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 unlikely(addr > limit - size);
  55
  56         /* Arbitrary sizes? Be careful about overflow */
  57         addr += size;
  58         if (unlikely(addr < size))
  59                 return true;
  60         return unlikely(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 if pagefaults are
  78  *          enabled.
  79  *
  80  * Checks if a pointer to a block of memory in user space is valid.
  81  *
  82  * Returns true (nonzero) if the memory block may be valid, false (zero)
  83  * if it is definitely invalid.
  84  *
  85  * Note that, depending on architecture, this function probably just
  86  * checks that the pointer is in the user space range - after calling
  87  * this function, memory access functions may still return -EFAULT.
  88  */
  89 #define access_ok(type, addr, size) \
  90         likely(!__range_not_ok(addr, size, user_addr_max()))
  91
  92 /*
  93  * The exception table consists of pairs of addresses relative to the
  94  * exception table enty itself: the first is the address of an
  95  * instruction that is allowed to fault, and the second is the address
  96  * at which the program should continue.  No registers are modified,
  97  * so it is entirely up to the continuation code to figure out what to
  98  * do.
  99  *
 100  * All the routines below use bits of fixup code that are out of line
 101  * with the main instruction path.  This means when everything is well,
 102  * we don't even have to jump over them.  Further, they do not intrude
 103  * on our cache or tlb entries.
 104  */
 105
 106 struct exception_table_entry {
 107         int insn, fixup;
 108 };
 109 /* This is not the generic standard exception_table_entry format */
 110 #define ARCH_HAS_SORT_EXTABLE
 111 #define ARCH_HAS_SEARCH_EXTABLE
 112
 113 extern int fixup_exception(struct pt_regs *regs);
 114 extern int early_fixup_exception(unsigned long *ip);
 115
 116 /*
 117  * These are the main single-value transfer routines.  They automatically
 118  * use the right size if we just have the right pointer type.
 119  *
 120  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 121  * and yet we don't want to do any pointers, because that is too much
 122  * of a performance impact. Thus we have a few rather ugly macros here,
 123  * and hide all the ugliness from the user.
 124  *
 125  * The "__xxx" versions of the user access functions are versions that
 126  * do not verify the address space, that must have been done previously
 127  * with a separate "access_ok()" call (this is used when we do multiple
 128  * accesses to the same area of user memory).
 129  */
 130
 131 extern int __get_user_1(void);
 132 extern int __get_user_2(void);
 133 extern int __get_user_4(void);
 134 extern int __get_user_8(void);
 135 extern int __get_user_bad(void);
 136
 137 /*
 138  * This is a type: either unsigned long, if the argument fits into
 139  * that type, or otherwise unsigned long long.
 140  */
 141 #define __inttype(x) \
 142 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 143
 144 /**
 145  * get_user: - Get a simple variable from user space.
 146  * @x:   Variable to store result.
 147  * @ptr: Source address, in user space.
 148  *
 149  * Context: User context only. This function may sleep if pagefaults are
 150  *          enabled.
 151  *
 152  * This macro copies a single simple variable from user space to kernel
 153  * space.  It supports simple types like char and int, but not larger
 154  * data types like structures or arrays.
 155  *
 156  * @ptr must have pointer-to-simple-variable type, and the result of
 157  * dereferencing @ptr must be assignable to @x without a cast.
 158  *
 159  * Returns zero on success, or -EFAULT on error.
 160  * On error, the variable @x is set to zero.
 161  */
 162 /*
 163  * Careful: we have to cast the result to the type of the pointer
 164  * for sign reasons.
 165  *
 166  * The use of _ASM_DX as the register specifier is a bit of a
 167  * simplification, as gcc only cares about it as the starting point
 168  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 169  * (%ecx being the next register in gcc's x86 register sequence), and
 170  * %rdx on 64 bits.
 171  *
 172  * Clang/LLVM cares about the size of the register, but still wants
 173  * the base register for something that ends up being a pair.
