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/thread_info.h>
   9 #include <linux/string.h>
  10 #include <asm/asm.h>
  11 #include <asm/page.h>
  12 #include <asm/smap.h>
  13
  14 #define VERIFY_READ 0
  15 #define VERIFY_WRITE 1
  16
  17 /*
  18  * The fs value determines whether argument validity checking should be
  19  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  20  * get_fs() == KERNEL_DS, checking is bypassed.
  21  *
  22  * For historical reasons, these macros are grossly misnamed.
  23  */
  24
  25 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  26
  27 #define KERNEL_DS       MAKE_MM_SEG(-1UL)
  28 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_MAX)
  29
  30 #define get_ds()        (KERNEL_DS)
  31 #define get_fs()        (current_thread_info()->addr_limit)
  32 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  33
  34 #define segment_eq(a, b)        ((a).seg == (b).seg)
  35
  36 #define user_addr_max() (current_thread_info()->addr_limit.seg)
  37 #define __addr_ok(addr)         \
  38         ((unsigned long __force)(addr) < user_addr_max())
  39
  40 /*
  41  * Test whether a block of memory is a valid user space address.
  42  * Returns 0 if the range is valid, nonzero otherwise.
  43  */
  44 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
  45 {
  46         /*
  47          * If we have used "sizeof()" for the size,
  48          * we know it won't overflow the limit (but
  49          * it might overflow the 'addr', so it's
  50          * important to subtract the size from the
  51          * limit, not add it to the address).
  52          */
  53         if (__builtin_constant_p(size))
  54                 return unlikely(addr > limit - size);
  55
  56         /* Arbitrary sizes? Be careful about overflow */
  57         addr += size;
  58         if (unlikely(addr < size))
  59                 return true;
  60         return unlikely(addr > limit);
  61 }
  62
  63 #define __range_not_ok(addr, size, limit)                               \
  64 ({                                                                      \
  65         __chk_user_ptr(addr);                                           \
  66         __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
  67 })
  68
  69 /**
  70  * access_ok: - Checks if a user space pointer is valid
  71  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  72  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  73  *        to write to a block, it is always safe to read from it.
  74  * @addr: User space pointer to start of block to check
  75  * @size: Size of block to check
  76  *
  77  * Context: User context only. This function may sleep if pagefaults are
  78  *          enabled.
  79  *
  80  * Checks if a pointer to a block of memory in user space is valid.
  81  *
  82  * Returns true (nonzero) if the memory block may be valid, false (zero)
  83  * if it is definitely invalid.
  84  *
  85  * Note that, depending on architecture, this function probably just
  86  * checks that the pointer is in the user space range - after calling
  87  * this function, memory access functions may still return -EFAULT.
  88  */
  89 #define access_ok(type, addr, size) \
  90         likely(!__range_not_ok(addr, size, user_addr_max()))
  91
  92 /*
  93  * The exception table consists of triples of addresses relative to the
  94  * exception table entry itself. The first address is of an instruction
  95  * that is allowed to fault, the second is the target at which the program
  96  * should continue. The third is a handler function to deal with the fault
  97  * caused by the instruction in the first field.
  98  *
  99  * All the routines below use bits of fixup code that are out of line
 100  * with the main instruction path.  This means when everything is well,
 101  * we don't even have to jump over them.  Further, they do not intrude
 102  * on our cache or tlb entries.
 103  */
 104
 105 struct exception_table_entry {
 106         int insn, fixup, handler;
 107 };
 108 /* This is not the generic standard exception_table_entry format */
 109 #define ARCH_HAS_SORT_EXTABLE
 110 #define ARCH_HAS_SEARCH_EXTABLE
 111
 112 extern int fixup_exception(struct pt_regs *regs, int trapnr);
 113 extern bool ex_has_fault_handler(unsigned long ip);
 114 extern int early_fixup_exception(unsigned long *ip);
 115
 116 /*
 117  * These are the main single-value transfer routines.  They automatically
 118  * use the right size if we just have the right pointer type.
 119  *
 120  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 121  * and yet we don't want to do any pointers, because that is too much
 122  * of a performance impact. Thus we have a few rather ugly macros here,
 123  * and hide all the ugliness from the user.
 124  *
 125  * The "__xxx" versions of the user access functions are versions that
 126  * do not verify the address space, that must have been done previously
 127  * with a separate "access_ok()" call (this is used when we do multiple
 128  * accesses to the same area of user memory).
