kernel/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  * architectures with an MMU should override these two
  77  */
  78 #ifndef __copy_from_user
  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
 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
 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
 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
 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
 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
 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
 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  */
 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
 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
 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
 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 */