arch/x86/include/asm/uaccess.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_UACCESS_H
   3 #define _ASM_X86_UACCESS_H
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/compiler.h>
   8 #include <linux/kasan-checks.h>
   9 #include <linux/string.h>
  10 #include <asm/asm.h>
  11 #include <asm/page.h>
  12 #include <asm/smap.h>
  13 #include <asm/extable.h>
  14
  15 /*
  16  * The fs value determines whether argument validity checking should be
  17  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  18  * get_fs() == KERNEL_DS, checking is bypassed.
  19  *
  20  * For historical reasons, these macros are grossly misnamed.
  21  */
  22
  23 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  24
  25 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  26 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  27
  28 #define get_ds()        (KERNEL_DS)
  29 #define get_fs()        (current->thread.addr_limit)
  30 static inline void set_fs(mm_segment_t fs)
  31 {
  32         current->thread.addr_limit = fs;
  33         /* On user-mode return, check fs is correct */
  34         set_thread_flag(TIF_FSCHECK);
  35 }
  36
  37 #define segment_eq(a, b)        ((a).seg == (b).seg)
  38
  39 #define user_addr_max() (current->thread.addr_limit.seg)
  40 #define __addr_ok(addr)         \
  41         ((unsigned long __force)(addr) < user_addr_max())
  42
  43 /*
  44  * Test whether a block of memory is a valid user space address.
  45  * Returns 0 if the range is valid, nonzero otherwise.
  46  */
  47 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  48 {
  49         /*
  50          * If we have used "sizeof()" for the size,
  51          * we know it won't overflow the limit (but
  52          * it might overflow the 'addr', so it's
  53          * important to subtract the size from the
  54          * limit, not add it to the address).
  55          */
  56         if (__builtin_constant_p(size))
  57                 return unlikely(addr > limit - size);
  58
  59         /* Arbitrary sizes? Be careful about overflow */
  60         addr += size;
  61         if (unlikely(addr < size))
  62                 return true;
  63         return unlikely(addr > limit);
  64 }
  65
  66 #define __range_not_ok(addr, size, limit)                               \
  67 ({                                                                      \
  68         __chk_user_ptr(addr);                                           \
  69         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  70 })
  71
  72 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  73 # define WARN_ON_IN_IRQ()       WARN_ON_ONCE(!in_task())
  74 #else
  75 # define WARN_ON_IN_IRQ()
  76 #endif
  77
  78 /**
  79  * access_ok: - Checks if a user space pointer is valid
  80  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  81  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  82  *        to write to a block, it is always safe to read from it.
  83  * @addr: User space pointer to start of block to check
  84  * @size: Size of block to check
  85  *
  86  * Context: User context only. This function may sleep if pagefaults are
  87  *          enabled.
  88  *
  89  * Checks if a pointer to a block of memory in user space is valid.
  90  *
  91  * Returns true (nonzero) if the memory block may be valid, false (zero)
  92  * if it is definitely invalid.
  93  *
  94  * Note that, depending on architecture, this function probably just
  95  * checks that the pointer is in the user space range - after calling
  96  * this function, memory access functions may still return -EFAULT.
  97  */
  98 #define access_ok(type, addr, size)                                     \
  99 ({                                                                      \
 100         WARN_ON_IN_IRQ();                                               \
 101         likely(!__range_not_ok(addr, size, user_addr_max()));           \
 102 })
 103
 104 /*
 105  * These are the main single-value transfer routines.  They automatically
 106  * use the right size if we just have the right pointer type.
 107  *
 108  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 109  * and yet we don't want to do any pointers, because that is too much
 110  * of a performance impact. Thus we have a few rather ugly macros here,
 111  * and hide all the ugliness from the user.
 112  *
 113  * The "__xxx" versions of the user access functions are versions that
 114  * do not verify the address space, that must have been done previously
 115  * with a separate "access_ok()" call (this is used when we do multiple
 116  * accesses to the same area of user memory).
 117  */
 118
 119 extern int __get_user_1(void);
 120 extern int __get_user_2(void);
 121 extern int __get_user_4(void);
 122 extern int __get_user_8(void);
 123 extern int __get_user_bad(void);
 124
 125 #define __uaccess_begin() stac()
 126 #define __uaccess_end()   clac()
 127
 128 /*
 129  * This is a type: either unsigned long, if the argument fits into
 130  * that type, or otherwise unsigned long long.
