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 /*
  86  * These are the main single-value transfer routines.  They automatically
  87  * use the right size if we just have the right pointer type.
  88  *
  89  * This gets kind of ugly. We want to return _two_ values in "get_user()"
  90  * and yet we don't want to do any pointers, because that is too much
  91  * of a performance impact. Thus we have a few rather ugly macros here,
  92  * and hide all the uglyness from the user.
  93  *
  94  * The "__xxx" versions of the user access functions are versions that
  95  * do not verify the address space, that must have been done previously
  96  * with a separate "access_ok()" call (this is used when we do multiple
  97  * accesses to the same area of user memory).
  98  *
  99  * As we use the same address space for kernel and user data on the
 100  * PowerPC, we can just do these as direct assignments.  (Of course, the
 101  * exception handling means that it's no longer "just"...)
 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
 113 extern long __put_user_bad(void);
 114
 115 #define __put_user_nocheck(x, ptr, size)                \
 116 ({                                                      \
 117         long __pu_err;                                  \
 118         __put_user_size((x), (ptr), (size), __pu_err);  \
 119         __pu_err;                                       \
 120 })
 121
 122 #define __put_user_check(x, ptr, size)                                  \
 123 ({                                                                      \
 124         long __pu_err = -EFAULT;                                        \
 125         __typeof__(*(ptr)) *__pu_addr = (ptr);                          \
 126         if (access_ok(VERIFY_WRITE, __pu_addr, size))                   \
 127                 __put_user_size((x), __pu_addr, (size), __pu_err);      \
 128         __pu_err;                                                       \
 129 })
 130
 131 #define __put_user_size(x, ptr, size, retval)                           \
 132 do {                                                                    \
 133         retval = 0;                                                     \
 134         switch (size) {                                                 \
 135         case 1: __put_user_asm(x, ptr, retval, "l.sb"); break;          \
 136         case 2: __put_user_asm(x, ptr, retval, "l.sh"); break;          \
 137         case 4: __put_user_asm(x, ptr, retval, "l.sw"); break;          \
 138         case 8: __put_user_asm2(x, ptr, retval); break;                 \
 139         default: __put_user_bad();                                      \
 140         }                                                               \
 141 } while (0)
 142
 143 struct __large_struct {
 144         unsigned long buf[100];
 145 };
 146 #define __m(x) (*(struct __large_struct *)(x))
 147
 148 /*
 149  * We don't tell gcc that we are accessing memory, but this is OK
 150  * because we do not write to any memory gcc knows about, so there
 151  * are no aliasing issues.
 152  */
 153 #define __put_user_asm(x, addr, err, op)                        \
 154         __asm__ __volatile__(                                   \
 155                 "1:     "op" 0(%2),%1\n"                        \
 156                 "2:\n"                                          \
 157                 ".section .fixup,\"ax\"\n"                      \
 158                 "3:     l.addi %0,r0,%3\n"                      \
 159                 "       l.j 2b\n"                               \
 160                 "       l.nop\n"                                \
 161                 ".previous\n"                                   \
 162                 ".section __ex_table,\"a\"\n"                   \
 163                 "       .align 2\n"                             \
 164                 "       .long 1b,3b\n"                          \
 165                 ".previous"                                     \
 166                 : "=r"(err)                                     \
 167                 : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
 168
 169 #define __put_user_asm2(x, addr, err)                           \
 170         __asm__ __volatile__(                                   \
 171                 "1:     l.sw 0(%2),%1\n"                        \
 172                 "2:     l.sw 4(%2),%H1\n"                       \
 173                 "3:\n"                                          \
 174                 ".section .fixup,\"ax\"\n"                      \
 175                 "4:     l.addi %0,r0,%3\n"                      \
 176                 "       l.j 3b\n"                               \
 177                 "       l.nop\n"                                \
 178                 ".previous\n"                                   \
 179                 ".section __ex_table,\"a\"\n"                   \
 180                 "       .align 2\n"                             \
 181                 "       .long 1b,4b\n"                          \
 182                 "       .long 2b,4b\n"                          \
 183                 ".previous"                                     \
 184                 : "=r"(err)                                     \
 185                 : "r"(x), "r"(addr), "i"(-EFAULT), "0"(err))
 186
 187 #define __get_user_nocheck(x, ptr, size)                        \
 188 ({                                                              \
 189         long __gu_err, __gu_val;                                \
 190         __get_user_size(__gu_val, (ptr), (size), __gu_err);     \
