/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1997-2000 Doug Rabson
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <sys/cdefs.h>
#include "opt_ddb.h"
#include "opt_kld.h"
#include "opt_hwpmc_hooks.h"
#include "opt_hwt_hooks.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/boottrace.h>
#include <sys/eventhandler.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/libkern.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/vnode.h>

#ifdef DDB
#include <ddb/ddb.h>
#endif

#include <net/vnet.h>

#include <security/mac/mac_framework.h>

#include "linker_if.h"

#if defined(HWPMC_HOOKS) || defined(HWT_HOOKS)
#include <sys/pmckern.h>
#endif

#ifdef KLD_DEBUG
int kld_debug = 0;
SYSCTL_INT(_debug, OID_AUTO, kld_debug, CTLFLAG_RWTUN,
    &kld_debug, 0, "Set various levels of KLD debug");
#endif

/* These variables are used by kernel debuggers to enumerate loaded files. */
const int kld_off_address = offsetof(struct linker_file, address);
const int kld_off_filename = offsetof(struct linker_file, filename);
const int kld_off_pathname = offsetof(struct linker_file, pathname);
const int kld_off_next = offsetof(struct linker_file, link.tqe_next);

/*
 * static char *linker_search_path(const char *name, struct mod_depend
 * *verinfo);
 */
static const char       *linker_basename(const char *path);

/*
 * Find a currently loaded file given its filename.
 */
static linker_file_t linker_find_file_by_name(const char* _filename);

/*
 * Find a currently loaded file given its file id.
 */
static linker_file_t linker_find_file_by_id(int _fileid);

/* Metadata from the static kernel */
SET_DECLARE(modmetadata_set, struct mod_metadata);

MALLOC_DEFINE(M_LINKER, "linker", "kernel linker");

linker_file_t linker_kernel_file;

static struct sx kld_sx;        /* kernel linker lock */
static u_int kld_busy;
static struct thread *kld_busy_owner;

/*
 * Load counter used by clients to determine if a linker file has been
 * re-loaded. This counter is incremented for each file load.
 */
static int loadcnt;

static linker_class_list_t classes;
static linker_file_list_t linker_files;
static int next_file_id = 1;
static int linker_no_more_classes = 0;

#define LINKER_GET_NEXT_FILE_ID(a) do {                                 \
        linker_file_t lftmp;                                            \
                                                                        \
        if (!cold)                                                      \
                sx_assert(&kld_sx, SA_XLOCKED);                         \
retry:                                                                  \
        TAILQ_FOREACH(lftmp, &linker_files, link) {                     \
                if (next_file_id == lftmp->id) {                        \
                        next_file_id++;                                 \
                        goto retry;                                     \
                }                                                       \
        }                                                               \
        (a) = next_file_id;                                             \
} while (0)

/* XXX wrong name; we're looking at version provision tags here, not modules */
typedef TAILQ_HEAD(, modlist) modlisthead_t;
struct modlist {
        TAILQ_ENTRY(modlist) link;      /* chain together all modules */
        linker_file_t   container;
        const char      *name;
        int             version;
};
typedef struct modlist *modlist_t;
static modlisthead_t found_modules;

static void     linker_file_add_dependency(linker_file_t file,
                    linker_file_t dep);
static caddr_t  linker_file_lookup_symbol_internal(linker_file_t file,
                    const char* name, int deps);
static int      linker_load_module(const char *kldname,
                    const char *modname, struct linker_file *parent,
                    const struct mod_depend *verinfo, struct linker_file **lfpp);
static modlist_t modlist_lookup2(const char *name, const struct mod_depend *verinfo);

static void
linker_init(void *arg)
{

        sx_init(&kld_sx, "kernel linker");
        TAILQ_INIT(&classes);
        TAILQ_INIT(&linker_files);
}

SYSINIT(linker, SI_SUB_KLD, SI_ORDER_FIRST, linker_init, NULL);

static void
linker_stop_class_add(void *arg)
{

        linker_no_more_classes = 1;
}

SYSINIT(linker_class, SI_SUB_KLD, SI_ORDER_ANY, linker_stop_class_add, NULL);

int
linker_add_class(linker_class_t lc)
{

        /*
         * We disallow any class registration past SI_ORDER_ANY
         * of SI_SUB_KLD.  We bump the reference count to keep the
         * ops from being freed.
         */
        if (linker_no_more_classes == 1)
                return (EPERM);
        kobj_class_compile((kobj_class_t) lc);
        ((kobj_class_t)lc)->refs++;     /* XXX: kobj_mtx */
        TAILQ_INSERT_TAIL(&classes, lc, link);
        return (0);
}

static void
linker_file_sysinit(linker_file_t lf)
{
        struct sysinit **start, **stop, **sipp, **xipp, *save;
        int last;

        KLD_DPF(FILE, ("linker_file_sysinit: calling SYSINITs for %s\n",
            lf->filename));

        sx_assert(&kld_sx, SA_XLOCKED);

        if (linker_file_lookup_set(lf, "sysinit_set", &start, &stop, NULL) != 0)
                return;
        /*
         * Perform a bubble sort of the system initialization objects by
         * their subsystem (primary key) and order (secondary key).
         *
         * Since some things care about execution order, this is the operation
         * which ensures continued function.
         */
        for (sipp = start; sipp < stop; sipp++) {
                for (xipp = sipp + 1; xipp < stop; xipp++) {
                        if ((*sipp)->subsystem < (*xipp)->subsystem ||
                            ((*sipp)->subsystem == (*xipp)->subsystem &&
                            (*sipp)->order <= (*xipp)->order))
                                continue;       /* skip */
                        save = *sipp;
                        *sipp = *xipp;
                        *xipp = save;
                }
        }

        /*
         * Traverse the (now) ordered list of system initialization tasks.
         * Perform each task, and continue on to the next task.
         */
        last = SI_SUB_DUMMY;
        sx_xunlock(&kld_sx);
        mtx_lock(&Giant);
        for (sipp = start; sipp < stop; sipp++) {
                if ((*sipp)->subsystem == SI_SUB_DUMMY)
                        continue;       /* skip dummy task(s) */

                if ((*sipp)->subsystem > last)
                        BOOTTRACE("%s: sysinit 0x%7x", lf->filename,
                            (*sipp)->subsystem);

                /* Call function */
                (*((*sipp)->func)) ((*sipp)->udata);
                last = (*sipp)->subsystem;
        }
        mtx_unlock(&Giant);
        sx_xlock(&kld_sx);
}

static void
linker_file_sysuninit(linker_file_t lf)
{
        struct sysinit **start, **stop, **sipp, **xipp, *save;
        int last;

        KLD_DPF(FILE, ("linker_file_sysuninit: calling SYSUNINITs for %s\n",
            lf->filename));

        sx_assert(&kld_sx, SA_XLOCKED);

        if (linker_file_lookup_set(lf, "sysuninit_set", &start, &stop,
            NULL) != 0)
                return;

        /*
         * Perform a reverse bubble sort of the system initialization objects
         * by their subsystem (primary key) and order (secondary key).
         *
         * Since some things care about execution order, this is the operation
         * which ensures continued function.
         */
        for (sipp = start; sipp < stop; sipp++) {
                for (xipp = sipp + 1; xipp < stop; xipp++) {
                        if ((*sipp)->subsystem > (*xipp)->subsystem ||
                            ((*sipp)->subsystem == (*xipp)->subsystem &&
                            (*sipp)->order >= (*xipp)->order))
                                continue;       /* skip */
                        save = *sipp;
                        *sipp = *xipp;
                        *xipp = save;
                }
        }

        /*
         * Traverse the (now) ordered list of system initialization tasks.
         * Perform each task, and continue on to the next task.
         */
        sx_xunlock(&kld_sx);
        mtx_lock(&Giant);
        last = SI_SUB_DUMMY;
        for (sipp = start; sipp < stop; sipp++) {
                if ((*sipp)->subsystem == SI_SUB_DUMMY)
                        continue;       /* skip dummy task(s) */

                if ((*sipp)->subsystem > last)
                        BOOTTRACE("%s: sysuninit 0x%7x", lf->filename,
                            (*sipp)->subsystem);

                /* Call function */
                (*((*sipp)->func)) ((*sipp)->udata);
                last = (*sipp)->subsystem;
        }
        mtx_unlock(&Giant);
        sx_xlock(&kld_sx);
}

static void
linker_file_register_sysctls(linker_file_t lf, bool enable)
{
        struct sysctl_oid **start, **stop, **oidp;

        KLD_DPF(FILE,
            ("linker_file_register_sysctls: registering SYSCTLs for %s\n",
            lf->filename));

        sx_assert(&kld_sx, SA_XLOCKED);

        if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
                return;

        sx_xunlock(&kld_sx);
        sysctl_wlock();
        for (oidp = start; oidp < stop; oidp++) {
                if (enable)
                        sysctl_register_oid(*oidp);
                else
                        sysctl_register_disabled_oid(*oidp);
        }
        sysctl_wunlock();
        sx_xlock(&kld_sx);
}

