include/asm-powerpc/uaccess.h

   1 #ifndef _ARCH_POWERPC_UACCESS_H
   2 #define _ARCH_POWERPC_UACCESS_H
   3
   4 #ifdef __KERNEL__
   5 #ifndef __ASSEMBLY__
   6
   7 #include <linux/sched.h>
   8 #include <linux/errno.h>
   9 #include <asm/processor.h>
  10
  11 #define VERIFY_READ     0
  12 #define VERIFY_WRITE    1
  13
  14 /*
  15  * The fs value determines whether argument validity checking should be
  16  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  17  * get_fs() == KERNEL_DS, checking is bypassed.
  18  *
  19  * For historical reasons, these macros are grossly misnamed.
  20  *
  21  * The fs/ds values are now the highest legal address in the "segment".
  22  * This simplifies the checking in the routines below.
  23  */
  24
  25 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  26
  27 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  28 #ifdef __powerpc64__
  29 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
  30 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
  31 #else
  32 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
  33 #endif
  34
  35 #define get_ds()        (KERNEL_DS)
  36 #define get_fs()        (current->thread.fs)
  37 #define set_fs(val)     (current->thread.fs = (val))
  38
  39 #define segment_eq(a, b)        ((a).seg == (b).seg)
  40
  41 #ifdef __powerpc64__
  42 /*
  43  * This check is sufficient because there is a large enough
  44  * gap between user addresses and the kernel addresses
  45  */
  46 #define __access_ok(addr, size, segment)        \
  47         (((addr) <= (segment).seg) && ((size) <= (segment).seg))
  48
  49 #else
  50
  51 #define __access_ok(addr, size, segment)        \
  52         (((addr) <= (segment).seg) &&           \
  53          (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
  54
  55 #endif
  56
  57 #define access_ok(type, addr, size)             \
  58         (__chk_user_ptr(addr),                  \
  59          __access_ok((__force unsigned long)(addr), (size), get_fs()))
  60
  61 /*
  62  * The exception table consists of pairs of addresses: the first is the
  63  * address of an instruction that is allowed to fault, and the second is
  64  * the address at which the program should continue.  No registers are
  65  * modified, so it is entirely up to the continuation code to figure out
  66  * what to do.
  67  *
  68  * All the routines below use bits of fixup code that are out of line
  69  * with the main instruction path.  This means when everything is well,
  70  * we don't even have to jump over them.  Further, they do not intrude
  71  * on our cache or tlb entries.
  72  */
  73
  74 struct exception_table_entry {
  75         unsigned long insn;
  76         unsigned long fixup;
  77 };
  78
  79 /*
  80  * These are the main single-value transfer routines.  They automatically
  81  * use the right size if we just have the right pointer type.
  82  *
  83  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  84  * and yet we don't want to do any pointers, because that is too much
  85  * of a performance impact. Thus we have a few rather ugly macros here,
  86  * and hide all the ugliness from the user.
  87  *
  88  * The "__xxx" versions of the user access functions are versions that
  89  * do not verify the address space, that must have been done previously
  90  * with a separate "access_ok()" call (this is used when we do multiple
  91  * accesses to the same area of user memory).
  92  *
  93  * As we use the same address space for kernel and user data on the
  94  * PowerPC, we can just do these as direct assignments.  (Of course, the
  95  * exception handling means that it's no longer "just"...)
  96  *
  97  * The "user64" versions of the user access functions are versions that
  98  * allow access of 64-bit data. The "get_user" functions do not
  99  * properly handle 64-bit data because the value gets down cast to a long.
 100  * The "put_user" functions already handle 64-bit data properly but we add
 101  * "user64" versions for completeness
 102  */
 103 #define get_user(x, ptr) \
 104         __get_user_check((x), (ptr), sizeof(*(ptr)))
 105 #define put_user(x, ptr) \
 106         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 107
 108 #define __get_user(x, ptr) \
 109         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 110 #define __put_user(x, ptr) \
 111         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 112 #ifndef __powerpc64__
 113 #define __get_user64(x, ptr) \
 114         __get_user64_nocheck((x), (ptr), sizeof(*(ptr)))
 115 #define __put_user64(x, ptr) __put_user(x, ptr)
 116 #endif
 117
 118 #define __get_user_unaligned __get_user
 119 #define __put_user_unaligned __put_user
 120
 121 extern long __put_user_bad(void);
 122
 123 /*
 124  * We don't tell gcc that we are accessing memory, but this is OK
 125  * because we do not write to any memory gcc knows about, so there
 126  * are no aliasing issues.
