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

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * livepatch.c - x86-specific Kernel Live Patching Core
   4 */
   5
   6#include <linux/module.h>
   7#include <linux/kallsyms.h>
   8#include <linux/livepatch.h>
   9#include <asm/text-patching.h>
  10
  11/* Apply per-object alternatives. Based on x86 module_finalize() */
  12void arch_klp_init_object_loaded(struct klp_patch *patch,
  13                                 struct klp_object *obj)
  14{
  15        int cnt;
  16        struct klp_modinfo *info;
  17        Elf_Shdr *s, *alt = NULL, *para = NULL;
  18        void *aseg, *pseg;
  19        const char *objname;
  20        char sec_objname[MODULE_NAME_LEN];
  21        char secname[KSYM_NAME_LEN];
  22
  23        info = patch->mod->klp_info;
  24        objname = obj->name ? obj->name : "vmlinux";
  25
  26        /* See livepatch core code for BUILD_BUG_ON() explanation */
  27        BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128);
  28
  29        for (s = info->sechdrs; s < info->sechdrs + info->hdr.e_shnum; s++) {
  30                /* Apply per-object .klp.arch sections */
  31                cnt = sscanf(info->secstrings + s->sh_name,
  32                             ".klp.arch.%55[^.].%127s",
  33                             sec_objname, secname);
  34                if (cnt != 2)
  35                        continue;
  36                if (strcmp(sec_objname, objname))
  37                        continue;
  38                if (!strcmp(".altinstructions", secname))
  39                        alt = s;
  40                if (!strcmp(".parainstructions", secname))
  41                        para = s;
  42        }
  43
  44        if (alt) {
  45                aseg = (void *) alt->sh_addr;
  46                apply_alternatives(aseg, aseg + alt->sh_size);
  47        }
  48
  49        if (para) {
  50                pseg = (void *) para->sh_addr;
  51                apply_paravirt(pseg, pseg + para->sh_size);
  52        }
  53}
  54