drivers/tty/vt/vt_ioctl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (C) 1992 obz under the linux copyright
   4  *
   5  *  Dynamic diacritical handling - aeb@cwi.nl - Dec 1993
   6  *  Dynamic keymap and string allocation - aeb@cwi.nl - May 1994
   7  *  Restrict VT switching via ioctl() - grif@cs.ucr.edu - Dec 1995
   8  *  Some code moved for less code duplication - Andi Kleen - Mar 1997
   9  *  Check put/get_user, cleanups - acme@conectiva.com.br - Jun 2001
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/sched/signal.h>
  15 #include <linux/tty.h>
  16 #include <linux/timer.h>
  17 #include <linux/kernel.h>
  18 #include <linux/compat.h>
  19 #include <linux/module.h>
  20 #include <linux/kd.h>
  21 #include <linux/vt.h>
  22 #include <linux/string.h>
  23 #include <linux/slab.h>
  24 #include <linux/major.h>
  25 #include <linux/fs.h>
  26 #include <linux/console.h>
  27 #include <linux/consolemap.h>
  28 #include <linux/signal.h>
  29 #include <linux/suspend.h>
  30 #include <linux/timex.h>
  31
  32 #include <asm/io.h>
  33 #include <linux/uaccess.h>
  34
  35 #include <linux/nospec.h>
  36
  37 #include <linux/kbd_kern.h>
  38 #include <linux/vt_kern.h>
  39 #include <linux/kbd_diacr.h>
  40 #include <linux/selection.h>
  41
  42 bool vt_dont_switch;
  43
  44 static inline bool vt_in_use(unsigned int i)
  45 {
  46         const struct vc_data *vc = vc_cons[i].d;
  47
  48         /*
  49          * console_lock must be held to prevent the vc from being deallocated
  50          * while we're checking whether it's in-use.
  51          */
  52         WARN_CONSOLE_UNLOCKED();
  53
  54         return vc && kref_read(&vc->port.kref) > 1;
  55 }
  56
  57 static inline bool vt_busy(int i)
  58 {
  59         if (vt_in_use(i))
  60                 return true;
  61         if (i == fg_console)
  62                 return true;
  63         if (vc_is_sel(vc_cons[i].d))
  64                 return true;
  65
  66         return false;
  67 }
  68
  69 /*
  70  * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
  71  * experimentation and study of X386 SYSV handling.
  72  *
  73  * One point of difference: SYSV vt's are /dev/vtX, which X >= 0, and
  74  * /dev/console is a separate ttyp. Under Linux, /dev/tty0 is /dev/console,
  75  * and the vc start at /dev/ttyX, X >= 1. We maintain that here, so we will
  76  * always treat our set of vt as numbered 1..MAX_NR_CONSOLES (corresponding to
  77  * ttys 0..MAX_NR_CONSOLES-1). Explicitly naming VT 0 is illegal, but using
  78  * /dev/tty0 (fg_console) as a target is legal, since an implicit aliasing
  79  * to the current console is done by the main ioctl code.
  80  */
  81
  82 #ifdef CONFIG_X86
  83 #include <asm/syscalls.h>
  84 #endif
  85
  86 static void complete_change_console(struct vc_data *vc);
  87
  88 /*
  89  *      User space VT_EVENT handlers
  90  */
  91
  92 struct vt_event_wait {
  93         struct list_head list;
  94         struct vt_event event;
  95         int done;
  96 };
  97
  98 static LIST_HEAD(vt_events);
  99 static DEFINE_SPINLOCK(vt_event_lock);
 100 static DECLARE_WAIT_QUEUE_HEAD(vt_event_waitqueue);
 101
 102 /**
 103  *      vt_event_post
 104  *      @event: the event that occurred
 105  *      @old: old console
 106  *      @new: new console
 107  *
 108  *      Post an VT event to interested VT handlers
 109  */
 110
 111 void vt_event_post(unsigned int event, unsigned int old, unsigned int new)
 112 {
 113         struct list_head *pos, *head;
 114         unsigned long flags;
 115         int wake = 0;
 116
 117         spin_lock_irqsave(&vt_event_lock, flags);
 118         head = &vt_events;
 119
 120         list_for_each(pos, head) {
 121                 struct vt_event_wait *ve = list_entry(pos,
 122                                                 struct vt_event_wait, list);
 123                 if (!(ve->event.event & event))
 124                         continue;
 125                 ve->event.event = event;
 126                 /* kernel view is consoles 0..n-1, user space view is
 127                    console 1..n with 0 meaning current, so we must bias */
 128                 ve->event.oldev = old + 1;
 129                 ve->event.newev = new + 1;
 130                 wake = 1;
 131                 ve->done = 1;
 132         }
 133         spin_unlock_irqrestore(&vt_event_lock, flags);
 134         if (wake)
 135                 wake_up_interruptible(&vt_event_waitqueue);
 136 }
 137
 138 static void __vt_event_queue(struct vt_event_wait *vw)
 139 {
 140         unsigned long flags;
 141         /* Prepare the event */
 142         INIT_LIST_HEAD(&vw->list);
 143         vw->done = 0;
 144         /* Queue our event */
 145         spin_lock_irqsave(&vt_event_lock, flags);
 146         list_add(&vw->list, &vt_events);
 147         spin_unlock_irqrestore(&vt_event_lock, flags);
 148 }
 149
 150 static void __vt_event_wait(struct vt_event_wait *vw)
 151 {
 152         /* Wait for it to pass */
 153         wait_event_interruptible(vt_event_waitqueue, vw->done);
 154 }
 155
 156 static void __vt_event_dequeue(struct vt_event_wait *vw)
 157 {
 158         unsigned long flags;
 159
 160         /* Dequeue it */
 161         spin_lock_irqsave(&vt_event_lock, flags);
 162         list_del(&vw->list);
 163         spin_unlock_irqrestore(&vt_event_lock, flags);
 164 }
 165
 166 /**
 167  *      vt_event_wait           -       wait for an event
 168  *      @vw: our event
 169  *
 170  *      Waits for an event to occur which completes our vt_event_wait
 171  *      structure. On return the structure has wv->done set to 1 for success
 172  *      or 0 if some event such as a signal ended the wait.
