include/asm-x86/uaccess_32.h

   1 #ifndef __i386_UACCESS_H
   2 #define __i386_UACCESS_H
   3
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/errno.h>
   8 #include <linux/thread_info.h>
   9 #include <linux/prefetch.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13
  14 /*
  15  * movsl can be slow when source and dest are not both 8-byte aligned
  16  */
  17 #ifdef CONFIG_X86_INTEL_USERCOPY
  18 extern struct movsl_mask {
  19         int mask;
  20 } ____cacheline_aligned_in_smp movsl_mask;
  21 #endif
  22
  23 extern void __put_user_bad(void);
  24
  25 /*
  26  * Strange magic calling convention: pointer in %ecx,
  27  * value in %eax(:%edx), return value in %eax, no clobbers.
  28  */
  29 extern void __put_user_1(void);
  30 extern void __put_user_2(void);
  31 extern void __put_user_4(void);
  32 extern void __put_user_8(void);
  33
  34 #define __put_user_x(size, x, ptr)                              \
  35         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
  36                      :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
  37
  38 #define __put_user_8(x, ptr)                                    \
  39         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
  40                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
  41
  42
  43 /**
  44  * put_user: - Write a simple value into user space.
  45  * @x:   Value to copy to user space.
  46  * @ptr: Destination address, in user space.
  47  *
  48  * Context: User context only.  This function may sleep.
  49  *
  50  * This macro copies a single simple value from kernel space to user
  51  * space.  It supports simple types like char and int, but not larger
  52  * data types like structures or arrays.
  53  *
  54  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
  55  * to the result of dereferencing @ptr.
  56  *
  57  * Returns zero on success, or -EFAULT on error.
  58  */
  59 #ifdef CONFIG_X86_WP_WORKS_OK
  60
  61 #define put_user(x, ptr)                                        \
  62 ({                                                              \
  63         int __ret_pu;                                           \
  64         __typeof__(*(ptr)) __pu_val;                            \
  65         __chk_user_ptr(ptr);                                    \
  66         __pu_val = x;                                           \
  67         switch (sizeof(*(ptr))) {                               \
  68         case 1:                                                 \
  69                 __put_user_x(1, __pu_val, ptr);                 \
  70                 break;                                          \
  71         case 2:                                                 \
  72                 __put_user_x(2, __pu_val, ptr);                 \
  73                 break;                                          \
  74         case 4:                                                 \
  75                 __put_user_x(4, __pu_val, ptr);                 \
  76                 break;                                          \
  77         case 8:                                                 \
  78                 __put_user_8(__pu_val, ptr);                    \
  79                 break;                                          \
  80         default:                                                \
  81                 __put_user_x(X, __pu_val, ptr);                 \
  82                 break;                                          \
  83         }                                                       \
  84         __ret_pu;                                               \
  85 })
  86
  87 #else
  88 #define put_user(x, ptr)                                        \
  89 ({                                                              \
  90         int __ret_pu;                                           \
  91         __typeof__(*(ptr))__pus_tmp = x;                        \
  92         __ret_pu = 0;                                           \
  93         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
  94                                        sizeof(*(ptr))) != 0))   \
  95                 __ret_pu = -EFAULT;                             \
  96         __ret_pu;                                               \
  97 })
  98
  99
 100 #endif
 101
 102 /**
 103  * __get_user: - Get a simple variable from user space, with less checking.
 104  * @x:   Variable to store result.
 105  * @ptr: Source address, in user space.
 106  *
 107  * Context: User context only.  This function may sleep.
 108  *
 109  * This macro copies a single simple variable from user space to kernel
 110  * space.  It supports simple types like char and int, but not larger
 111  * data types like structures or arrays.
 112  *
 113  * @ptr must have pointer-to-simple-variable type, and the result of
 114  * dereferencing @ptr must be assignable to @x without a cast.
 115  *
 116  * Caller must check the pointer with access_ok() before calling this
 117  * function.
 118  *
 119  * Returns zero on success, or -EFAULT on error.
