arch/x86/include/asm/uaccess.h

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