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_asm_u64(x, addr, err, errret)                        \
 190         asm volatile("\n"                                               \
 191                      "1:        movl %%eax,0(%2)\n"                     \
 192                      "2:        movl %%edx,4(%2)\n"                     \
 193                      "3:"                                               \
 194                      ".section .fixup,\"ax\"\n"                         \
 195                      "4:        movl %3,%0\n"                           \
 196                      "  jmp 3b\n"                                       \
 197                      ".previous\n"                                      \
 198                      _ASM_EXTABLE_UA(1b, 4b)                            \
 199                      _ASM_EXTABLE_UA(2b, 4b)                            \
 200                      : "=r" (err)                                       \
 201                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 202
 203 #define __put_user_asm_ex_u64(x, addr)                                  \
 204         asm volatile("\n"                                               \
 205                      "1:        movl %%eax,0(%1)\n"                     \
 206                      "2:        movl %%edx,4(%1)\n"                     \
 207                      "3:"                                               \
 208                      _ASM_EXTABLE_EX(1b, 2b)                            \
 209                      _ASM_EXTABLE_EX(2b, 3b)                            \
 210                      : : "A" (x), "r" (addr))
 211
 212 #define __put_user_x8(x, ptr, __ret_pu)                         \
 213         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 214                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 215 #else
 216 #define __put_user_asm_u64(x, ptr, retval, errret) \
 217         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 218 #define __put_user_asm_ex_u64(x, addr)  \
 219         __put_user_asm_ex(x, addr, "q", "", "er")
 220 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 221 #endif
 222
 223 extern void __put_user_bad(void);
 224
 225 /*
 226  * Strange magic calling convention: pointer in %ecx,
 227  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 228  */
 229 extern void __put_user_1(void);
 230 extern void __put_user_2(void);
 231 extern void __put_user_4(void);
 232 extern void __put_user_8(void);
 233
 234 /**
 235  * put_user: - Write a simple value into user space.
 236  * @x:   Value to copy to user space.
 237  * @ptr: Destination address, in user space.
 238  *
 239  * Context: User context only. This function may sleep if pagefaults are
 240  *          enabled.
 241  *
 242  * This macro copies a single simple value from kernel space to user
 243  * space.  It supports simple types like char and int, but not larger
 244  * data types like structures or arrays.
 245  *
 246  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 247  * to the result of dereferencing @ptr.
 248  *
 249  * Returns zero on success, or -EFAULT on error.
 250  */
 251 #define put_user(x, ptr)                                        \
 252 ({                                                              \
 253         int __ret_pu;                                           \
 254         __typeof__(*(ptr)) __pu_val;                            \
 255         __chk_user_ptr(ptr);                                    \
 256         might_fault();                                          \
 257         __pu_val = x;                                           \
 258         switch (sizeof(*(ptr))) {                               \
 259         case 1:                                                 \
 260                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 261                 break;                                          \
 262         case 2:                                                 \
 263                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 264                 break;                                          \
 265         case 4:                                                 \
 266                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 267                 break;                                          \
 268         case 8:                                                 \
 269                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 270                 break;                                          \
 271         default:                                                \
 272                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 273                 break;                                          \
 274         }                                                       \
 275         __builtin_expect(__ret_pu, 0);                          \
 276 })
 277
 278 #define __put_user_size(x, ptr, size, retval, errret)                   \
 279 do {                                                                    \
 280         retval = 0;                                                     \
 281         __chk_user_ptr(ptr);                                            \
 282         switch (size) {                                                 \
 283         case 1:                                                         \
 284                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 285                 break;                                                  \
 286         case 2:                                                         \
 287                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 288                 break;                                                  \
 289         case 4:                                                         \
 290                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 291                 break;                                                  \
 292         case 8:                                                         \
 293                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 294                                    errret);                             \
 295                 break;                                                  \
 296         default:                                                        \
 297                 __put_user_bad();                                       \
 298         }                                                               \
 299 } while (0)
 300
 301 /*
 302  * This doesn't do __uaccess_begin/end - the exception handling
 303  * around it must do that.
