lib/extable.c: use bsearch() library function in search_extable()

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/extable.h

@@ -2,13 +2,14 @@
 #define _LINUX_EXTABLE_H
 
 #include <linux/stddef.h> /* for NULL */
+#include <linux/types.h>
 
 struct module;
 struct exception_table_entry;
 
 const struct exception_table_entry *
 search_extable(const struct exception_table_entry *first,
- const struct exception_table_entry *last,
+ const size_t num,
  unsigned long value);
 void sort_extable(struct exception_table_entry *start,
  struct exception_table_entry *finish);

kernel/extable.c

@@ -55,7 +55,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
 {
  const struct exception_table_entry *e;
 
- e = search_extable(__start___ex_table, __stop___ex_table-1, addr);
+ e = search_extable(__start___ex_table, __stop___ex_table - __start___ex_table, addr);
  if (!e)
  e = search_module_extables(addr);
  return e;

kernel/module.c

@@ -4201,7 +4201,7 @@ const struct exception_table_entry *search_module_extables(unsigned long addr)
  goto out;
 
  e = search_extable(mod->extable,
- mod->extable + mod->num_exentries - 1,
+ mod->num_exentries,
  addr);
 out:
  preempt_enable();

lib/extable.c

@@ -9,6 +9,7 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#include <linux/bsearch.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/sort.h>
@@ -51,7 +52,7 @@ static void swap_ex(void *a, void *b, int size)
  * This is used both for the kernel exception table and for
  * the exception tables of modules that get loaded.
  */
-static int cmp_ex(const void *a, const void *b)
+static int cmp_ex_sort(const void *a, const void *b)
 {
  const struct exception_table_entry *x = a, *y = b;
 
@@ -67,7 +68,7 @@ void sort_extable(struct exception_table_entry *start,
  struct exception_table_entry *finish)
 {
  sort(start, finish - start, sizeof(struct exception_table_entry),
- cmp_ex, swap_ex);
+ cmp_ex_sort, swap_ex);
 }
 
 #ifdef CONFIG_MODULES
@@ -93,6 +94,20 @@ void trim_init_extable(struct module *m)
 #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 k = *(unsigned long*) key;
+
+ /* avoid overflow */
+ if (k > ex_to_insn(_elt))
+ return 1;
+ if (k < 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,
@@ -102,24 +117,9 @@ void trim_init_extable(struct module *m)
  */
 const struct exception_table_entry *
 search_extable(const struct exception_table_entry *first,
- const struct exception_table_entry *last,
+ const size_t num,
  unsigned long value)
 {
- while (first <= last) {
- const struct exception_table_entry *mid;
-
- mid = ((last - first) >> 1) + first;
- /*
- * careful, the distance between value and insn
- * can be larger than MAX_LONG:
- */
- if (ex_to_insn(mid) < value)
- first = mid + 1;
- else if (ex_to_insn(mid) > value)
- last = mid - 1;
- else
- return mid;
- }
- return NULL;
+ return bsearch(&value, first, num, sizeof(struct exception_table_entry), cmp_ex_search);
 }
 #endif