linux/arch/x86/include/asm/uaccess.h
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   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 */
  44static 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 addr > limit - size;
  55
  56        /* Arbitrary sizes? Be careful about overflow */
  57        addr += size;
  58        if (addr < size)
  59                return true;
  60        return 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.
  78 *
  79 * Checks if a pointer to a block of memory in user space is valid.
  80 *
  81 * Returns true (nonzero) if the memory block may be valid, false (zero)
  82 * if it is definitely invalid.
  83 *
  84 * Note that, depending on architecture, this function probably just
  85 * checks that the pointer is in the user space range - after calling
  86 * this function, memory access functions may still return -EFAULT.
  87 */
  88#define access_ok(type, addr, size) \
  89        likely(!__range_not_ok(addr, size, user_addr_max()))
  90
  91/*
  92 * The exception table consists of pairs of addresses relative to the
  93 * exception table enty itself: the first is the address of an
  94 * instruction that is allowed to fault, and the second is the address
  95 * at which the program should continue.  No registers are modified,
  96 * so it is entirely up to the continuation code to figure out what to
  97 * do.
  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
 105struct exception_table_entry {
 106        int insn, fixup;
 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
 112extern int fixup_exception(struct pt_regs *regs);
 113extern 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
 130extern int __get_user_1(void);
 131extern int __get_user_2(void);
 132extern int __get_user_4(void);
 133extern int __get_user_8(void);
 134extern int __get_user_bad(void);
 135
 136/*
 137 * This is a type: either unsigned long, if the argument fits into
 138 * that type, or otherwise unsigned long long.
 139 */
 140#define __inttype(x) \
 141__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 142
 143/**
 144 * get_user: - Get a simple variable from user space.
 145 * @x:   Variable to store result.
 146 * @ptr: Source address, in user space.
 147 *
 148 * Context: User context only.  This function may sleep.
 149 *
 150 * This macro copies a single simple variable from user space to kernel
 151 * space.  It supports simple types like char and int, but not larger
 152 * data types like structures or arrays.
 153 *
 154 * @ptr must have pointer-to-simple-variable type, and the result of
 155 * dereferencing @ptr must be assignable to @x without a cast.
 156 *
 157 * Returns zero on success, or -EFAULT on error.
 158 * On error, the variable @x is set to zero.
 159 */
 160/*
 161 * Careful: we have to cast the result to the type of the pointer
 162 * for sign reasons.
 163 *
 164 * The use of _ASM_DX as the register specifier is a bit of a
 165 * simplification, as gcc only cares about it as the starting point
 166 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 167 * (%ecx being the next register in gcc's x86 register sequence), and
 168 * %rdx on 64 bits.
 169 *
 170 * Clang/LLVM cares about the size of the register, but still wants
 171 * the base register for something that ends up being a pair.
