1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1992 obz under the linux copyright
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
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>
22 #include <linux/string.h>
23 #include <linux/slab.h>
24 #include <linux/major.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>
33 #include <linux/uaccess.h>
35 #include <linux/nospec.h>
37 #include <linux/kbd_kern.h>
38 #include <linux/vt_kern.h>
39 #include <linux/kbd_diacr.h>
40 #include <linux/selection.h>
44 static inline bool vt_in_use(unsigned int i)
46 const struct vc_data *vc = vc_cons[i].d;
49 * console_lock must be held to prevent the vc from being deallocated
50 * while we're checking whether it's in-use.
52 WARN_CONSOLE_UNLOCKED();
54 return vc && kref_read(&vc->port.kref) > 1;
57 static inline bool vt_busy(int i)
63 if (vc_is_sel(vc_cons[i].d))
70 * Console (vt and kd) routines, as defined by USL SVR4 manual, and by
71 * experimentation and study of X386 SYSV handling.
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.
83 #include <asm/syscalls.h>
86 static void complete_change_console(struct vc_data *vc);
89 * User space VT_EVENT handlers
92 struct vt_event_wait {
93 struct list_head list;
94 struct vt_event event;
98 static LIST_HEAD(vt_events);
99 static DEFINE_SPINLOCK(vt_event_lock);
100 static DECLARE_WAIT_QUEUE_HEAD(vt_event_waitqueue);
104 * @event: the event that occurred
108 * Post an VT event to interested VT handlers
111 void vt_event_post(unsigned int event, unsigned int old, unsigned int new)
113 struct list_head *pos, *head;
117 spin_lock_irqsave(&vt_event_lock, flags);
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))
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;
133 spin_unlock_irqrestore(&vt_event_lock, flags);
135 wake_up_interruptible(&vt_event_waitqueue);
138 static void __vt_event_queue(struct vt_event_wait *vw)
141 /* Prepare the event */
142 INIT_LIST_HEAD(&vw->list);
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);
150 static void __vt_event_wait(struct vt_event_wait *vw)
152 /* Wait for it to pass */
153 wait_event_interruptible(vt_event_waitqueue, vw->done);
156 static void __vt_event_dequeue(struct vt_event_wait *vw)
161 spin_lock_irqsave(&vt_event_lock, flags);
163 spin_unlock_irqrestore(&vt_event_lock, flags);
167 * vt_event_wait - wait for an event
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.
175 static void vt_event_wait(struct vt_event_wait *vw)
177 __vt_event_queue(vw);
179 __vt_event_dequeue(vw);
183 * vt_event_wait_ioctl - event ioctl handler
184 * @event: argument to ioctl (the event)
186 * Implement the VT_WAITEVENT ioctl using the VT event interface
189 static int vt_event_wait_ioctl(struct vt_event __user *event)
191 struct vt_event_wait vw;
193 if (copy_from_user(&vw.event, event, sizeof(struct vt_event)))
195 /* Highest supported event for now */
196 if (vw.event.event & ~VT_MAX_EVENT)
200 /* If it occurred report it */
202 if (copy_to_user(event, &vw.event, sizeof(struct vt_event)))
210 * vt_waitactive - active console wait
213 * Helper for event waits. Used to implement the legacy
214 * event waiting ioctls in terms of events
217 int vt_waitactive(int n)
219 struct vt_event_wait vw;
221 vw.event.event = VT_EVENT_SWITCH;
222 __vt_event_queue(&vw);
223 if (n == fg_console + 1) {
224 __vt_event_dequeue(&vw);
227 __vt_event_wait(&vw);
228 __vt_event_dequeue(&vw);
231 } while (vw.event.newev != n);
236 * these are the valid i/o ports we're allowed to change. they map all the
239 #define GPFIRST 0x3b4
241 #define GPNUM (GPLAST - GPFIRST + 1)
244 * currently, setting the mode from KD_TEXT to KD_GRAPHICS doesn't do a whole
245 * lot. i'm not sure if it should do any restoration of modes or what...
