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 <asm/page.h>
  30
  31 #define VERIFY_READ     0
  32 #define VERIFY_WRITE    1
  33
  34 /*
  35  * The fs value determines whether argument validity checking should be
  36  * performed or not.  If get_fs() == USER_DS, checking is performed, with
  37  * get_fs() == KERNEL_DS, checking is bypassed.
  38  *
  39  * For historical reasons, these macros are grossly misnamed.
  40  */
  41
  42 /* addr_limit is the maximum accessible address for the task. we misuse
  43  * the KERNEL_DS and USER_DS values to both assign and compare the
  44  * addr_limit values through the equally misnamed get/set_fs macros.
  45  * (see above)
  46  */
  47
  48 #define KERNEL_DS       (~0UL)
  49 #define get_ds()        (KERNEL_DS)
  50
  51 #define USER_DS         (TASK_SIZE)
  52 #define get_fs()        (current_thread_info()->addr_limit)
  53 #define set_fs(x)       (current_thread_info()->addr_limit = (x))
  54
  55 #define segment_eq(a, b)        ((a) == (b))
  56
  57 /* Ensure that the range from addr to addr+size is all within the process'
  58  * address space
  59  */
  60 #define __range_ok(addr, size) (size <= get_fs() && addr <= (get_fs()-size))
  61
  62 /* Ensure that addr is below task's addr_limit */
  63 #define __addr_ok(addr) ((unsigned long) addr < get_fs())
  64
  65 #define access_ok(type, addr, size) \
  66         __range_ok((unsigned long)addr, (unsigned long)size)
  67
  68 /*
  69  * The exception table consists of pairs of addresses: the first is the
  70  * address of an instruction that is allowed to fault, and the second is
  71  * the address at which the program should continue.  No registers are
  72  * modified, so it is entirely up to the continuation code to figure out
  73  * what to do.
  74  *
  75  * All the routines below use bits of fixup code that are out of line
  76  * with the main instruction path.  This means when everything is well,
  77  * we don't even have to jump over them.  Further, they do not intrude
  78  * on our cache or tlb entries.
  79  */
  80
  81 struct exception_table_entry {
  82         unsigned long insn, fixup;
  83 };
  84
  85 /* Returns 0 if exception not found and fixup otherwise.  */
  86 extern unsigned long search_exception_table(unsigned long);
  87 extern void sort_exception_table(void);
  88
  89 /*
  90  * These are the main single-value transfer routines.  They automatically
  91  * use the right size if we just have the right pointer type.
  92  *
  93  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  94  * and yet we don't want to do any pointers, because that is too much
  95  * of a performance impact. Thus we have a few rather ugly macros here,
  96  * and hide all the uglyness from the user.
  97  *
  98  * The "__xxx" versions of the user access functions are versions that
  99  * do not verify the address space, that must have been done previously
 100  * with a separate "access_ok()" call (this is used when we do multiple
 101  * accesses to the same area of user memory).
 102  *
 103  * As we use the same address space for kernel and user data on the
 104  * PowerPC, we can just do these as direct assignments.  (Of course, the
 105  * exception handling means that it's no longer "just"...)
 106  */
 107 #define get_user(x, ptr) \
 108         __get_user_check((x), (ptr), sizeof(*(ptr)))
 109 #define put_user(x, ptr) \
 110         __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 111
 112 #define __get_user(x, ptr) \
 113         __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
 114 #define __put_user(x, ptr) \
 115         __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
 116
 117 extern long __put_user_bad(void);
 118
 119 #define __put_user_nocheck(x, ptr, size)                \
 120 ({                                                      \
 121         long __pu_err;                                  \
 122         __put_user_size((x), (ptr), (size), __pu_err);  \
 123         __pu_err;                                       \
 124 })
 125
 126 #define __put_user_check(x, ptr, size)                                  \
 127 ({                                                                      \
 128         long __pu_err = -EFAULT;                                        \
 129         __typeof__(*(ptr)) *__pu_addr = (ptr);                          \
 130         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
 131                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 132         __pu_err;                                                       \
 133 })
 134
 135 #define __put_user_size(x, ptr, size, retval)                           \
 136 do {                                                                    \
 137         retval = 0;                                                     \
 138         switch (size) {                                                 \
 139         case 1: __put_user_asm(x, ptr, retval, "l.sb"); break;          \
 140         case 2: __put_user_asm(x, ptr, retval, "l.sh"); break;          \
 141         case 4: __put_user_asm(x, ptr, retval, "l.sw"); break;          \
 142         case 8: __put_user_asm2(x, ptr, retval); break;                 \
 143         default: __put_user_bad();                                      \
 144         }                                                               \
 145 } while (0)
 146
 147 struct __large_struct {
 148         unsigned long buf[100];
 149 };
 150 #define __m(x) (*(struct __large_struct *)(x))
 151
 152 /*
 153  * We don't tell gcc that we are accessing memory, but this is OK
 154  * because we do not write to any memory gcc knows about, so there
 155  * are no aliasing issues.
