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
 109 #define ARCH_HAS_RELATIVE_EXTABLE
 110
 111 #define swap_ex_entry_fixup(a, b, tmp, delta)                   \
 112         do {                                                    \
 113                 (a)->fixup = (b)->fixup + (delta);              \
 114                 (b)->fixup = (tmp).fixup - (delta);             \
 115                 (a)->handler = (b)->handler + (delta);          \
 116                 (b)->handler = (tmp).handler - (delta);         \
 117         } while (0)
 118
 119 extern int fixup_exception(struct pt_regs *regs, int trapnr);
 120 extern bool ex_has_fault_handler(unsigned long ip);
 121 extern int early_fixup_exception(unsigned long *ip);
 122
 123 /*
 124  * These are the main single-value transfer routines.  They automatically
 125  * use the right size if we just have the right pointer type.
 126  *
 127  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 128  * and yet we don't want to do any pointers, because that is too much
 129  * of a performance impact. Thus we have a few rather ugly macros here,
 130  * and hide all the ugliness from the user.
 131  *
 132  * The "__xxx" versions of the user access functions are versions that
 133  * do not verify the address space, that must have been done previously
 134  * with a separate "access_ok()" call (this is used when we do multiple
 135  * accesses to the same area of user memory).
 136  */
 137
 138 extern int __get_user_1(void);
 139 extern int __get_user_2(void);
 140 extern int __get_user_4(void);
 141 extern int __get_user_8(void);
 142 extern int __get_user_bad(void);
 143
 144 #define __uaccess_begin() stac()
 145 #define __uaccess_end()   clac()
 146
 147 /*
 148  * This is a type: either unsigned long, if the argument fits into
 149  * that type, or otherwise unsigned long long.
 150  */
 151 #define __inttype(x) \
 152 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 153
 154 /**
 155  * get_user: - Get a simple variable from user space.
 156  * @x:   Variable to store result.
 157  * @ptr: Source address, in user space.
 158  *
 159  * Context: User context only. This function may sleep if pagefaults are
 160  *          enabled.
 161  *
 162  * This macro copies a single simple variable from user space to kernel
 163  * space.  It supports simple types like char and int, but not larger
 164  * data types like structures or arrays.
 165  *
 166  * @ptr must have pointer-to-simple-variable type, and the result of
 167  * dereferencing @ptr must be assignable to @x without a cast.
 168  *
 169  * Returns zero on success, or -EFAULT on error.
 170  * On error, the variable @x is set to zero.
 171  */
 172 /*
 173  * Careful: we have to cast the result to the type of the pointer
 174  * for sign reasons.
 175  *
 176  * The use of _ASM_DX as the register specifier is a bit of a
 177  * simplification, as gcc only cares about it as the starting point
 178  * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 179  * (%ecx being the next register in gcc's x86 register sequence), and
 180  * %rdx on 64 bits.
 181  *
 182  * Clang/LLVM cares about the size of the register, but still wants
 183  * the base register for something that ends up being a pair.
