[RESEND PATCH v2] lib/extable.c: use bsearch() library function in search_extable()
From: Thomas Meyer
Date: Thu Jun 15 2017 - 08:43:40 EST
Signed-off-by: Thomas Meyer <thomas@xxxxxxxx>
---
Âinclude/linux/extable.h |ÂÂ3 ++-
Âkernel/extable.cÂÂÂÂÂÂÂÂ|ÂÂ2 +-
Âkernel/module.cÂÂÂÂÂÂÂÂÂ|ÂÂ2 +-
Âlib/extable.cÂÂÂÂÂÂÂÂÂÂÂ| 38 +++++++++++++++++++-------------------
Â4 files changed, 23 insertions(+), 22 deletions(-)
diff --git a/include/linux/extable.h b/include/linux/extable.h
index 7effea4..b575bb9 100644
--- a/include/linux/extable.h
+++ b/include/linux/extable.h
@@ -2,13 +2,14 @@
Â#define _LINUX_EXTABLE_H
Â
Â#include <linux/stddef.h> /* for NULL */
+#include <linux/types.h>
Â
Âstruct module;
Âstruct exception_table_entry;
Â
Âconst struct exception_table_entry *
Âsearch_extable(const struct exception_table_entry *first,
- ÂÂÂÂÂÂÂconst struct exception_table_entry *last,
+ ÂÂÂÂÂÂÂconst size_t num,
 ÂÂÂÂÂÂÂunsigned long value);
Âvoid sort_extable(struct exception_table_entry *start,
 ÂÂstruct exception_table_entry *finish);
diff --git a/kernel/extable.c b/kernel/extable.c
index 2676d7f..0c25b75 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -55,7 +55,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
Â{
 const struct exception_table_entry *e;
Â
- 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;
diff --git a/kernel/module.c b/kernel/module.c
index 4a3665f..22faf11 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -4201,7 +4201,7 @@ const struct exception_table_entry *search_module_extables(unsigned long addr)
 goto out;
Â
 e = search_extable(mod->extable,
- ÂÂÂmod->extable + mod->num_exentries - 1,
+ ÂÂÂmod->num_exentries,
 ÂÂÂaddr);
Âout:
 preempt_enable();
diff --git a/lib/extable.c b/lib/extable.c
index 62968da..d4d3929 100644
--- a/lib/extable.c
+++ b/lib/extable.c
@@ -9,6 +9,7 @@
 * 2 of the License, or (at your option) any later version.
 */
Â
+#include <linux/bsearch.h>
Â#include <linux/module.h>
Â#include <linux/init.h>
Â#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)
Â{
 const struct exception_table_entry *x = a, *y = b;
Â
@@ -67,7 +68,7 @@ void sort_extable(struct exception_table_entry *start,
 ÂÂstruct exception_table_entry *finish)
Â{
 sort(start, finish - start, sizeof(struct exception_table_entry),
- ÂÂÂÂÂcmp_ex, swap_ex);
+ ÂÂÂÂÂcmp_ex_sort, swap_ex);
Â}
Â
Â#ifdef CONFIG_MODULES
@@ -93,6 +94,20 @@ void trim_init_extable(struct module *m)
Â#endif /* !ARCH_HAS_SORT_EXTABLE */
Â
Â#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;
+}
+
Â/*
 * 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)
 */
Âconst struct exception_table_entry *
Âsearch_extable(const struct exception_table_entry *first,
- ÂÂÂÂÂÂÂconst struct exception_table_entry *last,
+ ÂÂÂÂÂÂÂconst size_t num,Â
 ÂÂÂÂÂÂÂunsigned long value)
Â{
- while (first <= last) {
- const struct exception_table_entry *mid;
-
- mid = ((last - first) >> 1) + first;
- /*
- Â* careful, the distance between value and insn
- Â* can be larger than MAX_LONG:
- Â*/
- 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);
Â}
Â#endif