1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2012 ARM Ltd.
4 */
5
6#include <linux/linkage.h>
7
8#include <asm/asm-uaccess.h>
9#include <asm/assembler.h>
10#include <asm/cache.h>
11
12/*
13 * Copy from user space to a kernel buffer (alignment handled by the hardware)
14 *
15 * Parameters:
16 * x0 - to
17 * x1 - from
18 * x2 - n
19 * Returns:
20 * x0 - bytes not copied
21 */
22
23 .macro ldrb1 reg, ptr, val
24 user_ldst 9998f, ldtrb, \reg, \ptr, \val
25 .endm
26
27 .macro strb1 reg, ptr, val
28 strb \reg, [\ptr], \val
29 .endm
30
31 .macro ldrh1 reg, ptr, val
32 user_ldst 9997f, ldtrh, \reg, \ptr, \val
33 .endm
34
35 .macro strh1 reg, ptr, val
36 strh \reg, [\ptr], \val
37 .endm
38
39 .macro ldr1 reg, ptr, val
40 user_ldst 9997f, ldtr, \reg, \ptr, \val
41 .endm
42
43 .macro str1 reg, ptr, val
44 str \reg, [\ptr], \val
45 .endm
46
47 .macro ldp1 reg1, reg2, ptr, val
48 user_ldp 9997f, \reg1, \reg2, \ptr, \val
49 .endm
50
51 .macro stp1 reg1, reg2, ptr, val
52 stp \reg1, \reg2, [\ptr], \val
53 .endm
54
55 .macro cpy1 dst, src, count
56 .arch_extension mops
57 USER_CPY(9997f, 0, cpyfprt [\dst]!, [\src]!, \count!)
58 USER_CPY(9996f, 0, cpyfmrt [\dst]!, [\src]!, \count!)
59 USER_CPY(9996f, 0, cpyfert [\dst]!, [\src]!, \count!)
60 .endm
61
62end .req x5
63srcin .req x15
64SYM_FUNC_START(__arch_copy_from_user)
65 add end, x0, x2
66 mov srcin, x1
67#include "copy_template.S"
68 mov x0, #0 // Nothing to copy
69 ret
70
71 // Exception fixups
729996: b.cs 9997f
73 // Registers are in Option A format
74 add dst, dst, count
759997: cmp dst, dstin
76 b.ne 9998f
77 // Before being absolutely sure we couldn't copy anything, try harder
78USER(9998f, ldtrb tmp1w, [srcin])
79 strb tmp1w, [dst], #1
809998: sub x0, end, dst // bytes not copied
81 ret
82SYM_FUNC_END(__arch_copy_from_user)
83EXPORT_SYMBOL(__arch_copy_from_user)
84

source code of linux/arch/arm64/lib/copy_from_user.S