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 static inline void set_fs(mm_segment_t fs)
  30 {
  31         current->thread.addr_limit = fs;
  32         /* On user-mode return, check fs is correct */
  33         set_thread_flag(TIF_FSCHECK);
  34 }
  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("\n"                                       \
 328                      "1:        movl %2,%%eax\n"                        \
 329                      "2:        movl %3,%%edx\n"                        \
 330                      "3:\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 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 388         asm volatile("\n"                                               \
 389                      "1:        mov"itype" %2,%"rtype"1\n"              \
 390                      "2:\n"                                             \
 391                      ".section .fixup,\"ax\"\n"                         \
 392                      "3:        mov %3,%0\n"                            \
 393                      "  jmp 2b\n"                                       \
 394                      ".previous\n"                                      \
 395                      _ASM_EXTABLE(1b, 3b)                               \
 396                      : "=r" (err), ltype(x)                             \
 397                      : "m" (__m(addr)), "i" (errret), "0" (err))
 398
 399 /*
 400  * This doesn't do __uaccess_begin/end - the exception handling
 401  * around it must do that.
 402  */
 403 #define __get_user_size_ex(x, ptr, size)                                \
 404 do {                                                                    \
 405         __chk_user_ptr(ptr);                                            \
 406         switch (size) {                                                 \
 407         case 1:                                                         \
 408                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 409                 break;                                                  \
 410         case 2:                                                         \
 411                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 412                 break;                                                  \
 413         case 4:                                                         \
 414                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 415                 break;                                                  \
 416         case 8:                                                         \
 417                 __get_user_asm_ex_u64(x, ptr);                          \
 418                 break;                                                  \
 419         default:                                                        \
 420                 (x) = __get_user_bad();                                 \
 421         }                                                               \
 422 } while (0)
 423
 424 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 425         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 426                      "2:\n"                                             \
 427                      ".section .fixup,\"ax\"\n"                         \
 428                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 429                      "  jmp 2b\n"                                       \
 430                      ".previous\n"                                      \
 431                      _ASM_EXTABLE_EX(1b, 3b)                            \
 432                      : ltype(x) : "m" (__m(addr)))
 433
 434 #define __put_user_nocheck(x, ptr, size)                        \
 435 ({                                                              \
 436         int __pu_err;                                           \
 437         __uaccess_begin();                                      \
 438         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 439         __uaccess_end();                                        \
 440         __builtin_expect(__pu_err, 0);                          \
 441 })
 442
 443 #define __get_user_nocheck(x, ptr, size)                                \
 444 ({                                                                      \
 445         int __gu_err;                                                   \
 446         __inttype(*(ptr)) __gu_val;                                     \
 447         __uaccess_begin();                                              \
 448         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 449         __uaccess_end();                                                \
 450         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 451         __builtin_expect(__gu_err, 0);                                  \
 452 })
 453
 454 /* FIXME: this hack is definitely wrong -AK */
 455 struct __large_struct { unsigned long buf[100]; };
 456 #define __m(x) (*(struct __large_struct __user *)(x))
 457
 458 /*
 459  * Tell gcc we read from memory instead of writing: this is because
 460  * we do not write to any memory gcc knows about, so there are no
 461  * aliasing issues.
 462  */
 463 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 464         asm volatile("\n"                                               \
 465                      "1:        mov"itype" %"rtype"1,%2\n"              \
 466                      "2:\n"                                             \
 467                      ".section .fixup,\"ax\"\n"                         \
 468                      "3:        mov %3,%0\n"                            \
 469                      "  jmp 2b\n"                                       \
 470                      ".previous\n"                                      \
 471                      _ASM_EXTABLE(1b, 3b)                               \
 472                      : "=r"(err)                                        \
 473                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 474
 475 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 476         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 477                      "2:\n"                                             \
 478                      _ASM_EXTABLE_EX(1b, 2b)                            \
 479                      : : ltype(x), "m" (__m(addr)))
 480
 481 /*
 482  * uaccess_try and catch
 483  */
 484 #define uaccess_try     do {                                            \
 485         current->thread.uaccess_err = 0;                                \
 486         __uaccess_begin();                                              \
 487         barrier();
 488
 489 #define uaccess_catch(err)                                              \
 490         __uaccess_end();                                                \
 491         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 492 } while (0)
 493
 494 /**
 495  * __get_user: - Get a simple variable from user space, with less checking.