 184  */
 185 #define get_user(x, ptr)                                                \
 186 ({                                                                      \
 187         int __ret_gu;                                                   \
 188         register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 189         register void *__sp asm(_ASM_SP);                               \
 190         __chk_user_ptr(ptr);                                            \
 191         might_fault();                                                  \
 192         asm volatile("call __get_user_%P4"                              \
 193                      : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)    \
 194                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 195         (x) = (__force __typeof__(*(ptr))) __val_gu;                    \
 196         __builtin_expect(__ret_gu, 0);                                  \
 197 })
 198
 199 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 200         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 201                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 202
 203
 204
 205 #ifdef CONFIG_X86_32
 206 #define __put_user_asm_u64(x, addr, err, errret)                        \
 207         asm volatile("\n"                                               \
 208                      "1:        movl %%eax,0(%2)\n"                     \
 209                      "2:        movl %%edx,4(%2)\n"                     \
 210                      "3:"                                               \
 211                      ".section .fixup,\"ax\"\n"                         \
 212                      "4:        movl %3,%0\n"                           \
 213                      "  jmp 3b\n"                                       \
 214                      ".previous\n"                                      \
 215                      _ASM_EXTABLE(1b, 4b)                               \
 216                      _ASM_EXTABLE(2b, 4b)                               \
 217                      : "=r" (err)                                       \
 218                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 219
 220 #define __put_user_asm_ex_u64(x, addr)                                  \
 221         asm volatile("\n"                                               \
 222                      "1:        movl %%eax,0(%1)\n"                     \
 223                      "2:        movl %%edx,4(%1)\n"                     \
 224                      "3:"                                               \
 225                      _ASM_EXTABLE_EX(1b, 2b)                            \
 226                      _ASM_EXTABLE_EX(2b, 3b)                            \
 227                      : : "A" (x), "r" (addr))
 228
 229 #define __put_user_x8(x, ptr, __ret_pu)                         \
 230         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 231                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 232 #else
 233 #define __put_user_asm_u64(x, ptr, retval, errret) \
 234         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 235 #define __put_user_asm_ex_u64(x, addr)  \
 236         __put_user_asm_ex(x, addr, "q", "", "er")
 237 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 238 #endif
 239
 240 extern void __put_user_bad(void);
 241
 242 /*
 243  * Strange magic calling convention: pointer in %ecx,
 244  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 245  */
 246 extern void __put_user_1(void);
 247 extern void __put_user_2(void);
 248 extern void __put_user_4(void);
 249 extern void __put_user_8(void);
 250
 251 /**
 252  * put_user: - Write a simple value into user space.
 253  * @x:   Value to copy to user space.
 254  * @ptr: Destination address, in user space.
 255  *
 256  * Context: User context only. This function may sleep if pagefaults are
 257  *          enabled.
 258  *
 259  * This macro copies a single simple value from kernel space to user
 260  * space.  It supports simple types like char and int, but not larger
 261  * data types like structures or arrays.
 262  *
 263  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 264  * to the result of dereferencing @ptr.
 265  *
 266  * Returns zero on success, or -EFAULT on error.
 267  */
 268 #define put_user(x, ptr)                                        \
 269 ({                                                              \
 270         int __ret_pu;                                           \
 271         __typeof__(*(ptr)) __pu_val;                            \
 272         __chk_user_ptr(ptr);                                    \
 273         might_fault();                                          \
 274         __pu_val = x;                                           \
 275         switch (sizeof(*(ptr))) {                               \
 276         case 1:                                                 \
 277                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 278                 break;                                          \
 279         case 2:                                                 \
 280                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 281                 break;                                          \
 282         case 4:                                                 \
 283                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 284                 break;                                          \
 285         case 8:                                                 \
 286                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 287                 break;                                          \
 288         default:                                                \
 289                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 290                 break;                                          \
 291         }                                                       \
 292         __builtin_expect(__ret_pu, 0);                          \
 293 })
 294
 295 #define __put_user_size(x, ptr, size, retval, errret)                   \
 296 do {                                                                    \
 297         retval = 0;                                                     \
 298         __chk_user_ptr(ptr);                                            \
 299         switch (size) {                                                 \
 300         case 1:                                                         \
 301                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 302                 break;                                                  \
 303         case 2:                                                         \
 304                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 305                 break;                                                  \
 306         case 4:                                                         \
 307                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 308                 break;                                                  \
 309         case 8:                                                         \
 310                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 311                                    errret);                             \
 312                 break;                                                  \
 313         default:                                                        \
 314                 __put_user_bad();                                       \
 315         }                                                               \
 316 } while (0)
 317
 318 /*
 319  * This doesn't do __uaccess_begin/end - the exception handling
 320  * around it must do that.
