arch/i386/lib/usercopy.c

   1 /*
   2  * User address space access functions.
   3  * The non inlined parts of asm-i386/uaccess.h are here.
   4  *
   5  * Copyright 1997 Andi Kleen <ak@muc.de>
   6  * Copyright 1997 Linus Torvalds
   7  */
   8 #include <linux/config.h>
   9 #include <linux/mm.h>
  10 #include <linux/highmem.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/module.h>
  13 #include <asm/uaccess.h>
  14 #include <asm/mmx.h>
  15
  16 static inline int __movsl_is_ok(unsigned long a1, unsigned long a2, unsigned long n)
  17 {
  18 #ifdef CONFIG_X86_INTEL_USERCOPY
  19         if (n >= 64 && ((a1 ^ a2) & movsl_mask.mask))
  20                 return 0;
  21 #endif
  22         return 1;
  23 }
  24 #define movsl_is_ok(a1,a2,n) \
  25         __movsl_is_ok((unsigned long)(a1),(unsigned long)(a2),(n))
  26
  27 /*
  28  * Copy a null terminated string from userspace.
  29  */
  30
  31 #define __do_strncpy_from_user(dst,src,count,res)                          \
  32 do {                                                                       \
  33         int __d0, __d1, __d2;                                              \
  34         might_sleep();                                                     \
  35         __asm__ __volatile__(                                              \
  36                 "       testl %1,%1\n"                                     \
  37                 "       jz 2f\n"                                           \
  38                 "0:     lodsb\n"                                           \
  39                 "       stosb\n"                                           \
  40                 "       testb %%al,%%al\n"                                 \
  41                 "       jz 1f\n"                                           \
  42                 "       decl %1\n"                                         \
  43                 "       jnz 0b\n"                                          \
  44                 "1:     subl %1,%0\n"                                      \
  45                 "2:\n"                                                     \
  46                 ".section .fixup,\"ax\"\n"                                 \
  47                 "3:     movl %5,%0\n"                                      \
  48                 "       jmp 2b\n"                                          \
  49                 ".previous\n"                                              \
  50                 ".section __ex_table,\"a\"\n"                              \
  51                 "       .align 4\n"                                        \
  52                 "       .long 0b,3b\n"                                     \
  53                 ".previous"                                                \
  54                 : "=d"(res), "=c"(count), "=&a" (__d0), "=&S" (__d1),      \
  55                   "=&D" (__d2)                                             \
  56                 : "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
  57                 : "memory");                                               \
  58 } while (0)
  59
  60 /**
  61  * __strncpy_from_user: - Copy a NUL terminated string from userspace, with less checking.
  62  * @dst:   Destination address, in kernel space.  This buffer must be at
  63  *         least @count bytes long.
  64  * @src:   Source address, in user space.
  65  * @count: Maximum number of bytes to copy, including the trailing NUL.
  66  *
  67  * Copies a NUL-terminated string from userspace to kernel space.
  68  * Caller must check the specified block with access_ok() before calling
  69  * this function.
  70  *
  71  * On success, returns the length of the string (not including the trailing
  72  * NUL).
  73  *
  74  * If access to userspace fails, returns -EFAULT (some data may have been
  75  * copied).
  76  *
  77  * If @count is smaller than the length of the string, copies @count bytes
  78  * and returns @count.
  79  */
  80 long
  81 __strncpy_from_user(char *dst, const char __user *src, long count)
  82 {
  83         long res;
  84         __do_strncpy_from_user(dst, src, count, res);
  85         return res;
  86 }
  87 EXPORT_SYMBOL(__strncpy_from_user);
  88
  89 /**
  90  * strncpy_from_user: - Copy a NUL terminated string from userspace.
  91  * @dst:   Destination address, in kernel space.  This buffer must be at
  92  *         least @count bytes long.
  93  * @src:   Source address, in user space.
  94  * @count: Maximum number of bytes to copy, including the trailing NUL.
  95  *
  96  * Copies a NUL-terminated string from userspace to kernel space.
