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  * @addr: User space pointer to start of block to check
  81  * @size: Size of block to check
  82  *
  83  * Context: User context only. This function may sleep if pagefaults are
  84  *          enabled.
  85  *
  86  * Checks if a pointer to a block of memory in user space is valid.
  87  *
  88  * Returns true (nonzero) if the memory block may be valid, false (zero)
  89  * if it is definitely invalid.
  90  *
  91  * Note that, depending on architecture, this function probably just
  92  * checks that the pointer is in the user space range - after calling
  93  * this function, memory access functions may still return -EFAULT.
  94  */
  95 #define access_ok(addr, size)                                   \
  96 ({                                                                      \
  97         WARN_ON_IN_IRQ();                                               \
  98         likely(!__range_not_ok(addr, size, user_addr_max()));           \
  99 })
 100
 101 /*
 102  * These are the main single-value transfer routines.  They automatically
 103  * use the right size if we just have the right pointer type.
 104  *
 105  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 106  * and yet we don't want to do any pointers, because that is too much
 107  * of a performance impact. Thus we have a few rather ugly macros here,
 108  * and hide all the ugliness from the user.
 109  *
 110  * The "__xxx" versions of the user access functions are versions that
 111  * do not verify the address space, that must have been done previously
 112  * with a separate "access_ok()" call (this is used when we do multiple
 113  * accesses to the same area of user memory).
 114  */
 115
 116 extern int __get_user_1(void);
 117 extern int __get_user_2(void);
 118 extern int __get_user_4(void);
 119 extern int __get_user_8(void);
 120 extern int __get_user_bad(void);
 121
 122 #define __uaccess_begin() stac()
 123 #define __uaccess_end()   clac()
 124 #define __uaccess_begin_nospec()        \
 125 ({                                      \
 126         stac();                         \
 127         barrier_nospec();               \
 128 })
 129
 130 /*
 131  * This is a type: either unsigned long, if the argument fits into
 132  * that type, or otherwise unsigned long long.
 133  */
 134 #define __inttype(x) \
 135 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 136
 137 /**
 138  * get_user: - Get a simple variable from user space.
 139  * @x:   Variable to store result.
 140  * @ptr: Source address, in user space.
 141  *
 142  * Context: User context only. This function may sleep if pagefaults are
 143  *          enabled.
 144  *
 145  * This macro copies a single simple variable from user space to kernel
 146  * space.  It supports simple types like char and int, but not larger
 147  * data types like structures or arrays.
 148  *
 149  * @ptr must have pointer-to-simple-variable type, and the result of
 150  * dereferencing @ptr must be assignable to @x without a cast.
 151  *
 152  * Returns zero on success, or -EFAULT on error.
 153  * On error, the variable @x is set to zero.
 154  */
 155 /*
 156  * Careful: we have to cast the result to the type of the pointer
 157  * for sign reasons.
 158  *
 159  * The use of _ASM_DX as the register specifier is a bit of a
 160  * simplification, as gcc only cares about it as the starting point
 161  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 162  * (%ecx being the next register in gcc's x86 register sequence), and
 163  * %rdx on 64 bits.
 164  *
 165  * Clang/LLVM cares about the size of the register, but still wants
 166  * the base register for something that ends up being a pair.
