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/compiler.h>
   7 #include <linux/kasan-checks.h>
   8 #include <linux/string.h>
   9 #include <asm/asm.h>
  10 #include <asm/page.h>
  11 #include <asm/smap.h>
  12 #include <asm/extable.h>
  13
  14 /*
  15  * The fs value determines whether argument validity checking should be
  16  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  17  * get_fs() == KERNEL_DS, checking is bypassed.
  18  *
  19  * For historical reasons, these macros are grossly misnamed.
  20  */
  21
  22 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  23
  24 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  25 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  26
  27 #define get_ds()        (KERNEL_DS)
  28 #define get_fs()        (current->thread.addr_limit)
  29 #define set_fs(x)       (current->thread.addr_limit = (x))
  30
  31 #define segment_eq(a, b)        ((a).seg == (b).seg)
  32
  33 #define user_addr_max() (current->thread.addr_limit.seg)
  34 #define __addr_ok(addr)         \
  35         ((unsigned long __force)(addr) < user_addr_max())
  36
  37 /*
  38  * Test whether a block of memory is a valid user space address.
  39  * Returns 0 if the range is valid, nonzero otherwise.
  40  */
  41 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  42 {
  43         /*
  44          * If we have used "sizeof()" for the size,
  45          * we know it won't overflow the limit (but
  46          * it might overflow the 'addr', so it's
  47          * important to subtract the size from the
  48          * limit, not add it to the address).
  49          */
  50         if (__builtin_constant_p(size))
  51                 return unlikely(addr > limit - size);
  52
  53         /* Arbitrary sizes? Be careful about overflow */
  54         addr += size;
  55         if (unlikely(addr < size))
  56                 return true;
  57         return unlikely(addr > limit);
  58 }
  59
  60 #define __range_not_ok(addr, size, limit)                               \
  61 ({                                                                      \
  62         __chk_user_ptr(addr);                                           \
  63         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  64 })
  65
  66 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  67 # define WARN_ON_IN_IRQ()       WARN_ON_ONCE(!in_task())
  68 #else
  69 # define WARN_ON_IN_IRQ()
  70 #endif
  71
  72 /**
  73  * access_ok: - Checks if a user space pointer is valid
  74  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  75  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  76  *        to write to a block, it is always safe to read from it.
  77  * @addr: User space pointer to start of block to check
  78  * @size: Size of block to check
  79  *
  80  * Context: User context only. This function may sleep if pagefaults are
  81  *          enabled.
  82  *
  83  * Checks if a pointer to a block of memory in user space is valid.
  84  *
  85  * Returns true (nonzero) if the memory block may be valid, false (zero)
  86  * if it is definitely invalid.
  87  *
  88  * Note that, depending on architecture, this function probably just
  89  * checks that the pointer is in the user space range - after calling
  90  * this function, memory access functions may still return -EFAULT.
  91  */
  92 #define access_ok(type, addr, size)                                     \
  93 ({                                                                      \
  94         WARN_ON_IN_IRQ();                                               \
  95         likely(!__range_not_ok(addr, size, user_addr_max()));           \
  96 })
  97
  98 /*
  99  * These are the main single-value transfer routines.  They automatically
 100  * use the right size if we just have the right pointer type.
 101  *
 102  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 103  * and yet we don't want to do any pointers, because that is too much
 104  * of a performance impact. Thus we have a few rather ugly macros here,
 105  * and hide all the ugliness from the user.
 106  *
 107  * The "__xxx" versions of the user access functions are versions that
 108  * do not verify the address space, that must have been done previously
 109  * with a separate "access_ok()" call (this is used when we do multiple
 110  * accesses to the same area of user memory).
 111  */
 112
 113 extern int __get_user_1(void);
 114 extern int __get_user_2(void);
 115 extern int __get_user_4(void);
 116 extern int __get_user_8(void);
 117 extern int __get_user_bad(void);
 118
 119 #define __uaccess_begin() stac()
 120 #define __uaccess_end()   clac()
 121
 122 /*
 123  * This is a type: either unsigned long, if the argument fits into
 124  * that type, or otherwise unsigned long long.
