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 x5, x1, x2 // upper user buffer boundary 32 subs x2, x2, #16 33 b.mi 1f 340: 35USER(9f, ldp x3, x4, [x1], #16) 36 subs x2, x2, #16 37 stp x3, x4, [x0], #16 38 b.pl 0b 391: adds x2, x2, #8 40 b.mi 2f 41USER(9f, ldr x3, [x1], #8 ) 42 sub x2, x2, #8 43 str x3, [x0], #8 442: adds x2, x2, #4 45 b.mi 3f 46USER(9f, ldr w3, [x1], #4 ) 47 sub x2, x2, #4 48 str w3, [x0], #4 493: adds x2, x2, #2 50 b.mi 4f 51USER(9f, ldrh w3, [x1], #2 ) 52 sub x2, x2, #2 53 strh w3, [x0], #2 544: adds x2, x2, #1 55 b.mi 5f 56USER(9f, ldrb w3, [x1] ) 57 strb w3, [x0] 585: mov x0, #0 59 ret 60ENDPROC(__copy_from_user) 61 62 .section .fixup,"ax" 63 .align 2 649: sub x2, x5, x1 65 mov x3, x2 6610: strb wzr, [x0], #1 // zero remaining buffer space 67 subs x3, x3, #1 68 b.ne 10b 69 mov x0, x2 // bytes not copied 70 ret 71 .previous 72