arch/openrisc/include/asm/uaccess.h

   1 /*
   2  * OpenRISC Linux
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * OpenRISC implementation:
   9  * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
  10  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  11  * et al.
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  */
  18
  19 #ifndef __ASM_OPENRISC_UACCESS_H
  20 #define __ASM_OPENRISC_UACCESS_H
  21
  22 /*
  23  * User space memory access functions
  24  */
  25 #include <linux/errno.h>
  26 #include <linux/thread_info.h>
  27 #include <linux/prefetch.h>
  28 #include <linux/string.h>
  29 #include <linux/thread_info.h>
  30 #include <asm/page.h>
  31
  32 #define VERIFY_READ     0
  33 #define VERIFY_WRITE    1
  34
  35 /*
  36  * The fs value determines whether argument validity checking should be
  37  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  38  * get_fs() == KERNEL_DS, checking is bypassed.
  39  *
  40  * For historical reasons, these macros are grossly misnamed.
  41  */
  42
  43 /* addr_limit is the maximum accessible address for the task. we misuse
  44  * the KERNEL_DS and USER_DS values to both assign and compare the
  45  * addr_limit values through the equally misnamed get/set_fs macros.
  46  * (see above)
  47  */
  48
  49 #define KERNEL_DS       (~0UL)
  50 #define get_ds()        (KERNEL_DS)
  51
  52 #define USER_DS         (TASK_SIZE)
  53 #define get_fs()        (current_thread_info()->addr_limit)
  54 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  55
  56 #define segment_eq(a, b)        ((a) == (b))
  57
  58 /* Ensure that the range from addr to addr+size is all within the process'
  59  * address space
  60  */
  61 #define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs()-size))
  62
  63 /* Ensure that addr is below task's addr_limit */
  64 #define __addr_ok(addr) ((unsigned long) addr < get_fs())
  65
  66 #define access_ok(type, addr, size) \
  67         __range_ok((unsigned long)addr, (unsigned long)size)
  68
  69 /*
  70  * The exception table consists of pairs of addresses: the first is the
  71  * address of an instruction that is allowed to fault, and the second is
  72  * the address at which the program should continue.  No registers are
  73  * modified, so it is entirely up to the continuation code to figure out
  74  * what to do.
  75  *
  76  * All the routines below use bits of fixup code that are out of line
  77  * with the main instruction path.  This means when everything is well,
  78  * we don't even have to jump over them.  Further, they do not intrude
  79  * on our cache or tlb entries.
  80  */
  81
  82 struct exception_table_entry {
  83         unsigned long insn, fixup;
  84 };
  85
  86 /* Returns 0 if exception not found and fixup otherwise.  */
  87 extern unsigned long search_exception_table(unsigned long);
  88 extern void sort_exception_table(void);
  89
  90 /*
  91  * These are the main single-value transfer routines.  They automatically
  92  * use the right size if we just have the right pointer type.
  93  *
  94  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  95  * and yet we don't want to do any pointers, because that is too much
  96  * of a performance impact. Thus we have a few rather ugly macros here,
  97  * and hide all the uglyness from the user.
  98  *
  99  * The "__xxx" versions of the user access functions are versions that
 100  * do not verify the address space, that must have been done previously
 101  * with a separate "access_ok()" call (this is used when we do multiple
 102  * accesses to the same area of user memory).
 103  *
 104  * As we use the same address space for kernel and user data on the
 105  * PowerPC, we can just do these as direct assignments.  (Of course, the
 106  * exception handling means that it's no longer "just"...)
 107  */
 108 #define get_user(x, ptr) \
 109         __get_user_check((x), (ptr), sizeof(*(ptr)))
 110 #define put_user(x, ptr) \
 111         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 112
 113 #define __get_user(x, ptr) \
 114         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 115 #define __put_user(x, ptr) \
 116         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 117
 118 extern long __put_user_bad(void);
 119
 120 #define __put_user_nocheck(x, ptr, size)                \
 121 ({                                                      \
 122         long __pu_err;                                  \
 123         __put_user_size((x), (ptr), (size), __pu_err);  \
 124         __pu_err;                                       \
 125 })
 126
 127 #define __put_user_check(x, ptr, size)                                  \
 128 ({                                                                      \
 129         long __pu_err = -EFAULT;                                        \
 130         __typeof__(*(ptr)) *__pu_addr = (ptr);                          \
 131         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
 132                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 133         __pu_err;                                                       \
 134 })
 135
 136 #define __put_user_size(x, ptr, size, retval)                           \
 137 do {                                                                    \
 138         retval = 0;                                                     \
 139         switch (size) {                                                 \
 140         case 1: __put_user_asm(x, ptr, retval, "l.sb"); break;          \
 141         case 2: __put_user_asm(x, ptr, retval, "l.sh"); break;          \
 142         case 4: __put_user_asm(x, ptr, retval, "l.sw"); break;          \
 143         case 8: __put_user_asm2(x, ptr, retval); break;                 \
 144         default: __put_user_bad();                                      \
 145         }                                                               \
 146 } while (0)
 147
 148 struct __large_struct {
 149         unsigned long buf[100];
 150 };
 151 #define __m(x) (*(struct __large_struct *)(x))
 152
 153 /*
 154  * We don't tell gcc that we are accessing memory, but this is OK
 155  * because we do not write to any memory gcc knows about, so there
 156  * are no aliasing issues.