/*
 * Invoke the LINKER_CTF_GET implementation for this file.  Existing
 * implementations will load CTF info from the filesystem upon the first call
 * and cache it in the kernel thereafter.
 */
static void
linker_ctf_load_file(linker_file_t file)
{
        linker_ctf_t lc;
        int error;

        error = linker_ctf_get(file, &lc);
        if (error == 0)
                return;
        if (bootverbose) {
                printf("failed to load CTF for %s: %d\n", file->filename,
                    error);
        }
}

static void
linker_file_enable_sysctls(linker_file_t lf)
{
        struct sysctl_oid **start, **stop, **oidp;

        KLD_DPF(FILE,
            ("linker_file_enable_sysctls: enable SYSCTLs for %s\n",
            lf->filename));

        sx_assert(&kld_sx, SA_XLOCKED);

        if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
                return;

        sx_xunlock(&kld_sx);
        sysctl_wlock();
        for (oidp = start; oidp < stop; oidp++)
                sysctl_enable_oid(*oidp);
        sysctl_wunlock();
        sx_xlock(&kld_sx);
}

static void
linker_file_unregister_sysctls(linker_file_t lf)
{
        struct sysctl_oid **start, **stop, **oidp;

        KLD_DPF(FILE, ("linker_file_unregister_sysctls: unregistering SYSCTLs"
            " for %s\n", lf->filename));

        sx_assert(&kld_sx, SA_XLOCKED);

        if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
                return;

        sx_xunlock(&kld_sx);
        sysctl_wlock();
        for (oidp = start; oidp < stop; oidp++)
                sysctl_unregister_oid(*oidp);
        sysctl_wunlock();
        sx_xlock(&kld_sx);
}

static int
linker_file_register_modules(linker_file_t lf)
{
        struct mod_metadata **start, **stop, **mdp;
        const moduledata_t *moddata;
        int first_error, error;

        KLD_DPF(FILE, ("linker_file_register_modules: registering modules"
            " in %s\n", lf->filename));

        sx_assert(&kld_sx, SA_XLOCKED);

        if (linker_file_lookup_set(lf, MDT_SETNAME, &start, &stop, NULL) != 0) {
                /*
                 * This fallback should be unnecessary, but if we get booted
                 * from boot2 instead of loader and we are missing our
                 * metadata then we have to try the best we can.
                 */
                if (lf == linker_kernel_file) {
                        start = SET_BEGIN(modmetadata_set);
                        stop = SET_LIMIT(modmetadata_set);
                } else
                        return (0);
        }
        first_error = 0;
        for (mdp = start; mdp < stop; mdp++) {
                if ((*mdp)->md_type != MDT_MODULE)
                        continue;
                moddata = (*mdp)->md_data;
                KLD_DPF(FILE, ("Registering module %s in %s\n",
                    moddata->name, lf->filename));
                error = module_register(moddata, lf);
                if (error) {
                        printf("Module %s failed to register: %d\n",
                            moddata->name, error);
                        if (first_error == 0)
                                first_error = error;
                }
        }
        return (first_error);
}

static void
linker_init_kernel_modules(void *dummy __unused)
{

        sx_xlock(&kld_sx);
        linker_file_register_modules(linker_kernel_file);
        sx_xunlock(&kld_sx);
}

SYSINIT(linker_kernel, SI_SUB_KLD, SI_ORDER_ANY, linker_init_kernel_modules,
    NULL);

static int
linker_load_file(const char *filename, linker_file_t *result)
{
        linker_class_t lc;
        linker_file_t lf;
        int foundfile, error, modules;

        /* Refuse to load modules if securelevel raised */
        if (prison0.pr_securelevel > 0)
                return (EPERM);

        sx_assert(&kld_sx, SA_XLOCKED);
        lf = linker_find_file_by_name(filename);
        if (lf) {
                KLD_DPF(FILE, ("linker_load_file: file %s is already loaded,"
                    " incrementing refs\n", filename));
                *result = lf;
                lf->refs++;
                return (0);
        }
        foundfile = 0;
        error = 0;

        /*
         * We do not need to protect (lock) classes here because there is
         * no class registration past startup (SI_SUB_KLD, SI_ORDER_ANY)
         * and there is no class deregistration mechanism at this time.
         */
        TAILQ_FOREACH(lc, &classes, link) {
                KLD_DPF(FILE, ("linker_load_file: trying to load %s\n",
                    filename));
                error = LINKER_LOAD_FILE(lc, filename, &lf);
                /*
                 * If we got something other than ENOENT, then it exists but
                 * we cannot load it for some other reason.
                 */
                if (error != ENOENT) {
                        foundfile = 1;
                        if (error == EEXIST)
                                break;
                }
                if (lf) {
                        error = linker_file_register_modules(lf);
                        if (error == EEXIST) {
                                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
                                return (error);
                        }
                        modules = !TAILQ_EMPTY(&lf->modules);
                        linker_file_register_sysctls(lf, false);
#ifdef VIMAGE
                        LINKER_PROPAGATE_VNETS(lf);
#endif
                        linker_file_sysinit(lf);
                        lf->flags |= LINKER_FILE_LINKED;

                        /*
                         * If all of the modules in this file failed
                         * to load, unload the file and return an
                         * error of ENOEXEC.
                         */
                        if (modules && TAILQ_EMPTY(&lf->modules)) {
                                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
                                return (ENOEXEC);
                        }
                        linker_file_enable_sysctls(lf);

                        /*
                         * Ask the linker to load CTF data for this file.
                         */
                        linker_ctf_load_file(lf);
                        EVENTHANDLER_INVOKE(kld_load, lf);
                        *result = lf;
                        return (0);
                }
        }
        /*
         * Less than ideal, but tells the user whether it failed to load or
         * the module was not found.
         */
        if (foundfile) {
                /*
                 * If the file type has not been recognized by the last try
                 * printout a message before to fail.
                 */
                if (error == ENOSYS)
                        printf("%s: %s - unsupported file type\n",
                            __func__, filename);

                /*
                 * Format not recognized or otherwise unloadable.
                 * When loading a module that is statically built into
                 * the kernel EEXIST percolates back up as the return
                 * value.  Preserve this so that apps like sysinstall
                 * can recognize this special case and not post bogus
                 * dialog boxes.
                 */
                if (error != EEXIST)
                        error = ENOEXEC;
        } else
                error = ENOENT;         /* Nothing found */
        return (error);
}

int
linker_reference_module(const char *modname, struct mod_depend *verinfo,
    linker_file_t *result)
{
        modlist_t mod;
        int error;

        sx_xlock(&kld_sx);
        if ((mod = modlist_lookup2(modname, verinfo)) != NULL) {
                *result = mod->container;
                (*result)->refs++;
                sx_xunlock(&kld_sx);
                return (0);
        }

        error = linker_load_module(NULL, modname, NULL, verinfo, result);
        sx_xunlock(&kld_sx);
        return (error);
}

int
linker_release_module(const char *modname, struct mod_depend *verinfo,
    linker_file_t lf)
{
        modlist_t mod;
        int error;

        sx_xlock(&kld_sx);
        if (lf == NULL) {
                KASSERT(modname != NULL,
                    ("linker_release_module: no file or name"));
                mod = modlist_lookup2(modname, verinfo);
                if (mod == NULL) {
                        sx_xunlock(&kld_sx);
                        return (ESRCH);
                }
                lf = mod->container;
        } else
                KASSERT(modname == NULL && verinfo == NULL,
                    ("linker_release_module: both file and name"));
        error = linker_file_unload(lf, LINKER_UNLOAD_NORMAL);
        sx_xunlock(&kld_sx);
        return (error);
}

static linker_file_t
linker_find_file_by_name(const char *filename)
{
        linker_file_t lf;
        char *koname;

        koname = malloc(strlen(filename) + 4, M_LINKER, M_WAITOK);
        sprintf(koname, "%s.ko", filename);

        sx_assert(&kld_sx, SA_XLOCKED);
        TAILQ_FOREACH(lf, &linker_files, link) {
                if (strcmp(lf->filename, koname) == 0)
                        break;
                if (strcmp(lf->filename, filename) == 0)
                        break;
        }
        free(koname, M_LINKER);
        return (lf);
}

static linker_file_t
linker_find_file_by_id(int fileid)
{
        linker_file_t lf;

        sx_assert(&kld_sx, SA_XLOCKED);
        TAILQ_FOREACH(lf, &linker_files, link)
                if (lf->id == fileid && lf->flags & LINKER_FILE_LINKED)
                        break;
        return (lf);
}

int
linker_file_foreach(linker_predicate_t *predicate, void *context)
{
        linker_file_t lf;
        int retval = 0;

        sx_xlock(&kld_sx);
        TAILQ_FOREACH(lf, &linker_files, link) {
                retval = predicate(lf, context);
                if (retval != 0)
                        break;
        }
        sx_xunlock(&kld_sx);
        return (retval);
}

linker_file_t
linker_make_file(const char *pathname, linker_class_t lc)
{
        linker_file_t lf;
        const char *filename;

        if (!cold)
                sx_assert(&kld_sx, SA_XLOCKED);
        filename = linker_basename(pathname);

