xref: /freebsd/sys/kern/kern_linker.c (revision 0640d357f29fb1c0daaaffadd0416c5981413afd)
1 /*-
2  * Copyright (c) 1997 Doug Rabson
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  *	$Id: kern_linker.c,v 1.12 1998/11/03 13:09:31 peter Exp $
27  */
28 
29 #include "opt_ddb.h"
30 
31 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/systm.h>
34 #include <sys/malloc.h>
35 #include <sys/sysproto.h>
36 #include <sys/sysent.h>
37 #include <sys/proc.h>
38 #include <sys/lock.h>
39 #include <machine/cpu.h>
40 #include <machine/bootinfo.h>
41 #include <sys/module.h>
42 #include <sys/linker.h>
43 #include <sys/unistd.h>
44 #include <sys/fcntl.h>
45 #include <sys/libkern.h>
46 #include <sys/namei.h>
47 #include <sys/vnode.h>
48 #include <sys/sysctl.h>
49 
50 MALLOC_DEFINE(M_LINKER, "kld", "kernel linker");
51 linker_file_t linker_current_file;
52 
53 static struct lock lock;	/* lock for the file list */
54 static linker_class_list_t classes;
55 static linker_file_list_t files;
56 static int next_file_id = 1;
57 
58 static void
59 linker_init(void* arg)
60 {
61     lockinit(&lock, PVM, "klink", 0, 0);
62     TAILQ_INIT(&classes);
63     TAILQ_INIT(&files);
64 }
65 
66 SYSINIT(linker, SI_SUB_KLD, SI_ORDER_FIRST, linker_init, 0);
67 
68 int
69 linker_add_class(const char* desc, void* priv,
70 		 struct linker_class_ops* ops)
71 {
72     linker_class_t lc;
73 
74     lc = malloc(sizeof(struct linker_class), M_LINKER, M_NOWAIT);
75     if (!lc)
76 	return ENOMEM;
77     bzero(lc, sizeof(*lc));
78 
79     lc->desc = desc;
80     lc->priv = priv;
81     lc->ops = ops;
82     TAILQ_INSERT_HEAD(&classes, lc, link);
83 
84     return 0;
85 }
86 
87 static void
88 linker_file_sysinit(linker_file_t lf)
89 {
90     struct linker_set* sysinits;
91     struct sysinit** sipp;
92     struct sysinit** xipp;
93     struct sysinit* save;
94     moduledata_t *moddata;
95 
96     KLD_DPF(FILE, ("linker_file_sysinit: calling SYSINITs for %s\n",
97 		   lf->filename));
98 
99     sysinits = (struct linker_set*)
100 	linker_file_lookup_symbol(lf, "sysinit_set", 0);
101 
102     KLD_DPF(FILE, ("linker_file_sysinit: SYSINITs %p\n", sysinits));
103     if (!sysinits)
104 	return;
105 
106     /* HACK ALERT! */
107     for (sipp = (struct sysinit **)sysinits->ls_items; *sipp; sipp++) {
108 	if ((*sipp)->func == module_register_init) {
109 	    moddata = (*sipp)->udata;
110 	    moddata->_file = lf;
111 	}
112     }
113 
114     /*
115      * Perform a bubble sort of the system initialization objects by
116      * their subsystem (primary key) and order (secondary key).
117      *
118      * Since some things care about execution order, this is the
119      * operation which ensures continued function.
120      */
121     for( sipp = (struct sysinit **)sysinits->ls_items; *sipp; sipp++) {
122 	for( xipp = sipp + 1; *xipp; xipp++) {
123 	    if( (*sipp)->subsystem < (*xipp)->subsystem ||
124 		( (*sipp)->subsystem == (*xipp)->subsystem &&
125 		  (*sipp)->order < (*xipp)->order))
126 		continue;	/* skip*/
127 	    save = *sipp;
128 	    *sipp = *xipp;
129 	    *xipp = save;
130 	}
131     }
132 
133 
134     /*
135      * Traverse the (now) ordered list of system initialization tasks.
