1 #ifndef __ASM_GENERIC_UACCESS_H
2 #define __ASM_GENERIC_UACCESS_H
3
4 /*
5 * User space memory access functions, these should work
6 * on a ny machine that has kernel and user data in the same
7 * address space, e.g. all NOMMU machines.
8 */
9 #include <linux/sched.h>
10 #include <linux/mm.h>
11 #include <linux/string.h>
12
13 #include <asm/segment.h>
14
15 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
16
17 #ifndef KERNEL_DS
18 #define KERNEL_DS MAKE_MM_SEG(~0UL)
19 #endif
20
21 #ifndef USER_DS
22 #define USER_DS MAKE_MM_SEG(TASK_SIZE - 1)
23 #endif
24
25 #ifndef get_fs
26 #define get_ds() (KERNEL_DS)
27 #define get_fs() (current_thread_info()->addr_limit)
28
set_fs(mm_segment_t fs)29 static inline void set_fs(mm_segment_t fs)
30 {
31 current_thread_info()->addr_limit = fs;
32 }
33 #endif
34
35 #define segment_eq(a, b) ((a).seg == (b).seg)
36
37 #define VERIFY_READ 0
38 #define VERIFY_WRITE 1
39
40 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr),(size))
41
42 /*
43 * The architecture should really override this if possible, at least
44 * doing a check on the get_fs()
45 */
46 #ifndef __access_ok
__access_ok(unsigned long addr,unsigned long size)47 static inline int __access_ok(unsigned long addr, unsigned long size)
48 {
49 return 1;
50 }
51 #endif
52
53 /*
54 * The exception table consists of pairs of addresses: the first is the
55 * address of an instruction that is allowed to fault, and the second is
56 * the address at which the program should continue. No registers are
57 * modified, so it is entirely up to the continuation code to figure out
58 * what to do.
59 *
60 * All the routines below use bits of fixup code that are out of line
61 * with the main instruction path. This means when everything is well,
62 * we don't even have to jump over them. Further, they do not intrude
63 * on our cache or tlb entries.
64 */
65
66 struct exception_table_entry
67 {
68 unsigned long insn, fixup;
69 };
70
71 /* Returns 0 if exception not found and fixup otherwise. */
72 extern unsigned long search_exception_table(unsigned long);
73
74 /*
75 * architectures with an MMU should override these two
76 */
77 #ifndef __copy_from_user
__copy_from_user(void * to,const void __user * from,unsigned long n)78 static inline __must_check long __copy_from_user(void *to,
79 const void __user * from, unsigned long n)
80 {
81 if (__builtin_constant_p(n)) {
82 switch(n) {
83 case 1:
84 *(u8 *)to = *(u8 __force *)from;
85 return 0;
86 case 2:
87 *(u16 *)to = *(u16 __force *)from;
88 return 0;
89 case 4:
90 *(u32 *)to = *(u32 __force *)from;
91 return 0;
92 #ifdef CONFIG_64BIT
93 case 8:
94 *(u64 *)to = *(u64 __force *)from;
95 return 0;
96 #endif
97 default:
98 break;
99 }
100 }
101
102 memcpy(to, (const void __force *)from, n);
103 return 0;
104 }
105 #endif
106
107 #ifndef __copy_to_user
__copy_to_user(void __user * to,const void * from,unsigned long n)108 static inline __must_check long __copy_to_user(void __user *to,
109 const void *from, unsigned long n)
110 {
111 if (__builtin_constant_p(n)) {
112 switch(n) {
113 case 1:
114 *(u8 __force *)to = *(u8 *)from;
115 return 0;
116 case 2:
117 *(u16 __force *)to = *(u16 *)from;
118 return 0;
119 case 4:
120 *(u32 __force *)to = *(u32 *)from;
121 return 0;
122 #ifdef CONFIG_64BIT
123 case 8:
124 *(u64 __force *)to = *(u64 *)from;
125 return 0;
126 #endif
127 default:
128 break;
129 }
130 }
131
132 memcpy((void __force *)to, from, n);
133 return 0;
134 }
135 #endif
136
137 /*
138 * These are the main single-value transfer routines. They automatically
139 * use the right size if we just have the right pointer type.
140 * This version just falls back to copy_{from,to}_user, which should
141 * provide a fast-path for small values.
