arch/x86/include/asm/uaccess.h

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