Do not rely on the fact that components in module_path to have

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

/*-
 * Copyright (c) 1997 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.
 *
 * $FreeBSD: src/sys/kern/kern_linker.c,v 1.41.2.3 2001/11/21 17:50:35 luigi Exp $
 * $DragonFly: src/sys/kern/kern_linker.c,v 1.36 2007/05/07 02:11:33 y0netan1 Exp $
 */

#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/sysproto.h>
#include <sys/sysent.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/linker.h>
#include <sys/fcntl.h>
#include <sys/libkern.h>
#include <sys/nlookup.h>
#include <sys/vnode.h>
#include <sys/sysctl.h>

#include <vm/vm_zone.h>

#ifdef KLD_DEBUG
int kld_debug = 0;
#endif

/* Metadata from the static kernel */
SET_DECLARE(modmetadata_set, struct mod_metadata);
MALLOC_DEFINE(M_LINKER, "kld", "kernel linker");

linker_file_t linker_current_file;
linker_file_t linker_kernel_file;

static struct lock lock;        /* lock for the file list */
static linker_class_list_t classes;
static linker_file_list_t linker_files;
static int next_file_id = 1;

static void
linker_init(void* arg)
{
    lockinit(&lock, "klink", 0, 0);
    TAILQ_INIT(&classes);
    TAILQ_INIT(&linker_files);
}

SYSINIT(linker, SI_BOOT2_KLD, SI_ORDER_FIRST, linker_init, 0);

int
linker_add_class(const char* desc, void* priv,
                 struct linker_class_ops* ops)
{
    linker_class_t lc;

    lc = kmalloc(sizeof(struct linker_class), M_LINKER, M_NOWAIT);
    if (!lc)
        return ENOMEM;
    bzero(lc, sizeof(*lc));

    lc->desc = desc;
    lc->priv = priv;
    lc->ops = ops;
    TAILQ_INSERT_HEAD(&classes, lc, link);

    return 0;
}

static int
linker_file_sysinit(linker_file_t lf)
{
    struct sysinit** start, ** stop;
    struct sysinit** sipp;
    struct sysinit** xipp;
    struct sysinit* save;
    const moduledata_t *moddata;
    int error;

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

    if (linker_file_lookup_set(lf, "sysinit_set", &start, &stop, NULL) != 0)
        return 0; /* XXX is this correct ? No sysinit ? */

    /* HACK ALERT! */
    for (sipp = start; sipp < stop; sipp++) {
        if ((*sipp)->func == module_register_init) {
            moddata = (*sipp)->udata;
            error = module_register(moddata, lf);
            if (error) {
                kprintf("linker_file_sysinit \"%s\" failed to register! %d\n",
                    lf->filename, error);
                return error;
            }
        }
    }
            
    /*
     * 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.
     */
    for (sipp = start; sipp < stop; sipp++) {
        if ((*sipp)->subsystem == SI_SPECIAL_DUMMY)
            continue;   /* skip dummy task(s)*/

        /* Call function */
        (*((*sipp)->func))((*sipp)->udata);
    }
    return 0; /* no errors */
}

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

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

    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.
     */
    for (sipp = start; sipp < stop; sipp++) {
        if ((*sipp)->subsystem == SI_SPECIAL_DUMMY)
            continue;   /* skip dummy task(s)*/

        /* Call function */
        (*((*sipp)->func))((*sipp)->udata);
    }
}

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

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

    if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
        return;
    for (oidp = start; oidp < stop; oidp++)
        sysctl_register_oid(*oidp);
}

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

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

    if (linker_file_lookup_set(lf, "sysctl_set", &start, &stop, NULL) != 0)
        return;
    for (oidp = start; oidp < stop; oidp++)
        sysctl_unregister_oid(*oidp);
}

int
linker_load_file(const char* filename, linker_file_t* result)
{
    linker_class_t lc;
    linker_file_t lf;
    int foundfile, error = 0;
    char *koname = NULL;

    /* Refuse to load modules if securelevel raised */
    if (securelevel > 0 || kernel_mem_readonly)
        return EPERM; 

