include/asm-i386/uaccess.h

   1 #ifndef __i386_UACCESS_H
   2 #define __i386_UACCESS_H
   3
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/config.h>
   8 #include <linux/errno.h>
   9 #include <linux/thread_info.h>
  10 #include <linux/prefetch.h>
  11 #include <linux/string.h>
  12 #include <asm/page.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
  28 #define KERNEL_DS       MAKE_MM_SEG(0xFFFFFFFFUL)
  29 #define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)
  30
  31 #define get_ds()        (KERNEL_DS)
  32 #define get_fs()        (current_thread_info()->addr_limit)
  33 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  34
  35 #define segment_eq(a,b) ((a).seg == (b).seg)
  36
  37 /*
  38  * movsl can be slow when source and dest are not both 8-byte aligned
  39  */
  40 #ifdef CONFIG_X86_INTEL_USERCOPY
  41 extern struct movsl_mask {
  42         int mask;
  43 } ____cacheline_aligned_in_smp movsl_mask;
  44 #endif
  45
  46 #define __addr_ok(addr) ((unsigned long __force)(addr) < (current_thread_info()->addr_limit.seg))
  47
  48 /*
  49  * Test whether a block of memory is a valid user space address.
  50  * Returns 0 if the range is valid, nonzero otherwise.
  51  *
  52  * This is equivalent to the following test:
  53  * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
  54  *
  55  * This needs 33-bit arithmetic. We have a carry...
  56  */
  57 #define __range_ok(addr,size) ({ \
  58         unsigned long flag,sum; \
  59         __chk_user_ptr(addr); \
  60         asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
  61                 :"=&r" (flag), "=r" (sum) \
  62                 :"1" (addr),"g" ((int)(size)),"g" (current_thread_info()->addr_limit.seg)); \
  63         flag; })
  64
  65 /**
  66  * access_ok: - Checks if a user space pointer is valid
  67  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  68  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  69  *        to write to a block, it is always safe to read from it.
  70  * @addr: User space pointer to start of block to check
  71  * @size: Size of block to check
  72  *
  73  * Context: User context only.  This function may sleep.
  74  *
  75  * Checks if a pointer to a block of memory in user space is valid.
  76  *
  77  * Returns true (nonzero) if the memory block may be valid, false (zero)
  78  * if it is definitely invalid.
  79  *
  80  * Note that, depending on architecture, this function probably just
  81  * checks that the pointer is in the user space range - after calling
  82  * this function, memory access functions may still return -EFAULT.
  83  */
  84 #define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))
  85
  86 /**
  87  * verify_area: - Obsolete/deprecated and will go away soon,
  88  * use access_ok() instead.
  89  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE
  90  * @addr: User space pointer to start of block to check
  91  * @size: Size of block to check
  92  *
  93  * Context: User context only.  This function may sleep.
  94  *
  95  * This function has been replaced by access_ok().
  96  *
  97  * Checks if a pointer to a block of memory in user space is valid.
  98  *
  99  * Returns zero if the memory block may be valid, -EFAULT
 100  * if it is definitely invalid.
 101  *
 102  * See access_ok() for more details.
 103  */
 104 static inline int __deprecated verify_area(int type, const void __user * addr, unsigned long size)
 105 {
 106         return access_ok(type,addr,size) ? 0 : -EFAULT;
 107 }
 108
 109
 110 /*
 111  * The exception table consists of pairs of addresses: the first is the
 112  * address of an instruction that is allowed to fault, and the second is
 113  * the address at which the program should continue.  No registers are
 114  * modified, so it is entirely up to the continuation code to figure out
 115  * what to do.
 116  *
 117  * All the routines below use bits of fixup code that are out of line
 118  * with the main instruction path.  This means when everything is well,
 119  * we don't even have to jump over them.  Further, they do not intrude
 120  * on our cache or tlb entries.
 121  */
 122
 123 struct exception_table_entry
 124 {
 125         unsigned long insn, fixup;
 126 };
 127
 128 extern int fixup_exception(struct pt_regs *regs);
 129
 130 /*
 131  * These are the main single-value transfer routines.  They automatically
 132  * use the right size if we just have the right pointer type.
 133  *
 134  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 135  * and yet we don't want to do any pointers, because that is too much
 136  * of a performance impact. Thus we have a few rather ugly macros here,
 137  * and hide all the ugliness from the user.
 138  *
 139  * The "__xxx" versions of the user access functions are versions that
 140  * do not verify the address space, that must have been done previously
 141  * with a separate "access_ok()" call (this is used when we do multiple
 142  * accesses to the same area of user memory).
