2 * Based on arch/arm/lib/clear_user.S
4 * Copyright (C) 2012 ARM Ltd.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 #include <linux/linkage.h>
20 #include <asm/asm-uaccess.h>
24 /* Prototype: int __arch_clear_user(void *addr, size_t sz)
25 * Purpose : clear some user memory
26 * Params : addr - user memory address to clear
27 * : sz - number of bytes to clear
28 * Returns : number of bytes NOT cleared
30 * Alignment fixed up by hardware.
32 ENTRY(__arch_clear_user)
33 uaccess_enable_not_uao x2, x3, x4
34 mov x2, x1 // save the size for fixup return
38 uao_user_alternative 9f, str, sttr, xzr, x0, 8
43 uao_user_alternative 9f, str, sttr, wzr, x0, 4
47 uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
51 uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
53 uaccess_disable_not_uao x2, x3
55 ENDPROC(__arch_clear_user)
59 9: mov x0, x2 // return the original size