 174  */
 175 #define get_user(x, ptr)                                                \
 176 ({                                                                      \
 177         int __ret_gu;                                                   \
 178         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 179         __chk_user_ptr(ptr);                                            \
 180         might_fault();                                                  \
 181         asm volatile("call __get_user_%P3"                              \
 182                      : "=a" (__ret_gu), "=r" (__val_gu)                 \
 183                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 184         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 185         __builtin_expect(__ret_gu, 0);                                  \
 186 })
 187
 188 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 189         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 190                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 191
 192
 193
 194 #ifdef CONFIG_X86_32
 195 #define __put_user_asm_u64(x, addr, err, errret)                        \
 196         asm volatile(ASM_STAC "\n"                                      \
 197                      "1:        movl %%eax,0(%2)\n"                     \
 198                      "2:        movl %%edx,4(%2)\n"                     \
 199                      "3: " ASM_CLAC "\n"                                \
 200                      ".section .fixup,\"ax\"\n"                         \
 201                      "4:        movl %3,%0\n"                           \
 202                      "  jmp 3b\n"                                       \
 203                      ".previous\n"                                      \
 204                      _ASM_EXTABLE(1b, 4b)                               \
 205                      _ASM_EXTABLE(2b, 4b)                               \
 206                      : "=r" (err)                                       \
 207                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 208
 209 #define __put_user_asm_ex_u64(x, addr)                                  \
 210         asm volatile(ASM_STAC "\n"                                      \
 211                      "1:        movl %%eax,0(%1)\n"                     \
 212                      "2:        movl %%edx,4(%1)\n"                     \
 213                      "3: " ASM_CLAC "\n"                                \
 214                      _ASM_EXTABLE_EX(1b, 2b)                            \
 215                      _ASM_EXTABLE_EX(2b, 3b)                            \
 216                      : : "A" (x), "r" (addr))
 217
 218 #define __put_user_x8(x, ptr, __ret_pu)                         \
 219         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 220                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 221 #else
 222 #define __put_user_asm_u64(x, ptr, retval, errret) \
 223         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 224 #define __put_user_asm_ex_u64(x, addr)  \
 225         __put_user_asm_ex(x, addr, "q", "", "er")
 226 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 227 #endif
 228
 229 extern void __put_user_bad(void);
 230
 231 /*
 232  * Strange magic calling convention: pointer in %ecx,
 233  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 234  */
 235 extern void __put_user_1(void);
 236 extern void __put_user_2(void);
 237 extern void __put_user_4(void);
 238 extern void __put_user_8(void);
 239
 240 /**
 241  * put_user: - Write a simple value into user space.
 242  * @x:   Value to copy to user space.
 243  * @ptr: Destination address, in user space.
 244  *
 245  * Context: User context only. This function may sleep if pagefaults are
 246  *          enabled.
 247  *
 248  * This macro copies a single simple value from kernel space to user
 249  * space.  It supports simple types like char and int, but not larger
 250  * data types like structures or arrays.
 251  *
 252  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 253  * to the result of dereferencing @ptr.
 254  *
 255  * Returns zero on success, or -EFAULT on error.
