1// Copyright 2014 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// +build ppc64 ppc64le
6
7#include "go_asm.h"
8#include "go_tls.h"
9#include "funcdata.h"
10#include "textflag.h"
11
12// We have to resort to TLS variable to save g (R30).
13// One reason is that external code might trigger
14// SIGSEGV, and our runtime.sigtramp don't even know we
15// are in external code, and will continue to use R30,
16// this might well result in another SIGSEGV.
17
18// save_g saves the g register into pthread-provided
19// thread-local memory, so that we can call externally compiled
20// ppc64 code that will overwrite this register.
21//
22// If !iscgo, this is a no-op.
23//
24// NOTE: setg_gcc<> assume this clobbers only R31.
25TEXT runtime·save_g(SB),NOSPLIT|NOFRAME,$0-0
26#ifndef GOOS_aix
27	MOVBZ	runtime·iscgo(SB), R31
28	CMP	R31, $0
29	BEQ	nocgo
30#endif
31	MOVD	runtime·tls_g(SB), R31
32	MOVD	g, 0(R13)(R31*1)
33
34nocgo:
35	RET
36
37// load_g loads the g register from pthread-provided
38// thread-local memory, for use after calling externally compiled
39// ppc64 code that overwrote those registers.
40//
41// This is never called directly from C code (it doesn't have to
42// follow the C ABI), but it may be called from a C context, where the
43// usual Go registers aren't set up.
44//
45// NOTE: _cgo_topofstack assumes this only clobbers g (R30), and R31.
46TEXT runtime·load_g(SB),NOSPLIT|NOFRAME,$0-0
47	MOVD	runtime·tls_g(SB), R31
48	MOVD	0(R13)(R31*1), g
49	RET
50
51GLOBL runtime·tls_g+0(SB), TLSBSS+DUPOK, $8
52