1 // SPDX-License-Identifier: GPL-2.0-or-later 1
2 /*
3 * Copyright (C) 2017 Joe Lawrence <joe.lawren
4 */
5
6 /*
7 * livepatch-callbacks-demo.c - (un)patching c
8 *
9 *
10 * Purpose
11 * -------
12 *
13 * Demonstration of registering livepatch (un)
14 *
15 *
16 * Usage
17 * -----
18 *
19 * Step 1 - load the simple module
20 *
21 * insmod samples/livepatch/livepatch-callba
22 *
23 *
24 * Step 2 - load the demonstration livepatch (
25 *
26 * insmod samples/livepatch/livepatch-callba
27 *
28 *
29 * Step 3 - cleanup
30 *
31 * echo 0 > /sys/kernel/livepatch/livepatch_
32 * rmmod livepatch_callbacks_demo
33 * rmmod livepatch_callbacks_mod
34 *
35 * Watch dmesg output to see livepatch enablem
36 * and patching operations for both vmlinux an
37 *
38 * NOTE: swap the insmod order of livepatch-ca
39 * livepatch-callbacks-demo.ko to observ
40 * target module is loaded after a livep
41 *
42 * NOTE: 'pre_patch_ret' is a module parameter
43 * callback return status. Try setting
44 * such as -19 (-ENODEV):
45 *
46 * # Load demo livepatch, vmlinux is pat
47 * insmod samples/livepatch/livepatch-ca
48 *
49 * # Setup next pre-patch callback to re
50 * echo -19 > /sys/module/livepatch_call
51 *
52 * # Module loader refuses to load the t
53 * insmod samples/livepatch/livepatch-ca
54 * insmod: ERROR: could not insert modul
55 *
56 * NOTE: There is a second target module,
57 * livepatch-callbacks-busymod.ko, avail
58 * with livepatch (un)patch callbacks.
59 * a 'sleep_secs' parameter that parks t
60 * functions that the livepatch demo mod
61 * Modifying this value and tweaking the
62 * effectively demonstrate stalled patch
63 *
64 * # Load a target module, let it park o
65 * # thirty seconds
66 * insmod samples/livepatch/livepatch-ca
67 *
68 * # Meanwhile load the livepatch
69 * insmod samples/livepatch/livepatch-ca
70 *
71 * # ... then load and unload another ta
72 * # transition is in progress
73 * insmod samples/livepatch/livepatch-ca
74 * rmmod samples/livepatch/livepatch-cal
75 *
76 * # Finally cleanup
77 * echo 0 > /sys/kernel/livepatch/livepa
78 * rmmod samples/livepatch/livepatch-cal
79 */
80
81 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
82
83 #include <linux/module.h>
84 #include <linux/kernel.h>
85 #include <linux/livepatch.h>
86
87 static int pre_patch_ret;
88 module_param(pre_patch_ret, int, 0644);
89 MODULE_PARM_DESC(pre_patch_ret, "pre_patch_ret
90
91 static const char *const module_state[] = {
92 [MODULE_STATE_LIVE] = "[MODULE_STA
93 [MODULE_STATE_COMING] = "[MODULE_STA
94 [MODULE_STATE_GOING] = "[MODULE_STA
95 [MODULE_STATE_UNFORMED] = "[MODULE_STA
96 };
97
98 static void callback_info(const char *callback
99 {
100 if (obj->mod)
101 pr_info("%s: %s -> %s\n", call
102 module_state[obj->mod-
103 else
104 pr_info("%s: vmlinux\n", callb
105 }
106
107 /* Executed on object patching (ie, patch enab
108 static int pre_patch_callback(struct klp_objec
109 {
110 callback_info(__func__, obj);
111 return pre_patch_ret;
112 }
113
114 /* Executed on object unpatching (ie, patch di
115 static void post_patch_callback(struct klp_obj
116 {
117 callback_info(__func__, obj);
118 }
119
120 /* Executed on object unpatching (ie, patch di
121 static void pre_unpatch_callback(struct klp_ob
122 {
123 callback_info(__func__, obj);
124 }
125
126 /* Executed on object unpatching (ie, patch di
127 static void post_unpatch_callback(struct klp_o
128 {
129 callback_info(__func__, obj);
130 }
131
132 static void patched_work_func(struct work_stru
133 {
134 pr_info("%s\n", __func__);
135 }
136
137 static struct klp_func no_funcs[] = {
138 { }
139 };
140
141 static struct klp_func busymod_funcs[] = {
142 {
143 .old_name = "busymod_work_func
144 .new_func = patched_work_func,
145 }, { }
146 };
147
148 static struct klp_object objs[] = {
149 {
150 .name = NULL, /* vmlinux */
151 .funcs = no_funcs,
152 .callbacks = {
153 .pre_patch = pre_patch
154 .post_patch = post_pat
155 .pre_unpatch = pre_unp
156 .post_unpatch = post_u
157 },
158 }, {
159 .name = "livepatch_callbacks_m
160 .funcs = no_funcs,
161 .callbacks = {
162 .pre_patch = pre_patch
163 .post_patch = post_pat
164 .pre_unpatch = pre_unp
165 .post_unpatch = post_u
166 },
167 }, {
168 .name = "livepatch_callbacks_b
169 .funcs = busymod_funcs,
170 .callbacks = {
171 .pre_patch = pre_patch
172 .post_patch = post_pat
173 .pre_unpatch = pre_unp
174 .post_unpatch = post_u
175 },
176 }, { }
177 };
178
179 static struct klp_patch patch = {
180 .mod = THIS_MODULE,
181 .objs = objs,
182 };
183
184 static int livepatch_callbacks_demo_init(void)
185 {
186 return klp_enable_patch(&patch);
187 }
188
189 static void livepatch_callbacks_demo_exit(void
190 {
191 }
192
193 module_init(livepatch_callbacks_demo_init);
194 module_exit(livepatch_callbacks_demo_exit);
195 MODULE_LICENSE("GPL");
196 MODULE_INFO(livepatch, "Y");
197
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