svn commit: r240921 - head/sys/kern

[John Baldwin]

Author: jhb
Date: Tue Sep 25 14:55:46 2012
New Revision: 240921
URL: http://svn.freebsd.org/changeset/base/240921

Log:
  Add optional entropy harvesting for software interrupts in swi_sched()
  as controlled by kern.random.sys.harvest.swi.  SWI harvesting feeds into
  the interrupt FIFO and each event is estimated as providing a single bit of
  entropy.
  
  Reviewed by:	markm, obrien
  MFC after:	2 weeks

Modified:
  head/sys/kern/kern_intr.c

Modified: head/sys/kern/kern_intr.c
==============================================================================
--- head/sys/kern/kern_intr.c	Tue Sep 25 13:34:09 2012	(r240920)
+++ head/sys/kern/kern_intr.c	Tue Sep 25 14:55:46 2012	(r240921)
@@ -1144,11 +1144,21 @@ swi_sched(void *cookie, int flags)
 {
 	struct intr_handler *ih = (struct intr_handler *)cookie;
 	struct intr_event *ie = ih->ih_event;
+	struct intr_entropy entropy;
 	int error;
 
 	CTR3(KTR_INTR, "swi_sched: %s %s need=%d", ie->ie_name, ih->ih_name,
 	    ih->ih_need);
 
+	if (harvest.swi) {
+		CTR2(KTR_INTR, "swi_sched: pid %d (%s) gathering entropy",
+		    curproc->p_pid, curthread->td_name);
+		entropy.event = (uintptr_t)ih;
+		entropy.td = curthread;
+		random_harvest(&entropy, sizeof(entropy), 1, 0,
+		    RANDOM_INTERRUPT);
+	}
+
 	/*
 	 * Set ih_need for this handler so that if the ithread is already
 	 * running it will execute this handler on the next pass.  Otherwise,