/*

 * Copyright (C) 2013-2014 Josh Poimboeuf <jpoimboe@redhat.com>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA,

 * 02110-1301, USA.

 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>

#include <linux/printk.h>

#include <linux/slab.h>

#include <linux/kallsyms.h>

#include "kpatch.h"

#include "kpatch-patch.h"

static bool replace;

module_param(replace, bool, S_IRUGO);

MODULE_PARM_DESC(replace, "replace all previously loaded patch modules");

extern struct kpatch_patch_func __kpatch_funcs[], __kpatch_funcs_end[];

extern struct kpatch_patch_dynrela __kpatch_dynrelas[], __kpatch_dynrelas_end[];

extern struct kpatch_pre_patch_callback __kpatch_callbacks_pre_patch[], __kpatch_callbacks_pre_patch_end[];

extern struct kpatch_post_patch_callback __kpatch_callbacks_post_patch[], __kpatch_callbacks_post_patch_end[];

extern struct kpatch_pre_unpatch_callback __kpatch_callbacks_pre_unpatch[], __kpatch_callbacks_pre_unpatch_end[];

extern struct kpatch_post_unpatch_callback __kpatch_callbacks_post_unpatch[], __kpatch_callbacks_post_unpatch_end[];

extern unsigned long __kpatch_force_funcs[], __kpatch_force_funcs_end[];

extern char __kpatch_checksum[];

static struct kpatch_module kpmod;

static ssize_t patch_enabled_show(struct kobject *kobj,

				  struct kobj_attribute *attr, char *buf)

{

	return sprintf(buf, "%d\n", kpmod.enabled);

}

static ssize_t patch_enabled_store(struct kobject *kobj,

				   struct kobj_attribute *attr, const char *buf,

				   size_t count)

{

	int ret;

	unsigned long val;

	ret = kstrtoul(buf, 10, &val;;

	if (ret)

		return ret;

	val = !!val;

	if (val)

		ret = kpatch_register(&kpmod, replace);

	else

		ret = kpatch_unregister(&kpmod);

	if (ret)

		return ret;

	return count;

}

static ssize_t patch_checksum_show(struct kobject *kobj,

				   struct kobj_attribute *attr, char *buf)

{

	return snprintf(buf, PAGE_SIZE, "%s\n", __kpatch_checksum);

}

static struct kobj_attribute patch_enabled_attr =

	__ATTR(enabled, 0644, patch_enabled_show, patch_enabled_store);

static struct kobj_attribute patch_checksum_attr =

	__ATTR(checksum, 0444, patch_checksum_show, NULL);

static struct attribute *patch_attrs[] = {

	&patch_enabled_attr.attr,

	&patch_checksum_attr.attr,

	NULL,

};

static void patch_kobj_free(struct kobject *kobj)

{

}

static struct kobj_type patch_ktype = {

        .release = patch_kobj_free,

        .sysfs_ops = &kobj_sysfs_ops,

        .default_attrs = patch_attrs,

};

static ssize_t patch_func_old_addr_show(struct kobject *kobj,

					struct kobj_attribute *attr, char *buf)

{

	struct kpatch_func *func =

		container_of(kobj, struct kpatch_func, kobj);

	return sprintf(buf, "0x%lx\n", func->old_addr);

}

static ssize_t patch_func_new_addr_show(struct kobject *kobj,

					struct kobj_attribute *attr, char *buf)

{

	struct kpatch_func *func =

		container_of(kobj, struct kpatch_func, kobj);

	return sprintf(buf, "0x%lx\n", func->new_addr);

}

static struct kobj_attribute patch_old_addr_attr =

	__ATTR(old_addr, S_IRUSR, patch_func_old_addr_show, NULL);

static struct kobj_attribute patch_new_addr_attr =

	__ATTR(new_addr, S_IRUSR, patch_func_new_addr_show, NULL);

static struct attribute *patch_func_kobj_attrs[] = {

	&patch_old_addr_attr.attr,

	&patch_new_addr_attr.attr,

	NULL,

};

static ssize_t patch_func_kobj_show(struct kobject *kobj,

				    struct attribute *attr, char *buf)

{

	struct kobj_attribute *func_attr =

		container_of(attr, struct kobj_attribute, attr);

	return func_attr->show(kobj, func_attr, buf);

