arch/frv/mm/extable.c

   1 /*
   2  * linux/arch/frv/mm/extable.c
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/spinlock.h>
   7 #include <asm/uaccess.h>
   8
   9 extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler;
  10 extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler;
  11 extern spinlock_t modlist_lock;
  12
  13 /*****************************************************************************/
  14 /*
  15  *
  16  */
  17 static inline unsigned long search_one_table(const struct exception_table_entry *first,
  18                                              const struct exception_table_entry *last,
  19                                              unsigned long value)
  20 {
  21         while (first <= last) {
  22                 const struct exception_table_entry __attribute__((aligned(8))) *mid;
  23                 long diff;
  24
  25                 mid = (last - first) / 2 + first;
  26                 diff = mid->insn - value;
  27                 if (diff == 0)
  28                         return mid->fixup;
  29                 else if (diff < 0)
  30                         first = mid + 1;
  31                 else
  32                         last = mid - 1;
  33         }
  34         return 0;
  35 } /* end search_one_table() */
  36
  37 /*****************************************************************************/
  38 /*
  39  * see if there's a fixup handler available to deal with a kernel fault
  40  */
  41 unsigned long search_exception_table(unsigned long pc)
  42 {
  43         const struct exception_table_entry *extab;
  44
  45         /* determine if the fault lay during a memcpy_user or a memset_user */
  46         if (__frame->lr == (unsigned long) &__memset_user_error_lr &&
  47             (unsigned long) &memset <= pc && pc < (unsigned long) &__memset_end
  48             ) {
  49                 /* the fault occurred in a protected memset
  50                  * - we search for the return address (in LR) instead of the program counter
  51                  * - it was probably during a clear_user()
  52                  */
  53                 return (unsigned long) &__memset_user_error_handler;
  54         }
  55
  56         if (__frame->lr == (unsigned long) &__memcpy_user_error_lr &&
  57             (unsigned long) &memcpy <= pc && pc < (unsigned long) &__memcpy_end
  58             ) {
  59                 /* the fault occurred in a protected memset
  60                  * - we search for the return address (in LR) instead of the program counter
  61                  * - it was probably during a copy_to/from_user()
  62                  */
  63                 return (unsigned long) &__memcpy_user_error_handler;
  64         }
  65
  66         extab = search_exception_tables(pc);
  67         if (extab)
  68                 return extab->fixup;
  69
  70         return 0;
  71
  72 } /* end search_exception_table() */