src/runtime/os_fuchsia.go

// Copyright 2016 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.

package runtime

import (
	"internal/abi"
	"runtime/internal/atomic"
	"unsafe"
)

const nsecInf = int64(0x7FFFFFFFFFFFFFFF)

func osyield()

//go:nosplit
func osyield_no_g() {
	osyield()
}

//go:linkname cputicks syscall/zx.Sys_ticks_get
func cputicks() int64

//go:linkname sys_cprng_draw syscall/zx.Sys_cprng_draw
//go:noescape
func sys_cprng_draw(buffer unsafe.Pointer, size uint)

//go:linkname sys_system_get_num_cpus syscall/zx.Sys_system_get_num_cpus
func sys_system_get_num_cpus() uint32

//go:linkname sys_deadline_after syscall/zx.Sys_deadline_after
func sys_deadline_after(ns int64) int64

//go:linkname sys_futex_wait syscall/zx.Sys_futex_wait
//go:noescape
func sys_futex_wait(v *int32, cv int32, newOwner uint32, deadline int64) int32

//go:linkname sys_futex_wake syscall/zx.Sys_futex_wake
//go:noescape
func sys_futex_wake(v *int32, count uint32) int32

//go:linkname sys_thread_create syscall/zx.Sys_thread_create
//go:noescape
func sys_thread_create(p uint32, name *byte, nlen uint, opts int, out *uint32) int32

//go:linkname sys_thread_start syscall/zx.Sys_thread_start
//go:noescape
func sys_thread_start(h uint32, pc unsafe.Pointer, stk unsafe.Pointer, mp uintptr, arg2 uintptr) int32

//go:linkname sys_clock_get_monotonic syscall/zx.Sys_clock_get_monotonic
func sys_clock_get_monotonic() int64

//go:linkname sys_nanosleep syscall/zx.Sys_nanosleep
func sys_nanosleep(deadline int64) int32

//go:linkname sys_process_exit syscall/zx.Sys_process_exit
func sys_process_exit(retcode int64)

//go:linkname zx_set_stdio_handle syscall/zx.set_stdio_handle
func zx_set_stdio_handle(n int, h uint32, t uint32)

//go:linkname zx_set_proc_handle syscall/zx.set_proc_handle
func zx_set_proc_handle(h uint32)

//go:linkname zx_get_proc_handle syscall/zx.get_proc_handle
func zx_get_proc_handle() uint32

//go:linkname zx_set_vmar_root syscall/zx.set_vmar_root
func zx_set_vmar_root(h uint32)

//go:linkname zx_set_namespace syscall/zx.set_namespace
func zx_set_namespace(m map[string]uint32)

//go:linkname zx_notify_new_thread syscall/zx.notify_new_thread
func zx_notify_new_thread(h uint32, w byte)

//go:linkname zx_init_threads_channel syscall/zx.init_threads_channel
func zx_init_threads_channel()

type mOS struct {
	// threadLock protects the fields below.
	//
	// This lock must be held to write the fields or read them from another
	// thread. Other threads should hold threadLock to prevent the M from
	// getting unminit'd from underneath them.
	threadLock mutex

	thread     uint32
	threadKoid uint64
}

//go:nosplit
func getThreadHandle() uint32 {
	return getg().m.thread
}

//go:nosplit
func getThreadKoid() uint64 {
	return getg().m.threadKoid
}

type sigset struct{}

//go:nosplit
func getRandomData(r []byte) {
	if len(r) == 0 {
		return
	}
	sys_cprng_draw(unsafe.Pointer(&r[0]), uint(len(r)))
}

//go:nosplit
func futexsleep(addr *uint32, val uint32, ns int64) {
	deadline := sys_deadline_after(ns)
	if ns < 0 {
		deadline = nsecInf
	}
	sys_futex_wait((*int32)(unsafe.Pointer(addr)), int32(val), 0, deadline)
}

//go:nosplit
func futexwakeup(addr *uint32, cnt uint32) {
	sys_futex_wake((*int32)(unsafe.Pointer(addr)), cnt)
}

// cgocallm0 calls a C function on the current stack.
//
// It is intended for use inside functions like osinit that run
// before mstart directly on an OS thread stack.
//
// If in doubt, do not use.
func cgocallm0(fn, arg unsafe.Pointer)

