LXR linux/include/linux/livepatch.h

   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_sympos: a hint indicating which symbol position the old function
  41 *              can be found (optional)
  42 * @old_addr:   the address of the function being patched
  43 * @kobj:       kobject for sysfs resources
  44 * @state:      tracks function-level patch application state
  45 * @stack_node: list node for klp_ops func_stack list
  46 */
  47struct klp_func {
  48        /* external */
  49        const char *old_name;
  50        void *new_func;
  51        /*
  52         * The old_sympos field is optional and can be used to resolve
  53         * duplicate symbol names in livepatch objects. If this field is zero,
  54         * it is expected the symbol is unique, otherwise patching fails. If
  55         * this value is greater than zero then that occurrence of the symbol
  56         * in kallsyms for the given object is used.
  57         */
  58        unsigned long old_sympos;
  59
  60        /* internal */
  61        unsigned long old_addr;
  62        struct kobject kobj;
  63        enum klp_state state;
  64        struct list_head stack_node;
  65};
  66
  67/**
  68 * struct klp_object - kernel object structure for live patching
  69 * @name:       module name (or NULL for vmlinux)
  70 * @funcs:      function entries for functions to be patched in the object
  71 * @kobj:       kobject for sysfs resources
  72 * @mod:        kernel module associated with the patched object
  73 *              (NULL for vmlinux)
  74 * @state:      tracks object-level patch application state
  75 */
  76struct klp_object {
  77        /* external */
  78        const char *name;
  79        struct klp_func *funcs;
  80
  81        /* internal */
  82        struct kobject kobj;
  83        struct module *mod;
  84        enum klp_state state;
  85};
  86
  87/**
  88 * struct klp_patch - patch structure for live patching
  89 * @mod:        reference to the live patch module
  90 * @objs:       object entries for kernel objects to be patched
  91 * @list:       list node for global list of registered patches
  92 * @kobj:       kobject for sysfs resources
  93 * @state:      tracks patch-level application state
  94 */
  95struct klp_patch {
  96        /* external */
  97        struct module *mod;
  98        struct klp_object *objs;
  99
 100        /* internal */
 101        struct list_head list;
 102        struct kobject kobj;
 103        enum klp_state state;
 104};
 105
 106#define klp_for_each_object(patch, obj) \
 107        for (obj = patch->objs; obj->funcs || obj->name; obj++)
 108
 109#define klp_for_each_func(obj, func) \
 110        for (func = obj->funcs; \
 111             func->old_name || func->new_func || func->old_sympos; \
 112             func++)
 113
 114int klp_register_patch(struct klp_patch *);
 115int klp_unregister_patch(struct klp_patch *);
 116int klp_enable_patch(struct klp_patch *);
 117int klp_disable_patch(struct klp_patch *);
 118
 119void arch_klp_init_object_loaded(struct klp_patch *patch,
 120                                 struct klp_object *obj);
 121
 122/* Called from the module loader during module coming/going states */
 123int klp_module_coming(struct module *mod);
 124void klp_module_going(struct module *mod);
 125
 126#else /* !CONFIG_LIVEPATCH */
 127
 128static inline int klp_module_coming(struct module *mod) { return 0; }
 129static inline void klp_module_going(struct module *mod) { }
 130
 131#endif /* CONFIG_LIVEPATCH */
 132
 133#endif /* _LINUX_LIVEPATCH_H_ */
 134