 173  */
 174
 175 static void vt_event_wait(struct vt_event_wait *vw)
 176 {
 177         __vt_event_queue(vw);
 178         __vt_event_wait(vw);
 179         __vt_event_dequeue(vw);
 180 }
 181
 182 /**
 183  *      vt_event_wait_ioctl     -       event ioctl handler
 184  *      @arg: argument to ioctl
 185  *
 186  *      Implement the VT_WAITEVENT ioctl using the VT event interface
 187  */
 188
 189 static int vt_event_wait_ioctl(struct vt_event __user *event)
 190 {
 191         struct vt_event_wait vw;
 192
 193         if (copy_from_user(&vw.event, event, sizeof(struct vt_event)))
 194                 return -EFAULT;
 195         /* Highest supported event for now */
 196         if (vw.event.event & ~VT_MAX_EVENT)
 197                 return -EINVAL;
 198
 199         vt_event_wait(&vw);
 200         /* If it occurred report it */
 201         if (vw.done) {
 202                 if (copy_to_user(event, &vw.event, sizeof(struct vt_event)))
 203                         return -EFAULT;
 204                 return 0;
 205         }
 206         return -EINTR;
 207 }
 208
 209 /**
 210  *      vt_waitactive   -       active console wait
 211  *      @event: event code
 212  *      @n: new console
 213  *
 214  *      Helper for event waits. Used to implement the legacy
 215  *      event waiting ioctls in terms of events
 216  */
 217
 218 int vt_waitactive(int n)
 219 {
 220         struct vt_event_wait vw;
 221         do {
 222                 vw.event.event = VT_EVENT_SWITCH;
 223                 __vt_event_queue(&vw);
 224                 if (n == fg_console + 1) {
 225                         __vt_event_dequeue(&vw);
 226                         break;
 227                 }
 228                 __vt_event_wait(&vw);
 229                 __vt_event_dequeue(&vw);
 230                 if (vw.done == 0)
 231                         return -EINTR;
 232         } while (vw.event.newev != n);
 233         return 0;
 234 }
 235
 236 /*
 237  * these are the valid i/o ports we're allowed to change. they map all the
 238  * video ports
 239  */
 240 #define GPFIRST 0x3b4
 241 #define GPLAST 0x3df
 242 #define GPNUM (GPLAST - GPFIRST + 1)
 243
 244
 245
 246 static inline int
 247 do_fontx_ioctl(int cmd, struct consolefontdesc __user *user_cfd, int perm, struct console_font_op *op)
 248 {
 249         struct consolefontdesc cfdarg;
 250         int i;
 251
 252         if (copy_from_user(&cfdarg, user_cfd, sizeof(struct consolefontdesc)))
 253                 return -EFAULT;
 254
 255         switch (cmd) {
 256         case PIO_FONTX:
 257                 if (!perm)
 258                         return -EPERM;
 259                 op->op = KD_FONT_OP_SET;
 260                 op->flags = KD_FONT_FLAG_OLD;
 261                 op->width = 8;
 262                 op->height = cfdarg.charheight;
 263                 op->charcount = cfdarg.charcount;
 264                 op->data = cfdarg.chardata;
 265                 return con_font_op(vc_cons[fg_console].d, op);
 266         case GIO_FONTX: {
 267                 op->op = KD_FONT_OP_GET;
 268                 op->flags = KD_FONT_FLAG_OLD;
 269                 op->width = 8;
 270                 op->height = cfdarg.charheight;
 271                 op->charcount = cfdarg.charcount;
 272                 op->data = cfdarg.chardata;
 273                 i = con_font_op(vc_cons[fg_console].d, op);
 274                 if (i)
 275                         return i;
 276                 cfdarg.charheight = op->height;
 277                 cfdarg.charcount = op->charcount;
 278                 if (copy_to_user(user_cfd, &cfdarg, sizeof(struct consolefontdesc)))
 279                         return -EFAULT;
 280                 return 0;
 281                 }
 282         }
 283         return -EINVAL;
 284 }
 285
 286 static inline int
 287 do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud, int perm, struct vc_data *vc)
 288 {
 289         struct unimapdesc tmp;
 290
 291         if (copy_from_user(&tmp, user_ud, sizeof tmp))
 292                 return -EFAULT;
 293         switch (cmd) {
 294         case PIO_UNIMAP:
 295                 if (!perm)
 296                         return -EPERM;
 297                 return con_set_unimap(vc, tmp.entry_ct, tmp.entries);
 298         case GIO_UNIMAP:
 299                 if (!perm && fg_console != vc->vc_num)
 300                         return -EPERM;
 301                 return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp.entries);
 302         }
 303         return 0;
 304 }
 305
 306 /* deallocate a single console, if possible (leave 0) */
 307 static int vt_disallocate(unsigned int vc_num)
 308 {
 309         struct vc_data *vc = NULL;
 310         int ret = 0;
 311
 312         console_lock();
 313         if (vt_busy(vc_num))
 314                 ret = -EBUSY;
 315         else if (vc_num)
 316                 vc = vc_deallocate(vc_num);
 317         console_unlock();
 318
 319         if (vc && vc_num >= MIN_NR_CONSOLES)
 320                 tty_port_put(&vc->port);
 321
 322         return ret;
 323 }
 324
 325 /* deallocate all unused consoles, but leave 0 */
 326 static void vt_disallocate_all(void)
 327 {
 328         struct vc_data *vc[MAX_NR_CONSOLES];
 329         int i;
 330
 331         console_lock();
 332         for (i = 1; i < MAX_NR_CONSOLES; i++)
 333                 if (!vt_busy(i))
 334                         vc[i] = vc_deallocate(i);
 335                 else
 336                         vc[i] = NULL;
 337         console_unlock();
 338
 339         for (i = 1; i < MAX_NR_CONSOLES; i++) {
 340                 if (vc[i] && i >= MIN_NR_CONSOLES)
 341                         tty_port_put(&vc[i]->port);
 342         }
 343 }
 344
 345
 346 /*
 347  * We handle the console-specific ioctl's here.  We allow the
 348  * capability to modify any console, not just the fg_console.
