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_put_char(struct tty_struct *tty, unsigned char ch)
 188 {
 189         return line_write(tty, &ch, sizeof(ch));
 190 }
 191
 192 int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
 193 {
 194         struct line *line = tty->driver_data;
 195         unsigned long flags;
 196         int n, ret = 0;
 197
 198         spin_lock_irqsave(&line->lock, flags);
 199         if (line->head != line->tail)
 200                 ret = buffer_data(line, buf, len);
 201         else {
 202                 n = write_chan(line->chan_out, buf, len,
 203                                line->driver->write_irq);
 204                 if (n < 0) {
 205                         ret = n;
 206                         goto out_up;
 207                 }
 208
 209                 len -= n;
 210                 ret += n;
 211                 if (len > 0)
 212                         ret += buffer_data(line, buf + n, len);
 213         }
 214 out_up:
 215         spin_unlock_irqrestore(&line->lock, flags);
 216         return ret;
 217 }
 218
 219 void line_set_termios(struct tty_struct *tty, struct ktermios * old)
 220 {
 221         /* nothing */
 222 }
 223
 224 void line_throttle(struct tty_struct *tty)
 225 {
 226         struct line *line = tty->driver_data;
 227
 228         deactivate_chan(line->chan_in, line->driver->read_irq);
 229         line->throttled = 1;
 230 }
 231
 232 void line_unthrottle(struct tty_struct *tty)
 233 {
 234         struct line *line = tty->driver_data;
 235
 236         line->throttled = 0;
 237         chan_interrupt(line, line->driver->read_irq);
 238 }
 239
 240 static irqreturn_t line_write_interrupt(int irq, void *data)
 241 {
 242         struct chan *chan = data;
 243         struct line *line = chan->line;
 244         int err;
 245
 246         /*
 247          * Interrupts are disabled here because genirq keep irqs disabled when
 248          * calling the action handler.
 249          */
 250
 251         spin_lock(&line->lock);
 252         err = flush_buffer(line);
 253         if (err == 0) {
 254                 spin_unlock(&line->lock);
 255                 return IRQ_NONE;
 256         } else if ((err < 0) && (err != -EAGAIN)) {
 257                 line->head = line->buffer;
 258                 line->tail = line->buffer;
 259         }
 260         spin_unlock(&line->lock);
 261
 262         tty_port_tty_wakeup(&line->port);
 263
 264         return IRQ_HANDLED;
 265 }
 266
 267 int line_setup_irq(int fd, int input, int output, struct line *line, void *data)
 268 {
 269         const struct line_driver *driver = line->driver;
 270         int err = 0;
 271
 272         if (input)
 273                 err = um_request_irq(driver->read_irq, fd, IRQ_READ,
 274                                      line_interrupt, IRQF_SHARED,
 275                                      driver->read_irq_name, data);
 276         if (err)
 277                 return err;
 278         if (output)
 279                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 280                                      line_write_interrupt, IRQF_SHARED,
 281                                      driver->write_irq_name, data);
 282         return err;
 283 }
 284
 285 static 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
 305 static void unregister_winch(struct tty_struct *tty);
 306
 307 static 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
 318 static const struct tty_port_operations line_port_ops = {
 319         .activate = line_activate,
 320         .destruct = line_destruct,
 321 };
 322
 323 int 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
 330 int 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
 344 void 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
 351 void line_hangup(struct tty_struct *tty)
 352 {
 353         struct line *line = tty->driver_data;
 354
 355         tty_port_hangup(&line->port);
 356 }
 357
 358 void 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
 366 int 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         } else {
 387                 char *new = kstrdup(init, GFP_KERNEL);
 388                 if (!new) {
 389                         *error_out = "Failed to allocate memory";
 390                         return -ENOMEM;
 391                 }
 392                 if (line->valid) {
 393                         tty_unregister_device(driver, n);
 394                         kfree(line->init_str);
 395                 }
 396                 line->init_str = new;
 397                 line->valid = 1;
 398                 err = parse_chan_pair(new, line, n, opts, error_out);
 399                 if (!err) {
 400                         struct device *d = tty_port_register_device(&line->port,
 401                                         driver, n, NULL);
 402                         if (IS_ERR(d)) {
 403                                 *error_out = "Failed to register device";
 404                                 err = PTR_ERR(d);
 405                                 parse_chan_pair(NULL, line, n, opts, error_out);
 406                         }
 407                 }
 408                 if (err) {
 409                         line->init_str = NULL;
 410                         line->valid = 0;
 411                         kfree(new);
 412                 }
 413         }
 414 out:
 415         return err;
 416 }
 417
 418 /*
 419  * Common setup code for both startup command line and mconsole initialization.
