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 #define user_addr_max() (current->thread.addr_limit.seg)
  39
  40 /*
  41  * Test whether a block of memory is a valid user space address.
  42  * Returns 0 if the range is valid, nonzero otherwise.
  43  */
  44 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  45 {
  46         /*
  47          * If we have used "sizeof()" for the size,
  48          * we know it won't overflow the limit (but
  49          * it might overflow the 'addr', so it's
  50          * important to subtract the size from the
  51          * limit, not add it to the address).
  52          */
  53         if (__builtin_constant_p(size))
  54                 return unlikely(addr > limit - size);
  55
  56         /* Arbitrary sizes? Be careful about overflow */
  57         addr += size;
  58         if (unlikely(addr < size))
  59                 return true;
  60         return unlikely(addr > limit);
  61 }
  62
  63 #define __range_not_ok(addr, size, limit)                               \
  64 ({                                                                      \
  65         __chk_user_ptr(addr);                                           \
  66         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  67 })
  68
  69 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  70 # define WARN_ON_IN_IRQ()       WARN_ON_ONCE(!in_task())
  71 #else
  72 # define WARN_ON_IN_IRQ()
  73 #endif
  74
  75 /**
  76  * access_ok: - Checks if a user space pointer is valid
  77  * @addr: User space pointer to start of block to check
  78  * @size: Size of block to check
  79  *
  80  * Context: User context only. This function may sleep if pagefaults are
  81  *          enabled.
  82  *
  83  * Checks if a pointer to a block of memory in user space is valid.
  84  *
  85  * Returns true (nonzero) if the memory block may be valid, false (zero)
  86  * if it is definitely invalid.
  87  *
  88  * Note that, depending on architecture, this function probably just
  89  * checks that the pointer is in the user space range - after calling
  90  * this function, memory access functions may still return -EFAULT.
  91  */
  92 #define access_ok(addr, size)                                   \
  93 ({                                                                      \
  94         WARN_ON_IN_IRQ();                                               \
  95         likely(!__range_not_ok(addr, size, user_addr_max()));           \
  96 })
  97
  98 /*
  99  * These are the main single-value transfer routines.  They automatically
 100  * use the right size if we just have the right pointer type.
 101  *
 102  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 103  * and yet we don't want to do any pointers, because that is too much
 104  * of a performance impact. Thus we have a few rather ugly macros here,
 105  * and hide all the ugliness from the user.
 106  *
 107  * The "__xxx" versions of the user access functions are versions that
 108  * do not verify the address space, that must have been done previously
 109  * with a separate "access_ok()" call (this is used when we do multiple
 110  * accesses to the same area of user memory).
 111  */
 112
 113 extern int __get_user_1(void);
 114 extern int __get_user_2(void);
 115 extern int __get_user_4(void);
 116 extern int __get_user_8(void);
 117 extern int __get_user_bad(void);
 118
 119 #define __uaccess_begin() stac()
 120 #define __uaccess_end()   clac()
 121 #define __uaccess_begin_nospec()        \
 122 ({                                      \
 123         stac();                         \
 124         barrier_nospec();               \
 125 })
 126
 127 /*
 128  * This is a type: either unsigned long, if the argument fits into
 129  * that type, or otherwise unsigned long long.
 130  */
 131 #define __inttype(x) \
 132 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 133
 134 /**
 135  * get_user: - Get a simple variable from user space.
 136  * @x:   Variable to store result.
 137  * @ptr: Source address, in user space.
 138  *
 139  * Context: User context only. This function may sleep if pagefaults are
 140  *          enabled.
 141  *
 142  * This macro copies a single simple variable from user space to kernel
 143  * space.  It supports simple types like char and int, but not larger
 144  * data types like structures or arrays.
 145  *
 146  * @ptr must have pointer-to-simple-variable type, and the result of
 147  * dereferencing @ptr must be assignable to @x without a cast.
 148  *
 149  * Returns zero on success, or -EFAULT on error.
 150  * On error, the variable @x is set to zero.
 151  */
 152 /*
 153  * Careful: we have to cast the result to the type of the pointer
 154  * for sign reasons.
