LXR linux/arch/x86/kernel/livepatch.c

   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() */
  24void 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