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 #define __uaccess_begin_nospec()        \
 128 ({                                      \
 129         stac();                         \
 130         barrier_nospec();               \
 131 })
 132
 133 /*
 134  * This is a type: either unsigned long, if the argument fits into
 135  * that type, or otherwise unsigned long long.
 136  */
 137 #define __inttype(x) \
 138 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 139
 140 /**
 141  * get_user: - Get a simple variable from user space.
 142  * @x:   Variable to store result.
 143  * @ptr: Source address, in user space.
 144  *
 145  * Context: User context only. This function may sleep if pagefaults are
 146  *          enabled.
 147  *
 148  * This macro copies a single simple variable from user space to kernel
 149  * space.  It supports simple types like char and int, but not larger
 150  * data types like structures or arrays.
 151  *
 152  * @ptr must have pointer-to-simple-variable type, and the result of
 153  * dereferencing @ptr must be assignable to @x without a cast.
 154  *
 155  * Returns zero on success, or -EFAULT on error.
 156  * On error, the variable @x is set to zero.
 157  */
 158 /*
 159  * Careful: we have to cast the result to the type of the pointer
 160  * for sign reasons.
 161  *
 162  * The use of _ASM_DX as the register specifier is a bit of a
 163  * simplification, as gcc only cares about it as the starting point
 164  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 165  * (%ecx being the next register in gcc's x86 register sequence), and
 166  * %rdx on 64 bits.
 167  *
 168  * Clang/LLVM cares about the size of the register, but still wants
 169  * the base register for something that ends up being a pair.
 170  */
 171 #define get_user(x, ptr)                                                \
 172 ({                                                                      \
 173         int __ret_gu;                                                   \
 174         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 175         __chk_user_ptr(ptr);                                            \
 176         might_fault();                                                  \
 177         asm volatile("call __get_user_%P4"                              \
 178                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 179                         ASM_CALL_CONSTRAINT                             \
 180                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 181         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 182         __builtin_expect(__ret_gu, 0);                                  \
 183 })
 184
 185 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 186         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 187                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 188
 189
 190
 191 #ifdef CONFIG_X86_32
 192 #define __put_user_asm_u64(x, addr, err, errret)                        \
 193         asm volatile("\n"                                               \
 194                      "1:        movl %%eax,0(%2)\n"                     \
 195                      "2:        movl %%edx,4(%2)\n"                     \
 196                      "3:"                                               \
 197                      ".section .fixup,\"ax\"\n"                         \
 198                      "4:        movl %3,%0\n"                           \
 199                      "  jmp 3b\n"                                       \
 200                      ".previous\n"                                      \
 201                      _ASM_EXTABLE_UA(1b, 4b)                            \
 202                      _ASM_EXTABLE_UA(2b, 4b)                            \
 203                      : "=r" (err)                                       \
 204                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 205
 206 #define __put_user_asm_ex_u64(x, addr)                                  \
 207         asm volatile("\n"                                               \
 208                      "1:        movl %%eax,0(%1)\n"                     \
 209                      "2:        movl %%edx,4(%1)\n"                     \
 210                      "3:"                                               \
 211                      _ASM_EXTABLE_EX(1b, 2b)                            \
 212                      _ASM_EXTABLE_EX(2b, 3b)                            \
 213                      : : "A" (x), "r" (addr))
 214
 215 #define __put_user_x8(x, ptr, __ret_pu)                         \
 216         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 217                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 218 #else
 219 #define __put_user_asm_u64(x, ptr, retval, errret) \
 220         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 221 #define __put_user_asm_ex_u64(x, addr)  \
 222         __put_user_asm_ex(x, addr, "q", "", "er")
 223 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 224 #endif
 225
 226 extern void __put_user_bad(void);
 227
 228 /*
 229  * Strange magic calling convention: pointer in %ecx,
 230  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 231  */
 232 extern void __put_user_1(void);
 233 extern void __put_user_2(void);
 234 extern void __put_user_4(void);
 235 extern void __put_user_8(void);
 236
 237 /**
 238  * put_user: - Write a simple value into user space.
 239  * @x:   Value to copy to user space.
 240  * @ptr: Destination address, in user space.
 241  *
 242  * Context: User context only. This function may sleep if pagefaults are
 243  *          enabled.
