1// Copyright 2018 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// +build freebsd
6
7package runtime
8
9import (
10	"runtime/internal/atomic"
11	"unsafe"
12)
13
14const _VDSO_TH_NUM = 4 // defined in <sys/vdso.h> #ifdef _KERNEL
15
16var timekeepSharedPage *vdsoTimekeep
17
18//go:nosplit
19func (bt *bintime) Add(bt2 *bintime) {
20	u := bt.frac
21	bt.frac += bt2.frac
22	if u > bt.frac {
23		bt.sec++
24	}
25	bt.sec += bt2.sec
26}
27
28//go:nosplit
29func (bt *bintime) AddX(x uint64) {
30	u := bt.frac
31	bt.frac += x
32	if u > bt.frac {
33		bt.sec++
34	}
35}
36
37var (
38	// binuptimeDummy is used in binuptime as the address of an atomic.Load, to simulate
39	// an atomic_thread_fence_acq() call which behaves as an instruction reordering and
40	// memory barrier.
41	binuptimeDummy uint32
42
43	zeroBintime bintime
44)
45
46// based on /usr/src/lib/libc/sys/__vdso_gettimeofday.c
47//
48//go:nosplit
49func binuptime(abs bool) (bt bintime) {
50	timehands := (*[_VDSO_TH_NUM]vdsoTimehands)(add(unsafe.Pointer(timekeepSharedPage), vdsoTimekeepSize))
51	for {
52		if timekeepSharedPage.enabled == 0 {
53			return zeroBintime
54		}
55
56		curr := atomic.Load(&timekeepSharedPage.current) // atomic_load_acq_32
57		th := &timehands[curr]
58		gen := atomic.Load(&th.gen) // atomic_load_acq_32
59		bt = th.offset
60
61		if tc, ok := th.getTimecounter(); !ok {
62			return zeroBintime
63		} else {
64			delta := (tc - th.offset_count) & th.counter_mask
65			bt.AddX(th.scale * uint64(delta))
66		}
67		if abs {
68			bt.Add(&th.boottime)
69		}
70
71		atomic.Load(&binuptimeDummy) // atomic_thread_fence_acq()
72		if curr == timekeepSharedPage.current && gen != 0 && gen == th.gen {
73			break
74		}
75	}
76	return bt
77}
78
79//go:nosplit
80func vdsoClockGettime(clockID int32) bintime {
81	if timekeepSharedPage == nil || timekeepSharedPage.ver != _VDSO_TK_VER_CURR {
82		return zeroBintime
83	}
84	abs := false
85	switch clockID {
86	case _CLOCK_MONOTONIC:
87		/* ok */
88	case _CLOCK_REALTIME:
89		abs = true
90	default:
91		return zeroBintime
92	}
93	return binuptime(abs)
94}
95
96func fallback_nanotime() int64
97func fallback_walltime() (sec int64, nsec int32)
98
99//go:nosplit
100func nanotime1() int64 {
101	bt := vdsoClockGettime(_CLOCK_MONOTONIC)
102	if bt == zeroBintime {
103		return fallback_nanotime()
104	}
105	return int64((1e9 * uint64(bt.sec)) + ((1e9 * uint64(bt.frac>>32)) >> 32))
106}
107
108func walltime1() (sec int64, nsec int32) {
109	bt := vdsoClockGettime(_CLOCK_REALTIME)
110	if bt == zeroBintime {
111		return fallback_walltime()
112	}
113	return int64(bt.sec), int32((1e9 * uint64(bt.frac>>32)) >> 32)
114}
115