// exceptionInfo is defined in zircon/syscalls/exception.h.
type exceptionInfo struct {
	pid           uint64
	tid           uint64
	exceptionType uint32
	padding       [4]uint8
}

// watchexceptions is called when pprof CPU tracing is enabled. It runs without
// a p, hence nowritebarrierrec.
//
//go:nosplit
//go:nowritebarrierrec
func watchexceptions() {
	procHandle := zx_get_proc_handle()
	var exceptionChannel uint32
	if status := vdsoCall_zx_task_create_exception_channel(procHandle, 0, unsafe.Pointer(&exceptionChannel)); status != ZX_OK {
		println("failed to create exception channel", status)
		exit(2)
	}
	for {

		var observed uint32
		if status := fake_m_object_wait_one(exceptionChannel, ZX_CHANNEL_READABLE, ZX_TIME_INFINITE, &observed); status != ZX_OK {
			println("failed to wait on exception channel", status)
			exit(2)
		}

		var info exceptionInfo
		var exceptionHandle uint32
		var actualBytes, actualHandles uint32
		if status := vdsoCall_zx_channel_read(
			exceptionChannel,
			0,
			unsafe.Pointer(&info),
			unsafe.Pointer(&exceptionHandle),
			uint32(unsafe.Sizeof(info)),
			1,
			unsafe.Pointer(&actualBytes),
			unsafe.Pointer(&actualHandles),
		); status != ZX_OK {
			println("failed to read from exception channel", status)
			exit(2)
		}

		switch info.exceptionType {
		// A fatal exception occurred, attempt to push a panic into the
		// offending thread.
		case ZX_EXCP_FATAL_PAGE_FAULT, ZX_EXCP_UNALIGNED_ACCESS, ZX_EXCP_UNDEFINED_INSTRUCTION:
			var thread uint32
			if status := vdsoCall_zx_exception_get_thread(exceptionHandle, unsafe.Pointer(&thread)); status != ZX_OK {
				println("failed to get exception thread", status)
				exit(2)
			}

			var ctx sigctxt
			if status := vdsoCall_zx_thread_read_state(
				thread,
				ZX_THREAD_STATE_GENERAL_REGS,
				unsafe.Pointer(&ctx.regs),
				uint(unsafe.Sizeof(ctx.regs)),
			); status != ZX_OK {
				println("failed to read thread state", status)
				exit(2)
			}

			// Prepare a panic, we'll call sigpanic on the dead thread.
			ctx.prepareExceptionPanic()
			if status := vdsoCall_zx_thread_write_state(
				thread,
				ZX_THREAD_STATE_GENERAL_REGS,
				unsafe.Pointer(&ctx.regs),
				uint(unsafe.Sizeof(ctx.regs)),
			); status != ZX_OK {
				println("failed to recover thread state on OS exception")
				ctx.traceback()
				exit(2)
			}
			handled := ZX_EXCEPTION_STATE_HANDLED
			if status := vdsoCall_zx_object_set_property(
				exceptionHandle,
				ZX_PROP_EXCEPTION_STATE,
				unsafe.Pointer(&handled),
				uint(unsafe.Sizeof(handled)),
			); status != ZX_OK {
				println("failed to mark OS exception as handled")
				ctx.traceback()
				exit(2)
			}

			// Close the thread handle, we don't need it anymore, and we don't really
			// care if it succeeds.
			_ = vdsoCall_zx_handle_close(thread)
			if status := vdsoCall_zx_handle_close(exceptionHandle); status != ZX_OK {
				println("failed to close exception handle")
				ctx.traceback()
				exit(2)
			}
		default:
			// We're not handling this exception, just close the handle.
			vdsoCall_zx_handle_close(exceptionHandle)
		}
	}
}

var critlock mutex

func osinit() {
	if _cgo_get_initial_handles != nil {
		cgocallm0(_cgo_get_initial_handles, unsafe.Pointer(&fdioHandles))
		for i := 0; i < 3; i = i + 1 {
			zx_set_stdio_handle(i, fdioHandles.stdioClones[i], fdioHandles.stdioCloneTypes[i])
		}
		zx_set_proc_handle(fdioHandles.processSelf)
		zx_set_vmar_root(fdioHandles.vmarRootSelf)
		zx_init_threads_channel()
	} else {
		println("runtime: fuchsia requires cgo")
		exit(2)
	}

