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 #ifdef __powerpc64__
 124 #define __EX_TABLE_ALIGN        "3"
 125 #define __EX_TABLE_TYPE         "llong"
 126 #else
 127 #define __EX_TABLE_ALIGN        "2"
 128 #define __EX_TABLE_TYPE         "long"
 129 #endif
 130
 131 /*
 132  * We don't tell gcc that we are accessing memory, but this is OK
 133  * because we do not write to any memory gcc knows about, so there
 134  * are no aliasing issues.
 135  */
 136 #define __put_user_asm(x, addr, err, op)                        \
 137         __asm__ __volatile__(                                   \
 138                 "1:     " op " %1,0(%2) # put_user\n"           \
 139                 "2:\n"                                          \
 140                 ".section .fixup,\"ax\"\n"                      \
 141                 "3:     li %0,%3\n"                             \
 142                 "       b 2b\n"                                 \
 143                 ".previous\n"                                   \
 144                 ".section __ex_table,\"a\"\n"                   \
 145                 "       .align " __EX_TABLE_ALIGN "\n"          \
 146                 "       ."__EX_TABLE_TYPE" 1b,3b\n"             \
 147                 ".previous"                                     \
 148                 : "=r" (err)                                    \
 149                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 150
 151 #ifdef __powerpc64__
 152 #define __put_user_asm2(x, ptr, retval)                         \
 153           __put_user_asm(x, ptr, retval, "std")
 154 #else /* __powerpc64__ */
 155 #define __put_user_asm2(x, addr, err)                           \
 156         __asm__ __volatile__(                                   \
 157                 "1:     stw %1,0(%2)\n"                         \
 158                 "2:     stw %1+1,4(%2)\n"                       \
 159                 "3:\n"                                          \
 160                 ".section .fixup,\"ax\"\n"                      \
 161                 "4:     li %0,%3\n"                             \
 162                 "       b 3b\n"                                 \
 163                 ".previous\n"                                   \
 164                 ".section __ex_table,\"a\"\n"                   \
 165                 "       .align " __EX_TABLE_ALIGN "\n"          \
 166                 "       ." __EX_TABLE_TYPE " 1b,4b\n"           \
 167                 "       ." __EX_TABLE_TYPE " 2b,4b\n"           \
 168                 ".previous"                                     \
 169                 : "=r" (err)                                    \
 170                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 171 #endif /* __powerpc64__ */
 172
 173 #define __put_user_size(x, ptr, size, retval)                   \
 174 do {                                                            \
 175         retval = 0;                                             \
 176         switch (size) {                                         \
 177           case 1: __put_user_asm(x, ptr, retval, "stb"); break; \
 178           case 2: __put_user_asm(x, ptr, retval, "sth"); break; \
 179           case 4: __put_user_asm(x, ptr, retval, "stw"); break; \
 180           case 8: __put_user_asm2(x, ptr, retval); break;       \
 181           default: __put_user_bad();                            \
 182         }                                                       \
 183 } while (0)
 184
 185 #define __put_user_nocheck(x, ptr, size)                        \
 186 ({                                                              \
 187         long __pu_err;                                          \
 188         might_sleep();                                          \
 189         __chk_user_ptr(ptr);                                    \
 190         __put_user_size((x), (ptr), (size), __pu_err);          \
 191         __pu_err;                                               \
 192 })
 193
 194 #define __put_user_check(x, ptr, size)                                  \
 195 ({                                                                      \
 196         long __pu_err = -EFAULT;                                        \
 197         __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
 198         might_sleep();                                                  \
 199         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
 200                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 201         __pu_err;                                                       \
 202 })
 203
 204 extern long __get_user_bad(void);
 205
 206 #define __get_user_asm(x, addr, err, op)                \
 207         __asm__ __volatile__(                           \
 208                 "1:     "op" %1,0(%2)   # get_user\n"   \
 209                 "2:\n"                                  \
 210                 ".section .fixup,\"ax\"\n"              \
 211                 "3:     li %0,%3\n"                     \
 212                 "       li %1,0\n"                      \
 213                 "       b 2b\n"                         \
 214                 ".previous\n"                           \
 215                 ".section __ex_table,\"a\"\n"           \
 216                 "       .align "__EX_TABLE_ALIGN "\n"   \
 217                 "       ." __EX_TABLE_TYPE " 1b,3b\n"   \
 218                 ".previous"                             \
