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 #include <asm/smap.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 user_addr_max() (current_thread_info()->addr_limit.seg)
  37 #define __addr_ok(addr)         \
  38         ((unsigned long __force)(addr) < user_addr_max())
  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 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  45 {
  46         /*
  47          * If we have used "sizeof()" for the size,
  48          * we know it won't overflow the limit (but
  49          * it might overflow the 'addr', so it's
  50          * important to subtract the size from the
  51          * limit, not add it to the address).
  52          */
  53         if (__builtin_constant_p(size))
  54                 return addr > limit - size;
  55
  56         /* Arbitrary sizes? Be careful about overflow */
  57         addr += size;
  58         if (addr < size)
  59                 return true;
  60         return addr > limit;
  61 }
  62
  63 #define __range_not_ok(addr, size, limit)                               \
  64 ({                                                                      \
  65         __chk_user_ptr(addr);                                           \
  66         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  67 })
  68
  69 /**
  70  * access_ok: - Checks if a user space pointer is valid
  71  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  72  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  73  *        to write to a block, it is always safe to read from it.
  74  * @addr: User space pointer to start of block to check
  75  * @size: Size of block to check
  76  *
  77  * Context: User context only.  This function may sleep.
  78  *
  79  * Checks if a pointer to a block of memory in user space is valid.
  80  *
  81  * Returns true (nonzero) if the memory block may be valid, false (zero)
  82  * if it is definitely invalid.
  83  *
  84  * Note that, depending on architecture, this function probably just
  85  * checks that the pointer is in the user space range - after calling
  86  * this function, memory access functions may still return -EFAULT.
  87  */
  88 #define access_ok(type, addr, size) \
  89         likely(!__range_not_ok(addr, size, user_addr_max()))
  90
  91 /*
  92  * The exception table consists of pairs of addresses relative to the
  93  * exception table enty itself: the first is the address of an
  94  * instruction that is allowed to fault, and the second is the address
  95  * at which the program should continue.  No registers are modified,
  96  * so it is entirely up to the continuation code to figure out what to
  97  * do.
  98  *
  99  * All the routines below use bits of fixup code that are out of line
 100  * with the main instruction path.  This means when everything is well,
 101  * we don't even have to jump over them.  Further, they do not intrude
 102  * on our cache or tlb entries.
 103  */
 104
 105 struct exception_table_entry {
 106         int insn, fixup;
 107 };
 108 /* This is not the generic standard exception_table_entry format */
 109 #define ARCH_HAS_SORT_EXTABLE
 110 #define ARCH_HAS_SEARCH_EXTABLE
 111
 112 extern int fixup_exception(struct pt_regs *regs);
 113 extern int early_fixup_exception(unsigned long *ip);
 114
 115 /*
 116  * These are the main single-value transfer routines.  They automatically
 117  * use the right size if we just have the right pointer type.
 118  *
 119  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 120  * and yet we don't want to do any pointers, because that is too much
 121  * of a performance impact. Thus we have a few rather ugly macros here,
 122  * and hide all the ugliness from the user.
 123  *
 124  * The "__xxx" versions of the user access functions are versions that
 125  * do not verify the address space, that must have been done previously
 126  * with a separate "access_ok()" call (this is used when we do multiple
 127  * accesses to the same area of user memory).
 128  */
 129
 130 extern int __get_user_1(void);
 131 extern int __get_user_2(void);
 132 extern int __get_user_4(void);
 133 extern int __get_user_8(void);
 134 extern int __get_user_bad(void);
 135
 136 /*
 137  * This is a type: either unsigned long, if the argument fits into
 138  * that type, or otherwise unsigned long long.
 139  */
 140 #define __inttype(x) \
 141 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 142
 143 /**
 144  * get_user: - Get a simple variable from user space.
 145  * @x:   Variable to store result.
 146  * @ptr: Source address, in user space.
 147  *
 148  * Context: User context only.  This function may sleep.
 149  *
 150  * This macro copies a single simple variable from user space to kernel
 151  * space.  It supports simple types like char and int, but not larger
 152  * data types like structures or arrays.
