2 * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com>
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
19 * livepatch-shadow-fix2.c - Shadow variables, livepatch demo
24 * Adds functionality to livepatch-shadow-mod's in-flight data
25 * structures through a shadow variable. The livepatch patches a
26 * routine that periodically inspects data structures, incrementing a
27 * per-data-structure counter, creating the counter if needed.
33 * This module is not intended to be standalone. See the "Usage"
34 * section of livepatch-shadow-mod.c.
37 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
39 #include <linux/module.h>
40 #include <linux/kernel.h>
41 #include <linux/livepatch.h>
42 #include <linux/slab.h>
44 /* Shadow variable enums */
49 struct list_head list;
50 unsigned long jiffies_expire;
53 bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies)
59 * Patch: handle in-flight dummy structures, if they do not
60 * already have a SV_COUNTER shadow variable, then attach a
64 shadow_count = klp_shadow_get_or_alloc(d, SV_COUNTER,
65 &count, sizeof(count),
70 return time_after(jiffies, d->jiffies_expire);
73 void livepatch_fix2_dummy_free(struct dummy *d)
75 void **shadow_leak, *leak;
78 /* Patch: copy the memory leak patch from the fix1 module. */
79 shadow_leak = klp_shadow_get(d, SV_LEAK);
82 klp_shadow_free(d, SV_LEAK);
84 pr_info("%s: dummy @ %p, prevented leak @ %p\n",
87 pr_info("%s: dummy @ %p leaked!\n", __func__, d);
91 * Patch: fetch the SV_COUNTER shadow variable and display
92 * the final count. Detach the shadow variable.
94 shadow_count = klp_shadow_get(d, SV_COUNTER);
96 pr_info("%s: dummy @ %p, check counter = %d\n",
97 __func__, d, *shadow_count);
98 klp_shadow_free(d, SV_COUNTER);
104 static struct klp_func funcs[] = {
106 .old_name = "dummy_check",
107 .new_func = livepatch_fix2_dummy_check,
110 .old_name = "dummy_free",
111 .new_func = livepatch_fix2_dummy_free,
115 static struct klp_object objs[] = {
117 .name = "livepatch_shadow_mod",
122 static struct klp_patch patch = {
127 static int livepatch_shadow_fix2_init(void)
131 ret = klp_register_patch(&patch);
134 ret = klp_enable_patch(&patch);
136 WARN_ON(klp_unregister_patch(&patch));
142 static void livepatch_shadow_fix2_exit(void)
144 /* Cleanup any existing SV_COUNTER shadow variables */
145 klp_shadow_free_all(SV_COUNTER);
147 WARN_ON(klp_unregister_patch(&patch));
150 module_init(livepatch_shadow_fix2_init);
151 module_exit(livepatch_shadow_fix2_exit);
152 MODULE_LICENSE("GPL");
153 MODULE_INFO(livepatch, "Y");