// calls only nosplit functions between entersyscallblock/exitsyscall.
func notetsleepg(n *note, ns int64) bool {
	gp := getg()
	if gp == gp.m.g0 {
		throw("notetsleepg on g0")
	}
	semacreate(gp.m)
	entersyscallblock()
	ok := notetsleep_internal(n, ns, nil, 0)
	exitsyscall()
	return ok
}

func beforeIdle(int64, int64) (*g, bool) {
	return nil, false
}

// traceClockNow returns a monotonic timestamp. The clock this function gets
// the timestamp from is specific to tracing, and shouldn't be mixed with other
// clock sources.
//
// nosplit because it's called from exitsyscall, which is nosplit.
//
// traceClockNow is called by golang.org/x/exp/trace using linkname.
//
//go:linkname traceClockNow
//go:nosplit
func traceClockNow() traceTime {
	if osHasLowResClock {

	runtime.ExitSyscall()
	for i := 0; e1 == EAGAIN && i < 10; i++ {
		runtime.EnterSyscall()
		CallLeFuncWithErr(GetZosLibVec()+SYS_USLEEP<<4, uintptr(10))
		runtime.ExitSyscall()
		runtime.EnterSyscall()
		r0, e2, e1 = CallLeFuncWithErr(GetZosLibVec()+SYS_CLOSE<<4, uintptr(fd))
		runtime.ExitSyscall()
	}
	if r0 != 0 {
		err = errnoErr2(e1, e2)
	}
	return

	c := libcall{
		fn:   fn,
		n:    nargs,
		args: uintptr(unsafe.Pointer(&a1)),
	}

	entersyscallblock()
	asmcgocall(unsafe.Pointer(&asmsyscall6), unsafe.Pointer(&c))
	exitsyscall()
	return c.r1, 0, c.err
}

// This is exported via linkname to assembly in the syscall package.
//
//go:nosplit
//go:cgo_unsafe_args
//go:linkname syscall_rawSyscall6

}

// sigNoteSleep waits for a note created by sigNoteSetup to be woken.
func sigNoteSleep(*note) {
	for {
		var b byte
		entersyscallblock()
		n := read(sigNoteRead, unsafe.Pointer(&b), 1)
		exitsyscall()
		if n != -_EINTR {
			return
		}
	}
}

// BSD interface for threading.
func osinit() {
	// pthread_create delayed until end of goenvs so that we
	// can look at the environment first.

// wrap it in our own nicer implementation.

package syscall

import (
	"internal/itoa"
	runtimesyscall "internal/runtime/syscall"
	"runtime"
	"unsafe"
)

// Pull in entersyscall/exitsyscall for Syscall/Syscall6.
//
// Note that this can't be a push linkname because the runtime already has a
// nameless linkname to export to assembly here and in x/sys. Additionally,

var Fmul64 = fmul64
var Fdiv64 = fdiv64
var F64to32 = f64to32
var F32to64 = f32to64
var Fcmp64 = fcmp64
var Fintto64 = fintto64
var F64toint = f64toint

var Entersyscall = entersyscall
var Exitsyscall = exitsyscall
var LockedOSThread = lockedOSThread
var Xadduintptr = atomic.Xadduintptr

var ReadRandomFailed = &readRandomFailed

var Fastlog2 = fastlog2

var Atoi = atoi
var Atoi32 = atoi32

//
//go:nosplit
func fakeSyscall(duration time.Duration) {
	runtime.Entersyscall()
	for start := runtime.Nanotime(); runtime.Nanotime()-start < int64(duration); {
	}
	runtime.Exitsyscall()
}

// Check that a goroutine will be preempted if it is calling short system calls.
func testPreemptionAfterSyscall(t *testing.T, syscallDuration time.Duration) {
	if runtime.GOARCH == "wasm" {

//
// exitsyscall should be an internal detail,
// but widely used packages access it using linkname.
// Notable members of the hall of shame include:
//   - gvisor.dev/gvisor
//
// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:nosplit
//go:nowritebarrierrec
//go:linkname exitsyscall
func exitsyscall() {
	gp := getg()

		n2 := n
		for n2 > fixedStack {
			order++
			n2 >>= 1
		}
		var x gclinkptr
		if stackNoCache != 0 || thisg.m.p == 0 || thisg.m.preemptoff != "" {
			// thisg.m.p == 0 can happen in the guts of exitsyscall
			// or procresize. Just get a stack from the global pool.
			// Also don't touch stackcache during gc
			// as it's flushed concurrently.
			lock(&stackpool[order].item.mu)
			x = stackpoolalloc(order)