include/asm-mips/uaccess.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1996, 1997, 1998, 1999, 2000, 03, 04 by Ralf Baechle
   7  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   8  * Copyright (C) 2007  Maciej W. Rozycki
   9  */
  10 #ifndef _ASM_UACCESS_H
  11 #define _ASM_UACCESS_H
  12
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/thread_info.h>
  16 #include <asm-generic/uaccess.h>
  17
  18 /*
  19  * The fs value determines whether argument validity checking should be
  20  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  21  * get_fs() == KERNEL_DS, checking is bypassed.
  22  *
  23  * For historical reasons, these macros are grossly misnamed.
  24  */
  25 #ifdef CONFIG_32BIT
  26
  27 #define __UA_LIMIT      0x80000000UL
  28
  29 #define __UA_ADDR       ".word"
  30 #define __UA_LA         "la"
  31 #define __UA_ADDU       "addu"
  32 #define __UA_t0         "$8"
  33 #define __UA_t1         "$9"
  34
  35 #endif /* CONFIG_32BIT */
  36
  37 #ifdef CONFIG_64BIT
  38
  39 #define __UA_LIMIT      (- TASK_SIZE)
  40
  41 #define __UA_ADDR       ".dword"
  42 #define __UA_LA         "dla"
  43 #define __UA_ADDU       "daddu"
  44 #define __UA_t0         "$12"
  45 #define __UA_t1         "$13"
  46
  47 #endif /* CONFIG_64BIT */
  48
  49 /*
  50  * USER_DS is a bitmask that has the bits set that may not be set in a valid
  51  * userspace address.  Note that we limit 32-bit userspace to 0x7fff8000 but
  52  * the arithmetic we're doing only works if the limit is a power of two, so
  53  * we use 0x80000000 here on 32-bit kernels.  If a process passes an invalid
  54  * address in this range it's the process's problem, not ours :-)
  55  */
  56
  57 #define KERNEL_DS       ((mm_segment_t) { 0UL })
  58 #define USER_DS         ((mm_segment_t) { __UA_LIMIT })
  59
  60 #define VERIFY_READ    0
  61 #define VERIFY_WRITE   1
  62
  63 #define get_ds()        (KERNEL_DS)
  64 #define get_fs()        (current_thread_info()->addr_limit)
  65 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  66
  67 #define segment_eq(a, b)        ((a).seg == (b).seg)
  68
  69
  70 /*
  71  * Is a address valid? This does a straighforward calculation rather
  72  * than tests.
  73  *
  74  * Address valid if:
  75  *  - "addr" doesn't have any high-bits set
  76  *  - AND "size" doesn't have any high-bits set
  77  *  - AND "addr+size" doesn't have any high-bits set
  78  *  - OR we are in kernel mode.
  79  *
  80  * __ua_size() is a trick to avoid runtime checking of positive constant
  81  * sizes; for those we already know at compile time that the size is ok.
  82  */
  83 #define __ua_size(size)                                                 \
  84         ((__builtin_constant_p(size) && (signed long) (size) > 0) ? 0 : (size))
  85
  86 /*
  87  * access_ok: - Checks if a user space pointer is valid
  88  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  89  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  90  *        to write to a block, it is always safe to read from it.
  91  * @addr: User space pointer to start of block to check
  92  * @size: Size of block to check
  93  *
  94  * Context: User context only.  This function may sleep.
  95  *
  96  * Checks if a pointer to a block of memory in user space is valid.
  97  *
  98  * Returns true (nonzero) if the memory block may be valid, false (zero)
  99  * if it is definitely invalid.
 100  *
 101  * Note that, depending on architecture, this function probably just
 102  * checks that the pointer is in the user space range - after calling
 103  * this function, memory access functions may still return -EFAULT.
 104  */
 105
 106 #define __access_mask get_fs().seg
 107
 108 #define __access_ok(addr, size, mask)                                   \
 109         (((signed long)((mask) & ((addr) | ((addr) + (size)) | __ua_size(size)))) == 0)
 110
 111 #define access_ok(type, addr, size)                                     \
 112         likely(__access_ok((unsigned long)(addr), (size), __access_mask))
 113
 114 /*
 115  * put_user: - Write a simple value into user space.
 116  * @x:   Value to copy to user space.
