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() */
  12 void 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 }