sysdeps/generic/backtrace.c

   1 /* Return backtrace of current program state.  Generic version.
   2    Copyright (C) 1998, 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <execinfo.h>
  22 #include <signal.h>
  23 #include <frame.h>
  24 #include <sigcontextinfo.h>
  25 #include <bp-checks.h>
  26
  27 /* This is a global variable set at program start time.  It marks the
  28    highest used stack address.  */
  29 extern void *__libc_stack_end;
  30
  31
  32 /* This implementation assumes a stack layout that matches the defaults
  33    used by gcc's `__builtin_frame_address' and `__builtin_return_address'
  34    (FP is the frame pointer register):
  35
  36           +-----------------+     +-----------------+
  37     FP -> | previous FP --------> | previous FP ------>...
  38           |                 |     |                 |
  39           | return address  |     | return address  |
  40           +-----------------+     +-----------------+
  41
  42   */
  43
  44 /* Get some notion of the current stack.  Need not be exactly the top
  45    of the stack, just something somewhere in the current frame.  */
  46 #ifndef CURRENT_STACK_FRAME
  47 # define CURRENT_STACK_FRAME  ({ char __csf; &__csf; })
  48 #endif
  49
  50 /* By default we assume that the stack grows downward.  */
  51 #ifndef INNER_THAN
  52 # define INNER_THAN <
  53 #endif
  54
  55 /* By default assume the `next' pointer in struct layout points to the
  56    next struct layout.  */
  57 #ifndef ADVANCE_STACK_FRAME
  58 # define ADVANCE_STACK_FRAME(next) BOUNDED_1 ((struct layout *) (next))
  59 #endif
  60
  61 int
  62 __backtrace (array, size)
  63      void **array;
  64      int size;
  65 {
  66   struct layout *current;
  67   void *__unbounded top_frame;
  68   void *__unbounded top_stack;
  69   int cnt = 0;
  70
  71   top_frame = __builtin_frame_address (0);
  72   top_stack = CURRENT_STACK_FRAME;
  73
  74   /* We skip the call to this function, it makes no sense to record it.  */
  75   current = BOUNDED_1 ((struct layout *) top_frame);
  76   while (cnt < size)
  77     {
  78       if ((void *) current INNER_THAN top_stack
  79           || !((void *) current INNER_THAN __libc_stack_end))
  80        /* This means the address is out of range.  Note that for the
  81           toplevel we see a frame pointer with value NULL which clearly is
  82           out of range.  */
  83         break;
  84
  85       array[cnt++] = current->return_address;
  86
  87       current = ADVANCE_STACK_FRAME (current->next);
  88     }
  89
  90   return cnt;
  91 }
  92 weak_alias (__backtrace, backtrace)