JZ	sigtramp        // g.m == nil
	MOVL	m_ncgo(AX), CX
	TESTL	CX, CX
	JZ	sigtramp        // g.m.ncgo == 0
	MOVQ	m_curg(AX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg == nil
	MOVQ	g_syscallsp(CX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg.syscallsp == 0
	MOVQ	m_cgoCallers(AX), R8
	TESTQ	R8, R8
	JZ	sigtramp        // g.m.cgoCallers == nil
	MOVL	m_cgoCallersUse(AX), CX
	TESTL	CX, CX

// See racecallback for command codes.
TEXT	runtime·racecallbackthunk(SB), NOSPLIT|NOFRAME, $0
	// Handle command raceGetProcCmd (0) here.
	// First, code below assumes that we are on curg, while raceGetProcCmd
	// can be executed on g0. Second, it is called frequently, so will
	// benefit from this fast path.
	CBNZ	R0, rest
	MOVD	g, R13
#ifdef TLS_darwin

	gp := getg()
	casGToWaiting(gp.m.curg, _Grunning, waitReasonDumpingHeap)

	// Set dump file.
	dumpfd = fd

	// Call dump routine.
	mdump(m)

	// Reset dump file.
	dumpfd = 0
	if tmpbuf != nil {
		sysFree(unsafe.Pointer(&tmpbuf[0]), uintptr(len(tmpbuf)), &memstats.other_sys)
		tmpbuf = nil
	}

	casgstatus(gp.m.curg, _Gwaiting, _Grunning)
}

	w := tl.writer()
	if pp := tl.mp.p.ptr(); pp != nil && !pp.trace.statusWasTraced(tl.gen) && pp.trace.acquireStatus(tl.gen) {
		w = w.writeProcStatus(uint64(pp.id), procStatus, pp.trace.inSweep)
	}
	if gp := tl.mp.curg; gp != nil && !gp.trace.statusWasTraced(tl.gen) && gp.trace.acquireStatus(tl.gen) {
		w = w.writeGoStatus(uint64(gp.goid), int64(tl.mp.procid), goStatus, gp.inMarkAssist, 0 /* no stack */)
	}
	return traceEventWriter{w}
}

	CMP	$0, R6
	BEQ	sigtramp    // g.m == nil
	MOVW	m_ncgo(R6), R7
	CMPW	$0, R7
	BEQ	sigtramp    // g.m.ncgo = 0
	MOVD	m_curg(R6), R7
	CMP	$0, R7
	BEQ	sigtramp    // g.m.curg == nil
	MOVD	g_syscallsp(R7), R7
	CMP	$0, R7
	BEQ	sigtramp    // g.m.curg.syscallsp == 0
	MOVD	m_cgoCallers(R6), R7 // R7 is the fifth arg in C calling convention.
	CMP	$0, R7
	BEQ	sigtramp    // g.m.cgoCallers == nil
	MOVW	m_cgoCallersUse(R6), R8

	MOVD	g_m(g), R6
	CBZ	R6, sigtramp    // g.m == nil
	MOVW	m_ncgo(R6), R7
	CBZW	R7, sigtramp    // g.m.ncgo = 0
	MOVD	m_curg(R6), R8
	CBZ	R8, sigtramp    // g.m.curg == nil
	MOVD	g_syscallsp(R8), R7
	CBZ	R7,	sigtramp    // g.m.curg.syscallsp == 0
	MOVD	m_cgoCallers(R6), R4 // R4 is the fifth arg in C calling convention.
	CBZ	R4,	sigtramp    // g.m.cgoCallers == nil
	MOVW	m_cgoCallersUse(R6), R8

	JZ	sigtramp        // g.m == nil
	MOVL	m_ncgo(AX), CX
	TESTL	CX, CX
	JZ	sigtramp        // g.m.ncgo == 0
	MOVQ	m_curg(AX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg == nil
	MOVQ	g_syscallsp(CX), CX
	TESTQ	CX, CX
	JZ	sigtramp        // g.m.curg.syscallsp == 0
	MOVQ	m_cgoCallers(AX), R8
	TESTQ	R8, R8
	JZ	sigtramp        // g.m.cgoCallers == nil
	MOVL	m_cgoCallersUse(AX), CX
	TESTL	CX, CX

// func switchToCrashStack0(fn func())
TEXT runtime·switchToCrashStack0(SB), NOSPLIT, $0-8
	MOVD fn+0(FP), CTXT	// context register
	MOVD	g_m(g), R2	// curm

	// set g to gcrash
	MOVD	$runtime·gcrash(SB), g	// g = &gcrash
	MOVD	R2, g_m(g)	// g.m = curm
	MOVD	g, m_g0(R2)	// curm.g0 = g

	// switch to crashstack
	I64Load (g_stack+stack_hi)(g)
	I64Const $(-4*8)
	I64Add
	I32WrapI64
	Set SP

	MOVL	m_vdsoSP(SI), DX
	MOVL	CX, 0(SP)
	MOVL	DX, 4(SP)

	LEAL	sec+0(FP), DX
	MOVL	-4(DX), CX
	MOVL	CX, m_vdsoPC(SI)
	MOVL	DX, m_vdsoSP(SI)

	CMPL	AX, m_curg(SI)	// Only switch if on curg.
	JNE	noswitch

	MOVL	m_g0(SI), DX
	MOVL	(g_sched+gobuf_sp)(DX), SP	// Set SP to g0 stack

noswitch:
	SUBL	$16, SP		// Space for results
	ANDL	$~15, SP	// Align for C code

		// for that memory to get freed.
		KeepAlive(ep)
		return
	}

	// stack
	if gp := getg(); gp.m.curg.stack.lo <= uintptr(p) && uintptr(p) < gp.m.curg.stack.hi {
		found := false
		var u unwinder
		for u.initAt(gp.m.curg.sched.pc, gp.m.curg.sched.sp, 0, gp.m.curg, 0); u.valid(); u.next() {
			if u.frame.sp <= uintptr(p) && uintptr(p) < u.frame.varp {
				found = true
				break
			}
		}