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}