163 lines · c
1// SPDX-License-Identifier: GPL-2.02// Copyright (C) 2019 SUSE3 4#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt5 6#include <linux/slab.h>7#include <linux/module.h>8#include <linux/kernel.h>9#include <linux/printk.h>10#include <linux/livepatch.h>11 12#define CONSOLE_LOGLEVEL_STATE 113/* Version 1 does not support migration. */14#define CONSOLE_LOGLEVEL_STATE_VERSION 115 16static const char *const module_state[] = {17 [MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state",18 [MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init",19 [MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away",20 [MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",21};22 23static void callback_info(const char *callback, struct klp_object *obj)24{25 if (obj->mod)26 pr_info("%s: %s -> %s\n", callback, obj->mod->name,27 module_state[obj->mod->state]);28 else29 pr_info("%s: vmlinux\n", callback);30}31 32static struct klp_patch patch;33 34static int allocate_loglevel_state(void)35{36 struct klp_state *loglevel_state;37 38 loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);39 if (!loglevel_state)40 return -EINVAL;41 42 loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);43 if (!loglevel_state->data)44 return -ENOMEM;45 46 pr_info("%s: allocating space to store console_loglevel\n",47 __func__);48 return 0;49}50 51static void fix_console_loglevel(void)52{53 struct klp_state *loglevel_state;54 55 loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);56 if (!loglevel_state)57 return;58 59 pr_info("%s: fixing console_loglevel\n", __func__);60 *(int *)loglevel_state->data = console_loglevel;61 console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;62}63 64static void restore_console_loglevel(void)65{66 struct klp_state *loglevel_state;67 68 loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);69 if (!loglevel_state)70 return;71 72 pr_info("%s: restoring console_loglevel\n", __func__);73 console_loglevel = *(int *)loglevel_state->data;74}75 76static void free_loglevel_state(void)77{78 struct klp_state *loglevel_state;79 80 loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);81 if (!loglevel_state)82 return;83 84 pr_info("%s: freeing space for the stored console_loglevel\n",85 __func__);86 kfree(loglevel_state->data);87}88 89/* Executed on object patching (ie, patch enablement) */90static int pre_patch_callback(struct klp_object *obj)91{92 callback_info(__func__, obj);93 return allocate_loglevel_state();94}95 96/* Executed on object unpatching (ie, patch disablement) */97static void post_patch_callback(struct klp_object *obj)98{99 callback_info(__func__, obj);100 fix_console_loglevel();101}102 103/* Executed on object unpatching (ie, patch disablement) */104static void pre_unpatch_callback(struct klp_object *obj)105{106 callback_info(__func__, obj);107 restore_console_loglevel();108}109 110/* Executed on object unpatching (ie, patch disablement) */111static void post_unpatch_callback(struct klp_object *obj)112{113 callback_info(__func__, obj);114 free_loglevel_state();115}116 117static struct klp_func no_funcs[] = {118 {}119};120 121static struct klp_object objs[] = {122 {123 .name = NULL, /* vmlinux */124 .funcs = no_funcs,125 .callbacks = {126 .pre_patch = pre_patch_callback,127 .post_patch = post_patch_callback,128 .pre_unpatch = pre_unpatch_callback,129 .post_unpatch = post_unpatch_callback,130 },131 }, { }132};133 134static struct klp_state states[] = {135 {136 .id = CONSOLE_LOGLEVEL_STATE,137 .version = CONSOLE_LOGLEVEL_STATE_VERSION,138 }, { }139};140 141static struct klp_patch patch = {142 .mod = THIS_MODULE,143 .objs = objs,144 .states = states,145 .replace = true,146};147 148static int test_klp_callbacks_demo_init(void)149{150 return klp_enable_patch(&patch);151}152 153static void test_klp_callbacks_demo_exit(void)154{155}156 157module_init(test_klp_callbacks_demo_init);158module_exit(test_klp_callbacks_demo_exit);159MODULE_LICENSE("GPL");160MODULE_INFO(livepatch, "Y");161MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>");162MODULE_DESCRIPTION("Livepatch test: system state modification");163