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/kasan-checks.h>
   9 #include <linux/thread_info.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13 #include <asm/smap.h>
  14 #include <asm/extable.h>
  15
  16 #define VERIFY_READ 0
  17 #define VERIFY_WRITE 1
  18
  19 /*
  20  * The fs value determines whether argument validity checking should be
  21  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  22  * get_fs() == KERNEL_DS, checking is bypassed.
  23  *
  24  * For historical reasons, these macros are grossly misnamed.
  25  */
  26
  27 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  28
  29 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  30 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  31
  32 #define get_ds()        (KERNEL_DS)
  33 #define get_fs()        (current->thread.addr_limit)
  34 #define set_fs(x)       (current->thread.addr_limit = (x))
  35
  36 #define segment_eq(a, b)        ((a).seg == (b).seg)
  37
  38 #define user_addr_max() (current->thread.addr_limit.seg)
  39 #define __addr_ok(addr)         \
  40         ((unsigned long __force)(addr) < user_addr_max())
  41
  42 /*
  43  * Test whether a block of memory is a valid user space address.
  44  * Returns 0 if the range is valid, nonzero otherwise.
  45  */
  46 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  47 {
  48         /*
  49          * If we have used "sizeof()" for the size,
  50          * we know it won't overflow the limit (but
  51          * it might overflow the 'addr', so it's
  52          * important to subtract the size from the
  53          * limit, not add it to the address).
  54          */
  55         if (__builtin_constant_p(size))
  56                 return unlikely(addr > limit - size);
  57
  58         /* Arbitrary sizes? Be careful about overflow */
  59         addr += size;
  60         if (unlikely(addr < size))
  61                 return true;
  62         return unlikely(addr > limit);
  63 }
  64
  65 #define __range_not_ok(addr, size, limit)                               \
  66 ({                                                                      \
  67         __chk_user_ptr(addr);                                           \
  68         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  69 })
  70
  71 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  72 # define WARN_ON_IN_IRQ()       WARN_ON_ONCE(!in_task())
  73 #else
  74 # define WARN_ON_IN_IRQ()
  75 #endif
  76
  77 /**
  78  * access_ok: - Checks if a user space pointer is valid
  79  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  80  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  81  *        to write to a block, it is always safe to read from it.
  82  * @addr: User space pointer to start of block to check
  83  * @size: Size of block to check
  84  *
  85  * Context: User context only. This function may sleep if pagefaults are
  86  *          enabled.
  87  *
  88  * Checks if a pointer to a block of memory in user space is valid.
  89  *
  90  * Returns true (nonzero) if the memory block may be valid, false (zero)
  91  * if it is definitely invalid.
  92  *
  93  * Note that, depending on architecture, this function probably just
  94  * checks that the pointer is in the user space range - after calling
  95  * this function, memory access functions may still return -EFAULT.
  96  */
  97 #define access_ok(type, addr, size)                                     \
  98 ({                                                                      \
  99         WARN_ON_IN_IRQ();                                               \
 100         likely(!__range_not_ok(addr, size, user_addr_max()));           \
 101 })
 102
 103 /*
 104  * These are the main single-value transfer routines.  They automatically
 105  * use the right size if we just have the right pointer type.
 106  *
 107  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 108  * and yet we don't want to do any pointers, because that is too much
 109  * of a performance impact. Thus we have a few rather ugly macros here,
 110  * and hide all the ugliness from the user.
 111  *
 112  * The "__xxx" versions of the user access functions are versions that
 113  * do not verify the address space, that must have been done previously
 114  * with a separate "access_ok()" call (this is used when we do multiple
 115  * accesses to the same area of user memory).
 116  */
 117
 118 extern int __get_user_1(void);
 119 extern int __get_user_2(void);
 120 extern int __get_user_4(void);
 121 extern int __get_user_8(void);
 122 extern int __get_user_bad(void);
 123
 124 #define __uaccess_begin() stac()
 125 #define __uaccess_end()   clac()
 126
 127 /*
 128  * This is a type: either unsigned long, if the argument fits into
 129  * that type, or otherwise unsigned long long.
 130  */
 131 #define __inttype(x) \
 132 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 133
 134 /**
 135  * get_user: - Get a simple variable from user space.
 136  * @x:   Variable to store result.
 137  * @ptr: Source address, in user space.
