feat: try manual reboot hook (#521)

* feat: try manual reboot hook

* refactor: move ksu_handle_reboot to supercalls.c for ShirkNeko

---------

kernel/supercalls.c

@@ -69,6 +69,17 @@ static void init_uid_scanner(void)
     }
 }
 
+void ksu_handle_reboot(int magic1, int magic2, void __user * arg) {
+    if (magic1 == KSU_INSTALL_MAGIC1 && magic2 == KSU_INSTALL_MAGIC2) {
+        int fd = ksu_install_fd();
+        pr_info("[%d] install ksu fd: %d\n", current->pid, fd);
+
+        if (copy_to_user(arg, &fd, sizeof(fd))) {
+            pr_err("install ksu fd reply err\n");
+        }
+    }
+}
+
 static int do_grant_root(void __user *arg)
 {
     // Check if current UID is allowed