Text file src/runtime/tls_ppc64x.s

     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.
    25	TEXT 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	
    34	nocgo:
    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.
    46	TEXT 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	
    51	GLOBL runtime·tls_g+0(SB), TLSBSS+DUPOK, $8

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