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         const struct exception_table_entry *extab;
  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
  59         if (__frame->lr == (unsigned long) &__memcpy_user_error_lr &&
  60             (unsigned long) &memcpy <= pc && pc < (unsigned long) &__memcpy_end
  61             ) {
  62                 /* the fault occurred in a protected memset
  63                  * - we search for the return address (in LR) instead of the program counter
  64                  * - it was probably during a copy_to/from_user()
  65                  */
  66                 return (unsigned long) &__memcpy_user_error_handler;
  67         }
  68
  69         extab = search_exception_tables(pc);
  70         if (extab)
  71                 return extab->fixup;
  72
  73         return 0;
  74
  75 } /* end search_exception_table() */