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// SPDX-License-Identifier: GPL-2.0

/*

* Init code for a livepatch kernel module

*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/livepatch.h>

static struct klp_patch *patch;

static int __init livepatch_mod_init(void)

{

struct klp_object_ext *obj_exts;

size_t obj_exts_sec_size;

struct klp_object *objs;

unsigned int nr_objs;

int ret;

obj_exts = klp_find_section_by_name(THIS_MODULE, ".init.klp_objects",

&obj_exts_sec_size);

nr_objs = obj_exts_sec_size / sizeof(*obj_exts);

if (!nr_objs) {

pr_err("nothing to patch!\n");

ret = -EINVAL;

goto err;

}

patch = kzalloc_obj(*patch);

if (!patch) {

ret = -ENOMEM;

goto err;

}

objs = kzalloc(sizeof(struct klp_object) * (nr_objs + 1), GFP_KERNEL);

if (!objs) {

ret = -ENOMEM;

goto err_free_patch;

}

for (int i = 0; i < nr_objs; i++) {

struct klp_object_ext *obj_ext = obj_exts + i;

struct klp_func_ext *funcs_ext = obj_ext->funcs;

unsigned int nr_funcs = obj_ext->nr_funcs;

struct klp_func *funcs = objs[i].funcs;

struct klp_object *obj = objs + i;

funcs = kzalloc(sizeof(struct klp_func) * (nr_funcs + 1), GFP_KERNEL);

if (!funcs) {

ret = -ENOMEM;

for (int j = 0; j < i; j++)

kfree(objs[i].funcs);

goto err_free_objs;

}

for (int j = 0; j < nr_funcs; j++) {

funcs[j].old_name = funcs_ext[j].old_name;

funcs[j].new_func = funcs_ext[j].new_func;

funcs[j].old_sympos = funcs_ext[j].sympos;

}

obj->name = obj_ext->name;

obj->funcs = funcs;

memcpy(&obj->callbacks, &obj_ext->callbacks, sizeof(struct klp_callbacks));

}

patch->mod = THIS_MODULE;

patch->objs = objs;

/* TODO patch->states */

#ifdef KLP_NO_REPLACE

patch->replace = false;

#else

patch->replace = true;

#endif

return klp_enable_patch(patch);

err_free_objs:

kfree(objs);

err_free_patch:

kfree(patch);

err:

return ret;

}

static void __exit livepatch_mod_exit(void)

{

struct klp_object *obj;

klp_for_each_object_static(patch, obj)

kfree(obj->funcs);

kfree(patch->objs);

kfree(patch);

}

module_init(livepatch_mod_init);

module_exit(livepatch_mod_exit);

MODULE_LICENSE("GPL");

MODULE_INFO(livepatch, "Y");

MODULE_DESCRIPTION("Livepatch module");