 167  */
 168 #define get_user(x, ptr)                                                \
 169 ({                                                                      \
 170         int __ret_gu;                                                   \
 171         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 172         __chk_user_ptr(ptr);                                            \
 173         might_fault();                                                  \
 174         asm volatile("call __get_user_%P4"                              \
 175                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 176                         ASM_CALL_CONSTRAINT                             \
 177                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 178         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 179         __builtin_expect(__ret_gu, 0);                                  \
 180 })
 181
 182 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 183         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 184                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 185
 186
 187
 188 #ifdef CONFIG_X86_32
 189 #define __put_user_goto_u64(x, addr, label)                     \
 190         asm_volatile_goto("\n"                                  \
 191                      "1:        movl %%eax,0(%1)\n"             \
 192                      "2:        movl %%edx,4(%1)\n"             \
 193                      _ASM_EXTABLE_UA(1b, %l2)                   \
 194                      _ASM_EXTABLE_UA(2b, %l2)                   \
 195                      : : "A" (x), "r" (addr)                    \
 196                      : : label)
 197
 198 #define __put_user_asm_ex_u64(x, addr)                                  \
 199         asm volatile("\n"                                               \
 200                      "1:        movl %%eax,0(%1)\n"                     \
 201                      "2:        movl %%edx,4(%1)\n"                     \
 202                      "3:"                                               \
 203                      _ASM_EXTABLE_EX(1b, 2b)                            \
 204                      _ASM_EXTABLE_EX(2b, 3b)                            \
 205                      : : "A" (x), "r" (addr))
 206
 207 #define __put_user_x8(x, ptr, __ret_pu)                         \
 208         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 209                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 210 #else
 211 #define __put_user_goto_u64(x, ptr, label) \
 212         __put_user_goto(x, ptr, "q", "", "er", label)
 213 #define __put_user_asm_ex_u64(x, addr)  \
 214         __put_user_asm_ex(x, addr, "q", "", "er")
 215 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 216 #endif
 217
 218 extern void __put_user_bad(void);
 219
 220 /*
 221  * Strange magic calling convention: pointer in %ecx,
 222  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 223  */
 224 extern void __put_user_1(void);
 225 extern void __put_user_2(void);
 226 extern void __put_user_4(void);
 227 extern void __put_user_8(void);
 228
 229 /**
 230  * put_user: - Write a simple value into user space.
 231  * @x:   Value to copy to user space.
 232  * @ptr: Destination address, in user space.
 233  *
 234  * Context: User context only. This function may sleep if pagefaults are
 235  *          enabled.
 236  *
 237  * This macro copies a single simple value from kernel space to user
 238  * space.  It supports simple types like char and int, but not larger
 239  * data types like structures or arrays.
 240  *
 241  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 242  * to the result of dereferencing @ptr.
 243  *
 244  * Returns zero on success, or -EFAULT on error.
 245  */
 246 #define put_user(x, ptr)                                        \
 247 ({                                                              \
 248         int __ret_pu;                                           \
 249         __typeof__(*(ptr)) __pu_val;                            \
 250         __chk_user_ptr(ptr);                                    \
 251         might_fault();                                          \
 252         __pu_val = x;                                           \
 253         switch (sizeof(*(ptr))) {                               \
 254         case 1:                                                 \
 255                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 256                 break;                                          \
 257         case 2:                                                 \
 258                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 259                 break;                                          \
 260         case 4:                                                 \
 261                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 262                 break;                                          \
 263         case 8:                                                 \
 264                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 265                 break;                                          \
 266         default:                                                \
 267                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 268                 break;                                          \
 269         }                                                       \
 270         __builtin_expect(__ret_pu, 0);                          \
 271 })
 272
 273 #define __put_user_size(x, ptr, size, label)                            \
 274 do {                                                                    \
 275         __chk_user_ptr(ptr);                                            \
 276         switch (size) {                                                 \
 277         case 1:                                                         \
 278                 __put_user_goto(x, ptr, "b", "b", "iq", label); \
 279                 break;                                                  \
 280         case 2:                                                         \
 281                 __put_user_goto(x, ptr, "w", "w", "ir", label);         \
 282                 break;                                                  \
 283         case 4:                                                         \
 284                 __put_user_goto(x, ptr, "l", "k", "ir", label);         \
 285                 break;                                                  \
 286         case 8:                                                         \
 287                 __put_user_goto_u64((__typeof__(*ptr))(x), ptr, label); \
 288                 break;                                                  \
 289         default:                                                        \
 290                 __put_user_bad();                                       \
 291         }                                                               \
 292 } while (0)
 293
 294 /*
 295  * This doesn't do __uaccess_begin/end - the exception handling
 296  * around it must do that.
