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| /*
| * Based on arch/arm/lib/clear_user.S
| *
| * Copyright (C) 2012 ARM Ltd.
| *
| * This program is free software; you can redistribute it and/or modify
| * it under the terms of the GNU General Public License version 2 as
| * published by the Free Software Foundation.
| *
| * This program is distributed in the hope that it will be useful,
| * but WITHOUT ANY WARRANTY; without even the implied warranty of
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
| * GNU General Public License for more details.
| *
| * You should have received a copy of the GNU General Public License
| * along with this program. If not, see <http://www.gnu.org/licenses/>.
| */
| #include <linux/linkage.h>
|
| #include <asm/asm-uaccess.h>
|
| .text
|
| /* Prototype: int __arch_clear_user(void *addr, size_t sz)
| * Purpose : clear some user memory
| * Params : addr - user memory address to clear
| * : sz - number of bytes to clear
| * Returns : number of bytes NOT cleared
| *
| * Alignment fixed up by hardware.
| */
| ENTRY(__arch_clear_user)
| uaccess_enable_not_uao x2, x3, x4
| mov x2, x1 // save the size for fixup return
| subs x1, x1, #8
| b.mi 2f
| 1:
| uao_user_alternative 9f, str, sttr, xzr, x0, 8
| subs x1, x1, #8
| b.pl 1b
| 2: adds x1, x1, #4
| b.mi 3f
| uao_user_alternative 9f, str, sttr, wzr, x0, 4
| sub x1, x1, #4
| 3: adds x1, x1, #2
| b.mi 4f
| uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
| sub x1, x1, #2
| 4: adds x1, x1, #1
| b.mi 5f
| uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
| 5: mov x0, #0
| uaccess_disable_not_uao x2, x3
| ret
| ENDPROC(__arch_clear_user)
|
| .section .fixup,"ax"
| .align 2
| 9: mov x0, x2 // return the original size
| uaccess_disable_not_uao x2, x3
| ret
| .previous
|
|
