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 30 static inline bool __must_check 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 __must_check 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 __must_check 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 __must_check 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 /* 77 * These are the generic interfaces; they must not be declared if the 78 * stubs in <linux/random.h> are to be invoked, 79 * i.e. CONFIG_ARCH_RANDOM is not defined. 80 */ 81 #ifdef CONFIG_ARCH_RANDOM 82 83 static inline bool __must_check arch_get_random_long(unsigned long *v) 84 { 85 return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_long(v) : false; 86 } 87 88 static inline bool __must_check arch_get_random_int(unsigned int *v) 89 { 90 return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_int(v) : false; 91 } 92 93 static inline bool __must_check arch_get_random_seed_long(unsigned long *v) 94 { 95 return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_long(v) : false; 96 } 97 98 static inline bool __must_check arch_get_random_seed_int(unsigned int *v) 99 { 100 return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_int(v) : false; 101 } 102 103 extern void x86_init_rdrand(struct cpuinfo_x86 *c); 104 105 #else /* !CONFIG_ARCH_RANDOM */ 106 107 static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { } 108 109 #endif /* !CONFIG_ARCH_RANDOM */ 110 111 #endif /* ASM_X86_ARCHRANDOM_H */ 112