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_fs()        (current->thread.addr_limit)
  29 static inline void set_fs(mm_segment_t fs)
  30 {
  31         current->thread.addr_limit = fs;
  32         /* On user-mode return, check fs is correct */
  33         set_thread_flag(TIF_FSCHECK);
  34 }
  35
  36 #define segment_eq(a, b)        ((a).seg == (b).seg)
  37
  38 #define user_addr_max() (current->thread.addr_limit.seg)
  39 #define __addr_ok(addr)         \
  40         ((unsigned long __force)(addr) < user_addr_max())
  41
  42 /*
  43  * Test whether a block of memory is a valid user space address.
  44  * Returns 0 if the range is valid, nonzero otherwise.
  45  */
  46 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  47 {
  48         /*
  49          * If we have used "sizeof()" for the size,
  50          * we know it won't overflow the limit (but
  51          * it might overflow the 'addr', so it's
  52          * important to subtract the size from the
  53          * limit, not add it to the address).
  54          */
  55         if (__builtin_constant_p(size))
  56                 return unlikely(addr > limit - size);
  57
  58         /* Arbitrary sizes? Be careful about overflow */
  59         addr += size;
  60         if (unlikely(addr < size))
  61                 return true;
  62         return unlikely(addr > limit);
  63 }
  64
  65 #define __range_not_ok(addr, size, limit)                               \
  66 ({                                                                      \
  67         __chk_user_ptr(addr);                                           \
  68         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  69 })
  70
  71 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
  72 # define WARN_ON_IN_IRQ()       WARN_ON_ONCE(!in_task())
  73 #else
  74 # define WARN_ON_IN_IRQ()
  75 #endif
  76
  77 /**
  78  * access_ok: - Checks if a user space pointer is valid
  79  * @addr: User space pointer to start of block to check
  80  * @size: Size of block to check
  81  *
  82  * Context: User context only. This function may sleep if pagefaults are
  83  *          enabled.
  84  *
  85  * Checks if a pointer to a block of memory in user space is valid.
  86  *
  87  * Returns true (nonzero) if the memory block may be valid, false (zero)
  88  * if it is definitely invalid.
  89  *
  90  * Note that, depending on architecture, this function probably just
  91  * checks that the pointer is in the user space range - after calling
  92  * this function, memory access functions may still return -EFAULT.
  93  */
  94 #define access_ok(addr, size)                                   \
  95 ({                                                                      \
  96         WARN_ON_IN_IRQ();                                               \
  97         likely(!__range_not_ok(addr, size, user_addr_max()));           \
  98 })
  99
 100 /*
 101  * These are the main single-value transfer routines.  They automatically
 102  * use the right size if we just have the right pointer type.
 103  *
 104  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 105  * and yet we don't want to do any pointers, because that is too much
 106  * of a performance impact. Thus we have a few rather ugly macros here,
 107  * and hide all the ugliness from the user.
 108  *
 109  * The "__xxx" versions of the user access functions are versions that
 110  * do not verify the address space, that must have been done previously
 111  * with a separate "access_ok()" call (this is used when we do multiple
 112  * accesses to the same area of user memory).
 113  */
 114
 115 extern int __get_user_1(void);
 116 extern int __get_user_2(void);
 117 extern int __get_user_4(void);
 118 extern int __get_user_8(void);
 119 extern int __get_user_bad(void);
 120
 121 #define __uaccess_begin() stac()
 122 #define __uaccess_end()   clac()
 123 #define __uaccess_begin_nospec()        \
 124 ({                                      \
 125         stac();                         \
 126         barrier_nospec();               \
 127 })
 128
 129 /*
 130  * This is a type: either unsigned long, if the argument fits into
 131  * that type, or otherwise unsigned long long.
 132  */
 133 #define __inttype(x) \
 134 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 135
 136 /**
 137  * get_user: - Get a simple variable from user space.
 138  * @x:   Variable to store result.
 139  * @ptr: Source address, in user space.
 140  *
 141  * Context: User context only. This function may sleep if pagefaults are
 142  *          enabled.
 143  *
 144  * This macro copies a single simple variable from user space to kernel
 145  * space.  It supports simple types like char and int, but not larger
 146  * data types like structures or arrays.
 147  *
 148  * @ptr must have pointer-to-simple-variable type, and the result of
 149  * dereferencing @ptr must be assignable to @x without a cast.
 150  *
 151  * Returns zero on success, or -EFAULT on error.
 152  * On error, the variable @x is set to zero.
