/*
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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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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*
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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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#define RDRAND_INT ".byte 0x0f,0xc7,0xf0"
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#define RDSEED_INT ".byte 0x0f,0xc7,0xf8"
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#ifdef CONFIG_X86_64
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# define RDRAND_LONG ".byte 0x48,0x0f,0xc7,0xf0"
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# define RDSEED_LONG ".byte 0x48,0x0f,0xc7,0xf8"
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#else
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# define RDRAND_LONG RDRAND_INT
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# define RDSEED_LONG RDSEED_INT
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#endif
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/* Unconditional execution of RDRAND and RDSEED */
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static inline bool 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_LONG
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*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 rdrand_int(unsigned int *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_INT
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*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 rdseed_long(unsigned long *v)
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{
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bool ok;
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asm volatile(RDSEED_LONG
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*v));
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return ok;
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}
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static inline bool rdseed_int(unsigned int *v)
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{
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bool ok;
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asm volatile(RDSEED_INT
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CC_SET(c)
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: CC_OUT(c) (ok), "=a" (*v));
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return ok;
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}
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/* Conditional execution based on CPU type */
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#define arch_has_random() static_cpu_has(X86_FEATURE_RDRAND)
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#define arch_has_random_seed() static_cpu_has(X86_FEATURE_RDSEED)
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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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* i.e. CONFIG_ARCH_RANDOM is not defined.
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*/
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#ifdef CONFIG_ARCH_RANDOM
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static inline bool arch_get_random_long(unsigned long *v)
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{
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return arch_has_random() ? rdrand_long(v) : false;
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}
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static inline bool arch_get_random_int(unsigned int *v)
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{
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return arch_has_random() ? rdrand_int(v) : false;
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}
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static inline bool arch_get_random_seed_long(unsigned long *v)
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{
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return arch_has_random_seed() ? rdseed_long(v) : false;
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}
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static inline bool arch_get_random_seed_int(unsigned int *v)
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{
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return arch_has_random_seed() ? rdseed_int(v) : false;
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}
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extern void x86_init_rdrand(struct cpuinfo_x86 *c);
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#else /* !CONFIG_ARCH_RANDOM */
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static inline void x86_init_rdrand(struct cpuinfo_x86 *c) { }
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#endif /* !CONFIG_ARCH_RANDOM */
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#endif /* ASM_X86_ARCHRANDOM_H */
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