 321  */
 322 #define __put_user_size_ex(x, ptr, size)                                \
 323 do {                                                                    \
 324         __chk_user_ptr(ptr);                                            \
 325         switch (size) {                                                 \
 326         case 1:                                                         \
 327                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 328                 break;                                                  \
 329         case 2:                                                         \
 330                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 331                 break;                                                  \
 332         case 4:                                                         \
 333                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 334                 break;                                                  \
 335         case 8:                                                         \
 336                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 337                 break;                                                  \
 338         default:                                                        \
 339                 __put_user_bad();                                       \
 340         }                                                               \
 341 } while (0)
 342
 343 #ifdef CONFIG_X86_32
 344 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 345 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 346 #else
 347 #define __get_user_asm_u64(x, ptr, retval, errret) \
 348          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 349 #define __get_user_asm_ex_u64(x, ptr) \
 350          __get_user_asm_ex(x, ptr, "q", "", "=r")
 351 #endif
 352
 353 #define __get_user_size(x, ptr, size, retval, errret)                   \
 354 do {                                                                    \
 355         retval = 0;                                                     \
 356         __chk_user_ptr(ptr);                                            \
 357         switch (size) {                                                 \
 358         case 1:                                                         \
 359                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 360                 break;                                                  \
 361         case 2:                                                         \
 362                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 363                 break;                                                  \
 364         case 4:                                                         \
 365                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 366                 break;                                                  \
 367         case 8:                                                         \
 368                 __get_user_asm_u64(x, ptr, retval, errret);             \
 369                 break;                                                  \
 370         default:                                                        \
 371                 (x) = __get_user_bad();                                 \
 372         }                                                               \
 373 } while (0)
 374
 375 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 376         asm volatile("\n"                                               \
 377                      "1:        mov"itype" %2,%"rtype"1\n"              \
 378                      "2:\n"                                             \
 379                      ".section .fixup,\"ax\"\n"                         \
 380                      "3:        mov %3,%0\n"                            \
 381                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 382                      "  jmp 2b\n"                                       \
 383                      ".previous\n"                                      \
 384                      _ASM_EXTABLE(1b, 3b)                               \
 385                      : "=r" (err), ltype(x)                             \
 386                      : "m" (__m(addr)), "i" (errret), "0" (err))
 387
 388 /*
 389  * This doesn't do __uaccess_begin/end - the exception handling
 390  * around it must do that.
 391  */
 392 #define __get_user_size_ex(x, ptr, size)                                \
 393 do {                                                                    \
 394         __chk_user_ptr(ptr);                                            \
 395         switch (size) {                                                 \
 396         case 1:                                                         \
 397                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 398                 break;                                                  \
 399         case 2:                                                         \
 400                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 401                 break;                                                  \
 402         case 4:                                                         \
 403                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 404                 break;                                                  \
 405         case 8:                                                         \
 406                 __get_user_asm_ex_u64(x, ptr);                          \
 407                 break;                                                  \
 408         default:                                                        \
 409                 (x) = __get_user_bad();                                 \
 410         }                                                               \
 411 } while (0)
 412
 413 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 414         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 415                      "2:\n"                                             \
 416                      _ASM_EXTABLE_EX(1b, 2b)                            \
 417                      : ltype(x) : "m" (__m(addr)))
 418
 419 #define __put_user_nocheck(x, ptr, size)                        \
 420 ({                                                              \
 421         int __pu_err;                                           \
 422         __uaccess_begin();                                      \
 423         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 424         __uaccess_end();                                        \
 425         __builtin_expect(__pu_err, 0);                          \
 426 })
 427
 428 #define __get_user_nocheck(x, ptr, size)                                \
 429 ({                                                                      \
 430         int __gu_err;                                                   \
 431         unsigned long __gu_val;                                         \
 432         __uaccess_begin();                                              \
 433         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 434         __uaccess_end();                                                \
 435         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 436         __builtin_expect(__gu_err, 0);                                  \
 437 })
 438
 439 /* FIXME: this hack is definitely wrong -AK */
 440 struct __large_struct { unsigned long buf[100]; };
 441 #define __m(x) (*(struct __large_struct __user *)(x))
 442
 443 /*
 444  * Tell gcc we read from memory instead of writing: this is because
 445  * we do not write to any memory gcc knows about, so there are no
 446  * aliasing issues.
