sysdeps/s390/backtrace.c

   1 /* Return backtrace of current program state.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <execinfo.h>
  22 #include <stddef.h>
  23
  24 /* This is a global variable set at program start time.  It marks the
  25    highest used stack address.  */
  26 extern void *__libc_stack_end;
  27
  28
  29 /* This is the stack layout we see for every non-leaf function.
  30            size                    offset
  31     %r15 ->    +------------------+
  32              4 | back chain       |  0
  33              4 | end of stack     |  4
  34              8 | glue             |  8
  35              8 | scratch          | 16
  36             40 | save area r6-r15 | 24
  37             16 | save area f4,f6  | 64
  38             16 | empty            | 80
  39                +------------------+
  40    r14 in the save area holds the return address.
  41 */
  42
  43 struct layout
  44 {
  45   int back_chain;
  46   int end_of_stack;
  47   int glue[2];
  48   int scratch[2];
  49   int save_grps[10];
  50   int save_fp[4];
  51   int empty[2];
  52 };
  53
  54 int
  55 __backtrace (array, size)
  56      void **array;
  57      int size;
  58 {
  59   /* We assume that all the code is generated with frame pointers set.  */
  60   struct layout *stack;
  61   int cnt = 0;
  62
  63   asm ("LR  %0,%%r15" : "=d" (stack) );
  64   /* We skip the call to this function, it makes no sense to record it.  */
  65   stack = (struct layout *) stack->back_chain;
  66   while (cnt < size)
  67     {
  68       if (stack == NULL || (void *) stack > __libc_stack_end)
  69         /* This means the address is out of range.  Note that for the
  70            toplevel we see a frame pointer with value NULL which clearly is
  71            out of range.  */
  72         break;
  73
  74       array[cnt++] = stack->save_grps[9];
  75
  76       stack = (struct layout *) stack->back_chain;
  77     }
  78
  79   return cnt;
  80 }
  81 weak_alias (__backtrace, backtrace)