 143  */
 144
 145 extern void __get_user_1(void);
 146 extern void __get_user_2(void);
 147 extern void __get_user_4(void);
 148
 149 #define __get_user_x(size,ret,x,ptr) \
 150         __asm__ __volatile__("call __get_user_" #size \
 151                 :"=a" (ret),"=d" (x) \
 152                 :"0" (ptr))
 153
 154
 155 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 156 /**
 157  * get_user: - Get a simple variable from user space.
 158  * @x:   Variable to store result.
 159  * @ptr: Source address, in user space.
 160  *
 161  * Context: User context only.  This function may sleep.
 162  *
 163  * This macro copies a single simple variable from user space to kernel
 164  * space.  It supports simple types like char and int, but not larger
 165  * data types like structures or arrays.
 166  *
 167  * @ptr must have pointer-to-simple-variable type, and the result of
 168  * dereferencing @ptr must be assignable to @x without a cast.
 169  *
 170  * Returns zero on success, or -EFAULT on error.
 171  * On error, the variable @x is set to zero.
 172  */
 173 #define get_user(x,ptr)                                                 \
 174 ({      int __ret_gu;                                                   \
 175         unsigned long __val_gu;                                         \
 176         __chk_user_ptr(ptr);                                            \
 177         switch(sizeof (*(ptr))) {                                       \
 178         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 179         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 180         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 181         default: __get_user_x(X,__ret_gu,__val_gu,ptr); break;          \
 182         }                                                               \
 183         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 184         __ret_gu;                                                       \
 185 })
 186
 187 extern void __put_user_bad(void);
 188
 189 /*
 190  * Strange magic calling convention: pointer in %ecx,
 191  * value in %eax(:%edx), return value in %eax, no clobbers.
 192  */
 193 extern void __put_user_1(void);
 194 extern void __put_user_2(void);
 195 extern void __put_user_4(void);
 196 extern void __put_user_8(void);
 197
 198 #define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 199 #define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 200 #define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 201 #define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
 202 #define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))
 203
 204 /**
 205  * put_user: - Write a simple value into user space.
 206  * @x:   Value to copy to user space.
 207  * @ptr: Destination address, in user space.
 208  *
 209  * Context: User context only.  This function may sleep.
 210  *
 211  * This macro copies a single simple value from kernel space to user
 212  * space.  It supports simple types like char and int, but not larger
 213  * data types like structures or arrays.
 214  *
 215  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 216  * to the result of dereferencing @ptr.
 217  *
 218  * Returns zero on success, or -EFAULT on error.
 219  */
 220 #ifdef CONFIG_X86_WP_WORKS_OK
 221
 222 #define put_user(x,ptr)                                         \
 223 ({      int __ret_pu;                                           \
 224         __chk_user_ptr(ptr);                                    \
 225         switch(sizeof(*(ptr))) {                                \
 226         case 1: __put_user_1(x, ptr); break;                    \
 227         case 2: __put_user_2(x, ptr); break;                    \
 228         case 4: __put_user_4(x, ptr); break;                    \
 229         case 8: __put_user_8(x, ptr); break;                    \
 230         default:__put_user_X(x, ptr); break;                    \
 231         }                                                       \
 232         __ret_pu;                                               \
 233 })
 234
 235 #else
 236 #define put_user(x,ptr)                                         \
 237 ({                                                              \
 238         int __ret_pu;                                           \
 239         __typeof__(*(ptr)) __pus_tmp = x;                       \
 240         __ret_pu=0;                                             \
 241         if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp,          \
 242                                 sizeof(*(ptr))) != 0))          \
 243                 __ret_pu=-EFAULT;                               \
 244         __ret_pu;                                               \
 245  })
 246
 247
 248 #endif
 249
 250 /**
 251  * __get_user: - Get a simple variable from user space, with less checking.
 252  * @x:   Variable to store result.
 253  * @ptr: Source address, in user space.
 254  *
 255  * Context: User context only.  This function may sleep.
 256  *
 257  * This macro copies a single simple variable from user space to kernel
 258  * space.  It supports simple types like char and int, but not larger
 259  * data types like structures or arrays.
 260  *
 261  * @ptr must have pointer-to-simple-variable type, and the result of
 262  * dereferencing @ptr must be assignable to @x without a cast.
 263  *
 264  * Caller must check the pointer with access_ok() before calling this
 265  * function.
 266  *
 267  * Returns zero on success, or -EFAULT on error.
 268  * On error, the variable @x is set to zero.
 269  */
 270 #define __get_user(x,ptr) \
 271   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 272
 273
 274 /**
 275  * __put_user: - Write a simple value into user space, with less checking.