 138  *
 139  * Context: User context only. This function may sleep if pagefaults are
 140  *          enabled.
 141  *
 142  * This macro copies a single simple variable from user space to kernel
 143  * space.  It supports simple types like char and int, but not larger
 144  * data types like structures or arrays.
 145  *
 146  * @ptr must have pointer-to-simple-variable type, and the result of
 147  * dereferencing @ptr must be assignable to @x without a cast.
 148  *
 149  * Returns zero on success, or -EFAULT on error.
 150  * On error, the variable @x is set to zero.
 151  */
 152 /*
 153  * Careful: we have to cast the result to the type of the pointer
 154  * for sign reasons.
 155  *
 156  * The use of _ASM_DX as the register specifier is a bit of a
 157  * simplification, as gcc only cares about it as the starting point
 158  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 159  * (%ecx being the next register in gcc's x86 register sequence), and
 160  * %rdx on 64 bits.
 161  *
 162  * Clang/LLVM cares about the size of the register, but still wants
 163  * the base register for something that ends up being a pair.
 164  */
 165 #define get_user(x, ptr)                                                \
 166 ({                                                                      \
 167         int __ret_gu;                                                   \
 168         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 169         register void *__sp asm(_ASM_SP);                               \
 170         __chk_user_ptr(ptr);                                            \
 171         might_fault();                                                  \
 172         asm volatile("call __get_user_%P4"                              \
 173                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 174                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 175         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 176         __builtin_expect(__ret_gu, 0);                                  \
 177 })
 178
 179 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 180         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 181                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 182
 183
 184
 185 #ifdef CONFIG_X86_32
 186 #define __put_user_asm_u64(x, addr, err, errret)                        \
 187         asm volatile("\n"                                               \
 188                      "1:        movl %%eax,0(%2)\n"                     \
 189                      "2:        movl %%edx,4(%2)\n"                     \
 190                      "3:"                                               \
 191                      ".section .fixup,\"ax\"\n"                         \
 192                      "4:        movl %3,%0\n"                           \
 193                      "  jmp 3b\n"                                       \
 194                      ".previous\n"                                      \
 195                      _ASM_EXTABLE(1b, 4b)                               \
 196                      _ASM_EXTABLE(2b, 4b)                               \
 197                      : "=r" (err)                                       \
 198                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 199
 200 #define __put_user_asm_ex_u64(x, addr)                                  \
 201         asm volatile("\n"                                               \
 202                      "1:        movl %%eax,0(%1)\n"                     \
 203                      "2:        movl %%edx,4(%1)\n"                     \
 204                      "3:"                                               \
 205                      _ASM_EXTABLE_EX(1b, 2b)                            \
 206                      _ASM_EXTABLE_EX(2b, 3b)                            \
 207                      : : "A" (x), "r" (addr))
 208
 209 #define __put_user_x8(x, ptr, __ret_pu)                         \
 210         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 211                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 212 #else
 213 #define __put_user_asm_u64(x, ptr, retval, errret) \
 214         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 215 #define __put_user_asm_ex_u64(x, addr)  \
 216         __put_user_asm_ex(x, addr, "q", "", "er")
 217 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 218 #endif
 219
 220 extern void __put_user_bad(void);
 221
 222 /*
 223  * Strange magic calling convention: pointer in %ecx,
 224  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 225  */
 226 extern void __put_user_1(void);
 227 extern void __put_user_2(void);
 228 extern void __put_user_4(void);
 229 extern void __put_user_8(void);
 230
 231 /**
 232  * put_user: - Write a simple value into user space.
 233  * @x:   Value to copy to user space.
 234  * @ptr: Destination address, in user space.
 235  *
 236  * Context: User context only. This function may sleep if pagefaults are
 237  *          enabled.
 238  *
 239  * This macro copies a single simple value from kernel space to user
 240  * space.  It supports simple types like char and int, but not larger
 241  * data types like structures or arrays.
 242  *
 243  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 244  * to the result of dereferencing @ptr.
 245  *
 246  * Returns zero on success, or -EFAULT on error.
