arch/nios2/include/asm/uaccess.h

   1 /*
   2  * User space memory access functions for Nios II
   3  *
   4  * Copyright (C) 2010-2011, Tobias Klauser <tklauser@distanz.ch>
   5  * Copyright (C) 2009, Wind River Systems Inc
   6  *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
   7  *
   8  * This file is subject to the terms and conditions of the GNU General Public
   9  * License.  See the file "COPYING" in the main directory of this archive
  10  * for more details.
  11  */
  12
  13 #ifndef _ASM_NIOS2_UACCESS_H
  14 #define _ASM_NIOS2_UACCESS_H
  15
  16 #include <linux/errno.h>
  17 #include <linux/thread_info.h>
  18 #include <linux/string.h>
  19
  20 #include <asm/page.h>
  21
  22 #define VERIFY_READ     0
  23 #define VERIFY_WRITE    1
  24
  25 /*
  26  * The exception table consists of pairs of addresses: the first is the
  27  * address of an instruction that is allowed to fault, and the second is
  28  * the address at which the program should continue.  No registers are
  29  * modified, so it is entirely up to the continuation code to figure out
  30  * what to do.
  31  *
  32  * All the routines below use bits of fixup code that are out of line
  33  * with the main instruction path.  This means when everything is well,
  34  * we don't even have to jump over them.  Further, they do not intrude
  35  * on our cache or tlb entries.
  36  */
  37 struct exception_table_entry {
  38         unsigned long insn;
  39         unsigned long fixup;
  40 };
  41
  42 extern int fixup_exception(struct pt_regs *regs);
  43
  44 /*
  45  * Segment stuff
  46  */
  47 #define MAKE_MM_SEG(s)          ((mm_segment_t) { (s) })
  48 #define USER_DS                 MAKE_MM_SEG(0x80000000UL)
  49 #define KERNEL_DS               MAKE_MM_SEG(0)
  50
  51 #define get_ds()                (KERNEL_DS)
  52
  53 #define get_fs()                (current_thread_info()->addr_limit)
  54 #define set_fs(seg)             (current_thread_info()->addr_limit = (seg))
  55
  56 #define segment_eq(a, b)        ((a).seg == (b).seg)
  57
  58 #define __access_ok(addr, len)                  \
  59         (((signed long)(((long)get_fs().seg) &  \
  60                 ((long)(addr) | (((long)(addr)) + (len)) | (len)))) == 0)
  61
  62 #define access_ok(type, addr, len)              \
  63         likely(__access_ok((unsigned long)(addr), (unsigned long)(len)))
  64
  65 # define __EX_TABLE_SECTION     ".section __ex_table,\"a\"\n"
  66
  67 /*
  68  * Zero Userspace
  69  */
  70
  71 static inline unsigned long __must_check __clear_user(void __user *to,
  72                                                       unsigned long n)
  73 {
  74         __asm__ __volatile__ (
  75                 "1:     stb     zero, 0(%1)\n"
  76                 "       addi    %0, %0, -1\n"
  77                 "       addi    %1, %1, 1\n"
  78                 "       bne     %0, zero, 1b\n"
  79                 "2:\n"
  80                 __EX_TABLE_SECTION
  81                 ".word  1b, 2b\n"
  82                 ".previous\n"
  83                 : "=r" (n), "=r" (to)
  84                 : "0" (n), "1" (to)
  85         );
  86
  87         return n;
  88 }
  89
  90 static inline unsigned long __must_check clear_user(void __user *to,
  91                                                     unsigned long n)
  92 {
  93         if (!access_ok(VERIFY_WRITE, to, n))
  94                 return n;
  95         return __clear_user(to, n);
  96 }
  97
  98 extern long __copy_from_user(void *to, const void __user *from,
  99                                 unsigned long n);
 100 extern long __copy_to_user(void __user *to, const void *from, unsigned long n);
 101
 102 static inline long copy_from_user(void *to, const void __user *from,
 103                                 unsigned long n)
 104 {
 105         unsigned long res = n;
 106         if (access_ok(VERIFY_READ, from, n))
 107                 res = __copy_from_user(to, from, n);
 108         if (unlikely(res))
 109                 memset(to + (n - res), 0, res);
 110         return res;
 111 }
 112
 113 static inline long copy_to_user(void __user *to, const void *from,
 114                                 unsigned long n)
 115 {
 116         if (!access_ok(VERIFY_WRITE, to, n))
 117                 return n;
 118         return __copy_to_user(to, from, n);
 119 }
 120
 121 extern long strncpy_from_user(char *__to, const char __user *__from,
 122                                 long __len);
 123 extern long strnlen_user(const char __user *s, long n);
 124
 125 #define __copy_from_user_inatomic       __copy_from_user
 126 #define __copy_to_user_inatomic         __copy_to_user
 127
 128 /* Optimized macros */
 129 #define __get_user_asm(val, insn, addr, err)                            \
 130 {                                                                       \
 131         __asm__ __volatile__(                                           \
 132         "       movi    %0, %3\n"                                       \
 133         "1:   " insn " %1, 0(%2)\n"                                     \
 134         "       movi     %0, 0\n"                                       \
 135         "2:\n"                                                          \
 136         "       .section __ex_table,\"a\"\n"                            \
 137         "       .word 1b, 2b\n"                                         \
 138         "       .previous"                                              \
 139         : "=&r" (err), "=r" (val)                                       \
 140         : "r" (addr), "i" (-EFAULT));                                   \
 141 }
 142
 143 #define __get_user_unknown(val, size, ptr, err) do {                    \
 144         err = 0;                                                        \
 145         if (__copy_from_user(&(val), ptr, size)) {                      \
 146                 err = -EFAULT;                                          \