 304  */
 305 #define __put_user_size_ex(x, ptr, size)                                \
 306 do {                                                                    \
 307         __chk_user_ptr(ptr);                                            \
 308         switch (size) {                                                 \
 309         case 1:                                                         \
 310                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 311                 break;                                                  \
 312         case 2:                                                         \
 313                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 314                 break;                                                  \
 315         case 4:                                                         \
 316                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 317                 break;                                                  \
 318         case 8:                                                         \
 319                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 320                 break;                                                  \
 321         default:                                                        \
 322                 __put_user_bad();                                       \
 323         }                                                               \
 324 } while (0)
 325
 326 #ifdef CONFIG_X86_32
 327 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 328 ({                                                                      \
 329         __typeof__(ptr) __ptr = (ptr);                                  \
 330         asm volatile("\n"                                       \
 331                      "1:        movl %2,%%eax\n"                        \
 332                      "2:        movl %3,%%edx\n"                        \
 333                      "3:\n"                             \
 334                      ".section .fixup,\"ax\"\n"                         \
 335                      "4:        mov %4,%0\n"                            \
 336                      "  xorl %%eax,%%eax\n"                             \
 337                      "  xorl %%edx,%%edx\n"                             \
 338                      "  jmp 3b\n"                                       \
 339                      ".previous\n"                                      \
 340                      _ASM_EXTABLE_UA(1b, 4b)                            \
 341                      _ASM_EXTABLE_UA(2b, 4b)                            \
 342                      : "=r" (retval), "=&A"(x)                          \
 343                      : "m" (__m(__ptr)), "m" __m(((u32 __user *)(__ptr)) + 1),  \
 344                        "i" (errret), "0" (retval));                     \
 345 })
 346
 347 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 348 #else
 349 #define __get_user_asm_u64(x, ptr, retval, errret) \
 350          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 351 #define __get_user_asm_ex_u64(x, ptr) \
 352          __get_user_asm_ex(x, ptr, "q", "", "=r")
 353 #endif
 354
 355 #define __get_user_size(x, ptr, size, retval, errret)                   \
 356 do {                                                                    \
 357         retval = 0;                                                     \
 358         __chk_user_ptr(ptr);                                            \
 359         switch (size) {                                                 \
 360         case 1:                                                         \
 361                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 362                 break;                                                  \
 363         case 2:                                                         \
 364                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 365                 break;                                                  \
 366         case 4:                                                         \
 367                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 368                 break;                                                  \
 369         case 8:                                                         \
 370                 __get_user_asm_u64(x, ptr, retval, errret);             \
 371                 break;                                                  \
 372         default:                                                        \
 373                 (x) = __get_user_bad();                                 \
 374         }                                                               \
 375 } while (0)
 376
 377 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 378         asm volatile("\n"                                               \
 379                      "1:        mov"itype" %2,%"rtype"1\n"              \
 380                      "2:\n"                                             \
 381                      ".section .fixup,\"ax\"\n"                         \
 382                      "3:        mov %3,%0\n"                            \
 383                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 384                      "  jmp 2b\n"                                       \
 385                      ".previous\n"                                      \
 386                      _ASM_EXTABLE_UA(1b, 3b)                            \
 387                      : "=r" (err), ltype(x)                             \
 388                      : "m" (__m(addr)), "i" (errret), "0" (err))
 389
 390 #define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret)        \
 391         asm volatile("\n"                                               \
 392                      "1:        mov"itype" %2,%"rtype"1\n"              \
 393                      "2:\n"                                             \
 394                      ".section .fixup,\"ax\"\n"                         \
 395                      "3:        mov %3,%0\n"                            \
 396                      "  jmp 2b\n"                                       \
 397                      ".previous\n"                                      \
 398                      _ASM_EXTABLE_UA(1b, 3b)                            \
 399                      : "=r" (err), ltype(x)                             \
 400                      : "m" (__m(addr)), "i" (errret), "0" (err))
 401
 402 /*
 403  * This doesn't do __uaccess_begin/end - the exception handling
 404  * around it must do that.
