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.
    23TEXT 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)
    31nocgo:
    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.
    43TEXT 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
    51GLOBL runtime·tls_g+0(SB),TLSBSS,$8
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