include/asm-x86/uaccess_32.h

   1 #ifndef __i386_UACCESS_H
   2 #define __i386_UACCESS_H
   3
   4 /*
   5  * User space memory access functions
   6  */
   7 #include <linux/errno.h>
   8 #include <linux/thread_info.h>
   9 #include <linux/prefetch.h>
  10 #include <linux/string.h>
  11 #include <asm/page.h>
  12
  13 #define VERIFY_READ 0
  14 #define VERIFY_WRITE 1
  15
  16 /*
  17  * The fs value determines whether argument validity checking should be
  18  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  19  * get_fs() == KERNEL_DS, checking is bypassed.
  20  *
  21  * For historical reasons, these macros are grossly misnamed.
  22  */
  23
  24 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  25
  26
  27 #define KERNEL_DS       MAKE_MM_SEG(0xFFFFFFFFUL)
  28 #define USER_DS         MAKE_MM_SEG(PAGE_OFFSET)
  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 /*
  37  * movsl can be slow when source and dest are not both 8-byte aligned
  38  */
  39 #ifdef CONFIG_X86_INTEL_USERCOPY
  40 extern struct movsl_mask {
  41         int mask;
  42 } ____cacheline_aligned_in_smp movsl_mask;
  43 #endif
  44
  45 #define __addr_ok(addr) ((unsigned long __force)(addr) < (current_thread_info()->addr_limit.seg))
  46
  47 /*
  48  * Test whether a block of memory is a valid user space address.
  49  * Returns 0 if the range is valid, nonzero otherwise.
  50  *
  51  * This is equivalent to the following test:
  52  * (u33)addr + (u33)size >= (u33)current->addr_limit.seg
  53  *
  54  * This needs 33-bit arithmetic. We have a carry...
  55  */
  56 #define __range_ok(addr,size) ({ \
  57         unsigned long flag,roksum; \
  58         __chk_user_ptr(addr); \
  59         asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
  60                 :"=&r" (flag), "=r" (roksum) \
  61                 :"1" (addr),"g" ((int)(size)),"rm" (current_thread_info()->addr_limit.seg)); \
  62         flag; })
  63
  64 /**
  65  * access_ok: - Checks if a user space pointer is valid
  66  * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
  67  *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
  68  *        to write to a block, it is always safe to read from it.
  69  * @addr: User space pointer to start of block to check
  70  * @size: Size of block to check
  71  *
  72  * Context: User context only.  This function may sleep.
  73  *
  74  * Checks if a pointer to a block of memory in user space is valid.
  75  *
  76  * Returns true (nonzero) if the memory block may be valid, false (zero)
  77  * if it is definitely invalid.
  78  *
  79  * Note that, depending on architecture, this function probably just
  80  * checks that the pointer is in the user space range - after calling
  81  * this function, memory access functions may still return -EFAULT.
  82  */
  83 #define access_ok(type,addr,size) (likely(__range_ok(addr,size) == 0))
  84
  85 /*
  86  * The exception table consists of pairs of addresses: the first is the
  87  * address of an instruction that is allowed to fault, and the second is
  88  * the address at which the program should continue.  No registers are
  89  * modified, so it is entirely up to the continuation code to figure out
  90  * what to do.
  91  *
  92  * All the routines below use bits of fixup code that are out of line
  93  * with the main instruction path.  This means when everything is well,
  94  * we don't even have to jump over them.  Further, they do not intrude
  95  * on our cache or tlb entries.
  96  */
  97
  98 struct exception_table_entry
  99 {
 100         unsigned long insn, fixup;
 101 };
 102
 103 extern int fixup_exception(struct pt_regs *regs);
 104
 105 /*
 106  * These are the main single-value transfer routines.  They automatically
 107  * use the right size if we just have the right pointer type.
 108  *
 109  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 110  * and yet we don't want to do any pointers, because that is too much
 111  * of a performance impact. Thus we have a few rather ugly macros here,
 112  * and hide all the ugliness from the user.
