arch/um/drivers/line.c

   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
  19 static 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  */
  35 static 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
  50 int line_write_room(struct tty_struct *tty)
  51 {
  52         struct line *line = tty->driver_data;
  53         unsigned long flags;
  54         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
  63 int line_chars_in_buffer(struct tty_struct *tty)
  64 {
  65         struct line *line = tty->driver_data;
  66         unsigned long flags;
  67         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  */
  86 static int buffer_data(struct line *line, const char *buf, int 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!*/
 130 static 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->driver->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->driver->write_irq);
 160
 161         if (n < 0)
 162                 return n;
 163
 164         line->head += n;
 165         return line->head == line->tail;
 166 }
 167
 168 void 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  */
 182 void line_flush_chars(struct tty_struct *tty)
 183 {
 184         line_flush_buffer(tty);
 185 }
 186
 187 int line_write(struct tty_struct *tty, const unsigned char *buf, int 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->driver->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         }
 209 out_up:
 210         spin_unlock_irqrestore(&line->lock, flags);
 211         return ret;
 212 }
 213
 214 void line_set_termios(struct tty_struct *tty, struct ktermios * old)
 215 {
 216         /* nothing */
 217 }
 218
 219 void line_throttle(struct tty_struct *tty)
 220 {
 221         struct line *line = tty->driver_data;
 222
 223         deactivate_chan(line->chan_in, line->driver->read_irq);
 224         line->throttled = 1;
 225 }
 226
 227 void line_unthrottle(struct tty_struct *tty)
 228 {
 229         struct line *line = tty->driver_data;
 230
 231         line->throttled = 0;
 232         chan_interrupt(line, line->driver->read_irq);
 233 }
 234
 235 static irqreturn_t line_write_interrupt(int irq, void *data)
 236 {
 237         struct chan *chan = data;
 238         struct line *line = chan->line;
 239         int err;
 240
 241         /*
 242          * Interrupts are disabled here because genirq keep irqs disabled when
 243          * calling the action handler.
 244          */
 245
 246         spin_lock(&line->lock);
 247         err = flush_buffer(line);
 248         if (err == 0) {
 249                 spin_unlock(&line->lock);
 250                 return IRQ_NONE;
 251         } else if ((err < 0) && (err != -EAGAIN)) {
 252                 line->head = line->buffer;
 253                 line->tail = line->buffer;
 254         }
 255         spin_unlock(&line->lock);
 256
 257         tty_port_tty_wakeup(&line->port);
 258
 259         return IRQ_HANDLED;
 260 }
 261
 262 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
 263 {
 264         const struct line_driver *driver = line->driver;
 265         int err;
 266
 267         if (input) {
 268                 err = um_request_irq(driver->read_irq, fd, IRQ_READ,
 269                                      line_interrupt, IRQF_SHARED,
 270                                      driver->read_irq_name, data);
 271                 if (err < 0)
 272                         return err;
 273         }
 274
 275         if (output) {
 276                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 277                                      line_write_interrupt, IRQF_SHARED,
 278                                      driver->write_irq_name, data);
 279                 if (err < 0)
 280                         return err;
 281         }
 282
 283         return 0;
 284 }
 285
 286 static int line_activate(struct tty_port *port, struct tty_struct *tty)
 287 {
 288         int ret;
 289         struct line *line = tty->driver_data;
 290
 291         ret = enable_chan(line);
 292         if (ret)
 293                 return ret;
 294
 295         if (!line->sigio) {
 296                 chan_enable_winch(line->chan_out, port);
 297                 line->sigio = 1;
 298         }
 299
 300         chan_window_size(line, &tty->winsize.ws_row,
 301                 &tty->winsize.ws_col);
 302
 303         return 0;
 304 }
 305
 306 static void unregister_winch(struct tty_struct *tty);
 307
 308 static void line_destruct(struct tty_port *port)
 309 {
 310         struct tty_struct *tty = tty_port_tty_get(port);
 311         struct line *line = tty->driver_data;
 312
 313         if (line->sigio) {
 314                 unregister_winch(tty);
 315                 line->sigio = 0;
 316         }
 317 }
 318