    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++;
        goto out;
    }
    if (find_mod_metadata(filename)) {
        if (linker_kernel_file)
            ++linker_kernel_file->refs;
        *result = linker_kernel_file;
        goto out;
    }

    koname = kmalloc(strlen(filename) + 4, M_LINKER, M_WAITOK);
    if (koname == NULL) {
        error = ENOMEM;
        goto out;
    }
    ksprintf(koname, "%s.ko", filename);
    lf = NULL;
    foundfile = 0;
    for (lc = TAILQ_FIRST(&classes); lc; lc = TAILQ_NEXT(lc, link)) {
        KLD_DPF(FILE, ("linker_load_file: trying to load %s as %s\n",
                       filename, lc->desc));

        error = lc->ops->load_file(koname, &lf);        /* First with .ko */
        if (lf == NULL && error == ENOENT)
            error = lc->ops->load_file(filename, &lf);  /* Then try without */
        /*
         * 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 (lf) {
            linker_file_register_sysctls(lf);
            error = linker_file_sysinit(lf);

            *result = lf;
            goto out;
        }
    }
    /*
     * Less than ideal, but tells the user whether it failed to load or
     * the module was not found.
     */
    if (foundfile) {
            /*
             * 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 messages.
             */
            if (error != EEXIST)
                    error = ENOEXEC;
    } else {
        error = ENOENT;         /* Nothing found */
    }

out:
    if (koname)
        kfree(koname, M_LINKER);
    return error;
}

linker_file_t
linker_find_file_by_name(const char* filename)
{
    linker_file_t lf = 0;
    char *koname;
    int i;

    for (i = strlen(filename); i > 0 && filename[i-1] != '/'; --i)
        ;
    filename += i;

    koname = kmalloc(strlen(filename) + 4, M_LINKER, M_WAITOK);
    if (koname == NULL)
        goto out;
    ksprintf(koname, "%s.ko", filename);

    lockmgr(&lock, LK_SHARED);
    for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link)) {
        if (!strcmp(lf->filename, koname))
            break;
        if (!strcmp(lf->filename, filename))
            break;
    }
    lockmgr(&lock, LK_RELEASE);

out:
    if (koname)
        kfree(koname, M_LINKER);
    return lf;
}

linker_file_t
linker_find_file_by_id(int fileid)
{
    linker_file_t lf = 0;

    lockmgr(&lock, LK_SHARED);
    for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link))
        if (lf->id == fileid)
            break;
    lockmgr(&lock, LK_RELEASE);

    return lf;
}

linker_file_t
linker_make_file(const char* pathname, void* priv, struct linker_file_ops* ops)
{
    linker_file_t lf = 0;
    int namelen;
    const char *filename;

    filename = rindex(pathname, '/');
    if (filename && filename[1])
        filename++;
    else
        filename = pathname;

    KLD_DPF(FILE, ("linker_make_file: new file, filename=%s\n", filename));
    lockmgr(&lock, LK_EXCLUSIVE);
    namelen = strlen(filename) + 1;
    lf = kmalloc(sizeof(struct linker_file) + namelen, M_LINKER, M_WAITOK);
    if (!lf)
        goto out;
    bzero(lf, sizeof(*lf));

    lf->refs = 1;
    lf->userrefs = 0;
    lf->flags = 0;
    lf->filename = (char*) (lf + 1);
    strcpy(lf->filename, filename);
    lf->id = next_file_id++;
    lf->ndeps = 0;
    lf->deps = NULL;
    STAILQ_INIT(&lf->common);
    TAILQ_INIT(&lf->modules);

    lf->priv = priv;
    lf->ops = ops;
    TAILQ_INSERT_TAIL(&linker_files, lf, link);

out:
    lockmgr(&lock, LK_RELEASE);
    return lf;
}

int
linker_file_unload(linker_file_t file)
{
    module_t mod, next;
    struct common_symbol* cp;
    int error = 0;
    int i;

    /* Refuse to unload modules if securelevel raised */
    if (securelevel > 0 || kernel_mem_readonly)
        return EPERM; 

    KLD_DPF(FILE, ("linker_file_unload: lf->refs=%d\n", file->refs));
    lockmgr(&lock, LK_EXCLUSIVE);
    if (file->refs == 1) {
        KLD_DPF(FILE, ("linker_file_unload: file is unloading, informing modules\n"));
        /*
         * Temporarily bump file->refs to prevent recursive unloading
         */
        ++file->refs;