 120  * On error, the variable @x is set to zero.
 121  */
 122 #define __get_user(x, ptr)                              \
 123         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 124
 125
 126 /**
 127  * __put_user: - Write a simple value into user space, with less checking.
 128  * @x:   Value to copy to user space.
 129  * @ptr: Destination address, in user space.
 130  *
 131  * Context: User context only.  This function may sleep.
 132  *
 133  * This macro copies a single simple value from kernel space to user
 134  * space.  It supports simple types like char and int, but not larger
 135  * data types like structures or arrays.
 136  *
 137  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 138  * to the result of dereferencing @ptr.
 139  *
 140  * Caller must check the pointer with access_ok() before calling this
 141  * function.
 142  *
 143  * Returns zero on success, or -EFAULT on error.
 144  */
 145 #define __put_user(x, ptr)                                              \
 146         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 147
 148 #define __put_user_nocheck(x, ptr, size)                        \
 149 ({                                                              \
 150         long __pu_err;                                          \
 151         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 152         __pu_err;                                               \
 153 })
 154
 155
 156 #define __put_user_u64(x, addr, err)                                    \
 157         asm volatile("1:        movl %%eax,0(%2)\n"                     \
 158                      "2:        movl %%edx,4(%2)\n"                     \
 159                      "3:\n"                                             \
 160                      ".section .fixup,\"ax\"\n"                         \
 161                      "4:        movl %3,%0\n"                           \
 162                      "  jmp 3b\n"                                       \
 163                      ".previous\n"                                      \
 164                      _ASM_EXTABLE(1b, 4b)                               \
 165                      _ASM_EXTABLE(2b, 4b)                               \
 166                      : "=r" (err)                                       \
 167                      : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
 168
 169 #ifdef CONFIG_X86_WP_WORKS_OK
 170
 171 #define __put_user_size(x, ptr, size, retval, errret)                   \
 172 do {                                                                    \
 173         retval = 0;                                                     \
 174         __chk_user_ptr(ptr);                                            \
 175         switch (size) {                                                 \
 176         case 1:                                                         \
 177                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 178                 break;                                                  \
 179         case 2:                                                         \
 180                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 181                 break;                                                  \
 182         case 4:                                                         \
 183                 __put_user_asm(x, ptr, retval, "l", "",  "ir", errret); \
 184                 break;                                                  \
 185         case 8:                                                         \
 186                 __put_user_u64((__typeof__(*ptr))(x), ptr, retval);     \
 187                 break;                                                  \
 188         default:                                                        \
 189                 __put_user_bad();                                       \
 190         }                                                               \
 191 } while (0)
 192
 193 #else
 194
 195 #define __put_user_size(x, ptr, size, retval, errret)                   \
 196 do {                                                                    \
 197         __typeof__(*(ptr))__pus_tmp = x;                                \
 198         retval = 0;                                                     \
 199                                                                         \
 200         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
 201                 retval = errret;                                        \
 202 } while (0)
 203
 204 #endif
 205 struct __large_struct { unsigned long buf[100]; };
 206 #define __m(x) (*(struct __large_struct __user *)(x))
 207
 208 /*
 209  * Tell gcc we read from memory instead of writing: this is because
 210  * we do not write to any memory gcc knows about, so there are no
 211  * aliasing issues.