 447  */
 448 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 449         asm volatile("\n"                                               \
 450                      "1:        mov"itype" %"rtype"1,%2\n"              \
 451                      "2:\n"                                             \
 452                      ".section .fixup,\"ax\"\n"                         \
 453                      "3:        mov %3,%0\n"                            \
 454                      "  jmp 2b\n"                                       \
 455                      ".previous\n"                                      \
 456                      _ASM_EXTABLE(1b, 3b)                               \
 457                      : "=r"(err)                                        \
 458                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 459
 460 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 461         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 462                      "2:\n"                                             \
 463                      _ASM_EXTABLE_EX(1b, 2b)                            \
 464                      : : ltype(x), "m" (__m(addr)))
 465
 466 /*
 467  * uaccess_try and catch
 468  */
 469 #define uaccess_try     do {                                            \
 470         current_thread_info()->uaccess_err = 0;                         \
 471         __uaccess_begin();                                              \
 472         barrier();
 473
 474 #define uaccess_catch(err)                                              \
 475         __uaccess_end();                                                \
 476         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 477 } while (0)
 478
 479 /**
 480  * __get_user: - Get a simple variable from user space, with less checking.
 481  * @x:   Variable to store result.
 482  * @ptr: Source address, in user space.
 483  *
 484  * Context: User context only. This function may sleep if pagefaults are
 485  *          enabled.
 486  *
 487  * This macro copies a single simple variable from user space to kernel
 488  * space.  It supports simple types like char and int, but not larger
 489  * data types like structures or arrays.
 490  *
 491  * @ptr must have pointer-to-simple-variable type, and the result of
 492  * dereferencing @ptr must be assignable to @x without a cast.
 493  *
 494  * Caller must check the pointer with access_ok() before calling this
 495  * function.
 496  *
 497  * Returns zero on success, or -EFAULT on error.
 498  * On error, the variable @x is set to zero.
 499  */
 500
 501 #define __get_user(x, ptr)                                              \
 502         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 503
 504 /**
 505  * __put_user: - Write a simple value into user space, with less checking.
 506  * @x:   Value to copy to user space.
 507  * @ptr: Destination address, in user space.
 508  *
 509  * Context: User context only. This function may sleep if pagefaults are
 510  *          enabled.
 511  *
 512  * This macro copies a single simple value from kernel space to user
 513  * space.  It supports simple types like char and int, but not larger
 514  * data types like structures or arrays.
 515  *
 516  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 517  * to the result of dereferencing @ptr.
 518  *
 519  * Caller must check the pointer with access_ok() before calling this
 520  * function.
 521  *
 522  * Returns zero on success, or -EFAULT on error.
 523  */
 524
 525 #define __put_user(x, ptr)                                              \
 526         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 527
 528 #define __get_user_unaligned __get_user
 529 #define __put_user_unaligned __put_user
 530
 531 /*
 532  * {get|put}_user_try and catch
 533  *
 534  * get_user_try {
 535  *      get_user_ex(...);
 536  * } get_user_catch(err)
 537  */
 538 #define get_user_try            uaccess_try
 539 #define get_user_catch(err)     uaccess_catch(err)
 540
 541 #define get_user_ex(x, ptr)     do {                                    \
 542         unsigned long __gue_val;                                        \
 543         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 544         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 545 } while (0)
 546
 547 #define put_user_try            uaccess_try
 548 #define put_user_catch(err)     uaccess_catch(err)
 549
 550 #define put_user_ex(x, ptr)                                             \
 551         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 552
 553 extern unsigned long
 554 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 555 extern __must_check long
 556 strncpy_from_user(char *dst, const char __user *src, long count);
 557
 558 extern __must_check long strlen_user(const char __user *str);
 559 extern __must_check long strnlen_user(const char __user *str, long n);
 560
 561 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 562 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 563
 564 extern void __cmpxchg_wrong_size(void)
 565         __compiletime_error("Bad argument size for cmpxchg");
 566
 567 #define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 568 ({                                                                      \
 569         int __ret = 0;                                                  \
 570         __typeof__(ptr) __uval = (uval);                                \
 571         __typeof__(*(ptr)) __old = (old);                               \
 572         __typeof__(*(ptr)) __new = (new);                               \
 573         __uaccess_begin();                                              \
 574         switch (size) {                                                 \
 575         case 1:                                                         \
 576         {                                                               \
 577                 asm volatile("\n"                                       \
 578                         "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 579                         "2:\n"                                          \
 580                         "\t.section .fixup, \"ax\"\n"                   \
 581                         "3:\tmov     %3, %0\n"                          \
 582                         "\tjmp     2b\n"                                \
 583                         "\t.previous\n"                                 \
 584                         _ASM_EXTABLE(1b, 3b)                            \
 585                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 586                         : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 587                         : "memory"                                      \
 588                 );                                                      \
 589                 break;                                                  \
 590         }                                                               \
 591         case 2:                                                         \
 592         {                                                               \
 593                 asm volatile("\n"                                       \