247 * XXX It should at least call into the driver, fbdev's definitely need to
248 * restore their engine state. --BenH
250 static int vt_kdsetmode(struct vc_data *vc, unsigned long mode)
265 /* FIXME: this needs the console lock extending */
266 if (vc->vc_mode == mode)
270 if (vc->vc_num != fg_console)
273 /* explicitly blank/unblank the screen if switching modes */
276 do_unblank_screen(1);
284 static int vt_k_ioctl(struct tty_struct *tty, unsigned int cmd,
285 unsigned long arg, bool perm)
287 struct vc_data *vc = tty->driver_data;
288 void __user *up = (void __user *)arg;
289 unsigned int console = vc->vc_num;
297 * The use of PIT_TICK_RATE is historic, it used to be
298 * the platform-dependent CLOCK_TICK_RATE between 2.6.12
299 * and 2.6.36, which was a minor but unfortunate ABI
300 * change. kd_mksound is locked by the input layer.
303 arg = PIT_TICK_RATE / arg;
311 unsigned int ticks, count;
314 * Generate the tone for the appropriate number of ticks.
315 * If the time is zero, turn off sound ourselves.
317 ticks = msecs_to_jiffies((arg >> 16) & 0xffff);
318 count = ticks ? (arg & 0xffff) : 0;
320 count = PIT_TICK_RATE / count;
321 kd_mksound(count, ticks);
329 return put_user(KB_101, (char __user *)arg);
332 * These cannot be implemented on any machine that implements
333 * ioperm() in user level (such as Alpha PCs) or not at all.
335 * XXX: you should never use these, just call ioperm directly..
341 * KDADDIO and KDDELIO may be able to add ports beyond what
342 * we reject here, but to be safe...
344 * These are locked internally via sys_ioperm
346 if (arg < GPFIRST || arg > GPLAST)
349 return ksys_ioperm(arg, 1, (cmd == KDADDIO)) ? -ENXIO : 0;
353 return ksys_ioperm(GPFIRST, GPNUM,
354 (cmd == KDENABIO)) ? -ENXIO : 0;
357 /* Linux m68k/i386 interface for setting the keyboard delay/repeat rate */
361 struct kbd_repeat kbrep;
363 if (!capable(CAP_SYS_TTY_CONFIG))
366 if (copy_from_user(&kbrep, up, sizeof(struct kbd_repeat)))
369 ret = kbd_rate(&kbrep);
372 if (copy_to_user(up, &kbrep, sizeof(struct kbd_repeat)))
381 return vt_kdsetmode(vc, arg);
384 return put_user(vc->vc_mode, (int __user *)arg);
389 * these work like a combination of mmap and KDENABIO.
390 * this could be easily finished.
397 ret = vt_do_kdskbmode(console, arg);
400 tty_ldisc_flush(tty);
404 return put_user(vt_do_kdgkbmode(console), (int __user *)arg);
406 /* this could be folded into KDSKBMODE, but for compatibility
407 reasons it is not so easy to fold KDGKBMETA into KDGKBMODE */
409 return vt_do_kdskbmeta(console, arg);
412 /* FIXME: should review whether this is worth locking */
413 return put_user(vt_do_kdgkbmeta(console), (int __user *)arg);
417 if(!capable(CAP_SYS_TTY_CONFIG))
419 return vt_do_kbkeycode_ioctl(cmd, up, perm);
423 return vt_do_kdsk_ioctl(cmd, up, perm, console);
427 return vt_do_kdgkb_ioctl(cmd, up, perm);
429 /* Diacritical processing. Handled in keyboard.c as it has
430 to operate on the keyboard locks and structures */
435 return vt_do_diacrit(cmd, up, perm);
437 /* the ioctls below read/set the flags usually shown in the leds */
438 /* don't use them - they will go away without warning */
443 return vt_do_kdskled(console, cmd, arg, perm);
446 * A process can indicate its willingness to accept signals
447 * generated by pressing an appropriate key combination.
448 * Thus, one can have a daemon that e.g. spawns a new console
449 * upon a keypress and then changes to it.
450 * See also the kbrequest field of inittab(5).
