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Subject[PATCH v15 06/11] livepatch: Use lists to manage patches, objects and functions
Date
From: Jason Baron <jbaron@akamai.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@akamai.com>
[pmladek@suse.com: Initialize lists before init calls]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
---
include/linux/livepatch.h | 19 +++++++++++++++++--
kernel/livepatch/core.c | 9 +++++++--
2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 8f9c19c69744..e117e20ff771 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_func: pointer to 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
@@ -80,6 +82,7 @@ struct klp_func {
/* internal */
void *old_func;
struct kobject kobj;
+ struct list_head node;
struct list_head stack_node;
unsigned long old_size, new_size;
bool kobj_added;
@@ -117,6 +120,8 @@ struct klp_callbacks {
* @funcs: function entries for functions to be patched in the object
* @callbacks: functions to be executed pre/post (un)patching
* @kobj: kobject for sysfs resources
+ * @func_list: dynamic list of the function entries
+ * @node: list node for klp_patch obj_list
* @mod: kernel module associated with the patched object
* (NULL for vmlinux)
* @kobj_added: @kobj has been added and needs freeing
@@ -130,6 +135,8 @@ struct klp_object {

/* internal */
struct kobject kobj;
+ struct list_head func_list;
+ struct list_head node;
struct module *mod;
bool kobj_added;
bool patched;
@@ -141,6 +148,7 @@ struct klp_object {
* @objs: object entries for kernel objects to be patched
* @list: list node for global list of actively used patches
* @kobj: kobject for sysfs resources
+ * @obj_list: dynamic list of the object entries
* @kobj_added: @kobj has been added and needs freeing
* @enabled: the patch is enabled (but operation may be incomplete)
* @forced: was involved in a forced transition
@@ -155,6 +163,7 @@ struct klp_patch {
/* internal */
struct list_head list;
struct kobject kobj;
+ struct list_head obj_list;
bool kobj_added;
bool enabled;
bool forced;
@@ -162,14 +171,20 @@ struct klp_patch {
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_enable_patch(struct klp_patch *);

void arch_klp_init_object_loaded(struct klp_patch *patch,
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index bd41b03a72d5..37d0d3645fa6 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -659,20 +659,25 @@ static int klp_init_patch_early(struct klp_patch *patch)
return -EINVAL;

INIT_LIST_HEAD(&patch->list);
+ INIT_LIST_HEAD(&patch->obj_list);
patch->kobj_added = false;
patch->enabled = false;
patch->forced = false;
INIT_WORK(&patch->free_work, klp_free_patch_work_fn);
init_completion(&patch->finish);

- klp_for_each_object(patch, obj) {
+ klp_for_each_object_static(patch, obj) {
if (!obj->funcs)
return -EINVAL;

+ INIT_LIST_HEAD(&obj->func_list);
obj->kobj_added = false;
+ list_add_tail(&obj->node, &patch->obj_list);

- klp_for_each_func(obj, func)
+ klp_for_each_func_static(obj, func) {
func->kobj_added = false;
+ list_add_tail(&func->node, &obj->func_list);
+ }
}

if (!try_module_get(patch->mod))
--
2.13.7
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