xref: /freebsd/sys/dev/ksyms/ksyms.c (revision 0f502d1c) 
1 /*-
2  * Copyright (c) 2008-2009, Stacey Son <sson@freebsd.org>
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  * $FreeBSD$
27  */
28 
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 
33 #include <sys/conf.h>
34 #include <sys/elf.h>
35 #include <sys/ksyms.h>
36 #include <sys/linker.h>
37 #include <sys/malloc.h>
38 #include <sys/mman.h>
39 #include <sys/module.h>
40 #include <sys/mutex.h>
41 #include <sys/proc.h>
42 #include <sys/queue.h>
43 #include <sys/resourcevar.h>
44 #include <sys/stat.h>
45 #include <sys/uio.h>
46 
47 #include <machine/elf.h>
48 
49 #include <vm/pmap.h>
50 #include <vm/vm.h>
51 #include <vm/vm_extern.h>
52 #include <vm/vm_map.h>
53 
54 #include "linker_if.h"
55 
56 #define SHDR_NULL	0
57 #define SHDR_SYMTAB	1
58 #define SHDR_STRTAB	2
59 #define SHDR_SHSTRTAB	3
60 
61 #define SHDR_NUM	4
62 
63 #define STR_SYMTAB	".symtab"
64 #define STR_STRTAB	".strtab"
65 #define STR_SHSTRTAB	".shstrtab"
66 
67 #define KSYMS_DNAME	"ksyms"
68 
69 static	d_open_t 	ksyms_open;
70 static	d_read_t	ksyms_read;
71 static	d_close_t	ksyms_close;
72 static	d_ioctl_t	ksyms_ioctl;
73 static	d_mmap_t	ksyms_mmap;
74 
75 static struct cdevsw ksyms_cdevsw = {
76     .d_version	=	D_VERSION,
77     .d_flags	=	D_PSEUDO | D_TRACKCLOSE,
78     .d_open	=	ksyms_open,
79     .d_close	=	ksyms_close,
80     .d_read	=	ksyms_read,
81     .d_ioctl	=	ksyms_ioctl,
82     .d_mmap	=	ksyms_mmap,
83     .d_name	=	KSYMS_DNAME
84 };
85 
86 struct ksyms_softc {
87 	LIST_ENTRY(ksyms_softc)	sc_list;
88 	vm_offset_t 		sc_uaddr;
89 	size_t 			sc_usize;
90 	pmap_t			sc_pmap;
91 	struct proc	       *sc_proc;
92 };
93 
94 static struct mtx 		 ksyms_mtx;
95 static struct cdev 		*ksyms_dev;
96 static LIST_HEAD(, ksyms_softc)	 ksyms_list =
97 	LIST_HEAD_INITIALIZER(ksyms_list);
98 
99 static const char 	ksyms_shstrtab[] =
100 	"\0" STR_SYMTAB "\0" STR_STRTAB "\0" STR_SHSTRTAB "\0";
101 
102 struct ksyms_hdr {
103 	Elf_Ehdr	kh_ehdr;
104 	Elf_Phdr	kh_txtphdr;
105 	Elf_Phdr	kh_datphdr;
106 	Elf_Shdr	kh_shdr[SHDR_NUM];
107 	char		kh_shstrtab[sizeof(ksyms_shstrtab)];
108 };
109 
110 struct tsizes {
111 	size_t		ts_symsz;
112 	size_t		ts_strsz;
113 };
114 
115 struct toffsets {
116 	vm_offset_t	to_symoff;
117 	vm_offset_t	to_stroff;
118 	unsigned	to_stridx;
119 	size_t		to_resid;
120 };
121 
122 static MALLOC_DEFINE(M_KSYMS, "KSYMS", "Kernel Symbol Table");
123 
124 /*
125  * Get the symbol and string table sizes for a kernel module. Add it to the
126  * running total.
