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