/* Check getcontext and setcontext on the context from makecontext
   with shadow stack.
   Copyright (C) 2018-2025 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
   <https://www.gnu.org/licenses/>.  */

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <ucontext.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdatomic.h>
#include <x86intrin.h>

static ucontext_t ctx[5];
static atomic_int done;

static void
__attribute_optimization_barrier__
f2 (void)
{
  printf ("start f2\n");
  done++;
  if (setcontext (&ctx[2]) != 0)
    {
      printf ("%s: setcontext: %m\n", __FUNCTION__);
      exit (EXIT_FAILURE);
    }
}

static void
f1 (void)
{
  printf ("start f1\n");
  if (getcontext (&ctx[2]) != 0)
    {
      printf ("%s: getcontext: %m\n", __FUNCTION__);
      exit (EXIT_FAILURE);
    }
  if (done)
    exit (EXIT_SUCCESS);
  f2 ();
}

static int
do_test (void)
{
  char st1[32768];
  puts ("making contexts");
  if (getcontext (&ctx[0]) != 0)
    {
      printf ("%s: getcontext: %m\n", __FUNCTION__);
      exit (EXIT_FAILURE);
    }
  if (getcontext (&ctx[1]) != 0)
    {
      printf ("%s: getcontext: %m\n", __FUNCTION__);
      exit (EXIT_FAILURE);
    }

  ctx[3].uc_stack.ss_sp = st1;
  ctx[3].uc_stack.ss_size = sizeof st1;
  ctx[3].uc_link = &ctx[0];
  makecontext (&ctx[3], (void (*) (void)) f1, 0);

  ctx[1].uc_stack.ss_sp = st1;
  ctx[1].uc_stack.ss_size = sizeof st1;
  ctx[1].uc_link = &ctx[0];
  makecontext (&ctx[1], (void (*) (void)) f1, 0);

  ctx[4].uc_stack.ss_sp = st1;
  ctx[4].uc_stack.ss_size = sizeof st1;
  ctx[4].uc_link = &ctx[0];
  makecontext (&ctx[4], (void (*) (void)) f1, 0);

  /* NB: When shadow stack is enabled, makecontext calls map_shadow_stack
     to allocate a new shadow stack which can be unmapped.  The base
     address and size of the new shadow stack are returned in __ssp[1]
     and __ssp[2].  makecontext is called for CTX1, CTX3 and CTX4.  But
     only CTX1 is used.  New shadow stacks are allocated in the order
     of CTX3, CTX1, CTX4.  It is very likely that CTX1's shadow stack is
     placed between CTX3 and CTX4.  We munmap CTX3's and CTX4's shadow
     stacks to create gaps above and below CTX1's shadow stack.  We check
     that setcontext CTX1 works correctly in this case.  */
  if (_get_ssp () != 0)
    {
      if (ctx[3].__ssp[1] != 0
	  && munmap ((void *) (uintptr_t) ctx[3].__ssp[1],
		     (size_t) ctx[3].__ssp[2]) != 0)
	{
	  printf ("%s: munmap: %m\n", __FUNCTION__);
	  exit (EXIT_FAILURE);
	}

      if (ctx[4].__ssp[1] != 0
	  && munmap ((void *) (uintptr_t) ctx[4].__ssp[1],
		     (size_t) ctx[4].__ssp[2]) != 0)
	{
	  printf ("%s: munmap: %m\n", __FUNCTION__);
	  exit (EXIT_FAILURE);
	}
    }

  if (setcontext (&ctx[1]) != 0)
    {
      printf ("%s: setcontext: %m\n", __FUNCTION__);
      exit (EXIT_FAILURE);
    }
  exit (EXIT_FAILURE);
}

#include <support/test-driver.c>
