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 #define __uaccess_begin_nospec()        \
 127 ({                                      \
 128         stac();                         \
 129         barrier_nospec();               \
 130 })
 131
 132 /*
 133  * This is a type: either unsigned long, if the argument fits into
 134  * that type, or otherwise unsigned long long.
 135  */
 136 #define __inttype(x) \
 137 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 138
 139 /**
 140  * get_user: - Get a simple variable from user space.
 141  * @x:   Variable to store result.
 142  * @ptr: Source address, in user space.
 143  *
 144  * Context: User context only. This function may sleep if pagefaults are
 145  *          enabled.
 146  *
 147  * This macro copies a single simple variable from user space to kernel
 148  * space.  It supports simple types like char and int, but not larger
 149  * data types like structures or arrays.
 150  *
 151  * @ptr must have pointer-to-simple-variable type, and the result of
 152  * dereferencing @ptr must be assignable to @x without a cast.
 153  *
 154  * Returns zero on success, or -EFAULT on error.
 155  * On error, the variable @x is set to zero.
 156  */
 157 /*
 158  * Careful: we have to cast the result to the type of the pointer
 159  * for sign reasons.
 160  *
 161  * The use of _ASM_DX as the register specifier is a bit of a
 162  * simplification, as gcc only cares about it as the starting point
 163  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 164  * (%ecx being the next register in gcc's x86 register sequence), and
 165  * %rdx on 64 bits.
 166  *
 167  * Clang/LLVM cares about the size of the register, but still wants
 168  * the base register for something that ends up being a pair.
 169  */
 170 #define get_user(x, ptr)                                                \
 171 ({                                                                      \
 172         int __ret_gu;                                                   \
 173         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 174         register void *__sp asm(_ASM_SP);                               \
 175         __chk_user_ptr(ptr);                                            \
 176         might_fault();                                                  \
 177         asm volatile("call __get_user_%P4"                              \
 178                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 179                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 180         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 181         __builtin_expect(__ret_gu, 0);                                  \
 182 })
 183
 184 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 185         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 186                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 187
 188
 189
 190 #ifdef CONFIG_X86_32
 191 #define __put_user_asm_u64(x, addr, err, errret)                        \
 192         asm volatile("\n"                                               \
 193                      "1:        movl %%eax,0(%2)\n"                     \
 194                      "2:        movl %%edx,4(%2)\n"                     \
 195                      "3:"                                               \
 196                      ".section .fixup,\"ax\"\n"                         \
 197                      "4:        movl %3,%0\n"                           \
 198                      "  jmp 3b\n"                                       \
 199                      ".previous\n"                                      \
 200                      _ASM_EXTABLE(1b, 4b)                               \
 201                      _ASM_EXTABLE(2b, 4b)                               \
 202                      : "=r" (err)                                       \
 203                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 204
 205 #define __put_user_asm_ex_u64(x, addr)                                  \
 206         asm volatile("\n"                                               \
 207                      "1:        movl %%eax,0(%1)\n"                     \
 208                      "2:        movl %%edx,4(%1)\n"                     \
 209                      "3:"                                               \
 210                      _ASM_EXTABLE_EX(1b, 2b)                            \
 211                      _ASM_EXTABLE_EX(2b, 3b)                            \
 212                      : : "A" (x), "r" (addr))
 213
 214 #define __put_user_x8(x, ptr, __ret_pu)                         \
 215         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 216                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 217 #else
 218 #define __put_user_asm_u64(x, ptr, retval, errret) \
 219         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 220 #define __put_user_asm_ex_u64(x, addr)  \
 221         __put_user_asm_ex(x, addr, "q", "", "er")
 222 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 223 #endif
 224
 225 extern void __put_user_bad(void);
 226
 227 /*
 228  * Strange magic calling convention: pointer in %ecx,
 229  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 230  */
 231 extern void __put_user_1(void);
 232 extern void __put_user_2(void);
 233 extern void __put_user_4(void);
 234 extern void __put_user_8(void);
 235
 236 /**
 237  * put_user: - Write a simple value into user space.
 238  * @x:   Value to copy to user space.
 239  * @ptr: Destination address, in user space.
 240  *
 241  * Context: User context only. This function may sleep if pagefaults are
 242  *          enabled.
