arch/x86/include/asm/uaccess.h

   1 #ifndef _ASM_X86_UACCESS_H
   2 #define _ASM_X86_UACCESS_H
   3 /*
   4  * User space memory access functions
   5  */
   6 #include <linux/errno.h>
   7 #include <linux/compiler.h>
   8 #include <linux/kasan-checks.h>
   9 #include <linux/thread_info.h>
  10 #include <linux/string.h>
  11 #include <asm/asm.h>
  12 #include <asm/page.h>
  13 #include <asm/smap.h>
  14 #include <asm/extable.h>
  15
  16 #define VERIFY_READ 0
  17 #define VERIFY_WRITE 1
  18
  19 /*
  20  * The fs value determines whether argument validity checking should be
  21  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  22  * get_fs() == KERNEL_DS, checking is bypassed.
  23  *
  24  * For historical reasons, these macros are grossly misnamed.
  25  */
  26
  27 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  28
  29 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  30 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  31
  32 #define get_ds()        (KERNEL_DS)
  33 #define get_fs()        (current->thread.addr_limit)
  34 #define set_fs(x)       (current->thread.addr_limit = (x))
  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 /**
  72  * access_ok: - Checks if a user space pointer is valid
  73  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  74  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  75  *        to write to a block, it is always safe to read from it.
  76  * @addr: User space pointer to start of block to check
  77  * @size: Size of block to check
  78  *
  79  * Context: User context only. This function may sleep if pagefaults are
  80  *          enabled.
  81  *
  82  * Checks if a pointer to a block of memory in user space is valid.
  83  *
  84  * Returns true (nonzero) if the memory block may be valid, false (zero)
  85  * if it is definitely invalid.
  86  *
  87  * Note that, depending on architecture, this function probably just
  88  * checks that the pointer is in the user space range - after calling
  89  * this function, memory access functions may still return -EFAULT.
  90  */
  91 #define access_ok(type, addr, size) \
  92         likely(!__range_not_ok(addr, size, user_addr_max()))
  93
  94 /*
  95  * These are the main single-value transfer routines.  They automatically
  96  * use the right size if we just have the right pointer type.
  97  *
  98  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  99  * and yet we don't want to do any pointers, because that is too much
 100  * of a performance impact. Thus we have a few rather ugly macros here,
 101  * and hide all the ugliness from the user.
 102  *
 103  * The "__xxx" versions of the user access functions are versions that
 104  * do not verify the address space, that must have been done previously
 105  * with a separate "access_ok()" call (this is used when we do multiple
 106  * accesses to the same area of user memory).
 107  */
 108
 109 extern int __get_user_1(void);
 110 extern int __get_user_2(void);
 111 extern int __get_user_4(void);
 112 extern int __get_user_8(void);
 113 extern int __get_user_bad(void);
 114
 115 #define __uaccess_begin() stac()
 116 #define __uaccess_end()   clac()
 117
 118 /*
 119  * This is a type: either unsigned long, if the argument fits into
 120  * that type, or otherwise unsigned long long.
 121  */
 122 #define __inttype(x) \
 123 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 124
 125 /**
 126  * get_user: - Get a simple variable from user space.
 127  * @x:   Variable to store result.
 128  * @ptr: Source address, in user space.
 129  *
 130  * Context: User context only. This function may sleep if pagefaults are
 131  *          enabled.
 132  *
 133  * This macro copies a single simple variable from user space to kernel
 134  * space.  It supports simple types like char and int, but not larger
 135  * data types like structures or arrays.
 136  *
 137  * @ptr must have pointer-to-simple-variable type, and the result of
 138  * dereferencing @ptr must be assignable to @x without a cast.
 139  *
 140  * Returns zero on success, or -EFAULT on error.
 141  * On error, the variable @x is set to zero.
 142  */
 143 /*
 144  * Careful: we have to cast the result to the type of the pointer
 145  * for sign reasons.
 146  *
 147  * The use of _ASM_DX as the register specifier is a bit of a
 148  * simplification, as gcc only cares about it as the starting point
 149  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 150  * (%ecx being the next register in gcc's x86 register sequence), and
 151  * %rdx on 64 bits.
