debug/backtrace.c

   1 /* Return backtrace of current program state.  Generic version.
   2    Copyright (C) 1998-2017 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <execinfo.h>
  21 #include <signal.h>
  22 #include <frame.h>
  23 #include <sigcontextinfo.h>
  24 #include <ldsodefs.h>
  25
  26 /* This implementation assumes a stack layout that matches the defaults
  27    used by gcc's `__builtin_frame_address' and `__builtin_return_address'
  28    (FP is the frame pointer register):
  29
  30           +-----------------+     +-----------------+
  31     FP -> | previous FP --------> | previous FP ------>...
  32           |                 |     |                 |
  33           | return address  |     | return address  |
  34           +-----------------+     +-----------------+
  35
  36   */
  37
  38 /* Get some notion of the current stack.  Need not be exactly the top
  39    of the stack, just something somewhere in the current frame.  */
  40 #ifndef CURRENT_STACK_FRAME
  41 # define CURRENT_STACK_FRAME  ({ char __csf; &__csf; })
  42 #endif
  43
  44 /* By default we assume that the stack grows downward.  */
  45 #ifndef INNER_THAN
  46 # define INNER_THAN <
  47 #endif
  48
  49 /* By default assume the `next' pointer in struct layout points to the
  50    next struct layout.  */
  51 #ifndef ADVANCE_STACK_FRAME
  52 # define ADVANCE_STACK_FRAME(next) ((struct layout *) (next))
  53 #endif
  54
  55 /* By default, the frame pointer is just what we get from gcc.  */
  56 #ifndef FIRST_FRAME_POINTER
  57 # define FIRST_FRAME_POINTER  __builtin_frame_address (0)
  58 #endif
  59
  60 int
  61 __backtrace (void **array, int size)
  62 {
  63   struct layout *current;
  64   void *top_frame;
  65   void *top_stack;
  66   int cnt = 0;
  67
  68   top_frame = FIRST_FRAME_POINTER;
  69   top_stack = CURRENT_STACK_FRAME;
  70
  71   /* We skip the call to this function, it makes no sense to record it.  */
  72   current = ((struct layout *) top_frame);
  73   while (cnt < size)
  74     {
  75       if ((void *) current INNER_THAN top_stack
  76           || !((void *) current INNER_THAN __libc_stack_end))
  77        /* This means the address is out of range.  Note that for the
  78           toplevel we see a frame pointer with value NULL which clearly is
  79           out of range.  */
  80         break;
  81
  82       array[cnt++] = current->return_address;
  83
  84       current = ADVANCE_STACK_FRAME (current->next);
  85     }
  86
  87   return cnt;
  88 }
  89 weak_alias (__backtrace, backtrace)
  90 libc_hidden_def (__backtrace)