5bfce5ef55
Adds potential sources of randomness: RDRAND, RDTSC, or the i8254. This moves the pre-alternatives inline rdrand function into the header so both pieces of code can use it. Availability of RDRAND is then controlled by CONFIG_ARCH_RANDOM, if someone wants to disable it even for kASLR. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/1381450698-28710-4-git-send-email-keescook@chromium.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
96 lines
2.6 KiB
C
96 lines
2.6 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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/* Instead of arch_get_random_long() when alternatives haven't run. */
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static inline int rdrand_long(unsigned long *v)
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{
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int ok;
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asm volatile("1: " RDRAND_LONG "\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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: "=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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#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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#else
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static inline int rdrand_long(unsigned long *v)
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{
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return 0;
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}
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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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