libucontext/arch/riscv32/swapcontext.S

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2021-03-09 06:59:59 +00:00
/*
* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
*
* 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)
ALIAS(__swapcontext, libucontext_swapcontext)
FUNC(libucontext_swapcontext)
/* move $a1 to $t0 to avoid clobbering. */
mv t0, a1
sw ra, REG_OFFSET(REG_PC)(a0)
sw ra, REG_OFFSET(REG_RA)(a0)
sw sp, REG_OFFSET(REG_SP)(a0)
/* first saved register block */
sw s0, REG_OFFSET(REG_S0)(a0)
sw s1, REG_OFFSET(REG_S1)(a0)
/* return register block */
sw a0, REG_OFFSET(REG_A0)(a0)
sw a1, REG_OFFSET(REG_A1)(a0)
/* second saved register block */
sw s2, REG_OFFSET(REG_S2)(a0)
sw s3, REG_OFFSET(REG_S3)(a0)
sw s4, REG_OFFSET(REG_S4)(a0)
sw s5, REG_OFFSET(REG_S5)(a0)
sw s6, REG_OFFSET(REG_S6)(a0)
sw s7, REG_OFFSET(REG_S7)(a0)
sw s8, REG_OFFSET(REG_S8)(a0)
sw s9, REG_OFFSET(REG_S9)(a0)
sw s10, REG_OFFSET(REG_S10)(a0)
sw s11, REG_OFFSET(REG_S11)(a0)
/* restore the other context from $t0. */
lw t1, REG_OFFSET(REG_PC)(t0)
lw ra, REG_OFFSET(REG_RA)(t0)
lw sp, REG_OFFSET(REG_SP)(t0)
/* first saved register block */
lw s0, REG_OFFSET(REG_S0)(t0)
lw s1, REG_OFFSET(REG_S1)(t0)
/* return register block */
lw a0, REG_OFFSET(REG_A0)(t0)
lw a1, REG_OFFSET(REG_A1)(t0)
/* argument register block */
lw a2, REG_OFFSET(REG_A2)(t0)
lw a3, REG_OFFSET(REG_A3)(t0)
lw a4, REG_OFFSET(REG_A4)(t0)
lw a5, REG_OFFSET(REG_A5)(t0)
lw a6, REG_OFFSET(REG_A6)(t0)
lw a7, REG_OFFSET(REG_A7)(t0)
/* second saved register block */
lw s2, REG_OFFSET(REG_S2)(t0)
lw s3, REG_OFFSET(REG_S3)(t0)
lw s4, REG_OFFSET(REG_S4)(t0)
lw s5, REG_OFFSET(REG_S5)(t0)
lw s6, REG_OFFSET(REG_S6)(t0)
lw s7, REG_OFFSET(REG_S7)(t0)
lw s8, REG_OFFSET(REG_S8)(t0)
lw s9, REG_OFFSET(REG_S9)(t0)
lw s10, REG_OFFSET(REG_S10)(t0)
lw s11, REG_OFFSET(REG_S11)(t0)
/* done swapping, jump to new PC in S1 */
jr t1
END(libucontext_swapcontext)