1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  4 */
  5
  6#include <linux/irqreturn.h>
  7#include <linux/kd.h>
  8#include <linux/sched/signal.h>
  9#include <linux/slab.h>
 10
 11#include "chan.h"
 12#include <irq_kern.h>
 13#include <irq_user.h>
 14#include <kern_util.h>
 15#include <os.h>
 16
 17#define LINE_BUFSIZE 4096
 18
 19static irqreturn_t line_interrupt(int irq, void *data)
 20{
 21	struct chan *chan = data;
 22	struct line *line = chan->line;
 23
 24	if (line)
 25		chan_interrupt(line, irq);
 26
 27	return IRQ_HANDLED;
 28}
 29
 30/*
 31 * Returns the free space inside the ring buffer of this line.
 32 *
 33 * Should be called while holding line->lock (this does not modify data).
 34 */
 35static unsigned int write_room(struct line *line)
 36{
 37	int n;
 38
 39	if (line->buffer == NULL)
 40		return LINE_BUFSIZE - 1;
 41
 42	/* This is for the case where the buffer is wrapped! */
 43	n = line->head - line->tail;
 44
 45	if (n <= 0)
 46		n += LINE_BUFSIZE; /* The other case */
 47	return n - 1;
 48}
 49
 50unsigned int line_write_room(struct tty_struct *tty)
 51{
 52	struct line *line = tty->driver_data;
 53	unsigned long flags;
 54	unsigned int room;
 55
 56	spin_lock_irqsave(&line->lock, flags);
 57	room = write_room(line);
 58	spin_unlock_irqrestore(&line->lock, flags);
 59
 60	return room;
 61}
 62
 63unsigned int line_chars_in_buffer(struct tty_struct *tty)
 64{
 65	struct line *line = tty->driver_data;
 66	unsigned long flags;
 67	unsigned int ret;
 68
 69	spin_lock_irqsave(&line->lock, flags);
 70	/* write_room subtracts 1 for the needed NULL, so we readd it.*/
 71	ret = LINE_BUFSIZE - (write_room(line) + 1);
 72	spin_unlock_irqrestore(&line->lock, flags);
 73
 74	return ret;
 75}
 76
 77/*
 78 * This copies the content of buf into the circular buffer associated with
 79 * this line.
 80 * The return value is the number of characters actually copied, i.e. the ones
 81 * for which there was space: this function is not supposed to ever flush out
 82 * the circular buffer.
 83 *
 84 * Must be called while holding line->lock!
 85 */
 86static int buffer_data(struct line *line, const u8 *buf, size_t len)
 87{
 88	int end, room;
 89
 90	if (line->buffer == NULL) {
 91		line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
 92		if (line->buffer == NULL) {
 93			printk(KERN_ERR "buffer_data - atomic allocation "
 94			       "failed\n");
 95			return 0;
 96		}
 97		line->head = line->buffer;
 98		line->tail = line->buffer;
 99	}
100
101	room = write_room(line);
102	len = (len > room) ? room : len;
103
104	end = line->buffer + LINE_BUFSIZE - line->tail;
105
106	if (len < end) {
107		memcpy(line->tail, buf, len);
108		line->tail += len;
109	}
110	else {
111		/* The circular buffer is wrapping */
112		memcpy(line->tail, buf, end);
113		buf += end;
114		memcpy(line->buffer, buf, len - end);
115		line->tail = line->buffer + len - end;
116	}
117
118	return len;
119}
120
121/*
122 * Flushes the ring buffer to the output channels. That is, write_chan is
123 * called, passing it line->head as buffer, and an appropriate count.
124 *
125 * On exit, returns 1 when the buffer is empty,
126 * 0 when the buffer is not empty on exit,
127 * and -errno when an error occurred.
128 *
129 * Must be called while holding line->lock!*/
130static int flush_buffer(struct line *line)
131{
132	int n, count;
133
134	if ((line->buffer == NULL) || (line->head == line->tail))
135		return 1;
136
137	if (line->tail < line->head) {
138		/* line->buffer + LINE_BUFSIZE is the end of the buffer! */
139		count = line->buffer + LINE_BUFSIZE - line->head;
140
141		n = write_chan(line->chan_out, line->head, count,
142			       line->write_irq);
143		if (n < 0)
144			return n;
145		if (n == count) {
146			/*
147			 * We have flushed from ->head to buffer end, now we
148			 * must flush only from the beginning to ->tail.