 256  */
 257 #define put_user(x, ptr)                                        \
 258 ({                                                              \
 259         int __ret_pu;                                           \
 260         __typeof__(*(ptr)) __pu_val;                            \
 261         __chk_user_ptr(ptr);                                    \
 262         might_fault();                                          \
 263         __pu_val = x;                                           \
 264         switch (sizeof(*(ptr))) {                               \
 265         case 1:                                                 \
 266                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 267                 break;                                          \
 268         case 2:                                                 \
 269                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 270                 break;                                          \
 271         case 4:                                                 \
 272                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 273                 break;                                          \
 274         case 8:                                                 \
 275                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 276                 break;                                          \
 277         default:                                                \
 278                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 279                 break;                                          \
 280         }                                                       \
 281         __builtin_expect(__ret_pu, 0);                          \
 282 })
 283
 284 #define __put_user_size(x, ptr, size, retval, errret)                   \
 285 do {                                                                    \
 286         retval = 0;                                                     \
 287         __chk_user_ptr(ptr);                                            \
 288         switch (size) {                                                 \
 289         case 1:                                                         \
 290                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 291                 break;                                                  \
 292         case 2:                                                         \
 293                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 294                 break;                                                  \
 295         case 4:                                                         \
 296                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 297                 break;                                                  \
 298         case 8:                                                         \
 299                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 300                                    errret);                             \
 301                 break;                                                  \
 302         default:                                                        \
 303                 __put_user_bad();                                       \
 304         }                                                               \
 305 } while (0)
 306
 307 #define __put_user_size_ex(x, ptr, size)                                \
 308 do {                                                                    \
 309         __chk_user_ptr(ptr);                                            \
 310         switch (size) {                                                 \
 311         case 1:                                                         \
 312                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 313                 break;                                                  \
 314         case 2:                                                         \
 315                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 316                 break;                                                  \
 317         case 4:                                                         \
 318                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 319                 break;                                                  \
 320         case 8:                                                         \
 321                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 322                 break;                                                  \
 323         default:                                                        \
 324                 __put_user_bad();                                       \
 325         }                                                               \
 326 } while (0)
 327
 328 #ifdef CONFIG_X86_32
 329 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 330 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 331 #else
 332 #define __get_user_asm_u64(x, ptr, retval, errret) \
 333          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 334 #define __get_user_asm_ex_u64(x, ptr) \
 335          __get_user_asm_ex(x, ptr, "q", "", "=r")
 336 #endif
 337
 338 #define __get_user_size(x, ptr, size, retval, errret)                   \
 339 do {                                                                    \
 340         retval = 0;                                                     \
 341         __chk_user_ptr(ptr);                                            \
 342         switch (size) {                                                 \
 343         case 1:                                                         \
 344                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 345                 break;                                                  \
 346         case 2:                                                         \
 347                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 348                 break;                                                  \
 349         case 4:                                                         \
 350                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 351                 break;                                                  \
 352         case 8:                                                         \
 353                 __get_user_asm_u64(x, ptr, retval, errret);             \
 354                 break;                                                  \
 355         default:                                                        \
 356                 (x) = __get_user_bad();                                 \
 357         }                                                               \
 358 } while (0)
 359
 360 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 361         asm volatile(ASM_STAC "\n"                                      \
 362                      "1:        mov"itype" %2,%"rtype"1\n"              \
 363                      "2: " ASM_CLAC "\n"                                \
 364                      ".section .fixup,\"ax\"\n"                         \
 365                      "3:        mov %3,%0\n"                            \
 366                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 367                      "  jmp 2b\n"                                       \
 368                      ".previous\n"                                      \
 369                      _ASM_EXTABLE(1b, 3b)                               \
 370                      : "=r" (err), ltype(x)                             \
 371                      : "m" (__m(addr)), "i" (errret), "0" (err))
 372
 373 #define __get_user_size_ex(x, ptr, size)                                \
 374 do {                                                                    \
 375         __chk_user_ptr(ptr);                                            \
 376         switch (size) {                                                 \
 377         case 1:                                                         \
 378                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 379                 break;                                                  \
 380         case 2:                                                         \
 381                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 382                 break;                                                  \
 383         case 4:                                                         \
 384                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 385                 break;                                                  \
 386         case 8:                                                         \
 387                 __get_user_asm_ex_u64(x, ptr);                          \
 388                 break;                                                  \
 389         default:                                                        \
 390                 (x) = __get_user_bad();                                 \
 391         }                                                               \
 392 } while (0)
 393
 394 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 395         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 396                      "2:\n"                                             \
 397                      _ASM_EXTABLE_EX(1b, 2b)                            \
 398                      : ltype(x) : "m" (__m(addr)))
 399
 400 #define __put_user_nocheck(x, ptr, size)                        \
 401 ({                                                              \
 402         int __pu_err;                                           \
 403         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 404         __builtin_expect(__pu_err, 0);                          \
 405 })
 406
 407 #define __get_user_nocheck(x, ptr, size)                                \
 408 ({                                                                      \
 409         int __gu_err;                                                   \
 410         unsigned long __gu_val;                                         \
 411         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 412         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 413         __builtin_expect(__gu_err, 0);                                  \
 414 })
 415
 416 /* FIXME: this hack is definitely wrong -AK */
 417 struct __large_struct { unsigned long buf[100]; };
 418 #define __m(x) (*(struct __large_struct __user *)(x))
 419
 420 /*
 421  * Tell gcc we read from memory instead of writing: this is because
 422  * we do not write to any memory gcc knows about, so there are no
 423  * aliasing issues.