 594                         "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 595                         "2:\n"                                          \
 596                         "\t.section .fixup, \"ax\"\n"                   \
 597                         "3:\tmov     %3, %0\n"                          \
 598                         "\tjmp     2b\n"                                \
 599                         "\t.previous\n"                                 \
 600                         _ASM_EXTABLE(1b, 3b)                            \
 601                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 602                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 603                         : "memory"                                      \
 604                 );                                                      \
 605                 break;                                                  \
 606         }                                                               \
 607         case 4:                                                         \
 608         {                                                               \
 609                 asm volatile("\n"                                       \
 610                         "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 611                         "2:\n"                                          \
 612                         "\t.section .fixup, \"ax\"\n"                   \
 613                         "3:\tmov     %3, %0\n"                          \
 614                         "\tjmp     2b\n"                                \
 615                         "\t.previous\n"                                 \
 616                         _ASM_EXTABLE(1b, 3b)                            \
 617                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 618                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 619                         : "memory"                                      \
 620                 );                                                      \
 621                 break;                                                  \
 622         }                                                               \
 623         case 8:                                                         \
 624         {                                                               \
 625                 if (!IS_ENABLED(CONFIG_X86_64))                         \
 626                         __cmpxchg_wrong_size();                         \
 627                                                                         \
 628                 asm volatile("\n"                                       \
 629                         "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 630                         "2:\n"                                          \
 631                         "\t.section .fixup, \"ax\"\n"                   \
 632                         "3:\tmov     %3, %0\n"                          \
 633                         "\tjmp     2b\n"                                \
 634                         "\t.previous\n"                                 \
 635                         _ASM_EXTABLE(1b, 3b)                            \
 636                         : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 637                         : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 638                         : "memory"                                      \
 639                 );                                                      \
 640                 break;                                                  \
 641         }                                                               \
 642         default:                                                        \
 643                 __cmpxchg_wrong_size();                                 \
 644         }                                                               \
 645         __uaccess_end();                                                \
 646         *__uval = __old;                                                \
 647         __ret;                                                          \
 648 })
 649
 650 #define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 651 ({                                                                      \
 652         access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 653                 __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 654                                 (old), (new), sizeof(*(ptr))) :         \
 655                 -EFAULT;                                                \
 656 })
 657
 658 /*
 659  * movsl can be slow when source and dest are not both 8-byte aligned
 660  */
 661 #ifdef CONFIG_X86_INTEL_USERCOPY
 662 extern struct movsl_mask {
 663         int mask;
 664 } ____cacheline_aligned_in_smp movsl_mask;
 665 #endif
 666
 667 #define ARCH_HAS_NOCACHE_UACCESS 1
 668
 669 #ifdef CONFIG_X86_32
 670 # include <asm/uaccess_32.h>
 671 #else
 672 # include <asm/uaccess_64.h>
 673 #endif
 674
 675 unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 676                                            unsigned n);
 677 unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 678                                          unsigned n);
 679
 680 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 681 # define copy_user_diag __compiletime_error
 682 #else
 683 # define copy_user_diag __compiletime_warning
 684 #endif
 685
 686 extern void copy_user_diag("copy_from_user() buffer size is too small")
 687 copy_from_user_overflow(void);
 688 extern void copy_user_diag("copy_to_user() buffer size is too small")
 689 copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 690
 691 #undef copy_user_diag
 692
 693 #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 694
 695 extern void
 696 __compiletime_warning("copy_from_user() buffer size is not provably correct")
 697 __copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
 698 #define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
 699
 700 extern void
 701 __compiletime_warning("copy_to_user() buffer size is not provably correct")
 702 __copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 703 #define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
 704
 705 #else
 706
 707 static inline void
 708 __copy_from_user_overflow(int size, unsigned long count)
 709 {
 710         WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 711 }
 712
 713 #define __copy_to_user_overflow __copy_from_user_overflow
 714
 715 #endif
 716
 717 static inline unsigned long __must_check
 718 copy_from_user(void *to, const void __user *from, unsigned long n)
 719 {
 720         int sz = __compiletime_object_size(to);
 721
 722         might_fault();
 723
 724         /*
 725          * While we would like to have the compiler do the checking for us
 726          * even in the non-constant size case, any false positives there are
 727          * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
 728          * without - the [hopefully] dangerous looking nature of the warning
 729          * would make people go look at the respecitive call sites over and
 730          * over again just to find that there's no problem).