 131  */
 132 #define __inttype(x) \
 133 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 134
 135 /**
 136  * get_user: - Get a simple variable from user space.
 137  * @x:   Variable to store result.
 138  * @ptr: Source address, in user space.
 139  *
 140  * Context: User context only. This function may sleep if pagefaults are
 141  *          enabled.
 142  *
 143  * This macro copies a single simple variable from user space to kernel
 144  * space.  It supports simple types like char and int, but not larger
 145  * data types like structures or arrays.
 146  *
 147  * @ptr must have pointer-to-simple-variable type, and the result of
 148  * dereferencing @ptr must be assignable to @x without a cast.
 149  *
 150  * Returns zero on success, or -EFAULT on error.
 151  * On error, the variable @x is set to zero.
 152  */
 153 /*
 154  * Careful: we have to cast the result to the type of the pointer
 155  * for sign reasons.
 156  *
 157  * The use of _ASM_DX as the register specifier is a bit of a
 158  * simplification, as gcc only cares about it as the starting point
 159  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 160  * (%ecx being the next register in gcc's x86 register sequence), and
 161  * %rdx on 64 bits.
 162  *
 163  * Clang/LLVM cares about the size of the register, but still wants
 164  * the base register for something that ends up being a pair.
 165  */
 166 #define get_user(x, ptr)                                                \
 167 ({                                                                      \
 168         int __ret_gu;                                                   \
 169         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 170         __chk_user_ptr(ptr);                                            \
 171         might_fault();                                                  \
 172         asm volatile("call __get_user_%P4"                              \
 173                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 174                         ASM_CALL_CONSTRAINT                             \
 175                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 176         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 177         __builtin_expect(__ret_gu, 0);                                  \
 178 })
 179
 180 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 181         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 182                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 183
 184
 185
 186 #ifdef CONFIG_X86_32
 187 #define __put_user_asm_u64(x, addr, err, errret)                        \
 188         asm volatile("\n"                                               \
 189                      "1:        movl %%eax,0(%2)\n"                     \
 190                      "2:        movl %%edx,4(%2)\n"                     \
 191                      "3:"                                               \
 192                      ".section .fixup,\"ax\"\n"                         \
 193                      "4:        movl %3,%0\n"                           \
 194                      "  jmp 3b\n"                                       \
 195                      ".previous\n"                                      \
 196                      _ASM_EXTABLE(1b, 4b)                               \
 197                      _ASM_EXTABLE(2b, 4b)                               \
 198                      : "=r" (err)                                       \
 199                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 200
 201 #define __put_user_asm_ex_u64(x, addr)                                  \
 202         asm volatile("\n"                                               \
 203                      "1:        movl %%eax,0(%1)\n"                     \
 204                      "2:        movl %%edx,4(%1)\n"                     \
 205                      "3:"                                               \
 206                      _ASM_EXTABLE_EX(1b, 2b)                            \
 207                      _ASM_EXTABLE_EX(2b, 3b)                            \
 208                      : : "A" (x), "r" (addr))
 209
 210 #define __put_user_x8(x, ptr, __ret_pu)                         \
 211         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 212                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 213 #else
 214 #define __put_user_asm_u64(x, ptr, retval, errret) \
 215         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 216 #define __put_user_asm_ex_u64(x, addr)  \
 217         __put_user_asm_ex(x, addr, "q", "", "er")
 218 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 219 #endif
 220
 221 extern void __put_user_bad(void);
 222
 223 /*
 224  * Strange magic calling convention: pointer in %ecx,
 225  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 226  */
 227 extern void __put_user_1(void);
 228 extern void __put_user_2(void);
 229 extern void __put_user_4(void);
 230 extern void __put_user_8(void);
 231
 232 /**
 233  * put_user: - Write a simple value into user space.
 234  * @x:   Value to copy to user space.
 235  * @ptr: Destination address, in user space.
 236  *
 237  * Context: User context only. This function may sleep if pagefaults are
 238  *          enabled.
 239  *
 240  * This macro copies a single simple value from kernel space to user
 241  * space.  It supports simple types like char and int, but not larger
 242  * data types like structures or arrays.
