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 #include <asm/page.h>
  11
  12 #define VERIFY_READ     0
  13 #define VERIFY_WRITE    1
  14
  15 /*
  16  * The fs value determines whether argument validity checking should be
  17  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  18  * get_fs() == KERNEL_DS, checking is bypassed.
  19  *
  20  * For historical reasons, these macros are grossly misnamed.
  21  *
  22  * The fs/ds values are now the highest legal address in the "segment".
  23  * This simplifies the checking in the routines below.
  24  */
  25
  26 #define MAKE_MM_SEG(s)  ((mm_segment_t) { (s) })
  27
  28 #define KERNEL_DS       MAKE_MM_SEG(~0UL)
  29 #ifdef __powerpc64__
  30 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
  31 #define USER_DS         MAKE_MM_SEG(TASK_SIZE_USER64 - 1)
  32 #else
  33 #define USER_DS         MAKE_MM_SEG(TASK_SIZE - 1)
  34 #endif
  35
  36 #define get_ds()        (KERNEL_DS)
  37 #define get_fs()        (current->thread.fs)
  38 #define set_fs(val)     (current->thread.fs = (val))
  39
  40 #define segment_eq(a, b)        ((a).seg == (b).seg)
  41
  42 #ifdef __powerpc64__
  43 /*
  44  * This check is sufficient because there is a large enough
  45  * gap between user addresses and the kernel addresses
  46  */
  47 #define __access_ok(addr, size, segment)        \
  48         (((addr) <= (segment).seg) && ((size) <= (segment).seg))
  49
  50 #else
  51
  52 #define __access_ok(addr, size, segment)        \
  53         (((addr) <= (segment).seg) &&           \
  54          (((size) == 0) || (((size) - 1) <= ((segment).seg - (addr)))))
  55
  56 #endif
  57
  58 #define access_ok(type, addr, size)             \
  59         (__chk_user_ptr(addr),                  \
  60          __access_ok((__force unsigned long)(addr), (size), get_fs()))
  61
  62 /*
  63  * The exception table consists of pairs of addresses: the first is the
  64  * address of an instruction that is allowed to fault, and the second is
  65  * the address at which the program should continue.  No registers are
  66  * modified, so it is entirely up to the continuation code to figure out
  67  * what to do.
  68  *
  69  * All the routines below use bits of fixup code that are out of line
  70  * with the main instruction path.  This means when everything is well,
  71  * we don't even have to jump over them.  Further, they do not intrude
  72  * on our cache or tlb entries.
  73  */
  74
  75 struct exception_table_entry {
  76         unsigned long insn;
  77         unsigned long fixup;
  78 };
  79
  80 /*
  81  * These are the main single-value transfer routines.  They automatically
  82  * use the right size if we just have the right pointer type.
  83  *
  84  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  85  * and yet we don't want to do any pointers, because that is too much
  86  * of a performance impact. Thus we have a few rather ugly macros here,
  87  * and hide all the ugliness from the user.
  88  *
  89  * The "__xxx" versions of the user access functions are versions that
  90  * do not verify the address space, that must have been done previously
  91  * with a separate "access_ok()" call (this is used when we do multiple
  92  * accesses to the same area of user memory).
  93  *
  94  * As we use the same address space for kernel and user data on the
  95  * PowerPC, we can just do these as direct assignments.  (Of course, the
  96  * exception handling means that it's no longer "just"...)
  97  *
  98  * The "user64" versions of the user access functions are versions that
  99  * allow access of 64-bit data. The "get_user" functions do not
 100  * properly handle 64-bit data because the value gets down cast to a long.
 101  * The "put_user" functions already handle 64-bit data properly but we add
 102  * "user64" versions for completeness
 103  */
 104 #define get_user(x, ptr) \
 105         __get_user_check((x), (ptr), sizeof(*(ptr)))
 106 #define put_user(x, ptr) \
 107         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 108
 109 #define __get_user(x, ptr) \
 110         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 111 #define __put_user(x, ptr) \
 112         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 113 #ifndef __powerpc64__
 114 #define __get_user64(x, ptr) \
 115         __get_user64_nocheck((x), (ptr), sizeof(*(ptr)))
 116 #define __put_user64(x, ptr) __put_user(x, ptr)
 117 #endif
 118
 119 #define __get_user_unaligned __get_user
 120 #define __put_user_unaligned __put_user
 121
 122 extern long __put_user_bad(void);
 123
 124 /*
 125  * We don't tell gcc that we are accessing memory, but this is OK
 126  * because we do not write to any memory gcc knows about, so there
 127  * are no aliasing issues.
