1 /* 2 * Copyright (c) 2019, Arm Limited. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <arch_helpers.h> 8 #include <cdefs.h> 9 #include <stdint.h> 10 11 /* 12 * This is only a toy implementation to generate a seemingly random 13 * 128-bit key from sp, x30 and cntpct_el0 values. 14 * A production system must re-implement this function to generate 15 * keys from a reliable randomness source. 16 */ plat_init_apkey(void)17uint128_t plat_init_apkey(void) 18 { 19 uint64_t return_addr = (uint64_t)__builtin_return_address(0U); 20 uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U); 21 uint64_t cntpct = read_cntpct_el0(); 22 23 /* Generate 128-bit key */ 24 uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct; 25 uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct; 26 27 return ((uint128_t)(key_hi) << 64) | key_lo; 28 } 29