kernel - Fix excessive call stack depth on stuck interrupt

[dragonfly.git] / sys / kern / tty_cons.c

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      from: @(#)cons.c        7.2 (Berkeley) 5/9/91
 * $FreeBSD: src/sys/kern/tty_cons.c,v 1.81.2.4 2001/12/17 18:44:41 guido Exp $
 */

#include "opt_ddb.h"
#include "opt_comconsole.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/priv.h>
#include <sys/reboot.h>
#include <sys/sysctl.h>
#include <sys/tty.h>
#include <sys/uio.h>
#include <sys/msgport.h>
#include <sys/msgport2.h>
#include <sys/device.h>

#include <ddb/ddb.h>

#include <machine/cpu.h>

static d_open_t cnopen;
static d_close_t cnclose;
static d_read_t cnread;
static d_write_t cnwrite;
static d_ioctl_t cnioctl;
static d_kqfilter_t cnkqfilter;

static int cnintercept(struct dev_generic_args *ap);

#define CDEV_MAJOR      0
static struct dev_ops cn_ops = {
        { "console", 0, D_TTY | D_MPSAFE },
        .d_open =       cnopen,
        .d_close =      cnclose,
        .d_read =       cnread,
        .d_write =      cnwrite,
        .d_ioctl =      cnioctl,
        .d_kqfilter =   cnkqfilter,
};

static struct dev_ops cn_iops = {
        { "intercept", 0, D_TTY | D_MPSAFE },
        .d_default =    cnintercept
};

static struct dev_ops *cn_fwd_ops;
static cdev_t   cn_dev;

//XXX: get this shit out! (alexh)
#if 0
SYSCTL_OPAQUE(_machdep, CPU_CONSDEV, consdev, CTLFLAG_RD,
        &cn_udev, sizeof cn_udev, "T,udev_t", "");
#endif

static int cn_mute;

#ifdef BREAK_TO_DEBUGGER
int     break_to_debugger = 1;
#else
int     break_to_debugger = 0;
#endif
TUNABLE_INT("kern.break_to_debugger", &break_to_debugger);
SYSCTL_INT(_kern, OID_AUTO, break_to_debugger, CTLFLAG_RW,
        &break_to_debugger, 0, "");

#ifdef ALT_BREAK_TO_DEBUGGER
int     alt_break_to_debugger = 1;
#else
int     alt_break_to_debugger = 0;
#endif
TUNABLE_INT("kern.alt_break_to_debugger", &alt_break_to_debugger);
SYSCTL_INT(_kern, OID_AUTO, alt_break_to_debugger, CTLFLAG_RW,
        &alt_break_to_debugger, 0, "");

int     cons_unavail = 0;       /* XXX:
                                 * physical console not available for
                                 * input (i.e., it is in graphics mode)
                                 */
int     sysbeep_enable = 1;

static u_char cn_is_open;               /* nonzero if logical console is open */
static int openmode, openflag;          /* how /dev/console was openned */
static cdev_t cn_devfsdev;              /* represents the device private info */
static u_char cn_phys_is_open;          /* nonzero if physical device is open */
static u_char console_pausing;          /* pause after each line during probe */
static char *console_pausestr=
"<pause; press any key to proceed to next line or '.' to end pause mode>";

struct consdev *cn_tab;         /* physical console device info */
struct consdev *gdb_tab;        /* physical gdb debugger device info */

SYSCTL_INT(_kern, OID_AUTO, sysbeep_enable, CTLFLAG_RW, &sysbeep_enable, 0, "");
static uint32_t console_rdev;
SYSCTL_INT(_kern, OID_AUTO, console_rdev, CTLFLAG_RW,
        &console_rdev, 0, "");

CONS_DRIVER(cons, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
SET_DECLARE(cons_set, struct consdev);

void
cninit(void)
{
        struct consdev *best_cp, *cp, **list;

        /*
         * Workaround for token acquisition and releases during the
         * console init.  For some reason if lwkt_gettoken()'s mpcount
         * optimization is turned off the console init blows up.  It
         * might be trying to kprintf() something in the middle of
         * its init.
         */
        lwkt_gettoken(&tty_token);