 153  */
 154 /*
 155  * Careful: we have to cast the result to the type of the pointer
 156  * for sign reasons.
 157  *
 158  * The use of _ASM_DX as the register specifier is a bit of a
 159  * simplification, as gcc only cares about it as the starting point
 160  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 161  * (%ecx being the next register in gcc's x86 register sequence), and
 162  * %rdx on 64 bits.
 163  *
 164  * Clang/LLVM cares about the size of the register, but still wants
 165  * the base register for something that ends up being a pair.
 166  */
 167 #define get_user(x, ptr)                                                \
 168 ({                                                                      \
 169         int __ret_gu;                                                   \
 170         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 171         __chk_user_ptr(ptr);                                            \
 172         might_fault();                                                  \
 173         asm volatile("call __get_user_%P4"                              \
 174                      : "=a" (__ret_gu), "=r" (__val_gu),                \
 175                         ASM_CALL_CONSTRAINT                             \
 176                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 177         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 178         __builtin_expect(__ret_gu, 0);                                  \
 179 })
 180
 181 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 182         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 183                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 184
 185
 186
 187 #ifdef CONFIG_X86_32
 188 #define __put_user_goto_u64(x, addr, label)                     \
 189         asm_volatile_goto("\n"                                  \
 190                      "1:        movl %%eax,0(%1)\n"             \
 191                      "2:        movl %%edx,4(%1)\n"             \
 192                      _ASM_EXTABLE_UA(1b, %l2)                   \
 193                      _ASM_EXTABLE_UA(2b, %l2)                   \
 194                      : : "A" (x), "r" (addr)                    \
 195                      : : label)
 196
 197 #define __put_user_asm_ex_u64(x, addr)                                  \
 198         asm volatile("\n"                                               \
 199                      "1:        movl %%eax,0(%1)\n"                     \
 200                      "2:        movl %%edx,4(%1)\n"                     \
 201                      "3:"                                               \
 202                      _ASM_EXTABLE_EX(1b, 2b)                            \
 203                      _ASM_EXTABLE_EX(2b, 3b)                            \
 204                      : : "A" (x), "r" (addr))
 205
 206 #define __put_user_x8(x, ptr, __ret_pu)                         \
 207         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 208                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 209 #else
 210 #define __put_user_goto_u64(x, ptr, label) \
 211         __put_user_goto(x, ptr, "q", "", "er", label)
 212 #define __put_user_asm_ex_u64(x, addr)  \
 213         __put_user_asm_ex(x, addr, "q", "", "er")
 214 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 215 #endif
 216
 217 extern void __put_user_bad(void);
 218
 219 /*
 220  * Strange magic calling convention: pointer in %ecx,
 221  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 222  */
 223 extern void __put_user_1(void);
 224 extern void __put_user_2(void);
 225 extern void __put_user_4(void);
 226 extern void __put_user_8(void);
 227
 228 /**
 229  * put_user: - Write a simple value into user space.
 230  * @x:   Value to copy to user space.
 231  * @ptr: Destination address, in user space.
 232  *
 233  * Context: User context only. This function may sleep if pagefaults are
 234  *          enabled.
 235  *
 236  * This macro copies a single simple value from kernel space to user
 237  * space.  It supports simple types like char and int, but not larger
 238  * data types like structures or arrays.
 239  *
 240  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 241  * to the result of dereferencing @ptr.
 242  *
 243  * Returns zero on success, or -EFAULT on error.
 244  */
 245 #define put_user(x, ptr)                                        \
 246 ({                                                              \
 247         int __ret_pu;                                           \
 248         __typeof__(*(ptr)) __pu_val;                            \
 249         __chk_user_ptr(ptr);                                    \
 250         might_fault();                                          \
 251         __pu_val = x;                                           \
 252         switch (sizeof(*(ptr))) {                               \
 253         case 1:                                                 \
 254                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 255                 break;                                          \
 256         case 2:                                                 \
 257                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 258                 break;                                          \
 259         case 4:                                                 \
 260                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 261                 break;                                          \
 262         case 8:                                                 \
 263                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 264                 break;                                          \
 265         default:                                                \
 266                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 267                 break;                                          \
 268         }                                                       \
 269         __builtin_expect(__ret_pu, 0);                          \
 270 })
 271
 272 #define __put_user_size(x, ptr, size, label)                            \
 273 do {                                                                    \
 274         __chk_user_ptr(ptr);                                            \
 275         switch (size) {                                                 \
 276         case 1:                                                         \
 277                 __put_user_goto(x, ptr, "b", "b", "iq", label); \
 278                 break;                                                  \
 279         case 2:                                                         \
 280                 __put_user_goto(x, ptr, "w", "w", "ir", label);         \
 281                 break;                                                  \
 282         case 4:                                                         \
 283                 __put_user_goto(x, ptr, "l", "k", "ir", label);         \
 284                 break;                                                  \
 285         case 8:                                                         \
 286                 __put_user_goto_u64(x, ptr, label);                     \
 287                 break;                                                  \
 288         default:                                                        \
 289                 __put_user_bad();                                       \
 290         }                                                               \
 291 } while (0)
 292
 293 /*
 294  * This doesn't do __uaccess_begin/end - the exception handling
 295  * around it must do that.
