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 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
  50 unsigned 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
  63 unsigned 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  */
  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_throttle(struct tty_struct *tty)
 215 {
 216         struct line *line = tty->driver_data;
 217
 218         deactivate_chan(line->chan_in, line->driver->read_irq);
 219         line->throttled = 1;
 220 }
 221
 222 void line_unthrottle(struct tty_struct *tty)
 223 {
 224         struct line *line = tty->driver_data;
 225
 226         line->throttled = 0;
 227         chan_interrupt(line, line->driver->read_irq);
 228 }
 229
 230 static 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
 257 int 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(driver->read_irq, fd, IRQ_READ,
 264                                      line_interrupt, IRQF_SHARED,
 265                                      driver->read_irq_name, data);
 266                 if (err < 0)
 267                         return err;
 268         }
 269
 270         if (output) {
 271                 err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
 272                                      line_write_interrupt, IRQF_SHARED,
 273                                      driver->write_irq_name, data);
 274                 if (err < 0)
 275                         return err;
 276         }
 277
 278         return 0;
 279 }
 280
 281 static int line_activate(struct tty_port *port, struct tty_struct *tty)
 282 {
 283         int ret;
 284         struct line *line = tty->driver_data;
 285
 286         ret = enable_chan(line);
 287         if (ret)
 288                 return ret;
 289
 290         if (!line->sigio) {
 291                 chan_enable_winch(line->chan_out, port);
 292                 line->sigio = 1;
 293         }
 294
 295         chan_window_size(line, &tty->winsize.ws_row,
 296                 &tty->winsize.ws_col);
 297
 298         return 0;
 299 }
 300
 301 static void unregister_winch(struct tty_struct *tty);
 302
 303 static void line_destruct(struct tty_port *port)
 304 {
 305         struct tty_struct *tty = tty_port_tty_get(port);
 306         struct line *line = tty->driver_data;
 307
 308         if (line->sigio) {
 309                 unregister_winch(tty);
 310                 line->sigio = 0;
 311         }
 312 }
 313
 314 static const struct tty_port_operations line_port_ops = {
 315         .activate = line_activate,
 316         .destruct = line_destruct,
 317 };
 318
 319 int line_open(struct tty_struct *tty, struct file *filp)
 320 {
 321         struct line *line = tty->driver_data;
 322
 323         return tty_port_open(&line->port, tty, filp);
 324 }
 325
 326 int line_install(struct tty_driver *driver, struct tty_struct *tty,
 327                  struct line *line)
 328 {
 329         int ret;
 330
 331         ret = tty_standard_install(driver, tty);
 332         if (ret)
 333                 return ret;
 334
 335         tty->driver_data = line;
 336
 337         return 0;
 338 }
 339
 340 void line_close(struct tty_struct *tty, struct file * filp)
 341 {
 342         struct line *line = tty->driver_data;
 343
 344         tty_port_close(&line->port, tty, filp);
 345 }
 346
 347 void line_hangup(struct tty_struct *tty)
 348 {
 349         struct line *line = tty->driver_data;
 350
 351         tty_port_hangup(&line->port);
 352 }
 353
 354 void close_lines(struct line *lines, int nlines)
 355 {
 356         int i;
 357
 358         for(i = 0; i < nlines; i++)
 359                 close_chan(&lines[i]);
 360 }
 361
 362 int setup_one_line(struct line *lines, int n, char *init,
 363                    const struct chan_opts *opts, char **error_out)
 364 {
 365         struct line *line = &lines[n];
 366         struct tty_driver *driver = line->driver->driver;
 367         int err = -EINVAL;
 368
 369         if (line->port.count) {
 370                 *error_out = "Device is already open";
 371                 goto out;
 372         }
 373
 374         if (!strcmp(init, "none")) {
 375                 if (line->valid) {
 376                         line->valid = 0;
 377                         kfree(line->init_str);
 378                         tty_unregister_device(driver, n);
 379                         parse_chan_pair(NULL, line, n, opts, error_out);
 380                         err = 0;
 381                 }
 382         } else {
 383                 char *new = kstrdup(init, GFP_KERNEL);
 384                 if (!new) {
 385                         *error_out = "Failed to allocate memory";
 386                         return -ENOMEM;
 387                 }
 388                 if (line->valid) {
 389                         tty_unregister_device(driver, n);
 390                         kfree(line->init_str);
 391                 }
 392                 line->init_str = new;
 393                 line->valid = 1;
 394                 err = parse_chan_pair(new, line, n, opts, error_out);
 395                 if (!err) {
 396                         struct device *d = tty_port_register_device(&line->port,
 397                                         driver, n, NULL);
 398                         if (IS_ERR(d)) {
 399                                 *error_out = "Failed to register device";
 400                                 err = PTR_ERR(d);
 401                                 parse_chan_pair(NULL, line, n, opts, error_out);
 402                         }
 403                 }
 404                 if (err) {
 405                         line->init_str = NULL;
 406                         line->valid = 0;
 407                         kfree(new);
 408                 }
 409         }
 410 out:
 411         return err;
 412 }
 413
 414 /*
 415  * Common setup code for both startup command line and mconsole initialization.
