xref: /openbmc/linux/drivers/tty/serial/kgdboc.c (revision 64206956)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Based on the same principle as kgdboe using the NETPOLL api, this
4  * driver uses a console polling api to implement a gdb serial inteface
5  * which is multiplexed on a console port.
6  *
7  * Maintainer: Jason Wessel <jason.wessel@windriver.com>
8  *
9  * 2007-2008 (c) Jason Wessel - Wind River Systems, Inc.
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/kernel.h>
15 #include <linux/ctype.h>
16 #include <linux/kgdb.h>
17 #include <linux/kdb.h>
18 #include <linux/tty.h>
19 #include <linux/console.h>
20 #include <linux/vt_kern.h>
21 #include <linux/input.h>
22 #include <linux/irq_work.h>
23 #include <linux/module.h>
24 #include <linux/platform_device.h>
25 #include <linux/serial_core.h>
26 
27 #define MAX_CONFIG_LEN		40
28 
29 static struct kgdb_io		kgdboc_io_ops;
30 
31 /* -1 = init not run yet, 0 = unconfigured, 1 = configured. */
32 static int configured		= -1;
33 static DEFINE_MUTEX(config_mutex);
34 
35 static char config[MAX_CONFIG_LEN];
36 static struct kparam_string kps = {
37 	.string			= config,
38 	.maxlen			= MAX_CONFIG_LEN,
39 };
40 
41 static int kgdboc_use_kms;  /* 1 if we use kernel mode switching */
42 static struct tty_driver	*kgdb_tty_driver;
43 static int			kgdb_tty_line;
44 
45 static struct platform_device *kgdboc_pdev;
46 
47 #if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)
48 static struct kgdb_io		kgdboc_earlycon_io_ops;
49 static int                      (*earlycon_orig_exit)(struct console *con);
50 #endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
51 
52 /*
53  * When we leave the debug trap handler we need to reset the keyboard status
54  * (since the original keyboard state gets partially clobbered by kdb use of
55  * the keyboard).
56  *
57  * The path to deliver the reset is somewhat circuitous.
58  *
59  * To deliver the reset we register an input handler, reset the keyboard and
60  * then deregister the input handler. However, to get this done right, we do
61  * have to carefully manage the calling context because we can only register
62  * input handlers from task context.
63  *
64  * In particular we need to trigger the action from the debug trap handler with
65  * all its NMI and/or NMI-like oddities. To solve this the kgdboc trap exit code
66  * (the "post_exception" callback) uses irq_work_queue(), which is NMI-safe, to
67  * schedule a callback from a hardirq context. From there we have to defer the
68  * work again, this time using schedule_work(), to get a callback using the
69  * system workqueue, which runs in task context.
70  */
71 #ifdef CONFIG_KDB_KEYBOARD
kgdboc_reset_connect(struct input_handler * handler,struct input_dev * dev,const struct input_device_id * id)72 static int kgdboc_reset_connect(struct input_handler *handler,
73 				struct input_dev *dev,
74 				const struct input_device_id *id)
75 {
76 	input_reset_device(dev);
77 
78 	/* Return an error - we do not want to bind, just to reset */
79 	return -ENODEV;
80 }
81 
kgdboc_reset_disconnect(struct input_handle * handle)82 static void kgdboc_reset_disconnect(struct input_handle *handle)
83 {
84 	/* We do not expect anyone to actually bind to us */
85 	BUG();
86 }
87 
88 static const struct input_device_id kgdboc_reset_ids[] = {
89 	{
90 		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
91 		.evbit = { BIT_MASK(EV_KEY) },
92 	},
93 	{ }
94 };
95 
96 static struct input_handler kgdboc_reset_handler = {
97 	.connect	= kgdboc_reset_connect,
98 	.disconnect	= kgdboc_reset_disconnect,
99 	.name		= "kgdboc_reset",
100 	.id_table	= kgdboc_reset_ids,
101 };
102 
103 static DEFINE_MUTEX(kgdboc_reset_mutex);
104 
kgdboc_restore_input_helper(struct work_struct * dummy)105 static void kgdboc_restore_input_helper(struct work_struct *dummy)
106 {
107 	/*
108 	 * We need to take a mutex to prevent several instances of
109 	 * this work running on different CPUs so they don't try
110 	 * to register again already registered handler.
