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   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 #define __addr_ok(addr)                                 \
  24         ((unsigned long __force)(addr) <                \
  25          (current_thread_info()->addr_limit.seg))
  26
  27 extern void __put_user_bad(void);
  28
  29 /*
  30  * Strange magic calling convention: pointer in %ecx,
  31  * value in %eax(:%edx), return value in %eax, no clobbers.
  32  */
  33 extern void __put_user_1(void);
  34 extern void __put_user_2(void);
  35 extern void __put_user_4(void);
  36 extern void __put_user_8(void);
  37
  38 #define __put_user_x(size, x, ptr)                              \
  39         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
  40                      :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
  41
  42 #define __put_user_8(x, ptr)                                    \
  43         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
  44                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
  45
  46
  47 /**
  48  * put_user: - Write a simple value into user space.
  49  * @x:   Value to copy to user space.
  50  * @ptr: Destination address, in user space.
  51  *
  52  * Context: User context only.  This function may sleep.
  53  *
  54  * This macro copies a single simple value from kernel space to user
  55  * space.  It supports simple types like char and int, but not larger
  56  * data types like structures or arrays.
  57  *
  58  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
  59  * to the result of dereferencing @ptr.
  60  *
  61  * Returns zero on success, or -EFAULT on error.
  62  */
  63 #ifdef CONFIG_X86_WP_WORKS_OK
  64
  65 #define put_user(x, ptr)                                        \
  66 ({                                                              \
  67         int __ret_pu;                                           \
  68         __typeof__(*(ptr)) __pu_val;                            \
  69         __chk_user_ptr(ptr);                                    \
  70         __pu_val = x;                                           \
  71         switch (sizeof(*(ptr))) {                               \
  72         case 1:                                                 \
  73                 __put_user_x(1, __pu_val, ptr);                 \
  74                 break;                                          \
  75         case 2:                                                 \
  76                 __put_user_x(2, __pu_val, ptr);                 \
  77                 break;                                          \
  78         case 4:                                                 \
  79                 __put_user_x(4, __pu_val, ptr);                 \
  80                 break;                                          \
  81         case 8:                                                 \
  82                 __put_user_8(__pu_val, ptr);                    \
  83                 break;                                          \
  84         default:                                                \
  85                 __put_user_x(X, __pu_val, ptr);                 \
  86                 break;                                          \
  87         }                                                       \
  88         __ret_pu;                                               \
  89 })
  90
  91 #else
  92 #define put_user(x, ptr)                                        \
  93 ({                                                              \
  94         int __ret_pu;                                           \
  95         __typeof__(*(ptr))__pus_tmp = x;                        \
  96         __ret_pu = 0;                                           \
  97         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
  98                                        sizeof(*(ptr))) != 0))   \
  99                 __ret_pu = -EFAULT;                             \
 100         __ret_pu;                                               \
 101 })
 102
 103
 104 #endif
 105
 106 /**
 107  * __get_user: - Get a simple variable from user space, with less checking.
 108  * @x:   Variable to store result.
 109  * @ptr: Source address, in user space.
 110  *
 111  * Context: User context only.  This function may sleep.
 112  *
 113  * This macro copies a single simple variable from user space to kernel
 114  * space.  It supports simple types like char and int, but not larger
 115  * data types like structures or arrays.
 116  *
 117  * @ptr must have pointer-to-simple-variable type, and the result of
 118  * dereferencing @ptr must be assignable to @x without a cast.
 119  *
 120  * Caller must check the pointer with access_ok() before calling this
 121  * function.
 122  *
 123  * Returns zero on success, or -EFAULT on error.
 124  * On error, the variable @x is set to zero.
 125  */
 126 #define __get_user(x, ptr)                              \
 127         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 128
 129
 130 /**
 131  * __put_user: - Write a simple value into user space, with less checking.
 132  * @x:   Value to copy to user space.
 133  * @ptr: Destination address, in user space.