 424  */
 425 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 426         asm volatile(ASM_STAC "\n"                                      \
 427                      "1:        mov"itype" %"rtype"1,%2\n"              \
 428                      "2: " ASM_CLAC "\n"                                \
 429                      ".section .fixup,\"ax\"\n"                         \
 430                      "3:        mov %3,%0\n"                            \
 431                      "  jmp 2b\n"                                       \
 432                      ".previous\n"                                      \
 433                      _ASM_EXTABLE(1b, 3b)                               \
 434                      : "=r"(err)                                        \
 435                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 436
 437 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 438         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 439                      "2:\n"                                             \
 440                      _ASM_EXTABLE_EX(1b, 2b)                            \
 441                      : : ltype(x), "m" (__m(addr)))
 442
 443 /*
 444  * uaccess_try and catch
 445  */
 446 #define uaccess_try     do {                                            \
 447         current_thread_info()->uaccess_err = 0;                         \
 448         stac();                                                         \
 449         barrier();
 450
 451 #define uaccess_catch(err)                                              \
 452         clac();                                                         \
 453         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 454 } while (0)
 455
 456 /**
 457  * __get_user: - Get a simple variable from user space, with less checking.
 458  * @x:   Variable to store result.
 459  * @ptr: Source address, in user space.
 460  *
 461  * Context: User context only. This function may sleep if pagefaults are
 462  *          enabled.
 463  *
 464  * This macro copies a single simple variable from user space to kernel
 465  * space.  It supports simple types like char and int, but not larger
 466  * data types like structures or arrays.
 467  *
 468  * @ptr must have pointer-to-simple-variable type, and the result of
 469  * dereferencing @ptr must be assignable to @x without a cast.
 470  *
 471  * Caller must check the pointer with access_ok() before calling this
 472  * function.
 473  *
 474  * Returns zero on success, or -EFAULT on error.
 475  * On error, the variable @x is set to zero.
 476  */
 477
 478 #define __get_user(x, ptr)                                              \
 479         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 480
 481 /**
 482  * __put_user: - Write a simple value into user space, with less checking.
 483  * @x:   Value to copy to user space.
 484  * @ptr: Destination address, in user space.
 485  *
 486  * Context: User context only. This function may sleep if pagefaults are
 487  *          enabled.
 488  *
 489  * This macro copies a single simple value from kernel space to user
 490  * space.  It supports simple types like char and int, but not larger
 491  * data types like structures or arrays.
 492  *
 493  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 494  * to the result of dereferencing @ptr.
 495  *
 496  * Caller must check the pointer with access_ok() before calling this
 497  * function.
 498  *
 499  * Returns zero on success, or -EFAULT on error.