111 	 */
112 	mutex_lock(&kgdboc_reset_mutex);
113 
114 	if (input_register_handler(&kgdboc_reset_handler) == 0)
115 		input_unregister_handler(&kgdboc_reset_handler);
116 
117 	mutex_unlock(&kgdboc_reset_mutex);
118 }
119 
120 static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper);
121 
kgdboc_queue_restore_input_helper(struct irq_work * unused)122 static void kgdboc_queue_restore_input_helper(struct irq_work *unused)
123 {
124 	schedule_work(&kgdboc_restore_input_work);
125 }
126 
127 static DEFINE_IRQ_WORK(kgdboc_restore_input_irq_work, kgdboc_queue_restore_input_helper);
128 
kgdboc_restore_input(void)129 static void kgdboc_restore_input(void)
130 {
131 	if (likely(system_state == SYSTEM_RUNNING))
132 		irq_work_queue(&kgdboc_restore_input_irq_work);
133 }
134 
kgdboc_register_kbd(char ** cptr)135 static int kgdboc_register_kbd(char **cptr)
136 {
137 	if (strncmp(*cptr, "kbd", 3) == 0 ||
138 		strncmp(*cptr, "kdb", 3) == 0) {
139 		if (kdb_poll_idx < KDB_POLL_FUNC_MAX) {
140 			kdb_poll_funcs[kdb_poll_idx] = kdb_get_kbd_char;
141 			kdb_poll_idx++;
142 			if (cptr[0][3] == ',')
143 				*cptr += 4;
144 			else
145 				return 1;
146 		}
147 	}
148 	return 0;
149 }
150 
kgdboc_unregister_kbd(void)151 static void kgdboc_unregister_kbd(void)
152 {
153 	int i;
154 
155 	for (i = 0; i < kdb_poll_idx; i++) {
156 		if (kdb_poll_funcs[i] == kdb_get_kbd_char) {
157 			kdb_poll_idx--;
158 			kdb_poll_funcs[i] = kdb_poll_funcs[kdb_poll_idx];
159 			kdb_poll_funcs[kdb_poll_idx] = NULL;
160 			i--;
161 		}
162 	}
163 	irq_work_sync(&kgdboc_restore_input_irq_work);
164 	flush_work(&kgdboc_restore_input_work);
165 }
166 #else /* ! CONFIG_KDB_KEYBOARD */
167 #define kgdboc_register_kbd(x) 0
168 #define kgdboc_unregister_kbd()
169 #define kgdboc_restore_input()
170 #endif /* ! CONFIG_KDB_KEYBOARD */
171 
172 #if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)
cleanup_earlycon(void)173 static void cleanup_earlycon(void)
174 {
175 	if (kgdboc_earlycon_io_ops.cons)
176 		kgdb_unregister_io_module(&kgdboc_earlycon_io_ops);
177 }
178 #else /* !IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
cleanup_earlycon(void)179 static inline void cleanup_earlycon(void) { }
180 #endif /* !IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
181 
cleanup_kgdboc(void)182 static void cleanup_kgdboc(void)
183 {
184 	cleanup_earlycon();
185 
186 	if (configured != 1)
187 		return;
188 
189 	if (kgdb_unregister_nmi_console())
190 		return;
191 	kgdboc_unregister_kbd();
192 	kgdb_unregister_io_module(&kgdboc_io_ops);
193 }
194 
configure_kgdboc(void)195 static int configure_kgdboc(void)
196 {
197 	struct tty_driver *p;
198 	int tty_line = 0;
199 	int err = -ENODEV;
200 	char *cptr = config;
201 	struct console *cons;
202 	int cookie;
203 
204 	if (!strlen(config) || isspace(config[0])) {
205 		err = 0;
206 		goto noconfig;
207 	}
208 
209 	kgdboc_io_ops.cons = NULL;
210 	kgdb_tty_driver = NULL;
211 
212 	kgdboc_use_kms = 0;
213 	if (strncmp(cptr, "kms,", 4) == 0) {
214 		cptr += 4;
215 		kgdboc_use_kms = 1;
216 	}
217 
218 	if (kgdboc_register_kbd(&cptr))
219 		goto do_register;
220 
221 	p = tty_find_polling_driver(cptr, &tty_line);
222 	if (!p)
223 		goto noconfig;
224 
225 	/*
226 	 * Take console_lock to serialize device() callback with
227 	 * other console operations. For example, fg_console is
228 	 * modified under console_lock when switching vt.