 129  */
 130
 131 extern int __get_user_1(void);
 132 extern int __get_user_2(void);
 133 extern int __get_user_4(void);
 134 extern int __get_user_8(void);
 135 extern int __get_user_bad(void);
 136
 137 #define __uaccess_begin() stac()
 138 #define __uaccess_end()   clac()
 139
 140 /*
 141  * This is a type: either unsigned long, if the argument fits into
 142  * that type, or otherwise unsigned long long.
 143  */
 144 #define __inttype(x) \
 145 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 146
 147 /**
 148  * get_user: - Get a simple variable from user space.
 149  * @x:   Variable to store result.
 150  * @ptr: Source address, in user space.
 151  *
 152  * Context: User context only. This function may sleep if pagefaults are
 153  *          enabled.
 154  *
 155  * This macro copies a single simple variable from user space to kernel
 156  * space.  It supports simple types like char and int, but not larger
 157  * data types like structures or arrays.
 158  *
 159  * @ptr must have pointer-to-simple-variable type, and the result of
 160  * dereferencing @ptr must be assignable to @x without a cast.
 161  *
 162  * Returns zero on success, or -EFAULT on error.
 163  * On error, the variable @x is set to zero.
 164  */
 165 /*
 166  * Careful: we have to cast the result to the type of the pointer
 167  * for sign reasons.
 168  *
 169  * The use of _ASM_DX as the register specifier is a bit of a
 170  * simplification, as gcc only cares about it as the starting point
 171  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 172  * (%ecx being the next register in gcc's x86 register sequence), and
 173  * %rdx on 64 bits.
 174  *
 175  * Clang/LLVM cares about the size of the register, but still wants
 176  * the base register for something that ends up being a pair.
 177  */
 178 #define get_user(x, ptr)                                                \
 179 ({                                                                      \
 180         int __ret_gu;                                                   \
 181         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 182         register void *__sp asm(_ASM_SP);                               \
 183         __chk_user_ptr(ptr);                                            \
 184         might_fault();                                                  \
 185         asm volatile("call __get_user_%P4"                              \
 186                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 187                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 188         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 189         __builtin_expect(__ret_gu, 0);                                  \
 190 })
 191
 192 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 193         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 194                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 195
 196
 197
 198 #ifdef CONFIG_X86_32
 199 #define __put_user_asm_u64(x, addr, err, errret)                        \
 200         asm volatile("\n"                                               \
 201                      "1:        movl %%eax,0(%2)\n"                     \
 202                      "2:        movl %%edx,4(%2)\n"                     \
 203                      "3:"                                               \
 204                      ".section .fixup,\"ax\"\n"                         \
 205                      "4:        movl %3,%0\n"                           \
 206                      "  jmp 3b\n"                                       \
 207                      ".previous\n"                                      \
 208                      _ASM_EXTABLE(1b, 4b)                               \
 209                      _ASM_EXTABLE(2b, 4b)                               \
 210                      : "=r" (err)                                       \
 211                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 212
 213 #define __put_user_asm_ex_u64(x, addr)                                  \
 214         asm volatile("\n"                                               \
 215                      "1:        movl %%eax,0(%1)\n"                     \
 216                      "2:        movl %%edx,4(%1)\n"                     \
 217                      "3:"                                               \
 218                      _ASM_EXTABLE_EX(1b, 2b)                            \
 219                      _ASM_EXTABLE_EX(2b, 3b)                            \
 220                      : : "A" (x), "r" (addr))
 221
 222 #define __put_user_x8(x, ptr, __ret_pu)                         \
 223         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 224                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 225 #else
 226 #define __put_user_asm_u64(x, ptr, retval, errret) \
 227         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 228 #define __put_user_asm_ex_u64(x, addr)  \
 229         __put_user_asm_ex(x, addr, "q", "", "er")
 230 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 231 #endif
 232
 233 extern void __put_user_bad(void);
 234
 235 /*
 236  * Strange magic calling convention: pointer in %ecx,
 237  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 238  */
 239 extern void __put_user_1(void);
 240 extern void __put_user_2(void);
 241 extern void __put_user_4(void);
 242 extern void __put_user_8(void);
 243
 244 /**
 245  * put_user: - Write a simple value into user space.
 246  * @x:   Value to copy to user space.
 247  * @ptr: Destination address, in user space.
 248  *
 249  * Context: User context only. This function may sleep if pagefaults are
 250  *          enabled.
 251  *
 252  * This macro copies a single simple value from kernel space to user
 253  * space.  It supports simple types like char and int, but not larger
 254  * data types like structures or arrays.