 496  * @x:   Variable to store result.
 497  * @ptr: Source address, in user space.
 498  *
 499  * Context: User context only. This function may sleep if pagefaults are
 500  *          enabled.
 501  *
 502  * This macro copies a single simple variable from user space to kernel
 503  * space.  It supports simple types like char and int, but not larger
 504  * data types like structures or arrays.
 505  *
 506  * @ptr must have pointer-to-simple-variable type, and the result of
 507  * dereferencing @ptr must be assignable to @x without a cast.
 508  *
 509  * Caller must check the pointer with access_ok() before calling this
 510  * function.
 511  *
 512  * Returns zero on success, or -EFAULT on error.
 513  * On error, the variable @x is set to zero.
 514  */
 515
 516 #define __get_user(x, ptr)                                              \
 517         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 518
 519 /**
 520  * __put_user: - Write a simple value into user space, with less checking.
 521  * @x:   Value to copy to user space.
 522  * @ptr: Destination address, in user space.
 523  *
 524  * Context: User context only. This function may sleep if pagefaults are
 525  *          enabled.
 526  *
 527  * This macro copies a single simple value from kernel space to user
 528  * space.  It supports simple types like char and int, but not larger
 529  * data types like structures or arrays.
 530  *
 531  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 532  * to the result of dereferencing @ptr.
 533  *
 534  * Caller must check the pointer with access_ok() before calling this
 535  * function.
 536  *
 537  * Returns zero on success, or -EFAULT on error.
 538  */
 539
 540 #define __put_user(x, ptr)                                              \
 541         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 542
 543 /*
 544  * {get|put}_user_try and catch
 545  *
 546  * get_user_try {
 547  *      get_user_ex(...);
 548  * } get_user_catch(err)
 549  */
 550 #define get_user_try            uaccess_try
 551 #define get_user_catch(err)     uaccess_catch(err)
 552
 553 #define get_user_ex(x, ptr)     do {                                    \
 554         unsigned long __gue_val;                                        \
 555         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 556         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 557 } while (0)
 558
 559 #define put_user_try            uaccess_try
 560 #define put_user_catch(err)     uaccess_catch(err)
 561
 562 #define put_user_ex(x, ptr)                                             \
 563         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 564
 565 extern unsigned long
 566 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 567 extern __must_check long
 568 strncpy_from_user(char *dst, const char __user *src, long count);
 569
 570 extern __must_check long strnlen_user(const char __user *str, long n);
 571
 572 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 573 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 574
 575 extern void __cmpxchg_wrong_size(void)
 576         __compiletime_error("Bad argument size for cmpxchg");
 577
 578 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 579 ({                                                                      \
 580         int __ret = 0;                                                  \
 581         __typeof__(ptr) __uval = (uval);                                \
 582         __typeof__(*(ptr)) __old = (old);                               \
 583         __typeof__(*(ptr)) __new = (new);                               \
 584         __uaccess_begin();                                              \
 585         switch (size) {                                                 \
 586         case 1:                                                         \
 587         {                                                               \
 588                 asm volatile("\n"                                       \
 589                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 590                         "2:\n"                                          \
 591                         "\t.section .fixup, \"ax\"\n"                   \
 592                         "3:\tmov     %3, %0\n"                          \
 593                         "\tjmp     2b\n"                                \
 594                         "\t.previous\n"                                 \
 595                         _ASM_EXTABLE(1b, 3b)                            \
 596                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 597                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 598                         : "memory"                                      \
 599                 );                                                      \
 600                 break;                                                  \
 601         }                                                               \
 602         case 2:                                                         \
 603         {                                                               \
 604                 asm volatile("\n"                                       \
 605                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 606                         "2:\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         case 4:                                                         \
 619         {                                                               \
 620                 asm volatile("\n"                                       \