 500  */
 501
 502 #define __put_user(x, ptr)                                              \
 503         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 504
 505 #define __get_user_unaligned __get_user
 506 #define __put_user_unaligned __put_user
 507
 508 /*
 509  * {get|put}_user_try and catch
 510  *
 511  * get_user_try {
 512  *      get_user_ex(...);
 513  * } get_user_catch(err)
 514  */
 515 #define get_user_try            uaccess_try
 516 #define get_user_catch(err)     uaccess_catch(err)
 517
 518 #define get_user_ex(x, ptr)     do {                                    \
 519         unsigned long __gue_val;                                        \
 520         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 521         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 522 } while (0)
 523
 524 #define put_user_try            uaccess_try
 525 #define put_user_catch(err)     uaccess_catch(err)
 526
 527 #define put_user_ex(x, ptr)                                             \
 528         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 529
 530 extern unsigned long
 531 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 532 extern __must_check long
 533 strncpy_from_user(char *dst, const char __user *src, long count);
 534
 535 extern __must_check long strlen_user(const char __user *str);
 536 extern __must_check long strnlen_user(const char __user *str, long n);
 537
 538 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 539 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 540
 541 extern void __cmpxchg_wrong_size(void)
 542         __compiletime_error("Bad argument size for cmpxchg");
 543
 544 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 545 ({                                                                      \
 546         int __ret = 0;                                                  \
 547         __typeof__(ptr) __uval = (uval);                                \
 548         __typeof__(*(ptr)) __old = (old);                               \
 549         __typeof__(*(ptr)) __new = (new);                               \
 550         switch (size) {                                                 \
 551         case 1:                                                         \
 552         {                                                               \
 553                 asm volatile("\t" ASM_STAC "\n"                         \
 554                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 555                         "2:\t" ASM_CLAC "\n"                            \
 556                         "\t.section .fixup, \"ax\"\n"                   \
 557                         "3:\tmov     %3, %0\n"                          \
 558                         "\tjmp     2b\n"                                \
 559                         "\t.previous\n"                                 \
 560                         _ASM_EXTABLE(1b, 3b)                            \
 561                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 562                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 563                         : "memory"                                      \
 564                 );                                                      \
 565                 break;                                                  \
 566         }                                                               \
 567         case 2:                                                         \
 568         {                                                               \
 569                 asm volatile("\t" ASM_STAC "\n"                         \
 570                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 571                         "2:\t" ASM_CLAC "\n"                            \
 572                         "\t.section .fixup, \"ax\"\n"                   \
 573                         "3:\tmov     %3, %0\n"                          \
 574                         "\tjmp     2b\n"                                \
 575                         "\t.previous\n"                                 \
 576                         _ASM_EXTABLE(1b, 3b)                            \
 577                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 578                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 579                         : "memory"                                      \
 580                 );                                                      \
 581                 break;                                                  \
 582         }                                                               \
 583         case 4:                                                         \
 584         {                                                               \
 585                 asm volatile("\t" ASM_STAC "\n"                         \
 586                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 587                         "2:\t" ASM_CLAC "\n"                            \
 588                         "\t.section .fixup, \"ax\"\n"                   \
 589                         "3:\tmov     %3, %0\n"                          \
 590                         "\tjmp     2b\n"                                \
 591                         "\t.previous\n"                                 \
 592                         _ASM_EXTABLE(1b, 3b)                            \
 593                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 594                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 595                         : "memory"                                      \
 596                 );                                                      \
 597                 break;                                                  \
 598         }                                                               \
 599         case 8:                                                         \
 600         {                                                               \
 601                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 602                         __cmpxchg_wrong_size();                         \
 603                                                                         \
 604                 asm volatile("\t" ASM_STAC "\n"                         \
