gcc/config/ia64/unwind-aix.c

   1 /* Implements unwind table entry lookup for AIX (cf. fde-glibc.c).
   2    Copyright (C) 2001 Free Software Foundation, Inc.
   3    Contributed by Timothy Wall <twall@redhat.com>
   4
   5    This file is part of GNU CC.
   6
   7    GNU CC is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GNU CC is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GNU CC; see the file COPYING.  If not, write to
  19    the Free Software Foundation, 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "tconfig.h"
  23 #include "tsystem.h"
  24 #include "unwind.h"
  25 #include "unwind-ia64.h"
  26
  27 #include <dlfcn.h>
  28 #include <link.h>
  29 #include <sys/mman.h>
  30
  31 static struct unw_table_entry *
  32 find_fde_for_dso (Elf64_Addr pc, rt_link_map *map,
  33                   unsigned long* pseg_base, unsigned long* pgp)
  34 {
  35   rt_segment *seg;
  36   Elf64_Addr seg_base;
  37   struct unw_table_entry *f_base;
  38   size_t lo, hi;
  39
  40   /* See if PC falls into one of the loaded segments.  */
  41   for (seg = map->l_segments; seg; seg = (rt_segment *)seg->s_next)
  42     {
  43       if (pc >= seg->s_map_addr && pc < seg->s_map_addr + seg->s_mapsz)
  44         break;
  45     }
  46   if (!seg)
  47     return NULL;
  48
  49   /* Search for the entry within the unwind table.  */
  50   f_base = (struct unw_table_entry *) (map->l_unwind_table);
  51   seg_base = (Elf64_Addr) seg->s_map_addr;
  52   lo = 0;
  53   hi = map->l_unwind_sz / sizeof (struct unw_table_entry);
  54
  55   while (lo < hi)
  56     {
  57       size_t mid = (lo + hi) / 2;
  58       struct unw_table_entry *f = f_base + mid;
  59
  60       if (pc < f->start_offset + seg_base)
  61         hi = mid;
  62       else if (pc >= f->end_offset + seg_base)
  63         lo = mid + 1;
  64       else {
  65         /* AIX executables are *always* dynamic.  Look up GP for this
  66            object. */
  67         Elf64_Dyn *dyn = map->l_ld;
  68         *pgp = 0;
  69         for (; dyn->d_tag != DT_NULL ; dyn++)
  70           {
  71             if (dyn->d_tag == DT_PLTGOT)
  72               {
  73                 *pgp = dyn->d_un.d_ptr;
  74                 break;
  75               }
  76           }
  77         *pseg_base = seg_base;
  78         return f;
  79       }
  80     }
  81   return NULL;
  82 }
  83
  84 /* Return a pointer to the unwind table entry for the function containing
  85    PC. */
  86 struct unw_table_entry *
  87 _Unwind_FindTableEntry (void *pc, unsigned long *pseg_base, unsigned long *pgp)
  88 {
  89   extern rt_r_debug _r_debug;
  90   struct unw_table_entry *ret;
  91   rt_link_map *map = _r_debug.r_map; /* address of link map */
  92
  93   /* Check the main application first, hoping that most of the user's
  94      code is there instead of in some library.  */
  95   ret = find_fde_for_dso ((Elf64_Addr)pc, map, pseg_base, pgp);
  96   if (ret)
  97     {
  98       /* If we're in the main application, use the current GP value. */
  99       register unsigned long gp __asm__("gp");
 100       *pgp = gp;
 101       return ret;
 102     }
 103
 104   /* FIXME need a DSO lock mechanism for AIX here, to ensure shared
 105      libraries aren't changed while we're examining them.  */
 106
 107   for (map = _r_debug.r_map; map; map = map->l_next)
 108     {
 109       /* Skip the main application's entry.  */
 110       if (!map->l_name)
 111       continue;
 112       ret = find_fde_for_dso ((Elf64_Addr)pc, map, pseg_base, pgp);
 113       if (ret)
 114       break;
 115     }
 116
 117   /* FIXME need a DSO unlock mechanism for AIX here.  */
 118
 119   return ret;
 120 }