1/*
2 * livepatch.h - Kernel Live Patching Core
3 *
4 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
5 * Copyright (C) 2014 SUSE
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, see <http://www.gnu.org/licenses/>.
19 */
20
21#ifndef _LINUX_LIVEPATCH_H_
22#define _LINUX_LIVEPATCH_H_
23
24#include <linux/module.h>
25#include <linux/ftrace.h>
26
27#if IS_ENABLED(CONFIG_LIVEPATCH)
28
29#include <asm/livepatch.h>
30
31enum klp_state {
32	KLP_DISABLED,
33	KLP_ENABLED
34};
35
36/**
37 * struct klp_func - function structure for live patching
38 * @old_name:	name of the function to be patched
39 * @new_func:	pointer to the patched function code
40 * @old_addr:	a hint conveying at what address the old function
41 *		can be found (optional, vmlinux patches only)
42 * @kobj:	kobject for sysfs resources
43 * @state:	tracks function-level patch application state
44 * @stack_node:	list node for klp_ops func_stack list
45 */
46struct klp_func {
47	/* external */
48	const char *old_name;
49	void *new_func;
50	/*
51	 * The old_addr field is optional and can be used to resolve
52	 * duplicate symbol names in the vmlinux object.  If this
53	 * information is not present, the symbol is located by name
54	 * with kallsyms. If the name is not unique and old_addr is
55	 * not provided, the patch application fails as there is no
56	 * way to resolve the ambiguity.
57	 */
58	unsigned long old_addr;
59
60	/* internal */
61	struct kobject kobj;
62	enum klp_state state;
63	struct list_head stack_node;
64};
65
66/**
67 * struct klp_reloc - relocation structure for live patching
68 * @loc:	address where the relocation will be written
69 * @val:	address of the referenced symbol (optional,
70 *		vmlinux	patches only)
71 * @type:	ELF relocation type
72 * @name:	name of the referenced symbol (for lookup/verification)
73 * @addend:	offset from the referenced symbol
74 * @external:	symbol is either exported or within the live patch module itself
75 */
76struct klp_reloc {
77	unsigned long loc;
78	unsigned long val;
79	unsigned long type;
80	const char *name;
81	int addend;
82	int external;
83};
84
85/**
86 * struct klp_object - kernel object structure for live patching
87 * @name:	module name (or NULL for vmlinux)
88 * @relocs:	relocation entries to be applied at load time
89 * @funcs:	function entries for functions to be patched in the object
90 * @kobj:	kobject for sysfs resources
91 * @mod:	kernel module associated with the patched object
92 * 		(NULL for vmlinux)
93 * @state:	tracks object-level patch application state
94 */
95struct klp_object {
96	/* external */
97	const char *name;
98	struct klp_reloc *relocs;
99	struct klp_func *funcs;
100
101	/* internal */
102	struct kobject *kobj;
103	struct module *mod;
104	enum klp_state state;
105};
106
107/**
108 * struct klp_patch - patch structure for live patching
109 * @mod:	reference to the live patch module
110 * @objs:	object entries for kernel objects to be patched
111 * @list:	list node for global list of registered patches
112 * @kobj:	kobject for sysfs resources
113 * @state:	tracks patch-level application state
114 */
115struct klp_patch {
116	/* external */
117	struct module *mod;
118	struct klp_object *objs;
119
120	/* internal */
121	struct list_head list;
122	struct kobject kobj;
123	enum klp_state state;
124};
125
126int klp_register_patch(struct klp_patch *);
127int klp_unregister_patch(struct klp_patch *);
128int klp_enable_patch(struct klp_patch *);
129int klp_disable_patch(struct klp_patch *);
130
131#endif /* CONFIG_LIVEPATCH */
132
133#endif /* _LINUX_LIVEPATCH_H_ */
134