linux-kernel - [Patch 4/5] module: trim exception table in module

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Message-Id: <20090604014849.6332.35945.sendpatchset@localhost.localdomain>
Date:	Wed, 3 Jun 2009 21:46:37 -0400
From:	Amerigo Wang <amwang@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	jdike@...toit.com, rusty@...tcorp.com.au, hch@...radead.org,
	Amerigo Wang <amwang@...hat.com>, mingo@...e.hu,
	akpm@...ux-foundation.org
Subject: [Patch 4/5] module: trim exception table in module_free()


Just as the comment said, trim the exception table entries when
module_free() mod->module_init.

Currently, this is only done for x86. Other platforms should
also fix it like this (except sparc32).

Signed-off-by: WANG Cong <amwang@...hat.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>

---
Index: linux-2.6/arch/x86/kernel/module.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/module.c
+++ linux-2.6/arch/x86/kernel/module.c
@@ -27,6 +27,7 @@
 #include <asm/system.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/uaccess.h>
 
 #if 0
 #define DEBUGP printk
@@ -60,12 +61,24 @@ void *module_alloc(unsigned long size)
 }
 #endif
 
+static void trim_init_extable(struct module *m)
+{
+	/*trim the beginning*/
+	while (m->num_exentries && within_module_init(m->extable[0].insn, m)) {
+		m->extable++;
+		m->num_exentries--;
+	}
+	/*trim the end*/
+	while (m->num_exentries &&
+		within_module_init(m->extable[m->num_exentries-1].insn, m))
+		m->num_exentries--;
+}
+
 /* Free memory returned from module_alloc */
 void module_free(struct module *mod, void *module_region)
 {
 	vfree(module_region);
-	/* FIXME: If module_region == mod->init_region, trim exception
-	   table entries. */
+	trim_init_extable(mod);
 }
 
 /* We don't need anything special. */
--
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