 127  */
 128 #define __put_user_asm(x, addr, err, op)                        \
 129         __asm__ __volatile__(                                   \
 130                 "1:     " op " %1,0(%2) # put_user\n"           \
 131                 "2:\n"                                          \
 132                 ".section .fixup,\"ax\"\n"                      \
 133                 "3:     li %0,%3\n"                             \
 134                 "       b 2b\n"                                 \
 135                 ".previous\n"                                   \
 136                 ".section __ex_table,\"a\"\n"                   \
 137                 "       .balign %5\n"                           \
 138                         PPC_LONG "1b,3b\n"                      \
 139                 ".previous"                                     \
 140                 : "=r" (err)                                    \
 141                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err),\
 142                   "i"(sizeof(unsigned long)))
 143
 144 #ifdef __powerpc64__
 145 #define __put_user_asm2(x, ptr, retval)                         \
 146           __put_user_asm(x, ptr, retval, "std")
 147 #else /* __powerpc64__ */
 148 #define __put_user_asm2(x, addr, err)                           \
 149         __asm__ __volatile__(                                   \
 150                 "1:     stw %1,0(%2)\n"                         \
 151                 "2:     stw %1+1,4(%2)\n"                       \
 152                 "3:\n"                                          \
 153                 ".section .fixup,\"ax\"\n"                      \
 154                 "4:     li %0,%3\n"                             \
 155                 "       b 3b\n"                                 \
 156                 ".previous\n"                                   \
 157                 ".section __ex_table,\"a\"\n"                   \
 158                 "       .balign %5\n"                           \
 159                         PPC_LONG "1b,4b\n"                      \
 160                         PPC_LONG "2b,4b\n"                      \
 161                 ".previous"                                     \
 162                 : "=r" (err)                                    \
 163                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err),\
 164                   "i"(sizeof(unsigned long)))
 165 #endif /* __powerpc64__ */
 166
 167 #define __put_user_size(x, ptr, size, retval)                   \
 168 do {                                                            \
 169         retval = 0;                                             \
 170         switch (size) {                                         \
 171           case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
 172           case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
 173           case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
 174           case 8: __put_user_asm2(x, ptr, retval); break;       \
 175           default: __put_user_bad();                            \
 176         }                                                       \
 177 } while (0)
 178
 179 #define __put_user_nocheck(x, ptr, size)                        \
 180 ({                                                              \
 181         long __pu_err;                                          \
 182         might_sleep();                                          \
 183         __chk_user_ptr(ptr);                                    \
 184         __put_user_size((x), (ptr), (size), __pu_err);          \
 185         __pu_err;                                               \
 186 })
 187
 188 #define __put_user_check(x, ptr, size)                                  \
 189 ({                                                                      \
 190         long __pu_err = -EFAULT;                                        \
 191         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 192         might_sleep();                                                  \
 193         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
 194                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 195         __pu_err;                                                       \
 196 })
 197
 198 extern long __get_user_bad(void);
 199
 200 #define __get_user_asm(x, addr, err, op)                \
 201         __asm__ __volatile__(                           \
 202                 "1:     "op" %1,0(%2)   # get_user\n"   \
 203                 "2:\n"                                  \
 204                 ".section .fixup,\"ax\"\n"              \
 205                 "3:     li %0,%3\n"                     \
 206                 "       li %1,0\n"                      \
 207                 "       b 2b\n"                         \
 208                 ".previous\n"                           \
 209                 ".section __ex_table,\"a\"\n"           \
 210                 "       .balign %5\n"                   \
 211                         PPC_LONG "1b,3b\n"              \
 212                 ".previous"                             \
 213                 : "=r" (err), "=r" (x)                  \
 214                 : "b" (addr), "i" (-EFAULT), "0" (err), \
 215                   "i"(sizeof(unsigned long)))
 216
 217 #ifdef __powerpc64__
