include/asm-ppc/uaccess.h

   1 #ifdef __KERNEL__
   2 #ifndef _PPC_UACCESS_H
   3 #define _PPC_UACCESS_H
   4
   5 #ifndef __ASSEMBLY__
   6 #include <linux/sched.h>
   7 #include <linux/errno.h>
   8 #include <asm/processor.h>
   9
  10 #define VERIFY_READ     0
  11 #define VERIFY_WRITE    1
  12
  13 /*
  14  * The fs value determines whether argument validity checking should be
  15  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  16  * get_fs() == KERNEL_DS, checking is bypassed.
  17  *
  18  * For historical reasons, these macros are grossly misnamed.
  19  *
  20  * The fs/ds values are now the highest legal address in the "segment".
  21  * This simplifies the checking in the routines below.
  22  */
  23
  24 #define KERNEL_DS       ((mm_segment_t) { ~0UL })
  25 #define USER_DS         ((mm_segment_t) { TASK_SIZE - 1 })
  26
  27 #define get_ds()        (KERNEL_DS)
  28 #define get_fs()        (current->thread.fs)
  29 #define set_fs(val)     (current->thread.fs = (val))
  30
  31 #define segment_eq(a,b) ((a).seg == (b).seg)
  32
  33 #define __access_ok(addr,size)                                              \
  34         ((addr) <= current->thread.fs.seg                                   \
  35          && ((size) == 0 || (size) - 1 <= current->thread.fs.seg - (addr)))
  36
  37 #define access_ok(type, addr, size) __access_ok((unsigned long)(addr),(size))
  38
  39 extern inline int verify_area(int type, const void __user * addr, unsigned long size)
  40 {
  41         return access_ok(type, addr, size) ? 0 : -EFAULT;
  42 }
  43
  44
  45 /*
  46  * The exception table consists of pairs of addresses: the first is the
  47  * address of an instruction that is allowed to fault, and the second is
  48  * the address at which the program should continue.  No registers are
  49  * modified, so it is entirely up to the continuation code to figure out
  50  * what to do.
  51  *
  52  * All the routines below use bits of fixup code that are out of line
  53  * with the main instruction path.  This means when everything is well,
  54  * we don't even have to jump over them.  Further, they do not intrude
  55  * on our cache or tlb entries.
  56  */
  57
  58 struct exception_table_entry
  59 {
  60         unsigned long insn, fixup;
  61 };
  62
  63 /*
  64  * These are the main single-value transfer routines.  They automatically
  65  * use the right size if we just have the right pointer type.
  66  *
  67  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  68  * and yet we don't want to do any pointers, because that is too much
  69  * of a performance impact. Thus we have a few rather ugly macros here,
  70  * and hide all the ugliness from the user.
  71  *
  72  * The "__xxx" versions of the user access functions are versions that
  73  * do not verify the address space, that must have been done previously
  74  * with a separate "access_ok()" call (this is used when we do multiple
  75  * accesses to the same area of user memory).
  76  *
  77  * As we use the same address space for kernel and user data on the
  78  * PowerPC, we can just do these as direct assignments.  (Of course, the
  79  * exception handling means that it's no longer "just"...)
  80  *
  81  * The "user64" versions of the user access functions are versions that
  82  * allow access of 64-bit data. The "get_user" functions do not
  83  * properly handle 64-bit data because the value gets down cast to a long.
