LXR linux/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 * This is equivalent to the following test:
  45 * (u33)addr + (u33)size > (u33)current->addr_limit.seg (u65 for x86_64)
  46 *
  47 * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
  48 */
  49
  50#define __range_not_ok(addr, size, limit)                               \
  51({                                                                      \
  52        unsigned long flag, roksum;                                     \
  53        __chk_user_ptr(addr);                                           \
  54        asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"             \
  55            : "=&r" (flag), "=r" (roksum)                               \
  56            : "1" (addr), "g" ((long)(size)),                           \
  57              "rm" (limit));                                            \
  58        flag;                                                           \
  59})
  60
  61/**
  62 * access_ok: - Checks if a user space pointer is valid
  63 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  64 *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  65 *        to write to a block, it is always safe to read from it.
  66 * @addr: User space pointer to start of block to check
  67 * @size: Size of block to check
  68 *
  69 * Context: User context only.  This function may sleep.
  70 *
  71 * Checks if a pointer to a block of memory in user space is valid.
  72 *
  73 * Returns true (nonzero) if the memory block may be valid, false (zero)
  74 * if it is definitely invalid.
  75 *
  76 * Note that, depending on architecture, this function probably just
  77 * checks that the pointer is in the user space range - after calling
  78 * this function, memory access functions may still return -EFAULT.
  79 */
  80#define access_ok(type, addr, size) \
  81        (likely(__range_not_ok(addr, size, user_addr_max()) == 0))
  82
  83/*
  84 * The exception table consists of pairs of addresses relative to the
  85 * exception table enty itself: the first is the address of an
  86 * instruction that is allowed to fault, and the second is the address
  87 * at which the program should continue.  No registers are modified,
  88 * so it is entirely up to the continuation code to figure out what to
  89 * do.
  90 *
  91 * All the routines below use bits of fixup code that are out of line
  92 * with the main instruction path.  This means when everything is well,
  93 * we don't even have to jump over them.  Further, they do not intrude
  94 * on our cache or tlb entries.
  95 */
  96
  97struct exception_table_entry {
  98        int insn, fixup;
  99};
 100/* This is not the generic standard exception_table_entry format */
 101#define ARCH_HAS_SORT_EXTABLE
 102#define ARCH_HAS_SEARCH_EXTABLE
 103
 104extern int fixup_exception(struct pt_regs *regs);
 105extern int early_fixup_exception(unsigned long *ip);
 106
 107/*
 108 * These are the main single-value transfer routines.  They automatically
 109 * use the right size if we just have the right pointer type.
 110 *
 111 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 112 * and yet we don't want to do any pointers, because that is too much
 113 * of a performance impact. Thus we have a few rather ugly macros here,
 114 * and hide all the ugliness from the user.
 115 *
 116 * The "__xxx" versions of the user access functions are versions that
 117 * do not verify the address space, that must have been done previously
 118 * with a separate "access_ok()" call (this is used when we do multiple
 119 * accesses to the same area of user memory).
 120 */
 121
 122extern int __get_user_1(void);
 123extern int __get_user_2(void);
 124extern int __get_user_4(void);
 125extern int __get_user_8(void);
 126extern int __get_user_bad(void);
 127
 128/*
 129 * This is a type: either unsigned long, if the argument fits into
 130 * that type, or otherwise unsigned long long.
 131 */
 132#define __inttype(x) \
 133__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 134
 135/**
 136 * get_user: - Get a simple variable from user space.
 137 * @x:   Variable to store result.
 138 * @ptr: Source address, in user space.
 139 *
 140 * Context: User context only.  This function may sleep.
 141 *
 142 * This macro copies a single simple variable from user space to kernel
 143 * space.  It supports simple types like char and int, but not larger
 144 * data types like structures or arrays.
 145 *
 146 * @ptr must have pointer-to-simple-variable type, and the result of
 147 * dereferencing @ptr must be assignable to @x without a cast.
 148 *
 149 * Returns zero on success, or -EFAULT on error.
 150 * On error, the variable @x is set to zero.
 151 */
 152/*
 153 * Careful: we have to cast the result to the type of the pointer
 154 * for sign reasons.
 155 *
 156 * The use of %edx as the register specifier is a bit of a
 157 * simplification, as gcc only cares about it as the starting point
 158 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
 159 * (%ecx being the next register in gcc's x86 register sequence), and
 160 * %rdx on 64 bits.
