1// Copyright 2009 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_amd64.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	MOVQ	_crosscall2_ptr(SB), AX
14	MOVQ	$crosscall2_trampoline<>(SB), BX
15	MOVQ	BX, (AX)
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.
25// This signature is known to SWIG, so we can't change it.
26TEXT crosscall2(SB),NOSPLIT,$0-0
27	PUSH_REGS_HOST_TO_ABI0()
28
29	// Make room for arguments to cgocallback.
30	ADJSP	$0x18
31#ifndef GOOS_windows
32	MOVQ	DI, 0x0(SP)	/* fn */
33	MOVQ	SI, 0x8(SP)	/* arg */
34	// Skip n in DX.
35	MOVQ	CX, 0x10(SP)	/* ctxt */
36#else
37	MOVQ	CX, 0x0(SP)	/* fn */
38	MOVQ	DX, 0x8(SP)	/* arg */
39	// Skip n in R8.
40	MOVQ	R9, 0x10(SP)	/* ctxt */
41#endif
42
43	CALL	runtime·cgocallback(SB)
44
45	ADJSP	$-0x18
46	POP_REGS_HOST_TO_ABI0()
47	RET
48