229 	 */
230 	console_lock();
231 
232 	cookie = console_srcu_read_lock();
233 	for_each_console_srcu(cons) {
234 		int idx;
235 		if (cons->device && cons->device(cons, &idx) == p &&
236 		    idx == tty_line) {
237 			kgdboc_io_ops.cons = cons;
238 			break;
239 		}
240 	}
241 	console_srcu_read_unlock(cookie);
242 
243 	console_unlock();
244 
245 	kgdb_tty_driver = p;
246 	kgdb_tty_line = tty_line;
247 
248 do_register:
249 	err = kgdb_register_io_module(&kgdboc_io_ops);
250 	if (err)
251 		goto noconfig;
252 
253 	err = kgdb_register_nmi_console();
254 	if (err)
255 		goto nmi_con_failed;
256 
257 	configured = 1;
258 
259 	return 0;
260 
261 nmi_con_failed:
262 	kgdb_unregister_io_module(&kgdboc_io_ops);
263 noconfig:
264 	kgdboc_unregister_kbd();
265 	configured = 0;
266 
267 	return err;
268 }
269 
kgdboc_probe(struct platform_device * pdev)270 static int kgdboc_probe(struct platform_device *pdev)
271 {
272 	int ret = 0;
273 
274 	mutex_lock(&config_mutex);
275 	if (configured != 1) {
276 		ret = configure_kgdboc();
277 
278 		/* Convert "no device" to "defer" so we'll keep trying */
279 		if (ret == -ENODEV)
280 			ret = -EPROBE_DEFER;
281 	}
282 	mutex_unlock(&config_mutex);
283 
284 	return ret;
285 }
286 
287 static struct platform_driver kgdboc_platform_driver = {
288 	.probe = kgdboc_probe,
289 	.driver = {
290 		.name = "kgdboc",
291 		.suppress_bind_attrs = true,
292 	},
293 };
294 
init_kgdboc(void)295 static int __init init_kgdboc(void)
296 {
297 	int ret;
298 
299 	/*
300 	 * kgdboc is a little bit of an odd "platform_driver".  It can be
301 	 * up and running long before the platform_driver object is
302 	 * created and thus doesn't actually store anything in it.  There's
303 	 * only one instance of kgdb so anything is stored as global state.
304 	 * The platform_driver is only created so that we can leverage the
305 	 * kernel's mechanisms (like -EPROBE_DEFER) to call us when our
306 	 * underlying tty is ready.  Here we init our platform driver and
307 	 * then create the single kgdboc instance.
