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 = 0;
 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)
 272                 return err;
 273         if (output)
 274                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 275                                      line_write_interrupt, IRQF_SHARED,
 276                                      driver->write_irq_name, data);
 277         return err;
 278 }
 279
 280 static int line_activate(struct tty_port *port, struct tty_struct *tty)
 281 {
 282         int ret;
 283         struct line *line = tty->driver_data;
 284
 285         ret = enable_chan(line);
 286         if (ret)
 287                 return ret;
 288
 289         if (!line->sigio) {
 290                 chan_enable_winch(line->chan_out, port);
 291                 line->sigio = 1;
 292         }
 293
 294         chan_window_size(line, &tty->winsize.ws_row,
 295                 &tty->winsize.ws_col);
 296
 297         return 0;
 298 }
 299
 300 static void unregister_winch(struct tty_struct *tty);
 301
 302 static void line_destruct(struct tty_port *port)
 303 {
 304         struct tty_struct *tty = tty_port_tty_get(port);
 305         struct line *line = tty->driver_data;
 306
 307         if (line->sigio) {
 308                 unregister_winch(tty);
 309                 line->sigio = 0;
 310         }
 311 }
 312
 313 static const struct tty_port_operations line_port_ops = {
 314         .activate = line_activate,
 315         .destruct = line_destruct,
 316 };
 317
 318 int line_open(struct tty_struct *tty, struct file *filp)
 319 {
 320         struct line *line = tty->driver_data;
 321
 322         return tty_port_open(&line->port, tty, filp);
 323 }
 324
 325 int line_install(struct tty_driver *driver, struct tty_struct *tty,
 326                  struct line *line)
 327 {
 328         int ret;
 329
 330         ret = tty_standard_install(driver, tty);
 331         if (ret)
 332                 return ret;
 333
 334         tty->driver_data = line;
 335
 336         return 0;
 337 }
 338
 339 void line_close(struct tty_struct *tty, struct file * filp)
 340 {
 341         struct line *line = tty->driver_data;
 342
 343         tty_port_close(&line->port, tty, filp);
 344 }
 345
 346 void line_hangup(struct tty_struct *tty)
 347 {
 348         struct line *line = tty->driver_data;
 349
 350         tty_port_hangup(&line->port);
 351 }
 352
 353 void close_lines(struct line *lines, int nlines)
 354 {
 355         int i;
 356
 357         for(i = 0; i < nlines; i++)
 358                 close_chan(&lines[i]);
 359 }
 360
 361 int setup_one_line(struct line *lines, int n, char *init,
 362                    const struct chan_opts *opts, char **error_out)
 363 {
 364         struct line *line = &lines[n];
 365         struct tty_driver *driver = line->driver->driver;
 366         int err = -EINVAL;
 367
 368         if (line->port.count) {
 369                 *error_out = "Device is already open";
 370                 goto out;
 371         }
 372
 373         if (!strcmp(init, "none")) {
 374                 if (line->valid) {
 375                         line->valid = 0;
 376                         kfree(line->init_str);
 377                         tty_unregister_device(driver, n);
 378                         parse_chan_pair(NULL, line, n, opts, error_out);
 379                         err = 0;
 380                 }
 381         } else {
 382                 char *new = kstrdup(init, GFP_KERNEL);
 383                 if (!new) {
 384                         *error_out = "Failed to allocate memory";
 385                         return -ENOMEM;
 386                 }
 387                 if (line->valid) {
 388                         tty_unregister_device(driver, n);
 389                         kfree(line->init_str);
 390                 }
 391                 line->init_str = new;
 392                 line->valid = 1;
 393                 err = parse_chan_pair(new, line, n, opts, error_out);
 394                 if (!err) {
 395                         struct device *d = tty_port_register_device(&line->port,
 396                                         driver, n, NULL);
 397                         if (IS_ERR(d)) {
 398                                 *error_out = "Failed to register device";
 399                                 err = PTR_ERR(d);
 400                                 parse_chan_pair(NULL, line, n, opts, error_out);
 401                         }
 402                 }
 403                 if (err) {
 404                         line->init_str = NULL;
 405                         line->valid = 0;
 406                         kfree(new);
 407                 }
 408         }
 409 out:
 410         return err;
 411 }
 412
 413 /*
 414  * Common setup code for both startup command line and mconsole initialization.
 415  * @lines contains the array (of size @num) to modify;
 416  * @init is the setup string;
 417  * @error_out is an error string in the case of failure;
 418  */
 419
 420 int line_setup(char **conf, unsigned int num, char **def,
 421                char *init, char *name)
 422 {
 423         char *error;
 424
 425         if (*init == '=') {
 426                 /*
 427                  * We said con=/ssl= instead of con#=, so we are configuring all
 428                  * consoles at once.
