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/asm.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,roksum; \
  59         __chk_user_ptr(addr); \
  60         asm("addl %3,%1 ; sbbl %0,%0; cmpl %1,%4; sbbl $0,%0" \
  61                 :"=&r" (flag), "=r" (roksum) \
  62                 :"1" (addr),"g" ((int)(size)),"rm" (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  * The exception table consists of pairs of addresses: the first is the
  88  * address of an instruction that is allowed to fault, and the second is
  89  * the address at which the program should continue.  No registers are
  90  * modified, so it is entirely up to the continuation code to figure out
  91  * what to do.
  92  *
  93  * All the routines below use bits of fixup code that are out of line
  94  * with the main instruction path.  This means when everything is well,
  95  * we don't even have to jump over them.  Further, they do not intrude
  96  * on our cache or tlb entries.
  97  */
  98
  99 struct exception_table_entry
 100 {
 101         unsigned long insn, fixup;
 102 };
 103
 104 extern int fixup_exception(struct pt_regs *regs);
 105
 106 /*
 107  * These are the main single-value transfer routines.  They automatically
 108  * use the right size if we just have the right pointer type.
 109  *
 110  * This gets kind of ugly. We want to return _two_ values in "get_user()"
 111  * and yet we don't want to do any pointers, because that is too much
 112  * of a performance impact. Thus we have a few rather ugly macros here,
 113  * and hide all the ugliness from the user.
 114  *
 115  * The "__xxx" versions of the user access functions are versions that
 116  * do not verify the address space, that must have been done previously
 117  * with a separate "access_ok()" call (this is used when we do multiple
 118  * accesses to the same area of user memory).
 119  */
 120
 121 extern void __get_user_1(void);
 122 extern void __get_user_2(void);
 123 extern void __get_user_4(void);
 124
 125 #define __get_user_x(size,ret,x,ptr) \
 126         __asm__ __volatile__("call __get_user_" #size \
 127                 :"=a" (ret),"=d" (x) \
 128                 :"0" (ptr))
 129
 130
 131 /* Careful: we have to cast the result to the type of the pointer for sign reasons */
 132 /**
 133  * get_user: - Get a simple variable from user space.
 134  * @x:   Variable to store result.
 135  * @ptr: Source address, in user space.
 136  *
 137  * Context: User context only.  This function may sleep.
 138  *
 139  * This macro copies a single simple variable from user space to kernel
 140  * space.  It supports simple types like char and int, but not larger
 141  * data types like structures or arrays.
 142  *
 143  * @ptr must have pointer-to-simple-variable type, and the result of
 144  * dereferencing @ptr must be assignable to @x without a cast.
 145  *
 146  * Returns zero on success, or -EFAULT on error.
 147  * On error, the variable @x is set to zero.
 148  */
 149 #define get_user(x,ptr)                                                 \
 150 ({      int __ret_gu;                                                   \
 151         unsigned long __val_gu;                                         \
 152         __chk_user_ptr(ptr);                                            \
 153         switch(sizeof (*(ptr))) {                                       \
 154         case 1:  __get_user_x(1,__ret_gu,__val_gu,ptr); break;          \
 155         case 2:  __get_user_x(2,__ret_gu,__val_gu,ptr); break;          \
 156         case 4:  __get_user_x(4,__ret_gu,__val_gu,ptr); break;          \
 157         default: __get_user_x(X,__ret_gu,__val_gu,ptr); break;          \
 158         }                                                               \
 159         (x) = (__typeof__(*(ptr)))__val_gu;                             \
 160         __ret_gu;                                                       \
 161 })
 162
 163 extern void __put_user_bad(void);
 164
 165 /*
 166  * Strange magic calling convention: pointer in %ecx,
 167  * value in %eax(:%edx), return value in %eax, no clobbers.