  97  *
  98  * On success, returns the length of the string (not including the trailing
  99  * NUL).
 100  *
 101  * If access to userspace fails, returns -EFAULT (some data may have been
 102  * copied).
 103  *
 104  * If @count is smaller than the length of the string, copies @count bytes
 105  * and returns @count.
 106  */
 107 long
 108 strncpy_from_user(char *dst, const char __user *src, long count)
 109 {
 110         long res = -EFAULT;
 111         if (access_ok(VERIFY_READ, src, 1))
 112                 __do_strncpy_from_user(dst, src, count, res);
 113         return res;
 114 }
 115 EXPORT_SYMBOL(strncpy_from_user);
 116
 117 /*
 118  * Zero Userspace
 119  */
 120
 121 #define __do_clear_user(addr,size)                                      \
 122 do {                                                                    \
 123         int __d0;                                                       \
 124         might_sleep();                                                  \
 125         __asm__ __volatile__(                                           \
 126                 "0:     rep; stosl\n"                                   \
 127                 "       movl %2,%0\n"                                   \
 128                 "1:     rep; stosb\n"                                   \
 129                 "2:\n"                                                  \
 130                 ".section .fixup,\"ax\"\n"                              \
 131                 "3:     lea 0(%2,%0,4),%0\n"                            \
 132                 "       jmp 2b\n"                                       \
 133                 ".previous\n"                                           \
 134                 ".section __ex_table,\"a\"\n"                           \
 135                 "       .align 4\n"                                     \
 136                 "       .long 0b,3b\n"                                  \
 137                 "       .long 1b,2b\n"                                  \
 138                 ".previous"                                             \
 139                 : "=&c"(size), "=&D" (__d0)                             \
 140                 : "r"(size & 3), "0"(size / 4), "1"(addr), "a"(0));     \
 141 } while (0)
 142
 143 /**
 144  * clear_user: - Zero a block of memory in user space.
 145  * @to:   Destination address, in user space.
 146  * @n:    Number of bytes to zero.
 147  *
 148  * Zero a block of memory in user space.
 149  *
 150  * Returns number of bytes that could not be cleared.
 151  * On success, this will be zero.
 152  */
 153 unsigned long
 154 clear_user(void __user *to, unsigned long n)
 155 {
 156         might_sleep();
 157         if (access_ok(VERIFY_WRITE, to, n))
 158                 __do_clear_user(to, n);
 159         return n;
 160 }
 161 EXPORT_SYMBOL(clear_user);
 162
 163 /**
 164  * __clear_user: - Zero a block of memory in user space, with less checking.
 165  * @to:   Destination address, in user space.
 166  * @n:    Number of bytes to zero.
 167  *
 168  * Zero a block of memory in user space.  Caller must check
 169  * the specified block with access_ok() before calling this function.
 170  *
 171  * Returns number of bytes that could not be cleared.
 172  * On success, this will be zero.
 173  */
 174 unsigned long
 175 __clear_user(void __user *to, unsigned long n)
 176 {
 177         __do_clear_user(to, n);
 178         return n;
 179 }
 180 EXPORT_SYMBOL(__clear_user);
 181
 182 /**
 183  * strlen_user: - Get the size of a string in user space.
 184  * @s: The string to measure.
 185  * @n: The maximum valid length
 186  *
 187  * Get the size of a NUL-terminated string in user space.
 188  *
 189  * Returns the size of the string INCLUDING the terminating NUL.
 190  * On exception, returns 0.
 191  * If the string is too long, returns a value greater than @n.