 243  *
 244  * This macro copies a single simple value from kernel space to user
 245  * space.  It supports simple types like char and int, but not larger
 246  * data types like structures or arrays.
 247  *
 248  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 249  * to the result of dereferencing @ptr.
 250  *
 251  * Returns zero on success, or -EFAULT on error.
 252  */
 253 #define put_user(x, ptr)                                        \
 254 ({                                                              \
 255         int __ret_pu;                                           \
 256         __typeof__(*(ptr)) __pu_val;                            \
 257         __chk_user_ptr(ptr);                                    \
 258         might_fault();                                          \
 259         __pu_val = x;                                           \
 260         switch (sizeof(*(ptr))) {                               \
 261         case 1:                                                 \
 262                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 263                 break;                                          \
 264         case 2:                                                 \
 265                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 266                 break;                                          \
 267         case 4:                                                 \
 268                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 269                 break;                                          \
 270         case 8:                                                 \
 271                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 272                 break;                                          \
 273         default:                                                \
 274                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 275                 break;                                          \
 276         }                                                       \
 277         __builtin_expect(__ret_pu, 0);                          \
 278 })
 279
 280 #define __put_user_size(x, ptr, size, retval, errret)                   \
 281 do {                                                                    \
 282         retval = 0;                                                     \
 283         __chk_user_ptr(ptr);                                            \
 284         switch (size) {                                                 \
 285         case 1:                                                         \
 286                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 287                 break;                                                  \
 288         case 2:                                                         \
 289                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 290                 break;                                                  \
 291         case 4:                                                         \
 292                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 293                 break;                                                  \
 294         case 8:                                                         \
 295                 __put_user_asm_u64(x, ptr, retval, errret);             \
 296                 break;                                                  \
 297         default:                                                        \
 298                 __put_user_bad();                                       \
 299         }                                                               \
 300 } while (0)
 301
 302 /*
 303  * This doesn't do __uaccess_begin/end - the exception handling
 304  * around it must do that.
 305  */
 306 #define __put_user_size_ex(x, ptr, size)                                \
 307 do {                                                                    \
 308         __chk_user_ptr(ptr);                                            \
 309         switch (size) {                                                 \
 310         case 1:                                                         \
 311                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 312                 break;                                                  \
 313         case 2:                                                         \
 314                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 315                 break;                                                  \
 316         case 4:                                                         \
 317                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 318                 break;                                                  \
 319         case 8:                                                         \
 320                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 321                 break;                                                  \
 322         default:                                                        \
 323                 __put_user_bad();                                       \
 324         }                                                               \
 325 } while (0)
 326
 327 #ifdef CONFIG_X86_32
 328 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 329 ({                                                                      \
 330         __typeof__(ptr) __ptr = (ptr);                                  \
 331         asm volatile("\n"                                       \
 332                      "1:        movl %2,%%eax\n"                        \
 333                      "2:        movl %3,%%edx\n"                        \
 334                      "3:\n"                             \
 335                      ".section .fixup,\"ax\"\n"                         \
 336                      "4:        mov %4,%0\n"                            \
 337                      "  xorl %%eax,%%eax\n"                             \
 338                      "  xorl %%edx,%%edx\n"                             \
 339                      "  jmp 3b\n"                                       \
 340                      ".previous\n"                                      \
 341                      _ASM_EXTABLE(1b, 4b)                               \
 342                      _ASM_EXTABLE(2b, 4b)                               \
 343                      : "=r" (retval), "=&A"(x)                          \
 344                      : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
 345                        "i" (errret), "0" (retval));                     \
 346 })
 347
 348 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 349 #else
 350 #define __get_user_asm_u64(x, ptr, retval, errret) \
 351          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 352 #define __get_user_asm_ex_u64(x, ptr) \
 353          __get_user_asm_ex(x, ptr, "q", "", "=r")
 354 #endif
 355
 356 #define __get_user_size(x, ptr, size, retval, errret)                   \
 357 do {                                                                    \
 358         retval = 0;                                                     \
 359         __chk_user_ptr(ptr);                                            \
 360         switch (size) {                                                 \
 361         case 1:                                                         \
 362                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 363                 break;                                                  \
 364         case 2:                                                         \
 365                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 366                 break;                                                  \
 367         case 4:                                                         \
 368                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 369                 break;                                                  \
 370         case 8:                                                         \
 371                 __get_user_asm_u64(x, ptr, retval, errret);             \
 372                 break;                                                  \
 373         default:                                                        \
 374                 (x) = __get_user_bad();                                 \
 375         }                                                               \
 376 } while (0)
 377
 378 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 379         asm volatile("\n"                                               \
 380                      "1:        mov"itype" %2,%"rtype"1\n"              \
 381                      "2:\n"                                             \
 382                      ".section .fixup,\"ax\"\n"                         \
 383                      "3:        mov %3,%0\n"                            \
 384                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 385                      "  jmp 2b\n"                                       \
 386                      ".previous\n"                                      \
 387                      _ASM_EXTABLE(1b, 3b)                               \
 388                      : "=r" (err), ltype(x)                             \
 389                      : "m" (__m(addr)), "i" (errret), "0" (err))
 390
 391 /*
 392  * This doesn't do __uaccess_begin/end - the exception handling
 393  * around it must do that.