 255  *
 256  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 257  * to the result of dereferencing @ptr.
 258  *
 259  * Returns zero on success, or -EFAULT on error.
 260  */
 261 #define put_user(x, ptr)                                        \
 262 ({                                                              \
 263         int __ret_pu;                                           \
 264         __typeof__(*(ptr)) __pu_val;                            \
 265         __chk_user_ptr(ptr);                                    \
 266         might_fault();                                          \
 267         __pu_val = x;                                           \
 268         switch (sizeof(*(ptr))) {                               \
 269         case 1:                                                 \
 270                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 271                 break;                                          \
 272         case 2:                                                 \
 273                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 274                 break;                                          \
 275         case 4:                                                 \
 276                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 277                 break;                                          \
 278         case 8:                                                 \
 279                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 280                 break;                                          \
 281         default:                                                \
 282                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 283                 break;                                          \
 284         }                                                       \
 285         __builtin_expect(__ret_pu, 0);                          \
 286 })
 287
 288 #define __put_user_size(x, ptr, size, retval, errret)                   \
 289 do {                                                                    \
 290         retval = 0;                                                     \
 291         __chk_user_ptr(ptr);                                            \
 292         switch (size) {                                                 \
 293         case 1:                                                         \
 294                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 295                 break;                                                  \
 296         case 2:                                                         \
 297                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 298                 break;                                                  \
 299         case 4:                                                         \
 300                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 301                 break;                                                  \
 302         case 8:                                                         \
 303                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 304                                    errret);                             \
 305                 break;                                                  \
 306         default:                                                        \
 307                 __put_user_bad();                                       \
 308         }                                                               \
 309 } while (0)
 310
 311 /*
 312  * This doesn't do __uaccess_begin/end - the exception handling
 313  * around it must do that.
 314  */
 315 #define __put_user_size_ex(x, ptr, size)                                \
 316 do {                                                                    \
 317         __chk_user_ptr(ptr);                                            \
 318         switch (size) {                                                 \
 319         case 1:                                                         \
 320                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 321                 break;                                                  \
 322         case 2:                                                         \
 323                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 324                 break;                                                  \
 325         case 4:                                                         \
 326                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 327                 break;                                                  \
 328         case 8:                                                         \
 329                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 330                 break;                                                  \
 331         default:                                                        \
 332                 __put_user_bad();                                       \
 333         }                                                               \
 334 } while (0)
 335
 336 #ifdef CONFIG_X86_32
 337 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 338 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 339 #else
 340 #define __get_user_asm_u64(x, ptr, retval, errret) \
 341          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 342 #define __get_user_asm_ex_u64(x, ptr) \
 343          __get_user_asm_ex(x, ptr, "q", "", "=r")
 344 #endif
 345
 346 #define __get_user_size(x, ptr, size, retval, errret)                   \
 347 do {                                                                    \
 348         retval = 0;                                                     \
 349         __chk_user_ptr(ptr);                                            \
 350         switch (size) {                                                 \
 351         case 1:                                                         \
 352                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 353                 break;                                                  \
 354         case 2:                                                         \
 355                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 356                 break;                                                  \
 357         case 4:                                                         \
 358                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 359                 break;                                                  \
 360         case 8:                                                         \
 361                 __get_user_asm_u64(x, ptr, retval, errret);             \
 362                 break;                                                  \
 363         default:                                                        \
 364                 (x) = __get_user_bad();                                 \
 365         }                                                               \
 366 } while (0)
 367
 368 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 369         asm volatile("\n"                                               \
 370                      "1:        mov"itype" %2,%"rtype"1\n"              \
 371                      "2:\n"                                             \
 372                      ".section .fixup,\"ax\"\n"                         \
 373                      "3:        mov %3,%0\n"                            \
 374                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 375                      "  jmp 2b\n"                                       \
 376                      ".previous\n"                                      \
 377                      _ASM_EXTABLE(1b, 3b)                               \
 378                      : "=r" (err), ltype(x)                             \
 379                      : "m" (__m(addr)), "i" (errret), "0" (err))
 380
 381 /*
 382  * This doesn't do __uaccess_begin/end - the exception handling
 383  * around it must do that.
