// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * livepatch-sample.c - Kernel Live Patching Sample Module
 *
 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/livepatch.h>

#include <linux/sched.h>
#include <linux/sched/loadavg.h>
#include <linux/sched/stat.h>
#include <linux/pid_namespace.h>
#include <linux/proc_fs.h>

/*
 * This (dumb) live patch overrides the function that prints the
 * kernel boot cmdline when /proc/cmdline is read.
 *
 * Example:
 *
 * $ cat /proc/cmdline
 * <your cmdline>
 *
 * $ insmod livepatch-sample.ko
 * $ cat /proc/cmdline
 * this has been live patched
 *
 * $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled
 * $ cat /proc/cmdline
 * <your cmdline>
 */

#include <linux/seq_file.h>
static int livepatch_cmdline_proc_show(struct seq_file *m, void *v)
{
	seq_printf(m, "%s\n", "this has been live patched");
	return 0;
}


#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)

static int livepatch_loadavg_proc_show(struct seq_file *m, void *v) 
{
	unsigned long avnrun[3];

#if 0
    get_avenrun(avnrun, FIXED_1/200, 0); 

	seq_printf(m, "RongTao: %lu.%02lu %lu.%02lu %lu.%02lu %ld/%d %d\n",
        LOAD_INT(avnrun[0]), LOAD_FRAC(avnrun[0]),
        LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
        LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]),
        nr_running(), nr_threads,
        idr_get_cursor(&task_active_pid_ns(current)->idr) - 1); 
#elif 0
	seq_printf(m, "RongTao: %lu.%02lu %lu.%02lu %lu.%02lu\n",
		   LOAD_INT(avnrun[0]), LOAD_FRAC(avnrun[0]),
		   LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]),
		   LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]));
#else
	seq_printf(m, "RongTao: 11111\n");
#endif
	    return 0;
}

/**
 *  补丁函数
 */
static struct klp_func funcs[] = {
	{
		.old_name = "cmdline_proc_show",
		.new_func = livepatch_cmdline_proc_show,
	},
	{
		.old_name = "loadavg_proc_show",
		.new_func = livepatch_loadavg_proc_show,
	}, { }
};

static struct klp_object objs[] = {
	{
		/* name being NULL means vmlinux */
		.funcs = funcs,
	}, { }
};

static struct klp_patch patch = {
	.mod = THIS_MODULE,
	.objs = objs,
};

static int livepatch_init(void)
{
    /**
     *  使能补丁
     */
	return klp_enable_patch(&patch);
}

static void livepatch_exit(void)
{
}

module_init(livepatch_init);
module_exit(livepatch_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");