 192  */
 193 long strnlen_user(const char __user *s, long n)
 194 {
 195         unsigned long mask = -__addr_ok(s);
 196         unsigned long res, tmp;
 197
 198         might_sleep();
 199
 200         __asm__ __volatile__(
 201                 "       testl %0, %0\n"
 202                 "       jz 3f\n"
 203                 "       andl %0,%%ecx\n"
 204                 "0:     repne; scasb\n"
 205                 "       setne %%al\n"
 206                 "       subl %%ecx,%0\n"
 207                 "       addl %0,%%eax\n"
 208                 "1:\n"
 209                 ".section .fixup,\"ax\"\n"
 210                 "2:     xorl %%eax,%%eax\n"
 211                 "       jmp 1b\n"
 212                 "3:     movb $1,%%al\n"
 213                 "       jmp 1b\n"
 214                 ".previous\n"
 215                 ".section __ex_table,\"a\"\n"
 216                 "       .align 4\n"
 217                 "       .long 0b,2b\n"
 218                 ".previous"
 219                 :"=r" (n), "=D" (s), "=a" (res), "=c" (tmp)
 220                 :"0" (n), "1" (s), "2" (0), "3" (mask)
 221                 :"cc");
 222         return res & mask;
 223 }
 224 EXPORT_SYMBOL(strnlen_user);
 225
 226 #ifdef CONFIG_X86_INTEL_USERCOPY
 227 static unsigned long
 228 __copy_user_intel(void __user *to, const void *from, unsigned long size)
 229 {
 230         int d0, d1;
 231         __asm__ __volatile__(
 232                        "       .align 2,0x90\n"
 233                        "1:     movl 32(%4), %%eax\n"
 234                        "       cmpl $67, %0\n"
 235                        "       jbe 3f\n"
 236                        "2:     movl 64(%4), %%eax\n"
 237                        "       .align 2,0x90\n"
 238                        "3:     movl 0(%4), %%eax\n"
 239                        "4:     movl 4(%4), %%edx\n"
 240                        "5:     movl %%eax, 0(%3)\n"
 241                        "6:     movl %%edx, 4(%3)\n"
 242                        "7:     movl 8(%4), %%eax\n"
 243                        "8:     movl 12(%4),%%edx\n"
 244                        "9:     movl %%eax, 8(%3)\n"
 245                        "10:    movl %%edx, 12(%3)\n"
 246                        "11:    movl 16(%4), %%eax\n"
 247                        "12:    movl 20(%4), %%edx\n"
 248                        "13:    movl %%eax, 16(%3)\n"
 249                        "14:    movl %%edx, 20(%3)\n"
 250                        "15:    movl 24(%4), %%eax\n"
 251                        "16:    movl 28(%4), %%edx\n"
 252                        "17:    movl %%eax, 24(%3)\n"
 253                        "18:    movl %%edx, 28(%3)\n"
 254                        "19:    movl 32(%4), %%eax\n"
 255                        "20:    movl 36(%4), %%edx\n"
 256                        "21:    movl %%eax, 32(%3)\n"
 257                        "22:    movl %%edx, 36(%3)\n"
 258                        "23:    movl 40(%4), %%eax\n"
 259                        "24:    movl 44(%4), %%edx\n"
 260                        "25:    movl %%eax, 40(%3)\n"
 261                        "26:    movl %%edx, 44(%3)\n"
 262                        "27:    movl 48(%4), %%eax\n"
 263                        "28:    movl 52(%4), %%edx\n"
 264                        "29:    movl %%eax, 48(%3)\n"
 265                        "30:    movl %%edx, 52(%3)\n"
 266                        "31:    movl 56(%4), %%eax\n"
 267                        "32:    movl 60(%4), %%edx\n"
 268                        "33:    movl %%eax, 56(%3)\n"
 269                        "34:    movl %%edx, 60(%3)\n"
 270                        "       addl $-64, %0\n"
 271                        "       addl $64, %4\n"
 272                        "       addl $64, %3\n"
 273                        "       cmpl $63, %0\n"
 274                        "       ja  1b\n"
 275                        "35:    movl  %0, %%eax\n"
 276                        "       shrl  $2, %0\n"
 277                        "       andl  $3, %%eax\n"
 278                        "       cld\n"
 279                        "99:    rep; movsl\n"
 280                        "36:    movl %%eax, %0\n"
 281                        "37:    rep; movsb\n"
 282                        "100:\n"
 283                        ".section .fixup,\"ax\"\n"
 284                        "101:   lea 0(%%eax,%0,4),%0\n"
 285                        "       jmp 100b\n"
 286                        ".previous\n"
 287                        ".section __ex_table,\"a\"\n"
 288                        "       .align 4\n"
 289                        "       .long 1b,100b\n"
 290                        "       .long 2b,100b\n"
