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 <common/debug.h> 9 #include <lib/utils.h> 10 #include <platform_def.h> 11 12 #include "juno_decl.h" 13 14 u_register_t plat_get_stack_protector_canary(void) 15 { 16 u_register_t c[TRNG_NBYTES / sizeof(u_register_t)]; 17 u_register_t ret = 0; 18 size_t i; 19 20 if (juno_getentropy(c, sizeof(c)) != 0) { 21 ERROR("Not enough entropy to initialize canary value\n"); 22 panic(); 23 } 24 25 /* 26 * On Juno we get 128-bits of entropy in one round. 27 * Fuse the values together to form the canary. 28 */ 29 for (i = 0; i < ARRAY_SIZE(c); i++) 30 ret ^= c[i]; 31 return ret; 32 } 33