Text file
src/runtime/tls_ppc64x.s
Documentation: runtime
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 //go:build ppc64 || ppc64le
6 // +build ppc64 ppc64le
7
8 #include "go_asm.h"
9 #include "go_tls.h"
10 #include "funcdata.h"
11 #include "textflag.h"
12
13 // We have to resort to TLS variable to save g (R30).
14 // One reason is that external code might trigger
15 // SIGSEGV, and our runtime.sigtramp don't even know we
16 // are in external code, and will continue to use R30,
17 // this might well result in another SIGSEGV.
18
19 // save_g saves the g register into pthread-provided
20 // thread-local memory, so that we can call externally compiled
21 // ppc64 code that will overwrite this register.
22 //
23 // If !iscgo, this is a no-op.
24 //
25 // NOTE: setg_gcc<> assume this clobbers only R31.
26 TEXT runtime·save_g(SB),NOSPLIT|NOFRAME,$0-0
27 #ifndef GOOS_aix
28 MOVBZ runtime·iscgo(SB), R31
29 CMP R31, $0
30 BEQ nocgo
31 #endif
32 MOVD runtime·tls_g(SB), R31
33 MOVD g, 0(R31)
34
35 nocgo:
36 RET
37
38 // load_g loads the g register from pthread-provided
39 // thread-local memory, for use after calling externally compiled
40 // ppc64 code that overwrote those registers.
41 //
42 // This is never called directly from C code (it doesn't have to
43 // follow the C ABI), but it may be called from a C context, where the
44 // usual Go registers aren't set up.
45 //
46 // NOTE: _cgo_topofstack assumes this only clobbers g (R30), and R31.
47 TEXT runtime·load_g(SB),NOSPLIT|NOFRAME,$0-0
48 MOVD runtime·tls_g(SB), R31
49 MOVD 0(R31), g
50 RET
51
52 GLOBL runtime·tls_g+0(SB), TLSBSS+DUPOK, $8
53
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