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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	// +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		MOVB	runtime·iscgo(SB), R31
    27		CMP	R31, $0
    28		BEQ	nocgo
    29		MOVD	runtime·tls_g(SB), R31
    30		MOVD	g, 0(R13)(R31*1)
    31	
    32	nocgo:
    33		RET
    34	
    35	// load_g loads the g register from pthread-provided
    36	// thread-local memory, for use after calling externally compiled
    37	// ppc64 code that overwrote those registers.
    38	//
    39	// This is never called directly from C code (it doesn't have to
    40	// follow the C ABI), but it may be called from a C context, where the
    41	// usual Go registers aren't set up.
    42	//
    43	// NOTE: _cgo_topofstack assumes this only clobbers g (R30), and R31.
    44	TEXT runtime·load_g(SB),NOSPLIT|NOFRAME,$0-0
    45		MOVD	runtime·tls_g(SB), R31
    46		MOVD	0(R13)(R31*1), g
    47		RET
    48	
    49	GLOBL runtime·tls_g+0(SB), TLSBSS, $8

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