 117  * @ptr: Destination address, in user space.
 118  *
 119  * Context: User context only.  This function may sleep.
 120  *
 121  * This macro copies a single simple value from kernel space to user
 122  * space.  It supports simple types like char and int, but not larger
 123  * data types like structures or arrays.
 124  *
 125  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 126  * to the result of dereferencing @ptr.
 127  *
 128  * Returns zero on success, or -EFAULT on error.
 129  */
 130 #define put_user(x,ptr) \
 131         __put_user_check((x), (ptr), sizeof(*(ptr)))
 132
 133 /*
 134  * get_user: - Get a simple variable from user space.
 135  * @x:   Variable to store result.
 136  * @ptr: Source address, in user space.
 137  *
 138  * Context: User context only.  This function may sleep.
 139  *
 140  * This macro copies a single simple variable from user space to kernel
 141  * space.  It supports simple types like char and int, but not larger
 142  * data types like structures or arrays.
 143  *
 144  * @ptr must have pointer-to-simple-variable type, and the result of
 145  * dereferencing @ptr must be assignable to @x without a cast.
 146  *
 147  * Returns zero on success, or -EFAULT on error.
 148  * On error, the variable @x is set to zero.
 149  */
 150 #define get_user(x,ptr) \
 151         __get_user_check((x), (ptr), sizeof(*(ptr)))
 152
 153 /*
 154  * __put_user: - Write a simple value into user space, with less checking.
 155  * @x:   Value to copy to user space.
 156  * @ptr: Destination address, in user space.
 157  *
 158  * Context: User context only.  This function may sleep.
 159  *
 160  * This macro copies a single simple value from kernel space to user
 161  * space.  It supports simple types like char and int, but not larger
 162  * data types like structures or arrays.
 163  *
 164  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 165  * to the result of dereferencing @ptr.
 166  *
 167  * Caller must check the pointer with access_ok() before calling this
 168  * function.
 169  *
 170  * Returns zero on success, or -EFAULT on error.
 171  */
 172 #define __put_user(x,ptr) \
 173         __put_user_nocheck((x), (ptr), sizeof(*(ptr)))
 174
 175 /*
 176  * __get_user: - Get a simple variable from user space, with less checking.
 177  * @x:   Variable to store result.
 178  * @ptr: Source address, in user space.
 179  *
 180  * Context: User context only.  This function may sleep.
 181  *
 182  * This macro copies a single simple variable from user space to kernel
 183  * space.  It supports simple types like char and int, but not larger
 184  * data types like structures or arrays.
 185  *
 186  * @ptr must have pointer-to-simple-variable type, and the result of
 187  * dereferencing @ptr must be assignable to @x without a cast.
 188  *
 189  * Caller must check the pointer with access_ok() before calling this
 190  * function.
 191  *
 192  * Returns zero on success, or -EFAULT on error.
 193  * On error, the variable @x is set to zero.
 194  */
 195 #define __get_user(x,ptr) \
 196         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 197
 198 struct __large_struct { unsigned long buf[100]; };
 199 #define __m(x) (*(struct __large_struct __user *)(x))
 200
 201 /*
 202  * Yuck.  We need two variants, one for 64bit operation and one
 203  * for 32 bit mode and old iron.