 168  */
 169 extern void __put_user_1(void);
 170 extern void __put_user_2(void);
 171 extern void __put_user_4(void);
 172 extern void __put_user_8(void);
 173
 174 #define __put_user_1(x, ptr) __asm__ __volatile__("call __put_user_1":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 175 #define __put_user_2(x, ptr) __asm__ __volatile__("call __put_user_2":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 176 #define __put_user_4(x, ptr) __asm__ __volatile__("call __put_user_4":"=a" (__ret_pu):"0" ((typeof(*(ptr)))(x)), "c" (ptr))
 177 #define __put_user_8(x, ptr) __asm__ __volatile__("call __put_user_8":"=a" (__ret_pu):"A" ((typeof(*(ptr)))(x)), "c" (ptr))
 178 #define __put_user_X(x, ptr) __asm__ __volatile__("call __put_user_X":"=a" (__ret_pu):"c" (ptr))
 179
 180 /**
 181  * put_user: - Write a simple value into user space.
 182  * @x:   Value to copy to user space.
 183  * @ptr: Destination address, in user space.
 184  *
 185  * Context: User context only.  This function may sleep.
 186  *
 187  * This macro copies a single simple value from kernel space to user
 188  * space.  It supports simple types like char and int, but not larger
 189  * data types like structures or arrays.
 190  *
 191  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 192  * to the result of dereferencing @ptr.
 193  *
 194  * Returns zero on success, or -EFAULT on error.
 195  */
 196 #ifdef CONFIG_X86_WP_WORKS_OK
 197
 198 #define put_user(x,ptr)                                         \
 199 ({      int __ret_pu;                                           \
 200         __typeof__(*(ptr)) __pu_val;                            \
 201         __chk_user_ptr(ptr);                                    \
 202         __pu_val = x;                                           \
 203         switch(sizeof(*(ptr))) {                                \
 204         case 1: __put_user_1(__pu_val, ptr); break;             \
 205         case 2: __put_user_2(__pu_val, ptr); break;             \
 206         case 4: __put_user_4(__pu_val, ptr); break;             \
 207         case 8: __put_user_8(__pu_val, ptr); break;             \
 208         default:__put_user_X(__pu_val, ptr); break;             \
 209         }                                                       \
 210         __ret_pu;                                               \
 211 })
 212
 213 #else
 214 #define put_user(x,ptr)                                         \
 215 ({                                                              \
 216         int __ret_pu;                                           \
 217         __typeof__(*(ptr)) __pus_tmp = x;                       \
 218         __ret_pu=0;                                             \
 219         if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp,          \
 220                                 sizeof(*(ptr))) != 0))          \
 221                 __ret_pu=-EFAULT;                               \
 222         __ret_pu;                                               \
 223  })
 224
 225
 226 #endif
 227
 228 /**
 229  * __get_user: - Get a simple variable from user space, with less checking.
 230  * @x:   Variable to store result.
 231  * @ptr: Source address, in user space.
 232  *
 233  * Context: User context only.  This function may sleep.
 234  *
 235  * This macro copies a single simple variable from user space to kernel
 236  * space.  It supports simple types like char and int, but not larger
 237  * data types like structures or arrays.
 238  *
 239  * @ptr must have pointer-to-simple-variable type, and the result of
 240  * dereferencing @ptr must be assignable to @x without a cast.
 241  *
 242  * Caller must check the pointer with access_ok() before calling this
 243  * function.
 244  *
 245  * Returns zero on success, or -EFAULT on error.
 246  * On error, the variable @x is set to zero.
 247  */
 248 #define __get_user(x,ptr) \
 249   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
 250
 251
 252 /**
 253  * __put_user: - Write a simple value into user space, with less checking.
 254  * @x:   Value to copy to user space.
 255  * @ptr: Destination address, in user space.
 256  *
 257  * Context: User context only.  This function may sleep.
 258  *
 259  * This macro copies a single simple value from kernel space to user
 260  * space.  It supports simple types like char and int, but not larger
 261  * data types like structures or arrays.
 262  *
 263  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
 264  * to the result of dereferencing @ptr.
 265  *
 266  * Caller must check the pointer with access_ok() before calling this
 267  * function.