 384  */
 385 #define __get_user_size_ex(x, ptr, size)                                \
 386 do {                                                                    \
 387         __chk_user_ptr(ptr);                                            \
 388         switch (size) {                                                 \
 389         case 1:                                                         \
 390                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 391                 break;                                                  \
 392         case 2:                                                         \
 393                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 394                 break;                                                  \
 395         case 4:                                                         \
 396                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 397                 break;                                                  \
 398         case 8:                                                         \
 399                 __get_user_asm_ex_u64(x, ptr);                          \
 400                 break;                                                  \
 401         default:                                                        \
 402                 (x) = __get_user_bad();                                 \
 403         }                                                               \
 404 } while (0)
 405
 406 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 407         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 408                      "2:\n"                                             \
 409                      _ASM_EXTABLE_EX(1b, 2b)                            \
 410                      : ltype(x) : "m" (__m(addr)))
 411
 412 #define __put_user_nocheck(x, ptr, size)                        \
 413 ({                                                              \
 414         int __pu_err;                                           \
 415         __uaccess_begin();                                      \
 416         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 417         __uaccess_end();                                        \
 418         __builtin_expect(__pu_err, 0);                          \
 419 })
 420
 421 #define __get_user_nocheck(x, ptr, size)                                \
 422 ({                                                                      \
 423         int __gu_err;                                                   \
 424         unsigned long __gu_val;                                         \
 425         __uaccess_begin();                                              \
 426         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 427         __uaccess_end();                                                \
 428         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 429         __builtin_expect(__gu_err, 0);                                  \
 430 })
 431
 432 /* FIXME: this hack is definitely wrong -AK */
 433 struct __large_struct { unsigned long buf[100]; };
 434 #define __m(x) (*(struct __large_struct __user *)(x))
 435
 436 /*
 437  * Tell gcc we read from memory instead of writing: this is because
 438  * we do not write to any memory gcc knows about, so there are no
 439  * aliasing issues.
 440  */
 441 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 442         asm volatile("\n"                                               \
 443                      "1:        mov"itype" %"rtype"1,%2\n"              \
 444                      "2:\n"                                             \
 445                      ".section .fixup,\"ax\"\n"                         \
 446                      "3:        mov %3,%0\n"                            \
 447                      "  jmp 2b\n"                                       \
 448                      ".previous\n"                                      \
 449                      _ASM_EXTABLE(1b, 3b)                               \
 450                      : "=r"(err)                                        \
 451                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 452
 453 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 454         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 455                      "2:\n"                                             \
 456                      _ASM_EXTABLE_EX(1b, 2b)                            \
 457                      : : ltype(x), "m" (__m(addr)))
 458
 459 /*
 460  * uaccess_try and catch
 461  */
 462 #define uaccess_try     do {                                            \
 463         current_thread_info()->uaccess_err = 0;                         \
 464         __uaccess_begin();                                              \
 465         barrier();
 466
 467 #define uaccess_catch(err)                                              \
 468         __uaccess_end();                                                \
 469         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 470 } while (0)
 471
 472 /**
 473  * __get_user: - Get a simple variable from user space, with less checking.
 474  * @x:   Variable to store result.
 475  * @ptr: Source address, in user space.
 476  *
 477  * Context: User context only. This function may sleep if pagefaults are
 478  *          enabled.
 479  *
 480  * This macro copies a single simple variable from user space to kernel
 481  * space.  It supports simple types like char and int, but not larger
 482  * data types like structures or arrays.
 483  *
 484  * @ptr must have pointer-to-simple-variable type, and the result of
 485  * dereferencing @ptr must be assignable to @x without a cast.
 486  *
 487  * Caller must check the pointer with access_ok() before calling this
 488  * function.
 489  *
 490  * Returns zero on success, or -EFAULT on error.
 491  * On error, the variable @x is set to zero.
 492  */
 493
 494 #define __get_user(x, ptr)                                              \
 495         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 496
 497 /**
 498  * __put_user: - Write a simple value into user space, with less checking.
 499  * @x:   Value to copy to user space.
 500  * @ptr: Destination address, in user space.
 501  *
 502  * Context: User context only. This function may sleep if pagefaults are
 503  *          enabled.
 504  *
 505  * This macro copies a single simple value from kernel space to user
 506  * space.  It supports simple types like char and int, but not larger
 507  * data types like structures or arrays.
 508  *
 509  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 510  * to the result of dereferencing @ptr.
 511  *
 512  * Caller must check the pointer with access_ok() before calling this
 513  * function.
 514  *
 515  * Returns zero on success, or -EFAULT on error.
