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  * Careful: we have to cast the result to the type of the pointer
 153  * for sign reasons.
 154  */
 155 #define get_user(x, ptr)                                                \
 156 ({                                                                      \
 157         int __ret_gu;                                                   \
 158         register __inttype(*(ptr)) __val_gu asm("%edx");                \
 159         __chk_user_ptr(ptr);                                            \
 160         might_fault();                                                  \
 161         asm volatile("call __get_user_%P3"                              \
 162                      : "=a" (__ret_gu), "=r" (__val_gu)                 \
 163                      : "0" (ptr), "i" (sizeof(*(ptr))));                \
 164         (x) = (__typeof__(*(ptr))) __val_gu;                            \
 165         __ret_gu;                                                       \
 166 })
 167
 168 #define __put_user_x(size, x, ptr, __ret_pu)                    \
 169         asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
 170                      : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 171
 172
 173
 174 #ifdef CONFIG_X86_32
 175 #define __put_user_asm_u64(x, addr, err, errret)                        \
 176         asm volatile(ASM_STAC "\n"                                      \
 177                      "1:        movl %%eax,0(%2)\n"                     \
 178                      "2:        movl %%edx,4(%2)\n"                     \
 179                      "3: " ASM_CLAC "\n"                                \
 180                      ".section .fixup,\"ax\"\n"                         \
 181                      "4:        movl %3,%0\n"                           \
 182                      "  jmp 3b\n"                                       \
 183                      ".previous\n"                                      \
 184                      _ASM_EXTABLE(1b, 4b)                               \
 185                      _ASM_EXTABLE(2b, 4b)                               \
 186                      : "=r" (err)                                       \
 187                      : "A" (x), "r" (addr), "i" (errret), "0" (err))
 188
 189 #define __put_user_asm_ex_u64(x, addr)                                  \
 190         asm volatile(ASM_STAC "\n"                                      \
 191                      "1:        movl %%eax,0(%1)\n"                     \
 192                      "2:        movl %%edx,4(%1)\n"                     \
 193                      "3: " ASM_CLAC "\n"                                \
 194                      _ASM_EXTABLE_EX(1b, 2b)                            \
 195                      _ASM_EXTABLE_EX(2b, 3b)                            \
 196                      : : "A" (x), "r" (addr))
 197
 198 #define __put_user_x8(x, ptr, __ret_pu)                         \
 199         asm volatile("call __put_user_8" : "=a" (__ret_pu)      \
 200                      : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
 201 #else
 202 #define __put_user_asm_u64(x, ptr, retval, errret) \
 203         __put_user_asm(x, ptr, retval, "q", "", "er", errret)
 204 #define __put_user_asm_ex_u64(x, addr)  \
 205         __put_user_asm_ex(x, addr, "q", "", "er")
 206 #define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
 207 #endif
 208
 209 extern void __put_user_bad(void);
 210
 211 /*
 212  * Strange magic calling convention: pointer in %ecx,
 213  * value in %eax(:%edx), return value in %eax. clobbers %rbx
 214  */
 215 extern void __put_user_1(void);
 216 extern void __put_user_2(void);
 217 extern void __put_user_4(void);
 218 extern void __put_user_8(void);
 219
 220 /**
 221  * put_user: - Write a simple value into user space.
 222  * @x:   Value to copy to user space.
 223  * @ptr: Destination address, in user space.
 224  *
 225  * Context: User context only.  This function may sleep.
 226  *
 227  * This macro copies a single simple value from kernel space to user
 228  * space.  It supports simple types like char and int, but not larger
 229  * data types like structures or arrays.
 230  *
 231  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 232  * to the result of dereferencing @ptr.
 233  *
 234  * Returns zero on success, or -EFAULT on error.
