common/mdb/mdb_module.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.
 * Copyright (c) 2012 by Delphix. All rights reserved.
 * Copyright (c) 2012 Joyent, Inc. All rights reserved.
 */

#include <sys/param.h>
#include <unistd.h>
#include <strings.h>
#include <dlfcn.h>
#include <link.h>

#include <mdb/mdb_module.h>
#include <mdb/mdb_modapi.h>
#include <mdb/mdb_ctf.h>
#include <mdb/mdb_debug.h>
#include <mdb/mdb_callb.h>
#include <mdb/mdb_string.h>
#include <mdb/mdb_ks.h>
#include <mdb/mdb_err.h>
#include <mdb/mdb_io.h>
#include <mdb/mdb_frame.h>
#include <mdb/mdb_whatis_impl.h>
#include <mdb/mdb.h>

/*
 * The format of an mdb dcmd changed between MDB_API_VERSION 3 and 4, with an
 * addition of a new field to the public interface. To maintain backwards
 * compatibility with older versions, we know to keep around the old version of
 * the structure so we can correctly read the set of dcmds passed in.
 */
typedef struct mdb_dcmd_v3 {
    const char *dco_name;       /* Command name */
    const char *dco_usage;      /* Usage message (optional) */
    const char *dco_descr;      /* Description */
    mdb_dcmd_f *dco_funcp;      /* Command function */
    void (*dco_help)(void);     /* Command help function (or NULL) */
} mdb_dcmd_v3_t;

/*
 * For builtin modules, we set mod_init to this function, which just
 * returns a constant modinfo struct with no dcmds and walkers.
 */
static const mdb_modinfo_t *
builtin_init(void)
{
    static const mdb_modinfo_t info = { MDB_API_VERSION };
    return (&info);
}

int
mdb_module_validate_name(const char *name, const char **errmsgp)
{
    if (strlen(name) == 0) {
        *errmsgp = "no module name was specified\n";
        return (0);
    }

    if (strlen(name) > MDB_NV_NAMELEN) {
        *errmsgp = "module name '%s' exceeds name length limit\n";
        return (0);
    }

    if (strbadid(name) != NULL) {
        *errmsgp = "module name '%s' contains illegal characters\n";
        return (0);
    }

    if (mdb_nv_lookup(&mdb.m_modules, name) != NULL) {
        *errmsgp = "%s module is already loaded\n";
        return (0);
    }

    return (1);
}

int
mdb_module_create(const char *name, const char *fname, int mode,
    mdb_module_t **mpp)
{
    static const mdb_walker_t empty_walk_list[] = { 0 };
    static const mdb_dcmd_t empty_dcmd_list[] = { 0 };

    int dlmode = (mode & MDB_MOD_GLOBAL) ? RTLD_GLOBAL : RTLD_LOCAL;

    const mdb_modinfo_t *info;
    const mdb_dcmd_t *dcp;
    const mdb_walker_t *wp;

    const mdb_dcmd_v3_t *dcop;
    mdb_dcmd_t *dctp = NULL;

    mdb_module_t *mod;

    mod = mdb_zalloc(sizeof (mdb_module_t), UM_SLEEP);
    mod->mod_info = mdb_alloc(sizeof (mdb_modinfo_t), UM_SLEEP);

    (void) mdb_nv_create(&mod->mod_dcmds, UM_SLEEP);
    (void) mdb_nv_create(&mod->mod_walkers, UM_SLEEP);

    mod->mod_name = strdup(name);
    mdb.m_lmod = mod;       /* Mark module as currently loading */

    if (!(mode & MDB_MOD_BUILTIN)) {
        mdb_dprintf(MDB_DBG_MODULE, "dlopen %s %x\n", fname, dlmode);
        mod->mod_hdl = dlmopen(LM_ID_BASE, fname, RTLD_NOW | dlmode);

        if (mod->mod_hdl == NULL) {
            warn("%s\n", dlerror());
            goto err;
        }

        mod->mod_init = (const mdb_modinfo_t *(*)(void))
            dlsym(mod->mod_hdl, "_mdb_init");

        mod->mod_fini = (void (*)(void))
            dlsym(mod->mod_hdl, "_mdb_fini");