 244  *
 245  * This macro copies a single simple value from kernel space to user
 246  * space.  It supports simple types like char and int, but not larger
 247  * data types like structures or arrays.
 248  *
 249  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 250  * to the result of dereferencing @ptr.
 251  *
 252  * Returns zero on success, or -EFAULT on error.
 253  */
 254 #define put_user(x, ptr)                                        \
 255 ({                                                              \
 256         int __ret_pu;                                           \
 257         __typeof__(*(ptr)) __pu_val;                            \
 258         __chk_user_ptr(ptr);                                    \
 259         might_fault();                                          \
 260         __pu_val = x;                                           \
 261         switch (sizeof(*(ptr))) {                               \
 262         case 1:                                                 \
 263                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 264                 break;                                          \
 265         case 2:                                                 \
 266                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 267                 break;                                          \
 268         case 4:                                                 \
 269                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 270                 break;                                          \
 271         case 8:                                                 \
 272                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 273                 break;                                          \
 274         default:                                                \
 275                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 276                 break;                                          \
 277         }                                                       \
 278         __builtin_expect(__ret_pu, 0);                          \
 279 })
 280
 281 #define __put_user_size(x, ptr, size, retval, errret)                   \
 282 do {                                                                    \
 283         retval = 0;                                                     \
 284         __chk_user_ptr(ptr);                                            \
 285         switch (size) {                                                 \
 286         case 1:                                                         \
 287                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 288                 break;                                                  \
 289         case 2:                                                         \
 290                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 291                 break;                                                  \
 292         case 4:                                                         \
 293                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 294                 break;                                                  \
 295         case 8:                                                         \
 296                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 297                                    errret);                             \
 298                 break;                                                  \
 299         default:                                                        \
 300                 __put_user_bad();                                       \
 301         }                                                               \
 302 } while (0)
 303
 304 /*
 305  * This doesn't do __uaccess_begin/end - the exception handling
 306  * around it must do that.
 307  */
 308 #define __put_user_size_ex(x, ptr, size)                                \
 309 do {                                                                    \
 310         __chk_user_ptr(ptr);                                            \
 311         switch (size) {                                                 \
 312         case 1:                                                         \
 313                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 314                 break;                                                  \
 315         case 2:                                                         \
 316                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 317                 break;                                                  \
 318         case 4:                                                         \
 319                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 320                 break;                                                  \
 321         case 8:                                                         \
 322                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 323                 break;                                                  \
 324         default:                                                        \
 325                 __put_user_bad();                                       \
 326         }                                                               \
 327 } while (0)
 328
 329 #ifdef CONFIG_X86_32
 330 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 331 ({                                                                      \
 332         __typeof__(ptr) __ptr = (ptr);                                  \
 333         asm volatile("\n"                                       \
 334                      "1:        movl %2,%%eax\n"                        \
 335                      "2:        movl %3,%%edx\n"                        \
 336                      "3:\n"                             \
 337                      ".section .fixup,\"ax\"\n"                         \
 338                      "4:        mov %4,%0\n"                            \
 339                      "  xorl %%eax,%%eax\n"                             \
 340                      "  xorl %%edx,%%edx\n"                             \
 341                      "  jmp 3b\n"                                       \
 342                      ".previous\n"                                      \
 343                      _ASM_EXTABLE_UA(1b, 4b)                            \
 344                      _ASM_EXTABLE_UA(2b, 4b)                            \
 345                      : "=r" (retval), "=&A"(x)                          \
 346                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 347                        "i" (errret), "0" (retval));                     \
 348 })
 349
 350 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 351 #else
 352 #define __get_user_asm_u64(x, ptr, retval, errret) \
 353          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 354 #define __get_user_asm_ex_u64(x, ptr) \
 355          __get_user_asm_ex(x, ptr, "q", "", "=r")
 356 #endif