 113  *
 114  * The "__xxx" versions of the user access functions are versions that
 115  * do not verify the address space, that must have been done previously
 116  * with a separate "access_ok()" call (this is used when we do multiple
 117  * accesses to the same area of user memory).
 118  */
 119
 120 extern void __get_user_1(void);
 121 extern void __get_user_2(void);
 122 extern void __get_user_4(void);
 123
 124 #define __get_user_x(size,ret,x,ptr) \
 125         __asm__ __volatile__("call __get_user_" #size \
 126                 :"=a" (ret),"=d" (x) \
 127                 :"0" (ptr))
 128
 129
 130 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 131 /**
 132  * get_user: - Get a simple variable from user space.
 133  * @x:   Variable to store result.
 134  * @ptr: Source address, in user space.
 135  *
 136  * Context: User context only.  This function may sleep.
 137  *
 138  * This macro copies a single simple variable from user space to kernel
 139  * space.  It supports simple types like char and int, but not larger
 140  * data types like structures or arrays.
 141  *
 142  * @ptr must have pointer-to-simple-variable type, and the result of
 143  * dereferencing @ptr must be assignable to @x without a cast.
 144  *
 145  * Returns zero on success, or -EFAULT on error.
 146  * On error, the variable @x is set to zero.
 147  */
 148 #define get_user(x,ptr)                                                 \
 149 ({      int __ret_gu;                                                   \
 150         unsigned long __val_gu;                                         \
 151         __chk_user_ptr(ptr);                                            \
 152         switch(sizeof (*(ptr))) {                                       \
 153         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 154         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 155         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 156         default: __get_user_x(X,__ret_gu,__val_gu,ptr); break;          \
 157         }                                                               \
 158         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 159         __ret_gu;                                                       \
 160 })
 161
 162 extern void __put_user_bad(void);
 163
 164 /*
 165  * Strange magic calling convention: pointer in %ecx,
 166  * value in %eax(:%edx), return value in %eax, no clobbers.
 167  */
 168 extern void __put_user_1(void);
 169 extern void __put_user_2(void);
 170 extern void __put_user_4(void);
 171 extern void __put_user_8(void);
 172
 173 #define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 174 #define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 175 #define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 176 #define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
 177 #define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))
 178
 179 /**
 180  * put_user: - Write a simple value into user space.
 181  * @x:   Value to copy to user space.
 182  * @ptr: Destination address, in user space.
 183  *
 184  * Context: User context only.  This function may sleep.
 185  *
 186  * This macro copies a single simple value from kernel space to user
 187  * space.  It supports simple types like char and int, but not larger
 188  * data types like structures or arrays.
 189  *
 190  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 191  * to the result of dereferencing @ptr.
 192  *
 193  * Returns zero on success, or -EFAULT on error.
 194  */
 195 #ifdef CONFIG_X86_WP_WORKS_OK
 196
 197 #define put_user(x,ptr)                                         \
 198 ({      int __ret_pu;                                           \
 199         __typeof__(*(ptr)) __pu_val;                            \
 200         __chk_user_ptr(ptr);                                    \
 201         __pu_val = x;                                           \
 202         switch(sizeof(*(ptr))) {                                \
 203         case 1: __put_user_1(__pu_val, ptr); break;             \
 204         case 2: __put_user_2(__pu_val, ptr); break;             \
 205         case 4: __put_user_4(__pu_val, ptr); break;             \
 206         case 8: __put_user_8(__pu_val, ptr); break;             \
 207         default:__put_user_X(__pu_val, ptr); break;             \
 208         }                                                       \
 209         __ret_pu;                                               \
 210 })
 211
 212 #else
 213 #define put_user(x,ptr)                                         \
 214 ({                                                              \
 215         int __ret_pu;                                           \
 216         __typeof__(*(ptr)) __pus_tmp = x;                       \
 217         __ret_pu=0;                                             \
 218         if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp,          \
 219                                 sizeof(*(ptr))) != 0))          \
 220                 __ret_pu=-EFAULT;                               \
 221         __ret_pu;                                               \
 222  })
 223
 224
 225 #endif
 226
 227 /**
 228  * __get_user: - Get a simple variable from user space, with less checking.
