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Text file src/runtime/tls_s390x.s

Documentation: runtime

     1	// Copyright 2016 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 "go_asm.h"
     6	#include "go_tls.h"
     7	#include "funcdata.h"
     8	#include "textflag.h"
     9	
    10	// We have to resort to TLS variable to save g (R13).
    11	// One reason is that external code might trigger
    12	// SIGSEGV, and our runtime.sigtramp don't even know we
    13	// are in external code, and will continue to use R13,
    14	// this might well result in another SIGSEGV.
    15	
    16	// save_g saves the g register into pthread-provided
    17	// thread-local memory, so that we can call externally compiled
    18	// s390x code that will overwrite this register.
    19	//
    20	// If !iscgo, this is a no-op.
    21	//
    22	// NOTE: setg_gcc<> assume this clobbers only R10 and R11.
    23	TEXT runtime·save_g(SB),NOSPLIT|NOFRAME,$0-0
    24		MOVB	runtime·iscgo(SB),  R10
    25		CMPBEQ	R10, $0, nocgo
    26		MOVW	AR0, R11
    27		SLD	$32, R11
    28		MOVW	AR1, R11
    29		MOVD	runtime·tls_g(SB), R10
    30		MOVD	g, 0(R10)(R11*1)
    31	nocgo:
    32		RET
    33	
    34	// load_g loads the g register from pthread-provided
    35	// thread-local memory, for use after calling externally compiled
    36	// s390x code that overwrote those registers.
    37	//
    38	// This is never called directly from C code (it doesn't have to
    39	// follow the C ABI), but it may be called from a C context, where the
    40	// usual Go registers aren't set up.
    41	//
    42	// NOTE: _cgo_topofstack assumes this only clobbers g (R13), R10 and R11.
    43	TEXT runtime·load_g(SB),NOSPLIT|NOFRAME,$0-0
    44		MOVW	AR0, R11
    45		SLD	$32, R11
    46		MOVW	AR1, R11
    47		MOVD	runtime·tls_g(SB), R10
    48		MOVD	0(R10)(R11*1), g
    49		RET
    50	
    51	GLOBL runtime·tls_g+0(SB),TLSBSS,$8

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