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/* This test program is part of GDB, the GNU debugger.
Copyright 2015-2017 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* This is the test program loaded into GDB by the py-unwind test. */
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
static void *
swap_value (void **location, void *new_value)
{
void *old_value = *location;
*location = new_value;
return old_value;
}
static void
bad_layout(void **variable_ptr, void *fp)
{
fprintf (stderr, "First variable should be allocated one word below "
"the frame. Got variable's address %p, frame at %p instead.\n",
variable_ptr, fp);
abort();
}
#define MY_FRAME (__builtin_frame_address (0))
static void
corrupt_frame_inner (void)
{
/* Save outer frame address, then corrupt the unwind chain by
setting the outer frame address in it to self. This is
ABI-specific: the first word of the frame contains previous frame
address in amd64. */
void *previous_fp = swap_value ((void **) MY_FRAME, MY_FRAME);
/* Verify the compiler allocates the first local variable one word
below frame. This is where the test unwinder expects to find the
correct outer frame address. */
if (&previous_fp + 1 != (void **) MY_FRAME)
bad_layout (&previous_fp + 1, MY_FRAME);
/* Now restore it so that we can return. The test sets the
breakpoint just before this happens, and GDB will not be able to
show the backtrace without JIT reader. */
swap_value ((void **) MY_FRAME, previous_fp); /* break backtrace-broken */
}
static void
corrupt_frame_outer (void)
{
/* See above for the explanation of the code here. This function
corrupts its frame, too, and then calls the inner one. */
void *previous_fp = swap_value ((void **) MY_FRAME, MY_FRAME);
if (&previous_fp + 1 != (void **) MY_FRAME)
bad_layout (&previous_fp, MY_FRAME);
corrupt_frame_inner ();
swap_value ((void **) MY_FRAME, previous_fp);
}
int
main ()
{
corrupt_frame_outer ();
return 0;
}
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