kmdb/kctl/kctl_dmod.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Driver-side functions for loading and unloading dmods.
 */

#include <sys/types.h>
#include <sys/kobj.h>
#include <sys/kobj_impl.h>
#include <sys/modctl.h>
#include <sys/systm.h>
#include <sys/ctf_api.h>
#include <sys/kmdb.h>

#include <kmdb/kctl/kctl.h>
#include <kmdb/kctl/kctl_wr.h>
#include <kmdb/kmdb_wr_impl.h>
#include <kmdb/kmdb_kdi.h>
#include <mdb/mdb_errno.h>

struct modctl       *kdi_dmods;

/*
 * When a load is attempted, a check is first made of the modules on the
 * kctl_dmods list.  If a module is found, the load will not proceed.
 * kctl_dmods_lock must be held while traversing kctl_dmods, and while adding
 * to and subtracting from it.
 */
static struct modctl    kctl_dmods;
static kmutex_t     kctl_dmods_lock;

static kmdb_wr_path_t   *kctl_dmod_path;

/*
 * Used to track outstanding driver-initiated load notifications.  These
 * notifications have been allocated by driver, and thus must be freed by the
 * driver in the event of an emergency unload.  If we don't free them free
 * them ourselves, they'll leak.  Granted, the world is probably melting down
 * at that point, but there's no reason why we shouldn't tidy up the deck
 * chairs before we go.
 */
static kmdb_wr_load_t   *kctl_dmod_loads;
static kmutex_t     kctl_dmod_loads_lock;

static int
kctl_find_module(char *modname, char *fullname, size_t fullnamelen)
{
    intptr_t fd;
    int i;

    /* If they gave us an absolute path, we don't need to search */
    if (modname[0] == '/') {
        if (strlen(modname) + 1 > fullnamelen) {
            cmn_err(CE_WARN, "Can't load dmod %s - name too long",
                modname);
            return (0);
        }

        if ((fd = kobj_open(modname)) == -1)
            return (0);
        kobj_close(fd);

        (void) strcpy(fullname, modname);

        return (1);
    }

    for (i = 0; kctl_dmod_path->dpth_path[i] != NULL; i++) {
        const char *path = kctl_dmod_path->dpth_path[i];

        if (strlen(path) + 1 + strlen(modname) + 1 > fullnamelen) {
            kctl_dprintf("Can't load dmod from %s/%s - "
                "name too long", path, modname);
            continue;
        }

        (void) snprintf(fullname, fullnamelen, "%s/%s", path, modname);

        if ((fd = kobj_open(fullname)) == -1)
            continue;

        kobj_close(fd);

        kctl_dprintf("kobj_open %s found", fullname);

        /* Found it */
        return (1);
    }

    /* No luck */
    return (0);
}

static void
kctl_dlr_free(kmdb_wr_load_t *dlr)
{
    if (dlr->dlr_node.wn_flags & WNFLAGS_NOFREE)
        return;

    kctl_strfree(dlr->dlr_fname);
    kmem_free(dlr, sizeof (kmdb_wr_load_t));
}

int
kctl_dmod_load(kmdb_wr_load_t *dlr)
{
    struct modctl *modp;
    char modpath[MAXPATHLEN];
    const char *modname = kctl_basename(dlr->dlr_fname);
    int rc;

    mutex_enter(&kctl_dmods_lock);

    /* Have we already loaded this dmod? */
    for (modp = kctl_dmods.mod_next; modp != &kctl_dmods;
        modp = modp->mod_next) {
        if (strcmp(modname, modp->mod_modname) == 0) {
            mutex_exit(&kctl_dmods_lock);
            dlr->dlr_errno = EEXIST;
            return (-1);
        }
    }

    /*
     * If we find something that looks like a dmod, create a modctl for it,
     * and add said modctl to our dmods list.  This will allow us to drop
     * the dmods lock, while still preventing duplicate loads.  If we aren't
     * able to actually load the dmod, we can always remove the modctl
     * later.
     */
    if (!kctl_find_module(dlr->dlr_fname, modpath, sizeof (modpath))) {
        mutex_exit(&kctl_dmods_lock);
        dlr->dlr_errno = ENOENT;
        return (-1);
    }

    modp = kobj_zalloc(sizeof (struct modctl), KM_SLEEP);

