sysdeps/powerpc/powerpc32/backtrace.c

   1 /* Return backtrace of current program state.
   2    Copyright (C) 1998, 2000, 2005 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <execinfo.h>
  20 #include <stddef.h>
  21 #include <bp-checks.h>
  22
  23 /* This is the stack layout we see with every stack frame.
  24    Note that every routine is required by the ABI to lay out the stack
  25    like this.
  26
  27             +----------------+        +-----------------+
  28     %r1  -> | %r1 last frame--------> | %r1 last frame--->...  --> NULL
  29             |                |        |                 |
  30             | (unused)       |        | return address  |
  31             +----------------+        +-----------------+
  32 */
  33 struct layout
  34 {
  35   struct layout *__unbounded next;
  36   void *__unbounded return_address;
  37 };
  38
  39 int
  40 __backtrace (void **array, int size)
  41 {
  42   struct layout *current;
  43   int count;
  44
  45   /* Force gcc to spill LR.  */
  46   asm volatile ("" : "=l"(current));
  47
  48   /* Get the address on top-of-stack.  */
  49   asm volatile ("lwz %0,0(1)" : "=r"(current));
  50   current = BOUNDED_1 (current);
  51
  52   for (                         count = 0;
  53        current != NULL &&       count < size;
  54        current = BOUNDED_1 (current->next), count++)
  55     array[count] = current->return_address;
  56
  57   /* It's possible the second-last stack frame can't return
  58      (that is, it's __libc_start_main), in which case
  59      the CRT startup code will have set its LR to 'NULL'.  */
  60   if (count > 0 && array[count-1] == NULL)
  61     count--;
  62
  63   return count;
  64 }
  65 weak_alias (__backtrace, backtrace)
  66 libc_hidden_def (__backtrace)