 147         }                                                               \
 148         } while (0)
 149
 150 #define __get_user_common(val, size, ptr, err)                          \
 151 do {                                                                    \
 152         switch (size) {                                                 \
 153         case 1:                                                         \
 154                 __get_user_asm(val, "ldbu", ptr, err);                  \
 155                 break;                                                  \
 156         case 2:                                                         \
 157                 __get_user_asm(val, "ldhu", ptr, err);                  \
 158                 break;                                                  \
 159         case 4:                                                         \
 160                 __get_user_asm(val, "ldw", ptr, err);                   \
 161                 break;                                                  \
 162         default:                                                        \
 163                 __get_user_unknown(val, size, ptr, err);                \
 164                 break;                                                  \
 165         }                                                               \
 166 } while (0)
 167
 168 #define __get_user(x, ptr)                                              \
 169         ({                                                              \
 170         long __gu_err = -EFAULT;                                        \
 171         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);              \
 172         unsigned long __gu_val = 0;                                     \
 173         __get_user_common(__gu_val, sizeof(*(ptr)), __gu_ptr, __gu_err);\
 174         (x) = (__force __typeof__(x))__gu_val;                          \
 175         __gu_err;                                                       \
 176         })
 177
 178 #define get_user(x, ptr)                                                \
 179 ({                                                                      \
 180         long __gu_err = -EFAULT;                                        \
 181         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);              \
 182         unsigned long __gu_val = 0;                                     \
 183         if (access_ok(VERIFY_READ,  __gu_ptr, sizeof(*__gu_ptr)))       \
 184                 __get_user_common(__gu_val, sizeof(*__gu_ptr),          \
 185                         __gu_ptr, __gu_err);                            \
 186         (x) = (__force __typeof__(x))__gu_val;                          \
 187         __gu_err;                                                       \
 188 })
 189
 190 #define __put_user_asm(val, insn, ptr, err)                             \
 191 {                                                                       \
 192         __asm__ __volatile__(                                           \
 193         "       movi    %0, %3\n"                                       \
 194         "1:   " insn " %1, 0(%2)\n"                                     \
 195         "       movi     %0, 0\n"                                       \
 196         "2:\n"                                                          \
 197         "       .section __ex_table,\"a\"\n"                            \
 198         "       .word 1b, 2b\n"                                         \
 199         "       .previous\n"                                            \
 200         : "=&r" (err)                                                   \
 201         : "r" (val), "r" (ptr), "i" (-EFAULT));                         \
 202 }
 203
 204 #define put_user(x, ptr)                                                \
 205 ({                                                                      \
 206         long __pu_err = -EFAULT;                                        \
 207         __typeof__(*(ptr)) __user *__pu_ptr = (ptr);                    \
 208         __typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x);              \
 209         if (access_ok(VERIFY_WRITE, __pu_ptr, sizeof(*__pu_ptr))) {     \
 210                 switch (sizeof(*__pu_ptr)) {                            \
 211                 case 1:                                                 \
 212                         __put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \
 213                         break;                                          \
 214                 case 2:                                                 \
 215                         __put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \
 216                         break;                                          \
 217                 case 4:                                                 \
 218                         __put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \
 219                         break;                                          \
 220                 default:                                                \
 221                         /* XXX: This looks wrong... */                  \
 222                         __pu_err = 0;                                   \
 223                         if (copy_to_user(__pu_ptr, &(__pu_val),         \
 224                                 sizeof(*__pu_ptr)))                     \
 225                                 __pu_err = -EFAULT;                     \
 226                         break;                                          \
 227                 }                                                       \
 228         }                                                               \
 229         __pu_err;                                                       \
 230 })
 231
 232 #define __put_user(x, ptr) put_user(x, ptr)
 233
 234 #endif /* _ASM_NIOS2_UACCESS_H */