 219                 : "=r" (err), "=r" (x)                  \
 220                 : "b" (addr), "i" (-EFAULT), "0" (err))
 221
 222 #ifdef __powerpc64__
 223 #define __get_user_asm2(x, addr, err)                   \
 224         __get_user_asm(x, addr, err, "ld")
 225 #else /* __powerpc64__ */
 226 #define __get_user_asm2(x, addr, err)                   \
 227         __asm__ __volatile__(                           \
 228                 "1:     lwz %1,0(%2)\n"                 \
 229                 "2:     lwz %1+1,4(%2)\n"               \
 230                 "3:\n"                                  \
 231                 ".section .fixup,\"ax\"\n"              \
 232                 "4:     li %0,%3\n"                     \
 233                 "       li %1,0\n"                      \
 234                 "       li %1+1,0\n"                    \
 235                 "       b 3b\n"                         \
 236                 ".previous\n"                           \
 237                 ".section __ex_table,\"a\"\n"           \
 238                 "       .align " __EX_TABLE_ALIGN "\n"  \
 239                 "       ." __EX_TABLE_TYPE " 1b,4b\n"   \
 240                 "       ." __EX_TABLE_TYPE " 2b,4b\n"   \
 241                 ".previous"                             \
 242                 : "=r" (err), "=&r" (x)                 \
 243                 : "b" (addr), "i" (-EFAULT), "0" (err))
 244 #endif /* __powerpc64__ */
 245
 246 #define __get_user_size(x, ptr, size, retval)                   \
 247 do {                                                            \
 248         retval = 0;                                             \
 249         __chk_user_ptr(ptr);                                    \
 250         if (size > sizeof(x))                                   \
 251                 (x) = __get_user_bad();                         \
 252         switch (size) {                                         \
 253         case 1: __get_user_asm(x, ptr, retval, "lbz"); break;   \
 254         case 2: __get_user_asm(x, ptr, retval, "lhz"); break;   \
 255         case 4: __get_user_asm(x, ptr, retval, "lwz"); break;   \
 256         case 8: __get_user_asm2(x, ptr, retval);  break;        \
 257         default: (x) = __get_user_bad();                        \
 258         }                                                       \
 259 } while (0)
 260
 261 #define __get_user_nocheck(x, ptr, size)                        \
 262 ({                                                              \
 263         long __gu_err;                                          \
 264         unsigned long __gu_val;                                 \
 265         __chk_user_ptr(ptr);                                    \
 266         might_sleep();                                          \
 267         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 268         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 269         __gu_err;                                               \
 270 })
 271
 272 #ifndef __powerpc64__
 273 #define __get_user64_nocheck(x, ptr, size)                      \
 274 ({                                                              \
 275         long __gu_err;                                          \
 276         long long __gu_val;                                     \
 277         __chk_user_ptr(ptr);                                    \
 278         might_sleep();                                          \
 279         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 280         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 281         __gu_err;                                               \
 282 })
 283 #endif /* __powerpc64__ */
 284
 285 #define __get_user_check(x, ptr, size)                                  \
 286 ({                                                                      \
 287         long __gu_err = -EFAULT;                                        \
 288         unsigned long  __gu_val = 0;                                    \
 289         const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
 290         might_sleep();                                                  \
 291         if (access_ok(VERIFY_READ, __gu_addr, (size)))                  \
 292                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 293         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 294         __gu_err;                                                       \
 295 })
 296
 297 /* more complex routines */
 298
 299 extern unsigned long __copy_tofrom_user(void __user *to,
 300                 const void __user *from, unsigned long size);
 301
 302 #ifndef __powerpc64__
 303
 304 extern inline unsigned long copy_from_user(void *to,
 305                 const void __user *from, unsigned long n)
 306 {
 307         unsigned long over;
 308
 309         if (access_ok(VERIFY_READ, from, n))
 310                 return __copy_tofrom_user((__force void __user *)to, from, n);
 311         if ((unsigned long)from < TASK_SIZE) {
 312                 over = (unsigned long)from + n - TASK_SIZE;
 313                 return __copy_tofrom_user((__force void __user *)to, from,
 314                                 n - over) + over;
 315         }
 316         return n;
 317 }
 318
 319 extern inline unsigned long copy_to_user(void __user *to,
 320                 const void *from, unsigned long n)
 321 {
 322         unsigned long over;
