2 * Copyright (c) 2012 Alex Hornung <alex@alexhornung.com>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in
13 * the documentation and/or other materials provided with the
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
19 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
20 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
22 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
24 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
33 #include <sys/libkern.h>
34 #include <sys/module.h>
35 #include <sys/malloc.h>
37 #include <sys/random.h>
39 #include <machine/specialreg.h>
41 #define RDRAND_ALIGN(p) (void *)(roundup2((uintptr_t)(p), 16))
45 struct callout sc_rng_co;
50 static void rdrand_rng_harvest(void *);
51 int rdrand_rng(uint8_t *out, int limit);
54 MALLOC_DEFINE(M_RDRAND, "rdrand_data", "RdRand Data");
58 rdrand_identify(driver_t *drv, device_t parent)
61 /* NB: order 10 is so we get attached after h/w devices */
62 if (device_find_child(parent, "rdrand", -1) == NULL &&
63 BUS_ADD_CHILD(parent, parent, 10, "rdrand", -1) == 0)
64 panic("rdrand: could not attach");
69 rdrand_probe(device_t dev)
72 if ((cpu_feature2 & CPUID2_RDRAND) == 0) {
73 device_printf(dev, "No RdRand support.\n");
77 device_set_desc(dev, "RdRand RNG");
83 rdrand_attach(device_t dev)
85 struct rdrand_softc *sc;
87 sc = device_get_softc(dev);
90 sc->sc_rng_ticks = hz/100;
94 callout_init_mp(&sc->sc_rng_co);
95 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
96 rdrand_rng_harvest, sc);
103 rdrand_detach(device_t dev)
105 struct rdrand_softc *sc;
107 sc = device_get_softc(dev);
109 callout_stop_sync(&sc->sc_rng_co);
115 static int random_count = 512; /* in bytes */
118 rdrand_rng_harvest(void *arg)
120 struct rdrand_softc *sc = arg;
121 uint8_t randomness[2048];
122 uint8_t *arandomness; /* randomness aligned */
125 arandomness = RDRAND_ALIGN(randomness);
126 cnt = rdrand_rng(arandomness, random_count);
128 for (i = 0; i < cnt; i++)
129 add_true_randomness((int)arandomness[i]);
131 callout_reset(&sc->sc_rng_co, sc->sc_rng_ticks,
132 rdrand_rng_harvest, sc);
136 static device_method_t rdrand_methods[] = {
137 DEVMETHOD(device_identify, rdrand_identify),
138 DEVMETHOD(device_probe, rdrand_probe),
139 DEVMETHOD(device_attach, rdrand_attach),
140 DEVMETHOD(device_detach, rdrand_detach),
146 static driver_t rdrand_driver = {
149 sizeof(struct rdrand_softc),
152 static devclass_t rdrand_devclass;
154 DRIVER_MODULE(rdrand, nexus, rdrand_driver, rdrand_devclass, NULL, NULL);
155 MODULE_VERSION(rdrand, 1);
156 MODULE_DEPEND(rdrand, crypto, 1, 1, 1);