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 struct exception_table_entry __attribute__((aligned(8))) __start___ex_table[];
  10 extern const struct exception_table_entry __attribute__((aligned(8))) __stop___ex_table[];
  11 extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler;
  12 extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler;
  13 extern spinlock_t modlist_lock;
  14
  15 /*****************************************************************************/
  16 /*
  17  *
  18  */
  19 static inline unsigned long search_one_table(const struct exception_table_entry *first,
  20                                              const struct exception_table_entry *last,
  21                                              unsigned long value)
  22 {
  23         while (first <= last) {
  24                 const struct exception_table_entry __attribute__((aligned(8))) *mid;
  25                 long diff;
  26
  27                 mid = (last - first) / 2 + first;
  28                 diff = mid->insn - value;
  29                 if (diff == 0)
  30                         return mid->fixup;
  31                 else if (diff < 0)
  32                         first = mid + 1;
  33                 else
  34                         last = mid - 1;
  35         }
  36         return 0;
  37 } /* end search_one_table() */
  38
  39 /*****************************************************************************/
  40 /*
  41  * see if there's a fixup handler available to deal with a kernel fault
  42  */
  43 unsigned long search_exception_table(unsigned long pc)
  44 {
  45         const struct exception_table_entry *extab;
  46
  47         /* determine if the fault lay during a memcpy_user or a memset_user */
  48         if (__frame->lr == (unsigned long) &__memset_user_error_lr &&
  49             (unsigned long) &memset <= pc && pc < (unsigned long) &__memset_end
  50             ) {
  51                 /* the fault occurred in a protected memset
  52                  * - we search for the return address (in LR) instead of the program counter
  53                  * - it was probably during a clear_user()
  54                  */
  55                 return (unsigned long) &__memset_user_error_handler;
  56         }
  57
  58         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         extab = search_exception_tables(pc);
  69         if (extab)
  70                 return extab->fixup;
  71
  72         return 0;
  73
  74 } /* end search_exception_table() */