 134  *
 135  * Context: User context only.  This function may sleep.
 136  *
 137  * This macro copies a single simple value from kernel space to user
 138  * space.  It supports simple types like char and int, but not larger
 139  * data types like structures or arrays.
 140  *
 141  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 142  * to the result of dereferencing @ptr.
 143  *
 144  * Caller must check the pointer with access_ok() before calling this
 145  * function.
 146  *
 147  * Returns zero on success, or -EFAULT on error.
 148  */
 149 #define __put_user(x, ptr)                                              \
 150         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 151
 152 #define __put_user_nocheck(x, ptr, size)                        \
 153 ({                                                              \
 154         long __pu_err;                                          \
 155         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 156         __pu_err;                                               \
 157 })
 158
 159
 160 #define __put_user_u64(x, addr, err)                                    \
 161         asm volatile("1:        movl %%eax,0(%2)\n"                     \
 162                      "2:        movl %%edx,4(%2)\n"                     \
 163                      "3:\n"                                             \
 164                      ".section .fixup,\"ax\"\n"                         \
 165                      "4:        movl %3,%0\n"                           \
 166                      "  jmp 3b\n"                                       \
 167                      ".previous\n"                                      \
 168                      _ASM_EXTABLE(1b, 4b)                               \
 169                      _ASM_EXTABLE(2b, 4b)                               \
 170                      : "=r" (err)                                       \
 171                      : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
 172
 173 #ifdef CONFIG_X86_WP_WORKS_OK
 174
 175 #define __put_user_size(x, ptr, size, retval, errret)                   \
 176 do {                                                                    \
 177         retval = 0;                                                     \
 178         __chk_user_ptr(ptr);                                            \
 179         switch (size) {                                                 \
 180         case 1:                                                         \
 181                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 182                 break;                                                  \
 183         case 2:                                                         \
 184                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 185                 break;                                                  \
 186         case 4:                                                         \
 187                 __put_user_asm(x, ptr, retval, "l", "",  "ir", errret); \
 188                 break;                                                  \
 189         case 8:                                                         \
 190                 __put_user_u64((__typeof__(*ptr))(x), ptr, retval);     \
 191                 break;                                                  \
 192         default:                                                        \
 193                 __put_user_bad();                                       \
 194         }                                                               \
 195 } while (0)
 196
 197 #else
 198
 199 #define __put_user_size(x, ptr, size, retval, errret)                   \
 200 do {                                                                    \
 201         __typeof__(*(ptr))__pus_tmp = x;                                \
 202         retval = 0;                                                     \
 203                                                                         \
 204         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
 205                 retval = errret;                                        \
 206 } while (0)
 207
 208 #endif
 209 struct __large_struct { unsigned long buf[100]; };
 210 #define __m(x) (*(struct __large_struct __user *)(x))
 211
 212 /*
 213  * Tell gcc we read from memory instead of writing: this is because
 214  * we do not write to any memory gcc knows about, so there are no
 215  * aliasing issues.
