1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 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. 14 * 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 25 * SUCH DAMAGE. 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD$"); 30 31#include <sys/elf.h> 32#include <sys/time.h> 33#include <sys/vdso.h> 34#include <errno.h> 35#include <strings.h> 36#include <time.h> 37#include <machine/atomic.h> 38#include "libc_private.h" 39 40static int 41tc_delta(const struct vdso_timehands *th, u_int *delta) 42{ 43 int error; 44 u_int tc; 45 46 error = __vdso_gettc(th, &tc); 47 if (error == 0) 48 *delta = (tc - th->th_offset_count) & th->th_counter_mask; 49 return (error); 50} 51 52/* 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. 56 * 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. 60 */ 61static int 62binuptime(struct bintime *bt, struct vdso_timekeep *tk, int abs) 63{ 64 struct vdso_timehands *th; 65 uint32_t curr, gen; 66 uint64_t scale, x; 67 u_int delta, scale_bits; 68 int error; 69 70 do { 71 if (!tk->tk_enabled) 72 return (ENOSYS); 73 74 curr = atomic_load_acq_32(&tk->tk_current); 75 th = &tk->tk_th[curr]; 76 gen = atomic_load_acq_32(&th->th_gen); 77 *bt = th->th_offset; 78 error = tc_delta(th, &delta); 79 if (error == EAGAIN) 80 continue; 81 if (error != 0) 82 return (error); 83 scale = th->th_scale; 84#ifdef _LP64 85 scale_bits = ffsl(scale); 86#else 87 scale_bits = ffsll(scale); 88#endif 89 if (__predict_false(scale_bits + fls(delta) > 63)) { 90 x = (scale >> 32) * delta; 91 scale &= 0xffffffff; 92 bt->sec += x >> 32; 93 bintime_addx(bt, x << 32); 94 } 95 bintime_addx(bt, scale * delta); 96 if (abs) 97 bintime_add(bt, &th->th_boottime); 98 99 /* 100 * Ensure that the load of th_offset is completed 101 * before the load of th_gen. 102 */ 103 atomic_thread_fence_acq(); 104 } while (curr != tk->tk_current || gen == 0 || gen != th->th_gen); 105 return (0); 106} 107 108static struct vdso_timekeep *tk; 109 110#pragma weak __vdso_gettimeofday 111int 112__vdso_gettimeofday(struct timeval *tv, struct timezone *tz) 113{ 114 struct bintime bt; 115 int error; 116 117 if (tz != NULL) 118 return (ENOSYS); 119 if (tk == NULL) { 120 error = __vdso_gettimekeep(&tk); 121 if (error != 0 || tk == NULL) 122 return (ENOSYS); 123 } 124 if (tk->tk_ver != VDSO_TK_VER_CURR) 125 return (ENOSYS); 126 error = binuptime(&bt, tk, 1); 127 if (error != 0) 128 return (error); 129 bintime2timeval(&bt, tv); 130 return (0); 131} 132 133#pragma weak __vdso_clock_gettime 134int 135__vdso_clock_gettime(clockid_t clock_id, struct timespec *ts) 136{ 137 struct bintime bt; 138 int abs, error; 139 140 if (tk == NULL) { 141 error = _elf_aux_info(AT_TIMEKEEP, &tk, sizeof(tk)); 142 if (error != 0 || tk == NULL) 143 return (ENOSYS); 144 } 145 if (tk->tk_ver != VDSO_TK_VER_CURR) 146 return (ENOSYS); 147 switch (clock_id) { 148 case CLOCK_REALTIME: 149 case CLOCK_REALTIME_PRECISE: 150 case CLOCK_REALTIME_FAST: 151 case CLOCK_SECOND: 152 abs = 1; 153 break; 154 case CLOCK_MONOTONIC: 155 case CLOCK_MONOTONIC_PRECISE: 156 case CLOCK_MONOTONIC_FAST: 157 case CLOCK_UPTIME: 158 case CLOCK_UPTIME_PRECISE: 159 case CLOCK_UPTIME_FAST: 160 abs = 0; 161 break; 162 default: 163 return (ENOSYS); 164 } 165 error = binuptime(&bt, tk, abs); 166 if (error != 0) 167 return (error); 168 bintime2timespec(&bt, ts); 169 if (clock_id == CLOCK_SECOND) 170 ts->tv_nsec = 0; 171 return (0); 172} 173