 243  *
 244  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 245  * to the result of dereferencing @ptr.
 246  *
 247  * Returns zero on success, or -EFAULT on error.
 248  */
 249 #define put_user(x, ptr)                                        \
 250 ({                                                              \
 251         int __ret_pu;                                           \
 252         __typeof__(*(ptr)) __pu_val;                            \
 253         __chk_user_ptr(ptr);                                    \
 254         might_fault();                                          \
 255         __pu_val = x;                                           \
 256         switch (sizeof(*(ptr))) {                               \
 257         case 1:                                                 \
 258                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 259                 break;                                          \
 260         case 2:                                                 \
 261                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 262                 break;                                          \
 263         case 4:                                                 \
 264                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 265                 break;                                          \
 266         case 8:                                                 \
 267                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 268                 break;                                          \
 269         default:                                                \
 270                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 271                 break;                                          \
 272         }                                                       \
 273         __builtin_expect(__ret_pu, 0);                          \
 274 })
 275
 276 #define __put_user_size(x, ptr, size, retval, errret)                   \
 277 do {                                                                    \
 278         retval = 0;                                                     \
 279         __chk_user_ptr(ptr);                                            \
 280         switch (size) {                                                 \
 281         case 1:                                                         \
 282                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 283                 break;                                                  \
 284         case 2:                                                         \
 285                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 286                 break;                                                  \
 287         case 4:                                                         \
 288                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 289                 break;                                                  \
 290         case 8:                                                         \
 291                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 292                                    errret);                             \
 293                 break;                                                  \
 294         default:                                                        \
 295                 __put_user_bad();                                       \
 296         }                                                               \
 297 } while (0)
 298
 299 /*
 300  * This doesn't do __uaccess_begin/end - the exception handling
 301  * around it must do that.
 302  */
 303 #define __put_user_size_ex(x, ptr, size)                                \
 304 do {                                                                    \
 305         __chk_user_ptr(ptr);                                            \
 306         switch (size) {                                                 \
 307         case 1:                                                         \
 308                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 309                 break;                                                  \
 310         case 2:                                                         \
 311                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 312                 break;                                                  \
 313         case 4:                                                         \
 314                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 315                 break;                                                  \
 316         case 8:                                                         \
 317                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 318                 break;                                                  \
 319         default:                                                        \
 320                 __put_user_bad();                                       \
 321         }                                                               \
 322 } while (0)
 323
 324 #ifdef CONFIG_X86_32
 325 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 326 ({                                                                      \
 327         __typeof__(ptr) __ptr = (ptr);                                  \
 328         asm volatile("\n"                                       \
 329                      "1:        movl %2,%%eax\n"                        \
 330                      "2:        movl %3,%%edx\n"                        \
 331                      "3:\n"                             \
 332                      ".section .fixup,\"ax\"\n"                         \
 333                      "4:        mov %4,%0\n"                            \
 334                      "  xorl %%eax,%%eax\n"                             \
 335                      "  xorl %%edx,%%edx\n"                             \
 336                      "  jmp 3b\n"                                       \
 337                      ".previous\n"                                      \
 338                      _ASM_EXTABLE(1b, 4b)                               \
 339                      _ASM_EXTABLE(2b, 4b)                               \
 340                      : "=r" (retval), "=&A"(x)                          \
 341                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 342                        "i" (errret), "0" (retval));                     \
 343 })
 344
 345 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 346 #else
 347 #define __get_user_asm_u64(x, ptr, retval, errret) \
 348          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 349 #define __get_user_asm_ex_u64(x, ptr) \
 350          __get_user_asm_ex(x, ptr, "q", "", "=r")
 351 #endif
 352
 353 #define __get_user_size(x, ptr, size, retval, errret)                   \
