[PATCH v13 07/12] livepatch: Use lists to manage patches, objects and functions

Petr Mladek
2018-10-15T12:38:22Z

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>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
---
include/linux/livepatch.h | 19 +++++++++++++++++--
kernel/livepatch/core.c | 31 ++++++++++++++++++++++++++-----
2 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 17ceb81beedf..e4629309916e 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)
* @module_put: module reference taken and patch not forced
* @free_work: work freeing the patch that has to be done in another context
@@ -150,6 +158,7 @@ struct klp_patch {
/* internal */
struct list_head list;
struct kobject kobj;
+ struct list_head obj_list;
bool enabled;
bool module_put;
struct work_struct free_work;
@@ -196,14 +205,20 @@ struct klp_patch {
}
#define KLP_OBJECT_END { }

-#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_addr || 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 76c5b08ffacf..96ff7820fe24 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -50,6 +50,29 @@ LIST_HEAD(klp_patches);

static struct kobject *klp_root_kobj;

+static int klp_init_lists(struct klp_patch *patch)
+{
+ struct klp_object *obj;
+ struct klp_func *func;
+
+ INIT_LIST_HEAD(&patch->obj_list);
+ if (!patch->objs)
+ return -EINVAL;
+
+ klp_for_each_object_static(patch, obj) {
+ list_add(&obj->node, &patch->obj_list);
+
+ INIT_LIST_HEAD(&obj->func_list);
+ if (!obj->funcs)
+ return -EINVAL;
+
+ klp_for_each_func_static(obj, func)
+ list_add(&func->node, &obj->func_list);
+ }
+
+ return 0;
+}
+
static bool klp_is_module(struct klp_object *obj)
{
return obj->name;
@@ -609,9 +632,6 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
int ret;
const char *name;

- if (!obj->funcs)
- return -EINVAL;
-
if (klp_is_module(obj) && strlen(obj->name) >= MODULE_NAME_LEN)
return -EINVAL;

@@ -649,8 +669,9 @@ static int klp_init_patch(struct klp_patch *patch)
INIT_WORK(&patch->free_work, klp_free_patch_fn);
init_completion(&patch->finish);

- if (!patch->objs)
- return -EINVAL;
+ ret = klp_init_lists(patch);
+ if (ret)
+ return ret;

/*
* A reference is taken on the patch module to prevent it from being
--
2.13.7