 405  */
 406 #define __get_user_size_ex(x, ptr, size)                                \
 407 do {                                                                    \
 408         __chk_user_ptr(ptr);                                            \
 409         switch (size) {                                                 \
 410         case 1:                                                         \
 411                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 412                 break;                                                  \
 413         case 2:                                                         \
 414                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 415                 break;                                                  \
 416         case 4:                                                         \
 417                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 418                 break;                                                  \
 419         case 8:                                                         \
 420                 __get_user_asm_ex_u64(x, ptr);                          \
 421                 break;                                                  \
 422         default:                                                        \
 423                 (x) = __get_user_bad();                                 \
 424         }                                                               \
 425 } while (0)
 426
 427 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 428         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 429                      "2:\n"                                             \
 430                      ".section .fixup,\"ax\"\n"                         \
 431                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 432                      "  jmp 2b\n"                                       \
 433                      ".previous\n"                                      \
 434                      _ASM_EXTABLE_EX(1b, 3b)                            \
 435                      : ltype(x) : "m" (__m(addr)))
 436
 437 #define __put_user_nocheck(x, ptr, size)                        \
 438 ({                                                              \
 439         int __pu_err;                                           \
 440         __uaccess_begin();                                      \
 441         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 442         __uaccess_end();                                        \
 443         __builtin_expect(__pu_err, 0);                          \
 444 })
 445
 446 #define __get_user_nocheck(x, ptr, size)                                \
 447 ({                                                                      \
 448         int __gu_err;                                                   \
 449         __inttype(*(ptr)) __gu_val;                                     \
 450         __uaccess_begin_nospec();                                       \
 451         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 452         __uaccess_end();                                                \
 453         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 454         __builtin_expect(__gu_err, 0);                                  \
 455 })
 456
 457 /* FIXME: this hack is definitely wrong -AK */
 458 struct __large_struct { unsigned long buf[100]; };
 459 #define __m(x) (*(struct __large_struct __user *)(x))
 460
 461 /*
 462  * Tell gcc we read from memory instead of writing: this is because
 463  * we do not write to any memory gcc knows about, so there are no
 464  * aliasing issues.
 465  */
 466 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 467         asm volatile("\n"                                               \
 468                      "1:        mov"itype" %"rtype"1,%2\n"              \
 469                      "2:\n"                                             \
 470                      ".section .fixup,\"ax\"\n"                         \
 471                      "3:        mov %3,%0\n"                            \
 472                      "  jmp 2b\n"                                       \
 473                      ".previous\n"                                      \
 474                      _ASM_EXTABLE_UA(1b, 3b)                            \
 475                      : "=r"(err)                                        \
 476                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 477
 478 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 479         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 480                      "2:\n"                                             \
 481                      _ASM_EXTABLE_EX(1b, 2b)                            \
 482                      : : ltype(x), "m" (__m(addr)))
 483
 484 /*
 485  * uaccess_try and catch
 486  */
 487 #define uaccess_try     do {                                            \
 488         current->thread.uaccess_err = 0;                                \
 489         __uaccess_begin();                                              \
 490         barrier();
 491
 492 #define uaccess_try_nospec do {                                         \
 493         current->thread.uaccess_err = 0;                                \
 494         __uaccess_begin_nospec();                                       \
 495
 496 #define uaccess_catch(err)                                              \
 497         __uaccess_end();                                                \
 498         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 499 } while (0)
 500
 501 /**
 502  * __get_user: - Get a simple variable from user space, with less checking.
 503  * @x:   Variable to store result.
 504  * @ptr: Source address, in user space.
 505  *
 506  * Context: User context only. This function may sleep if pagefaults are
 507  *          enabled.
 508  *
 509  * This macro copies a single simple variable from user space to kernel
 510  * space.  It supports simple types like char and int, but not larger
 511  * data types like structures or arrays.
