// SPDX-License-Identifier: GPL-2.0// Copyright (C) 2019 SUSE #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/slab.h>#include <linux/module.h>#include <linux/kernel.h>#include <linux/printk.h>#include <linux/livepatch.h> #define CONSOLE_LOGLEVEL_STATE 1/* Version 2 supports migration. */#define CONSOLE_LOGLEVEL_STATE_VERSION 2 static const char *const module_state[] = {	[MODULE_STATE_LIVE]	= "[MODULE_STATE_LIVE] Normal state",	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",}; static void callback_info(const char *callback, struct klp_object *obj){	if (obj->mod)		pr_info("%s: %s -> %s\n", callback, obj->mod->name,			module_state[obj->mod->state]);	else		pr_info("%s: vmlinux\n", callback);} static struct klp_patch patch; static int allocate_loglevel_state(void){	struct klp_state *loglevel_state, *prev_loglevel_state; 	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);	if (prev_loglevel_state) {		pr_info("%s: space to store console_loglevel already allocated\n",		__func__);		return 0;	} 	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);	if (!loglevel_state)		return -EINVAL; 	loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);	if (!loglevel_state->data)		return -ENOMEM; 	pr_info("%s: allocating space to store console_loglevel\n",		__func__);	return 0;} static void fix_console_loglevel(void){	struct klp_state *loglevel_state, *prev_loglevel_state; 	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);	if (!loglevel_state)		return; 	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);	if (prev_loglevel_state) {		pr_info("%s: taking over the console_loglevel change\n",		__func__);		loglevel_state->data = prev_loglevel_state->data;		return;	} 	pr_info("%s: fixing console_loglevel\n", __func__);	*(int *)loglevel_state->data = console_loglevel;	console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;} static void restore_console_loglevel(void){	struct klp_state *loglevel_state, *prev_loglevel_state; 	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);	if (prev_loglevel_state) {		pr_info("%s: passing the console_loglevel change back to the old livepatch\n",		__func__);		return;	} 	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);	if (!loglevel_state)		return; 	pr_info("%s: restoring console_loglevel\n", __func__);	console_loglevel = *(int *)loglevel_state->data;} static void free_loglevel_state(void){	struct klp_state *loglevel_state, *prev_loglevel_state; 	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);	if (prev_loglevel_state) {		pr_info("%s: keeping space to store console_loglevel\n",		__func__);		return;	} 	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);	if (!loglevel_state)		return; 	pr_info("%s: freeing space for the stored console_loglevel\n",		__func__);	kfree(loglevel_state->data);} /* Executed on object patching (ie, patch enablement) */static int pre_patch_callback(struct klp_object *obj){	callback_info(__func__, obj);	return allocate_loglevel_state();} /* Executed on object unpatching (ie, patch disablement) */static void post_patch_callback(struct klp_object *obj){	callback_info(__func__, obj);	fix_console_loglevel();} /* Executed on object unpatching (ie, patch disablement) */static void pre_unpatch_callback(struct klp_object *obj){	callback_info(__func__, obj);	restore_console_loglevel();} /* Executed on object unpatching (ie, patch disablement) */static void post_unpatch_callback(struct klp_object *obj){	callback_info(__func__, obj);	free_loglevel_state();} static struct klp_func no_funcs[] = {	{}}; static struct klp_object objs[] = {	{		.name = NULL,	/* vmlinux */		.funcs = no_funcs,		.callbacks = {			.pre_patch = pre_patch_callback,			.post_patch = post_patch_callback,			.pre_unpatch = pre_unpatch_callback,			.post_unpatch = post_unpatch_callback,		},	}, { }}; static struct klp_state states[] = {	{		.id = CONSOLE_LOGLEVEL_STATE,		.version = CONSOLE_LOGLEVEL_STATE_VERSION,	}, { }}; static struct klp_patch patch = {	.mod = THIS_MODULE,	.objs = objs,	.states = states,	.replace = true,}; static int test_klp_callbacks_demo_init(void){	return klp_enable_patch(&patch);} static void test_klp_callbacks_demo_exit(void){} module_init(test_klp_callbacks_demo_init);module_exit(test_klp_callbacks_demo_exit);MODULE_LICENSE("GPL");MODULE_INFO(livepatch, "Y");MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>");MODULE_DESCRIPTION("Livepatch test: system state modification");