libucontext/arch/s390x/swapcontext.S

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/*
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* Copyright (c) 2018, 2020 Ariadne Conill <ariadne@dereferenced.org>
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*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
#include "defs.h"
ALIAS(swapcontext, libucontext_swapcontext)
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FUNC(libucontext_swapcontext)
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lgr %r1, %r2 /* use %r1 to save current context to */
lgr %r0, %r3 /* use %r0 for source context */
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stam %a0, %a15, AREG_OFFSET(0)(%r1) /* store access registers */
stmg %r0, %r15, REG_OFFSET(0)(%r1) /* store general-purpose registers */
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lgr %r2, %r0 /* swap %r0 to %r2 (XXX: figure out why it hates loading from %r0) */
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lam %a2, %a15, AREG_OFFSET(2)(%r2) /* load access registers, but skip %a0 and %a1 which are for TLS */
lmg %r0, %r15, REG_OFFSET(0)(%r2) /* load general-purpose registers */
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br %r14 /* return to new link register address */
END(libucontext_swapcontext)