        mod->mod_tgt_ctor = (mdb_tgt_ctor_f *)
            dlsym(mod->mod_hdl, "_mdb_tgt_create");

        mod->mod_dis_ctor = (mdb_dis_ctor_f *)
            dlsym(mod->mod_hdl, "_mdb_dis_create");

        if (!(mdb.m_flags & MDB_FL_NOCTF))
            mod->mod_ctfp = mdb_ctf_open(fname, NULL);
    } else {
#ifdef _KMDB
        /*
         * mdb_ks is a special case - a builtin with _mdb_init and
         * _mdb_fini routines.  If we don't hack it in here, we'll have
         * to duplicate most of the module creation code elsewhere.
         */
        if (strcmp(name, "mdb_ks") == 0)
            mod->mod_init = mdb_ks_init;
        else
#endif
            mod->mod_init = builtin_init;
    }

    if (mod->mod_init == NULL) {
        warn("%s module is missing _mdb_init definition\n", name);
        goto err;
    }

    if ((info = mod->mod_init()) == NULL) {
        warn("%s module failed to initialize\n", name);
        goto err;
    }

    /*
     * Reject modules compiled for a newer version of the debugger.
     */
    if (info->mi_dvers > MDB_API_VERSION) {
        warn("%s module requires newer mdb API version (%hu) than "
            "debugger (%d)\n", name, info->mi_dvers, MDB_API_VERSION);
        goto err;
    }

    /*
     * Load modules compiled for the current API version.
     */
    switch (info->mi_dvers) {
    case MDB_API_VERSION:
    case 3:
    case 2:
    case 1:
        /*
         * Current API version -- copy entire modinfo
         * structure into our own private storage.
         */
        bcopy(info, mod->mod_info, sizeof (mdb_modinfo_t));
        if (mod->mod_info->mi_dcmds == NULL)
            mod->mod_info->mi_dcmds = empty_dcmd_list;
        if (mod->mod_info->mi_walkers == NULL)
            mod->mod_info->mi_walkers = empty_walk_list;
        break;
    default:
        /*
         * Too old to be compatible -- abort the load.
         */
        warn("%s module is compiled for obsolete mdb API "
            "version %hu\n", name, info->mi_dvers);
        goto err;
    }

    /*
     * In MDB_API_VERSION 4, the size of the mdb_dcmd_t struct changed. If
     * our module is from an earlier version, we need to walk it in the old
     * structure and convert it to the new one.
     *
     * Note that we purposefully don't predicate on whether or not we have
     * the empty list case and duplicate it anyways. That case is rare and
     * it makes our logic simpler when we need to unload the module.
     */
    if (info->mi_dvers < 4) {
        int ii = 0;
        for (dcop = (mdb_dcmd_v3_t *)&mod->mod_info->mi_dcmds[0];
            dcop->dco_name != NULL; dcop++)
            ii++;
        /* Don't forget null terminated one at the end */
        dctp = mdb_zalloc(sizeof (mdb_dcmd_t) * (ii + 1), UM_SLEEP);
        ii = 0;
        for (dcop = (mdb_dcmd_v3_t *)&mod->mod_info->mi_dcmds[0];
            dcop->dco_name != NULL; dcop++, ii++) {
            dctp[ii].dc_name = dcop->dco_name;
            dctp[ii].dc_usage = dcop->dco_usage;
            dctp[ii].dc_descr = dcop->dco_descr;
            dctp[ii].dc_funcp = dcop->dco_funcp;
            dctp[ii].dc_help = dcop->dco_help;
            dctp[ii].dc_tabp = NULL;
        }
        mod->mod_info->mi_dcmds = dctp;
    }