 155  *
 156  * The use of _ASM_DX as the register specifier is a bit of a
 157  * simplification, as gcc only cares about it as the starting point
 158  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 159  * (%ecx being the next register in gcc's x86 register sequence), and
 160  * %rdx on 64 bits.
 161  *
 162  * Clang/LLVM cares about the size of the register, but still wants
 163  * the base register for something that ends up being a pair.
 164  */
 165 #define get_user(x, ptr)                                                \
 166 ({                                                                      \
 167         int __ret_gu;                                                   \
 168         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 169         __chk_user_ptr(ptr);                                            \
 170         might_fault();                                                  \
 171         asm volatile("call __get_user_%P4"                              \
 172                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 173                         ASM_CALL_CONSTRAINT                             \
 174                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 175         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 176         __builtin_expect(__ret_gu, 0);                                  \
 177 })
 178
 179 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 180         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 181                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 182
 183
 184
 185 #ifdef CONFIG_X86_32
 186 #define __put_user_goto_u64(x, addr, label)                     \
 187         asm_volatile_goto("\n"                                  \
 188                      "1:        movl %%eax,0(%1)\n"             \
 189                      "2:        movl %%edx,4(%1)\n"             \
 190                      _ASM_EXTABLE_UA(1b, %l2)                   \
 191                      _ASM_EXTABLE_UA(2b, %l2)                   \
 192                      : : "A" (x), "r" (addr)                    \
 193                      : : label)
 194
 195 #define __put_user_asm_ex_u64(x, addr)                                  \
 196         asm volatile("\n"                                               \
 197                      "1:        movl %%eax,0(%1)\n"                     \
 198                      "2:        movl %%edx,4(%1)\n"                     \
 199                      "3:"                                               \
 200                      _ASM_EXTABLE_EX(1b, 2b)                            \
 201                      _ASM_EXTABLE_EX(2b, 3b)                            \
 202                      : : "A" (x), "r" (addr))
 203
 204 #define __put_user_x8(x, ptr, __ret_pu)                         \
 205         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 206                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 207 #else
 208 #define __put_user_goto_u64(x, ptr, label) \
 209         __put_user_goto(x, ptr, "q", "", "er", label)
 210 #define __put_user_asm_ex_u64(x, addr)  \
 211         __put_user_asm_ex(x, addr, "q", "", "er")
 212 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 213 #endif
 214
 215 extern void __put_user_bad(void);
 216
 217 /*
 218  * Strange magic calling convention: pointer in %ecx,
 219  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 220  */
 221 extern void __put_user_1(void);
 222 extern void __put_user_2(void);
 223 extern void __put_user_4(void);
 224 extern void __put_user_8(void);
 225
 226 /**
 227  * put_user: - Write a simple value into user space.
 228  * @x:   Value to copy to user space.
 229  * @ptr: Destination address, in user space.
 230  *
 231  * Context: User context only. This function may sleep if pagefaults are
 232  *          enabled.
 233  *
 234  * This macro copies a single simple value from kernel space to user
 235  * space.  It supports simple types like char and int, but not larger
 236  * data types like structures or arrays.
 237  *
 238  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 239  * to the result of dereferencing @ptr.
 240  *
 241  * Returns zero on success, or -EFAULT on error.
 242  */
 243 #define put_user(x, ptr)                                        \
 244 ({                                                              \
 245         int __ret_pu;                                           \
 246         __typeof__(*(ptr)) __pu_val;                            \
 247         __chk_user_ptr(ptr);                                    \
 248         might_fault();                                          \
 249         __pu_val = x;                                           \
 250         switch (sizeof(*(ptr))) {                               \
 251         case 1:                                                 \
 252                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 253                 break;                                          \
 254         case 2:                                                 \
 255                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 256                 break;                                          \
 257         case 4:                                                 \
 258                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 259                 break;                                          \
 260         case 8:                                                 \
 261                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 262                 break;                                          \
 263         default:                                                \
 264                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 265                 break;                                          \
 266         }                                                       \
 267         __builtin_expect(__ret_pu, 0);                          \
 268 })
 269
 270 #define __put_user_size(x, ptr, size, label)                            \
 271 do {                                                                    \
 272         __chk_user_ptr(ptr);                                            \
 273         switch (size) {                                                 \
 274         case 1:                                                         \
 275                 __put_user_goto(x, ptr, "b", "b", "iq", label); \
 276                 break;                                                  \
 277         case 2:                                                         \
 278                 __put_user_goto(x, ptr, "w", "w", "ir", label);         \
 279                 break;                                                  \
 280         case 4:                                                         \
 281                 __put_user_goto(x, ptr, "l", "k", "ir", label);         \
 282                 break;                                                  \
 283         case 8:                                                         \
 284                 __put_user_goto_u64((__typeof__(*ptr))(x), ptr, label); \
 285                 break;                                                  \
 286         default:                                                        \
 287                 __put_user_bad();                                       \
 288         }                                                               \
 289 } while (0)
 290
 291 /*
 292  * This doesn't do __uaccess_begin/end - the exception handling
 293  * around it must do that.
