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Douglas Raillard306593d2017-02-24 18:14:15 +00001/*
2 * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
3 *
dp-armfa3cf0b2017-05-03 09:38:09 +01004 * SPDX-License-Identifier: BSD-3-Clause
Douglas Raillard306593d2017-02-24 18:14:15 +00005 */
6
7#include <arch_helpers.h>
8#include <platform.h>
9#include <stdint.h>
10
11#define RANDOM_CANARY_VALUE ((u_register_t) 3288484550995823360ULL)
12
13u_register_t plat_get_stack_protector_canary(void)
14{
15 /*
16 * Ideally, a random number should be returned instead of the
17 * combination of a timer's value and a compile-time constant. As the
18 * FVP does not have any random number generator, this is better than
19 * nothing but not necessarily really secure.
20 */
21 return RANDOM_CANARY_VALUE ^ read_cntpct_el0();
22}
23