 349  */
 350 int vt_ioctl(struct tty_struct *tty,
 351              unsigned int cmd, unsigned long arg)
 352 {
 353         struct vc_data *vc = tty->driver_data;
 354         struct console_font_op op;      /* used in multiple places here */
 355         unsigned int console = vc->vc_num;
 356         unsigned char ucval;
 357         unsigned int uival;
 358         void __user *up = (void __user *)arg;
 359         int i, perm;
 360         int ret = 0;
 361
 362         /*
 363          * To have permissions to do most of the vt ioctls, we either have
 364          * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
 365          */
 366         perm = 0;
 367         if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
 368                 perm = 1;
 369
 370         switch (cmd) {
 371         case TIOCLINUX:
 372                 ret = tioclinux(tty, arg);
 373                 break;
 374         case KIOCSOUND:
 375                 if (!perm)
 376                         return -EPERM;
 377                 /*
 378                  * The use of PIT_TICK_RATE is historic, it used to be
 379                  * the platform-dependent CLOCK_TICK_RATE between 2.6.12
 380                  * and 2.6.36, which was a minor but unfortunate ABI
 381                  * change. kd_mksound is locked by the input layer.
 382                  */
 383                 if (arg)
 384                         arg = PIT_TICK_RATE / arg;
 385                 kd_mksound(arg, 0);
 386                 break;
 387
 388         case KDMKTONE:
 389                 if (!perm)
 390                         return -EPERM;
 391         {
 392                 unsigned int ticks, count;
 393
 394                 /*
 395                  * Generate the tone for the appropriate number of ticks.
 396                  * If the time is zero, turn off sound ourselves.
 397                  */
 398                 ticks = msecs_to_jiffies((arg >> 16) & 0xffff);
 399                 count = ticks ? (arg & 0xffff) : 0;
 400                 if (count)
 401                         count = PIT_TICK_RATE / count;
 402                 kd_mksound(count, ticks);
 403                 break;
 404         }
 405
 406         case KDGKBTYPE:
 407                 /*
 408                  * this is naïve.
 409                  */
 410                 ucval = KB_101;
 411                 ret = put_user(ucval, (char __user *)arg);
 412                 break;
 413
 414                 /*
 415                  * These cannot be implemented on any machine that implements
 416                  * ioperm() in user level (such as Alpha PCs) or not at all.
 417                  *
 418                  * XXX: you should never use these, just call ioperm directly..
 419                  */
 420 #ifdef CONFIG_X86
 421         case KDADDIO:
 422         case KDDELIO:
 423                 /*
 424                  * KDADDIO and KDDELIO may be able to add ports beyond what
 425                  * we reject here, but to be safe...
 426                  *
 427                  * These are locked internally via sys_ioperm
 428                  */
 429                 if (arg < GPFIRST || arg > GPLAST) {
 430                         ret = -EINVAL;
 431                         break;
 432                 }
 433                 ret = ksys_ioperm(arg, 1, (cmd == KDADDIO)) ? -ENXIO : 0;
 434                 break;
 435
 436         case KDENABIO:
 437         case KDDISABIO:
 438                 ret = ksys_ioperm(GPFIRST, GPNUM,
 439                                   (cmd == KDENABIO)) ? -ENXIO : 0;
 440                 break;
 441 #endif
 442
 443         /* Linux m68k/i386 interface for setting the keyboard delay/repeat rate */
 444
 445         case KDKBDREP:
 446         {
 447                 struct kbd_repeat kbrep;
 448
 449                 if (!capable(CAP_SYS_TTY_CONFIG))
 450                         return -EPERM;
 451
 452                 if (copy_from_user(&kbrep, up, sizeof(struct kbd_repeat))) {
 453                         ret =  -EFAULT;
 454                         break;
 455                 }
 456                 ret = kbd_rate(&kbrep);
 457                 if (ret)
 458                         break;
 459                 if (copy_to_user(up, &kbrep, sizeof(struct kbd_repeat)))
 460                         ret = -EFAULT;
 461                 break;
 462         }
 463
 464         case KDSETMODE:
 465                 /*
 466                  * currently, setting the mode from KD_TEXT to KD_GRAPHICS
 467                  * doesn't do a whole lot. i'm not sure if it should do any
 468                  * restoration of modes or what...
 469                  *
 470                  * XXX It should at least call into the driver, fbdev's definitely
 471                  * need to restore their engine state. --BenH
 472                  */
 473                 if (!perm)
 474                         return -EPERM;
 475                 switch (arg) {
 476                 case KD_GRAPHICS:
 477                         break;
 478                 case KD_TEXT0:
 479                 case KD_TEXT1:
 480                         arg = KD_TEXT;
 481                 case KD_TEXT:
 482                         break;
 483                 default:
 484                         ret = -EINVAL;
 485                         goto out;
 486                 }
 487                 /* FIXME: this needs the console lock extending */
 488                 if (vc->vc_mode == (unsigned char) arg)
 489                         break;
 490                 vc->vc_mode = (unsigned char) arg;
 491                 if (console != fg_console)
 492                         break;
 493                 /*
 494                  * explicitly blank/unblank the screen if switching modes
 495                  */
 496                 console_lock();
 497                 if (arg == KD_TEXT)
 498                         do_unblank_screen(1);
 499                 else
 500                         do_blank_screen(1);
 501                 console_unlock();
 502                 break;
 503
 504         case KDGETMODE:
 505                 uival = vc->vc_mode;
 506                 goto setint;
 507
 508         case KDMAPDISP:
 509         case KDUNMAPDISP:
 510                 /*
 511                  * these work like a combination of mmap and KDENABIO.
 512                  * this could be easily finished.
 513                  */
 514                 ret = -EINVAL;
 515                 break;
 516
 517         case KDSKBMODE:
 518                 if (!perm)
 519                         return -EPERM;
 520                 ret = vt_do_kdskbmode(console, arg);
 521                 if (ret == 0)
 522                         tty_ldisc_flush(tty);
 523                 break;
 524
 525         case KDGKBMODE:
 526                 uival = vt_do_kdgkbmode(console);
 527                 ret = put_user(uival, (int __user *)arg);
 528                 break;
 529
 530         /* this could be folded into KDSKBMODE, but for compatibility
 531            reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
 532         case KDSKBMETA:
 533                 ret = vt_do_kdskbmeta(console, arg);
 534                 break;
 535
 536         case KDGKBMETA:
 537                 /* FIXME: should review whether this is worth locking */
 538                 uival = vt_do_kdgkbmeta(console);
 539         setint:
 540                 ret = put_user(uival, (int __user *)arg);
 541                 break;
 542
 543         case KDGETKEYCODE:
 544         case KDSETKEYCODE:
 545                 if(!capable(CAP_SYS_TTY_CONFIG))
 546                         perm = 0;
 547                 ret = vt_do_kbkeycode_ioctl(cmd, up, perm);
 548                 break;
 549
 550         case KDGKBENT:
 551         case KDSKBENT:
 552                 ret = vt_do_kdsk_ioctl(cmd, up, perm, console);
 553                 break;
 554
 555         case KDGKBSENT:
 556         case KDSKBSENT:
 557                 ret = vt_do_kdgkb_ioctl(cmd, up, perm);
 558                 break;
 559
 560         /* Diacritical processing. Handled in keyboard.c as it has
 561            to operate on the keyboard locks and structures */
 562         case KDGKBDIACR:
 563         case KDGKBDIACRUC:
 564         case KDSKBDIACR:
 565         case KDSKBDIACRUC:
 566                 ret = vt_do_diacrit(cmd, up, perm);
 567                 break;
 568
 569         /* the ioctls below read/set the flags usually shown in the leds */
 570         /* don't use them - they will go away without warning */
 571         case KDGKBLED:
 572         case KDSKBLED:
 573         case KDGETLED:
 574         case KDSETLED:
 575                 ret = vt_do_kdskled(console, cmd, arg, perm);
 576                 break;
 577
 578         /*
 579          * A process can indicate its willingness to accept signals
 580          * generated by pressing an appropriate key combination.
