1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
---|---|
2 | /* |
3 | * This file is part of the Linux kernel. |
4 | * |
5 | * Copyright (c) 2011-2014, Intel Corporation |
6 | * Authors: Fenghua Yu <fenghua.yu@intel.com>, |
7 | * H. Peter Anvin <hpa@linux.intel.com> |
8 | */ |
9 | |
10 | #ifndef ASM_X86_ARCHRANDOM_H |
11 | #define ASM_X86_ARCHRANDOM_H |
12 | |
13 | #include <asm/processor.h> |
14 | #include <asm/cpufeature.h> |
15 | |
16 | #define RDRAND_RETRY_LOOPS 10 |
17 | |
18 | /* Unconditional execution of RDRAND and RDSEED */ |
19 | |
20 | static inline bool __must_check rdrand_long(unsigned long *v) |
21 | { |
22 | bool ok; |
23 | unsigned int retry = RDRAND_RETRY_LOOPS; |
24 | do { |
25 | asm volatile("rdrand %[out]" |
26 | CC_SET(c) |
27 | : CC_OUT(c) (ok), [out] "=r"(*v)); |
28 | if (ok) |
29 | return true; |
30 | } while (--retry); |
31 | return false; |
32 | } |
33 | |
34 | static inline bool __must_check rdseed_long(unsigned long *v) |
35 | { |
36 | bool ok; |
37 | asm volatile("rdseed %[out]" |
38 | CC_SET(c) |
39 | : CC_OUT(c) (ok), [out] "=r"(*v)); |
40 | return ok; |
41 | } |
42 | |
43 | /* |
44 | * These are the generic interfaces; they must not be declared if the |
45 | * stubs in <linux/random.h> are to be invoked. |
46 | */ |
47 | |
48 | static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs) |
49 | { |
50 | return max_longs && static_cpu_has(X86_FEATURE_RDRAND) && rdrand_long(v) ? 1 : 0; |
51 | } |
52 | |
53 | static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs) |
54 | { |
55 | return max_longs && static_cpu_has(X86_FEATURE_RDSEED) && rdseed_long(v) ? 1 : 0; |
56 | } |
57 | |
58 | #ifndef CONFIG_UML |
59 | void x86_init_rdrand(struct cpuinfo_x86 *c); |
60 | #endif |
61 | |
62 | #endif /* ASM_X86_ARCHRANDOM_H */ |
63 |