forked from ariadne/libucontext
95 lines
2.5 KiB
ArmAsm
95 lines
2.5 KiB
ArmAsm
/*
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* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* This software is provided 'as is' and without any warranty, express or
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* implied. In no event shall the authors be liable for any damages arising
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* from the use of this software.
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*/
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#include "defs.h"
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ALIAS(swapcontext, libucontext_swapcontext)
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FUNC(libucontext_swapcontext)
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mov r4, r0 /* move r4 to r0, and increment by REG_OFFSET(REG_MACL) + REG_SZ. */
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add #(REG_OFFSET(REG_MACL + 1)), r0
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sts.l macl, @-r0 /* save macl/mach registers */
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sts.l mach, @-r0
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stc.l gbr, @-r0 /* save gbr register */
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movt r1 /* load T-flag into r1 */
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mov.l r1, @-r0 /* save T-flag as SR register */
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sts.l pr, @-r0 /* save current PR */
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sts.l pr, @-r0 /* save current PR as PC as well */
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mov.l r15, @-r0 /* preserve registers backwards, from r15 to r1 */
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mov.l r14, @-r0
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mov.l r13, @-r0
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mov.l r12, @-r0
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mov.l r11, @-r0
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mov.l r10, @-r0
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mov.l r9, @-r0
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mov.l r8, @-r0
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mov.l r7, @-r0
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mov.l r6, @-r0
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mov.l r5, @-r0
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mov.l r4, @-r0
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mov.l r3, @-r0
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mov.l r2, @-r0
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mov.l r1, @-r0
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mov r0, r1
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mov #0, r0
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mov.l r0, @-r1 /* preserve r0 as explicit zero */
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mov r5, r0 /* now restore the new context */
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add #(REG_OFFSET(6)), r0 /* restore GPRs r6-15 */
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mov.l @r0+, r6
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mov.l @r0+, r7
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mov.l @r0+, r8
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mov.l @r0+, r9
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mov.l @r0+, r10
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mov.l @r0+, r11
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mov.l @r0+, r12
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mov.l @r0+, r13
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mov.l @r0+, r14
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mov.l @r0+, r15
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mov.l @r0+, r2 /* restore PR */
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lds.l @r0+, pr
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mov.l @r0+, r1 /* restore T-flag */
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shlr r1
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add #REG_SZ, r0 /* skip GBR (used for TLS) */
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lds.l @r0+, mach /* load mach/macl registers */
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lds.l @r0+, macl
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mov r5, r0 /* bring r0 back to the top of the context */
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add #(REG_OFFSET(0)), r1 /* restore r0 into r1 (temporarily) */
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mov.l r1, @-r15 /* push to stack from r1 */
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mov.l r2, @-r15 /* push PC to stack */
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mov.l @(REG_OFFSET(1), r0), r1 /* restore real r1 */
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mov.l @(REG_OFFSET(2), r0), r2 /* restore real r2 */
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mov.l @(REG_OFFSET(3), r0), r3 /* restore real r3 */
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mov.l @(REG_OFFSET(4), r0), r4 /* restore real r4 */
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mov.l @(REG_OFFSET(5), r0), r5 /* restore real r5 */
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mov.l @r15+, r0 /* pop PC from stack */
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jmp @r0 /* jump to new PC */
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mov.l @r15+, r0 /* pop original r0 from stack */
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END(libucontext_swapcontext)
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