 394  */
 395 #define __get_user_size_ex(x, ptr, size)                                \
 396 do {                                                                    \
 397         __chk_user_ptr(ptr);                                            \
 398         switch (size) {                                                 \
 399         case 1:                                                         \
 400                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 401                 break;                                                  \
 402         case 2:                                                         \
 403                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 404                 break;                                                  \
 405         case 4:                                                         \
 406                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 407                 break;                                                  \
 408         case 8:                                                         \
 409                 __get_user_asm_ex_u64(x, ptr);                          \
 410                 break;                                                  \
 411         default:                                                        \
 412                 (x) = __get_user_bad();                                 \
 413         }                                                               \
 414 } while (0)
 415
 416 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 417         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 418                      "2:\n"                                             \
 419                      ".section .fixup,\"ax\"\n"                         \
 420                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 421                      "  jmp 2b\n"                                       \
 422                      ".previous\n"                                      \
 423                      _ASM_EXTABLE_EX(1b, 3b)                            \
 424                      : ltype(x) : "m" (__m(addr)))
 425
 426 #define __put_user_nocheck(x, ptr, size)                        \
 427 ({                                                              \
 428         int __pu_err;                                           \
 429         __typeof__(*(ptr)) __pu_val;                            \
 430         __pu_val = x;                                           \
 431         __uaccess_begin();                                      \
 432         __put_user_size(__pu_val, (ptr), (size), __pu_err, -EFAULT);\
 433         __uaccess_end();                                        \
 434         __builtin_expect(__pu_err, 0);                          \
 435 })
 436
 437 #define __get_user_nocheck(x, ptr, size)                                \
 438 ({                                                                      \
 439         int __gu_err;                                                   \
 440         __inttype(*(ptr)) __gu_val;                                     \
 441         __typeof__(ptr) __gu_ptr = (ptr);                               \
 442         __typeof__(size) __gu_size = (size);                            \
 443         __uaccess_begin_nospec();                                       \
 444         __get_user_size(__gu_val, __gu_ptr, __gu_size, __gu_err, -EFAULT);      \
 445         __uaccess_end();                                                \
 446         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 447         __builtin_expect(__gu_err, 0);                                  \
 448 })
 449
 450 /* FIXME: this hack is definitely wrong -AK */
 451 struct __large_struct { unsigned long buf[100]; };
 452 #define __m(x) (*(struct __large_struct __user *)(x))
 453
 454 /*
 455  * Tell gcc we read from memory instead of writing: this is because
 456  * we do not write to any memory gcc knows about, so there are no
 457  * aliasing issues.