 153  *
 154  * @ptr must have pointer-to-simple-variable type, and the result of
 155  * dereferencing @ptr must be assignable to @x without a cast.
 156  *
 157  * Returns zero on success, or -EFAULT on error.
 158  * On error, the variable @x is set to zero.
 159  */
 160 /*
 161  * Careful: we have to cast the result to the type of the pointer
 162  * for sign reasons.
 163  *
 164  * The use of _ASM_DX as the register specifier is a bit of a
 165  * simplification, as gcc only cares about it as the starting point
 166  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 167  * (%ecx being the next register in gcc's x86 register sequence), and
 168  * %rdx on 64 bits.
 169  *
 170  * Clang/LLVM cares about the size of the register, but still wants
 171  * the base register for something that ends up being a pair.
 172  */
 173 #define get_user(x, ptr)                                                \
 174 ({                                                                      \
 175         int __ret_gu;                                                   \
 176         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 177         __chk_user_ptr(ptr);                                            \
 178         might_fault();                                                  \
 179         asm volatile("call __get_user_%P3"                              \
 180                      : "=a" (__ret_gu), "=r" (__val_gu)                 \
 181                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 182         (x) = (__typeof__(*(ptr))) __val_gu;                            \
 183         __ret_gu;                                                       \
 184 })
 185
 186 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 187         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 188                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 189
 190
 191
 192 #ifdef CONFIG_X86_32
 193 #define __put_user_asm_u64(x, addr, err, errret)                        \
 194         asm volatile(ASM_STAC "\n"                                      \
 195                      "1:        movl %%eax,0(%2)\n"                     \
 196                      "2:        movl %%edx,4(%2)\n"                     \
 197                      "3: " ASM_CLAC "\n"                                \
 198                      ".section .fixup,\"ax\"\n"                         \
 199                      "4:        movl %3,%0\n"                           \
 200                      "  jmp 3b\n"                                       \
 201                      ".previous\n"                                      \
 202                      _ASM_EXTABLE(1b, 4b)                               \
 203                      _ASM_EXTABLE(2b, 4b)                               \
 204                      : "=r" (err)                                       \
 205                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 206
 207 #define __put_user_asm_ex_u64(x, addr)                                  \
 208         asm volatile(ASM_STAC "\n"                                      \
 209                      "1:        movl %%eax,0(%1)\n"                     \
 210                      "2:        movl %%edx,4(%1)\n"                     \
 211                      "3: " ASM_CLAC "\n"                                \
 212                      _ASM_EXTABLE_EX(1b, 2b)                            \
 213                      _ASM_EXTABLE_EX(2b, 3b)                            \
 214                      : : "A" (x), "r" (addr))
 215
 216 #define __put_user_x8(x, ptr, __ret_pu)                         \
 217         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 218                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 219 #else
 220 #define __put_user_asm_u64(x, ptr, retval, errret) \
 221         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 222 #define __put_user_asm_ex_u64(x, addr)  \
 223         __put_user_asm_ex(x, addr, "q", "", "er")
 224 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 225 #endif
 226
 227 extern void __put_user_bad(void);
 228
 229 /*
 230  * Strange magic calling convention: pointer in %ecx,
 231  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 232  */
 233 extern void __put_user_1(void);
 234 extern void __put_user_2(void);
 235 extern void __put_user_4(void);
 236 extern void __put_user_8(void);
 237
 238 /**
 239  * put_user: - Write a simple value into user space.
 240  * @x:   Value to copy to user space.
 241  * @ptr: Destination address, in user space.
 242  *
 243  * Context: User context only.  This function may sleep.
 244  *
 245  * This macro copies a single simple value from kernel space to user
 246  * space.  It supports simple types like char and int, but not larger
 247  * data types like structures or arrays.
 248  *
 249  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 250  * to the result of dereferencing @ptr.
 251  *
 252  * Returns zero on success, or -EFAULT on error.