149			 */
150			line->head = line->buffer;
151		} else {
152			line->head += n;
153			return 0;
154		}
155	}
156
157	count = line->tail - line->head;
158	n = write_chan(line->chan_out, line->head, count,
159		       line->write_irq);
160
161	if (n < 0)
162		return n;
163
164	line->head += n;
165	return line->head == line->tail;
166}
167
168void line_flush_buffer(struct tty_struct *tty)
169{
170	struct line *line = tty->driver_data;
171	unsigned long flags;
172
173	spin_lock_irqsave(&line->lock, flags);
174	flush_buffer(line);
175	spin_unlock_irqrestore(&line->lock, flags);
176}
177
178/*
179 * We map both ->flush_chars and ->put_char (which go in pair) onto
180 * ->flush_buffer and ->write. Hope it's not that bad.
181 */
182void line_flush_chars(struct tty_struct *tty)
183{
184	line_flush_buffer(tty);
185}
186
187ssize_t line_write(struct tty_struct *tty, const u8 *buf, size_t len)
188{
189	struct line *line = tty->driver_data;
190	unsigned long flags;
191	int n, ret = 0;
192
193	spin_lock_irqsave(&line->lock, flags);
194	if (line->head != line->tail)
195		ret = buffer_data(line, buf, len);
196	else {
197		n = write_chan(line->chan_out, buf, len,
198			       line->write_irq);
199		if (n < 0) {
200			ret = n;
201			goto out_up;
202		}
203
204		len -= n;
205		ret += n;
206		if (len > 0)
207			ret += buffer_data(line, buf + n, len);
208	}
209out_up:
210	spin_unlock_irqrestore(&line->lock, flags);
211	return ret;
212}
213
214void line_throttle(struct tty_struct *tty)
215{
216	struct line *line = tty->driver_data;
217
218	deactivate_chan(line->chan_in, line->read_irq);
219	line->throttled = 1;
220}
221
222void line_unthrottle(struct tty_struct *tty)
223{
224	struct line *line = tty->driver_data;
225
226	line->throttled = 0;
227	chan_interrupt(line, line->read_irq);
228}
229
230static irqreturn_t line_write_interrupt(int irq, void *data)
231{
232	struct chan *chan = data;
233	struct line *line = chan->line;
234	int err;
235
236	/*
237	 * Interrupts are disabled here because genirq keep irqs disabled when
238	 * calling the action handler.
239	 */
240
241	spin_lock(&line->lock);
242	err = flush_buffer(line);
243	if (err == 0) {
244		spin_unlock(&line->lock);
245		return IRQ_NONE;
246	} else if ((err < 0) && (err != -EAGAIN)) {
247		line->head = line->buffer;
248		line->tail = line->buffer;
249	}
250	spin_unlock(&line->lock);
251
252	tty_port_tty_wakeup(&line->port);
253
254	return IRQ_HANDLED;
255}
256
257int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
258{
259	const struct line_driver *driver = line->driver;
260	int err;
261
262	if (input) {
263		err = um_request_irq(UM_IRQ_ALLOC, fd, IRQ_READ,
264				     line_interrupt, 0,
265				     driver->read_irq_name, data);
266		if (err < 0)
267			return err;
268
269		line->read_irq = err;
270	}
271
272	if (output) {
273		err = um_request_irq(UM_IRQ_ALLOC, fd, IRQ_WRITE,
274				     line_write_interrupt, 0,
275				     driver->write_irq_name, data);
276		if (err < 0)
277			return err;
278
279		line->write_irq = err;
280	}
281
282	return 0;
283}
284
285static int line_activate(struct tty_port *port, struct tty_struct *tty)
286{
287	int ret;
288	struct line *line = tty->driver_data;
289
290	ret = enable_chan(line);
291	if (ret)
292		return ret;
293
294	if (!line->sigio) {
295		chan_enable_winch(line->chan_out, port);
296		line->sigio = 1;