        /*
         * Inform any modules associated with this file.
         */
        mod = TAILQ_FIRST(&file->modules);
        while (mod) {
            /*
             * Give the module a chance to veto the unload.  Note that the
             * act of unloading the module may cause other modules in the
             * same file list to be unloaded recursively.
             */
            if ((error = module_unload(mod)) != 0) {
                KLD_DPF(FILE, ("linker_file_unload: module %x vetoes unload\n",
                               mod));
                lockmgr(&lock, LK_RELEASE);
                file->refs--;
                goto out;
            }

            /*
             * Recursive relationships may prevent the release from
             * immediately removing the module, or may remove other
             * modules in the list.
             */
            next = module_getfnext(mod);
            module_release(mod);
            mod = next;
        }

        /*
         * Since we intend to destroy the file structure, we expect all
         * modules to have been removed by now.
         */
        for (mod = TAILQ_FIRST(&file->modules); 
             mod; 
             mod = module_getfnext(mod)
        ) {
            kprintf("linker_file_unload: module %p still has refs!\n", mod);
        }
        --file->refs;
    }

    file->refs--;
    if (file->refs > 0) {
        lockmgr(&lock, LK_RELEASE);
        goto out;
    }

    /* Don't try to run SYSUNINITs if we are unloaded due to a link error */
    if (file->flags & LINKER_FILE_LINKED) {
        linker_file_sysuninit(file);
        linker_file_unregister_sysctls(file);
    }

    TAILQ_REMOVE(&linker_files, file, link);
    lockmgr(&lock, LK_RELEASE);

    for (i = 0; i < file->ndeps; i++)
        linker_file_unload(file->deps[i]);
    kfree(file->deps, M_LINKER);

    for (cp = STAILQ_FIRST(&file->common); cp;
         cp = STAILQ_FIRST(&file->common)) {
        STAILQ_REMOVE(&file->common, cp, common_symbol, link);
        kfree(cp, M_LINKER);
    }

    file->ops->unload(file);
    kfree(file, M_LINKER);

out:
    return error;
}

int
linker_file_add_dependancy(linker_file_t file, linker_file_t dep)
{
    linker_file_t* newdeps;

    newdeps = kmalloc((file->ndeps + 1) * sizeof(linker_file_t*),
                     M_LINKER, M_WAITOK);
    if (newdeps == NULL)
        return ENOMEM;
    bzero(newdeps, (file->ndeps + 1) * sizeof(linker_file_t*));

    if (file->deps) {
        bcopy(file->deps, newdeps, file->ndeps * sizeof(linker_file_t*));
        kfree(file->deps, M_LINKER);
    }
    file->deps = newdeps;
    file->deps[file->ndeps] = dep;
    file->ndeps++;

    return 0;
}

/*
 * 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 ***
 */
int
linker_file_lookup_set(linker_file_t file, const char *name,
                      void *firstp, void *lastp, int *countp)
{
    return file->ops->lookup_set(file, name, firstp, lastp, countp);
}

int
linker_file_lookup_symbol(linker_file_t file, const char* name, int deps, caddr_t *raddr)
{
    c_linker_sym_t sym;
    linker_symval_t symval;
    linker_file_t lf;
    size_t common_size = 0;
    int i;

    KLD_DPF(SYM, ("linker_file_lookup_symbol: file=%x, name=%s, deps=%d\n",
                  file, name, deps));

    if (file->ops->lookup_symbol(file, name, &sym) == 0) {
        file->ops->symbol_values(file, sym, &symval);

        /*
         * XXX Assume a common symbol if its value is 0 and it has a non-zero
         * size, otherwise it could be an absolute symbol with a value of 0.
         */
        if (symval.value == 0 && symval.size != 0) {
            /*
             * For commons, first look them up in the dependancies and
             * only allocate space if not found there.
             */
            common_size = symval.size;
        } else {
            KLD_DPF(SYM, ("linker_file_lookup_symbol: symbol.value=%x\n", symval.value));
            *raddr = symval.value;
            return 0;
        }
    }
    if (deps) {
        for (i = 0; i < file->ndeps; i++) {
            if (linker_file_lookup_symbol(file->deps[i], name, 0, raddr) == 0) {
                KLD_DPF(SYM, ("linker_file_lookup_symbol: deps value=%x\n", *raddr));
                return 0;
            }
        }