 297  */
 298 #define __put_user_size_ex(x, ptr, size)                                \
 299 do {                                                                    \
 300         __chk_user_ptr(ptr);                                            \
 301         switch (size) {                                                 \
 302         case 1:                                                         \
 303                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 304                 break;                                                  \
 305         case 2:                                                         \
 306                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 307                 break;                                                  \
 308         case 4:                                                         \
 309                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 310                 break;                                                  \
 311         case 8:                                                         \
 312                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 313                 break;                                                  \
 314         default:                                                        \
 315                 __put_user_bad();                                       \
 316         }                                                               \
 317 } while (0)
 318
 319 #ifdef CONFIG_X86_32
 320 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 321 ({                                                                      \
 322         __typeof__(ptr) __ptr = (ptr);                                  \
 323         asm volatile("\n"                                       \
 324                      "1:        movl %2,%%eax\n"                        \
 325                      "2:        movl %3,%%edx\n"                        \
 326                      "3:\n"                             \
 327                      ".section .fixup,\"ax\"\n"                         \
 328                      "4:        mov %4,%0\n"                            \
 329                      "  xorl %%eax,%%eax\n"                             \
 330                      "  xorl %%edx,%%edx\n"                             \
 331                      "  jmp 3b\n"                                       \
 332                      ".previous\n"                                      \
 333                      _ASM_EXTABLE_UA(1b, 4b)                            \
 334                      _ASM_EXTABLE_UA(2b, 4b)                            \
 335                      : "=r" (retval), "=&A"(x)                          \
 336                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 337                        "i" (errret), "0" (retval));                     \
 338 })
 339
 340 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 341 #else
 342 #define __get_user_asm_u64(x, ptr, retval, errret) \
 343          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 344 #define __get_user_asm_ex_u64(x, ptr) \
 345          __get_user_asm_ex(x, ptr, "q", "", "=r")
 346 #endif
 347
 348 #define __get_user_size(x, ptr, size, retval, errret)                   \
 349 do {                                                                    \
 350         retval = 0;                                                     \
 351         __chk_user_ptr(ptr);                                            \
 352         switch (size) {                                                 \
 353         case 1:                                                         \
 354                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 355                 break;                                                  \
 356         case 2:                                                         \
 357                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 358                 break;                                                  \
 359         case 4:                                                         \
 360                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 361                 break;                                                  \
 362         case 8:                                                         \
 363                 __get_user_asm_u64(x, ptr, retval, errret);             \
 364                 break;                                                  \
 365         default:                                                        \
 366                 (x) = __get_user_bad();                                 \
 367         }                                                               \
 368 } while (0)
 369
 370 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 371         asm volatile("\n"                                               \
 372                      "1:        mov"itype" %2,%"rtype"1\n"              \
 373                      "2:\n"                                             \
 374                      ".section .fixup,\"ax\"\n"                         \
 375                      "3:        mov %3,%0\n"                            \
 376                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 377                      "  jmp 2b\n"                                       \
 378                      ".previous\n"                                      \
 379                      _ASM_EXTABLE_UA(1b, 3b)                            \
 380                      : "=r" (err), ltype(x)                             \
 381                      : "m" (__m(addr)), "i" (errret), "0" (err))
 382
 383 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 384         asm volatile("\n"                                               \
 385                      "1:        mov"itype" %2,%"rtype"1\n"              \
 386                      "2:\n"                                             \
 387                      ".section .fixup,\"ax\"\n"                         \
 388                      "3:        mov %3,%0\n"                            \
 389                      "  jmp 2b\n"                                       \
 390                      ".previous\n"                                      \
 391                      _ASM_EXTABLE_UA(1b, 3b)                            \
 392                      : "=r" (err), ltype(x)                             \
 393                      : "m" (__m(addr)), "i" (errret), "0" (err))
 394
 395 /*
 396  * This doesn't do __uaccess_begin/end - the exception handling
 397  * around it must do that.