        KLD_DPF(FILE, ("linker_make_file: new file, filename='%s' for pathname='%s'\n", filename, pathname));
        lf = (linker_file_t)kobj_create((kobj_class_t)lc, M_LINKER, M_WAITOK);
        if (lf == NULL)
                return (NULL);
        lf->ctors_addr = 0;
        lf->ctors_size = 0;
        lf->ctors_invoked = LF_NONE;
        lf->dtors_addr = 0;
        lf->dtors_size = 0;
        lf->refs = 1;
        lf->userrefs = 0;
        lf->flags = 0;
        lf->filename = strdup(filename, M_LINKER);
        lf->pathname = strdup(pathname, M_LINKER);
        LINKER_GET_NEXT_FILE_ID(lf->id);
        lf->ndeps = 0;
        lf->deps = NULL;
        lf->loadcnt = ++loadcnt;
#ifdef __arm__
        lf->exidx_addr = 0;
        lf->exidx_size = 0;
#endif
        STAILQ_INIT(&lf->common);
        TAILQ_INIT(&lf->modules);
        TAILQ_INSERT_TAIL(&linker_files, lf, link);
        return (lf);
}

int
linker_file_unload(linker_file_t file, int flags)
{
        module_t mod, next;
        modlist_t ml, nextml;
        struct common_symbol *cp;
        int error, i;

        /* Refuse to unload modules if securelevel raised. */
        if (prison0.pr_securelevel > 0)
                return (EPERM);

        sx_assert(&kld_sx, SA_XLOCKED);
        KLD_DPF(FILE, ("linker_file_unload: lf->refs=%d\n", file->refs));

        /* Easy case of just dropping a reference. */
        if (file->refs > 1) {
                file->refs--;
                return (0);
        }

        /* Give eventhandlers a chance to prevent the unload. */
        error = 0;
        if ((file->flags & LINKER_FILE_LINKED) != 0) {
                EVENTHANDLER_INVOKE(kld_unload_try, file, &error);
                if (error != 0)
                        return (EBUSY);
        }

        KLD_DPF(FILE, ("linker_file_unload: file is unloading,"
            " informing modules\n"));

        /*
         * Quiesce all the modules to give them a chance to veto the unload.
         */
        MOD_SLOCK;
        for (mod = TAILQ_FIRST(&file->modules); mod;
             mod = module_getfnext(mod)) {
                error = module_quiesce(mod);
                if (error != 0 && flags != LINKER_UNLOAD_FORCE) {
                        KLD_DPF(FILE, ("linker_file_unload: module %s"
                            " vetoed unload\n", module_getname(mod)));
                        /*
                         * XXX: Do we need to tell all the quiesced modules
                         * that they can resume work now via a new module
                         * event?
                         */
                        MOD_SUNLOCK;
                        return (error);
                }
        }
        MOD_SUNLOCK;

        /*
         * Inform any modules associated with this file that they are
         * being unloaded.
         */
        MOD_XLOCK;
        for (mod = TAILQ_FIRST(&file->modules); mod; mod = next) {
                next = module_getfnext(mod);
                MOD_XUNLOCK;

                /*
                 * Give the module a chance to veto the unload.
                 */
                if ((error = module_unload(mod)) != 0) {
#ifdef KLD_DEBUG
                        MOD_SLOCK;
                        KLD_DPF(FILE, ("linker_file_unload: module %s"
                            " failed unload\n", module_getname(mod)));
                        MOD_SUNLOCK;
#endif
                        return (error);
                }
                MOD_XLOCK;
                module_release(mod);
        }
        MOD_XUNLOCK;

        TAILQ_FOREACH_SAFE(ml, &found_modules, link, nextml) {
                if (ml->container == file) {
                        TAILQ_REMOVE(&found_modules, ml, link);
                        free(ml, M_LINKER);
                }
        }

        /*
         * Don't try to run SYSUNINITs if we are unloaded due to a
         * link error.
         */
        if ((file->flags & LINKER_FILE_LINKED) != 0) {
                file->flags &= ~LINKER_FILE_LINKED;
                linker_file_unregister_sysctls(file);
                linker_file_sysuninit(file);
                EVENTHANDLER_INVOKE(kld_unload, file->filename, file->address,
                    file->size);
        }
        TAILQ_REMOVE(&linker_files, file, link);

        if (file->deps) {
                for (i = 0; i < file->ndeps; i++)
                        linker_file_unload(file->deps[i], flags);
                free(file->deps, M_LINKER);
                file->deps = NULL;
        }
        while ((cp = STAILQ_FIRST(&file->common)) != NULL) {
                STAILQ_REMOVE_HEAD(&file->common, link);
                free(cp, M_LINKER);
        }

        LINKER_UNLOAD(file);

        if (file->filename) {
                free(file->filename, M_LINKER);
                file->filename = NULL;
        }
        if (file->pathname) {
                free(file->pathname, M_LINKER);
                file->pathname = NULL;
        }
        kobj_delete((kobj_t) file, M_LINKER);
        return (0);
}

int
linker_ctf_get(linker_file_t file, linker_ctf_t *lc)
{
        return (LINKER_CTF_GET(file, lc));
}

int
linker_ctf_lookup_typename_ddb(linker_ctf_t *lc, const char *typename)
{
#ifdef DDB
        linker_file_t lf;

        TAILQ_FOREACH (lf, &linker_files, link){
                if (LINKER_CTF_LOOKUP_TYPENAME(lf, lc, typename) == 0)
                        return (0);
        }
#endif
        return (ENOENT);
}

int
linker_ctf_lookup_sym_ddb(const char *symname, c_linker_sym_t *sym,
    linker_ctf_t *lc)
{
#ifdef DDB
        linker_file_t lf;

        TAILQ_FOREACH (lf, &linker_files, link){
                if (LINKER_LOOKUP_DEBUG_SYMBOL_CTF(lf, symname, sym, lc) == 0)
                        return (0);
        }
#endif
        return (ENOENT);
}

static void
linker_file_add_dependency(linker_file_t file, linker_file_t dep)
{
        linker_file_t *newdeps;

        sx_assert(&kld_sx, SA_XLOCKED);
        file->deps = realloc(file->deps, (file->ndeps + 1) * sizeof(*newdeps),
            M_LINKER, M_WAITOK | M_ZERO);
        file->deps[file->ndeps] = dep;
        file->ndeps++;
        KLD_DPF(FILE, ("linker_file_add_dependency:"
            " adding %s as dependency for %s\n", 
            dep->filename, file->filename));
}

/*
 * Locate a linker set and its contents.  This is a helper function to avoid
 * linker_if.h exposure elsewhere.  Note: firstp and lastp are really void **.
 * This function is used in this file so we can avoid having lots of (void **)
 * casts.
 */
int
linker_file_lookup_set(linker_file_t file, const char *name,
    void *firstp, void *lastp, int *countp)
{

        sx_assert(&kld_sx, SA_LOCKED);
        return (LINKER_LOOKUP_SET(file, name, firstp, lastp, countp));
}

/*
 * List all functions in a file.
 */
int
linker_file_function_listall(linker_file_t lf,
    linker_function_nameval_callback_t callback_func, void *arg)
{
        return (LINKER_EACH_FUNCTION_NAMEVAL(lf, callback_func, arg));
}

caddr_t
linker_file_lookup_symbol(linker_file_t file, const char *name, int deps)
{
        caddr_t sym;
        int locked;

        locked = sx_xlocked(&kld_sx);
        if (!locked)
                sx_xlock(&kld_sx);
        sym = linker_file_lookup_symbol_internal(file, name, deps);
        if (!locked)
                sx_xunlock(&kld_sx);
        return (sym);
}

static caddr_t
linker_file_lookup_symbol_internal(linker_file_t file, const char *name,
    int deps)
{
        c_linker_sym_t sym;
        linker_symval_t symval;
        caddr_t address;
        size_t common_size = 0;
        int i;

        sx_assert(&kld_sx, SA_XLOCKED);
        KLD_DPF(SYM, ("linker_file_lookup_symbol: file=%p, name=%s, deps=%d\n",
            file, name, deps));

        /*
         * Treat the __this_linker_file as a special symbol. This is a
         * global that linuxkpi uses to populate the THIS_MODULE
         * value.  In this case we can simply return the linker_file_t.
         *
         * Modules compiled statically into the kernel are assigned NULL.
         */
        if (strcmp(name, "__this_linker_file") == 0) {
                address = (file == linker_kernel_file) ? NULL : (caddr_t)file;
                KLD_DPF(SYM, ("linker_file_lookup_symbol: resolving special "
                    "symbol __this_linker_file to %p\n", address));
                return (address);
        }

        if (LINKER_LOOKUP_SYMBOL(file, name, &sym) == 0) {
                LINKER_SYMBOL_VALUES(file, sym, &symval);
                if (symval.value == 0)
                        /*
                         * For commons, first look them up in the
                         * dependencies and only allocate space if not found
                         * there.
                         */
                        common_size = symval.size;
                else {
                        KLD_DPF(SYM, ("linker_file_lookup_symbol: symbol"
                            ".value=%p\n", symval.value));
                        return (symval.value);
                }
        }
        if (deps) {
                for (i = 0; i < file->ndeps; i++) {
                        address = linker_file_lookup_symbol_internal(
                            file->deps[i], name, 0);
                        if (address) {
                                KLD_DPF(SYM, ("linker_file_lookup_symbol:"
                                    " deps value=%p\n", address));
                                return (address);
                        }
                }
        }
        if (common_size > 0) {
                /*
                 * This is a common symbol which was not found in the
                 * dependencies.  We maintain a simple common symbol table in
                 * the file object.
                 */
                struct common_symbol *cp;

