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 20static 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 34static inline bool __must_check rdseed_long(unsigned long *v) 35{ 36 bool ok; 37 asm volatile("rdseed %[out]" 38 CC_SET(c) 39 : CC_OUT(c) (ok), [out] "=r" (*v)); 40 return ok; 41} 42 43/* 44 * These are the generic interfaces; they must not be declared if the 45 * stubs in <linux/random.h> are to be invoked. 46 */ 47 48static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs) 49{ 50 return max_longs && static_cpu_has(X86_FEATURE_RDRAND) && rdrand_long(v) ? 1 : 0; 51} 52 53static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs) 54{ 55 return max_longs && static_cpu_has(X86_FEATURE_RDSEED) && rdseed_long(v) ? 1 : 0; 56} 57 58#ifndef CONFIG_UML 59void x86_init_rdrand(struct cpuinfo_x86 *c); 60#endif 61 62#endif /* ASM_X86_ARCHRANDOM_H */ 63