| Soby Mathew | b4c6df4 | 2022-11-09 11:13:29 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * SPDX-License-Identifier: BSD-3-Clause |
| 3 | * SPDX-FileCopyrightText: Copyright TF-RMM Contributors. |
| 4 | */ |
| 5 | |
| 6 | #ifndef ENTROPY_H |
| 7 | #define ENTROPY_H |
| 8 | |
| 9 | #include <arch.h> |
| 10 | #include <utils_def.h> |
| 11 | |
| 12 | /* |
| 13 | * Write 8 bytes of random data in random. Returns true on success, false on |
| 14 | * failure. |
| 15 | */ |
| 16 | static inline bool arch_collect_entropy(uint64_t *random) |
| 17 | { |
| 18 | unsigned long rc; |
| 19 | uint64_t val; |
| 20 | |
| 21 | asm volatile( |
| 22 | " mrs %[val], " __XSTRING(RNDR) "\n" |
| 23 | " str %[val], %[random_ptr]\n" |
| 24 | " cset %[rc], ne\n" /* RNDR sets NZCV to 0b0100 on failure */ |
| 25 | : [random_ptr] "=m" (*random), |
| 26 | [rc] "=r" (rc), |
| 27 | [val] "=r" (val) |
| 28 | : |
| 29 | : "cc" |
| 30 | ); |
| 31 | return (rc == 1); |
| 32 | } |
| 33 | |
| 34 | #endif /* ENTROPY_H */ |