 218 #define __get_user_asm2(x, addr, err)                   \
 219         __get_user_asm(x, addr, err, "ld")
 220 #else /* __powerpc64__ */
 221 #define __get_user_asm2(x, addr, err)                   \
 222         __asm__ __volatile__(                           \
 223                 "1:     lwz %1,0(%2)\n"                 \
 224                 "2:     lwz %1+1,4(%2)\n"               \
 225                 "3:\n"                                  \
 226                 ".section .fixup,\"ax\"\n"              \
 227                 "4:     li %0,%3\n"                     \
 228                 "       li %1,0\n"                      \
 229                 "       li %1+1,0\n"                    \
 230                 "       b 3b\n"                         \
 231                 ".previous\n"                           \
 232                 ".section __ex_table,\"a\"\n"           \
 233                 "       .balign %5\n"                   \
 234                         PPC_LONG "1b,4b\n"              \
 235                         PPC_LONG "2b,4b\n"              \
 236                 ".previous"                             \
 237                 : "=r" (err), "=&r" (x)                 \
 238                 : "b" (addr), "i" (-EFAULT), "0" (err), \
 239                   "i"(sizeof(unsigned long)))
 240 #endif /* __powerpc64__ */
 241
 242 #define __get_user_size(x, ptr, size, retval)                   \
 243 do {                                                            \
 244         retval = 0;                                             \
 245         __chk_user_ptr(ptr);                                    \
 246         if (size > sizeof(x))                                   \
 247                 (x) = __get_user_bad();                         \
 248         switch (size) {                                         \
 249         case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
 250         case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
 251         case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
 252         case 8: __get_user_asm2(x, ptr, retval);  break;        \
 253         default: (x) = __get_user_bad();                        \
 254         }                                                       \
 255 } while (0)
 256
 257 #define __get_user_nocheck(x, ptr, size)                        \
 258 ({                                                              \
 259         long __gu_err;                                          \
 260         unsigned long __gu_val;                                 \
 261         __chk_user_ptr(ptr);                                    \
 262         might_sleep();                                          \
 263         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 264         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 265         __gu_err;                                               \
 266 })
 267
 268 #ifndef __powerpc64__
 269 #define __get_user64_nocheck(x, ptr, size)                      \
 270 ({                                                              \
 271         long __gu_err;                                          \
 272         long long __gu_val;                                     \
 273         __chk_user_ptr(ptr);                                    \
 274         might_sleep();                                          \
 275         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 276         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 277         __gu_err;                                               \
 278 })
 279 #endif /* __powerpc64__ */
 280
 281 #define __get_user_check(x, ptr, size)                                  \
 282 ({                                                                      \
 283         long __gu_err = -EFAULT;                                        \
 284         unsigned long  __gu_val = 0;                                    \
 285         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
 286         might_sleep();                                                  \
 287         if (access_ok(VERIFY_READ, __gu_addr, (size)))                  \
 288                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 289         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 290         __gu_err;                                                       \
 291 })
 292
 293 /* more complex routines */
 294
 295 extern unsigned long __copy_tofrom_user(void __user *to,
 296                 const void __user *from, unsigned long size);
 297
 298 #ifndef __powerpc64__
 299
 300 extern inline unsigned long copy_from_user(void *to,
 301                 const void __user *from, unsigned long n)
 302 {
 303         unsigned long over;
 304
 305         if (access_ok(VERIFY_READ, from, n))
 306                 return __copy_tofrom_user((__force void __user *)to, from, n);
 307         if ((unsigned long)from < TASK_SIZE) {
 308                 over = (unsigned long)from + n - TASK_SIZE;
 309                 return __copy_tofrom_user((__force void __user *)to, from,
 310                                 n - over) + over;
 311         }
 312         return n;
 313 }
 314
 315 extern inline unsigned long copy_to_user(void __user *to,
 316                 const void *from, unsigned long n)
 317 {
 318         unsigned long over;
 319
 320         if (access_ok(VERIFY_WRITE, to, n))