    /*
     * Before we actually go ahead with the load, we need to check
     * each dcmd and walk structure for any invalid values:
     */
    for (dcp = &mod->mod_info->mi_dcmds[0]; dcp->dc_name != NULL; dcp++) {
        if (strbadid(dcp->dc_name) != NULL) {
            warn("dcmd name '%s' contains illegal characters\n",
                dcp->dc_name);
            goto err;
        }

        if (dcp->dc_descr == NULL) {
            warn("dcmd '%s' must have a description\n",
                dcp->dc_name);
            goto err;
        }

        if (dcp->dc_funcp == NULL) {
            warn("dcmd '%s' has a NULL function pointer\n",
                dcp->dc_name);
            goto err;
        }
    }

    for (wp = &mod->mod_info->mi_walkers[0]; wp->walk_name != NULL; wp++) {
        if (strbadid(wp->walk_name) != NULL) {
            warn("walk name '%s' contains illegal characters\n",
                wp->walk_name);
            goto err;
        }

        if (wp->walk_descr == NULL) {
            warn("walk '%s' must have a description\n",
                wp->walk_name);
            goto err;
        }

        if (wp->walk_step == NULL) {
            warn("walk '%s' has a NULL walk_step function\n",
                wp->walk_name);
            goto err;
        }
    }

    /*
     * Now that we've established that there are no problems,
     * we can go ahead and hash the module, and its dcmds and walks:
     */
    (void) mdb_nv_insert(&mdb.m_modules, mod->mod_name, NULL,
        (uintptr_t)mod, MDB_NV_RDONLY|MDB_NV_EXTNAME);

    for (dcp = &mod->mod_info->mi_dcmds[0]; dcp->dc_name != NULL; dcp++) {
        if (mdb_module_add_dcmd(mod, dcp, mode) == -1)
            warn("failed to load dcmd %s`%s", name, dcp->dc_name);
    }

    for (wp = &mod->mod_info->mi_walkers[0]; wp->walk_name != NULL; wp++) {
        if (mdb_module_add_walker(mod, wp, mode) == -1)
            warn("failed to load walk %s`%s", name, wp->walk_name);
    }

    /*
     * Add the module to the end of the list of modules in load-dependency
     * order.  We maintain this list so we can unload in reverse order.
     */
    if (mdb.m_mtail != NULL) {
        ASSERT(mdb.m_mtail->mod_next == NULL);
        mdb.m_mtail->mod_next = mod;
        mod->mod_prev = mdb.m_mtail;
        mdb.m_mtail = mod;
    } else {
        ASSERT(mdb.m_mhead == NULL);
        mdb.m_mtail = mdb.m_mhead = mod;
    }

    mdb.m_lmod = NULL;
    if (mpp != NULL)
        *mpp = mod;
    return (0);

err:
    mdb_whatis_unregister_module(mod);

    if (mod->mod_ctfp != NULL)
        ctf_close(mod->mod_ctfp);

    if (mod->mod_hdl != NULL)
        (void) dlclose(mod->mod_hdl);

    mdb_nv_destroy(&mod->mod_dcmds);
    mdb_nv_destroy(&mod->mod_walkers);

    strfree((char *)mod->mod_name);
    mdb_free(mod->mod_info, sizeof (mdb_modinfo_t));
    mdb_free(mod, sizeof (mdb_module_t));

    mdb.m_lmod = NULL;
    return (-1);
}

mdb_module_t *
mdb_module_load_builtin(const char *name)
{
    mdb_module_t *mp;

    if (mdb_module_create(name, NULL, MDB_MOD_BUILTIN, &mp) < 0)
        return (NULL);
    return (mp);
}

int
mdb_module_unload_common(const char *name)
{
    mdb_var_t *v = mdb_nv_lookup(&mdb.m_modules, name);
    mdb_module_t *mod;
    const mdb_dcmd_t *dcp;

    if (v == NULL)
        return (set_errno(EMDB_NOMOD));

    mod = mdb_nv_get_cookie(v);

    if (mod == &mdb.m_rmod || mod->mod_hdl == NULL)
        return (set_errno(EMDB_BUILTINMOD));

    mdb_dprintf(MDB_DBG_MODULE, "unloading %s\n", name);

    if (mod->mod_fini != NULL) {
        mdb_dprintf(MDB_DBG_MODULE, "calling %s`_mdb_fini\n", name);
        mod->mod_fini();
    }

    mdb_whatis_unregister_module(mod);

    if (mod->mod_ctfp != NULL)
        ctf_close(mod->mod_ctfp);