 172 */
 173#define get_user(x, ptr)                                                \
 174({                                                                      \
 175        int __ret_gu;                                                   \
 176        register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);            \
 177        __chk_user_ptr(ptr);                                            \
 178        might_fault();                                                  \
 179        asm volatile("call __get_user_%P3"                              \
 180                     : "=a" (__ret_gu), "=r" (__val_gu)                 \
 181                     : "0" (ptr), "i" (sizeof(*(ptr))));                \
 182        (x) = (__typeof__(*(ptr))) __val_gu;                            \
 183        __ret_gu;                                                       \
 184})
 185
 186#define __put_user_x(size, x, ptr, __ret_pu)                    \
 187        asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 188                     : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 189
 190
 191
 192#ifdef CONFIG_X86_32
 193#define __put_user_asm_u64(x, addr, err, errret)                        \
 194        asm volatile(ASM_STAC "\n"                                      \
 195                     "1:        movl %%eax,0(%2)\n"                     \
 196                     "2:        movl %%edx,4(%2)\n"                     \
 197                     "3: " ASM_CLAC "\n"                                \
 198                     ".section .fixup,\"ax\"\n"                         \
 199                     "4:        movl %3,%0\n"                           \
 200                     "  jmp 3b\n"                                       \
 201                     ".previous\n"                                      \
 202                     _ASM_EXTABLE(1b, 4b)                               \
 203                     _ASM_EXTABLE(2b, 4b)                               \
 204                     : "=r" (err)                                       \
 205                     : "A" (x), "r" (addr), "i" (errret), "0" (err))
 206
 207#define __put_user_asm_ex_u64(x, addr)                                  \
 208        asm volatile(ASM_STAC "\n"                                      \
 209                     "1:        movl %%eax,0(%1)\n"                     \
 210                     "2:        movl %%edx,4(%1)\n"                     \
 211                     "3: " ASM_CLAC "\n"                                \
 212                     _ASM_EXTABLE_EX(1b, 2b)                            \
 213                     _ASM_EXTABLE_EX(2b, 3b)                            \
 214                     : : "A" (x), "r" (addr))
 215
 216#define __put_user_x8(x, ptr, __ret_pu)                         \
 217        asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 218                     : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 219#else
 220#define __put_user_asm_u64(x, ptr, retval, errret) \
 221        __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 222#define __put_user_asm_ex_u64(x, addr)  \
 223        __put_user_asm_ex(x, addr, "q", "", "er")
 224#define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 225#endif
 226
 227extern void __put_user_bad(void);
 228
 229/*
 230 * Strange magic calling convention: pointer in %ecx,
 231 * value in %eax(:%edx), return value in %eax. clobbers %rbx
 232 */
 233extern void __put_user_1(void);
 234extern void __put_user_2(void);
 235extern void __put_user_4(void);
 236extern void __put_user_8(void);
 237
 238/**
 239 * put_user: - Write a simple value into user space.
 240 * @x:   Value to copy to user space.
 241 * @ptr: Destination address, in user space.
 242 *
 243 * Context: User context only.  This function may sleep.
 244 *
 245 * This macro copies a single simple value from kernel space to user
 246 * space.  It supports simple types like char and int, but not larger
 247 * data types like structures or arrays.
 248 *
 249 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 250 * to the result of dereferencing @ptr.
 251 *
 252 * Returns zero on success, or -EFAULT on error.
 253 */
 254#define put_user(x, ptr)                                        \
 255({                                                              \
 256        int __ret_pu;                                           \
 257        __typeof__(*(ptr)) __pu_val;                            \
 258        __chk_user_ptr(ptr);                                    \
 259        might_fault();                                          \
 260        __pu_val = x;                                           \
 261        switch (sizeof(*(ptr))) {                               \
 262        case 1:                                                 \
 263                __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 264                break;                                          \
 265        case 2:                                                 \
 266                __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 267                break;                                          \
 268        case 4:                                                 \
 269                __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 270                break;                                          \
 271        case 8:                                                 \
 272                __put_user_x8(__pu_val, ptr, __ret_pu);         \
 273                break;                                          \
 274        default:                                                \
 275                __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 276                break;                                          \
 277        }                                                       \
 278        __ret_pu;                                               \
 279})
 280
 281#define __put_user_size(x, ptr, size, retval, errret)                   \
 282do {                                                                    \
 283        retval = 0;                                                     \
 284        __chk_user_ptr(ptr);                                            \
 285        switch (size) {                                                 \
 286        case 1:                                                         \
 287                __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 288                break;                                                  \
 289        case 2:                                                         \
 290                __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 291                break;                                                  \
 292        case 4:                                                         \
 293                __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 294                break;                                                  \
 295        case 8:                                                         \
 296                __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 297                                   errret);                             \
 298                break;                                                  \
 299        default:                                                        \
 300                __put_user_bad();                                       \
