1// Copyright 2020 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_riscv64.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 MOV _crosscall2_ptr(SB), X7
14 MOV $crosscall2_trampoline<>(SB), X8
15 MOV X8, (X7)
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 * Push arguments for fn (X10, X11, X13), along with all callee-save
28 * registers. Note that at procedure entry the first argument is at
29 * 8(X2).
30 */
31 ADD $(-8*29), X2
32 MOV X10, (8*1)(X2) // fn unsafe.Pointer
33 MOV X11, (8*2)(X2) // a unsafe.Pointer
34 MOV X13, (8*3)(X2) // ctxt uintptr
35
36 SAVE_GPR((8*4))
37 MOV X1, (8*16)(X2)
38 SAVE_FPR((8*17))
39
40 // Initialize Go ABI environment
41 CALL runtime·load_g(SB)
42 CALL runtime·cgocallback(SB)
43
44 RESTORE_GPR((8*4))
45 MOV (8*16)(X2), X1
46 RESTORE_FPR((8*17))
47
48 ADD $(8*29), X2
49
50 RET
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