    modp->mod_filename = kctl_strdup(modpath);
    modp->mod_modname = kctl_basename(modp->mod_filename);
    modp->mod_busy = 1;
    modp->mod_loadflags |= MOD_NOAUTOUNLOAD | MOD_NONOTIFY;
    modp->mod_next = &kctl_dmods;
    modp->mod_prev = kctl_dmods.mod_prev;
    modp->mod_prev->mod_next = modp;
    kctl_dmods.mod_prev = modp;

    mutex_exit(&kctl_dmods_lock);

    if (kctl.kctl_boot_ops == NULL)
        rc = kobj_load_module(modp, 0);
    else
        rc = kobj_load_primary_module(modp);

    if (rc != 0) {
        kctl_warn("failed to load dmod %s", modp->mod_modname);

        if (kctl.kctl_boot_ops == NULL)
            mod_release_requisites(modp);

        mutex_enter(&kctl_dmods_lock);
        modp->mod_next->mod_prev = modp->mod_prev;
        modp->mod_prev->mod_next = modp->mod_next;
        mutex_exit(&kctl_dmods_lock);

        kctl_strfree(modp->mod_filename);
        kobj_free(modp, sizeof (struct modctl));

        dlr->dlr_errno = EMDB_NOMOD;
        return (-1);
    }

    /*
     * It worked!  If the module has any CTF data, decompress it, and make a
     * note of the load.
     */
    mutex_enter(&mod_lock);
    if ((rc = kctl_mod_decompress(modp)) != 0) {
        kctl_warn("failed to decompress CTF data for dmod %s: %s",
            modpath, ctf_errmsg(rc));
    }
    mutex_exit(&mod_lock);

    kctl_dprintf("loaded dmod %s at %p", modpath, modp);

    modp->mod_ref = 1;
    modp->mod_loaded = 1;

    dlr->dlr_modctl = modp;

    return (0);
}

/*
 * Driver-initiated loads.  Load the module and announce it to the debugger.
 */
void
kctl_dmod_autoload(const char *fname)
{
    kmdb_wr_load_t *dlr;

    dlr = kobj_zalloc(sizeof (kmdb_wr_load_t), KM_SLEEP);
    dlr->dlr_node.wn_task = WNTASK_DMOD_LOAD;
    dlr->dlr_fname = kctl_strdup(fname);

    /*
     * If we're loading at boot, the kmdb_wr_load_t will have been
     * "allocated" by krtld, and will thus not be under the control of
     * kmem.  We need to ensure that we don't attempt to free it when
     * we get it back from the debugger.
     */
    if (kctl.kctl_boot_ops != NULL)
        dlr->dlr_node.wn_flags |= WNFLAGS_NOFREE;

    if (kctl_dmod_load(dlr) < 0) {
        kctl_dlr_free(dlr);
        return;
    }

    /*
     * Add to the list of open driver-initiated loads.  We need to track
     * these so we can free them (and thus avoid leaks) in the event that
     * the debugger needs to be blown away before it can return them.
     */
    mutex_enter(&kctl_dmod_loads_lock);
    dlr->dlr_next = kctl_dmod_loads;
    if (kctl_dmod_loads != NULL)
        kctl_dmod_loads->dlr_prev = dlr;
    kctl_dmod_loads = dlr;
    mutex_exit(&kctl_dmod_loads_lock);

    kmdb_wr_debugger_notify(dlr);
}

void
kctl_dmod_load_all(void)
{
    /*
     * The standard list of modules isn't populated until the tail end of
     * kobj_init().  Prior to that point, the only available list is that of
     * primaries.  We'll use that if the normal list isn't ready yet.
     */
    if (modules.mod_mp == NULL) {
        /* modules hasn't been initialized yet -- use primaries */
        struct modctl_list *ml;

        for (ml = kobj_linkmaps[KOBJ_LM_PRIMARY]; ml != NULL;
            ml = ml->modl_next)
            kctl_dmod_autoload(ml->modl_modp->mod_modname);

    } else {
        struct modctl *modp = &modules;

        do {
            if (modp->mod_mp != NULL)
                kctl_dmod_autoload(modp->mod_modname);
        } while ((modp = modp->mod_next) != &modules);
    }
}

void
kctl_dmod_load_ack(kmdb_wr_load_t *dlr)
{
    /* Remove from the list of open driver-initiated requests */
    mutex_enter(&kctl_dmod_loads_lock);
    if (dlr->dlr_prev == NULL)
        kctl_dmod_loads = dlr->dlr_next;
    else
        dlr->dlr_prev->dlr_next = dlr->dlr_next;

    if (dlr->dlr_next != NULL)
        dlr->dlr_next->dlr_prev = dlr->dlr_prev;
    mutex_exit(&kctl_dmod_loads_lock);

    kctl_dlr_free(dlr);
}

static int
kctl_dmod_unload_common(struct modctl *modp)
{
    struct modctl *m;

    kctl_dprintf("unloading dmod %s", modp->mod_modname);

    mutex_enter(&kctl_dmods_lock);
    for (m = kctl_dmods.mod_next; m != &kctl_dmods; m = m->mod_next) {
        if (m == modp)
            break;
    }
    mutex_exit(&kctl_dmods_lock);

    if (m != modp)
        return (ENOENT);

