Commit 26c3e98e authored by Petr Mladek's avatar Petr Mladek Committed by Jiri Kosina
Browse files

livepatch: Shuffle klp_enable_patch()/klp_disable_patch() code 



We are going to simplify the API and code by removing the registration
step. This would require calling init/free functions from enable/disable
ones.

This patch just moves the code to prevent more forward declarations.

This patch does not change the code except for two forward declarations.

Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Acked-by: default avatarMiroslav Benes <mbenes@suse.cz>
Acked-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 19514910

kernel/livepatch/core.c

+166 −164
Original line number Diff line number Diff line
@@ -278,170 +278,6 @@ static int klp_write_object_relocations(struct module *pmod, 
	return ret;

}



static int __klp_disable_patch(struct klp_patch *patch)

{

	struct klp_object *obj;



	if (WARN_ON(!patch->enabled))

		return -EINVAL;



	if (klp_transition_patch)

		return -EBUSY;



	/* enforce stacking: only the last enabled patch can be disabled */

	if (!list_is_last(&patch->list, &klp_patches) &&

	    list_next_entry(patch, list)->enabled)

		return -EBUSY;



	klp_init_transition(patch, KLP_UNPATCHED);



	klp_for_each_object(patch, obj)

		if (obj->patched)

			klp_pre_unpatch_callback(obj);



	/*

	 * Enforce the order of the func->transition writes in

	 * klp_init_transition() and the TIF_PATCH_PENDING writes in

	 * klp_start_transition().  In the rare case where klp_ftrace_handler()

	 * is called shortly after klp_update_patch_state() switches the task,

	 * this ensures the handler sees that func->transition is set.

	 */

	smp_wmb();



	klp_start_transition();

	klp_try_complete_transition();

	patch->enabled = false;



	return 0;

}



/**

 * klp_disable_patch() - disables a registered patch

 * @patch:	The registered, enabled patch to be disabled

 *

 * Unregisters the patched functions from ftrace.

 *

 * Return: 0 on success, otherwise error

 */

int klp_disable_patch(struct klp_patch *patch)

{

	int ret;



	mutex_lock(&klp_mutex);



	if (!klp_is_patch_registered(patch)) {

		ret = -EINVAL;

		goto err;

	}



	if (!patch->enabled) {

		ret = -EINVAL;

		goto err;

	}



	ret = __klp_disable_patch(patch);



err:

	mutex_unlock(&klp_mutex);

	return ret;

}

EXPORT_SYMBOL_GPL(klp_disable_patch);



static int __klp_enable_patch(struct klp_patch *patch)

{

	struct klp_object *obj;

	int ret;



	if (klp_transition_patch)

		return -EBUSY;



	if (WARN_ON(patch->enabled))

		return -EINVAL;



	/* enforce stacking: only the first disabled patch can be enabled */

	if (patch->list.prev != &klp_patches &&

	    !list_prev_entry(patch, list)->enabled)

		return -EBUSY;



	/*

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

	 * unloaded.

	 */

	if (!try_module_get(patch->mod))

		return -ENODEV;



	pr_notice("enabling patch '%s'\n", patch->mod->name);



	klp_init_transition(patch, KLP_PATCHED);



	/*

	 * Enforce the order of the func->transition writes in

	 * klp_init_transition() and the ops->func_stack writes in

	 * klp_patch_object(), so that klp_ftrace_handler() will see the

	 * func->transition updates before the handler is registered and the

	 * new funcs become visible to the handler.

	 */

	smp_wmb();



	klp_for_each_object(patch, obj) {

		if (!klp_is_object_loaded(obj))

			continue;



		ret = klp_pre_patch_callback(obj);

		if (ret) {

			pr_warn("pre-patch callback failed for object '%s'\n",

				klp_is_module(obj) ? obj->name : "vmlinux");

			goto err;

		}



		ret = klp_patch_object(obj);

		if (ret) {

			pr_warn("failed to patch object '%s'\n",

				klp_is_module(obj) ? obj->name : "vmlinux");

			goto err;

		}

	}



	klp_start_transition();

	klp_try_complete_transition();

	patch->enabled = true;



	return 0;

err:

	pr_warn("failed to enable patch '%s'\n", patch->mod->name);



	klp_cancel_transition();

	return ret;

}



/**

 * klp_enable_patch() - enables a registered patch

 * @patch:	The registered, disabled patch to be enabled

 *

 * Performs the needed symbol lookups and code relocations,

 * then registers the patched functions with ftrace.