 204  */
 205 #ifdef CONFIG_32BIT
 206 #define __GET_USER_DW(val, ptr) __get_user_asm_ll32(val, ptr)
 207 #endif
 208 #ifdef CONFIG_64BIT
 209 #define __GET_USER_DW(val, ptr) __get_user_asm(val, "ld", ptr)
 210 #endif
 211
 212 extern void __get_user_unknown(void);
 213
 214 #define __get_user_common(val, size, ptr)                               \
 215 do {                                                                    \
 216         switch (size) {                                                 \
 217         case 1: __get_user_asm(val, "lb", ptr); break;                  \
 218         case 2: __get_user_asm(val, "lh", ptr); break;                  \
 219         case 4: __get_user_asm(val, "lw", ptr); break;                  \
 220         case 8: __GET_USER_DW(val, ptr); break;                         \
 221         default: __get_user_unknown(); break;                           \
 222         }                                                               \
 223 } while (0)
 224
 225 #define __get_user_nocheck(x, ptr, size)                                \
 226 ({                                                                      \
 227         long __gu_err;                                                  \
 228                                                                         \
 229         __get_user_common((x), size, ptr);                              \
 230         __gu_err;                                                       \
 231 })
 232
 233 #define __get_user_check(x, ptr, size)                                  \
 234 ({                                                                      \
 235         long __gu_err = -EFAULT;                                        \
 236         const __typeof__(*(ptr)) __user * __gu_ptr = (ptr);             \
 237                                                                         \
 238         if (likely(access_ok(VERIFY_READ,  __gu_ptr, size)))            \
 239                 __get_user_common((x), size, __gu_ptr);                 \
 240                                                                         \
 241         __gu_err;                                                       \
 242 })
 243
 244 #define __get_user_asm(val, insn, addr)                                 \
 245 {                                                                       \
 246         long __gu_tmp;                                                  \
 247                                                                         \
 248         __asm__ __volatile__(                                           \
 249         "1:     " insn "        %1, %3                          \n"     \
 250         "2:                                                     \n"     \
 251         "       .section .fixup,\"ax\"                          \n"     \
 252         "3:     li      %0, %4                                  \n"     \
 253         "       j       2b                                      \n"     \
 254         "       .previous                                       \n"     \
 255         "       .section __ex_table,\"a\"                       \n"     \
 256         "       "__UA_ADDR "\t1b, 3b                            \n"     \
 257         "       .previous                                       \n"     \
 258         : "=r" (__gu_err), "=r" (__gu_tmp)                              \
 259         : "0" (0), "o" (__m(addr)), "i" (-EFAULT));                     \
 260                                                                         \
 261         (val) = (__typeof__(*(addr))) __gu_tmp;                         \
 262 }
 263
 264 /*
 265  * Get a long long 64 using 32 bit registers.
 266  */
 267 #define __get_user_asm_ll32(val, addr)                                  \
 268 {                                                                       \
 269         union {                                                         \
 270                 unsigned long long      l;                              \
 271                 __typeof__(*(addr))     t;                              \
 272         } __gu_tmp;                                                     \
 273                                                                         \
 274         __asm__ __volatile__(                                           \
 275         "1:     lw      %1, (%3)                                \n"     \
 276         "2:     lw      %D1, 4(%3)                              \n"     \
 277         "3:     .section        .fixup,\"ax\"                   \n"     \
 278         "4:     li      %0, %4                                  \n"     \
 279         "       move    %1, $0                                  \n"     \
 280         "       move    %D1, $0                                 \n"     \
 281         "       j       3b                                      \n"     \
 282         "       .previous                                       \n"     \
 283         "       .section        __ex_table,\"a\"                \n"     \
 284         "       " __UA_ADDR "   1b, 4b                          \n"     \
 285         "       " __UA_ADDR "   2b, 4b                          \n"     \
 286         "       .previous                                       \n"     \
 287         : "=r" (__gu_err), "=&r" (__gu_tmp.l)                           \
 288         : "0" (0), "r" (addr), "i" (-EFAULT));                          \
 289                                                                         \
 290         (val) = __gu_tmp.t;                                             \
 291 }
 292
 293 /*
 294  * Yuck.  We need two variants, one for 64bit operation and one
 295  * for 32 bit mode and old iron.
