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 rdrand_int(unsigned int *v) 35 { 36 bool ok; 37 unsigned int retry = RDRAND_RETRY_LOOPS; 38 do { 39 asm volatile("rdrand %[out]" 40 CC_SET(c) 41 : CC_OUT(c) (ok), [out] "=r" (*v)); 42 if (ok) 43 return true; 44 } while (--retry); 45 return false; 46 } 47 48 static inline bool __must_check rdseed_long(unsigned long *v) 49 { 50 bool ok; 51 asm volatile("rdseed %[out]" 52 CC_SET(c) 53 : CC_OUT(c) (ok), [out] "=r" (*v)); 54 return ok; 55 } 56 57 static inline bool __must_check rdseed_int(unsigned int *v) 58 { 59 bool ok; 60 asm volatile("rdseed %[out]" 61 CC_SET(c) 62 : CC_OUT(c) (ok), [out] "=r" (*v)); 63 return ok; 64 } 65 66 /* 67 * These are the generic interfaces; they must not be declared if the 68 * stubs in <linux/random.h> are to be invoked, 69 * i.e. CONFIG_ARCH_RANDOM is not defined. 70 */ 71 #ifdef CONFIG_ARCH_RANDOM 72 73 static inline bool __must_check arch_get_random_long(unsigned long *v) 74 { 75 return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_long(v) : false; 76 } 77 78 static inline bool __must_check arch_get_random_int(unsigned int *v) 79 { 80 return static_cpu_has(X86_FEATURE_RDRAND) ? rdrand_int(v) : false; 81 } 82 83 static inline bool __must_check arch_get_random_seed_long(unsigned long *v) 84 { 85 return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_long(v) : false; 86 } 87 88 static inline bool __must_check arch_get_random_seed_int(unsigned int *v) 89 { 90 return static_cpu_has(X86_FEATURE_RDSEED) ? rdseed_int(v) : false; 91 } 92 93 extern void x86_init_rdrand(struct cpuinfo_x86 *c); 94 95 #else /* !CONFIG_ARCH_RANDOM */ 96 97 static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { } 98 99 #endif /* !CONFIG_ARCH_RANDOM */ 100 101 #endif /* ASM_X86_ARCHRANDOM_H */ 102