  84  * The "put_user" functions already handle 64-bit data properly but we add
  85  * "user64" versions for completeness
  86  */
  87 #define get_user(x,ptr) \
  88   __get_user_check((x),(ptr),sizeof(*(ptr)))
  89 #define get_user64(x,ptr) \
  90   __get_user64_check((x),(ptr),sizeof(*(ptr)))
  91 #define put_user(x,ptr) \
  92   __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
  93 #define put_user64(x,ptr) put_user(x,ptr)
  94
  95 #define __get_user(x,ptr) \
  96   __get_user_nocheck((x),(ptr),sizeof(*(ptr)))
  97 #define __get_user64(x,ptr) \
  98   __get_user64_nocheck((x),(ptr),sizeof(*(ptr)))
  99 #define __put_user(x,ptr) \
 100   __put_user_nocheck((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)))
 101 #define __put_user64(x,ptr) __put_user(x,ptr)
 102
 103 extern long __put_user_bad(void);
 104
 105 #define __put_user_nocheck(x,ptr,size)                  \
 106 ({                                                      \
 107         long __pu_err;                                  \
 108         __put_user_size((x),(ptr),(size),__pu_err);     \
 109         __pu_err;                                       \
 110 })
 111
 112 #define __put_user_check(x,ptr,size)                            \
 113 ({                                                              \
 114         long __pu_err = -EFAULT;                                \
 115         __typeof__(*(ptr)) *__pu_addr = (ptr);                  \
 116         if (access_ok(VERIFY_WRITE,__pu_addr,size))             \
 117                 __put_user_size((x),__pu_addr,(size),__pu_err); \
 118         __pu_err;                                               \
 119 })
 120
 121 #define __put_user_size(x,ptr,size,retval)              \
 122 do {                                                    \
 123         retval = 0;                                     \
 124         switch (size) {                                 \
 125         case 1:                                         \
 126                 __put_user_asm(x, ptr, retval, "stb");  \
 127                 break;                                  \
 128         case 2:                                         \
 129                 __put_user_asm(x, ptr, retval, "sth");  \
 130                 break;                                  \
 131         case 4:                                         \
 132                 __put_user_asm(x, ptr, retval, "stw");  \
 133                 break;                                  \
 134         case 8:                                         \
 135                 __put_user_asm2(x, ptr, retval);        \
 136                 break;                                  \
 137         default:                                        \
 138                 __put_user_bad();                       \
 139         }                                               \
 140 } while (0)
 141
 142 /*
 143  * We don't tell gcc that we are accessing memory, but this is OK
 144  * because we do not write to any memory gcc knows about, so there
 145  * are no aliasing issues.
 146  */
 147 #define __put_user_asm(x, addr, err, op)                        \
 148         __asm__ __volatile__(                                   \
 149                 "1:     "op" %1,0(%2)\n"                        \
 150                 "2:\n"                                          \
 151                 ".section .fixup,\"ax\"\n"                      \
 152                 "3:     li %0,%3\n"                             \
 153                 "       b 2b\n"                                 \
 154                 ".previous\n"                                   \
 155                 ".section __ex_table,\"a\"\n"                   \
 156                 "       .align 2\n"                             \
 157                 "       .long 1b,3b\n"                          \
 158                 ".previous"                                     \
 159                 : "=r" (err)                                    \
 160                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 161
 162 #define __put_user_asm2(x, addr, err)                           \
 163         __asm__ __volatile__(                                   \
 164                 "1:     stw %1,0(%2)\n"                         \
 165                 "2:     stw %1+1,4(%2)\n"                       \
 166                 "3:\n"                                          \
 167                 ".section .fixup,\"ax\"\n"                      \
 168                 "4:     li %0,%3\n"                             \
 169                 "       b 3b\n"                                 \
 170                 ".previous\n"                                   \
 171                 ".section __ex_table,\"a\"\n"                   \
 172                 "       .align 2\n"                             \
 173                 "       .long 1b,4b\n"                          \
 174                 "       .long 2b,4b\n"                          \
 175                 ".previous"                                     \
 176                 : "=r" (err)                                    \