                STAILQ_FOREACH(cp, &file->common, link) {
                        if (strcmp(cp->name, name) == 0) {
                                KLD_DPF(SYM, ("linker_file_lookup_symbol:"
                                    " old common value=%p\n", cp->address));
                                return (cp->address);
                        }
                }
                /*
                 * Round the symbol size up to align.
                 */
                common_size = (common_size + sizeof(int) - 1) & -sizeof(int);
                cp = malloc(sizeof(struct common_symbol)
                    + common_size + strlen(name) + 1, M_LINKER,
                    M_WAITOK | M_ZERO);
                cp->address = (caddr_t)(cp + 1);
                cp->name = cp->address + common_size;
                strcpy(cp->name, name);
                bzero(cp->address, common_size);
                STAILQ_INSERT_TAIL(&file->common, cp, link);

                KLD_DPF(SYM, ("linker_file_lookup_symbol: new common"
                    " value=%p\n", cp->address));
                return (cp->address);
        }
        KLD_DPF(SYM, ("linker_file_lookup_symbol: fail\n"));
        return (0);
}

/*
 * Both DDB and stack(9) rely on the kernel linker to provide forward and
 * backward lookup of symbols.  However, DDB and sometimes stack(9) need to
 * do this in a lockfree manner.  We provide a set of internal helper
 * routines to perform these operations without locks, and then wrappers that
 * optionally lock.
 *
 * linker_debug_lookup() is ifdef DDB as currently it's only used by DDB.
 */
#ifdef DDB
static int
linker_debug_lookup(const char *symstr, c_linker_sym_t *sym)
{
        linker_file_t lf;

        TAILQ_FOREACH(lf, &linker_files, link) {
                if (LINKER_LOOKUP_DEBUG_SYMBOL(lf, symstr, sym) == 0)
                        return (0);
        }
        return (ENOENT);
}
#endif

static int
linker_debug_search_symbol(caddr_t value, c_linker_sym_t *sym, long *diffp)
{
        linker_file_t lf;
        c_linker_sym_t best, es;
        u_long diff, bestdiff, off;

        best = 0;
        off = (uintptr_t)value;
        bestdiff = off;
        TAILQ_FOREACH(lf, &linker_files, link) {
                if (LINKER_SEARCH_SYMBOL(lf, value, &es, &diff) != 0)
                        continue;
                if (es != 0 && diff < bestdiff) {
                        best = es;
                        bestdiff = diff;
                }
                if (bestdiff == 0)
                        break;
        }
        if (best) {
                *sym = best;
                *diffp = bestdiff;
                return (0);
        } else {
                *sym = 0;
                *diffp = off;
                return (ENOENT);
        }
}

static int
linker_debug_symbol_values(c_linker_sym_t sym, linker_symval_t *symval)
{
        linker_file_t lf;

        TAILQ_FOREACH(lf, &linker_files, link) {
                if (LINKER_DEBUG_SYMBOL_VALUES(lf, sym, symval) == 0)
                        return (0);
        }
        return (ENOENT);
}

static int
linker_debug_search_symbol_name(caddr_t value, char *buf, u_int buflen,
    long *offset)
{
        linker_symval_t symval;
        c_linker_sym_t sym;
        int error;

        *offset = 0;
        error = linker_debug_search_symbol(value, &sym, offset);
        if (error)
                return (error);
        error = linker_debug_symbol_values(sym, &symval);
        if (error)
                return (error);
        strlcpy(buf, symval.name, buflen);
        return (0);
}

/*
 * DDB Helpers.  DDB has to look across multiple files with their own symbol
 * tables and string tables.
 *
 * Note that we do not obey list locking protocols here.  We really don't need
 * DDB to hang because somebody's got the lock held.  We'll take the chance
 * that the files list is inconsistent instead.
 */
#ifdef DDB
int
linker_ddb_lookup(const char *symstr, c_linker_sym_t *sym)
{

        return (linker_debug_lookup(symstr, sym));
}
#endif

int
linker_ddb_search_symbol(caddr_t value, c_linker_sym_t *sym, long *diffp)
{

        return (linker_debug_search_symbol(value, sym, diffp));
}

int
linker_ddb_symbol_values(c_linker_sym_t sym, linker_symval_t *symval)
{

        return (linker_debug_symbol_values(sym, symval));
}

int
linker_ddb_search_symbol_name(caddr_t value, char *buf, u_int buflen,
    long *offset)
{

        return (linker_debug_search_symbol_name(value, buf, buflen, offset));
}

/*
 * stack(9) helper for non-debugging environemnts.  Unlike DDB helpers, we do
 * obey locking protocols, and offer a significantly less complex interface.
 */
int
linker_search_symbol_name_flags(caddr_t value, char *buf, u_int buflen,
    long *offset, int flags)
{
        int error;

        KASSERT((flags & (M_NOWAIT | M_WAITOK)) != 0 &&
            (flags & (M_NOWAIT | M_WAITOK)) != (M_NOWAIT | M_WAITOK),
            ("%s: bad flags: 0x%x", __func__, flags));

        if (flags & M_NOWAIT) {
                if (!sx_try_slock(&kld_sx))
                        return (EWOULDBLOCK);
        } else
                sx_slock(&kld_sx);

        error = linker_debug_search_symbol_name(value, buf, buflen, offset);
        sx_sunlock(&kld_sx);
        return (error);
}

int
linker_search_symbol_name(caddr_t value, char *buf, u_int buflen,
    long *offset)
{

        return (linker_search_symbol_name_flags(value, buf, buflen, offset,
            M_WAITOK));
}

int
linker_kldload_busy(int flags)
{
        int error;

        MPASS((flags & ~(LINKER_UB_UNLOCK | LINKER_UB_LOCKED |
            LINKER_UB_PCATCH)) == 0);
        if ((flags & LINKER_UB_LOCKED) != 0)
                sx_assert(&kld_sx, SA_XLOCKED);

        if ((flags & LINKER_UB_LOCKED) == 0)
                sx_xlock(&kld_sx);
        while (kld_busy > 0) {
                if (kld_busy_owner == curthread)
                        break;
                error = sx_sleep(&kld_busy, &kld_sx,
                    (flags & LINKER_UB_PCATCH) != 0 ? PCATCH : 0,
                    "kldbusy", 0);
                if (error != 0) {
                        if ((flags & LINKER_UB_UNLOCK) != 0)
                                sx_xunlock(&kld_sx);
                        return (error);
                }
        }
        kld_busy++;
        kld_busy_owner = curthread;
        if ((flags & LINKER_UB_UNLOCK) != 0)
                sx_xunlock(&kld_sx);
        return (0);
}

void
linker_kldload_unbusy(int flags)
{
        MPASS((flags & ~LINKER_UB_LOCKED) == 0);
        if ((flags & LINKER_UB_LOCKED) != 0)
                sx_assert(&kld_sx, SA_XLOCKED);

        if ((flags & LINKER_UB_LOCKED) == 0)
                sx_xlock(&kld_sx);
        MPASS(kld_busy > 0);
        if (kld_busy_owner != curthread)
                panic("linker_kldload_unbusy done by not owning thread %p",
                    kld_busy_owner);
        kld_busy--;
        if (kld_busy == 0) {
                kld_busy_owner = NULL;
                wakeup(&kld_busy);
        }
        sx_xunlock(&kld_sx);
}

/*
 * Syscalls.
 */
int
kern_kldload(struct thread *td, const char *file, int *fileid)
{
        const char *kldname, *modname;
        linker_file_t lf;
        int error;

        if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
                return (error);

        if ((error = priv_check(td, PRIV_KLD_LOAD)) != 0)
                return (error);

        /*
         * If file does not contain a qualified name or any dot in it
         * (kldname.ko, or kldname.ver.ko) treat it as an interface
         * name.
         */
        if (strchr(file, '/') || strchr(file, '.')) {
                kldname = file;
                modname = NULL;
        } else {
                kldname = NULL;
                modname = file;
        }

        error = linker_kldload_busy(LINKER_UB_PCATCH);
        if (error != 0) {
                sx_xunlock(&kld_sx);
                return (error);
        }