453 if (!perm || !capable(CAP_KILL))
455 if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
458 spin_lock_irq(&vt_spawn_con.lock);
459 put_pid(vt_spawn_con.pid);
460 vt_spawn_con.pid = get_pid(task_pid(current));
461 vt_spawn_con.sig = arg;
462 spin_unlock_irq(&vt_spawn_con.lock);
466 struct console_font_op op;
468 if (copy_from_user(&op, up, sizeof(op)))
470 if (!perm && op.op != KD_FONT_OP_GET)
472 ret = con_font_op(vc, &op);
475 if (copy_to_user(up, &op, sizeof(op)))
487 static inline int do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud,
488 bool perm, struct vc_data *vc)
490 struct unimapdesc tmp;
492 if (copy_from_user(&tmp, user_ud, sizeof tmp))
498 return con_set_unimap(vc, tmp.entry_ct, tmp.entries);
500 if (!perm && fg_console != vc->vc_num)
502 return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct),
508 static int vt_io_ioctl(struct vc_data *vc, unsigned int cmd, void __user *up,
515 return con_set_cmap(up);
518 return con_get_cmap(up);
523 return con_set_trans_old(up);
526 return con_get_trans_old(up);
531 return con_set_trans_new(up);
534 return con_get_trans_new(up);
539 con_clear_unimap(vc);
544 return do_unimap_ioctl(cmd, up, perm, vc);
553 static int vt_reldisp(struct vc_data *vc, unsigned int swtch)
557 if (vc->vt_mode.mode != VT_PROCESS)
560 /* Switched-to response */
561 if (vc->vt_newvt < 0) {
562 /* If it's just an ACK, ignore it */
563 return swtch == VT_ACKACQ ? 0 : -EINVAL;
566 /* Switching-from response */
568 /* Switch disallowed, so forget we were trying to do it. */
573 /* The current vt has been released, so complete the switch. */
574 newvt = vc->vt_newvt;
576 ret = vc_allocate(newvt);
581 * When we actually do the console switch, make sure we are atomic with
582 * respect to other console switches..
584 complete_change_console(vc_cons[newvt].d);
589 static int vt_setactivate(struct vt_setactivate __user *sa)
591 struct vt_setactivate vsa;
595 if (copy_from_user(&vsa, sa, sizeof(vsa)))
597 if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES)
600 vsa.console = array_index_nospec(vsa.console, MAX_NR_CONSOLES + 1);
603 ret = vc_allocate(vsa.console);
610 * This is safe providing we don't drop the console sem between
611 * vc_allocate and finishing referencing nvc.
613 nvc = vc_cons[vsa.console].d;
614 nvc->vt_mode = vsa.mode;
615 nvc->vt_mode.frsig = 0;
616 put_pid(nvc->vt_pid);
617 nvc->vt_pid = get_pid(task_pid(current));
620 /* Commence switch and lock */
621 /* Review set_console locks */
622 set_console(vsa.console);
627 /* deallocate a single console, if possible (leave 0) */
628 static int vt_disallocate(unsigned int vc_num)
630 struct vc_data *vc = NULL;
637 vc = vc_deallocate(vc_num);
640 if (vc && vc_num >= MIN_NR_CONSOLES)
641 tty_port_put(&vc->port);
646 /* deallocate all unused consoles, but leave 0 */
647 static void vt_disallocate_all(void)
649 struct vc_data *vc[MAX_NR_CONSOLES];
653 for (i = 1; i < MAX_NR_CONSOLES; i++)
655 vc[i] = vc_deallocate(i);
660 for (i = 1; i < MAX_NR_CONSOLES; i++) {
661 if (vc[i] && i >= MIN_NR_CONSOLES)
662 tty_port_put(&vc[i]->port);
666 static int vt_resizex(struct vc_data *vc, struct vt_consize __user *cs)
671 if (copy_from_user(&v, cs, sizeof(struct vt_consize)))
674 /* FIXME: Should check the copies properly */
676 v.v_vlin = vc->vc_scan_lines;
679 int rows = v.v_vlin / v.v_clin;
680 if (v.v_rows != rows) {
681 if (v.v_rows) /* Parameters don't add up */
687 if (v.v_vcol && v.v_ccol) {
688 int cols = v.v_vcol / v.v_ccol;
689 if (v.v_cols != cols) {
699 for (i = 0; i < MAX_NR_CONSOLES; i++) {
708 int save_scan_lines = vcp->vc_scan_lines;
709 int save_font_height = vcp->vc_font.height;
712 vcp->vc_scan_lines = v.v_vlin;
714 vcp->vc_font.height = v.v_clin;
715 vcp->vc_resize_user = 1;
716 ret = vc_resize(vcp, v.v_cols, v.v_rows);
718 vcp->vc_scan_lines = save_scan_lines;
719 vcp->vc_font.height = save_font_height;
731 * We handle the console-specific ioctl's here. We allow the
732 * capability to modify any console, not just the fg_console.
