| Alexei Fedorov | 719714f | 2019-10-03 10:57:53 +0100 | [diff] [blame^] | 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 | */ |
| 15 | uint128_t init_apkey(void) |
| 16 | { |
| 17 | uint64_t return_addr = (uint64_t)__builtin_return_address(0U); |
| 18 | uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U); |
| 19 | |
| 20 | uint64_t cntpct = read_cntpct_el0(); |
| 21 | |
| 22 | uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct; |
| 23 | uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct; |
| 24 | |
| 25 | return ((uint128_t)(key_hi) << 64) | key_lo; |
| 26 | } |