 191         (x) = (__force __typeof__(*(ptr)))__gu_val;             \
 192         __gu_err;                                               \
 193 })
 194
 195 #define __get_user_check(x, ptr, size)                                  \
 196 ({                                                                      \
 197         long __gu_err = -EFAULT, __gu_val = 0;                          \
 198         const __typeof__(*(ptr)) * __gu_addr = (ptr);                   \
 199         if (access_ok(VERIFY_READ, __gu_addr, size))                    \
 200                 __get_user_size(__gu_val, __gu_addr, (size), __gu_err); \
 201         (x) = (__force __typeof__(*(ptr)))__gu_val;                     \
 202         __gu_err;                                                       \
 203 })
 204
 205 extern long __get_user_bad(void);
 206
 207 #define __get_user_size(x, ptr, size, retval)                           \
 208 do {                                                                    \
 209         retval = 0;                                                     \
 210         switch (size) {                                                 \
 211         case 1: __get_user_asm(x, ptr, retval, "l.lbz"); break;         \
 212         case 2: __get_user_asm(x, ptr, retval, "l.lhz"); break;         \
 213         case 4: __get_user_asm(x, ptr, retval, "l.lwz"); break;         \
 214         case 8: __get_user_asm2(x, ptr, retval); break;                 \
 215         default: (x) = __get_user_bad();                                \
 216         }                                                               \
 217 } while (0)
 218
 219 #define __get_user_asm(x, addr, err, op)                \
 220         __asm__ __volatile__(                           \
 221                 "1:     "op" %1,0(%2)\n"                \
 222                 "2:\n"                                  \
 223                 ".section .fixup,\"ax\"\n"              \
 224                 "3:     l.addi %0,r0,%3\n"              \
 225                 "       l.addi %1,r0,0\n"               \
 226                 "       l.j 2b\n"                       \
 227                 "       l.nop\n"                        \
 228                 ".previous\n"                           \
 229                 ".section __ex_table,\"a\"\n"           \
 230                 "       .align 2\n"                     \
 231                 "       .long 1b,3b\n"                  \
 232                 ".previous"                             \
 233                 : "=r"(err), "=r"(x)                    \
 234                 : "r"(addr), "i"(-EFAULT), "0"(err))
 235
 236 #define __get_user_asm2(x, addr, err)                   \
 237         __asm__ __volatile__(                           \
 238                 "1:     l.lwz %1,0(%2)\n"               \
 239                 "2:     l.lwz %H1,4(%2)\n"              \
 240                 "3:\n"                                  \
 241                 ".section .fixup,\"ax\"\n"              \
 242                 "4:     l.addi %0,r0,%3\n"              \
 243                 "       l.addi %1,r0,0\n"               \
 244                 "       l.addi %H1,r0,0\n"              \
 245                 "       l.j 3b\n"                       \
 246                 "       l.nop\n"                        \
 247                 ".previous\n"                           \
 248                 ".section __ex_table,\"a\"\n"           \
 249                 "       .align 2\n"                     \
 250                 "       .long 1b,4b\n"                  \
 251                 "       .long 2b,4b\n"                  \
 252                 ".previous"                             \
 253                 : "=r"(err), "=&r"(x)                   \
 254                 : "r"(addr), "i"(-EFAULT), "0"(err))
 255
 256 /* more complex routines */
 257
 258 extern unsigned long __must_check
 259 __copy_tofrom_user(void *to, const void *from, unsigned long size);
 260
 261 #define __copy_from_user(to, from, size) \
 262         __copy_tofrom_user(to, from, size)
 263 #define __copy_to_user(to, from, size) \
 264         __copy_tofrom_user(to, from, size)
 265
 266 #define __copy_to_user_inatomic __copy_to_user
 267 #define __copy_from_user_inatomic __copy_from_user
 268
 269 static inline unsigned long
 270 copy_from_user(void *to, const void *from, unsigned long n)
 271 {
 272         unsigned long res = n;
 273
 274         if (likely(access_ok(VERIFY_READ, from, n)))
 275                 res = __copy_tofrom_user(to, from, n);
 276         if (unlikely(res))
 277                 memset(to + (n - res), 0, res);
 278         return res;
 279 }
 280
 281 static inline unsigned long
 282 copy_to_user(void *to, const void *from, unsigned long n)
 283 {
 284         if (likely(access_ok(VERIFY_WRITE, to, n)))
 285                 n = __copy_tofrom_user(to, from, n);
 286         return n;
 287 }
 288
 289 extern unsigned long __clear_user(void *addr, unsigned long size);
 290
 291 static inline __must_check unsigned long
 292 clear_user(void *addr, unsigned long size)
 293 {
 294         if (likely(access_ok(VERIFY_WRITE, addr, size)))
 295                 size = __clear_user(addr, size);
 296         return size;
 297 }
 298
 299 #define user_addr_max() \
 300         (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
 301
 302 extern long strncpy_from_user(char *dest, const char __user *src, long count);
 303
 304 extern __must_check long strlen_user(const char __user *str);
 305 extern __must_check long strnlen_user(const char __user *str, long n);
 306
 307 #endif /* __ASM_OPENRISC_UACCESS_H */