734 int vt_ioctl(struct tty_struct *tty,
735 unsigned int cmd, unsigned long arg)
737 struct vc_data *vc = tty->driver_data;
738 void __user *up = (void __user *)arg;
743 * To have permissions to do most of the vt ioctls, we either have
744 * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
747 if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
750 ret = vt_k_ioctl(tty, cmd, arg, perm);
751 if (ret != -ENOIOCTLCMD)
754 ret = vt_io_ioctl(vc, cmd, up, perm);
755 if (ret != -ENOIOCTLCMD)
760 return tioclinux(tty, arg);
767 if (copy_from_user(&tmp, up, sizeof(struct vt_mode)))
769 if (tmp.mode != VT_AUTO && tmp.mode != VT_PROCESS)
774 /* the frsig is ignored, so we set it to 0 */
775 vc->vt_mode.frsig = 0;
777 vc->vt_pid = get_pid(task_pid(current));
778 /* no switch is required -- saw@shade.msu.ru */
790 memcpy(&tmp, &vc->vt_mode, sizeof(struct vt_mode));
793 rc = copy_to_user(up, &tmp, sizeof(struct vt_mode));
800 * Returns global vt state. Note that VT 0 is always open, since
801 * it's an alias for the current VT, and people can't use it here.
802 * We cannot return state for more than 16 VTs, since v_state is short.
806 struct vt_stat __user *vtstat = up;
807 unsigned short state, mask;
809 if (put_user(fg_console + 1, &vtstat->v_active))
812 state = 1; /* /dev/tty0 is always open */
813 console_lock(); /* required by vt_in_use() */
814 for (i = 0, mask = 2; i < MAX_NR_CONSOLES && mask;
819 return put_user(state, &vtstat->v_state);
823 * Returns the first available (non-opened) console.
826 console_lock(); /* required by vt_in_use() */
827 for (i = 0; i < MAX_NR_CONSOLES; ++i)
831 i = i < MAX_NR_CONSOLES ? (i+1) : -1;
832 return put_user(i, (int __user *)arg);
835 * ioctl(fd, VT_ACTIVATE, num) will cause us to switch to vt # num,
836 * with num >= 1 (switches to vt 0, our console, are not allowed, just
837 * to preserve sanity).
842 if (arg == 0 || arg > MAX_NR_CONSOLES)
847 ret = vc_allocate(arg);
858 return vt_setactivate(up);
861 * wait until the specified VT has been activated
866 if (arg == 0 || arg > MAX_NR_CONSOLES)
868 return vt_waitactive(arg);
871 * If a vt is under process control, the kernel will not switch to it
872 * immediately, but postpone the operation until the process calls this
873 * ioctl, allowing the switch to complete.
875 * According to the X sources this is the behavior:
876 * 0: pending switch-from not OK
877 * 1: pending switch-from OK
878 * 2: completed switch-to OK
885 ret = vt_reldisp(vc, arg);
892 * Disallocate memory associated to VT (but leave VT1)
895 if (arg > MAX_NR_CONSOLES)
899 vt_disallocate_all();
901 return vt_disallocate(--arg);
906 struct vt_sizes __user *vtsizes = up;
912 if (get_user(ll, &vtsizes->v_rows) ||
913 get_user(cc, &vtsizes->v_cols))
917 for (i = 0; i < MAX_NR_CONSOLES; i++) {
921 vc->vc_resize_user = 1;
922 /* FIXME: review v tty lock */
923 vc_resize(vc_cons[i].d, cc, ll);
934 return vt_resizex(vc, up);
937 if (!capable(CAP_SYS_TTY_CONFIG))
939 vt_dont_switch = true;
941 case VT_UNLOCKSWITCH:
942 if (!capable(CAP_SYS_TTY_CONFIG))
944 vt_dont_switch = false;
946 case VT_GETHIFONTMASK:
947 return put_user(vc->vc_hi_font_mask,
948 (unsigned short __user *)arg);
950 return vt_event_wait_ioctl((struct vt_event __user *)arg);
958 void reset_vc(struct vc_data *vc)
960 vc->vc_mode = KD_TEXT;
961 vt_reset_unicode(vc->vc_num);
962 vc->vt_mode.mode = VT_AUTO;
963 vc->vt_mode.waitv = 0;
964 vc->vt_mode.relsig = 0;
