Initial commit: Go 1.23 release state

src/runtime/vdso_freebsd.go

@@ -0,0 +1,114 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build freebsd
+
+package runtime
+
+import (
+	"internal/runtime/atomic"
+	"unsafe"
+)
+
+const _VDSO_TH_NUM = 4 // defined in <sys/vdso.h> #ifdef _KERNEL
+
+var timekeepSharedPage *vdsoTimekeep
+
+//go:nosplit
+func (bt *bintime) Add(bt2 *bintime) {
+	u := bt.frac
+	bt.frac += bt2.frac
+	if u > bt.frac {
+		bt.sec++
+	}
+	bt.sec += bt2.sec
+}
+
+//go:nosplit
+func (bt *bintime) AddX(x uint64) {
+	u := bt.frac
+	bt.frac += x
+	if u > bt.frac {
+		bt.sec++
+	}
+}
+
+var (
+	// binuptimeDummy is used in binuptime as the address of an atomic.Load, to simulate
+	// an atomic_thread_fence_acq() call which behaves as an instruction reordering and
+	// memory barrier.
+	binuptimeDummy uint32
+
+	zeroBintime bintime
+)
+
+// based on /usr/src/lib/libc/sys/__vdso_gettimeofday.c
+//
+//go:nosplit
+func binuptime(abs bool) (bt bintime) {
+	timehands := (*[_VDSO_TH_NUM]vdsoTimehands)(add(unsafe.Pointer(timekeepSharedPage), vdsoTimekeepSize))
+	for {
+		if timekeepSharedPage.enabled == 0 {
+			return zeroBintime
+		}
+
+		curr := atomic.Load(&timekeepSharedPage.current) // atomic_load_acq_32
+		th := &timehands[curr]
+		gen := atomic.Load(&th.gen) // atomic_load_acq_32
+		bt = th.offset
+
+		if tc, ok := th.getTimecounter(); !ok {
+			return zeroBintime
+		} else {
+			delta := (tc - th.offset_count) & th.counter_mask
+			bt.AddX(th.scale * uint64(delta))
+		}
+		if abs {
+			bt.Add(&th.boottime)
+		}
+
+		atomic.Load(&binuptimeDummy) // atomic_thread_fence_acq()
+		if curr == timekeepSharedPage.current && gen != 0 && gen == th.gen {
+			break
+		}
+	}
+	return bt
+}
+
+//go:nosplit
+func vdsoClockGettime(clockID int32) bintime {
+	if timekeepSharedPage == nil || timekeepSharedPage.ver != _VDSO_TK_VER_CURR {
+		return zeroBintime
+	}
+	abs := false
+	switch clockID {
+	case _CLOCK_MONOTONIC:
+		/* ok */
+	case _CLOCK_REALTIME:
+		abs = true
+	default:
+		return zeroBintime
+	}
+	return binuptime(abs)
+}
+
+func fallback_nanotime() int64
+func fallback_walltime() (sec int64, nsec int32)
+
+//go:nosplit
+func nanotime1() int64 {
+	bt := vdsoClockGettime(_CLOCK_MONOTONIC)
+	if bt == zeroBintime {
+		return fallback_nanotime()
+	}
+	return int64((1e9 * uint64(bt.sec)) + ((1e9 * uint64(bt.frac>>32)) >> 32))
+}
+
+func walltime() (sec int64, nsec int32) {
+	bt := vdsoClockGettime(_CLOCK_REALTIME)
+	if bt == zeroBintime {
+		return fallback_walltime()
+	}
+	return int64(bt.sec), int32((1e9 * uint64(bt.frac>>32)) >> 32)
+}