136      * Perform each task, and continue on to the next task.
137      *
138      * The last item on the list is expected to be the scheduler,
139      * which will not return.
140      */
141     for( sipp = (struct sysinit **)sysinits->ls_items; *sipp; sipp++) {
142 	if( (*sipp)->subsystem == SI_SUB_DUMMY)
143 	    continue;	/* skip dummy task(s)*/
144 
145 	switch( (*sipp)->type) {
146 	case SI_TYPE_DEFAULT:
147 	    /* no special processing*/
148 	    (*((*sipp)->func))( (*sipp)->udata);
149 	    break;
150 
151 	case SI_TYPE_KTHREAD:
152 #if !defined(SMP)
153 	    /* kernel thread*/
154 	    if (fork1(&proc0, RFFDG|RFPROC|RFMEM))
155 		panic("fork kernel thread");
156 	    cpu_set_fork_handler(pfind(proc0.p_retval[0]),
157 		(*sipp)->func, (*sipp)->udata);
158 	    break;
159 #endif
160 
161 	case SI_TYPE_KPROCESS:
162 	    /* kernel thread*/
163 	    if (fork1(&proc0, RFFDG|RFPROC))
164 		panic("fork kernel process");
165 	    cpu_set_fork_handler(pfind(proc0.p_retval[0]),
166 		(*sipp)->func, (*sipp)->udata);
167 	    break;
168 
169 	default:
170 	    panic( "linker_file_sysinit: unrecognized init type");
171 	}
172     }
173 }
174 
175 int
176 linker_load_file(const char* filename, linker_file_t* result)
177 {
178     linker_class_t lc;
179     linker_file_t lf;
180     int error = 0;
181     char *koname = NULL;
182 
183     lf = linker_find_file_by_name(filename);
184     if (lf) {
185 	KLD_DPF(FILE, ("linker_load_file: file %s is already loaded, incrementing refs\n", filename));
186 	*result = lf;
187 	lf->refs++;
188 	goto out;
189     }
190 
191     koname = malloc(strlen(filename) + 4, M_LINKER, M_WAITOK);
192     if (koname == NULL) {
193 	error = ENOMEM;
194 	goto out;
195     }
196     sprintf(koname, "%s.ko", filename);
197     lf = NULL;
198     for (lc = TAILQ_FIRST(&classes); lc; lc = TAILQ_NEXT(lc, link)) {
199 	KLD_DPF(FILE, ("linker_load_file: trying to load %s as %s\n",
200 		       filename, lc->desc));
201 	error = lc->ops->load_file(koname, &lf);
202 	if (lf == NULL && error && error != ENOENT)
203 	    goto out;
204 	if (lf == NULL)
205 	    error = lc->ops->load_file(filename, &lf);
206 	if (lf == NULL && error && error != ENOENT)
207 	    goto out;
208 	if (lf) {
209 	    linker_file_sysinit(lf);
210 
211 	    *result = lf;
212 	    error = 0;
213 	    goto out;
214 	}
215     }
216     error = ENOEXEC;		/* format not recognised */
217 
218 out:
219     if (koname)
220 	free(koname, M_LINKER);
221     return error;
222 }
223 
224 linker_file_t
225 linker_find_file_by_name(const char* filename)
226 {
227     linker_file_t lf = 0;
228     char *koname;
229 
230     koname = malloc(strlen(filename) + 4, M_LINKER, M_WAITOK);
231     if (koname == NULL)
232 	goto out;
233     sprintf(koname, "%s.ko", filename);
234 
235     lockmgr(&lock, LK_SHARED, 0, curproc);
236     for (lf = TAILQ_FIRST(&files); lf; lf = TAILQ_NEXT(lf, link)) {
237 	if (!strcmp(lf->filename, koname))
238 	    break;
239 	if (!strcmp(lf->filename, filename))
240 	    break;
241     }
242     lockmgr(&lock, LK_RELEASE, 0, curproc);
243 
244 out:
245     if (koname)
246 	free(koname, M_LINKER);
247     return lf;
248 }
249 
250 linker_file_t