 152  *
 153  * Clang/LLVM cares about the size of the register, but still wants
 154  * the base register for something that ends up being a pair.
 155  */
 156 #define get_user(x, ptr)                                                \
 157 ({                                                                      \
 158         int __ret_gu;                                                   \
 159         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 160         register void *__sp asm(_ASM_SP);                               \
 161         __chk_user_ptr(ptr);                                            \
 162         might_fault();                                                  \
 163         asm volatile("call __get_user_%P4"                              \
 164                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 165                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 166         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 167         __builtin_expect(__ret_gu, 0);                                  \
 168 })
 169
 170 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 171         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 172                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 173
 174
 175
 176 #ifdef CONFIG_X86_32
 177 #define __put_user_asm_u64(x, addr, err, errret)                        \
 178         asm volatile("\n"                                               \
 179                      "1:        movl %%eax,0(%2)\n"                     \
 180                      "2:        movl %%edx,4(%2)\n"                     \
 181                      "3:"                                               \
 182                      ".section .fixup,\"ax\"\n"                         \
 183                      "4:        movl %3,%0\n"                           \
 184                      "  jmp 3b\n"                                       \
 185                      ".previous\n"                                      \
 186                      _ASM_EXTABLE(1b, 4b)                               \
 187                      _ASM_EXTABLE(2b, 4b)                               \
 188                      : "=r" (err)                                       \
 189                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 190
 191 #define __put_user_asm_ex_u64(x, addr)                                  \
 192         asm volatile("\n"                                               \
 193                      "1:        movl %%eax,0(%1)\n"                     \
 194                      "2:        movl %%edx,4(%1)\n"                     \
 195                      "3:"                                               \
 196                      _ASM_EXTABLE_EX(1b, 2b)                            \
 197                      _ASM_EXTABLE_EX(2b, 3b)                            \
 198                      : : "A" (x), "r" (addr))
 199
 200 #define __put_user_x8(x, ptr, __ret_pu)                         \
 201         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 202                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 203 #else
 204 #define __put_user_asm_u64(x, ptr, retval, errret) \
 205         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 206 #define __put_user_asm_ex_u64(x, addr)  \
 207         __put_user_asm_ex(x, addr, "q", "", "er")
 208 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 209 #endif
 210
 211 extern void __put_user_bad(void);
 212
 213 /*
 214  * Strange magic calling convention: pointer in %ecx,
 215  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 216  */
 217 extern void __put_user_1(void);
 218 extern void __put_user_2(void);
 219 extern void __put_user_4(void);
 220 extern void __put_user_8(void);
 221
 222 /**
 223  * put_user: - Write a simple value into user space.
 224  * @x:   Value to copy to user space.
 225  * @ptr: Destination address, in user space.
 226  *
 227  * Context: User context only. This function may sleep if pagefaults are
 228  *          enabled.
 229  *
 230  * This macro copies a single simple value from kernel space to user
 231  * space.  It supports simple types like char and int, but not larger
 232  * data types like structures or arrays.
 233  *
 234  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 235  * to the result of dereferencing @ptr.
 236  *
 237  * Returns zero on success, or -EFAULT on error.
 238  */
 239 #define put_user(x, ptr)                                        \
 240 ({                                                              \
 241         int __ret_pu;                                           \
 242         __typeof__(*(ptr)) __pu_val;                            \
 243         __chk_user_ptr(ptr);                                    \
 244         might_fault();                                          \
 245         __pu_val = x;                                           \
 246         switch (sizeof(*(ptr))) {                               \
 247         case 1:                                                 \
 248                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 249                 break;                                          \
 250         case 2:                                                 \
 251                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 252                 break;                                          \
 253         case 4:                                                 \
 254                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 255                 break;                                          \
 256         case 8:                                                 \
 257                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 258                 break;                                          \
 259         default:                                                \
 260                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 261                 break;                                          \
 262         }                                                       \
 263         __builtin_expect(__ret_pu, 0);                          \
 264 })
 265
 266 #define __put_user_size(x, ptr, size, retval, errret)                   \
 267 do {                                                                    \
 268         retval = 0;                                                     \
 269         __chk_user_ptr(ptr);                                            \
 270         switch (size) {                                                 \
 271         case 1:                                                         \
 272                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 273                 break;                                                  \
 274         case 2:                                                         \
 275                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 276                 break;                                                  \
 277         case 4:                                                         \
 278                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 279                 break;                                                  \
 280         case 8:                                                         \
 281                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 282                                    errret);                             \
 283                 break;                                                  \
 284         default:                                                        \
 285                 __put_user_bad();                                       \
 286         }                                                               \
 287 } while (0)
 288
 289 /*
 290  * This doesn't do __uaccess_begin/end - the exception handling
 291  * around it must do that.