	ncpu = int32(sys_system_get_num_cpus())
	physPageSize = 4096
}

func parseRootNS() {
	if fdioHandles.rootNSNumHandles > 0 {
		const maxHandleCount = 1 << 20 // arbitrary
		paths := (*(*[maxHandleCount]*byte)(unsafe.Pointer(fdioHandles.rootNSPaths)))[:fdioHandles.rootNSNumHandles]
		handles := (*(*[maxHandleCount]uint32)(unsafe.Pointer(fdioHandles.rootNSHandles)))[:fdioHandles.rootNSNumHandles]
		m := make(map[string]uint32)
		for i, p := range paths {
			m[gostring(p)] = handles[i]
		}

		zx_set_namespace(m)
	}
}

// Filled in by runtime/cgo when linked into binary.
var (
	_cgo_get_initial_handles    unsafe.Pointer
	_cgo_get_thread_self_handle unsafe.Pointer
	_cgo_timespec_get           unsafe.Pointer
	_cgo_write1                 unsafe.Pointer
)

type ThreadType byte

const (
	_ ThreadType = iota
	WorkerThread
	UnknownRuntimeThread
	SysmonThread
	WatchExceptionsThread
	ProfileLoopThread
	TemplateThread
)

//go:nosplit
func minit() {
	_g_ := getg()
	mp := _g_.m

	lock(&mp.threadLock)

	var h uint32
	asmcgocall(_cgo_get_thread_self_handle, unsafe.Pointer(&h))

	mp.thread = h

	// NB: Write barrier restrictions in this function disallow a nicer pattern
	// to assign these variables.
	isWorker := mp.p != 0 || mp.nextp != 0
	threadName := []byte("go-worker")
	threadType := WorkerThread
	if !isWorker {
		// There are some known functions that we can compare against,
		// unfortunately we can't use FuncForPC here because of the write
		// barriers imposed by the callers.
		switch abi.FuncPCABIInternal(mp.mstartfn) {
		case abi.FuncPCABIInternal(sysmon):
			threadName = []byte("sysmon")
			threadType = SysmonThread
		case abi.FuncPCABIInternal(watchexceptions):
			threadName = []byte("watchexceptions")
			threadType = WatchExceptionsThread
		case abi.FuncPCABIInternal(profileLoop):
			threadName = []byte("profileLoop")
			threadType = ProfileLoopThread
		case abi.FuncPCABIInternal(templateThread):
			threadName = []byte("templateThread")
			threadType = TemplateThread
		default:
			threadName = []byte("unknown-runtime-thread")
			threadType = UnknownRuntimeThread
		}
	}

	if status := vdsoCall_zx_object_set_property(h, propName, unsafe.Pointer(&threadName[0]), uint(len(threadName))); status != 0 {
		println("runtime: vdsoCall_zx_object_set_property failed: ", status)
		exit(2)
	}

	var info zxInfoHandleBasic
	var actualSize uint64
	var availSize uint64
	if status := vdsoCall_zx_object_get_info(h, ZX_INFO_HANDLE_BASIC, unsafe.Pointer(&info), uint(unsafe.Sizeof(info)), unsafe.Pointer(&actualSize), unsafe.Pointer(&availSize)); status != ZX_OK {
		println("failed to get the thread koid for tracing", status)
	} else {
		mp.threadKoid = info.koid
	}

	zx_notify_new_thread(h, byte(threadType))
	unlock(&mp.threadLock)
}

//go:nosplit
func unminit() {
	mp := getg().m

	lock(&mp.threadLock)

	mp.thread = ZX_HANDLE_INVALID
	mp.threadKoid = 0

	unlock(&mp.threadLock)
}

func mdestroy(mp *m) {
	// TODO
}

var exceptionError = error(errorString("OS exception"))

func (c *sigctxt) traceback() {
	traceback(c.regs.rPC(), c.regs.rSP(), c.regs.rLR(), getg())
}

func sigpanic() {
	if !canpanic() {
		throw("encountered OS exception")
	}
	panicCheck2(exceptionError.Error())
	panic(exceptionError)
}

func mpreinit(mp *m) {
	// TODO
}

//go:nosplit
func sigsave(p *sigset) {
	// TODO
}

//go:nosplit
func msigrestore(sigmask sigset) {
	// TODO
}

func initsig(preinit bool) {
	// We can't call newm if this is preinit.
	if !preinit {
		newm(watchexceptions, nil, -1)
	}
}

