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

[thomas@m3y3r.de: v3: fix arch specific implementations]
  Link: http://lkml.kernel.org/r/1497890858.12931.7.camel@m3y3r.de
Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 20 deletions

diff --git a/lib/extable.c b/lib/extable.c
index 62968daa66a9..f54996fdd0b8 100644
--- a/lib/extable.c
+++ b/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 _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,
@@ -101,25 +116,11 @@ void trim_init_extable(struct module *m)
  * already sorted.
  */
 const struct exception_table_entry *
-search_extable(const struct exception_table_entry *first,
-               const struct exception_table_entry *last,
+search_extable(const struct exception_table_entry *base,
+               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, base, num,
+                       sizeof(struct exception_table_entry), cmp_ex_search);
 }
 #endif