 420  * @lines contains the array (of size @num) to modify;
 421  * @init is the setup string;
 422  * @error_out is an error string in the case of failure;
 423  */
 424
 425 int line_setup(char **conf, unsigned int num, char **def,
 426                char *init, char *name)
 427 {
 428         char *error;
 429
 430         if (*init == '=') {
 431                 /*
 432                  * We said con=/ssl= instead of con#=, so we are configuring all
 433                  * consoles at once.
 434                  */
 435                 *def = init + 1;
 436         } else {
 437                 char *end;
 438                 unsigned n = simple_strtoul(init, &end, 0);
 439
 440                 if (*end != '=') {
 441                         error = "Couldn't parse device number";
 442                         goto out;
 443                 }
 444                 if (n >= num) {
 445                         error = "Device number out of range";
 446                         goto out;
 447                 }
 448                 conf[n] = end + 1;
 449         }
 450         return 0;
 451
 452 out:
 453         printk(KERN_ERR "Failed to set up %s with "
 454                "configuration string \"%s\" : %s\n", name, init, error);
 455         return -EINVAL;
 456 }
 457
 458 int line_config(struct line *lines, unsigned int num, char *str,
 459                 const struct chan_opts *opts, char **error_out)
 460 {
 461         char *end;
 462         int n;
 463
 464         if (*str == '=') {
 465                 *error_out = "Can't configure all devices from mconsole";
 466                 return -EINVAL;
 467         }
 468
 469         n = simple_strtoul(str, &end, 0);
 470         if (*end++ != '=') {
 471                 *error_out = "Couldn't parse device number";
 472                 return -EINVAL;
 473         }
 474         if (n >= num) {
 475                 *error_out = "Device number out of range";
 476                 return -EINVAL;
 477         }
 478
 479         return setup_one_line(lines, n, end, opts, error_out);
 480 }
 481
 482 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
 483                     int size, char **error_out)
 484 {
 485         struct line *line;
 486         char *end;
 487         int dev, n = 0;
 488
 489         dev = simple_strtoul(name, &end, 0);
 490         if ((*end != '\0') || (end == name)) {
 491                 *error_out = "line_get_config failed to parse device number";
 492                 return 0;
 493         }
 494
 495         if ((dev < 0) || (dev >= num)) {
 496                 *error_out = "device number out of range";
 497                 return 0;
 498         }
 499
 500         line = &lines[dev];
 501
 502         if (!line->valid)
 503                 CONFIG_CHUNK(str, size, n, "none", 1);
 504         else {
 505                 struct tty_struct *tty = tty_port_tty_get(&line->port);
 506                 if (tty == NULL) {
 507                         CONFIG_CHUNK(str, size, n, line->init_str, 1);
 508                 } else {
 509                         n = chan_config_string(line, str, size, error_out);
 510                         tty_kref_put(tty);
 511                 }
 512         }
 513
 514         return n;
 515 }
 516
 517 int line_id(char **str, int *start_out, int *end_out)
 518 {
 519         char *end;
 520         int n;
 521
 522         n = simple_strtoul(*str, &end, 0);
 523         if ((*end != '\0') || (end == *str))
 524                 return -1;
 525
 526         *str = end;
 527         *start_out = n;
 528         *end_out = n;
 529         return n;
 530 }
 531
 532 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
 533 {
 534         if (n >= num) {
 535                 *error_out = "Device number out of range";
 536                 return -EINVAL;
 537         }
 538         return setup_one_line(lines, n, "none", NULL, error_out);
 539 }
 540
 541 int register_lines(struct line_driver *line_driver,
