linux-kernel - [PATCH 1/8] livepatch: Use lists to manage patches, objects and functions

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Message-Id: <20180323120028.31451-2-pmladek@suse.com>
Date:   Fri, 23 Mar 2018 13:00:21 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     Jiri Kosina <jikos@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Miroslav Benes <mbenes@...e.cz>
Cc:     Jason Baron <jbaron@...mai.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Jessica Yu <jeyu@...nel.org>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        Petr Mladek <pmladek@...e.com>
Subject: [PATCH 1/8] livepatch: Use lists to manage patches, objects and functions

From: Jason Baron <jbaron@...mai.com>

Currently klp_patch contains a pointer to a statically allocated array of
struct klp_object and struct klp_objects contains a pointer to a statically
allocated array of klp_func. In order to allow for the dynamic allocation
of objects and functions, link klp_patch, klp_object, and klp_func together
via linked lists. This allows us to more easily allocate new objects and
functions, while having the iterator be a simple linked list walk.

The static structures are added to the lists early. It allows to add
the dynamically allocated objects before klp_init_object() and
klp_init_func() calls. Therefore it reduces the further changes
to the code.

This patch does not change the existing behavior.

Signed-off-by: Jason Baron <jbaron@...mai.com>
[pmladek@...e.com: Initialize lists before init calls]
Signed-off-by: Petr Mladek <pmladek@...e.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Jessica Yu <jeyu@...nel.org>
Cc: Jiri Kosina <jikos@...nel.org>
Cc: Miroslav Benes <mbenes@...e.cz>
---
 include/linux/livepatch.h | 19 +++++++++++++++++--
 kernel/livepatch/core.c   | 16 ++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 4754f01c1abb..f0a5a28b1386 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/ftrace.h>
 #include <linux/completion.h>
+#include <linux/list.h>
 
 #if IS_ENABLED(CONFIG_LIVEPATCH)
 
@@ -42,6 +43,7 @@
  *		can be found (optional)
  * @old_addr:	the address of the function being patched
  * @kobj:	kobject for sysfs resources
+ * @node:	list node for klp_object func_list
  * @stack_node:	list node for klp_ops func_stack list
  * @old_size:	size of the old function
  * @new_size:	size of the new function
@@ -79,6 +81,7 @@ struct klp_func {
 	/* internal */
 	unsigned long old_addr;
 	struct kobject kobj;
+	struct list_head node;
 	struct list_head stack_node;
 	unsigned long old_size, new_size;
 	bool patched;
@@ -117,6 +120,8 @@ struct klp_callbacks {
  * @kobj:	kobject for sysfs resources
  * @mod:	kernel module associated with the patched object
  *		(NULL for vmlinux)
+ * @func_list:	dynamic list of the function entries
+ * @node:	list node for klp_patch obj_list
  * @patched:	the object's funcs have been added to the klp_ops list
  */
 struct klp_object {
@@ -127,6 +132,8 @@ struct klp_object {
 
 	/* internal */
 	struct kobject kobj;
+	struct list_head func_list;
+	struct list_head node;
 	struct module *mod;
 	bool patched;
 };
@@ -137,6 +144,7 @@ struct klp_object {
  * @objs:	object entries for kernel objects to be patched
  * @list:	list node for global list of registered patches
  * @kobj:	kobject for sysfs resources
+ * @obj_list:	dynamic list of the object entries
  * @enabled:	the patch is enabled (but operation may be incomplete)
  * @finish:	for waiting till it is safe to remove the patch module
  */
@@ -148,18 +156,25 @@ struct klp_patch {
 	/* internal */
 	struct list_head list;
 	struct kobject kobj;
+	struct list_head obj_list;
 	bool enabled;
 	struct completion finish;
 };
 
-#define klp_for_each_object(patch, obj) \
+#define klp_for_each_object_static(patch, obj) \
 	for (obj = patch->objs; obj->funcs || obj->name; obj++)
 
-#define klp_for_each_func(obj, func) \
+#define klp_for_each_object(patch, obj)	\
+	list_for_each_entry(obj, &patch->obj_list, node)
+
+#define klp_for_each_func_static(obj, func) \
 	for (func = obj->funcs; \
 	     func->old_name || func->new_func || func->old_sympos; \
 	     func++)
 
+#define klp_for_each_func(obj, func)	\
+	list_for_each_entry(func, &obj->func_list, node)
+
 int klp_register_patch(struct klp_patch *);
 int klp_unregister_patch(struct klp_patch *);
 int klp_enable_patch(struct klp_patch *);
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 3a4656fb7047..56cb0574c59c 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -49,6 +49,21 @@ static LIST_HEAD(klp_patches);
 
 static struct kobject *klp_root_kobj;
 
+static void klp_init_lists(struct klp_patch *patch)
+{
+	struct klp_object *obj;
+	struct klp_func *func;
+
+	INIT_LIST_HEAD(&patch->obj_list);
+	klp_for_each_object_static(patch, obj) {
+		list_add(&obj->node, &patch->obj_list);
+
+		INIT_LIST_HEAD(&obj->func_list);
+		klp_for_each_func_static(obj, func)
+			list_add(&func->node, &obj->func_list);
+	}
+}
+
 static bool klp_is_module(struct klp_object *obj)
 {
 	return obj->name;
@@ -794,6 +809,7 @@ static int klp_init_patch(struct klp_patch *patch)
 
 	patch->enabled = false;
 	init_completion(&patch->finish);
+	klp_init_lists(patch);
 
 	ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
 				   klp_root_kobj, "%s", patch->mod->name);
-- 
2.13.6