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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2019 SUSE
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/livepatch.h>
#define CONSOLE_LOGLEVEL_STATE 1
/* Version 2 supports migration. */
#define CONSOLE_LOGLEVEL_STATE_VERSION 2
static const char *const module_state[] = {
[MODULE_STATE_LIVE] = "[MODULE_STATE_LIVE] Normal state",
[MODULE_STATE_COMING] = "[MODULE_STATE_COMING] Full formed, running module_init",
[MODULE_STATE_GOING] = "[MODULE_STATE_GOING] Going away",
[MODULE_STATE_UNFORMED] = "[MODULE_STATE_UNFORMED] Still setting it up",
};
static void callback_info(const char *callback, struct klp_object *obj)
{
if (obj->mod)
pr_info("%s: %s -> %s\n", callback, obj->mod->name,
module_state[obj->mod->state]);
else
pr_info("%s: vmlinux\n", callback);
}
static struct klp_patch patch;
static int allocate_loglevel_state(void)
{
struct klp_state *loglevel_state, *prev_loglevel_state;
prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
if (prev_loglevel_state) {
pr_info("%s: space to store console_loglevel already allocated\n",
__func__);
return 0;
}
loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
if (!loglevel_state)
return -EINVAL;
loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);
if (!loglevel_state->data)
return -ENOMEM;
pr_info("%s: allocating space to store console_loglevel\n",
__func__);
return 0;
}
static void fix_console_loglevel(void)
{
struct klp_state *loglevel_state, *prev_loglevel_state;
loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
if (!loglevel_state)
return;
prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
if (prev_loglevel_state) {
pr_info("%s: taking over the console_loglevel change\n",
__func__);
loglevel_state->data = prev_loglevel_state->data;
return;
}
pr_info("%s: fixing console_loglevel\n", __func__);
*(int *)loglevel_state->data = console_loglevel;
console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
}
static void restore_console_loglevel(void)
{
struct klp_state *loglevel_state, *prev_loglevel_state;
prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
if (prev_loglevel_state) {
pr_info("%s: passing the console_loglevel change back to the old livepatch\n",
__func__);
return;
}
loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
if (!loglevel_state)
return;
pr_info("%s: restoring console_loglevel\n", __func__);
console_loglevel = *(int *)loglevel_state->data;
}
static void free_loglevel_state(void)
{
struct klp_state *loglevel_state, *prev_loglevel_state;
prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
if (prev_loglevel_state) {
pr_info("%s: keeping space to store console_loglevel\n",
__func__);
return;
}
loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
if (!loglevel_state)
return;
pr_info("%s: freeing space for the stored console_loglevel\n",
__func__);
kfree(loglevel_state->data);
}
/* Executed on object patching (ie, patch enablement) */
static int pre_patch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
return allocate_loglevel_state();
}
/* Executed on object unpatching (ie, patch disablement) */
static void post_patch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
fix_console_loglevel();
}
/* Executed on object unpatching (ie, patch disablement) */
static void pre_unpatch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
restore_console_loglevel();
}
/* Executed on object unpatching (ie, patch disablement) */
static void post_unpatch_callback(struct klp_object *obj)
{
callback_info(__func__, obj);
free_loglevel_state();
}
static struct klp_func no_funcs[] = {
{}
};
static struct klp_object objs[] = {
{
.name = NULL, /* vmlinux */
.funcs = no_funcs,
.callbacks = {
.pre_patch = pre_patch_callback,
.post_patch = post_patch_callback,
.pre_unpatch = pre_unpatch_callback,
.post_unpatch = post_unpatch_callback,
},
}, { }
};
static struct klp_state states[] = {
{
.id = CONSOLE_LOGLEVEL_STATE,
.version = CONSOLE_LOGLEVEL_STATE_VERSION,
}, { }
};
static struct klp_patch patch = {
.mod = THIS_MODULE,
.objs = objs,
.states = states,
.replace = true,
};
static int test_klp_callbacks_demo_init(void)
{
return klp_enable_patch(&patch);
}
static void test_klp_callbacks_demo_exit(void)
{
}
module_init(test_klp_callbacks_demo_init);
module_exit(test_klp_callbacks_demo_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");
MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>");
MODULE_DESCRIPTION("Livepatch test: system state modification");
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