1ff6844c3SAntonio Nino Diaz /* 2ff6844c3SAntonio Nino Diaz * Copyright (c) 2019, Arm Limited. All rights reserved. 3ff6844c3SAntonio Nino Diaz * 4ff6844c3SAntonio Nino Diaz * SPDX-License-Identifier: BSD-3-Clause 5ff6844c3SAntonio Nino Diaz */ 6ff6844c3SAntonio Nino Diaz 7*ed108b56SAlexei Fedorov #include <arch_helpers.h> 8ff6844c3SAntonio Nino Diaz #include <cdefs.h> 9ff6844c3SAntonio Nino Diaz #include <stdint.h> 10ff6844c3SAntonio Nino Diaz 11ff6844c3SAntonio Nino Diaz /* 12*ed108b56SAlexei Fedorov * This is only a toy implementation to generate a seemingly random 13*ed108b56SAlexei Fedorov * 128-bit key from sp, x30 and cntpct_el0 values. 14*ed108b56SAlexei Fedorov * A production system must re-implement this function to generate 15*ed108b56SAlexei Fedorov * keys from a reliable randomness source. 16ff6844c3SAntonio Nino Diaz */ plat_init_apkey(void)17*ed108b56SAlexei Fedorovuint128_t plat_init_apkey(void) 18ff6844c3SAntonio Nino Diaz { 19*ed108b56SAlexei Fedorov uint64_t return_addr = (uint64_t)__builtin_return_address(0U); 20*ed108b56SAlexei Fedorov uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U); 21*ed108b56SAlexei Fedorov uint64_t cntpct = read_cntpct_el0(); 22ff6844c3SAntonio Nino Diaz 23*ed108b56SAlexei Fedorov /* Generate 128-bit key */ 24*ed108b56SAlexei Fedorov uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct; 25*ed108b56SAlexei Fedorov uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct; 26ff6844c3SAntonio Nino Diaz 27*ed108b56SAlexei Fedorov return ((uint128_t)(key_hi) << 64) | key_lo; 28ff6844c3SAntonio Nino Diaz } 29