/*
* This file is part of the Linux kernel.
*
* Copyright (c) 2011, Intel Corporation
* Authors: Fenghua Yu <[email protected]>,
* H. Peter Anvin <[email protected]>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/

#ifndef ASM_X86_ARCHRANDOM_H
#define ASM_X86_ARCHRANDOM_H

#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/alternative.h>
#include <asm/nops.h>

#define RDRAND_RETRY_LOOPS 10

#define RDRAND_INT ".byte 0x0f,0xc7,0xf0"
#ifdef CONFIG_X86_64
# define RDRAND_LONG ".byte 0x48,0x0f,0xc7,0xf0"
#else
# define RDRAND_LONG RDRAND_INT
#endif

#ifdef CONFIG_ARCH_RANDOM

#define GET_RANDOM(name, type, rdrand, nop) \
static inline int name(type *v) \
{ \
int ok; \
alternative_io("movl $0, %0\n\t" \
nop, \
"\n1: " rdrand "\n\t" \
"jc 2f\n\t" \
"decl %0\n\t" \
"jnz 1b\n\t" \
"2:", \
X86_FEATURE_RDRAND, \
ASM_OUTPUT2("=r" (ok), "=a" (*v)), \
"0" (RDRAND_RETRY_LOOPS)); \
return ok; \
}

#ifdef CONFIG_X86_64

GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5);
GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4);

#else

GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3);
GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3);

#endif /* CONFIG_X86_64 */

#endif /* CONFIG_ARCH_RANDOM */

extern void x86_init_rdrand(struct cpuinfo_x86 *c);

#endif /* ASM_X86_ARCHRANDOM_H */