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 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
  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
  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 /*
  77  * architectures with an MMU should override these two
  78  */
  79 #ifndef __copy_from_user
  80 static inline __must_check long __copy_from_user(void *to,
  81                 const void __user * from, unsigned long n)
  82 {
  83         if (__builtin_constant_p(n)) {
  84                 switch(n) {
  85                 case 1:
  86                         *(u8 *)to = *(u8 __force *)from;
  87                         return 0;
  88                 case 2:
  89                         *(u16 *)to = *(u16 __force *)from;
  90                         return 0;
  91                 case 4:
  92                         *(u32 *)to = *(u32 __force *)from;
  93                         return 0;
  94 #ifdef CONFIG_64BIT
  95                 case 8:
  96                         *(u64 *)to = *(u64 __force *)from;
  97                         return 0;
  98 #endif
  99                 default:
 100                         break;
 101                 }
 102         }
 103
 104         memcpy(to, (const void __force *)from, n);
 105         return 0;
 106 }
 107 #endif
 108
 109 #ifndef __copy_to_user
 110 static inline __must_check long __copy_to_user(void __user *to,
 111                 const void *from, unsigned long n)
 112 {
 113         if (__builtin_constant_p(n)) {
 114                 switch(n) {
 115                 case 1:
 116                         *(u8 __force *)to = *(u8 *)from;
 117                         return 0;
 118                 case 2:
 119                         *(u16 __force *)to = *(u16 *)from;
 120                         return 0;
 121                 case 4:
 122                         *(u32 __force *)to = *(u32 *)from;
 123                         return 0;
 124 #ifdef CONFIG_64BIT
 125                 case 8:
 126                         *(u64 __force *)to = *(u64 *)from;
 127                         return 0;
 128 #endif
 129                 default:
 130                         break;
 131                 }
 132         }
 133
 134         memcpy((void __force *)to, from, n);
 135         return 0;
 136 }
 137 #endif
 138
 139 /*
 140  * These are the main single-value transfer routines.  They automatically
 141  * use the right size if we just have the right pointer type.
 142  * This version just falls back to copy_{from,to}_user, which should
 143  * provide a fast-path for small values.
 144  */
 145 #define __put_user(x, ptr) \
 146 ({                                                              \
 147         __typeof__(*(ptr)) __x = (x);                           \
 148         int __pu_err = -EFAULT;                                 \
 149         __chk_user_ptr(ptr);                                    \
 150         switch (sizeof (*(ptr))) {                              \
 151         case 1:                                                 \
 152         case 2:                                                 \
 153         case 4:                                                 \
 154         case 8:                                                 \
 155                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 156                                          ptr, &__x);            \
 157                 break;                                          \
 158         default:                                                \
 159                 __put_user_bad();                               \
 160                 break;                                          \
 161          }                                                      \
 162         __pu_err;                                               \
 163 })
 164
 165 #define put_user(x, ptr)                                        \
 166 ({                                                              \
 167         void *__p = (ptr);                                      \
 168         might_fault();                                          \
 169         access_ok(VERIFY_WRITE, __p, sizeof(*ptr)) ?            \
 170                 __put_user((x), ((__typeof__(*(ptr)) *)__p)) :  \
 171                 -EFAULT;                                        \
 172 })
 173
 174 #ifndef __put_user_fn
 175
 176 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 177 {
 178         size = __copy_to_user(ptr, x, size);
 179         return size ? -EFAULT : size;
 180 }
 181
 182 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
 183
 184 #endif
 185
 186 extern int __put_user_bad(void) __attribute__((noreturn));
 187
 188 #define __get_user(x, ptr)                                      \
 189 ({                                                              \
 190         int __gu_err = -EFAULT;                                 \
 191         __chk_user_ptr(ptr);                                    \
 192         switch (sizeof(*(ptr))) {                               \
 193         case 1: {                                               \
 194                 unsigned char __x;                              \
 195                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 196                                          ptr, &__x);            \
 197                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 198                 break;                                          \
 199         };                                                      \
 200         case 2: {                                               \
 201                 unsigned short __x;                             \