 125  */
 126 #define __inttype(x) \
 127 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 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 if pagefaults are
 135  *          enabled.
 136  *
 137  * This macro copies a single simple variable from user space to kernel
 138  * space.  It supports simple types like char and int, but not larger
 139  * data types like structures or arrays.
 140  *
 141  * @ptr must have pointer-to-simple-variable type, and the result of
 142  * dereferencing @ptr must be assignable to @x without a cast.
 143  *
 144  * Returns zero on success, or -EFAULT on error.
 145  * On error, the variable @x is set to zero.
 146  */
 147 /*
 148  * Careful: we have to cast the result to the type of the pointer
 149  * for sign reasons.
 150  *
 151  * The use of _ASM_DX as the register specifier is a bit of a
 152  * simplification, as gcc only cares about it as the starting point
 153  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 154  * (%ecx being the next register in gcc's x86 register sequence), and
 155  * %rdx on 64 bits.
 156  *
 157  * Clang/LLVM cares about the size of the register, but still wants
 158  * the base register for something that ends up being a pair.
 159  */
 160 #define get_user(x, ptr)                                                \
 161 ({                                                                      \
 162         int __ret_gu;                                                   \
 163         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 164         register void *__sp asm(_ASM_SP);                               \
 165         __chk_user_ptr(ptr);                                            \
 166         might_fault();                                                  \
 167         asm volatile("call __get_user_%P4"                              \
 168                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 169                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 170         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 171         __builtin_expect(__ret_gu, 0);                                  \
 172 })
 173
 174 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 175         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 176                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 177
 178
 179
 180 #ifdef CONFIG_X86_32
 181 #define __put_user_asm_u64(x, addr, err, errret)                        \
 182         asm volatile("\n"                                               \
 183                      "1:        movl %%eax,0(%2)\n"                     \
 184                      "2:        movl %%edx,4(%2)\n"                     \
 185                      "3:"                                               \
 186                      ".section .fixup,\"ax\"\n"                         \
 187                      "4:        movl %3,%0\n"                           \
 188                      "  jmp 3b\n"                                       \
 189                      ".previous\n"                                      \
 190                      _ASM_EXTABLE(1b, 4b)                               \
 191                      _ASM_EXTABLE(2b, 4b)                               \
 192                      : "=r" (err)                                       \
 193                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 194
 195 #define __put_user_asm_ex_u64(x, addr)                                  \
 196         asm volatile("\n"                                               \
 197                      "1:        movl %%eax,0(%1)\n"                     \
 198                      "2:        movl %%edx,4(%1)\n"                     \
 199                      "3:"                                               \
 200                      _ASM_EXTABLE_EX(1b, 2b)                            \
 201                      _ASM_EXTABLE_EX(2b, 3b)                            \
 202                      : : "A" (x), "r" (addr))
 203
 204 #define __put_user_x8(x, ptr, __ret_pu)                         \
 205         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 206                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 207 #else
 208 #define __put_user_asm_u64(x, ptr, retval, errret) \
 209         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 210 #define __put_user_asm_ex_u64(x, addr)  \
 211         __put_user_asm_ex(x, addr, "q", "", "er")
 212 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 213 #endif
 214
 215 extern void __put_user_bad(void);
 216
 217 /*
 218  * Strange magic calling convention: pointer in %ecx,
 219  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 220  */
 221 extern void __put_user_1(void);
 222 extern void __put_user_2(void);
 223 extern void __put_user_4(void);
 224 extern void __put_user_8(void);
 225
 226 /**
 227  * put_user: - Write a simple value into user space.
 228  * @x:   Value to copy to user space.
 229  * @ptr: Destination address, in user space.
 230  *
 231  * Context: User context only. This function may sleep if pagefaults are
 232  *          enabled.
 233  *
 234  * This macro copies a single simple value from kernel space to user
 235  * space.  It supports simple types like char and int, but not larger
 236  * data types like structures or arrays.
 237  *
 238  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 239  * to the result of dereferencing @ptr.
 240  *
 241  * Returns zero on success, or -EFAULT on error.
