livepatch: introduce patch/func-walking helpers
[cascardo/linux.git] / kernel / livepatch / core.c
index 3f9f1d6..c38398e 100644 (file)
@@ -128,7 +128,7 @@ static bool klp_is_patch_registered(struct klp_patch *patch)
 
 static bool klp_initialized(void)
 {
-       return klp_root_kobj;
+       return !!klp_root_kobj;
 }
 
 struct klp_find_arg {
@@ -335,32 +335,20 @@ unlock:
        rcu_read_unlock();
 }
 
-static int klp_disable_func(struct klp_func *func)
+static void klp_disable_func(struct klp_func *func)
 {
        struct klp_ops *ops;
-       int ret;
-
-       if (WARN_ON(func->state != KLP_ENABLED))
-               return -EINVAL;
 
-       if (WARN_ON(!func->old_addr))
-               return -EINVAL;
+       WARN_ON(func->state != KLP_ENABLED);
+       WARN_ON(!func->old_addr);
 
        ops = klp_find_ops(func->old_addr);
        if (WARN_ON(!ops))
-               return -EINVAL;
+               return;
 
        if (list_is_singular(&ops->func_stack)) {
-               ret = unregister_ftrace_function(&ops->fops);
-               if (ret) {
-                       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");
+               WARN_ON(unregister_ftrace_function(&ops->fops));
+               WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
 
                list_del_rcu(&func->stack_node);
                list_del(&ops->node);
@@ -370,8 +358,6 @@ static int klp_disable_func(struct klp_func *func)
        }
 
        func->state = KLP_DISABLED;
-
-       return 0;
 }
 
 static int klp_enable_func(struct klp_func *func)
@@ -432,23 +418,15 @@ err:
        return ret;
 }
 
-static int klp_disable_object(struct klp_object *obj)
+static void klp_disable_object(struct klp_object *obj)
 {
        struct klp_func *func;
-       int ret;
 
-       for (func = obj->funcs; func->old_name; func++) {
-               if (func->state != KLP_ENABLED)
-                       continue;
-
-               ret = klp_disable_func(func);
-               if (ret)
-                       return ret;
-       }
+       klp_for_each_func(obj, func)
+               if (func->state == KLP_ENABLED)
+                       klp_disable_func(func);
 
        obj->state = KLP_DISABLED;
-
-       return 0;
 }
 
 static int klp_enable_object(struct klp_object *obj)
@@ -462,24 +440,21 @@ static int klp_enable_object(struct klp_object *obj)
        if (WARN_ON(!klp_is_object_loaded(obj)))
                return -EINVAL;
 
-       for (func = obj->funcs; func->old_name; func++) {
+       klp_for_each_func(obj, func) {
                ret = klp_enable_func(func);
-               if (ret)
-                       goto unregister;
+               if (ret) {
+                       klp_disable_object(obj);
+                       return ret;
+               }
        }
        obj->state = KLP_ENABLED;
 
        return 0;
-
-unregister:
-       WARN_ON(klp_disable_object(obj));
-       return ret;
 }
 
 static int __klp_disable_patch(struct klp_patch *patch)
 {
        struct klp_object *obj;
-       int ret;
 
        /* enforce stacking: only the last enabled patch can be disabled */
        if (!list_is_last(&patch->list, &klp_patches) &&
@@ -488,13 +463,9 @@ static int __klp_disable_patch(struct klp_patch *patch)
 
        pr_notice("disabling patch '%s'\n", patch->mod->name);
 
-       for (obj = patch->objs; obj->funcs; obj++) {
-               if (obj->state != KLP_ENABLED)
-                       continue;
-
-               ret = klp_disable_object(obj);
-               if (ret)
-                       return ret;
+       klp_for_each_object(patch, obj) {
+               if (obj->state == KLP_ENABLED)
+                       klp_disable_object(obj);
        }
 
        patch->state = KLP_DISABLED;
@@ -552,9 +523,7 @@ static int __klp_enable_patch(struct klp_patch *patch)
 
        pr_notice("enabling patch '%s'\n", patch->mod->name);
 
-       for (obj = patch->objs; obj->funcs; obj++) {
-               klp_find_object_module(obj);
-
+       klp_for_each_object(patch, obj) {
                if (!klp_is_object_loaded(obj))
                        continue;
 
@@ -682,6 +651,15 @@ static struct kobj_type klp_ktype_patch = {
        .default_attrs = klp_patch_attrs,
 };
 
+static void klp_kobj_release_object(struct kobject *kobj)
+{
+}
+
+static struct kobj_type klp_ktype_object = {
+       .release = klp_kobj_release_object,
+       .sysfs_ops = &kobj_sysfs_ops,
+};
+
 static void klp_kobj_release_func(struct kobject *kobj)
 {
 }
@@ -711,7 +689,7 @@ static void klp_free_object_loaded(struct klp_object *obj)
 
        obj->mod = NULL;
 