127  */
128 static int
129 ksyms_size_permod(linker_file_t lf, void *arg)
130 {
131 	struct tsizes *ts;
132 	const Elf_Sym *symtab;
133 	caddr_t strtab;
134 	long syms;
135 
136 	ts = arg;
137 
138 	syms = LINKER_SYMTAB_GET(lf, &symtab);
139 	ts->ts_symsz += syms * sizeof(Elf_Sym);
140 	ts->ts_strsz += LINKER_STRTAB_GET(lf, &strtab);
141 
142 	return (0);
143 }
144 
145 /*
146  * For kernel module get the symbol and string table sizes, returning the
147  * totals in *ts.
148  */
149 static void
150 ksyms_size_calc(struct tsizes *ts)
151 {
152 	ts->ts_symsz = 0;
153 	ts->ts_strsz = 0;
154 
155 	(void) linker_file_foreach(ksyms_size_permod, ts);
156 }
157 
158 #define KSYMS_EMIT(src, des, sz) do {				\
159 		copyout(src, (void *)des, sz);			\
160 		des += sz;					\
161 	} while (0)
162 
163 #define SYMBLKSZ	256 * sizeof (Elf_Sym)
164 
165 /*
166  * For a kernel module, add the symbol and string tables into the
167  * snapshot buffer.  Fix up the offsets in the tables.
168  */
169 static int
170 ksyms_add(linker_file_t lf, void *arg)
171 {
172 	struct toffsets *to;
173 	const Elf_Sym *symtab;
174 	Elf_Sym *symp;
175 	caddr_t strtab;
176 	long symsz;
177 	size_t strsz, numsyms;
178 	linker_symval_t symval;
179 	char *buf;
180 	int i, nsyms, len;
181 
182 	to = arg;
183 
184 	MOD_SLOCK;
185 	numsyms =  LINKER_SYMTAB_GET(lf, &symtab);
186 	strsz = LINKER_STRTAB_GET(lf, &strtab);
187 	symsz = numsyms * sizeof(Elf_Sym);
188 
189 	buf = malloc(SYMBLKSZ, M_KSYMS, M_WAITOK);
190 
191 	while (symsz > 0) {
192 		len = min(SYMBLKSZ, symsz);
193 		bcopy(symtab, buf, len);
194 
195 		/*
196 		 * Fix up symbol table for kernel modules:
197 		 *   string offsets need adjusted
198 		 *   symbol values made absolute
199 		 */
200 		symp = (Elf_Sym *) buf;
201 		nsyms = len / sizeof (Elf_Sym);
202 		for (i = 0; i < nsyms; i++) {
203 			symp[i].st_name += to->to_stridx;
204 			if (lf->id > 1 && LINKER_SYMBOL_VALUES(lf,
205 				(c_linker_sym_t) &symtab[i], &symval) == 0) {
206 				symp[i].st_value = (uintptr_t) symval.value;
207 			}
208 		}
209 
210 		if (len > to->to_resid) {
211 			MOD_SUNLOCK;
212 			free(buf, M_KSYMS);
213 			return (ENXIO);
214 		} else
215 			to->to_resid -= len;
216 		KSYMS_EMIT(buf, to->to_symoff, len);
217 
218 		symtab += nsyms;
219 		symsz -= len;
220 	}
221 	free(buf, M_KSYMS);
222 	MOD_SUNLOCK;
223 
224 	if (strsz > to->to_resid)
225 		return (ENXIO);
226 	else
227 		to->to_resid -= strsz;
228 	KSYMS_EMIT(strtab, to->to_stroff, strsz);
229 	to->to_stridx += strsz;
230 
231 	return (0);
232 }
233 
234 /*
235  * Create a single ELF symbol table for the kernel and kernel modules loaded
236  * at this time. Write this snapshot out in the process address space. Return
237  * 0 on success, otherwise error.