 216  */
 217 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 218         asm volatile("1:        mov"itype" %"rtype"1,%2\n"              \
 219                      "2:\n"                                             \
 220                      ".section .fixup,\"ax\"\n"                         \
 221                      "3:        movl %3,%0\n"                           \
 222                      "  jmp 2b\n"                                       \
 223                      ".previous\n"                                      \
 224                      _ASM_EXTABLE(1b, 3b)                               \
 225                      : "=r"(err)                                        \
 226                      : ltype (x), "m" (__m(addr)), "i" (errret), "0" (err))
 227
 228
 229 #define __get_user_nocheck(x, ptr, size)                                \
 230 ({                                                                      \
 231         long __gu_err;                                                  \
 232         unsigned long __gu_val;                                         \
 233         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 234         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 235         __gu_err;                                                       \
 236 })
 237
 238 #define __get_user_size(x, ptr, size, retval, errret)                   \
 239 do {                                                                    \
 240         retval = 0;                                                     \
 241         __chk_user_ptr(ptr);                                            \
 242         switch (size) {                                                 \
 243         case 1:                                                         \
 244                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 245                 break;                                                  \
 246         case 2:                                                         \
 247                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 248                 break;                                                  \
 249         case 4:                                                         \
 250                 __get_user_asm(x, ptr, retval, "l", "", "=r", errret);  \
 251                 break;                                                  \
 252         default:                                                        \
 253                 (x) = __get_user_bad();                                 \
 254         }                                                               \
 255 } while (0)
 256
 257 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 258         asm volatile("1:        mov"itype" %2,%"rtype"1\n"              \
 259                      "2:\n"                                             \
 260                      ".section .fixup,\"ax\"\n"                         \
 261                      "3:        movl %3,%0\n"                           \
 262                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 263                      "  jmp 2b\n"                                       \
 264                      ".previous\n"                                      \
 265                      _ASM_EXTABLE(1b, 3b)                               \
 266                      : "=r" (err), ltype (x)                            \
 267                      : "m" (__m(addr)), "i" (errret), "0" (err))
 268
 269
 270 unsigned long __must_check __copy_to_user_ll
 271                 (void __user *to, const void *from, unsigned long n);
 272 unsigned long __must_check __copy_from_user_ll
 273                 (void *to, const void __user *from, unsigned long n);
 274 unsigned long __must_check __copy_from_user_ll_nozero
 275                 (void *to, const void __user *from, unsigned long n);
 276 unsigned long __must_check __copy_from_user_ll_nocache
 277                 (void *to, const void __user *from, unsigned long n);
 278 unsigned long __must_check __copy_from_user_ll_nocache_nozero
 279                 (void *to, const void __user *from, unsigned long n);
 280
 281 /**
 282  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
 283  * @to:   Destination address, in user space.
 284  * @from: Source address, in kernel space.
 285  * @n:    Number of bytes to copy.
 286  *
 287  * Context: User context only.
 288  *
 289  * Copy data from kernel space to user space.  Caller must check
 290  * the specified block with access_ok() before calling this function.
 291  * The caller should also make sure he pins the user space address
 292  * so that the we don't result in page fault and sleep.
 293  *
 294  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 295  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 296  * If a store crosses a page boundary and gets a fault, the x86 will not write
 297  * anything, so this is accurate.
 298  */
 299
 300 static __always_inline unsigned long __must_check
 301 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 302 {
 303         if (__builtin_constant_p(n)) {
 304                 unsigned long ret;
 305
 306                 switch (n) {
 307                 case 1:
 308                         __put_user_size(*(u8 *)from, (u8 __user *)to,
 309                                         1, ret, 1);
 310                         return ret;
 311                 case 2:
 312                         __put_user_size(*(u16 *)from, (u16 __user *)to,
 313                                         2, ret, 2);
 314                         return ret;
 315                 case 4:
 316                         __put_user_size(*(u32 *)from, (u32 __user *)to,
 317                                         4, ret, 4);
 318                         return ret;
 319                 }
 320         }
 321         return __copy_to_user_ll(to, from, n);
 322 }
 323
 324 /**
 325  * __copy_to_user: - Copy a block of data into user space, with less checking.
 326  * @to:   Destination address, in user space.
 327  * @from: Source address, in kernel space.
 328  * @n:    Number of bytes to copy.
 329  *
 330  * Context: User context only.  This function may sleep.
 331  *
 332  * Copy data from kernel space to user space.  Caller must check
 333  * the specified block with access_ok() before calling this function.
 334  *
 335  * Returns number of bytes that could not be copied.
 336  * On success, this will be zero.
 337  */
 338 static __always_inline unsigned long __must_check
 339 __copy_to_user(void __user *to, const void *from, unsigned long n)
 340 {
 341        might_sleep();
 342        return __copy_to_user_inatomic(to, from, n);
 343 }
 344
 345 static __always_inline unsigned long
 346 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 347 {
 348         /* Avoid zeroing the tail if the copy fails..
