kern_cons.c

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/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1991 The Regents of the University of California.
 * Copyright (c) 1999 Michael Smith
 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
 *
 * 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
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_ddb.h"
#include "opt_syscons.h"
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/fcntl.h>
#include <sys/kbio.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/msgbuf.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/reboot.h>
#include <sys/sysctl.h>
#include <sys/sbuf.h>
#include <sys/tty.h>
#include <sys/uio.h>
#include <sys/vnode.h>
 
#include <ddb/ddb.h>
 
#include <dev/kbd/kbdreg.h>
 
#include <machine/cpu.h>
#include <machine/clock.h>
 
static MALLOC_DEFINE(M_TTYCONS, "tty console", "tty console handling");
 
struct cn_device {
        STAILQ_ENTRY(cn_device) cnd_next;
        struct          consdev *cnd_cn;
};
 
#define CNDEVPATHMAX    32
#define CNDEVTAB_SIZE   4
static struct cn_device cn_devtab[CNDEVTAB_SIZE];
static STAILQ_HEAD(, cn_device) cn_devlist =
    STAILQ_HEAD_INITIALIZER(cn_devlist);
 
int     cons_avail_mask = 0;    /* Bit mask. Each registered low level console
                                 * which is currently unavailable for inpit
                                 * (i.e., if it is in graphics mode) will have
                                 * this bit cleared.
                                 */
 
static int cn_mute;
SYSCTL_INT(_kern, OID_AUTO, consmute, CTLFLAG_RW, &cn_mute, 0,
    "State of the console muting");
 
static char *consbuf;                   /* buffer used by `consmsgbuf' */
static struct callout conscallout;      /* callout for outputting to constty */
struct msgbuf consmsgbuf;               /* message buffer for console tty */
static bool console_pausing;            /* pause after each line during probe */
static const char console_pausestr[] =
"<pause; press any key to proceed to next line or '.' to end pause mode>";
struct tty *constty;                    /* pointer to console "window" tty */
static struct mtx constty_mtx;          /* Mutex for constty assignment. */
MTX_SYSINIT(constty_mtx, &constty_mtx, "constty_mtx", MTX_DEF);
static struct mtx cnputs_mtx;           /* Mutex for cnputs(). */
MTX_SYSINIT(cnputs_mtx, &cnputs_mtx, "cnputs_mtx", MTX_SPIN | MTX_NOWITNESS);
 
static void constty_timeout(void *arg);
 
static struct consdev cons_consdev;
DATA_SET(cons_set, cons_consdev);
SET_DECLARE(cons_set, struct consdev);
 
/*
 * Stub for configurations that don't actually have a keyboard driver. Inclusion
 * of kbd.c is contingent on any number of keyboard/console drivers being
 * present in the kernel; rather than trying to catch them all, we'll just
 * maintain this weak kbdinit that will be overridden by the strong version in
 * kbd.c if it's present.
 */
__weak_symbol void
kbdinit(void)
{
 
}
 
void
cninit(void)
{
        struct consdev *best_cn, *cn, **list;
 
        /*
         * 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);
 
        /*
         * Bring up the kbd layer just in time for cnprobe.  Console drivers
         * have a dependency on kbd being ready, so this fits nicely between the
         * machdep callers of cninit() and MI probing/initialization of consoles
         * here.
         */
        kbdinit();
 
        /*
         * Find the first console with the highest priority.
         */
        best_cn = NULL;
        SET_FOREACH(list, cons_set) {
                cn = *list;
                cnremove(cn);
                /* Skip cons_consdev. */
                if (cn->cn_ops == NULL)
                        continue;
                cn->cn_ops->cn_probe(cn);
                if (cn->cn_pri == CN_DEAD)
                        continue;
                if (best_cn == NULL || cn->cn_pri > best_cn->cn_pri)
                        best_cn = cn;
                if (boothowto & RB_MULTIPLE) {
                        /*
                         * Initialize console, and attach to it.
                         */
                        cn->cn_ops->cn_init(cn);
                        cnadd(cn);
                }
        }
        if (best_cn == NULL)
                return;
        if ((boothowto & RB_MULTIPLE) == 0) {
                best_cn->cn_ops->cn_init(best_cn);
                cnadd(best_cn);
        }
        if (boothowto & RB_PAUSE)
                console_pausing = true;
        /*
         * Make the best console the preferred console.
         */
        cnselect(best_cn);
 
#ifdef EARLY_PRINTF
        /*
         * Release early console.
         */
        early_putc = NULL;
#endif
}
 
void
cninit_finish()
{
        console_pausing = false;
} 
 
/* add a new physical console to back the virtual console */
int
cnadd(struct consdev *cn)
{
        struct cn_device *cnd;
        int i;
 
