src/libs/libunwind/x86/Gstep.c

   1 /* libunwind - a platform-independent unwind library
   2    Copyright (C) 2002-2004 Hewlett-Packard Co
   3         Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
   4
   5 This file is part of libunwind.
   6
   7 Permission is hereby granted, free of charge, to any person obtaining
   8 a copy of this software and associated documentation files (the
   9 "Software"), to deal in the Software without restriction, including
  10 without limitation the rights to use, copy, modify, merge, publish,
  11 distribute, sublicense, and/or sell copies of the Software, and to
  12 permit persons to whom the Software is furnished to do so, subject to
  13 the following conditions:
  14
  15 The above copyright notice and this permission notice shall be
  16 included in all copies or substantial portions of the Software.
  17
  18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  20 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  22 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  23 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  24 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
  25
  26 #include "unwind_i.h"
  27 #include "offsets.h"
  28
  29 PROTECTED int
  30 unw_step (unw_cursor_t *cursor)
  31 {
  32   struct cursor *c = (struct cursor *) cursor;
  33   int ret, i;
  34
  35   Debug (1, "(cursor=%p, ip=0x%08x)\n", c, (unsigned) c->dwarf.ip);
  36
  37   /* Try DWARF-based unwinding... */
  38   ret = dwarf_step (&c->dwarf);
  39
  40   if (ret < 0 && ret != -UNW_ENOINFO)
  41     {
  42       Debug (2, "returning %d\n", ret);
  43       return ret;
  44     }
  45
  46   if (unlikely (ret < 0))
  47     {
  48       /* DWARF failed, let's see if we can follow the frame-chain
  49          or skip over the signal trampoline.  */
  50       struct dwarf_loc ebp_loc, eip_loc;
  51
  52       /* We could get here because of missing/bad unwind information.
  53          Validate all addresses before dereferencing. */
  54       c->validate = 1;
  55
  56       Debug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret);
  57
  58       if (unw_is_signal_frame (cursor))
  59         {
  60           ret = unw_handle_signal_frame(cursor);
  61           if (ret < 0)
  62             {
  63               Debug (2, "returning 0\n");
  64               return 0;
  65             }
  66         }
  67       else
  68         {
  69           ret = dwarf_get (&c->dwarf, c->dwarf.loc[EBP], &c->dwarf.cfa);
  70           if (ret < 0)
  71             {
  72               Debug (2, "returning %d\n", ret);
  73               return ret;
  74             }
  75
  76           Debug (13, "[EBP=0x%x] = 0x%x\n", DWARF_GET_LOC (c->dwarf.loc[EBP]),
  77                  c->dwarf.cfa);
  78
  79           ebp_loc = DWARF_LOC (c->dwarf.cfa, 0);
  80           eip_loc = DWARF_LOC (c->dwarf.cfa + 4, 0);
  81           c->dwarf.cfa += 8;
  82
  83           /* Mark all registers unsaved, since we don't know where
  84              they are saved (if at all), except for the EBP and
  85              EIP.  */
  86           for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
  87             c->dwarf.loc[i] = DWARF_NULL_LOC;
  88
  89           c->dwarf.loc[EBP] = ebp_loc;
  90           c->dwarf.loc[EIP] = eip_loc;
  91           c->dwarf.use_prev_instr = 1;
  92         }
  93       c->dwarf.ret_addr_column = EIP;
  94
  95       if (!DWARF_IS_NULL_LOC (c->dwarf.loc[EBP]))
  96         {
  97           ret = dwarf_get (&c->dwarf, c->dwarf.loc[EIP], &c->dwarf.ip);
  98           if (ret < 0)
  99             {
 100               Debug (13, "dwarf_get([EIP=0x%x]) failed\n", DWARF_GET_LOC (c->dwarf.loc[EIP]));
 101               Debug (2, "returning %d\n", ret);
 102               return ret;
 103             }
 104           else
 105             {
 106               Debug (13, "[EIP=0x%x] = 0x%x\n", DWARF_GET_LOC (c->dwarf.loc[EIP]),
 107                 c->dwarf.ip);
 108             }
 109         }
 110       else
 111         c->dwarf.ip = 0;
 112     }
 113   ret = (c->dwarf.ip == 0) ? 0 : 1;
 114   Debug (2, "returning %d\n", ret);
 115   return ret;
 116 }