 319 static const struct tty_port_operations line_port_ops = {
 320         .activate = line_activate,
 321         .destruct = line_destruct,
 322 };
 323
 324 int line_open(struct tty_struct *tty, struct file *filp)
 325 {
 326         struct line *line = tty->driver_data;
 327
 328         return tty_port_open(&line->port, tty, filp);
 329 }
 330
 331 int line_install(struct tty_driver *driver, struct tty_struct *tty,
 332                  struct line *line)
 333 {
 334         int ret;
 335
 336         ret = tty_standard_install(driver, tty);
 337         if (ret)
 338                 return ret;
 339
 340         tty->driver_data = line;
 341
 342         return 0;
 343 }
 344
 345 void line_close(struct tty_struct *tty, struct file * filp)
 346 {
 347         struct line *line = tty->driver_data;
 348
 349         tty_port_close(&line->port, tty, filp);
 350 }
 351
 352 void line_hangup(struct tty_struct *tty)
 353 {
 354         struct line *line = tty->driver_data;
 355
 356         tty_port_hangup(&line->port);
 357 }
 358
 359 void close_lines(struct line *lines, int nlines)
 360 {
 361         int i;
 362
 363         for(i = 0; i < nlines; i++)
 364                 close_chan(&lines[i]);
 365 }
 366
 367 int setup_one_line(struct line *lines, int n, char *init,
 368                    const struct chan_opts *opts, char **error_out)
 369 {
 370         struct line *line = &lines[n];
 371         struct tty_driver *driver = line->driver->driver;
 372         int err = -EINVAL;
 373
 374         if (line->port.count) {
 375                 *error_out = "Device is already open";
 376                 goto out;
 377         }
 378
 379         if (!strcmp(init, "none")) {
 380                 if (line->valid) {
 381                         line->valid = 0;
 382                         kfree(line->init_str);
 383                         tty_unregister_device(driver, n);
 384                         parse_chan_pair(NULL, line, n, opts, error_out);
 385                         err = 0;
 386                 }
 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                         line->init_str = NULL;
 411                         line->valid = 0;
 412                         kfree(new);
 413                 }
 414         }
 415 out:
 416         return err;
 417 }
 418
 419 /*
 420  * Common setup code for both startup command line and mconsole initialization.
 421  * @lines contains the array (of size @num) to modify;
 422  * @init is the setup string;
 423  * @error_out is an error string in the case of failure;
 424  */
 425
 426 int line_setup(char **conf, unsigned int num, char **def,
 427                char *init, char *name)
 428 {
 429         char *error;
 430
 431         if (*init == '=') {
 432                 /*
 433                  * We said con=/ssl= instead of con#=, so we are configuring all
 434                  * consoles at once.
 435                  */
 436                 *def = init + 1;
 437         } else {
 438                 char *end;
 439                 unsigned n = simple_strtoul(init, &end, 0);
 440
 441                 if (*end != '=') {
 442                         error = "Couldn't parse device number";
 443                         goto out;
 444                 }
 445                 if (n >= num) {
 446                         error = "Device number out of range";
 447                         goto out;
 448                 }
 449                 conf[n] = end + 1;
 450         }
 451         return 0;
 452
 453 out:
 454         printk(KERN_ERR "Failed to set up %s with "
 455                "configuration string \"%s\" : %s\n", name, init, error);
 456         return -EINVAL;
 457 }
 458
 459 int line_config(struct line *lines, unsigned int num, char *str,
 460                 const struct chan_opts *opts, char **error_out)
 461 {
 462         char *end;
 463         int n;
 464
 465         if (*str == '=') {
 466                 *error_out = "Can't configure all devices from mconsole";
 467                 return -EINVAL;
 468         }
 469
 470         n = simple_strtoul(str, &end, 0);
 471         if (*end++ != '=') {
 472                 *error_out = "Couldn't parse device number";
 473                 return -EINVAL;
 474         }
 475         if (n >= num) {
 476                 *error_out = "Device number out of range";
 477                 return -EINVAL;
 478         }
 479
 480         return setup_one_line(lines, n, end, opts, error_out);
 481 }
 482
 483 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
 484                     int size, char **error_out)
 485 {
 486         struct line *line;
 487         char *end;
 488         int dev, n = 0;
 489
 490         dev = simple_strtoul(name, &end, 0);
 491         if ((*end != '\0') || (end == name)) {