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next)
                if (cnd->cnd_cn == cn)
                        return (0);
        for (i = 0; i < CNDEVTAB_SIZE; i++) {
                cnd = &cn_devtab[i];
                if (cnd->cnd_cn == NULL)
                        break;
        }
        if (cnd->cnd_cn != NULL)
                return (ENOMEM);
        cnd->cnd_cn = cn;
        if (cn->cn_name[0] == '\0') {
                /* XXX: it is unclear if/where this print might output */
                printf("WARNING: console at %p has no name\n", cn);
        }
        STAILQ_INSERT_TAIL(&cn_devlist, cnd, cnd_next);
        if (STAILQ_FIRST(&cn_devlist) == cnd)
                ttyconsdev_select(cnd->cnd_cn->cn_name);
 
        /* Add device to the active mask. */
        cnavailable(cn, (cn->cn_flags & CN_FLAG_NOAVAIL) == 0);
 
        return (0);
}
 
void
cnremove(struct consdev *cn)
{
        struct cn_device *cnd;
        int i;
 
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                if (cnd->cnd_cn != cn)
                        continue;
                if (STAILQ_FIRST(&cn_devlist) == cnd)
                        ttyconsdev_select(NULL);
                STAILQ_REMOVE(&cn_devlist, cnd, cn_device, cnd_next);
                cnd->cnd_cn = NULL;
 
                /* Remove this device from available mask. */
                for (i = 0; i < CNDEVTAB_SIZE; i++) 
                        if (cnd == &cn_devtab[i]) {
                                cons_avail_mask &= ~(1 << i);
                                break;
                        }
#if 0
                /*
                 * XXX
                 * syscons gets really confused if console resources are
                 * freed after the system has initialized.
                 */
                if (cn->cn_term != NULL)
                        cn->cn_ops->cn_term(cn);
#endif
                return;
        }
}
 
void
cnselect(struct consdev *cn)
{
        struct cn_device *cnd;
 
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                if (cnd->cnd_cn != cn)
                        continue;
                if (cnd == STAILQ_FIRST(&cn_devlist))
                        return;
                STAILQ_REMOVE(&cn_devlist, cnd, cn_device, cnd_next);
                STAILQ_INSERT_HEAD(&cn_devlist, cnd, cnd_next);
                ttyconsdev_select(cnd->cnd_cn->cn_name);
                return;
        }
}
 
void
cnavailable(struct consdev *cn, int available)
{
        int i;
 
        for (i = 0; i < CNDEVTAB_SIZE; i++) {
                if (cn_devtab[i].cnd_cn == cn)
                        break;
        }
        if (available) {
                if (i < CNDEVTAB_SIZE)
                        cons_avail_mask |= (1 << i); 
                cn->cn_flags &= ~CN_FLAG_NOAVAIL;
        } else {
                if (i < CNDEVTAB_SIZE)
                        cons_avail_mask &= ~(1 << i);
                cn->cn_flags |= CN_FLAG_NOAVAIL;
        }
}
 
int
cnunavailable(void)
{
 
        return (cons_avail_mask == 0);
}
 
/*
 * sysctl_kern_console() provides output parseable in conscontrol(1).
 */
static int
sysctl_kern_console(SYSCTL_HANDLER_ARGS)
{
        struct cn_device *cnd;
        struct consdev *cp, **list;
        char *p;
        bool delete;
        int error;
        struct sbuf *sb;
 
        sb = sbuf_new(NULL, NULL, CNDEVPATHMAX * 2, SBUF_AUTOEXTEND |
            SBUF_INCLUDENUL);
        if (sb == NULL)
                return (ENOMEM);
        sbuf_clear(sb);
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next)
                sbuf_printf(sb, "%s,", cnd->cnd_cn->cn_name);
        sbuf_printf(sb, "/");
        SET_FOREACH(list, cons_set) {
                cp = *list;
                if (cp->cn_name[0] != '\0')
                        sbuf_printf(sb, "%s,", cp->cn_name);
        }
        sbuf_finish(sb);
        error = sysctl_handle_string(oidp, sbuf_data(sb), sbuf_len(sb), req);
        if (error == 0 && req->newptr != NULL) {
                p = sbuf_data(sb);
                error = ENXIO;
                delete = false;
                if (*p == '-') {
                        delete = true;
                        p++;
                }
                SET_FOREACH(list, cons_set) {
                        cp = *list;
                        if (strcmp(p, cp->cn_name) != 0)
                                continue;
                        if (delete) {
                                cnremove(cp);
                                error = 0;
                        } else {
                                error = cnadd(cp);
                                if (error == 0)
                                        cnselect(cp);
                        }
                        break;
                }
        }
        sbuf_delete(sb);
        return (error);
}
 
