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 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
 105struct 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
 119extern int fixup_exception(struct pt_regs *regs, int trapnr);
 120extern bool ex_has_fault_handler(unsigned long ip);
 121extern 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
 138extern int __get_user_1(void);
 139extern int __get_user_2(void);
 140extern int __get_user_4(void);
 141extern int __get_user_8(void);
 142extern 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
 240extern 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 */
 246extern void __put_user_1(void);
 247extern void __put_user_2(void);
 248extern void __put_user_4(void);
 249extern 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)                   \
 296do {                                                                    \
 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)                                \
 323do {                                                                    \
 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)                   \
 354do {                                                                    \
 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)                                \
 393do {                                                                    \
 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 */
 440struct __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
 553extern unsigned long
 554copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 555extern __must_check long
 556strncpy_from_user(char *dst, const char __user *src, long count);
 557
 558extern __must_check long strlen_user(const char __user *str);
 559extern __must_check long strnlen_user(const char __user *str, long n);
 560
 561unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 562unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 563
 564extern 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
 662extern 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
 675unsigned long __must_check _copy_from_user(void *to, const void __user *from,
 676                                           unsigned n);
 677unsigned 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
 686extern void copy_user_diag("copy_from_user() buffer size is too small")
 687copy_from_user_overflow(void);
 688extern void copy_user_diag("copy_to_user() buffer size is too small")
 689copy_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
 695extern 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
 700extern 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
 707static 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
 717static inline unsigned long __must_check
 718copy_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
 752static inline unsigned long __must_check
 753copy_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
 809
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