 294  */
 295 #define __put_user_size_ex(x, ptr, size)                                \
 296 do {                                                                    \
 297         __chk_user_ptr(ptr);                                            \
 298         switch (size) {                                                 \
 299         case 1:                                                         \
 300                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 301                 break;                                                  \
 302         case 2:                                                         \
 303                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 304                 break;                                                  \
 305         case 4:                                                         \
 306                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 307                 break;                                                  \
 308         case 8:                                                         \
 309                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 310                 break;                                                  \
 311         default:                                                        \
 312                 __put_user_bad();                                       \
 313         }                                                               \
 314 } while (0)
 315
 316 #ifdef CONFIG_X86_32
 317 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 318 ({                                                                      \
 319         __typeof__(ptr) __ptr = (ptr);                                  \
 320         asm volatile("\n"                                       \
 321                      "1:        movl %2,%%eax\n"                        \
 322                      "2:        movl %3,%%edx\n"                        \
 323                      "3:\n"                             \
 324                      ".section .fixup,\"ax\"\n"                         \
 325                      "4:        mov %4,%0\n"                            \
 326                      "  xorl %%eax,%%eax\n"                             \
 327                      "  xorl %%edx,%%edx\n"                             \
 328                      "  jmp 3b\n"                                       \
 329                      ".previous\n"                                      \
 330                      _ASM_EXTABLE_UA(1b, 4b)                            \
 331                      _ASM_EXTABLE_UA(2b, 4b)                            \
 332                      : "=r" (retval), "=&A"(x)                          \
 333                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 334                        "i" (errret), "0" (retval));                     \
 335 })
 336
 337 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 338 #else
 339 #define __get_user_asm_u64(x, ptr, retval, errret) \
 340          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 341 #define __get_user_asm_ex_u64(x, ptr) \
 342          __get_user_asm_ex(x, ptr, "q", "", "=r")
 343 #endif
 344
 345 #define __get_user_size(x, ptr, size, retval, errret)                   \
 346 do {                                                                    \
 347         retval = 0;                                                     \
 348         __chk_user_ptr(ptr);                                            \
 349         switch (size) {                                                 \
 350         case 1:                                                         \
 351                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 352                 break;                                                  \
 353         case 2:                                                         \
 354                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 355                 break;                                                  \
 356         case 4:                                                         \
 357                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 358                 break;                                                  \
 359         case 8:                                                         \
 360                 __get_user_asm_u64(x, ptr, retval, errret);             \
 361                 break;                                                  \
 362         default:                                                        \
 363                 (x) = __get_user_bad();                                 \
 364         }                                                               \
 365 } while (0)
 366
 367 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 368         asm volatile("\n"                                               \
 369                      "1:        mov"itype" %2,%"rtype"1\n"              \
 370                      "2:\n"                                             \
 371                      ".section .fixup,\"ax\"\n"                         \
 372                      "3:        mov %3,%0\n"                            \
 373                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 374                      "  jmp 2b\n"                                       \
 375                      ".previous\n"                                      \
 376                      _ASM_EXTABLE_UA(1b, 3b)                            \
 377                      : "=r" (err), ltype(x)                             \
 378                      : "m" (__m(addr)), "i" (errret), "0" (err))
 379
 380 #define __get_user_asm_nozero(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                      "  jmp 2b\n"                                       \
 387                      ".previous\n"                                      \
 388                      _ASM_EXTABLE_UA(1b, 3b)                            \
 389                      : "=r" (err), ltype(x)                             \
 390                      : "m" (__m(addr)), "i" (errret), "0" (err))
 391
 392 /*
 393  * This doesn't do __uaccess_begin/end - the exception handling
 394  * around it must do that.