 621                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 622                         "2:\n"                                          \
 623                         "\t.section .fixup, \"ax\"\n"                   \
 624                         "3:\tmov     %3, %0\n"                          \
 625                         "\tjmp     2b\n"                                \
 626                         "\t.previous\n"                                 \
 627                         _ASM_EXTABLE(1b, 3b)                            \
 628                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 629                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 630                         : "memory"                                      \
 631                 );                                                      \
 632                 break;                                                  \
 633         }                                                               \
 634         case 8:                                                         \
 635         {                                                               \
 636                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 637                         __cmpxchg_wrong_size();                         \
 638                                                                         \
 639                 asm volatile("\n"                                       \
 640                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 641                         "2:\n"                                          \
 642                         "\t.section .fixup, \"ax\"\n"                   \
 643                         "3:\tmov     %3, %0\n"                          \
 644                         "\tjmp     2b\n"                                \
 645                         "\t.previous\n"                                 \
 646                         _ASM_EXTABLE(1b, 3b)                            \
 647                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 648                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 649                         : "memory"                                      \
 650                 );                                                      \
 651                 break;                                                  \
 652         }                                                               \
 653         default:                                                        \
 654                 __cmpxchg_wrong_size();                                 \
 655         }                                                               \
 656         __uaccess_end();                                                \
 657         *__uval = __old;                                                \
 658         __ret;                                                          \
 659 })
 660
 661 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 662 ({                                                                      \
 663         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 664                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 665                                 (old), (new), sizeof(*(ptr))) :         \
 666                 -EFAULT;                                                \
 667 })
 668
 669 /*
 670  * movsl can be slow when source and dest are not both 8-byte aligned
 671  */
 672 #ifdef CONFIG_X86_INTEL_USERCOPY
 673 extern struct movsl_mask {
 674         int mask;
 675 } ____cacheline_aligned_in_smp movsl_mask;
 676 #endif
 677
 678 #define ARCH_HAS_NOCACHE_UACCESS 1
 679
 680 #ifdef CONFIG_X86_32
 681 # include <asm/uaccess_32.h>
 682 #else
 683 # include <asm/uaccess_64.h>
 684 #endif
 685
 686 /*
 687  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 688  * nested NMI paths are careful to preserve CR2.
 689  *
 690  * Caller must use pagefault_enable/disable, or run in interrupt context,
 691  * and also do a uaccess_ok() check
 692  */
 693 #define __copy_from_user_nmi __copy_from_user_inatomic
 694
 695 /*
 696  * The "unsafe" user accesses aren't really "unsafe", but the naming
 697  * is a big fat warning: you have to not only do the access_ok()
 698  * checking before using them, but you have to surround them with the
 699  * user_access_begin/end() pair.
 700  */
 701 #define user_access_begin()     __uaccess_begin()
 702 #define user_access_end()       __uaccess_end()
 703
 704 #define unsafe_put_user(x, ptr, err_label)                                      \
 705 do {                                                                            \
 706         int __pu_err;                                                           \
 707         __typeof__(*(ptr)) __pu_val = (x);                                      \
 708         __put_user_size(__pu_val, (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);    \
 709         if (unlikely(__pu_err)) goto err_label;                                 \
 710 } while (0)
 711
 712 #define unsafe_get_user(x, ptr, err_label)                                      \
 713 do {                                                                            \
 714         int __gu_err;                                                           \
 715         __inttype(*(ptr)) __gu_val;                                             \
 716         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 717         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 718         if (unlikely(__gu_err)) goto err_label;                                 \
 719 } while (0)
 720
 721 #endif /* _ASM_X86_UACCESS_H */
 722