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 */
8 #include <linux/module.h>
9 #include <asm/uaccess.h>
10
11 /*
12 * Copy a null terminated string from userspace.
13 */
14
15 #define __do_strncpy_from_user(dst,src,count,res) \
16 do { \
17 long __d0, __d1, __d2; \
18 might_sleep(); \
19 __asm__ __volatile__( \
20 " testq %1,%1\n" \
21 " jz 2f\n" \
22 "0: lodsb\n" \
23 " stosb\n" \
24 " testb %%al,%%al\n" \
25 " jz 1f\n" \
26 " decq %1\n" \
27 " jnz 0b\n" \
28 "1: subq %1,%0\n" \
29 "2:\n" \
30 ".section .fixup,\"ax\"\n" \
31 "3: movq %5,%0\n" \
32 " jmp 2b\n" \
33 ".previous\n" \
34 _ASM_EXTABLE(0b,3b) \
35 : "=r"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1), \
36 "=&D" (__d2) \
37 : "i"(-EFAULT), ""(count), "1"(count), "3"(src), "4"(dst) \
38 : "memory"); \
39 } while (0)
40
41 long
42 __strncpy_from_user(char *dst, const char __user *src, long count)
43 {
44 long res;
45 __do_strncpy_from_user(dst, src, count, res);
46 return res;
47 }
48 EXPORT_SYMBOL(__strncpy_from_user);
49
50 long
51 strncpy_from_user(char *dst, const char __user *src, long count)
52 {
53 long res = -EFAULT;
54 if (access_ok(VERIFY_READ, src, 1))
55 return __strncpy_from_user(dst, src, count);
56 return res;
57 }
58 EXPORT_SYMBOL(strncpy_from_user);
59
60 /*
61 * Zero Userspace
62 */
63
64 unsigned long __clear_user(void __user *addr, unsigned long size)
65 {
66 long __d0;
67 might_sleep();
68 /* no memory constraint because it doesn't change any memory gcc knows
69 about */
70 asm volatile(
71 " testq %[size8],%[size8]\n"
72 " jz 4f\n"
73 "0: movq %[zero],(%[dst])\n"
74 " addq %[eight],%[dst]\n"
75 " decl %%ecx ; jnz 0b\n"
76 "4: movq %[size1],%%rcx\n"
77 " testl %%ecx,%%ecx\n"
78 " jz 2f\n"
79 "1: movb %b[zero],(%[dst])\n"
80 " incq %[dst]\n"
81 " decl %%ecx ; jnz 1b\n"
82 "2:\n"
83 ".section .fixup,\"ax\"\n"
84 "3: lea 0(%[size1],%[size8],8),%[size8]\n"
85 " jmp 2b\n"
86 ".previous\n"
87 _ASM_EXTABLE(0b,3b)
88 _ASM_EXTABLE(1b,2b)
89 : [size8] "=c"(size), [dst] "=&D" (__d0)
90 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
91 [zero] "r" (0UL), [eight] "r" (8UL));
92 return size;
93 }
94 EXPORT_SYMBOL(__clear_user);
95
96 unsigned long clear_user(void __user *to, unsigned long n)
97 {
98 if (access_ok(VERIFY_WRITE, to, n))
99 return __clear_user(to, n);
100 return n;
101 }
102 EXPORT_SYMBOL(clear_user);
103
104 /*
105 * Return the size of a string (including the ending 0)
106 *
107 * Return 0 on exception, a value greater than N if too long
108 */
109
110 long __strnlen_user(const char __user *s, long n)
111 {
112 long res = 0;
113 char c;
114
115 while (1) {
116 if (res>n)
117 return n+1;
118 if (__get_user(c, s))
119 return 0;
120 if (!c)
121 return res+1;
122 res++;
123 s++;
124 }
125 }
126 EXPORT_SYMBOL(__strnlen_user);
127
128 long strnlen_user(const char __user *s, long n)
129 {
130 if (!access_ok(VERIFY_READ, s, n))
131 return 0;
132 return __strnlen_user(s, n);
133 }
134 EXPORT_SYMBOL(strnlen_user);
135
136 long strlen_user(const char __user *s)
137 {
138 long res = 0;
139 char c;
140
141 for (;;) {
142 if (get_user(c, s))
143 return 0;
144 if (!c)
145 return res+1;
146 res++;
147 s++;
148 }
149 }
150 EXPORT_SYMBOL(strlen_user);
151
152 unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
153 {
154 if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {
155 return copy_user_generic((__force void *)to, (__force void *)from, len);
156 }
157 return len;
158 }
159 EXPORT_SYMBOL(copy_in_user);
160
161
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