 253  */
 254 #define put_user(x, ptr)                                        \
 255 ({                                                              \
 256         int __ret_pu;                                           \
 257         __typeof__(*(ptr)) __pu_val;                            \
 258         __chk_user_ptr(ptr);                                    \
 259         might_fault();                                          \
 260         __pu_val = x;                                           \
 261         switch (sizeof(*(ptr))) {                               \
 262         case 1:                                                 \
 263                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 264                 break;                                          \
 265         case 2:                                                 \
 266                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 267                 break;                                          \
 268         case 4:                                                 \
 269                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 270                 break;                                          \
 271         case 8:                                                 \
 272                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 273                 break;                                          \
 274         default:                                                \
 275                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 276                 break;                                          \
 277         }                                                       \
 278         __ret_pu;                                               \
 279 })
 280
 281 #define __put_user_size(x, ptr, size, retval, errret)                   \
 282 do {                                                                    \
 283         retval = 0;                                                     \
 284         __chk_user_ptr(ptr);                                            \
 285         switch (size) {                                                 \
 286         case 1:                                                         \
 287                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 288                 break;                                                  \
 289         case 2:                                                         \
 290                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 291                 break;                                                  \
 292         case 4:                                                         \
 293                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 294                 break;                                                  \
 295         case 8:                                                         \
 296                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 297                                    errret);                             \
 298                 break;                                                  \
 299         default:                                                        \
 300                 __put_user_bad();                                       \
 301         }                                                               \
 302 } while (0)
 303
 304 #define __put_user_size_ex(x, ptr, size)                                \
 305 do {                                                                    \
 306         __chk_user_ptr(ptr);                                            \
 307         switch (size) {                                                 \
 308         case 1:                                                         \
 309                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 310                 break;                                                  \
 311         case 2:                                                         \
 312                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 313                 break;                                                  \
 314         case 4:                                                         \
 315                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 316                 break;                                                  \
 317         case 8:                                                         \
 318                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 319                 break;                                                  \
 320         default:                                                        \
 321                 __put_user_bad();                                       \
 322         }                                                               \
 323 } while (0)
 324
 325 #ifdef CONFIG_X86_32
 326 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 327 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 328 #else
 329 #define __get_user_asm_u64(x, ptr, retval, errret) \
 330          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 331 #define __get_user_asm_ex_u64(x, ptr) \
 332          __get_user_asm_ex(x, ptr, "q", "", "=r")
 333 #endif
 334
 335 #define __get_user_size(x, ptr, size, retval, errret)                   \
 336 do {                                                                    \
 337         retval = 0;                                                     \
 338         __chk_user_ptr(ptr);                                            \
 339         switch (size) {                                                 \
 340         case 1:                                                         \
 341                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 342                 break;                                                  \
 343         case 2:                                                         \
 344                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 345                 break;                                                  \
 346         case 4:                                                         \
 347                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 348                 break;                                                  \
 349         case 8:                                                         \
 350                 __get_user_asm_u64(x, ptr, retval, errret);             \
 351                 break;                                                  \
 352         default:                                                        \
 353                 (x) = __get_user_bad();                                 \
 354         }                                                               \
 355 } while (0)
 356
 357 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 358         asm volatile(ASM_STAC "\n"                                      \
 359                      "1:        mov"itype" %2,%"rtype"1\n"              \
 360                      "2: " ASM_CLAC "\n"                                \