251 linker_find_file_by_id(int fileid)
252 {
253     linker_file_t lf = 0;
254 
255     lockmgr(&lock, LK_SHARED, 0, curproc);
256     for (lf = TAILQ_FIRST(&files); lf; lf = TAILQ_NEXT(lf, link))
257 	if (lf->id == fileid)
258 	    break;
259     lockmgr(&lock, LK_RELEASE, 0, curproc);
260 
261     return lf;
262 }
263 
264 linker_file_t
265 linker_make_file(const char* pathname, void* priv, struct linker_file_ops* ops)
266 {
267     linker_file_t lf = 0;
268     int namelen;
269     const char *filename;
270 
271     filename = rindex(pathname, '/');
272     if (filename && filename[1])
273 	filename++;
274     else
275 	filename = pathname;
276 
277     KLD_DPF(FILE, ("linker_make_file: new file, filename=%s\n", filename));
278     lockmgr(&lock, LK_EXCLUSIVE|LK_RETRY, 0, curproc);
279     namelen = strlen(filename) + 1;
280     lf = malloc(sizeof(struct linker_file) + namelen, M_LINKER, M_WAITOK);
281     if (!lf)
282 	goto out;
283     bzero(lf, sizeof(*lf));
284 
285     lf->refs = 1;
286     lf->userrefs = 0;
287     lf->filename = (char*) (lf + 1);
288     strcpy(lf->filename, filename);
289     lf->id = next_file_id++;
290     lf->ndeps = 0;
291     lf->deps = NULL;
292     STAILQ_INIT(&lf->common);
293     TAILQ_INIT(&lf->modules);
294 
295     lf->priv = priv;
296     lf->ops = ops;
297     TAILQ_INSERT_TAIL(&files, lf, link);
298 
299 out:
300     lockmgr(&lock, LK_RELEASE, 0, curproc);
301     return lf;
302 }
303 
304 int
305 linker_file_unload(linker_file_t file)
306 {
307     module_t mod, next;
308     struct common_symbol* cp;
309     int error = 0;
310     int i;
311 
312     KLD_DPF(FILE, ("linker_file_unload: lf->refs=%d\n", file->refs));
313     lockmgr(&lock, LK_EXCLUSIVE|LK_RETRY, 0, curproc);
314     if (file->refs == 1) {
315 	KLD_DPF(FILE, ("linker_file_unload: file is unloading, informing modules\n"));
316 	/*
317 	 * Inform any modules associated with this file.
318 	 */
319 	for (mod = TAILQ_FIRST(&file->modules); mod; mod = next) {
320 	    next = module_getfnext(mod);
321 
322 	    /*
323 	     * Give the module a chance to veto the unload.
324 	     */
325 	    if (error = module_unload(mod)) {
326 		KLD_DPF(FILE, ("linker_file_unload: module %x vetoes unload\n",
327 			       mod));
328 		lockmgr(&lock, LK_RELEASE, 0, curproc);
329 		goto out;
330 	    }
331 
332 	    module_release(mod);
333 	}
334     }
335 
336     file->refs--;
337     if (file->refs > 0) {
338 	lockmgr(&lock, LK_RELEASE, 0, curproc);
339 	goto out;
340     }
341 
342     TAILQ_REMOVE(&files, file, link);
343     lockmgr(&lock, LK_RELEASE, 0, curproc);
344 
345     for (i = 0; i < file->ndeps; i++)
346 	linker_file_unload(file->deps[i]);
347     free(file->deps, M_LINKER);
348 
349     for (cp = STAILQ_FIRST(&file->common); cp;
350 	 cp = STAILQ_FIRST(&file->common)) {
351 	STAILQ_REMOVE(&file->common, cp, common_symbol, link);
352 	free(cp, M_LINKER);
353     }
354 
355     file->ops->unload(file);
356     free(file, M_LINKER);
357 
358 out:
359     return error;
360 }
361 
362 int
363 linker_file_add_dependancy(linker_file_t file, linker_file_t dep)
364 {
365     linker_file_t* newdeps;
366 
367     newdeps = malloc((file->ndeps + 1) * sizeof(linker_file_t*),