 247  */
 248 #define put_user(x, ptr)                                        \
 249 ({                                                              \
 250         int __ret_pu;                                           \
 251         __typeof__(*(ptr)) __pu_val;                            \
 252         __chk_user_ptr(ptr);                                    \
 253         might_fault();                                          \
 254         __pu_val = x;                                           \
 255         switch (sizeof(*(ptr))) {                               \
 256         case 1:                                                 \
 257                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 258                 break;                                          \
 259         case 2:                                                 \
 260                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 261                 break;                                          \
 262         case 4:                                                 \
 263                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 264                 break;                                          \
 265         case 8:                                                 \
 266                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 267                 break;                                          \
 268         default:                                                \
 269                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 270                 break;                                          \
 271         }                                                       \
 272         __builtin_expect(__ret_pu, 0);                          \
 273 })
 274
 275 #define __put_user_size(x, ptr, size, retval, errret)                   \
 276 do {                                                                    \
 277         retval = 0;                                                     \
 278         __chk_user_ptr(ptr);                                            \
 279         switch (size) {                                                 \
 280         case 1:                                                         \
 281                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 282                 break;                                                  \
 283         case 2:                                                         \
 284                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 285                 break;                                                  \
 286         case 4:                                                         \
 287                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 288                 break;                                                  \
 289         case 8:                                                         \
 290                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 291                                    errret);                             \
 292                 break;                                                  \
 293         default:                                                        \
 294                 __put_user_bad();                                       \
 295         }                                                               \
 296 } while (0)
 297
 298 /*
 299  * This doesn't do __uaccess_begin/end - the exception handling
 300  * around it must do that.
 301  */
 302 #define __put_user_size_ex(x, ptr, size)                                \
 303 do {                                                                    \
 304         __chk_user_ptr(ptr);                                            \
 305         switch (size) {                                                 \
 306         case 1:                                                         \
 307                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 308                 break;                                                  \
 309         case 2:                                                         \
 310                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 311                 break;                                                  \
 312         case 4:                                                         \
 313                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 314                 break;                                                  \
 315         case 8:                                                         \
 316                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 317                 break;                                                  \
 318         default:                                                        \
 319                 __put_user_bad();                                       \
 320         }                                                               \
 321 } while (0)
 322
 323 #ifdef CONFIG_X86_32
 324 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 325 ({                                                                      \
 326         __typeof__(ptr) __ptr = (ptr);                                  \
 327         asm volatile(ASM_STAC "\n"                                      \
 328                      "1:        movl %2,%%eax\n"                        \
 329                      "2:        movl %3,%%edx\n"                        \
 330                      "3: " ASM_CLAC "\n"                                \
 331                      ".section .fixup,\"ax\"\n"                         \
 332                      "4:        mov %4,%0\n"                            \
 333                      "  xorl %%eax,%%eax\n"                             \
 334                      "  xorl %%edx,%%edx\n"                             \
 335                      "  jmp 3b\n"                                       \
 336                      ".previous\n"                                      \
 337                      _ASM_EXTABLE(1b, 4b)                               \
 338                      _ASM_EXTABLE(2b, 4b)                               \
 339                      : "=r" (retval), "=A"(x)                           \
 340                      : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
 341                        "i" (errret), "0" (retval));                     \
 342 })
 343
 344 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 345 #else
 346 #define __get_user_asm_u64(x, ptr, retval, errret) \
 347          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 348 #define __get_user_asm_ex_u64(x, ptr) \
 349          __get_user_asm_ex(x, ptr, "q", "", "=r")
 350 #endif
 351
 352 #define __get_user_size(x, ptr, size, retval, errret)                   \
 353 do {                                                                    \
 354         retval = 0;                                                     \
 355         __chk_user_ptr(ptr);                                            \
 356         switch (size) {                                                 \
 357         case 1:                                                         \
 358                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 359                 break;                                                  \
 360         case 2:                                                         \
 361                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 362                 break;                                                  \
 363         case 4:                                                         \
 364                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 365                 break;                                                  \
 366         case 8:                                                         \
 367                 __get_user_asm_u64(x, ptr, retval, errret);             \
 368                 break;                                                  \
 369         default:                                                        \
 370                 (x) = __get_user_bad();                                 \
 371         }                                                               \
 372 } while (0)
 373
 374 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 375         asm volatile("\n"                                               \
 376                      "1:        mov"itype" %2,%"rtype"1\n"              \
 377                      "2:\n"                                             \
 378                      ".section .fixup,\"ax\"\n"                         \
 379                      "3:        mov %3,%0\n"                            \
 380                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 381                      "  jmp 2b\n"                                       \
 382                      ".previous\n"                                      \
 383                      _ASM_EXTABLE(1b, 3b)                               \
 384                      : "=r" (err), ltype(x)                             \
 385                      : "m" (__m(addr)), "i" (errret), "0" (err))
 386
 387 /*
 388  * This doesn't do __uaccess_begin/end - the exception handling
 389  * around it must do that.