 128  */
 129 #define __put_user_asm(x, addr, err, op)                        \
 130         __asm__ __volatile__(                                   \
 131                 "1:     " op " %1,0(%2) # put_user\n"           \
 132                 "2:\n"                                          \
 133                 ".section .fixup,\"ax\"\n"                      \
 134                 "3:     li %0,%3\n"                             \
 135                 "       b 2b\n"                                 \
 136                 ".previous\n"                                   \
 137                 ".section __ex_table,\"a\"\n"                   \
 138                 "       .balign %5\n"                           \
 139                         PPC_LONG "1b,3b\n"                      \
 140                 ".previous"                                     \
 141                 : "=r" (err)                                    \
 142                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err),\
 143                   "i"(sizeof(unsigned long)))
 144
 145 #ifdef __powerpc64__
 146 #define __put_user_asm2(x, ptr, retval)                         \
 147           __put_user_asm(x, ptr, retval, "std")
 148 #else /* __powerpc64__ */
 149 #define __put_user_asm2(x, addr, err)                           \
 150         __asm__ __volatile__(                                   \
 151                 "1:     stw %1,0(%2)\n"                         \
 152                 "2:     stw %1+1,4(%2)\n"                       \
 153                 "3:\n"                                          \
 154                 ".section .fixup,\"ax\"\n"                      \
 155                 "4:     li %0,%3\n"                             \
 156                 "       b 3b\n"                                 \
 157                 ".previous\n"                                   \
 158                 ".section __ex_table,\"a\"\n"                   \
 159                 "       .balign %5\n"                           \
 160                         PPC_LONG "1b,4b\n"                      \
 161                         PPC_LONG "2b,4b\n"                      \
 162                 ".previous"                                     \
 163                 : "=r" (err)                                    \
 164                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err),\
 165                   "i"(sizeof(unsigned long)))
 166 #endif /* __powerpc64__ */
 167
 168 #define __put_user_size(x, ptr, size, retval)                   \
 169 do {                                                            \
 170         retval = 0;                                             \
 171         switch (size) {                                         \
 172           case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
 173           case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
 174           case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
 175           case 8: __put_user_asm2(x, ptr, retval); break;       \
 176           default: __put_user_bad();                            \
 177         }                                                       \
 178 } while (0)
 179
 180 #define __put_user_nocheck(x, ptr, size)                        \
 181 ({                                                              \
 182         long __pu_err;                                          \
 183         __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
 184         if (!is_kernel_addr((unsigned long)__pu_addr))          \
 185                 might_sleep();                                  \
 186         __chk_user_ptr(ptr);                                    \
 187         __put_user_size((x), __pu_addr, (size), __pu_err);      \
 188         __pu_err;                                               \
 189 })
 190
 191 #define __put_user_check(x, ptr, size)                                  \
 192 ({                                                                      \
 193         long __pu_err = -EFAULT;                                        \
 194         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 195         might_sleep();                                                  \
 196         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
 197                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 198         __pu_err;                                                       \
 199 })
 200
 201 extern long __get_user_bad(void);
 202
 203 #define __get_user_asm(x, addr, err, op)                \
 204         __asm__ __volatile__(                           \
 205                 "1:     "op" %1,0(%2)   # get_user\n"   \
 206                 "2:\n"                                  \
 207                 ".section .fixup,\"ax\"\n"              \
 208                 "3:     li %0,%3\n"                     \
 209                 "       li %1,0\n"                      \
 210                 "       b 2b\n"                         \
 211                 ".previous\n"                           \
 212                 ".section __ex_table,\"a\"\n"           \
 213                 "       .balign %5\n"                   \
 214                         PPC_LONG "1b,3b\n"              \
 215                 ".previous"                             \
 216                 : "=r" (err), "=r" (x)                  \
 217                 : "b" (addr), "i" (-EFAULT), "0" (err), \
 218                   "i"(sizeof(unsigned long)))
 219
 220 #ifdef __powerpc64__