 291                        "       .long 3b,100b\n"
 292                        "       .long 4b,100b\n"
 293                        "       .long 5b,100b\n"
 294                        "       .long 6b,100b\n"
 295                        "       .long 7b,100b\n"
 296                        "       .long 8b,100b\n"
 297                        "       .long 9b,100b\n"
 298                        "       .long 10b,100b\n"
 299                        "       .long 11b,100b\n"
 300                        "       .long 12b,100b\n"
 301                        "       .long 13b,100b\n"
 302                        "       .long 14b,100b\n"
 303                        "       .long 15b,100b\n"
 304                        "       .long 16b,100b\n"
 305                        "       .long 17b,100b\n"
 306                        "       .long 18b,100b\n"
 307                        "       .long 19b,100b\n"
 308                        "       .long 20b,100b\n"
 309                        "       .long 21b,100b\n"
 310                        "       .long 22b,100b\n"
 311                        "       .long 23b,100b\n"
 312                        "       .long 24b,100b\n"
 313                        "       .long 25b,100b\n"
 314                        "       .long 26b,100b\n"
 315                        "       .long 27b,100b\n"
 316                        "       .long 28b,100b\n"
 317                        "       .long 29b,100b\n"
 318                        "       .long 30b,100b\n"
 319                        "       .long 31b,100b\n"
 320                        "       .long 32b,100b\n"
 321                        "       .long 33b,100b\n"
 322                        "       .long 34b,100b\n"
 323                        "       .long 35b,100b\n"
 324                        "       .long 36b,100b\n"
 325                        "       .long 37b,100b\n"
 326                        "       .long 99b,101b\n"
 327                        ".previous"
 328                        : "=&c"(size), "=&D" (d0), "=&S" (d1)
 329                        :  "1"(to), "2"(from), "0"(size)
 330                        : "eax", "edx", "memory");
 331         return size;
 332 }
 333
 334 static unsigned long
 335 __copy_user_zeroing_intel(void *to, const void __user *from, unsigned long size)
 336 {
 337         int d0, d1;
 338         __asm__ __volatile__(
 339                        "        .align 2,0x90\n"
 340                        "0:      movl 32(%4), %%eax\n"
 341                        "        cmpl $67, %0\n"
 342                        "        jbe 2f\n"
 343                        "1:      movl 64(%4), %%eax\n"
 344                        "        .align 2,0x90\n"
 345                        "2:      movl 0(%4), %%eax\n"
 346                        "21:     movl 4(%4), %%edx\n"
 347                        "        movl %%eax, 0(%3)\n"
 348                        "        movl %%edx, 4(%3)\n"
 349                        "3:      movl 8(%4), %%eax\n"
 350                        "31:     movl 12(%4),%%edx\n"
 351                        "        movl %%eax, 8(%3)\n"
 352                        "        movl %%edx, 12(%3)\n"
 353                        "4:      movl 16(%4), %%eax\n"
 354                        "41:     movl 20(%4), %%edx\n"
 355                        "        movl %%eax, 16(%3)\n"
 356                        "        movl %%edx, 20(%3)\n"
 357                        "10:     movl 24(%4), %%eax\n"
 358                        "51:     movl 28(%4), %%edx\n"
 359                        "        movl %%eax, 24(%3)\n"
 360                        "        movl %%edx, 28(%3)\n"
 361                        "11:     movl 32(%4), %%eax\n"
 362                        "61:     movl 36(%4), %%edx\n"
 363                        "        movl %%eax, 32(%3)\n"
 364                        "        movl %%edx, 36(%3)\n"
 365                        "12:     movl 40(%4), %%eax\n"
 366                        "71:     movl 44(%4), %%edx\n"
 367                        "        movl %%eax, 40(%3)\n"
 368                        "        movl %%edx, 44(%3)\n"
 369                        "13:     movl 48(%4), %%eax\n"
 370                        "81:     movl 52(%4), %%edx\n"
 371                        "        movl %%eax, 48(%3)\n"
 372                        "        movl %%edx, 52(%3)\n"
 373                        "14:     movl 56(%4), %%eax\n"
 374                        "91:     movl 60(%4), %%edx\n"
 375                        "        movl %%eax, 56(%3)\n"
 376                        "        movl %%edx, 60(%3)\n"
 377                        "        addl $-64, %0\n"
 378                        "        addl $64, %4\n"
