1 /*
2 * livepatch.c - x86-specific Kernel Live Patching Core
3 *
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.
8 *
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.
13 *
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/>.
16 */
17
18 #include <linux/module.h>
19 #include <linux/kallsyms.h>
20 #include <linux/livepatch.h>
21 #include <asm/text-patching.h>
22
23 /* Apply per-object alternatives. Based on x86 module_finalize() */
arch_klp_init_object_loaded(struct klp_patch * patch,struct klp_object * obj)24 void arch_klp_init_object_loaded(struct klp_patch *patch,
25 struct klp_object *obj)
26 {
27 int cnt;
28 struct klp_modinfo *info;
29 Elf_Shdr *s, *alt = NULL, *para = NULL;
30 void *aseg, *pseg;
31 const char *objname;
32 char sec_objname[MODULE_NAME_LEN];
33 char secname[KSYM_NAME_LEN];
34
35 info = patch->mod->klp_info;
36 objname = obj->name ? obj->name : "vmlinux";
37
38 /* See livepatch core code for BUILD_BUG_ON() explanation */
39 BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128);
40
41 for (s = info->sechdrs; s < info->sechdrs + info->hdr.e_shnum; s++) {
42 /* Apply per-object .klp.arch sections */
43 cnt = sscanf(info->secstrings + s->sh_name,
44 ".klp.arch.%55[^.].%127s",
45 sec_objname, secname);
46 if (cnt != 2)
47 continue;
48 if (strcmp(sec_objname, objname))
49 continue;
50 if (!strcmp(".altinstructions", secname))
51 alt = s;
52 if (!strcmp(".parainstructions", secname))
53 para = s;
54 }
55
56 if (alt) {
57 aseg = (void *) alt->sh_addr;
58 apply_alternatives(aseg, aseg + alt->sh_size);
59 }
60
61 if (para) {
62 pseg = (void *) para->sh_addr;
63 apply_paravirt(pseg, pseg + para->sh_size);
64 }
65 }
66