-       for (func = obj->funcs; func->old_name; func++)
+       klp_for_each_func(obj, func)
                func->old_addr = 0;
 }
 
@@ -726,7 +704,7 @@ static void klp_free_objects_limited(struct klp_patch *patch,
 
        for (obj = patch->objs; obj->funcs && obj != limit; obj++) {
                klp_free_funcs_limited(obj, NULL);
-               kobject_put(obj->kobj);
+               kobject_put(&obj->kobj);
        }
 }
 
@@ -744,7 +722,7 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
        func->state = KLP_DISABLED;
 
        return kobject_init_and_add(&func->kobj, &klp_ktype_func,
-                                   obj->kobj, "%s", func->old_name);
+                                   &obj->kobj, "%s", func->old_name);
 }
 
 /* parts of the initialization that is done only when the object is loaded */
@@ -760,7 +738,7 @@ static int klp_init_object_loaded(struct klp_patch *patch,
                        return ret;
        }
 
-       for (func = obj->funcs; func->old_name; func++) {
+       klp_for_each_func(obj, func) {
                ret = klp_find_verify_func_addr(obj, func);
                if (ret)
                        return ret;
@@ -784,11 +762,12 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
        klp_find_object_module(obj);
 
        name = klp_is_module(obj) ? obj->name : "vmlinux";
-       obj->kobj = kobject_create_and_add(name, &patch->kobj);
-       if (!obj->kobj)
-               return -ENOMEM;
+       ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object,
+                                  &patch->kobj, "%s", name);
+       if (ret)
+               return ret;
 
-       for (func = obj->funcs; func->old_name; func++) {
+       klp_for_each_func(obj, func) {
                ret = klp_init_func(obj, func);
                if (ret)
                        goto free;
@@ -804,7 +783,7 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
 
 free:
        klp_free_funcs_limited(obj, func);
-       kobject_put(obj->kobj);
+       kobject_put(&obj->kobj);
        return ret;
 }
 
@@ -825,7 +804,7 @@ static int klp_init_patch(struct klp_patch *patch)
        if (ret)
                goto unlock;
 
-       for (obj = patch->objs; obj->funcs; obj++) {
+       klp_for_each_object(patch, obj) {
                ret = klp_init_object(patch, obj);
                if (ret)
                        goto free;
@@ -914,7 +893,7 @@ int klp_register_patch(struct klp_patch *patch)
 }
 EXPORT_SYMBOL_GPL(klp_register_patch);
 
-static void klp_module_notify_coming(struct klp_patch *patch,
+static int klp_module_notify_coming(struct klp_patch *patch,
                                     struct klp_object *obj)
 {
        struct module *pmod = patch->mod;
@@ -922,22 +901,23 @@ static void klp_module_notify_coming(struct klp_patch *patch,
        int ret;
 
        ret = klp_init_object_loaded(patch, obj);
-       if (ret)
-               goto err;
+       if (ret) {
+               pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+                       pmod->name, mod->name, ret);
+               return ret;
+       }
 
        if (patch->state == KLP_DISABLED)
-               return;
+               return 0;
 
        pr_notice("applying patch '%s' to loading module '%s'\n",
                  pmod->name, mod->name);
 
        ret = klp_enable_object(obj);
-       if (!ret)
-               return;
-
-err:
-       pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
-               pmod->name, mod->name, ret);
+       if (ret)
+               pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+                       pmod->name, mod->name, ret);
+       return ret;
 }
 
 static void klp_module_notify_going(struct klp_patch *patch,
@@ -945,7 +925,6 @@ static void klp_module_notify_going(struct klp_patch *patch,
 {
        struct module *pmod = patch->mod;
        struct module *mod = obj->mod;
-       int ret;
 
        if (patch->state == KLP_DISABLED)
                goto disabled;
@@ -953,10 +932,7 @@ static void klp_module_notify_going(struct klp_patch *patch,
        pr_notice("reverting patch '%s' on unloading module '%s'\n",
                  pmod->name, mod->name);
 
-       ret = klp_disable_object(obj);
-       if (ret)
-               pr_warn("failed to revert patch '%s' on module '%s' (%d)\n",
-                       pmod->name, mod->name, ret);
+       klp_disable_object(obj);
 
 disabled:
        klp_free_object_loaded(obj);
@@ -965,6 +941,7 @@ disabled:
 static int klp_module_notify(struct notifier_block *nb, unsigned long action,
                             void *data)
 {
+       int ret;
        struct module *mod = data;
        struct klp_patch *patch;
        struct klp_object *obj;
@@ -984,13 +961,18 @@ static int klp_module_notify(struct notifier_block *nb, unsigned long action,
                mod->klp_alive = false;
 
        list_for_each_entry(patch, &klp_patches, list) {
-               for (obj = patch->objs; obj->funcs; obj++) {
+               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;
-                               klp_module_notify_coming(patch, obj);
+                               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);