 416  * @lines contains the array (of size @num) to modify;
 417  * @init is the setup string;
 418  * @error_out is an error string in the case of failure;
 419  */
 420
 421 int line_setup(char **conf, unsigned int num, char **def,
 422                char *init, char *name)
 423 {
 424         char *error;
 425
 426         if (*init == '=') {
 427                 /*
 428                  * We said con=/ssl= instead of con#=, so we are configuring all
 429                  * consoles at once.
 430                  */
 431                 *def = init + 1;
 432         } else {
 433                 char *end;
 434                 unsigned n = simple_strtoul(init, &end, 0);
 435
 436                 if (*end != '=') {
 437                         error = "Couldn't parse device number";
 438                         goto out;
 439                 }
 440                 if (n >= num) {
 441                         error = "Device number out of range";
 442                         goto out;
 443                 }
 444                 conf[n] = end + 1;
 445         }
 446         return 0;
 447
 448 out:
 449         printk(KERN_ERR "Failed to set up %s with "
 450                "configuration string \"%s\" : %s\n", name, init, error);
 451         return -EINVAL;
 452 }
 453
 454 int line_config(struct line *lines, unsigned int num, char *str,
 455                 const struct chan_opts *opts, char **error_out)
 456 {
 457         char *end;
 458         int n;
 459
 460         if (*str == '=') {
 461                 *error_out = "Can't configure all devices from mconsole";
 462                 return -EINVAL;
 463         }
 464
 465         n = simple_strtoul(str, &end, 0);
 466         if (*end++ != '=') {
 467                 *error_out = "Couldn't parse device number";
 468                 return -EINVAL;
 469         }
 470         if (n >= num) {
 471                 *error_out = "Device number out of range";
 472                 return -EINVAL;
 473         }
 474
 475         return setup_one_line(lines, n, end, opts, error_out);
 476 }
 477
 478 int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
 479                     int size, char **error_out)
 480 {
 481         struct line *line;
 482         char *end;
 483         int dev, n = 0;
 484
 485         dev = simple_strtoul(name, &end, 0);
 486         if ((*end != '\0') || (end == name)) {
 487                 *error_out = "line_get_config failed to parse device number";
 488                 return 0;
 489         }
 490
 491         if ((dev < 0) || (dev >= num)) {
 492                 *error_out = "device number out of range";
 493                 return 0;
 494         }
 495
 496         line = &lines[dev];
 497
 498         if (!line->valid)
 499                 CONFIG_CHUNK(str, size, n, "none", 1);
 500         else {
 501                 struct tty_struct *tty = tty_port_tty_get(&line->port);
 502                 if (tty == NULL) {
 503                         CONFIG_CHUNK(str, size, n, line->init_str, 1);
 504                 } else {
 505                         n = chan_config_string(line, str, size, error_out);
 506                         tty_kref_put(tty);
 507                 }
 508         }
 509
 510         return n;
 511 }
 512
 513 int line_id(char **str, int *start_out, int *end_out)
 514 {
 515         char *end;
 516         int n;
 517
 518         n = simple_strtoul(*str, &end, 0);
 519         if ((*end != '\0') || (end == *str))
 520                 return -1;
 521
 522         *str = end;
 523         *start_out = n;
 524         *end_out = n;
 525         return n;
 526 }
 527
 528 int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
 529 {
 530         if (n >= num) {
 531                 *error_out = "Device number out of range";
 532                 return -EINVAL;
 533         }
 534         return setup_one_line(lines, n, "none", NULL, error_out);
 535 }
 536
 537 int register_lines(struct line_driver *line_driver,
