// innermost frame, that the SPWRITE function voluntarily preempted itself on entry
		// during the stack growth check. In that case, the function has
		// not yet had a chance to do any writes to SP and is safe to unwind.
		// isAsyncSafePoint does not allow assembly functions to be async preempted,
		// and preemptPark double-checks that SPWRITE functions are not async preempted.

	{"net.inet.ah.enable", []_C_int{4, 2, 51, 1}},
	{"net.inet.ah.stats", []_C_int{4, 2, 51, 2}},
	{"net.inet.carp.allow", []_C_int{4, 2, 112, 1}},
	{"net.inet.carp.log", []_C_int{4, 2, 112, 3}},
	{"net.inet.carp.preempt", []_C_int{4, 2, 112, 2}},
	{"net.inet.carp.stats", []_C_int{4, 2, 112, 4}},
	{"net.inet.divert.recvspace", []_C_int{4, 2, 258, 1}},
	{"net.inet.divert.sendspace", []_C_int{4, 2, 258, 2}},

	{"net.inet.ah.enable", []_C_int{4, 2, 51, 1}},
	{"net.inet.ah.stats", []_C_int{4, 2, 51, 2}},
	{"net.inet.carp.allow", []_C_int{4, 2, 112, 1}},
	{"net.inet.carp.log", []_C_int{4, 2, 112, 3}},
	{"net.inet.carp.preempt", []_C_int{4, 2, 112, 2}},
	{"net.inet.carp.stats", []_C_int{4, 2, 112, 4}},
	{"net.inet.divert.recvspace", []_C_int{4, 2, 258, 1}},
	{"net.inet.divert.sendspace", []_C_int{4, 2, 258, 2}},

	}
	return n
}

func signame(sig uint32) string {
	if sig >= uint32(len(sigtable)) {
		return ""
	}
	return sigtable[sig].name
}

const preemptMSupported = false

func preemptM(mp *m) {
	// Not currently supported.
	//
	// TODO: Use a note like we use signals on POSIX OSes

		// go code on the system stack can't defer
		throw("defer on system stack")
	}

	d := newdefer()
	d.link = gp._defer
	gp._defer = d
	d.fn = fn
	d.pc = getcallerpc()
	// We must not be preempted between calling getcallersp and
	// storing it to d.sp because getcallersp's result is a
	// uintptr stack pointer.
	d.sp = getcallersp()

	// deferproc returns 0 normally.
	// a deferred func that stops a panic

	// so instruction sequences that use REGTMP are unsafe to
	// preempt asynchronously.
	obj.MarkUnsafePoints(c.ctxt, c.cursym.Func().Text, c.newprog, c.isUnsafePoint, c.isRestartable)
}

// isUnsafePoint returns whether p is an unsafe point.
func (c *ctxt0) isUnsafePoint(p *obj.Prog) bool {
	// If p explicitly uses REGTMP, it's unsafe to preempt, because the
	// preemption sequence clobbers REGTMP.

	{"net.inet.ah.enable", []_C_int{4, 2, 51, 1}},
	{"net.inet.ah.stats", []_C_int{4, 2, 51, 2}},
	{"net.inet.carp.allow", []_C_int{4, 2, 112, 1}},
	{"net.inet.carp.log", []_C_int{4, 2, 112, 3}},
	{"net.inet.carp.preempt", []_C_int{4, 2, 112, 2}},
	{"net.inet.carp.stats", []_C_int{4, 2, 112, 4}},
	{"net.inet.divert.recvspace", []_C_int{4, 2, 258, 1}},
	{"net.inet.divert.sendspace", []_C_int{4, 2, 258, 2}},

	{"net.inet.ah.enable", []_C_int{4, 2, 51, 1}},
	{"net.inet.ah.stats", []_C_int{4, 2, 51, 2}},
	{"net.inet.carp.allow", []_C_int{4, 2, 112, 1}},
	{"net.inet.carp.log", []_C_int{4, 2, 112, 3}},
	{"net.inet.carp.preempt", []_C_int{4, 2, 112, 2}},
	{"net.inet.carp.stats", []_C_int{4, 2, 112, 4}},
	{"net.inet.divert.recvspace", []_C_int{4, 2, 258, 1}},
	{"net.inet.divert.sendspace", []_C_int{4, 2, 258, 2}},

	{"net.inet.ah.enable", []_C_int{4, 2, 51, 1}},
	{"net.inet.ah.stats", []_C_int{4, 2, 51, 2}},
	{"net.inet.carp.allow", []_C_int{4, 2, 112, 1}},
	{"net.inet.carp.log", []_C_int{4, 2, 112, 3}},
	{"net.inet.carp.preempt", []_C_int{4, 2, 112, 2}},
	{"net.inet.carp.stats", []_C_int{4, 2, 112, 4}},
	{"net.inet.divert.recvspace", []_C_int{4, 2, 258, 1}},
	{"net.inet.divert.sendspace", []_C_int{4, 2, 258, 2}},

// to the heap, or ^uintptr(0) if there was nothing to sweep.
func sweepone() uintptr {
	gp := getg()

	// Increment locks to ensure that the goroutine is not preempted
	// in the middle of sweep thus leaving the span in an inconsistent state for next GC
	gp.m.locks++

	// TODO(austin): sweepone is almost always called in a loop;
	// lift the sweepLocker into its callers.