libucontext/arch/aarch64/swapcontext.S

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/*
* Copyright (c) 2018 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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str xzr, [x0, #REG_OFFSET(0)]
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/* save GPRs */
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stp x2, x3, [x0, #REG_OFFSET(2)]
stp x4, x5, [x0, #REG_OFFSET(4)]
stp x6, x7, [x0, #REG_OFFSET(6)]
stp x8, x9, [x0, #REG_OFFSET(8)]
stp x10, x11, [x0, #REG_OFFSET(10)]
stp x12, x13, [x0, #REG_OFFSET(12)]
stp x14, x15, [x0, #REG_OFFSET(14)]
stp x16, x17, [x0, #REG_OFFSET(16)]
stp x18, x19, [x0, #REG_OFFSET(18)]
stp x20, x21, [x0, #REG_OFFSET(20)]
stp x22, x23, [x0, #REG_OFFSET(22)]
stp x24, x25, [x0, #REG_OFFSET(24)]
stp x26, x27, [x0, #REG_OFFSET(26)]
stp x28, x29, [x0, #REG_OFFSET(28)]
str x30, [x0, #REG_OFFSET(30)]
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/* save current program counter in link register */
str x30, [x0, #PC_OFFSET]
/* save current stack pointer */
mov x2, sp
str x2, [x0, #SP_OFFSET]
/* save pstate */
str xzr, [x0, #PSTATE_OFFSET]
/* context to swap to is in x1 so... we move to x0 and call setcontext */
/* store our link register in x28 */
mov x28, x30
/* move x1 to x0 and call setcontext */
mov x0, x1
bl libucontext_setcontext
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/* hmm, we came back here try to return */
mov x30, x28
ret
END(libucontext_swapcontext)