2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
37 #include <machine/atomic.h>
38 #include "libc_private.h"
41 tc_delta(const struct vdso_timehands *th, u_int *delta)
46 error = __vdso_gettc(th, &tc);
48 *delta = (tc - th->th_offset_count) & th->th_counter_mask;
53 * Calculate the absolute or boot-relative time from the
54 * machine-specific fast timecounter and the published timehands
55 * structure read from the shared page.
57 * The lockless reading scheme is similar to the one used to read the
58 * in-kernel timehands, see sys/kern/kern_tc.c:binuptime(). This code
59 * is based on the kernel implementation.
62 binuptime(struct bintime *bt, struct vdso_timekeep *tk, int abs)
64 struct vdso_timehands *th;
67 u_int delta, scale_bits;
74 curr = atomic_load_acq_32(&tk->tk_current);
75 th = &tk->tk_th[curr];
76 gen = atomic_load_acq_32(&th->th_gen);
78 error = tc_delta(th, &delta);
85 scale_bits = ffsl(scale);
87 scale_bits = ffsll(scale);
89 if (__predict_false(scale_bits + fls(delta) > 63)) {
90 x = (scale >> 32) * delta;
93 bintime_addx(bt, x << 32);
95 bintime_addx(bt, scale * delta);
97 bintime_add(bt, &th->th_boottime);
100 * Ensure that the load of th_offset is completed
101 * before the load of th_gen.
103 atomic_thread_fence_acq();
104 } while (curr != tk->tk_current || gen == 0 || gen != th->th_gen);
108 static struct vdso_timekeep *tk;
110 #pragma weak __vdso_gettimeofday
112 __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
120 error = __vdso_gettimekeep(&tk);
121 if (error != 0 || tk == NULL)
124 if (tk->tk_ver != VDSO_TK_VER_CURR)
126 error = binuptime(&bt, tk, 1);
129 bintime2timeval(&bt, tv);
133 #pragma weak __vdso_clock_gettime
135 __vdso_clock_gettime(clockid_t clock_id, struct timespec *ts)
141 error = _elf_aux_info(AT_TIMEKEEP, &tk, sizeof(tk));
142 if (error != 0 || tk == NULL)
145 if (tk->tk_ver != VDSO_TK_VER_CURR)
149 case CLOCK_REALTIME_PRECISE:
150 case CLOCK_REALTIME_FAST:
154 case CLOCK_MONOTONIC:
155 case CLOCK_MONOTONIC_PRECISE:
156 case CLOCK_MONOTONIC_FAST:
158 case CLOCK_UPTIME_PRECISE:
159 case CLOCK_UPTIME_FAST:
165 error = binuptime(&bt, tk, abs);
168 bintime2timespec(&bt, ts);
169 if (clock_id == CLOCK_SECOND)