1/*-
2 * Copyright (c) 2013 The FreeBSD Foundation
3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
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/lock.h>
39#include <sys/malloc.h>
40#include <sys/module.h>
41#include <sys/random.h>
42#include <sys/selinfo.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#include <dev/random/randomdev_soft.h>
50#include <dev/random/random_harvestq.h>
51#include <dev/random/live_entropy_sources.h>
52#include <dev/random/random_adaptors.h>
53
54#define	RETRY_COUNT	10
55
56static int random_ivy_read(void *, int);
57
58static struct random_hardware_source random_ivy = {
59	.ident = "Hardware, Intel IvyBridge+ RNG",
60	.source = RANDOM_PURE_RDRAND,
61	.read = random_ivy_read
62};
63
64static inline int
65ivy_rng_store(long *buf)
66{
67#ifdef __GNUCLIKE_ASM
68	long tmp;
69	int retry;
70
71	retry = RETRY_COUNT;
72	__asm __volatile(
73	    "1:\n\t"
74	    "rdrand	%2\n\t"	/* read randomness into tmp */
75	    "jb		2f\n\t" /* CF is set on success, exit retry loop */
76	    "dec	%0\n\t" /* otherwise, retry-- */
77	    "jne	1b\n\t" /* and loop if retries are not exhausted */
78	    "jmp	3f\n"	/* failure, retry is 0, used as return value */
79	    "2:\n\t"
80	    "mov	%2,%1\n\t" /* *buf = tmp */
81	    "3:"
82	    : "+q" (retry), "=m" (*buf), "=q" (tmp) : : "cc");
83	return (retry);
84#else /* __GNUCLIKE_ASM */
85	return (0);
86#endif
87}
88
89static int
90random_ivy_read(void *buf, int c)
91{
92	long *b;
93	int count;
94
95	KASSERT(c % sizeof(long) == 0, ("partial read %d", c));
96	for (b = buf, count = c; count > 0; count -= sizeof(long), b++) {
97		if (ivy_rng_store(b) == 0)
98			break;
99	}
100	return (c - count);
101}
102
103static int
104rdrand_modevent(module_t mod, int type, void *unused)
105{
106	int error = 0;
107
108	switch (type) {
109	case MOD_LOAD:
110		if (cpu_feature2 & CPUID2_RDRAND)
111			live_entropy_source_register(&random_ivy);
112		else
113#ifndef KLD_MODULE
114			if (bootverbose)
115#endif
116				printf("%s: RDRAND is not present\n",
117				    random_ivy.ident);
118		break;
119
120	case MOD_UNLOAD:
121		if (cpu_feature2 & CPUID2_RDRAND)
122			live_entropy_source_deregister(&random_ivy);
123		break;
124
125	case MOD_SHUTDOWN:
126		break;
127
128	default:
129		error = EOPNOTSUPP;
130		break;
131
132	}
133
134	return (error);
135}
136
137LIVE_ENTROPY_SRC_MODULE(random_rdrand, rdrand_modevent, 1);
138