 229  * @x:   Variable to store result.
 230  * @ptr: Source address, in user space.
 231  *
 232  * Context: User context only.  This function may sleep.
 233  *
 234  * This macro copies a single simple variable from user space to kernel
 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 the result of
 239  * dereferencing @ptr must be assignable to @x without a cast.
 240  *
 241  * Caller must check the pointer with access_ok() before calling this
 242  * function.
 243  *
 244  * Returns zero on success, or -EFAULT on error.
 245  * On error, the variable @x is set to zero.
 246  */
 247 #define __get_user(x,ptr) \
 248   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 249
 250
 251 /**
 252  * __put_user: - Write a simple value into user space, with less checking.
 253  * @x:   Value to copy to user space.
 254  * @ptr: Destination address, in user space.
 255  *
 256  * Context: User context only.  This function may sleep.
 257  *
 258  * This macro copies a single simple value from kernel space to user
 259  * space.  It supports simple types like char and int, but not larger
 260  * data types like structures or arrays.
 261  *
 262  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 263  * to the result of dereferencing @ptr.
 264  *
 265  * Caller must check the pointer with access_ok() before calling this
 266  * function.
 267  *
 268  * Returns zero on success, or -EFAULT on error.
 269  */
 270 #define __put_user(x,ptr) \
 271   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 272
 273 #define __put_user_nocheck(x,ptr,size)                          \
 274 ({                                                              \
 275         long __pu_err;                                          \
 276         __put_user_size((x),(ptr),(size),__pu_err,-EFAULT);     \
 277         __pu_err;                                               \
 278 })
 279
 280
 281 #define __put_user_u64(x, addr, err)                            \
 282         __asm__ __volatile__(                                   \
 283                 "1:     movl %%eax,0(%2)\n"                     \
 284                 "2:     movl %%edx,4(%2)\n"                     \
 285                 "3:\n"                                          \
 286                 ".section .fixup,\"ax\"\n"                      \
 287                 "4:     movl %3,%0\n"                           \
 288                 "       jmp 3b\n"                               \
 289                 ".previous\n"                                   \
 290                 ".section __ex_table,\"a\"\n"                   \
 291                 "       .align 4\n"                             \
 292                 "       .long 1b,4b\n"                          \
 293                 "       .long 2b,4b\n"                          \
 294                 ".previous"                                     \
 295                 : "=r"(err)                                     \
 296                 : "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))
 297
 298 #ifdef CONFIG_X86_WP_WORKS_OK
 299
 300 #define __put_user_size(x,ptr,size,retval,errret)                       \
 301 do {                                                                    \
 302         retval = 0;                                                     \
 303         __chk_user_ptr(ptr);                                            \
 304         switch (size) {                                                 \
 305         case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
 306         case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
 307         case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
 308         case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
 309           default: __put_user_bad();                                    \
 310         }                                                               \
 311 } while (0)
 312
 313 #else
 314
 315 #define __put_user_size(x,ptr,size,retval,errret)                       \
 316 do {                                                                    \
 317         __typeof__(*(ptr)) __pus_tmp = x;                               \
 318         retval = 0;                                                     \
 319                                                                         \
 320         if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))     \
 321                 retval = errret;                                        \
 322 } while (0)
 323
 324 #endif
 325 struct __large_struct { unsigned long buf[100]; };
 326 #define __m(x) (*(struct __large_struct __user *)(x))
 327
 328 /*
 329  * Tell gcc we read from memory instead of writing: this is because
 330  * we do not write to any memory gcc knows about, so there are no
 331  * aliasing issues.