 429                  */
 430                 *def = init + 1;
 431         } else {
 432                 char *end;
 433                 unsigned n = simple_strtoul(init, &end, 0);
 434
 435                 if (*end != '=') {
 436                         error = "Couldn't parse device number";
 437                         goto out;
 438                 }
 439                 if (n >= num) {
 440                         error = "Device number out of range";
 441                         goto out;
 442                 }
 443                 conf[n] = end + 1;
 444         }
 445         return 0;
 446
 447 out:
 448         printk(KERN_ERR "Failed to set up %s with "
 449                "configuration string \"%s\" : %s\n", name, init, error);
 450         return -EINVAL;
 451 }
 452
 453 int line_config(struct line *lines, unsigned int num, char *str,
 454                 const struct chan_opts *opts, char **error_out)
 455 {
 456         char *end;
 457         int n;
 458
 459         if (*str == '=') {
 460                 *error_out = "Can't configure all devices from mconsole";
 461                 return -EINVAL;
 462         }
 463
 464         n = simple_strtoul(str, &end, 0);
 465         if (*end++ != '=') {
 466                 *error_out = "Couldn't parse device number";
 467                 return -EINVAL;
 468         }
 469         if (n >= num) {
 470                 *error_out = "Device number out of range";
 471                 return -EINVAL;
 472         }
 473
 474         return setup_one_line(lines, n, end, opts, error_out);
 475 }
 476
 477 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
 478                     int size, char **error_out)
 479 {
 480         struct line *line;
 481         char *end;
 482         int dev, n = 0;
 483
 484         dev = simple_strtoul(name, &end, 0);
 485         if ((*end != '\0') || (end == name)) {
 486                 *error_out = "line_get_config failed to parse device number";
 487                 return 0;
 488         }
 489
 490         if ((dev < 0) || (dev >= num)) {
 491                 *error_out = "device number out of range";
 492                 return 0;
 493         }
 494
 495         line = &lines[dev];
 496
 497         if (!line->valid)
 498                 CONFIG_CHUNK(str, size, n, "none", 1);
 499         else {
 500                 struct tty_struct *tty = tty_port_tty_get(&line->port);
 501                 if (tty == NULL) {
 502                         CONFIG_CHUNK(str, size, n, line->init_str, 1);
 503                 } else {
 504                         n = chan_config_string(line, str, size, error_out);
 505                         tty_kref_put(tty);
 506                 }
 507         }
 508
 509         return n;
 510 }
 511
 512 int line_id(char **str, int *start_out, int *end_out)
 513 {
 514         char *end;
 515         int n;
 516
 517         n = simple_strtoul(*str, &end, 0);
 518         if ((*end != '\0') || (end == *str))
 519                 return -1;
 520
 521         *str = end;
 522         *start_out = n;
 523         *end_out = n;
 524         return n;
 525 }
 526
 527 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
 528 {
 529         if (n >= num) {
 530                 *error_out = "Device number out of range";
 531                 return -EINVAL;
 532         }
 533         return setup_one_line(lines, n, "none", NULL, error_out);
 534 }
 535
 536 int register_lines(struct line_driver *line_driver,
 537                    const struct tty_operations *ops,
 538                    struct line *lines, int nlines)
 539 {
 540         struct tty_driver *driver = alloc_tty_driver(nlines);
 541         int err;
 542         int i;
 543
 544         if (!driver)
 545                 return -ENOMEM;
 546
 547         driver->driver_name = line_driver->name;
 548         driver->name = line_driver->device_name;
 549         driver->major = line_driver->major;
 550         driver->minor_start = line_driver->minor_start;
 551         driver->type = line_driver->type;
 552         driver->subtype = line_driver->subtype;
 553         driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 554         driver->init_termios = tty_std_termios;
 555
 556         for (i = 0; i < nlines; i++) {
 557                 tty_port_init(&lines[i].port);
 558                 lines[i].port.ops = &line_port_ops;
 559                 spin_lock_init(&lines[i].lock);
 560                 lines[i].driver = line_driver;
 561                 INIT_LIST_HEAD(&lines[i].chan_list);
 562         }
 563         tty_set_operations(driver, ops);
 564
 565         err = tty_register_driver(driver);
 566         if (err) {
 567                 printk(KERN_ERR "register_lines : can't register %s driver\n",
 568                        line_driver->name);
 569                 put_tty_driver(driver);
 570                 for (i = 0; i < nlines; i++)
 571                         tty_port_destroy(&lines[i].port);
 572                 return err;
 573         }
 574
 575         line_driver->driver = driver;
 576         mconsole_register_dev(&line_driver->mc);
 577         return 0;
 578 }
 579
 580 static DEFINE_SPINLOCK(winch_handler_lock);
 581 static LIST_HEAD(winch_handlers);
 582
 583 struct winch {
 584         struct list_head list;
 585         int fd;
 586         int tty_fd;
 587         int pid;
 588         struct tty_port *port;
 589         unsigned long stack;
 590         struct work_struct work;
 591 };
 592
 593 static void __free_winch(struct work_struct *work)
 594 {
 595         struct winch *winch = container_of(work, struct winch, work);