 379                        "        addl $64, %3\n"
 380                        "        cmpl $63, %0\n"
 381                        "        ja  0b\n"
 382                        "5:      movl  %0, %%eax\n"
 383                        "        shrl  $2, %0\n"
 384                        "        andl $3, %%eax\n"
 385                        "        cld\n"
 386                        "6:      rep; movsl\n"
 387                        "        movl %%eax,%0\n"
 388                        "7:      rep; movsb\n"
 389                        "8:\n"
 390                        ".section .fixup,\"ax\"\n"
 391                        "9:      lea 0(%%eax,%0,4),%0\n"
 392                        "16:     pushl %0\n"
 393                        "        pushl %%eax\n"
 394                        "        xorl %%eax,%%eax\n"
 395                        "        rep; stosb\n"
 396                        "        popl %%eax\n"
 397                        "        popl %0\n"
 398                        "        jmp 8b\n"
 399                        ".previous\n"
 400                        ".section __ex_table,\"a\"\n"
 401                        "        .align 4\n"
 402                        "        .long 0b,16b\n"
 403                        "        .long 1b,16b\n"
 404                        "        .long 2b,16b\n"
 405                        "        .long 21b,16b\n"
 406                        "        .long 3b,16b\n"
 407                        "        .long 31b,16b\n"
 408                        "        .long 4b,16b\n"
 409                        "        .long 41b,16b\n"
 410                        "        .long 10b,16b\n"
 411                        "        .long 51b,16b\n"
 412                        "        .long 11b,16b\n"
 413                        "        .long 61b,16b\n"
 414                        "        .long 12b,16b\n"
 415                        "        .long 71b,16b\n"
 416                        "        .long 13b,16b\n"
 417                        "        .long 81b,16b\n"
 418                        "        .long 14b,16b\n"
 419                        "        .long 91b,16b\n"
 420                        "        .long 6b,9b\n"
 421                        "        .long 7b,16b\n"
 422                        ".previous"
 423                        : "=&c"(size), "=&D" (d0), "=&S" (d1)
 424                        :  "1"(to), "2"(from), "0"(size)
 425                        : "eax", "edx", "memory");
 426         return size;
 427 }
 428 #else
 429 /*
 430  * Leave these declared but undefined.  They should not be any references to
 431  * them
 432  */
 433 unsigned long
 434 __copy_user_zeroing_intel(void *to, const void __user *from, unsigned long size);
 435 unsigned long
 436 __copy_user_intel(void __user *to, const void *from, unsigned long size);
 437 #endif /* CONFIG_X86_INTEL_USERCOPY */
 438
 439 /* Generic arbitrary sized copy.  */
 440 #define __copy_user(to,from,size)                                       \
 441 do {                                                                    \
 442         int __d0, __d1, __d2;                                           \
 443         __asm__ __volatile__(                                           \
 444                 "       cmp  $7,%0\n"                                   \
 445                 "       jbe  1f\n"                                      \
 446                 "       movl %1,%0\n"                                   \
 447                 "       negl %0\n"                                      \
 448                 "       andl $7,%0\n"                                   \
 449                 "       subl %0,%3\n"                                   \
 450                 "4:     rep; movsb\n"                                   \
 451                 "       movl %3,%0\n"                                   \
 452                 "       shrl $2,%0\n"                                   \
 453                 "       andl $3,%3\n"                                   \
 454                 "       .align 2,0x90\n"                                \
 455                 "0:     rep; movsl\n"                                   \
 456                 "       movl %3,%0\n"                                   \
 457                 "1:     rep; movsb\n"                                   \
 458                 "2:\n"                                                  \
 459                 ".section .fixup,\"ax\"\n"                              \
 460                 "5:     addl %3,%0\n"                                   \
 461                 "       jmp 2b\n"                                       \