 221 #define __get_user_asm2(x, addr, err)                   \
 222         __get_user_asm(x, addr, err, "ld")
 223 #else /* __powerpc64__ */
 224 #define __get_user_asm2(x, addr, err)                   \
 225         __asm__ __volatile__(                           \
 226                 "1:     lwz %1,0(%2)\n"                 \
 227                 "2:     lwz %1+1,4(%2)\n"               \
 228                 "3:\n"                                  \
 229                 ".section .fixup,\"ax\"\n"              \
 230                 "4:     li %0,%3\n"                     \
 231                 "       li %1,0\n"                      \
 232                 "       li %1+1,0\n"                    \
 233                 "       b 3b\n"                         \
 234                 ".previous\n"                           \
 235                 ".section __ex_table,\"a\"\n"           \
 236                 "       .balign %5\n"                   \
 237                         PPC_LONG "1b,4b\n"              \
 238                         PPC_LONG "2b,4b\n"              \
 239                 ".previous"                             \
 240                 : "=r" (err), "=&r" (x)                 \
 241                 : "b" (addr), "i" (-EFAULT), "0" (err), \
 242                   "i"(sizeof(unsigned long)))
 243 #endif /* __powerpc64__ */
 244
 245 #define __get_user_size(x, ptr, size, retval)                   \
 246 do {                                                            \
 247         retval = 0;                                             \
 248         __chk_user_ptr(ptr);                                    \
 249         if (size > sizeof(x))                                   \
 250                 (x) = __get_user_bad();                         \
 251         switch (size) {                                         \
 252         case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
 253         case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
 254         case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
 255         case 8: __get_user_asm2(x, ptr, retval);  break;        \
 256         default: (x) = __get_user_bad();                        \
 257         }                                                       \
 258 } while (0)
 259
 260 #define __get_user_nocheck(x, ptr, size)                        \
 261 ({                                                              \
 262         long __gu_err;                                          \
 263         unsigned long __gu_val;                                 \
 264         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
 265         __chk_user_ptr(ptr);                                    \
 266         if (!is_kernel_addr((unsigned long)__gu_addr))          \
 267                 might_sleep();                                  \
 268         __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 269         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 270         __gu_err;                                               \
 271 })
 272
 273 #ifndef __powerpc64__
 274 #define __get_user64_nocheck(x, ptr, size)                      \
 275 ({                                                              \
 276         long __gu_err;                                          \
 277         long long __gu_val;                                     \
 278         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
 279         __chk_user_ptr(ptr);                                    \
 280         if (!is_kernel_addr((unsigned long)__gu_addr))          \
 281                 might_sleep();                                  \
 282         __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 283         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 284         __gu_err;                                               \
 285 })
 286 #endif /* __powerpc64__ */
 287
 288 #define __get_user_check(x, ptr, size)                                  \
 289 ({                                                                      \
 290         long __gu_err = -EFAULT;                                        \
 291         unsigned long  __gu_val = 0;                                    \
 292         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
 293         might_sleep();                                                  \
 294         if (access_ok(VERIFY_READ, __gu_addr, (size)))                  \
 295                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 296         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 297         __gu_err;                                                       \
 298 })
 299
 300 /* more complex routines */
 301
 302 extern unsigned long __copy_tofrom_user(void __user *to,
 303                 const void __user *from, unsigned long size);
 304
 305 #ifndef __powerpc64__
 306
 307 static inline unsigned long copy_from_user(void *to,
 308                 const void __user *from, unsigned long n)
 309 {
 310         unsigned long over;
 311
 312         if (access_ok(VERIFY_READ, from, n))
 313                 return __copy_tofrom_user((__force void __user *)to, from, n);
 314         if ((unsigned long)from < TASK_SIZE) {
 315                 over = (unsigned long)from + n - TASK_SIZE;
 316                 return __copy_tofrom_user((__force void __user *)to, from,
 317                                 n - over) + over;
 318         }
 319         return n;
 320 }
 321
 322 static inline unsigned long copy_to_user(void __user *to,