 321                 return __copy_tofrom_user(to, (__force void __user *)from, n);
 322         if ((unsigned long)to < TASK_SIZE) {
 323                 over = (unsigned long)to + n - TASK_SIZE;
 324                 return __copy_tofrom_user(to, (__force void __user *)from,
 325                                 n - over) + over;
 326         }
 327         return n;
 328 }
 329
 330 #else /* __powerpc64__ */
 331
 332 #define __copy_in_user(to, from, size) \
 333         __copy_tofrom_user((to), (from), (size))
 334
 335 extern unsigned long copy_from_user(void *to, const void __user *from,
 336                                     unsigned long n);
 337 extern unsigned long copy_to_user(void __user *to, const void *from,
 338                                   unsigned long n);
 339 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 340                                   unsigned long n);
 341
 342 #endif /* __powerpc64__ */
 343
 344 static inline unsigned long __copy_from_user_inatomic(void *to,
 345                 const void __user *from, unsigned long n)
 346 {
 347         if (__builtin_constant_p(n) && (n <= 8)) {
 348                 unsigned long ret;
 349
 350                 switch (n) {
 351                 case 1:
 352                         __get_user_size(*(u8 *)to, from, 1, ret);
 353                         break;
 354                 case 2:
 355                         __get_user_size(*(u16 *)to, from, 2, ret);
 356                         break;
 357                 case 4:
 358                         __get_user_size(*(u32 *)to, from, 4, ret);
 359                         break;
 360                 case 8:
 361                         __get_user_size(*(u64 *)to, from, 8, ret);
 362                         break;
 363                 }
 364                 if (ret == 0)
 365                         return 0;
 366         }
 367         return __copy_tofrom_user((__force void __user *)to, from, n);
 368 }
 369
 370 static inline unsigned long __copy_to_user_inatomic(void __user *to,
 371                 const void *from, unsigned long n)
 372 {
 373         if (__builtin_constant_p(n) && (n <= 8)) {
 374                 unsigned long ret;
 375
 376                 switch (n) {
 377                 case 1:
 378                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret);
 379                         break;
 380                 case 2:
 381                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret);
 382                         break;
 383                 case 4:
 384                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret);
 385                         break;
 386                 case 8:
 387                         __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret);
 388                         break;
 389                 }
 390                 if (ret == 0)
 391                         return 0;
 392         }
 393         return __copy_tofrom_user(to, (__force const void __user *)from, n);
 394 }
 395
 396 static inline unsigned long __copy_from_user(void *to,
 397                 const void __user *from, unsigned long size)
 398 {
 399         might_sleep();
 400         return __copy_from_user_inatomic(to, from, size);
 401 }
 402
 403 static inline unsigned long __copy_to_user(void __user *to,
 404                 const void *from, unsigned long size)
 405 {
 406         might_sleep();
 407         return __copy_to_user_inatomic(to, from, size);
 408 }
 409
 410 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 411
 412 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 413 {
 414         might_sleep();
 415         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 416                 return __clear_user(addr, size);
 417         if ((unsigned long)addr < TASK_SIZE) {
 418                 unsigned long over = (unsigned long)addr + size - TASK_SIZE;
 419                 return __clear_user(addr, size - over) + over;
 420         }
 421         return size;
 422 }
 423
 424 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
 425
 426 static inline long strncpy_from_user(char *dst, const char __user *src,
 427                 long count)
 428 {
 429         might_sleep();
 430         if (likely(access_ok(VERIFY_READ, src, 1)))
 431                 return __strncpy_from_user(dst, src, count);
 432         return -EFAULT;
 433 }
 434
 435 /*
 436  * Return the size of a string (including the ending 0)
 437  *
 438  * Return 0 for error
 439  */
 440 extern int __strnlen_user(const char __user *str, long len, unsigned long top);
 441
 442 /*
 443  * Returns the length of the string at str (including the null byte),
 444  * or 0 if we hit a page we can't access,
 445  * or something > len if we didn't find a null byte.
 446  *
 447  * The `top' parameter to __strnlen_user is to make sure that
 448  * we can never overflow from the user area into kernel space.
 449  */
 450 static inline int strnlen_user(const char __user *str, long len)
 451 {
 452         unsigned long top = current->thread.fs.seg;
 453
 454         if ((unsigned long)str > top)
 455                 return 0;
 456         return __strnlen_user(str, len, top);
 457 }
 458
 459 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 460
 461 #endif  /* __ASSEMBLY__ */
 462 #endif /* __KERNEL__ */
 463
 464 #endif  /* _ARCH_POWERPC_UACCESS_H */