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, 10 insertions, 10 deletions

diff --git a/sys/net/pf_table.c b/sys/net/pf_table.c
index 487207dcd0e..07ec189a12f 100644
--- a/sys/net/pf_table.c
+++ b/sys/net/pf_table.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pf_table.c,v 1.132 2020/06/04 04:27:51 yasuoka Exp $	*/
+/*	$OpenBSD: pf_table.c,v 1.133 2020/06/24 22:03:43 cheloha Exp $	*/
 
 /*
  * Copyright (c) 2002 Cedric Berger
@@ -271,7 +271,7 @@ pfr_add_addrs(struct pfr_table *tbl, struct pfr_addr *addr, int size,
 	struct pfr_kentry	*p, *q;
 	struct pfr_addr		 ad;
 	int			 i, rv, xadd = 0;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	ACCEPT_FLAGS(flags, PFR_FLAG_DUMMY | PFR_FLAG_FEEDBACK);
 	if (pfr_validate_table(tbl, 0, flags & PFR_FLAG_USERIOCTL))
@@ -438,7 +438,7 @@ pfr_set_addrs(struct pfr_table *tbl, struct pfr_addr *addr, int size,
 	struct pfr_kentry	*p, *q;
 	struct pfr_addr		 ad;
 	int			 i, rv, xadd = 0, xdel = 0, xchange = 0;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	ACCEPT_FLAGS(flags, PFR_FLAG_DUMMY | PFR_FLAG_FEEDBACK);
 	if (pfr_validate_table(tbl, ignore_pfrt_flags, flags &
@@ -630,7 +630,7 @@ pfr_get_astats(struct pfr_table *tbl, struct pfr_astats *addr, int *size,
 	struct pfr_walktree	 w;
 	struct pfr_kentryworkq	 workq;
 	int			 rv;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	if (pfr_validate_table(tbl, 0, 0))
 		return (EINVAL);
@@ -703,7 +703,7 @@ pfr_clr_astats(struct pfr_table *tbl, struct pfr_addr *addr, int size,
 	}
 
 	if (!(flags & PFR_FLAG_DUMMY)) {
-		pfr_clstats_kentries(&workq, time_second, 0);
+		pfr_clstats_kentries(&workq, gettime(), 0);
 	}
 	if (nzero != NULL)
 		*nzero = xzero;
@@ -1285,7 +1285,7 @@ pfr_add_tables(struct pfr_table *tbl, int size, int *nadd, int flags)
 	struct pfr_ktableworkq	 addq, changeq;
 	struct pfr_ktable	*p, *q, *r, key;
 	int			 i, rv, xadd = 0;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	ACCEPT_FLAGS(flags, PFR_FLAG_DUMMY);
 	SLIST_INIT(&addq);
@@ -1438,7 +1438,7 @@ pfr_get_tstats(struct pfr_table *filter, struct pfr_tstats *tbl, int *size,
 	struct pfr_ktable	*p;
 	struct pfr_ktableworkq	 workq;
 	int			 n, nn;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	/* XXX PFR_FLAG_CLSTATS disabled */
 	ACCEPT_FLAGS(flags, PFR_FLAG_ALLRSETS);
@@ -1479,7 +1479,7 @@ pfr_clr_tstats(struct pfr_table *tbl, int size, int *nzero, int flags)
 	struct pfr_ktableworkq	 workq;
 	struct pfr_ktable	*p, key;
 	int			 i, xzero = 0;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	ACCEPT_FLAGS(flags, PFR_FLAG_DUMMY | PFR_FLAG_ADDRSTOO);
 	SLIST_INIT(&workq);
@@ -1732,7 +1732,7 @@ pfr_ina_commit(struct pfr_table *trs, u_int32_t ticket, int *nadd,
 	struct pfr_ktableworkq	 workq;
 	struct pf_ruleset	*rs;
 	int			 xadd = 0, xchange = 0;
-	time_t			 tzero = time_second;
+	time_t			 tzero = gettime();
 
 	ACCEPT_FLAGS(flags, PFR_FLAG_DUMMY);
 	rs = pf_find_ruleset(trs->pfrt_anchor);
@@ -2226,7 +2226,7 @@ pfr_attach_table(struct pf_ruleset *rs, char *name, int intr)
 		strlcpy(tbl.pfrt_anchor, ac->path, sizeof(tbl.pfrt_anchor));
 	kt = pfr_lookup_table(&tbl);
 	if (kt == NULL) {
-		kt = pfr_create_ktable(&tbl, time_second, 1, intr);
+		kt = pfr_create_ktable(&tbl, gettime(), 1, intr);
 		if (kt == NULL)
 			return (NULL);
 		if (ac != NULL) {