 177                 : "r" (x), "b" (addr), "i" (-EFAULT), "0" (err))
 178
 179 #define __get_user_nocheck(x, ptr, size)                        \
 180 ({                                                              \
 181         long __gu_err, __gu_val;                                \
 182         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 183         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 184         __gu_err;                                               \
 185 })
 186
 187 #define __get_user64_nocheck(x, ptr, size)                      \
 188 ({                                                              \
 189         long __gu_err;                                          \
 190         long long __gu_val;                                     \
 191         __get_user_size64(__gu_val, (ptr), (size), __gu_err);   \
 192         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 193         __gu_err;                                               \
 194 })
 195
 196 #define __get_user_check(x, ptr, size)                                  \
 197 ({                                                                      \
 198         long __gu_err = -EFAULT, __gu_val = 0;                          \
 199         const __typeof__(*(ptr)) *__gu_addr = (ptr);                    \
 200         if (access_ok(VERIFY_READ, __gu_addr, (size)))                  \
 201                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 202         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 203         __gu_err;                                                       \
 204 })
 205
 206 #define __get_user64_check(x, ptr, size)                                  \
 207 ({                                                                        \
 208         long __gu_err = -EFAULT;                                          \
 209         long long __gu_val = 0;                                           \
 210         const __typeof__(*(ptr)) *__gu_addr = (ptr);                      \
 211         if (access_ok(VERIFY_READ, __gu_addr, (size)))                    \
 212                 __get_user_size64(__gu_val, __gu_addr, (size), __gu_err); \
 213         (x) = (__typeof__(*(ptr)))__gu_val;                               \
 214         __gu_err;                                                         \
 215 })
 216
 217 extern long __get_user_bad(void);
 218
 219 #define __get_user_size(x, ptr, size, retval)                   \
 220 do {                                                            \
 221         retval = 0;                                             \
 222         switch (size) {                                         \
 223         case 1:                                                 \
 224                 __get_user_asm(x, ptr, retval, "lbz");          \
 225                 break;                                          \
 226         case 2:                                                 \
 227                 __get_user_asm(x, ptr, retval, "lhz");          \
 228                 break;                                          \
 229         case 4:                                                 \
 230                 __get_user_asm(x, ptr, retval, "lwz");          \
 231                 break;                                          \
 232         default:                                                \
 233                 x = __get_user_bad();                           \
 234         }                                                       \
 235 } while (0)
 236
 237 #define __get_user_size64(x, ptr, size, retval)                 \
 238 do {                                                            \
 239         retval = 0;                                             \
 240         switch (size) {                                         \
 241         case 1:                                                 \
 242                 __get_user_asm(x, ptr, retval, "lbz");          \
 243                 break;                                          \
 244         case 2:                                                 \
 245                 __get_user_asm(x, ptr, retval, "lhz");          \
 246                 break;                                          \
 247         case 4:                                                 \
 248                 __get_user_asm(x, ptr, retval, "lwz");          \
 249                 break;                                          \
 250         case 8:                                                 \
 251                 __get_user_asm2(x, ptr, retval);                \
 252                 break;                                          \
 253         default:                                                \
 254                 x = __get_user_bad();                           \
 255         }                                                       \
 256 } while (0)
 257
 258 #define __get_user_asm(x, addr, err, op)                \
 259         __asm__ __volatile__(                           \
 260                 "1:     "op" %1,0(%2)\n"                \
 261                 "2:\n"                                  \
