| /* | |
| * Based on arch/arm/lib/strncpy_from_user.S | |
| * | |
| * Copyright (C) 1995-2000 Russell King | |
| * 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/assembler.h> | |
| #include <asm/errno.h> | |
| .text | |
| .align 5 | |
| /* | |
| * Copy a string from user space to kernel space. | |
| * x0 = dst, x1 = src, x2 = byte length | |
| * returns the number of characters copied (strlen of copied string), | |
| * -EFAULT on exception, or "len" if we fill the whole buffer | |
| */ | |
| ENTRY(__strncpy_from_user) | |
| mov x4, x1 | |
| 1: subs x2, x2, #1 | |
| bmi 2f | |
| USER(9f, ldrb w3, [x1], #1 ) | |
| strb w3, [x0], #1 | |
| cbnz w3, 1b | |
| sub x1, x1, #1 // take NUL character out of count | |
| 2: sub x0, x1, x4 | |
| ret | |
| ENDPROC(__strncpy_from_user) | |
| .section .fixup,"ax" | |
| .align 0 | |
| 9: strb wzr, [x0] // null terminate | |
| mov x0, #-EFAULT | |
| ret | |
| .previous |