 296  */
 297 #ifdef CONFIG_32BIT
 298 #define __PUT_USER_DW(ptr) __put_user_asm_ll32(ptr)
 299 #endif
 300 #ifdef CONFIG_64BIT
 301 #define __PUT_USER_DW(ptr) __put_user_asm("sd", ptr)
 302 #endif
 303
 304 #define __put_user_nocheck(x, ptr, size)                                \
 305 ({                                                                      \
 306         __typeof__(*(ptr)) __pu_val;                                    \
 307         long __pu_err = 0;                                              \
 308                                                                         \
 309         __pu_val = (x);                                                 \
 310         switch (size) {                                                 \
 311         case 1: __put_user_asm("sb", ptr); break;                       \
 312         case 2: __put_user_asm("sh", ptr); break;                       \
 313         case 4: __put_user_asm("sw", ptr); break;                       \
 314         case 8: __PUT_USER_DW(ptr); break;                              \
 315         default: __put_user_unknown(); break;                           \
 316         }                                                               \
 317         __pu_err;                                                       \
 318 })
 319
 320 #define __put_user_check(x, ptr, size)                                  \
 321 ({                                                                      \
 322         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 323         __typeof__(*(ptr)) __pu_val = (x);                              \
 324         long __pu_err = -EFAULT;                                        \
 325                                                                         \
 326         if (likely(access_ok(VERIFY_WRITE,  __pu_addr, size))) {        \
 327                 switch (size) {                                         \
 328                 case 1: __put_user_asm("sb", __pu_addr); break;         \
 329                 case 2: __put_user_asm("sh", __pu_addr); break;         \
 330                 case 4: __put_user_asm("sw", __pu_addr); break;         \
 331                 case 8: __PUT_USER_DW(__pu_addr); break;                \
 332                 default: __put_user_unknown(); break;                   \
 333                 }                                                       \
 334         }                                                               \
 335         __pu_err;                                                       \
 336 })
 337
 338 #define __put_user_asm(insn, ptr)                                       \
 339 {                                                                       \
 340         __asm__ __volatile__(                                           \
 341         "1:     " insn "        %z2, %3         # __put_user_asm\n"     \
 342         "2:                                                     \n"     \
 343         "       .section        .fixup,\"ax\"                   \n"     \
 344         "3:     li      %0, %4                                  \n"     \
 345         "       j       2b                                      \n"     \
 346         "       .previous                                       \n"     \
 347         "       .section        __ex_table,\"a\"                \n"     \
 348         "       " __UA_ADDR "   1b, 3b                          \n"     \
 349         "       .previous                                       \n"     \
 350         : "=r" (__pu_err)                                               \
 351         : "0" (0), "Jr" (__pu_val), "o" (__m(ptr)),                     \
 352           "i" (-EFAULT));                                               \
 353 }
 354
 355 #define __put_user_asm_ll32(ptr)                                        \
 356 {                                                                       \
 357         __asm__ __volatile__(                                           \
 358         "1:     sw      %2, (%3)        # __put_user_asm_ll32   \n"     \
 359         "2:     sw      %D2, 4(%3)                              \n"     \
 360         "3:                                                     \n"     \
 361         "       .section        .fixup,\"ax\"                   \n"     \
 362         "4:     li      %0, %4                                  \n"     \
 363         "       j       3b                                      \n"     \
 364         "       .previous                                       \n"     \
 365         "       .section        __ex_table,\"a\"                \n"     \
 366         "       " __UA_ADDR "   1b, 4b                          \n"     \
 367         "       " __UA_ADDR "   2b, 4b                          \n"     \
 368         "       .previous"                                              \
 369         : "=r" (__pu_err)                                               \
 370         : "0" (0), "r" (__pu_val), "r" (ptr),                           \
 371           "i" (-EFAULT));                                               \
 372 }
 373
 374 extern void __put_user_unknown(void);
 375
 376 /*
 377  * We're generating jump to subroutines which will be outside the range of
 378  * jump instructions
 379  */
 380 #ifdef MODULE
 381 #define __MODULE_JAL(destination)                                       \
 382         ".set\tnoat\n\t"                                                \
 383         __UA_LA "\t$1, " #destination "\n\t"                            \
 384         "jalr\t$1\n\t"                                                  \
 385         ".set\tat\n\t"
 386 #else
 387 #define __MODULE_JAL(destination)                                       \
 388         "jal\t" #destination "\n\t"
 389 #endif
 390
 391 #ifndef CONFIG_CPU_DADDI_WORKAROUNDS
 392 #define DADDI_SCRATCH "$0"
 393 #else
 394 #define DADDI_SCRATCH "$3"
 395 #endif
 396
 397 extern size_t __copy_user(void *__to, const void *__from, size_t __n);
 398
 399 #define __invoke_copy_to_user(to, from, n)                              \
 400 ({                                                                      \
 401         register void __user *__cu_to_r __asm__("$4");                  \
 402         register const void *__cu_from_r __asm__("$5");                 \
 403         register long __cu_len_r __asm__("$6");                         \
 404                                                                         \
 405         __cu_to_r = (to);                                               \
 406         __cu_from_r = (from);                                           \
 407         __cu_len_r = (n);                                               \
 408         __asm__ __volatile__(                                           \
 409         __MODULE_JAL(__copy_user)                                       \
 410         : "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r)       \
 411         :                                                               \
 412         : "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31",         \
 413           DADDI_SCRATCH, "memory");                                     \
 414         __cu_len_r;                                                     \
 415 })
 416
 417 /*
 418  * __copy_to_user: - Copy a block of data into user space, with less checking.