 492                 *error_out = "line_get_config failed to parse device number";
 493                 return 0;
 494         }
 495
 496         if ((dev < 0) || (dev >= num)) {
 497                 *error_out = "device number out of range";
 498                 return 0;
 499         }
 500
 501         line = &lines[dev];
 502
 503         if (!line->valid)
 504                 CONFIG_CHUNK(str, size, n, "none", 1);
 505         else {
 506                 struct tty_struct *tty = tty_port_tty_get(&line->port);
 507                 if (tty == NULL) {
 508                         CONFIG_CHUNK(str, size, n, line->init_str, 1);
 509                 } else {
 510                         n = chan_config_string(line, str, size, error_out);
 511                         tty_kref_put(tty);
 512                 }
 513         }
 514
 515         return n;
 516 }
 517
 518 int line_id(char **str, int *start_out, int *end_out)
 519 {
 520         char *end;
 521         int n;
 522
 523         n = simple_strtoul(*str, &end, 0);
 524         if ((*end != '\0') || (end == *str))
 525                 return -1;
 526
 527         *str = end;
 528         *start_out = n;
 529         *end_out = n;
 530         return n;
 531 }
 532
 533 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
 534 {
 535         if (n >= num) {
 536                 *error_out = "Device number out of range";
 537                 return -EINVAL;
 538         }
 539         return setup_one_line(lines, n, "none", NULL, error_out);
 540 }
 541
 542 int register_lines(struct line_driver *line_driver,
 543                    const struct tty_operations *ops,
 544                    struct line *lines, int nlines)
 545 {
 546         struct tty_driver *driver = alloc_tty_driver(nlines);
 547         int err;
 548         int i;
 549
 550         if (!driver)
 551                 return -ENOMEM;
 552
 553         driver->driver_name = line_driver->name;
 554         driver->name = line_driver->device_name;
 555         driver->major = line_driver->major;
 556         driver->minor_start = line_driver->minor_start;
 557         driver->type = line_driver->type;
 558         driver->subtype = line_driver->subtype;
 559         driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 560         driver->init_termios = tty_std_termios;
 561
 562         for (i = 0; i < nlines; i++) {
 563                 tty_port_init(&lines[i].port);
 564                 lines[i].port.ops = &line_port_ops;
 565                 spin_lock_init(&lines[i].lock);
 566                 lines[i].driver = line_driver;
 567                 INIT_LIST_HEAD(&lines[i].chan_list);
 568         }
 569         tty_set_operations(driver, ops);
 570
 571         err = tty_register_driver(driver);
 572         if (err) {
 573                 printk(KERN_ERR "register_lines : can't register %s driver\n",
 574                        line_driver->name);
 575                 put_tty_driver(driver);
 576                 for (i = 0; i < nlines; i++)
 577                         tty_port_destroy(&lines[i].port);
 578                 return err;
 579         }
 580
 581         line_driver->driver = driver;
 582         mconsole_register_dev(&line_driver->mc);
 583         return 0;
 584 }
 585
 586 static DEFINE_SPINLOCK(winch_handler_lock);
 587 static LIST_HEAD(winch_handlers);
 588
 589 struct winch {
 590         struct list_head list;
 591         int fd;
 592         int tty_fd;
 593         int pid;
 594         struct tty_port *port;
 595         unsigned long stack;
 596         struct work_struct work;
 597 };
 598
 599 static void __free_winch(struct work_struct *work)
 600 {
 601         struct winch *winch = container_of(work, struct winch, work);
 602         um_free_irq(WINCH_IRQ, winch);
 603
 604         if (winch->pid != -1)
 605                 os_kill_process(winch->pid, 1);
 606         if (winch->stack != 0)
 607                 free_stack(winch->stack, 0);
 608         kfree(winch);
 609 }
 610
 611 static void free_winch(struct winch *winch)
 612 {
 613         int fd = winch->fd;
 614         winch->fd = -1;
 615         if (fd != -1)
 616                 os_close_file(fd);
 617         __free_winch(&winch->work);
 618 }
 619
 620 static irqreturn_t winch_interrupt(int irq, void *data)
 621 {
 622         struct winch *winch = data;
 623         struct tty_struct *tty;
 624         struct line *line;
 625         int fd = winch->fd;
 626         int err;
 627         char c;
 628         struct pid *pgrp;
 629
 630         if (fd != -1) {
 631                 err = generic_read(fd, &c, NULL);
 632                 if (err < 0) {
 633                         if (err != -EAGAIN) {
 634                                 winch->fd = -1;
