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/*
* Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <stdint.h>
#include <arch_helpers.h>
#include <arch_features.h>
#include <plat/common/platform.h>
#define RANDOM_CANARY_VALUE ((u_register_t) 3288484550995823360ULL)
u_register_t plat_get_stack_protector_canary(void)
{
#if ENABLE_FEAT_RNG
/* Use the RNDR instruction if the CPU supports it */
if (is_armv8_5_rng_present()) {
return read_rndr();
}
#endif
/*
* Ideally, a random number should be returned above. If a random
* number generator is not supported, return instead a
* combination of a timer's value and a compile-time constant.
* This is better than nothing but not necessarily really secure.
*/
return RANDOM_CANARY_VALUE ^ read_cntpct_el0();
}
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