308 	 */
309 	ret = platform_driver_register(&kgdboc_platform_driver);
310 	if (ret)
311 		return ret;
312 
313 	kgdboc_pdev = platform_device_alloc("kgdboc", PLATFORM_DEVID_NONE);
314 	if (!kgdboc_pdev) {
315 		ret = -ENOMEM;
316 		goto err_did_register;
317 	}
318 
319 	ret = platform_device_add(kgdboc_pdev);
320 	if (!ret)
321 		return 0;
322 
323 	platform_device_put(kgdboc_pdev);
324 
325 err_did_register:
326 	platform_driver_unregister(&kgdboc_platform_driver);
327 	return ret;
328 }
329 
exit_kgdboc(void)330 static void exit_kgdboc(void)
331 {
332 	mutex_lock(&config_mutex);
333 	cleanup_kgdboc();
334 	mutex_unlock(&config_mutex);
335 
336 	platform_device_unregister(kgdboc_pdev);
337 	platform_driver_unregister(&kgdboc_platform_driver);
338 }
339 
kgdboc_get_char(void)340 static int kgdboc_get_char(void)
341 {
342 	if (!kgdb_tty_driver)
343 		return -1;
344 	return kgdb_tty_driver->ops->poll_get_char(kgdb_tty_driver,
345 						kgdb_tty_line);
346 }
347 
kgdboc_put_char(u8 chr)348 static void kgdboc_put_char(u8 chr)
349 {
350 	if (!kgdb_tty_driver)
351 		return;
352 	kgdb_tty_driver->ops->poll_put_char(kgdb_tty_driver,
353 					kgdb_tty_line, chr);
354 }
355 
param_set_kgdboc_var(const char * kmessage,const struct kernel_param * kp)356 static int param_set_kgdboc_var(const char *kmessage,
357 				const struct kernel_param *kp)
358 {
359 	size_t len = strlen(kmessage);
360 	int ret = 0;
361 
362 	if (len >= MAX_CONFIG_LEN) {
363 		pr_err("config string too long\n");
364 		return -ENOSPC;
365 	}
366 
367 	if (kgdb_connected) {
368 		pr_err("Cannot reconfigure while KGDB is connected.\n");
369 		return -EBUSY;
370 	}
371 
372 	mutex_lock(&config_mutex);
373 
374 	strcpy(config, kmessage);
375 	/* Chop out \n char as a result of echo */
376 	if (len && config[len - 1] == '\n')
377 		config[len - 1] = '\0';
378 
379 	if (configured == 1)
380 		cleanup_kgdboc();
381 
382 	/*
383 	 * Configure with the new params as long as init already ran.
384 	 * Note that we can get called before init if someone loads us
385 	 * with "modprobe kgdboc kgdboc=..." or if they happen to use
386 	 * the odd syntax of "kgdboc.kgdboc=..." on the kernel command.
387 	 */
388 	if (configured >= 0)
389 		ret = configure_kgdboc();
390 
391 	/*
392 	 * If we couldn't configure then clear out the config.  Note that
393 	 * specifying an invalid config on the kernel command line vs.
394 	 * through sysfs have slightly different behaviors.  If we fail
395 	 * to configure what was specified on the kernel command line
396 	 * we'll leave it in the 'config' and return -EPROBE_DEFER from
397 	 * our probe.  When specified through sysfs userspace is
398 	 * responsible for loading the tty driver before setting up.
399 	 */
400 	if (ret)
401 		config[0] = '\0';
402 
403 	mutex_unlock(&config_mutex);
404 
405 	return ret;
406 }
407 
408 static int dbg_restore_graphics;
409 
kgdboc_pre_exp_handler(void)410 static void kgdboc_pre_exp_handler(void)
411 {
412 	if (!dbg_restore_graphics && kgdboc_use_kms) {
413 		dbg_restore_graphics = 1;
414 		con_debug_enter(vc_cons[fg_console].d);
415 	}
416 	/* Increment the module count when the debugger is active */
417 	if (!kgdb_connected)
418 		try_module_get(THIS_MODULE);
419 }
420 
kgdboc_post_exp_handler(void)421 static void kgdboc_post_exp_handler(void)
422 {
423 	/* decrement the module count when the debugger detaches */
424 	if (!kgdb_connected)
425 		module_put(THIS_MODULE);
426 	if (kgdboc_use_kms && dbg_restore_graphics) {
427 		dbg_restore_graphics = 0;
428 		con_debug_leave();
429 	}
430 	kgdboc_restore_input();
431 }
432 
