aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/lib/usercopy_64.c
blob: 893d43f838ccd0186a6ef6869594358de12fd303 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
/* 
 * User address space access functions.
 *
 * Copyright 1997 Andi Kleen <ak@muc.de>
 * Copyright 1997 Linus Torvalds
 * Copyright 2002 Andi Kleen <ak@suse.de>
 */
#include <linux/module.h>
#include <asm/uaccess.h>

/*
 * Copy a null terminated string from userspace.
 */

#define __do_strncpy_from_user(dst,src,count,res)			   \
do {									   \
	long __d0, __d1, __d2;						   \
	might_sleep();							   \
	__asm__ __volatile__(						   \
		"	testq %1,%1\n"					   \
		"	jz 2f\n"					   \
		"0:	lodsb\n"					   \
		"	stosb\n"					   \
		"	testb %%al,%%al\n"				   \
		"	jz 1f\n"					   \
		"	decq %1\n"					   \
		"	jnz 0b\n"					   \
		"1:	subq %1,%0\n"					   \
		"2:\n"							   \
		".section .fixup,\"ax\"\n"				   \
		"3:	movq %5,%0\n"					   \
		"	jmp 2b\n"					   \
		".previous\n"						   \
		".section __ex_table,\"a\"\n"				   \
		"	.align 8\n"					   \
		"	.quad 0b,3b\n"					   \
		".previous"						   \
		: "=r"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1),	   \
		  "=&D" (__d2)						   \
		: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
		: "memory");						   \
} while (0)

long
__strncpy_from_user(char *dst, const char __user *src, long count)
{
	long res;
	__do_strncpy_from_user(dst, src, count, res);
	return res;
}
EXPORT_SYMBOL(__strncpy_from_user);

long
strncpy_from_user(char *dst, const char __user *src, long count)
{
	long res = -EFAULT;
	if (access_ok(VERIFY_READ, src, 1))
		return __strncpy_from_user(dst, src, count);
	return res;
}
EXPORT_SYMBOL(strncpy_from_user);

/*
 * Zero Userspace
 */

unsigned long __clear_user(void __user *addr, unsigned long size)
{
	long __d0;
	might_sleep();
	/* no memory constraint because it doesn't change any memory gcc knows
	   about */
	asm volatile(
		"	testq  %[size8],%[size8]\n"
		"	jz     4f\n"
		"0:	movq %[zero],(%[dst])\n"
		"	addq   %[eight],%[dst]\n"
		"	decl %%ecx ; jnz   0b\n"
		"4:	movq  %[size1],%%rcx\n"
		"	testl %%ecx,%%ecx\n"
		"	jz     2f\n"
		"1:	movb   %b[zero],(%[dst])\n"
		"	incq   %[dst]\n"
		"	decl %%ecx ; jnz  1b\n"
		"2:\n"
		".section .fixup,\"ax\"\n"
		"3:	lea 0(%[size1],%[size8],8),%[size8]\n"
		"	jmp 2b\n"
		".previous\n"
		".section __ex_table,\"a\"\n"
		"       .align 8\n"
		"	.quad 0b,3b\n"
		"	.quad 1b,2b\n"
		".previous"
		: [size8] "=c"(size), [dst] "=&D" (__d0)
		: [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
		  [zero] "r" (0UL), [eight] "r" (8UL));
	return size;
}
EXPORT_SYMBOL(__clear_user);

unsigned long clear_user(void __user *to, unsigned long n)
{
	if (access_ok(VERIFY_WRITE, to, n))
		return __clear_user(to, n);
	return n;
}
EXPORT_SYMBOL(clear_user);

/*
 * Return the size of a string (including the ending 0)
 *
 * Return 0 on exception, a value greater than N if too long
 */

long __strnlen_user(const char __user *s, long n)
{
	long res = 0;
	char c;

	while (1) {
		if (res>n)
			return n+1;
		if (__get_user(c, s))
			return 0;
		if (!c)
			return res+1;
		res++;
		s++;
	}
}
EXPORT_SYMBOL(__strnlen_user);

long strnlen_user(const char __user *s, long n)
{
	if (!access_ok(VERIFY_READ, s, n))
		return 0;
	return __strnlen_user(s, n);
}
EXPORT_SYMBOL(strnlen_user);

long strlen_user(const char __user *s)
{
	long res = 0;
	char c;

	for (;;) {
		if (get_user(c, s))
			return 0;
		if (!c)
			return res+1;
		res++;
		s++;
	}
}
EXPORT_SYMBOL(strlen_user);

unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
{
	if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) { 
		return copy_user_generic((__force void *)to, (__force void *)from, len);
	} 
	return len;		
}
EXPORT_SYMBOL(copy_in_user);