arch/frv/mm/extable.c

   1 /*
   2  * linux/arch/frv/mm/extable.c
   3  */
   4
   5 #include <linux/config.h>
   6 #include <linux/module.h>
   7 #include <linux/spinlock.h>
   8 #include <asm/uaccess.h>
   9
  10 extern const struct exception_table_entry __attribute__((aligned(8))) __start___ex_table[];
  11 extern const struct exception_table_entry __attribute__((aligned(8))) __stop___ex_table[];
  12 extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler;
  13 extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler;
  14 extern spinlock_t modlist_lock;
  15
  16 /*****************************************************************************/
  17 /*
  18  *
  19  */
  20 static inline unsigned long search_one_table(const struct exception_table_entry *first,
  21                                              const struct exception_table_entry *last,
  22                                              unsigned long value)
  23 {
  24         while (first <= last) {
  25                 const struct exception_table_entry __attribute__((aligned(8))) *mid;
  26                 long diff;
  27
  28                 mid = (last - first) / 2 + first;
  29                 diff = mid->insn - value;
  30                 if (diff == 0)
  31                         return mid->fixup;
  32                 else if (diff < 0)
  33                         first = mid + 1;
  34                 else
  35                         last = mid - 1;
  36         }
  37         return 0;
  38 } /* end search_one_table() */
  39
  40 /*****************************************************************************/
  41 /*
  42  * see if there's a fixup handler available to deal with a kernel fault
  43  */
  44 unsigned long search_exception_table(unsigned long pc)
  45 {
  46         unsigned long ret = 0;
  47
  48         /* determine if the fault lay during a memcpy_user or a memset_user */
  49         if (__frame->lr == (unsigned long) &__memset_user_error_lr &&
  50             (unsigned long) &memset <= pc && pc < (unsigned long) &__memset_end
  51             ) {
  52                 /* the fault occurred in a protected memset
  53                  * - we search for the return address (in LR) instead of the program counter
  54                  * - it was probably during a clear_user()
  55                  */
  56                 return (unsigned long) &__memset_user_error_handler;
  57         }
  58         else if (__frame->lr == (unsigned long) &__memcpy_user_error_lr &&
  59                  (unsigned long) &memcpy <= pc && pc < (unsigned long) &__memcpy_end
  60                  ) {
  61                 /* the fault occurred in a protected memset
  62                  * - we search for the return address (in LR) instead of the program counter
  63                  * - it was probably during a copy_to/from_user()
  64                  */
  65                 return (unsigned long) &__memcpy_user_error_handler;
  66         }
  67
  68 #ifndef CONFIG_MODULES
  69         /* there is only the kernel to search.  */
  70         ret = search_one_table(__start___ex_table, __stop___ex_table - 1, pc);
  71         return ret;
  72
  73 #else
  74         /* the kernel is the last "module" -- no need to treat it special */
  75         unsigned long flags;
  76         struct module *mp;
  77
  78         spin_lock_irqsave(&modlist_lock, flags);
  79
  80         for (mp = module_list; mp != NULL; mp = mp->next) {
  81                 if (mp->ex_table_start == NULL || !(mp->flags & (MOD_RUNNING | MOD_INITIALIZING)))
  82                         continue;
  83                 ret = search_one_table(mp->ex_table_start, mp->ex_table_end - 1, pc);
  84                 if (ret)
  85                         break;
  86         }
  87
  88         spin_unlock_irqrestore(&modlist_lock, flags);
  89         return ret;
  90 #endif
  91 } /* end search_exception_table() */