 512  *
 513  * @ptr must have pointer-to-simple-variable type, and the result of
 514  * dereferencing @ptr must be assignable to @x without a cast.
 515  *
 516  * Caller must check the pointer with access_ok() before calling this
 517  * function.
 518  *
 519  * Returns zero on success, or -EFAULT on error.
 520  * On error, the variable @x is set to zero.
 521  */
 522
 523 #define __get_user(x, ptr)                                              \
 524         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 525
 526 /**
 527  * __put_user: - Write a simple value into user space, with less checking.
 528  * @x:   Value to copy to user space.
 529  * @ptr: Destination address, in user space.
 530  *
 531  * Context: User context only. This function may sleep if pagefaults are
 532  *          enabled.
 533  *
 534  * This macro copies a single simple value from kernel space to user
 535  * space.  It supports simple types like char and int, but not larger
 536  * data types like structures or arrays.
 537  *
 538  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 539  * to the result of dereferencing @ptr.
 540  *
 541  * Caller must check the pointer with access_ok() before calling this
 542  * function.
 543  *
 544  * Returns zero on success, or -EFAULT on error.
 545  */
 546
 547 #define __put_user(x, ptr)                                              \
 548         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 549
 550 /*
 551  * {get|put}_user_try and catch
 552  *
 553  * get_user_try {
 554  *      get_user_ex(...);
 555  * } get_user_catch(err)
 556  */
 557 #define get_user_try            uaccess_try_nospec
 558 #define get_user_catch(err)     uaccess_catch(err)
 559
 560 #define get_user_ex(x, ptr)     do {                                    \
 561         unsigned long __gue_val;                                        \
 562         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 563         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 564 } while (0)
 565
 566 #define put_user_try            uaccess_try
 567 #define put_user_catch(err)     uaccess_catch(err)
 568
 569 #define put_user_ex(x, ptr)                                             \
 570         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 571
 572 extern unsigned long
 573 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 574 extern __must_check long
 575 strncpy_from_user(char *dst, const char __user *src, long count);
 576
 577 extern __must_check long strnlen_user(const char __user *str, long n);
 578
 579 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 580 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 581
 582 extern void __cmpxchg_wrong_size(void)
 583         __compiletime_error("Bad argument size for cmpxchg");
 584
 585 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 586 ({                                                                      \
 587         int __ret = 0;                                                  \
 588         __typeof__(ptr) __uval = (uval);                                \
 589         __typeof__(*(ptr)) __old = (old);                               \
 590         __typeof__(*(ptr)) __new = (new);                               \
 591         __uaccess_begin_nospec();                                       \
 592         switch (size) {                                                 \
 593         case 1:                                                         \
 594         {                                                               \
 595                 asm volatile("\n"                                       \
 596                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 597                         "2:\n"                                          \
 598                         "\t.section .fixup, \"ax\"\n"                   \
 599                         "3:\tmov     %3, %0\n"                          \
 600                         "\tjmp     2b\n"                                \
 601                         "\t.previous\n"                                 \
 602                         _ASM_EXTABLE_UA(1b, 3b)                         \
 603                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 604                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 605                         : "memory"                                      \
 606                 );                                                      \
 607                 break;                                                  \
 608         }                                                               \
 609         case 2:                                                         \
 610         {                                                               \
 611                 asm volatile("\n"                                       \
 612                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 613                         "2:\n"                                          \
 614                         "\t.section .fixup, \"ax\"\n"                   \
 615                         "3:\tmov     %3, %0\n"                          \
 616                         "\tjmp     2b\n"                                \
 617                         "\t.previous\n"                                 \
 618                         _ASM_EXTABLE_UA(1b, 3b)                         \
 619                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 620                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 621                         : "memory"                                      \
 622                 );                                                      \
 623                 break;                                                  \
 624         }                                                               \
 625         case 4:                                                         \
 626         {                                                               \