 398  */
 399 #define __get_user_size_ex(x, ptr, size)                                \
 400 do {                                                                    \
 401         __chk_user_ptr(ptr);                                            \
 402         switch (size) {                                                 \
 403         case 1:                                                         \
 404                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 405                 break;                                                  \
 406         case 2:                                                         \
 407                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 408                 break;                                                  \
 409         case 4:                                                         \
 410                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 411                 break;                                                  \
 412         case 8:                                                         \
 413                 __get_user_asm_ex_u64(x, ptr);                          \
 414                 break;                                                  \
 415         default:                                                        \
 416                 (x) = __get_user_bad();                                 \
 417         }                                                               \
 418 } while (0)
 419
 420 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 421         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 422                      "2:\n"                                             \
 423                      ".section .fixup,\"ax\"\n"                         \
 424                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 425                      "  jmp 2b\n"                                       \
 426                      ".previous\n"                                      \
 427                      _ASM_EXTABLE_EX(1b, 3b)                            \
 428                      : ltype(x) : "m" (__m(addr)))
 429
 430 #define __put_user_nocheck(x, ptr, size)                        \
 431 ({                                                              \
 432         __label__ __pu_label;                                   \
 433         int __pu_err = -EFAULT;                                 \
 434         __uaccess_begin();                                      \
 435         __put_user_size((x), (ptr), (size), __pu_label);        \
 436         __pu_err = 0;                                           \
 437 __pu_label:                                                     \
 438         __uaccess_end();                                        \
 439         __builtin_expect(__pu_err, 0);                          \
 440 })
 441
 442 #define __get_user_nocheck(x, ptr, size)                                \
 443 ({                                                                      \
 444         int __gu_err;                                                   \
 445         __inttype(*(ptr)) __gu_val;                                     \
 446         __uaccess_begin_nospec();                                       \
 447         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 448         __uaccess_end();                                                \
 449         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 450         __builtin_expect(__gu_err, 0);                                  \
 451 })
 452
 453 /* FIXME: this hack is definitely wrong -AK */
 454 struct __large_struct { unsigned long buf[100]; };
 455 #define __m(x) (*(struct __large_struct __user *)(x))
 456
 457 /*
 458  * Tell gcc we read from memory instead of writing: this is because
 459  * we do not write to any memory gcc knows about, so there are no
 460  * aliasing issues.
 461  */
 462 #define __put_user_goto(x, addr, itype, rtype, ltype, label)    \
 463         asm_volatile_goto("\n"                                          \
 464                 "1:     mov"itype" %"rtype"0,%1\n"                      \
 465                 _ASM_EXTABLE_UA(1b, %l2)                                        \
 466                 : : ltype(x), "m" (__m(addr))                           \
 467                 : : label)
 468
 469 #define __put_user_failed(x, addr, itype, rtype, ltype, errret)         \
 470         ({      __label__ __puflab;                                     \
 471                 int __pufret = errret;                                  \
 472                 __put_user_goto(x,addr,itype,rtype,ltype,__puflab);     \
 473                 __pufret = 0;                                           \
 474         __puflab: __pufret; })
 475
 476 #define __put_user_asm(x, addr, retval, itype, rtype, ltype, errret)    do {    \
 477         retval = __put_user_failed(x, addr, itype, rtype, ltype, errret);       \
 478 } while (0)
 479
 480 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 481         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 482                      "2:\n"                                             \
 483                      _ASM_EXTABLE_EX(1b, 2b)                            \
 484                      : : ltype(x), "m" (__m(addr)))
 485
 486 /*
 487  * uaccess_try and catch
 488  */
 489 #define uaccess_try     do {                                            \
 490         current->thread.uaccess_err = 0;                                \
 491         __uaccess_begin();                                              \
 492         barrier();
 493
 494 #define uaccess_try_nospec do {                                         \
 495         current->thread.uaccess_err = 0;                                \
 496         __uaccess_begin_nospec();                                       \
 497
 498 #define uaccess_catch(err)                                              \
 499         __uaccess_end();                                                \
 500         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 501 } while (0)
 502
 503 /**
 504  * __get_user: - Get a simple variable from user space, with less checking.
