sysdeps/arm/find_exidx.c

   1 /* Copyright (C) 2005-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library.  If not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <link.h>
  19 #include <unwind.h>
  20
  21 struct unw_eh_callback_data
  22 {
  23   _Unwind_Ptr pc;
  24   _Unwind_Ptr exidx_start;
  25   int exidx_len;
  26 };
  27
  28
  29 /* Callback to determins if the PC lies within an object, and remember the
  30    location of the exception index table if it does.  */
  31
  32 static int
  33 find_exidx_callback (struct dl_phdr_info * info, size_t size, void * ptr)
  34 {
  35   struct unw_eh_callback_data * data;
  36   const ElfW(Phdr) *phdr;
  37   int i;
  38   int match;
  39   _Unwind_Ptr load_base;
  40
  41   data = (struct unw_eh_callback_data *) ptr;
  42   load_base = info->dlpi_addr;
  43   phdr = info->dlpi_phdr;
  44
  45   match = 0;
  46   for (i = info->dlpi_phnum; i > 0; i--, phdr++)
  47     {
  48       if (phdr->p_type == PT_LOAD)
  49         {
  50           _Unwind_Ptr vaddr = phdr->p_vaddr + load_base;
  51           if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
  52             match = 1;
  53         }
  54       else if (phdr->p_type == PT_ARM_EXIDX)
  55         {
  56           data->exidx_start = (_Unwind_Ptr) (phdr->p_vaddr + load_base);
  57           data->exidx_len = phdr->p_memsz;
  58         }
  59     }
  60
  61   return match;
  62 }
  63
  64
  65 /* Find the exception index table containing PC.  */
  66
  67 _Unwind_Ptr
  68 __gnu_Unwind_Find_exidx (_Unwind_Ptr pc, int * pcount)
  69 {
  70   struct unw_eh_callback_data data;
  71
  72   data.pc = pc;
  73   data.exidx_start = 0;
  74   if (__dl_iterate_phdr (find_exidx_callback, &data) <= 0)
  75     return 0;
  76
  77   *pcount = data.exidx_len / 8;
  78   return data.exidx_start;
  79 }