238  */
239 static int
240 ksyms_snapshot(struct tsizes *ts, vm_offset_t uaddr, size_t resid)
241 {
242 
243 	struct ksyms_hdr *hdr;
244 	struct toffsets	 to;
245 	int error = 0;
246 
247 	/* Be kernel stack friendly */
248 	hdr = malloc(sizeof (*hdr), M_KSYMS, M_WAITOK|M_ZERO);
249 
250 	/*
251 	 * Create the ELF header.
252 	 */
253 	hdr->kh_ehdr.e_ident[EI_PAD] = 0;
254 	hdr->kh_ehdr.e_ident[EI_MAG0] = ELFMAG0;
255 	hdr->kh_ehdr.e_ident[EI_MAG1] = ELFMAG1;
256 	hdr->kh_ehdr.e_ident[EI_MAG2] = ELFMAG2;
257 	hdr->kh_ehdr.e_ident[EI_MAG3] = ELFMAG3;
258 	hdr->kh_ehdr.e_ident[EI_DATA] = ELF_DATA;
259 	hdr->kh_ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
260 	hdr->kh_ehdr.e_ident[EI_CLASS] = ELF_CLASS;
261 	hdr->kh_ehdr.e_ident[EI_VERSION] = EV_CURRENT;
262 	hdr->kh_ehdr.e_ident[EI_ABIVERSION] = 0;
263 	hdr->kh_ehdr.e_type = ET_EXEC;
264 	hdr->kh_ehdr.e_machine = ELF_ARCH;
265 	hdr->kh_ehdr.e_version = EV_CURRENT;
266 	hdr->kh_ehdr.e_entry = 0;
267 	hdr->kh_ehdr.e_phoff = offsetof(struct ksyms_hdr, kh_txtphdr);
268 	hdr->kh_ehdr.e_shoff = offsetof(struct ksyms_hdr, kh_shdr);
269 	hdr->kh_ehdr.e_flags = 0;
270 	hdr->kh_ehdr.e_ehsize = sizeof(Elf_Ehdr);
271 	hdr->kh_ehdr.e_phentsize = sizeof(Elf_Phdr);
272 	hdr->kh_ehdr.e_phnum = 2;	/* Text and Data */
273 	hdr->kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
274 	hdr->kh_ehdr.e_shnum = SHDR_NUM;
275 	hdr->kh_ehdr.e_shstrndx = SHDR_SHSTRTAB;
276 
277 	/*
278 	 * Add both the text and data Program headers.
279 	 */
280 	hdr->kh_txtphdr.p_type = PT_LOAD;
281 	/* XXX - is there a way to put the actual .text addr/size here? */
282 	hdr->kh_txtphdr.p_vaddr = 0;
283 	hdr->kh_txtphdr.p_memsz = 0;
284 	hdr->kh_txtphdr.p_flags = PF_R | PF_X;
285 
286 	hdr->kh_datphdr.p_type = PT_LOAD;
287 	/* XXX - is there a way to put the actual .data addr/size here? */
288 	hdr->kh_datphdr.p_vaddr = 0;
289 	hdr->kh_datphdr.p_memsz = 0;
290 	hdr->kh_datphdr.p_flags = PF_R | PF_W | PF_X;
291 
292 	/*
293 	 * Add the Section headers: null, symtab, strtab, shstrtab,
294 	 */
295 
296 	/* First section header - null */
297 
298 	/* Second section header - symtab */
299 	hdr->kh_shdr[SHDR_SYMTAB].sh_name = 1; /* String offset (skip null) */
300 	hdr->kh_shdr[SHDR_SYMTAB].sh_type = SHT_SYMTAB;
301 	hdr->kh_shdr[SHDR_SYMTAB].sh_flags = 0;
302 	hdr->kh_shdr[SHDR_SYMTAB].sh_addr = 0;
303 	hdr->kh_shdr[SHDR_SYMTAB].sh_offset = sizeof(*hdr);
304 	hdr->kh_shdr[SHDR_SYMTAB].sh_size = ts->ts_symsz;
305 	hdr->kh_shdr[SHDR_SYMTAB].sh_link = SHDR_STRTAB;
306 	hdr->kh_shdr[SHDR_SYMTAB].sh_info = ts->ts_symsz / sizeof(Elf_Sym);
307 	hdr->kh_shdr[SHDR_SYMTAB].sh_addralign = sizeof(long);
308 	hdr->kh_shdr[SHDR_SYMTAB].sh_entsize = sizeof(Elf_Sym);
309 
310 	/* Third section header - strtab */