        /*
         * Check if we should mute the console (for security reasons perhaps)
         * It can be changes dynamically using sysctl kern.consmute
         * once we are up and going.
         *
         */
        cn_mute = ((boothowto & (RB_MUTE
                        |RB_SINGLE
                        |RB_VERBOSE
                        |RB_ASKNAME)) == RB_MUTE);

        /*
         * Find the first console with the highest priority.
         */
        best_cp = NULL;
        SET_FOREACH(list, cons_set) {
                cp = *list;
                if (cp->cn_probe == NULL)
                        continue;
                (*cp->cn_probe)(cp);
                if (cp->cn_pri > CN_DEAD && cp->cn_probegood &&
                    (best_cp == NULL || cp->cn_pri > best_cp->cn_pri))
                        best_cp = cp;
        }

        
        /*
         * If no console, give up.
         */
        if (best_cp == NULL) {
                if (cn_tab != NULL && cn_tab->cn_term != NULL)
                        (*cn_tab->cn_term)(cn_tab);
                goto done;
        }

        /*
         * Initialize console, then attach to it.  This ordering allows
         * debugging using the previous console, if any.
         */
        (*best_cp->cn_init)(best_cp);
        if (cn_tab != NULL && cn_tab != best_cp) {
                /* Turn off the previous console.  */
                if (cn_tab->cn_term != NULL)
                        (*cn_tab->cn_term)(cn_tab);
        }
        if (boothowto & RB_PAUSE)
                console_pausing = 1;
done:
        cn_tab = best_cp;

        /*
         * We can safely release the token after the init is done.
         * Also assert that the mpcount is still correct or otherwise
         * the SMP/AP boot will blow up on us.
         */
        lwkt_reltoken(&tty_token);
}


/*
 * Hook the open and close functions on the selected device.
 */
void
cninit_finish(void)
{
        if ((cn_tab == NULL) || cn_mute)
                return;
        if (cn_tab->cn_dev == NULL) {
                cn_tab->cn_init_fini(cn_tab);
                if (cn_tab->cn_dev == NULL) {
                        kprintf("Unable to hook console! cn_tab %p\n", cn_tab);
                        return;
                }
        }

        cn_fwd_ops = dev_ops_intercept(cn_tab->cn_dev, &cn_iops);
        cn_dev = cn_tab->cn_dev;
        if (cn_dev) {
                console_rdev = makeudev(cn_dev->si_umajor,
                                        (cn_dev->si_uminor == 255 ?
                                            0 : cn_dev->si_uminor));
        } else {
                console_rdev = 0;
        }
        console_pausing = 0;
}

static void
cnuninit(void)
{
        if (cn_tab == NULL)
                return;
        if (cn_fwd_ops)
                dev_ops_restore(cn_tab->cn_dev, cn_fwd_ops);
        cn_fwd_ops = NULL;
        cn_dev = NULL;
}


/*
 * User has changed the state of the console muting.
 * This may require us to open or close the device in question.
 */
static int
sysctl_kern_consmute(SYSCTL_HANDLER_ARGS)
{
        int error;
        int ocn_mute;

        ocn_mute = cn_mute;
        error = sysctl_handle_int(oidp, &cn_mute, 0, req);
        if((error == 0) && (cn_tab != NULL) && (req->newptr != NULL)) {
                if(ocn_mute && !cn_mute) {
                        /*
                         * going from muted to unmuted.. open the physical dev 
                         * if the console has been openned
                         */
                        cninit_finish();
                        if (cn_is_open) {
                                /* XXX curproc is not what we want really */
                                error = dev_dopen(cn_dev, openflag,
                                                openmode, curproc->p_ucred, NULL);
                        }
                        /* if it failed, back it out */
                        if ( error != 0) cnuninit();
                } else if (!ocn_mute && cn_mute) {
                        /*
                         * going from unmuted to muted.. close the physical dev 
                         * if it's only open via /dev/console
                         */
                        if (cn_is_open) {
                                error = dev_dclose(cn_dev, openflag,
                                                   openmode, NULL);
                        }
                        if (error == 0)
                                cnuninit();
                }
                if (error != 0) {
                        /* 
                         * back out the change if there was an error
                         */
                        cn_mute = ocn_mute;
                }
        }
        return (error);
}