        /*
         * It is possible that kldloaded module will attach a new ifnet,
         * so vnet context must be set when this ocurs.
         */
        CURVNET_SET(TD_TO_VNET(td));

        error = linker_load_module(kldname, modname, NULL, NULL, &lf);
        CURVNET_RESTORE();

        if (error == 0) {
                lf->userrefs++;
                if (fileid != NULL)
                        *fileid = lf->id;
        }
        linker_kldload_unbusy(LINKER_UB_LOCKED);
        return (error);
}

int
sys_kldload(struct thread *td, struct kldload_args *uap)
{
        char *pathname = NULL;
        int error, fileid;

        td->td_retval[0] = -1;

        pathname = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
        error = copyinstr(uap->file, pathname, MAXPATHLEN, NULL);
        if (error == 0) {
                error = kern_kldload(td, pathname, &fileid);
                if (error == 0)
                        td->td_retval[0] = fileid;
        }
        free(pathname, M_TEMP);
        return (error);
}

int
kern_kldunload(struct thread *td, int fileid, int flags)
{
        linker_file_t lf;
        int error = 0;

        if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
                return (error);

        if ((error = priv_check(td, PRIV_KLD_UNLOAD)) != 0)
                return (error);

        error = linker_kldload_busy(LINKER_UB_PCATCH);
        if (error != 0) {
                sx_xunlock(&kld_sx);
                return (error);
        }

        CURVNET_SET(TD_TO_VNET(td));
        lf = linker_find_file_by_id(fileid);
        if (lf) {
                KLD_DPF(FILE, ("kldunload: lf->userrefs=%d\n", lf->userrefs));

                if (lf->userrefs == 0) {
                        /*
                         * XXX: maybe LINKER_UNLOAD_FORCE should override ?
                         */
                        printf("kldunload: attempt to unload file that was"
                            " loaded by the kernel\n");
                        error = EBUSY;
                } else if (lf->refs > 1) {
                        error = EBUSY;
                } else {
                        lf->userrefs--;
                        error = linker_file_unload(lf, flags);
                        if (error)
                                lf->userrefs++;
                }
        } else
                error = ENOENT;
        CURVNET_RESTORE();
        linker_kldload_unbusy(LINKER_UB_LOCKED);
        return (error);
}

int
sys_kldunload(struct thread *td, struct kldunload_args *uap)
{

        return (kern_kldunload(td, uap->fileid, LINKER_UNLOAD_NORMAL));
}

int
sys_kldunloadf(struct thread *td, struct kldunloadf_args *uap)
{

        if (uap->flags != LINKER_UNLOAD_NORMAL &&
            uap->flags != LINKER_UNLOAD_FORCE)
                return (EINVAL);
        return (kern_kldunload(td, uap->fileid, uap->flags));
}

int
sys_kldfind(struct thread *td, struct kldfind_args *uap)
{
        char *pathname;
        const char *filename;
        linker_file_t lf;
        int error;

#ifdef MAC
        error = mac_kld_check_stat(td->td_ucred);
        if (error)
                return (error);
#endif

        td->td_retval[0] = -1;

        pathname = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
        if ((error = copyinstr(uap->file, pathname, MAXPATHLEN, NULL)) != 0)
                goto out;

        filename = linker_basename(pathname);
        sx_xlock(&kld_sx);
        lf = linker_find_file_by_name(filename);
        if (lf)
                td->td_retval[0] = lf->id;
        else
                error = ENOENT;
        sx_xunlock(&kld_sx);
out:
        free(pathname, M_TEMP);
        return (error);
}

int
sys_kldnext(struct thread *td, struct kldnext_args *uap)
{
        linker_file_t lf;
        int error = 0;

#ifdef MAC
        error = mac_kld_check_stat(td->td_ucred);
        if (error)
                return (error);
#endif

        sx_xlock(&kld_sx);
        if (uap->fileid == 0)
                lf = TAILQ_FIRST(&linker_files);
        else {
                lf = linker_find_file_by_id(uap->fileid);
                if (lf == NULL) {
                        error = ENOENT;
                        goto out;
                }
                lf = TAILQ_NEXT(lf, link);
        }

        /* Skip partially loaded files. */
        while (lf != NULL && !(lf->flags & LINKER_FILE_LINKED))
                lf = TAILQ_NEXT(lf, link);

        if (lf)
                td->td_retval[0] = lf->id;
        else
                td->td_retval[0] = 0;
out:
        sx_xunlock(&kld_sx);
        return (error);
}

int
sys_kldstat(struct thread *td, struct kldstat_args *uap)
{
        struct kld_file_stat *stat;
        int error, version;

        /*
         * Check the version of the user's structure.
         */
        if ((error = copyin(&uap->stat->version, &version, sizeof(version)))
            != 0)
                return (error);
        if (version != sizeof(struct kld_file_stat_1) &&
            version != sizeof(struct kld_file_stat))
                return (EINVAL);

        stat = malloc(sizeof(*stat), M_TEMP, M_WAITOK | M_ZERO);
        error = kern_kldstat(td, uap->fileid, stat);
        if (error == 0)
                error = copyout(stat, uap->stat, version);
        free(stat, M_TEMP);
        return (error);
}

int
kern_kldstat(struct thread *td, int fileid, struct kld_file_stat *stat)
{
        linker_file_t lf;
        int namelen;
#ifdef MAC
        int error;

        error = mac_kld_check_stat(td->td_ucred);
        if (error)
                return (error);
#endif

        sx_xlock(&kld_sx);
        lf = linker_find_file_by_id(fileid);
        if (lf == NULL) {
                sx_xunlock(&kld_sx);
                return (ENOENT);
        }

        /* Version 1 fields: */
        namelen = strlen(lf->filename) + 1;
        if (namelen > sizeof(stat->name))
                namelen = sizeof(stat->name);
        bcopy(lf->filename, &stat->name[0], namelen);
        stat->refs = lf->refs;
        stat->id = lf->id;
        stat->address = lf->address;
        stat->size = lf->size;
        /* Version 2 fields: */
        namelen = strlen(lf->pathname) + 1;
        if (namelen > sizeof(stat->pathname))
                namelen = sizeof(stat->pathname);
        bcopy(lf->pathname, &stat->pathname[0], namelen);
        sx_xunlock(&kld_sx);

        td->td_retval[0] = 0;
        return (0);
}

#ifdef DDB
DB_COMMAND_FLAGS(kldstat, db_kldstat, DB_CMD_MEMSAFE)
{
        linker_file_t lf;

#define POINTER_WIDTH   ((int)(sizeof(void *) * 2 + 2))
        db_printf("Id Refs Address%*c Size     Name\n", POINTER_WIDTH - 7, ' ');
#undef  POINTER_WIDTH
        TAILQ_FOREACH(lf, &linker_files, link) {
                if (db_pager_quit)
                        return;
                db_printf("%2d %4d %p %-8zx %s\n", lf->id, lf->refs,
                    lf->address, lf->size, lf->filename);
        }
}
#endif /* DDB */

int
sys_kldfirstmod(struct thread *td, struct kldfirstmod_args *uap)
{
        linker_file_t lf;
        module_t mp;
        int error = 0;

#ifdef MAC
        error = mac_kld_check_stat(td->td_ucred);
        if (error)
                return (error);
#endif

        sx_xlock(&kld_sx);
        lf = linker_find_file_by_id(uap->fileid);
        if (lf) {
                MOD_SLOCK;
                mp = TAILQ_FIRST(&lf->modules);
                if (mp != NULL)
                        td->td_retval[0] = module_getid(mp);
                else
                        td->td_retval[0] = 0;
                MOD_SUNLOCK;
        } else
                error = ENOENT;
        sx_xunlock(&kld_sx);
        return (error);
}

int
sys_kldsym(struct thread *td, struct kldsym_args *uap)
{
        char *symstr = NULL;
        c_linker_sym_t sym;
        linker_symval_t symval;
        linker_file_t lf;
        struct kld_sym_lookup lookup;
        int error = 0;

#ifdef MAC
        error = mac_kld_check_stat(td->td_ucred);
        if (error)
                return (error);
#endif

        if ((error = copyin(uap->data, &lookup, sizeof(lookup))) != 0)
                return (error);
        if (lookup.version != sizeof(lookup) ||
            uap->cmd != KLDSYM_LOOKUP)
                return (EINVAL);
        symstr = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
        if ((error = copyinstr(lookup.symname, symstr, MAXPATHLEN, NULL)) != 0)
                goto out;
        sx_xlock(&kld_sx);
        if (uap->fileid != 0) {
                lf = linker_find_file_by_id(uap->fileid);
                if (lf == NULL)
                        error = ENOENT;
                else if (LINKER_LOOKUP_SYMBOL(lf, symstr, &sym) == 0 &&
                    LINKER_SYMBOL_VALUES(lf, sym, &symval) == 0) {
                        lookup.symvalue = (uintptr_t) symval.value;
                        lookup.symsize = symval.size;
                        error = copyout(&lookup, uap->data, sizeof(lookup));
                } else
                        error = ENOENT;
        } else {
                TAILQ_FOREACH(lf, &linker_files, link) {
                        if (LINKER_LOOKUP_SYMBOL(lf, symstr, &sym) == 0 &&
                            LINKER_SYMBOL_VALUES(lf, sym, &symval) == 0) {
                                lookup.symvalue = (uintptr_t)symval.value;
                                lookup.symsize = symval.size;
                                error = copyout(&lookup, uap->data,
                                    sizeof(lookup));
                                break;
                        }
                }
                if (lf == NULL)
                        error = ENOENT;
        }
        sx_xunlock(&kld_sx);
out:
        free(symstr, M_TEMP);
        return (error);
}