 581          * Thus, one can have a daemon that e.g. spawns a new console
 582          * upon a keypress and then changes to it.
 583          * See also the kbrequest field of inittab(5).
 584          */
 585         case KDSIGACCEPT:
 586         {
 587                 if (!perm || !capable(CAP_KILL))
 588                         return -EPERM;
 589                 if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
 590                         ret = -EINVAL;
 591                 else {
 592                         spin_lock_irq(&vt_spawn_con.lock);
 593                         put_pid(vt_spawn_con.pid);
 594                         vt_spawn_con.pid = get_pid(task_pid(current));
 595                         vt_spawn_con.sig = arg;
 596                         spin_unlock_irq(&vt_spawn_con.lock);
 597                 }
 598                 break;
 599         }
 600
 601         case VT_SETMODE:
 602         {
 603                 struct vt_mode tmp;
 604
 605                 if (!perm)
 606                         return -EPERM;
 607                 if (copy_from_user(&tmp, up, sizeof(struct vt_mode))) {
 608                         ret = -EFAULT;
 609                         goto out;
 610                 }
 611                 if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS) {
 612                         ret = -EINVAL;
 613                         goto out;
 614                 }
 615                 console_lock();
 616                 vc->vt_mode = tmp;
 617                 /* the frsig is ignored, so we set it to 0 */
 618                 vc->vt_mode.frsig = 0;
 619                 put_pid(vc->vt_pid);
 620                 vc->vt_pid = get_pid(task_pid(current));
 621                 /* no switch is required -- saw@shade.msu.ru */
 622                 vc->vt_newvt = -1;
 623                 console_unlock();
 624                 break;
 625         }
 626
 627         case VT_GETMODE:
 628         {
 629                 struct vt_mode tmp;
 630                 int rc;
 631
 632                 console_lock();
 633                 memcpy(&tmp, &vc->vt_mode, sizeof(struct vt_mode));
 634                 console_unlock();
 635
 636                 rc = copy_to_user(up, &tmp, sizeof(struct vt_mode));
 637                 if (rc)
 638                         ret = -EFAULT;
 639                 break;
 640         }
 641
 642         /*
 643          * Returns global vt state. Note that VT 0 is always open, since
 644          * it's an alias for the current VT, and people can't use it here.
 645          * We cannot return state for more than 16 VTs, since v_state is short.
 646          */
 647         case VT_GETSTATE:
 648         {
 649                 struct vt_stat __user *vtstat = up;
 650                 unsigned short state, mask;
 651
 652                 if (put_user(fg_console + 1, &vtstat->v_active))
 653                         ret = -EFAULT;
 654                 else {
 655                         state = 1;      /* /dev/tty0 is always open */
 656                         console_lock(); /* required by vt_in_use() */
 657                         for (i = 0, mask = 2; i < MAX_NR_CONSOLES && mask;
 658                                                         ++i, mask <<= 1)
 659                                 if (vt_in_use(i))
 660                                         state |= mask;
 661                         console_unlock();
 662                         ret = put_user(state, &vtstat->v_state);
 663                 }
 664                 break;
 665         }
 666
 667         /*
 668          * Returns the first available (non-opened) console.
 669          */
 670         case VT_OPENQRY:
 671                 console_lock(); /* required by vt_in_use() */
 672                 for (i = 0; i < MAX_NR_CONSOLES; ++i)
 673                         if (!vt_in_use(i))
 674                                 break;
 675                 console_unlock();
 676                 uival = i < MAX_NR_CONSOLES ? (i+1) : -1;
 677                 goto setint;
 678
 679         /*
 680          * ioctl(fd, VT_ACTIVATE, num) will cause us to switch to vt # num,
 681          * with num >= 1 (switches to vt 0, our console, are not allowed, just
 682          * to preserve sanity).
 683          */
 684         case VT_ACTIVATE:
 685                 if (!perm)
 686                         return -EPERM;
 687                 if (arg == 0 || arg > MAX_NR_CONSOLES)
 688                         ret =  -ENXIO;
 689                 else {
 690                         arg--;
 691                         console_lock();
 692                         ret = vc_allocate(arg);
 693                         console_unlock();
 694                         if (ret)
 695                                 break;
 696                         set_console(arg);
 697                 }
 698                 break;
 699
 700         case VT_SETACTIVATE:
 701         {
 702                 struct vt_setactivate vsa;
 703
 704                 if (!perm)
 705                         return -EPERM;
 706
 707                 if (copy_from_user(&vsa, (struct vt_setactivate __user *)arg,
 708                                         sizeof(struct vt_setactivate))) {
 709                         ret = -EFAULT;
 710                         goto out;
 711                 }
 712                 if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)
 713                         ret = -ENXIO;
 714                 else {
 715                         vsa.console = array_index_nospec(vsa.console,
 716                                                          MAX_NR_CONSOLES + 1);
 717                         vsa.console--;
 718                         console_lock();
 719                         ret = vc_allocate(vsa.console);
 720                         if (ret == 0) {
 721                                 struct vc_data *nvc;
 722                                 /* This is safe providing we don't drop the
 723                                    console sem between vc_allocate and
 724                                    finishing referencing nvc */
 725                                 nvc = vc_cons[vsa.console].d;
 726                                 nvc->vt_mode = vsa.mode;
 727                                 nvc->vt_mode.frsig = 0;
 728                                 put_pid(nvc->vt_pid);
 729                                 nvc->vt_pid = get_pid(task_pid(current));
 730                         }
 731                         console_unlock();
 732                         if (ret)
 733                                 break;
 734                         /* Commence switch and lock */
 735                         /* Review set_console locks */
 736                         set_console(vsa.console);
 737                 }
 738                 break;
 739         }
 740
 741         /*
 742          * wait until the specified VT has been activated
 743          */
 744         case VT_WAITACTIVE:
 745                 if (!perm)
 746                         return -EPERM;
 747                 if (arg == 0 || arg > MAX_NR_CONSOLES)
 748                         ret = -ENXIO;
 749                 else
 750                         ret = vt_waitactive(arg);
 751                 break;
 752
 753         /*
 754          * If a vt is under process control, the kernel will not switch to it
 755          * immediately, but postpone the operation until the process calls this
 756          * ioctl, allowing the switch to complete.