 235  */
 236 #define put_user(x, ptr)                                        \
 237 ({                                                              \
 238         int __ret_pu;                                           \
 239         __typeof__(*(ptr)) __pu_val;                            \
 240         __chk_user_ptr(ptr);                                    \
 241         might_fault();                                          \
 242         __pu_val = x;                                           \
 243         switch (sizeof(*(ptr))) {                               \
 244         case 1:                                                 \
 245                 __put_user_x(1, __pu_val, ptr, __ret_pu);       \
 246                 break;                                          \
 247         case 2:                                                 \
 248                 __put_user_x(2, __pu_val, ptr, __ret_pu);       \
 249                 break;                                          \
 250         case 4:                                                 \
 251                 __put_user_x(4, __pu_val, ptr, __ret_pu);       \
 252                 break;                                          \
 253         case 8:                                                 \
 254                 __put_user_x8(__pu_val, ptr, __ret_pu);         \
 255                 break;                                          \
 256         default:                                                \
 257                 __put_user_x(X, __pu_val, ptr, __ret_pu);       \
 258                 break;                                          \
 259         }                                                       \
 260         __ret_pu;                                               \
 261 })
 262
 263 #define __put_user_size(x, ptr, size, retval, errret)                   \
 264 do {                                                                    \
 265         retval = 0;                                                     \
 266         __chk_user_ptr(ptr);                                            \
 267         switch (size) {                                                 \
 268         case 1:                                                         \
 269                 __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
 270                 break;                                                  \
 271         case 2:                                                         \
 272                 __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
 273                 break;                                                  \
 274         case 4:                                                         \
 275                 __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
 276                 break;                                                  \
 277         case 8:                                                         \
 278                 __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval,  \
 279                                    errret);                             \
 280                 break;                                                  \
 281         default:                                                        \
 282                 __put_user_bad();                                       \
 283         }                                                               \
 284 } while (0)
 285
 286 #define __put_user_size_ex(x, ptr, size)                                \
 287 do {                                                                    \
 288         __chk_user_ptr(ptr);                                            \
 289         switch (size) {                                                 \
 290         case 1:                                                         \
 291                 __put_user_asm_ex(x, ptr, "b", "b", "iq");              \
 292                 break;                                                  \
 293         case 2:                                                         \
 294                 __put_user_asm_ex(x, ptr, "w", "w", "ir");              \
 295                 break;                                                  \
 296         case 4:                                                         \
 297                 __put_user_asm_ex(x, ptr, "l", "k", "ir");              \
 298                 break;                                                  \
 299         case 8:                                                         \
 300                 __put_user_asm_ex_u64((__typeof__(*ptr))(x), ptr);      \
 301                 break;                                                  \
 302         default:                                                        \
 303                 __put_user_bad();                                       \
 304         }                                                               \
 305 } while (0)
 306
 307 #ifdef CONFIG_X86_32
 308 #define __get_user_asm_u64(x, ptr, retval, errret)      (x) = __get_user_bad()
 309 #define __get_user_asm_ex_u64(x, ptr)                   (x) = __get_user_bad()
 310 #else
 311 #define __get_user_asm_u64(x, ptr, retval, errret) \
 312          __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
 313 #define __get_user_asm_ex_u64(x, ptr) \
 314          __get_user_asm_ex(x, ptr, "q", "", "=r")
 315 #endif
 316
 317 #define __get_user_size(x, ptr, size, retval, errret)                   \
 318 do {                                                                    \
 319         retval = 0;                                                     \
 320         __chk_user_ptr(ptr);                                            \
 321         switch (size) {                                                 \
 322         case 1:                                                         \
 323                 __get_user_asm(x, ptr, retval, "b", "b", "=q", errret); \
 324                 break;                                                  \
 325         case 2:                                                         \
 326                 __get_user_asm(x, ptr, retval, "w", "w", "=r", errret); \
 327                 break;                                                  \
 328         case 4:                                                         \
 329                 __get_user_asm(x, ptr, retval, "l", "k", "=r", errret); \
 330                 break;                                                  \