 731          *
 732          * And there are cases where it's just not realistic for the compiler
 733          * to prove the count to be in range. For example when multiple call
 734          * sites of a helper function - perhaps in different source files -
 735          * all doing proper range checking, yet the helper function not doing
 736          * so again.
 737          *
 738          * Therefore limit the compile time checking to the constant size
 739          * case, and do only runtime checking for non-constant sizes.
 740          */
 741
 742         if (likely(sz < 0 || sz >= n))
 743                 n = _copy_from_user(to, from, n);
 744         else if(__builtin_constant_p(n))
 745                 copy_from_user_overflow();
 746         else
 747                 __copy_from_user_overflow(sz, n);
 748
 749         return n;
 750 }
 751
 752 static inline unsigned long __must_check
 753 copy_to_user(void __user *to, const void *from, unsigned long n)
 754 {
 755         int sz = __compiletime_object_size(from);
 756
 757         might_fault();
 758
 759         /* See the comment in copy_from_user() above. */
 760         if (likely(sz < 0 || sz >= n))
 761                 n = _copy_to_user(to, from, n);
 762         else if(__builtin_constant_p(n))
 763                 copy_to_user_overflow();
 764         else
 765                 __copy_to_user_overflow(sz, n);
 766
 767         return n;
 768 }
 769
 770 #undef __copy_from_user_overflow
 771 #undef __copy_to_user_overflow
 772
 773 /*
 774  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
 775  * nested NMI paths are careful to preserve CR2.
 776  *
 777  * Caller must use pagefault_enable/disable, or run in interrupt context,
 778  * and also do a uaccess_ok() check
 779  */
 780 #define __copy_from_user_nmi __copy_from_user_inatomic
 781
 782 /*
 783  * The "unsafe" user accesses aren't really "unsafe", but the naming
 784  * is a big fat warning: you have to not only do the access_ok()
 785  * checking before using them, but you have to surround them with the
 786  * user_access_begin/end() pair.
 787  */
 788 #define user_access_begin()     __uaccess_begin()
 789 #define user_access_end()       __uaccess_end()
 790
 791 #define unsafe_put_user(x, ptr)                                         \
 792 ({                                                                              \
 793         int __pu_err;                                                           \
 794         __put_user_size((x), (ptr), sizeof(*(ptr)), __pu_err, -EFAULT);         \
 795         __builtin_expect(__pu_err, 0);                                          \
 796 })
 797
 798 #define unsafe_get_user(x, ptr)                                         \
 799 ({                                                                              \
 800         int __gu_err;                                                           \
 801         unsigned long __gu_val;                                                 \
 802         __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err, -EFAULT);    \
 803         (x) = (__force __typeof__(*(ptr)))__gu_val;                             \
 804         __builtin_expect(__gu_err, 0);                                          \
 805 })
 806
 807 #endif /* _ASM_X86_UACCESS_H */
 808