 361                      ".section .fixup,\"ax\"\n"                         \
 362                      "3:        mov %3,%0\n"                            \
 363                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 364                      "  jmp 2b\n"                                       \
 365                      ".previous\n"                                      \
 366                      _ASM_EXTABLE(1b, 3b)                               \
 367                      : "=r" (err), ltype(x)                             \
 368                      : "m" (__m(addr)), "i" (errret), "0" (err))
 369
 370 #define __get_user_size_ex(x, ptr, size)                                \
 371 do {                                                                    \
 372         __chk_user_ptr(ptr);                                            \
 373         switch (size) {                                                 \
 374         case 1:                                                         \
 375                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 376                 break;                                                  \
 377         case 2:                                                         \
 378                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 379                 break;                                                  \
 380         case 4:                                                         \
 381                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 382                 break;                                                  \
 383         case 8:                                                         \
 384                 __get_user_asm_ex_u64(x, ptr);                          \
 385                 break;                                                  \
 386         default:                                                        \
 387                 (x) = __get_user_bad();                                 \
 388         }                                                               \
 389 } while (0)
 390
 391 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 392         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 393                      "2:\n"                                             \
 394                      _ASM_EXTABLE_EX(1b, 2b)                            \
 395                      : ltype(x) : "m" (__m(addr)))
 396
 397 #define __put_user_nocheck(x, ptr, size)                        \
 398 ({                                                              \
 399         int __pu_err;                                           \
 400         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 401         __pu_err;                                               \
 402 })
 403
 404 #define __get_user_nocheck(x, ptr, size)                                \
 405 ({                                                                      \
 406         int __gu_err;                                                   \
 407         unsigned long __gu_val;                                         \
 408         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 409         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 410         __gu_err;                                                       \
 411 })
 412
 413 /* FIXME: this hack is definitely wrong -AK */
 414 struct __large_struct { unsigned long buf[100]; };
 415 #define __m(x) (*(struct __large_struct __user *)(x))
 416
 417 /*
 418  * Tell gcc we read from memory instead of writing: this is because
 419  * we do not write to any memory gcc knows about, so there are no
 420  * aliasing issues.
 421  */
 422 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 423         asm volatile(ASM_STAC "\n"                                      \
 424                      "1:        mov"itype" %"rtype"1,%2\n"              \
 425                      "2: " ASM_CLAC "\n"                                \
 426                      ".section .fixup,\"ax\"\n"                         \
 427                      "3:        mov %3,%0\n"                            \
 428                      "  jmp 2b\n"                                       \
 429                      ".previous\n"                                      \
 430                      _ASM_EXTABLE(1b, 3b)                               \
 431                      : "=r"(err)                                        \
 432                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 433
 434 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 435         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 436                      "2:\n"                                             \
 437                      _ASM_EXTABLE_EX(1b, 2b)                            \
 438                      : : ltype(x), "m" (__m(addr)))
 439
 440 /*
 441  * uaccess_try and catch
 442  */
 443 #define uaccess_try     do {                                            \
 444         current_thread_info()->uaccess_err = 0;                         \
 445         stac();                                                         \
 446         barrier();
 447
 448 #define uaccess_catch(err)                                              \
 449         clac();                                                         \
 450         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 451 } while (0)
 452
 453 /**
 454  * __get_user: - Get a simple variable from user space, with less checking.
 455  * @x:   Variable to store result.
 456  * @ptr: Source address, in user space.
 457  *
 458  * Context: User context only.  This function may sleep.
 459  *
 460  * This macro copies a single simple variable from user space to kernel
 461  * space.  It supports simple types like char and int, but not larger
 462  * data types like structures or arrays.
 463  *
 464  * @ptr must have pointer-to-simple-variable type, and the result of
 465  * dereferencing @ptr must be assignable to @x without a cast.
 466  *
 467  * Caller must check the pointer with access_ok() before calling this
 468  * function.
 469  *
 470  * Returns zero on success, or -EFAULT on error.
 471  * On error, the variable @x is set to zero.
 472  */
 473
 474 #define __get_user(x, ptr)                                              \
 475         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 476
 477 /**
 478  * __put_user: - Write a simple value into user space, with less checking.
 479  * @x:   Value to copy to user space.
 480  * @ptr: Destination address, in user space.
 481  *
 482  * Context: User context only.  This function may sleep.
 483  *
 484  * This macro copies a single simple value from kernel space to user
 485  * space.  It supports simple types like char and int, but not larger
 486  * data types like structures or arrays.
 487  *
 488  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 489  * to the result of dereferencing @ptr.
 490  *
 491  * Caller must check the pointer with access_ok() before calling this
 492  * function.
 493  *
 494  * Returns zero on success, or -EFAULT on error.