 505  * @x:   Variable to store result.
 506  * @ptr: Source address, in user space.
 507  *
 508  * Context: User context only. This function may sleep if pagefaults are
 509  *          enabled.
 510  *
 511  * This macro copies a single simple variable from user space to kernel
 512  * space.  It supports simple types like char and int, but not larger
 513  * data types like structures or arrays.
 514  *
 515  * @ptr must have pointer-to-simple-variable type, and the result of
 516  * dereferencing @ptr must be assignable to @x without a cast.
 517  *
 518  * Caller must check the pointer with access_ok() before calling this
 519  * function.
 520  *
 521  * Returns zero on success, or -EFAULT on error.
 522  * On error, the variable @x is set to zero.
 523  */
 524
 525 #define __get_user(x, ptr)                                              \
 526         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 527
 528 /**
 529  * __put_user: - Write a simple value into user space, with less checking.
 530  * @x:   Value to copy to user space.
 531  * @ptr: Destination address, in user space.
 532  *
 533  * Context: User context only. This function may sleep if pagefaults are
 534  *          enabled.
 535  *
 536  * This macro copies a single simple value from kernel space to user
 537  * space.  It supports simple types like char and int, but not larger
 538  * data types like structures or arrays.
 539  *
 540  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 541  * to the result of dereferencing @ptr.
 542  *
 543  * Caller must check the pointer with access_ok() before calling this
 544  * function.
 545  *
 546  * Returns zero on success, or -EFAULT on error.
 547  */
 548
 549 #define __put_user(x, ptr)                                              \
 550         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 551
 552 /*
 553  * {get|put}_user_try and catch
 554  *
 555  * get_user_try {
 556  *      get_user_ex(...);
 557  * } get_user_catch(err)
 558  */
 559 #define get_user_try            uaccess_try_nospec
 560 #define get_user_catch(err)     uaccess_catch(err)
 561
 562 #define get_user_ex(x, ptr)     do {                                    \
 563         unsigned long __gue_val;                                        \
 564         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 565         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 566 } while (0)
 567
 568 #define put_user_try            uaccess_try
 569 #define put_user_catch(err)     uaccess_catch(err)
 570
 571 #define put_user_ex(x, ptr)                                             \
 572         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 573
 574 extern unsigned long
 575 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 576 extern __must_check long
 577 strncpy_from_user(char *dst, const char __user *src, long count);
 578
 579 extern __must_check long strnlen_user(const char __user *str, long n);
 580
 581 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 582 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 583
 584 extern void __cmpxchg_wrong_size(void)
 585         __compiletime_error("Bad argument size for cmpxchg");
 586
 587 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 588 ({                                                                      \
 589         int __ret = 0;                                                  \
 590         __typeof__(ptr) __uval = (uval);                                \
 591         __typeof__(*(ptr)) __old = (old);                               \
 592         __typeof__(*(ptr)) __new = (new);                               \
 593         __uaccess_begin_nospec();                                       \
 594         switch (size) {                                                 \
 595         case 1:                                                         \
 596         {                                                               \
 597                 asm volatile("\n"                                       \
 598                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 599                         "2:\n"                                          \
 600                         "\t.section .fixup, \"ax\"\n"                   \
 601                         "3:\tmov     %3, %0\n"                          \
 602                         "\tjmp     2b\n"                                \
 603                         "\t.previous\n"                                 \
 604                         _ASM_EXTABLE_UA(1b, 3b)                         \
 605                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 606                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 607                         : "memory"                                      \
 608                 );                                                      \
 609                 break;                                                  \
 610         }                                                               \
 611         case 2:                                                         \
 612         {                                                               \
 613                 asm volatile("\n"                                       \
 614                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 615                         "2:\n"                                          \
 616                         "\t.section .fixup, \"ax\"\n"                   \
 617                         "3:\tmov     %3, %0\n"                          \
 618                         "\tjmp     2b\n"                                \
 619                         "\t.previous\n"                                 \
 620                         _ASM_EXTABLE_UA(1b, 3b)                         \
 621                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 622                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 623                         : "memory"                                      \