 419  * @to:   Destination address, in user space.
 420  * @from: Source address, in kernel space.
 421  * @n:    Number of bytes to copy.
 422  *
 423  * Context: User context only.  This function may sleep.
 424  *
 425  * Copy data from kernel space to user space.  Caller must check
 426  * the specified block with access_ok() before calling this function.
 427  *
 428  * Returns number of bytes that could not be copied.
 429  * On success, this will be zero.
 430  */
 431 #define __copy_to_user(to, from, n)                                     \
 432 ({                                                                      \
 433         void __user *__cu_to;                                           \
 434         const void *__cu_from;                                          \
 435         long __cu_len;                                                  \
 436                                                                         \
 437         might_sleep();                                                  \
 438         __cu_to = (to);                                                 \
 439         __cu_from = (from);                                             \
 440         __cu_len = (n);                                                 \
 441         __cu_len = __invoke_copy_to_user(__cu_to, __cu_from, __cu_len); \
 442         __cu_len;                                                       \
 443 })
 444
 445 extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n);
 446
 447 #define __copy_to_user_inatomic(to, from, n)                            \
 448 ({                                                                      \
 449         void __user *__cu_to;                                           \
 450         const void *__cu_from;                                          \
 451         long __cu_len;                                                  \
 452                                                                         \
 453         __cu_to = (to);                                                 \
 454         __cu_from = (from);                                             \
 455         __cu_len = (n);                                                 \
 456         __cu_len = __invoke_copy_to_user(__cu_to, __cu_from, __cu_len); \
 457         __cu_len;                                                       \
 458 })
 459
 460 #define __copy_from_user_inatomic(to, from, n)                          \
 461 ({                                                                      \
 462         void *__cu_to;                                                  \
 463         const void __user *__cu_from;                                   \
 464         long __cu_len;                                                  \
 465                                                                         \
 466         __cu_to = (to);                                                 \
 467         __cu_from = (from);                                             \
 468         __cu_len = (n);                                                 \
 469         __cu_len = __invoke_copy_from_user_inatomic(__cu_to, __cu_from, \
 470                                                     __cu_len);          \
 471         __cu_len;                                                       \
 472 })
 473
 474 /*
 475  * copy_to_user: - Copy a block of data into user space.
 476  * @to:   Destination address, in user space.
 477  * @from: Source address, in kernel space.
 478  * @n:    Number of bytes to copy.
 479  *
 480  * Context: User context only.  This function may sleep.
 481  *
 482  * Copy data from kernel space to user space.
 483  *
 484  * Returns number of bytes that could not be copied.
 485  * On success, this will be zero.
 486  */
 487 #define copy_to_user(to, from, n)                                       \
 488 ({                                                                      \
 489         void __user *__cu_to;                                           \
 490         const void *__cu_from;                                          \
 491         long __cu_len;                                                  \
 492                                                                         \
 493         might_sleep();                                                  \
 494         __cu_to = (to);                                                 \
 495         __cu_from = (from);                                             \
 496         __cu_len = (n);                                                 \
 497         if (access_ok(VERIFY_WRITE, __cu_to, __cu_len))                 \
 498                 __cu_len = __invoke_copy_to_user(__cu_to, __cu_from,    \
 499                                                  __cu_len);             \
 500         __cu_len;                                                       \
 501 })
 502
 503 #define __invoke_copy_from_user(to, from, n)                            \
 504 ({                                                                      \
 505         register void *__cu_to_r __asm__("$4");                         \
 506         register const void __user *__cu_from_r __asm__("$5");          \
 507         register long __cu_len_r __asm__("$6");                         \
 508                                                                         \
 509         __cu_to_r = (to);                                               \
 510         __cu_from_r = (from);                                           \
 511         __cu_len_r = (n);                                               \
 512         __asm__ __volatile__(                                           \
 513         ".set\tnoreorder\n\t"                                           \
 514         __MODULE_JAL(__copy_user)                                       \
 515         ".set\tnoat\n\t"                                                \
 516         __UA_ADDU "\t$1, %1, %2\n\t"                                    \
 517         ".set\tat\n\t"                                                  \
 518         ".set\treorder"                                                 \
 519         : "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r)       \
 520         :                                                               \
 521         : "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31",         \
 522           DADDI_SCRATCH, "memory");                                     \
 523         __cu_len_r;                                                     \
