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/* Return backtrace of current program state.
Copyright (C) 1998-2013 Free Software Foundation, Inc.
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, see
<http://www.gnu.org/licenses/>. */
#include <execinfo.h>
#include <stddef.h>
/* This is the stack layout we see with every stack frame.
Note that every routine is required by the ABI to lay out the stack
like this.
+----------------+ +-----------------+
%r1 -> | %r1 last frame--------> | %r1 last frame--->... --> NULL
| | | |
| (unused) | | return address |
+----------------+ +-----------------+
*/
struct layout
{
struct layout *next;
void *return_address;
};
int
__backtrace (void **array, int size)
{
struct layout *current;
int count;
/* Force gcc to spill LR. */
asm volatile ("" : "=l"(current));
/* Get the address on top-of-stack. */
asm volatile ("lwz %0,0(1)" : "=r"(current));
for ( count = 0;
current != NULL && count < size;
current = current->next, count++)
array[count] = current->return_address;
/* It's possible the second-last stack frame can't return
(that is, it's __libc_start_main), in which case
the CRT startup code will have set its LR to 'NULL'. */
if (count > 0 && array[count-1] == NULL)
count--;
return count;
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)
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