 542                    const struct tty_operations *ops,
 543                    struct line *lines, int nlines)
 544 {
 545         struct tty_driver *driver = alloc_tty_driver(nlines);
 546         int err;
 547         int i;
 548
 549         if (!driver)
 550                 return -ENOMEM;
 551
 552         driver->driver_name = line_driver->name;
 553         driver->name = line_driver->device_name;
 554         driver->major = line_driver->major;
 555         driver->minor_start = line_driver->minor_start;
 556         driver->type = line_driver->type;
 557         driver->subtype = line_driver->subtype;
 558         driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 559         driver->init_termios = tty_std_termios;
 560
 561         for (i = 0; i < nlines; i++) {
 562                 tty_port_init(&lines[i].port);
 563                 lines[i].port.ops = &line_port_ops;
 564                 spin_lock_init(&lines[i].lock);
 565                 lines[i].driver = line_driver;
 566                 INIT_LIST_HEAD(&lines[i].chan_list);
 567         }
 568         tty_set_operations(driver, ops);
 569
 570         err = tty_register_driver(driver);
 571         if (err) {
 572                 printk(KERN_ERR "register_lines : can't register %s driver\n",
 573                        line_driver->name);
 574                 put_tty_driver(driver);
 575                 for (i = 0; i < nlines; i++)
 576                         tty_port_destroy(&lines[i].port);
 577                 return err;
 578         }
 579
 580         line_driver->driver = driver;
 581         mconsole_register_dev(&line_driver->mc);
 582         return 0;
 583 }
 584
 585 static DEFINE_SPINLOCK(winch_handler_lock);
 586 static LIST_HEAD(winch_handlers);
 587
 588 struct winch {
 589         struct list_head list;
 590         int fd;
 591         int tty_fd;
 592         int pid;
 593         struct tty_port *port;
 594         unsigned long stack;
 595         struct work_struct work;
 596 };
 597
 598 static void __free_winch(struct work_struct *work)
 599 {
 600         struct winch *winch = container_of(work, struct winch, work);
 601         um_free_irq(WINCH_IRQ, winch);
 602
 603         if (winch->pid != -1)
 604                 os_kill_process(winch->pid, 1);
 605         if (winch->stack != 0)
 606                 free_stack(winch->stack, 0);
 607         kfree(winch);
 608 }
 609
 610 static void free_winch(struct winch *winch)
 611 {
 612         int fd = winch->fd;
 613         winch->fd = -1;
 614         if (fd != -1)
 615                 os_close_file(fd);
 616         list_del(&winch->list);
 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                         free_winch(winch);
 718                         break;
 719                 }
 720                 tty_kref_put(wtty);
 721         }
 722         spin_unlock(&winch_handler_lock);
 723 }
 724
 725 static void winch_cleanup(void)
 726 {
 727         struct list_head *ele, *next;
 728         struct winch *winch;
 729
 730         spin_lock(&winch_handler_lock);
 731
 732         list_for_each_safe(ele, next, &winch_handlers) {
 733                 winch = list_entry(ele, struct winch, list);
 734                 free_winch(winch);
 735         }
 736
 737         spin_unlock(&winch_handler_lock);
 738 }
 739 __uml_exitcall(winch_cleanup);
 740
 741 char *add_xterm_umid(char *base)
 742 {
 743         char *umid, *title;
 744         int len;
 745
 746         umid = get_umid();
 747         if (*umid == '\0')
 748                 return base;
 749
 750         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
 751         title = kmalloc(len, GFP_KERNEL);
 752         if (title == NULL) {
 753                 printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
 754                 return base;
 755         }
 756
 757         snprintf(title, len, "%s (%s)", base, umid);
 758         return title;
 759 }