 605                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 606                         "2:\t" ASM_CLAC "\n"                            \
 607                         "\t.section .fixup, \"ax\"\n"                   \
 608                         "3:\tmov     %3, %0\n"                          \
 609                         "\tjmp     2b\n"                                \
 610                         "\t.previous\n"                                 \
 611                         _ASM_EXTABLE(1b, 3b)                            \
 612                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 613                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 614                         : "memory"                                      \
 615                 );                                                      \
 616                 break;                                                  \
 617         }                                                               \
 618         default:                                                        \
 619                 __cmpxchg_wrong_size();                                 \
 620         }                                                               \
 621         *__uval = __old;                                                \
 622         __ret;                                                          \
 623 })
 624
 625 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 626 ({                                                                      \
 627         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 628                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 629                                 (old), (new), sizeof(*(ptr))) :         \
 630                 -EFAULT;                                                \
 631 })
 632
 633 /*
 634  * movsl can be slow when source and dest are not both 8-byte aligned
 635  */
 636 #ifdef CONFIG_X86_INTEL_USERCOPY
 637 extern struct movsl_mask {
 638         int mask;
 639 } ____cacheline_aligned_in_smp movsl_mask;
 640 #endif
 641
 642 #define ARCH_HAS_NOCACHE_UACCESS 1
 643
 644 #ifdef CONFIG_X86_32
 645 # include <asm/uaccess_32.h>
 646 #else
 647 # include <asm/uaccess_64.h>
 648 #endif
 649
 650 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 651                                            unsigned n);
 652 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 653                                          unsigned n);
 654
 655 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 656 # define copy_user_diag __compiletime_error
 657 #else
 658 # define copy_user_diag __compiletime_warning
 659 #endif
 660
 661 extern void copy_user_diag("copy_from_user() buffer size is too small")
 662 copy_from_user_overflow(void);
 663 extern void copy_user_diag("copy_to_user() buffer size is too small")
 664 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 665
 666 #undef copy_user_diag
 667
 668 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 669
 670 extern void
 671 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 672 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
 673 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
 674
 675 extern void
 676 __compiletime_warning("copy_to_user() buffer size is not provably correct")
 677 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 678 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
 679
 680 #else
 681
 682 static inline void
 683 __copy_from_user_overflow(int size, unsigned long count)
 684 {
 685         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 686 }
 687
 688 #define __copy_to_user_overflow __copy_from_user_overflow
 689
 690 #endif
 691
 692 static inline unsigned long __must_check
 693 copy_from_user(void *to, const void __user *from, unsigned long n)
 694 {
 695         int sz = __compiletime_object_size(to);
 696
 697         might_fault();
 698
 699         /*
 700          * While we would like to have the compiler do the checking for us
 701          * even in the non-constant size case, any false positives there are
 702          * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
 703          * without - the [hopefully] dangerous looking nature of the warning
 704          * would make people go look at the respecitive call sites over and
 705          * over again just to find that there's no problem).
 706          *
 707          * And there are cases where it's just not realistic for the compiler
 708          * to prove the count to be in range. For example when multiple call
 709          * sites of a helper function - perhaps in different source files -
 710          * all doing proper range checking, yet the helper function not doing
 711          * so again.
 712          *
 713          * Therefore limit the compile time checking to the constant size
 714          * case, and do only runtime checking for non-constant sizes.
 715          */
 716
 717         if (likely(sz < 0 || sz >= n))
 718                 n = _copy_from_user(to, from, n);
 719         else if(__builtin_constant_p(n))
 720                 copy_from_user_overflow();
 721         else
 722                 __copy_from_user_overflow(sz, n);
 723
 724         return n;
 725 }
 726
 727 static inline unsigned long __must_check
 728 copy_to_user(void __user *to, const void *from, unsigned long n)
 729 {
 730         int sz = __compiletime_object_size(from);
 731
 732         might_fault();
 733
 734         /* See the comment in copy_from_user() above. */
 735         if (likely(sz < 0 || sz >= n))
 736                 n = _copy_to_user(to, from, n);
 737         else if(__builtin_constant_p(n))
 738                 copy_to_user_overflow();
 739         else
 740                 __copy_to_user_overflow(sz, n);
 741
 742         return n;
 743 }
 744
 745 #undef __copy_from_user_overflow
 746 #undef __copy_to_user_overflow
 747
 748 /*
 749  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 750  * nested NMI paths are careful to preserve CR2.
 751  *
 752  * Caller must use pagefault_enable/disable, or run in interrupt context,
 753  * and also do a uaccess_ok() check
 754  */
 755 #define __copy_from_user_nmi __copy_from_user_inatomic
 756
 757 #endif /* _ASM_X86_UACCESS_H */
 758