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Commit 0937e3b0 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Jiri Kosina
Browse files

livepatch: simplify disable error path 



If registering the function with ftrace has previously succeeded,
unregistering will almost never fail.  Even if it does, it's not a fatal
error.  We can still carry on and disable the klp_func from being used
by removing it from the klp_ops func stack.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.cz>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 4421f8f0

kernel/livepatch/core.c

+17 −50
Original line number Original line Diff line number Diff line
@@ -322,32 +322,20 @@ static void notrace klp_ftrace_handler(unsigned long ip, 
	klp_arch_set_pc(regs, (unsigned long)func->new_func);

	klp_arch_set_pc(regs, (unsigned long)func->new_func);

}

}





static int klp_disable_func(struct klp_func *func)

static void klp_disable_func(struct klp_func *func)

{

{

	struct klp_ops *ops;

	struct klp_ops *ops;

	int ret;



	if (WARN_ON(func->state != KLP_ENABLED))

		return -EINVAL;





	if (WARN_ON(!func->old_addr))

	WARN_ON(func->state != KLP_ENABLED);

		return -EINVAL;

	WARN_ON(!func->old_addr);





	ops = klp_find_ops(func->old_addr);

	ops = klp_find_ops(func->old_addr);

	if (WARN_ON(!ops))

	if (WARN_ON(!ops))

		return -EINVAL;

		return;





	if (list_is_singular(&ops->func_stack)) {

	if (list_is_singular(&ops->func_stack)) {

		ret = unregister_ftrace_function(&ops->fops);

		WARN_ON(unregister_ftrace_function(&ops->fops));

		if (ret) {

		WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));

			pr_err("failed to unregister ftrace handler for function '%s' (%d)\n",

			       func->old_name, ret);

			return ret;

		}



		ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);

		if (ret)

			pr_warn("function unregister succeeded but failed to clear the filter\n");





		list_del_rcu(&func->stack_node);

		list_del_rcu(&func->stack_node);

		list_del(&ops->node);

		list_del(&ops->node);
@@ -357,8 +345,6 @@ static int klp_disable_func(struct klp_func *func) 
	}

	}





	func->state = KLP_DISABLED;

	func->state = KLP_DISABLED;



	return 0;

}

}





static int klp_enable_func(struct klp_func *func)

static int klp_enable_func(struct klp_func *func)
@@ -419,23 +405,15 @@ err: 
	return ret;

	return ret;

}

}





static int klp_disable_object(struct klp_object *obj)

static void klp_disable_object(struct klp_object *obj)

{

{

	struct klp_func *func;

	struct klp_func *func;

	int ret;





	for (func = obj->funcs; func->old_name; func++) {

	for (func = obj->funcs; func->old_name; func++)

		if (func->state != KLP_ENABLED)

		if (func->state == KLP_ENABLED)

			continue;

			klp_disable_func(func);



		ret = klp_disable_func(func);

		if (ret)

			return ret;

	}





	obj->state = KLP_DISABLED;

	obj->state = KLP_DISABLED;



	return 0;

}

}





static int klp_enable_object(struct klp_object *obj)

static int klp_enable_object(struct klp_object *obj)
@@ -451,22 +429,19 @@ static int klp_enable_object(struct klp_object *obj) 




	for (func = obj->funcs; func->old_name; func++) {

	for (func = obj->funcs; func->old_name; func++) {

		ret = klp_enable_func(func);

		ret = klp_enable_func(func);

		if (ret)

		if (ret) {

			goto unregister;

			klp_disable_object(obj);

			return ret;

		}

	}

	}

	obj->state = KLP_ENABLED;

	obj->state = KLP_ENABLED;





	return 0;

	return 0;



unregister:

	WARN_ON(klp_disable_object(obj));

	return ret;

}

}





static int __klp_disable_patch(struct klp_patch *patch)

static int __klp_disable_patch(struct klp_patch *patch)

{

{

	struct klp_object *obj;

	struct klp_object *obj;

	int ret;





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

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

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

	if (!list_is_last(&patch->list, &klp_patches) &&
@@ -476,12 +451,8 @@ static int __klp_disable_patch(struct klp_patch *patch) 
	pr_notice("disabling patch '%s'\n", patch->mod->name);

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





	for (obj = patch->objs; obj->funcs; obj++) {

	for (obj = patch->objs; obj->funcs; obj++) {

		if (obj->state != KLP_ENABLED)

		if (obj->state == KLP_ENABLED)

			continue;

			klp_disable_object(obj);



		ret = klp_disable_object(obj);

		if (ret)

			return ret;

	}

	}





	patch->state = KLP_DISABLED;

	patch->state = KLP_DISABLED;
@@ -931,7 +902,6 @@ static void klp_module_notify_going(struct klp_patch *patch, 
{

{

	struct module *pmod = patch->mod;

	struct module *pmod = patch->mod;

	struct module *mod = obj->mod;

	struct module *mod = obj->mod;

	int ret;





	if (patch->state == KLP_DISABLED)

	if (patch->state == KLP_DISABLED)

		goto disabled;

		goto disabled;
@@ -939,10 +909,7 @@ static void klp_module_notify_going(struct klp_patch *patch, 
	pr_notice("reverting patch '%s' on unloading module '%s'\n",

	pr_notice("reverting patch '%s' on unloading module '%s'\n",

		  pmod->name, mod->name);

		  pmod->name, mod->name);





	ret = klp_disable_object(obj);

	klp_disable_object(obj);

	if (ret)

		pr_warn("failed to revert patch '%s' on module '%s' (%d)\n",

			pmod->name, mod->name, ret);





disabled:

disabled:

	klp_free_object_loaded(obj);

	klp_free_object_loaded(obj);