 390  */
 391 #define __get_user_size_ex(x, ptr, size)                                \
 392 do {                                                                    \
 393         __chk_user_ptr(ptr);                                            \
 394         switch (size) {                                                 \
 395         case 1:                                                         \
 396                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 397                 break;                                                  \
 398         case 2:                                                         \
 399                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 400                 break;                                                  \
 401         case 4:                                                         \
 402                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 403                 break;                                                  \
 404         case 8:                                                         \
 405                 __get_user_asm_ex_u64(x, ptr);                          \
 406                 break;                                                  \
 407         default:                                                        \
 408                 (x) = __get_user_bad();                                 \
 409         }                                                               \
 410 } while (0)
 411
 412 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 413         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 414                      "2:\n"                                             \
 415                      ".section .fixup,\"ax\"\n"                         \
 416                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 417                      "  jmp 2b\n"                                       \
 418                      ".previous\n"                                      \
 419                      _ASM_EXTABLE_EX(1b, 3b)                            \
 420                      : ltype(x) : "m" (__m(addr)))
 421
 422 #define __put_user_nocheck(x, ptr, size)                        \
 423 ({                                                              \
 424         int __pu_err;                                           \
 425         __uaccess_begin();                                      \
 426         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 427         __uaccess_end();                                        \
 428         __builtin_expect(__pu_err, 0);                          \
 429 })
 430
 431 #define __get_user_nocheck(x, ptr, size)                                \
 432 ({                                                                      \
 433         int __gu_err;                                                   \
 434         __inttype(*(ptr)) __gu_val;                                     \
 435         __uaccess_begin();                                              \
 436         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 437         __uaccess_end();                                                \
 438         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 439         __builtin_expect(__gu_err, 0);                                  \
 440 })
 441
 442 /* FIXME: this hack is definitely wrong -AK */
 443 struct __large_struct { unsigned long buf[100]; };
 444 #define __m(x) (*(struct __large_struct __user *)(x))
 445
 446 /*
 447  * Tell gcc we read from memory instead of writing: this is because
 448  * we do not write to any memory gcc knows about, so there are no
 449  * aliasing issues.
 450  */
 451 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 452         asm volatile("\n"                                               \
 453                      "1:        mov"itype" %"rtype"1,%2\n"              \
 454                      "2:\n"                                             \
 455                      ".section .fixup,\"ax\"\n"                         \
 456                      "3:        mov %3,%0\n"                            \
 457                      "  jmp 2b\n"                                       \
 458                      ".previous\n"                                      \
 459                      _ASM_EXTABLE(1b, 3b)                               \
 460                      : "=r"(err)                                        \
 461                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 462
 463 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 464         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 465                      "2:\n"                                             \
 466                      _ASM_EXTABLE_EX(1b, 2b)                            \
 467                      : : ltype(x), "m" (__m(addr)))
 468
 469 /*
 470  * uaccess_try and catch
 471  */
 472 #define uaccess_try     do {                                            \
 473         current->thread.uaccess_err = 0;                                \
 474         __uaccess_begin();                                              \
 475         barrier();
 476
 477 #define uaccess_catch(err)                                              \
 478         __uaccess_end();                                                \
 479         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 480 } while (0)
 481
 482 /**
 483  * __get_user: - Get a simple variable from user space, with less checking.
 484  * @x:   Variable to store result.
 485  * @ptr: Source address, in user space.
 486  *
 487  * Context: User context only. This function may sleep if pagefaults are
 488  *          enabled.
 489  *
 490  * This macro copies a single simple variable from user space to kernel
 491  * space.  It supports simple types like char and int, but not larger
 492  * data types like structures or arrays.
 493  *
 494  * @ptr must have pointer-to-simple-variable type, and the result of
 495  * dereferencing @ptr must be assignable to @x without a cast.
 496  *
 497  * Caller must check the pointer with access_ok() before calling this
 498  * function.