 354 do {                                                                    \
 355         retval = 0;                                                     \
 356         __chk_user_ptr(ptr);                                            \
 357         switch (size) {                                                 \
 358         case 1:                                                         \
 359                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 360                 break;                                                  \
 361         case 2:                                                         \
 362                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 363                 break;                                                  \
 364         case 4:                                                         \
 365                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 366                 break;                                                  \
 367         case 8:                                                         \
 368                 __get_user_asm_u64(x, ptr, retval, errret);             \
 369                 break;                                                  \
 370         default:                                                        \
 371                 (x) = __get_user_bad();                                 \
 372         }                                                               \
 373 } while (0)
 374
 375 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 376         asm volatile("\n"                                               \
 377                      "1:        mov"itype" %2,%"rtype"1\n"              \
 378                      "2:\n"                                             \
 379                      ".section .fixup,\"ax\"\n"                         \
 380                      "3:        mov %3,%0\n"                            \
 381                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 382                      "  jmp 2b\n"                                       \
 383                      ".previous\n"                                      \
 384                      _ASM_EXTABLE(1b, 3b)                               \
 385                      : "=r" (err), ltype(x)                             \
 386                      : "m" (__m(addr)), "i" (errret), "0" (err))
 387
 388 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 389         asm volatile("\n"                                               \
 390                      "1:        mov"itype" %2,%"rtype"1\n"              \
 391                      "2:\n"                                             \
 392                      ".section .fixup,\"ax\"\n"                         \
 393                      "3:        mov %3,%0\n"                            \
 394                      "  jmp 2b\n"                                       \
 395                      ".previous\n"                                      \
 396                      _ASM_EXTABLE(1b, 3b)                               \
 397                      : "=r" (err), ltype(x)                             \
 398                      : "m" (__m(addr)), "i" (errret), "0" (err))
 399
 400 /*
 401  * This doesn't do __uaccess_begin/end - the exception handling
 402  * around it must do that.
 403  */
 404 #define __get_user_size_ex(x, ptr, size)                                \
 405 do {                                                                    \
 406         __chk_user_ptr(ptr);                                            \
 407         switch (size) {                                                 \
 408         case 1:                                                         \
 409                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 410                 break;                                                  \
 411         case 2:                                                         \
 412                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 413                 break;                                                  \
 414         case 4:                                                         \
 415                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 416                 break;                                                  \
 417         case 8:                                                         \
 418                 __get_user_asm_ex_u64(x, ptr);                          \
 419                 break;                                                  \
 420         default:                                                        \
 421                 (x) = __get_user_bad();                                 \
 422         }                                                               \
 423 } while (0)
 424
 425 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 426         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 427                      "2:\n"                                             \
 428                      ".section .fixup,\"ax\"\n"                         \
 429                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 430                      "  jmp 2b\n"                                       \
 431                      ".previous\n"                                      \
 432                      _ASM_EXTABLE_EX(1b, 3b)                            \
 433                      : ltype(x) : "m" (__m(addr)))
 434
 435 #define __put_user_nocheck(x, ptr, size)                        \
 436 ({                                                              \
 437         int __pu_err;                                           \
 438         __uaccess_begin();                                      \
 439         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 440         __uaccess_end();                                        \
 441         __builtin_expect(__pu_err, 0);                          \
 442 })
 443
 444 #define __get_user_nocheck(x, ptr, size)                                \
 445 ({                                                                      \
 446         int __gu_err;                                                   \
 447         __inttype(*(ptr)) __gu_val;                                     \
 448         __uaccess_begin();                                              \
 449         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 450         __uaccess_end();                                                \
 451         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 452         __builtin_expect(__gu_err, 0);                                  \
 453 })
 454
 455 /* FIXME: this hack is definitely wrong -AK */
 456 struct __large_struct { unsigned long buf[100]; };
 457 #define __m(x) (*(struct __large_struct __user *)(x))
 458
 459 /*
 460  * Tell gcc we read from memory instead of writing: this is because
 461  * we do not write to any memory gcc knows about, so there are no
 462  * aliasing issues.
