freebsd-dev/sys/dev/random/harvest.c

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/*-
* Copyright (c) 2000 Mark R V Murray
* All rights reserved.
*
* 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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/poll.h>
#include <sys/selinfo.h>
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#include <sys/sysctl.h>
#include <sys/random.h>
#include <machine/cpu.h>
#include <dev/random/randomdev.h>
static int read_random_phony(void *, int);
/* Structure holding the desired entropy sources */
struct harvest_select harvest = { 0, 0, 0 };
/* hold the address of the routine which is actually called if
* the randomdev is loaded
*/
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static void (*reap_func)(u_int64_t, void *, u_int, u_int, u_int, enum esource)
= NULL;
static int (*read_func)(void *, int) = read_random_phony;
/* Initialise the harvester at load time */
void
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random_init_harvester(void (*reaper)(u_int64_t, void *, u_int, u_int, u_int,
enum esource), int (*reader)(void *, int))
{
reap_func = reaper;
read_func = reader;
}
/* Deinitialise the harvester at unload time */
void
random_deinit_harvester(void)
{
reap_func = NULL;
read_func = read_random_phony;
}
/* Entropy harvesting routine. This is supposed to be fast; do
* not do anything slow in here!
* Implemented as in indirect call to allow non-inclusion of
* the entropy device.
*/
void
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random_harvest(void *entropy, u_int count, u_int bits, u_int frac,
enum esource origin)
{
if (reap_func)
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(*reap_func)(get_cyclecount(), entropy, count, bits, frac,
origin);
}
/* Userland-visible version of read_random */
int
read_random(void *buf, int count)
{
return (*read_func)(buf, count);
}
/* If the entropy device is not loaded, make a token effort to
* provide _some_ kind of randomness. This should only be used
* inside other RNG's, like arc4random(9).
*/
static int
read_random_phony(void *buf, int count)
{
u_long randval;
int size, i;
static int initialised = 0;
/* Try to give random(9) a half decent initialisation
* DO NOT make the mistake of thinking this is secure!!
*/
if (!initialised)
srandom((u_long)get_cyclecount());
/* Fill buf[] with random(9) output */
for (i = 0; i < count; i+= (int)sizeof(u_long)) {
randval = random();
size = (count - i) < (int)sizeof(u_long)
? (count - i)
: sizeof(u_long);
memcpy(&((char *)buf)[i], &randval, (size_t)size);
}
return count;
}
/* Helper routine to enable kthread_exit() to work while the module is
* being (or has been) unloaded.
* This routine is in this file because it is always linked into the kernel,
* and will thus never be unloaded. This is critical for unloadable modules
* that have threads.
*/
void
random_set_wakeup_exit(void *control)
{
wakeup(control);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
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mtx_lock(&Giant);
kthread_exit(0);
/* NOTREACHED */
}