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livepatch/klp-build: Add stub init code for livepatch modules

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Add a module initialization stub which can be linked with binary diff
objects to produce a livepatch module.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2025-09-17 09:04:07 -07:00
parent abaf1f42dd
commit 59adee07b5
1 changed files with 108 additions and 0 deletions
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108
scripts/livepatch/init.c Normal file
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@ -0,0 +1,108 @@
// 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>
extern struct klp_object_ext __start_klp_objects[];
extern struct klp_object_ext __stop_klp_objects[];
static struct klp_patch *patch;
static int __init livepatch_mod_init(void)
{
struct klp_object *objs;
unsigned int nr_objs;
int ret;
nr_objs = __stop_klp_objects - __start_klp_objects;
if (!nr_objs) {
pr_err("nothing to patch!\n");
ret = -EINVAL;
goto err;
}
patch = kzalloc(sizeof(*patch), GFP_KERNEL);
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 = __start_klp_objects + 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)
{
unsigned int nr_objs;
nr_objs = __stop_klp_objects - __start_klp_objects;
for (int i = 0; i < nr_objs; i++)
kfree(patch->objs[i].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");