 757          *
 758          * According to the X sources this is the behavior:
 759          *      0:      pending switch-from not OK
 760          *      1:      pending switch-from OK
 761          *      2:      completed switch-to OK
 762          */
 763         case VT_RELDISP:
 764                 if (!perm)
 765                         return -EPERM;
 766
 767                 console_lock();
 768                 if (vc->vt_mode.mode != VT_PROCESS) {
 769                         console_unlock();
 770                         ret = -EINVAL;
 771                         break;
 772                 }
 773                 /*
 774                  * Switching-from response
 775                  */
 776                 if (vc->vt_newvt >= 0) {
 777                         if (arg == 0)
 778                                 /*
 779                                  * Switch disallowed, so forget we were trying
 780                                  * to do it.
 781                                  */
 782                                 vc->vt_newvt = -1;
 783
 784                         else {
 785                                 /*
 786                                  * The current vt has been released, so
 787                                  * complete the switch.
 788                                  */
 789                                 int newvt;
 790                                 newvt = vc->vt_newvt;
 791                                 vc->vt_newvt = -1;
 792                                 ret = vc_allocate(newvt);
 793                                 if (ret) {
 794                                         console_unlock();
 795                                         break;
 796                                 }
 797                                 /*
 798                                  * When we actually do the console switch,
 799                                  * make sure we are atomic with respect to
 800                                  * other console switches..
 801                                  */
 802                                 complete_change_console(vc_cons[newvt].d);
 803                         }
 804                 } else {
 805                         /*
 806                          * Switched-to response
 807                          */
 808                         /*
 809                          * If it's just an ACK, ignore it
 810                          */
 811                         if (arg != VT_ACKACQ)
 812                                 ret = -EINVAL;
 813                 }
 814                 console_unlock();
 815                 break;
 816
 817          /*
 818           * Disallocate memory associated to VT (but leave VT1)
 819           */
 820          case VT_DISALLOCATE:
 821                 if (arg > MAX_NR_CONSOLES) {
 822                         ret = -ENXIO;
 823                         break;
 824                 }
 825                 if (arg == 0)
 826                         vt_disallocate_all();
 827                 else
 828                         ret = vt_disallocate(--arg);
 829                 break;
 830
 831         case VT_RESIZE:
 832         {
 833                 struct vt_sizes __user *vtsizes = up;
 834                 struct vc_data *vc;
 835
 836                 ushort ll,cc;
 837                 if (!perm)
 838                         return -EPERM;
 839                 if (get_user(ll, &vtsizes->v_rows) ||
 840                     get_user(cc, &vtsizes->v_cols))
 841                         ret = -EFAULT;
 842                 else {
 843                         console_lock();
 844                         for (i = 0; i < MAX_NR_CONSOLES; i++) {
 845                                 vc = vc_cons[i].d;
 846
 847                                 if (vc) {
 848                                         vc->vc_resize_user = 1;
 849                                         /* FIXME: review v tty lock */
 850                                         vc_resize(vc_cons[i].d, cc, ll);
 851                                 }
 852                         }
 853                         console_unlock();
 854                 }
 855                 break;
 856         }
 857
 858         case VT_RESIZEX:
 859         {
 860                 struct vt_consize v;
 861                 if (!perm)
 862                         return -EPERM;
 863                 if (copy_from_user(&v, up, sizeof(struct vt_consize)))
 864                         return -EFAULT;
 865                 /* FIXME: Should check the copies properly */
 866                 if (!v.v_vlin)
 867                         v.v_vlin = vc->vc_scan_lines;
 868                 if (v.v_clin) {
 869                         int rows = v.v_vlin/v.v_clin;
 870                         if (v.v_rows != rows) {
 871                                 if (v.v_rows) /* Parameters don't add up */
 872                                         return -EINVAL;
 873                                 v.v_rows = rows;
 874                         }
 875                 }
 876                 if (v.v_vcol && v.v_ccol) {
 877                         int cols = v.v_vcol/v.v_ccol;
 878                         if (v.v_cols != cols) {
 879                                 if (v.v_cols)
 880                                         return -EINVAL;
 881                                 v.v_cols = cols;
 882                         }
 883                 }
 884
 885                 if (v.v_clin > 32)
 886                         return -EINVAL;
 887
 888                 for (i = 0; i < MAX_NR_CONSOLES; i++) {
 889                         struct vc_data *vcp;
 890
 891                         if (!vc_cons[i].d)
 892                                 continue;
 893                         console_lock();
 894                         vcp = vc_cons[i].d;
 895                         if (vcp) {
 896                                 if (v.v_vlin)
 897                                         vcp->vc_scan_lines = v.v_vlin;
 898                                 if (v.v_clin)