 323                 const void *from, unsigned long n)
 324 {
 325         unsigned long over;
 326
 327         if (access_ok(VERIFY_WRITE, to, n))
 328                 return __copy_tofrom_user(to, (__force void __user *)from, n);
 329         if ((unsigned long)to < TASK_SIZE) {
 330                 over = (unsigned long)to + n - TASK_SIZE;
 331                 return __copy_tofrom_user(to, (__force void __user *)from,
 332                                 n - over) + over;
 333         }
 334         return n;
 335 }
 336
 337 #else /* __powerpc64__ */
 338
 339 #define __copy_in_user(to, from, size) \
 340         __copy_tofrom_user((to), (from), (size))
 341
 342 extern unsigned long copy_from_user(void *to, const void __user *from,
 343                                     unsigned long n);
 344 extern unsigned long copy_to_user(void __user *to, const void *from,
 345                                   unsigned long n);
 346 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 347                                   unsigned long n);
 348
 349 #endif /* __powerpc64__ */
 350
 351 static inline unsigned long __copy_from_user_inatomic(void *to,
 352                 const void __user *from, unsigned long n)
 353 {
 354         if (__builtin_constant_p(n) && (n <= 8)) {
 355                 unsigned long ret;
 356
 357                 switch (n) {
 358                 case 1:
 359                         __get_user_size(*(u8 *)to, from, 1, ret);
 360                         break;
 361                 case 2:
 362                         __get_user_size(*(u16 *)to, from, 2, ret);
 363                         break;
 364                 case 4:
 365                         __get_user_size(*(u32 *)to, from, 4, ret);
 366                         break;
 367                 case 8:
 368                         __get_user_size(*(u64 *)to, from, 8, ret);
 369                         break;
 370                 }
 371                 if (ret == 0)
 372                         return 0;
 373         }
 374         return __copy_tofrom_user((__force void __user *)to, from, n);
 375 }
 376
 377 static inline unsigned long __copy_to_user_inatomic(void __user *to,
 378                 const void *from, unsigned long n)
 379 {
 380         if (__builtin_constant_p(n) && (n <= 8)) {
 381                 unsigned long ret;
 382
 383                 switch (n) {
 384                 case 1:
 385                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret);
 386                         break;
 387                 case 2:
 388                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret);
 389                         break;
 390                 case 4:
 391                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret);
 392                         break;
 393                 case 8:
 394                         __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret);
 395                         break;
 396                 }
 397                 if (ret == 0)
 398                         return 0;
 399         }
 400         return __copy_tofrom_user(to, (__force const void __user *)from, n);
 401 }
 402
 403 static inline unsigned long __copy_from_user(void *to,
 404                 const void __user *from, unsigned long size)
 405 {
 406         might_sleep();
 407         return __copy_from_user_inatomic(to, from, size);
 408 }
 409
 410 static inline unsigned long __copy_to_user(void __user *to,
 411                 const void *from, unsigned long size)
 412 {
 413         might_sleep();
 414         return __copy_to_user_inatomic(to, from, size);
 415 }
 416
 417 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 418
 419 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 420 {
 421         might_sleep();
 422         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 423                 return __clear_user(addr, size);
 424         if ((unsigned long)addr < TASK_SIZE) {
 425                 unsigned long over = (unsigned long)addr + size - TASK_SIZE;
 426                 return __clear_user(addr, size - over) + over;
 427         }
 428         return size;
 429 }
 430
 431 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
 432
 433 static inline long strncpy_from_user(char *dst, const char __user *src,
 434                 long count)
 435 {
 436         might_sleep();
 437         if (likely(access_ok(VERIFY_READ, src, 1)))
 438                 return __strncpy_from_user(dst, src, count);
 439         return -EFAULT;
 440 }
 441
 442 /*
 443  * Return the size of a string (including the ending 0)
 444  *
 445  * Return 0 for error
 446  */
 447 extern int __strnlen_user(const char __user *str, long len, unsigned long top);
 448
 449 /*
 450  * Returns the length of the string at str (including the null byte),
 451  * or 0 if we hit a page we can't access,
 452  * or something > len if we didn't find a null byte.
 453  *
 454  * The `top' parameter to __strnlen_user is to make sure that
 455  * we can never overflow from the user area into kernel space.
 456  */
 457 static inline int strnlen_user(const char __user *str, long len)
 458 {
 459         unsigned long top = current->thread.fs.seg;
 460
 461         if ((unsigned long)str > top)
 462                 return 0;
 463         return __strnlen_user(str, len, top);
 464 }
 465
 466 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 467
 468 #endif  /* __ASSEMBLY__ */
 469 #endif /* __KERNEL__ */
 470
 471 #endif  /* _ARCH_POWERPC_UACCESS_H */