xref: /freebsd/sys/compat/linuxkpi/common/include/linux/random.h (revision 7f88d742e578c4cef4e26ce10b9a936e58237964)

/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2010 iX Systems, Inc.
 * Copyright (c) 2010 Panasas, Inc.
 * Copyright (c) 2013-2016 Mellanox Technologies, Ltd.
 * All rights reserved.
 * Copyright 2023 The FreeBSD Foundation
 *
 * Portions of this software was developed by Björn Zeeb
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _LINUXKPI_LINUX_RANDOM_H_
#define	_LINUXKPI_LINUX_RANDOM_H_

#include <linux/types.h>
#include <sys/random.h>
#include <sys/libkern.h>

static inline void
get_random_bytes(void *buf, int nbytes)
{

	arc4random_buf(buf, nbytes);
}

static inline u_int
get_random_int(void)
{
	u_int val;

	get_random_bytes(&val, sizeof(val));
	return (val);
}

#define	get_random_u32() get_random_int()

/*
 * See "Fast Random Integer Generation in an Interval" by Daniel Lemire
 * [https://arxiv.org/pdf/1805.10941.pdf] for implementation insights.
 */
static inline uint32_t
get_random_u32_inclusive(uint32_t floor, uint32_t ceil)
{
	uint64_t x;
	uint32_t t, v;

	MPASS(ceil >= floor);

	v = get_random_u32();
	t = ceil - floor + 1;
	x = (uint64_t)t * v;
	while (x < t)
		x = (uint64_t)t * get_random_u32();
	v = x >> 32;

	return (floor + v);
}

static inline u_long
get_random_long(void)
{
	u_long val;

	get_random_bytes(&val, sizeof(val));
	return (val);
}

static inline uint64_t
get_random_u64(void)
{
	uint64_t val;

	get_random_bytes(&val, sizeof(val));
	return (val);
}

static __inline uint32_t
prandom_u32(void)
{
	uint32_t val;

	get_random_bytes(&val, sizeof(val));
	return (val);
}

static inline u32
prandom_u32_max(u32 max)
{
	return (arc4random_uniform(max));
}

#endif /* _LINUXKPI_LINUX_RANDOM_H_ */