Pileus Git - ~andy/linux/blob - arch/x86/include/asm/uaccess.h

   1 #ifndef _ASM_X86_UACCESS_H
   2 #define _ASM_X86_UACCESS_H
   3 /*
   4  * User space memory access functions
   5  */
   6 #include <linux/errno.h>
   7 #include <linux/compiler.h>
   8 #include <linux/thread_info.h>
   9 #include <linux/string.h>
  10 #include <asm/asm.h>
  11 #include <asm/page.h>
  12 #include <asm/smap.h>
  13
  14 #define VERIFY_READ 0
  15 #define VERIFY_WRITE 1
  16
  17 /*
  18  * The fs value determines whether argument validity checking should be
  19  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  20  * get_fs() == KERNEL_DS, checking is bypassed.
  21  *
  22  * For historical reasons, these macros are grossly misnamed.
  23  */
  24
  25 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  26
  27 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  28 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  29
  30 #define get_ds()        (KERNEL_DS)
  31 #define get_fs()        (current_thread_info()->addr_limit)
  32 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  33
  34 #define segment_eq(a, b)        ((a).seg == (b).seg)
  35
  36 #define user_addr_max() (current_thread_info()->addr_limit.seg)
  37 #define __addr_ok(addr)         \
  38         ((unsigned long __force)(addr) < user_addr_max())
  39
  40 /*
  41  * Test whether a block of memory is a valid user space address.
  42  * Returns 0 if the range is valid, nonzero otherwise.
  43  *
  44  * This is equivalent to the following test:
  45  * (u33)addr + (u33)size > (u33)current->addr_limit.seg (u65 for x86_64)
  46  *
  47  * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
  48  */
  49
  50 #define __range_not_ok(addr, size, limit)                               \
  51 ({                                                                      \
  52         unsigned long flag, roksum;                                     \
  53         __chk_user_ptr(addr);                                           \
  54         asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"             \
  55             : "=&r" (flag), "=r" (roksum)                               \
  56             : "1" (addr), "g" ((long)(size)),                           \
  57               "rm" (limit));                                            \
  58         flag;                                                           \
  59 })
  60
  61 /**
  62  * access_ok: - Checks if a user space pointer is valid
  63  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  64  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  65  *        to write to a block, it is always safe to read from it.
  66  * @addr: User space pointer to start of block to check
  67  * @size: Size of block to check
  68  *
  69  * Context: User context only.  This function may sleep.
  70  *
  71  * Checks if a pointer to a block of memory in user space is valid.
  72  *
  73  * Returns true (nonzero) if the memory block may be valid, false (zero)
  74  * if it is definitely invalid.
  75  *
  76  * Note that, depending on architecture, this function probably just
  77  * checks that the pointer is in the user space range - after calling
  78  * this function, memory access functions may still return -EFAULT.
  79  */
  80 #define access_ok(type, addr, size) \
  81         (likely(__range_not_ok(addr, size, user_addr_max()) == 0))
  82
  83 /*
  84  * The exception table consists of pairs of addresses relative to the
  85  * exception table enty itself: the first is the address of an
  86  * instruction that is allowed to fault, and the second is the address
  87  * at which the program should continue.  No registers are modified,
  88  * so it is entirely up to the continuation code to figure out what to
  89  * do.
  90  *
  91  * All the routines below use bits of fixup code that are out of line
  92  * with the main instruction path.  This means when everything is well,
  93  * we don't even have to jump over them.  Further, they do not intrude
  94  * on our cache or tlb entries.
  95  */
  96
  97 struct exception_table_entry {
  98         int insn, fixup;
  99 };
 100 /* This is not the generic standard exception_table_entry format */
 101 #define ARCH_HAS_SORT_EXTABLE
 102 #define ARCH_HAS_SEARCH_EXTABLE
 103
 104 extern int fixup_exception(struct pt_regs *regs);
 105 extern int early_fixup_exception(unsigned long *ip);
 106
 107 /*
 108  * These are the main single-value transfer routines.  They automatically
 109  * use the right size if we just have the right pointer type.
 110  *
 111  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 112  * and yet we don't want to do any pointers, because that is too much
 113  * of a performance impact. Thus we have a few rather ugly macros here,
 114  * and hide all the ugliness from the user.