 161 */
 162#define get_user(x, ptr)                                                \
 163({                                                                      \
 164        int __ret_gu;                                                   \
 165        register __inttype(*(ptr)) __val_gu asm("%edx");                \
 166        __chk_user_ptr(ptr);                                            \
 167        might_fault();                                                  \
 168        asm volatile("call __get_user_%P3"                              \
 169                     : "=a" (__ret_gu), "=r" (__val_gu)                 \
 170                     : "0" (ptr), "i" (sizeof(*(ptr))));                \
 171        (x) = (__typeof__(*(ptr))) __val_gu;                            \
 172        __ret_gu;                                                       \
 173})
 174
 175#define __put_user_x(size, x, ptr, __ret_pu)                    \
 176        asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 177                     : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 178
 179
 180
 181#ifdef CONFIG_X86_32
 182#define __put_user_asm_u64(x, addr, err, errret)                        \
 183        asm volatile(ASM_STAC "\n"                                      \
 184                     "1:        movl %%eax,0(%2)\n"                     \
 185                     "2:        movl %%edx,4(%2)\n"                     \
 186                     "3: " ASM_CLAC "\n"                                \
 187                     ".section .fixup,\"ax\"\n"                         \
 188                     "4:        movl %3,%0\n"                           \
 189                     "  jmp 3b\n"                                       \
 190                     ".previous\n"                                      \
 191                     _ASM_EXTABLE(1b, 4b)                               \
 192                     _ASM_EXTABLE(2b, 4b)                               \
 193                     : "=r" (err)                                       \
 194                     : "A" (x), "r" (addr), "i" (errret), "0" (err))
 195
 196#define __put_user_asm_ex_u64(x, addr)                                  \
 197        asm volatile(ASM_STAC "\n"                                      \
 198                     "1:        movl %%eax,0(%1)\n"                     \
 199                     "2:        movl %%edx,4(%1)\n"                     \
 200                     "3: " ASM_CLAC "\n"                                \
 201                     _ASM_EXTABLE_EX(1b, 2b)                            \
 202                     _ASM_EXTABLE_EX(2b, 3b)                            \
 203                     : : "A" (x), "r" (addr))
 204
 205#define __put_user_x8(x, ptr, __ret_pu)                         \
 206        asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 207                     : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 208#else
 209#define __put_user_asm_u64(x, ptr, retval, errret) \
 210        __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 211#define __put_user_asm_ex_u64(x, addr)  \
 212        __put_user_asm_ex(x, addr, "q", "", "er")
 213#define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 214#endif
 215
 216extern void __put_user_bad(void);
 217
 218/*
 219 * Strange magic calling convention: pointer in %ecx,
 220 * value in %eax(:%edx), return value in %eax. clobbers %rbx
 221 */
 222extern void __put_user_1(void);
 223extern void __put_user_2(void);
 224extern void __put_user_4(void);
 225extern void __put_user_8(void);
 226
 227/**
 228 * put_user: - Write a simple value into user space.
 229 * @x:   Value to copy to user space.
 230 * @ptr: Destination address, in user space.
 231 *
 232 * Context: User context only.  This function may sleep.
 233 *
 234 * This macro copies a single simple value from kernel space to user
 235 * space.  It supports simple types like char and int, but not larger
 236 * data types like structures or arrays.
 237 *
 238 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 239 * to the result of dereferencing @ptr.
 240 *
 241 * Returns zero on success, or -EFAULT on error.
