1 /*-
2 * Copyright (c) 2013-2015 Mark R V Murray
3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
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/param.h>
30 #include <sys/kernel.h>
31 #include <sys/conf.h>
32 #include <sys/lock.h>
33 #include <sys/malloc.h>
34 #include <sys/module.h>
35 #include <sys/random.h>
36 #include <sys/systm.h>
37
38 #include <machine/segments.h>
39 #include <machine/pcb.h>
40 #include <machine/md_var.h>
41 #include <machine/specialreg.h>
42
43 #include <dev/random/randomdev.h>
44
45 static u_int random_nehemiah_read(void *, u_int);
46
47 static struct random_source random_nehemiah = {
48 .rs_ident = "VIA Nehemiah Padlock RNG",
49 .rs_source = RANDOM_PURE_NEHEMIAH,
50 .rs_read = random_nehemiah_read
51 };
52
53 /* This H/W source never stores more than 8 bytes in one go */
54 /* ARGSUSED */
55 static __inline size_t
VIA_RNG_store(void * buf)56 VIA_RNG_store(void *buf)
57 {
58 uint32_t retval = 0;
59 uint32_t rate = 0;
60
61 __asm __volatile(
62 "movl $0,%%edx\n\t"
63 ".byte 0x0f, 0xa7, 0xc0"
64 : "=a" (retval), "+d" (rate), "+D" (buf)
65 :
66 : "memory"
67 );
68 if (rate == 0)
69 return (retval&0x1f);
70 return (0);
71 }
72
73 /* It is specifically allowed that buf is a multiple of sizeof(long) */
74 static u_int
random_nehemiah_read(void * buf,u_int c)75 random_nehemiah_read(void *buf, u_int c)
76 {
77 uint8_t *b;
78 size_t count, ret;
79 uint64_t tmp;
80
81 fpu_kern_enter(curthread, NULL, FPU_KERN_NORMAL | FPU_KERN_NOCTX);
82 b = buf;
83 for (count = c; count > 0; count -= ret) {
84 ret = MIN(VIA_RNG_store(&tmp), count);
85 memcpy(b, &tmp, ret);
86 b += ret;
87 }
88 fpu_kern_leave(curthread, NULL);
89
90 return (c);
91 }
92
93 static int
nehemiah_modevent(module_t mod,int type,void * unused)94 nehemiah_modevent(module_t mod, int type, void *unused)
95 {
96 int error = 0;
97
98 switch (type) {
99 case MOD_LOAD:
100 if (via_feature_rng & VIA_HAS_RNG) {
101 random_source_register(&random_nehemiah);
102 printf("random: fast provider: \"%s\"\n", random_nehemiah.rs_ident);
103 }
104 break;
105
106 case MOD_UNLOAD:
107 if (via_feature_rng & VIA_HAS_RNG) {
108 random_source_deregister(&random_nehemiah);
109 }
110 break;
111
112 case MOD_SHUTDOWN:
113 break;
114
115 default:
116 error = EOPNOTSUPP;
117 break;
118
119 }
120
121 return (error);
122 }
123
124 static moduledata_t nehemiah_mod = {
125 "nehemiah",
126 nehemiah_modevent,
127 0
128 };
129
130 DECLARE_MODULE(nehemiah, nehemiah_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH);
131 MODULE_VERSION(nehemiah, 1);
132 MODULE_DEPEND(nehemiah, random_harvestq, 1, 1, 1);
133