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authorJessica Yu <jeyu@redhat.com>2016-03-16 20:55:39 -0400
committerJiri Kosina <jkosina@suse.cz>2016-03-17 09:45:10 +0100
commit7e545d6eca20ce8ef7f66a63146cbff82b2ba760 (patch)
treef8c4366009b357842b8b17b3bfddbfc3b634ff40 /kernel/livepatch/core.c
parent4c973d1620ae08f5cbe27644c5f5b974c8f594ec (diff)
downloadlinux-sh-7e545d6eca20ce8ef7f66a63146cbff82b2ba760.tar.gz
livepatch/module: remove livepatch module notifier
Remove the livepatch module notifier in favor of directly enabling and disabling patches to modules in the module loader. Hard-coding the function calls ensures that ftrace_module_enable() is run before klp_module_coming() during module load, and that klp_module_going() is run before ftrace_release_mod() during module unload. This way, ftrace and livepatch code is run in the correct order during the module load/unload sequence without dependence on the module notifier call chain. Signed-off-by: Jessica Yu <jeyu@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'kernel/livepatch/core.c')
-rw-r--r--kernel/livepatch/core.c147
1 files changed, 71 insertions, 76 deletions
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 780f00cdb7e5..d68fbf63b083 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -99,12 +99,12 @@ static void klp_find_object_module(struct klp_object *obj)
/*
* We do not want to block removal of patched modules and therefore
* we do not take a reference here. The patches are removed by
- * a going module handler instead.
+ * klp_module_going() instead.
*/
mod = find_module(obj->name);
/*
- * Do not mess work of the module coming and going notifiers.
- * Note that the patch might still be needed before the going handler
+ * Do not mess work of klp_module_coming() and klp_module_going().
+ * Note that the patch might still be needed before klp_module_going()
* is called. Module functions can be called even in the GOING state
* until mod->exit() finishes. This is especially important for
* patches that modify semantic of the functions.
@@ -866,103 +866,108 @@ int klp_register_patch(struct klp_patch *patch)
}
EXPORT_SYMBOL_GPL(klp_register_patch);
-static int klp_module_notify_coming(struct klp_patch *patch,
- struct klp_object *obj)
+int klp_module_coming(struct module *mod)
{
- struct module *pmod = patch->mod;
- struct module *mod = obj->mod;
int ret;
+ struct klp_patch *patch;
+ struct klp_object *obj;
- ret = klp_init_object_loaded(patch, obj);
- if (ret) {
- pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
- pmod->name, mod->name, ret);
- return ret;
- }
+ if (WARN_ON(mod->state != MODULE_STATE_COMING))
+ return -EINVAL;
- if (patch->state == KLP_DISABLED)
- return 0;
+ mutex_lock(&klp_mutex);
+ /*
+ * Each module has to know that klp_module_coming()
+ * has been called. We never know what module will
+ * get patched by a new patch.
+ */
+ mod->klp_alive = true;
- pr_notice("applying patch '%s' to loading module '%s'\n",
- pmod->name, mod->name);
+ list_for_each_entry(patch, &klp_patches, list) {
+ klp_for_each_object(patch, obj) {
+ if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+ continue;
- ret = klp_enable_object(obj);
- if (ret)
- pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
- pmod->name, mod->name, ret);
- return ret;
-}
+ obj->mod = mod;
-static void klp_module_notify_going(struct klp_patch *patch,
- struct klp_object *obj)
-{
- struct module *pmod = patch->mod;
- struct module *mod = obj->mod;
+ ret = klp_init_object_loaded(patch, obj);
+ if (ret) {
+ pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+ patch->mod->name, obj->mod->name, ret);
+ goto err;
+ }
- if (patch->state == KLP_DISABLED)
- goto disabled;
+ if (patch->state == KLP_DISABLED)
+ break;
+
+ pr_notice("applying patch '%s' to loading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+
+ ret = klp_enable_object(obj);
+ if (ret) {
+ pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+ patch->mod->name, obj->mod->name, ret);
+ goto err;
+ }
+
+ break;
+ }
+ }
- pr_notice("reverting patch '%s' on unloading module '%s'\n",
- pmod->name, mod->name);
+ mutex_unlock(&klp_mutex);
- klp_disable_object(obj);
+ return 0;
-disabled:
+err:
+ /*
+ * If a patch is unsuccessfully applied, return
+ * error to the module loader.
+ */
+ pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
+ patch->mod->name, obj->mod->name, obj->mod->name);
+ mod->klp_alive = false;
klp_free_object_loaded(obj);
+ mutex_unlock(&klp_mutex);
+
+ return ret;
}
-static int klp_module_notify(struct notifier_block *nb, unsigned long action,
- void *data)
+void klp_module_going(struct module *mod)
{
- int ret;
- struct module *mod = data;
struct klp_patch *patch;
struct klp_object *obj;
- if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING)
- return 0;
+ if (WARN_ON(mod->state != MODULE_STATE_GOING &&
+ mod->state != MODULE_STATE_COMING))
+ return;
mutex_lock(&klp_mutex);
-
/*
- * Each module has to know that the notifier has been called.
- * We never know what module will get patched by a new patch.
+ * Each module has to know that klp_module_going()
+ * has been called. We never know what module will
+ * get patched by a new patch.
*/
- if (action == MODULE_STATE_COMING)
- mod->klp_alive = true;
- else /* MODULE_STATE_GOING */
- mod->klp_alive = false;
+ mod->klp_alive = false;
list_for_each_entry(patch, &klp_patches, list) {
klp_for_each_object(patch, obj) {
if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
continue;
- if (action == MODULE_STATE_COMING) {
- obj->mod = mod;
- ret = klp_module_notify_coming(patch, obj);
- if (ret) {
- obj->mod = NULL;
- pr_warn("patch '%s' is in an inconsistent state!\n",
- patch->mod->name);
- }
- } else /* MODULE_STATE_GOING */
- klp_module_notify_going(patch, obj);
+ if (patch->state != KLP_DISABLED) {
+ pr_notice("reverting patch '%s' on unloading module '%s'\n",
+ patch->mod->name, obj->mod->name);
+ klp_disable_object(obj);
+ }
+ klp_free_object_loaded(obj);
break;
}
}
mutex_unlock(&klp_mutex);
-
- return 0;
}
-static struct notifier_block klp_module_nb = {
- .notifier_call = klp_module_notify,
- .priority = INT_MIN+1, /* called late but before ftrace notifier */
-};
-
static int __init klp_init(void)
{
int ret;
@@ -973,21 +978,11 @@ static int __init klp_init(void)
return -EINVAL;
}
- ret = register_module_notifier(&klp_module_nb);
- if (ret)
- return ret;
-
klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
- if (!klp_root_kobj) {
- ret = -ENOMEM;
- goto unregister;
- }
+ if (!klp_root_kobj)
+ return -ENOMEM;
return 0;
-
-unregister:
- unregister_module_notifier(&klp_module_nb);
- return ret;
}
module_init(klp_init);