SYSCTL_PROC(_kern, OID_AUTO, consmute, CTLTYPE_INT|CTLFLAG_RW,
        0, sizeof cn_mute, sysctl_kern_consmute, "I", "");


/*
 * We intercept the OPEN and CLOSE calls on the original device, and
 * forward the rest through.
 */
static int
cnintercept(struct dev_generic_args *ap)
{
        int error;

        if (ap->a_desc == &dev_open_desc) {
                error = cnopen((struct dev_open_args *)ap);
        } else if (ap->a_desc == &dev_close_desc) {
                error = cnclose((struct dev_close_args *)ap);
        } else if (cn_fwd_ops) {
                error = dev_doperate_ops(cn_fwd_ops, ap);
        } else {
                error = ENXIO;
        }
        return (error);
}

/*
 * cnopen() is called as an intercept function (dev will be that of the
 * actual physical device representing our console), and also called from
 * the muting code and from the /dev/console switch (dev will have the
 * console's cdevsw).
 */
static int
cnopen(struct dev_open_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        int flag = ap->a_oflags;
        int mode = ap->a_devtype;
        cdev_t cndev;
        cdev_t physdev;
        int retval = 0;

        if (cn_tab == NULL || cn_fwd_ops == NULL)
                return (0);

        cndev = cn_tab->cn_dev;         /* actual physical device */
        physdev = (dev == cn_devfsdev) ? cndev : dev;

        /*
         * If mute is active, then non console opens don't get here
         * so we don't need to check for that. They bypass this and go
         * straight to the device.
         *
         * It is important to note that due to our intercept and the fact
         * that we might be called via the original (intercepted) device,
         * the original device's ops may point to us, so to avoid an
         * infinite recursion we have to forward through cn_fwd_ops.
         * This is a severe hack that really needs to be fixed XXX.
         *
         * XXX at the moment we assume that the port forwarding function
         * is synchronous for open.
         */
        if (!cn_mute) {
                ap->a_head.a_dev = physdev;
                retval = dev_doperate_ops(cn_fwd_ops, &ap->a_head);
        }
        if (retval == 0) {
                /*
                 * check if we openned it via /dev/console or
                 * via the physical entry (e.g. /dev/sio0).
                 */
                if (dev == cndev) {
                        cn_phys_is_open = 1;
                } else if (physdev == cndev) {
                        openmode = mode;
                        openflag = flag;
                        cn_is_open = 1;
                }
                dev->si_tty = cndev->si_tty;
        }
        return (retval);
}

/*
 * cnclose() is called as a port intercept function (dev will be that of the
 * actual physical device representing our console), and also called from
 * the muting code and from the /dev/console switch (dev will have the
 * console's cdevsw).
 */
static int
cnclose(struct dev_close_args *ap)
{
        struct tty *cn_tp;
        cdev_t cndev;
        cdev_t physdev;
        cdev_t dev = ap->a_head.a_dev;

        if (cn_tab == NULL || cn_fwd_ops == NULL)
                return(0);
        cndev = cn_tab->cn_dev;
        cn_tp = cndev->si_tty;
        physdev = (dev == cn_devfsdev) ? cndev : dev;

        /*
         * act appropriatly depending on whether it's /dev/console
         * or the pysical device (e.g. /dev/sio) that's being closed.
         * in either case, don't actually close the device unless
         * both are closed.
         */
        if (dev == cndev) {
                /* the physical device is about to be closed */
                cn_phys_is_open = 0;
                if (cn_is_open) {
                        if (cn_tp) {
                                /* perform a ttyhalfclose() */
                                /* reset session and proc group */
                                ttyclearsession(cn_tp);
                        }
                        return(0);
                }
        } else if (physdev == cndev) {
                /* the logical console is about to be closed */
                cn_is_open = 0;
                if (cn_phys_is_open)
                        return(0);
                dev = cndev;
        }
        if (cn_fwd_ops) {
                ap->a_head.a_dev = dev;
                return (dev_doperate_ops(cn_fwd_ops, &ap->a_head));
        }
        return (0);
}

