linux-stable/samples/livepatch/livepatch-callbacks-demo.c
Thomas Gleixner 1ccea77e2a treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13
Based on 2 normalized pattern(s):

  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
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  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 see http www gnu org licenses

  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 [based]
  [from] [clk] [highbank] [c] you should have received a copy of the
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extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 355 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 11:28:45 +02:00

196 lines
5.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
*/
/*
* livepatch-callbacks-demo.c - (un)patching callbacks livepatch demo
*
*
* Purpose
* -------
*
* Demonstration of registering livepatch (un)patching callbacks.
*
*
* Usage
* -----
*
* Step 1 - load the simple module
*
* insmod samples/livepatch/livepatch-callbacks-mod.ko
*
*
* Step 2 - load the demonstration livepatch (with callbacks)
*
* insmod samples/livepatch/livepatch-callbacks-demo.ko
*
*
* Step 3 - cleanup
*
* echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
* rmmod livepatch_callbacks_demo
* rmmod livepatch_callbacks_mod
*
* Watch dmesg output to see livepatch enablement, callback execution
* and patching operations for both vmlinux and module targets.
*
* NOTE: swap the insmod order of livepatch-callbacks-mod.ko and
* livepatch-callbacks-demo.ko to observe what happens when a
* target module is loaded after a livepatch with callbacks.
*
* NOTE: 'pre_patch_ret' is a module parameter that sets the pre-patch
* callback return status. Try setting up a non-zero status
* such as -19 (-ENODEV):
*
* # Load demo livepatch, vmlinux is patched
* insmod samples/livepatch/livepatch-callbacks-demo.ko
*
* # Setup next pre-patch callback to return -ENODEV
* echo -19 > /sys/module/livepatch_callbacks_demo/parameters/pre_patch_ret
*
* # Module loader refuses to load the target module
* insmod samples/livepatch/livepatch-callbacks-mod.ko
* insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-mod.ko: No such device
*
* NOTE: There is a second target module,
* livepatch-callbacks-busymod.ko, available for experimenting
* with livepatch (un)patch callbacks. This module contains
* a 'sleep_secs' parameter that parks the module on one of the
* functions that the livepatch demo module wants to patch.
* Modifying this value and tweaking the order of module loads can
* effectively demonstrate stalled patch transitions:
*
* # Load a target module, let it park on 'busymod_work_func' for
* # thirty seconds
* insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=30
*
* # Meanwhile load the livepatch
* insmod samples/livepatch/livepatch-callbacks-demo.ko
*
* # ... then load and unload another target module while the
* # transition is in progress
* insmod samples/livepatch/livepatch-callbacks-mod.ko
* rmmod samples/livepatch/livepatch-callbacks-mod.ko
*
* # Finally cleanup
* echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
* rmmod samples/livepatch/livepatch-callbacks-demo.ko
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/livepatch.h>
static int pre_patch_ret;
module_param(pre_patch_ret, int, 0644);
MODULE_PARM_DESC(pre_patch_ret, "pre_patch_ret (default=0)");
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);
}
/* Executed on object patching (ie, patch enablement) */
static int pre_patch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
return pre_patch_ret;
}
/* Executed on object unpatching (ie, patch disablement) */
static void post_patch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
}
/* Executed on object unpatching (ie, patch disablement) */
static void pre_unpatch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
}
/* Executed on object unpatching (ie, patch disablement) */
static void post_unpatch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
}
static void patched_work_func(struct work_struct *work)
{
pr_info("%s\n", __func__);
}
static struct klp_func no_funcs[] = {
{ }
};
static struct klp_func busymod_funcs[] = {
{
.old_name = "busymod_work_func",
.new_func = patched_work_func,
}, { }
};
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,
},
}, {
.name = "livepatch_callbacks_mod",
.funcs = no_funcs,
.callbacks = {
.pre_patch = pre_patch_callback,
.post_patch = post_patch_callback,
.pre_unpatch = pre_unpatch_callback,
.post_unpatch = post_unpatch_callback,
},
}, {
.name = "livepatch_callbacks_busymod",
.funcs = busymod_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_patch patch = {
.mod = THIS_MODULE,
.objs = objs,
};
static int livepatch_callbacks_demo_init(void)
{
return klp_enable_patch(&patch);
}
static void livepatch_callbacks_demo_exit(void)
{
}
module_init(livepatch_callbacks_demo_init);
module_exit(livepatch_callbacks_demo_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");