//go:nosplit
//go:nowritebarrierrec
func libpreinit() {
	initsig(true)
}

//go:nosplit
func sigblock(exiting bool) {
	// TODO
}

func sigenable(sig uint32) {
	// TODO
}

func sigdisable(sig uint32) {
	// TODO
}

func sigignore(sig uint32) {
	// TODO
}

func crash() {
	*(*int32)(nil) = 0
}

func threadinit(mp *m)

var gothreadname = []byte("gothread")

//go:nowritebarrier
func newosproc(mp *m) {
	stk := unsafe.Pointer(mp.g0.stack.hi)
	p := uint32(0) // TODO: only works due to temporary hack in zircon
	var h uint32
	status := sys_thread_create(p, &gothreadname[0], uint(len(gothreadname)), 0, &h)
	if status < 0 {
		println("runtime: newosproc sys_thread_create failed:", h)
		exit(2)
	}

	status = sys_thread_start(h, unsafe.Pointer(abi.FuncPCABI0(threadinit)), stk, uintptr(unsafe.Pointer(mp)), 0)
	if status < 0 {
		println("runtime: newosproc sys_thread_start failed:", h)
		exit(2)
	}
}

//go:nosplit
func newosproc0(stacksize uintptr, fn unsafe.Pointer) {
	stack := sysAlloc(stacksize, &memstats.stacks_sys)
	if stack == nil {
		writeErrStr(failallocatestack)
		exit(1)
	}

	p := uint32(0) // TODO: only works due to temporary hack in zircon
	var h uint32
	status := sys_thread_create(p, &gothreadname[0], uint(len(gothreadname)), 0, &h)
	if status < 0 {
		writeErrStr(failthreadcreate)
		exit(1)

	}

	status = sys_thread_start(h, fn, unsafe.Pointer(uintptr(stack)+stacksize), 0, 0)
	if status < 0 {
		writeErrStr(failthreadstart)
		exit(1)
	}
}

const failthreadstart = "runtime: failed to start new OS thread\n"

type zx_proc_args struct {
	protocol        uint32
	version         uint32
	handle_info_off uint32
	args_off        uint32
	args_num        uint32
}

type zx_proc_info struct {
	magic         uint32
	version       uint32
	next_tls_slot uint32
	proc_args     *zx_proc_args
	handle        *uint32
	handle_info   *uint32
	handle_count  int32
	argv          **byte
	argc          int32
}

type zx_tls_root struct {
	self     *zx_tls_root
	proc     *zx_proc_info
	magic    uint32
	flags    uint16
	maxslots uint16
	slots    [8]uintptr // has length maxslots
}

func resetcpuprofiler(hz int32) {
	// TODO
}

// fdio_init matches a Go struct of the same name in gcc_fuchsia.c.
type fdio_init struct {
	stdioClones          [3]uint32
	stdioCloneNumHandles [3]uint32
	stdioCloneTypes      [3]uint32
	processSelf          uint32
	vmarRootSelf         uint32
	envlen               int32
	environ              **byte
	_                    [4]byte
	rootNSNumHandles     int32
	rootNSHandles        *uint32
	rootNSPaths          **byte
}

var fdioHandles fdio_init

func goenvs() {
	if _cgo_get_initial_handles != nil {
		const maxEnvSize = 1 << 20 // arbitrary
		envp := (*(*[maxEnvSize]*byte)(unsafe.Pointer(fdioHandles.environ)))[:fdioHandles.envlen]
		envs = make([]string, len(envp))
		for i, e := range envp {
			envs[i] = gostring(e)
		}
		// TODO: find a better place to call this
		parseRootNS()
	} else {
		// TODO: implement cgo-less init
		println("runtime: no fuchsia process handle without cgo yet")
		exit(2)
	}
}