}

static const struct sysfs_ops patch_func_sysfs_ops = {

	.show	= patch_func_kobj_show,

};

static void patch_func_kobj_free(struct kobject *kobj)

{

	struct kpatch_func *func =

		container_of(kobj, struct kpatch_func, kobj);

	kfree(func);

}

static struct kobj_type patch_func_ktype = {

	.release	= patch_func_kobj_free,

	.sysfs_ops	= &patch_func_sysfs_ops,

	.default_attrs	= patch_func_kobj_attrs,

};

static void patch_object_kobj_free(struct kobject *kobj)

{

	struct kpatch_object *obj =

		container_of(kobj, struct kpatch_object, kobj);

	kfree(obj);

}

static struct kobj_type patch_object_ktype = {

	.release = patch_object_kobj_free,

	.sysfs_ops = &kobj_sysfs_ops,

};

static struct kpatch_object *patch_find_or_add_object(struct list_head *head,

						      const char *name)

{

	struct kpatch_object *object;

	int ret;

	list_for_each_entry(object, head, list) {

		if (!strcmp(object->name, name))

			return object;

	}

	object = kzalloc(sizeof(*object), GFP_KERNEL);

	if (!object)

		return NULL;

	object->name = name;

	INIT_LIST_HEAD(&object->funcs);

	INIT_LIST_HEAD(&object->dynrelas);

	list_add_tail(&object->list, head);

	ret = kobject_init_and_add(&object->kobj, &patch_object_ktype,

				   &kpmod.kobj, "%s", object->name);

	if (ret) {

		list_del(&object->list);

		kfree(object);

		return NULL;

	}

	return object;

}

static void patch_free_objects(void)

{

	struct kpatch_object *object, *object_safe;

	struct kpatch_func *func, *func_safe;

	struct kpatch_dynrela *dynrela, *dynrela_safe;

	list_for_each_entry_safe(object, object_safe, &kpmod.objects, list) {

		list_for_each_entry_safe(func, func_safe, &object->funcs,

					 list) {

			list_del(&func->list);

			kobject_put(&func->kobj);

		}

		list_for_each_entry_safe(dynrela, dynrela_safe,

					 &object->dynrelas, list) {

			list_del(&dynrela->list);

			kfree(dynrela);

		}

		list_del(&object->list);

		kobject_put(&object->kobj);

	}

}

static int patch_is_func_forced(unsigned long addr)

{

	unsigned long *a;

	for (a = __kpatch_force_funcs; a < __kpatch_force_funcs_end; a++)

		if (*a == addr)

			return 1;

	return 0;

}

static int patch_make_funcs_list(struct list_head *objects)

{

	struct kpatch_object *object;

	struct kpatch_patch_func *p_func;

	struct kpatch_func *func;

	int ret;

	for (p_func = __kpatch_funcs; p_func < __kpatch_funcs_end; p_func++) {

		object = patch_find_or_add_object(&kpmod.objects,

						  p_func->objname);

		if (!object)

			return -ENOMEM;

		func = kzalloc(sizeof(*func), GFP_KERNEL);

		if (!func)

			return -ENOMEM;

		func->new_addr = p_func->new_addr;

		func->new_size = p_func->new_size;

		func->old_size = p_func->old_size;

		func->sympos = p_func->sympos;

		func->name = p_func->name;

		func->force = patch_is_func_forced(func->new_addr);

		list_add_tail(&func->list, &object->funcs);

		ret = kobject_init_and_add(&func->kobj, &patch_func_ktype,

					   &object->kobj, "%s,%lu",

					   func->name, func->sympos ? func->sympos : 1);

		if (ret)

			return ret;

	}

	return 0;

}

static int patch_make_dynrelas_list(struct list_head *objects)

{

	struct kpatch_object *object;

	struct kpatch_patch_dynrela *p_dynrela;

	struct kpatch_dynrela *dynrela;

	for (p_dynrela = __kpatch_dynrelas; p_dynrela < __kpatch_dynrelas_end;

	     p_dynrela++) {

		object = patch_find_or_add_object(objects, p_dynrela->objname);

		if (!object)

			return -ENOMEM;

		dynrela = kzalloc(sizeof(*dynrela), GFP_KERNEL);

		if (!dynrela)

			return -ENOMEM;

		dynrela->dest = p_dynrela->dest;

		dynrela->type = p_dynrela->type;

		dynrela->sympos = p_dynrela->sympos;

		dynrela->name = p_dynrela->name;

		dynrela->external = p_dynrela->external;

		dynrela->addend = p_dynrela->addend;

		list_add_tail(&dynrela->list, &object->dynrelas);

