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>

4 files changed, 36 insertions, 32 deletions

diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index 94627a3a6a0d..50c020c47e54 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -317,7 +317,8 @@ const struct exception_table_entry *search_module_dbetables(unsigned long addr)
 
 	spin_lock_irqsave(&dbe_lock, flags);
 	list_for_each_entry(dbe, &dbe_list, dbe_list) {
-		e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
+		e = search_extable(dbe->dbe_start,
+				   dbe->dbe_end - dbe->dbe_start, addr);
 		if (e)
 			break;
 	}
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 38dfa27730ff..b68b4d0726d3 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -429,7 +429,8 @@ static const struct exception_table_entry *search_dbe_tables(unsigned long addr)
 {
 	const struct exception_table_entry *e;
 
-	e = search_extable(__start___dbe_table, __stop___dbe_table - 1, addr);
+	e = search_extable(__start___dbe_table,
+			   __stop___dbe_table - __start___dbe_table, addr);
 	if (!e)
 		e = search_module_dbetables(addr);
 	return e;
diff --git a/arch/sh/mm/extable_64.c b/arch/sh/mm/extable_64.c
index b90cdfad2c78..7a3b4d33d2e7 100644
--- a/arch/sh/mm/extable_64.c
+++ b/arch/sh/mm/extable_64.c
@@ -10,6 +10,7 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  */
+#include <linux/bsearch.h>
 #include <linux/rwsem.h>
 #include <linux/extable.h>
 #include <linux/uaccess.h>
@@ -40,10 +41,23 @@ static const struct exception_table_entry *check_exception_ranges(unsigned long
 	return NULL;
 }
 
+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 > _elt->insn)
+		return 1;
+	if (_key < _elt->insn)
+		return -1;
+	return 0;
+}
+
 /* Simple binary search */
 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)
 {
 	const struct exception_table_entry *mid;
@@ -52,20 +66,8 @@ search_extable(const struct exception_table_entry *first,
 	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;
+	return bsearch(&value, base, num,
+		       sizeof(struct exception_table_entry), cmp_ex_search);
 }
 
 int fixup_exception(struct pt_regs *regs)
diff --git a/arch/sparc/mm/extable.c b/arch/sparc/mm/extable.c
index db214e9931d9..2422511dc8c5 100644
--- a/arch/sparc/mm/extable.c
+++ b/arch/sparc/mm/extable.c
@@ -13,11 +13,11 @@ void sort_extable(struct exception_table_entry *start,
 
 /* Caller knows they are in a range if ret->fixup == 0 */
 const struct exception_table_entry *
-search_extable(const struct exception_table_entry *start,
-	       const struct exception_table_entry *last,
+search_extable(const struct exception_table_entry *base,
+	       const size_t num,
 	       unsigned long value)
 {
-	const struct exception_table_entry *walk;
+	int i;
 
 	/* Single insn entries are encoded as:
 	 *	word 1:	insn address
@@ -37,30 +37,30 @@ search_extable(const struct exception_table_entry *start,
 	 */
 
 	/* 1. Try to find an exact match. */
-	for (walk = start; walk <= last; walk++) {
-		if (walk->fixup == 0) {
+	for (i = 0; i < num; i++) {
+		if (base[i].fixup == 0) {
 			/* A range entry, skip both parts. */
-			walk++;
+			i++;
 			continue;
 		}
 
 		/* A deleted entry; see trim_init_extable */
-		if (walk->fixup == -1)
+		if (base[i].fixup == -1)
 			continue;
 
-		if (walk->insn == value)
-			return walk;
+		if (base[i].insn == value)
+			return &base[i];
 	}
 
 	/* 2. Try to find a range match. */
-	for (walk = start; walk <= (last - 1); walk++) {
-		if (walk->fixup)
+	for (i = 0; i < (num - 1); i++) {
+		if (base[i].fixup)
 			continue;
 
-		if (walk[0].insn <= value && walk[1].insn > value)
-			return walk;
+		if (base[i].insn <= value && base[i + 1].insn > value)
+			return &base[i];
 
-		walk++;
+		i++;
 	}
 
         return NULL;