    /* Found it */
    modp->mod_ref = 0;
    modp->mod_loaded = 0;

    kobj_unload_module(modp);

    mod_release_requisites(modp);

    /* Remove it from our dmods list */
    mutex_enter(&kctl_dmods_lock);
    modp->mod_next->mod_prev = modp->mod_prev;
    modp->mod_prev->mod_next = modp->mod_next;
    mutex_exit(&kctl_dmods_lock);

    kctl_strfree(modp->mod_filename);
    kmem_free(modp, sizeof (struct modctl));

    return (0);
}

void
kctl_dmod_unload(kmdb_wr_unload_t *dur)
{
    int rc;

    if ((rc = kctl_dmod_unload_common(dur->dur_modctl)) != 0) {
        cmn_err(CE_WARN, "unexpected dmod unload failure: %d", rc);
        dur->dur_errno = rc;
    }
}

/*
 * This will be called during shutdown.  The debugger has been stopped, we're
 * off the module notification list, and we've already processed everything in
 * the driver's work queue.  We should have received (and processed) unload
 * requests for each of the dmods we've loaded.  To be safe, however, we'll
 * double-check.
 *
 * If we're doing an emergency shutdown, there may be outstanding
 * driver-initiated messages that haven't been returned to us.  The debugger is
 * dead, so it's not going to be returning them.  We'll leak them unless we
 * find and free them ourselves.
 */
void
kctl_dmod_unload_all(void)
{
    kmdb_wr_load_t *dlr;
    struct modctl *modp;

    while ((modp = kctl_dmods.mod_next) != &kctl_dmods)
        (void) kctl_dmod_unload_common(modp);

    while ((dlr = kctl_dmod_loads) != NULL) {
        kctl_dmod_loads = dlr->dlr_next;

        kctl_dprintf("freed orphan load notification for %s",
            dlr->dlr_fname);
        kctl_dlr_free(dlr);
    }
}

kmdb_wr_path_t *
kctl_dmod_path_set(kmdb_wr_path_t *pth)
{
    kmdb_wr_path_t *opth;

    if (kctl.kctl_flags & KMDB_F_DRV_DEBUG) {
        if (pth != NULL) {
            int i;
            kctl_dprintf("changing dmod path to: %p", pth);
            for (i = 0; pth->dpth_path[i] != NULL; i++)
                kctl_dprintf(" %s", pth->dpth_path[i]);
        } else {
            kctl_dprintf("changing dmod path to NULL");
        }
    }

    opth = kctl_dmod_path;
    kctl_dmod_path = pth;

    return (opth);
}

void
kctl_dmod_path_reset(void)
{
    kmdb_wr_path_t *pth;

    if ((pth = kctl_dmod_path_set(NULL)) != NULL) {
        WR_ACK(pth);
        kmdb_wr_debugger_notify(pth);
    }
}

void
kctl_dmod_sync(void)
{
    struct modctl *modp;

    /*
     * kobj_sync() has no visibility into our dmods, so we need to
     * explicitly tell krtld to export the portions of our dmods that were
     * allocated using boot scratch memory.
     */
    for (modp = kctl_dmods.mod_next; modp != &kctl_dmods;
        modp = modp->mod_next)
        kobj_export_module(modp->mod_mp);
}

void
kctl_dmod_init(void)
{
    mutex_init(&kctl_dmod_loads_lock, NULL, MUTEX_DRIVER, NULL);
    mutex_init(&kctl_dmods_lock, NULL, MUTEX_DRIVER, NULL);

    bzero(&kctl_dmods, sizeof (struct modctl));
    kctl_dmods.mod_next = kctl_dmods.mod_prev = &kctl_dmods;
    kdi_dmods = &kctl_dmods;
}

void
kctl_dmod_fini(void)
{
    mutex_destroy(&kctl_dmods_lock);
    mutex_destroy(&kctl_dmod_loads_lock);
    kdi_dmods = NULL;
}