        /* If we have not found it in the dependencies, search globally */
        for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link)) {
            /* But skip the current file if it's on the list */
            if (lf == file)
                continue;
            /* And skip the files we searched above */
            for (i = 0; i < file->ndeps; i++)
                if (lf == file->deps[i])
                    break;
            if (i < file->ndeps)
                continue;
            if (linker_file_lookup_symbol(lf, name, 0, raddr) == 0) {
                KLD_DPF(SYM, ("linker_file_lookup_symbol: global value=%x\n", *raddr));
                return 0;
            }
        }
    }

    if (common_size > 0) {
        /*
         * This is a common symbol which was not found in the
         * dependancies.  We maintain a simple common symbol table in
         * the file object.
         */
        struct common_symbol* cp;

        for (cp = STAILQ_FIRST(&file->common); cp;
             cp = STAILQ_NEXT(cp, link))
            if (!strcmp(cp->name, name)) {
                KLD_DPF(SYM, ("linker_file_lookup_symbol: old common value=%x\n", cp->address));
                *raddr = cp->address;
                return 0;
            }

        /*
         * Round the symbol size up to align.
         */
        common_size = (common_size + sizeof(int) - 1) & -sizeof(int);
        cp = kmalloc(sizeof(struct common_symbol)
                    + common_size
                    + strlen(name) + 1,
                    M_LINKER, M_WAITOK);
        if (!cp) {
            KLD_DPF(SYM, ("linker_file_lookup_symbol: nomem\n"));
            return ENOMEM;
        }
        bzero(cp, sizeof(struct common_symbol) + common_size + strlen(name)+ 1);

        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=%x\n", cp->address));
        *raddr = cp->address;
        return 0;
    }

    KLD_DPF(SYM, ("linker_file_lookup_symbol: fail\n"));
    return ENOENT;
}

#ifdef DDB
/*
 * 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 inconsistant instead.
 */

int
linker_ddb_lookup(const char *symstr, c_linker_sym_t *sym)
{
    linker_file_t lf;

    for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link)) {
        if (lf->ops->lookup_symbol(lf, symstr, sym) == 0)
            return 0;
    }
    return ENOENT;
}

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

    best = 0;
    bestdiff = off;
    for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link)) {
        if (lf->ops->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;
    }
}

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

    for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link)) {
        if (lf->ops->symbol_values(lf, sym, symval) == 0)
            return 0;
    }
    return ENOENT;
}

#endif

/*
 * Syscalls.
 */

int
sys_kldload(struct kldload_args *uap)
{
    struct thread *td = curthread;
    char* filename = NULL, *modulename;
    linker_file_t lf;
    int error = 0;

    uap->sysmsg_result = -1;

    if (securelevel > 0 || kernel_mem_readonly) /* redundant, but that's OK */
        return EPERM;

    if ((error = suser(td)) != 0)
        return error;

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

    /* Can't load more than one module with the same name */
    modulename = rindex(filename, '/');
    if (modulename == NULL)
        modulename = filename;
    else
        modulename++;
    if (linker_find_file_by_name(modulename)) {
        error = EEXIST;
        goto out;
    }

    if ((error = linker_load_file(filename, &lf)) != 0)
        goto out;

    lf->userrefs++;
    uap->sysmsg_result = lf->id;

out:
    if (filename)
        kfree(filename, M_TEMP);
    return error;
}

int
sys_kldunload(struct kldunload_args *uap)
{
    struct thread *td = curthread;
    linker_file_t lf;
    int error = 0;

    if (securelevel > 0 || kernel_mem_readonly) /* redundant, but that's OK */
        return EPERM;

    if ((error = suser(td)) != 0)
        return error;

    lf = linker_find_file_by_id(uap->fileid);
    if (lf) {
        KLD_DPF(FILE, ("kldunload: lf->userrefs=%d\n", lf->userrefs));
        if (lf->userrefs == 0) {
            kprintf("linkerunload: attempt to unload file that was loaded by the kernel\n");
            error = EBUSY;
            goto out;
        }
        lf->userrefs--;
        error = linker_file_unload(lf);
        if (error)
            lf->userrefs++;
    } else
        error = ENOENT;

out:
    return error;
}

int
sys_kldfind(struct kldfind_args *uap)
{
    char *filename = NULL, *modulename;
    linker_file_t lf;
    int error = 0;

    uap->sysmsg_result = -1;

