xref: /freebsd/sys/compat/linuxkpi/common/include/linux/random.h (revision a90b9d0159070121c221b966469c3e36d912bf82)
1 /*-
2  * Copyright (c) 2010 Isilon Systems, Inc.
3  * Copyright (c) 2010 iX Systems, Inc.
4  * Copyright (c) 2010 Panasas, Inc.
5  * Copyright (c) 2013-2016 Mellanox Technologies, Ltd.
6  * All rights reserved.
7  * Copyright 2023 The FreeBSD Foundation
8  *
9  * Portions of this software was developed by Björn Zeeb
10  * under sponsorship from the FreeBSD Foundation.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice unmodified, this list of conditions, and the following
17  *    disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32  */
33 
34 #ifndef _LINUXKPI_LINUX_RANDOM_H_
35 #define	_LINUXKPI_LINUX_RANDOM_H_
36 
37 #include <linux/types.h>
38 #include <sys/random.h>
39 #include <sys/libkern.h>
40 
41 static inline void
42 get_random_bytes(void *buf, int nbytes)
43 {
44 
45 	arc4random_buf(buf, nbytes);
46 }
47 
48 static inline u_int
49 get_random_int(void)
50 {
51 	u_int val;
52 
53 	get_random_bytes(&val, sizeof(val));
54 	return (val);
55 }
56 
57 #define	get_random_u32() get_random_int()
58 
59 /*
60  * See "Fast Random Integer Generation in an Interval" by Daniel Lemire
61  * [https://arxiv.org/pdf/1805.10941.pdf] for implementation insights.
62  */
63 static inline uint32_t
64 get_random_u32_inclusive(uint32_t floor, uint32_t ceil)
65 {
66 	uint64_t x;
67 	uint32_t t, v;
68 
69 	MPASS(ceil >= floor);
70 
71 	v = get_random_u32();
72 	t = ceil - floor + 1;
73 	x = (uint64_t)t * v;
74 	while (x < t)
75 		x = (uint64_t)t * get_random_u32();
76 	v = x >> 32;
77 
78 	return (floor + v);
79 }
80 
81 static inline u_long
82 get_random_long(void)
83 {
84 	u_long val;
85 
86 	get_random_bytes(&val, sizeof(val));
87 	return (val);
88 }
89 
90 static inline uint64_t
91 get_random_u64(void)
92 {
93 	uint64_t val;
94 
95 	get_random_bytes(&val, sizeof(val));
96 	return (val);
97 }
98 
99 static inline uint32_t
100 get_random_u32_below(uint32_t max)
101 {
102 	return (arc4random_uniform(max));
103 }
104 
105 static __inline uint32_t
106 prandom_u32(void)
107 {
108 	uint32_t val;
109 
110 	get_random_bytes(&val, sizeof(val));
111 	return (val);
112 }
113 
114 static inline u32
115 prandom_u32_max(u32 max)
116 {
117 	return (arc4random_uniform(max));
118 }
119 
120 #endif /* _LINUXKPI_LINUX_RANDOM_H_ */
121