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         if (!access_ok(VERIFY_READ, from, n))
 106                 return n;
 107         return __copy_from_user(to, from, n);
 108 }
 109
 110 static inline long copy_to_user(void __user *to, const void *from,
 111                                 unsigned long n)
 112 {
 113         if (!access_ok(VERIFY_WRITE, to, n))
 114                 return n;
 115         return __copy_to_user(to, from, n);
 116 }
 117
 118 extern long strncpy_from_user(char *__to, const char __user *__from,
 119                                 long __len);
 120 extern long strnlen_user(const char __user *s, long n);
 121
 122 #define __copy_from_user_inatomic       __copy_from_user
 123 #define __copy_to_user_inatomic         __copy_to_user
 124
 125 /* Optimized macros */
 126 #define __get_user_asm(val, insn, addr, err)                            \
 127 {                                                                       \
 128         __asm__ __volatile__(                                           \
 129         "       movi    %0, %3\n"                                       \
 130         "1:   " insn " %1, 0(%2)\n"                                     \
 131         "       movi     %0, 0\n"                                       \
 132         "2:\n"                                                          \
 133         "       .section __ex_table,\"a\"\n"                            \
 134         "       .word 1b, 2b\n"                                         \
 135         "       .previous"                                              \
 136         : "=&r" (err), "=r" (val)                                       \
 137         : "r" (addr), "i" (-EFAULT));                                   \
 138 }
 139
 140 #define __get_user_unknown(val, size, ptr, err) do {                    \
 141         err = 0;                                                        \
 142         if (copy_from_user(&(val), ptr, size)) {                        \
 143                 err = -EFAULT;                                          \
 144         }                                                               \
 145         } while (0)
 146
 147 #define __get_user_common(val, size, ptr, err)                          \
 148 do {                                                                    \
 149         switch (size) {                                                 \
 150         case 1:                                                         \
 151                 __get_user_asm(val, "ldbu", ptr, err);                  \
 152                 break;                                                  \
 153         case 2:                                                         \
 154                 __get_user_asm(val, "ldhu", ptr, err);                  \
 155                 break;                                                  \
 156         case 4:                                                         \
 157                 __get_user_asm(val, "ldw", ptr, err);                   \
 158                 break;                                                  \
 159         default:                                                        \
 160                 __get_user_unknown(val, size, ptr, err);                \
 161                 break;                                                  \
 162         }                                                               \
 163 } while (0)
 164
 165 #define __get_user(x, ptr)                                              \
 166         ({                                                              \
 167         long __gu_err = -EFAULT;                                        \
 168         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);              \
 169         unsigned long __gu_val;                                         \
 170         __get_user_common(__gu_val, sizeof(*(ptr)), __gu_ptr, __gu_err);\
 171         (x) = (__force __typeof__(x))__gu_val;                          \
 172         __gu_err;                                                       \
 173         })
 174
 175 #define get_user(x, ptr)                                                \
 176 ({                                                                      \
 177         long __gu_err = -EFAULT;                                        \
 178         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);              \
 179         unsigned long __gu_val = 0;                                     \
 180         if (access_ok(VERIFY_READ,  __gu_ptr, sizeof(*__gu_ptr)))       \
 181                 __get_user_common(__gu_val, sizeof(*__gu_ptr),          \
 182                         __gu_ptr, __gu_err);                            \
 183         (x) = (__force __typeof__(x))__gu_val;                          \
 184         __gu_err;                                                       \
 185 })
 186
 187 #define __put_user_asm(val, insn, ptr, err)                             \
 188 {                                                                       \
 189         __asm__ __volatile__(                                           \
 190         "       movi    %0, %3\n"                                       \
 191         "1:   " insn " %1, 0(%2)\n"                                     \
 192         "       movi     %0, 0\n"                                       \
 193         "2:\n"                                                          \
 194         "       .section __ex_table,\"a\"\n"                            \
 195         "       .word 1b, 2b\n"                                         \
 196         "       .previous\n"                                            \
 197         : "=&r" (err)                                                   \
 198         : "r" (val), "r" (ptr), "i" (-EFAULT));                         \
 199 }
 200
 201 #define put_user(x, ptr)                                                \
 202 ({                                                                      \
 203         long __pu_err = -EFAULT;                                        \
 204         __typeof__(*(ptr)) __user *__pu_ptr = (ptr);                    \
 205         __typeof__(*(ptr)) __pu_val = (__typeof(*ptr))(x);              \
 206         if (access_ok(VERIFY_WRITE, __pu_ptr, sizeof(*__pu_ptr))) {     \
 207                 switch (sizeof(*__pu_ptr)) {                            \
 208                 case 1:                                                 \
 209                         __put_user_asm(__pu_val, "stb", __pu_ptr, __pu_err); \
 210                         break;                                          \
 211                 case 2:                                                 \
 212                         __put_user_asm(__pu_val, "sth", __pu_ptr, __pu_err); \
 213                         break;                                          \
 214                 case 4:                                                 \
 215                         __put_user_asm(__pu_val, "stw", __pu_ptr, __pu_err); \
 216                         break;                                          \
 217                 default:                                                \
 218                         /* XXX: This looks wrong... */                  \
 219                         __pu_err = 0;                                   \
 220                         if (copy_to_user(__pu_ptr, &(__pu_val),         \
 221                                 sizeof(*__pu_ptr)))                     \
 222                                 __pu_err = -EFAULT;                     \
 223                         break;                                          \
 224                 }                                                       \
 225         }                                                               \
 226         __pu_err;                                                       \
 227 })
 228
 229 #define __put_user(x, ptr) put_user(x, ptr)
 230
 231 #endif /* _ASM_NIOS2_UACCESS_H */