1*223d989eSMarek Vasut /* 2*223d989eSMarek Vasut * Copyright (c) 2021-2025, Renesas Electronics Corporation. All rights reserved. 3*223d989eSMarek Vasut * 4*223d989eSMarek Vasut * SPDX-License-Identifier: BSD-3-Clause 5*223d989eSMarek Vasut */ 6*223d989eSMarek Vasut 7*223d989eSMarek Vasut #include <stdint.h> 8*223d989eSMarek Vasut 9*223d989eSMarek Vasut #include <arch_helpers.h> 10*223d989eSMarek Vasut #include <common/debug.h> 11*223d989eSMarek Vasut 12*223d989eSMarek Vasut #define RANDOM_CANARY_VALUE ((u_register_t)0xDFF5FC8A720E205EULL) 13*223d989eSMarek Vasut 14*223d989eSMarek Vasut u_register_t plat_get_stack_protector_canary(void) 15*223d989eSMarek Vasut { 16*223d989eSMarek Vasut uintptr_t val1 = (uintptr_t)__builtin_return_address(0U); 17*223d989eSMarek Vasut uintptr_t val2 = (uintptr_t)__builtin_frame_address(0U); 18*223d989eSMarek Vasut u_register_t cnt; 19*223d989eSMarek Vasut u_register_t seed; 20*223d989eSMarek Vasut u_register_t mul; 21*223d989eSMarek Vasut u_register_t ret; 22*223d989eSMarek Vasut 23*223d989eSMarek Vasut cnt = read_cntpct_el0(); 24*223d989eSMarek Vasut seed = (cnt ^ RANDOM_CANARY_VALUE) & ULONG_MAX; 25*223d989eSMarek Vasut ret = seed; 26*223d989eSMarek Vasut 27*223d989eSMarek Vasut INFO("seed value: 0x%16lx cnt: 0x%16lx\n", seed, cnt); 28*223d989eSMarek Vasut 29*223d989eSMarek Vasut if ((ULONG_MAX / val1) > seed) { 30*223d989eSMarek Vasut mul = (u_register_t)(val1 * seed); 31*223d989eSMarek Vasut if ((ULONG_MAX - mul) > val2) { 32*223d989eSMarek Vasut ret = mul + val2; 33*223d989eSMarek Vasut } 34*223d989eSMarek Vasut } 35*223d989eSMarek Vasut 36*223d989eSMarek Vasut INFO("canary value: 0x%lx cnt: 0x%16lx\n", ret, read_cntpct_el0()); 37*223d989eSMarek Vasut 38*223d989eSMarek Vasut return ret; 39*223d989eSMarek Vasut } 40