    if (mod->mod_cb != NULL)
        mdb_callb_remove_by_mod(mod);

    if (mod->mod_prev == NULL) {
        ASSERT(mdb.m_mhead == mod);
        mdb.m_mhead = mod->mod_next;
    } else
        mod->mod_prev->mod_next = mod->mod_next;

    if (mod->mod_next == NULL) {
        ASSERT(mdb.m_mtail == mod);
        mdb.m_mtail = mod->mod_prev;
    } else
        mod->mod_next->mod_prev = mod->mod_prev;

    while (mdb_nv_size(&mod->mod_walkers) != 0) {
        mdb_nv_rewind(&mod->mod_walkers);
        v = mdb_nv_peek(&mod->mod_walkers);
        (void) mdb_module_remove_walker(mod, mdb_nv_get_name(v));
    }

    while (mdb_nv_size(&mod->mod_dcmds) != 0) {
        mdb_nv_rewind(&mod->mod_dcmds);
        v = mdb_nv_peek(&mod->mod_dcmds);
        (void) mdb_module_remove_dcmd(mod, mdb_nv_get_name(v));
    }

    v = mdb_nv_lookup(&mdb.m_modules, name);
    ASSERT(v != NULL);
    mdb_nv_remove(&mdb.m_modules, v);

    (void) dlclose(mod->mod_hdl);

    mdb_nv_destroy(&mod->mod_walkers);
    mdb_nv_destroy(&mod->mod_dcmds);

    strfree((char *)mod->mod_name);

    if (mod->mod_info->mi_dvers < 4) {
        int ii = 0;

        for (dcp = &mod->mod_info->mi_dcmds[0]; dcp->dc_name != NULL;
            dcp++)
            ii++;

        mdb_free((void *)mod->mod_info->mi_dcmds,
            sizeof (mdb_dcmd_t) * (ii + 1));
    }

    mdb_free(mod->mod_info, sizeof (mdb_modinfo_t));
    mdb_free(mod, sizeof (mdb_module_t));

    return (0);
}

int
mdb_module_add_dcmd(mdb_module_t *mod, const mdb_dcmd_t *dcp, int flags)
{
    mdb_var_t *v = mdb_nv_lookup(&mod->mod_dcmds, dcp->dc_name);
    mdb_idcmd_t *idcp;

    uint_t nflag = MDB_NV_OVERLOAD | MDB_NV_SILENT;

    if (flags & MDB_MOD_FORCE)
        nflag |= MDB_NV_INTERPOS;

    if (v != NULL)
        return (set_errno(EMDB_DCMDEXISTS));

    idcp = mdb_alloc(sizeof (mdb_idcmd_t), UM_SLEEP);

    idcp->idc_usage = dcp->dc_usage;
    idcp->idc_descr = dcp->dc_descr;
    idcp->idc_help = dcp->dc_help;
    idcp->idc_funcp = dcp->dc_funcp;
    idcp->idc_tabp = dcp->dc_tabp;
    idcp->idc_modp = mod;

    v = mdb_nv_insert(&mod->mod_dcmds, dcp->dc_name, NULL,
        (uintptr_t)idcp, MDB_NV_SILENT | MDB_NV_RDONLY);

    idcp->idc_name = mdb_nv_get_name(v);
    idcp->idc_var = mdb_nv_insert(&mdb.m_dcmds, idcp->idc_name, NULL,
        (uintptr_t)v, nflag);

    mdb_dprintf(MDB_DBG_DCMD, "added dcmd %s`%s\n",
        mod->mod_name, idcp->idc_name);

    return (0);
}

int
mdb_module_remove_dcmd(mdb_module_t *mod, const char *dname)
{
    mdb_var_t *v = mdb_nv_lookup(&mod->mod_dcmds, dname);
    mdb_idcmd_t *idcp;
    mdb_cmd_t *cp;

    if (v == NULL)
        return (set_errno(EMDB_NODCMD));

    mdb_dprintf(MDB_DBG_DCMD, "removed dcmd %s`%s\n", mod->mod_name, dname);
    idcp = mdb_nv_get_cookie(v);