311 	hdr->kh_shdr[SHDR_STRTAB].sh_name = 1 + sizeof(STR_SYMTAB);
312 	hdr->kh_shdr[SHDR_STRTAB].sh_type = SHT_STRTAB;
313 	hdr->kh_shdr[SHDR_STRTAB].sh_flags = 0;
314 	hdr->kh_shdr[SHDR_STRTAB].sh_addr = 0;
315 	hdr->kh_shdr[SHDR_STRTAB].sh_offset =
316 	    hdr->kh_shdr[SHDR_SYMTAB].sh_offset + ts->ts_symsz;
317 	hdr->kh_shdr[SHDR_STRTAB].sh_size = ts->ts_strsz;
318 	hdr->kh_shdr[SHDR_STRTAB].sh_link = 0;
319 	hdr->kh_shdr[SHDR_STRTAB].sh_info = 0;
320 	hdr->kh_shdr[SHDR_STRTAB].sh_addralign = sizeof(char);
321 	hdr->kh_shdr[SHDR_STRTAB].sh_entsize = 0;
322 
323 	/* Fourth section - shstrtab */
324 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_name = 1 + sizeof(STR_SYMTAB) +
325 	    sizeof(STR_STRTAB);
326 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_type = SHT_STRTAB;
327 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_flags = 0;
328 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_addr = 0;
329 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_offset =
330 	    offsetof(struct ksyms_hdr, kh_shstrtab);
331 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_size = sizeof(ksyms_shstrtab);
332 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_link = 0;
333 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_info = 0;
334 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_addralign = 0 /* sizeof(char) */;
335 	hdr->kh_shdr[SHDR_SHSTRTAB].sh_entsize = 0;
336 
337 	/* Copy shstrtab into the header */
338 	bcopy(ksyms_shstrtab, hdr->kh_shstrtab, sizeof(ksyms_shstrtab));
339 
340 	to.to_symoff = uaddr + hdr->kh_shdr[SHDR_SYMTAB].sh_offset;
341 	to.to_stroff = uaddr + hdr->kh_shdr[SHDR_STRTAB].sh_offset;
342 	to.to_stridx = 0;
343 	if (sizeof(struct ksyms_hdr) > resid) {
344 		free(hdr, M_KSYMS);
345 		return (ENXIO);
346 	}
347 	to.to_resid = resid - sizeof(struct ksyms_hdr);
348 
349 	/* Emit Header */
350 	copyout(hdr, (void *)uaddr, sizeof(struct ksyms_hdr));
351 
352 	free(hdr, M_KSYMS);
353 
354 	/* Add symbol and string tables for each kernelmodule */
355 	error = linker_file_foreach(ksyms_add, &to);
356 
357 	if (to.to_resid != 0)
358 		return (ENXIO);
359 
360 	return (error);
361 }
362 
363 static void
364 ksyms_cdevpriv_dtr(void *data)
365 {
366 	struct ksyms_softc *sc;
367 
368 	sc = (struct ksyms_softc *)data;
369 
370 	mtx_lock(&ksyms_mtx);
371 	LIST_REMOVE(sc, sc_list);
372 	mtx_unlock(&ksyms_mtx);
373 	free(sc, M_KSYMS);
374 }
375 
376 /* ARGSUSED */
377 static int
378 ksyms_open(struct cdev *dev, int flags, int fmt __unused, struct thread *td)
379 {
380 	struct tsizes ts;
381 	size_t total_elf_sz;
382 	int error, try;
383 	struct ksyms_softc *sc;
384 
385 	/*
386 	 *  Limit one open() per process. The process must close()
387 	 *  before open()'ing again.
