| David Brazdil | 0f672f6 | 2019-12-10 10:32:29 +0000 | [diff] [blame^] | 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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> |
| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 87 | static inline bool arch_get_random_long(unsigned long *v) |
| 88 | { |
| 89 | return arch_has_random() ? rdrand_long(v) : false; |
| 90 | } |
| 91 | |
| 92 | static inline bool arch_get_random_int(unsigned int *v) |
| 93 | { |
| 94 | return arch_has_random() ? rdrand_int(v) : false; |
| 95 | } |
| 96 | |
| 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 | |
| 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 | |
| 111 | static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { } |
| 112 | |
| 113 | #endif /* !CONFIG_ARCH_RANDOM */ |
| 114 | |
| 115 | #endif /* ASM_X86_ARCHRANDOM_H */ |