 115  *
 116  * The "__xxx" versions of the user access functions are versions that
 117  * do not verify the address space, that must have been done previously
 118  * with a separate "access_ok()" call (this is used when we do multiple
 119  * accesses to the same area of user memory).
 120  */
 121
 122 extern int __get_user_1(void);
 123 extern int __get_user_2(void);
 124 extern int __get_user_4(void);
 125 extern int __get_user_8(void);
 126 extern int __get_user_bad(void);
 127
 128 #define __get_user_x(size, ret, x, ptr)               \
 129         asm volatile("call __get_user_" #size         \
 130                      : "=a" (ret), "=d" (x)           \
 131                      : "0" (ptr))                     \
 132
 133 /* Careful: we have to cast the result to the type of the pointer
 134  * for sign reasons */
 135
 136 /**
 137  * get_user: - Get a simple variable from user space.
 138  * @x:   Variable to store result.
 139  * @ptr: Source address, in user space.
 140  *
 141  * Context: User context only.  This function may sleep.
 142  *
 143  * This macro copies a single simple variable from user space to kernel
 144  * space.  It supports simple types like char and int, but not larger
 145  * data types like structures or arrays.
 146  *
 147  * @ptr must have pointer-to-simple-variable type, and the result of
 148  * dereferencing @ptr must be assignable to @x without a cast.
 149  *
 150  * Returns zero on success, or -EFAULT on error.
 151  * On error, the variable @x is set to zero.
 152  */
 153 #ifdef CONFIG_X86_32
 154 #define __get_user_8(__ret_gu, __val_gu, ptr)                           \
 155                 __get_user_x(X, __ret_gu, __val_gu, ptr)
 156 #else
 157 #define __get_user_8(__ret_gu, __val_gu, ptr)                           \
 158                 __get_user_x(8, __ret_gu, __val_gu, ptr)
 159 #endif
 160
 161 #define get_user(x, ptr)                                                \
 162 ({                                                                      \
 163         int __ret_gu;                                                   \
 164         unsigned long __val_gu;                                         \
 165         __chk_user_ptr(ptr);                                            \
 166         might_fault();                                                  \
 167         switch (sizeof(*(ptr))) {                                       \
 168         case 1:                                                         \
 169                 __get_user_x(1, __ret_gu, __val_gu, ptr);               \
 170                 break;                                                  \
 171         case 2:                                                         \
 172                 __get_user_x(2, __ret_gu, __val_gu, ptr);               \
 173                 break;                                                  \
 174         case 4:                                                         \
 175                 __get_user_x(4, __ret_gu, __val_gu, ptr);               \
 176                 break;                                                  \
 177         case 8:                                                         \
 178                 __get_user_8(__ret_gu, __val_gu, ptr);                  \
 179                 break;                                                  \
 180         default:                                                        \
 181                 __get_user_x(X, __ret_gu, __val_gu, ptr);               \
 182                 break;                                                  \
 183         }                                                               \
 184         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 185         __ret_gu;                                                       \
 186 })
 187
 188 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 189         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 190                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 191
 192
 193
 194 #ifdef CONFIG_X86_32
 195 #define __put_user_asm_u64(x, addr, err, errret)                        \
 196         asm volatile(ASM_STAC "\n"                                      \
 197                      "1:        movl %%eax,0(%2)\n"                     \
 198                      "2:        movl %%edx,4(%2)\n"                     \
 199                      "3: " ASM_CLAC "\n"                                \
 200                      ".section .fixup,\"ax\"\n"                         \
 201                      "4:        movl %3,%0\n"                           \
 202                      "  jmp 3b\n"                                       \
 203                      ".previous\n"                                      \
 204                      _ASM_EXTABLE(1b, 4b)                               \
 205                      _ASM_EXTABLE(2b, 4b)                               \
 206                      : "=r" (err)                                       \
 207                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 208
 209 #define __put_user_asm_ex_u64(x, addr)                                  \
 210         asm volatile(ASM_STAC "\n"                                      \
 211                      "1:        movl %%eax,0(%1)\n"                     \
 212                      "2:        movl %%edx,4(%1)\n"                     \
 213                      "3: " ASM_CLAC "\n"                                \
 214                      _ASM_EXTABLE_EX(1b, 2b)                            \
 215                      _ASM_EXTABLE_EX(2b, 3b)                            \
 216                      : : "A" (x), "r" (addr))
 217
 218 #define __put_user_x8(x, ptr, __ret_pu)                         \
 219         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 220                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 221 #else
 222 #define __put_user_asm_u64(x, ptr, retval, errret) \
 223         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 224 #define __put_user_asm_ex_u64(x, addr)  \
 225         __put_user_asm_ex(x, addr, "q", "", "er")
 226 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 227 #endif
 228
 229 extern void __put_user_bad(void);
 230
 231 /*
 232  * Strange magic calling convention: pointer in %ecx,
 233  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 234  */
 235 extern void __put_user_1(void);
 236 extern void __put_user_2(void);
 237 extern void __put_user_4(void);
 238 extern void __put_user_8(void);
 239
 240 #ifdef CONFIG_X86_WP_WORKS_OK
 241
 242 /**
 243  * put_user: - Write a simple value into user space.