 357
 358 #define __get_user_size(x, ptr, size, retval, errret)                   \
 359 do {                                                                    \
 360         retval = 0;                                                     \
 361         __chk_user_ptr(ptr);                                            \
 362         switch (size) {                                                 \
 363         case 1:                                                         \
 364                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 365                 break;                                                  \
 366         case 2:                                                         \
 367                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 368                 break;                                                  \
 369         case 4:                                                         \
 370                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 371                 break;                                                  \
 372         case 8:                                                         \
 373                 __get_user_asm_u64(x, ptr, retval, errret);             \
 374                 break;                                                  \
 375         default:                                                        \
 376                 (x) = __get_user_bad();                                 \
 377         }                                                               \
 378 } while (0)
 379
 380 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 381         asm volatile("\n"                                               \
 382                      "1:        mov"itype" %2,%"rtype"1\n"              \
 383                      "2:\n"                                             \
 384                      ".section .fixup,\"ax\"\n"                         \
 385                      "3:        mov %3,%0\n"                            \
 386                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 387                      "  jmp 2b\n"                                       \
 388                      ".previous\n"                                      \
 389                      _ASM_EXTABLE_UA(1b, 3b)                            \
 390                      : "=r" (err), ltype(x)                             \
 391                      : "m" (__m(addr)), "i" (errret), "0" (err))
 392
 393 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 394         asm volatile("\n"                                               \
 395                      "1:        mov"itype" %2,%"rtype"1\n"              \
 396                      "2:\n"                                             \
 397                      ".section .fixup,\"ax\"\n"                         \
 398                      "3:        mov %3,%0\n"                            \
 399                      "  jmp 2b\n"                                       \
 400                      ".previous\n"                                      \
 401                      _ASM_EXTABLE_UA(1b, 3b)                            \
 402                      : "=r" (err), ltype(x)                             \
 403                      : "m" (__m(addr)), "i" (errret), "0" (err))
 404
 405 /*
 406  * This doesn't do __uaccess_begin/end - the exception handling
 407  * around it must do that.
 408  */
 409 #define __get_user_size_ex(x, ptr, size)                                \
 410 do {                                                                    \
 411         __chk_user_ptr(ptr);                                            \
 412         switch (size) {                                                 \
 413         case 1:                                                         \
 414                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 415                 break;                                                  \
 416         case 2:                                                         \
 417                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 418                 break;                                                  \
 419         case 4:                                                         \
 420                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 421                 break;                                                  \
 422         case 8:                                                         \
 423                 __get_user_asm_ex_u64(x, ptr);                          \
 424                 break;                                                  \
 425         default:                                                        \
 426                 (x) = __get_user_bad();                                 \
 427         }                                                               \
 428 } while (0)
 429
 430 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 431         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 432                      "2:\n"                                             \
 433                      ".section .fixup,\"ax\"\n"                         \
 434                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 435                      "  jmp 2b\n"                                       \
 436                      ".previous\n"                                      \
 437                      _ASM_EXTABLE_EX(1b, 3b)                            \
 438                      : ltype(x) : "m" (__m(addr)))
 439
 440 #define __put_user_nocheck(x, ptr, size)                        \
 441 ({                                                              \
 442         int __pu_err;                                           \
 443         __uaccess_begin();                                      \
 444         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 445         __uaccess_end();                                        \
 446         __builtin_expect(__pu_err, 0);                          \
 447 })
 448
 449 #define __get_user_nocheck(x, ptr, size)                                \
 450 ({                                                                      \
 451         int __gu_err;                                                   \
 452         __inttype(*(ptr)) __gu_val;                                     \
 453         __uaccess_begin_nospec();                                       \
 454         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 455         __uaccess_end();                                                \
 456         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 457         __builtin_expect(__gu_err, 0);                                  \
 458 })
 459
 460 /* FIXME: this hack is definitely wrong -AK */
 461 struct __large_struct { unsigned long buf[100]; };
 462 #define __m(x) (*(struct __large_struct __user *)(x))
 463
 464 /*
 465  * Tell gcc we read from memory instead of writing: this is because
 466  * we do not write to any memory gcc knows about, so there are no
 467  * aliasing issues.
