Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * User address space access functions. | |
3 | * | |
4 | * Copyright 1997 Andi Kleen <ak@muc.de> | |
5 | * Copyright 1997 Linus Torvalds | |
6 | * Copyright 2002 Andi Kleen <ak@suse.de> | |
7 | */ | |
2ee60e17 | 8 | #include <linux/module.h> |
1da177e4 LT |
9 | #include <asm/uaccess.h> |
10 | ||
1da177e4 LT |
11 | /* |
12 | * Zero Userspace | |
13 | */ | |
14 | ||
15 | unsigned long __clear_user(void __user *addr, unsigned long size) | |
16 | { | |
17 | long __d0; | |
3ee1afa3 | 18 | might_fault(); |
1da177e4 LT |
19 | /* no memory constraint because it doesn't change any memory gcc knows |
20 | about */ | |
63bcff2a | 21 | stac(); |
1da177e4 LT |
22 | asm volatile( |
23 | " testq %[size8],%[size8]\n" | |
24 | " jz 4f\n" | |
25 | "0: movq %[zero],(%[dst])\n" | |
26 | " addq %[eight],%[dst]\n" | |
27 | " decl %%ecx ; jnz 0b\n" | |
28 | "4: movq %[size1],%%rcx\n" | |
29 | " testl %%ecx,%%ecx\n" | |
30 | " jz 2f\n" | |
31 | "1: movb %b[zero],(%[dst])\n" | |
32 | " incq %[dst]\n" | |
33 | " decl %%ecx ; jnz 1b\n" | |
34 | "2:\n" | |
35 | ".section .fixup,\"ax\"\n" | |
36 | "3: lea 0(%[size1],%[size8],8),%[size8]\n" | |
37 | " jmp 2b\n" | |
38 | ".previous\n" | |
8da804f2 PA |
39 | _ASM_EXTABLE(0b,3b) |
40 | _ASM_EXTABLE(1b,2b) | |
e0a96129 | 41 | : [size8] "=&c"(size), [dst] "=&D" (__d0) |
1da177e4 LT |
42 | : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr), |
43 | [zero] "r" (0UL), [eight] "r" (8UL)); | |
63bcff2a | 44 | clac(); |
1da177e4 LT |
45 | return size; |
46 | } | |
2ee60e17 | 47 | EXPORT_SYMBOL(__clear_user); |
1da177e4 LT |
48 | |
49 | unsigned long clear_user(void __user *to, unsigned long n) | |
50 | { | |
51 | if (access_ok(VERIFY_WRITE, to, n)) | |
52 | return __clear_user(to, n); | |
53 | return n; | |
54 | } | |
2ee60e17 | 55 | EXPORT_SYMBOL(clear_user); |
1da177e4 | 56 | |
1da177e4 LT |
57 | unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len) |
58 | { | |
59 | if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) { | |
60 | return copy_user_generic((__force void *)to, (__force void *)from, len); | |
61 | } | |
62 | return len; | |
63 | } | |
2ee60e17 AK |
64 | EXPORT_SYMBOL(copy_in_user); |
65 | ||
1129585a VM |
66 | /* |
67 | * Try to copy last bytes and clear the rest if needed. | |
68 | * Since protection fault in copy_from/to_user is not a normal situation, | |
69 | * it is not necessary to optimize tail handling. | |
70 | */ | |
277d5b40 | 71 | __visible unsigned long |
1129585a VM |
72 | copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest) |
73 | { | |
74 | char c; | |
75 | unsigned zero_len; | |
76 | ||
66db3feb | 77 | for (; len; --len, to++) { |
1129585a VM |
78 | if (__get_user_nocheck(c, from++, sizeof(char))) |
79 | break; | |
66db3feb | 80 | if (__put_user_nocheck(c, to, sizeof(char))) |
1129585a VM |
81 | break; |
82 | } | |
83 | ||
84 | for (c = 0, zero_len = len; zerorest && zero_len; --zero_len) | |
85 | if (__put_user_nocheck(c, to++, sizeof(char))) | |
86 | break; | |
63bcff2a | 87 | clac(); |
1129585a VM |
88 | return len; |
89 | } |