965 vc->vt_mode.acqsig = 0;
966 vc->vt_mode.frsig = 0;
973 void vc_SAK(struct work_struct *work)
976 container_of(work, struct vc, SAK_work);
978 struct tty_struct *tty;
983 /* FIXME: review tty ref counting */
986 * SAK should also work in all raw modes and reset
998 struct compat_console_font_op {
999 compat_uint_t op; /* operation code KD_FONT_OP_* */
1000 compat_uint_t flags; /* KD_FONT_FLAG_* */
1001 compat_uint_t width, height; /* font size */
1002 compat_uint_t charcount;
1003 compat_caddr_t data; /* font data with height fixed to 32 */
1007 compat_kdfontop_ioctl(struct compat_console_font_op __user *fontop,
1008 int perm, struct console_font_op *op, struct vc_data *vc)
1012 if (copy_from_user(op, fontop, sizeof(struct compat_console_font_op)))
1014 if (!perm && op->op != KD_FONT_OP_GET)
1016 op->data = compat_ptr(((struct compat_console_font_op *)op)->data);
1017 i = con_font_op(vc, op);
1020 ((struct compat_console_font_op *)op)->data = (unsigned long)op->data;
1021 if (copy_to_user(fontop, op, sizeof(struct compat_console_font_op)))
1026 struct compat_unimapdesc {
1027 unsigned short entry_ct;
1028 compat_caddr_t entries;
1032 compat_unimap_ioctl(unsigned int cmd, struct compat_unimapdesc __user *user_ud,
1033 int perm, struct vc_data *vc)
1035 struct compat_unimapdesc tmp;
1036 struct unipair __user *tmp_entries;
1038 if (copy_from_user(&tmp, user_ud, sizeof tmp))
1040 tmp_entries = compat_ptr(tmp.entries);
1045 return con_set_unimap(vc, tmp.entry_ct, tmp_entries);
1047 if (!perm && fg_console != vc->vc_num)
1049 return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct), tmp_entries);
1054 long vt_compat_ioctl(struct tty_struct *tty,
1055 unsigned int cmd, unsigned long arg)
1057 struct vc_data *vc = tty->driver_data;
1058 struct console_font_op op; /* used in multiple places here */
1059 void __user *up = compat_ptr(arg);
1063 * To have permissions to do most of the vt ioctls, we either have
1064 * to be the owner of the tty, or have CAP_SYS_TTY_CONFIG.
1067 if (current->signal->tty == tty || capable(CAP_SYS_TTY_CONFIG))
1072 * these need special handlers for incompatible data structures
1076 return compat_kdfontop_ioctl(up, perm, &op, vc);
1080 return compat_unimap_ioctl(cmd, up, perm, vc);
1083 * all these treat 'arg' as an integer
1102 case VT_DISALLOCATE:
1105 return vt_ioctl(tty, cmd, arg);
1108 * the rest has a compatible data structure behind arg,
1109 * but we have to convert it to a proper 64 bit pointer.
1112 return vt_ioctl(tty, cmd, (unsigned long)up);
1117 #endif /* CONFIG_COMPAT */
1121 * Performs the back end of a vt switch. Called under the console
1124 static void complete_change_console(struct vc_data *vc)
1126 unsigned char old_vc_mode;
1127 int old = fg_console;
1129 last_console = fg_console;
1132 * If we're switching, we could be going from KD_GRAPHICS to
1133 * KD_TEXT mode or vice versa, which means we need to blank or
1134 * unblank the screen later.
1136 old_vc_mode = vc_cons[fg_console].d->vc_mode;
1140 * This can't appear below a successful kill_pid(). If it did,
1141 * then the *blank_screen operation could occur while X, having
1142 * received acqsig, is waking up on another processor. This
1143 * condition can lead to overlapping accesses to the VGA range
1144 * and the framebuffer (causing system lockups).
1146 * To account for this we duplicate this code below only if the
1147 * controlling process is gone and we've called reset_vc.