 292  */
 293 #define __put_user_size_ex(x, ptr, size)                                \
 294 do {                                                                    \
 295         __chk_user_ptr(ptr);                                            \
 296         switch (size) {                                                 \
 297         case 1:                                                         \
 298                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 299                 break;                                                  \
 300         case 2:                                                         \
 301                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 302                 break;                                                  \
 303         case 4:                                                         \
 304                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 305                 break;                                                  \
 306         case 8:                                                         \
 307                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 308                 break;                                                  \
 309         default:                                                        \
 310                 __put_user_bad();                                       \
 311         }                                                               \
 312 } while (0)
 313
 314 #ifdef CONFIG_X86_32
 315 #define __get_user_asm_u64(x, ptr, retval, errret)                      \
 316 ({                                                                      \
 317         __typeof__(ptr) __ptr = (ptr);                                  \
 318         asm volatile(ASM_STAC "\n"                                      \
 319                      "1:        movl %2,%%eax\n"                        \
 320                      "2:        movl %3,%%edx\n"                        \
 321                      "3: " ASM_CLAC "\n"                                \
 322                      ".section .fixup,\"ax\"\n"                         \
 323                      "4:        mov %4,%0\n"                            \
 324                      "  xorl %%eax,%%eax\n"                             \
 325                      "  xorl %%edx,%%edx\n"                             \
 326                      "  jmp 3b\n"                                       \
 327                      ".previous\n"                                      \
 328                      _ASM_EXTABLE(1b, 4b)                               \
 329                      _ASM_EXTABLE(2b, 4b)                               \
 330                      : "=r" (retval), "=A"(x)                           \
 331                      : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
 332                        "i" (errret), "0" (retval));                     \
 333 })
 334
 335 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 336 #else
 337 #define __get_user_asm_u64(x, ptr, retval, errret) \
 338          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 339 #define __get_user_asm_ex_u64(x, ptr) \
 340          __get_user_asm_ex(x, ptr, "q", "", "=r")
 341 #endif
 342
 343 #define __get_user_size(x, ptr, size, retval, errret)                   \
 344 do {                                                                    \
 345         retval = 0;                                                     \
 346         __chk_user_ptr(ptr);                                            \
 347         switch (size) {                                                 \
 348         case 1:                                                         \
 349                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 350                 break;                                                  \
 351         case 2:                                                         \
 352                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 353                 break;                                                  \
 354         case 4:                                                         \
 355                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 356                 break;                                                  \
 357         case 8:                                                         \
 358                 __get_user_asm_u64(x, ptr, retval, errret);             \
 359                 break;                                                  \
 360         default:                                                        \
 361                 (x) = __get_user_bad();                                 \
 362         }                                                               \
 363 } while (0)
 364
 365 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 366         asm volatile("\n"                                               \
 367                      "1:        mov"itype" %2,%"rtype"1\n"              \
 368                      "2:\n"                                             \
 369                      ".section .fixup,\"ax\"\n"                         \
 370                      "3:        mov %3,%0\n"                            \
 371                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 372                      "  jmp 2b\n"                                       \
 373                      ".previous\n"                                      \
 374                      _ASM_EXTABLE(1b, 3b)                               \
 375                      : "=r" (err), ltype(x)                             \
 376                      : "m" (__m(addr)), "i" (errret), "0" (err))
 377
 378 /*
 379  * This doesn't do __uaccess_begin/end - the exception handling
 380  * around it must do that.