 516  */
 517
 518 #define __put_user(x, ptr)                                              \
 519         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 520
 521 #define __get_user_unaligned __get_user
 522 #define __put_user_unaligned __put_user
 523
 524 /*
 525  * {get|put}_user_try and catch
 526  *
 527  * get_user_try {
 528  *      get_user_ex(...);
 529  * } get_user_catch(err)
 530  */
 531 #define get_user_try            uaccess_try
 532 #define get_user_catch(err)     uaccess_catch(err)
 533
 534 #define get_user_ex(x, ptr)     do {                                    \
 535         unsigned long __gue_val;                                        \
 536         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 537         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 538 } while (0)
 539
 540 #define put_user_try            uaccess_try
 541 #define put_user_catch(err)     uaccess_catch(err)
 542
 543 #define put_user_ex(x, ptr)                                             \
 544         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 545
 546 extern unsigned long
 547 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 548 extern __must_check long
 549 strncpy_from_user(char *dst, const char __user *src, long count);
 550
 551 extern __must_check long strlen_user(const char __user *str);
 552 extern __must_check long strnlen_user(const char __user *str, long n);
 553
 554 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 555 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 556
 557 extern void __cmpxchg_wrong_size(void)
 558         __compiletime_error("Bad argument size for cmpxchg");
 559
 560 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 561 ({                                                                      \
 562         int __ret = 0;                                                  \
 563         __typeof__(ptr) __uval = (uval);                                \
 564         __typeof__(*(ptr)) __old = (old);                               \
 565         __typeof__(*(ptr)) __new = (new);                               \
 566         __uaccess_begin();                                              \
 567         switch (size) {                                                 \
 568         case 1:                                                         \
 569         {                                                               \
 570                 asm volatile("\n"                                       \
 571                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 572                         "2:\n"                                          \
 573                         "\t.section .fixup, \"ax\"\n"                   \
 574                         "3:\tmov     %3, %0\n"                          \
 575                         "\tjmp     2b\n"                                \
 576                         "\t.previous\n"                                 \
 577                         _ASM_EXTABLE(1b, 3b)                            \
 578                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 579                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 580                         : "memory"                                      \
 581                 );                                                      \
 582                 break;                                                  \
 583         }                                                               \
 584         case 2:                                                         \
 585         {                                                               \
 586                 asm volatile("\n"                                       \
 587                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 588                         "2:\n"                                          \
 589                         "\t.section .fixup, \"ax\"\n"                   \
 590                         "3:\tmov     %3, %0\n"                          \
 591                         "\tjmp     2b\n"                                \
 592                         "\t.previous\n"                                 \
 593                         _ASM_EXTABLE(1b, 3b)                            \
 594                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 595                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 596                         : "memory"                                      \
 597                 );                                                      \
 598                 break;                                                  \
 599         }                                                               \
 600         case 4:                                                         \
 601         {                                                               \
 602                 asm volatile("\n"                                       \
 603                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 604                         "2:\n"                                          \
 605                         "\t.section .fixup, \"ax\"\n"                   \
 606                         "3:\tmov     %3, %0\n"                          \
 607                         "\tjmp     2b\n"                                \
 608                         "\t.previous\n"                                 \
 609                         _ASM_EXTABLE(1b, 3b)                            \
 610                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 611                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 612                         : "memory"                                      \
 613                 );                                                      \
 614                 break;                                                  \
 615         }                                                               \
 616         case 8:                                                         \
 617         {                                                               \
 618                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 619                         __cmpxchg_wrong_size();                         \
 620                                                                         \
 621                 asm volatile("\n"                                       \
 622                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 623                         "2:\n"                                          \
 624                         "\t.section .fixup, \"ax\"\n"                   \
 625                         "3:\tmov     %3, %0\n"                          \
 626                         "\tjmp     2b\n"                                \
 627                         "\t.previous\n"                                 \
 628                         _ASM_EXTABLE(1b, 3b)                            \