 244  * @x:   Value to copy to user space.
 245  * @ptr: Destination address, in user space.
 246  *
 247  * Context: User context only.  This function may sleep.
 248  *
 249  * This macro copies a single simple value from kernel space to user
 250  * space.  It supports simple types like char and int, but not larger
 251  * data types like structures or arrays.
 252  *
 253  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 254  * to the result of dereferencing @ptr.
 255  *
 256  * Returns zero on success, or -EFAULT on error.
 257  */
 258 #define put_user(x, ptr)                                        \
 259 ({                                                              \
 260         int __ret_pu;                                           \
 261         __typeof__(*(ptr)) __pu_val;                            \
 262         __chk_user_ptr(ptr);                                    \
 263         might_fault();                                          \
 264         __pu_val = x;                                           \
 265         switch (sizeof(*(ptr))) {                               \
 266         case 1:                                                 \
 267                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 268                 break;                                          \
 269         case 2:                                                 \
 270                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 271                 break;                                          \
 272         case 4:                                                 \
 273                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 274                 break;                                          \
 275         case 8:                                                 \
 276                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 277                 break;                                          \
 278         default:                                                \
 279                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 280                 break;                                          \
 281         }                                                       \
 282         __ret_pu;                                               \
 283 })
 284
 285 #define __put_user_size(x, ptr, size, retval, errret)                   \
 286 do {                                                                    \
 287         retval = 0;                                                     \
 288         __chk_user_ptr(ptr);                                            \
 289         switch (size) {                                                 \
 290         case 1:                                                         \
 291                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 292                 break;                                                  \
 293         case 2:                                                         \
 294                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 295                 break;                                                  \
 296         case 4:                                                         \
 297                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 298                 break;                                                  \
 299         case 8:                                                         \
 300                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 301                                    errret);                             \
 302                 break;                                                  \
 303         default:                                                        \
 304                 __put_user_bad();                                       \
 305         }                                                               \
 306 } while (0)
 307
 308 #define __put_user_size_ex(x, ptr, size)                                \
 309 do {                                                                    \
 310         __chk_user_ptr(ptr);                                            \
 311         switch (size) {                                                 \
 312         case 1:                                                         \
 313                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 314                 break;                                                  \
 315         case 2:                                                         \
 316                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 317                 break;                                                  \
 318         case 4:                                                         \
 319                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 320                 break;                                                  \
 321         case 8:                                                         \
 322                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 323                 break;                                                  \
 324         default:                                                        \
 325                 __put_user_bad();                                       \
 326         }                                                               \
 327 } while (0)
 328
 329 #else
 330
 331 #define __put_user_size(x, ptr, size, retval, errret)                   \
 332 do {                                                                    \
 333         __typeof__(*(ptr))__pus_tmp = x;                                \
 334         retval = 0;                                                     \
 335                                                                         \
 336         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
 337                 retval = errret;                                        \
 338 } while (0)
 339
 340 #define put_user(x, ptr)                                        \
 341 ({                                                              \
 342         int __ret_pu;                                           \
 343         __typeof__(*(ptr))__pus_tmp = x;                        \
 344         __ret_pu = 0;                                           \
 345         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
 346                                        sizeof(*(ptr))) != 0))   \
 347                 __ret_pu = -EFAULT;                             \
 348         __ret_pu;                                               \
 349 })
 350 #endif
 351
 352 #ifdef CONFIG_X86_32
 353 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 354 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 355 #else
 356 #define __get_user_asm_u64(x, ptr, retval, errret) \
 357          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 358 #define __get_user_asm_ex_u64(x, ptr) \
 359          __get_user_asm_ex(x, ptr, "q", "", "=r")
 360 #endif
 361
 362 #define __get_user_size(x, ptr, size, retval, errret)                   \
 363 do {                                                                    \
