// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
   *
   * Copyright (C) 2004 Paul Mackerras, IBM Corp.

   */

  #include <linux/bsearch.h>

  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/sort.h>

  #include <linux/uaccess.h>

  #include <linux/extable.h>

  #ifndef ARCH_HAS_RELATIVE_EXTABLE
  #define ex_to_insn(x)	((x)->insn)
  #else
  static inline unsigned long ex_to_insn(const struct exception_table_entry *x)
  {
  	return (unsigned long)&x->insn + x->insn;
  }
  #endif

  #ifndef ARCH_HAS_SORT_EXTABLE

  #ifndef ARCH_HAS_RELATIVE_EXTABLE
  #define swap_ex		NULL
  #else
  static void swap_ex(void *a, void *b, int size)
  {
  	struct exception_table_entry *x = a, *y = b, tmp;
  	int delta = b - a;
  
  	tmp = *x;
  	x->insn = y->insn + delta;
  	y->insn = tmp.insn - delta;
  
  #ifdef swap_ex_entry_fixup
  	swap_ex_entry_fixup(x, y, tmp, delta);
  #else
  	x->fixup = y->fixup + delta;
  	y->fixup = tmp.fixup - delta;
  #endif
  }
  #endif /* ARCH_HAS_RELATIVE_EXTABLE */

  /*
   * The exception table needs to be sorted so that the binary
   * search that we use to find entries in it works properly.
   * This is used both for the kernel exception table and for
   * the exception tables of modules that get loaded.
   */

  static int cmp_ex_sort(const void *a, const void *b)

  {
  	const struct exception_table_entry *x = a, *y = b;
  
  	/* avoid overflow */

  	if (ex_to_insn(x) > ex_to_insn(y))

  		return 1;

  	if (ex_to_insn(x) < ex_to_insn(y))

  		return -1;
  	return 0;
  }
  
  void sort_extable(struct exception_table_entry *start,
  		  struct exception_table_entry *finish)
  {
  	sort(start, finish - start, sizeof(struct exception_table_entry),

  	     cmp_ex_sort, swap_ex);

  }

  
  #ifdef CONFIG_MODULES
  /*
   * If the exception table is sorted, any referring to the module init
   * will be at the beginning or the end.
   */
  void trim_init_extable(struct module *m)
  {
  	/*trim the beginning*/

  	while (m->num_exentries &&
  	       within_module_init(ex_to_insn(&m->extable[0]), m)) {

  		m->extable++;
  		m->num_exentries--;
  	}
  	/*trim the end*/
  	while (m->num_exentries &&

  	       within_module_init(ex_to_insn(&m->extable[m->num_exentries - 1]),
  				  m))

  		m->num_exentries--;
  }
  #endif /* CONFIG_MODULES */
  #endif /* !ARCH_HAS_SORT_EXTABLE */

  
  #ifndef ARCH_HAS_SEARCH_EXTABLE

  
  static int cmp_ex_search(const void *key, const void *elt)
  {
  	const struct exception_table_entry *_elt = elt;
  	unsigned long _key = *(unsigned long *)key;
  
  	/* avoid overflow */
  	if (_key > ex_to_insn(_elt))
  		return 1;
  	if (_key < ex_to_insn(_elt))
  		return -1;
  	return 0;
  }

  /*
   * Search one exception table for an entry corresponding to the
   * given instruction address, and return the address of the entry,
   * or NULL if none is found.
   * We use a binary search, and thus we assume that the table is
   * already sorted.
   */
  const struct exception_table_entry *

  search_extable(const struct exception_table_entry *base,
  	       const size_t num,

  	       unsigned long value)
  {

  	return bsearch(&value, base, num,
  		       sizeof(struct exception_table_entry), cmp_ex_search);

  }
  #endif