433 static struct kgdb_io kgdboc_io_ops = {
434 	.name			= "kgdboc",
435 	.read_char		= kgdboc_get_char,
436 	.write_char		= kgdboc_put_char,
437 	.pre_exception		= kgdboc_pre_exp_handler,
438 	.post_exception		= kgdboc_post_exp_handler,
439 };
440 
441 #if IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE)
kgdboc_option_setup(char * opt)442 static int kgdboc_option_setup(char *opt)
443 {
444 	if (!opt) {
445 		pr_err("config string not provided\n");
446 		return 1;
447 	}
448 
449 	if (strlen(opt) >= MAX_CONFIG_LEN) {
450 		pr_err("config string too long\n");
451 		return 1;
452 	}
453 	strcpy(config, opt);
454 
455 	return 1;
456 }
457 
458 __setup("kgdboc=", kgdboc_option_setup);
459 
460 
461 /* This is only available if kgdboc is a built in for early debugging */
kgdboc_early_init(char * opt)462 static int __init kgdboc_early_init(char *opt)
463 {
464 	kgdboc_option_setup(opt);
465 	configure_kgdboc();
466 	return 0;
467 }
468 
469 early_param("ekgdboc", kgdboc_early_init);
470 
kgdboc_earlycon_get_char(void)471 static int kgdboc_earlycon_get_char(void)
472 {
473 	char c;
474 
475 	if (!kgdboc_earlycon_io_ops.cons->read(kgdboc_earlycon_io_ops.cons,
476 					       &c, 1))
477 		return NO_POLL_CHAR;
478 
479 	return c;
480 }
481 
kgdboc_earlycon_put_char(u8 chr)482 static void kgdboc_earlycon_put_char(u8 chr)
483 {
484 	kgdboc_earlycon_io_ops.cons->write(kgdboc_earlycon_io_ops.cons, &chr,
485 					   1);
486 }
487 
kgdboc_earlycon_pre_exp_handler(void)488 static void kgdboc_earlycon_pre_exp_handler(void)
489 {
490 	struct console *con;
491 	static bool already_warned;
492 	int cookie;
493 
494 	if (already_warned)
495 		return;
496 
497 	/*
498 	 * When the first normal console comes up the kernel will take all
499 	 * the boot consoles out of the list.  Really, we should stop using
500 	 * the boot console when it does that but until a TTY is registered
501 	 * we have no other choice so we keep using it.  Since not all
502 	 * serial drivers might be OK with this, print a warning once per
503 	 * boot if we detect this case.
504 	 */
505 	cookie = console_srcu_read_lock();
506 	for_each_console_srcu(con) {
507 		if (con == kgdboc_earlycon_io_ops.cons)
508 			break;
509 	}
510 	console_srcu_read_unlock(cookie);
511 	if (con)
512 		return;
513 
514 	already_warned = true;
515 	pr_warn("kgdboc_earlycon is still using bootconsole\n");
516 }
517 
kgdboc_earlycon_deferred_exit(struct console * con)518 static int kgdboc_earlycon_deferred_exit(struct console *con)
519 {
520 	/*
521 	 * If we get here it means the boot console is going away but we
522 	 * don't yet have a suitable replacement.  Don't pass through to
523 	 * the original exit routine.  We'll call it later in our deinit()
524 	 * function.  For now, restore the original exit() function pointer
525 	 * as a sentinal that we've hit this point.
526 	 */
527 	con->exit = earlycon_orig_exit;
528 
529 	return 0;
530 }
531 
kgdboc_earlycon_deinit(void)532 static void kgdboc_earlycon_deinit(void)
533 {
534 	if (!kgdboc_earlycon_io_ops.cons)
535 		return;
536 
537 	if (kgdboc_earlycon_io_ops.cons->exit == kgdboc_earlycon_deferred_exit)
538 		/*
539 		 * kgdboc_earlycon is exiting but original boot console exit
540 		 * was never called (AKA kgdboc_earlycon_deferred_exit()
541 		 * didn't ever run).  Undo our trap.
542 		 */
543 		kgdboc_earlycon_io_ops.cons->exit = earlycon_orig_exit;
544 	else if (kgdboc_earlycon_io_ops.cons->exit)
545 		/*
546 		 * We skipped calling the exit() routine so we could try to
547 		 * keep using the boot console even after it went away.  We're
548 		 * finally done so call the function now.