 458  */
 459 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 460         asm volatile("\n"                                               \
 461                      "1:        mov"itype" %"rtype"1,%2\n"              \
 462                      "2:\n"                                             \
 463                      ".section .fixup,\"ax\"\n"                         \
 464                      "3:        mov %3,%0\n"                            \
 465                      "  jmp 2b\n"                                       \
 466                      ".previous\n"                                      \
 467                      _ASM_EXTABLE(1b, 3b)                               \
 468                      : "=r"(err)                                        \
 469                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 470
 471 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 472         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 473                      "2:\n"                                             \
 474                      _ASM_EXTABLE_EX(1b, 2b)                            \
 475                      : : ltype(x), "m" (__m(addr)))
 476
 477 /*
 478  * uaccess_try and catch
 479  */
 480 #define uaccess_try     do {                                            \
 481         current->thread.uaccess_err = 0;                                \
 482         __uaccess_begin();                                              \
 483         barrier();
 484
 485 #define uaccess_try_nospec do {                                         \
 486         current->thread.uaccess_err = 0;                                \
 487         __uaccess_begin_nospec();                                       \
 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 #define __get_user_unaligned __get_user
 544 #define __put_user_unaligned __put_user
 545
 546 /*
 547  * {get|put}_user_try and catch
 548  *
 549  * get_user_try {
 550  *      get_user_ex(...);
 551  * } get_user_catch(err)
 552  */
 553 #define get_user_try            uaccess_try_nospec
 554 #define get_user_catch(err)     uaccess_catch(err)
 555
 556 #define get_user_ex(x, ptr)     do {                                    \
 557         unsigned long __gue_val;                                        \
 558         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 559         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 560 } while (0)
 561
 562 #define put_user_try            uaccess_try
 563 #define put_user_catch(err)     uaccess_catch(err)
 564
 565 #define put_user_ex(x, ptr)                                             \
 566         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 567
 568 extern unsigned long
 569 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 570 extern __must_check long
 571 strncpy_from_user(char *dst, const char __user *src, long count);
 572
 573 extern __must_check long strlen_user(const char __user *str);
 574 extern __must_check long strnlen_user(const char __user *str, long n);
 575
 576 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 577 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 578
 579 extern void __cmpxchg_wrong_size(void)
 580         __compiletime_error("Bad argument size for cmpxchg");
 581
 582 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 583 ({                                                                      \
 584         int __ret = 0;                                                  \
 585         __typeof__(ptr) __uval = (uval);                                \
 586         __typeof__(*(ptr)) __old = (old);                               \
 587         __typeof__(*(ptr)) __new = (new);                               \
 588         __uaccess_begin_nospec();                                       \
 589         switch (size) {                                                 \
 590         case 1:                                                         \
 591         {                                                               \
 592                 asm volatile("\n"                                       \
 593                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 594                         "2:\n"                                          \
 595                         "\t.section .fixup, \"ax\"\n"                   \
 596                         "3:\tmov     %3, %0\n"                          \
 597                         "\tjmp     2b\n"                                \
 598                         "\t.previous\n"                                 \
 599                         _ASM_EXTABLE(1b, 3b)                            \
 600                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 601                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 602                         : "memory"                                      \
 603                 );                                                      \
 604                 break;                                                  \
 605         }                                                               \
 606         case 2:                                                         \
 607         {                                                               \
 608                 asm volatile("\n"                                       \
 609                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 610                         "2:\n"                                          \
 611                         "\t.section .fixup, \"ax\"\n"                   \
 612                         "3:\tmov     %3, %0\n"                          \
 613                         "\tjmp     2b\n"                                \
 614                         "\t.previous\n"                                 \
 615                         _ASM_EXTABLE(1b, 3b)                            \
 616                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 617                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 618                         : "memory"                                      \
 619                 );                                                      \
 620                 break;                                                  \
 621         }                                                               \
 622         case 4:                                                         \
 623         {                                                               \
 624                 asm volatile("\n"                                       \
 625                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 626                         "2:\n"                                          \
 627                         "\t.section .fixup, \"ax\"\n"                   \
 628                         "3:\tmov     %3, %0\n"                          \
 629                         "\tjmp     2b\n"                                \