 463  */
 464 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 465         asm volatile("\n"                                               \
 466                      "1:        mov"itype" %"rtype"1,%2\n"              \
 467                      "2:\n"                                             \
 468                      ".section .fixup,\"ax\"\n"                         \
 469                      "3:        mov %3,%0\n"                            \
 470                      "  jmp 2b\n"                                       \
 471                      ".previous\n"                                      \
 472                      _ASM_EXTABLE(1b, 3b)                               \
 473                      : "=r"(err)                                        \
 474                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 475
 476 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 477         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 478                      "2:\n"                                             \
 479                      _ASM_EXTABLE_EX(1b, 2b)                            \
 480                      : : ltype(x), "m" (__m(addr)))
 481
 482 /*
 483  * uaccess_try and catch
 484  */
 485 #define uaccess_try     do {                                            \
 486         current->thread.uaccess_err = 0;                                \
 487         __uaccess_begin();                                              \
 488         barrier();
 489
 490 #define uaccess_catch(err)                                              \
 491         __uaccess_end();                                                \
 492         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 493 } while (0)
 494
 495 /**
 496  * __get_user: - Get a simple variable from user space, with less checking.
 497  * @x:   Variable to store result.
 498  * @ptr: Source address, in user space.
 499  *
 500  * Context: User context only. This function may sleep if pagefaults are
 501  *          enabled.
 502  *
 503  * This macro copies a single simple variable from user space to kernel
 504  * space.  It supports simple types like char and int, but not larger
 505  * data types like structures or arrays.
 506  *
 507  * @ptr must have pointer-to-simple-variable type, and the result of
 508  * dereferencing @ptr must be assignable to @x without a cast.
 509  *
 510  * Caller must check the pointer with access_ok() before calling this
 511  * function.
 512  *
 513  * Returns zero on success, or -EFAULT on error.
 514  * On error, the variable @x is set to zero.
 515  */
 516
 517 #define __get_user(x, ptr)                                              \
 518         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 519
 520 /**
 521  * __put_user: - Write a simple value into user space, with less checking.
 522  * @x:   Value to copy to user space.
 523  * @ptr: Destination address, in user space.
 524  *
 525  * Context: User context only. This function may sleep if pagefaults are
 526  *          enabled.
 527  *
 528  * This macro copies a single simple value from kernel space to user
 529  * space.  It supports simple types like char and int, but not larger
 530  * data types like structures or arrays.
 531  *
 532  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 533  * to the result of dereferencing @ptr.
 534  *
 535  * Caller must check the pointer with access_ok() before calling this
 536  * function.
 537  *
 538  * Returns zero on success, or -EFAULT on error.
 539  */
 540
 541 #define __put_user(x, ptr)                                              \
 542         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 543
 544 /*
 545  * {get|put}_user_try and catch
 546  *
 547  * get_user_try {
 548  *      get_user_ex(...);
 549  * } get_user_catch(err)
 550  */
 551 #define get_user_try            uaccess_try
 552 #define get_user_catch(err)     uaccess_catch(err)
 553
 554 #define get_user_ex(x, ptr)     do {                                    \
 555         unsigned long __gue_val;                                        \
 556         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 557         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 558 } while (0)
 559
 560 #define put_user_try            uaccess_try
 561 #define put_user_catch(err)     uaccess_catch(err)
 562
 563 #define put_user_ex(x, ptr)                                             \
 564         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 565
 566 extern unsigned long
 567 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 568 extern __must_check long
 569 strncpy_from_user(char *dst, const char __user *src, long count);
 570
 571 extern __must_check long strnlen_user(const char __user *str, long n);
 572
 573 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 574 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 575
 576 extern void __cmpxchg_wrong_size(void)
 577         __compiletime_error("Bad argument size for cmpxchg");
 578
 579 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 580 ({                                                                      \
 581         int __ret = 0;                                                  \
 582         __typeof__(ptr) __uval = (uval);                                \
 583         __typeof__(*(ptr)) __old = (old);                               \
 584         __typeof__(*(ptr)) __new = (new);                               \
 585         __uaccess_begin();                                              \
 586         switch (size) {                                                 \
 587         case 1:                                                         \
 588         {                                                               \
 589                 asm volatile("\n"                                       \
 590                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 591                         "2:\n"                                          \
 592                         "\t.section .fixup, \"ax\"\n"                   \
 593                         "3:\tmov     %3, %0\n"                          \
 594                         "\tjmp     2b\n"                                \
 595                         "\t.previous\n"                                 \
 596                         _ASM_EXTABLE(1b, 3b)                            \
 597                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 598                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 599                         : "memory"                                      \
 600                 );                                                      \
 601                 break;                                                  \
 602         }                                                               \
 603         case 2:                                                         \
 604         {                                                               \