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

    modulename = rindex(filename, '/');
    if (modulename == NULL)
        modulename = filename;

    lf = linker_find_file_by_name(modulename);
    if (lf)
        uap->sysmsg_result = lf->id;
    else
        error = ENOENT;

out:
    if (filename)
        kfree(filename, M_TEMP);
    return error;
}

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

    if (uap->fileid == 0) {
        if (TAILQ_FIRST(&linker_files))
            uap->sysmsg_result = TAILQ_FIRST(&linker_files)->id;
        else
            uap->sysmsg_result = 0;
        return 0;
    }

    lf = linker_find_file_by_id(uap->fileid);
    if (lf) {
        if (TAILQ_NEXT(lf, link))
            uap->sysmsg_result = TAILQ_NEXT(lf, link)->id;
        else
            uap->sysmsg_result = 0;
    } else
        error = ENOENT;

    return error;
}

int
sys_kldstat(struct kldstat_args *uap)
{
    linker_file_t lf;
    int error = 0;
    int version;
    struct kld_file_stat* stat;
    int namelen;

    lf = linker_find_file_by_id(uap->fileid);
    if (!lf) {
        error = ENOENT;
        goto out;
    }

    stat = uap->stat;

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

    namelen = strlen(lf->filename) + 1;
    if (namelen > MAXPATHLEN)
        namelen = MAXPATHLEN;
    if ((error = copyout(lf->filename, &stat->name[0], namelen)) != 0)
        goto out;
    if ((error = copyout(&lf->refs, &stat->refs, sizeof(int))) != 0)
        goto out;
    if ((error = copyout(&lf->id, &stat->id, sizeof(int))) != 0)
        goto out;
    if ((error = copyout(&lf->address, &stat->address, sizeof(caddr_t))) != 0)
        goto out;
    if ((error = copyout(&lf->size, &stat->size, sizeof(size_t))) != 0)
        goto out;

    uap->sysmsg_result = 0;

out:
    return error;
}

int
sys_kldfirstmod(struct kldfirstmod_args *uap)
{
    linker_file_t lf;
    int error = 0;

    lf = linker_find_file_by_id(uap->fileid);
    if (lf) {
        if (TAILQ_FIRST(&lf->modules))
            uap->sysmsg_result = module_getid(TAILQ_FIRST(&lf->modules));
        else
            uap->sysmsg_result = 0;
    } else
        error = ENOENT;

    return error;
}

int
sys_kldsym(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;

    if ((error = copyin(uap->data, &lookup, sizeof(lookup))) != 0)
        goto out;
    if (lookup.version != sizeof(lookup) || uap->cmd != KLDSYM_LOOKUP) {
        error = EINVAL;
        goto out;
    }

    symstr = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK);
    if ((error = copyinstr(lookup.symname, symstr, MAXPATHLEN, NULL)) != 0)
        goto out;

    if (uap->fileid != 0) {
        lf = linker_find_file_by_id(uap->fileid);
        if (lf == NULL) {
            error = ENOENT;
            goto out;
        }
        if (lf->ops->lookup_symbol(lf, symstr, &sym) == 0 &&
            lf->ops->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 {
        for (lf = TAILQ_FIRST(&linker_files); lf; lf = TAILQ_NEXT(lf, link)) {
            if (lf->ops->lookup_symbol(lf, symstr, &sym) == 0 &&
                lf->ops->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)
            error = ENOENT;
    }
out:
    if (symstr)
        kfree(symstr, M_TEMP);
    return error;
}

/*
 * Look for module metadata in the static kernel
 */
struct mod_metadata *
find_mod_metadata(const char *modname)
{
    int len;
    struct mod_metadata **mdp;
    struct mod_metadata *mdt;

    /*
     * Strip path prefixes and any dot extension.  MDT_MODULE names
     * are just the module name without a path or ".ko".
     */
    for (len = strlen(modname) - 1; len >= 0; --len) {
        if (modname[len] == '/')
            break;
    }
    modname += len + 1;
    for (len = 0; modname[len] && modname[len] != '.'; ++len)
        ;

    /*
     * Look for the module declaration
     */
    SET_FOREACH(mdp, modmetadata_set) {
        mdt = *mdp;
        if (mdt->md_type != MDT_MODULE)
            continue;
        if (strlen(mdt->md_cval) == len &&
            strncmp(mdt->md_cval, modname, len) == 0) {
            return(mdt);
        }
    }
    return(NULL);
}

