1 /*
2  * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
3  *
4  * SPDX-License-Identifier: BSD-3-Clause
5  */
6 
7 #include <arch_helpers.h>
8 #include <debug.h>
9 #include <utils.h>
10 #include "juno_decl.h"
11 #include "juno_def.h"
12 
plat_get_stack_protector_canary(void)13 u_register_t plat_get_stack_protector_canary(void)
14 {
15 	u_register_t c[TRNG_NBYTES / sizeof(u_register_t)];
16 	u_register_t ret = 0;
17 	size_t i;
18 
19 	if (juno_getentropy(c, sizeof(c)) != 0) {
20 		ERROR("Not enough entropy to initialize canary value\n");
21 		panic();
22 	}
23 
24 	/*
25 	 * On Juno we get 128-bits of entropy in one round.
26 	 * Fuse the values together to form the canary.
27 	 */
28 	for (i = 0; i < ARRAY_SIZE(c); i++)
29 		ret ^= c[i];
30 	return ret;
31 }
32