 157  */
 158 #define __put_user_asm(x, addr, err, op)                        \
 159         __asm__ __volatile__(                                   \
 160                 "1:     "op" 0(%2),%1\n"                        \
 161                 "2:\n"                                          \
 162                 ".section .fixup,\"ax\"\n"                      \
 163                 "3:     l.addi %0,r0,%3\n"                      \
 164                 "       l.j 2b\n"                               \
 165                 "       l.nop\n"                                \
 166                 ".previous\n"                                   \
 167                 ".section __ex_table,\"a\"\n"                   \
 168                 "       .align 2\n"                             \
 169                 "       .long 1b,3b\n"                          \
 170                 ".previous"                                     \
 171                 : "=r"(err)                                     \
 172                 : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
 173
 174 #define __put_user_asm2(x, addr, err)                           \
 175         __asm__ __volatile__(                                   \
 176                 "1:     l.sw 0(%2),%1\n"                        \
 177                 "2:     l.sw 4(%2),%H1\n"                       \
 178                 "3:\n"                                          \
 179                 ".section .fixup,\"ax\"\n"                      \
 180                 "4:     l.addi %0,r0,%3\n"                      \
 181                 "       l.j 3b\n"                               \
 182                 "       l.nop\n"                                \
 183                 ".previous\n"                                   \
 184                 ".section __ex_table,\"a\"\n"                   \
 185                 "       .align 2\n"                             \
 186                 "       .long 1b,4b\n"                          \
 187                 "       .long 2b,4b\n"                          \
 188                 ".previous"                                     \
 189                 : "=r"(err)                                     \
 190                 : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
 191
 192 #define __get_user_nocheck(x, ptr, size)                        \
 193 ({                                                              \
 194         long __gu_err, __gu_val;                                \
 195         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 196         (x) = (__typeof__(*(ptr)))__gu_val;                     \
 197         __gu_err;                                               \
 198 })
 199
 200 #define __get_user_check(x, ptr, size)                                  \
 201 ({                                                                      \
 202         long __gu_err = -EFAULT, __gu_val = 0;                          \
 203         const __typeof__(*(ptr)) * __gu_addr = (ptr);                   \
 204         if (access_ok(VERIFY_READ, __gu_addr, size))                    \
 205                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 206         (x) = (__typeof__(*(ptr)))__gu_val;                             \
 207         __gu_err;                                                       \
 208 })
 209
 210 extern long __get_user_bad(void);
 211
 212 #define __get_user_size(x, ptr, size, retval)                           \
 213 do {                                                                    \
 214         retval = 0;                                                     \
 215         switch (size) {                                                 \
 216         case 1: __get_user_asm(x, ptr, retval, "l.lbz"); break;         \
 217         case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break;         \
 218         case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break;         \
 219         case 8: __get_user_asm2(x, ptr, retval);                        \
 220         default: (x) = __get_user_bad();                                \
 221         }                                                               \
 222 } while (0)
 223
 224 #define __get_user_asm(x, addr, err, op)                \
 225         __asm__ __volatile__(                           \
 226                 "1:     "op" %1,0(%2)\n"                \
 227                 "2:\n"                                  \
 228                 ".section .fixup,\"ax\"\n"              \
 229                 "3:     l.addi %0,r0,%3\n"              \
 230                 "       l.addi %1,r0,0\n"               \
 231                 "       l.j 2b\n"                       \
 232                 "       l.nop\n"                        \
 233                 ".previous\n"                           \
