diff options
Diffstat (limited to 'arch/arm64/lib/strncpy_from_user.S')
| -rw-r--r-- | arch/arm64/lib/strncpy_from_user.S | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/arch/arm64/lib/strncpy_from_user.S b/arch/arm64/lib/strncpy_from_user.S new file mode 100644 index 00000000000..56e448a831a --- /dev/null +++ b/arch/arm64/lib/strncpy_from_user.S @@ -0,0 +1,50 @@ +/* + * 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 |