 323
 324         if (access_ok(VERIFY_WRITE, to, n))
 325                 return __copy_tofrom_user(to, (__force void __user *)from, n);
 326         if ((unsigned long)to < TASK_SIZE) {
 327                 over = (unsigned long)to + n - TASK_SIZE;
 328                 return __copy_tofrom_user(to, (__force void __user *)from,
 329                                 n - over) + over;
 330         }
 331         return n;
 332 }
 333
 334 #else /* __powerpc64__ */
 335
 336 #define __copy_in_user(to, from, size) \
 337         __copy_tofrom_user((to), (from), (size))
 338
 339 extern unsigned long copy_from_user(void *to, const void __user *from,
 340                                     unsigned long n);
 341 extern unsigned long copy_to_user(void __user *to, const void *from,
 342                                   unsigned long n);
 343 extern unsigned long copy_in_user(void __user *to, const void __user *from,
 344                                   unsigned long n);
 345
 346 #endif /* __powerpc64__ */
 347
 348 static inline unsigned long __copy_from_user_inatomic(void *to,
 349                 const void __user *from, unsigned long n)
 350 {
 351         if (__builtin_constant_p(n) && (n <= 8)) {
 352                 unsigned long ret;
 353
 354                 switch (n) {
 355                 case 1:
 356                         __get_user_size(*(u8 *)to, from, 1, ret);
 357                         break;
 358                 case 2:
 359                         __get_user_size(*(u16 *)to, from, 2, ret);
 360                         break;
 361                 case 4:
 362                         __get_user_size(*(u32 *)to, from, 4, ret);
 363                         break;
 364                 case 8:
 365                         __get_user_size(*(u64 *)to, from, 8, ret);
 366                         break;
 367                 }
 368                 if (ret == 0)
 369                         return 0;
 370         }
 371         return __copy_tofrom_user((__force void __user *)to, from, n);
 372 }
 373
 374 static inline unsigned long __copy_to_user_inatomic(void __user *to,
 375                 const void *from, unsigned long n)
 376 {
 377         if (__builtin_constant_p(n) && (n <= 8)) {
 378                 unsigned long ret;
 379
 380                 switch (n) {
 381                 case 1:
 382                         __put_user_size(*(u8 *)from, (u8 __user *)to, 1, ret);
 383                         break;
 384                 case 2:
 385                         __put_user_size(*(u16 *)from, (u16 __user *)to, 2, ret);
 386                         break;
 387                 case 4:
 388                         __put_user_size(*(u32 *)from, (u32 __user *)to, 4, ret);
 389                         break;
 390                 case 8:
 391                         __put_user_size(*(u64 *)from, (u64 __user *)to, 8, ret);
 392                         break;
 393                 }
 394                 if (ret == 0)
 395                         return 0;
 396         }
 397         return __copy_tofrom_user(to, (__force const void __user *)from, n);
 398 }
 399
 400 static inline unsigned long __copy_from_user(void *to,
 401                 const void __user *from, unsigned long size)
 402 {
 403         might_sleep();
 404         return __copy_from_user_inatomic(to, from, size);
 405 }
 406
 407 static inline unsigned long __copy_to_user(void __user *to,
 408                 const void *from, unsigned long size)
 409 {
 410         might_sleep();
 411         return __copy_to_user_inatomic(to, from, size);
 412 }
 413
 414 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 415
 416 static inline unsigned long clear_user(void __user *addr, unsigned long size)
 417 {
 418         might_sleep();
 419         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 420                 return __clear_user(addr, size);
 421         if ((unsigned long)addr < TASK_SIZE) {
 422                 unsigned long over = (unsigned long)addr + size - TASK_SIZE;
 423                 return __clear_user(addr, size - over) + over;
 424         }
 425         return size;
 426 }
 427
 428 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
 429
 430 static inline long strncpy_from_user(char *dst, const char __user *src,
 431                 long count)
 432 {
 433         might_sleep();
 434         if (likely(access_ok(VERIFY_READ, src, 1)))
 435                 return __strncpy_from_user(dst, src, count);
 436         return -EFAULT;
 437 }
 438
 439 /*
 440  * Return the size of a string (including the ending 0)
 441  *
 442  * Return 0 for error
 443  */
 444 extern int __strnlen_user(const char __user *str, long len, unsigned long top);
 445
 446 /*
 447  * Returns the length of the string at str (including the null byte),
 448  * or 0 if we hit a page we can't access,
 449  * or something > len if we didn't find a null byte.
 450  *
 451  * The `top' parameter to __strnlen_user is to make sure that
 452  * we can never overflow from the user area into kernel space.
 453  */
 454 static inline int strnlen_user(const char __user *str, long len)
 455 {
 456         unsigned long top = current->thread.fs.seg;
 457
 458         if ((unsigned long)str > top)
 459                 return 0;
 460         return __strnlen_user(str, len, top);
 461 }
 462
 463 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 464
 465 #endif  /* __ASSEMBLY__ */
 466 #endif /* __KERNEL__ */
 467
 468 #endif  /* _ARCH_POWERPC_UACCESS_H */