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   1 #ifndef __i386_UACCESS_H
   2 #define __i386_UACCESS_H
   3
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/errno.h>
   8 #include <linux/thread_info.h>
   9 #include <linux/prefetch.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13
  14 /*
  15  * movsl can be slow when source and dest are not both 8-byte aligned
  16  */
  17 #ifdef CONFIG_X86_INTEL_USERCOPY
  18 extern struct movsl_mask {
  19         int mask;
  20 } ____cacheline_aligned_in_smp movsl_mask;
  21 #endif
  22
  23 #define __addr_ok(addr)                                 \
  24         ((unsigned long __force)(addr) <                \
  25          (current_thread_info()->addr_limit.seg))
  26
  27 /* Careful: we have to cast the result to the type of the pointer
  28  * for sign reasons */
  29
  30 /**
  31  * get_user: - Get a simple variable from user space.
  32  * @x:   Variable to store result.
  33  * @ptr: Source address, in user space.
  34  *
  35  * Context: User context only.  This function may sleep.
  36  *
  37  * This macro copies a single simple variable from user space to kernel
  38  * space.  It supports simple types like char and int, but not larger
  39  * data types like structures or arrays.
  40  *
  41  * @ptr must have pointer-to-simple-variable type, and the result of
  42  * dereferencing @ptr must be assignable to @x without a cast.
  43  *
  44  * Returns zero on success, or -EFAULT on error.
  45  * On error, the variable @x is set to zero.
  46  */
  47 #define get_user(x, ptr)                                                \
  48 ({                                                                      \
  49         int __ret_gu;                                                   \
  50         unsigned long __val_gu;                                         \
  51         __chk_user_ptr(ptr);                                            \
  52         switch (sizeof(*(ptr))) {                                       \
  53         case 1:                                                         \
  54                 __get_user_x(1, __ret_gu, __val_gu, ptr);               \
  55                 break;                                                  \
  56         case 2:                                                         \
  57                 __get_user_x(2, __ret_gu, __val_gu, ptr);               \
  58                 break;                                                  \
  59         case 4:                                                         \
  60                 __get_user_x(4, __ret_gu, __val_gu, ptr);               \
  61                 break;                                                  \
  62         default:                                                        \
  63                 __get_user_x(X, __ret_gu, __val_gu, ptr);               \
  64                 break;                                                  \
  65         }                                                               \
  66         (x) = (__typeof__(*(ptr)))__val_gu;                             \
  67         __ret_gu;                                                       \
  68 })
  69
  70 extern void __put_user_bad(void);
  71
  72 /*
  73  * Strange magic calling convention: pointer in %ecx,
  74  * value in %eax(:%edx), return value in %eax, no clobbers.
  75  */
  76 extern void __put_user_1(void);
  77 extern void __put_user_2(void);
  78 extern void __put_user_4(void);
  79 extern void __put_user_8(void);
  80
  81 #define __put_user_x(size, x, ptr)                              \
  82         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
  83                      :"0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
  84
  85 #define __put_user_8(x, ptr)                                    \
  86         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
  87                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
  88
  89
  90 /**
  91  * put_user: - Write a simple value into user space.
  92  * @x:   Value to copy to user space.
  93  * @ptr: Destination address, in user space.
  94  *
  95  * Context: User context only.  This function may sleep.
  96  *
  97  * This macro copies a single simple value from kernel space to user
  98  * space.  It supports simple types like char and int, but not larger
  99  * data types like structures or arrays.
 100  *
 101  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 102  * to the result of dereferencing @ptr.
 103  *
 104  * Returns zero on success, or -EFAULT on error.
 105  */
 106 #ifdef CONFIG_X86_WP_WORKS_OK
 107
 108 #define put_user(x, ptr)                                        \
 109 ({                                                              \
 110         int __ret_pu;                                           \
 111         __typeof__(*(ptr)) __pu_val;                            \
 112         __chk_user_ptr(ptr);                                    \
 113         __pu_val = x;                                           \
 114         switch (sizeof(*(ptr))) {                               \
 115         case 1:                                                 \
 116                 __put_user_x(1, __pu_val, ptr);                 \
 117                 break;                                          \
 118         case 2:                                                 \
 119                 __put_user_x(2, __pu_val, ptr);                 \
 120                 break;                                          \
 121         case 4:                                                 \
 122                 __put_user_x(4, __pu_val, ptr);                 \
 123                 break;                                          \
 124         case 8:                                                 \
 125                 __put_user_8(__pu_val, ptr);                    \
 126                 break;                                          \
 127         default:                                                \
 128                 __put_user_x(X, __pu_val, ptr);                 \
 129                 break;                                          \
 130         }                                                       \
 131         __ret_pu;                                               \
 132 })
 133
 134 #else
 135 #define put_user(x, ptr)                                        \
 136 ({                                                              \
 137         int __ret_pu;                                           \
 138         __typeof__(*(ptr))__pus_tmp = x;                        \
 139         __ret_pu = 0;                                           \
 140         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp,         \
 141                                        sizeof(*(ptr))) != 0))   \
 142                 __ret_pu = -EFAULT;                             \
 143         __ret_pu;                                               \
 144 })
 145
 146
 147 #endif
 148
 149 /**
 150  * __get_user: - Get a simple variable from user space, with less checking.
