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
rdrand_long(unsigned long * v)30 static 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
rdrand_int(unsigned int * v)44 static 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
rdseed_long(unsigned long * v)58 static 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
rdseed_int(unsigned int * v)67 static 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
arch_get_random_long(unsigned long * v)87 static inline bool arch_get_random_long(unsigned long *v)
88 {
89 return arch_has_random() ? rdrand_long(v) : false;
90 }
91
arch_get_random_int(unsigned int * v)92 static inline bool arch_get_random_int(unsigned int *v)
93 {
94 return arch_has_random() ? rdrand_int(v) : false;
95 }
96
arch_get_random_seed_long(unsigned long * v)97 static inline bool arch_get_random_seed_long(unsigned long *v)
98 {
99 return arch_has_random_seed() ? rdseed_long(v) : false;
100 }
101
arch_get_random_seed_int(unsigned int * v)102 static inline bool arch_get_random_seed_int(unsigned int *v)
103 {
104 return arch_has_random_seed() ? rdseed_int(v) : false;
105 }
106
107 extern void x86_init_rdrand(struct cpuinfo_x86 *c);
108
109 #else /* !CONFIG_ARCH_RANDOM */
110
x86_init_rdrand(struct cpuinfo_x86 * c)111 static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { }
112
113 #endif /* !CONFIG_ARCH_RANDOM */
114
115 #endif /* ASM_X86_ARCHRANDOM_H */
116