 276  * @x:   Value to copy to user space.
 277  * @ptr: Destination address, in user space.
 278  *
 279  * Context: User context only.  This function may sleep.
 280  *
 281  * This macro copies a single simple value from kernel space to user
 282  * space.  It supports simple types like char and int, but not larger
 283  * data types like structures or arrays.
 284  *
 285  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 286  * to the result of dereferencing @ptr.
 287  *
 288  * Caller must check the pointer with access_ok() before calling this
 289  * function.
 290  *
 291  * Returns zero on success, or -EFAULT on error.
 292  */
 293 #define __put_user(x,ptr) \
 294   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 295
 296 #define __put_user_nocheck(x,ptr,size)                          \
 297 ({                                                              \
 298         long __pu_err;                                          \
 299         __put_user_size((x),(ptr),(size),__pu_err,-EFAULT);     \
 300         __pu_err;                                               \
 301 })
 302
 303
 304 #define __put_user_u64(x, addr, err)                            \
 305         __asm__ __volatile__(                                   \
 306                 "1:     movl %%eax,0(%2)\n"                     \
 307                 "2:     movl %%edx,4(%2)\n"                     \
 308                 "3:\n"                                          \
 309                 ".section .fixup,\"ax\"\n"                      \
 310                 "4:     movl %3,%0\n"                           \
 311                 "       jmp 3b\n"                               \
 312                 ".previous\n"                                   \
 313                 ".section __ex_table,\"a\"\n"                   \
 314                 "       .align 4\n"                             \
 315                 "       .long 1b,4b\n"                          \
 316                 "       .long 2b,4b\n"                          \
 317                 ".previous"                                     \
 318                 : "=r"(err)                                     \
 319                 : "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))
 320
 321 #ifdef CONFIG_X86_WP_WORKS_OK
 322
 323 #define __put_user_size(x,ptr,size,retval,errret)                       \
 324 do {                                                                    \
 325         retval = 0;                                                     \
 326         __chk_user_ptr(ptr);                                            \
 327         switch (size) {                                                 \
 328         case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
 329         case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
 330         case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
 331         case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
 332           default: __put_user_bad();                                    \
 333         }                                                               \
 334 } while (0)
 335
 336 #else
 337
 338 #define __put_user_size(x,ptr,size,retval,errret)                       \
 339 do {                                                                    \
 340         __typeof__(*(ptr)) __pus_tmp = x;                               \
 341         retval = 0;                                                     \
 342                                                                         \
 343         if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))     \
 344                 retval = errret;                                        \
 345 } while (0)
 346
 347 #endif
 348 struct __large_struct { unsigned long buf[100]; };
 349 #define __m(x) (*(struct __large_struct __user *)(x))
 350
 351 /*
 352  * Tell gcc we read from memory instead of writing: this is because
 353  * we do not write to any memory gcc knows about, so there are no
 354  * aliasing issues.
 355  */
 356 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 357         __asm__ __volatile__(                                           \
 358                 "1:     mov"itype" %"rtype"1,%2\n"                      \
 359                 "2:\n"                                                  \
 360                 ".section .fixup,\"ax\"\n"                              \
 361                 "3:     movl %3,%0\n"                                   \
 362                 "       jmp 2b\n"                                       \
 363                 ".previous\n"                                           \
 364                 ".section __ex_table,\"a\"\n"                           \
 365                 "       .align 4\n"                                     \
 366                 "       .long 1b,3b\n"                                  \
 367                 ".previous"                                             \
 368                 : "=r"(err)                                             \
 369                 : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))
 370
 371
 372 #define __get_user_nocheck(x,ptr,size)                          \
 373 ({                                                              \
 374         long __gu_err;                                          \
 375         unsigned long __gu_val;                                 \
 376         __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
 377         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 378         __gu_err;                                               \
 379 })
 380
 381 extern long __get_user_bad(void);
 382
 383 #define __get_user_size(x,ptr,size,retval,errret)                       \
 384 do {                                                                    \
 385         retval = 0;                                                     \
 386         __chk_user_ptr(ptr);                                            \
 387         switch (size) {                                                 \
 388         case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
 389         case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
 390         case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break;  \
 391         default: (x) = __get_user_bad();                                \
 392         }                                                               \
 393 } while (0)
 394
 395 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 396         __asm__ __volatile__(                                           \
 397                 "1:     mov"itype" %2,%"rtype"1\n"                      \
 398                 "2:\n"                                                  \
 399                 ".section .fixup,\"ax\"\n"                              \
 400                 "3:     movl %3,%0\n"                                   \
 401                 "       xor"itype" %"rtype"1,%"rtype"1\n"               \
 402                 "       jmp 2b\n"                                       \
 403                 ".previous\n"                                           \
 404                 ".section __ex_table,\"a\"\n"                           \
 405                 "       .align 4\n"                                     \
 406                 "       .long 1b,3b\n"                                  \
 407                 ".previous"                                             \
 408                 : "=r"(err), ltype (x)                                  \
 409                 : "m"(__m(addr)), "i"(errret), "0"(err))
 410
 411
 412 unsigned long __must_check __copy_to_user_ll(void __user *to,
 413                                 const void *from, unsigned long n);
 414 unsigned long __must_check __copy_from_user_ll(void *to,
 415                                 const void __user *from, unsigned long n);
 416
 417 /*
 418  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 419  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 420  * If a store crosses a page boundary and gets a fault, the x86 will not write
 421  * anything, so this is accurate.