 524 })
 525
 526 #define __invoke_copy_from_user_inatomic(to, from, n)                   \
 527 ({                                                                      \
 528         register void *__cu_to_r __asm__("$4");                         \
 529         register const void __user *__cu_from_r __asm__("$5");          \
 530         register long __cu_len_r __asm__("$6");                         \
 531                                                                         \
 532         __cu_to_r = (to);                                               \
 533         __cu_from_r = (from);                                           \
 534         __cu_len_r = (n);                                               \
 535         __asm__ __volatile__(                                           \
 536         ".set\tnoreorder\n\t"                                           \
 537         __MODULE_JAL(__copy_user_inatomic)                              \
 538         ".set\tnoat\n\t"                                                \
 539         __UA_ADDU "\t$1, %1, %2\n\t"                                    \
 540         ".set\tat\n\t"                                                  \
 541         ".set\treorder"                                                 \
 542         : "+r" (__cu_to_r), "+r" (__cu_from_r), "+r" (__cu_len_r)       \
 543         :                                                               \
 544         : "$8", "$9", "$10", "$11", "$12", "$15", "$24", "$31",         \
 545           DADDI_SCRATCH, "memory");                                     \
 546         __cu_len_r;                                                     \
 547 })
 548
 549 /*
 550  * __copy_from_user: - Copy a block of data from user space, with less checking.
 551  * @to:   Destination address, in kernel space.
 552  * @from: Source address, in user space.
 553  * @n:    Number of bytes to copy.
 554  *
 555  * Context: User context only.  This function may sleep.
 556  *
 557  * Copy data from user space to kernel space.  Caller must check
 558  * the specified block with access_ok() before calling this function.
 559  *
 560  * Returns number of bytes that could not be copied.
 561  * On success, this will be zero.
 562  *
 563  * If some data could not be copied, this function will pad the copied
 564  * data to the requested size using zero bytes.
 565  */
 566 #define __copy_from_user(to, from, n)                                   \
 567 ({                                                                      \
 568         void *__cu_to;                                                  \
 569         const void __user *__cu_from;                                   \
 570         long __cu_len;                                                  \
 571                                                                         \
 572         might_sleep();                                                  \
 573         __cu_to = (to);                                                 \
 574         __cu_from = (from);                                             \
 575         __cu_len = (n);                                                 \
 576         __cu_len = __invoke_copy_from_user(__cu_to, __cu_from,          \
 577                                            __cu_len);                   \
 578         __cu_len;                                                       \
 579 })
 580
 581 /*
 582  * copy_from_user: - Copy a block of data from user space.
 583  * @to:   Destination address, in kernel space.
 584  * @from: Source address, in user space.
 585  * @n:    Number of bytes to copy.
 586  *
 587  * Context: User context only.  This function may sleep.
 588  *
 589  * Copy data from user space to kernel space.
 590  *
 591  * Returns number of bytes that could not be copied.
 592  * On success, this will be zero.
 593  *
 594  * If some data could not be copied, this function will pad the copied
 595  * data to the requested size using zero bytes.
 596  */
 597 #define copy_from_user(to, from, n)                                     \
 598 ({                                                                      \
 599         void *__cu_to;                                                  \
 600         const void __user *__cu_from;                                   \
 601         long __cu_len;                                                  \
 602                                                                         \
 603         might_sleep();                                                  \
 604         __cu_to = (to);                                                 \
 605         __cu_from = (from);                                             \
 606         __cu_len = (n);                                                 \
 607         if (access_ok(VERIFY_READ, __cu_from, __cu_len))                \
 608                 __cu_len = __invoke_copy_from_user(__cu_to, __cu_from,  \
 609                                                    __cu_len);           \
 610         __cu_len;                                                       \
 611 })
 612
 613 #define __copy_in_user(to, from, n)     __copy_from_user(to, from, n)
 614
 615 #define copy_in_user(to, from, n)                                       \
 616 ({                                                                      \
 617         void __user *__cu_to;                                           \
 618         const void __user *__cu_from;                                   \
 619         long __cu_len;                                                  \
 620                                                                         \
 621         might_sleep();                                                  \
 622         __cu_to = (to);                                                 \
 623         __cu_from = (from);                                             \
 624         __cu_len = (n);                                                 \
 625         if (likely(access_ok(VERIFY_READ, __cu_from, __cu_len) &&       \
 626                    access_ok(VERIFY_WRITE, __cu_to, __cu_len)))         \
 627                 __cu_len = __invoke_copy_from_user(__cu_to, __cu_from,  \
 628                                                    __cu_len);           \
 629         __cu_len;                                                       \
 630 })
 631
 632 /*
 633  * __clear_user: - Zero a block of memory in user space, with less checking.