 212  */
 213 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 214         asm volatile("1:        mov"itype" %"rtype"1,%2\n"              \
 215                      "2:\n"                                             \
 216                      ".section .fixup,\"ax\"\n"                         \
 217                      "3:        movl %3,%0\n"                           \
 218                      "  jmp 2b\n"                                       \
 219                      ".previous\n"                                      \
 220                      _ASM_EXTABLE(1b, 3b)                               \
 221                      : "=r"(err)                                        \
 222                      : ltype (x), "m" (__m(addr)), "i" (errret), "0" (err))
 223
 224
 225 #define __get_user_nocheck(x, ptr, size)                                \
 226 ({                                                                      \
 227         long __gu_err;                                                  \
 228         unsigned long __gu_val;                                         \
 229         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 230         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 231         __gu_err;                                                       \
 232 })
 233
 234 #define __get_user_size(x, ptr, size, retval, errret)                   \
 235 do {                                                                    \
 236         retval = 0;                                                     \
 237         __chk_user_ptr(ptr);                                            \
 238         switch (size) {                                                 \
 239         case 1:                                                         \
 240                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 241                 break;                                                  \
 242         case 2:                                                         \
 243                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 244                 break;                                                  \
 245         case 4:                                                         \
 246                 __get_user_asm(x, ptr, retval, "l", "", "=r", errret);  \
 247                 break;                                                  \
 248         default:                                                        \
 249                 (x) = __get_user_bad();                                 \
 250         }                                                               \
 251 } while (0)
 252
 253 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 254         asm volatile("1:        mov"itype" %2,%"rtype"1\n"              \
 255                      "2:\n"                                             \
 256                      ".section .fixup,\"ax\"\n"                         \
 257                      "3:        movl %3,%0\n"                           \
 258                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 259                      "  jmp 2b\n"                                       \
 260                      ".previous\n"                                      \
 261                      _ASM_EXTABLE(1b, 3b)                               \
 262                      : "=r" (err), ltype (x)                            \
 263                      : "m" (__m(addr)), "i" (errret), "0" (err))
 264
 265
 266 unsigned long __must_check __copy_to_user_ll
 267                 (void __user *to, const void *from, unsigned long n);
 268 unsigned long __must_check __copy_from_user_ll
 269                 (void *to, const void __user *from, unsigned long n);
 270 unsigned long __must_check __copy_from_user_ll_nozero
 271                 (void *to, const void __user *from, unsigned long n);
 272 unsigned long __must_check __copy_from_user_ll_nocache
 273                 (void *to, const void __user *from, unsigned long n);
 274 unsigned long __must_check __copy_from_user_ll_nocache_nozero
 275                 (void *to, const void __user *from, unsigned long n);
 276
 277 /**
 278  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
 279  * @to:   Destination address, in user space.
 280  * @from: Source address, in kernel space.
 281  * @n:    Number of bytes to copy.
 282  *
 283  * Context: User context only.
 284  *
 285  * Copy data from kernel space to user space.  Caller must check
 286  * the specified block with access_ok() before calling this function.
 287  * The caller should also make sure he pins the user space address
 288  * so that the we don't result in page fault and sleep.
 289  *
 290  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 291  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 292  * If a store crosses a page boundary and gets a fault, the x86 will not write
 293  * anything, so this is accurate.
 294  */
 295
 296 static __always_inline unsigned long __must_check
 297 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 298 {
 299         if (__builtin_constant_p(n)) {
 300                 unsigned long ret;
 301
 302                 switch (n) {
 303                 case 1:
 304                         __put_user_size(*(u8 *)from, (u8 __user *)to,
 305                                         1, ret, 1);
 306                         return ret;
 307                 case 2:
 308                         __put_user_size(*(u16 *)from, (u16 __user *)to,
 309                                         2, ret, 2);
 310                         return ret;
 311                 case 4:
 312                         __put_user_size(*(u32 *)from, (u32 __user *)to,
 313                                         4, ret, 4);
 314                         return ret;
 315                 }
 316         }
 317         return __copy_to_user_ll(to, from, n);
 318 }
 319
 320 /**
 321  * __copy_to_user: - Copy a block of data into user space, with less checking.
 322  * @to:   Destination address, in user space.
 323  * @from: Source address, in kernel space.
 324  * @n:    Number of bytes to copy.
 325  *
 326  * Context: User context only.  This function may sleep.
 327  *
 328  * Copy data from kernel space to user space.  Caller must check
 329  * the specified block with access_ok() before calling this function.
 330  *
 331  * Returns number of bytes that could not be copied.
 332  * On success, this will be zero.
