diff --git a/lib/libc/sys/__vdso_gettimeofday.c b/lib/libc/sys/__vdso_gettimeofday.c
index 4c1f4bda23e1..c1457a54d37e 100644
--- a/lib/libc/sys/__vdso_gettimeofday.c
+++ b/lib/libc/sys/__vdso_gettimeofday.c
@@ -1,173 +1,199 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
  *
  * 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.
  * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/elf.h>
 #include <sys/time.h>
 #include <sys/vdso.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <strings.h>
 #include <time.h>
 #include <machine/atomic.h>
 #include "libc_private.h"
 
 static int
 tc_delta(const struct vdso_timehands *th, u_int *delta)
 {
 	int error;
 	u_int tc;
 
 	error = __vdso_gettc(th, &tc);
 	if (error == 0)
 		*delta = (tc - th->th_offset_count) & th->th_counter_mask;
 	return (error);
 }
 
 /*
  * Calculate the absolute or boot-relative time from the
  * machine-specific fast timecounter and the published timehands
  * structure read from the shared page.
  *
  * The lockless reading scheme is similar to the one used to read the
  * in-kernel timehands, see sys/kern/kern_tc.c:binuptime().  This code
  * is based on the kernel implementation.
  */
 static int
 binuptime(struct bintime *bt, struct vdso_timekeep *tk, bool abs)
 {
 	struct vdso_timehands *th;
 	uint32_t curr, gen;
 	uint64_t scale, x;
 	u_int delta, scale_bits;
 	int error;
 
 	do {
 		if (!tk->tk_enabled)
 			return (ENOSYS);
 
 		curr = atomic_load_acq_32(&tk->tk_current);
 		th = &tk->tk_th[curr];
 		gen = atomic_load_acq_32(&th->th_gen);
 		*bt = th->th_offset;
 		error = tc_delta(th, &delta);
 		if (error == EAGAIN)
 			continue;
 		if (error != 0)
 			return (error);
 		scale = th->th_scale;
 #ifdef _LP64
 		scale_bits = ffsl(scale);
 #else
 		scale_bits = ffsll(scale);
 #endif
 		if (__predict_false(scale_bits + fls(delta) > 63)) {
 			x = (scale >> 32) * delta;
 			scale &= 0xffffffff;
 			bt->sec += x >> 32;
 			bintime_addx(bt, x << 32);
 		}
 		bintime_addx(bt, scale * delta);
 		if (abs)
 			bintime_add(bt, &th->th_boottime);
 
 		/*
 		 * Ensure that the load of th_offset is completed
 		 * before the load of th_gen.
 		 */
 		atomic_thread_fence_acq();
 	} while (curr != tk->tk_current || gen == 0 || gen != th->th_gen);
 	return (0);
 }
 
+static int
+getnanouptime(struct bintime *bt, struct vdso_timekeep *tk)
+{
+	struct vdso_timehands *th;
+	uint32_t curr, gen;
+
+	do {
+		if (!tk->tk_enabled)
+			return (ENOSYS);
+
+		curr = atomic_load_acq_32(&tk->tk_current);
+		th = &tk->tk_th[curr];
+		gen = atomic_load_acq_32(&th->th_gen);
+		*bt = th->th_offset;
+
+		/*
+		 * Ensure that the load of th_offset is completed
+		 * before the load of th_gen.
+		 */
+		atomic_thread_fence_acq();
+	} while (curr != tk->tk_current || gen == 0 || gen != th->th_gen);
+	return (0);
+}
+
 static struct vdso_timekeep *tk;
 
 #pragma weak __vdso_gettimeofday
 int
 __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 {
 	struct bintime bt;
 	int error;
 
 	if (tz != NULL)
 		return (ENOSYS);
 	if (tk == NULL) {
 		error = __vdso_gettimekeep(&tk);
 		if (error != 0 || tk == NULL)
 			return (ENOSYS);
 	}
 	if (tk->tk_ver != VDSO_TK_VER_CURR)
 		return (ENOSYS);
 	error = binuptime(&bt, tk, true);
 	if (error != 0)
 		return (error);
 	bintime2timeval(&bt, tv);
 	return (0);
 }
 
 #pragma weak __vdso_clock_gettime
 int
 __vdso_clock_gettime(clockid_t clock_id, struct timespec *ts)
 {
 	struct bintime bt;
 	int error;
 
 	if (tk == NULL) {
 		error = _elf_aux_info(AT_TIMEKEEP, &tk, sizeof(tk));
 		if (error != 0 || tk == NULL)
 			return (ENOSYS);
 	}
 	if (tk->tk_ver != VDSO_TK_VER_CURR)
 		return (ENOSYS);
 	switch (clock_id) {
 	case CLOCK_REALTIME:
 	case CLOCK_REALTIME_PRECISE:
 	case CLOCK_REALTIME_FAST:
 	case CLOCK_SECOND:
 		error = binuptime(&bt, tk, true);
 		break;
 	case CLOCK_MONOTONIC:
 	case CLOCK_MONOTONIC_PRECISE:
-	case CLOCK_MONOTONIC_FAST:
 	case CLOCK_UPTIME:
 	case CLOCK_UPTIME_PRECISE:
+		error = binuptime(&bt, tk, false);
+		break;
+	case CLOCK_MONOTONIC_FAST:
 	case CLOCK_UPTIME_FAST:
 		error = getnanouptime(&bt, tk);
 		break;
 	default:
 		error = ENOSYS;
 		break;
 	}
 	if (error != 0)
 		return (error);
 	bintime2timespec(&bt, ts);
 	if (clock_id == CLOCK_SECOND)
 		ts->tv_nsec = 0;
 	return (0);
 }