 630                         "\t.previous\n"                                 \
 631                         _ASM_EXTABLE(1b, 3b)                            \
 632                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 633                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 634                         : "memory"                                      \
 635                 );                                                      \
 636                 break;                                                  \
 637         }                                                               \
 638         case 8:                                                         \
 639         {                                                               \
 640                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 641                         __cmpxchg_wrong_size();                         \
 642                                                                         \
 643                 asm volatile("\n"                                       \
 644                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 645                         "2:\n"                                          \
 646                         "\t.section .fixup, \"ax\"\n"                   \
 647                         "3:\tmov     %3, %0\n"                          \
 648                         "\tjmp     2b\n"                                \
 649                         "\t.previous\n"                                 \
 650                         _ASM_EXTABLE(1b, 3b)                            \
 651                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 652                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 653                         : "memory"                                      \
 654                 );                                                      \
 655                 break;                                                  \
 656         }                                                               \
 657         default:                                                        \
 658                 __cmpxchg_wrong_size();                                 \
 659         }                                                               \
 660         __uaccess_end();                                                \
 661         *__uval = __old;                                                \
 662         __ret;                                                          \
 663 })
 664
 665 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 666 ({                                                                      \
 667         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 668                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 669                                 (old), (new), sizeof(*(ptr))) :         \
 670                 -EFAULT;                                                \
 671 })
 672
 673 /*
 674  * movsl can be slow when source and dest are not both 8-byte aligned
 675  */
 676 #ifdef CONFIG_X86_INTEL_USERCOPY
 677 extern struct movsl_mask {
 678         int mask;
 679 } ____cacheline_aligned_in_smp movsl_mask;
 680 #endif
 681
 682 #define ARCH_HAS_NOCACHE_UACCESS 1
 683
 684 #ifdef CONFIG_X86_32
 685 # include <asm/uaccess_32.h>
 686 #else
 687 # include <asm/uaccess_64.h>
 688 #endif
 689
 690 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 691                                            unsigned n);
 692 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 693                                          unsigned n);
 694
 695 extern void __compiletime_error("usercopy buffer size is too small")
 696 __bad_copy_user(void);
 697
 698 static inline void copy_user_overflow(int size, unsigned long count)
 699 {
 700         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 701 }
 702
 703 static __always_inline unsigned long __must_check
 704 copy_from_user(void *to, const void __user *from, unsigned long n)
 705 {
 706         int sz = __compiletime_object_size(to);
 707
 708         might_fault();
 709
 710         kasan_check_write(to, n);
 711
 712         if (likely(sz < 0 || sz >= n)) {
 713                 check_object_size(to, n, false);
 714                 n = _copy_from_user(to, from, n);
 715         } else if (!__builtin_constant_p(n))
 716                 copy_user_overflow(sz, n);
 717         else
 718                 __bad_copy_user();
 719
 720         return n;
 721 }
 722
 723 static __always_inline unsigned long __must_check
 724 copy_to_user(void __user *to, const void *from, unsigned long n)
 725 {
 726         int sz = __compiletime_object_size(from);
 727
 728         kasan_check_read(from, n);
 729
 730         might_fault();
 731
 732         if (likely(sz < 0 || sz >= n)) {
 733                 check_object_size(from, n, true);
 734                 n = _copy_to_user(to, from, n);
 735         } else if (!__builtin_constant_p(n))
 736                 copy_user_overflow(sz, n);
 737         else
 738                 __bad_copy_user();
 739
 740         return n;
 741 }
 742
 743 /*
 744  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 745  * nested NMI paths are careful to preserve CR2.
 746  *
 747  * Caller must use pagefault_enable/disable, or run in interrupt context,
 748  * and also do a uaccess_ok() check
 749  */
 750 #define __copy_from_user_nmi __copy_from_user_inatomic
 751
 752 /*
 753  * The "unsafe" user accesses aren't really "unsafe", but the naming
 754  * is a big fat warning: you have to not only do the access_ok()
 755  * checking before using them, but you have to surround them with the
 756  * user_access_begin/end() pair.
 757  */
 758 #define user_access_begin()     __uaccess_begin()
 759 #define user_access_end()       __uaccess_end()
 760
 761 #define unsafe_put_user(x, ptr, err_label)                                      \
 762 do {                                                                            \
 763         int __pu_err;                                                           \
 764         __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);         \
 765         if (unlikely(__pu_err)) goto err_label;                                 \
 766 } while (0)
 767
 768 #define unsafe_get_user(x, ptr, err_label)                                      \
 769 do {                                                                            \
 770         int __gu_err;                                                           \
 771         unsigned long __gu_val;                                                 \
 772         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 773         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 774         if (unlikely(__gu_err)) goto err_label;                                 \
 775 } while (0)
 776
 777 #endif /* _ASM_X86_UACCESS_H */
 778