1149 if (old_vc_mode != vc->vc_mode) {
1150 if (vc->vc_mode == KD_TEXT)
1151 do_unblank_screen(1);
1157 * If this new console is under process control, send it a signal
1158 * telling it that it has acquired. Also check if it has died and
1159 * clean up (similar to logic employed in change_console())
1161 if (vc->vt_mode.mode == VT_PROCESS) {
1163 * Send the signal as privileged - kill_pid() will
1164 * tell us if the process has gone or something else
1167 if (kill_pid(vc->vt_pid, vc->vt_mode.acqsig, 1) != 0) {
1169 * The controlling process has died, so we revert back to
1170 * normal operation. In this case, we'll also change back
1171 * to KD_TEXT mode. I'm not sure if this is strictly correct
1172 * but it saves the agony when the X server dies and the screen
1173 * remains blanked due to KD_GRAPHICS! It would be nice to do
1174 * this outside of VT_PROCESS but there is no single process
1175 * to account for and tracking tty count may be undesirable.
1179 if (old_vc_mode != vc->vc_mode) {
1180 if (vc->vc_mode == KD_TEXT)
1181 do_unblank_screen(1);
1189 * Wake anyone waiting for their VT to activate
1191 vt_event_post(VT_EVENT_SWITCH, old, vc->vc_num);
1196 * Performs the front-end of a vt switch
1198 void change_console(struct vc_data *new_vc)
1202 if (!new_vc || new_vc->vc_num == fg_console || vt_dont_switch)
1206 * If this vt is in process mode, then we need to handshake with
1207 * that process before switching. Essentially, we store where that
1208 * vt wants to switch to and wait for it to tell us when it's done
1209 * (via VT_RELDISP ioctl).
1211 * We also check to see if the controlling process still exists.
1212 * If it doesn't, we reset this vt to auto mode and continue.
1213 * This is a cheap way to track process control. The worst thing
1214 * that can happen is: we send a signal to a process, it dies, and
1215 * the switch gets "lost" waiting for a response; hopefully, the
1216 * user will try again, we'll detect the process is gone (unless
1217 * the user waits just the right amount of time :-) and revert the
1218 * vt to auto control.
1220 vc = vc_cons[fg_console].d;
1221 if (vc->vt_mode.mode == VT_PROCESS) {
1223 * Send the signal as privileged - kill_pid() will
1224 * tell us if the process has gone or something else
1227 * We need to set vt_newvt *before* sending the signal or we
1230 vc->vt_newvt = new_vc->vc_num;
1231 if (kill_pid(vc->vt_pid, vc->vt_mode.relsig, 1) == 0) {
1233 * It worked. Mark the vt to switch to and
1234 * return. The process needs to send us a
1235 * VT_RELDISP ioctl to complete the switch.
1241 * The controlling process has died, so we revert back to
1242 * normal operation. In this case, we'll also change back
1243 * to KD_TEXT mode. I'm not sure if this is strictly correct
1244 * but it saves the agony when the X server dies and the screen
1245 * remains blanked due to KD_GRAPHICS! It would be nice to do
1246 * this outside of VT_PROCESS but there is no single process
1247 * to account for and tracking tty count may be undesirable.
1252 * Fall through to normal (VT_AUTO) handling of the switch...
1257 * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
1259 if (vc->vc_mode == KD_GRAPHICS)
1262 complete_change_console(new_vc);
1265 /* Perform a kernel triggered VT switch for suspend/resume */
1267 static int disable_vt_switch;
1269 int vt_move_to_console(unsigned int vt, int alloc)
1274 /* Graphics mode - up to X */
1275 if (disable_vt_switch) {
1281 if (alloc && vc_allocate(vt)) {
1282 /* we can't have a free VC for now. Too bad,
1283 * we don't want to mess the screen for now. */
1288 if (set_console(vt)) {
1290 * We're unable to switch to the SUSPEND_CONSOLE.
1291 * Let the calling function know so it can decide
1298 if (vt_waitactive(vt + 1)) {
1299 pr_debug("Suspend: Can't switch VCs.");
1306 * Normally during a suspend, we allocate a new console and switch to it.
1307 * When we resume, we switch back to the original console. This switch
1308 * can be slow, so on systems where the framebuffer can handle restoration
1309 * of video registers anyways, there's little point in doing the console
1310 * switch. This function allows you to disable it by passing it '0'.
1312 void pm_set_vt_switch(int do_switch)
1315 disable_vt_switch = !do_switch;
1318 EXPORT_SYMBOL(pm_set_vt_switch);