 332  */
 333 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 334         __asm__ __volatile__(                                           \
 335                 "1:     mov"itype" %"rtype"1,%2\n"                      \
 336                 "2:\n"                                                  \
 337                 ".section .fixup,\"ax\"\n"                              \
 338                 "3:     movl %3,%0\n"                                   \
 339                 "       jmp 2b\n"                                       \
 340                 ".previous\n"                                           \
 341                 ".section __ex_table,\"a\"\n"                           \
 342                 "       .align 4\n"                                     \
 343                 "       .long 1b,3b\n"                                  \
 344                 ".previous"                                             \
 345                 : "=r"(err)                                             \
 346                 : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))
 347
 348
 349 #define __get_user_nocheck(x,ptr,size)                          \
 350 ({                                                              \
 351         long __gu_err;                                          \
 352         unsigned long __gu_val;                                 \
 353         __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
 354         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 355         __gu_err;                                               \
 356 })
 357
 358 extern long __get_user_bad(void);
 359
 360 #define __get_user_size(x,ptr,size,retval,errret)                       \
 361 do {                                                                    \
 362         retval = 0;                                                     \
 363         __chk_user_ptr(ptr);                                            \
 364         switch (size) {                                                 \
 365         case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
 366         case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
 367         case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break;  \
 368         default: (x) = __get_user_bad();                                \
 369         }                                                               \
 370 } while (0)
 371
 372 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 373         __asm__ __volatile__(                                           \
 374                 "1:     mov"itype" %2,%"rtype"1\n"                      \
 375                 "2:\n"                                                  \
 376                 ".section .fixup,\"ax\"\n"                              \
 377                 "3:     movl %3,%0\n"                                   \
 378                 "       xor"itype" %"rtype"1,%"rtype"1\n"               \
 379                 "       jmp 2b\n"                                       \
 380                 ".previous\n"                                           \
 381                 ".section __ex_table,\"a\"\n"                           \
 382                 "       .align 4\n"                                     \
 383                 "       .long 1b,3b\n"                                  \
 384                 ".previous"                                             \
 385                 : "=r"(err), ltype (x)                                  \
 386                 : "m"(__m(addr)), "i"(errret), "0"(err))
 387
 388
 389 unsigned long __must_check __copy_to_user_ll(void __user *to,
 390                                 const void *from, unsigned long n);
 391 unsigned long __must_check __copy_from_user_ll(void *to,
 392                                 const void __user *from, unsigned long n);
 393 unsigned long __must_check __copy_from_user_ll_nozero(void *to,
 394                                 const void __user *from, unsigned long n);
 395 unsigned long __must_check __copy_from_user_ll_nocache(void *to,
 396                                 const void __user *from, unsigned long n);
 397 unsigned long __must_check __copy_from_user_ll_nocache_nozero(void *to,
 398                                 const void __user *from, unsigned long n);
 399
 400 /**
 401  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
 402  * @to:   Destination address, in user space.
 403  * @from: Source address, in kernel space.
 404  * @n:    Number of bytes to copy.
 405  *
 406  * Context: User context only.
 407  *
 408  * Copy data from kernel space to user space.  Caller must check
 409  * the specified block with access_ok() before calling this function.
 410  * The caller should also make sure he pins the user space address
 411  * so that the we don't result in page fault and sleep.
 412  *
 413  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 414  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 415  * If a store crosses a page boundary and gets a fault, the x86 will not write
 416  * anything, so this is accurate.
 417  */
 418
 419 static __always_inline unsigned long __must_check
 420 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 421 {
 422         if (__builtin_constant_p(n)) {
 423                 unsigned long ret;
 424
 425                 switch (n) {
 426                 case 1:
 427                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
 428                         return ret;
 429                 case 2:
 430                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
 431                         return ret;
 432                 case 4:
 433                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
 434                         return ret;
 435                 }
 436         }
 437         return __copy_to_user_ll(to, from, n);
 438 }
 439
 440 /**
 441  * __copy_to_user: - Copy a block of data into user space, with less checking.
 442  * @to:   Destination address, in user space.
 443  * @from: Source address, in kernel space.
 444  * @n:    Number of bytes to copy.
 445  *
 446  * Context: User context only.  This function may sleep.
 447  *
 448  * Copy data from kernel space to user space.  Caller must check
 449  * the specified block with access_ok() before calling this function.
 450  *
 451  * Returns number of bytes that could not be copied.
 452  * On success, this will be zero.
