libucontext/arch/loongarch64/makecontext.S

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/*
* Copyright (c) 2021 Peng Fan <fanpeng@loongson.cn>
*
* 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"
#define LOCALSZ (6)
#define A3_OFF (FRAMESZ - (5 * REG_SZ))
#define A4_OFF (FRAMESZ - (4 * REG_SZ))
#define A5_OFF (FRAMESZ - (3 * REG_SZ))
#define A6_OFF (FRAMESZ - (2 * REG_SZ))
#define A7_OFF (FRAMESZ - (1 * REG_SZ))
ALIAS(makecontext, libucontext_makecontext)
FUNC(libucontext_makecontext)
PUSH_FRAME(libucontext_makecontext)
move $t5, $a0
move $t4, $a1
/* store $a3 through $a7 to the stack frame. */
st.d $a3, $sp, A3_OFF
st.d $a4, $sp, A4_OFF
st.d $a5, $sp, A5_OFF
st.d $a6, $sp, A6_OFF
st.d $a7, $sp, A7_OFF
/* set $zero in the mcontext to 1. */
addi.d $v0, $zero, 1
st.d $v0, $t5, REG_OFFSET(0)
/* ensure the stack is aligned on a quad-word boundary. */
ld.d $t0, $t5, UCONTEXT_STACK_PTR
ld.d $t2, $t5, UCONTEXT_STACK_SIZE
/* the third argument(from zero), that's the first argument of func() */
addi.d $t1, $sp, A3_OFF
add.d $t0, $t0, $t2
addi.d $t7, $zero, ALMASK
and $t0, $t0, $t7
/* number of args */
beq $a2, $zero, no_more_arguments
bltu $a2, $zero, no_more_arguments
/* store register arguments. */
addi.d $t2, $t5, MCONTEXT_GREGS + (4 * REG_SZ)
move $t3, $zero
store_register_arg:
addi.d $t3, $t3, 1
ld.d $v1, $t1, 0
addi.d $t1, $t1, REG_SZ
st.d $v1, $t2, 0
addi.d $t2, $t2, REG_SZ
addi.d $t6, $zero, 8
bltu $t3, $t6, store_register_arg
bgeu $t3, $a2, no_more_arguments
/* make room for stack arguments. */
sub.d $t2, $a2, $t3
addi.d $t6, $zero, 3
sll.d $t2, $t2, $t6
sub.d $t0, $t0, $t2
addi.d $t6, $zero, ALMASK
and $t0, $t0, $t6
/* store stack arguments. */
move $t2, $t0
store_stack_arg:
addi.d $t3, $t3, 1
ld.d $v1, $t1, 0
addi.d $t1, $t1, REG_SZ
st.d $v1, $t2, 0
addi.d $t2, $t2, REG_SZ
bltu $t3, $a2, store_stack_arg
no_more_arguments:
/* trampoline setup. */
la.got $t8, libucontext_trampoline
ld.d $v1, $t5, UCONTEXT_UC_LINK
st.d $v1, $t5, REG_OFFSET(23)
st.d $t0, $t5, REG_OFFSET(3)
st.d $t8, $t5, REG_OFFSET(1)
st.d $t4, $t5, MCONTEXT_PC
POP_FRAME(libucontext_makecontext)
jr $ra
END(libucontext_makecontext)