/*

   * arch/sh/mm/extable_64.c

   *
   * Copyright (C) 2003 Richard Curnow
   * Copyright (C) 2003, 2004  Paul Mundt
   *
   * Cloned from the 2.5 SH version..

   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.

   */

  #include <linux/rwsem.h>
  #include <linux/module.h>
  #include <asm/uaccess.h>
  
  extern unsigned long copy_user_memcpy, copy_user_memcpy_end;
  extern void __copy_user_fixup(void);
  
  static const struct exception_table_entry __copy_user_fixup_ex = {
  	.fixup = (unsigned long)&__copy_user_fixup,
  };

  /*
   * Some functions that may trap due to a bad user-mode address have too
   * many loads and stores in them to make it at all practical to label
   * each one and put them all in the main exception table.
   *
   * In particular, the fast memcpy routine is like this.  It's fix-up is
   * just to fall back to a slow byte-at-a-time copy, which is handled the
   * conventional way.  So it's functionally OK to just handle any trap
   * occurring in the fast memcpy with that fixup.
   */

  static const struct exception_table_entry *check_exception_ranges(unsigned long addr)
  {
  	if ((addr >= (unsigned long)&copy_user_memcpy) &&
  	    (addr <= (unsigned long)&copy_user_memcpy_end))
  		return &__copy_user_fixup_ex;
  
  	return NULL;
  }
  
  /* Simple binary search */
  const struct exception_table_entry *
  search_extable(const struct exception_table_entry *first,
  		 const struct exception_table_entry *last,
  		 unsigned long value)
  {
  	const struct exception_table_entry *mid;
  
  	mid = check_exception_ranges(value);
  	if (mid)
  		return mid;
  
          while (first <= last) {
  		long diff;
  
  		mid = (last - first) / 2 + first;
  		diff = mid->insn - value;
                  if (diff == 0)
                          return mid;
                  else if (diff < 0)
                          first = mid+1;
                  else
                          last = mid-1;
          }
  
          return NULL;
  }
  
  int fixup_exception(struct pt_regs *regs)
  {
  	const struct exception_table_entry *fixup;
  
  	fixup = search_exception_tables(regs->pc);
  	if (fixup) {
  		regs->pc = fixup->fixup;
  		return 1;
  	}
  
  	return 0;
  }