Initial commit: Go 1.23 release state

src/runtime/vdso_freebsd_x86.go

@@ -0,0 +1,90 @@
+// 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 && (386 || amd64)
+
+package runtime
+
+import (
+	"internal/runtime/atomic"
+	"unsafe"
+)
+
+const (
+	_VDSO_TH_ALGO_X86_TSC  = 1
+	_VDSO_TH_ALGO_X86_HPET = 2
+)
+
+const (
+	_HPET_DEV_MAP_MAX  = 10
+	_HPET_MAIN_COUNTER = 0xf0 /* Main counter register */
+
+	hpetDevPath = "/dev/hpetX\x00"
+)
+
+var hpetDevMap [_HPET_DEV_MAP_MAX]uintptr
+
+//go:nosplit
+func (th *vdsoTimehands) getTSCTimecounter() uint32 {
+	tsc := cputicks()
+	if th.x86_shift > 0 {
+		tsc >>= th.x86_shift
+	}
+	return uint32(tsc)
+}
+
+//go:nosplit
+func (th *vdsoTimehands) getHPETTimecounter() (uint32, bool) {
+	idx := int(th.x86_hpet_idx)
+	if idx >= len(hpetDevMap) {
+		return 0, false
+	}
+
+	p := atomic.Loaduintptr(&hpetDevMap[idx])
+	if p == 0 {
+		systemstack(func() { initHPETTimecounter(idx) })
+		p = atomic.Loaduintptr(&hpetDevMap[idx])
+	}
+	if p == ^uintptr(0) {
+		return 0, false
+	}
+	return *(*uint32)(unsafe.Pointer(p + _HPET_MAIN_COUNTER)), true
+}
+
+//go:systemstack
+func initHPETTimecounter(idx int) {
+	const digits = "0123456789"
+
+	var devPath [len(hpetDevPath)]byte
+	copy(devPath[:], hpetDevPath)
+	devPath[9] = digits[idx]
+
+	fd := open(&devPath[0], 0 /* O_RDONLY */ |_O_CLOEXEC, 0)
+	if fd < 0 {
+		atomic.Casuintptr(&hpetDevMap[idx], 0, ^uintptr(0))
+		return
+	}
+
+	addr, mmapErr := mmap(nil, physPageSize, _PROT_READ, _MAP_SHARED, fd, 0)
+	closefd(fd)
+	newP := uintptr(addr)
+	if mmapErr != 0 {
+		newP = ^uintptr(0)
+	}
+	if !atomic.Casuintptr(&hpetDevMap[idx], 0, newP) && mmapErr == 0 {
+		munmap(addr, physPageSize)
+	}
+}
+
+//go:nosplit
+func (th *vdsoTimehands) getTimecounter() (uint32, bool) {
+	switch th.algo {
+	case _VDSO_TH_ALGO_X86_TSC:
+		return th.getTSCTimecounter(), true
+	case _VDSO_TH_ALGO_X86_HPET:
+		return th.getHPETTimecounter()
+	default:
+		return 0, false
+	}
+}