 151  * @x:   Variable to store result.
 152  * @ptr: Source address, in user space.
 153  *
 154  * Context: User context only.  This function may sleep.
 155  *
 156  * This macro copies a single simple variable from user space to kernel
 157  * space.  It supports simple types like char and int, but not larger
 158  * data types like structures or arrays.
 159  *
 160  * @ptr must have pointer-to-simple-variable type, and the result of
 161  * dereferencing @ptr must be assignable to @x without a cast.
 162  *
 163  * Caller must check the pointer with access_ok() before calling this
 164  * function.
 165  *
 166  * Returns zero on success, or -EFAULT on error.
 167  * On error, the variable @x is set to zero.
 168  */
 169 #define __get_user(x, ptr)                              \
 170         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 171
 172
 173 /**
 174  * __put_user: - Write a simple value into user space, with less checking.
 175  * @x:   Value to copy to user space.
 176  * @ptr: Destination address, in user space.
 177  *
 178  * Context: User context only.  This function may sleep.
 179  *
 180  * This macro copies a single simple value from kernel space to user
 181  * space.  It supports simple types like char and int, but not larger
 182  * data types like structures or arrays.
 183  *
 184  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 185  * to the result of dereferencing @ptr.
 186  *
 187  * Caller must check the pointer with access_ok() before calling this
 188  * function.
 189  *
 190  * Returns zero on success, or -EFAULT on error.
 191  */
 192 #define __put_user(x, ptr)                                              \
 193         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 194
 195 #define __put_user_nocheck(x, ptr, size)                        \
 196 ({                                                              \
 197         long __pu_err;                                          \
 198         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 199         __pu_err;                                               \
 200 })
 201
 202
 203 #define __put_user_u64(x, addr, err)                                    \
 204         asm volatile("1:        movl %%eax,0(%2)\n"                     \
 205                      "2:        movl %%edx,4(%2)\n"                     \
 206                      "3:\n"                                             \
 207                      ".section .fixup,\"ax\"\n"                         \
 208                      "4:        movl %3,%0\n"                           \
 209                      "  jmp 3b\n"                                       \
 210                      ".previous\n"                                      \
 211                      _ASM_EXTABLE(1b, 4b)                               \
 212                      _ASM_EXTABLE(2b, 4b)                               \
 213                      : "=r" (err)                                       \
 214                      : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
 215
 216 #ifdef CONFIG_X86_WP_WORKS_OK
 217
 218 #define __put_user_size(x, ptr, size, retval, errret)                   \
 219 do {                                                                    \
 220         retval = 0;                                                     \
 221         __chk_user_ptr(ptr);                                            \
 222         switch (size) {                                                 \
 223         case 1:                                                         \
 224                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 225                 break;                                                  \
 226         case 2:                                                         \
 227                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 228                 break;                                                  \
 229         case 4:                                                         \
 230                 __put_user_asm(x, ptr, retval, "l", "",  "ir", errret); \
 231                 break;                                                  \
 232         case 8:                                                         \
 233                 __put_user_u64((__typeof__(*ptr))(x), ptr, retval);     \
 234                 break;                                                  \
 235         default:                                                        \
 236                 __put_user_bad();                                       \
 237         }                                                               \
 238 } while (0)
 239
 240 #else
 241
 242 #define __put_user_size(x, ptr, size, retval, errret)                   \
 243 do {                                                                    \
 244         __typeof__(*(ptr))__pus_tmp = x;                                \
 245         retval = 0;                                                     \
 246                                                                         \
 247         if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))    \
 248                 retval = errret;                                        \
 249 } while (0)
 250
 251 #endif
 252 struct __large_struct { unsigned long buf[100]; };
 253 #define __m(x) (*(struct __large_struct __user *)(x))
 254
 255 /*
 256  * Tell gcc we read from memory instead of writing: this is because
 257  * we do not write to any memory gcc knows about, so there are no
 258  * aliasing issues.