 495  */
 496
 497 #define __put_user(x, ptr)                                              \
 498         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 499
 500 #define __get_user_unaligned __get_user
 501 #define __put_user_unaligned __put_user
 502
 503 /*
 504  * {get|put}_user_try and catch
 505  *
 506  * get_user_try {
 507  *      get_user_ex(...);
 508  * } get_user_catch(err)
 509  */
 510 #define get_user_try            uaccess_try
 511 #define get_user_catch(err)     uaccess_catch(err)
 512
 513 #define get_user_ex(x, ptr)     do {                                    \
 514         unsigned long __gue_val;                                        \
 515         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 516         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 517 } while (0)
 518
 519 #define put_user_try            uaccess_try
 520 #define put_user_catch(err)     uaccess_catch(err)
 521
 522 #define put_user_ex(x, ptr)                                             \
 523         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 524
 525 extern unsigned long
 526 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 527 extern __must_check long
 528 strncpy_from_user(char *dst, const char __user *src, long count);
 529
 530 extern __must_check long strlen_user(const char __user *str);
 531 extern __must_check long strnlen_user(const char __user *str, long n);
 532
 533 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 534 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 535
 536 extern void __cmpxchg_wrong_size(void)
 537         __compiletime_error("Bad argument size for cmpxchg");
 538
 539 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 540 ({                                                                      \
 541         int __ret = 0;                                                  \
 542         __typeof__(ptr) __uval = (uval);                                \
 543         __typeof__(*(ptr)) __old = (old);                               \
 544         __typeof__(*(ptr)) __new = (new);                               \
 545         switch (size) {                                                 \
 546         case 1:                                                         \
 547         {                                                               \
 548                 asm volatile("\t" ASM_STAC "\n"                         \
 549                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 550                         "2:\t" ASM_CLAC "\n"                            \
 551                         "\t.section .fixup, \"ax\"\n"                   \
 552                         "3:\tmov     %3, %0\n"                          \
 553                         "\tjmp     2b\n"                                \
 554                         "\t.previous\n"                                 \
 555                         _ASM_EXTABLE(1b, 3b)                            \
 556                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 557                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 558                         : "memory"                                      \
 559                 );                                                      \
 560                 break;                                                  \
 561         }                                                               \
 562         case 2:                                                         \
 563         {                                                               \
 564                 asm volatile("\t" ASM_STAC "\n"                         \
 565                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 566                         "2:\t" ASM_CLAC "\n"                            \
 567                         "\t.section .fixup, \"ax\"\n"                   \
 568                         "3:\tmov     %3, %0\n"                          \
 569                         "\tjmp     2b\n"                                \
 570                         "\t.previous\n"                                 \
 571                         _ASM_EXTABLE(1b, 3b)                            \
 572                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 573                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 574                         : "memory"                                      \
 575                 );                                                      \
 576                 break;                                                  \
 577         }                                                               \
 578         case 4:                                                         \
 579         {                                                               \
 580                 asm volatile("\t" ASM_STAC "\n"                         \
 581                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 582                         "2:\t" ASM_CLAC "\n"                            \
 583                         "\t.section .fixup, \"ax\"\n"                   \
 584                         "3:\tmov     %3, %0\n"                          \
 585                         "\tjmp     2b\n"                                \
 586                         "\t.previous\n"                                 \
 587                         _ASM_EXTABLE(1b, 3b)                            \
 588                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 589                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 590                         : "memory"                                      \
 591                 );                                                      \
 592                 break;                                                  \
 593         }                                                               \
 594         case 8:                                                         \
 595         {                                                               \
 596                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 597                         __cmpxchg_wrong_size();                         \
