2 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
34 #include <machine/atomic.h>
35 #include "libc_private.h"
38 tc_delta(const struct vdso_timehands *th, u_int *delta)
43 error = __vdso_gettc(th, &tc);
45 *delta = (tc - th->th_offset_count) & th->th_counter_mask;
50 * Calculate the absolute or boot-relative time from the
51 * machine-specific fast timecounter and the published timehands
52 * structure read from the shared page.
54 * The lockless reading scheme is similar to the one used to read the
55 * in-kernel timehands, see sys/kern/kern_tc.c:binuptime(). This code
56 * is based on the kernel implementation.
59 binuptime(struct bintime *bt, struct vdso_timekeep *tk, int abs)
61 struct vdso_timehands *th;
70 curr = atomic_load_acq_32(&tk->tk_current);
71 th = &tk->tk_th[curr];
72 gen = atomic_load_acq_32(&th->th_gen);
74 error = tc_delta(th, &delta);
79 bintime_addx(bt, th->th_scale * delta);
81 bintime_add(bt, &th->th_boottime);
84 * Ensure that the load of th_offset is completed
85 * before the load of th_gen.
87 atomic_thread_fence_acq();
88 } while (curr != tk->tk_current || gen == 0 || gen != th->th_gen);
92 static struct vdso_timekeep *tk;
94 #pragma weak __vdso_gettimeofday
96 __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
104 error = __vdso_gettimekeep(&tk);
105 if (error != 0 || tk == NULL)
108 if (tk->tk_ver != VDSO_TK_VER_CURR)
110 error = binuptime(&bt, tk, 1);
113 bintime2timeval(&bt, tv);
117 #pragma weak __vdso_clock_gettime
119 __vdso_clock_gettime(clockid_t clock_id, struct timespec *ts)
125 error = _elf_aux_info(AT_TIMEKEEP, &tk, sizeof(tk));
126 if (error != 0 || tk == NULL)
129 if (tk->tk_ver != VDSO_TK_VER_CURR)
133 case CLOCK_REALTIME_PRECISE:
134 case CLOCK_REALTIME_FAST:
138 case CLOCK_MONOTONIC:
139 case CLOCK_MONOTONIC_PRECISE:
140 case CLOCK_MONOTONIC_FAST:
142 case CLOCK_UPTIME_PRECISE:
143 case CLOCK_UPTIME_FAST:
149 error = binuptime(&bt, tk, abs);
152 bintime2timespec(&bt, ts);
153 if (clock_id == CLOCK_SECOND)