142 */
143 #define __put_user(x, ptr) \
144 ({ \
145 __typeof__(*(ptr)) __x = (x); \
146 int __pu_err = -EFAULT; \
147 __chk_user_ptr(ptr); \
148 switch (sizeof (*(ptr))) { \
149 case 1: \
150 case 2: \
151 case 4: \
152 case 8: \
153 __pu_err = __put_user_fn(sizeof (*(ptr)), \
154 ptr, &__x); \
155 break; \
156 default: \
157 __put_user_bad(); \
158 break; \
159 } \
160 __pu_err; \
161 })
162
163 #define put_user(x, ptr) \
164 ({ \
165 might_sleep(); \
166 access_ok(VERIFY_WRITE, ptr, sizeof(*ptr)) ? \
167 __put_user(x, ptr) : \
168 -EFAULT; \
169 })
170
__put_user_fn(size_t size,void __user * ptr,void * x)171 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
172 {
173 size = __copy_to_user(ptr, x, size);
174 return size ? -EFAULT : size;
175 }
176
177 extern int __put_user_bad(void) __attribute__((noreturn));
178
179 #define __get_user(x, ptr) \
180 ({ \
181 int __gu_err = -EFAULT; \
182 __chk_user_ptr(ptr); \
183 switch (sizeof(*(ptr))) { \
184 case 1: { \
185 unsigned char __x; \
186 __gu_err = __get_user_fn(sizeof (*(ptr)), \
187 ptr, &__x); \
188 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
189 break; \
190 }; \
191 case 2: { \
192 unsigned short __x; \
193 __gu_err = __get_user_fn(sizeof (*(ptr)), \
194 ptr, &__x); \
195 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
196 break; \
197 }; \
198 case 4: { \
199 unsigned int __x; \
200 __gu_err = __get_user_fn(sizeof (*(ptr)), \
201 ptr, &__x); \
202 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
203 break; \
204 }; \
205 case 8: { \
206 unsigned long long __x; \
207 __gu_err = __get_user_fn(sizeof (*(ptr)), \
208 ptr, &__x); \
209 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
210 break; \
211 }; \
212 default: \
213 __get_user_bad(); \
214 break; \
215 } \
216 __gu_err; \
217 })
218
219 #define get_user(x, ptr) \
220 ({ \
221 might_sleep(); \
222 access_ok(VERIFY_READ, ptr, sizeof(*ptr)) ? \
223 __get_user(x, ptr) : \
224 -EFAULT; \
225 })
226
__get_user_fn(size_t size,const void __user * ptr,void * x)227 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
228 {
229 size = __copy_from_user(x, ptr, size);
230 return size ? -EFAULT : size;
231 }
232
233 extern int __get_user_bad(void) __attribute__((noreturn));
234
235 #ifndef __copy_from_user_inatomic
236 #define __copy_from_user_inatomic __copy_from_user
237 #endif
238
239 #ifndef __copy_to_user_inatomic
240 #define __copy_to_user_inatomic __copy_to_user
241 #endif
242
copy_from_user(void * to,const void __user * from,unsigned long n)243 static inline long copy_from_user(void *to,
244 const void __user * from, unsigned long n)
245 {
246 might_sleep();
247 if (access_ok(VERIFY_READ, from, n))
248 return __copy_from_user(to, from, n);
249 else
250 return n;
251 }
252
copy_to_user(void __user * to,const void * from,unsigned long n)253 static inline long copy_to_user(void __user *to,
254 const void *from, unsigned long n)
255 {
256 might_sleep();
257 if (access_ok(VERIFY_WRITE, to, n))
258 return __copy_to_user(to, from, n);
259 else
260 return n;
261 }
262
263 /*
264 * Copy a null terminated string from userspace.
265 */
266 #ifndef __strncpy_from_user
267 static inline long
__strncpy_from_user(char * dst,const char __user * src,long count)268 __strncpy_from_user(char *dst, const char __user *src, long count)
269 {
270 char *tmp;
271 strncpy(dst, (const char __force *)src, count);
272 for (tmp = dst; *tmp && count > 0; tmp++, count--)
273 ;
274 return (tmp - dst);
275 }
276 #endif
277
278 static inline long
strncpy_from_user(char * dst,const char __user * src,long count)279 strncpy_from_user(char *dst, const char __user *src, long count)
280 {
281 if (!access_ok(VERIFY_READ, src, 1))
282 return -EFAULT;
283 return __strncpy_from_user(dst, src, count);
284 }
285
286 /*
287 * Return the size of a string (including the ending 0)
288 *
289 * Return 0 on exception, a value greater than N if too long
290 */
291 #ifndef __strnlen_user
292 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
293 #endif
294
295 /*
296 * Unlike strnlen, strnlen_user includes the nul terminator in
297 * its returned count. Callers should check for a returned value
298 * greater than N as an indication the string is too long.
299 */
strnlen_user(const char __user * src,long n)300 static inline long strnlen_user(const char __user *src, long n)
301 {
302 if (!access_ok(VERIFY_READ, src, 1))
303 return 0;
304 return __strnlen_user(src, n);
305 }
306
strlen_user(const char __user * src)307 static inline long strlen_user(const char __user *src)
308 {
309 return strnlen_user(src, 32767);
310 }
311
312 /*
313 * Zero Userspace
314 */
315 #ifndef __clear_user
316 static inline __must_check unsigned long
__clear_user(void __user * to,unsigned long n)317 __clear_user(void __user *to, unsigned long n)
318 {
319 memset((void __force *)to, 0, n);
320 return 0;
321 }
322 #endif
323
324 static inline __must_check unsigned long
clear_user(void __user * to,unsigned long n)325 clear_user(void __user *to, unsigned long n)
326 {
327 might_sleep();
328 if (!access_ok(VERIFY_WRITE, to, n))
329 return n;
330
331 return __clear_user(to, n);
332 }
333
334 #endif /* __ASM_GENERIC_UACCESS_H */
335