388 	 */
389 	mtx_lock(&ksyms_mtx);
390 	LIST_FOREACH(sc, &ksyms_list, sc_list) {
391 		if (sc->sc_proc == td->td_proc) {
392 			mtx_unlock(&ksyms_mtx);
393 			return (EBUSY);
394 		}
395 	}
396 
397 	sc = (struct ksyms_softc *) malloc(sizeof (*sc), M_KSYMS,
398 	    M_NOWAIT|M_ZERO);
399 
400 	if (sc == NULL) {
401 		mtx_unlock(&ksyms_mtx);
402 		return (ENOMEM);
403 	}
404 	sc->sc_proc = td->td_proc;
405 	sc->sc_pmap = &td->td_proc->p_vmspace->vm_pmap;
406 	LIST_INSERT_HEAD(&ksyms_list, sc, sc_list);
407 	mtx_unlock(&ksyms_mtx);
408 
409 	error = devfs_set_cdevpriv(sc, ksyms_cdevpriv_dtr);
410 	if (error)
411 		goto failed;
412 
413 	/*
414 	 * MOD_SLOCK doesn't work here (because of a lock reversal with
415 	 * KLD_SLOCK).  Therefore, simply try upto 3 times to get a "clean"
416 	 * snapshot of the kernel symbol table.  This should work fine in the
417 	 * rare case of a kernel module being loaded/unloaded at the same
418 	 * time.
419 	 */
420 	for(try = 0; try < 3; try++) {
421 		/*
422 	 	* Map a buffer in the calling process memory space and
423 	 	* create a snapshot of the kernel symbol table in it.
424 	 	*/
425 
426 		/* Compute the size of buffer needed. */
427 		ksyms_size_calc(&ts);
428 		total_elf_sz = sizeof(struct ksyms_hdr) + ts.ts_symsz +
429 			ts.ts_strsz;
430 
431 		error = copyout_map(td, &(sc->sc_uaddr),
432 				(vm_size_t) total_elf_sz);
433 		if (error)
434 			break;
435 		sc->sc_usize = total_elf_sz;
436 
437 		error = ksyms_snapshot(&ts, sc->sc_uaddr, total_elf_sz);
438 		if (!error)  {
439 			/* Successful Snapshot */
440 			return (0);
441 		}
442 
443 		/* Snapshot failed, unmap the memory and try again */
444 		(void) copyout_unmap(td, sc->sc_uaddr, sc->sc_usize);
445 	}
446 
447 failed:
448 	ksyms_cdevpriv_dtr(sc);
449 	return (error);
450 }
451 
452 /* ARGSUSED */
453 static int
454 ksyms_read(struct cdev *dev, struct uio *uio, int flags __unused)
455 {
456 	int error;
457 	size_t len, sz;
458 	struct ksyms_softc *sc;
459 	off_t off;
460 	char *buf;
461 	vm_size_t ubase;
462 
463 	error = devfs_get_cdevpriv((void **)&sc);
464 	if (error)
465 		return (error);
466 
467 	off = uio->uio_offset;
468 	len = uio->uio_resid;
469 
470 	if (off < 0 || off > sc->sc_usize)
471 		return (EFAULT);
472 
473 	if (len > (sc->sc_usize - off))
474 		len = sc->sc_usize - off;
475 
476 	if (len == 0)
477 		return (0);
478 
479 	/*
480 	 * Since the snapshot buffer is in the user space we have to copy it
481 	 * in to the kernel and then back out.  The extra copy saves valuable
482 	 * kernel memory.