297	}
298
299	chan_window_size(line, &tty->winsize.ws_row,
300		&tty->winsize.ws_col);
301
302	return 0;
303}
304
305static void unregister_winch(struct tty_struct *tty);
306
307static void line_destruct(struct tty_port *port)
308{
309	struct tty_struct *tty = tty_port_tty_get(port);
310	struct line *line = tty->driver_data;
311
312	if (line->sigio) {
313		unregister_winch(tty);
314		line->sigio = 0;
315	}
316}
317
318static const struct tty_port_operations line_port_ops = {
319	.activate = line_activate,
320	.destruct = line_destruct,
321};
322
323int line_open(struct tty_struct *tty, struct file *filp)
324{
325	struct line *line = tty->driver_data;
326
327	return tty_port_open(&line->port, tty, filp);
328}
329
330int line_install(struct tty_driver *driver, struct tty_struct *tty,
331		 struct line *line)
332{
333	int ret;
334
335	ret = tty_standard_install(driver, tty);
336	if (ret)
337		return ret;
338
339	tty->driver_data = line;
340
341	return 0;
342}
343
344void line_close(struct tty_struct *tty, struct file * filp)
345{
346	struct line *line = tty->driver_data;
347
348	tty_port_close(&line->port, tty, filp);
349}
350
351void line_hangup(struct tty_struct *tty)
352{
353	struct line *line = tty->driver_data;
354
355	tty_port_hangup(&line->port);
356}
357
358void close_lines(struct line *lines, int nlines)
359{
360	int i;
361
362	for(i = 0; i < nlines; i++)
363		close_chan(&lines[i]);
364}
365
366int setup_one_line(struct line *lines, int n, char *init,
367		   const struct chan_opts *opts, char **error_out)
368{
369	struct line *line = &lines[n];
370	struct tty_driver *driver = line->driver->driver;
371	int err = -EINVAL;
372
373	if (line->port.count) {
374		*error_out = "Device is already open";
375		goto out;
376	}
377
378	if (!strcmp(init, "none")) {
379		if (line->valid) {
380			line->valid = 0;
381			kfree(line->init_str);
382			tty_unregister_device(driver, n);
383			parse_chan_pair(NULL, line, n, opts, error_out);
384			err = 0;
385		}
386		*error_out = "configured as 'none'";
387	} else {
388		char *new = kstrdup(init, GFP_KERNEL);
389		if (!new) {
390			*error_out = "Failed to allocate memory";
391			return -ENOMEM;
392		}
393		if (line->valid) {
394			tty_unregister_device(driver, n);
395			kfree(line->init_str);
396		}
397		line->init_str = new;
398		line->valid = 1;
399		err = parse_chan_pair(new, line, n, opts, error_out);
400		if (!err) {
401			struct device *d = tty_port_register_device(&line->port,
402					driver, n, NULL);
403			if (IS_ERR(d)) {
404				*error_out = "Failed to register device";
405				err = PTR_ERR(d);
406				parse_chan_pair(NULL, line, n, opts, error_out);
407			}
408		}
409		if (err) {
410			*error_out = "failed to parse channel pair";
411			line->init_str = NULL;
412			line->valid = 0;
413			kfree(new);
414		}
415	}
416out:
417	return err;
418}
419
420/*
421 * Common setup code for both startup command line and mconsole initialization.
422 * @lines contains the array (of size @num) to modify;
423 * @init is the setup string;
424 * @error_out is an error string in the case of failure;
425 */
426
427int line_setup(char **conf, unsigned int num, char **def,
428	       char *init, char *name)
429{
430	char *error;
431
432	if (*init == '=') {
433		/*
434		 * We said con=/ssl= instead of con#=, so we are configuring all
435		 * consoles at once.