SYSCTL_PROC(_kern, OID_AUTO, console,
    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0,
    sysctl_kern_console, "A",
    "Console device control");
 
void
cngrab()
{
        struct cn_device *cnd;
        struct consdev *cn;
 
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                cn = cnd->cnd_cn;
                if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG))
                        cn->cn_ops->cn_grab(cn);
        }
}
 
void
cnungrab()
{
        struct cn_device *cnd;
        struct consdev *cn;
 
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                cn = cnd->cnd_cn;
                if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG))
                        cn->cn_ops->cn_ungrab(cn);
        }
}
 
void
cnresume()
{
        struct cn_device *cnd;
        struct consdev *cn;
 
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                cn = cnd->cnd_cn;
                if (cn->cn_ops->cn_resume != NULL)
                        cn->cn_ops->cn_resume(cn);
        }
}
 
/*
 * Low level console routines.
 */
int
cngetc(void)
{
        int c;
 
        if (cn_mute)
                return (-1);
        while ((c = cncheckc()) == -1)
                cpu_spinwait();
        if (c == '\r')
                c = '\n';               /* console input is always ICRNL */
        return (c);
}
 
int
cncheckc(void)
{
        struct cn_device *cnd;
        struct consdev *cn;
        int c;
 
        if (cn_mute)
                return (-1);
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                cn = cnd->cnd_cn;
                if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
                        c = cn->cn_ops->cn_getc(cn);
                        if (c != -1)
                                return (c);
                }
        }
        return (-1);
}
 
void
cngets(char *cp, size_t size, int visible)
{
        char *lp, *end;
        int c;
 
        cngrab();
 
        lp = cp;
        end = cp + size - 1;
        for (;;) {
                c = cngetc() & 0177;
                switch (c) {
                case '\n':
                case '\r':
                        cnputc(c);
                        *lp = '\0';
                        cnungrab();
                        return;
                case '\b':
                case '\177':
                        if (lp > cp) {
                                if (visible)
                                        cnputs("\b \b");
                                lp--;
                        }
                        continue;
                case '\0':
                        continue;
                default:
                        if (lp < end) {
                                switch (visible) {
                                case GETS_NOECHO:
                                        break;
                                case GETS_ECHOPASS:
                                        cnputc('*');
                                        break;
                                default:
                                        cnputc(c);
                                        break;
                                }
                                *lp++ = c;
                        }
                }
        }
}
 
void
cnputc(int c)
{
        struct cn_device *cnd;
        struct consdev *cn;
        const char *cp;
 
#ifdef EARLY_PRINTF
        if (early_putc != NULL) {
                if (c == '\n')
                        early_putc('\r');
                early_putc(c);
                return;
        }
#endif
 
        if (cn_mute || c == '\0')
                return;
        STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
                cn = cnd->cnd_cn;
                if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
                        if (c == '\n')
                                cn->cn_ops->cn_putc(cn, '\r');
                        cn->cn_ops->cn_putc(cn, c);
                }
        }
        if (console_pausing && c == '\n' && !kdb_active) {
                for (cp = console_pausestr; *cp != '\0'; cp++)
                        cnputc(*cp);
                cngrab();
                if (cngetc() == '.')
                        console_pausing = false;
                cnungrab();
                cnputc('\r');
                for (cp = console_pausestr; *cp != '\0'; cp++)
                        cnputc(' ');
                cnputc('\r');
        }
}
 
void
cnputsn(const char *p, size_t n)
{
        size_t i;
        bool unlock_reqd = false;
 
        if (mtx_initialized(&cnputs_mtx)) {
                /*
                 * NOTE: Debug prints and/or witness printouts in
                 * console driver clients can cause the "cnputs_mtx"
                 * mutex to recurse. Simply return if that happens.
                 */
                if (mtx_owned(&cnputs_mtx))
                        return;
                mtx_lock_spin(&cnputs_mtx);
                unlock_reqd = true;
        }
 
        for (i = 0; i < n; i++)
                cnputc(p[i]);
 
        if (unlock_reqd)
                mtx_unlock_spin(&cnputs_mtx);
}
 
void
cnputs(const char *p)
{
        cnputsn(p, strlen(p));
}
 
static unsigned int consmsgbuf_size = 65536;
SYSCTL_UINT(_kern, OID_AUTO, consmsgbuf_size, CTLFLAG_RWTUN, &consmsgbuf_size,
    0, "Console tty buffer size");
 