 462                 "3:     lea 0(%3,%0,4),%0\n"                            \
 463                 "       jmp 2b\n"                                       \
 464                 ".previous\n"                                           \
 465                 ".section __ex_table,\"a\"\n"                           \
 466                 "       .align 4\n"                                     \
 467                 "       .long 4b,5b\n"                                  \
 468                 "       .long 0b,3b\n"                                  \
 469                 "       .long 1b,2b\n"                                  \
 470                 ".previous"                                             \
 471                 : "=&c"(size), "=&D" (__d0), "=&S" (__d1), "=r"(__d2)   \
 472                 : "3"(size), "0"(size), "1"(to), "2"(from)              \
 473                 : "memory");                                            \
 474 } while (0)
 475
 476 #define __copy_user_zeroing(to,from,size)                               \
 477 do {                                                                    \
 478         int __d0, __d1, __d2;                                           \
 479         __asm__ __volatile__(                                           \
 480                 "       cmp  $7,%0\n"                                   \
 481                 "       jbe  1f\n"                                      \
 482                 "       movl %1,%0\n"                                   \
 483                 "       negl %0\n"                                      \
 484                 "       andl $7,%0\n"                                   \
 485                 "       subl %0,%3\n"                                   \
 486                 "4:     rep; movsb\n"                                   \
 487                 "       movl %3,%0\n"                                   \
 488                 "       shrl $2,%0\n"                                   \
 489                 "       andl $3,%3\n"                                   \
 490                 "       .align 2,0x90\n"                                \
 491                 "0:     rep; movsl\n"                                   \
 492                 "       movl %3,%0\n"                                   \
 493                 "1:     rep; movsb\n"                                   \
 494                 "2:\n"                                                  \
 495                 ".section .fixup,\"ax\"\n"                              \
 496                 "5:     addl %3,%0\n"                                   \
 497                 "       jmp 6f\n"                                       \
 498                 "3:     lea 0(%3,%0,4),%0\n"                            \
 499                 "6:     pushl %0\n"                                     \
 500                 "       pushl %%eax\n"                                  \
 501                 "       xorl %%eax,%%eax\n"                             \
 502                 "       rep; stosb\n"                                   \
 503                 "       popl %%eax\n"                                   \
 504                 "       popl %0\n"                                      \
 505                 "       jmp 2b\n"                                       \
 506                 ".previous\n"                                           \
 507                 ".section __ex_table,\"a\"\n"                           \
 508                 "       .align 4\n"                                     \
 509                 "       .long 4b,5b\n"                                  \
 510                 "       .long 0b,3b\n"                                  \
 511                 "       .long 1b,6b\n"                                  \
 512                 ".previous"                                             \
 513                 : "=&c"(size), "=&D" (__d0), "=&S" (__d1), "=r"(__d2)   \
 514                 : "3"(size), "0"(size), "1"(to), "2"(from)              \
 515                 : "memory");                                            \
 516 } while (0)
 517
 518
 519 unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned long n)
 520 {
 521         BUG_ON((long) n < 0);
 522 #ifndef CONFIG_X86_WP_WORKS_OK
 523         if (unlikely(boot_cpu_data.wp_works_ok == 0) &&
 524                         ((unsigned long )to) < TASK_SIZE) {
 525                 /*
 526                  * CPU does not honor the WP bit when writing
 527                  * from supervisory mode, and due to preemption or SMP,
 528                  * the page tables can change at any time.
