include/asm-generic/uaccess.h

   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
  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
  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
  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
 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
 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
 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
 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
 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
 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
 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  */
 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
 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
 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
 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 */