 *

 * Return: 0 on success, otherwise error

 */

int klp_enable_patch(struct klp_patch *patch)

{

	int ret;



	mutex_lock(&klp_mutex);



	if (!klp_is_patch_registered(patch)) {

		ret = -EINVAL;

		goto err;

	}



	ret = __klp_enable_patch(patch);



err:

	mutex_unlock(&klp_mutex);

	return ret;

}

EXPORT_SYMBOL_GPL(klp_enable_patch);



/*

 * Sysfs Interface

 *
@@ -454,6 +290,8 @@ EXPORT_SYMBOL_GPL(klp_enable_patch); 
 * /sys/kernel/livepatch/<patch>/<object>

 * /sys/kernel/livepatch/<patch>/<object>/<function,sympos>

 */

static int __klp_disable_patch(struct klp_patch *patch);

static int __klp_enable_patch(struct klp_patch *patch);



static ssize_t enabled_store(struct kobject *kobj, struct kobj_attribute *attr,

			     const char *buf, size_t count)
@@ -904,6 +742,170 @@ int klp_register_patch(struct klp_patch *patch) 
}

EXPORT_SYMBOL_GPL(klp_register_patch);



static int __klp_disable_patch(struct klp_patch *patch)

{

	struct klp_object *obj;



	if (WARN_ON(!patch->enabled))

		return -EINVAL;



	if (klp_transition_patch)

		return -EBUSY;



	/* enforce stacking: only the last enabled patch can be disabled */

	if (!list_is_last(&patch->list, &klp_patches) &&

	    list_next_entry(patch, list)->enabled)

		return -EBUSY;



	klp_init_transition(patch, KLP_UNPATCHED);



	klp_for_each_object(patch, obj)

		if (obj->patched)

			klp_pre_unpatch_callback(obj);



	/*

	 * Enforce the order of the func->transition writes in

	 * klp_init_transition() and the TIF_PATCH_PENDING writes in

	 * klp_start_transition().  In the rare case where klp_ftrace_handler()

	 * is called shortly after klp_update_patch_state() switches the task,

	 * this ensures the handler sees that func->transition is set.

	 */

	smp_wmb();



	klp_start_transition();

	klp_try_complete_transition();

	patch->enabled = false;



	return 0;

}



/**

 * klp_disable_patch() - disables a registered patch

 * @patch:	The registered, enabled patch to be disabled

 *

 * Unregisters the patched functions from ftrace.

 *

 * Return: 0 on success, otherwise error

 */

int klp_disable_patch(struct klp_patch *patch)

{

	int ret;



	mutex_lock(&klp_mutex);



	if (!klp_is_patch_registered(patch)) {

		ret = -EINVAL;

		goto err;

	}



	if (!patch->enabled) {

		ret = -EINVAL;

		goto err;

	}



	ret = __klp_disable_patch(patch);



err:

	mutex_unlock(&klp_mutex);

	return ret;

}

EXPORT_SYMBOL_GPL(klp_disable_patch);



static int __klp_enable_patch(struct klp_patch *patch)

{

	struct klp_object *obj;

	int ret;



	if (klp_transition_patch)

		return -EBUSY;



	if (WARN_ON(patch->enabled))

		return -EINVAL;



	/* enforce stacking: only the first disabled patch can be enabled */

	if (patch->list.prev != &klp_patches &&

	    !list_prev_entry(patch, list)->enabled)

		return -EBUSY;



	/*

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

	 * unloaded.

	 */

	if (!try_module_get(patch->mod))

		return -ENODEV;



	pr_notice("enabling patch '%s'\n", patch->mod->name);



	klp_init_transition(patch, KLP_PATCHED);



	/*

	 * Enforce the order of the func->transition writes in

	 * klp_init_transition() and the ops->func_stack writes in

	 * klp_patch_object(), so that klp_ftrace_handler() will see the

	 * func->transition updates before the handler is registered and the

	 * new funcs become visible to the handler.

	 */

	smp_wmb();



	klp_for_each_object(patch, obj) {

		if (!klp_is_object_loaded(obj))

			continue;



		ret = klp_pre_patch_callback(obj);

		if (ret) {

			pr_warn("pre-patch callback failed for object '%s'\n",

				klp_is_module(obj) ? obj->name : "vmlinux");

			goto err;

		}



		ret = klp_patch_object(obj);

		if (ret) {

			pr_warn("failed to patch object '%s'\n",

				klp_is_module(obj) ? obj->name : "vmlinux");

			goto err;

		}

	}



	klp_start_transition();

	klp_try_complete_transition();

	patch->enabled = true;



	return 0;

err:

	pr_warn("failed to enable patch '%s'\n", patch->mod->name);



	klp_cancel_transition();

	return ret;

}



/**

 * klp_enable_patch() - enables a registered patch

 * @patch:	The registered, disabled patch to be enabled

 *

 * Performs the needed symbol lookups and code relocations,

 * then registers the patched functions with ftrace.

 *

 * Return: 0 on success, otherwise error

 */

int klp_enable_patch(struct klp_patch *patch)

{

	int ret;



	mutex_lock(&klp_mutex);



	if (!klp_is_patch_registered(patch)) {

		ret = -EINVAL;

		goto err;

	}



	ret = __klp_enable_patch(patch);



err:

	mutex_unlock(&klp_mutex);

	return ret;

}

EXPORT_SYMBOL_GPL(klp_enable_patch);



/*

 * Remove parts of patches that touch a given kernel module. The list of

 * patches processed might be limited. When limit is NULL, all patches

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