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/*-
* Copyright (c) 2018 Justin Hibbits
* Copyright (c) 2013 The FreeBSD Foundation
* Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
* Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
* All rights reserved.
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/random.h>
#include <sys/systm.h>
#include <machine/cpu.h>
#include <machine/md_var.h>
#include <dev/random/randomdev.h>
/*
* Power ISA 3.0 adds a "darn" instruction (Deliver A Random Number). The RNG
* backing this instruction conforms to NIST SP800-90B and SP800-90C at the
* point of hardware design, and provides a minimum of 0.5 bits of entropy per
* bit.
*/
#define RETRY_COUNT 10
static u_int random_darn_read(void *, u_int);
static const struct random_source random_darn = {
.rs_ident = "PowerISA DARN random number generator",
.rs_source = RANDOM_PURE_DARN,
.rs_read = random_darn_read
};
static inline int
darn_rng_store(u_long *buf)
{
u_long rndval;
int retry;
for (retry = RETRY_COUNT; retry > 0; --retry) {
/* "DARN %rN, 1" instruction */
/*
* Arguments for DARN: rN and "L", where "L" can be one of:
* 0 - 32-bit conditional random number
* 1 - Conditional random number (conditioned to remove bias)
* 2 - Raw random number (unprocessed, may include bias)
* 3 - Reserved
*/
__asm __volatile(".long 0x7c0105e6 | (%0 << 21)" :
"+r"(rndval));
if (rndval != ~0)
break;
}
*buf = rndval;
return (retry);
}
/* It is required that buf length is a multiple of sizeof(u_long). */
static u_int
random_darn_read(void *buf, u_int c)
{
u_long *b, rndval;
u_int count;
KASSERT(c % sizeof(*b) == 0, ("partial read %d", c));
b = buf;
for (count = c; count > 0; count -= sizeof(*b)) {
if (darn_rng_store(&rndval) == 0)
break;
*b++ = rndval;
}
return (c - count);
}
static int
darn_modevent(module_t mod, int type, void *unused)
{
int error = 0;
switch (type) {
case MOD_LOAD:
if (cpu_features2 & PPC_FEATURE2_DARN) {
random_source_register(&random_darn);
printf("random: fast provider: \"%s\"\n", random_darn.rs_ident);
}
break;
case MOD_UNLOAD:
if (cpu_features2 & PPC_FEATURE2_DARN)
random_source_deregister(&random_darn);
break;
case MOD_SHUTDOWN:
break;
default:
error = EOPNOTSUPP;
break;
}
return (error);
}
static moduledata_t darn_mod = {
"darn",
darn_modevent,
0
};
DECLARE_MODULE(darn, darn_mod, SI_SUB_RANDOM, SI_ORDER_FOURTH);
MODULE_VERSION(darn, 1);
MODULE_DEPEND(darn, random_harvestq, 1, 1, 1);
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