/*
 * The following functions are dispatched solely from the /dev/console
 * device.  Their job is primarily to forward the request through.
 * If the console is not attached to anything then write()'s are sunk
 * to null and reads return 0 (mostly).
 */
static int
cnread(struct dev_read_args *ap)
{
        if (cn_tab == NULL || cn_fwd_ops == NULL)
                return (0);
        ap->a_head.a_dev = cn_tab->cn_dev;
        return (dev_doperate(&ap->a_head));
}

static int
cnwrite(struct dev_write_args *ap)
{
        struct uio *uio = ap->a_uio;
        cdev_t dev;

        if (cn_tab == NULL || cn_fwd_ops == NULL) {
                uio->uio_resid = 0; /* dump the data */
                return (0);
        }
        if (constty)
                dev = constty->t_dev;
        else
                dev = cn_tab->cn_dev;
        log_console(uio);
        ap->a_head.a_dev = dev;
        return (dev_doperate(&ap->a_head));
}

static int
cnioctl(struct dev_ioctl_args *ap)
{
        int error;

        if (cn_tab == NULL || cn_fwd_ops == NULL)
                return (0);
        KKASSERT(curproc != NULL);
        /*
         * Superuser can always use this to wrest control of console
         * output from the "virtual" console.
         */
        if (ap->a_cmd == TIOCCONS && constty) {
                if (ap->a_cred) {
                        error = priv_check_cred(ap->a_cred, PRIV_ROOT, 0);
                        if (error)
                                return (error);
                }
                constty = NULL;
                return (0);
        }
        ap->a_head.a_dev = cn_tab->cn_dev;
        return (dev_doperate(&ap->a_head));
}

static int
cnkqfilter(struct dev_kqfilter_args *ap)
{
        if ((cn_tab == NULL) || cn_mute || cn_fwd_ops == NULL)
                return (1);
        ap->a_head.a_dev = cn_tab->cn_dev;
        return (dev_doperate(&ap->a_head));
}

/*
 * These synchronous functions are primarily used the kernel needs to 
 * access the keyboard (e.g. when running the debugger), or output data
 * directly to the console.
 */
int
cngetc(void)
{
        int c;
        if ((cn_tab == NULL) || cn_mute)
                return (-1);
        c = (*cn_tab->cn_getc)(cn_tab->cn_private);
        if (c == '\r') c = '\n'; /* console input is always ICRNL */
        return (c);
}

int
cncheckc(void)
{
        if ((cn_tab == NULL) || cn_mute)
                return (-1);
        return ((*cn_tab->cn_checkc)(cn_tab->cn_private));
}

void
cnpoll(int on)
{
        if ((cn_tab == NULL) || cn_mute)
                return;
        if (cn_tab->cn_poll)
                ((*cn_tab->cn_poll)(cn_tab->cn_private, on));
}

void
cnputc(int c)
{
        char *cp;

        if ((cn_tab == NULL) || cn_mute)
                return;
        if (c) {
                if (c == '\n')
                        (*cn_tab->cn_putc)(cn_tab->cn_private, '\r');
                (*cn_tab->cn_putc)(cn_tab->cn_private, c);
#ifdef DDB
                if (console_pausing && !db_active && (c == '\n')) {
#else
                if (console_pausing && (c == '\n')) {
#endif
                        for(cp=console_pausestr; *cp != '\0'; cp++)
                            (*cn_tab->cn_putc)(cn_tab->cn_private, *cp);
                        if (cngetc() == '.')
                                console_pausing = 0;
                        (*cn_tab->cn_putc)(cn_tab->cn_private, '\r');
                        for(cp=console_pausestr; *cp != '\0'; cp++)
                            (*cn_tab->cn_putc)(cn_tab->cn_private, ' ');
                        (*cn_tab->cn_putc)(cn_tab->cn_private, '\r');
                }
        }
}

void
cndbctl(int on)
{
        static int refcount;

        if (cn_tab == NULL)
                return;
        if (!on)
                refcount--;
        if (refcount == 0 && cn_tab->cn_dbctl != NULL)
                (*cn_tab->cn_dbctl)(cn_tab->cn_private, on);
        if (on)
                refcount++;
}

static void
cn_drvinit(void *unused)
{
        cn_devfsdev = make_only_devfs_dev(&cn_ops, 0, UID_ROOT, GID_WHEEL,
                                          0600, "console");
}

SYSINIT(cndev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE + CDEV_MAJOR, cn_drvinit, NULL);