 899                                         vcp->vc_font.height = v.v_clin;
 900                                 vcp->vc_resize_user = 1;
 901                                 vc_resize(vcp, v.v_cols, v.v_rows);
 902                         }
 903                         console_unlock();
 904                 }
 905                 break;
 906         }
 907
 908         case PIO_FONT: {
 909                 if (!perm)
 910                         return -EPERM;
 911                 op.op = KD_FONT_OP_SET;
 912                 op.flags = KD_FONT_FLAG_OLD | KD_FONT_FLAG_DONT_RECALC; /* Compatibility */
 913                 op.width = 8;
 914                 op.height = 0;
 915                 op.charcount = 256;
 916                 op.data = up;
 917                 ret = con_font_op(vc_cons[fg_console].d, &op);
 918                 break;
 919         }
 920
 921         case GIO_FONT: {
 922                 op.op = KD_FONT_OP_GET;
 923                 op.flags = KD_FONT_FLAG_OLD;
 924                 op.width = 8;
 925                 op.height = 32;
 926                 op.charcount = 256;
 927                 op.data = up;
 928                 ret = con_font_op(vc_cons[fg_console].d, &op);
 929                 break;
 930         }
 931
 932         case PIO_CMAP:
 933                 if (!perm)
 934                         ret = -EPERM;
 935                 else
 936                         ret = con_set_cmap(up);
 937                 break;
 938
 939         case GIO_CMAP:
 940                 ret = con_get_cmap(up);
 941                 break;
 942
 943         case PIO_FONTX:
 944         case GIO_FONTX:
 945                 ret = do_fontx_ioctl(cmd, up, perm, &op);
 946                 break;
 947
 948         case PIO_FONTRESET:
 949         {
 950                 if (!perm)
 951                         return -EPERM;
 952
 953 #ifdef BROKEN_GRAPHICS_PROGRAMS
 954                 /* With BROKEN_GRAPHICS_PROGRAMS defined, the default
 955                    font is not saved. */
 956                 ret = -ENOSYS;
 957                 break;
 958 #else
 959                 {
 960                 op.op = KD_FONT_OP_SET_DEFAULT;
 961                 op.data = NULL;
 962                 ret = con_font_op(vc_cons[fg_console].d, &op);
 963                 if (ret)
 964                         break;
 965                 console_lock();
 966                 con_set_default_unimap(vc_cons[fg_console].d);
 967                 console_unlock();
 968                 break;
 969                 }
 970 #endif
 971         }
 972
 973         case KDFONTOP: {
 974                 if (copy_from_user(&op, up, sizeof(op))) {
 975                         ret = -EFAULT;
 976                         break;
 977                 }
 978                 if (!perm && op.op != KD_FONT_OP_GET)
 979                         return -EPERM;
 980                 ret = con_font_op(vc, &op);
 981                 if (ret)
 982                         break;
 983                 if (copy_to_user(up, &op, sizeof(op)))
 984                         ret = -EFAULT;
 985                 break;
 986         }
 987
 988         case PIO_SCRNMAP:
 989                 if (!perm)
 990                         ret = -EPERM;
 991                 else
 992                         ret = con_set_trans_old(up);
 993                 break;
 994
 995         case GIO_SCRNMAP:
 996                 ret = con_get_trans_old(up);
 997                 break;
 998
 999         case PIO_UNISCRNMAP:
1000                 if (!perm)
1001                         ret = -EPERM;
1002                 else
1003                         ret = con_set_trans_new(up);
1004                 break;
1005
1006         case GIO_UNISCRNMAP:
1007                 ret = con_get_trans_new(up);
1008                 break;
1009
1010         case PIO_UNIMAPCLR:
1011                 if (!perm)
1012                         return -EPERM;
1013                 con_clear_unimap(vc);
1014                 break;
1015
1016         case PIO_UNIMAP:
1017         case GIO_UNIMAP:
1018                 ret = do_unimap_ioctl(cmd, up, perm, vc);
1019                 break;
1020
1021         case VT_LOCKSWITCH:
1022                 if (!capable(CAP_SYS_TTY_CONFIG))
1023                         return -EPERM;
1024                 vt_dont_switch = true;
1025                 break;
1026         case VT_UNLOCKSWITCH:
1027                 if (!capable(CAP_SYS_TTY_CONFIG))
1028                         return -EPERM;
1029                 vt_dont_switch = false;
1030                 break;
1031         case VT_GETHIFONTMASK:
1032                 ret = put_user(vc->vc_hi_font_mask,
1033                                         (unsigned short __user *)arg);
1034                 break;
1035         case VT_WAITEVENT:
1036                 ret = vt_event_wait_ioctl((struct vt_event __user *)arg);
1037                 break;
1038         default:
1039                 ret = -ENOIOCTLCMD;
1040         }
1041 out:
1042         return ret;
1043 }
1044
1045 void reset_vc(struct vc_data *vc)
1046 {
1047         vc->vc_mode = KD_TEXT;
1048         vt_reset_unicode(vc->vc_num);
1049         vc->vt_mode.mode = VT_AUTO;
1050         vc->vt_mode.waitv = 0;
1051         vc->vt_mode.relsig = 0;
1052         vc->vt_mode.acqsig = 0;
1053         vc->vt_mode.frsig = 0;
1054         put_pid(vc->vt_pid);
1055         vc->vt_pid = NULL;
1056         vc->vt_newvt = -1;
1057         if (!in_interrupt())    /* Via keyboard.c:SAK() - akpm */
1058                 reset_palette(vc);
1059 }
1060
1061 void vc_SAK(struct work_struct *work)
1062 {
1063         struct vc *vc_con =
1064                 container_of(work, struct vc, SAK_work);
1065         struct vc_data *vc;
1066         struct tty_struct *tty;
1067
1068         console_lock();
1069         vc = vc_con->d;
1070         if (vc) {
1071                 /* FIXME: review tty ref counting */
1072                 tty = vc->port.tty;
1073                 /*
1074                  * SAK should also work in all raw modes and reset
1075                  * them properly.