 395  */
 396 #define __get_user_size_ex(x, ptr, size)                                \
 397 do {                                                                    \
 398         __chk_user_ptr(ptr);                                            \
 399         switch (size) {                                                 \
 400         case 1:                                                         \
 401                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 402                 break;                                                  \
 403         case 2:                                                         \
 404                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 405                 break;                                                  \
 406         case 4:                                                         \
 407                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 408                 break;                                                  \
 409         case 8:                                                         \
 410                 __get_user_asm_ex_u64(x, ptr);                          \
 411                 break;                                                  \
 412         default:                                                        \
 413                 (x) = __get_user_bad();                                 \
 414         }                                                               \
 415 } while (0)
 416
 417 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 418         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 419                      "2:\n"                                             \
 420                      ".section .fixup,\"ax\"\n"                         \
 421                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 422                      "  jmp 2b\n"                                       \
 423                      ".previous\n"                                      \
 424                      _ASM_EXTABLE_EX(1b, 3b)                            \
 425                      : ltype(x) : "m" (__m(addr)))
 426
 427 #define __put_user_nocheck(x, ptr, size)                        \
 428 ({                                                              \
 429         __label__ __pu_label;                                   \
 430         int __pu_err = -EFAULT;                                 \
 431         __uaccess_begin();                                      \
 432         __put_user_size((x), (ptr), (size), __pu_label);        \
 433         __pu_err = 0;                                           \
 434 __pu_label:                                                     \
 435         __uaccess_end();                                        \
 436         __builtin_expect(__pu_err, 0);                          \
 437 })
 438
 439 #define __get_user_nocheck(x, ptr, size)                                \
 440 ({                                                                      \
 441         int __gu_err;                                                   \
 442         __inttype(*(ptr)) __gu_val;                                     \
 443         __uaccess_begin_nospec();                                       \
 444         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 445         __uaccess_end();                                                \
 446         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 447         __builtin_expect(__gu_err, 0);                                  \
 448 })
 449
 450 /* FIXME: this hack is definitely wrong -AK */
 451 struct __large_struct { unsigned long buf[100]; };
 452 #define __m(x) (*(struct __large_struct __user *)(x))
 453
 454 /*
 455  * Tell gcc we read from memory instead of writing: this is because
 456  * we do not write to any memory gcc knows about, so there are no
 457  * aliasing issues.
 458  */
 459 #define __put_user_goto(x, addr, itype, rtype, ltype, label)    \
 460         asm_volatile_goto("\n"                                          \
 461                 "1:     mov"itype" %"rtype"0,%1\n"                      \
 462                 _ASM_EXTABLE_UA(1b, %l2)                                        \
 463                 : : ltype(x), "m" (__m(addr))                           \
 464                 : : label)
 465
 466 #define __put_user_failed(x, addr, itype, rtype, ltype, errret)         \
 467         ({      __label__ __puflab;                                     \
 468                 int __pufret = errret;                                  \
 469                 __put_user_goto(x,addr,itype,rtype,ltype,__puflab);     \
 470                 __pufret = 0;                                           \
 471         __puflab: __pufret; })
 472
 473 #define __put_user_asm(x, addr, retval, itype, rtype, ltype, errret)    do {    \
 474         retval = __put_user_failed(x, addr, itype, rtype, ltype, errret);       \
 475 } while (0)
 476
 477 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 478         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 479                      "2:\n"                                             \
 480                      _ASM_EXTABLE_EX(1b, 2b)                            \
 481                      : : ltype(x), "m" (__m(addr)))
 482
 483 /*
 484  * uaccess_try and catch
 485  */
 486 #define uaccess_try     do {                                            \
 487         current->thread.uaccess_err = 0;                                \
 488         __uaccess_begin();                                              \
 489         barrier();
 490
 491 #define uaccess_try_nospec do {                                         \
 492         current->thread.uaccess_err = 0;                                \
 493         __uaccess_begin_nospec();                                       \
 494
 495 #define uaccess_catch(err)                                              \
 496         __uaccess_end();                                                \
 497         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 498 } while (0)
 499
 500 /**
 501  * __get_user: - Get a simple variable from user space, with less checking.