 259  */
 260 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 261         asm volatile("1:        mov"itype" %"rtype"1,%2\n"              \
 262                      "2:\n"                                             \
 263                      ".section .fixup,\"ax\"\n"                         \
 264                      "3:        movl %3,%0\n"                           \
 265                      "  jmp 2b\n"                                       \
 266                      ".previous\n"                                      \
 267                      _ASM_EXTABLE(1b, 3b)                               \
 268                      : "=r"(err)                                        \
 269                      : ltype (x), "m" (__m(addr)), "i" (errret), "0" (err))
 270
 271
 272 #define __get_user_nocheck(x, ptr, size)                                \
 273 ({                                                                      \
 274         long __gu_err;                                                  \
 275         unsigned long __gu_val;                                         \
 276         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 277         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 278         __gu_err;                                                       \
 279 })
 280
 281 #define __get_user_size(x, ptr, size, retval, errret)                   \
 282 do {                                                                    \
 283         retval = 0;                                                     \
 284         __chk_user_ptr(ptr);                                            \
 285         switch (size) {                                                 \
 286         case 1:                                                         \
 287                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 288                 break;                                                  \
 289         case 2:                                                         \
 290                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 291                 break;                                                  \
 292         case 4:                                                         \
 293                 __get_user_asm(x, ptr, retval, "l", "", "=r", errret);  \
 294                 break;                                                  \
 295         default:                                                        \
 296                 (x) = __get_user_bad();                                 \
 297         }                                                               \
 298 } while (0)
 299
 300 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 301         asm volatile("1:        mov"itype" %2,%"rtype"1\n"              \
 302                      "2:\n"                                             \
 303                      ".section .fixup,\"ax\"\n"                         \
 304                      "3:        movl %3,%0\n"                           \
 305                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 306                      "  jmp 2b\n"                                       \
 307                      ".previous\n"                                      \
 308                      _ASM_EXTABLE(1b, 3b)                               \
 309                      : "=r" (err), ltype (x)                            \
 310                      : "m" (__m(addr)), "i" (errret), "0" (err))
 311
 312
 313 unsigned long __must_check __copy_to_user_ll
 314                 (void __user *to, const void *from, unsigned long n);
 315 unsigned long __must_check __copy_from_user_ll
 316                 (void *to, const void __user *from, unsigned long n);
 317 unsigned long __must_check __copy_from_user_ll_nozero
 318                 (void *to, const void __user *from, unsigned long n);
 319 unsigned long __must_check __copy_from_user_ll_nocache
 320                 (void *to, const void __user *from, unsigned long n);
 321 unsigned long __must_check __copy_from_user_ll_nocache_nozero
 322                 (void *to, const void __user *from, unsigned long n);
 323
 324 /**
 325  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
 326  * @to:   Destination address, in user space.
 327  * @from: Source address, in kernel space.
 328  * @n:    Number of bytes to copy.
 329  *
 330  * Context: User context only.
 331  *
 332  * Copy data from kernel space to user space.  Caller must check
 333  * the specified block with access_ok() before calling this function.
 334  * The caller should also make sure he pins the user space address
 335  * so that the we don't result in page fault and sleep.
 336  *
 337  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 338  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 339  * If a store crosses a page boundary and gets a fault, the x86 will not write
 340  * anything, so this is accurate.
 341  */
 342
 343 static __always_inline unsigned long __must_check
 344 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 345 {
 346         if (__builtin_constant_p(n)) {
 347                 unsigned long ret;
 348
 349                 switch (n) {
 350                 case 1:
 351                         __put_user_size(*(u8 *)from, (u8 __user *)to,
 352                                         1, ret, 1);
 353                         return ret;
 354                 case 2:
 355                         __put_user_size(*(u16 *)from, (u16 __user *)to,
 356                                         2, ret, 2);
 357                         return ret;
 358                 case 4:
 359                         __put_user_size(*(u32 *)from, (u32 __user *)to,
 360                                         4, ret, 4);
 361                         return ret;
 362                 }
 363         }
 364         return __copy_to_user_ll(to, from, n);
 365 }
 366
 367 /**
 368  * __copy_to_user: - Copy a block of data into user space, with less checking.
 369  * @to:   Destination address, in user space.
 370  * @from: Source address, in kernel space.
 371  * @n:    Number of bytes to copy.