368 		     M_LINKER, M_WAITOK);
369     if (newdeps == NULL)
370 	return ENOMEM;
371     bzero(newdeps, (file->ndeps + 1) * sizeof(linker_file_t*));
372 
373     if (file->deps) {
374 	bcopy(file->deps, newdeps, file->ndeps * sizeof(linker_file_t*));
375 	free(file->deps, M_LINKER);
376     }
377     file->deps = newdeps;
378     file->deps[file->ndeps] = dep;
379     file->ndeps++;
380 
381     return 0;
382 }
383 
384 caddr_t
385 linker_file_lookup_symbol(linker_file_t file, const char* name, int deps)
386 {
387     linker_sym_t sym;
388     linker_symval_t symval;
389     caddr_t address;
390     size_t common_size = 0;
391     int i;
392 
393     KLD_DPF(SYM, ("linker_file_lookup_symbol: file=%x, name=%s, deps=%d\n",
394 		  file, name, deps));
395 
396     if (file->ops->lookup_symbol(file, name, &sym) == 0) {
397 	file->ops->symbol_values(file, sym, &symval);
398 	if (symval.value == 0)
399 	    /*
400 	     * For commons, first look them up in the dependancies and
401 	     * only allocate space if not found there.
402 	     */
403 	    common_size = symval.size;
404 	else {
405 	    KLD_DPF(SYM, ("linker_file_lookup_symbol: symbol.value=%x\n", symval.value));
406 	    return symval.value;
407 	}
408     }
409 
410     if (deps)
411 	for (i = 0; i < file->ndeps; i++) {
412 	    address = linker_file_lookup_symbol(file->deps[i], name, 0);
413 	    if (address) {
414 		KLD_DPF(SYM, ("linker_file_lookup_symbol: deps value=%x\n", address));
415 		return address;
416 	    }
417 	}
418 
419     if (common_size > 0) {
420 	/*
421 	 * This is a common symbol which was not found in the
422 	 * dependancies.  We maintain a simple common symbol table in
423 	 * the file object.
424 	 */
425 	struct common_symbol* cp;
426 
427 	for (cp = STAILQ_FIRST(&file->common); cp;
428 	     cp = STAILQ_NEXT(cp, link))
429 	    if (!strcmp(cp->name, name)) {
430 		KLD_DPF(SYM, ("linker_file_lookup_symbol: old common value=%x\n", cp->address));
431 		return cp->address;
432 	    }
433 
434 	/*
435 	 * Round the symbol size up to align.
436 	 */
437 	common_size = (common_size + sizeof(int) - 1) & -sizeof(int);
438 	cp = malloc(sizeof(struct common_symbol)
439 		    + common_size
440 		    + strlen(name) + 1,
441 		    M_LINKER, M_WAITOK);
442 	if (!cp) {
443 	    KLD_DPF(SYM, ("linker_file_lookup_symbol: nomem\n"));
444 	    return 0;
445 	}
446 	bzero(cp, sizeof(struct common_symbol) + common_size + strlen(name)+ 1);
447 
448 	cp->address = (caddr_t) (cp + 1);
449 	cp->name = cp->address + common_size;
450 	strcpy(cp->name, name);
451 	bzero(cp->address, common_size);
452 	STAILQ_INSERT_TAIL(&file->common, cp, link);
453 
454 	KLD_DPF(SYM, ("linker_file_lookup_symbol: new common value=%x\n", cp->address));
455 	return cp->address;
456     }
457 
458     KLD_DPF(SYM, ("linker_file_lookup_symbol: fail\n"));
459     return 0;
460 }
461 
462 #ifdef DDB
463 /*
464  * DDB Helpers.  DDB has to look across multiple files with their own
465  * symbol tables and string tables.
466  *
467  * Note that we do not obey list locking protocols here.  We really don't
468  * need DDB to hang because somebody's got the lock held.  We'll take the
469  * chance that the files list is inconsistant instead.
