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 /*
  73  * architectures with an MMU should override these two
  74  */
  75 #ifndef __copy_from_user
  76 static inline __must_check long __copy_from_user(void *to,
  77                 const void __user * from, unsigned long n)
  78 {
  79         if (__builtin_constant_p(n)) {
  80                 switch(n) {
  81                 case 1:
  82                         *(u8 *)to = *(u8 __force *)from;
  83                         return 0;
  84                 case 2:
  85                         *(u16 *)to = *(u16 __force *)from;
  86                         return 0;
  87                 case 4:
  88                         *(u32 *)to = *(u32 __force *)from;
  89                         return 0;
  90 #ifdef CONFIG_64BIT
  91                 case 8:
  92                         *(u64 *)to = *(u64 __force *)from;
  93                         return 0;
  94 #endif
  95                 default:
  96                         break;
  97                 }
  98         }
  99
 100         memcpy(to, (const void __force *)from, n);
 101         return 0;
 102 }
 103 #endif
 104
 105 #ifndef __copy_to_user
 106 static inline __must_check long __copy_to_user(void __user *to,
 107                 const void *from, unsigned long n)
 108 {
 109         if (__builtin_constant_p(n)) {
 110                 switch(n) {
 111                 case 1:
 112                         *(u8 __force *)to = *(u8 *)from;
 113                         return 0;
 114                 case 2:
 115                         *(u16 __force *)to = *(u16 *)from;
 116                         return 0;
 117                 case 4:
 118                         *(u32 __force *)to = *(u32 *)from;
 119                         return 0;
 120 #ifdef CONFIG_64BIT
 121                 case 8:
 122                         *(u64 __force *)to = *(u64 *)from;
 123                         return 0;
 124 #endif
 125                 default:
 126                         break;
 127                 }
 128         }
 129
 130         memcpy((void __force *)to, from, n);
 131         return 0;
 132 }
 133 #endif
 134
 135 /*
 136  * These are the main single-value transfer routines.  They automatically
 137  * use the right size if we just have the right pointer type.
 138  * This version just falls back to copy_{from,to}_user, which should
 139  * provide a fast-path for small values.
 140  */
 141 #define __put_user(x, ptr) \
 142 ({                                                              \
 143         __typeof__(*(ptr)) __x = (x);                           \
 144         int __pu_err = -EFAULT;                                 \
 145         __chk_user_ptr(ptr);                                    \
 146         switch (sizeof (*(ptr))) {                              \
 147         case 1:                                                 \
 148         case 2:                                                 \
 149         case 4:                                                 \
 150         case 8:                                                 \
 151                 __pu_err = __put_user_fn(sizeof (*(ptr)),       \
 152                                          ptr, &__x);            \
 153                 break;                                          \
 154         default:                                                \
 155                 __put_user_bad();                               \
 156                 break;                                          \
 157          }                                                      \
 158         __pu_err;                                               \
 159 })
 160
 161 #define put_user(x, ptr)                                        \
 162 ({                                                              \
 163         void *__p = (ptr);                                      \
 164         might_fault();                                          \
 165         access_ok(VERIFY_WRITE, __p, sizeof(*ptr)) ?            \
 166                 __put_user((x), ((__typeof__(*(ptr)) *)__p)) :  \
 167                 -EFAULT;                                        \
 168 })
 169
 170 #ifndef __put_user_fn
 171
 172 static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
 173 {
 174         size = __copy_to_user(ptr, x, size);
 175         return size ? -EFAULT : size;
 176 }
 177
 178 #define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
 179
 180 #endif
 181
 182 extern int __put_user_bad(void) __attribute__((noreturn));
 183
 184 #define __get_user(x, ptr)                                      \
 185 ({                                                              \
 186         int __gu_err = -EFAULT;                                 \
 187         __chk_user_ptr(ptr);                                    \
 188         switch (sizeof(*(ptr))) {                               \
 189         case 1: {                                               \
 190                 unsigned char __x;                              \
 191                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 192                                          ptr, &__x);            \
 193                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 194                 break;                                          \
 195         };                                                      \
 196         case 2: {                                               \
 197                 unsigned short __x;                             \
 198                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 199                                          ptr, &__x);            \