 453  */
 454 static __always_inline unsigned long __must_check
 455 __copy_to_user(void __user *to, const void *from, unsigned long n)
 456 {
 457        might_sleep();
 458        return __copy_to_user_inatomic(to, from, n);
 459 }
 460
 461 static __always_inline unsigned long
 462 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 463 {
 464         /* Avoid zeroing the tail if the copy fails..
 465          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
 466          * but as the zeroing behaviour is only significant when n is not
 467          * constant, that shouldn't be a problem.
 468          */
 469         if (__builtin_constant_p(n)) {
 470                 unsigned long ret;
 471
 472                 switch (n) {
 473                 case 1:
 474                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 475                         return ret;
 476                 case 2:
 477                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 478                         return ret;
 479                 case 4:
 480                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 481                         return ret;
 482                 }
 483         }
 484         return __copy_from_user_ll_nozero(to, from, n);
 485 }
 486
 487 /**
 488  * __copy_from_user: - Copy a block of data from user space, with less checking.
 489  * @to:   Destination address, in kernel space.
 490  * @from: Source address, in user space.
 491  * @n:    Number of bytes to copy.
 492  *
 493  * Context: User context only.  This function may sleep.
 494  *
 495  * Copy data from user space to kernel space.  Caller must check
 496  * the specified block with access_ok() before calling this function.
 497  *
 498  * Returns number of bytes that could not be copied.
 499  * On success, this will be zero.
 500  *
 501  * If some data could not be copied, this function will pad the copied
 502  * data to the requested size using zero bytes.
 503  *
 504  * An alternate version - __copy_from_user_inatomic() - may be called from
 505  * atomic context and will fail rather than sleep.  In this case the
 506  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 507  * for explanation of why this is needed.
 508  */
 509 static __always_inline unsigned long
 510 __copy_from_user(void *to, const void __user *from, unsigned long n)
 511 {
 512         might_sleep();
 513         if (__builtin_constant_p(n)) {
 514                 unsigned long ret;
 515
 516                 switch (n) {
 517                 case 1:
 518                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 519                         return ret;
 520                 case 2:
 521                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 522                         return ret;
 523                 case 4:
 524                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 525                         return ret;
 526                 }
 527         }
 528         return __copy_from_user_ll(to, from, n);
 529 }
 530
 531 #define ARCH_HAS_NOCACHE_UACCESS
 532
 533 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 534                                 const void __user *from, unsigned long n)
 535 {
 536         might_sleep();
 537         if (__builtin_constant_p(n)) {
 538                 unsigned long ret;
 539
 540                 switch (n) {
 541                 case 1:
 542                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 543                         return ret;
 544                 case 2:
 545                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 546                         return ret;
 547                 case 4:
 548                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 549                         return ret;
 550                 }
 551         }
 552         return __copy_from_user_ll_nocache(to, from, n);
 553 }
 554
 555 static __always_inline unsigned long
 556 __copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n)
 557 {
 558        return __copy_from_user_ll_nocache_nozero(to, from, n);
 559 }
 560
 561 unsigned long __must_check copy_to_user(void __user *to,
 562                                 const void *from, unsigned long n);
 563 unsigned long __must_check copy_from_user(void *to,
 564                                 const void __user *from, unsigned long n);
 565 long __must_check strncpy_from_user(char *dst, const char __user *src,
 566                                 long count);
 567 long __must_check __strncpy_from_user(char *dst,
 568                                 const char __user *src, long count);
 569
 570 /**
 571  * strlen_user: - Get the size of a string in user space.
 572  * @str: The string to measure.
 573  *
 574  * Context: User context only.  This function may sleep.
 575  *
 576  * Get the size of a NUL-terminated string in user space.
 577  *
 578  * Returns the size of the string INCLUDING the terminating NUL.
 579  * On exception, returns 0.
 580  *
 581  * If there is a limit on the length of a valid string, you may wish to
 582  * consider using strnlen_user() instead.
 583  */
 584 #define strlen_user(str) strnlen_user(str, LONG_MAX)
 585
 586 long strnlen_user(const char __user *str, long n);
 587 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 588 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 589
 590 #endif /* __i386_UACCESS_H */