    /*
     * If we're removing a dcmd that is part of the most recent command,
     * we need to free mdb.m_lastcp so we don't attempt to execute some
     * text we've removed from our address space if -o repeatlast is set.
     */
    for (cp = mdb_list_next(&mdb.m_lastc); cp; cp = mdb_list_next(cp)) {
        if (cp->c_dcmd == idcp) {
            while ((cp = mdb_list_next(&mdb.m_lastc)) != NULL) {
                mdb_list_delete(&mdb.m_lastc, cp);
                mdb_cmd_destroy(cp);
            }
            break;
        }
    }

    mdb_nv_remove(&mdb.m_dcmds, idcp->idc_var);
    mdb_nv_remove(&mod->mod_dcmds, v);
    mdb_free(idcp, sizeof (mdb_idcmd_t));

    return (0);
}

/*ARGSUSED*/
static int
default_walk_init(mdb_walk_state_t *wsp)
{
    return (WALK_NEXT);
}

/*ARGSUSED*/
static void
default_walk_fini(mdb_walk_state_t *wsp)
{
    /* Nothing to do here */
}

int
mdb_module_add_walker(mdb_module_t *mod, const mdb_walker_t *wp, int flags)
{
    mdb_var_t *v = mdb_nv_lookup(&mod->mod_walkers, wp->walk_name);
    mdb_iwalker_t *iwp;

    uint_t nflag = MDB_NV_OVERLOAD | MDB_NV_SILENT;

    if (flags & MDB_MOD_FORCE)
        nflag |= MDB_NV_INTERPOS;

    if (v != NULL)
        return (set_errno(EMDB_WALKEXISTS));

    if (wp->walk_descr == NULL || wp->walk_step == NULL)
        return (set_errno(EINVAL));

    iwp = mdb_alloc(sizeof (mdb_iwalker_t), UM_SLEEP);

    iwp->iwlk_descr = strdup(wp->walk_descr);
    iwp->iwlk_init = wp->walk_init;
    iwp->iwlk_step = wp->walk_step;
    iwp->iwlk_fini = wp->walk_fini;
    iwp->iwlk_init_arg = wp->walk_init_arg;
    iwp->iwlk_modp = mod;

    if (iwp->iwlk_init == NULL)
        iwp->iwlk_init = default_walk_init;
    if (iwp->iwlk_fini == NULL)
        iwp->iwlk_fini = default_walk_fini;

    v = mdb_nv_insert(&mod->mod_walkers, wp->walk_name, NULL,
        (uintptr_t)iwp, MDB_NV_SILENT | MDB_NV_RDONLY);

    iwp->iwlk_name = mdb_nv_get_name(v);
    iwp->iwlk_var = mdb_nv_insert(&mdb.m_walkers, iwp->iwlk_name, NULL,
        (uintptr_t)v, nflag);

    mdb_dprintf(MDB_DBG_WALK, "added walk %s`%s\n",
        mod->mod_name, iwp->iwlk_name);

    return (0);
}

int
mdb_module_remove_walker(mdb_module_t *mod, const char *wname)
{
    mdb_var_t *v = mdb_nv_lookup(&mod->mod_walkers, wname);
    mdb_iwalker_t *iwp;

    if (v == NULL)
        return (set_errno(EMDB_NOWALK));

    mdb_dprintf(MDB_DBG_WALK, "removed walk %s`%s\n", mod->mod_name, wname);

    iwp = mdb_nv_get_cookie(v);
    mdb_nv_remove(&mdb.m_walkers, iwp->iwlk_var);
    mdb_nv_remove(&mod->mod_walkers, v);

    strfree(iwp->iwlk_descr);
    mdb_free(iwp, sizeof (mdb_iwalker_t));

    return (0);
}

void
mdb_module_unload_all(int mode)
{
    mdb_module_t *mod, *pmod;

    /*
     * We unload modules in the reverse order in which they were loaded
     * so as to allow _mdb_fini routines to invoke code which may be
     * present in a previously-loaded module (such as mdb_ks, etc.).
     */
    for (mod = mdb.m_mtail; mod != NULL; mod = pmod) {
        pmod =  mod->mod_prev;
        (void) mdb_module_unload(mod->mod_name, mode);
    }
}