470  */
471 
472 int
473 linker_ddb_lookup(char *symstr, linker_sym_t *sym)
474 {
475     linker_file_t lf;
476 
477     for (lf = TAILQ_FIRST(&files); lf; lf = TAILQ_NEXT(lf, link)) {
478 	if (lf->ops->lookup_symbol(lf, symstr, sym) == 0)
479 	    return 0;
480     }
481     return ENOENT;
482 }
483 
484 int
485 linker_ddb_search_symbol(caddr_t value, linker_sym_t *sym, long *diffp)
486 {
487     linker_file_t lf;
488     u_long off = (u_long)value;
489     u_long diff, bestdiff;
490     linker_sym_t best;
491     linker_sym_t es;
492 
493     best = 0;
494     bestdiff = off;
495     for (lf = TAILQ_FIRST(&files); lf; lf = TAILQ_NEXT(lf, link)) {
496 	if (lf->ops->search_symbol(lf, value, &es, &diff) != 0)
497 	    continue;
498 	if (es != 0 && diff < bestdiff) {
499 	    best = es;
500 	    bestdiff = diff;
501 	}
502 	if (bestdiff == 0)
503 	    break;
504     }
505     if (best) {
506 	*sym = best;
507 	*diffp = bestdiff;
508 	return 0;
509     } else {
510 	*sym = 0;
511 	*diffp = off;
512 	return ENOENT;
513     }
514 }
515 
516 int
517 linker_ddb_symbol_values(linker_sym_t sym, linker_symval_t *symval)
518 {
519     linker_file_t lf;
520 
521     for (lf = TAILQ_FIRST(&files); lf; lf = TAILQ_NEXT(lf, link)) {
522 	if (lf->ops->symbol_values(lf, sym, symval) == 0)
523 	    return 0;
524     }
525     return ENOENT;
526 }
527 
528 #endif
529 
530 /*
531  * Syscalls.
532  */
533 
534 int
535 kldload(struct proc* p, struct kldload_args* uap)
536 {
537     char* filename = NULL;
538     linker_file_t lf;
539     int error = 0;
540 
541     p->p_retval[0] = -1;
542 
543     if (securelevel > 0)
544 	return EPERM;
545 
546     if (error = suser(p->p_ucred, &p->p_acflag))
547 	return error;
548 
549     filename = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
550     if (error = copyinstr(SCARG(uap, file), filename, MAXPATHLEN, NULL))
551 	goto out;
552 
553     if (error = linker_load_file(filename, &lf))
554 	goto out;
555 
556     lf->userrefs++;
557     p->p_retval[0] = lf->id;
558 
559 out:
560     if (filename)
561 	free(filename, M_TEMP);
562     return error;
563 }
564 
565 int
566 kldunload(struct proc* p, struct kldunload_args* uap)
567 {
568     linker_file_t lf;
569     int error = 0;
570 
571     if (securelevel > 0)
572 	return EPERM;
573 
574     if (error = suser(p->p_ucred, &p->p_acflag))
575 	return error;
576 
577     lf = linker_find_file_by_id(SCARG(uap, fileid));
578     if (lf) {
579 	KLD_DPF(FILE, ("kldunload: lf->userrefs=%d\n", lf->userrefs));
580 	if (lf->userrefs == 0) {
581 	    printf("linkerunload: attempt to unload file which was not loaded by user\n");
582 	    error = EBUSY;
583 	    goto out;
584 	}
585 	lf->userrefs--;
586 	error = linker_file_unload(lf);
587     } else
588 	error = ENOENT;
589 
590 out:
591     return error;
592 }
593 
594 int
595 kldfind(struct proc* p, struct kldfind_args* uap)
596 {
597     char* filename = NULL;
598     linker_file_t lf;
599     int error = 0;
600 
601     p->p_retval[0] = -1;
602 
603     filename = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
604     if (error = copyinstr(SCARG(uap, file), filename, MAXPATHLEN, NULL))
605 	goto out;
606 
607     lf = linker_find_file_by_name(filename);
608     if (lf)
609 	p->p_retval[0] = lf->id;
610     else
611 	error = ENOENT;
612 
613 out:
614     if (filename)
615 	free(filename, M_TEMP);
616     return error;
617 }
618 
619 int
620 kldnext(struct proc* p, struct kldnext_args* uap)
621 {
622     linker_file_t lf;
623     int error = 0;
624 