 301        }                                                               \
 302} while (0)
 303
 304#define __put_user_size_ex(x, ptr, size)                                \
 305do {                                                                    \
 306        __chk_user_ptr(ptr);                                            \
 307        switch (size) {                                                 \
 308        case 1:                                                         \
 309                __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 310                break;                                                  \
 311        case 2:                                                         \
 312                __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 313                break;                                                  \
 314        case 4:                                                         \
 315                __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 316                break;                                                  \
 317        case 8:                                                         \
 318                __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 319                break;                                                  \
 320        default:                                                        \
 321                __put_user_bad();                                       \
 322        }                                                               \
 323} while (0)
 324
 325#ifdef CONFIG_X86_32
 326#define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 327#define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 328#else
 329#define __get_user_asm_u64(x, ptr, retval, errret) \
 330         __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 331#define __get_user_asm_ex_u64(x, ptr) \
 332         __get_user_asm_ex(x, ptr, "q", "", "=r")
 333#endif
 334
 335#define __get_user_size(x, ptr, size, retval, errret)                   \
 336do {                                                                    \
 337        retval = 0;                                                     \
 338        __chk_user_ptr(ptr);                                            \
 339        switch (size) {                                                 \
 340        case 1:                                                         \
 341                __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 342                break;                                                  \
 343        case 2:                                                         \
 344                __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 345                break;                                                  \
 346        case 4:                                                         \
 347                __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 348                break;                                                  \
 349        case 8:                                                         \
 350                __get_user_asm_u64(x, ptr, retval, errret);             \
 351                break;                                                  \
 352        default:                                                        \
 353                (x) = __get_user_bad();                                 \
 354        }                                                               \
 355} while (0)
 356
 357#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 358        asm volatile(ASM_STAC "\n"                                      \
 359                     "1:        mov"itype" %2,%"rtype"1\n"              \
 360                     "2: " ASM_CLAC "\n"                                \
 361                     ".section .fixup,\"ax\"\n"                         \
 362                     "3:        mov %3,%0\n"                            \
 363                     "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 364                     "  jmp 2b\n"                                       \
 365                     ".previous\n"                                      \
 366                     _ASM_EXTABLE(1b, 3b)                               \
 367                     : "=r" (err), ltype(x)                             \
 368                     : "m" (__m(addr)), "i" (errret), "0" (err))
 369
 370#define __get_user_size_ex(x, ptr, size)                                \
 371do {                                                                    \
 372        __chk_user_ptr(ptr);                                            \
 373        switch (size) {                                                 \
 374        case 1:                                                         \
 375                __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 376                break;                                                  \
 377        case 2:                                                         \
 378                __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 379                break;                                                  \
 380        case 4:                                                         \
 381                __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 382                break;                                                  \
 383        case 8:                                                         \
 384                __get_user_asm_ex_u64(x, ptr);                          \
 385                break;                                                  \
 386        default:                                                        \
 387                (x) = __get_user_bad();                                 \
 388        }                                                               \
 389} while (0)
 390
 391#define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 392        asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 393                     "2:\n"                                             \
 394                     _ASM_EXTABLE_EX(1b, 2b)                            \
 395                     : ltype(x) : "m" (__m(addr)))
 396
 397#define __put_user_nocheck(x, ptr, size)                        \
 398({                                                              \
 399        int __pu_err;                                           \
 400        __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 401        __pu_err;                                               \
 402})
 403
 404#define __get_user_nocheck(x, ptr, size)                                \
 405({                                                                      \
 406        int __gu_err;                                                   \
 407        unsigned long __gu_val;                                         \
 408        __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 409        (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 410        __gu_err;                                                       \
 411})
 412
 413/* FIXME: this hack is definitely wrong -AK */
 414struct __large_struct { unsigned long buf[100]; };
 415#define __m(x) (*(struct __large_struct __user *)(x))
 416
 417/*
 418 * Tell gcc we read from memory instead of writing: this is because
 419 * we do not write to any memory gcc knows about, so there are no
 420 * aliasing issues.