483 	 */
484 	buf = malloc(PAGE_SIZE, M_KSYMS, M_WAITOK);
485 	ubase = sc->sc_uaddr + off;
486 
487 	while (len) {
488 
489 		sz = min(PAGE_SIZE, len);
490 		if (copyin((void *)ubase, buf, sz))
491 			error = EFAULT;
492 		else
493 			error = uiomove(buf, sz, uio);
494 
495 		if (error)
496 			break;
497 
498 		len -= sz;
499 		ubase += sz;
500 	}
501 	free(buf, M_KSYMS);
502 
503 	return (error);
504 }
505 
506 /* ARGSUSED */
507 static int
508 ksyms_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int32_t flag __unused,
509     struct thread *td __unused)
510 {
511 	int error = 0;
512 	struct ksyms_softc *sc;
513 
514 	error = devfs_get_cdevpriv((void **)&sc);
515 	if (error)
516 		return (error);
517 
518 	switch (cmd) {
519 	case KIOCGSIZE:
520 		/*
521 		 * Return the size (in bytes) of the symbol table
522 		 * snapshot.
523 		 */
524 		*(size_t *)data = sc->sc_usize;
525 		break;
526 
527 	case KIOCGADDR:
528 		/*
529 		 * Return the address of the symbol table snapshot.
530 		 * XXX - compat32 version of this?
531 		 */
532 		*(void **)data = (void *)sc->sc_uaddr;
533 		break;
534 
535 	default:
536 		error = ENOTTY;
537 		break;
538 	}
539 
540 	return (error);
541 }
542 
543 /* ARGUSED */
544 static int
545 ksyms_mmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
546 		int prot __unused, vm_memattr_t *memattr __unused)
547 {
548     	struct ksyms_softc *sc;
549 	int error;
550 
551 	error = devfs_get_cdevpriv((void **)&sc);
552 	if (error)
553 		return (error);
554 
555 	/*
556 	 * XXX mmap() will actually map the symbol table into the process
557 	 * address space again.
558 	 */
559 	if (offset > round_page(sc->sc_usize) ||
560 	    (*paddr = pmap_extract(sc->sc_pmap,
561 	    (vm_offset_t)sc->sc_uaddr + offset)) == 0)
562 		return (-1);
563 
564 	return (0);
565 }
566 
567 /* ARGUSED */
568 static int
569 ksyms_close(struct cdev *dev, int flags __unused, int fmt __unused,
570 		struct thread *td)
571 {
572 	int error = 0;
573 	struct ksyms_softc *sc;
574 
575 	error = devfs_get_cdevpriv((void **)&sc);
576 	if (error)
577 		return (error);
578 
579 	/* Unmap the buffer from the process address space. */
580 	error = copyout_unmap(td, sc->sc_uaddr, sc->sc_usize);
581 
582 	devfs_clear_cdevpriv();
583 
584 	return (error);
585 }
586 
587 /* ARGSUSED */
588 static int
589 ksyms_modevent(module_t mod __unused, int type, void *data __unused)
590 {
591 	int error = 0;
592 
593 	switch (type) {
594 	case MOD_LOAD:
595 		mtx_init(&ksyms_mtx, "KSyms mtx", NULL, MTX_DEF);
596 		ksyms_dev = make_dev(&ksyms_cdevsw, 0, UID_ROOT, GID_WHEEL,
597 		    0444, KSYMS_DNAME);
598 		break;
599 
600 	case MOD_UNLOAD:
601 		if (!LIST_EMPTY(&ksyms_list))
602 			return (EBUSY);
603 		destroy_dev(ksyms_dev);
604 		mtx_destroy(&ksyms_mtx);
605 		break;
606 
607 	case MOD_SHUTDOWN:
608 		break;
609 
610 	default:
611 		error = EOPNOTSUPP;
612 		break;
613 	}
614 	return (error);
615 }
616 
617 DEV_MODULE(ksyms, ksyms_modevent, NULL);
618 MODULE_VERSION(ksyms, 1);
619