 364         retval = 0;                                                     \
 365         __chk_user_ptr(ptr);                                            \
 366         switch (size) {                                                 \
 367         case 1:                                                         \
 368                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 369                 break;                                                  \
 370         case 2:                                                         \
 371                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 372                 break;                                                  \
 373         case 4:                                                         \
 374                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 375                 break;                                                  \
 376         case 8:                                                         \
 377                 __get_user_asm_u64(x, ptr, retval, errret);             \
 378                 break;                                                  \
 379         default:                                                        \
 380                 (x) = __get_user_bad();                                 \
 381         }                                                               \
 382 } while (0)
 383
 384 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 385         asm volatile(ASM_STAC "\n"                                      \
 386                      "1:        mov"itype" %2,%"rtype"1\n"              \
 387                      "2: " ASM_CLAC "\n"                                \
 388                      ".section .fixup,\"ax\"\n"                         \
 389                      "3:        mov %3,%0\n"                            \
 390                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 391                      "  jmp 2b\n"                                       \
 392                      ".previous\n"                                      \
 393                      _ASM_EXTABLE(1b, 3b)                               \
 394                      : "=r" (err), ltype(x)                             \
 395                      : "m" (__m(addr)), "i" (errret), "0" (err))
 396
 397 #define __get_user_size_ex(x, ptr, size)                                \
 398 do {                                                                    \
 399         __chk_user_ptr(ptr);                                            \
 400         switch (size) {                                                 \
 401         case 1:                                                         \
 402                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 403                 break;                                                  \
 404         case 2:                                                         \
 405                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 406                 break;                                                  \
 407         case 4:                                                         \
 408                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 409                 break;                                                  \
 410         case 8:                                                         \
 411                 __get_user_asm_ex_u64(x, ptr);                          \
 412                 break;                                                  \
 413         default:                                                        \
 414                 (x) = __get_user_bad();                                 \
 415         }                                                               \
 416 } while (0)
 417
 418 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 419         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 420                      "2:\n"                                             \
 421                      _ASM_EXTABLE_EX(1b, 2b)                            \
 422                      : ltype(x) : "m" (__m(addr)))
 423
 424 #define __put_user_nocheck(x, ptr, size)                        \
 425 ({                                                              \
 426         int __pu_err;                                           \
 427         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 428         __pu_err;                                               \
 429 })
 430
 431 #define __get_user_nocheck(x, ptr, size)                                \
 432 ({                                                                      \
 433         int __gu_err;                                                   \
 434         unsigned long __gu_val;                                         \
 435         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 436         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 437         __gu_err;                                                       \
 438 })
 439
 440 /* FIXME: this hack is definitely wrong -AK */
 441 struct __large_struct { unsigned long buf[100]; };
 442 #define __m(x) (*(struct __large_struct __user *)(x))
 443
 444 /*
 445  * Tell gcc we read from memory instead of writing: this is because
 446  * we do not write to any memory gcc knows about, so there are no
 447  * aliasing issues.
 448  */
 449 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 450         asm volatile(ASM_STAC "\n"                                      \
 451                      "1:        mov"itype" %"rtype"1,%2\n"              \
 452                      "2: " ASM_CLAC "\n"                                \
 453                      ".section .fixup,\"ax\"\n"                         \
 454                      "3:        mov %3,%0\n"                            \
 455                      "  jmp 2b\n"                                       \
 456                      ".previous\n"                                      \
 457                      _ASM_EXTABLE(1b, 3b)                               \
 458                      : "=r"(err)                                        \
 459                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 460
 461 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 462         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 463                      "2:\n"                                             \
 464                      _ASM_EXTABLE_EX(1b, 2b)                            \
 465                      : : ltype(x), "m" (__m(addr)))
 466
 467 /*
 468  * uaccess_try and catch
 469  */
 470 #define uaccess_try     do {                                            \
 471         current_thread_info()->uaccess_err = 0;                         \
 472         stac();                                                         \
 473         barrier();
 474
 475 #define uaccess_catch(err)                                              \
 476         clac();                                                         \
 477         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 478 } while (0)
 479
 480 /**
 481  * __get_user: - Get a simple variable from user space, with less checking.