 372  *
 373  * Context: User context only.  This function may sleep.
 374  *
 375  * Copy data from kernel space to user space.  Caller must check
 376  * the specified block with access_ok() before calling this function.
 377  *
 378  * Returns number of bytes that could not be copied.
 379  * On success, this will be zero.
 380  */
 381 static __always_inline unsigned long __must_check
 382 __copy_to_user(void __user *to, const void *from, unsigned long n)
 383 {
 384        might_sleep();
 385        return __copy_to_user_inatomic(to, from, n);
 386 }
 387
 388 static __always_inline unsigned long
 389 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 390 {
 391         /* Avoid zeroing the tail if the copy fails..
 392          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
 393          * but as the zeroing behaviour is only significant when n is not
 394          * constant, that shouldn't be a problem.
 395          */
 396         if (__builtin_constant_p(n)) {
 397                 unsigned long ret;
 398
 399                 switch (n) {
 400                 case 1:
 401                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 402                         return ret;
 403                 case 2:
 404                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 405                         return ret;
 406                 case 4:
 407                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 408                         return ret;
 409                 }
 410         }
 411         return __copy_from_user_ll_nozero(to, from, n);
 412 }
 413
 414 /**
 415  * __copy_from_user: - Copy a block of data from user space, with less checking.
 416  * @to:   Destination address, in kernel space.
 417  * @from: Source address, in user space.
 418  * @n:    Number of bytes to copy.
 419  *
 420  * Context: User context only.  This function may sleep.
 421  *
 422  * Copy data from user space to kernel space.  Caller must check
 423  * the specified block with access_ok() before calling this function.
 424  *
 425  * Returns number of bytes that could not be copied.
 426  * On success, this will be zero.
 427  *
 428  * If some data could not be copied, this function will pad the copied
 429  * data to the requested size using zero bytes.
 430  *
 431  * An alternate version - __copy_from_user_inatomic() - may be called from
 432  * atomic context and will fail rather than sleep.  In this case the
 433  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 434  * for explanation of why this is needed.
 435  */
 436 static __always_inline unsigned long
 437 __copy_from_user(void *to, const void __user *from, unsigned long n)
 438 {
 439         might_sleep();
 440         if (__builtin_constant_p(n)) {
 441                 unsigned long ret;
 442
 443                 switch (n) {
 444                 case 1:
 445                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 446                         return ret;
 447                 case 2:
 448                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 449                         return ret;
 450                 case 4:
 451                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 452                         return ret;
 453                 }
 454         }
 455         return __copy_from_user_ll(to, from, n);
 456 }
 457
 458 #define ARCH_HAS_NOCACHE_UACCESS
 459
 460 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 461                                 const void __user *from, unsigned long n)
 462 {
 463         might_sleep();
 464         if (__builtin_constant_p(n)) {
 465                 unsigned long ret;
 466
 467                 switch (n) {
 468                 case 1:
 469                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 470                         return ret;
 471                 case 2:
 472                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 473                         return ret;
 474                 case 4:
 475                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 476                         return ret;
 477                 }
 478         }
 479         return __copy_from_user_ll_nocache(to, from, n);
 480 }
 481
 482 static __always_inline unsigned long
 483 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 484                                   unsigned long n)
 485 {
 486        return __copy_from_user_ll_nocache_nozero(to, from, n);
 487 }
 488
 489 unsigned long __must_check copy_to_user(void __user *to,
 490                                         const void *from, unsigned long n);
 491 unsigned long __must_check copy_from_user(void *to,
 492                                           const void __user *from,
 493                                           unsigned long n);
 494 long __must_check strncpy_from_user(char *dst, const char __user *src,
 495                                     long count);
 496 long __must_check __strncpy_from_user(char *dst,
 497                                       const char __user *src, long count);
 498
 499 /**
 500  * strlen_user: - Get the size of a string in user space.
 501  * @str: The string to measure.
 502  *
 503  * Context: User context only.  This function may sleep.
 504  *
 505  * Get the size of a NUL-terminated string in user space.
 506  *
 507  * Returns the size of the string INCLUDING the terminating NUL.
 508  * On exception, returns 0.
 509  *
 510  * If there is a limit on the length of a valid string, you may wish to
 511  * consider using strnlen_user() instead.
 512  */
 513 #define strlen_user(str) strnlen_user(str, LONG_MAX)
 514
 515 long strnlen_user(const char __user *str, long n);
 516 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 517 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 518
 519 #endif /* __i386_UACCESS_H */