The added sysfs interface /sys/kernel/livepatch/state is read-only,
it shows the patches that have been applied, incluing the stack index
and the state of each patch.

$ cat /sys/kernel/livepatch/state
Index   Patch                           State
-----------------------------------------------
1       klp_test1                       enabled
2       klp_test2                       enabled
3       klp_test3                       enabled
-----------------------------------------------

$ echo 0 > /sys/kernel/livepatch/klp_test3/enabled
$ cat /sys/kernel/livepatch/state
Index   Patch                           State
-----------------------------------------------
1       klp_test1                       enabled
2       klp_test2                       enabled
3       klp_test3                       disabled
-----------------------------------------------

Signed-off-by: Li Bin <huawei.li...@huawei.com>
---
 Documentation/ABI/testing/sysfs-kernel-livepatch |    9 +++++
 kernel/livepatch/core.c                          |   41 +++++++++++++++++++++-
 2 files changed, 49 insertions(+), 1 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch 
b/Documentation/ABI/testing/sysfs-kernel-livepatch
index 5bf42a8..01c64da 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -8,6 +8,15 @@ Description:
                The /sys/kernel/livepatch directory contains subdirectories for
                each loaded live patch module.
 
+What:          /sys/kernel/livepatch/state
+Date:          Jun 2015
+KernelVersion: 4.1.0   
+Contact:       live-patch...@vger.kernel.org
+Description:
+               The state file is read-only and shows the patches that have
+               been applied, including the patch stack index and state of
+               each patch. 
+
 What:          /sys/kernel/livepatch/<patch>
 Date:          Nov 2014
 KernelVersion: 3.19.0
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 3f9f1d6..5d004f3 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -604,6 +604,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
  * Sysfs Interface
  *
  * /sys/kernel/livepatch
+ * /sys/kernel/livepatch/state
  * /sys/kernel/livepatch/<patch>
  * /sys/kernel/livepatch/<patch>/enabled
  * /sys/kernel/livepatch/<patch>/<object>
@@ -1008,6 +1009,36 @@ static struct notifier_block klp_module_nb = {
        .priority = INT_MIN+1, /* called late but before ftrace notifier */
 };
 
+static ssize_t state_show(struct kobject *kobj,
+                           struct kobj_attribute *attr, char *buf)
+{
+       struct klp_patch *patch;
+       unsigned long size = 0;
+       int index = 0;
+       size += snprintf(buf+size, PAGE_SIZE-size-1, "%-5s\t%-26s\t%-8s\n", 
"Index", "Patch", "State");
+       size += snprintf(buf+size, PAGE_SIZE-size-1, 
"-----------------------------------------------\n");
+       mutex_lock(&klp_mutex);
+       list_for_each_entry(patch, &klp_patches, list) {
+               size += snprintf(buf+size, PAGE_SIZE-size-1, 
"%-5d\t%-26s\t%-8s\n",
+                       ++index, patch->mod->name, patch->state ? "enabled" : 
"disabled");
+       }
+       mutex_unlock(&klp_mutex);
+       size += snprintf(buf+size, PAGE_SIZE-size-1, 
"-----------------------------------------------\n");
+
+       return size;
+}
+static struct kobj_attribute state_kobj_attr = __ATTR_RO(state);
+
+static struct attribute *klp_top_attrs[] = {
+       &state_kobj_attr.attr,
+       NULL
+};
+
+static struct kobj_type klp_ktype_top = {
+       .sysfs_ops = &kobj_sysfs_ops,
+       .default_attrs = klp_top_attrs,
+};
+
 static int klp_init(void)
 {
        int ret;
@@ -1022,12 +1053,20 @@ static int klp_init(void)
        if (ret)
                return ret;
 
-       klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
+       klp_root_kobj = kzalloc(sizeof(*klp_root_kobj), GFP_KERNEL);
        if (!klp_root_kobj) {
                ret = -ENOMEM;
                goto unregister;
        }
 
+       ret = kobject_init_and_add(klp_root_kobj, &klp_ktype_top,
+                       kernel_kobj, "livepatch");
+       if (ret) {
+               kobject_put(klp_root_kobj);
+               klp_root_kobj = NULL;
+               goto unregister;
+       }
+
        return 0;
 
 unregister:
-- 
1.7.7

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