1// SPDX-License-Identifier: GPL-2.0
2// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
3
4#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
5
6#include <linux/module.h>
7#include <linux/kernel.h>
8#include <linux/livepatch.h>
9
10static int pre_patch_ret;
11module_param(pre_patch_ret, int, 0644);
12MODULE_PARM_DESC(pre_patch_ret, "pre_patch_ret (default=0)");
13
14static const char *const module_state[] = {
15 [MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state",
16 [MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init",
17 [MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away",
18 [MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",
19};
20
21static void callback_info(const char *callback, struct klp_object *obj)
22{
23 if (obj->mod)
24 pr_info("%s: %s -> %s\n", callback, obj->mod->name,
25 module_state[obj->mod->state]);
26 else
27 pr_info("%s: vmlinux\n", callback);
28}
29
30/* Executed on object patching (ie, patch enablement) */
31static int pre_patch_callback(struct klp_object *obj)
32{
33 callback_info(callback: __func__, obj);
34 return pre_patch_ret;
35}
36
37/* Executed on object unpatching (ie, patch disablement) */
38static void post_patch_callback(struct klp_object *obj)
39{
40 callback_info(callback: __func__, obj);
41}
42
43/* Executed on object unpatching (ie, patch disablement) */
44static void pre_unpatch_callback(struct klp_object *obj)
45{
46 callback_info(callback: __func__, obj);
47}
48
49/* Executed on object unpatching (ie, patch disablement) */
50static void post_unpatch_callback(struct klp_object *obj)
51{
52 callback_info(callback: __func__, obj);
53}
54
55static void patched_work_func(struct work_struct *work)
56{
57 pr_info("%s\n", __func__);
58}
59
60static struct klp_func no_funcs[] = {
61 {}
62};
63
64static struct klp_func busymod_funcs[] = {
65 {
66 .old_name = "busymod_work_func",
67 .new_func = patched_work_func,
68 }, {}
69};
70
71static struct klp_object objs[] = {
72 {
73 .name = NULL, /* vmlinux */
74 .funcs = no_funcs,
75 .callbacks = {
76 .pre_patch = pre_patch_callback,
77 .post_patch = post_patch_callback,
78 .pre_unpatch = pre_unpatch_callback,
79 .post_unpatch = post_unpatch_callback,
80 },
81 }, {
82 .name = "test_klp_callbacks_mod",
83 .funcs = no_funcs,
84 .callbacks = {
85 .pre_patch = pre_patch_callback,
86 .post_patch = post_patch_callback,
87 .pre_unpatch = pre_unpatch_callback,
88 .post_unpatch = post_unpatch_callback,
89 },
90 }, {
91 .name = "test_klp_callbacks_busy",
92 .funcs = busymod_funcs,
93 .callbacks = {
94 .pre_patch = pre_patch_callback,
95 .post_patch = post_patch_callback,
96 .pre_unpatch = pre_unpatch_callback,
97 .post_unpatch = post_unpatch_callback,
98 },
99 }, { }
100};
101
102static struct klp_patch patch = {
103 .mod = THIS_MODULE,
104 .objs = objs,
105};
106
107static int test_klp_callbacks_demo_init(void)
108{
109 return klp_enable_patch(&patch);
110}
111
112static void test_klp_callbacks_demo_exit(void)
113{
114}
115
116module_init(test_klp_callbacks_demo_init);
117module_exit(test_klp_callbacks_demo_exit);
118MODULE_LICENSE("GPL");
119MODULE_INFO(livepatch, "Y");
120MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
121MODULE_DESCRIPTION("Livepatch test: livepatch demo");
122

source code of linux/lib/livepatch/test_klp_callbacks_demo.c