Pileus Git - ~andy/linux/blob - 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
  97 struct 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
 104 extern int fixup_exception(struct pt_regs *regs);
 105 extern 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
 122 extern int __get_user_1(void);
 123 extern int __get_user_2(void);
 124 extern int __get_user_4(void);
 125 extern int __get_user_8(void);
 126 extern 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
 216 extern 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  */
 222 extern void __put_user_1(void);
 223 extern void __put_user_2(void);
 224 extern void __put_user_4(void);
 225 extern 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)                   \
 271 do {                                                                    \
 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)                                \
 294 do {                                                                    \
 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)                   \
 325 do {                                                                    \
 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)                                \
 360 do {                                                                    \
 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 */
 403 struct __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
 514 extern unsigned long
 515 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 516 extern __must_check long
 517 strncpy_from_user(char *dst, const char __user *src, long count);
 518
 519 extern __must_check long strlen_user(const char __user *str);
 520 extern __must_check long strnlen_user(const char __user *str, long n);
 521
 522 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 523 unsigned 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
 529 extern 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