/* Return backtrace of current program state.   Copyright (C) 2000, 2001, 2003, 2004, 2005 Free Software Foundation, Inc.   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>.   This file is part of the GNU C Library.   The GNU C Library is free software; you can redistribute it and/or   modify it under the terms of the GNU Lesser General Public   License as published by the Free Software Foundation; either   version 2.1 of the License, or (at your option) any later version.   The GNU C Library is distributed in the hope that it will be useful,   but WITHOUT ANY WARRANTY; without even the implied warranty of   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   Lesser General Public License for more details.   You should have received a copy of the GNU Lesser General Public   License along with the GNU C Library; if not, write to the Free   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA   02111-1307 USA.  */#include <bits/libc-lock.h>#include <dlfcn.h>#include <execinfo.h>#include <stddef.h>#include <stdlib.h>#include <unwind.h>/* This is a global variable set at program start time.  It marks the   highest used stack address.  */extern void *__libc_stack_end;/* This is the stack layout we see for every non-leaf function.           size                    offset    %r15 ->    +------------------+             4 | back chain       |  0             4 | end of stack     |  4             8 | glue             |  8             8 | scratch          | 16            40 | save area r6-r15 | 24            16 | save area f4,f6  | 64            16 | empty            | 80               +------------------+   r14 in the save area holds the return address.*/struct layout{  int back_chain;  int end_of_stack;  int glue[2];  int scratch[2];  int save_grps[10];  int save_fp[4];  int empty[2];};struct trace_arg{  void **array;  int cnt, size;};#ifdef SHAREDstatic _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);static voidinit (void){  void *handle = __libc_dlopen ("libgcc_s.so.1");  if (handle == NULL)    return;  unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace");  unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP");  if (unwind_getip == NULL)    unwind_backtrace = NULL;}#else# define unwind_backtrace _Unwind_Backtrace# define unwind_getip _Unwind_GetIP#endifstatic int__backchain_backtrace (void **array, int size){  /* We assume that all the code is generated with frame pointers set.  */  struct layout *stack;  int cnt = 0;  asm ("LR  %0,%%r15" : "=d" (stack) );  /* We skip the call to this function, it makes no sense to record it.  */  stack = (struct layout *) stack->back_chain;  while (cnt < size)    {      if (stack == NULL || (void *) stack > __libc_stack_end)	/* This means the address is out of range.  Note that for the	   toplevel we see a frame pointer with value NULL which clearly is	   out of range.  */	break;      array[cnt++] = (void *) (stack->save_grps[8] & 0x7fffffff);      stack = (struct layout *) stack->back_chain;    }  return cnt;}static _Unwind_Reason_Codebacktrace_helper (struct _Unwind_Context *ctx, void *a){  struct trace_arg *arg = a;  /* We are first called with address in the __backtrace function.     Skip it.  */  if (arg->cnt != -1)    arg->array[arg->cnt] = (void *) unwind_getip (ctx);  if (++arg->cnt == arg->size)    return _URC_END_OF_STACK;  return _URC_NO_REASON;}int__backtrace (void **array, int size){  struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };#ifdef SHARED  __libc_once_define (static, once);  __libc_once (once, init);#endif  if (unwind_backtrace == NULL)    return __backchain_backtrace (array, size);  if (size >= 1)    unwind_backtrace (backtrace_helper, &arg);  return arg.cnt != -1 ? arg.cnt : 0;}weak_alias (__backtrace, backtrace)libc_hidden_def (__backtrace)