kernel: use gettime(9)/getuptime(9) in lieu of time_second(9)/time_uptime(9)

time_second(9) and time_uptime(9) are widely used in the kernel to
quickly get the system UTC or system uptime as a time_t.  However,
time_t is 64-bit everywhere, so it is not generally safe to use them
on 32-bit platforms: you have a split-read problem if your hardware
cannot perform atomic 64-bit reads.

This patch replaces time_second(9) with gettime(9), a safer successor
interface, throughout the kernel.  Similarly, time_uptime(9) is replaced
with getuptime(9).

There is a performance cost on 32-bit platforms in exchange for
eliminating the split-read problem: instead of two register reads you
now have a lockless read loop to pull the values from the timehands.
This is really not *too* bad in the grand scheme of things, but
compared to what we were doing before it is several times slower.

There is no performance cost on 64-bit (__LP64__) platforms.

With input from visa@, dlg@, and tedu@.

Several bugs squashed by visa@.

ok kettenis@

1 files changed, 13 insertions, 13 deletions

diff --git a/sys/net/if_pfsync.c b/sys/net/if_pfsync.c
index ce9b909d4e7..515504d38e9 100644
--- a/sys/net/if_pfsync.c
+++ b/sys/net/if_pfsync.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_pfsync.c,v 1.270 2020/04/12 11:56:52 mpi Exp $	*/
+/*	$OpenBSD: if_pfsync.c,v 1.271 2020/06/24 22:03:43 cheloha Exp $	*/
 
 /*
  * Copyright (c) 2002 Michael Shalayeff
@@ -590,8 +590,8 @@ pfsync_state_import(struct pfsync_state *sp, int flags)
 
 	/* copy to state */
 	bcopy(&sp->rt_addr, &st->rt_addr, sizeof(st->rt_addr));
-	st->creation = time_uptime - ntohl(sp->creation);
-	st->expire = time_uptime;
+	st->creation = getuptime() - ntohl(sp->creation);
+	st->expire = getuptime();
 	if (ntohl(sp->expire)) {
 		u_int32_t timeout;
 
@@ -622,7 +622,7 @@ pfsync_state_import(struct pfsync_state *sp, int flags)
 	st->anchor.ptr = NULL;
 	st->rt_kif = NULL;
 
-	st->pfsync_time = time_uptime;
+	st->pfsync_time = getuptime();
 	st->sync_state = PFSYNC_S_NONE;
 
 	refcnt_init(&st->refcnt);
@@ -962,10 +962,10 @@ pfsync_in_upd(caddr_t buf, int len, int count, int flags)
 		if (sync < 2) {
 			pfsync_alloc_scrub_memory(&sp->dst, &st->dst);
 			pf_state_peer_ntoh(&sp->dst, &st->dst);
-			st->expire = time_uptime;
+			st->expire = getuptime();
 			st->timeout = sp->timeout;
 		}
-		st->pfsync_time = time_uptime;
+		st->pfsync_time = getuptime();
 
 		if (sync) {
 			pfsyncstat_inc(pfsyncs_stale);
@@ -1036,10 +1036,10 @@ pfsync_in_upd_c(caddr_t buf, int len, int count, int flags)
 		if (sync < 2) {
 			pfsync_alloc_scrub_memory(&up->dst, &st->dst);
 			pf_state_peer_ntoh(&up->dst, &st->dst);
-			st->expire = time_uptime;
+			st->expire = getuptime();
 			st->timeout = up->timeout;
 		}
-		st->pfsync_time = time_uptime;
+		st->pfsync_time = getuptime();
 
 		if (sync) {
 			pfsyncstat_inc(pfsyncs_stale);
@@ -1160,7 +1160,7 @@ pfsync_in_bus(caddr_t buf, int len, int count, int flags)
 		break;
 
 	case PFSYNC_BUS_END:
-		if (time_uptime - ntohl(bus->endtime) >=
+		if (getuptime() - ntohl(bus->endtime) >=
 		    sc->sc_ureq_sent) {
 			/* that's it, we're happy */
 			sc->sc_ureq_sent = 0;
@@ -1947,7 +1947,7 @@ pfsync_update_state_locked(struct pf_state *st)
 		    st->sync_state);
 	}
 
-	if (sync || (time_uptime - st->pfsync_time) < 2)
+	if (sync || (getuptime() - st->pfsync_time) < 2)
 		schednetisr(NETISR_PFSYNC);
 }
 
@@ -1998,7 +1998,7 @@ pfsync_request_full_update(struct pfsync_softc *sc)
 {
 	if (sc->sc_sync_if && ISSET(sc->sc_if.if_flags, IFF_RUNNING)) {
 		/* Request a full state table update. */
-		sc->sc_ureq_sent = time_uptime;
+		sc->sc_ureq_sent = getuptime();
 #if NCARP > 0
 		if (!sc->sc_link_demoted && pfsync_sync_ok)
 			carp_group_demote_adj(&sc->sc_if, 1,
@@ -2306,7 +2306,7 @@ pfsync_bulk_start(void)
 	if (TAILQ_EMPTY(&state_list))
 		pfsync_bulk_status(PFSYNC_BUS_END);
 	else {
-		sc->sc_ureq_received = time_uptime;
+		sc->sc_ureq_received = getuptime();
 
 		if (sc->sc_bulk_next == NULL)
 			sc->sc_bulk_next = TAILQ_FIRST(&state_list);
@@ -2379,7 +2379,7 @@ pfsync_bulk_status(u_int8_t status)
 	r.subh.count = htons(1);
 
 	r.bus.creatorid = pf_status.hostid;
-	r.bus.endtime = htonl(time_uptime - sc->sc_ureq_received);
+	r.bus.endtime = htonl(getuptime() - sc->sc_ureq_received);
 	r.bus.status = status;
 
 	pfsync_send_plus(&r, sizeof(r));