const _NSIG = 65 // TODO

const (
	ZX_CLOCK_MONOTONIC           = 0
	ZX_HANDLE_INVALID            = 0
	ZX_INFO_HANDLE_BASIC         = uint32(2)
	ZX_INFO_THREAD               = uint32(10)
	ZX_OK                        = int32(0)
	ZX_THREAD_STATE_GENERAL_REGS = uint32(0)
	ZX_THREAD_STATE_NEW          = uint32(0)
	ZX_THREAD_SUSPENDED          = uint32(1 << 5)
	ZX_THREAD_TERMINATED         = uint32(1 << 3)
	ZX_TIME_INFINITE             = int64(^uint64(1 << 63))
	ZX_TIMER_SIGNALED            = uint32(1 << 3)
	ZX_TIMER_SLACK_EARLY         = 1
	ZX_CHANNEL_READABLE          = uint32(1 << 0)
	ZX_EXCEPTION_STATE_HANDLED   = uint32(1)
	ZX_PROP_EXCEPTION_STATE      = uint32(16)
	// Exception types that are handled by the runtime. Defined in
	// zircon/syscall/exception.h
	ZX_EXCP_FATAL_PAGE_FAULT      = uint32(0x108)
	ZX_EXCP_UNDEFINED_INSTRUCTION = uint32(0x208)
	ZX_EXCP_UNALIGNED_ACCESS      = uint32(0x508)
)

//go:nosplit
func nanotime1() int64 {
	return sys_clock_get_monotonic()
}

// Should match timespec struct definition from libc time.h
type timespec struct {
	tv_sec  int64
	tv_nsec int64
}

//go:linkname time_now time.now
//go:nosplit
func time_now() (sec int64, nsec int32, mono int64) {
	var ts timespec
	if asmcgocall(_cgo_timespec_get, unsafe.Pointer(&ts)) != 0 {
		panic("failed to get UTC time")
	}
	return ts.tv_sec, int32(ts.tv_nsec), nanotime()
}

func unixnanotime() int64 {
	return nanotime()
}

type writeargs struct {
	fd    uint32
	buf   uintptr
	count uint32
}

//go:nosplit
func write1(fd uintptr, buf unsafe.Pointer, n int32) int32 {
	w := writeargs{
		fd:    uint32(fd),
		buf:   uintptr(buf),
		count: uint32(n),
	}
	return asmcgocall(_cgo_write1, unsafe.Pointer(&w))
}

//go:nosplit
func exit(code int32) {
	sys_process_exit(int64(code))
}

//go:nosplit
func usleep(usec uint32) {
	sys_nanosleep(sys_deadline_after(int64(usec * 1000)))
}

//go:nosplit
func usleep_no_g(usec uint32) {
	usleep(usec)
}

func signame(sig uint32) string {
	return "unknown_sig" // TODO
}

// zircon_mktls
//
//go:nosplit
func zircon_mktls() {
	// TODO
}

//go:nosplit
func zircon_settls(val uintptr) {
	// TODO: should call zx_set_object_property with property ZX_PROP_REGISTER_FS in amd64 or
	// ZX_PROP_REGISTER_CP15 on arm.
}

//go:linkname os_sigpipe os.sigpipe
func os_sigpipe() {
	// TODO
}

// gsignalStack is unused on fuchsia
type gsignalStack struct{}

const preemptMSupported = false

func preemptM(mp *m) {
	// No threads, so nothing to do.
}

var (
	profTimer uint32 // timer handle
	profHz    = ZX_TIME_INFINITE
)

type zxCpuSet struct {
	mask [16]uint32
}

type zxInfoHandleBasic struct {
	koid         uint64
	rights       uint32
	typ          uint32
	related_koid uint64
	reserved     uint32
	padding      [4]uint8
}

type zxInfoThread struct {
	state                 uint32
	waitExceptionPortType uint32
	affinityMask          zxCpuSet
}

//go:noescape
//go:nosplit
func fake_m_object_wait_one(handle uint32, signals uint32, deadline int64, observed *uint32) int32

func profilem(mp *m, thread uint32) {
	// Ignore nascent threads.
	var observed uint32
	var info zxInfoThread
	var actualSize uint64
	var availSize uint64
	if status := vdsoCall_zx_object_get_info(thread, ZX_INFO_THREAD, unsafe.Pointer(&info), uint(unsafe.Sizeof(info)), unsafe.Pointer(&actualSize), unsafe.Pointer(&availSize)); status != ZX_OK {
		return
	}
	if info.state == ZX_THREAD_STATE_NEW {
		return
	}

	// Wait for the thread to be suspended.
	if status := fake_m_object_wait_one(thread, ZX_THREAD_SUSPENDED|ZX_THREAD_TERMINATED, ZX_TIME_INFINITE, &observed); status != ZX_OK {
		return
	}