 421 */
 422#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 423        asm volatile(ASM_STAC "\n"                                      \
 424                     "1:        mov"itype" %"rtype"1,%2\n"              \
 425                     "2: " ASM_CLAC "\n"                                \
 426                     ".section .fixup,\"ax\"\n"                         \
 427                     "3:        mov %3,%0\n"                            \
 428                     "  jmp 2b\n"                                       \
 429                     ".previous\n"                                      \
 430                     _ASM_EXTABLE(1b, 3b)                               \
 431                     : "=r"(err)                                        \
 432                     : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 433
 434#define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 435        asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 436                     "2:\n"                                             \
 437                     _ASM_EXTABLE_EX(1b, 2b)                            \
 438                     : : ltype(x), "m" (__m(addr)))
 439
 440/*
 441 * uaccess_try and catch
 442 */
 443#define uaccess_try     do {                                            \
 444        current_thread_info()->uaccess_err = 0;                         \
 445        stac();                                                         \
 446        barrier();
 447
 448#define uaccess_catch(err)                                              \
 449        clac();                                                         \
 450        (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 451} while (0)
 452
 453/**
 454 * __get_user: - Get a simple variable from user space, with less checking.
 455 * @x:   Variable to store result.
 456 * @ptr: Source address, in user space.
 457 *
 458 * Context: User context only.  This function may sleep.
 459 *
 460 * This macro copies a single simple variable from user space to kernel
 461 * space.  It supports simple types like char and int, but not larger
 462 * data types like structures or arrays.
 463 *
 464 * @ptr must have pointer-to-simple-variable type, and the result of
 465 * dereferencing @ptr must be assignable to @x without a cast.
 466 *
 467 * Caller must check the pointer with access_ok() before calling this
 468 * function.
 469 *
 470 * Returns zero on success, or -EFAULT on error.
 471 * On error, the variable @x is set to zero.
 472 */
 473
 474#define __get_user(x, ptr)                                              \
 475        __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 476
 477/**
 478 * __put_user: - Write a simple value into user space, with less checking.
 479 * @x:   Value to copy to user space.
 480 * @ptr: Destination address, in user space.
 481 *
 482 * Context: User context only.  This function may sleep.
 483 *
 484 * This macro copies a single simple value from kernel space to user
 485 * space.  It supports simple types like char and int, but not larger
 486 * data types like structures or arrays.
 487 *
 488 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 489 * to the result of dereferencing @ptr.
 490 *
 491 * Caller must check the pointer with access_ok() before calling this
 492 * function.
 493 *
 494 * Returns zero on success, or -EFAULT on error.
 495 */
 496
 497#define __put_user(x, ptr)                                              \
 498        __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 499
 500#define __get_user_unaligned __get_user
 501#define __put_user_unaligned __put_user
 502
 503/*
 504 * {get|put}_user_try and catch
 505 *
 506 * get_user_try {
 507 *      get_user_ex(...);
 508 * } get_user_catch(err)
 509 */
 510#define get_user_try            uaccess_try
 511#define get_user_catch(err)     uaccess_catch(err)
 512
 513#define get_user_ex(x, ptr)     do {                                    \
 514        unsigned long __gue_val;                                        \
 515        __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 516        (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 517} while (0)
 518
 519#define put_user_try            uaccess_try
 520#define put_user_catch(err)     uaccess_catch(err)
 521
 522#define put_user_ex(x, ptr)                                             \
 523        __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 524
 525extern unsigned long
 526copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 527extern __must_check long
 528strncpy_from_user(char *dst, const char __user *src, long count);
 529
 530extern __must_check long strlen_user(const char __user *str);
 531extern __must_check long strnlen_user(const char __user *str, long n);
 532
 533unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 534unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 535
 536extern void __cmpxchg_wrong_size(void)
 537        __compiletime_error("Bad argument size for cmpxchg");
 538
 539#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)       \
 540({                                                                      \
 541        int __ret = 0;                                                  \
 542        __typeof__(ptr) __uval = (uval);                                \