 538                    const struct tty_operations *ops,
 539                    struct line *lines, int nlines)
 540 {
 541         struct tty_driver *driver;
 542         int err;
 543         int i;
 544
 545         driver = tty_alloc_driver(nlines, TTY_DRIVER_REAL_RAW |
 546                         TTY_DRIVER_DYNAMIC_DEV);
 547         if (IS_ERR(driver))
 548                 return PTR_ERR(driver);
 549
 550         driver->driver_name = line_driver->name;
 551         driver->name = line_driver->device_name;
 552         driver->major = line_driver->major;
 553         driver->minor_start = line_driver->minor_start;
 554         driver->type = line_driver->type;
 555         driver->subtype = line_driver->subtype;
 556         driver->init_termios = tty_std_termios;
 557
 558         for (i = 0; i < nlines; i++) {
 559                 tty_port_init(&lines[i].port);
 560                 lines[i].port.ops = &line_port_ops;
 561                 spin_lock_init(&lines[i].lock);
 562                 lines[i].driver = line_driver;
 563                 INIT_LIST_HEAD(&lines[i].chan_list);
 564         }
 565         tty_set_operations(driver, ops);
 566
 567         err = tty_register_driver(driver);
 568         if (err) {
 569                 printk(KERN_ERR "register_lines : can't register %s driver\n",
 570                        line_driver->name);
 571                 tty_driver_kref_put(driver);
 572                 for (i = 0; i < nlines; i++)
 573                         tty_port_destroy(&lines[i].port);
 574                 return err;
 575         }
 576
 577         line_driver->driver = driver;
 578         mconsole_register_dev(&line_driver->mc);
 579         return 0;
 580 }
 581
 582 static DEFINE_SPINLOCK(winch_handler_lock);
 583 static LIST_HEAD(winch_handlers);
 584
 585 struct winch {
 586         struct list_head list;
 587         int fd;
 588         int tty_fd;
 589         int pid;
 590         struct tty_port *port;
 591         unsigned long stack;
 592         struct work_struct work;
 593 };
 594
 595 static void __free_winch(struct work_struct *work)
 596 {
 597         struct winch *winch = container_of(work, struct winch, work);
 598         um_free_irq(WINCH_IRQ, winch);
 599
 600         if (winch->pid != -1)
 601                 os_kill_process(winch->pid, 1);
 602         if (winch->stack != 0)
 603                 free_stack(winch->stack, 0);
 604         kfree(winch);
 605 }
 606
 607 static void free_winch(struct winch *winch)
 608 {
 609         int fd = winch->fd;
 610         winch->fd = -1;
 611         if (fd != -1)
 612                 os_close_file(fd);
 613         __free_winch(&winch->work);
 614 }
 615
 616 static irqreturn_t winch_interrupt(int irq, void *data)
 617 {
 618         struct winch *winch = data;
 619         struct tty_struct *tty;
 620         struct line *line;
 621         int fd = winch->fd;
 622         int err;
 623         char c;
 624         struct pid *pgrp;
 625
 626         if (fd != -1) {
 627                 err = generic_read(fd, &c, NULL);
 628                 if (err < 0) {
 629                         if (err != -EAGAIN) {
 630                                 winch->fd = -1;
 631                                 list_del(&winch->list);
 632                                 os_close_file(fd);
 633                                 printk(KERN_ERR "winch_interrupt : "
 634                                        "read failed, errno = %d\n", -err);
 635                                 printk(KERN_ERR "fd %d is losing SIGWINCH "
 636                                        "support\n", winch->tty_fd);
 637                                 INIT_WORK(&winch->work, __free_winch);
 638                                 schedule_work(&winch->work);
 639                                 return IRQ_HANDLED;
 640                         }
 641                         goto out;
 642                 }
 643         }
 644         tty = tty_port_tty_get(winch->port);
 645         if (tty != NULL) {