 381  */
 382 #define __get_user_size_ex(x, ptr, size)                                \
 383 do {                                                                    \
 384         __chk_user_ptr(ptr);                                            \
 385         switch (size) {                                                 \
 386         case 1:                                                         \
 387                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 388                 break;                                                  \
 389         case 2:                                                         \
 390                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 391                 break;                                                  \
 392         case 4:                                                         \
 393                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 394                 break;                                                  \
 395         case 8:                                                         \
 396                 __get_user_asm_ex_u64(x, ptr);                          \
 397                 break;                                                  \
 398         default:                                                        \
 399                 (x) = __get_user_bad();                                 \
 400         }                                                               \
 401 } while (0)
 402
 403 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 404         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 405                      "2:\n"                                             \
 406                      ".section .fixup,\"ax\"\n"                         \
 407                      "3:xor"itype" %"rtype"0,%"rtype"0\n"               \
 408                      "  jmp 2b\n"                                       \
 409                      ".previous\n"                                      \
 410                      _ASM_EXTABLE_EX(1b, 3b)                            \
 411                      : ltype(x) : "m" (__m(addr)))
 412
 413 #define __put_user_nocheck(x, ptr, size)                        \
 414 ({                                                              \
 415         int __pu_err;                                           \
 416         __uaccess_begin();                                      \
 417         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 418         __uaccess_end();                                        \
 419         __builtin_expect(__pu_err, 0);                          \
 420 })
 421
 422 #define __get_user_nocheck(x, ptr, size)                                \
 423 ({                                                                      \
 424         int __gu_err;                                                   \
 425         __inttype(*(ptr)) __gu_val;                                     \
 426         __uaccess_begin();                                              \
 427         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 428         __uaccess_end();                                                \
 429         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 430         __builtin_expect(__gu_err, 0);                                  \
 431 })
 432
 433 /* FIXME: this hack is definitely wrong -AK */
 434 struct __large_struct { unsigned long buf[100]; };
 435 #define __m(x) (*(struct __large_struct __user *)(x))
 436
 437 /*
 438  * Tell gcc we read from memory instead of writing: this is because
 439  * we do not write to any memory gcc knows about, so there are no
 440  * aliasing issues.
 441  */
 442 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 443         asm volatile("\n"                                               \
 444                      "1:        mov"itype" %"rtype"1,%2\n"              \
 445                      "2:\n"                                             \
 446                      ".section .fixup,\"ax\"\n"                         \
 447                      "3:        mov %3,%0\n"                            \
 448                      "  jmp 2b\n"                                       \
 449                      ".previous\n"                                      \
 450                      _ASM_EXTABLE(1b, 3b)                               \
 451                      : "=r"(err)                                        \
 452                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 453
 454 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 455         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 456                      "2:\n"                                             \
 457                      _ASM_EXTABLE_EX(1b, 2b)                            \
 458                      : : ltype(x), "m" (__m(addr)))
 459
 460 /*
 461  * uaccess_try and catch
 462  */
 463 #define uaccess_try     do {                                            \
 464         current->thread.uaccess_err = 0;                                \
 465         __uaccess_begin();                                              \
 466         barrier();
 467
 468 #define uaccess_catch(err)                                              \
 469         __uaccess_end();                                                \
 470         (err) |= (current->thread.uaccess_err ? -EFAULT : 0);           \
 471 } while (0)
 472
 473 /**
 474  * __get_user: - Get a simple variable from user space, with less checking.
 475  * @x:   Variable to store result.
 476  * @ptr: Source address, in user space.
 477  *
 478  * Context: User context only. This function may sleep if pagefaults are
 479  *          enabled.
 480  *
 481  * This macro copies a single simple variable from user space to kernel
 482  * space.  It supports simple types like char and int, but not larger
 483  * data types like structures or arrays.
 484  *
 485  * @ptr must have pointer-to-simple-variable type, and the result of
 486  * dereferencing @ptr must be assignable to @x without a cast.
 487  *
 488  * Caller must check the pointer with access_ok() before calling this
 489  * function.
 490  *
 491  * Returns zero on success, or -EFAULT on error.
 492  * On error, the variable @x is set to zero.
 493  */
 494
 495 #define __get_user(x, ptr)                                              \
 496         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 497
 498 /**
 499  * __put_user: - Write a simple value into user space, with less checking.
 500  * @x:   Value to copy to user space.
 501  * @ptr: Destination address, in user space.
 502  *
 503  * Context: User context only. This function may sleep if pagefaults are
 504  *          enabled.