 262                 ".section .fixup,\"ax\"\n"              \
 263                 "3:     li %0,%3\n"                     \
 264                 "       li %1,0\n"                      \
 265                 "       b 2b\n"                         \
 266                 ".previous\n"                           \
 267                 ".section __ex_table,\"a\"\n"           \
 268                 "       .align 2\n"                     \
 269                 "       .long 1b,3b\n"                  \
 270                 ".previous"                             \
 271                 : "=r"(err), "=r"(x)                    \
 272                 : "b"(addr), "i"(-EFAULT), "0"(err))
 273
 274 #define __get_user_asm2(x, addr, err)                   \
 275         __asm__ __volatile__(                           \
 276                 "1:     lwz %1,0(%2)\n"                 \
 277                 "2:     lwz %1+1,4(%2)\n"               \
 278                 "3:\n"                                  \
 279                 ".section .fixup,\"ax\"\n"              \
 280                 "4:     li %0,%3\n"                     \
 281                 "       li %1,0\n"                      \
 282                 "       li %1+1,0\n"                    \
 283                 "       b 3b\n"                         \
 284                 ".previous\n"                           \
 285                 ".section __ex_table,\"a\"\n"           \
 286                 "       .align 2\n"                     \
 287                 "       .long 1b,4b\n"                  \
 288                 "       .long 2b,4b\n"                  \
 289                 ".previous"                             \
 290                 : "=r"(err), "=&r"(x)                   \
 291                 : "b"(addr), "i"(-EFAULT), "0"(err))
 292
 293 /* more complex routines */
 294
 295 extern int __copy_tofrom_user(void __user *to, const void __user *from,
 296                               unsigned long size);
 297
 298 extern inline unsigned long
 299 copy_from_user(void *to, const void __user *from, unsigned long n)
 300 {
 301         unsigned long over;
 302
 303         if (access_ok(VERIFY_READ, from, n))
 304                 return __copy_tofrom_user((void __user *)to, from, n);
 305         if ((unsigned long)from < TASK_SIZE) {
 306                 over = (unsigned long)from + n - TASK_SIZE;
 307                 return __copy_tofrom_user((void __user *)to, from, n - over) + over;
 308         }
 309         return n;
 310 }
 311
 312 extern inline unsigned long
 313 copy_to_user(void __user *to, const void *from, unsigned long n)
 314 {
 315         unsigned long over;
 316
 317         if (access_ok(VERIFY_WRITE, to, n))
 318                 return __copy_tofrom_user(to, (void __user *) from, n);
 319         if ((unsigned long)to < TASK_SIZE) {
 320                 over = (unsigned long)to + n - TASK_SIZE;
 321                 return __copy_tofrom_user(to, (void __user *) from, n - over) + over;
 322         }
 323         return n;
 324 }
 325
 326 #define __copy_from_user(to, from, size) \
 327         __copy_tofrom_user((void __user *)(to), (from), (size))
 328 #define __copy_to_user(to, from, size) \
 329         __copy_tofrom_user((to), (void __user *)(from), (size))
 330
 331 extern unsigned long __clear_user(void __user *addr, unsigned long size);
 332
 333 extern inline unsigned long
 334 clear_user(void __user *addr, unsigned long size)
 335 {
 336         if (access_ok(VERIFY_WRITE, addr, size))
 337                 return __clear_user(addr, size);
 338         if ((unsigned long)addr < TASK_SIZE) {
 339                 unsigned long over = (unsigned long)addr + size - TASK_SIZE;
 340                 return __clear_user(addr, size - over) + over;
 341         }
 342         return size;
 343 }
 344
 345 extern int __strncpy_from_user(char *dst, const char __user *src, long count);
 346
 347 extern inline long
 348 strncpy_from_user(char *dst, const char __user *src, long count)
 349 {
 350         if (access_ok(VERIFY_READ, src, 1))
 351                 return __strncpy_from_user(dst, src, count);
 352         return -EFAULT;
 353 }
 354
 355 /*
 356  * Return the size of a string (including the ending 0)
 357  *
 358  * Return 0 for error
 359  */
 360
 361 extern int __strnlen_user(const char __user *str, long len, unsigned long top);
 362
 363 /*
 364  * Returns the length of the string at str (including the null byte),
 365  * or 0 if we hit a page we can't access,
 366  * or something > len if we didn't find a null byte.
 367  *
 368  * The `top' parameter to __strnlen_user is to make sure that
 369  * we can never overflow from the user area into kernel space.
 370  */
 371 extern __inline__ int strnlen_user(const char __user *str, long len)
 372 {
 373         unsigned long top = current->thread.fs.seg;
 374
 375         if ((unsigned long)str > top)
 376                 return 0;
 377         return __strnlen_user(str, len, top);
 378 }
 379
 380 #define strlen_user(str)        strnlen_user((str), 0x7ffffffe)
 381
 382 #endif  /* __ASSEMBLY__ */
 383
 384 #endif  /* _PPC_UACCESS_H */
 385 #endif /* __KERNEL__ */