 543        __typeof__(*(ptr)) __old = (old);                               \
 544        __typeof__(*(ptr)) __new = (new);                               \
 545        switch (size) {                                                 \
 546        case 1:                                                         \
 547        {                                                               \
 548                asm volatile("\t" ASM_STAC "\n"                         \
 549                        "1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"          \
 550                        "2:\t" ASM_CLAC "\n"                            \
 551                        "\t.section .fixup, \"ax\"\n"                   \
 552                        "3:\tmov     %3, %0\n"                          \
 553                        "\tjmp     2b\n"                                \
 554                        "\t.previous\n"                                 \
 555                        _ASM_EXTABLE(1b, 3b)                            \
 556                        : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 557                        : "i" (-EFAULT), "q" (__new), "1" (__old)       \
 558                        : "memory"                                      \
 559                );                                                      \
 560                break;                                                  \
 561        }                                                               \
 562        case 2:                                                         \
 563        {                                                               \
 564                asm volatile("\t" ASM_STAC "\n"                         \
 565                        "1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"          \
 566                        "2:\t" ASM_CLAC "\n"                            \
 567                        "\t.section .fixup, \"ax\"\n"                   \
 568                        "3:\tmov     %3, %0\n"                          \
 569                        "\tjmp     2b\n"                                \
 570                        "\t.previous\n"                                 \
 571                        _ASM_EXTABLE(1b, 3b)                            \
 572                        : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 573                        : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 574                        : "memory"                                      \
 575                );                                                      \
 576                break;                                                  \
 577        }                                                               \
 578        case 4:                                                         \
 579        {                                                               \
 580                asm volatile("\t" ASM_STAC "\n"                         \
 581                        "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"          \
 582                        "2:\t" ASM_CLAC "\n"                            \
 583                        "\t.section .fixup, \"ax\"\n"                   \
 584                        "3:\tmov     %3, %0\n"                          \
 585                        "\tjmp     2b\n"                                \
 586                        "\t.previous\n"                                 \
 587                        _ASM_EXTABLE(1b, 3b)                            \
 588                        : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 589                        : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 590                        : "memory"                                      \
 591                );                                                      \
 592                break;                                                  \
 593        }                                                               \
 594        case 8:                                                         \
 595        {                                                               \
 596                if (!IS_ENABLED(CONFIG_X86_64))                         \
 597                        __cmpxchg_wrong_size();                         \
 598                                                                        \
 599                asm volatile("\t" ASM_STAC "\n"                         \
 600                        "1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"          \
 601                        "2:\t" ASM_CLAC "\n"                            \
 602                        "\t.section .fixup, \"ax\"\n"                   \
 603                        "3:\tmov     %3, %0\n"                          \
 604                        "\tjmp     2b\n"                                \
 605                        "\t.previous\n"                                 \
 606                        _ASM_EXTABLE(1b, 3b)                            \
 607                        : "+r" (__ret), "=a" (__old), "+m" (*(ptr))     \
 608                        : "i" (-EFAULT), "r" (__new), "1" (__old)       \
 609                        : "memory"                                      \