1076                  */
1077                 if (tty)
1078                         __do_SAK(tty);
1079                 reset_vc(vc);
1080         }
1081         console_unlock();
1082 }
1083
1084 #ifdef CONFIG_COMPAT
1085
1086 struct compat_consolefontdesc {
1087         unsigned short charcount;       /* characters in font (256 or 512) */
1088         unsigned short charheight;      /* scan lines per character (1-32) */
1089         compat_caddr_t chardata;        /* font data in expanded form */
1090 };
1091
1092 static inline int
1093 compat_fontx_ioctl(int cmd, struct compat_consolefontdesc __user *user_cfd,
1094                          int perm, struct console_font_op *op)
1095 {
1096         struct compat_consolefontdesc cfdarg;
1097         int i;
1098
1099         if (copy_from_user(&cfdarg, user_cfd, sizeof(struct compat_consolefontdesc)))
1100                 return -EFAULT;
1101
1102         switch (cmd) {
1103         case PIO_FONTX:
1104                 if (!perm)
1105                         return -EPERM;
1106                 op->op = KD_FONT_OP_SET;
1107                 op->flags = KD_FONT_FLAG_OLD;
1108                 op->width = 8;
1109                 op->height = cfdarg.charheight;
1110                 op->charcount = cfdarg.charcount;
1111                 op->data = compat_ptr(cfdarg.chardata);
1112                 return con_font_op(vc_cons[fg_console].d, op);
1113         case GIO_FONTX:
1114                 op->op = KD_FONT_OP_GET;
1115                 op->flags = KD_FONT_FLAG_OLD;
1116                 op->width = 8;
1117                 op->height = cfdarg.charheight;
1118                 op->charcount = cfdarg.charcount;
1119                 op->data = compat_ptr(cfdarg.chardata);
1120                 i = con_font_op(vc_cons[fg_console].d, op);
1121                 if (i)
1122                         return i;
1123                 cfdarg.charheight = op->height;
1124                 cfdarg.charcount = op->charcount;
1125                 if (copy_to_user(user_cfd, &cfdarg, sizeof(struct compat_consolefontdesc)))
1126                         return -EFAULT;
1127                 return 0;
1128         }
1129         return -EINVAL;
1130 }
1131
1132 struct compat_console_font_op {
1133         compat_uint_t op;        /* operation code KD_FONT_OP_* */
1134         compat_uint_t flags;     /* KD_FONT_FLAG_* */
1135         compat_uint_t width, height;     /* font size */
1136         compat_uint_t charcount;
1137         compat_caddr_t data;    /* font data with height fixed to 32 */
1138 };
1139
1140 static inline int
1141 compat_kdfontop_ioctl(struct compat_console_font_op __user *fontop,
1142                          int perm, struct console_font_op *op, struct vc_data *vc)
1143 {
1144         int i;
1145
1146         if (copy_from_user(op, fontop, sizeof(struct compat_console_font_op)))
1147                 return -EFAULT;
1148         if (!perm && op->op != KD_FONT_OP_GET)
1149                 return -EPERM;
1150         op->data = compat_ptr(((struct compat_console_font_op *)op)->data);
1151         i = con_font_op(vc, op);
1152         if (i)
1153                 return i;
1154         ((struct compat_console_font_op *)op)->data = (unsigned long)op->data;
1155         if (copy_to_user(fontop, op, sizeof(struct compat_console_font_op)))
1156                 return -EFAULT;
1157         return 0;
1158 }
1159
1160 struct compat_unimapdesc {
1161         unsigned short entry_ct;
1162         compat_caddr_t entries;
1163 };
1164
1165 static inline int
1166 compat_unimap_ioctl(unsigned int cmd, struct compat_unimapdesc __user *user_ud,
1167                          int perm, struct vc_data *vc)
1168 {
1169         struct compat_unimapdesc tmp;
1170         struct unipair __user *tmp_entries;
1171
1172         if (copy_from_user(&tmp, user_ud, sizeof tmp))
1173                 return -EFAULT;
1174         tmp_entries = compat_ptr(tmp.entries);
1175         switch (cmd) {
1176         case PIO_UNIMAP:
1177                 if (!perm)
1178                         return -EPERM;
1179                 return con_set_unimap(vc, tmp.entry_ct, tmp_entries);
1180         case GIO_UNIMAP:
1181                 if (!perm && fg_console != vc->vc_num)
1182                         return -EPERM;
1183                 return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp_entries);
1184         }
1185         return 0;
1186 }
1187
1188 long vt_compat_ioctl(struct tty_struct *tty,
1189              unsigned int cmd, unsigned long arg)
1190 {
1191         struct vc_data *vc = tty->driver_data;
1192         struct console_font_op op;      /* used in multiple places here */
1193         void __user *up = compat_ptr(arg);
1194         int perm;
1195
1196         /*
1197          * To have permissions to do most of the vt ioctls, we either have
1198          * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
1199          */
1200         perm = 0;
1201         if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
1202                 perm = 1;
1203
1204         switch (cmd) {
1205         /*
1206          * these need special handlers for incompatible data structures
1207          */
1208         case PIO_FONTX:
1209         case GIO_FONTX:
1210                 return compat_fontx_ioctl(cmd, up, perm, &op);
1211
1212         case KDFONTOP:
1213                 return compat_kdfontop_ioctl(up, perm, &op, vc);
1214
1215         case PIO_UNIMAP:
1216         case GIO_UNIMAP:
1217                 return compat_unimap_ioctl(cmd, up, perm, vc);
1218
1219         /*
1220          * all these treat 'arg' as an integer
1221          */
1222         case KIOCSOUND:
1223         case KDMKTONE:
1224 #ifdef CONFIG_X86
1225         case KDADDIO:
1226         case KDDELIO:
1227 #endif
1228         case KDSETMODE:
1229         case KDMAPDISP:
1230         case KDUNMAPDISP:
1231         case KDSKBMODE:
1232         case KDSKBMETA:
1233         case KDSKBLED:
1234         case KDSETLED:
1235         case KDSIGACCEPT:
1236         case VT_ACTIVATE:
1237         case VT_WAITACTIVE:
1238         case VT_RELDISP:
1239         case VT_DISALLOCATE:
1240         case VT_RESIZE:
1241         case VT_RESIZEX:
1242                 return vt_ioctl(tty, cmd, arg);
1243
1244         /*
1245          * the rest has a compatible data structure behind arg,
1246          * but we have to convert it to a proper 64 bit pointer.
1247          */
1248         default:
1249                 return vt_ioctl(tty, cmd, (unsigned long)up);
1250         }
1251 }
1252
1253
1254 #endif /* CONFIG_COMPAT */
1255
1256
1257 /*
1258  * Performs the back end of a vt switch. Called under the console
1259  * semaphore.
1260  */
1261 static void complete_change_console(struct vc_data *vc)
1262 {
1263         unsigned char old_vc_mode;
1264         int old = fg_console;
1265
1266         last_console = fg_console;
1267
1268         /*
1269          * If we're switching, we could be going from KD_GRAPHICS to
1270          * KD_TEXT mode or vice versa, which means we need to blank or
1271          * unblank the screen later.
1272          */
1273         old_vc_mode = vc_cons[fg_console].d->vc_mode;
1274         switch_screen(vc);
1275
1276         /*
1277          * This can't appear below a successful kill_pid().  If it did,
1278          * then the *blank_screen operation could occur while X, having
1279          * received acqsig, is waking up on another processor.  This
1280          * condition can lead to overlapping accesses to the VGA range
1281          * and the framebuffer (causing system lockups).