 634  * @to:   Destination address, in user space.
 635  * @n:    Number of bytes to zero.
 636  *
 637  * Zero a block of memory in user space.  Caller must check
 638  * the specified block with access_ok() before calling this function.
 639  *
 640  * Returns number of bytes that could not be cleared.
 641  * On success, this will be zero.
 642  */
 643 static inline __kernel_size_t
 644 __clear_user(void __user *addr, __kernel_size_t size)
 645 {
 646         __kernel_size_t res;
 647
 648         might_sleep();
 649         __asm__ __volatile__(
 650                 "move\t$4, %1\n\t"
 651                 "move\t$5, $0\n\t"
 652                 "move\t$6, %2\n\t"
 653                 __MODULE_JAL(__bzero)
 654                 "move\t%0, $6"
 655                 : "=r" (res)
 656                 : "r" (addr), "r" (size)
 657                 : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
 658
 659         return res;
 660 }
 661
 662 #define clear_user(addr,n)                                              \
 663 ({                                                                      \
 664         void __user * __cl_addr = (addr);                               \
 665         unsigned long __cl_size = (n);                                  \
 666         if (__cl_size && access_ok(VERIFY_WRITE,                        \
 667                 ((unsigned long)(__cl_addr)), __cl_size))               \
 668                 __cl_size = __clear_user(__cl_addr, __cl_size);         \
 669         __cl_size;                                                      \
 670 })
 671
 672 /*
 673  * __strncpy_from_user: - Copy a NUL terminated string from userspace, with less checking.
 674  * @dst:   Destination address, in kernel space.  This buffer must be at
 675  *         least @count bytes long.
 676  * @src:   Source address, in user space.
 677  * @count: Maximum number of bytes to copy, including the trailing NUL.
 678  *
 679  * Copies a NUL-terminated string from userspace to kernel space.
 680  * Caller must check the specified block with access_ok() before calling
 681  * this function.
 682  *
 683  * On success, returns the length of the string (not including the trailing
 684  * NUL).
 685  *
 686  * If access to userspace fails, returns -EFAULT (some data may have been
 687  * copied).
 688  *
 689  * If @count is smaller than the length of the string, copies @count bytes
 690  * and returns @count.
 691  */
 692 static inline long
 693 __strncpy_from_user(char *__to, const char __user *__from, long __len)
 694 {
 695         long res;
 696
 697         might_sleep();
 698         __asm__ __volatile__(
 699                 "move\t$4, %1\n\t"
 700                 "move\t$5, %2\n\t"
 701                 "move\t$6, %3\n\t"
 702                 __MODULE_JAL(__strncpy_from_user_nocheck_asm)
 703                 "move\t%0, $2"
 704                 : "=r" (res)
 705                 : "r" (__to), "r" (__from), "r" (__len)
 706                 : "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
 707
 708         return res;
 709 }
 710
 711 /*
 712  * strncpy_from_user: - Copy a NUL terminated string from userspace.
 713  * @dst:   Destination address, in kernel space.  This buffer must be at
 714  *         least @count bytes long.
 715  * @src:   Source address, in user space.
 716  * @count: Maximum number of bytes to copy, including the trailing NUL.
 717  *
 718  * Copies a NUL-terminated string from userspace to kernel space.
 719  *
 720  * On success, returns the length of the string (not including the trailing
 721  * NUL).
 722  *
 723  * If access to userspace fails, returns -EFAULT (some data may have been
 724  * copied).