 296  */
 297 #define __put_user_size_ex(x, ptr, size)                                \
 298 do {                                                                    \
 299         __chk_user_ptr(ptr);                                            \
 300         switch (size) {                                                 \
 301         case 1:                                                         \
 302                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 303                 break;                                                  \
 304         case 2:                                                         \
 305                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 306                 break;                                                  \
 307         case 4:                                                         \
 308                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 309                 break;                                                  \
 310         case 8:                                                         \
 311                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 312                 break;                                                  \
 313         default:                                                        \
 314                 __put_user_bad();                                       \
 315         }                                                               \
 316 } while (0)
 317
 318 #ifdef CONFIG_X86_32
 319 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 320 ({                                                                      \
 321         __typeof__(ptr) __ptr = (ptr);                                  \
 322         asm volatile("\n"                                       \
 323                      "1:        movl %2,%%eax\n"                        \
 324                      "2:        movl %3,%%edx\n"                        \
 325                      "3:\n"                             \
 326                      ".section .fixup,\"ax\"\n"                         \
 327                      "4:        mov %4,%0\n"                            \
 328                      "  xorl %%eax,%%eax\n"                             \
 329                      "  xorl %%edx,%%edx\n"                             \
 330                      "  jmp 3b\n"                                       \
 331                      ".previous\n"                                      \
 332                      _ASM_EXTABLE_UA(1b, 4b)                            \
 333                      _ASM_EXTABLE_UA(2b, 4b)                            \
 334                      : "=r" (retval), "=&A"(x)                          \
 335                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 336                        "i" (errret), "0" (retval));                     \
 337 })
 338
 339 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 340 #else
 341 #define __get_user_asm_u64(x, ptr, retval, errret) \
 342          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 343 #define __get_user_asm_ex_u64(x, ptr) \
 344          __get_user_asm_ex(x, ptr, "q", "", "=r")
 345 #endif
 346
 347 #define __get_user_size(x, ptr, size, retval, errret)                   \
 348 do {                                                                    \
 349         retval = 0;                                                     \
 350         __chk_user_ptr(ptr);                                            \
 351         switch (size) {                                                 \
 352         case 1:                                                         \
 353                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 354                 break;                                                  \
 355         case 2:                                                         \
 356                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 357                 break;                                                  \
 358         case 4:                                                         \
 359                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 360                 break;                                                  \
 361         case 8:                                                         \
 362                 __get_user_asm_u64(x, ptr, retval, errret);             \
 363                 break;                                                  \
 364         default:                                                        \
 365                 (x) = __get_user_bad();                                 \
 366         }                                                               \
 367 } while (0)
 368
 369 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 370         asm volatile("\n"                                               \
 371                      "1:        mov"itype" %2,%"rtype"1\n"              \
 372                      "2:\n"                                             \
 373                      ".section .fixup,\"ax\"\n"                         \
 374                      "3:        mov %3,%0\n"                            \
 375                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 376                      "  jmp 2b\n"                                       \
 377                      ".previous\n"                                      \
 378                      _ASM_EXTABLE_UA(1b, 3b)                            \
 379                      : "=r" (err), ltype(x)                             \
 380                      : "m" (__m(addr)), "i" (errret), "0" (err))
 381
 382 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 383         asm volatile("\n"                                               \
 384                      "1:        mov"itype" %2,%"rtype"1\n"              \
 385                      "2:\n"                                             \
 386                      ".section .fixup,\"ax\"\n"                         \
 387                      "3:        mov %3,%0\n"                            \
 388                      "  jmp 2b\n"                                       \
 389                      ".previous\n"                                      \
 390                      _ASM_EXTABLE_UA(1b, 3b)                            \
 391                      : "=r" (err), ltype(x)                             \
 392                      : "m" (__m(addr)), "i" (errret), "0" (err))
 393
 394 /*
 395  * This doesn't do __uaccess_begin/end - the exception handling
 396  * around it must do that.