625     if (SCARG(uap, fileid) == 0) {
626 	if (TAILQ_FIRST(&files))
627 	    p->p_retval[0] = TAILQ_FIRST(&files)->id;
628 	else
629 	    p->p_retval[0] = 0;
630 	return 0;
631     }
632 
633     lf = linker_find_file_by_id(SCARG(uap, fileid));
634     if (lf) {
635 	if (TAILQ_NEXT(lf, link))
636 	    p->p_retval[0] = TAILQ_NEXT(lf, link)->id;
637 	else
638 	    p->p_retval[0] = 0;
639     } else
640 	error = ENOENT;
641 
642     return error;
643 }
644 
645 int
646 kldstat(struct proc* p, struct kldstat_args* uap)
647 {
648     linker_file_t lf;
649     int error = 0;
650     int version;
651     struct kld_file_stat* stat;
652     int namelen;
653 
654     lf = linker_find_file_by_id(SCARG(uap, fileid));
655     if (!lf) {
656 	error = ENOENT;
657 	goto out;
658     }
659 
660     stat = SCARG(uap, stat);
661 
662     /*
663      * Check the version of the user's structure.
664      */
665     if (error = copyin(&stat->version, &version, sizeof(version)))
666 	goto out;
667     if (version != sizeof(struct kld_file_stat)) {
668 	error = EINVAL;
669 	goto out;
670     }
671 
672     namelen = strlen(lf->filename) + 1;
673     if (namelen > MAXPATHLEN)
674 	namelen = MAXPATHLEN;
675     if (error = copyout(lf->filename, &stat->name[0], namelen))
676 	goto out;
677     if (error = copyout(&lf->refs, &stat->refs, sizeof(int)))
678 	goto out;
679     if (error = copyout(&lf->id, &stat->id, sizeof(int)))
680 	goto out;
681     if (error = copyout(&lf->address, &stat->address, sizeof(caddr_t)))
682 	goto out;
683     if (error = copyout(&lf->size, &stat->size, sizeof(size_t)))
684 	goto out;
685 
686     p->p_retval[0] = 0;
687 
688 out:
689     return error;
690 }
691 
692 int
693 kldfirstmod(struct proc* p, struct kldfirstmod_args* uap)
694 {
695     linker_file_t lf;
696     int error = 0;
697 
698     lf = linker_find_file_by_id(SCARG(uap, fileid));
699     if (lf) {
700 	if (TAILQ_FIRST(&lf->modules))
701 	    p->p_retval[0] = module_getid(TAILQ_FIRST(&lf->modules));
702 	else
703 	    p->p_retval[0] = 0;
704     } else
705 	error = ENOENT;
706 
707     return error;
708 }
709 
710 /*
711  * Preloaded module support
712  */
713 
714 static void
715 linker_preload(void* arg)
716 {
717     caddr_t		modptr;
718     char		*modname;
719     char		*modtype;
720     linker_file_t	lf;
721     linker_class_t	lc;
722     int			error;
723     struct linker_set	*sysinits;
724     struct sysinit	**sipp;
725     moduledata_t	*moddata;
726 
727     modptr = NULL;
728     while ((modptr = preload_search_next_name(modptr)) != NULL) {
729 	modname = (char *)preload_search_info(modptr, MODINFO_NAME);
730 	modtype = (char *)preload_search_info(modptr, MODINFO_TYPE);
731 	if (modname == NULL) {
732 	    printf("Preloaded module at %p does not have a name!\n", modptr);
733 	    continue;
734 	}
735 	if (modtype == NULL) {
736 	    printf("Preloaded module at %p does not have a type!\n", modptr);
737 	    continue;
738 	}
739 	printf("Preloaded %s \"%s\" at %p.\n", modtype, modname, modptr);
740 	lf = linker_find_file_by_name(modname);
741 	if (lf) {
742 	    lf->userrefs++;
743 	    continue;
744 	}
745 	lf = NULL;
746 	for (lc = TAILQ_FIRST(&classes); lc; lc = TAILQ_NEXT(lc, link)) {
747 	    error = lc->ops->load_file(modname, &lf);
748 	    if (error) {
749 		lf = NULL;
750 		break;
751 	    }
752 	}
753 	if (lf) {
754 	    lf->userrefs++;
755 
756 	    sysinits = (struct linker_set*)
757 		linker_file_lookup_symbol(lf, "sysinit_set", 0);
758 	    if (sysinits) {
759 		/* HACK ALERT!