 502  * @x:   Variable to store result.
 503  * @ptr: Source address, in user space.
 504  *
 505  * Context: User context only. This function may sleep if pagefaults are
 506  *          enabled.
 507  *
 508  * This macro copies a single simple variable from user space to kernel
 509  * space.  It supports simple types like char and int, but not larger
 510  * data types like structures or arrays.
 511  *
 512  * @ptr must have pointer-to-simple-variable type, and the result of
 513  * dereferencing @ptr must be assignable to @x without a cast.
 514  *
 515  * Caller must check the pointer with access_ok() before calling this
 516  * function.
 517  *
 518  * Returns zero on success, or -EFAULT on error.
 519  * On error, the variable @x is set to zero.
 520  */
 521
 522 #define __get_user(x, ptr)                                              \
 523         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 524
 525 /**
 526  * __put_user: - Write a simple value into user space, with less checking.
 527  * @x:   Value to copy to user space.
 528  * @ptr: Destination address, in user space.
 529  *
 530  * Context: User context only. This function may sleep if pagefaults are
 531  *          enabled.
 532  *
 533  * This macro copies a single simple value from kernel space to user
 534  * space.  It supports simple types like char and int, but not larger
 535  * data types like structures or arrays.
 536  *
 537  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 538  * to the result of dereferencing @ptr.
 539  *
 540  * Caller must check the pointer with access_ok() before calling this
 541  * function.
 542  *
 543  * Returns zero on success, or -EFAULT on error.
 544  */
 545
 546 #define __put_user(x, ptr)                                              \
 547         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 548
 549 /*
 550  * {get|put}_user_try and catch
 551  *
 552  * get_user_try {
 553  *      get_user_ex(...);
 554  * } get_user_catch(err)
 555  */
 556 #define get_user_try            uaccess_try_nospec
 557 #define get_user_catch(err)     uaccess_catch(err)
 558
 559 #define get_user_ex(x, ptr)     do {                                    \
 560         unsigned long __gue_val;                                        \
 561         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 562         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 563 } while (0)
 564
 565 #define put_user_try            uaccess_try
 566 #define put_user_catch(err)     uaccess_catch(err)
 567
 568 #define put_user_ex(x, ptr)                                             \
 569         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 570
 571 extern unsigned long
 572 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 573 extern __must_check long
 574 strncpy_from_user(char *dst, const char __user *src, long count);
 575
 576 extern __must_check long strnlen_user(const char __user *str, long n);
 577
 578 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 579 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 580
 581 extern void __cmpxchg_wrong_size(void)
 582         __compiletime_error("Bad argument size for cmpxchg");
 583
 584 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 585 ({                                                                      \
 586         int __ret = 0;                                                  \
 587         __typeof__(ptr) __uval = (uval);                                \
 588         __typeof__(*(ptr)) __old = (old);                               \
 589         __typeof__(*(ptr)) __new = (new);                               \
 590         __uaccess_begin_nospec();                                       \
 591         switch (size) {                                                 \
 592         case 1:                                                         \
 593         {                                                               \
 594                 asm volatile("\n"                                       \
 595                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 596                         "2:\n"                                          \
 597                         "\t.section .fixup, \"ax\"\n"                   \
 598                         "3:\tmov     %3, %0\n"                          \
 599                         "\tjmp     2b\n"                                \
 600                         "\t.previous\n"                                 \
 601                         _ASM_EXTABLE_UA(1b, 3b)                         \
 602                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 603                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 604                         : "memory"                                      \
 605                 );                                                      \
 606                 break;                                                  \
 607         }                                                               \
 608         case 2:                                                         \
 609         {                                                               \
 610                 asm volatile("\n"                                       \
 611                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 612                         "2:\n"                                          \
 613                         "\t.section .fixup, \"ax\"\n"                   \
 614                         "3:\tmov     %3, %0\n"                          \
 615                         "\tjmp     2b\n"                                \
 616                         "\t.previous\n"                                 \
 617                         _ASM_EXTABLE_UA(1b, 3b)                         \
 618                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 619                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 620                         : "memory"                                      \
