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 any 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/string.h>
11
12 #include <asm/segment.h>
13
14 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) })
15
16 #ifndef KERNEL_DS
17 #define KERNEL_DS MAKE_MM_SEG(~0UL)
18 #endif
19
20 #ifndef USER_DS
21 #define USER_DS MAKE_MM_SEG(TASK_SIZE - 1)
22 #endif
23
24 #ifndef get_fs
25 #define get_ds() (KERNEL_DS)
26 #define get_fs() (current_thread_info()->addr_limit)
27
set_fs(mm_segment_t fs)28 static inline void set_fs(mm_segment_t fs)
29 {
30 current_thread_info()->addr_limit = fs;
31 }
32 #endif
33
34 #ifndef segment_eq
35 #define segment_eq(a, b) ((a).seg == (b).seg)
36 #endif
37
38 #define VERIFY_READ 0
39 #define VERIFY_WRITE 1
40
41 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr),(size))
42
43 /*
44 * The architecture should really override this if possible, at least
45 * doing a check on the get_fs()
46 */
47 #ifndef __access_ok
__access_ok(unsigned long addr,unsigned long size)48 static inline int __access_ok(unsigned long addr, unsigned long size)
49 {
50 return 1;
51 }
52 #endif
53
54 /*
55 * The exception table consists of pairs of addresses: the first is the
56 * address of an instruction that is allowed to fault, and the second is
57 * the address at which the program should continue. No registers are
58 * modified, so it is entirely up to the continuation code to figure out
59 * what to do.
60 *
61 * All the routines below use bits of fixup code that are out of line
62 * with the main instruction path. This means when everything is well,
63 * we don't even have to jump over them. Further, they do not intrude
64 * on our cache or tlb entries.
65 */
66
67 struct exception_table_entry
68 {
69 unsigned long insn, fixup;
70 };
71
72 /* Returns 0 if exception not found and fixup otherwise. */
73 extern unsigned long search_exception_table(unsigned long);
74
75 /*
76 * architectures with an MMU should override these two
77 */
78 #ifndef __copy_from_user
__copy_from_user(void * to,const void __user * from,unsigned long n)79 static inline __must_check long __copy_from_user(void *to,
80 const void __user * from, unsigned long n)
81 {
82 if (__builtin_constant_p(n)) {
83 switch(n) {
84 case 1:
85 *(u8 *)to = *(u8 __force *)from;
86 return 0;
87 case 2:
88 *(u16 *)to = *(u16 __force *)from;
89 return 0;
90 case 4:
91 *(u32 *)to = *(u32 __force *)from;
92 return 0;
93 #ifdef CONFIG_64BIT
94 case 8:
95 *(u64 *)to = *(u64 __force *)from;
96 return 0;
97 #endif
98 default:
99 break;
100 }
101 }
102
103 memcpy(to, (const void __force *)from, n);
104 return 0;
105 }
106 #endif
107
108 #ifndef __copy_to_user
__copy_to_user(void __user * to,const void * from,unsigned long n)109 static inline __must_check long __copy_to_user(void __user *to,
110 const void *from, unsigned long n)
111 {
112 if (__builtin_constant_p(n)) {
113 switch(n) {
114 case 1:
115 *(u8 __force *)to = *(u8 *)from;
116 return 0;
117 case 2:
118 *(u16 __force *)to = *(u16 *)from;
119 return 0;
120 case 4:
121 *(u32 __force *)to = *(u32 *)from;
122 return 0;
123 #ifdef CONFIG_64BIT
124 case 8:
125 *(u64 __force *)to = *(u64 *)from;
126 return 0;
127 #endif
128 default:
129 break;
130 }
131 }
132
133 memcpy((void __force *)to, from, n);
134 return 0;
135 }
136 #endif
137
138 /*
139 * These are the main single-value transfer routines. They automatically
140 * use the right size if we just have the right pointer type.
141 * This version just falls back to copy_{from,to}_user, which should
142 * provide a fast-path for small values.