760 		 * This is to set the sysinit moduledata so that the module
761 		 * can attach itself to the correct containing file.
762 		 * The sysinit could be run at *any* time.
763 		 */
764 		for (sipp = (struct sysinit **)sysinits->ls_items; *sipp; sipp++) {
765 		    if ((*sipp)->func == module_register_init) {
766 			moddata = (*sipp)->udata;
767 			moddata->_file = lf;
768 		    }
769 		}
770 		sysinit_add((struct sysinit **)sysinits->ls_items);
771 	    }
772 	}
773     }
774 }
775 
776 SYSINIT(preload, SI_SUB_KLD, SI_ORDER_MIDDLE, linker_preload, 0);
777 
778 /*
779  * Search for a not-loaded module by name.
780  *
781  * Modules may be found in the following locations:
782  *
783  * - preloaded (result is just the module name)
784  * - on disk (result is full path to module)
785  *
786  * If the module name is qualified in any way (contains path, etc.)
787  * the we simply return a copy of it.
788  *
789  * The search path can be manipulated via sysctl.  Note that we use the ';'
790  * character as a separator to be consistent with the bootloader.
791  */
792 
793 static char linker_path[MAXPATHLEN + 1] = "/;/boot/;/modules/";
794 
795 SYSCTL_STRING(_kern, OID_AUTO, module_path, CTLFLAG_RW, linker_path,
796 	      sizeof(linker_path), "module load search path");
797 
798 static char *
799 linker_strdup(const char *str)
800 {
801     char	*result;
802 
803     if ((result = malloc((strlen(str) + 1), M_LINKER, M_WAITOK)) != NULL)
804 	strcpy(result, str);
805     return(result);
806 }
807 
808 char *
809 linker_search_path(const char *name)
810 {
811     struct nameidata	nd;
812     struct proc		*p = curproc;	/* XXX */
813     char		*cp, *ep, *result;
814     int			error;
815     enum vtype		type;
816 
817     /* qualified at all? */
818     if (index(name, '/'))
819 	return(linker_strdup(name));
820 
821     /* traverse the linker path */
822     cp = linker_path;
823     for (;;) {
824 
825 	/* find the end of this component */
826 	for (ep = cp; (*ep != 0) && (*ep != ';'); ep++)
827 	    ;
828 	result = malloc((strlen(name) + (ep - cp) + 1), M_LINKER, M_WAITOK);
829 	if (result == NULL)	/* actually ENOMEM */
830 	    return(NULL);
831 
832 	strncpy(result, cp, ep - cp);
833 	strcpy(result + (ep - cp), name);
834 
835 	/*
836 	 * Attempt to open the file, and return the path if we succeed and it's
837 	 * a regular file.
838 	 */
839 	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, result, p);
840 	error = vn_open(&nd, FREAD, 0);
841 	if (error == 0) {
842 	    type = nd.ni_vp->v_type;
843 	    VOP_UNLOCK(nd.ni_vp, 0, p);
844 	    vn_close(nd.ni_vp, FREAD, p->p_ucred, p);
845 	    if (type == VREG)
846 		return(result);
847 	}
848 	free(result, M_LINKER);
849 
850 	if (*ep == 0)
851 	    break;
852 	cp = ep + 1;
853     }
854     return(NULL);
855 }
856