1 /*-
2 * Copyright (c) 2013-2015 Mark R V Murray
3 * Copyright (c) 2013 David E. O'Brien <[email protected]>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer
11 * in this position and unchanged.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 */
28
29 #include <sys/cdefs.h>
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/conf.h>
33 #include <sys/lock.h>
34 #include <sys/malloc.h>
35 #include <sys/module.h>
36 #include <sys/random.h>
37 #include <sys/systm.h>
38
39 #include <machine/segments.h>
40 #include <machine/pcb.h>
41 #include <machine/md_var.h>
42 #include <machine/specialreg.h>
43
44 #include <dev/random/randomdev.h>
45
46 static u_int random_nehemiah_read(void *, u_int);
47
48 static struct random_source random_nehemiah = {
49 .rs_ident = "VIA Nehemiah Padlock RNG",
50 .rs_source = RANDOM_PURE_NEHEMIAH,
51 .rs_read = random_nehemiah_read
52 };
53
54 /* This H/W source never stores more than 8 bytes in one go */
55 /* ARGSUSED */
56 static __inline size_t
VIA_RNG_store(void * buf)57 VIA_RNG_store(void *buf)
58 {
59 uint32_t retval = 0;
60 uint32_t rate = 0;
61
62 __asm __volatile(
63 "movl $0,%%edx\n\t"
64 ".byte 0x0f, 0xa7, 0xc0"
65 : "=a" (retval), "+d" (rate), "+D" (buf)
66 :
67 : "memory"
68 );
69 if (rate == 0)
70 return (retval&0x1f);
71 return (0);
72 }
73
74 /* It is specifically allowed that buf is a multiple of sizeof(long) */
75 static u_int
random_nehemiah_read(void * buf,u_int c)76 random_nehemiah_read(void *buf, u_int c)
77 {
78 uint8_t *b;
79 size_t count, ret;
80 uint64_t tmp;
81
82 fpu_kern_enter(curthread, NULL, FPU_KERN_NORMAL | FPU_KERN_NOCTX);
83 b = buf;
84 for (count = c; count > 0; count -= ret) {
85 ret = MIN(VIA_RNG_store(&tmp), count);
86 memcpy(b, &tmp, ret);
87 b += ret;
88 }
89 fpu_kern_leave(curthread, NULL);
90
91 return (c);
92 }
93
94 static int
nehemiah_modevent(module_t mod,int type,void * unused)95 nehemiah_modevent(module_t mod, int type, void *unused)
96 {
97 int error = 0;
98
99 switch (type) {
100 case MOD_LOAD:
101 if (via_feature_rng & VIA_HAS_RNG) {
102 random_source_register(&random_nehemiah);
103 printf("random: fast provider: \"%s\"\n", random_nehemiah.rs_ident);
104 }
105 break;
106
107 case MOD_UNLOAD:
108 if (via_feature_rng & VIA_HAS_RNG) {
109 random_source_deregister(&random_nehemiah);
110 }
111 break;
112
113 case MOD_SHUTDOWN:
114 break;
115
116 default:
117 error = EOPNOTSUPP;
118 break;
119
120 }
121
122 return (error);
123 }
124
125 static moduledata_t nehemiah_mod = {
126 "nehemiah",
127 nehemiah_modevent,
128 0
129 };
130
131 DECLARE_MODULE(nehemiah, nehemiah_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH);
132 MODULE_VERSION(nehemiah, 1);
133 MODULE_DEPEND(nehemiah, random_harvestq, 1, 1, 1);
134