1// Copyright 2015 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5#include "textflag.h"
6#include "abi_arm64.h"
7
8// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
9// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
10// Use a local trampoline, to avoid taking the address of a dynamically exported
11// function.
12TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
13	MOVD	_crosscall2_ptr(SB), R1
14	MOVD	$crosscall2_trampoline<>(SB), R2
15	MOVD	R2, (R1)
16	RET
17
18TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
19	JMP	crosscall2(SB)
20
21// Called by C code generated by cmd/cgo.
22// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
23// Saves C callee-saved registers and calls cgocallback with three arguments.
24// fn is the PC of a func(a unsafe.Pointer) function.
25TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
26	/*
27	 * We still need to save all callee save register as before, and then
28	 *  push 3 args for fn (R0, R1, R3), skipping R2.
29	 * Also note that at procedure entry in gc world, 8(RSP) will be the
30	 *  first arg.
31	 */
32	SUB	$(8*24), RSP
33	STP	(R0, R1), (8*1)(RSP)
34	MOVD	R3, (8*3)(RSP)
35
36	SAVE_R19_TO_R28(8*4)
37	SAVE_F8_TO_F15(8*14)
38	STP	(R29, R30), (8*22)(RSP)
39
40
41	// Initialize Go ABI environment
42	BL	runtime·load_g(SB)
43	BL	runtime·cgocallback(SB)
44
45	RESTORE_R19_TO_R28(8*4)
46	RESTORE_F8_TO_F15(8*14)
47	LDP	(8*22)(RSP), (R29, R30)
48
49	ADD	$(8*24), RSP
50	RET
51