 482  * @x:   Variable to store result.
 483  * @ptr: Source address, in user space.
 484  *
 485  * Context: User context only.  This function may sleep.
 486  *
 487  * This macro copies a single simple variable from user space to kernel
 488  * space.  It supports simple types like char and int, but not larger
 489  * data types like structures or arrays.
 490  *
 491  * @ptr must have pointer-to-simple-variable type, and the result of
 492  * dereferencing @ptr must be assignable to @x without a cast.
 493  *
 494  * Caller must check the pointer with access_ok() before calling this
 495  * function.
 496  *
 497  * Returns zero on success, or -EFAULT on error.
 498  * On error, the variable @x is set to zero.
 499  */
 500
 501 #define __get_user(x, ptr)                                              \
 502         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 503
 504 /**
 505  * __put_user: - Write a simple value into user space, with less checking.
 506  * @x:   Value to copy to user space.
 507  * @ptr: Destination address, in user space.
 508  *
 509  * Context: User context only.  This function may sleep.
 510  *
 511  * This macro copies a single simple value from kernel space to user
 512  * space.  It supports simple types like char and int, but not larger
 513  * data types like structures or arrays.
 514  *
 515  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 516  * to the result of dereferencing @ptr.
 517  *
 518  * Caller must check the pointer with access_ok() before calling this
 519  * function.
 520  *
 521  * Returns zero on success, or -EFAULT on error.
 522  */
 523
 524 #define __put_user(x, ptr)                                              \
 525         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 526
 527 #define __get_user_unaligned __get_user
 528 #define __put_user_unaligned __put_user
 529
 530 /*
 531  * {get|put}_user_try and catch
 532  *
 533  * get_user_try {
 534  *      get_user_ex(...);
 535  * } get_user_catch(err)
 536  */
 537 #define get_user_try            uaccess_try
 538 #define get_user_catch(err)     uaccess_catch(err)
 539
 540 #define get_user_ex(x, ptr)     do {                                    \
 541         unsigned long __gue_val;                                        \
 542         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 543         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 544 } while (0)
 545
 546 #ifdef CONFIG_X86_WP_WORKS_OK
 547
 548 #define put_user_try            uaccess_try
 549 #define put_user_catch(err)     uaccess_catch(err)
 550
 551 #define put_user_ex(x, ptr)                                             \
 552         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 553
 554 #else /* !CONFIG_X86_WP_WORKS_OK */
 555
 556 #define put_user_try            do {            \
 557         int __uaccess_err = 0;
 558
 559 #define put_user_catch(err)                     \
 560         (err) |= __uaccess_err;                 \
 561 } while (0)
 562
 563 #define put_user_ex(x, ptr)     do {            \
 564         __uaccess_err |= __put_user(x, ptr);    \
 565 } while (0)
 566
 567 #endif /* CONFIG_X86_WP_WORKS_OK */
 568
 569 extern unsigned long
 570 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 571 extern __must_check long
 572 strncpy_from_user(char *dst, const char __user *src, long count);
 573
 574 extern __must_check long strlen_user(const char __user *str);
 575 extern __must_check long strnlen_user(const char __user *str, long n);
 576
 577 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 578 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 579
 580 /*
 581  * movsl can be slow when source and dest are not both 8-byte aligned
 582  */
 583 #ifdef CONFIG_X86_INTEL_USERCOPY
 584 extern struct movsl_mask {
 585         int mask;
 586 } ____cacheline_aligned_in_smp movsl_mask;
 587 #endif
 588
 589 #define ARCH_HAS_NOCACHE_UACCESS 1
 590
 591 #ifdef CONFIG_X86_32
 592 # include <asm/uaccess_32.h>
 593 #else
 594 # include <asm/uaccess_64.h>
 595 #endif
 596
 597 #endif /* _ASM_X86_UACCESS_H */
 598