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// 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>
/*
* 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;
}
static struct klp_func funcs[] = {
{
.old_name = "cmdline_proc_show",
.new_func = livepatch_cmdline_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)
{
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");
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