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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | // Copyright (C) 2019 SUSE | |
3 | ||
4 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
5 | ||
6 | #include <linux/slab.h> | |
7 | #include <linux/module.h> | |
8 | #include <linux/kernel.h> | |
9 | #include <linux/printk.h> | |
10 | #include <linux/livepatch.h> | |
11 | ||
12 | #define CONSOLE_LOGLEVEL_STATE 1 | |
13 | /* Version 1 does not support migration. */ | |
14 | #define CONSOLE_LOGLEVEL_STATE_VERSION 1 | |
15 | ||
16 | static const char *const module_state[] = { | |
17 | [MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state", | |
18 | [MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init", | |
19 | [MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away", | |
20 | [MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up", | |
21 | }; | |
22 | ||
23 | static void callback_info(const char *callback, struct klp_object *obj) | |
24 | { | |
25 | if (obj->mod) | |
26 | pr_info("%s: %s -> %s\n", callback, obj->mod->name, | |
27 | module_state[obj->mod->state]); | |
28 | else | |
29 | pr_info("%s: vmlinux\n", callback); | |
30 | } | |
31 | ||
32 | static struct klp_patch patch; | |
33 | ||
34 | static int allocate_loglevel_state(void) | |
35 | { | |
36 | struct klp_state *loglevel_state; | |
37 | ||
38 | loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); | |
39 | if (!loglevel_state) | |
40 | return -EINVAL; | |
41 | ||
42 | loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL); | |
43 | if (!loglevel_state->data) | |
44 | return -ENOMEM; | |
45 | ||
46 | pr_info("%s: allocating space to store console_loglevel\n", | |
47 | __func__); | |
48 | return 0; | |
49 | } | |
50 | ||
51 | static void fix_console_loglevel(void) | |
52 | { | |
53 | struct klp_state *loglevel_state; | |
54 | ||
55 | loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); | |
56 | if (!loglevel_state) | |
57 | return; | |
58 | ||
59 | pr_info("%s: fixing console_loglevel\n", __func__); | |
60 | *(int *)loglevel_state->data = console_loglevel; | |
61 | console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH; | |
62 | } | |
63 | ||
64 | static void restore_console_loglevel(void) | |
65 | { | |
66 | struct klp_state *loglevel_state; | |
67 | ||
68 | loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); | |
69 | if (!loglevel_state) | |
70 | return; | |
71 | ||
72 | pr_info("%s: restoring console_loglevel\n", __func__); | |
73 | console_loglevel = *(int *)loglevel_state->data; | |
74 | } | |
75 | ||
76 | static void free_loglevel_state(void) | |
77 | { | |
78 | struct klp_state *loglevel_state; | |
79 | ||
80 | loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE); | |
81 | if (!loglevel_state) | |
82 | return; | |
83 | ||
84 | pr_info("%s: freeing space for the stored console_loglevel\n", | |
85 | __func__); | |
86 | kfree(loglevel_state->data); | |
87 | } | |
88 | ||
89 | /* Executed on object patching (ie, patch enablement) */ | |
90 | static int pre_patch_callback(struct klp_object *obj) | |
91 | { | |
92 | callback_info(__func__, obj); | |
93 | return allocate_loglevel_state(); | |
94 | } | |
95 | ||
96 | /* Executed on object unpatching (ie, patch disablement) */ | |
97 | static void post_patch_callback(struct klp_object *obj) | |
98 | { | |
99 | callback_info(__func__, obj); | |
100 | fix_console_loglevel(); | |
101 | } | |
102 | ||
103 | /* Executed on object unpatching (ie, patch disablement) */ | |
104 | static void pre_unpatch_callback(struct klp_object *obj) | |
105 | { | |
106 | callback_info(__func__, obj); | |
107 | restore_console_loglevel(); | |
108 | } | |
109 | ||
110 | /* Executed on object unpatching (ie, patch disablement) */ | |
111 | static void post_unpatch_callback(struct klp_object *obj) | |
112 | { | |
113 | callback_info(__func__, obj); | |
114 | free_loglevel_state(); | |
115 | } | |
116 | ||
117 | static struct klp_func no_funcs[] = { | |
118 | {} | |
119 | }; | |
120 | ||
121 | static struct klp_object objs[] = { | |
122 | { | |
123 | .name = NULL, /* vmlinux */ | |
124 | .funcs = no_funcs, | |
125 | .callbacks = { | |
126 | .pre_patch = pre_patch_callback, | |
127 | .post_patch = post_patch_callback, | |
128 | .pre_unpatch = pre_unpatch_callback, | |
129 | .post_unpatch = post_unpatch_callback, | |
130 | }, | |
131 | }, { } | |
132 | }; | |
133 | ||
134 | static struct klp_state states[] = { | |
135 | { | |
136 | .id = CONSOLE_LOGLEVEL_STATE, | |
137 | .version = CONSOLE_LOGLEVEL_STATE_VERSION, | |
138 | }, { } | |
139 | }; | |
140 | ||
141 | static struct klp_patch patch = { | |
142 | .mod = THIS_MODULE, | |
143 | .objs = objs, | |
144 | .states = states, | |
145 | .replace = true, | |
146 | }; | |
147 | ||
148 | static int test_klp_callbacks_demo_init(void) | |
149 | { | |
150 | return klp_enable_patch(&patch); | |
151 | } | |
152 | ||
153 | static void test_klp_callbacks_demo_exit(void) | |
154 | { | |
155 | } | |
156 | ||
157 | module_init(test_klp_callbacks_demo_init); | |
158 | module_exit(test_klp_callbacks_demo_exit); | |
159 | MODULE_LICENSE("GPL"); | |
160 | MODULE_INFO(livepatch, "Y"); | |
161 | MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>"); | |
162 | MODULE_DESCRIPTION("Livepatch test: system state modification"); |