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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2017-2023 SUSE
* Authors: Libor Pechacek <lpechacek@suse.cz>
* Nicolai Stange <nstange@suse.de>
* Marcos Paulo de Souza <mpdesouza@suse.com>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/livepatch.h>
/*
* Before CONFIG_ARCH_HAS_SYSCALL_WRAPPER was introduced there were no
* prefixes for system calls.
* powerpc set this config based on configs, so it can be enabled or not.
*/
#if defined(CONFIG_ARCH_HAS_SYSCALL_WRAPPER)
#if defined(__x86_64__)
#define FN_PREFIX __x64_
#elif defined(__s390x__)
#define FN_PREFIX __s390x_
#elif defined(__aarch64__)
#define FN_PREFIX __arm64_
#elif defined(__powerpc__)
#define FN_PREFIX
#else
#error "Missing syscall wrapper for the given architecture."
#endif
#else
/* Do not set a prefix for architectures that do not enable wrappers. */
#define FN_PREFIX
#endif
/* Protects klp_pids */
static DEFINE_MUTEX(kpid_mutex);
static unsigned int npids, npids_pending;
static int klp_pids[NR_CPUS];
module_param_array(klp_pids, int, &npids_pending, 0);
MODULE_PARM_DESC(klp_pids, "Array of pids to be transitioned to livepatched state.");
static ssize_t npids_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%u\n", npids_pending);
}
static struct kobj_attribute klp_attr = __ATTR_RO(npids);
static struct kobject *klp_kobj;
static asmlinkage long lp_sys_getpid(void)
{
int i;
mutex_lock(&kpid_mutex);
if (npids_pending > 0) {
for (i = 0; i < npids; i++) {
if (current->pid == klp_pids[i]) {
klp_pids[i] = 0;
npids_pending--;
break;
}
}
}
mutex_unlock(&kpid_mutex);
return task_tgid_vnr(current);
}
static struct klp_func vmlinux_funcs[] = {
{
.old_name = __stringify(FN_PREFIX) "sys_getpid",
.new_func = lp_sys_getpid,
}, {}
};
static struct klp_object objs[] = {
{
/* name being NULL means vmlinux */
.funcs = vmlinux_funcs,
}, {}
};
static struct klp_patch patch = {
.mod = THIS_MODULE,
.objs = objs,
};
static int livepatch_init(void)
{
int ret;
klp_kobj = kobject_create_and_add("test_klp_syscall", kernel_kobj);
if (!klp_kobj)
return -ENOMEM;
ret = sysfs_create_file(klp_kobj, &klp_attr.attr);
if (ret) {
kobject_put(klp_kobj);
return ret;
}
/*
* Save the number pids to transition to livepatched state before the
* number of pending pids is decremented.
*/
npids = npids_pending;
ret = klp_enable_patch(&patch);
if (ret)
kobject_put(klp_kobj);
return ret;
}
static void livepatch_exit(void)
{
kobject_put(klp_kobj);
}
module_init(livepatch_init);
module_exit(livepatch_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");
MODULE_AUTHOR("Libor Pechacek <lpechacek@suse.cz>");
MODULE_AUTHOR("Nicolai Stange <nstange@suse.de>");
MODULE_AUTHOR("Marcos Paulo de Souza <mpdesouza@suse.com>");
MODULE_DESCRIPTION("Livepatch test: syscall transition");
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