1// Copyright 2016 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
7// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
8// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
9// Use a local trampoline, to avoid taking the address of a dynamically exported
10// function.
11TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
12	MOVD	_crosscall2_ptr(SB), R1
13	MOVD	$crosscall2_trampoline<>(SB), R2
14	MOVD	R2, (R1)
15	RET
16
17TEXT crosscall2_trampoline<>(SB),NOSPLIT,$0-0
18	JMP	crosscall2(SB)
19
20// Called by C code generated by cmd/cgo.
21// func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
22// Saves C callee-saved registers and calls cgocallback with three arguments.
23// fn is the PC of a func(a unsafe.Pointer) function.
24TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
25	// Start with standard C stack frame layout and linkage.
26
27	// Save R6-R15 in the register save area of the calling function.
28	STMG	R6, R15, 48(R15)
29
30	// Allocate 96 bytes on the stack.
31	MOVD	$-96(R15), R15
32
33	// Save F8-F15 in our stack frame.
34	FMOVD	F8, 32(R15)
35	FMOVD	F9, 40(R15)
36	FMOVD	F10, 48(R15)
37	FMOVD	F11, 56(R15)
38	FMOVD	F12, 64(R15)
39	FMOVD	F13, 72(R15)
40	FMOVD	F14, 80(R15)
41	FMOVD	F15, 88(R15)
42
43	// Initialize Go ABI environment.
44	BL	runtime·load_g(SB)
45
46	MOVD	R2, 8(R15)	// fn unsafe.Pointer
47	MOVD	R3, 16(R15)	// a unsafe.Pointer
48	// Skip R4 = n uint32
49	MOVD	R5, 24(R15)	// ctxt uintptr
50	BL	runtime·cgocallback(SB)
51
52	FMOVD	32(R15), F8
53	FMOVD	40(R15), F9
54	FMOVD	48(R15), F10
55	FMOVD	56(R15), F11
56	FMOVD	64(R15), F12
57	FMOVD	72(R15), F13
58	FMOVD	80(R15), F14
59	FMOVD	88(R15), F15
60
61	// De-allocate stack frame.
62	MOVD	$96(R15), R15
63
64	// Restore R6-R15.
65	LMG	48(R15), R6, R15
66
67	RET
68
69