Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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) \
16do { \
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 ".section __ex_table,\"a\"\n" \
35 " .align 8\n" \
36 " .quad 0b,3b\n" \
37 ".previous" \
38 : "=r"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1), \
39 "=&D" (__d2) \
40 : "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
41 : "memory"); \
42} while (0)
43
44long
45__strncpy_from_user(char *dst, const char __user *src, long count)
46{
47 long res;
48 __do_strncpy_from_user(dst, src, count, res);
49 return res;
50}
51EXPORT_SYMBOL(__strncpy_from_user);
52
53long
54strncpy_from_user(char *dst, const char __user *src, long count)
55{
56 long res = -EFAULT;
57 if (access_ok(VERIFY_READ, src, 1))
58 return __strncpy_from_user(dst, src, count);
59 return res;
60}
61EXPORT_SYMBOL(strncpy_from_user);
62
63/*
64 * Zero Userspace
65 */
66
67unsigned long __clear_user(void __user *addr, unsigned long size)
68{
69 long __d0;
70 might_sleep();
71 /* no memory constraint because it doesn't change any memory gcc knows
72 about */
73 asm volatile(
74 " testq %[size8],%[size8]\n"
75 " jz 4f\n"
76 "0: movq %[zero],(%[dst])\n"
77 " addq %[eight],%[dst]\n"
78 " decl %%ecx ; jnz 0b\n"
79 "4: movq %[size1],%%rcx\n"
80 " testl %%ecx,%%ecx\n"
81 " jz 2f\n"
82 "1: movb %b[zero],(%[dst])\n"
83 " incq %[dst]\n"
84 " decl %%ecx ; jnz 1b\n"
85 "2:\n"
86 ".section .fixup,\"ax\"\n"
87 "3: lea 0(%[size1],%[size8],8),%[size8]\n"
88 " jmp 2b\n"
89 ".previous\n"
90 ".section __ex_table,\"a\"\n"
91 " .align 8\n"
92 " .quad 0b,3b\n"
93 " .quad 1b,2b\n"
94 ".previous"
95 : [size8] "=c"(size), [dst] "=&D" (__d0)
96 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
97 [zero] "r" (0UL), [eight] "r" (8UL));
98 return size;
99}
100EXPORT_SYMBOL(__clear_user);
101
102unsigned long clear_user(void __user *to, unsigned long n)
103{
104 if (access_ok(VERIFY_WRITE, to, n))
105 return __clear_user(to, n);
106 return n;
107}
108EXPORT_SYMBOL(clear_user);
109
110/*
111 * Return the size of a string (including the ending 0)
112 *
113 * Return 0 on exception, a value greater than N if too long
114 */
115
116long __strnlen_user(const char __user *s, long n)
117{
118 long res = 0;
119 char c;
120
121 while (1) {
122 if (res>n)
123 return n+1;
124 if (__get_user(c, s))
125 return 0;
126 if (!c)
127 return res+1;
128 res++;
129 s++;
130 }
131}
132EXPORT_SYMBOL(__strnlen_user);
133
134long strnlen_user(const char __user *s, long n)
135{
136 if (!access_ok(VERIFY_READ, s, n))
137 return 0;
138 return __strnlen_user(s, n);
139}
140EXPORT_SYMBOL(strnlen_user);
141
142long strlen_user(const char __user *s)
143{
144 long res = 0;
145 char c;
146
147 for (;;) {
148 if (get_user(c, s))
149 return 0;
150 if (!c)
151 return res+1;
152 res++;
153 s++;
154 }
155}
156EXPORT_SYMBOL(strlen_user);
157
158unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
159{
160 if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {
161 return copy_user_generic((__force void *)to, (__force void *)from, len);
162 }
163 return len;
164}
165EXPORT_SYMBOL(copy_in_user);
166