549 		 */
550 		kgdboc_earlycon_io_ops.cons->exit(kgdboc_earlycon_io_ops.cons);
551 
552 	kgdboc_earlycon_io_ops.cons = NULL;
553 }
554 
555 static struct kgdb_io kgdboc_earlycon_io_ops = {
556 	.name			= "kgdboc_earlycon",
557 	.read_char		= kgdboc_earlycon_get_char,
558 	.write_char		= kgdboc_earlycon_put_char,
559 	.pre_exception		= kgdboc_earlycon_pre_exp_handler,
560 	.deinit			= kgdboc_earlycon_deinit,
561 };
562 
563 #define MAX_CONSOLE_NAME_LEN (sizeof((struct console *) 0)->name)
564 static char kgdboc_earlycon_param[MAX_CONSOLE_NAME_LEN] __initdata;
565 static bool kgdboc_earlycon_late_enable __initdata;
566 
kgdboc_earlycon_init(char * opt)567 static int __init kgdboc_earlycon_init(char *opt)
568 {
569 	struct console *con;
570 
571 	kdb_init(KDB_INIT_EARLY);
572 
573 	/*
574 	 * Look for a matching console, or if the name was left blank just
575 	 * pick the first one we find.
576 	 */
577 
578 	/*
579 	 * Hold the console_list_lock to guarantee that no consoles are
580 	 * unregistered until the kgdboc_earlycon setup is complete.
581 	 * Trapping the exit() callback relies on exit() not being
582 	 * called until the trap is setup. This also allows safe
583 	 * traversal of the console list and race-free reading of @flags.
584 	 */
585 	console_list_lock();
586 	for_each_console(con) {
587 		if (con->write && con->read &&
588 		    (con->flags & (CON_BOOT | CON_ENABLED)) &&
589 		    (!opt || !opt[0] || strcmp(con->name, opt) == 0))
590 			break;
591 	}
592 
593 	if (!con) {
594 		/*
595 		 * Both earlycon and kgdboc_earlycon are initialized during
596 		 * early parameter parsing. We cannot guarantee earlycon gets
597 		 * in first and, in any case, on ACPI systems earlycon may
598 		 * defer its own initialization (usually to somewhere within
599 		 * setup_arch() ). To cope with either of these situations
600 		 * we can defer our own initialization to a little later in
601 		 * the boot.
602 		 */
603 		if (!kgdboc_earlycon_late_enable) {
604 			pr_info("No suitable earlycon yet, will try later\n");
605 			if (opt)
606 				strscpy(kgdboc_earlycon_param, opt,
607 					sizeof(kgdboc_earlycon_param));
608 			kgdboc_earlycon_late_enable = true;
609 		} else {
610 			pr_info("Couldn't find kgdb earlycon\n");
611 		}
612 		goto unlock;
613 	}
614 
615 	kgdboc_earlycon_io_ops.cons = con;
616 	pr_info("Going to register kgdb with earlycon '%s'\n", con->name);
617 	if (kgdb_register_io_module(&kgdboc_earlycon_io_ops) != 0) {
618 		kgdboc_earlycon_io_ops.cons = NULL;
619 		pr_info("Failed to register kgdb with earlycon\n");
620 	} else {
621 		/* Trap exit so we can keep earlycon longer if needed. */
622 		earlycon_orig_exit = con->exit;
623 		con->exit = kgdboc_earlycon_deferred_exit;
624 	}
625 
626 unlock:
627 	console_list_unlock();
628 
629 	/* Non-zero means malformed option so we always return zero */
630 	return 0;
631 }
632 
633 early_param("kgdboc_earlycon", kgdboc_earlycon_init);
634 
635 /*
636  * This is only intended for the late adoption of an early console.
637  *
638  * It is not a reliable way to adopt regular consoles because we can not
639  * control what order console initcalls are made and, in any case, many
640  * regular consoles are registered much later in the boot process than
641  * the console initcalls!
642  */
kgdboc_earlycon_late_init(void)643 static int __init kgdboc_earlycon_late_init(void)
644 {
645 	if (kgdboc_earlycon_late_enable)
646 		kgdboc_earlycon_init(kgdboc_earlycon_param);
647 	return 0;
648 }
649 console_initcall(kgdboc_earlycon_late_init);
650 
651 #endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
652 
653 module_init(init_kgdboc);
654 module_exit(exit_kgdboc);
655 module_param_call(kgdboc, param_set_kgdboc_var, param_get_string, &kps, 0644);
656 MODULE_PARM_DESC(kgdboc, "<serial_device>[,baud]");
657 MODULE_DESCRIPTION("KGDB Console TTY Driver");
658 MODULE_LICENSE("GPL");
659