 529                  * Do it manually.      Manfred <manfred@colorfullife.com>
 530                  */
 531                 while (n) {
 532                         unsigned long offset = ((unsigned long)to)%PAGE_SIZE;
 533                         unsigned long len = PAGE_SIZE - offset;
 534                         int retval;
 535                         struct page *pg;
 536                         void *maddr;
 537
 538                         if (len > n)
 539                                 len = n;
 540
 541 survive:
 542                         down_read(&current->mm->mmap_sem);
 543                         retval = get_user_pages(current, current->mm,
 544                                         (unsigned long )to, 1, 1, 0, &pg, NULL);
 545
 546                         if (retval == -ENOMEM && current->pid == 1) {
 547                                 up_read(&current->mm->mmap_sem);
 548                                 blk_congestion_wait(WRITE, HZ/50);
 549                                 goto survive;
 550                         }
 551
 552                         if (retval != 1) {
 553                                 up_read(&current->mm->mmap_sem);
 554                                 break;
 555                         }
 556
 557                         maddr = kmap_atomic(pg, KM_USER0);
 558                         memcpy(maddr + offset, from, len);
 559                         kunmap_atomic(maddr, KM_USER0);
 560                         set_page_dirty_lock(pg);
 561                         put_page(pg);
 562                         up_read(&current->mm->mmap_sem);
 563
 564                         from += len;
 565                         to += len;
 566                         n -= len;
 567                 }
 568                 return n;
 569         }
 570 #endif
 571         if (movsl_is_ok(to, from, n))
 572                 __copy_user(to, from, n);
 573         else
 574                 n = __copy_user_intel(to, from, n);
 575         return n;
 576 }
 577 EXPORT_SYMBOL(__copy_to_user_ll);
 578
 579 unsigned long
 580 __copy_from_user_ll(void *to, const void __user *from, unsigned long n)
 581 {
 582         BUG_ON((long)n < 0);
 583         if (movsl_is_ok(to, from, n))
 584                 __copy_user_zeroing(to, from, n);
 585         else
 586                 n = __copy_user_zeroing_intel(to, from, n);
 587         return n;
 588 }
 589 EXPORT_SYMBOL(__copy_from_user_ll);
 590
 591 /**
 592  * copy_to_user: - Copy a block of data into user space.
 593  * @to:   Destination address, in user space.
 594  * @from: Source address, in kernel space.
 595  * @n:    Number of bytes to copy.
 596  *
 597  * Context: User context only.  This function may sleep.
 598  *
 599  * Copy data from kernel space to user space.
 600  *
 601  * Returns number of bytes that could not be copied.
 602  * On success, this will be zero.
 603  */
 604 unsigned long
 605 copy_to_user(void __user *to, const void *from, unsigned long n)
 606 {
 607         might_sleep();
 608         BUG_ON((long) n < 0);
 609         if (access_ok(VERIFY_WRITE, to, n))
 610                 n = __copy_to_user(to, from, n);
 611         return n;
 612 }
 613 EXPORT_SYMBOL(copy_to_user);
 614
 615 /**
 616  * copy_from_user: - Copy a block of data from user space.
 617  * @to:   Destination address, in kernel space.
 618  * @from: Source address, in user space.
 619  * @n:    Number of bytes to copy.
 620  *
 621  * Context: User context only.  This function may sleep.
 622  *
 623  * Copy data from user space to kernel space.
 624  *
 625  * Returns number of bytes that could not be copied.
 626  * On success, this will be zero.
 627  *
 628  * If some data could not be copied, this function will pad the copied
 629  * data to the requested size using zero bytes.
 630  */
 631 unsigned long
 632 copy_from_user(void *to, const void __user *from, unsigned long n)
 633 {
 634         might_sleep();
 635         BUG_ON((long) n < 0);
 636         if (access_ok(VERIFY_READ, from, n))
 637                 n = __copy_from_user(to, from, n);
 638         else
 639                 memset(to, 0, n);
 640         return n;
 641 }
 642 EXPORT_SYMBOL(copy_from_user);