	// Ignore threads that were terminated as a result of suspension.
	if observed&ZX_THREAD_TERMINATED == ZX_THREAD_TERMINATED {
		return
	}

	var r generalRegs
	if status := vdsoCall_zx_thread_read_state(thread, ZX_THREAD_STATE_GENERAL_REGS, unsafe.Pointer(&r), uint(unsafe.Sizeof(r))); status != ZX_OK {
		return
	}

	gp := gFromSP(mp, r.rSP())

	sigprof(r.rPC(), r.rSP(), r.rLR(), gp, mp)
}

func gFromSP(mp *m, sp uintptr) *g {
	if gp := mp.g0; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
		return gp
	}
	if gp := mp.gsignal; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
		return gp
	}
	if gp := mp.curg; gp != nil && gp.stack.lo < sp && sp < gp.stack.hi {
		return gp
	}
	return nil
}

// profileLoop is called when pprof CPU tracing is enabled. It runs without a p, hence nowritebarrierrec.
//
//go:nosplit
//go:nowritebarrierrec
func profileLoop() {
	for {
		var observed uint32
		if status := fake_m_object_wait_one(profTimer, ZX_TIMER_SIGNALED, ZX_TIME_INFINITE, &observed); status != ZX_OK {
			continue
		}

		// Scan over all threads and suspend them, then trace. Ideally, we'd scan over
		// all of them and give them a chance to suspend before this, but I don't want
		// to deal with allocation here.
		first := (*m)(atomic.Loadp(unsafe.Pointer(&allm)))
		for mp := first; mp != nil; mp = mp.alllink {
			if mp == getg().m {
				// Don't profile ourselves.
				continue
			}

			// We must synchronize with unminit to avoid profiling
			// threads after unminit, at which point they may be in
			// the calling C code which we can't extract a G from
			// (as none exists).
			lock(&mp.threadLock)
			thread := mp.thread
			// Do not profile threads blocked on Notes (this
			// includes idle worker threads, idle timer thread,
			// idle heap scavenger, etc.).
			if thread == ZX_HANDLE_INVALID || mp.profilehz == 0 || mp.blocked {
				unlock(&mp.threadLock)
				continue
			}

			var token uint32
			if status := vdsoCall_zx_task_suspend_token(thread, unsafe.Pointer(&token)); status == ZX_OK {
				profilem(mp, thread)
			}
			vdsoCall_zx_handle_close(token)
			unlock(&mp.threadLock)

		}

		due := vdsoCall_zx_deadline_after(profHz)
		if status := vdsoCall_zx_timer_set(profTimer, due, ZX_TIMER_SLACK_EARLY); status != ZX_OK {
			// TODO: what do?
			return
		}
	}
}

// profileloop is defined in sys_fuchsia_{amd,arm}64.s
func profileloop()

func setProcessCPUProfiler(hz int32) {
	// This function is entered in the critical section guarded by
	// prof.signalLock in proc.go and is thus safe to assume the profiler's
	// timer is created atomically.
	if profTimer == ZX_HANDLE_INVALID {
		if status := vdsoCall_zx_timer_create(ZX_TIMER_SLACK_EARLY, ZX_CLOCK_MONOTONIC, unsafe.Pointer(&profTimer)); status != ZX_OK {
			// TODO: what do?
			return
		}

		newm(profileLoop, nil, -1)
	}
}

func setThreadCPUProfiler(hz int32) {
	// Don't do anything if we don't have a timer yet.
	if profTimer == ZX_HANDLE_INVALID {
		return
	}

	atomic.Store((*uint32)(unsafe.Pointer(&getg().m.profilehz)), uint32(hz))

	if hz > 0 {
		ns := int64(int64(1000000000) / int64(hz))
		// Bound tracing frequency to microseconds. This is likely
		// already well above the granularity traces can actually
		// provide.
		if ns < 1000 {
			ns = 1000
		}

		profHz = ns
		due := vdsoCall_zx_deadline_after(ns)
		if status := vdsoCall_zx_timer_set(profTimer, due, ZX_TIMER_SLACK_EARLY); status != ZX_OK {
			// TODO: what do?
			return
		}
	} else {
		if status := vdsoCall_zx_timer_cancel(profTimer); status != ZX_OK {
			return
		}
	}
}

func exitThread(wait *atomic.Uint32) {}

//go:nosplit
//go:nowritebarrierrec
func clearSignalHandlers() {}