 610                );                                                      \
 611                break;                                                  \
 612        }                                                               \
 613        default:                                                        \
 614                __cmpxchg_wrong_size();                                 \
 615        }                                                               \
 616        *__uval = __old;                                                \
 617        __ret;                                                          \
 618})
 619
 620#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)               \
 621({                                                                      \
 622        access_ok(VERIFY_WRITE, (ptr), sizeof(*(ptr))) ?                \
 623                __user_atomic_cmpxchg_inatomic((uval), (ptr),           \
 624                                (old), (new), sizeof(*(ptr))) :         \
 625                -EFAULT;                                                \
 626})
 627
 628/*
 629 * movsl can be slow when source and dest are not both 8-byte aligned
 630 */
 631#ifdef CONFIG_X86_INTEL_USERCOPY
 632extern struct movsl_mask {
 633        int mask;
 634} ____cacheline_aligned_in_smp movsl_mask;
 635#endif
 636
 637#define ARCH_HAS_NOCACHE_UACCESS 1
 638
 639#ifdef CONFIG_X86_32
 640# include <asm/uaccess_32.h>
 641#else
 642# include <asm/uaccess_64.h>
 643#endif
 644
 645unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 646                                           unsigned n);
 647unsigned long __must_check _copy_to_user(void __user *to, const void *from,
 648                                         unsigned n);
 649
 650#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 651# define copy_user_diag __compiletime_error
 652#else
 653# define copy_user_diag __compiletime_warning
 654#endif
 655
 656extern void copy_user_diag("copy_from_user() buffer size is too small")
 657copy_from_user_overflow(void);
 658extern void copy_user_diag("copy_to_user() buffer size is too small")
 659copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 660
 661#undef copy_user_diag
 662
 663#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
 664
 665extern void
 666__compiletime_warning("copy_from_user() buffer size is not provably correct")
 667__copy_from_user_overflow(void) __asm__("copy_from_user_overflow");
 668#define __copy_from_user_overflow(size, count) __copy_from_user_overflow()
 669
 670extern void
 671__compiletime_warning("copy_to_user() buffer size is not provably correct")
 672__copy_to_user_overflow(void) __asm__("copy_from_user_overflow");
 673#define __copy_to_user_overflow(size, count) __copy_to_user_overflow()
 674
 675#else
 676
 677static inline void
 678__copy_from_user_overflow(int size, unsigned long count)
 679{
 680        WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
 681}
 682
 683#define __copy_to_user_overflow __copy_from_user_overflow
 684
 685#endif
 686
 687static inline unsigned long __must_check
 688copy_from_user(void *to, const void __user *from, unsigned long n)
 689{
 690        int sz = __compiletime_object_size(to);
 691
 692        might_fault();
 693
 694        /*
 695         * While we would like to have the compiler do the checking for us
 696         * even in the non-constant size case, any false positives there are
 697         * a problem (especially when DEBUG_STRICT_USER_COPY_CHECKS, but even
 698         * without - the [hopefully] dangerous looking nature of the warning
 699         * would make people go look at the respecitive call sites over and
 700         * over again just to find that there's no problem).
 701         *
 702         * And there are cases where it's just not realistic for the compiler
 703         * to prove the count to be in range. For example when multiple call
 704         * sites of a helper function - perhaps in different source files -
 705         * all doing proper range checking, yet the helper function not doing
 706         * so again.
 707         *
 708         * Therefore limit the compile time checking to the constant size
 709         * case, and do only runtime checking for non-constant sizes.
 710         */
 711
 712        if (likely(sz < 0 || sz >= n))
 713                n = _copy_from_user(to, from, n);
 714        else if(__builtin_constant_p(n))
 715                copy_from_user_overflow();
 716        else
 717                __copy_from_user_overflow(sz, n);
 718
 719        return n;
 720}
 721
 722static inline unsigned long __must_check
 723copy_to_user(void __user *to, const void *from, unsigned long n)
 724{
 725        int sz = __compiletime_object_size(from);
 726
 727        might_fault();
 728
 729        /* See the comment in copy_from_user() above. */
 730        if (likely(sz < 0 || sz >= n))
 731                n = _copy_to_user(to, from, n);
 732        else if(__builtin_constant_p(n))
 733                copy_to_user_overflow();
 734        else
 735                __copy_to_user_overflow(sz, n);
 736
 737        return n;
 738}
 739
 740#undef __copy_from_user_overflow
 741#undef __copy_to_user_overflow
 742
 743#endif /* _ASM_X86_UACCESS_H */
 744
 745
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