Index: kern/kern_synch.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_synch.c,v
retrieving revision 1.308
diff -p -r1.308 kern_synch.c
*** kern/kern_synch.c	28 Feb 2014 10:16:51 -0000	1.308
--- kern/kern_synch.c	29 Jan 2015 02:55:55 -0000
*************** updatertime(lwp_t *l, const struct binti
*** 453,458 ****
--- 453,483 ----
  	if (__predict_false(l->l_flag & LW_IDLE))
  		return;
  
+ #if defined(__sparc__)
+     {
+ 	/*
+ 	 * "now - stime" becomes negative sometimes, which it shouldn't.
+ 	 * try to figure out where it comes from, because we don't ever
+ 	 * add a negative value from the timecounter side.
+ 	 */
+ 	struct bintime delta = *now;
+ 	bintime_sub(&delta, &l->l_stime);
+         if (delta.sec < 0) {
+ 		log(LOG_DEBUG, "cpu%u: (%u.%u:%s) "
+ 			       "delta.sec = %lld, delta.frac = %llu, "
+ 			       "now.sec = %lld, now.frac = %llu, "
+ 			       "l_stime.sec = %lld, l_stime.frac = %llu, "
+ 			       "RA = %p\n",
+ 			       cpu_number(), l->l_proc->p_pid, l->l_lid,
+ 			       l->l_name ? l->l_name : l->l_proc->p_comm,
+ 			       (long long)delta.sec, (unsigned long long)delta.frac,
+ 			       (long long)now->sec, (unsigned long long)now->frac,
+ 			       (long long)l->l_stime.sec,
+ 			       (unsigned long long)l->l_stime.frac,
+ 			       __builtin_return_address(0));
+ 	}
+     }
+ #endif
  	/* rtime += now - stime */
  	bintime_add(&l->l_rtime, now);
  	bintime_sub(&l->l_rtime, &l->l_stime);
Index: kern/kern_tc.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_tc.c,v
retrieving revision 1.46
diff -p -r1.46 kern_tc.c
*** kern/kern_tc.c	14 Sep 2013 20:52:43 -0000	1.46
--- kern/kern_tc.c	29 Jan 2015 02:55:55 -0000
*************** tc_windup(void)
*** 739,744 ****
--- 739,750 ----
  		ncount = 0;
  	th->th_offset_count += delta;
  	bintime_addx(&th->th_offset, th->th_scale * delta);
+ #ifdef __sparc__
+ if (delta & 0x80000000)
+   log(LOG_DEBUG, "cpu%u: (%u.%u:%s) tc_delta() gave: %x (th_offset_count now %llx)\n",
+     cpu_number(), curlwp->l_proc->p_pid, curlwp->l_lid, curlwp->l_name ? curlwp->l_name : curlwp->l_proc->p_comm,
+     delta, (unsigned long long)th->th_offset_count);
+ #endif
  
  	/*
  	 * Hardware latching timecounters may not generate interrupts on