 200                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 201                 break;                                          \
 202         };                                                      \
 203         case 4: {                                               \
 204                 unsigned int __x;                               \
 205                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 206                                          ptr, &__x);            \
 207                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 208                 break;                                          \
 209         };                                                      \
 210         case 8: {                                               \
 211                 unsigned long long __x;                         \
 212                 __gu_err = __get_user_fn(sizeof (*(ptr)),       \
 213                                          ptr, &__x);            \
 214                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
 215                 break;                                          \
 216         };                                                      \
 217         default:                                                \
 218                 __get_user_bad();                               \
 219                 break;                                          \
 220         }                                                       \
 221         __gu_err;                                               \
 222 })
 223
 224 #define get_user(x, ptr)                                        \
 225 ({                                                              \
 226         const void *__p = (ptr);                                \
 227         might_fault();                                          \
 228         access_ok(VERIFY_READ, __p, sizeof(*ptr)) ?             \
 229                 __get_user((x), (__typeof__(*(ptr)) *)__p) :    \
 230                 ((x) = (__typeof__(*(ptr)))0,-EFAULT);          \
 231 })
 232
 233 #ifndef __get_user_fn
 234 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 235 {
 236         size_t n = __copy_from_user(x, ptr, size);
 237         if (unlikely(n)) {
 238                 memset(x + (size - n), 0, n);
 239                 return -EFAULT;
 240         }
 241         return 0;
 242 }
 243
 244 #define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
 245
 246 #endif
 247
 248 extern int __get_user_bad(void) __attribute__((noreturn));
 249
 250 #ifndef __copy_from_user_inatomic
 251 #define __copy_from_user_inatomic __copy_from_user
 252 #endif
 253
 254 #ifndef __copy_to_user_inatomic
 255 #define __copy_to_user_inatomic __copy_to_user
 256 #endif
 257
 258 static inline long copy_from_user(void *to,
 259                 const void __user * from, unsigned long n)
 260 {
 261         unsigned long res = n;
 262         might_fault();
 263         if (likely(access_ok(VERIFY_READ, from, n)))
 264                 res = __copy_from_user(to, from, n);
 265         if (unlikely(res))
 266                 memset(to + (n - res), 0, res);
 267         return res;
 268 }
 269
 270 static inline long copy_to_user(void __user *to,
 271                 const void *from, unsigned long n)
 272 {
 273         might_fault();
 274         if (access_ok(VERIFY_WRITE, to, n))
 275                 return __copy_to_user(to, from, n);
 276         else
 277                 return n;
 278 }
 279
 280 /*
 281  * Copy a null terminated string from userspace.
 282  */
 283 #ifndef __strncpy_from_user
 284 static inline long
 285 __strncpy_from_user(char *dst, const char __user *src, long count)
 286 {
 287         char *tmp;
 288         strncpy(dst, (const char __force *)src, count);
 289         for (tmp = dst; *tmp && count > 0; tmp++, count--)
 290                 ;
 291         return (tmp - dst);
 292 }
 293 #endif
 294
 295 static inline long
 296 strncpy_from_user(char *dst, const char __user *src, long count)
 297 {
 298         if (!access_ok(VERIFY_READ, src, 1))
 299                 return -EFAULT;
 300         return __strncpy_from_user(dst, src, count);
 301 }
 302
 303 /*
 304  * Return the size of a string (including the ending 0)
 305  *
 306  * Return 0 on exception, a value greater than N if too long
 307  */
 308 #ifndef __strnlen_user
 309 #define __strnlen_user(s, n) (strnlen((s), (n)) + 1)
 310 #endif
 311
 312 /*
 313  * Unlike strnlen, strnlen_user includes the nul terminator in
 314  * its returned count. Callers should check for a returned value
 315  * greater than N as an indication the string is too long.
 316  */
 317 static inline long strnlen_user(const char __user *src, long n)
 318 {
 319         if (!access_ok(VERIFY_READ, src, 1))
 320                 return 0;
 321         return __strnlen_user(src, n);
 322 }
 323
 324 static inline long strlen_user(const char __user *src)
 325 {
 326         return strnlen_user(src, 32767);
 327 }
 328
 329 /*
 330  * Zero Userspace
 331  */
 332 #ifndef __clear_user
 333 static inline __must_check unsigned long
 334 __clear_user(void __user *to, unsigned long n)
 335 {
 336         memset((void __force *)to, 0, n);
 337         return 0;
 338 }
 339 #endif
 340
 341 static inline __must_check unsigned long
 342 clear_user(void __user *to, unsigned long n)
 343 {
 344         might_fault();
 345         if (!access_ok(VERIFY_WRITE, to, n))
 346                 return n;
 347
 348         return __clear_user(to, n);
 349 }
 350
 351 #endif /* __ASM_GENERIC_UACCESS_H */