1282          *
1283          * To account for this we duplicate this code below only if the
1284          * controlling process is gone and we've called reset_vc.
1285          */
1286         if (old_vc_mode != vc->vc_mode) {
1287                 if (vc->vc_mode == KD_TEXT)
1288                         do_unblank_screen(1);
1289                 else
1290                         do_blank_screen(1);
1291         }
1292
1293         /*
1294          * If this new console is under process control, send it a signal
1295          * telling it that it has acquired. Also check if it has died and
1296          * clean up (similar to logic employed in change_console())
1297          */
1298         if (vc->vt_mode.mode == VT_PROCESS) {
1299                 /*
1300                  * Send the signal as privileged - kill_pid() will
1301                  * tell us if the process has gone or something else
1302                  * is awry
1303                  */
1304                 if (kill_pid(vc->vt_pid, vc->vt_mode.acqsig, 1) != 0) {
1305                 /*
1306                  * The controlling process has died, so we revert back to
1307                  * normal operation. In this case, we'll also change back
1308                  * to KD_TEXT mode. I'm not sure if this is strictly correct
1309                  * but it saves the agony when the X server dies and the screen
1310                  * remains blanked due to KD_GRAPHICS! It would be nice to do
1311                  * this outside of VT_PROCESS but there is no single process
1312                  * to account for and tracking tty count may be undesirable.
1313                  */
1314                         reset_vc(vc);
1315
1316                         if (old_vc_mode != vc->vc_mode) {
1317                                 if (vc->vc_mode == KD_TEXT)
1318                                         do_unblank_screen(1);
1319                                 else
1320                                         do_blank_screen(1);
1321                         }
1322                 }
1323         }
1324
1325         /*
1326          * Wake anyone waiting for their VT to activate
1327          */
1328         vt_event_post(VT_EVENT_SWITCH, old, vc->vc_num);
1329         return;
1330 }
1331
1332 /*
1333  * Performs the front-end of a vt switch
1334  */
1335 void change_console(struct vc_data *new_vc)
1336 {
1337         struct vc_data *vc;
1338
1339         if (!new_vc || new_vc->vc_num == fg_console || vt_dont_switch)
1340                 return;
1341
1342         /*
1343          * If this vt is in process mode, then we need to handshake with
1344          * that process before switching. Essentially, we store where that
1345          * vt wants to switch to and wait for it to tell us when it's done
1346          * (via VT_RELDISP ioctl).
1347          *
1348          * We also check to see if the controlling process still exists.
1349          * If it doesn't, we reset this vt to auto mode and continue.
1350          * This is a cheap way to track process control. The worst thing
1351          * that can happen is: we send a signal to a process, it dies, and
1352          * the switch gets "lost" waiting for a response; hopefully, the
1353          * user will try again, we'll detect the process is gone (unless
1354          * the user waits just the right amount of time :-) and revert the
1355          * vt to auto control.
1356          */
1357         vc = vc_cons[fg_console].d;
1358         if (vc->vt_mode.mode == VT_PROCESS) {
1359                 /*
1360                  * Send the signal as privileged - kill_pid() will
1361                  * tell us if the process has gone or something else
1362                  * is awry.
1363                  *
1364                  * We need to set vt_newvt *before* sending the signal or we
1365                  * have a race.
1366                  */
1367                 vc->vt_newvt = new_vc->vc_num;
1368                 if (kill_pid(vc->vt_pid, vc->vt_mode.relsig, 1) == 0) {
1369                         /*
1370                          * It worked. Mark the vt to switch to and
1371                          * return. The process needs to send us a
1372                          * VT_RELDISP ioctl to complete the switch.
1373                          */
1374                         return;
1375                 }
1376
1377                 /*
1378                  * The controlling process has died, so we revert back to
1379                  * normal operation. In this case, we'll also change back
1380                  * to KD_TEXT mode. I'm not sure if this is strictly correct
1381                  * but it saves the agony when the X server dies and the screen
1382                  * remains blanked due to KD_GRAPHICS! It would be nice to do
1383                  * this outside of VT_PROCESS but there is no single process
1384                  * to account for and tracking tty count may be undesirable.
1385                  */
1386                 reset_vc(vc);
1387
1388                 /*
1389                  * Fall through to normal (VT_AUTO) handling of the switch...
1390                  */
1391         }
1392
1393         /*
1394          * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
1395          */
1396         if (vc->vc_mode == KD_GRAPHICS)
1397                 return;
1398
1399         complete_change_console(new_vc);
1400 }
1401
1402 /* Perform a kernel triggered VT switch for suspend/resume */
1403
1404 static int disable_vt_switch;
1405
1406 int vt_move_to_console(unsigned int vt, int alloc)
1407 {
1408         int prev;
1409
1410         console_lock();
1411         /* Graphics mode - up to X */
1412         if (disable_vt_switch) {
1413                 console_unlock();
1414                 return 0;
1415         }
1416         prev = fg_console;
1417
1418         if (alloc && vc_allocate(vt)) {
1419                 /* we can't have a free VC for now. Too bad,
1420                  * we don't want to mess the screen for now. */
1421                 console_unlock();
1422                 return -ENOSPC;
1423         }
1424
1425         if (set_console(vt)) {
1426                 /*
1427                  * We're unable to switch to the SUSPEND_CONSOLE.
1428                  * Let the calling function know so it can decide
1429                  * what to do.
1430                  */
1431                 console_unlock();
1432                 return -EIO;
1433         }
1434         console_unlock();
1435         if (vt_waitactive(vt + 1)) {
1436                 pr_debug("Suspend: Can't switch VCs.");
1437                 return -EINTR;
1438         }
1439         return prev;
1440 }
1441
1442 /*
1443  * Normally during a suspend, we allocate a new console and switch to it.
1444  * When we resume, we switch back to the original console.  This switch
1445  * can be slow, so on systems where the framebuffer can handle restoration
1446  * of video registers anyways, there's little point in doing the console
1447  * switch.  This function allows you to disable it by passing it '0'.
1448  */
1449 void pm_set_vt_switch(int do_switch)
1450 {
1451         console_lock();
1452         disable_vt_switch = !do_switch;
1453         console_unlock();
1454 }
1455 EXPORT_SYMBOL(pm_set_vt_switch);