 242 */
 243#define put_user(x, ptr)                                        \
 244({                                                              \
 245        int __ret_pu;                                           \
 246        __typeof__(*(ptr)) __pu_val;                            \
 247        __chk_user_ptr(ptr);                                    \
 248        might_fault();                                          \
 249        __pu_val = x;                                           \
 250        switch (sizeof(*(ptr))) {                               \
 251        case 1:                                                 \
 252                __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 253                break;                                          \
 254        case 2:                                                 \
 255                __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 256                break;                                          \
 257        case 4:                                                 \
 258                __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 259                break;                                          \
 260        case 8:                                                 \
 261                __put_user_x8(__pu_val, ptr, __ret_pu);         \
 262                break;                                          \
 263        default:                                                \
 264                __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 265                break;                                          \
 266        }                                                       \
 267        __ret_pu;                                               \
 268})
 269
 270#define __put_user_size(x, ptr, size, retval, errret)                   \
 271do {                                                                    \
 272        retval = 0;                                                     \
 273        __chk_user_ptr(ptr);                                            \
 274        switch (size) {                                                 \
 275        case 1:                                                         \
 276                __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 277                break;                                                  \
 278        case 2:                                                         \
 279                __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 280                break;                                                  \
 281        case 4:                                                         \
 282                __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 283                break;                                                  \
 284        case 8:                                                         \
 285                __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 286                                   errret);                             \
 287                break;                                                  \
 288        default:                                                        \
 289                __put_user_bad();                                       \
 290        }                                                               \
 291} while (0)
 292
 293#define __put_user_size_ex(x, ptr, size)                                \
 294do {                                                                    \
 295        __chk_user_ptr(ptr);                                            \
 296        switch (size) {                                                 \
 297        case 1:                                                         \
 298                __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 299                break;                                                  \
 300        case 2:                                                         \
 301                __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 302                break;                                                  \
 303        case 4:                                                         \
 304                __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 305                break;                                                  \
 306        case 8:                                                         \
 307                __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 308                break;                                                  \
 309        default:                                                        \
 310                __put_user_bad();                                       \
 311        }                                                               \
 312} while (0)
 313
 314#ifdef CONFIG_X86_32
 315#define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 316#define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 317#else
 318#define __get_user_asm_u64(x, ptr, retval, errret) \
 319         __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 320#define __get_user_asm_ex_u64(x, ptr) \
 321         __get_user_asm_ex(x, ptr, "q", "", "=r")
 322#endif
 323
 324#define __get_user_size(x, ptr, size, retval, errret)                   \
 325do {                                                                    \
 326        retval = 0;                                                     \
 327        __chk_user_ptr(ptr);                                            \
 328        switch (size) {                                                 \
 329        case 1:                                                         \
 330                __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 331                break;                                                  \
 332        case 2:                                                         \
 333                __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 334                break;                                                  \
 335        case 4:                                                         \
 336                __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 337                break;                                                  \
 338        case 8:                                                         \
 339                __get_user_asm_u64(x, ptr, retval, errret);             \
 340                break;                                                  \
 341        default:                                                        \
 342                (x) = __get_user_bad();                                 \
 343        }                                                               \
 344} while (0)
 345
 346#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 347        asm volatile(ASM_STAC "\n"                                      \
 348                     "1:        mov"itype" %2,%"rtype"1\n"              \
 349                     "2: " ASM_CLAC "\n"                                \
 350                     ".section .fixup,\"ax\"\n"                         \
 351                     "3:        mov %3,%0\n"                            \
 352                     "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 353                     "  jmp 2b\n"                                       \
 354                     ".previous\n"                                      \
 355                     _ASM_EXTABLE(1b, 3b)                               \
 356                     : "=r" (err), ltype(x)                             \
 357                     : "m" (__m(addr)), "i" (errret), "0" (err))
 358
 359#define __get_user_size_ex(x, ptr, size)                                \
 360do {                                                                    \
 361        __chk_user_ptr(ptr);                                            \
 362        switch (size) {                                                 \
 363        case 1:                                                         \
 364                __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 365                break;                                                  \
 366        case 2:                                                         \
 367                __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 368                break;                                                  \
 369        case 4:                                                         \
 370                __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 371                break;                                                  \
 372        case 8:                                                         \
 373                __get_user_asm_ex_u64(x, ptr);                          \
 374                break;                                                  \
 375        default:                                                        \
 376                (x) = __get_user_bad();                                 \
 377        }                                                               \
 378} while (0)
 379
 380#define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 381        asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 382                     "2:\n"                                             \
 383                     _ASM_EXTABLE_EX(1b, 2b)                            \
 384                     : ltype(x) : "m" (__m(addr)))
 385
 386#define __put_user_nocheck(x, ptr, size)                        \
 387({                                                              \
 388        int __pu_err;                                           \
 389        __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 390        __pu_err;                                               \
 391})
 392
 393#define __get_user_nocheck(x, ptr, size)                                \
 394({                                                                      \
 395        int __gu_err;                                                   \
 396        unsigned long __gu_val;                                         \
 397        __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 398        (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 399        __gu_err;                                                       \
 400})
 401
 402/* FIXME: this hack is definitely wrong -AK */
 403struct __large_struct { unsigned long buf[100]; };
 404#define __m(x) (*(struct __large_struct __user *)(x))
 405
 406/*
 407 * Tell gcc we read from memory instead of writing: this is because
 408 * we do not write to any memory gcc knows about, so there are no
 409 * aliasing issues.