 725  *
 726  * If @count is smaller than the length of the string, copies @count bytes
 727  * and returns @count.
 728  */
 729 static inline long
 730 strncpy_from_user(char *__to, const char __user *__from, long __len)
 731 {
 732         long res;
 733
 734         might_sleep();
 735         __asm__ __volatile__(
 736                 "move\t$4, %1\n\t"
 737                 "move\t$5, %2\n\t"
 738                 "move\t$6, %3\n\t"
 739                 __MODULE_JAL(__strncpy_from_user_asm)
 740                 "move\t%0, $2"
 741                 : "=r" (res)
 742                 : "r" (__to), "r" (__from), "r" (__len)
 743                 : "$2", "$3", "$4", "$5", "$6", __UA_t0, "$31", "memory");
 744
 745         return res;
 746 }
 747
 748 /* Returns: 0 if bad, string length+1 (memory size) of string if ok */
 749 static inline long __strlen_user(const char __user *s)
 750 {
 751         long res;
 752
 753         might_sleep();
 754         __asm__ __volatile__(
 755                 "move\t$4, %1\n\t"
 756                 __MODULE_JAL(__strlen_user_nocheck_asm)
 757                 "move\t%0, $2"
 758                 : "=r" (res)
 759                 : "r" (s)
 760                 : "$2", "$4", __UA_t0, "$31");
 761
 762         return res;
 763 }
 764
 765 /*
 766  * strlen_user: - Get the size of a string in user space.
 767  * @str: The string to measure.
 768  *
 769  * Context: User context only.  This function may sleep.
 770  *
 771  * Get the size of a NUL-terminated string in user space.
 772  *
 773  * Returns the size of the string INCLUDING the terminating NUL.
 774  * On exception, returns 0.
 775  *
 776  * If there is a limit on the length of a valid string, you may wish to
 777  * consider using strnlen_user() instead.
 778  */
 779 static inline long strlen_user(const char __user *s)
 780 {
 781         long res;
 782
 783         might_sleep();
 784         __asm__ __volatile__(
 785                 "move\t$4, %1\n\t"
 786                 __MODULE_JAL(__strlen_user_asm)
 787                 "move\t%0, $2"
 788                 : "=r" (res)
 789                 : "r" (s)
 790                 : "$2", "$4", __UA_t0, "$31");
 791
 792         return res;
 793 }
 794
 795 /* Returns: 0 if bad, string length+1 (memory size) of string if ok */
 796 static inline long __strnlen_user(const char __user *s, long n)
 797 {
 798         long res;
 799
 800         might_sleep();
 801         __asm__ __volatile__(
 802                 "move\t$4, %1\n\t"
 803                 "move\t$5, %2\n\t"
 804                 __MODULE_JAL(__strnlen_user_nocheck_asm)
 805                 "move\t%0, $2"
 806                 : "=r" (res)
 807                 : "r" (s), "r" (n)
 808                 : "$2", "$4", "$5", __UA_t0, "$31");
 809
 810         return res;
 811 }
 812
 813 /*
 814  * strlen_user: - Get the size of a string in user space.
 815  * @str: The string to measure.
 816  *
 817  * Context: User context only.  This function may sleep.
 818  *
 819  * Get the size of a NUL-terminated string in user space.
 820  *
 821  * Returns the size of the string INCLUDING the terminating NUL.
 822  * On exception, returns 0.
 823  *
 824  * If there is a limit on the length of a valid string, you may wish to
 825  * consider using strnlen_user() instead.
 826  */
 827 static inline long strnlen_user(const char __user *s, long n)
 828 {
 829         long res;
 830
 831         might_sleep();
 832         __asm__ __volatile__(
 833                 "move\t$4, %1\n\t"
 834                 "move\t$5, %2\n\t"
 835                 __MODULE_JAL(__strnlen_user_asm)
 836                 "move\t%0, $2"
 837                 : "=r" (res)
 838                 : "r" (s), "r" (n)
 839                 : "$2", "$4", "$5", __UA_t0, "$31");
 840
 841         return res;
 842 }
 843
 844 struct exception_table_entry
 845 {
 846         unsigned long insn;
 847         unsigned long nextinsn;
 848 };
 849
 850 extern int fixup_exception(struct pt_regs *regs);
 851
 852 #endif /* _ASM_UACCESS_H */