 468  */
 469 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 470         asm volatile("\n"                                               \
 471                      "1:        mov"itype" %"rtype"1,%2\n"              \
 472                      "2:\n"                                             \
 473                      ".section .fixup,\"ax\"\n"                         \
 474                      "3:        mov %3,%0\n"                            \
 475                      "  jmp 2b\n"                                       \
 476                      ".previous\n"                                      \
 477                      _ASM_EXTABLE_UA(1b, 3b)                            \
 478                      : "=r"(err)                                        \
 479                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 480
 481 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 482         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 483                      "2:\n"                                             \
 484                      _ASM_EXTABLE_EX(1b, 2b)                            \
 485                      : : ltype(x), "m" (__m(addr)))
 486
 487 /*
 488  * uaccess_try and catch
 489  */
 490 #define uaccess_try     do {                                            \
 491         current->thread.uaccess_err = 0;                                \
 492         __uaccess_begin();                                              \
 493         barrier();
 494
 495 #define uaccess_try_nospec do {                                         \
 496         current->thread.uaccess_err = 0;                                \
 497         __uaccess_begin_nospec();                                       \
 498
 499 #define uaccess_catch(err)                                              \
 500         __uaccess_end();                                                \
 501         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 502 } while (0)
 503
 504 /**
 505  * __get_user: - Get a simple variable from user space, with less checking.
 506  * @x:   Variable to store result.
 507  * @ptr: Source address, in user space.
 508  *
 509  * Context: User context only. This function may sleep if pagefaults are
 510  *          enabled.
 511  *
 512  * This macro copies a single simple variable from user space to kernel
 513  * space.  It supports simple types like char and int, but not larger
 514  * data types like structures or arrays.
 515  *
 516  * @ptr must have pointer-to-simple-variable type, and the result of
 517  * dereferencing @ptr must be assignable to @x without a cast.
 518  *
 519  * Caller must check the pointer with access_ok() before calling this
 520  * function.
 521  *
 522  * Returns zero on success, or -EFAULT on error.
 523  * On error, the variable @x is set to zero.
 524  */
 525
 526 #define __get_user(x, ptr)                                              \
 527         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 528
 529 /**
 530  * __put_user: - Write a simple value into user space, with less checking.
 531  * @x:   Value to copy to user space.
 532  * @ptr: Destination address, in user space.
 533  *
 534  * Context: User context only. This function may sleep if pagefaults are
 535  *          enabled.
 536  *
 537  * This macro copies a single simple value from kernel space to user
 538  * space.  It supports simple types like char and int, but not larger
 539  * data types like structures or arrays.
 540  *
 541  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 542  * to the result of dereferencing @ptr.
 543  *
 544  * Caller must check the pointer with access_ok() before calling this
 545  * function.
 546  *
 547  * Returns zero on success, or -EFAULT on error.
 548  */
 549
 550 #define __put_user(x, ptr)                                              \
 551         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 552
 553 /*
 554  * {get|put}_user_try and catch
 555  *
 556  * get_user_try {
 557  *      get_user_ex(...);
 558  * } get_user_catch(err)
 559  */
 560 #define get_user_try            uaccess_try_nospec
 561 #define get_user_catch(err)     uaccess_catch(err)
 562
 563 #define get_user_ex(x, ptr)     do {                                    \
 564         unsigned long __gue_val;                                        \
 565         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 566         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 567 } while (0)
 568
 569 #define put_user_try            uaccess_try
 570 #define put_user_catch(err)     uaccess_catch(err)
 571
 572 #define put_user_ex(x, ptr)                                             \
 573         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 574
 575 extern unsigned long
 576 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 577 extern __must_check long
 578 strncpy_from_user(char *dst, const char __user *src, long count);
 579
 580 extern __must_check long strnlen_user(const char __user *str, long n);
 581
 582 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 583 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 584
 585 extern void __cmpxchg_wrong_size(void)
 586         __compiletime_error("Bad argument size for cmpxchg");
 587
 588 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 589 ({                                                                      \
 590         int __ret = 0;                                                  \
 591         __typeof__(ptr) __uval = (uval);                                \
 592         __typeof__(*(ptr)) __old = (old);                               \
 593         __typeof__(*(ptr)) __new = (new);                               \
 594         __uaccess_begin_nospec();                                       \
 595         switch (size) {                                                 \
 596         case 1:                                                         \
 597         {                                                               \
 598                 asm volatile("\n"                                       \
 599                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 600                         "2:\n"                                          \
 601                         "\t.section .fixup, \"ax\"\n"                   \
 602                         "3:\tmov     %3, %0\n"                          \
 603                         "\tjmp     2b\n"                                \
 604                         "\t.previous\n"                                 \
 605                         _ASM_EXTABLE_UA(1b, 3b)                         \
 606                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 607                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 608                         : "memory"                                      \
 609                 );                                                      \
 610                 break;                                                  \
 611         }                                                               \
