PATCH v6 1/6] livepatch: Use lists to manage patches, objects and functions

[Petr Mladek]

From: Jason Baron <jbaron@xxxxxxxxxx>

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.

Also klp_init_*_list() functions are split because they will
be used when adding the dynamically allocated structures.

This patch does not change the existing behavior.

Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
[pmladek@xxxxxxxx: Initialize lists before init calls]
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Jessica Yu <jeyu@xxxxxxxxxx>
Cc: Jiri Kosina <jikos@xxxxxxxxxx>
Cc: Miroslav Benes <mbenes@xxxxxxx>
---
 include/linux/livepatch.h | 19 +++++++++++++++++--
 kernel/livepatch/core.c   | 27 +++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 4754f01c1abb..e5db2ba7e2a5 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)
 
@@ -43,6 +44,7 @@
  * @old_addr:	the address of the function being patched
  * @kobj:	kobject for sysfs resources
  * @stack_node:	list node for klp_ops func_stack list
+ * @func_entry:	links struct klp_func to struct klp_object
  * @old_size:	size of the old function
  * @new_size:	size of the new function
  * @patched:	the func has been added to the klp_ops list
@@ -80,6 +82,7 @@ struct klp_func {
 	unsigned long old_addr;
 	struct kobject kobj;
 	struct list_head stack_node;
+	struct list_head func_entry;
 	unsigned long old_size, new_size;
 	bool patched;
 	bool transition;
@@ -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:	head of list for struct klp_func
+ * @obj_entry:	links struct klp_object to struct klp_patch
  * @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 obj_entry;
 	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:	head of list for struct klp_object
  * @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, obj_entry)
+
+#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, func_entry)
+
 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..1d525f4a270a 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -49,6 +49,32 @@ static LIST_HEAD(klp_patches);
 
 static struct kobject *klp_root_kobj;
 
+static void klp_init_func_list(struct klp_object *obj, struct klp_func *func)
+{
+	list_add(&func->func_entry, &obj->func_list);
+}
+
+static void klp_init_object_list(struct klp_patch *patch,
+				 struct klp_object *obj)
+{
+	struct klp_func *func;
+
+	list_add(&obj->obj_entry, &patch->obj_list);
+
+	INIT_LIST_HEAD(&obj->func_list);
+	klp_for_each_func_static(obj, func)
+		klp_init_func_list(obj, func);
+}
+
+static void klp_init_patch_list(struct klp_patch *patch)
+{
+	struct klp_object *obj;
+
+	INIT_LIST_HEAD(&patch->obj_list);
+	klp_for_each_object_static(patch, obj)
+		klp_init_object_list(patch, obj);
+}
+
 static bool klp_is_module(struct klp_object *obj)
 {
 	return obj->name;
@@ -794,6 +820,7 @@ static int klp_init_patch(struct klp_patch *patch)
 
 	patch->enabled = false;
 	init_completion(&patch->finish);
+	klp_init_patch_list(patch);
 
 	ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
 				   klp_root_kobj, "%s", patch->mod->name);
-- 
2.13.6