// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build freebsd
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package runtime
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import (
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"runtime/internal/atomic"
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"unsafe"
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)
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const _VDSO_TH_NUM = 4 // defined in <sys/vdso.h> #ifdef _KERNEL
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var timekeepSharedPage *vdsoTimekeep
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//go:nosplit
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func (bt *bintime) Add(bt2 *bintime) {
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u := bt.frac
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bt.frac += bt2.frac
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if u > bt.frac {
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bt.sec++
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}
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bt.sec += bt2.sec
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}
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//go:nosplit
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func (bt *bintime) AddX(x uint64) {
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u := bt.frac
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bt.frac += x
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if u > bt.frac {
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bt.sec++
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}
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}
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var (
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// binuptimeDummy is used in binuptime as the address of an atomic.Load, to simulate
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// an atomic_thread_fence_acq() call which behaves as an instruction reordering and
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// memory barrier.
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binuptimeDummy uint32
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zeroBintime bintime
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)
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// based on /usr/src/lib/libc/sys/__vdso_gettimeofday.c
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//
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//go:nosplit
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func binuptime(abs bool) (bt bintime) {
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timehands := (*[_VDSO_TH_NUM]vdsoTimehands)(add(unsafe.Pointer(timekeepSharedPage), vdsoTimekeepSize))
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for {
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if timekeepSharedPage.enabled == 0 {
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return zeroBintime
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}
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curr := atomic.Load(&timekeepSharedPage.current) // atomic_load_acq_32
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th := &timehands[curr]
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gen := atomic.Load(&th.gen) // atomic_load_acq_32
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bt = th.offset
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if tc, ok := th.getTimecounter(); !ok {
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return zeroBintime
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} else {
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delta := (tc - th.offset_count) & th.counter_mask
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bt.AddX(th.scale * uint64(delta))
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}
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if abs {
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bt.Add(&th.boottime)
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}
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atomic.Load(&binuptimeDummy) // atomic_thread_fence_acq()
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if curr == timekeepSharedPage.current && gen != 0 && gen == th.gen {
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break
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}
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}
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return bt
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}
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//go:nosplit
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func vdsoClockGettime(clockID int32) bintime {
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if timekeepSharedPage == nil || timekeepSharedPage.ver != _VDSO_TK_VER_CURR {
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return zeroBintime
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}
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abs := false
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switch clockID {
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case _CLOCK_MONOTONIC:
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/* ok */
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case _CLOCK_REALTIME:
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abs = true
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default:
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return zeroBintime
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}
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return binuptime(abs)
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}
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func fallback_nanotime() int64
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func fallback_walltime() (sec int64, nsec int32)
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//go:nosplit
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func nanotime() int64 {
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bt := vdsoClockGettime(_CLOCK_MONOTONIC)
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if bt == zeroBintime {
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return fallback_nanotime()
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}
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return int64((1e9 * uint64(bt.sec)) + ((1e9 * uint64(bt.frac>>32)) >> 32))
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}
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func walltime() (sec int64, nsec int32) {
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bt := vdsoClockGettime(_CLOCK_REALTIME)
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if bt == zeroBintime {
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return fallback_walltime()
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}
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return int64(bt.sec), int32((1e9 * uint64(bt.frac>>32)) >> 32)
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}
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