 624                 );                                                      \
 625                 break;                                                  \
 626         }                                                               \
 627         case 4:                                                         \
 628         {                                                               \
 629                 asm volatile("\n"                                       \
 630                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 631                         "2:\n"                                          \
 632                         "\t.section .fixup, \"ax\"\n"                   \
 633                         "3:\tmov     %3, %0\n"                          \
 634                         "\tjmp     2b\n"                                \
 635                         "\t.previous\n"                                 \
 636                         _ASM_EXTABLE_UA(1b, 3b)                         \
 637                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 638                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 639                         : "memory"                                      \
 640                 );                                                      \
 641                 break;                                                  \
 642         }                                                               \
 643         case 8:                                                         \
 644         {                                                               \
 645                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 646                         __cmpxchg_wrong_size();                         \
 647                                                                         \
 648                 asm volatile("\n"                                       \
 649                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 650                         "2:\n"                                          \
 651                         "\t.section .fixup, \"ax\"\n"                   \
 652                         "3:\tmov     %3, %0\n"                          \
 653                         "\tjmp     2b\n"                                \
 654                         "\t.previous\n"                                 \
 655                         _ASM_EXTABLE_UA(1b, 3b)                         \
 656                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 657                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 658                         : "memory"                                      \
 659                 );                                                      \
 660                 break;                                                  \
 661         }                                                               \
 662         default:                                                        \
 663                 __cmpxchg_wrong_size();                                 \
 664         }                                                               \
 665         __uaccess_end();                                                \
 666         *__uval = __old;                                                \
 667         __ret;                                                          \
 668 })
 669
 670 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 671 ({                                                                      \
 672         access_ok((ptr), sizeof(*(ptr))) ?              \
 673                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 674                                 (old), (new), sizeof(*(ptr))) :         \
 675                 -EFAULT;                                                \
 676 })
 677
 678 /*
 679  * movsl can be slow when source and dest are not both 8-byte aligned
 680  */
 681 #ifdef CONFIG_X86_INTEL_USERCOPY
 682 extern struct movsl_mask {
 683         int mask;
 684 } ____cacheline_aligned_in_smp movsl_mask;
 685 #endif
 686
 687 #define ARCH_HAS_NOCACHE_UACCESS 1
 688
 689 #ifdef CONFIG_X86_32
 690 # include <asm/uaccess_32.h>
 691 #else
 692 # include <asm/uaccess_64.h>
 693 #endif
 694
 695 /*
 696  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 697  * nested NMI paths are careful to preserve CR2.
 698  *
 699  * Caller must use pagefault_enable/disable, or run in interrupt context,
 700  * and also do a uaccess_ok() check
 701  */
 702 #define __copy_from_user_nmi __copy_from_user_inatomic
 703
 704 /*
 705  * The "unsafe" user accesses aren't really "unsafe", but the naming
 706  * is a big fat warning: you have to not only do the access_ok()
 707  * checking before using them, but you have to surround them with the
 708  * user_access_begin/end() pair.
 709  */
 710 static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
 711 {
 712         if (unlikely(!access_ok(ptr,len)))
 713                 return 0;
 714         __uaccess_begin_nospec();
 715         return 1;
 716 }
 717 #define user_access_begin(a,b)  user_access_begin(a,b)
 718 #define user_access_end()       __uaccess_end()
 719
 720 #define unsafe_put_user(x, ptr, label)  \
 721         __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
 722
 723 #define unsafe_get_user(x, ptr, err_label)                                      \
 724 do {                                                                            \
 725         int __gu_err;                                                           \
 726         __inttype(*(ptr)) __gu_val;                                             \
 727         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 728         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 729         if (unlikely(__gu_err)) goto err_label;                                 \
 730 } while (0)
 731
 732 #endif /* _ASM_X86_UACCESS_H */
 733