/*
 * Redirect console output to a tty.
 */
int
constty_set(struct tty *tp)
{
        int size = consmsgbuf_size;
        void *buf = NULL;
 
        tty_assert_locked(tp);
        if (constty == tp)
                return (0);
        if (constty != NULL)
                return (EBUSY);
 
        if (consbuf == NULL) {
                tty_unlock(tp);
                buf = malloc(size, M_TTYCONS, M_WAITOK);
                tty_lock(tp);
        }
        mtx_lock(&constty_mtx);
        if (constty != NULL) {
                mtx_unlock(&constty_mtx);
                free(buf, M_TTYCONS);
                return (EBUSY);
        }
        if (consbuf == NULL) {
                consbuf = buf;
                msgbuf_init(&consmsgbuf, buf, size);
        } else
                free(buf, M_TTYCONS);
        constty = tp;
        mtx_unlock(&constty_mtx);
 
        callout_init_mtx(&conscallout, tty_getlock(tp), 0);
        constty_timeout(tp);
        return (0);
}
 
/*
 * Disable console redirection to a tty.
 */
int
constty_clear(struct tty *tp)
{
        int c;
 
        tty_assert_locked(tp);
        if (constty != tp)
                return (ENXIO);
        callout_stop(&conscallout);
        mtx_lock(&constty_mtx);
        constty = NULL;
        mtx_unlock(&constty_mtx);
        while ((c = msgbuf_getchar(&consmsgbuf)) != -1)
                cnputc(c);
        /* We never free consbuf because it can still be in use. */
        return (0);
}
 
/* Times per second to check for pending console tty messages. */
static int constty_wakeups_per_second = 15;
SYSCTL_INT(_kern, OID_AUTO, constty_wakeups_per_second, CTLFLAG_RW,
    &constty_wakeups_per_second, 0,
    "Times per second to check for pending console tty messages");
 
static void
constty_timeout(void *arg)
{
        struct tty *tp = arg;
        int c;
 
        tty_assert_locked(tp);
        while ((c = msgbuf_getchar(&consmsgbuf)) != -1) {
                if (tty_putchar(tp, c) < 0) {
                        constty_clear(tp);
                        return;
                }
        }
        callout_reset_sbt(&conscallout, SBT_1S / constty_wakeups_per_second,
            0, constty_timeout, tp, C_PREL(1));
}
 
/*
 * Sysbeep(), if we have hardware for it
 */
 
#ifdef HAS_TIMER_SPKR
 
static bool beeping;
static struct callout beeping_timer;
 
static void
sysbeepstop(void *chan)
{
 
        timer_spkr_release();
        beeping = false;
}
 
int
sysbeep(int pitch, sbintime_t duration)
{
 
        if (timer_spkr_acquire()) {
                if (!beeping) {
                        /* Something else owns it. */
                        return (EBUSY);
                }
        }
        timer_spkr_setfreq(pitch);
        if (!beeping) {
                beeping = true;
                callout_reset_sbt(&beeping_timer, duration, 0, sysbeepstop,
                    NULL, C_PREL(5));
        }
        return (0);
}
 
static void
sysbeep_init(void *unused)
{
 
        callout_init(&beeping_timer, 1);
}
SYSINIT(sysbeep, SI_SUB_SOFTINTR, SI_ORDER_ANY, sysbeep_init, NULL);
#else
 
/*
 * No hardware, no sound
 */
 
int
sysbeep(int pitch __unused, sbintime_t duration __unused)
{
 
        return (ENODEV);
}
 
#endif
 
/*
 * Temporary support for sc(4) to vt(4) transition.
 */
static unsigned vty_prefer;
static char vty_name[16];
SYSCTL_STRING(_kern, OID_AUTO, vty, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, vty_name,
    0, "Console vty driver");
 
int
vty_enabled(unsigned vty)
{
        static unsigned vty_selected = 0;
 
        if (vty_selected == 0) {
                TUNABLE_STR_FETCH("kern.vty", vty_name, sizeof(vty_name));
                do {
#if defined(DEV_SC)
                        if (strcmp(vty_name, "sc") == 0) {
                                vty_selected = VTY_SC;
                                break;
                        }
#endif
#if defined(DEV_VT)
                        if (strcmp(vty_name, "vt") == 0) {
                                vty_selected = VTY_VT;
                                break;
                        }
#endif
                        if (vty_prefer != 0) {
                                vty_selected = vty_prefer;
                                break;
                        }
#if defined(DEV_VT)
                        vty_selected = VTY_VT;
#elif defined(DEV_SC)
                        vty_selected = VTY_SC;
#endif
                } while (0);
 
                if (vty_selected == VTY_VT)
                        strcpy(vty_name, "vt");
                else if (vty_selected == VTY_SC)
                        strcpy(vty_name, "sc");
        }
        return ((vty_selected & vty) != 0);
}
 
void
vty_set_preferred(unsigned vty)
{
 
        vty_prefer = vty;
#if !defined(DEV_SC)
        vty_prefer &= ~VTY_SC;
#endif
#if !defined(DEV_VT)
        vty_prefer &= ~VTY_VT;
#endif
}