 242  */
 243 #define put_user(x, ptr)                                        \
 244 ({                                                              \
 245         int __ret_pu;                                           \
 246         __typeof__(*(ptr)) __pu_val;                            \
 247         __chk_user_ptr(ptr);                                    \
 248         might_fault();                                          \
 249         __pu_val = x;                                           \
 250         switch (sizeof(*(ptr))) {                               \
 251         case 1:                                                 \
 252                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 253                 break;                                          \
 254         case 2:                                                 \
 255                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 256                 break;                                          \
 257         case 4:                                                 \
 258                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 259                 break;                                          \
 260         case 8:                                                 \
 261                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 262                 break;                                          \
 263         default:                                                \
 264                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 265                 break;                                          \
 266         }                                                       \
 267         __builtin_expect(__ret_pu, 0);                          \
 268 })
 269
 270 #define __put_user_size(x, ptr, size, retval, errret)                   \
 271 do {                                                                    \
 272         retval = 0;                                                     \
 273         __chk_user_ptr(ptr);                                            \
 274         switch (size) {                                                 \
 275         case 1:                                                         \
 276                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 277                 break;                                                  \
 278         case 2:                                                         \
 279                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 280                 break;                                                  \
 281         case 4:                                                         \
 282                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 283                 break;                                                  \
 284         case 8:                                                         \
 285                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 286                                    errret);                             \
 287                 break;                                                  \
 288         default:                                                        \
 289                 __put_user_bad();                                       \
 290         }                                                               \
 291 } while (0)
 292
 293 /*
 294  * This doesn't do __uaccess_begin/end - the exception handling
 295  * around it must do that.
 296  */
 297 #define __put_user_size_ex(x, ptr, size)                                \
 298 do {                                                                    \
 299         __chk_user_ptr(ptr);                                            \
 300         switch (size) {                                                 \
 301         case 1:                                                         \
 302                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 303                 break;                                                  \
 304         case 2:                                                         \
 305                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 306                 break;                                                  \
 307         case 4:                                                         \
 308                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 309                 break;                                                  \
 310         case 8:                                                         \
 311                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 312                 break;                                                  \
 313         default:                                                        \
 314                 __put_user_bad();                                       \
 315         }                                                               \
 316 } while (0)
 317
 318 #ifdef CONFIG_X86_32
 319 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 320 ({                                                                      \
 321         __typeof__(ptr) __ptr = (ptr);                                  \
 322         asm volatile(ASM_STAC "\n"                                      \
 323                      "1:        movl %2,%%eax\n"                        \
 324                      "2:        movl %3,%%edx\n"                        \
 325                      "3: " ASM_CLAC "\n"                                \
 326                      ".section .fixup,\"ax\"\n"                         \
 327                      "4:        mov %4,%0\n"                            \
 328                      "  xorl %%eax,%%eax\n"                             \
 329                      "  xorl %%edx,%%edx\n"                             \
 330                      "  jmp 3b\n"                                       \
 331                      ".previous\n"                                      \
 332                      _ASM_EXTABLE(1b, 4b)                               \
 333                      _ASM_EXTABLE(2b, 4b)                               \
 334                      : "=r" (retval), "=A"(x)                           \
 335                      : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
 336                        "i" (errret), "0" (retval));                     \
 337 })
 338
 339 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 340 #else
 341 #define __get_user_asm_u64(x, ptr, retval, errret) \
 342          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 343 #define __get_user_asm_ex_u64(x, ptr) \
 344          __get_user_asm_ex(x, ptr, "q", "", "=r")
 345 #endif
 346
 347 #define __get_user_size(x, ptr, size, retval, errret)                   \
 348 do {                                                                    \
 349         retval = 0;                                                     \
 350         __chk_user_ptr(ptr);                                            \
 351         switch (size) {                                                 \
 352         case 1:                                                         \
 353                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 354                 break;                                                  \
 355         case 2:                                                         \
 356                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 357                 break;                                                  \
 358         case 4:                                                         \
 359                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 360                 break;                                                  \