 505  *
 506  * This macro copies a single simple value from kernel space to user
 507  * space.  It supports simple types like char and int, but not larger
 508  * data types like structures or arrays.
 509  *
 510  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 511  * to the result of dereferencing @ptr.
 512  *
 513  * Caller must check the pointer with access_ok() before calling this
 514  * function.
 515  *
 516  * Returns zero on success, or -EFAULT on error.
 517  */
 518
 519 #define __put_user(x, ptr)                                              \
 520         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 521
 522 #define __get_user_unaligned __get_user
 523 #define __put_user_unaligned __put_user
 524
 525 /*
 526  * {get|put}_user_try and catch
 527  *
 528  * get_user_try {
 529  *      get_user_ex(...);
 530  * } get_user_catch(err)
 531  */
 532 #define get_user_try            uaccess_try
 533 #define get_user_catch(err)     uaccess_catch(err)
 534
 535 #define get_user_ex(x, ptr)     do {                                    \
 536         unsigned long __gue_val;                                        \
 537         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 538         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 539 } while (0)
 540
 541 #define put_user_try            uaccess_try
 542 #define put_user_catch(err)     uaccess_catch(err)
 543
 544 #define put_user_ex(x, ptr)                                             \
 545         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 546
 547 extern unsigned long
 548 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 549 extern __must_check long
 550 strncpy_from_user(char *dst, const char __user *src, long count);
 551
 552 extern __must_check long strlen_user(const char __user *str);
 553 extern __must_check long strnlen_user(const char __user *str, long n);
 554
 555 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 556 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 557
 558 extern void __cmpxchg_wrong_size(void)
 559         __compiletime_error("Bad argument size for cmpxchg");
 560
 561 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 562 ({                                                                      \
 563         int __ret = 0;                                                  \
 564         __typeof__(ptr) __uval = (uval);                                \
 565         __typeof__(*(ptr)) __old = (old);                               \
 566         __typeof__(*(ptr)) __new = (new);                               \
 567         __uaccess_begin();                                              \
 568         switch (size) {                                                 \
 569         case 1:                                                         \
 570         {                                                               \
 571                 asm volatile("\n"                                       \
 572                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 573                         "2:\n"                                          \
 574                         "\t.section .fixup, \"ax\"\n"                   \
 575                         "3:\tmov     %3, %0\n"                          \
 576                         "\tjmp     2b\n"                                \
 577                         "\t.previous\n"                                 \
 578                         _ASM_EXTABLE(1b, 3b)                            \
 579                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 580                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 581                         : "memory"                                      \
 582                 );                                                      \
 583                 break;                                                  \
 584         }                                                               \
 585         case 2:                                                         \
 586         {                                                               \
 587                 asm volatile("\n"                                       \
 588                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 589                         "2:\n"                                          \
 590                         "\t.section .fixup, \"ax\"\n"                   \
 591                         "3:\tmov     %3, %0\n"                          \
 592                         "\tjmp     2b\n"                                \
 593                         "\t.previous\n"                                 \
 594                         _ASM_EXTABLE(1b, 3b)                            \
 595                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 596                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 597                         : "memory"                                      \
 598                 );                                                      \
 599                 break;                                                  \
 600         }                                                               \
 601         case 4:                                                         \
 602         {                                                               \
 603                 asm volatile("\n"                                       \
 604                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 605                         "2:\n"                                          \
 606                         "\t.section .fixup, \"ax\"\n"                   \
 607                         "3:\tmov     %3, %0\n"                          \
 608                         "\tjmp     2b\n"                                \
 609                         "\t.previous\n"                                 \
 610                         _ASM_EXTABLE(1b, 3b)                            \
 611                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 612                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 613                         : "memory"                                      \
 614                 );                                                      \
 615                 break;                                                  \