 156  */
 157 #define __put_user_asm(x, addr, err, op)                        \
 158         __asm__ __volatile__(                                   \
 159                 "1:     "op" 0(%2),%1\n"                        \
 160                 "2:\n"                                          \
 161                 ".section .fixup,\"ax\"\n"                      \
 162                 "3:     l.addi %0,r0,%3\n"                      \
 163                 "       l.j 2b\n"                               \
 164                 "       l.nop\n"                                \
 165                 ".previous\n"                                   \
 166                 ".section __ex_table,\"a\"\n"                   \
 167                 "       .align 2\n"                             \
 168                 "       .long 1b,3b\n"                          \
 169                 ".previous"                                     \
 170                 : "=r"(err)                                     \
 171                 : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
 172
 173 #define __put_user_asm2(x, addr, err)                           \
 174         __asm__ __volatile__(                                   \
 175                 "1:     l.sw 0(%2),%1\n"                        \
 176                 "2:     l.sw 4(%2),%H1\n"                       \
 177                 "3:\n"                                          \
 178                 ".section .fixup,\"ax\"\n"                      \
 179                 "4:     l.addi %0,r0,%3\n"                      \
 180                 "       l.j 3b\n"                               \
 181                 "       l.nop\n"                                \
 182                 ".previous\n"                                   \
 183                 ".section __ex_table,\"a\"\n"                   \
 184                 "       .align 2\n"                             \
 185                 "       .long 1b,4b\n"                          \
 186                 "       .long 2b,4b\n"                          \
 187                 ".previous"                                     \
 188                 : "=r"(err)                                     \
 189                 : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
 190
 191 #define __get_user_nocheck(x, ptr, size)                        \
 192 ({                                                              \
 193         long __gu_err, __gu_val;                                \
 194         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 195         (x) = (__force __typeof__(*(ptr)))__gu_val;             \
 196         __gu_err;                                               \
 197 })
 198
 199 #define __get_user_check(x, ptr, size)                                  \
 200 ({                                                                      \
 201         long __gu_err = -EFAULT, __gu_val = 0;                          \
 202         const __typeof__(*(ptr)) * __gu_addr = (ptr);                   \
 203         if (access_ok(VERIFY_READ, __gu_addr, size))                    \
 204                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 205         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 206         __gu_err;                                                       \
 207 })
 208
 209 extern long __get_user_bad(void);
 210
 211 #define __get_user_size(x, ptr, size, retval)                           \
 212 do {                                                                    \
 213         retval = 0;                                                     \
 214         switch (size) {                                                 \
 215         case 1: __get_user_asm(x, ptr, retval, "l.lbz"); break;         \
 216         case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break;         \
 217         case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break;         \
 218         case 8: __get_user_asm2(x, ptr, retval);                        \
 219         default: (x) = __get_user_bad();                                \
 220         }                                                               \
 221 } while (0)
 222
 223 #define __get_user_asm(x, addr, err, op)                \
 224         __asm__ __volatile__(                           \
 225                 "1:     "op" %1,0(%2)\n"                \
 226                 "2:\n"                                  \
 227                 ".section .fixup,\"ax\"\n"              \
 228                 "3:     l.addi %0,r0,%3\n"              \
 229                 "       l.addi %1,r0,0\n"               \
 230                 "       l.j 2b\n"                       \
 231                 "       l.nop\n"                        \
 232                 ".previous\n"                           \
 233                 ".section __ex_table,\"a\"\n"           \
 234                 "       .align 2\n"                     \
 235                 "       .long 1b,3b\n"                  \
 236                 ".previous"                             \
 237                 : "=r"(err), "=r"(x)                    \
 238                 : "r"(addr), "i"(-EFAULT), "0"(err))
 239
 240 #define __get_user_asm2(x, addr, err)                   \
 241         __asm__ __volatile__(                           \
 242                 "1:     l.lwz %1,0(%2)\n"               \
 243                 "2:     l.lwz %H1,4(%2)\n"              \
 244                 "3:\n"                                  \
 245                 ".section .fixup,\"ax\"\n"              \
 246                 "4:     l.addi %0,r0,%3\n"              \
 247                 "       l.addi %1,r0,0\n"               \
 248                 "       l.addi %H1,r0,0\n"              \
 249                 "       l.j 3b\n"                       \
 250                 "       l.nop\n"                        \
 251                 ".previous\n"                           \
 252                 ".section __ex_table,\"a\"\n"           \
 253                 "       .align 2\n"                     \
 254                 "       .long 1b,4b\n"                  \
 255                 "       .long 2b,4b\n"                  \
 256                 ".previous"                             \
 257                 : "=r"(err), "=&r"(x)                   \
 258                 : "r"(addr), "i"(-EFAULT), "0"(err))
 259
 260 /* more complex routines */
 261
 262 extern unsigned long __must_check
 263 __copy_tofrom_user(void *to, const void *from, unsigned long size);
 264
 265 #define __copy_from_user(to, from, size) \
 266         __copy_tofrom_user(to, from, size)
 267 #define __copy_to_user(to, from, size) \
 268         __copy_tofrom_user(to, from, size)
 269
 270 #define __copy_to_user_inatomic __copy_to_user
 271 #define __copy_from_user_inatomic __copy_from_user
 272
 273 static inline unsigned long
 274 copy_from_user(void *to, const void *from, unsigned long n)
 275 {
 276         unsigned long res = n;
 277
 278         if (likely(access_ok(VERIFY_READ, from, n)))
 279                 n = __copy_tofrom_user(to, from, n);
 280         if (unlikely(res))
 281                 memset(to + (n - res), 0, res);
 282         return res;
 283 }
 284
 285 static inline unsigned long
 286 copy_to_user(void *to, const void *from, unsigned long n)
 287 {
 288         if (likely(access_ok(VERIFY_WRITE, to, n)))
 289                 n = __copy_tofrom_user(to, from, n);
 290         return n;
 291 }
 292
 293 extern unsigned long __clear_user(void *addr, unsigned long size);
 294
 295 static inline __must_check unsigned long
 296 clear_user(void *addr, unsigned long size)
 297 {
 298         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 299                 size = __clear_user(addr, size);
 300         return size;
 301 }
 302
 303 #define user_addr_max() \
 304         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
 305
 306 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 307
 308 extern __must_check long strlen_user(const char __user *str);
 309 extern __must_check long strnlen_user(const char __user *str, long n);
 310
 311 #endif /* __ASM_OPENRISC_UACCESS_H */