1*91f16700Schasinglulu /* 2*91f16700Schasinglulu * Copyright (c) 2019, Arm Limited. All rights reserved. 3*91f16700Schasinglulu * 4*91f16700Schasinglulu * SPDX-License-Identifier: BSD-3-Clause 5*91f16700Schasinglulu */ 6*91f16700Schasinglulu 7*91f16700Schasinglulu #include <arch_helpers.h> 8*91f16700Schasinglulu #include <cdefs.h> 9*91f16700Schasinglulu #include <stdint.h> 10*91f16700Schasinglulu 11*91f16700Schasinglulu /* 12*91f16700Schasinglulu * This is only a toy implementation to generate a seemingly random 13*91f16700Schasinglulu * 128-bit key from sp, x30 and cntpct_el0 values. 14*91f16700Schasinglulu * A production system must re-implement this function to generate 15*91f16700Schasinglulu * keys from a reliable randomness source. 16*91f16700Schasinglulu */ 17*91f16700Schasinglulu uint128_t plat_init_apkey(void) 18*91f16700Schasinglulu { 19*91f16700Schasinglulu uint64_t return_addr = (uint64_t)__builtin_return_address(0U); 20*91f16700Schasinglulu uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U); 21*91f16700Schasinglulu uint64_t cntpct = read_cntpct_el0(); 22*91f16700Schasinglulu 23*91f16700Schasinglulu /* Generate 128-bit key */ 24*91f16700Schasinglulu uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct; 25*91f16700Schasinglulu uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct; 26*91f16700Schasinglulu 27*91f16700Schasinglulu return ((uint128_t)(key_hi) << 64) | key_lo; 28*91f16700Schasinglulu } 29