 616         }                                                               \
 617         case 8:                                                         \
 618         {                                                               \
 619                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 620                         __cmpxchg_wrong_size();                         \
 621                                                                         \
 622                 asm volatile("\n"                                       \
 623                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 624                         "2:\n"                                          \
 625                         "\t.section .fixup, \"ax\"\n"                   \
 626                         "3:\tmov     %3, %0\n"                          \
 627                         "\tjmp     2b\n"                                \
 628                         "\t.previous\n"                                 \
 629                         _ASM_EXTABLE(1b, 3b)                            \
 630                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 631                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 632                         : "memory"                                      \
 633                 );                                                      \
 634                 break;                                                  \
 635         }                                                               \
 636         default:                                                        \
 637                 __cmpxchg_wrong_size();                                 \
 638         }                                                               \
 639         __uaccess_end();                                                \
 640         *__uval = __old;                                                \
 641         __ret;                                                          \
 642 })
 643
 644 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 645 ({                                                                      \
 646         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 647                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 648                                 (old), (new), sizeof(*(ptr))) :         \
 649                 -EFAULT;                                                \
 650 })
 651
 652 /*
 653  * movsl can be slow when source and dest are not both 8-byte aligned
 654  */
 655 #ifdef CONFIG_X86_INTEL_USERCOPY
 656 extern struct movsl_mask {
 657         int mask;
 658 } ____cacheline_aligned_in_smp movsl_mask;
 659 #endif
 660
 661 #define ARCH_HAS_NOCACHE_UACCESS 1
 662
 663 #ifdef CONFIG_X86_32
 664 # include <asm/uaccess_32.h>
 665 #else
 666 # include <asm/uaccess_64.h>
 667 #endif
 668
 669 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 670                                            unsigned n);
 671 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 672                                          unsigned n);
 673
 674 extern void __compiletime_error("usercopy buffer size is too small")
 675 __bad_copy_user(void);
 676
 677 static inline void copy_user_overflow(int size, unsigned long count)
 678 {
 679         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 680 }
 681
 682 static __always_inline unsigned long __must_check
 683 copy_from_user(void *to, const void __user *from, unsigned long n)
 684 {
 685         int sz = __compiletime_object_size(to);
 686
 687         might_fault();
 688
 689         kasan_check_write(to, n);
 690
 691         if (likely(sz < 0 || sz >= n)) {
 692                 check_object_size(to, n, false);
 693                 n = _copy_from_user(to, from, n);
 694         } else if (!__builtin_constant_p(n))
 695                 copy_user_overflow(sz, n);
 696         else
 697                 __bad_copy_user();
 698
 699         return n;
 700 }
 701
 702 static __always_inline unsigned long __must_check
 703 copy_to_user(void __user *to, const void *from, unsigned long n)
 704 {
 705         int sz = __compiletime_object_size(from);
 706
 707         kasan_check_read(from, n);
 708
 709         might_fault();
 710
 711         if (likely(sz < 0 || sz >= n)) {
 712                 check_object_size(from, n, true);
 713                 n = _copy_to_user(to, from, n);
 714         } else if (!__builtin_constant_p(n))
 715                 copy_user_overflow(sz, n);
 716         else
 717                 __bad_copy_user();
 718
 719         return n;
 720 }
 721
 722 /*
 723  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 724  * nested NMI paths are careful to preserve CR2.
 725  *
 726  * Caller must use pagefault_enable/disable, or run in interrupt context,
 727  * and also do a uaccess_ok() check
 728  */
 729 #define __copy_from_user_nmi __copy_from_user_inatomic
 730
 731 /*
 732  * The "unsafe" user accesses aren't really "unsafe", but the naming
 733  * is a big fat warning: you have to not only do the access_ok()
 734  * checking before using them, but you have to surround them with the
 735  * user_access_begin/end() pair.
 736  */
 737 #define user_access_begin()     __uaccess_begin()
 738 #define user_access_end()       __uaccess_end()
 739
 740 #define unsafe_put_user(x, ptr, err_label)                                      \
 741 do {                                                                            \
 742         int __pu_err;                                                           \
 743         __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);         \
 744         if (unlikely(__pu_err)) goto err_label;                                 \
 745 } while (0)
 746
 747 #define unsafe_get_user(x, ptr, err_label)                                      \
 748 do {                                                                            \
 749         int __gu_err;                                                           \
 750         unsigned long __gu_val;                                                 \
 751         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 752         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 753         if (unlikely(__gu_err)) goto err_label;                                 \
 754 } while (0)
 755
 756 #endif /* _ASM_X86_UACCESS_H */
 757