 361         case 8:                                                         \
 362                 __get_user_asm_u64(x, ptr, retval, errret);             \
 363                 break;                                                  \
 364         default:                                                        \
 365                 (x) = __get_user_bad();                                 \
 366         }                                                               \
 367 } while (0)
 368
 369 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 370         asm volatile("\n"                                               \
 371                      "1:        mov"itype" %2,%"rtype"1\n"              \
 372                      "2:\n"                                             \
 373                      ".section .fixup,\"ax\"\n"                         \
 374                      "3:        mov %3,%0\n"                            \
 375                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 376                      "  jmp 2b\n"                                       \
 377                      ".previous\n"                                      \
 378                      _ASM_EXTABLE(1b, 3b)                               \
 379                      : "=r" (err), ltype(x)                             \
 380                      : "m" (__m(addr)), "i" (errret), "0" (err))
 381
 382 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 383         asm volatile("\n"                                               \
 384                      "1:        mov"itype" %2,%"rtype"1\n"              \
 385                      "2:\n"                                             \
 386                      ".section .fixup,\"ax\"\n"                         \
 387                      "3:        mov %3,%0\n"                            \
 388                      "  jmp 2b\n"                                       \
 389                      ".previous\n"                                      \
 390                      _ASM_EXTABLE(1b, 3b)                               \
 391                      : "=r" (err), ltype(x)                             \
 392                      : "m" (__m(addr)), "i" (errret), "0" (err))
 393
 394 /*
 395  * This doesn't do __uaccess_begin/end - the exception handling
 396  * around it must do that.
 397  */
 398 #define __get_user_size_ex(x, ptr, size)                                \
 399 do {                                                                    \
 400         __chk_user_ptr(ptr);                                            \
 401         switch (size) {                                                 \
 402         case 1:                                                         \
 403                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 404                 break;                                                  \
 405         case 2:                                                         \
 406                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 407                 break;                                                  \
 408         case 4:                                                         \
 409                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 410                 break;                                                  \
 411         case 8:                                                         \
 412                 __get_user_asm_ex_u64(x, ptr);                          \
 413                 break;                                                  \
 414         default:                                                        \
 415                 (x) = __get_user_bad();                                 \
 416         }                                                               \
 417 } while (0)
 418
 419 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 420         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 421                      "2:\n"                                             \
 422                      ".section .fixup,\"ax\"\n"                         \
 423                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 424                      "  jmp 2b\n"                                       \
 425                      ".previous\n"                                      \
 426                      _ASM_EXTABLE_EX(1b, 3b)                            \
 427                      : ltype(x) : "m" (__m(addr)))
 428
 429 #define __put_user_nocheck(x, ptr, size)                        \
 430 ({                                                              \
 431         int __pu_err;                                           \
 432         __uaccess_begin();                                      \
 433         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 434         __uaccess_end();                                        \
 435         __builtin_expect(__pu_err, 0);                          \
 436 })
 437
 438 #define __get_user_nocheck(x, ptr, size)                                \
 439 ({                                                                      \
 440         int __gu_err;                                                   \
 441         __inttype(*(ptr)) __gu_val;                                     \
 442         __uaccess_begin();                                              \
 443         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 444         __uaccess_end();                                                \
 445         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 446         __builtin_expect(__gu_err, 0);                                  \
 447 })
 448
 449 /* FIXME: this hack is definitely wrong -AK */
 450 struct __large_struct { unsigned long buf[100]; };
 451 #define __m(x) (*(struct __large_struct __user *)(x))
 452
 453 /*
 454  * Tell gcc we read from memory instead of writing: this is because
 455  * we do not write to any memory gcc knows about, so there are no
 456  * aliasing issues.
 457  */
 458 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 459         asm volatile("\n"                                               \
 460                      "1:        mov"itype" %"rtype"1,%2\n"              \
 461                      "2:\n"                                             \
 462                      ".section .fixup,\"ax\"\n"                         \
 463                      "3:        mov %3,%0\n"                            \
 464                      "  jmp 2b\n"                                       \
 465                      ".previous\n"                                      \
 466                      _ASM_EXTABLE(1b, 3b)                               \
 467                      : "=r"(err)                                        \
 468                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 469
 470 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 471         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 472                      "2:\n"                                             \
 473                      _ASM_EXTABLE_EX(1b, 2b)                            \
 474                      : : ltype(x), "m" (__m(addr)))
 475
 476 /*
 477  * uaccess_try and catch
 478  */
 479 #define uaccess_try     do {                                            \
 480         current->thread.uaccess_err = 0;                                \
 481         __uaccess_begin();                                              \
 482         barrier();
 483
 484 #define uaccess_catch(err)                                              \
 485         __uaccess_end();                                                \
 486         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 487 } while (0)
 488
 489 /**
 490  * __get_user: - Get a simple variable from user space, with less checking.
