Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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#define RDRAND_INT ".byte 0x0f,0xc7,0xf0"
19#define RDSEED_INT ".byte 0x0f,0xc7,0xf8"
20#ifdef CONFIG_X86_64
21# define RDRAND_LONG ".byte 0x48,0x0f,0xc7,0xf0"
22# define RDSEED_LONG ".byte 0x48,0x0f,0xc7,0xf8"
23#else
24# define RDRAND_LONG RDRAND_INT
25# define RDSEED_LONG RDSEED_INT
26#endif
27
28/* Unconditional execution of RDRAND and RDSEED */
29
30static inline bool rdrand_long(unsigned long *v)
31{
32 bool ok;
33 unsigned int retry = RDRAND_RETRY_LOOPS;
34 do {
35 asm volatile(RDRAND_LONG
36 CC_SET(c)
37 : CC_OUT(c) (ok), "=a" (*v));
38 if (ok)
39 return true;
40 } while (--retry);
41 return false;
42}
43
44static inline bool rdrand_int(unsigned int *v)
45{
46 bool ok;
47 unsigned int retry = RDRAND_RETRY_LOOPS;
48 do {
49 asm volatile(RDRAND_INT
50 CC_SET(c)
51 : CC_OUT(c) (ok), "=a" (*v));
52 if (ok)
53 return true;
54 } while (--retry);
55 return false;
56}
57
58static inline bool rdseed_long(unsigned long *v)
59{
60 bool ok;
61 asm volatile(RDSEED_LONG
62 CC_SET(c)
63 : CC_OUT(c) (ok), "=a" (*v));
64 return ok;
65}
66
67static inline bool rdseed_int(unsigned int *v)
68{
69 bool ok;
70 asm volatile(RDSEED_INT
71 CC_SET(c)
72 : CC_OUT(c) (ok), "=a" (*v));
73 return ok;
74}
75
76/* Conditional execution based on CPU type */
77#define arch_has_random() static_cpu_has(X86_FEATURE_RDRAND)
78#define arch_has_random_seed() static_cpu_has(X86_FEATURE_RDSEED)
79
80/*
81 * These are the generic interfaces; they must not be declared if the
82 * stubs in <linux/random.h> are to be invoked,
83 * i.e. CONFIG_ARCH_RANDOM is not defined.
84 */
85#ifdef CONFIG_ARCH_RANDOM
86
87static inline bool arch_get_random_long(unsigned long *v)
88{
89 return arch_has_random() ? rdrand_long(v) : false;
90}
91
92static inline bool arch_get_random_int(unsigned int *v)
93{
94 return arch_has_random() ? rdrand_int(v) : false;
95}
96
97static inline bool arch_get_random_seed_long(unsigned long *v)
98{
99 return arch_has_random_seed() ? rdseed_long(v) : false;
100}
101
102static inline bool arch_get_random_seed_int(unsigned int *v)
103{
104 return arch_has_random_seed() ? rdseed_int(v) : false;
105}
106
107extern void x86_init_rdrand(struct cpuinfo_x86 *c);
108
109#else /* !CONFIG_ARCH_RANDOM */
110
111static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { }
112
113#endif /* !CONFIG_ARCH_RANDOM */
114
115#endif /* ASM_X86_ARCHRANDOM_H */