 627                 asm volatile("\n"                                       \
 628                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 629                         "2:\n"                                          \
 630                         "\t.section .fixup, \"ax\"\n"                   \
 631                         "3:\tmov     %3, %0\n"                          \
 632                         "\tjmp     2b\n"                                \
 633                         "\t.previous\n"                                 \
 634                         _ASM_EXTABLE_UA(1b, 3b)                         \
 635                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 636                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 637                         : "memory"                                      \
 638                 );                                                      \
 639                 break;                                                  \
 640         }                                                               \
 641         case 8:                                                         \
 642         {                                                               \
 643                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 644                         __cmpxchg_wrong_size();                         \
 645                                                                         \
 646                 asm volatile("\n"                                       \
 647                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 648                         "2:\n"                                          \
 649                         "\t.section .fixup, \"ax\"\n"                   \
 650                         "3:\tmov     %3, %0\n"                          \
 651                         "\tjmp     2b\n"                                \
 652                         "\t.previous\n"                                 \
 653                         _ASM_EXTABLE_UA(1b, 3b)                         \
 654                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 655                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 656                         : "memory"                                      \
 657                 );                                                      \
 658                 break;                                                  \
 659         }                                                               \
 660         default:                                                        \
 661                 __cmpxchg_wrong_size();                                 \
 662         }                                                               \
 663         __uaccess_end();                                                \
 664         *__uval = __old;                                                \
 665         __ret;                                                          \
 666 })
 667
 668 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 669 ({                                                                      \
 670         access_ok((ptr), sizeof(*(ptr))) ?              \
 671                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 672                                 (old), (new), sizeof(*(ptr))) :         \
 673                 -EFAULT;                                                \
 674 })
 675
 676 /*
 677  * movsl can be slow when source and dest are not both 8-byte aligned
 678  */
 679 #ifdef CONFIG_X86_INTEL_USERCOPY
 680 extern struct movsl_mask {
 681         int mask;
 682 } ____cacheline_aligned_in_smp movsl_mask;
 683 #endif
 684
 685 #define ARCH_HAS_NOCACHE_UACCESS 1
 686
 687 #ifdef CONFIG_X86_32
 688 # include <asm/uaccess_32.h>
 689 #else
 690 # include <asm/uaccess_64.h>
 691 #endif
 692
 693 /*
 694  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 695  * nested NMI paths are careful to preserve CR2.
 696  *
 697  * Caller must use pagefault_enable/disable, or run in interrupt context,
 698  * and also do a uaccess_ok() check
 699  */
 700 #define __copy_from_user_nmi __copy_from_user_inatomic
 701
 702 /*
 703  * The "unsafe" user accesses aren't really "unsafe", but the naming
 704  * is a big fat warning: you have to not only do the access_ok()
 705  * checking before using them, but you have to surround them with the
 706  * user_access_begin/end() pair.
 707  */
 708 static __must_check inline bool user_access_begin(const void __user *ptr, size_t len)
 709 {
 710         if (unlikely(!access_ok(ptr,len)))
 711                 return 0;
 712         __uaccess_begin();
 713         return 1;
 714 }
 715 #define user_access_begin(a,b)  user_access_begin(a,b)
 716 #define user_access_end()       __uaccess_end()
 717
 718 #define unsafe_put_user(x, ptr, err_label)                                      \
 719 do {                                                                            \
 720         int __pu_err;                                                           \
 721         __typeof__(*(ptr)) __pu_val = (x);                                      \
 722         __put_user_size(__pu_val, (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);    \
 723         if (unlikely(__pu_err)) goto err_label;                                 \
 724 } while (0)
 725
 726 #define unsafe_get_user(x, ptr, err_label)                                      \
 727 do {                                                                            \
 728         int __gu_err;                                                           \
 729         __inttype(*(ptr)) __gu_val;                                             \
 730         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 731         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 732         if (unlikely(__gu_err)) goto err_label;                                 \
 733 } while (0)
 734
 735 #endif /* _ASM_X86_UACCESS_H */
 736