 491  * @x:   Variable to store result.
 492  * @ptr: Source address, in user space.
 493  *
 494  * Context: User context only. This function may sleep if pagefaults are
 495  *          enabled.
 496  *
 497  * This macro copies a single simple variable from user space to kernel
 498  * space.  It supports simple types like char and int, but not larger
 499  * data types like structures or arrays.
 500  *
 501  * @ptr must have pointer-to-simple-variable type, and the result of
 502  * dereferencing @ptr must be assignable to @x without a cast.
 503  *
 504  * Caller must check the pointer with access_ok() before calling this
 505  * function.
 506  *
 507  * Returns zero on success, or -EFAULT on error.
 508  * On error, the variable @x is set to zero.
 509  */
 510
 511 #define __get_user(x, ptr)                                              \
 512         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 513
 514 /**
 515  * __put_user: - Write a simple value into user space, with less checking.
 516  * @x:   Value to copy to user space.
 517  * @ptr: Destination address, in user space.
 518  *
 519  * Context: User context only. This function may sleep if pagefaults are
 520  *          enabled.
 521  *
 522  * This macro copies a single simple value from kernel space to user
 523  * space.  It supports simple types like char and int, but not larger
 524  * data types like structures or arrays.
 525  *
 526  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 527  * to the result of dereferencing @ptr.
 528  *
 529  * Caller must check the pointer with access_ok() before calling this
 530  * function.
 531  *
 532  * Returns zero on success, or -EFAULT on error.
 533  */
 534
 535 #define __put_user(x, ptr)                                              \
 536         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 537
 538 #define __get_user_unaligned __get_user
 539 #define __put_user_unaligned __put_user
 540
 541 /*
 542  * {get|put}_user_try and catch
 543  *
 544  * get_user_try {
 545  *      get_user_ex(...);
 546  * } get_user_catch(err)
 547  */
 548 #define get_user_try            uaccess_try
 549 #define get_user_catch(err)     uaccess_catch(err)
 550
 551 #define get_user_ex(x, ptr)     do {                                    \
 552         unsigned long __gue_val;                                        \
 553         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 554         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 555 } while (0)
 556
 557 #define put_user_try            uaccess_try
 558 #define put_user_catch(err)     uaccess_catch(err)
 559
 560 #define put_user_ex(x, ptr)                                             \
 561         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 562
 563 extern unsigned long
 564 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 565 extern __must_check long
 566 strncpy_from_user(char *dst, const char __user *src, long count);
 567
 568 extern __must_check long strlen_user(const char __user *str);
 569 extern __must_check long strnlen_user(const char __user *str, long n);
 570
 571 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 572 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 573
 574 extern void __cmpxchg_wrong_size(void)
 575         __compiletime_error("Bad argument size for cmpxchg");
 576
 577 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 578 ({                                                                      \
 579         int __ret = 0;                                                  \
 580         __typeof__(ptr) __uval = (uval);                                \
 581         __typeof__(*(ptr)) __old = (old);                               \
 582         __typeof__(*(ptr)) __new = (new);                               \
 583         __uaccess_begin();                                              \
 584         switch (size) {                                                 \
 585         case 1:                                                         \
 586         {                                                               \
 587                 asm volatile("\n"                                       \
 588                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 589                         "2:\n"                                          \
 590                         "\t.section .fixup, \"ax\"\n"                   \
 591                         "3:\tmov     %3, %0\n"                          \
 592                         "\tjmp     2b\n"                                \
 593                         "\t.previous\n"                                 \
 594                         _ASM_EXTABLE(1b, 3b)                            \
 595                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 596                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 597                         : "memory"                                      \
 598                 );                                                      \
 599                 break;                                                  \
 600         }                                                               \
 601         case 2:                                                         \
 602         {                                                               \
 603                 asm volatile("\n"                                       \
 604                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 605                         "2:\n"                                          \
 606                         "\t.section .fixup, \"ax\"\n"                   \
 607                         "3:\tmov     %3, %0\n"                          \
 608                         "\tjmp     2b\n"                                \
 609                         "\t.previous\n"                                 \
 610                         _ASM_EXTABLE(1b, 3b)                            \
 611                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 612                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 613                         : "memory"                                      \