 202                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 203                                          ptr, &__x);            \
 204                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 205                 break;                                          \
 206         };                                                      \
 207         case 4: {                                               \
 208                 unsigned int __x;                               \
 209                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 210                                          ptr, &__x);            \
 211                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 212                 break;                                          \
 213         };                                                      \
 214         case 8: {                                               \
 215                 unsigned long long __x;                         \
 216                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 217                                          ptr, &__x);            \
 218                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 219                 break;                                          \
 220         };                                                      \
 221         default:                                                \
 222                 __get_user_bad();                               \
 223                 break;                                          \
 224         }                                                       \
 225         __gu_err;                                               \
 226 })
 227
 228 #define get_user(x, ptr)                                        \
 229 ({                                                              \
 230         const void *__p = (ptr);                                \
 231         might_fault();                                          \
 232         access_ok(VERIFY_READ, __p, sizeof(*ptr)) ?             \
 233                 __get_user((x), (__typeof__(*(ptr)) *)__p) :    \
 234                 ((x) = (__typeof__(*(ptr)))0,-EFAULT);          \
 235 })
 236
 237 #ifndef __get_user_fn
 238 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 239 {
 240         size_t n = __copy_from_user(x, ptr, size);
 241         if (unlikely(n)) {
 242                 memset(x + (size - n), 0, n);
 243                 return -EFAULT;
 244         }
 245         return 0;
 246 }
 247
 248 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
 249
 250 #endif
 251
 252 extern int __get_user_bad(void) __attribute__((noreturn));
 253
 254 #ifndef __copy_from_user_inatomic
 255 #define __copy_from_user_inatomic __copy_from_user
 256 #endif
 257
 258 #ifndef __copy_to_user_inatomic
 259 #define __copy_to_user_inatomic __copy_to_user
 260 #endif
 261
 262 static inline long copy_from_user(void *to,
 263                 const void __user * from, unsigned long n)
 264 {
 265         unsigned long res = n;
 266         might_fault();
 267         if (likely(access_ok(VERIFY_READ, from, n)))
 268                 res = __copy_from_user(to, from, n);
 269         if (unlikely(res))
 270                 memset(to + (n - res), 0, res);
 271         return res;
 272 }
 273
 274 static inline long copy_to_user(void __user *to,
 275                 const void *from, unsigned long n)
 276 {
 277         might_fault();
 278         if (access_ok(VERIFY_WRITE, to, n))
 279                 return __copy_to_user(to, from, n);
 280         else
 281                 return n;
 282 }
 283
 284 /*
 285  * Copy a null terminated string from userspace.
 286  */
 287 #ifndef __strncpy_from_user
 288 static inline long
 289 __strncpy_from_user(char *dst, const char __user *src, long count)
 290 {
 291         char *tmp;
 292         strncpy(dst, (const char __force *)src, count);
 293         for (tmp = dst; *tmp && count > 0; tmp++, count--)
 294                 ;
 295         return (tmp - dst);
 296 }
 297 #endif
 298
 299 static inline long
 300 strncpy_from_user(char *dst, const char __user *src, long count)
 301 {
 302         if (!access_ok(VERIFY_READ, src, 1))
 303                 return -EFAULT;
 304         return __strncpy_from_user(dst, src, count);
 305 }
 306
 307 /*
 308  * Return the size of a string (including the ending 0)
 309  *
 310  * Return 0 on exception, a value greater than N if too long
 311  */
 312 #ifndef __strnlen_user
 313 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
 314 #endif
 315
 316 /*
 317  * Unlike strnlen, strnlen_user includes the nul terminator in
 318  * its returned count. Callers should check for a returned value
 319  * greater than N as an indication the string is too long.
 320  */
 321 static inline long strnlen_user(const char __user *src, long n)
 322 {
 323         if (!access_ok(VERIFY_READ, src, 1))
 324                 return 0;
 325         return __strnlen_user(src, n);
 326 }
 327
 328 static inline long strlen_user(const char __user *src)
 329 {
 330         return strnlen_user(src, 32767);
 331 }
 332
 333 /*
 334  * Zero Userspace
 335  */
 336 #ifndef __clear_user
 337 static inline __must_check unsigned long
 338 __clear_user(void __user *to, unsigned long n)
 339 {
 340         memset((void __force *)to, 0, n);
 341         return 0;
 342 }
 343 #endif
 344
 345 static inline __must_check unsigned long
 346 clear_user(void __user *to, unsigned long n)
 347 {
 348         might_fault();
 349         if (!access_ok(VERIFY_WRITE, to, n))
 350                 return n;
 351
 352         return __clear_user(to, n);
 353 }
 354
 355 #endif /* __ASM_GENERIC_UACCESS_H */