 499  *
 500  * Returns zero on success, or -EFAULT on error.
 501  * On error, the variable @x is set to zero.
 502  */
 503
 504 #define __get_user(x, ptr)                                              \
 505         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 506
 507 /**
 508  * __put_user: - Write a simple value into user space, with less checking.
 509  * @x:   Value to copy to user space.
 510  * @ptr: Destination address, in user space.
 511  *
 512  * Context: User context only. This function may sleep if pagefaults are
 513  *          enabled.
 514  *
 515  * This macro copies a single simple value from kernel space to user
 516  * space.  It supports simple types like char and int, but not larger
 517  * data types like structures or arrays.
 518  *
 519  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 520  * to the result of dereferencing @ptr.
 521  *
 522  * Caller must check the pointer with access_ok() before calling this
 523  * function.
 524  *
 525  * Returns zero on success, or -EFAULT on error.
 526  */
 527
 528 #define __put_user(x, ptr)                                              \
 529         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 530
 531 #define __get_user_unaligned __get_user
 532 #define __put_user_unaligned __put_user
 533
 534 /*
 535  * {get|put}_user_try and catch
 536  *
 537  * get_user_try {
 538  *      get_user_ex(...);
 539  * } get_user_catch(err)
 540  */
 541 #define get_user_try            uaccess_try
 542 #define get_user_catch(err)     uaccess_catch(err)
 543
 544 #define get_user_ex(x, ptr)     do {                                    \
 545         unsigned long __gue_val;                                        \
 546         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 547         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 548 } while (0)
 549
 550 #define put_user_try            uaccess_try
 551 #define put_user_catch(err)     uaccess_catch(err)
 552
 553 #define put_user_ex(x, ptr)                                             \
 554         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 555
 556 extern unsigned long
 557 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 558 extern __must_check long
 559 strncpy_from_user(char *dst, const char __user *src, long count);
 560
 561 extern __must_check long strlen_user(const char __user *str);
 562 extern __must_check long strnlen_user(const char __user *str, long n);
 563
 564 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 565 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 566
 567 extern void __cmpxchg_wrong_size(void)
 568         __compiletime_error("Bad argument size for cmpxchg");
 569
 570 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 571 ({                                                                      \
 572         int __ret = 0;                                                  \
 573         __typeof__(ptr) __uval = (uval);                                \
 574         __typeof__(*(ptr)) __old = (old);                               \
 575         __typeof__(*(ptr)) __new = (new);                               \
 576         __uaccess_begin();                                              \
 577         switch (size) {                                                 \
 578         case 1:                                                         \
 579         {                                                               \
 580                 asm volatile("\n"                                       \
 581                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 582                         "2:\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), "q" (__new), "1" (__old)       \
 590                         : "memory"                                      \
 591                 );                                                      \
 592                 break;                                                  \
 593         }                                                               \
 594         case 2:                                                         \
 595         {                                                               \
 596                 asm volatile("\n"                                       \
 597                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 598                         "2:\n"                                          \
 599                         "\t.section .fixup, \"ax\"\n"                   \
 600                         "3:\tmov     %3, %0\n"                          \
 601                         "\tjmp     2b\n"                                \
 602                         "\t.previous\n"                                 \
 603                         _ASM_EXTABLE(1b, 3b)                            \
 604                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 605                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 606                         : "memory"                                      \
 607                 );                                                      \
 608                 break;                                                  \
 609         }                                                               \
 610         case 4:                                                         \
 611         {                                                               \
 612                 asm volatile("\n"                                       \
 613                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 614                         "2:\n"                                          \
 615                         "\t.section .fixup, \"ax\"\n"                   \
 616                         "3:\tmov     %3, %0\n"                          \
 617                         "\tjmp     2b\n"                                \
 618                         "\t.previous\n"                                 \
 619                         _ASM_EXTABLE(1b, 3b)                            \
 620                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 621                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 622                         : "memory"                                      \
 623                 );                                                      \
 624                 break;                                                  \
