1/* 2 * Copyright (C) 2012 ARM Ltd. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public License 14 * along with this program. If not, see <http://www.gnu.org/licenses/>. 15 */ 16 17#include <linux/linkage.h> 18#include <asm/assembler.h> 19 20/* 21 * Copy from user space to a kernel buffer (alignment handled by the hardware) 22 * 23 * Parameters: 24 * x0 - to 25 * x1 - from 26 * x2 - n 27 * Returns: 28 * x0 - bytes not copied 29 */ 30ENTRY(__copy_from_user) 31 add x4, x1, x2 // upper user buffer boundary 32 subs x2, x2, #8 33 b.mi 2f 341: 35USER(9f, ldr x3, [x1], #8 ) 36 subs x2, x2, #8 37 str x3, [x0], #8 38 b.pl 1b 392: adds x2, x2, #4 40 b.mi 3f 41USER(9f, ldr w3, [x1], #4 ) 42 sub x2, x2, #4 43 str w3, [x0], #4 443: adds x2, x2, #2 45 b.mi 4f 46USER(9f, ldrh w3, [x1], #2 ) 47 sub x2, x2, #2 48 strh w3, [x0], #2 494: adds x2, x2, #1 50 b.mi 5f 51USER(9f, ldrb w3, [x1] ) 52 strb w3, [x0] 535: mov x0, #0 54 ret 55ENDPROC(__copy_from_user) 56 57 .section .fixup,"ax" 58 .align 2 599: sub x2, x4, x1 60 mov x3, x2 6110: strb wzr, [x0], #1 // zero remaining buffer space 62 subs x3, x3, #1 63 b.ne 10b 64 mov x0, x2 // bytes not copied 65 ret 66 .previous 67