 621                 );                                                      \
 622                 break;                                                  \
 623         }                                                               \
 624         case 4:                                                         \
 625         {                                                               \
 626                 asm volatile("\n"                                       \
 627                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 628                         "2:\n"                                          \
 629                         "\t.section .fixup, \"ax\"\n"                   \
 630                         "3:\tmov     %3, %0\n"                          \
 631                         "\tjmp     2b\n"                                \
 632                         "\t.previous\n"                                 \
 633                         _ASM_EXTABLE_UA(1b, 3b)                         \
 634                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 635                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 636                         : "memory"                                      \
 637                 );                                                      \
 638                 break;                                                  \
 639         }                                                               \
 640         case 8:                                                         \
 641         {                                                               \
 642                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 643                         __cmpxchg_wrong_size();                         \
 644                                                                         \
 645                 asm volatile("\n"                                       \
 646                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 647                         "2:\n"                                          \
 648                         "\t.section .fixup, \"ax\"\n"                   \
 649                         "3:\tmov     %3, %0\n"                          \
 650                         "\tjmp     2b\n"                                \
 651                         "\t.previous\n"                                 \
 652                         _ASM_EXTABLE_UA(1b, 3b)                         \
 653                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 654                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 655                         : "memory"                                      \
 656                 );                                                      \
 657                 break;                                                  \
 658         }                                                               \
 659         default:                                                        \
 660                 __cmpxchg_wrong_size();                                 \
 661         }                                                               \
 662         __uaccess_end();                                                \
 663         *__uval = __old;                                                \
 664         __ret;                                                          \
 665 })
 666
 667 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 668 ({                                                                      \
 669         access_ok((ptr), sizeof(*(ptr))) ?              \
 670                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 671                                 (old), (new), sizeof(*(ptr))) :         \
 672                 -EFAULT;                                                \
 673 })
 674
 675 /*
 676  * movsl can be slow when source and dest are not both 8-byte aligned
 677  */
 678 #ifdef CONFIG_X86_INTEL_USERCOPY
 679 extern struct movsl_mask {
 680         int mask;
 681 } ____cacheline_aligned_in_smp movsl_mask;
 682 #endif
 683
 684 #define ARCH_HAS_NOCACHE_UACCESS 1
 685
 686 #ifdef CONFIG_X86_32
 687 # include <asm/uaccess_32.h>
 688 #else
 689 # include <asm/uaccess_64.h>
 690 #endif
 691
 692 /*
 693  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 694  * nested NMI paths are careful to preserve CR2.
 695  *
 696  * Caller must use pagefault_enable/disable, or run in interrupt context,
 697  * and also do a uaccess_ok() check
 698  */
 699 #define __copy_from_user_nmi __copy_from_user_inatomic
 700
 701 /*
 702  * The "unsafe" user accesses aren't really "unsafe", but the naming
 703  * is a big fat warning: you have to not only do the access_ok()
 704  * checking before using them, but you have to surround them with the
 705  * user_access_begin/end() pair.
 706  */
 707 static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
 708 {
 709         if (unlikely(!access_ok(ptr,len)))
 710                 return 0;
 711         __uaccess_begin();
 712         return 1;
 713 }
 714 #define user_access_begin(a,b)  user_access_begin(a,b)
 715 #define user_access_end()       __uaccess_end()
 716
 717 #define unsafe_put_user(x, ptr, label)  \
 718         __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
 719
 720 #define unsafe_get_user(x, ptr, err_label)                                      \
 721 do {                                                                            \
 722         int __gu_err;                                                           \
 723         __inttype(*(ptr)) __gu_val;                                             \
 724         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 725         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 726         if (unlikely(__gu_err)) goto err_label;                                 \
 727 } while (0)
 728
 729 #endif /* _ASM_X86_UACCESS_H */
 730