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