 605                 asm volatile("\n"                                       \
 606                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 607                         "2:\n"                                          \
 608                         "\t.section .fixup, \"ax\"\n"                   \
 609                         "3:\tmov     %3, %0\n"                          \
 610                         "\tjmp     2b\n"                                \
 611                         "\t.previous\n"                                 \
 612                         _ASM_EXTABLE(1b, 3b)                            \
 613                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 614                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 615                         : "memory"                                      \
 616                 );                                                      \
 617                 break;                                                  \
 618         }                                                               \
 619         case 4:                                                         \
 620         {                                                               \
 621                 asm volatile("\n"                                       \
 622                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 623                         "2:\n"                                          \
 624                         "\t.section .fixup, \"ax\"\n"                   \
 625                         "3:\tmov     %3, %0\n"                          \
 626                         "\tjmp     2b\n"                                \
 627                         "\t.previous\n"                                 \
 628                         _ASM_EXTABLE(1b, 3b)                            \
 629                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 630                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 631                         : "memory"                                      \
 632                 );                                                      \
 633                 break;                                                  \
 634         }                                                               \
 635         case 8:                                                         \
 636         {                                                               \
 637                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 638                         __cmpxchg_wrong_size();                         \
 639                                                                         \
 640                 asm volatile("\n"                                       \
 641                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 642                         "2:\n"                                          \
 643                         "\t.section .fixup, \"ax\"\n"                   \
 644                         "3:\tmov     %3, %0\n"                          \
 645                         "\tjmp     2b\n"                                \
 646                         "\t.previous\n"                                 \
 647                         _ASM_EXTABLE(1b, 3b)                            \
 648                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 649                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 650                         : "memory"                                      \
 651                 );                                                      \
 652                 break;                                                  \
 653         }                                                               \
 654         default:                                                        \
 655                 __cmpxchg_wrong_size();                                 \
 656         }                                                               \
 657         __uaccess_end();                                                \
 658         *__uval = __old;                                                \
 659         __ret;                                                          \
 660 })
 661
 662 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 663 ({                                                                      \
 664         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 665                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 666                                 (old), (new), sizeof(*(ptr))) :         \
 667                 -EFAULT;                                                \
 668 })
 669
 670 /*
 671  * movsl can be slow when source and dest are not both 8-byte aligned
 672  */
 673 #ifdef CONFIG_X86_INTEL_USERCOPY
 674 extern struct movsl_mask {
 675         int mask;
 676 } ____cacheline_aligned_in_smp movsl_mask;
 677 #endif
 678
 679 #define ARCH_HAS_NOCACHE_UACCESS 1
 680
 681 #ifdef CONFIG_X86_32
 682 # include <asm/uaccess_32.h>
 683 #else
 684 # include <asm/uaccess_64.h>
 685 #endif
 686
 687 /*
 688  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 689  * nested NMI paths are careful to preserve CR2.
 690  *
 691  * Caller must use pagefault_enable/disable, or run in interrupt context,
 692  * and also do a uaccess_ok() check
 693  */
 694 #define __copy_from_user_nmi __copy_from_user_inatomic
 695
 696 /*
 697  * The "unsafe" user accesses aren't really "unsafe", but the naming
 698  * is a big fat warning: you have to not only do the access_ok()
 699  * checking before using them, but you have to surround them with the
 700  * user_access_begin/end() pair.
 701  */
 702 #define user_access_begin()     __uaccess_begin()
 703 #define user_access_end()       __uaccess_end()
 704
 705 #define unsafe_put_user(x, ptr, err_label)                                      \
 706 do {                                                                            \
 707         int __pu_err;                                                           \
 708         __typeof__(*(ptr)) __pu_val = (x);                                      \
 709         __put_user_size(__pu_val, (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);    \
 710         if (unlikely(__pu_err)) goto err_label;                                 \
 711 } while (0)
 712
 713 #define unsafe_get_user(x, ptr, err_label)                                      \
 714 do {                                                                            \
 715         int __gu_err;                                                           \
 716         __inttype(*(ptr)) __gu_val;                                             \
 717         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 718         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 719         if (unlikely(__gu_err)) goto err_label;                                 \
 720 } while (0)
 721
 722 #endif /* _ASM_X86_UACCESS_H */
 723