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hyperentropy.c revision 1.7.4.1 
      1 /*	$NetBSD: hyperentropy.c,v 1.7.4.1 2015/06/06 14:40:29 skrll Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2014 Antti Kantee.  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  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     16  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include <sys/cdefs.h>
     29 __KERNEL_RCSID(0, "$NetBSD: hyperentropy.c,v 1.7.4.1 2015/06/06 14:40:29 skrll Exp $");
     30 
     31 #include <sys/param.h>
     32 #include <sys/atomic.h>
     33 #include <sys/kmem.h>
     34 #include <sys/rndpool.h>
     35 #include <sys/rndsource.h>
     36 
     37 #include <rump/rumpuser.h>
     38 
     39 #include "rump_private.h"
     40 
     41 static krndsource_t rndsrc;
     42 static volatile unsigned hyperentropy_wanted;
     43 static void *feedrandom_softint;
     44 
     45 #define MAXGET (RND_POOLBITS/NBBY)
     46 static void
     47 feedrandom(size_t bytes)
     48 {
     49 	uint8_t *rnddata;
     50 	size_t dsize;
     51 
     52 	rnddata = kmem_intr_alloc(MAXGET, KM_SLEEP);
     53 	if (rumpuser_getrandom(rnddata, MIN(MAXGET, bytes),
     54 	    RUMPUSER_RANDOM_HARD|RUMPUSER_RANDOM_NOWAIT, &dsize) == 0)
     55 		rnd_add_data(&rndsrc, rnddata, dsize, NBBY*dsize);
     56 	kmem_intr_free(rnddata, MAXGET);
     57 }
     58 
     59 static void
     60 feedrandom_intr(void *cookie __unused)
     61 {
     62 
     63 	feedrandom(atomic_swap_uint(&hyperentropy_wanted, 0));
     64 }
     65 
     66 static void
     67 feedrandom_cb(size_t bytes, void *cookie __unused)
     68 {
     69 	unsigned old, new;
     70 
     71 	do {
     72 		old = hyperentropy_wanted;
     73 		new = ((MAXGET - old) < bytes? MAXGET : (old + bytes));
     74 	} while (atomic_cas_uint(&hyperentropy_wanted, old, new) != old);
     75 
     76 	softint_schedule(feedrandom_softint);
     77 }
     78 
     79 void
     80 rump_hyperentropy_init(void)
     81 {
     82 
     83 	if (rump_threads) {
     84 		feedrandom_softint =
     85 		    softint_establish(SOFTINT_CLOCK|SOFTINT_MPSAFE,
     86 			feedrandom_intr, NULL);
     87 		KASSERT(feedrandom_softint != NULL);
     88 		rndsource_setcb(&rndsrc, feedrandom_cb, &rndsrc);
     89 		rnd_attach_source(&rndsrc, "rump_hyperent", RND_TYPE_VM,
     90 		    RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
     91 	} else {
     92 		/* without threads, just fill the pool */
     93 		rnd_attach_source(&rndsrc, "rump_hyperent", RND_TYPE_VM,
     94 		    RND_FLAG_COLLECT_VALUE);
     95 		feedrandom(MAXGET);
     96 	}
     97 }
     98