 598                                                                         \
 599                 asm volatile("\t" ASM_STAC "\n"                         \
 600                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 601                         "2:\t" ASM_CLAC "\n"                            \
 602                         "\t.section .fixup, \"ax\"\n"                   \
 603                         "3:\tmov     %3, %0\n"                          \
 604                         "\tjmp     2b\n"                                \
 605                         "\t.previous\n"                                 \
 606                         _ASM_EXTABLE(1b, 3b)                            \
 607                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 608                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 609                         : "memory"                                      \
 610                 );                                                      \
 611                 break;                                                  \
 612         }                                                               \
 613         default:                                                        \
 614                 __cmpxchg_wrong_size();                                 \
 615         }                                                               \
 616         *__uval = __old;                                                \
 617         __ret;                                                          \
 618 })
 619
 620 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 621 ({                                                                      \
 622         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 623                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 624                                 (old), (new), sizeof(*(ptr))) :         \
 625                 -EFAULT;                                                \
 626 })
 627
 628 /*
 629  * movsl can be slow when source and dest are not both 8-byte aligned
 630  */
 631 #ifdef CONFIG_X86_INTEL_USERCOPY
 632 extern struct movsl_mask {
 633         int mask;
 634 } ____cacheline_aligned_in_smp movsl_mask;
 635 #endif
 636
 637 #define ARCH_HAS_NOCACHE_UACCESS 1
 638
 639 #ifdef CONFIG_X86_32
 640 # include <asm/uaccess_32.h>
 641 #else
 642 # include <asm/uaccess_64.h>
 643 #endif
 644
 645 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 646                                            unsigned n);
 647 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 648                                          unsigned n);
 649
 650 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 651 # define copy_user_diag __compiletime_error
 652 #else
 653 # define copy_user_diag __compiletime_warning
 654 #endif
 655
 656 extern void copy_user_diag("copy_from_user() buffer size is too small")
 657 copy_from_user_overflow(void);
 658 extern void copy_user_diag("copy_to_user() buffer size is too small")
 659 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 660
 661 #undef copy_user_diag
 662
 663 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 664
 665 extern void
 666 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 667 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
 668 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
 669
 670 extern void
 671 __compiletime_warning("copy_to_user() buffer size is not provably correct")
 672 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 673 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
 674
 675 #else
 676
 677 static inline void
 678 __copy_from_user_overflow(int size, unsigned long count)
 679 {
 680         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 681 }
 682
 683 #define __copy_to_user_overflow __copy_from_user_overflow
 684
 685 #endif
 686
 687 static inline unsigned long __must_check
 688 copy_from_user(void *to, const void __user *from, unsigned long n)
 689 {
 690         int sz = __compiletime_object_size(to);
 691
 692         might_fault();
 693
 694         /*
 695          * While we would like to have the compiler do the checking for us
 696          * even in the non-constant size case, any false positives there are
 697          * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
 698          * without - the [hopefully] dangerous looking nature of the warning
 699          * would make people go look at the respecitive call sites over and
 700          * over again just to find that there's no problem).
 701          *
 702          * And there are cases where it's just not realistic for the compiler
 703          * to prove the count to be in range. For example when multiple call
 704          * sites of a helper function - perhaps in different source files -
 705          * all doing proper range checking, yet the helper function not doing
 706          * so again.
 707          *
 708          * Therefore limit the compile time checking to the constant size
 709          * case, and do only runtime checking for non-constant sizes.
 710          */
 711
 712         if (likely(sz < 0 || sz >= n))
 713                 n = _copy_from_user(to, from, n);
 714         else if(__builtin_constant_p(n))
 715                 copy_from_user_overflow();
 716         else
 717                 __copy_from_user_overflow(sz, n);
 718
 719         return n;
 720 }
 721
 722 static inline unsigned long __must_check
 723 copy_to_user(void __user *to, const void *from, unsigned long n)
 724 {
 725         int sz = __compiletime_object_size(from);
 726
 727         might_fault();
 728
 729         /* See the comment in copy_from_user() above. */
 730         if (likely(sz < 0 || sz >= n))
 731                 n = _copy_to_user(to, from, n);
 732         else if(__builtin_constant_p(n))
 733                 copy_to_user_overflow();
 734         else
 735                 __copy_to_user_overflow(sz, n);
 736
 737         return n;
 738 }
 739
 740 #undef __copy_from_user_overflow
 741 #undef __copy_to_user_overflow
 742
 743 #endif /* _ASM_X86_UACCESS_H */
 744