436		 */
437		*def = init + 1;
438	} else {
439		char *end;
440		unsigned n = simple_strtoul(init, &end, 0);
441
442		if (*end != '=') {
443			error = "Couldn't parse device number";
444			goto out;
445		}
446		if (n >= num) {
447			error = "Device number out of range";
448			goto out;
449		}
450		conf[n] = end + 1;
451	}
452	return 0;
453
454out:
455	printk(KERN_ERR "Failed to set up %s with "
456	       "configuration string \"%s\" : %s\n", name, init, error);
457	return -EINVAL;
458}
459
460int line_config(struct line *lines, unsigned int num, char *str,
461		const struct chan_opts *opts, char **error_out)
462{
463	char *end;
464	int n;
465
466	if (*str == '=') {
467		*error_out = "Can't configure all devices from mconsole";
468		return -EINVAL;
469	}
470
471	n = simple_strtoul(str, &end, 0);
472	if (*end++ != '=') {
473		*error_out = "Couldn't parse device number";
474		return -EINVAL;
475	}
476	if (n >= num) {
477		*error_out = "Device number out of range";
478		return -EINVAL;
479	}
480
481	return setup_one_line(lines, n, end, opts, error_out);
482}
483
484int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
485		    int size, char **error_out)
486{
487	struct line *line;
488	char *end;
489	int dev, n = 0;
490
491	dev = simple_strtoul(name, &end, 0);
492	if ((*end != '\0') || (end == name)) {
493		*error_out = "line_get_config failed to parse device number";
494		return 0;
495	}
496
497	if ((dev < 0) || (dev >= num)) {
498		*error_out = "device number out of range";
499		return 0;
500	}
501
502	line = &lines[dev];
503
504	if (!line->valid)
505		CONFIG_CHUNK(str, size, n, "none", 1);
506	else {
507		struct tty_struct *tty = tty_port_tty_get(&line->port);
508		if (tty == NULL) {
509			CONFIG_CHUNK(str, size, n, line->init_str, 1);
510		} else {
511			n = chan_config_string(line, str, size, error_out);
512			tty_kref_put(tty);
513		}
514	}
515
516	return n;
517}
518
519int line_id(char **str, int *start_out, int *end_out)
520{
521	char *end;
522	int n;
523
524	n = simple_strtoul(*str, &end, 0);
525	if ((*end != '\0') || (end == *str))
526		return -1;
527
528	*str = end;
529	*start_out = n;
530	*end_out = n;
531	return n;
532}
533
534int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
535{
536	if (n >= num) {
537		*error_out = "Device number out of range";
538		return -EINVAL;
539	}
540	return setup_one_line(lines, n, "none", NULL, error_out);
541}
542
543int register_lines(struct line_driver *line_driver,
544		   const struct tty_operations *ops,
545		   struct line *lines, int nlines)
546{
547	struct tty_driver *driver;
548	int err;
549	int i;
550
551	driver = tty_alloc_driver(nlines, TTY_DRIVER_REAL_RAW |
552			TTY_DRIVER_DYNAMIC_DEV);
553	if (IS_ERR(driver))
554		return PTR_ERR(driver);
555
556	driver->driver_name = line_driver->name;
557	driver->name = line_driver->device_name;
558	driver->major = line_driver->major;
559	driver->minor_start = line_driver->minor_start;
560	driver->type = line_driver->type;
561	driver->subtype = line_driver->subtype;
 
562	driver->init_termios = tty_std_termios;
563
564	for (i = 0; i < nlines; i++) {
565		tty_port_init(&lines[i].port);
566		lines[i].port.ops = &line_port_ops;
567		spin_lock_init(&lines[i].lock);
568		lines[i].driver = line_driver;
569		INIT_LIST_HEAD(&lines[i].chan_list);
570	}
571	tty_set_operations(driver, ops);
572
573	err = tty_register_driver(driver);
574	if (err) {
575		printk(KERN_ERR "register_lines : can't register %s driver\n",
576		       line_driver->name);
577		tty_driver_kref_put(driver);
578		for (i = 0; i < nlines; i++)
579			tty_port_destroy(&lines[i].port);
580		return err;
581	}
582
583	line_driver->driver = driver;
584	mconsole_register_dev(&line_driver->mc);
585	return 0;
586}
587
588static DEFINE_SPINLOCK(winch_handler_lock);
589static LIST_HEAD(winch_handlers);
590
591struct winch {
592	struct list_head list;
593	int fd;
594	int tty_fd;
595	int pid;
596	struct tty_port *port;
597	unsigned long stack;
598	struct work_struct work;
599};
600
601static void __free_winch(struct work_struct *work)
602{
603	struct winch *winch = container_of(work, struct winch, work);