 234                 ".section __ex_table,\"a\"\n"           \
 235                 "       .align 2\n"                     \
 236                 "       .long 1b,3b\n"                  \
 237                 ".previous"                             \
 238                 : "=r"(err), "=r"(x)                    \
 239                 : "r"(addr), "i"(-EFAULT), "0"(err))
 240
 241 #define __get_user_asm2(x, addr, err)                   \
 242         __asm__ __volatile__(                           \
 243                 "1:     l.lwz %1,0(%2)\n"               \
 244                 "2:     l.lwz %H1,4(%2)\n"              \
 245                 "3:\n"                                  \
 246                 ".section .fixup,\"ax\"\n"              \
 247                 "4:     l.addi %0,r0,%3\n"              \
 248                 "       l.addi %1,r0,0\n"               \
 249                 "       l.addi %H1,r0,0\n"              \
 250                 "       l.j 3b\n"                       \
 251                 "       l.nop\n"                        \
 252                 ".previous\n"                           \
 253                 ".section __ex_table,\"a\"\n"           \
 254                 "       .align 2\n"                     \
 255                 "       .long 1b,4b\n"                  \
 256                 "       .long 2b,4b\n"                  \
 257                 ".previous"                             \
 258                 : "=r"(err), "=&r"(x)                   \
 259                 : "r"(addr), "i"(-EFAULT), "0"(err))
 260
 261 /* more complex routines */
 262
 263 extern unsigned long __must_check
 264 __copy_tofrom_user(void *to, const void *from, unsigned long size);
 265
 266 #define __copy_from_user(to, from, size) \
 267         __copy_tofrom_user(to, from, size)
 268 #define __copy_to_user(to, from, size) \
 269         __copy_tofrom_user(to, from, size)
 270
 271 #define __copy_to_user_inatomic __copy_to_user
 272 #define __copy_from_user_inatomic __copy_from_user
 273
 274 static inline unsigned long
 275 copy_from_user(void *to, const void *from, unsigned long n)
 276 {
 277         unsigned long over;
 278
 279         if (access_ok(VERIFY_READ, from, n))
 280                 return __copy_tofrom_user(to, from, n);
 281         if ((unsigned long)from < TASK_SIZE) {
 282                 over = (unsigned long)from + n - TASK_SIZE;
 283                 return __copy_tofrom_user(to, from, n - over) + over;
 284         }
 285         return n;
 286 }
 287
 288 static inline unsigned long
 289 copy_to_user(void *to, const void *from, unsigned long n)
 290 {
 291         unsigned long over;
 292
 293         if (access_ok(VERIFY_WRITE, to, n))
 294                 return __copy_tofrom_user(to, from, n);
 295         if ((unsigned long)to < TASK_SIZE) {
 296                 over = (unsigned long)to + n - TASK_SIZE;
 297                 return __copy_tofrom_user(to, from, n - over) + over;
 298         }
 299         return n;
 300 }
 301
 302 extern unsigned long __clear_user(void *addr, unsigned long size);
 303
 304 static inline __must_check unsigned long
 305 clear_user(void *addr, unsigned long size)
 306 {
 307
 308         if (access_ok(VERIFY_WRITE, addr, size))
 309                 return __clear_user(addr, size);
 310         if ((unsigned long)addr < TASK_SIZE) {
 311                 unsigned long over = (unsigned long)addr + size - TASK_SIZE;
 312                 return __clear_user(addr, size - over) + over;
 313         }
 314         return size;
 315 }
 316
 317 extern int __strncpy_from_user(char *dst, const char *src, long count);
 318
 319 static inline long strncpy_from_user(char *dst, const char *src, long count)
 320 {
 321         if (access_ok(VERIFY_READ, src, 1))
 322                 return __strncpy_from_user(dst, src, count);
 323         return -EFAULT;
 324 }
 325
 326 /*
 327  * Return the size of a string (including the ending 0)
 328  *
 329  * Return 0 for error
 330  */
 331
 332 extern int __strnlen_user(const char *str, long len, unsigned long top);
 333
 334 /*
 335  * Returns the length of the string at str (including the null byte),
 336  * or 0 if we hit a page we can't access,
 337  * or something > len if we didn't find a null byte.
 338  *
 339  * The `top' parameter to __strnlen_user is to make sure that
 340  * we can never overflow from the user area into kernel space.
 341  */
 342 static inline long strnlen_user(const char __user *str, long len)
 343 {
 344         unsigned long top = (unsigned long)get_fs();
 345         unsigned long res = 0;
 346
 347         if (__addr_ok(str))
 348                 res = __strnlen_user(str, len, top);
 349
 350         return res;
 351 }
 352
 353 #define strlen_user(str) strnlen_user(str, TASK_SIZE-1)
 354
 355 #endif /* __ASM_OPENRISC_UACCESS_H */