 268  *
 269  * Returns zero on success, or -EFAULT on error.
 270  */
 271 #define __put_user(x,ptr) \
 272   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 273
 274 #define __put_user_nocheck(x,ptr,size)                          \
 275 ({                                                              \
 276         long __pu_err;                                          \
 277         __put_user_size((x),(ptr),(size),__pu_err,-EFAULT);     \
 278         __pu_err;                                               \
 279 })
 280
 281
 282 #define __put_user_u64(x, addr, err)                            \
 283         __asm__ __volatile__(                                   \
 284                 "1:     movl %%eax,0(%2)\n"                     \
 285                 "2:     movl %%edx,4(%2)\n"                     \
 286                 "3:\n"                                          \
 287                 ".section .fixup,\"ax\"\n"                      \
 288                 "4:     movl %3,%0\n"                           \
 289                 "       jmp 3b\n"                               \
 290                 ".previous\n"                                   \
 291                 _ASM_EXTABLE(1b,4b)                             \
 292                 _ASM_EXTABLE(2b,4b)                             \
 293                 : "=r"(err)                                     \
 294                 : "A" (x), "r" (addr), "i"(-EFAULT), "0"(err))
 295
 296 #ifdef CONFIG_X86_WP_WORKS_OK
 297
 298 #define __put_user_size(x,ptr,size,retval,errret)                       \
 299 do {                                                                    \
 300         retval = 0;                                                     \
 301         __chk_user_ptr(ptr);                                            \
 302         switch (size) {                                                 \
 303         case 1: __put_user_asm(x,ptr,retval,"b","b","iq",errret);break; \
 304         case 2: __put_user_asm(x,ptr,retval,"w","w","ir",errret);break; \
 305         case 4: __put_user_asm(x,ptr,retval,"l","","ir",errret); break; \
 306         case 8: __put_user_u64((__typeof__(*ptr))(x),ptr,retval); break;\
 307           default: __put_user_bad();                                    \
 308         }                                                               \
 309 } while (0)
 310
 311 #else
 312
 313 #define __put_user_size(x,ptr,size,retval,errret)                       \
 314 do {                                                                    \
 315         __typeof__(*(ptr)) __pus_tmp = x;                               \
 316         retval = 0;                                                     \
 317                                                                         \
 318         if(unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))     \
 319                 retval = errret;                                        \
 320 } while (0)
 321
 322 #endif
 323 struct __large_struct { unsigned long buf[100]; };
 324 #define __m(x) (*(struct __large_struct __user *)(x))
 325
 326 /*
 327  * Tell gcc we read from memory instead of writing: this is because
 328  * we do not write to any memory gcc knows about, so there are no
 329  * aliasing issues.
 330  */
 331 #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 332         __asm__ __volatile__(                                           \
 333                 "1:     mov"itype" %"rtype"1,%2\n"                      \
 334                 "2:\n"                                                  \
 335                 ".section .fixup,\"ax\"\n"                              \
 336                 "3:     movl %3,%0\n"                                   \
 337                 "       jmp 2b\n"                                       \
 338                 ".previous\n"                                           \
 339                 _ASM_EXTABLE(1b,3b)                                     \
 340                 : "=r"(err)                                             \
 341                 : ltype (x), "m"(__m(addr)), "i"(errret), "0"(err))
 342
 343
 344 #define __get_user_nocheck(x,ptr,size)                          \
 345 ({                                                              \
 346         long __gu_err;                                          \
 347         unsigned long __gu_val;                                 \
 348         __get_user_size(__gu_val,(ptr),(size),__gu_err,-EFAULT);\
 349         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 350         __gu_err;                                               \
 351 })
 352
 353 extern long __get_user_bad(void);
 354
 355 #define __get_user_size(x,ptr,size,retval,errret)                       \
 356 do {                                                                    \
 357         retval = 0;                                                     \
 358         __chk_user_ptr(ptr);                                            \
