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49d859d78c
If the CPU declares that RDRAND is available, go through a guranteed reseed sequence, and make sure that it is actually working (producing data.) If it does not, disable the CPU feature flag. Allow RDRAND to be disabled on the command line (as opposed to at compile time) for a user who has special requirements with regards to random numbers. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "Theodore Ts'o" <tytso@mit.edu>
76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
/*
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* This file is part of the Linux kernel.
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*
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* Copyright (c) 2011, 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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#include <asm/alternative.h>
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#include <asm/nops.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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#ifdef CONFIG_X86_64
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# define RDRAND_LONG ".byte 0x48,0x0f,0xc7,0xf0"
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#else
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# define RDRAND_LONG RDRAND_INT
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#endif
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#ifdef CONFIG_ARCH_RANDOM
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#define GET_RANDOM(name, type, rdrand, nop) \
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static inline int name(type *v) \
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{ \
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int ok; \
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alternative_io("movl $0, %0\n\t" \
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nop, \
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"\n1: " rdrand "\n\t" \
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"jc 2f\n\t" \
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"decl %0\n\t" \
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"jnz 1b\n\t" \
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"2:", \
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X86_FEATURE_RDRAND, \
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ASM_OUTPUT2("=r" (ok), "=a" (*v)), \
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"0" (RDRAND_RETRY_LOOPS)); \
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return ok; \
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}
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#ifdef CONFIG_X86_64
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GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5);
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GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4);
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#else
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GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3);
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GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);
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#endif /* CONFIG_X86_64 */
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#endif /* CONFIG_ARCH_RANDOM */
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extern void x86_init_rdrand(struct cpuinfo_x86 *c);
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#endif /* ASM_X86_ARCHRANDOM_H */
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