1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2005-2017 Andes Technology Corporation
3
4#include <linux/linkage.h>
5#include <asm/assembler.h>
6#include <asm/errno.h>
7
8/* Prototype: int __arch_clear_user(void *addr, size_t sz)
9 * Purpose  : clear some user memory
10 * Params   : addr - user memory address to clear
11 *          : sz   - number of bytes to clear
12 * Returns  : number of bytes NOT cleared
13 */
14	.text
15	.align	5
16ENTRY(__arch_clear_user)
17	add	$r5, $r0, $r1
18	beqz	$r1, clear_exit
19	xor	$p1, $p1, $p1		! Use $p1=0 to clear mem
20	srli	$p0, $r1, #2		! $p0 = number of word to clear
21	andi	$r1, $r1, #3		! Bytes less than a word to copy
22	beqz	$p0, byte_clear		! Only less than a word to clear
23word_clear:
24USER(	smw.bim,$p1, [$r0], $p1)	! Clear the word
25	addi	$p0, $p0, #-1		! Decrease word count
26	bnez	$p0, word_clear		! Continue looping to clear all words
27	beqz	$r1, clear_exit		! No left bytes to copy
28byte_clear:
29USER(	sbi.bi,	$p1, [$r0], #1)		! Clear the byte
30	addi	$r1, $r1, #-1		! Decrease byte count
31	bnez	$r1, byte_clear		! Continue looping to clear all left bytes
32clear_exit:
33	move	$r0, $r1		! Set return value
34	ret
35
36	.section .fixup,"ax"
37	.align	0
389001:
39	sub	$r0, $r5, $r0		! Bytes left to copy
40	ret
41	.previous
42ENDPROC(__arch_clear_user)
43