/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */

#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/asm-extable.h>
#include <asm/cpu.h>
#include <asm/export.h>
#include <asm/regdef.h>

.irp to, 0, 1, 2, 3, 4, 5, 6, 7
.L_fixup_handle_\to\():
	addi.d	a0, a1, (\to) * (-8)
	jr	ra
.endr

SYM_FUNC_START(__clear_user)
	/*
	 * Some CPUs support hardware unaligned access
	 */
	ALTERNATIVE	"b __clear_user_generic",	\
			"b __clear_user_fast", CPU_FEATURE_UAL
SYM_FUNC_END(__clear_user)

EXPORT_SYMBOL(__clear_user)

/*
 * unsigned long __clear_user_generic(void *addr, size_t size)
 *
 * a0: addr
 * a1: size
 */
SYM_FUNC_START(__clear_user_generic)
	beqz	a1, 2f

1:	st.b	zero, a0, 0
	addi.d	a0, a0, 1
	addi.d	a1, a1, -1
	bgtz	a1, 1b

2:	move	a0, a1
	jr	ra

	_asm_extable 1b, .L_fixup_handle_0
SYM_FUNC_END(__clear_user_generic)

/*
 * unsigned long __clear_user_fast(void *addr, unsigned long size)
 *
 * a0: addr
 * a1: size
 */
SYM_FUNC_START(__clear_user_fast)
	beqz	a1, 10f

	ori	a2, zero, 64
	blt	a1, a2, 9f

	/* set 64 bytes at a time */
1:	st.d	zero, a0, 0
2:	st.d	zero, a0, 8
3:	st.d	zero, a0, 16
4:	st.d	zero, a0, 24
5:	st.d	zero, a0, 32
6:	st.d	zero, a0, 40
7:	st.d	zero, a0, 48
8:	st.d	zero, a0, 56

	addi.d	a0, a0, 64
	addi.d	a1, a1, -64
	bge	a1, a2, 1b

	beqz	a1, 10f

	/* set the remaining bytes */
9:	st.b	zero, a0, 0
	addi.d	a0, a0, 1
	addi.d	a1, a1, -1
	bgt	a1, zero, 9b

	/* return */
10:	move	a0, a1
	jr	ra

	/* fixup and ex_table */
	_asm_extable 1b, .L_fixup_handle_0
	_asm_extable 2b, .L_fixup_handle_1
	_asm_extable 3b, .L_fixup_handle_2
	_asm_extable 4b, .L_fixup_handle_3
	_asm_extable 5b, .L_fixup_handle_4
	_asm_extable 6b, .L_fixup_handle_5
	_asm_extable 7b, .L_fixup_handle_6
	_asm_extable 8b, .L_fixup_handle_7
	_asm_extable 9b, .L_fixup_handle_0
SYM_FUNC_END(__clear_user_fast)