/*
 * Copyright (c) 2018 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/ztest.h>
#include <zephyr/kernel.h>

#define STACKSIZE       2048
#define THREAD_COUNT	64
#define VERBOSE		0

void *last_sp = (void *)0xFFFFFFFF;
volatile unsigned int changed;

/*
 * The `alternate_thread` function deliberately makes use of a dangling pointer
 * in order to test stack randomisation.
 */
#if defined(__GNUC__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Wdangling-pointer"
#endif

void alternate_thread(void)
{
	int i;
	void *sp_val;

	/* If the stack isn't being randomized then sp_val will never change */
	sp_val = &i;

#if VERBOSE
	printk("stack pointer: %p last: %p\n", sp_val, last_sp);
#endif

	if (last_sp != (void *)0xFFFFFFFF && sp_val != last_sp) {
		changed++;
	}
	last_sp = sp_val;
}

#if defined(__GNUC__)
#pragma GCC diagnostic pop
#endif

K_THREAD_STACK_DEFINE(alt_thread_stack_area, STACKSIZE);
static struct k_thread alt_thread_data;

/**
 * @brief Test stack pointer randomization
 *
 * @ingroup kernel_memprotect_tests
 *
 */
ZTEST(stack_pointer_randomness, test_stack_pt_randomization)
{
	int i, sp_changed;
	int old_prio = k_thread_priority_get(k_current_get());

	/* Set preemptable priority */
	k_thread_priority_set(k_current_get(), K_PRIO_PREEMPT(1));

	printk("Test Stack pointer randomization\n");

	/* Start thread */
	for (i = 0; i < THREAD_COUNT; i++) {
		k_thread_create(&alt_thread_data, alt_thread_stack_area,
				STACKSIZE, (k_thread_entry_t)alternate_thread,
				NULL, NULL, NULL, K_HIGHEST_THREAD_PRIO, 0,
				K_NO_WAIT);
		k_sleep(K_MSEC(10));
	}


	printk("stack pointer changed %d times out of %d tests\n",
	       changed, THREAD_COUNT);

	sp_changed = changed;
	zassert_not_equal(sp_changed, 0, "Stack pointer is not randomized");

	/* Restore priority */
	k_thread_priority_set(k_current_get(), old_prio);
}

ZTEST_SUITE(stack_pointer_randomness, NULL, NULL,
		ztest_simple_1cpu_before, ztest_simple_1cpu_after, NULL);