/*
 * Preloaded module support
 */

static modlist_t
modlist_lookup(const char *name, int ver)
{
        modlist_t mod;

        TAILQ_FOREACH(mod, &found_modules, link) {
                if (strcmp(mod->name, name) == 0 &&
                    (ver == 0 || mod->version == ver))
                        return (mod);
        }
        return (NULL);
}

static modlist_t
modlist_lookup2(const char *name, const struct mod_depend *verinfo)
{
        modlist_t mod, bestmod;
        int ver;

        if (verinfo == NULL)
                return (modlist_lookup(name, 0));
        bestmod = NULL;
        TAILQ_FOREACH(mod, &found_modules, link) {
                if (strcmp(mod->name, name) != 0)
                        continue;
                ver = mod->version;
                if (ver == verinfo->md_ver_preferred)
                        return (mod);
                if (ver >= verinfo->md_ver_minimum &&
                    ver <= verinfo->md_ver_maximum &&
                    (bestmod == NULL || ver > bestmod->version))
                        bestmod = mod;
        }
        return (bestmod);
}

static modlist_t
modlist_newmodule(const char *modname, int version, linker_file_t container)
{
        modlist_t mod;

        mod = malloc(sizeof(struct modlist), M_LINKER, M_NOWAIT | M_ZERO);
        if (mod == NULL)
                panic("no memory for module list");
        mod->container = container;
        mod->name = modname;
        mod->version = version;
        TAILQ_INSERT_TAIL(&found_modules, mod, link);
        return (mod);
}

static void
linker_addmodules(linker_file_t lf, struct mod_metadata **start,
    struct mod_metadata **stop, int preload)
{
        struct mod_metadata *mp, **mdp;
        const char *modname;
        int ver;

        for (mdp = start; mdp < stop; mdp++) {
                mp = *mdp;
                if (mp->md_type != MDT_VERSION)
                        continue;
                modname = mp->md_cval;
                ver = ((const struct mod_version *)mp->md_data)->mv_version;
                if (modlist_lookup(modname, ver) != NULL) {
                        printf("module %s already present!\n", modname);
                        /* XXX what can we do? this is a build error. :-( */
                        continue;
                }
                modlist_newmodule(modname, ver, lf);
        }
}

static void
linker_preload(void *arg)
{
        caddr_t modptr;
        const char *modname, *nmodname;
        char *modtype;
        linker_file_t lf, nlf;
        linker_class_t lc;
        int error;
        linker_file_list_t loaded_files;
        linker_file_list_t depended_files;
        struct mod_metadata *mp, *nmp;
        struct mod_metadata **start, **stop, **mdp, **nmdp;
        const struct mod_depend *verinfo;
        int nver;
        int resolves;
        modlist_t mod;
        struct sysinit **si_start, **si_stop;

        TAILQ_INIT(&loaded_files);
        TAILQ_INIT(&depended_files);
        TAILQ_INIT(&found_modules);
        error = 0;

        modptr = NULL;
        sx_xlock(&kld_sx);
        while ((modptr = preload_search_next_name(modptr)) != NULL) {
                modname = (char *)preload_search_info(modptr, MODINFO_NAME);
                modtype = (char *)preload_search_info(modptr, MODINFO_TYPE);
                if (modname == NULL) {
                        printf("Preloaded module at %p does not have a"
                            " name!\n", modptr);
                        continue;
                }
                if (modtype == NULL) {
                        printf("Preloaded module at %p does not have a type!\n",
                            modptr);
                        continue;
                }
                if (bootverbose)
                        printf("Preloaded %s \"%s\" at %p.\n", modtype, modname,
                            modptr);
                lf = NULL;
                TAILQ_FOREACH(lc, &classes, link) {
                        error = LINKER_LINK_PRELOAD(lc, modname, &lf);
                        if (!error)
                                break;
                        lf = NULL;
                }
                if (lf)
                        TAILQ_INSERT_TAIL(&loaded_files, lf, loaded);
        }

        /*
         * First get a list of stuff in the kernel.
         */
        if (linker_file_lookup_set(linker_kernel_file, MDT_SETNAME, &start,
            &stop, NULL) == 0)
                linker_addmodules(linker_kernel_file, start, stop, 1);

        /*
         * This is a once-off kinky bubble sort to resolve relocation
         * dependency requirements.
         */
restart:
        TAILQ_FOREACH(lf, &loaded_files, loaded) {
                error = linker_file_lookup_set(lf, MDT_SETNAME, &start,
                    &stop, NULL);
                /*
                 * First, look to see if we would successfully link with this
                 * stuff.
                 */
                resolves = 1;   /* unless we know otherwise */
                if (!error) {
                        for (mdp = start; mdp < stop; mdp++) {
                                mp = *mdp;
                                if (mp->md_type != MDT_DEPEND)
                                        continue;
                                modname = mp->md_cval;
                                verinfo = mp->md_data;
                                for (nmdp = start; nmdp < stop; nmdp++) {
                                        nmp = *nmdp;
                                        if (nmp->md_type != MDT_VERSION)
                                                continue;
                                        nmodname = nmp->md_cval;
                                        if (strcmp(modname, nmodname) == 0)
                                                break;
                                }
                                if (nmdp < stop)   /* it's a self reference */
                                        continue;

                                /*
                                 * ok, the module isn't here yet, we
                                 * are not finished
                                 */
                                if (modlist_lookup2(modname, verinfo) == NULL)
                                        resolves = 0;
                        }
                }
                /*
                 * OK, if we found our modules, we can link.  So, "provide"
                 * the modules inside and add it to the end of the link order
                 * list.
                 */
                if (resolves) {
                        if (!error) {
                                for (mdp = start; mdp < stop; mdp++) {
                                        mp = *mdp;
                                        if (mp->md_type != MDT_VERSION)
                                                continue;
                                        modname = mp->md_cval;
                                        nver = ((const struct mod_version *)
                                            mp->md_data)->mv_version;
                                        if (modlist_lookup(modname,
                                            nver) != NULL) {
                                                printf("module %s already"
                                                    " present!\n", modname);
                                                TAILQ_REMOVE(&loaded_files,
                                                    lf, loaded);
                                                linker_file_unload(lf,
                                                    LINKER_UNLOAD_FORCE);
                                                /* we changed tailq next ptr */
                                                goto restart;
                                        }
                                        modlist_newmodule(modname, nver, lf);
                                }
                        }
                        TAILQ_REMOVE(&loaded_files, lf, loaded);
                        TAILQ_INSERT_TAIL(&depended_files, lf, loaded);
                        /*
                         * Since we provided modules, we need to restart the
                         * sort so that the previous files that depend on us
                         * have a chance. Also, we've busted the tailq next
                         * pointer with the REMOVE.
                         */
                        goto restart;
                }
        }

        /*
         * At this point, we check to see what could not be resolved..
         */
        while ((lf = TAILQ_FIRST(&loaded_files)) != NULL) {
                TAILQ_REMOVE(&loaded_files, lf, loaded);
                printf("KLD file %s is missing dependencies\n", lf->filename);
                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
        }

        /*
         * We made it. Finish off the linking in the order we determined.
         */
        TAILQ_FOREACH_SAFE(lf, &depended_files, loaded, nlf) {
                if (linker_kernel_file) {
                        linker_kernel_file->refs++;
                        linker_file_add_dependency(lf, linker_kernel_file);
                }
                error = linker_file_lookup_set(lf, MDT_SETNAME, &start,
                    &stop, NULL);
                if (!error) {
                        for (mdp = start; mdp < stop; mdp++) {
                                mp = *mdp;
                                if (mp->md_type != MDT_DEPEND)
                                        continue;
                                modname = mp->md_cval;
                                verinfo = mp->md_data;
                                mod = modlist_lookup2(modname, verinfo);
                                if (mod == NULL) {
                                        printf("KLD file %s - cannot find "
                                            "dependency \"%s\"\n",
                                            lf->filename, modname);
                                        goto fail;
                                }
                                /* Don't count self-dependencies */
                                if (lf == mod->container)
                                        continue;
                                mod->container->refs++;
                                linker_file_add_dependency(lf, mod->container);
                        }
                }
                /*
                 * Now do relocation etc using the symbol search paths
                 * established by the dependencies
                 */
                error = LINKER_LINK_PRELOAD_FINISH(lf);
                if (error) {
                        printf("KLD file %s - could not finalize loading\n",
                            lf->filename);
                        goto fail;
                }
                linker_file_register_modules(lf);
                if (!TAILQ_EMPTY(&lf->modules))
                        lf->flags |= LINKER_FILE_MODULES;
                if (linker_file_lookup_set(lf, "sysinit_set", &si_start,
                    &si_stop, NULL) == 0)
                        sysinit_add(si_start, si_stop);
                linker_file_register_sysctls(lf, true);
                lf->flags |= LINKER_FILE_LINKED;
                continue;
fail:
                TAILQ_REMOVE(&depended_files, lf, loaded);
                linker_file_unload(lf, LINKER_UNLOAD_FORCE);
        }
        sx_xunlock(&kld_sx);
        /* woohoo! we made it! */
}
SYSINIT(preload, SI_SUB_KLD, SI_ORDER_MIDDLE, linker_preload, NULL);

static void
linker_mountroot(void *arg __unused)
{
        linker_file_t lf;

        sx_xlock(&kld_sx);
        TAILQ_FOREACH (lf, &linker_files, link) {
                linker_ctf_load_file(lf);
        }
        sx_xunlock(&kld_sx);
}
EVENTHANDLER_DEFINE(mountroot, linker_mountroot, NULL, 0);