	}

	return 0;

}

static int patch_set_callbacks(struct list_head *objects)

{

	struct kpatch_pre_patch_callback *p_pre_patch_callback;

	struct kpatch_post_patch_callback *p_post_patch_callback;

	struct kpatch_pre_unpatch_callback *p_pre_unpatch_callback;

	struct kpatch_post_unpatch_callback *p_post_unpatch_callback;

	struct kpatch_object *object;

	for (p_pre_patch_callback = __kpatch_callbacks_pre_patch;

	     p_pre_patch_callback < __kpatch_callbacks_pre_patch_end;

	     p_pre_patch_callback++) {

		object = patch_find_or_add_object(objects, p_pre_patch_callback->objname);

		if (!object)

			return -ENOMEM;

		if (object->pre_patch_callback) {

			pr_err("extra pre-patch callback for object: %s\n",

				object->name);

			return -EINVAL;

		}

		object->pre_patch_callback =

			(int (*)(struct kpatch_object *)) p_pre_patch_callback->callback;

	}

	for (p_post_patch_callback = __kpatch_callbacks_post_patch;

	     p_post_patch_callback < __kpatch_callbacks_post_patch_end;

	     p_post_patch_callback++) {

		object = patch_find_or_add_object(objects, p_post_patch_callback->objname);

		if (!object)

			return -ENOMEM;

		if (object->post_patch_callback) {

			pr_err("extra post-patch callback for object: %s\n",

				object->name);

			return -EINVAL;

		}

		object->post_patch_callback =

			(void (*)(struct kpatch_object *)) p_post_patch_callback->callback;

	}

	for (p_pre_unpatch_callback = __kpatch_callbacks_pre_unpatch;

	     p_pre_unpatch_callback < __kpatch_callbacks_pre_unpatch_end;

	     p_pre_unpatch_callback++) {

		object = patch_find_or_add_object(objects, p_pre_unpatch_callback->objname);

		if (!object)

			return -ENOMEM;

		if (object->pre_unpatch_callback) {

			pr_err("extra pre-unpatch callback for object: %s\n",

				object->name);

			return -EINVAL;

		}

		object->pre_unpatch_callback =

			(void (*)(struct kpatch_object *)) p_pre_unpatch_callback->callback;

	}

	for (p_post_unpatch_callback = __kpatch_callbacks_post_unpatch;

	     p_post_unpatch_callback < __kpatch_callbacks_post_unpatch_end;

	     p_post_unpatch_callback++) {

		object = patch_find_or_add_object(objects, p_post_unpatch_callback->objname);

		if (!object)

			return -ENOMEM;

		if (object->post_unpatch_callback) {

			pr_err("extra post-unpatch callback for object: %s\n",

				object->name);

			return -EINVAL;

		}

		object->post_unpatch_callback =

			(void (*)(struct kpatch_object *)) p_post_unpatch_callback->callback;

	}

	return 0;

}

static int __init patch_init(void)

{

	int ret;

	ret = kobject_init_and_add(&kpmod.kobj, &patch_ktype,

				   kpatch_root_kobj, "%s",

				   THIS_MODULE->name);

	if (ret)

		return -ENOMEM;

	kpmod.mod = THIS_MODULE;

	INIT_LIST_HEAD(&kpmod.objects);

	ret = patch_make_funcs_list(&kpmod.objects);

	if (ret)

		goto err_objects;

	ret = patch_make_dynrelas_list(&kpmod.objects);

	if (ret)

		goto err_objects;

	ret = patch_set_callbacks(&kpmod.objects);

	if (ret)

		goto err_objects;

	ret = kpatch_register(&kpmod, replace);

	if (ret)

		goto err_objects;

	return 0;

err_objects:

	patch_free_objects();

	kobject_put(&kpmod.kobj);

	return ret;

}

static void __exit patch_exit(void)

{

	WARN_ON(kpmod.enabled);

	patch_free_objects();

	kobject_put(&kpmod.kobj);

}

module_init(patch_init);

module_exit(patch_exit);

MODULE_LICENSE("GPL");