 635                                 list_del(&winch->list);
 636                                 os_close_file(fd);
 637                                 printk(KERN_ERR "winch_interrupt : "
 638                                        "read failed, errno = %d\n", -err);
 639                                 printk(KERN_ERR "fd %d is losing SIGWINCH "
 640                                        "support\n", winch->tty_fd);
 641                                 INIT_WORK(&winch->work, __free_winch);
 642                                 schedule_work(&winch->work);
 643                                 return IRQ_HANDLED;
 644                         }
 645                         goto out;
 646                 }
 647         }
 648         tty = tty_port_tty_get(winch->port);
 649         if (tty != NULL) {
 650                 line = tty->driver_data;
 651                 if (line != NULL) {
 652                         chan_window_size(line, &tty->winsize.ws_row,
 653                                          &tty->winsize.ws_col);
 654                         pgrp = tty_get_pgrp(tty);
 655                         if (pgrp)
 656                                 kill_pgrp(pgrp, SIGWINCH, 1);
 657                         put_pid(pgrp);
 658                 }
 659                 tty_kref_put(tty);
 660         }
 661  out:
 662         return IRQ_HANDLED;
 663 }
 664
 665 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
 666                         unsigned long stack)
 667 {
 668         struct winch *winch;
 669
 670         winch = kmalloc(sizeof(*winch), GFP_KERNEL);
 671         if (winch == NULL) {
 672                 printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
 673                 goto cleanup;
 674         }
 675
 676         *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
 677                                    .fd          = fd,
 678                                    .tty_fd      = tty_fd,
 679                                    .pid         = pid,
 680                                    .port        = port,
 681                                    .stack       = stack });
 682
 683         if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
 684                            IRQF_SHARED, "winch", winch) < 0) {
 685                 printk(KERN_ERR "register_winch_irq - failed to register "
 686                        "IRQ\n");
 687                 goto out_free;
 688         }
 689
 690         spin_lock(&winch_handler_lock);
 691         list_add(&winch->list, &winch_handlers);
 692         spin_unlock(&winch_handler_lock);
 693
 694         return;
 695
 696  out_free:
 697         kfree(winch);
 698  cleanup:
 699         os_kill_process(pid, 1);
 700         os_close_file(fd);
 701         if (stack != 0)
 702                 free_stack(stack, 0);
 703 }
 704
 705 static void unregister_winch(struct tty_struct *tty)
 706 {
 707         struct list_head *ele, *next;
 708         struct winch *winch;
 709         struct tty_struct *wtty;
 710
 711         spin_lock(&winch_handler_lock);
 712
 713         list_for_each_safe(ele, next, &winch_handlers) {
 714                 winch = list_entry(ele, struct winch, list);
 715                 wtty = tty_port_tty_get(winch->port);
 716                 if (wtty == tty) {
 717                         list_del(&winch->list);
 718                         spin_unlock(&winch_handler_lock);
 719                         free_winch(winch);
 720                         break;
 721                 }
 722                 tty_kref_put(wtty);
 723         }
 724         spin_unlock(&winch_handler_lock);
 725 }
 726
 727 static void winch_cleanup(void)
 728 {
 729         struct winch *winch;
 730
 731         spin_lock(&winch_handler_lock);
 732         while ((winch = list_first_entry_or_null(&winch_handlers,
 733                                                  struct winch, list))) {
 734                 list_del(&winch->list);
 735                 spin_unlock(&winch_handler_lock);
 736
 737                 free_winch(winch);
 738
 739                 spin_lock(&winch_handler_lock);
 740         }
 741
 742         spin_unlock(&winch_handler_lock);
 743 }
 744 __uml_exitcall(winch_cleanup);
 745
 746 char *add_xterm_umid(char *base)
 747 {
 748         char *umid, *title;
 749         int len;
 750
 751         umid = get_umid();
 752         if (*umid == '\0')
 753                 return base;
 754
 755         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
 756         title = kmalloc(len, GFP_KERNEL);
 757         if (title == NULL) {
 758                 printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
 759                 return base;
 760         }
 761
 762         snprintf(title, len, "%s (%s)", base, umid);
 763         return title;
 764 }