 349          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
 350          * but as the zeroing behaviour is only significant when n is not
 351          * constant, that shouldn't be a problem.
 352          */
 353         if (__builtin_constant_p(n)) {
 354                 unsigned long ret;
 355
 356                 switch (n) {
 357                 case 1:
 358                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 359                         return ret;
 360                 case 2:
 361                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 362                         return ret;
 363                 case 4:
 364                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 365                         return ret;
 366                 }
 367         }
 368         return __copy_from_user_ll_nozero(to, from, n);
 369 }
 370
 371 /**
 372  * __copy_from_user: - Copy a block of data from user space, with less checking.
 373  * @to:   Destination address, in kernel space.
 374  * @from: Source address, in user space.
 375  * @n:    Number of bytes to copy.
 376  *
 377  * Context: User context only.  This function may sleep.
 378  *
 379  * Copy data from user space to kernel space.  Caller must check
 380  * the specified block with access_ok() before calling this function.
 381  *
 382  * Returns number of bytes that could not be copied.
 383  * On success, this will be zero.
 384  *
 385  * If some data could not be copied, this function will pad the copied
 386  * data to the requested size using zero bytes.
 387  *
 388  * An alternate version - __copy_from_user_inatomic() - may be called from
 389  * atomic context and will fail rather than sleep.  In this case the
 390  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 391  * for explanation of why this is needed.
 392  */
 393 static __always_inline unsigned long
 394 __copy_from_user(void *to, const void __user *from, unsigned long n)
 395 {
 396         might_sleep();
 397         if (__builtin_constant_p(n)) {
 398                 unsigned long ret;
 399
 400                 switch (n) {
 401                 case 1:
 402                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 403                         return ret;
 404                 case 2:
 405                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 406                         return ret;
 407                 case 4:
 408                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 409                         return ret;
 410                 }
 411         }
 412         return __copy_from_user_ll(to, from, n);
 413 }
 414
 415 #define ARCH_HAS_NOCACHE_UACCESS
 416
 417 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 418                                 const void __user *from, unsigned long n)
 419 {
 420         might_sleep();
 421         if (__builtin_constant_p(n)) {
 422                 unsigned long ret;
 423
 424                 switch (n) {
 425                 case 1:
 426                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 427                         return ret;
 428                 case 2:
 429                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 430                         return ret;
 431                 case 4:
 432                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 433                         return ret;
 434                 }
 435         }
 436         return __copy_from_user_ll_nocache(to, from, n);
 437 }
 438
 439 static __always_inline unsigned long
 440 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 441                                   unsigned long n)
 442 {
 443        return __copy_from_user_ll_nocache_nozero(to, from, n);
 444 }
 445
 446 unsigned long __must_check copy_to_user(void __user *to,
 447                                         const void *from, unsigned long n);
 448 unsigned long __must_check copy_from_user(void *to,
 449                                           const void __user *from,
 450                                           unsigned long n);
 451 long __must_check strncpy_from_user(char *dst, const char __user *src,
 452                                     long count);
 453 long __must_check __strncpy_from_user(char *dst,
 454                                       const char __user *src, long count);
 455
 456 /**
 457  * strlen_user: - Get the size of a string in user space.
 458  * @str: The string to measure.
 459  *
 460  * Context: User context only.  This function may sleep.
 461  *
 462  * Get the size of a NUL-terminated string in user space.
 463  *
 464  * Returns the size of the string INCLUDING the terminating NUL.
 465  * On exception, returns 0.
 466  *
 467  * If there is a limit on the length of a valid string, you may wish to
 468  * consider using strnlen_user() instead.
 469  */
 470 #define strlen_user(str) strnlen_user(str, LONG_MAX)
 471
 472 long strnlen_user(const char __user *str, long n);
 473 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 474 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 475
 476 #endif /* __i386_UACCESS_H */