 359         switch (size) {                                                 \
 360         case 1: __get_user_asm(x,ptr,retval,"b","b","=q",errret);break; \
 361         case 2: __get_user_asm(x,ptr,retval,"w","w","=r",errret);break; \
 362         case 4: __get_user_asm(x,ptr,retval,"l","","=r",errret);break;  \
 363         default: (x) = __get_user_bad();                                \
 364         }                                                               \
 365 } while (0)
 366
 367 #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)       \
 368         __asm__ __volatile__(                                           \
 369                 "1:     mov"itype" %2,%"rtype"1\n"                      \
 370                 "2:\n"                                                  \
 371                 ".section .fixup,\"ax\"\n"                              \
 372                 "3:     movl %3,%0\n"                                   \
 373                 "       xor"itype" %"rtype"1,%"rtype"1\n"               \
 374                 "       jmp 2b\n"                                       \
 375                 ".previous\n"                                           \
 376                 _ASM_EXTABLE(1b,3b)                                     \
 377                 : "=r"(err), ltype (x)                                  \
 378                 : "m"(__m(addr)), "i"(errret), "0"(err))
 379
 380
 381 unsigned long __must_check __copy_to_user_ll(void __user *to,
 382                                 const void *from, unsigned long n);
 383 unsigned long __must_check __copy_from_user_ll(void *to,
 384                                 const void __user *from, unsigned long n);
 385 unsigned long __must_check __copy_from_user_ll_nozero(void *to,
 386                                 const void __user *from, unsigned long n);
 387 unsigned long __must_check __copy_from_user_ll_nocache(void *to,
 388                                 const void __user *from, unsigned long n);
 389 unsigned long __must_check __copy_from_user_ll_nocache_nozero(void *to,
 390                                 const void __user *from, unsigned long n);
 391
 392 /**
 393  * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
 394  * @to:   Destination address, in user space.
 395  * @from: Source address, in kernel space.
 396  * @n:    Number of bytes to copy.
 397  *
 398  * Context: User context only.
 399  *
 400  * Copy data from kernel space to user space.  Caller must check
 401  * the specified block with access_ok() before calling this function.
 402  * The caller should also make sure he pins the user space address
 403  * so that the we don't result in page fault and sleep.
 404  *
 405  * Here we special-case 1, 2 and 4-byte copy_*_user invocations.  On a fault
 406  * we return the initial request size (1, 2 or 4), as copy_*_user should do.
 407  * If a store crosses a page boundary and gets a fault, the x86 will not write
 408  * anything, so this is accurate.
 409  */
 410
 411 static __always_inline unsigned long __must_check
 412 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 413 {
 414         if (__builtin_constant_p(n)) {
 415                 unsigned long ret;
 416
 417                 switch (n) {
 418                 case 1:
 419                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret, 1);
 420                         return ret;
 421                 case 2:
 422                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret, 2);
 423                         return ret;
 424                 case 4:
 425                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret, 4);
 426                         return ret;
 427                 }
 428         }
 429         return __copy_to_user_ll(to, from, n);
 430 }
 431
 432 /**
 433  * __copy_to_user: - Copy a block of data into user space, with less checking.
 434  * @to:   Destination address, in user space.
 435  * @from: Source address, in kernel space.
 436  * @n:    Number of bytes to copy.
 437  *
 438  * Context: User context only.  This function may sleep.
 439  *
 440  * Copy data from kernel space to user space.  Caller must check
 441  * the specified block with access_ok() before calling this function.
 442  *
 443  * Returns number of bytes that could not be copied.
 444  * On success, this will be zero.
 445  */
 446 static __always_inline unsigned long __must_check
 447 __copy_to_user(void __user *to, const void *from, unsigned long n)
 448 {
 449        might_sleep();
 450        return __copy_to_user_inatomic(to, from, n);
 451 }
 452
 453 static __always_inline unsigned long
 454 __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
 455 {
 456         /* Avoid zeroing the tail if the copy fails..
 457          * If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
 458          * but as the zeroing behaviour is only significant when n is not
 459          * constant, that shouldn't be a problem.