 596         um_free_irq(WINCH_IRQ, winch);
 597
 598         if (winch->pid != -1)
 599                 os_kill_process(winch->pid, 1);
 600         if (winch->stack != 0)
 601                 free_stack(winch->stack, 0);
 602         kfree(winch);
 603 }
 604
 605 static void free_winch(struct winch *winch)
 606 {
 607         int fd = winch->fd;
 608         winch->fd = -1;
 609         if (fd != -1)
 610                 os_close_file(fd);
 611         list_del(&winch->list);
 612         __free_winch(&winch->work);
 613 }
 614
 615 static irqreturn_t winch_interrupt(int irq, void *data)
 616 {
 617         struct winch *winch = data;
 618         struct tty_struct *tty;
 619         struct line *line;
 620         int fd = winch->fd;
 621         int err;
 622         char c;
 623         struct pid *pgrp;
 624
 625         if (fd != -1) {
 626                 err = generic_read(fd, &c, NULL);
 627                 if (err < 0) {
 628                         if (err != -EAGAIN) {
 629                                 winch->fd = -1;
 630                                 list_del(&winch->list);
 631                                 os_close_file(fd);
 632                                 printk(KERN_ERR "winch_interrupt : "
 633                                        "read failed, errno = %d\n", -err);
 634                                 printk(KERN_ERR "fd %d is losing SIGWINCH "
 635                                        "support\n", winch->tty_fd);
 636                                 INIT_WORK(&winch->work, __free_winch);
 637                                 schedule_work(&winch->work);
 638                                 return IRQ_HANDLED;
 639                         }
 640                         goto out;
 641                 }
 642         }
 643         tty = tty_port_tty_get(winch->port);
 644         if (tty != NULL) {
 645                 line = tty->driver_data;
 646                 if (line != NULL) {
 647                         chan_window_size(line, &tty->winsize.ws_row,
 648                                          &tty->winsize.ws_col);
 649                         pgrp = tty_get_pgrp(tty);
 650                         if (pgrp)
 651                                 kill_pgrp(pgrp, SIGWINCH, 1);
 652                         put_pid(pgrp);
 653                 }
 654                 tty_kref_put(tty);
 655         }
 656  out:
 657         return IRQ_HANDLED;
 658 }
 659
 660 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
 661                         unsigned long stack)
 662 {
 663         struct winch *winch;
 664
 665         winch = kmalloc(sizeof(*winch), GFP_KERNEL);
 666         if (winch == NULL) {
 667                 printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
 668                 goto cleanup;
 669         }
 670
 671         *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
 672                                    .fd          = fd,
 673                                    .tty_fd      = tty_fd,
 674                                    .pid         = pid,
 675                                    .port        = port,
 676                                    .stack       = stack });
 677
 678         if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
 679                            IRQF_SHARED, "winch", winch) < 0) {
 680                 printk(KERN_ERR "register_winch_irq - failed to register "
 681                        "IRQ\n");
 682                 goto out_free;
 683         }
 684
 685         spin_lock(&winch_handler_lock);
 686         list_add(&winch->list, &winch_handlers);
 687         spin_unlock(&winch_handler_lock);
 688
 689         return;
 690
 691  out_free:
 692         kfree(winch);
 693  cleanup:
 694         os_kill_process(pid, 1);
 695         os_close_file(fd);
 696         if (stack != 0)
 697                 free_stack(stack, 0);
 698 }
 699
 700 static void unregister_winch(struct tty_struct *tty)
 701 {
 702         struct list_head *ele, *next;
 703         struct winch *winch;
 704         struct tty_struct *wtty;
 705
 706         spin_lock(&winch_handler_lock);
 707
 708         list_for_each_safe(ele, next, &winch_handlers) {
 709                 winch = list_entry(ele, struct winch, list);
 710                 wtty = tty_port_tty_get(winch->port);
 711                 if (wtty == tty) {
 712                         free_winch(winch);
 713                         break;
 714                 }
 715                 tty_kref_put(wtty);
 716         }
 717         spin_unlock(&winch_handler_lock);
 718 }
 719
 720 static void winch_cleanup(void)
 721 {
 722         struct list_head *ele, *next;
 723         struct winch *winch;
 724
 725         spin_lock(&winch_handler_lock);
 726
 727         list_for_each_safe(ele, next, &winch_handlers) {
 728                 winch = list_entry(ele, struct winch, list);
 729                 free_winch(winch);
 730         }
 731
 732         spin_unlock(&winch_handler_lock);
 733 }
 734 __uml_exitcall(winch_cleanup);
 735
 736 char *add_xterm_umid(char *base)
 737 {
 738         char *umid, *title;
 739         int len;
 740
 741         umid = get_umid();
 742         if (*umid == '\0')
 743                 return base;
 744
 745         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
 746         title = kmalloc(len, GFP_KERNEL);
 747         if (title == NULL) {
 748                 printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
 749                 return base;
 750         }
 751
 752         snprintf(title, len, "%s (%s)", base, umid);
 753         return title;
 754 }