 422  */
 423
 424 /**
 425  * __copy_to_user: - Copy a block of data into user space, with less checking.
 426  * @to:   Destination address, in user space.
 427  * @from: Source address, in kernel space.
 428  * @n:    Number of bytes to copy.
 429  *
 430  * Context: User context only.  This function may sleep.
 431  *
 432  * Copy data from kernel space to user space.  Caller must check
 433  * the specified block with access_ok() before calling this function.
 434  *
 435  * Returns number of bytes that could not be copied.
 436  * On success, this will be zero.
 437  */
 438 static inline unsigned long __must_check
 439 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 440 {
 441         if (__builtin_constant_p(n)) {
 442                 unsigned long ret;
 443
 444                 switch (n) {
 445                 case 1:
 446                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
 447                         return ret;
 448                 case 2:
 449                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
 450                         return ret;
 451                 case 4:
 452                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
 453                         return ret;
 454                 }
 455         }
 456         return __copy_to_user_ll(to, from, n);
 457 }
 458
 459 static inline unsigned long __must_check
 460 __copy_to_user(void __user *to, const void *from, unsigned long n)
 461 {
 462        might_sleep();
 463        return __copy_to_user_inatomic(to, from, n);
 464 }
 465
 466 /**
 467  * __copy_from_user: - Copy a block of data from user space, with less checking.
 468  * @to:   Destination address, in kernel space.
 469  * @from: Source address, in user space.
 470  * @n:    Number of bytes to copy.
 471  *
 472  * Context: User context only.  This function may sleep.
 473  *
 474  * Copy data from user space to kernel space.  Caller must check
 475  * the specified block with access_ok() before calling this function.
 476  *
 477  * Returns number of bytes that could not be copied.
 478  * On success, this will be zero.
 479  *
 480  * If some data could not be copied, this function will pad the copied
 481  * data to the requested size using zero bytes.
 482  */
 483 static inline unsigned long
 484 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 485 {
 486         if (__builtin_constant_p(n)) {
 487                 unsigned long ret;
 488
 489                 switch (n) {
 490                 case 1:
 491                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 492                         return ret;
 493                 case 2:
 494                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 495                         return ret;
 496                 case 4:
 497                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 498                         return ret;
 499                 }
 500         }
 501         return __copy_from_user_ll(to, from, n);
 502 }
 503
 504 static inline unsigned long
 505 __copy_from_user(void *to, const void __user *from, unsigned long n)
 506 {
 507        might_sleep();
 508        return __copy_from_user_inatomic(to, from, n);
 509 }
 510 unsigned long __must_check copy_to_user(void __user *to,
 511                                 const void *from, unsigned long n);
 512 unsigned long __must_check copy_from_user(void *to,
 513                                 const void __user *from, unsigned long n);
 514 long __must_check strncpy_from_user(char *dst, const char __user *src,
 515                                 long count);
 516 long __must_check __strncpy_from_user(char *dst,
 517                                 const char __user *src, long count);
 518
 519 /**
 520  * strlen_user: - Get the size of a string in user space.
 521  * @str: The string to measure.
 522  *
 523  * Context: User context only.  This function may sleep.
 524  *
 525  * Get the size of a NUL-terminated string in user space.
 526  *
 527  * Returns the size of the string INCLUDING the terminating NUL.
 528  * On exception, returns 0.
 529  *
 530  * If there is a limit on the length of a valid string, you may wish to
 531  * consider using strnlen_user() instead.
 532  */
 533 #define strlen_user(str) strnlen_user(str, ~0UL >> 1)
 534
 535 long strnlen_user(const char __user *str, long n);
 536 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 537 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 538
 539 #endif /* __i386_UACCESS_H */