 614                 );                                                      \
 615                 break;                                                  \
 616         }                                                               \
 617         case 4:                                                         \
 618         {                                                               \
 619                 asm volatile("\n"                                       \
 620                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 621                         "2:\n"                                          \
 622                         "\t.section .fixup, \"ax\"\n"                   \
 623                         "3:\tmov     %3, %0\n"                          \
 624                         "\tjmp     2b\n"                                \
 625                         "\t.previous\n"                                 \
 626                         _ASM_EXTABLE(1b, 3b)                            \
 627                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 628                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 629                         : "memory"                                      \
 630                 );                                                      \
 631                 break;                                                  \
 632         }                                                               \
 633         case 8:                                                         \
 634         {                                                               \
 635                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 636                         __cmpxchg_wrong_size();                         \
 637                                                                         \
 638                 asm volatile("\n"                                       \
 639                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 640                         "2:\n"                                          \
 641                         "\t.section .fixup, \"ax\"\n"                   \
 642                         "3:\tmov     %3, %0\n"                          \
 643                         "\tjmp     2b\n"                                \
 644                         "\t.previous\n"                                 \
 645                         _ASM_EXTABLE(1b, 3b)                            \
 646                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 647                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 648                         : "memory"                                      \
 649                 );                                                      \
 650                 break;                                                  \
 651         }                                                               \
 652         default:                                                        \
 653                 __cmpxchg_wrong_size();                                 \
 654         }                                                               \
 655         __uaccess_end();                                                \
 656         *__uval = __old;                                                \
 657         __ret;                                                          \
 658 })
 659
 660 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 661 ({                                                                      \
 662         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 663                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 664                                 (old), (new), sizeof(*(ptr))) :         \
 665                 -EFAULT;                                                \
 666 })
 667
 668 /*
 669  * movsl can be slow when source and dest are not both 8-byte aligned
 670  */
 671 #ifdef CONFIG_X86_INTEL_USERCOPY
 672 extern struct movsl_mask {
 673         int mask;
 674 } ____cacheline_aligned_in_smp movsl_mask;
 675 #endif
 676
 677 #define ARCH_HAS_NOCACHE_UACCESS 1
 678
 679 #ifdef CONFIG_X86_32
 680 # include <asm/uaccess_32.h>
 681 #else
 682 # include <asm/uaccess_64.h>
 683 #endif
 684
 685 /*
 686  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 687  * nested NMI paths are careful to preserve CR2.
 688  *
 689  * Caller must use pagefault_enable/disable, or run in interrupt context,
 690  * and also do a uaccess_ok() check
 691  */
 692 #define __copy_from_user_nmi __copy_from_user_inatomic
 693
 694 /*
 695  * The "unsafe" user accesses aren't really "unsafe", but the naming
 696  * is a big fat warning: you have to not only do the access_ok()
 697  * checking before using them, but you have to surround them with the
 698  * user_access_begin/end() pair.
 699  */
 700 #define user_access_begin()     __uaccess_begin()
 701 #define user_access_end()       __uaccess_end()
 702
 703 #define unsafe_put_user(x, ptr, err_label)                                      \
 704 do {                                                                            \
 705         int __pu_err;                                                           \
 706         __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);             \
 707         if (unlikely(__pu_err)) goto err_label;                                 \
 708 } while (0)
 709
 710 #define unsafe_get_user(x, ptr, err_label)                                      \
 711 do {                                                                            \
 712         int __gu_err;                                                           \
 713         unsigned long __gu_val;                                                 \
 714         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 715         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 716         if (unlikely(__gu_err)) goto err_label;                                 \
 717 } while (0)
 718
 719 #endif /* _ASM_X86_UACCESS_H */
 720