 397  */
 398 #define __get_user_size_ex(x, ptr, size)                                \
 399 do {                                                                    \
 400         __chk_user_ptr(ptr);                                            \
 401         switch (size) {                                                 \
 402         case 1:                                                         \
 403                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 404                 break;                                                  \
 405         case 2:                                                         \
 406                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 407                 break;                                                  \
 408         case 4:                                                         \
 409                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 410                 break;                                                  \
 411         case 8:                                                         \
 412                 __get_user_asm_ex_u64(x, ptr);                          \
 413                 break;                                                  \
 414         default:                                                        \
 415                 (x) = __get_user_bad();                                 \
 416         }                                                               \
 417 } while (0)
 418
 419 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 420         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 421                      "2:\n"                                             \
 422                      ".section .fixup,\"ax\"\n"                         \
 423                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 424                      "  jmp 2b\n"                                       \
 425                      ".previous\n"                                      \
 426                      _ASM_EXTABLE_EX(1b, 3b)                            \
 427                      : ltype(x) : "m" (__m(addr)))
 428
 429 #define __put_user_nocheck(x, ptr, size)                        \
 430 ({                                                              \
 431         __label__ __pu_label;                                   \
 432         int __pu_err = -EFAULT;                                 \
 433         __typeof__(*(ptr)) __pu_val;                            \
 434         __pu_val = x;                                           \
 435         __uaccess_begin();                                      \
 436         __put_user_size(__pu_val, (ptr), (size), __pu_label);   \
 437         __pu_err = 0;                                           \
 438 __pu_label:                                                     \
 439         __uaccess_end();                                        \
 440         __builtin_expect(__pu_err, 0);                          \
 441 })
 442
 443 #define __get_user_nocheck(x, ptr, size)                                \
 444 ({                                                                      \
 445         int __gu_err;                                                   \
 446         __inttype(*(ptr)) __gu_val;                                     \
 447         __uaccess_begin_nospec();                                       \
 448         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 449         __uaccess_end();                                                \
 450         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 451         __builtin_expect(__gu_err, 0);                                  \
 452 })
 453
 454 /* FIXME: this hack is definitely wrong -AK */
 455 struct __large_struct { unsigned long buf[100]; };
 456 #define __m(x) (*(struct __large_struct __user *)(x))
 457
 458 /*
 459  * Tell gcc we read from memory instead of writing: this is because
 460  * we do not write to any memory gcc knows about, so there are no
 461  * aliasing issues.
 462  */
 463 #define __put_user_goto(x, addr, itype, rtype, ltype, label)    \
 464         asm_volatile_goto("\n"                                          \
 465                 "1:     mov"itype" %"rtype"0,%1\n"                      \
 466                 _ASM_EXTABLE_UA(1b, %l2)                                        \
 467                 : : ltype(x), "m" (__m(addr))                           \
 468                 : : label)
 469
 470 #define __put_user_failed(x, addr, itype, rtype, ltype, errret)         \
 471         ({      __label__ __puflab;                                     \
 472                 int __pufret = errret;                                  \
 473                 __put_user_goto(x,addr,itype,rtype,ltype,__puflab);     \
 474                 __pufret = 0;                                           \
 475         __puflab: __pufret; })
 476
 477 #define __put_user_asm(x, addr, retval, itype, rtype, ltype, errret)    do {    \
 478         retval = __put_user_failed(x, addr, itype, rtype, ltype, errret);       \
 479 } while (0)
 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((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 static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
 712 {
 713         if (unlikely(!access_ok(ptr,len)))
 714                 return 0;
 715         __uaccess_begin_nospec();
 716         return 1;
 717 }
 718 #define user_access_begin(a,b)  user_access_begin(a,b)
 719 #define user_access_end()       __uaccess_end()
 720
 721 #define unsafe_put_user(x, ptr, label)  \
 722         __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
 723
 724 #define unsafe_get_user(x, ptr, err_label)                                      \
 725 do {                                                                            \
 726         int __gu_err;                                                           \
 727         __inttype(*(ptr)) __gu_val;                                             \
 728         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 729         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 730         if (unlikely(__gu_err)) goto err_label;                                 \
 731 } while (0)
 732
 733 #endif /* _ASM_X86_UACCESS_H */
 734