/*
 * Preloaded module support
 */
static void
linker_preload(void* arg)
{
    caddr_t             modptr;
    char                *modname;
    char                *modtype;
    linker_file_t       lf;
    linker_class_t      lc;
    int                 error;
    struct sysinit      **sipp;
    const moduledata_t  *moddata;
    struct sysinit      **si_start, **si_stop;

    modptr = NULL;
    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) {
            kprintf("Preloaded module at %p does not have a name!\n", modptr);
            continue;
        }
        if (modtype == NULL) {
            kprintf("Preloaded module at %p does not have a type!\n", modptr);
            continue;
        }

        /*
         * This is a hack at the moment, but what's in FreeBSD-5 is even 
         * worse so I'd rather the hack.
         */
        kprintf("Preloaded %s \"%s\" at %p", modtype, modname, modptr);
        if (find_mod_metadata(modname)) {
            kprintf(" (ignored, already in static kernel)\n");
            continue;
        }
        kprintf(".\n");

        lf = linker_find_file_by_name(modname);
        if (lf) {
            lf->refs++;
            lf->userrefs++;
            continue;
        }
        lf = NULL;
        for (lc = TAILQ_FIRST(&classes); lc; lc = TAILQ_NEXT(lc, link)) {
            error = lc->ops->load_file(modname, &lf);
            if (error) {
                lf = NULL;
                break;
            }
        }
        if (lf) {
            lf->userrefs++;

            if (linker_file_lookup_set(lf, "sysinit_set", &si_start, &si_stop, NULL) == 0) {
                /* HACK ALERT!
                 * This is to set the sysinit moduledata so that the module
                 * can attach itself to the correct containing file.
                 * The sysinit could be run at *any* time.
                 */
                for (sipp = si_start; sipp < si_stop; sipp++) {
                    if ((*sipp)->func == module_register_init) {
                        moddata = (*sipp)->udata;
                        error = module_register(moddata, lf);
                        if (error)
                            kprintf("Preloaded %s \"%s\" failed to register: %d\n",
                                modtype, modname, error);
                    }
                }
                sysinit_add(si_start, si_stop);
            }
            linker_file_register_sysctls(lf);
        }
    }
}

SYSINIT(preload, SI_BOOT2_KLD, SI_ORDER_MIDDLE, linker_preload, 0);

/*
 * 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_path[MAXPATHLEN] = "/;/boot;/modules";

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

static char *
linker_strdup(const char *str)
{
    char        *result;

    if ((result = kmalloc((strlen(str) + 1), M_LINKER, M_WAITOK)) != NULL)
        strcpy(result, str);
    return(result);
}

char *
linker_search_path(const char *name)
{
    struct nlookupdata  nd;
    char                *cp, *ep, *result;
    size_t              name_len, prefix_len;
    int                 sep;
    int                 error;
    enum vtype          type;

    /* qualified at all? */
    if (index(name, '/'))
        return(linker_strdup(name));

    /* traverse the linker path */
    cp = linker_path;
    name_len = strlen(name);
    for (;;) {

        /* find the end of this component */
        for (ep = cp; (*ep != 0) && (*ep != ';'); ep++)
            ;
        prefix_len = ep - cp;
        /* if this component doesn't end with a slash, add one */
        if (ep == cp || *(ep - 1) != '/')
            sep = 1;
        else
            sep = 0;

        result = kmalloc(prefix_len + name_len + 1, M_LINKER, M_WAITOK);
        if (result == NULL)     /* actually ENOMEM */
            return(NULL);

        strncpy(result, cp, prefix_len);
        if (sep)
            result[prefix_len++] = '/';
        strcpy(result + prefix_len, name);

        /*
         * Attempt to open the file, and return the path if we succeed and it's
         * a regular file.
         */
        error = nlookup_init(&nd, result, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP);
        if (error == 0)
            error = vn_open(&nd, NULL, FREAD, 0);
        if (error == 0) {
            type = nd.nl_open_vp->v_type;
            if (type == VREG) {
                nlookup_done(&nd);
                return (result);
            }
        }
        nlookup_done(&nd);
        kfree(result, M_LINKER);

        if (*ep == 0)
            break;
        cp = ep + 1;
    }
    return(NULL);
}