xref: /openbmc/linux/arch/x86/lib/usercopy_64.c (revision 22246614)
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), "0"(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