 612         case 2:                                                         \
 613         {                                                               \
 614                 asm volatile("\n"                                       \
 615                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 616                         "2:\n"                                          \
 617                         "\t.section .fixup, \"ax\"\n"                   \
 618                         "3:\tmov     %3, %0\n"                          \
 619                         "\tjmp     2b\n"                                \
 620                         "\t.previous\n"                                 \
 621                         _ASM_EXTABLE_UA(1b, 3b)                         \
 622                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 623                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 624                         : "memory"                                      \
 625                 );                                                      \
 626                 break;                                                  \
 627         }                                                               \
 628         case 4:                                                         \
 629         {                                                               \
 630                 asm volatile("\n"                                       \
 631                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 632                         "2:\n"                                          \
 633                         "\t.section .fixup, \"ax\"\n"                   \
 634                         "3:\tmov     %3, %0\n"                          \
 635                         "\tjmp     2b\n"                                \
 636                         "\t.previous\n"                                 \
 637                         _ASM_EXTABLE_UA(1b, 3b)                         \
 638                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 639                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 640                         : "memory"                                      \
 641                 );                                                      \
 642                 break;                                                  \
 643         }                                                               \
 644         case 8:                                                         \
 645         {                                                               \
 646                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 647                         __cmpxchg_wrong_size();                         \
 648                                                                         \
 649                 asm volatile("\n"                                       \
 650                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 651                         "2:\n"                                          \
 652                         "\t.section .fixup, \"ax\"\n"                   \
 653                         "3:\tmov     %3, %0\n"                          \
 654                         "\tjmp     2b\n"                                \
 655                         "\t.previous\n"                                 \
 656                         _ASM_EXTABLE_UA(1b, 3b)                         \
 657                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 658                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 659                         : "memory"                                      \
 660                 );                                                      \
 661                 break;                                                  \
 662         }                                                               \
 663         default:                                                        \
 664                 __cmpxchg_wrong_size();                                 \
 665         }                                                               \
 666         __uaccess_end();                                                \
 667         *__uval = __old;                                                \
 668         __ret;                                                          \
 669 })
 670
 671 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 672 ({                                                                      \
 673         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 674                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 675                                 (old), (new), sizeof(*(ptr))) :         \
 676                 -EFAULT;                                                \
 677 })
 678
 679 /*
 680  * movsl can be slow when source and dest are not both 8-byte aligned
 681  */
 682 #ifdef CONFIG_X86_INTEL_USERCOPY
 683 extern struct movsl_mask {
 684         int mask;
 685 } ____cacheline_aligned_in_smp movsl_mask;
 686 #endif
 687
 688 #define ARCH_HAS_NOCACHE_UACCESS 1
 689
 690 #ifdef CONFIG_X86_32
 691 # include <asm/uaccess_32.h>
 692 #else
 693 # include <asm/uaccess_64.h>
 694 #endif
 695
 696 /*
 697  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 698  * nested NMI paths are careful to preserve CR2.
 699  *
 700  * Caller must use pagefault_enable/disable, or run in interrupt context,
 701  * and also do a uaccess_ok() check
 702  */
 703 #define __copy_from_user_nmi __copy_from_user_inatomic
 704
 705 /*
 706  * The "unsafe" user accesses aren't really "unsafe", but the naming
 707  * is a big fat warning: you have to not only do the access_ok()
 708  * checking before using them, but you have to surround them with the
 709  * user_access_begin/end() pair.
 710  */
 711 #define user_access_begin()     __uaccess_begin()
 712 #define user_access_end()       __uaccess_end()
 713
 714 #define unsafe_put_user(x, ptr, err_label)                                      \
 715 do {                                                                            \
 716         int __pu_err;                                                           \
 717         __typeof__(*(ptr)) __pu_val = (x);                                      \
 718         __put_user_size(__pu_val, (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);    \
 719         if (unlikely(__pu_err)) goto err_label;                                 \
 720 } while (0)
 721
 722 #define unsafe_get_user(x, ptr, err_label)                                      \
 723 do {                                                                            \
 724         int __gu_err;                                                           \
 725         __inttype(*(ptr)) __gu_val;                                             \
 726         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 727         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 728         if (unlikely(__gu_err)) goto err_label;                                 \
 729 } while (0)
 730
 731 #endif /* _ASM_X86_UACCESS_H */
 732