 410 */
 411#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 412        asm volatile(ASM_STAC "\n"                                      \
 413                     "1:        mov"itype" %"rtype"1,%2\n"              \
 414                     "2: " ASM_CLAC "\n"                                \
 415                     ".section .fixup,\"ax\"\n"                         \
 416                     "3:        mov %3,%0\n"                            \
 417                     "  jmp 2b\n"                                       \
 418                     ".previous\n"                                      \
 419                     _ASM_EXTABLE(1b, 3b)                               \
 420                     : "=r"(err)                                        \
 421                     : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 422
 423#define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 424        asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 425                     "2:\n"                                             \
 426                     _ASM_EXTABLE_EX(1b, 2b)                            \
 427                     : : ltype(x), "m" (__m(addr)))
 428
 429/*
 430 * uaccess_try and catch
 431 */
 432#define uaccess_try     do {                                            \
 433        current_thread_info()->uaccess_err = 0;                         \
 434        stac();                                                         \
 435        barrier();
 436
 437#define uaccess_catch(err)                                              \
 438        clac();                                                         \
 439        (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 440} while (0)
 441
 442/**
 443 * __get_user: - Get a simple variable from user space, with less checking.
 444 * @x:   Variable to store result.
 445 * @ptr: Source address, in user space.
 446 *
 447 * Context: User context only.  This function may sleep.
 448 *
 449 * This macro copies a single simple variable from user space to kernel
 450 * space.  It supports simple types like char and int, but not larger
 451 * data types like structures or arrays.
 452 *
 453 * @ptr must have pointer-to-simple-variable type, and the result of
 454 * dereferencing @ptr must be assignable to @x without a cast.
 455 *
 456 * Caller must check the pointer with access_ok() before calling this
 457 * function.
 458 *
 459 * Returns zero on success, or -EFAULT on error.
 460 * On error, the variable @x is set to zero.
 461 */
 462
 463#define __get_user(x, ptr)                                              \
 464        __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 465
 466/**
 467 * __put_user: - Write a simple value into user space, with less checking.
 468 * @x:   Value to copy to user space.
 469 * @ptr: Destination address, in user space.
 470 *
 471 * Context: User context only.  This function may sleep.
 472 *
 473 * This macro copies a single simple value from kernel space to user
 474 * space.  It supports simple types like char and int, but not larger
 475 * data types like structures or arrays.
 476 *
 477 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 478 * to the result of dereferencing @ptr.
 479 *
 480 * Caller must check the pointer with access_ok() before calling this
 481 * function.
 482 *
 483 * Returns zero on success, or -EFAULT on error.
 484 */
 485
 486#define __put_user(x, ptr)                                              \
 487        __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 488
 489#define __get_user_unaligned __get_user
 490#define __put_user_unaligned __put_user
 491
 492/*
 493 * {get|put}_user_try and catch
 494 *
 495 * get_user_try {
 496 *      get_user_ex(...);
 497 * } get_user_catch(err)
 498 */
 499#define get_user_try            uaccess_try
 500#define get_user_catch(err)     uaccess_catch(err)
 501
 502#define get_user_ex(x, ptr)     do {                                    \
 503        unsigned long __gue_val;                                        \
 504        __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 505        (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 506} while (0)
 507
 508#define put_user_try            uaccess_try
 509#define put_user_catch(err)     uaccess_catch(err)
 510
 511#define put_user_ex(x, ptr)                                             \
 512        __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 513
 514extern unsigned long
 515copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 516extern __must_check long
 517strncpy_from_user(char *dst, const char __user *src, long count);
 518
 519extern __must_check long strlen_user(const char __user *str);
 520extern __must_check long strnlen_user(const char __user *str, long n);
 521
 522unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 523unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 524
 525/*
 526 * movsl can be slow when source and dest are not both 8-byte aligned
 527 */
 528#ifdef CONFIG_X86_INTEL_USERCOPY
 529extern struct movsl_mask {
 530        int mask;
 531} ____cacheline_aligned_in_smp movsl_mask;
 532#endif
 533
 534#define ARCH_HAS_NOCACHE_UACCESS 1
 535
 536#ifdef CONFIG_X86_32
 537# include <asm/uaccess_32.h>
 538#else
 539# include <asm/uaccess_64.h>
 540#endif
 541
 542#endif /* _ASM_X86_UACCESS_H */
 543
 544