604	um_free_irq(WINCH_IRQ, winch);
605
606	if (winch->pid != -1)
607		os_kill_process(winch->pid, 1);
608	if (winch->stack != 0)
609		free_stack(winch->stack, 0);
610	kfree(winch);
611}
612
613static void free_winch(struct winch *winch)
614{
615	int fd = winch->fd;
616	winch->fd = -1;
617	if (fd != -1)
618		os_close_file(fd);
619	__free_winch(&winch->work);
620}
621
622static irqreturn_t winch_interrupt(int irq, void *data)
623{
624	struct winch *winch = data;
625	struct tty_struct *tty;
626	struct line *line;
627	int fd = winch->fd;
628	int err;
629	char c;
630	struct pid *pgrp;
631
632	if (fd != -1) {
633		err = generic_read(fd, &c, NULL);
634		/* A read of 2 means the winch thread failed and has warned */
635		if (err < 0 || (err == 1 && c == 2)) {
636			if (err != -EAGAIN) {
637				winch->fd = -1;
638				list_del(&winch->list);
639				os_close_file(fd);
640				if (err < 0) {
641					printk(KERN_ERR "winch_interrupt : read failed, errno = %d\n",
642					       -err);
643					printk(KERN_ERR "fd %d is losing SIGWINCH support\n",
644					       winch->tty_fd);
645				}
646				INIT_WORK(&winch->work, __free_winch);
647				schedule_work(&winch->work);
648				return IRQ_HANDLED;
649			}
650			goto out;
651		}
652	}
653	tty = tty_port_tty_get(winch->port);
654	if (tty != NULL) {
655		line = tty->driver_data;
656		if (line != NULL) {
657			chan_window_size(line, &tty->winsize.ws_row,
658					 &tty->winsize.ws_col);
659			pgrp = tty_get_pgrp(tty);
660			if (pgrp)
661				kill_pgrp(pgrp, SIGWINCH, 1);
662			put_pid(pgrp);
663		}
664		tty_kref_put(tty);
665	}
666 out:
667	return IRQ_HANDLED;
668}
669
670void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
671			unsigned long stack)
672{
673	struct winch *winch;
674
675	winch = kmalloc(sizeof(*winch), GFP_KERNEL);
676	if (winch == NULL) {
677		printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
678		goto cleanup;
679	}
680
681	*winch = ((struct winch) { .fd  	= fd,
 
682				   .tty_fd 	= tty_fd,
683				   .pid  	= pid,
684				   .port 	= port,
685				   .stack	= stack });
686
687	spin_lock(&winch_handler_lock);
688	list_add(&winch->list, &winch_handlers);
689	spin_unlock(&winch_handler_lock);
690
691	if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
692			   IRQF_SHARED, "winch", winch) < 0) {
693		printk(KERN_ERR "register_winch_irq - failed to register "
694		       "IRQ\n");
695		spin_lock(&winch_handler_lock);
696		list_del(&winch->list);
697		spin_unlock(&winch_handler_lock);
698		goto out_free;
699	}
 
 
 
 
700
701	return;
702
703 out_free:
704	kfree(winch);
705 cleanup:
706	os_kill_process(pid, 1);
707	os_close_file(fd);
708	if (stack != 0)
709		free_stack(stack, 0);
710}
711
712static void unregister_winch(struct tty_struct *tty)
713{
714	struct list_head *ele, *next;
715	struct winch *winch;
716	struct tty_struct *wtty;
717
718	spin_lock(&winch_handler_lock);
719
720	list_for_each_safe(ele, next, &winch_handlers) {
721		winch = list_entry(ele, struct winch, list);
722		wtty = tty_port_tty_get(winch->port);
723		if (wtty == tty) {
724			list_del(&winch->list);
725			spin_unlock(&winch_handler_lock);
726			free_winch(winch);
727			break;
728		}
729		tty_kref_put(wtty);
730	}
731	spin_unlock(&winch_handler_lock);
732}
733
734static void winch_cleanup(void)
735{
736	struct winch *winch;
737
738	spin_lock(&winch_handler_lock);
739	while ((winch = list_first_entry_or_null(&winch_handlers,
740						 struct winch, list))) {
741		list_del(&winch->list);
742		spin_unlock(&winch_handler_lock);
743
744		free_winch(winch);
745
746		spin_lock(&winch_handler_lock);
747	}
748
749	spin_unlock(&winch_handler_lock);
750}
751__uml_exitcall(winch_cleanup);
752
753char *add_xterm_umid(char *base)
754{
755	char *umid, *title;
756	int len;
757
758	umid = get_umid();
759	if (*umid == '\0')
760		return base;
761
762	len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
763	title = kmalloc(len, GFP_KERNEL);
764	if (title == NULL) {
765		printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
766		return base;
767	}
768
769	snprintf(title, len, "%s (%s)", base, umid);
770	return title;
771}