1/*
2 * linux/arch/unicore32/lib/clear_user.S
3 *
4 * Code specific to PKUnity SoC and UniCore ISA
5 *
6 * Copyright (C) 2001-2010 GUAN Xue-tao
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12#include <linux/linkage.h>
13#include <asm/assembler.h>
14
15		.text
16
17/* Prototype: int __clear_user(void *addr, size_t sz)
18 * Purpose  : clear some user memory
19 * Params   : addr - user memory address to clear
20 *          : sz   - number of bytes to clear
21 * Returns  : number of bytes NOT cleared
22 */
23WEAK(__clear_user)
24		stm.w	(lr), [sp-]
25		stm.w	(r1), [sp-]
26		mov	r2, #0
27		csub.a	r1, #4
28		bsl	2f
29		and.a	ip, r0, #3
30		beq	1f
31		csub.a	ip, #2
32		strusr	r2, r0, 1
33		strusr	r2, r0, 1, el
34		strusr	r2, r0, 1, sl
35		rsub	ip, ip, #4
36		sub	r1, r1, ip		@  7  6  5  4  3  2  1
371:		sub.a	r1, r1, #8		@ -1 -2 -3 -4 -5 -6 -7
38		strusr	r2, r0, 4, ns, rept=2
39		bns	1b
40		add.a	r1, r1, #4		@  3  2  1  0 -1 -2 -3
41		strusr	r2, r0, 4, ns
422:		cand.a	r1, #2			@ 1x 1x 0x 0x 1x 1x 0x
43		strusr	r2, r0, 1, ne, rept=2
44		cand.a	r1, #1			@ x1 x0 x1 x0 x1 x0 x1
45		beq	3f
46USER(		stb.u	r2, [r0])
473:		mov	r0, #0
48		ldm.w	(r1), [sp]+
49		ldm.w	(pc), [sp]+
50ENDPROC(__clear_user)
51
52		.pushsection .fixup,"ax"
53		.align	0
549001:		ldm.w	(r0), [sp]+
55		ldm.w	(pc), [sp]+
56		.popsection
57
58