1 /* 2 * Copyright (c) 2019, Arm Limited. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <cdefs.h> 8 #include <stdint.h> 9 10 /* 11 * Instruction pointer authentication key A. The low 64-bit are at [0], and the 12 * high bits at [1]. 13 */ 14 uint64_t plat_apiakey[2]; 15 16 /* 17 * This is only a toy implementation to generate a seemingly random 128-bit key 18 * from sp and x30 values. A production system must re-implement this function 19 * to generate keys from a reliable randomness source. 20 */ 21 uint64_t *plat_init_apiakey(void) 22 { 23 uintptr_t return_addr = (uintptr_t)__builtin_return_address(0U); 24 uintptr_t frame_addr = (uintptr_t)__builtin_frame_address(0U); 25 26 plat_apiakey[0] = (return_addr << 13) ^ frame_addr; 27 plat_apiakey[1] = (frame_addr << 15) ^ return_addr; 28 29 return plat_apiakey; 30 } 31