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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* This file is part of the Linux kernel.
*
* Copyright (c) 2011-2014, Intel Corporation
* Authors: Fenghua Yu <fenghua.yu@intel.com>,
* H. Peter Anvin <hpa@linux.intel.com>
*/
#ifndef ASM_X86_ARCHRANDOM_H
#define ASM_X86_ARCHRANDOM_H
#include <asm/processor.h>
#include <asm/cpufeature.h>
#define RDRAND_RETRY_LOOPS 10
/* Unconditional execution of RDRAND and RDSEED */
static inline bool __must_check rdrand_long(unsigned long *v)
{
bool ok;
unsigned int retry = RDRAND_RETRY_LOOPS;
do {
asm volatile("rdrand %[out]"
CC_SET(c)
: CC_OUT(c) (ok), [out] "=r" (*v));
if (ok)
return true;
} while (--retry);
return false;
}
static inline bool __must_check rdseed_long(unsigned long *v)
{
bool ok;
asm volatile("rdseed %[out]"
CC_SET(c)
: CC_OUT(c) (ok), [out] "=r" (*v));
return ok;
}
/*
* These are the generic interfaces; they must not be declared if the
* stubs in <linux/random.h> are to be invoked.
*/
static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
{
return max_longs && static_cpu_has(X86_FEATURE_RDRAND) && rdrand_long(v) ? 1 : 0;
}
static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
{
return max_longs && static_cpu_has(X86_FEATURE_RDSEED) && rdseed_long(v) ? 1 : 0;
}
#ifndef CONFIG_UML
void x86_init_rdrand(struct cpuinfo_x86 *c);
#endif
#endif /* ASM_X86_ARCHRANDOM_H */
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