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Diffstat (limited to 'arch/arm64/lib/copy_from_user.S')
-rw-r--r-- | arch/arm64/lib/copy_from_user.S | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S new file mode 100644 index 0000000..5e27add --- /dev/null +++ b/arch/arm64/lib/copy_from_user.S @@ -0,0 +1,66 @@ +/* + * 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> + +/* + * Copy from user space to a kernel buffer (alignment handled by the hardware) + * + * Parameters: + * x0 - to + * x1 - from + * x2 - n + * Returns: + * x0 - bytes not copied + */ +ENTRY(__copy_from_user) + add x4, x1, x2 // upper user buffer boundary + subs x2, x2, #8 + b.mi 2f +1: +USER(9f, ldr x3, [x1], #8 ) + subs x2, x2, #8 + str x3, [x0], #8 + b.pl 1b +2: adds x2, x2, #4 + b.mi 3f +USER(9f, ldr w3, [x1], #4 ) + sub x2, x2, #4 + str w3, [x0], #4 +3: adds x2, x2, #2 + b.mi 4f +USER(9f, ldrh w3, [x1], #2 ) + sub x2, x2, #2 + strh w3, [x0], #2 +4: adds x2, x2, #1 + b.mi 5f +USER(9f, ldrb w3, [x1] ) + strb w3, [x0] +5: mov x0, #0 + ret +ENDPROC(__copy_from_user) + + .section .fixup,"ax" + .align 2 +9: sub x2, x4, x1 + mov x3, x2 +10: strb wzr, [x0], #1 // zero remaining buffer space + subs x3, x3, #1 + b.ne 10b + mov x0, x2 // bytes not copied + ret + .previous |