/*
 * Handle preload files that failed to load any modules.
 */
static void
linker_preload_finish(void *arg)
{
        linker_file_t lf, nlf;

        sx_xlock(&kld_sx);
        TAILQ_FOREACH_SAFE(lf, &linker_files, link, nlf) {
                if (lf == linker_kernel_file)
                        continue;

                /*
                 * If all of the modules in this file failed to load, unload
                 * the file and return an error of ENOEXEC.  (Parity with
                 * linker_load_file.)
                 */
                if ((lf->flags & LINKER_FILE_MODULES) != 0 &&
                    TAILQ_EMPTY(&lf->modules)) {
                        linker_file_unload(lf, LINKER_UNLOAD_FORCE);
                        continue;
                }

                lf->flags &= ~LINKER_FILE_MODULES;
                lf->userrefs++; /* so we can (try to) kldunload it */
        }
        sx_xunlock(&kld_sx);
}

/*
 * Attempt to run after all DECLARE_MODULE SYSINITs.  Unfortunately they can be
 * scheduled at any subsystem and order, so run this as late as possible.  init
 * becomes runnable in SI_SUB_KTHREAD_INIT, so go slightly before that.
 */
SYSINIT(preload_finish, SI_SUB_KTHREAD_INIT - 100, SI_ORDER_MIDDLE,
    linker_preload_finish, NULL);

/*
 * Search for a not-loaded module by name.
 *
 * Modules may be found in the following locations:
 *
 * - preloaded (result is just the module name) - on disk (result is full path
 * to module)
 *
 * If the module name is qualified in any way (contains path, etc.) the we
 * simply return a copy of it.
 *
 * The search path can be manipulated via sysctl.  Note that we use the ';'
 * character as a separator to be consistent with the bootloader.
 */

static char linker_hintfile[] = "linker.hints";
static char linker_path[MAXPATHLEN] = "/boot/kernel;/boot/modules";

SYSCTL_STRING(_kern, OID_AUTO, module_path, CTLFLAG_RWTUN, linker_path,
    sizeof(linker_path), "module load search path");

TUNABLE_STR("module_path", linker_path, sizeof(linker_path));

static const char * const linker_ext_list[] = {
        "",
        ".ko",
        NULL
};

/*
 * Check if file actually exists either with or without extension listed in
 * the linker_ext_list. (probably should be generic for the rest of the
 * kernel)
 */
static char *
linker_lookup_file(const char *path, int pathlen, const char *name,
    int namelen, struct vattr *vap)
{
        struct nameidata nd;
        struct thread *td = curthread;  /* XXX */
        const char * const *cpp, *sep;
        char *result;
        int error, len, extlen, reclen, flags;
        __enum_uint8(vtype) type;

        extlen = 0;
        for (cpp = linker_ext_list; *cpp; cpp++) {
                len = strlen(*cpp);
                if (len > extlen)
                        extlen = len;
        }
        extlen++;               /* trailing '\0' */
        sep = (path[pathlen - 1] != '/') ? "/" : "";

        reclen = pathlen + strlen(sep) + namelen + extlen + 1;
        result = malloc(reclen, M_LINKER, M_WAITOK);
        for (cpp = linker_ext_list; *cpp; cpp++) {
                snprintf(result, reclen, "%.*s%s%.*s%s", pathlen, path, sep,
                    namelen, name, *cpp);
                /*
                 * Attempt to open the file, and return the path if
                 * we succeed and it's a regular file.
                 */
                NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, result);
                flags = FREAD;
                error = vn_open(&nd, &flags, 0, NULL);
                if (error == 0) {
                        NDFREE_PNBUF(&nd);
                        type = nd.ni_vp->v_type;
                        if (vap)
                                VOP_GETATTR(nd.ni_vp, vap, td->td_ucred);
                        VOP_UNLOCK(nd.ni_vp);
                        vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
                        if (type == VREG)
                                return (result);
                }
        }
        free(result, M_LINKER);
        return (NULL);
}

#define INT_ALIGN(base, ptr)    ptr =                                   \
        (base) + roundup2((ptr) - (base), sizeof(int))

/*
 * Lookup KLD which contains requested module in the "linker.hints" file. If
 * version specification is available, then try to find the best KLD.
 * Otherwise just find the latest one.
 */
static char *
linker_hints_lookup(const char *path, int pathlen, const char *modname,
    int modnamelen, const struct mod_depend *verinfo)
{
        struct thread *td = curthread;  /* XXX */
        struct ucred *cred = td ? td->td_ucred : NULL;
        struct nameidata nd;
        struct vattr vattr, mattr;
        const char *best, *sep;
        u_char *hints = NULL;
        u_char *cp, *recptr, *bufend, *result, *pathbuf;
        int error, ival, bestver, *intp, found, flags, clen, blen;
        ssize_t reclen;

        result = NULL;
        bestver = found = 0;

        sep = (path[pathlen - 1] != '/') ? "/" : "";
        reclen = imax(modnamelen, strlen(linker_hintfile)) + pathlen +
            strlen(sep) + 1;
        pathbuf = malloc(reclen, M_LINKER, M_WAITOK);
        snprintf(pathbuf, reclen, "%.*s%s%s", pathlen, path, sep,
            linker_hintfile);

        NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, pathbuf);
        flags = FREAD;
        error = vn_open(&nd, &flags, 0, NULL);
        if (error)
                goto bad;
        NDFREE_PNBUF(&nd);
        if (nd.ni_vp->v_type != VREG)
                goto bad;
        best = cp = NULL;
        error = VOP_GETATTR(nd.ni_vp, &vattr, cred);
        if (error)
                goto bad;
        /*
         * XXX: we need to limit this number to some reasonable value
         */
        if (vattr.va_size > LINKER_HINTS_MAX) {
                printf("linker.hints file too large %ld\n", (long)vattr.va_size);
                goto bad;
        }
        if (vattr.va_size < sizeof(ival)) {
                printf("linker.hints file truncated\n");
                goto bad;
        }
        hints = malloc(vattr.va_size, M_TEMP, M_WAITOK);
        error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)hints, vattr.va_size, 0,
            UIO_SYSSPACE, IO_NODELOCKED, cred, NOCRED, &reclen, td);
        if (error)
                goto bad;
        VOP_UNLOCK(nd.ni_vp);
        vn_close(nd.ni_vp, FREAD, cred, td);
        nd.ni_vp = NULL;
        if (reclen != 0) {
                printf("can't read %zd\n", reclen);
                goto bad;
        }
        intp = (int *)hints;
        ival = *intp++;
        if (ival != LINKER_HINTS_VERSION) {
                printf("linker.hints file version mismatch %d\n", ival);
                goto bad;
        }
        bufend = hints + vattr.va_size;
        recptr = (u_char *)intp;
        clen = blen = 0;
        while (recptr < bufend && !found) {
                intp = (int *)recptr;
                reclen = *intp++;
                ival = *intp++;
                cp = (char *)intp;
                switch (ival) {
                case MDT_VERSION:
                        clen = *cp++;
                        if (clen != modnamelen || bcmp(cp, modname, clen) != 0)
                                break;
                        cp += clen;
                        INT_ALIGN(hints, cp);
                        ival = *(int *)cp;
                        cp += sizeof(int);
                        clen = *cp++;
                        if (verinfo == NULL ||
                            ival == verinfo->md_ver_preferred) {
                                found = 1;
                                break;
                        }
                        if (ival >= verinfo->md_ver_minimum &&
                            ival <= verinfo->md_ver_maximum &&
                            ival > bestver) {
                                bestver = ival;
                                best = cp;
                                blen = clen;
                        }
                        break;
                default:
                        break;
                }
                recptr += reclen + sizeof(int);
        }
        /*
         * Finally check if KLD is in the place
         */
        if (found)
                result = linker_lookup_file(path, pathlen, cp, clen, &mattr);
        else if (best)
                result = linker_lookup_file(path, pathlen, best, blen, &mattr);

        /*
         * KLD is newer than hints file. What we should do now?
         */
        if (result && timespeccmp(&mattr.va_mtime, &vattr.va_mtime, >))
                printf("warning: KLD '%s' is newer than the linker.hints"
                    " file\n", result);
bad:
        free(pathbuf, M_LINKER);
        if (hints)
                free(hints, M_TEMP);
        if (nd.ni_vp != NULL) {
                VOP_UNLOCK(nd.ni_vp);
                vn_close(nd.ni_vp, FREAD, cred, td);
        }
        /*
         * If nothing found or hints is absent - fallback to the old
         * way by using "kldname[.ko]" as module name.
         */
        if (!found && !bestver && result == NULL)
                result = linker_lookup_file(path, pathlen, modname,
                    modnamelen, NULL);
        return (result);
}