143 */
144 #define __put_user(x, ptr) \
145 ({ \
146 __typeof__(*(ptr)) __x = (x); \
147 int __pu_err = -EFAULT; \
148 __chk_user_ptr(ptr); \
149 switch (sizeof (*(ptr))) { \
150 case 1: \
151 case 2: \
152 case 4: \
153 case 8: \
154 __pu_err = __put_user_fn(sizeof (*(ptr)), \
155 ptr, &__x); \
156 break; \
157 default: \
158 __put_user_bad(); \
159 break; \
160 } \
161 __pu_err; \
162 })
163
164 #define put_user(x, ptr) \
165 ({ \
166 void *__p = (ptr); \
167 might_fault(); \
168 access_ok(VERIFY_WRITE, __p, sizeof(*ptr)) ? \
169 __put_user((x), ((__typeof__(*(ptr)) *)__p)) : \
170 -EFAULT; \
171 })
172
173 #ifndef __put_user_fn
174
__put_user_fn(size_t size,void __user * ptr,void * x)175 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
176 {
177 size = __copy_to_user(ptr, x, size);
178 return size ? -EFAULT : size;
179 }
180
181 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
182
183 #endif
184
185 extern int __put_user_bad(void) __attribute__((noreturn));
186
187 #define __get_user(x, ptr) \
188 ({ \
189 int __gu_err = -EFAULT; \
190 __chk_user_ptr(ptr); \
191 switch (sizeof(*(ptr))) { \
192 case 1: { \
193 unsigned char __x; \
194 __gu_err = __get_user_fn(sizeof (*(ptr)), \
195 ptr, &__x); \
196 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
197 break; \
198 }; \
199 case 2: { \
200 unsigned short __x; \
201 __gu_err = __get_user_fn(sizeof (*(ptr)), \
202 ptr, &__x); \
203 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
204 break; \
205 }; \
206 case 4: { \
207 unsigned int __x; \
208 __gu_err = __get_user_fn(sizeof (*(ptr)), \
209 ptr, &__x); \
210 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
211 break; \
212 }; \
213 case 8: { \
214 unsigned long long __x; \
215 __gu_err = __get_user_fn(sizeof (*(ptr)), \
216 ptr, &__x); \
217 (x) = *(__force __typeof__(*(ptr)) *) &__x; \
218 break; \
219 }; \
220 default: \
221 __get_user_bad(); \
222 break; \
223 } \
224 __gu_err; \
225 })
226
227 #define get_user(x, ptr) \
228 ({ \
229 const void *__p = (ptr); \
230 might_fault(); \
231 access_ok(VERIFY_READ, __p, sizeof(*ptr)) ? \
232 __get_user((x), (__typeof__(*(ptr)) *)__p) : \
233 ((x) = (__typeof__(*(ptr)))0,-EFAULT); \
234 })
235
236 #ifndef __get_user_fn
__get_user_fn(size_t size,const void __user * ptr,void * x)237 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
238 {
239 size_t n = __copy_from_user(x, ptr, size);
240 if (unlikely(n)) {
241 memset(x + (size - n), 0, n);
242 return -EFAULT;
243 }
244 return 0;
245 }
246
247 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
248
249 #endif
250
251 extern int __get_user_bad(void) __attribute__((noreturn));
252
253 #ifndef __copy_from_user_inatomic
254 #define __copy_from_user_inatomic __copy_from_user
255 #endif
256
257 #ifndef __copy_to_user_inatomic
258 #define __copy_to_user_inatomic __copy_to_user
259 #endif
260
copy_from_user(void * to,const void __user * from,unsigned long n)261 static inline long copy_from_user(void *to,
262 const void __user * from, unsigned long n)
263 {
264 unsigned long res = n;
265 might_fault();
266 if (likely(access_ok(VERIFY_READ, from, n)))
267 res = __copy_from_user(to, from, n);
268 if (unlikely(res))
269 memset(to + (n - res), 0, res);
270 return res;
271 }
272
copy_to_user(void __user * to,const void * from,unsigned long n)273 static inline long copy_to_user(void __user *to,
274 const void *from, unsigned long n)
275 {
276 might_fault();
277 if (access_ok(VERIFY_WRITE, to, n))
278 return __copy_to_user(to, from, n);
279 else
280 return n;
281 }
282
283 /*
284 * Copy a null terminated string from userspace.
285 */
286 #ifndef __strncpy_from_user
287 static inline long
__strncpy_from_user(char * dst,const char __user * src,long count)288 __strncpy_from_user(char *dst, const char __user *src, long count)
289 {
290 char *tmp;
291 strncpy(dst, (const char __force *)src, count);
292 for (tmp = dst; *tmp && count > 0; tmp++, count--)
293 ;
294 return (tmp - dst);
295 }
296 #endif
297
298 static inline long
strncpy_from_user(char * dst,const char __user * src,long count)299 strncpy_from_user(char *dst, const char __user *src, long count)
300 {
301 if (!access_ok(VERIFY_READ, src, 1))
302 return -EFAULT;
303 return __strncpy_from_user(dst, src, count);
304 }
305
306 /*
307 * Return the size of a string (including the ending 0)
308 *
309 * Return 0 on exception, a value greater than N if too long
310 */
311 #ifndef __strnlen_user
312 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
313 #endif
314
315 /*
316 * Unlike strnlen, strnlen_user includes the nul terminator in
317 * its returned count. Callers should check for a returned value
318 * greater than N as an indication the string is too long.
319 */
strnlen_user(const char __user * src,long n)320 static inline long strnlen_user(const char __user *src, long n)
321 {
322 if (!access_ok(VERIFY_READ, src, 1))
323 return 0;
324 return __strnlen_user(src, n);
325 }
326
strlen_user(const char __user * src)327 static inline long strlen_user(const char __user *src)
328 {
329 return strnlen_user(src, 32767);
330 }
331
332 /*
333 * Zero Userspace
334 */
335 #ifndef __clear_user
336 static inline __must_check unsigned long
__clear_user(void __user * to,unsigned long n)337 __clear_user(void __user *to, unsigned long n)
338 {
339 memset((void __force *)to, 0, n);
340 return 0;
341 }
342 #endif
343
344 static inline __must_check unsigned long
clear_user(void __user * to,unsigned long n)345 clear_user(void __user *to, unsigned long n)
346 {
347 might_fault();
348 if (!access_ok(VERIFY_WRITE, to, n))
349 return n;
350
351 return __clear_user(to, n);
352 }
353
354 #endif /* __ASM_GENERIC_UACCESS_H */
355