 629                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 630                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 631                         : "memory"                                      \
 632                 );                                                      \
 633                 break;                                                  \
 634         }                                                               \
 635         default:                                                        \
 636                 __cmpxchg_wrong_size();                                 \
 637         }                                                               \
 638         __uaccess_end();                                                \
 639         *__uval = __old;                                                \
 640         __ret;                                                          \
 641 })
 642
 643 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 644 ({                                                                      \
 645         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 646                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 647                                 (old), (new), sizeof(*(ptr))) :         \
 648                 -EFAULT;                                                \
 649 })
 650
 651 /*
 652  * movsl can be slow when source and dest are not both 8-byte aligned
 653  */
 654 #ifdef CONFIG_X86_INTEL_USERCOPY
 655 extern struct movsl_mask {
 656         int mask;
 657 } ____cacheline_aligned_in_smp movsl_mask;
 658 #endif
 659
 660 #define ARCH_HAS_NOCACHE_UACCESS 1
 661
 662 #ifdef CONFIG_X86_32
 663 # include <asm/uaccess_32.h>
 664 #else
 665 # include <asm/uaccess_64.h>
 666 #endif
 667
 668 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 669                                            unsigned n);
 670 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 671                                          unsigned n);
 672
 673 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 674 # define copy_user_diag __compiletime_error
 675 #else
 676 # define copy_user_diag __compiletime_warning
 677 #endif
 678
 679 extern void copy_user_diag("copy_from_user() buffer size is too small")
 680 copy_from_user_overflow(void);
 681 extern void copy_user_diag("copy_to_user() buffer size is too small")
 682 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 683
 684 #undef copy_user_diag
 685
 686 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 687
 688 extern void
 689 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 690 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
 691 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
 692
 693 extern void
 694 __compiletime_warning("copy_to_user() buffer size is not provably correct")
 695 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 696 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
 697
 698 #else
 699
 700 static inline void
 701 __copy_from_user_overflow(int size, unsigned long count)
 702 {
 703         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 704 }
 705
 706 #define __copy_to_user_overflow __copy_from_user_overflow
 707
 708 #endif
 709
 710 static inline unsigned long __must_check
 711 copy_from_user(void *to, const void __user *from, unsigned long n)
 712 {
 713         int sz = __compiletime_object_size(to);
 714
 715         might_fault();
 716
 717         /*
 718          * While we would like to have the compiler do the checking for us
 719          * even in the non-constant size case, any false positives there are
 720          * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
 721          * without - the [hopefully] dangerous looking nature of the warning
 722          * would make people go look at the respecitive call sites over and
 723          * over again just to find that there's no problem).
 724          *
 725          * And there are cases where it's just not realistic for the compiler
 726          * to prove the count to be in range. For example when multiple call
 727          * sites of a helper function - perhaps in different source files -
 728          * all doing proper range checking, yet the helper function not doing
 729          * so again.
 730          *
 731          * Therefore limit the compile time checking to the constant size
 732          * case, and do only runtime checking for non-constant sizes.
 733          */
 734
 735         if (likely(sz < 0 || sz >= n))
 736                 n = _copy_from_user(to, from, n);
 737         else if(__builtin_constant_p(n))
 738                 copy_from_user_overflow();
 739         else
 740                 __copy_from_user_overflow(sz, n);
 741
 742         return n;
 743 }
 744
 745 static inline unsigned long __must_check
 746 copy_to_user(void __user *to, const void *from, unsigned long n)
 747 {
 748         int sz = __compiletime_object_size(from);
 749
 750         might_fault();
 751
 752         /* See the comment in copy_from_user() above. */
 753         if (likely(sz < 0 || sz >= n))
 754                 n = _copy_to_user(to, from, n);
 755         else if(__builtin_constant_p(n))
 756                 copy_to_user_overflow();
 757         else
 758                 __copy_to_user_overflow(sz, n);
 759
 760         return n;
 761 }
 762
 763 #undef __copy_from_user_overflow
 764 #undef __copy_to_user_overflow
 765
 766 /*
 767  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 768  * nested NMI paths are careful to preserve CR2.
 769  *
 770  * Caller must use pagefault_enable/disable, or run in interrupt context,
 771  * and also do a uaccess_ok() check
 772  */
 773 #define __copy_from_user_nmi __copy_from_user_inatomic
 774
 775 /*
 776  * The "unsafe" user accesses aren't really "unsafe", but the naming
 777  * is a big fat warning: you have to not only do the access_ok()
 778  * checking before using them, but you have to surround them with the
 779  * user_access_begin/end() pair.
 780  */
 781 #define user_access_begin()     __uaccess_begin()
 782 #define user_access_end()       __uaccess_end()
 783
 784 #define unsafe_put_user(x, ptr)                                         \
 785 ({                                                                              \
 786         int __pu_err;                                                           \
 787         __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);         \
 788         __builtin_expect(__pu_err, 0);                                          \
 789 })
 790
 791 #define unsafe_get_user(x, ptr)                                         \
 792 ({                                                                              \
 793         int __gu_err;                                                           \
 794         unsigned long __gu_val;                                                 \
 795         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 796         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 797         __builtin_expect(__gu_err, 0);                                          \
 798 })
 799
 800 #endif /* _ASM_X86_UACCESS_H */
 801