1 /* 2 * Copyright (c) 2024, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <stdint.h> 8 9 #include <arch_helpers.h> 10 #include <plat/common/platform.h> 11 12 #define RANDOM_CANARY_VALUE ((u_register_t) 3288484550995823360ULL) 13 14 u_register_t plat_get_stack_protector_canary(void) 15 { 16 /* 17 * On the Total Compute platform, it can generate RNG via MHU channel 18 * and communicate with RSE. But the stack protector canary function 19 * is needed prior to MHU channel gets ready. 20 * 21 * Since now MHU module cannot distinguish if MHU channel has been 22 * initialized or not, if it arbitrarily tries to send message, it will 23 * cause panic. For this reason, this function cannot rollback to 24 * dummy random number based on the MHU failure. 25 * 26 * For above reasons, simply return a value of the combination of a 27 * timer's value and a compile-time constant. 28 */ 29 return RANDOM_CANARY_VALUE ^ read_cntpct_el0(); 30 } 31