 625         }                                                               \
 626         case 8:                                                         \
 627         {                                                               \
 628                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 629                         __cmpxchg_wrong_size();                         \
 630                                                                         \
 631                 asm volatile("\n"                                       \
 632                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 633                         "2:\n"                                          \
 634                         "\t.section .fixup, \"ax\"\n"                   \
 635                         "3:\tmov     %3, %0\n"                          \
 636                         "\tjmp     2b\n"                                \
 637                         "\t.previous\n"                                 \
 638                         _ASM_EXTABLE(1b, 3b)                            \
 639                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 640                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 641                         : "memory"                                      \
 642                 );                                                      \
 643                 break;                                                  \
 644         }                                                               \
 645         default:                                                        \
 646                 __cmpxchg_wrong_size();                                 \
 647         }                                                               \
 648         __uaccess_end();                                                \
 649         *__uval = __old;                                                \
 650         __ret;                                                          \
 651 })
 652
 653 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 654 ({                                                                      \
 655         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 656                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 657                                 (old), (new), sizeof(*(ptr))) :         \
 658                 -EFAULT;                                                \
 659 })
 660
 661 /*
 662  * movsl can be slow when source and dest are not both 8-byte aligned
 663  */
 664 #ifdef CONFIG_X86_INTEL_USERCOPY
 665 extern struct movsl_mask {
 666         int mask;
 667 } ____cacheline_aligned_in_smp movsl_mask;
 668 #endif
 669
 670 #define ARCH_HAS_NOCACHE_UACCESS 1
 671
 672 #ifdef CONFIG_X86_32
 673 # include <asm/uaccess_32.h>
 674 #else
 675 # include <asm/uaccess_64.h>
 676 #endif
 677
 678 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 679                                            unsigned n);
 680 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 681                                          unsigned n);
 682
 683 extern void __compiletime_error("usercopy buffer size is too small")
 684 __bad_copy_user(void);
 685
 686 static inline void copy_user_overflow(int size, unsigned long count)
 687 {
 688         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 689 }
 690
 691 static __always_inline unsigned long __must_check
 692 copy_from_user(void *to, const void __user *from, unsigned long n)
 693 {
 694         int sz = __compiletime_object_size(to);
 695
 696         might_fault();
 697
 698         kasan_check_write(to, n);
 699
 700         if (likely(sz < 0 || sz >= n)) {
 701                 check_object_size(to, n, false);
 702                 n = _copy_from_user(to, from, n);
 703         } else if (!__builtin_constant_p(n))
 704                 copy_user_overflow(sz, n);
 705         else
 706                 __bad_copy_user();
 707
 708         return n;
 709 }
 710
 711 static __always_inline unsigned long __must_check
 712 copy_to_user(void __user *to, const void *from, unsigned long n)
 713 {
 714         int sz = __compiletime_object_size(from);
 715
 716         kasan_check_read(from, n);
 717
 718         might_fault();
 719
 720         if (likely(sz < 0 || sz >= n)) {
 721                 check_object_size(from, n, true);
 722                 n = _copy_to_user(to, from, n);
 723         } else if (!__builtin_constant_p(n))
 724                 copy_user_overflow(sz, n);
 725         else
 726                 __bad_copy_user();
 727
 728         return n;
 729 }
 730
 731 /*
 732  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 733  * nested NMI paths are careful to preserve CR2.
 734  *
 735  * Caller must use pagefault_enable/disable, or run in interrupt context,
 736  * and also do a uaccess_ok() check
 737  */
 738 #define __copy_from_user_nmi __copy_from_user_inatomic
 739
 740 /*
 741  * The "unsafe" user accesses aren't really "unsafe", but the naming
 742  * is a big fat warning: you have to not only do the access_ok()
 743  * checking before using them, but you have to surround them with the
 744  * user_access_begin/end() pair.
 745  */
 746 #define user_access_begin()     __uaccess_begin()
 747 #define user_access_end()       __uaccess_end()
 748
 749 #define unsafe_put_user(x, ptr, err_label)                                      \
 750 do {                                                                            \
 751         int __pu_err;                                                           \
 752         __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);         \
 753         if (unlikely(__pu_err)) goto err_label;                                 \
 754 } while (0)
 755
 756 #define unsafe_get_user(x, ptr, err_label)                                      \
 757 do {                                                                            \
 758         int __gu_err;                                                           \
 759         unsigned long __gu_val;                                                 \
 760         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 761         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 762         if (unlikely(__gu_err)) goto err_label;                                 \
 763 } while (0)
 764
 765 #endif /* _ASM_X86_UACCESS_H */
 766