/*
 * Lookup KLD which contains requested module in the all directories.
 */
static char *
linker_search_module(const char *modname, int modnamelen,
    const struct mod_depend *verinfo)
{
        char *cp, *ep, *result;

        /*
         * traverse the linker path
         */
        for (cp = linker_path; *cp; cp = ep + 1) {
                /* find the end of this component */
                for (ep = cp; (*ep != 0) && (*ep != ';'); ep++);
                result = linker_hints_lookup(cp, ep - cp, modname,
                    modnamelen, verinfo);
                if (result != NULL)
                        return (result);
                if (*ep == 0)
                        break;
        }
        return (NULL);
}

/*
 * Search for module in all directories listed in the linker_path.
 */
static char *
linker_search_kld(const char *name)
{
        char *cp, *ep, *result;
        int len;

        /* qualified at all? */
        if (strchr(name, '/'))
                return (strdup(name, M_LINKER));

        /* traverse the linker path */
        len = strlen(name);
        for (ep = linker_path; *ep; ep++) {
                cp = ep;
                /* find the end of this component */
                for (; *ep != 0 && *ep != ';'; ep++);
                result = linker_lookup_file(cp, ep - cp, name, len, NULL);
                if (result != NULL)
                        return (result);
        }
        return (NULL);
}

static const char *
linker_basename(const char *path)
{
        const char *filename;

        filename = strrchr(path, '/');
        if (filename == NULL)
                return path;
        if (filename[1])
                filename++;
        return (filename);
}

#if defined(HWPMC_HOOKS) || defined(HWT_HOOKS)
/*
 * Inform hwpmc about the set of kernel modules currently loaded.
 */
void *
linker_hwpmc_list_objects(void)
{
        linker_file_t lf;
        struct pmckern_map_in *kobase;
        int i, nmappings;

        nmappings = 0;
        sx_slock(&kld_sx);
        TAILQ_FOREACH(lf, &linker_files, link)
                nmappings++;

        /* Allocate nmappings + 1 entries. */
        kobase = malloc((nmappings + 1) * sizeof(struct pmckern_map_in),
            M_LINKER, M_WAITOK | M_ZERO);
        i = 0;
        TAILQ_FOREACH(lf, &linker_files, link) {
                /* Save the info for this linker file. */
                kobase[i].pm_file = lf->pathname;
                kobase[i].pm_address = (uintptr_t)lf->address;
                i++;
        }
        sx_sunlock(&kld_sx);

        KASSERT(i > 0, ("linker_hpwmc_list_objects: no kernel objects?"));

        /* The last entry of the malloced area comprises of all zeros. */
        KASSERT(kobase[i].pm_file == NULL,
            ("linker_hwpmc_list_objects: last object not NULL"));

        return ((void *)kobase);
}
#endif

/* check if root file system is not mounted */
static bool
linker_root_mounted(void)
{
        struct pwd *pwd;
        bool ret;

        if (rootvnode == NULL)
                return (false);

        pwd = pwd_hold(curthread);
        ret = pwd->pwd_rdir != NULL;
        pwd_drop(pwd);
        return (ret);
}

/*
 * Find a file which contains given module and load it, if "parent" is not
 * NULL, register a reference to it.
 */
static int
linker_load_module(const char *kldname, const char *modname,
    struct linker_file *parent, const struct mod_depend *verinfo,
    struct linker_file **lfpp)
{
        linker_file_t lfdep;
        const char *filename;
        char *pathname;
        int error;

        sx_assert(&kld_sx, SA_XLOCKED);
        if (modname == NULL) {
                /*
                 * We have to load KLD
                 */
                KASSERT(verinfo == NULL, ("linker_load_module: verinfo"
                    " is not NULL"));
                if (!linker_root_mounted())
                        return (ENXIO);
                pathname = linker_search_kld(kldname);
        } else {
                if (modlist_lookup2(modname, verinfo) != NULL)
                        return (EEXIST);
                if (!linker_root_mounted())
                        return (ENXIO);
                if (kldname != NULL)
                        pathname = strdup(kldname, M_LINKER);
                else
                        /*
                         * Need to find a KLD with required module
                         */
                        pathname = linker_search_module(modname,
                            strlen(modname), verinfo);
        }
        if (pathname == NULL)
                return (ENOENT);

        /*
         * Can't load more than one file with the same basename XXX:
         * Actually it should be possible to have multiple KLDs with
         * the same basename but different path because they can
         * provide different versions of the same modules.
         */
        filename = linker_basename(pathname);
        if (linker_find_file_by_name(filename))
                error = EEXIST;
        else do {
                error = linker_load_file(pathname, &lfdep);
                if (error)
                        break;
                if (modname && verinfo &&
                    modlist_lookup2(modname, verinfo) == NULL) {
                        linker_file_unload(lfdep, LINKER_UNLOAD_FORCE);
                        error = ENOENT;
                        break;
                }
                if (parent)
                        linker_file_add_dependency(parent, lfdep);
                if (lfpp)
                        *lfpp = lfdep;
        } while (0);
        free(pathname, M_LINKER);
        return (error);
}

/*
 * This routine is responsible for finding dependencies of userland initiated
 * kldload(2)'s of files.
 */
int
linker_load_dependencies(linker_file_t lf)
{
        linker_file_t lfdep;
        struct mod_metadata **start, **stop, **mdp, **nmdp;
        struct mod_metadata *mp, *nmp;
        const struct mod_depend *verinfo;
        modlist_t mod;
        const char *modname, *nmodname;
        int ver, error = 0;

        /*
         * All files are dependent on /kernel.
         */
        sx_assert(&kld_sx, SA_XLOCKED);
        if (linker_kernel_file) {
                linker_kernel_file->refs++;
                linker_file_add_dependency(lf, linker_kernel_file);
        }
        if (linker_file_lookup_set(lf, MDT_SETNAME, &start, &stop,
            NULL) != 0)
                return (0);
        for (mdp = start; mdp < stop; mdp++) {
                mp = *mdp;
                if (mp->md_type != MDT_VERSION)
                        continue;
                modname = mp->md_cval;
                ver = ((const struct mod_version *)mp->md_data)->mv_version;
                mod = modlist_lookup(modname, ver);
                if (mod != NULL) {
                        printf("interface %s.%d already present in the KLD"
                            " '%s'!\n", modname, ver,
                            mod->container->filename);
                        return (EEXIST);
                }
        }

        for (mdp = start; mdp < stop; mdp++) {
                mp = *mdp;
                if (mp->md_type != MDT_DEPEND)
                        continue;
                modname = mp->md_cval;
                verinfo = mp->md_data;
                nmodname = NULL;
                for (nmdp = start; nmdp < stop; nmdp++) {
                        nmp = *nmdp;
                        if (nmp->md_type != MDT_VERSION)
                                continue;
                        nmodname = nmp->md_cval;
                        if (strcmp(modname, nmodname) == 0)
                                break;
                }
                if (nmdp < stop)/* early exit, it's a self reference */
                        continue;
                mod = modlist_lookup2(modname, verinfo);
                if (mod) {      /* woohoo, it's loaded already */
                        lfdep = mod->container;
                        lfdep->refs++;
                        linker_file_add_dependency(lf, lfdep);
                        continue;
                }
                error = linker_load_module(NULL, modname, lf, verinfo, NULL);
                if (error) {
                        printf("KLD %s: depends on %s - not available or"
                            " version mismatch\n", lf->filename, modname);
                        break;
                }
        }

        if (error)
                return (error);
        linker_addmodules(lf, start, stop, 0);
        return (error);
}

static int
sysctl_kern_function_list_iterate(const char *name, void *opaque)
{
        struct sysctl_req *req;

        req = opaque;
        return (SYSCTL_OUT(req, name, strlen(name) + 1));
}

/*
 * Export a nul-separated, double-nul-terminated list of all function names
 * in the kernel.
 */
static int
sysctl_kern_function_list(SYSCTL_HANDLER_ARGS)
{
        linker_file_t lf;
        int error;

#ifdef MAC
        error = mac_kld_check_stat(req->td->td_ucred);
        if (error)
                return (error);
#endif
        error = sysctl_wire_old_buffer(req, 0);
        if (error != 0)
                return (error);
        sx_xlock(&kld_sx);
        TAILQ_FOREACH(lf, &linker_files, link) {
                error = LINKER_EACH_FUNCTION_NAME(lf,
                    sysctl_kern_function_list_iterate, req);
                if (error) {
                        sx_xunlock(&kld_sx);
                        return (error);
                }
        }
        sx_xunlock(&kld_sx);
        return (SYSCTL_OUT(req, "", 1));
}

SYSCTL_PROC(_kern, OID_AUTO, function_list,
    CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
    sysctl_kern_function_list, "",
    "kernel function list");