1 /*-
2 * Copyright (c) 2013 The FreeBSD Foundation
3 * Copyright (c) 2013 David E. O'Brien <[email protected]>
4 * Copyright (c) 2012 Konstantin Belousov <[email protected]>
5 * All rights reserved.
6 *
7 * Portions of this software were developed by Konstantin Belousov
8 * under sponsorship from the FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer
15 * in this position and unchanged.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 */
32
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include <sys/param.h>
37 #include <sys/kernel.h>
38 #include <sys/conf.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/module.h>
42 #include <sys/random.h>
43 #include <sys/systm.h>
44
45 #include <machine/md_var.h>
46 #include <machine/specialreg.h>
47
48 #include <dev/random/randomdev.h>
49
50 #define RETRY_COUNT 10
51
52 static u_int random_ivy_read(void *, u_int);
53
54 static struct random_source random_ivy = {
55 .rs_ident = "Intel Secure Key RNG",
56 .rs_source = RANDOM_PURE_RDRAND,
57 .rs_read = random_ivy_read
58 };
59
60 static inline int
ivy_rng_store(u_long * buf)61 ivy_rng_store(u_long *buf)
62 {
63 #ifdef __GNUCLIKE_ASM
64 u_long rndval;
65 int retry;
66
67 retry = RETRY_COUNT;
68 __asm __volatile(
69 "1:\n\t"
70 "rdrand %1\n\t" /* read randomness into rndval */
71 "jc 2f\n\t" /* CF is set on success, exit retry loop */
72 "dec %0\n\t" /* otherwise, retry-- */
73 "jne 1b\n\t" /* and loop if retries are not exhausted */
74 "2:"
75 : "+r" (retry), "=r" (rndval) : : "cc");
76 *buf = rndval;
77 return (retry);
78 #else /* __GNUCLIKE_ASM */
79 return (0);
80 #endif
81 }
82
83 /* It is required that buf length is a multiple of sizeof(u_long). */
84 static u_int
random_ivy_read(void * buf,u_int c)85 random_ivy_read(void *buf, u_int c)
86 {
87 u_long *b, rndval;
88 u_int count;
89
90 KASSERT(c % sizeof(*b) == 0, ("partial read %d", c));
91 b = buf;
92 for (count = c; count > 0; count -= sizeof(*b)) {
93 if (ivy_rng_store(&rndval) == 0)
94 break;
95 *b++ = rndval;
96 }
97 return (c - count);
98 }
99
100 static int
rdrand_modevent(module_t mod,int type,void * unused)101 rdrand_modevent(module_t mod, int type, void *unused)
102 {
103 int error = 0;
104
105 switch (type) {
106 case MOD_LOAD:
107 if (cpu_feature2 & CPUID2_RDRAND) {
108 random_source_register(&random_ivy);
109 printf("random: fast provider: \"%s\"\n", random_ivy.rs_ident);
110 }
111 break;
112
113 case MOD_UNLOAD:
114 if (cpu_feature2 & CPUID2_RDRAND)
115 random_source_deregister(&random_ivy);
116 break;
117
118 case MOD_SHUTDOWN:
119 break;
120
121 default:
122 error = EOPNOTSUPP;
123 break;
124
125 }
126
127 return (error);
128 }
129
130 DEV_MODULE(rdrand, rdrand_modevent, NULL);
131 MODULE_VERSION(rdrand, 1);
132 MODULE_DEPEND(rdrand, random_device, 1, 1, 1);
133