// Switches SP to g0 stack and calls (FARG). Arguments already set.
TEXT	asancall<>(SB), NOSPLIT, $0-0
	MOVV	R3, R23         // callee-saved
	BEQ	g, g0stack      // no g, still on a system stack
	MOVV	g_m(g), R14
	MOVV	m_g0(R14), R15
	BEQ	R15, g, g0stack

	MOVV	(g_sched+gobuf_sp)(R15), R9
	MOVV	R9, R3

g0stack:
	JAL	(FARG)
	MOVV	R23, R3

TEXT	msancall<>(SB), NOSPLIT, $0-0
	MOVD	RSP, R19                  // callee-saved
	CBZ	g, g0stack                // no g, still on a system stack
	MOVD	g_m(g), R10
	MOVD	m_g0(R10), R11
	CMP	R11, g
	BEQ	g0stack

	MOVD	(g_sched+gobuf_sp)(R11), R4
	MOVD	R4, RSP

g0stack:
	BL	(FARG)
	MOVD	R19, RSP

	AND	$~7, R13
	MOVW	R0, 60(R13)		// save argc, argv away
	MOVW	R1, 64(R13)

	// set up g register
	// g is R10
	MOVW	$runtime·g0(SB), g
	MOVW	$runtime·m0(SB), R8

	// save m->g0 = g0
	MOVW	g, m_g0(R8)
	// save g->m = m0
	MOVW	R8, g_m(g)

	// create istack out of the OS stack
	// (1MB of system stack is available on iOS and Android)
	MOVW	$(-64*1024+104)(R13), R0
	MOVW	R0, g_stackguard0(g)

TEXT	asancall<>(SB), NOSPLIT, $0-0
	MOVD	RSP, R19                  // callee-saved
	CBZ	g, g0stack                // no g, still on a system stack
	MOVD	g_m(g), R10
	MOVD	m_g0(R10), R11
	CMP	R11, g
	BEQ	g0stack

	MOVD	(g_sched+gobuf_sp)(R11), R5
	MOVD	R5, RSP

g0stack:
	BL	(FARG)
	MOVD	R19, RSP

	LEAQ	sec+0(FP), DX
	MOVQ	-8(DX), CX	// Sets CX to function return address.
	MOVQ	CX, m_vdsoPC(BX)
	MOVQ	DX, m_vdsoSP(BX)

	CMPQ	R14, m_curg(BX)	// Only switch if on curg.
	JNE	noswitch

	MOVQ	m_g0(BX), DX
	MOVQ	(g_sched+gobuf_sp)(DX), SP	// Set SP to g0 stack

noswitch:
	SUBQ	$32, SP		// Space for two time results
	ANDQ	$~15, SP	// Align for C code

	MOVL	$0, DI // CLOCK_REALTIME
	LEAQ	16(SP), SI

	get_tls(R12)
	MOVQ	g(R12), R14
	MOVQ	SP, R12		// callee-saved, preserved across the CALL
	CMPQ	R14, $0
	JE	call	// no g; still on a system stack

	MOVQ	g_m(R14), R13
	// Switch to g0 stack.
	MOVQ	m_g0(R13), R10
	CMPQ	R10, R14
	JE	call	// already on g0

	MOVQ	(g_sched+gobuf_sp)(R10), SP
call:
	ANDQ	$~15, SP	// alignment for gcc ABI
	CALL	AX
	MOVQ	R12, SP

	// Get info from the current goroutine
	MOVD	runtime·tls_g(SB), R10  // g offset in TLS
	MOVD	0(R10), g
	MOVD	g_m(g), R7		// m for g
	MOVD	R1, R16			// callee-saved, preserved across C call
	MOVD	m_g0(R7), R10		// g0 for m
	CMP	R10, g			// same g0?
	BEQ	call			// already on g0
	MOVD	(g_sched+gobuf_sp)(R10), R1 // switch R1
call:
	// prepare frame for C ABI
	SUB	$32, R1			// create frame for callee saving LR, CR, R2 etc.

	get_tls(R12)
	MOVQ	g(R12), R14
	MOVQ	SP, R12		// callee-saved, preserved across the CALL
	CMPQ	R14, $0
	JE	call	// no g; still on a system stack

	MOVQ	g_m(R14), R13
	// Switch to g0 stack.
	MOVQ	m_g0(R13), R10
	CMPQ	R10, R14
	JE	call	// already on g0

	MOVQ	(g_sched+gobuf_sp)(R10), SP
call:
	ANDQ	$~15, SP	// alignment for gcc ABI
	CALL	AX
	MOVQ	R12, SP

	ADD	$const_stackGuard, R3
	MOVD	R3, g_stackguard0(g)
	MOVD	R3, g_stackguard1(g)

	// set the per-goroutine and per-mach "registers"
	MOVD	$runtime·m0(SB), R3

	// save m->g0 = g0
	MOVD	g, m_g0(R3)
	// save m0 to g0->m
	MOVD	R3, g_m(g)

	BL	runtime·check(SB)

	// args are already prepared
	BL	runtime·args(SB)
	BL	runtime·osinit(SB)
	BL	runtime·schedinit(SB)

	JEQ	skiperrno2
	MOVL	0(AX), AX
	MOVQ	AX, libcall_err(DI)

skiperrno2:
	RET

// uint32 tstart_sysvicall(M *newm);
TEXT runtime·tstart_sysvicall(SB),NOSPLIT,$0
	// DI contains first arg newm
	MOVQ	m_g0(DI), DX		// g

	// Make TLS entries point at g and m.
	get_tls(BX)
	MOVQ	DX, g(BX)
	MOVQ	DI, g_m(DX)

	// Layout new m scheduler stack on os stack.
	MOVQ	SP, AX
	MOVQ	AX, (g_stack+stack_hi)(DX)