 331         case 8:                                                         \
 332                 __get_user_asm_u64(x, ptr, retval, errret);             \
 333                 break;                                                  \
 334         default:                                                        \
 335                 (x) = __get_user_bad();                                 \
 336         }                                                               \
 337 } while (0)
 338
 339 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 340         asm volatile(ASM_STAC "\n"                                      \
 341                      "1:        mov"itype" %2,%"rtype"1\n"              \
 342                      "2: " ASM_CLAC "\n"                                \
 343                      ".section .fixup,\"ax\"\n"                         \
 344                      "3:        mov %3,%0\n"                            \
 345                      "  xor"itype" %"rtype"1,%"rtype"1\n"               \
 346                      "  jmp 2b\n"                                       \
 347                      ".previous\n"                                      \
 348                      _ASM_EXTABLE(1b, 3b)                               \
 349                      : "=r" (err), ltype(x)                             \
 350                      : "m" (__m(addr)), "i" (errret), "0" (err))
 351
 352 #define __get_user_size_ex(x, ptr, size)                                \
 353 do {                                                                    \
 354         __chk_user_ptr(ptr);                                            \
 355         switch (size) {                                                 \
 356         case 1:                                                         \
 357                 __get_user_asm_ex(x, ptr, "b", "b", "=q");              \
 358                 break;                                                  \
 359         case 2:                                                         \
 360                 __get_user_asm_ex(x, ptr, "w", "w", "=r");              \
 361                 break;                                                  \
 362         case 4:                                                         \
 363                 __get_user_asm_ex(x, ptr, "l", "k", "=r");              \
 364                 break;                                                  \
 365         case 8:                                                         \
 366                 __get_user_asm_ex_u64(x, ptr);                          \
 367                 break;                                                  \
 368         default:                                                        \
 369                 (x) = __get_user_bad();                                 \
 370         }                                                               \
 371 } while (0)
 372
 373 #define __get_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 374         asm volatile("1:        mov"itype" %1,%"rtype"0\n"              \
 375                      "2:\n"                                             \
 376                      _ASM_EXTABLE_EX(1b, 2b)                            \
 377                      : ltype(x) : "m" (__m(addr)))
 378
 379 #define __put_user_nocheck(x, ptr, size)                        \
 380 ({                                                              \
 381         int __pu_err;                                           \
 382         __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
 383         __pu_err;                                               \
 384 })
 385
 386 #define __get_user_nocheck(x, ptr, size)                                \
 387 ({                                                                      \
 388         int __gu_err;                                                   \
 389         unsigned long __gu_val;                                         \
 390         __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);    \
 391         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 392         __gu_err;                                                       \
 393 })
 394
 395 /* FIXME: this hack is definitely wrong -AK */
 396 struct __large_struct { unsigned long buf[100]; };
 397 #define __m(x) (*(struct __large_struct __user *)(x))
 398
 399 /*
 400  * Tell gcc we read from memory instead of writing: this is because
 401  * we do not write to any memory gcc knows about, so there are no
 402  * aliasing issues.
 403  */
 404 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 405         asm volatile(ASM_STAC "\n"                                      \
 406                      "1:        mov"itype" %"rtype"1,%2\n"              \
 407                      "2: " ASM_CLAC "\n"                                \
 408                      ".section .fixup,\"ax\"\n"                         \
 409                      "3:        mov %3,%0\n"                            \
 410                      "  jmp 2b\n"                                       \
 411                      ".previous\n"                                      \
 412                      _ASM_EXTABLE(1b, 3b)                               \
 413                      : "=r"(err)                                        \
 414                      : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
 415
 416 #define __put_user_asm_ex(x, addr, itype, rtype, ltype)                 \
 417         asm volatile("1:        mov"itype" %"rtype"0,%1\n"              \
 418                      "2:\n"                                             \
 419                      _ASM_EXTABLE_EX(1b, 2b)                            \
 420                      : : ltype(x), "m" (__m(addr)))
 421
 422 /*
 423  * uaccess_try and catch
 424  */
 425 #define uaccess_try     do {                                            \
 426         current_thread_info()->uaccess_err = 0;                         \
 427         stac();                                                         \
 428         barrier();
 429
 430 #define uaccess_catch(err)                                              \
 431         clac();                                                         \
 432         (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0);    \
 433 } while (0)
 434
 435 /**
 436  * __get_user: - Get a simple variable from user space, with less checking.