 460          */
 461         if (__builtin_constant_p(n)) {
 462                 unsigned long ret;
 463
 464                 switch (n) {
 465                 case 1:
 466                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 467                         return ret;
 468                 case 2:
 469                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 470                         return ret;
 471                 case 4:
 472                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 473                         return ret;
 474                 }
 475         }
 476         return __copy_from_user_ll_nozero(to, from, n);
 477 }
 478
 479 /**
 480  * __copy_from_user: - Copy a block of data from user space, with less checking.
 481  * @to:   Destination address, in kernel space.
 482  * @from: Source address, in user space.
 483  * @n:    Number of bytes to copy.
 484  *
 485  * Context: User context only.  This function may sleep.
 486  *
 487  * Copy data from user space to kernel space.  Caller must check
 488  * the specified block with access_ok() before calling this function.
 489  *
 490  * Returns number of bytes that could not be copied.
 491  * On success, this will be zero.
 492  *
 493  * If some data could not be copied, this function will pad the copied
 494  * data to the requested size using zero bytes.
 495  *
 496  * An alternate version - __copy_from_user_inatomic() - may be called from
 497  * atomic context and will fail rather than sleep.  In this case the
 498  * uncopied bytes will *NOT* be padded with zeros.  See fs/filemap.h
 499  * for explanation of why this is needed.
 500  */
 501 static __always_inline unsigned long
 502 __copy_from_user(void *to, const void __user *from, unsigned long n)
 503 {
 504         might_sleep();
 505         if (__builtin_constant_p(n)) {
 506                 unsigned long ret;
 507
 508                 switch (n) {
 509                 case 1:
 510                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 511                         return ret;
 512                 case 2:
 513                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 514                         return ret;
 515                 case 4:
 516                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 517                         return ret;
 518                 }
 519         }
 520         return __copy_from_user_ll(to, from, n);
 521 }
 522
 523 #define ARCH_HAS_NOCACHE_UACCESS
 524
 525 static __always_inline unsigned long __copy_from_user_nocache(void *to,
 526                                 const void __user *from, unsigned long n)
 527 {
 528         might_sleep();
 529         if (__builtin_constant_p(n)) {
 530                 unsigned long ret;
 531
 532                 switch (n) {
 533                 case 1:
 534                         __get_user_size(*(u8 *)to, from, 1, ret, 1);
 535                         return ret;
 536                 case 2:
 537                         __get_user_size(*(u16 *)to, from, 2, ret, 2);
 538                         return ret;
 539                 case 4:
 540                         __get_user_size(*(u32 *)to, from, 4, ret, 4);
 541                         return ret;
 542                 }
 543         }
 544         return __copy_from_user_ll_nocache(to, from, n);
 545 }
 546
 547 static __always_inline unsigned long
 548 __copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n)
 549 {
 550        return __copy_from_user_ll_nocache_nozero(to, from, n);
 551 }
 552
 553 unsigned long __must_check copy_to_user(void __user *to,
 554                                 const void *from, unsigned long n);
 555 unsigned long __must_check copy_from_user(void *to,
 556                                 const void __user *from, unsigned long n);
 557 long __must_check strncpy_from_user(char *dst, const char __user *src,
 558                                 long count);
 559 long __must_check __strncpy_from_user(char *dst,
 560                                 const char __user *src, long count);
 561
 562 /**
 563  * strlen_user: - Get the size of a string in user space.
 564  * @str: The string to measure.
 565  *
 566  * Context: User context only.  This function may sleep.
 567  *
 568  * Get the size of a NUL-terminated string in user space.
 569  *
 570  * Returns the size of the string INCLUDING the terminating NUL.
 571  * On exception, returns 0.
 572  *
 573  * If there is a limit on the length of a valid string, you may wish to
 574  * consider using strnlen_user() instead.
 575  */
 576 #define strlen_user(str) strnlen_user(str, LONG_MAX)
 577
 578 long strnlen_user(const char __user *str, long n);
 579 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 580 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 581
 582 #endif /* __i386_UACCESS_H */