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Date: Mon, 19 Jun 2017 18:47:38 +0200
From: Thomas Meyer <thomas@...3r.de>
To: Andrew Morton <akpm@...ux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
"David S. Miller" <davem@...emloft.net>,
Rich Felker <dalias@...c.org>,
Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [PATCH v3] lib/extable.c: use bsearch() library function in
search_extable()
v3: Fix arch specific implementations
Signed-off-by: Thomas Meyer <thomas@...3r.de>
---
arch/mips/kernel/module.c | 3 ++-
arch/mips/kernel/traps.c | 3 ++-
arch/sh/mm/extable_64.c | 34 ++++++++++++++++++----------------
arch/sparc/mm/extable.c | 28 ++++++++++++++--------------
include/linux/extable.h | 5 +++--
kernel/extable.c | 3 ++-
kernel/module.c | 2 +-
lib/extable.c | 41 +++++++++++++++++++++--------------------
8 files changed, 63 insertions(+), 56 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 9681b5877140..120d3c8c94b0 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -427,7 +427,8 @@ 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;
diff --git a/include/linux/extable.h b/include/linux/extable.h
index 7effea4b257d..28addad0dda7 100644
--- a/include/linux/extable.h
+++ b/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,
+search_extable(const struct exception_table_entry *base,
+ const size_t num,
unsigned long value);
void sort_extable(struct exception_table_entry *start,
struct exception_table_entry *finish);
diff --git a/kernel/extable.c b/kernel/extable.c
index 2676d7f8baf6..fd91f0e78811 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -55,7 +55,8 @@ 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;
diff --git a/kernel/module.c b/kernel/module.c
index 4a3665f8f837..22faf11d4b06 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;
e = search_extable(mod->extable,
- mod->extable + mod->num_exentries - 1,
+ mod->num_exentries,
addr);
out:
preempt_enable();
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
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