 437  * @x:   Variable to store result.
 438  * @ptr: Source address, in user space.
 439  *
 440  * Context: User context only.  This function may sleep.
 441  *
 442  * This macro copies a single simple variable from user space to kernel
 443  * space.  It supports simple types like char and int, but not larger
 444  * data types like structures or arrays.
 445  *
 446  * @ptr must have pointer-to-simple-variable type, and the result of
 447  * dereferencing @ptr must be assignable to @x without a cast.
 448  *
 449  * Caller must check the pointer with access_ok() before calling this
 450  * function.
 451  *
 452  * Returns zero on success, or -EFAULT on error.
 453  * On error, the variable @x is set to zero.
 454  */
 455
 456 #define __get_user(x, ptr)                                              \
 457         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 458
 459 /**
 460  * __put_user: - Write a simple value into user space, with less checking.
 461  * @x:   Value to copy to user space.
 462  * @ptr: Destination address, in user space.
 463  *
 464  * Context: User context only.  This function may sleep.
 465  *
 466  * This macro copies a single simple value from kernel space to user
 467  * space.  It supports simple types like char and int, but not larger
 468  * data types like structures or arrays.
 469  *
 470  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 471  * to the result of dereferencing @ptr.
 472  *
 473  * Caller must check the pointer with access_ok() before calling this
 474  * function.
 475  *
 476  * Returns zero on success, or -EFAULT on error.
 477  */
 478
 479 #define __put_user(x, ptr)                                              \
 480         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 481
 482 #define __get_user_unaligned __get_user
 483 #define __put_user_unaligned __put_user
 484
 485 /*
 486  * {get|put}_user_try and catch
 487  *
 488  * get_user_try {
 489  *      get_user_ex(...);
 490  * } get_user_catch(err)
 491  */
 492 #define get_user_try            uaccess_try
 493 #define get_user_catch(err)     uaccess_catch(err)
 494
 495 #define get_user_ex(x, ptr)     do {                                    \
 496         unsigned long __gue_val;                                        \
 497         __get_user_size_ex((__gue_val), (ptr), (sizeof(*(ptr))));       \
 498         (x) = (__force __typeof__(*(ptr)))__gue_val;                    \
 499 } while (0)
 500
 501 #define put_user_try            uaccess_try
 502 #define put_user_catch(err)     uaccess_catch(err)
 503
 504 #define put_user_ex(x, ptr)                                             \
 505         __put_user_size_ex((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 506
 507 extern unsigned long
 508 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 509 extern __must_check long
 510 strncpy_from_user(char *dst, const char __user *src, long count);
 511
 512 extern __must_check long strlen_user(const char __user *str);
 513 extern __must_check long strnlen_user(const char __user *str, long n);
 514
 515 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 516 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 517
 518 /*
 519  * movsl can be slow when source and dest are not both 8-byte aligned
 520  */
 521 #ifdef CONFIG_X86_INTEL_USERCOPY
 522 extern struct movsl_mask {
 523         int mask;
 524 } ____cacheline_aligned_in_smp movsl_mask;
 525 #endif
 526
 527 #define ARCH_HAS_NOCACHE_UACCESS 1
 528
 529 #ifdef CONFIG_X86_32
 530 # include <asm/uaccess_32.h>
 531 #else
 532 # include <asm/uaccess_64.h>
 533 #endif
 534
 535 #endif /* _ASM_X86_UACCESS_H */
 536