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