 646                 line = tty->driver_data;
 647                 if (line != NULL) {
 648                         chan_window_size(line, &tty->winsize.ws_row,
 649                                          &tty->winsize.ws_col);
 650                         pgrp = tty_get_pgrp(tty);
 651                         if (pgrp)
 652                                 kill_pgrp(pgrp, SIGWINCH, 1);
 653                         put_pid(pgrp);
 654                 }
 655                 tty_kref_put(tty);
 656         }
 657  out:
 658         return IRQ_HANDLED;
 659 }
 660
 661 void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
 662                         unsigned long stack)
 663 {
 664         struct winch *winch;
 665
 666         winch = kmalloc(sizeof(*winch), GFP_KERNEL);
 667         if (winch == NULL) {
 668                 printk(KERN_ERR "register_winch_irq - kmalloc failed\n");
 669                 goto cleanup;
 670         }
 671
 672         *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
 673                                    .fd          = fd,
 674                                    .tty_fd      = tty_fd,
 675                                    .pid         = pid,
 676                                    .port        = port,
 677                                    .stack       = stack });
 678
 679         if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
 680                            IRQF_SHARED, "winch", winch) < 0) {
 681                 printk(KERN_ERR "register_winch_irq - failed to register "
 682                        "IRQ\n");
 683                 goto out_free;
 684         }
 685
 686         spin_lock(&winch_handler_lock);
 687         list_add(&winch->list, &winch_handlers);
 688         spin_unlock(&winch_handler_lock);
 689
 690         return;
 691
 692  out_free:
 693         kfree(winch);
 694  cleanup:
 695         os_kill_process(pid, 1);
 696         os_close_file(fd);
 697         if (stack != 0)
 698                 free_stack(stack, 0);
 699 }
 700
 701 static void unregister_winch(struct tty_struct *tty)
 702 {
 703         struct list_head *ele, *next;
 704         struct winch *winch;
 705         struct tty_struct *wtty;
 706
 707         spin_lock(&winch_handler_lock);
 708
 709         list_for_each_safe(ele, next, &winch_handlers) {
 710                 winch = list_entry(ele, struct winch, list);
 711                 wtty = tty_port_tty_get(winch->port);
 712                 if (wtty == tty) {
 713                         list_del(&winch->list);
 714                         spin_unlock(&winch_handler_lock);
 715                         free_winch(winch);
 716                         break;
 717                 }
 718                 tty_kref_put(wtty);
 719         }
 720         spin_unlock(&winch_handler_lock);
 721 }
 722
 723 static void winch_cleanup(void)
 724 {
 725         struct winch *winch;
 726
 727         spin_lock(&winch_handler_lock);
 728         while ((winch = list_first_entry_or_null(&winch_handlers,
 729                                                  struct winch, list))) {
 730                 list_del(&winch->list);
 731                 spin_unlock(&winch_handler_lock);
 732
 733                 free_winch(winch);
 734
 735                 spin_lock(&winch_handler_lock);
 736         }
 737
 738         spin_unlock(&winch_handler_lock);
 739 }
 740 __uml_exitcall(winch_cleanup);
 741
 742 char *add_xterm_umid(char *base)
 743 {
 744         char *umid, *title;
 745         int len;
 746
 747         umid = get_umid();
 748         if (*umid == '\0')
 749                 return base;
 750
 751         len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
 752         title = kmalloc(len, GFP_KERNEL);
 753         if (title == NULL) {
 754                 printk(KERN_ERR "Failed to allocate buffer for xterm title\n");
 755                 return base;
 756         }
 757
 758         snprintf(title, len, "%s (%s)", base, umid);
 759         return title;
 760 }