 333  */
 334 static __always_inline unsigned long __must_check
 335 __copy_to_user(void __user *to, const void *from, unsigned long n)
 336 {
 337        might_sleep();
 338        return __copy_to_user_inatomic(to, from, n);
 339 }
 340
 341 static __always_inline unsigned long
 342 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 343 {
 344         /* Avoid zeroing the tail if the copy fails..
 345          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
 346          * but as the zeroing behaviour is only significant when n is not
 347          * constant, that shouldn't be a problem.
 348          */
 349         if (__builtin_constant_p(n)) {
 350                 unsigned long ret;
 351
 352                 switch (n) {
 353                 case 1:
 354                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 355                         return ret;
 356                 case 2:
 357                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 358                         return ret;
 359                 case 4:
 360                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 361                         return ret;
 362                 }
 363         }
 364         return __copy_from_user_ll_nozero(to, from, n);
 365 }
 366
 367 /**
 368  * __copy_from_user: - Copy a block of data from user space, with less checking.
 369  * @to:   Destination address, in kernel space.
 370  * @from: Source address, in user space.
 371  * @n:    Number of bytes to copy.
 372  *
 373  * Context: User context only.  This function may sleep.
 374  *
 375  * Copy data from user space to kernel space.  Caller must check
 376  * the specified block with access_ok() before calling this function.
 377  *
 378  * Returns number of bytes that could not be copied.
 379  * On success, this will be zero.
 380  *
 381  * If some data could not be copied, this function will pad the copied
 382  * data to the requested size using zero bytes.
 383  *
 384  * An alternate version - __copy_from_user_inatomic() - may be called from
 385  * atomic context and will fail rather than sleep.  In this case the
 386  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 387  * for explanation of why this is needed.
 388  */
 389 static __always_inline unsigned long
 390 __copy_from_user(void *to, const void __user *from, unsigned long n)
 391 {
 392         might_sleep();
 393         if (__builtin_constant_p(n)) {
 394                 unsigned long ret;
 395
 396                 switch (n) {
 397                 case 1:
 398                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 399                         return ret;
 400                 case 2:
 401                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 402                         return ret;
 403                 case 4:
 404                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 405                         return ret;
 406                 }
 407         }
 408         return __copy_from_user_ll(to, from, n);
 409 }
 410
 411 #define ARCH_HAS_NOCACHE_UACCESS
 412
 413 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 414                                 const void __user *from, unsigned long n)
 415 {
 416         might_sleep();
 417         if (__builtin_constant_p(n)) {
 418                 unsigned long ret;
 419
 420                 switch (n) {
 421                 case 1:
 422                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 423                         return ret;
 424                 case 2:
 425                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 426                         return ret;
 427                 case 4:
 428                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 429                         return ret;
 430                 }
 431         }
 432         return __copy_from_user_ll_nocache(to, from, n);
 433 }
 434
 435 static __always_inline unsigned long
 436 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 437                                   unsigned long n)
 438 {
 439        return __copy_from_user_ll_nocache_nozero(to, from, n);
 440 }
 441
 442 unsigned long __must_check copy_to_user(void __user *to,
 443                                         const void *from, unsigned long n);
 444 unsigned long __must_check copy_from_user(void *to,
 445                                           const void __user *from,
 446                                           unsigned long n);
 447 long __must_check strncpy_from_user(char *dst, const char __user *src,
 448                                     long count);
 449 long __must_check __strncpy_from_user(char *dst,
 450                                       const char __user *src, long count);
 451
 452 /**
 453  * strlen_user: - Get the size of a string in user space.
 454  * @str: The string to measure.
 455  *
 456  * Context: User context only.  This function may sleep.
 457  *
 458  * Get the size of a NUL-terminated string in user space.
 459  *
 460  * Returns the size of the string INCLUDING the terminating NUL.
 461  * On exception, returns 0.
 462  *
 463  * If there is a limit on the length of a valid string, you may wish to
 464  * consider using strnlen_user() instead.
 465  */
 466 #define strlen_user(str) strnlen_user(str, LONG_MAX)
 467
 468 long strnlen_user(const char __user *str, long n);
 469 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 470 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 471
 472 #endif /* __i386_UACCESS_H */