *c2;
{
  if (c1->hdr.length == c2->hdr.length
      && c1->version == c2->version
      && strcmp (c1->augmentation, c2->augmentation) == 0
      && strcmp (c1->augmentation, "eh") != 0
      && c1->code_align == c2->code_align
      && c1->data_align == c2->data_align
      && c1->ra_column == c2->ra_column
      && c1->augmentation_size == c2->augmentation_size
      && c1->personality == c2->personality
      && c1->per_encoding == c2->per_encoding
      && c1->lsda_encoding == c2->lsda_encoding
      && c1->fde_encoding == c2->fde_encoding
      && (c1->initial_insn_length
          == c2->initial_insn_length)
      && memcmp (c1->initial_instructions,
                 c2->initial_instructions,
                 c1->initial_insn_length) == 0)
    return 0;

  return 1;
}

/* This function is called for each input file before the .eh_frame
   section is relocated.  It discards duplicate CIEs and FDEs for discarded
   functions.  The function returns TRUE iff any entries have been
   deleted.  */

bfd_boolean
_bfd_elf_discard_section_eh_frame (abfd, info, sec,
                                   reloc_symbol_deleted_p, cookie)
     bfd *abfd;
     struct bfd_link_info *info;
     asection *sec;
     bfd_boolean (*reloc_symbol_deleted_p) PARAMS ((bfd_vma, PTR));
     struct elf_reloc_cookie *cookie;
{
  bfd_byte *ehbuf = NULL, *buf;