sysv_shm.c revision 71038 
1/* $FreeBSD: head/sys/kern/sysv_shm.c 71038 2001-01-14 18:04:30Z des $ */
2/*	$NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $	*/
3
4/*
5 * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *	This product includes software developed by Adam Glass and Charles
18 *	Hannum.
19 * 4. The names of the authors may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#include "opt_compat.h"
35#include "opt_rlimit.h"
36#include "opt_sysvipc.h"
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/sysproto.h>
41#include <sys/kernel.h>
42#include <sys/sysctl.h>
43#include <sys/shm.h>
44#include <sys/proc.h>
45#include <sys/malloc.h>
46#include <sys/mman.h>
47#include <sys/stat.h>
48#include <sys/syscall.h>
49#include <sys/sysent.h>
50#include <sys/jail.h>
51
52#include <vm/vm.h>
53#include <vm/vm_param.h>
54#include <sys/lock.h>
55#include <vm/pmap.h>
56#include <vm/vm_object.h>
57#include <vm/vm_map.h>
58#include <vm/vm_page.h>
59#include <vm/vm_pager.h>
60
61static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
62
63struct oshmctl_args;
64static int oshmctl __P((struct proc *p, struct oshmctl_args *uap));
65
66static int shmget_allocate_segment __P((struct proc *p, struct shmget_args *uap, int mode));
67static int shmget_existing __P((struct proc *p, struct shmget_args *uap, int mode, int segnum));
68
69/* XXX casting to (sy_call_t *) is bogus, as usual. */
70static sy_call_t *shmcalls[] = {
71	(sy_call_t *)shmat, (sy_call_t *)oshmctl,
72	(sy_call_t *)shmdt, (sy_call_t *)shmget,
73	(sy_call_t *)shmctl
74};
75
76#define	SHMSEG_FREE     	0x0200
77#define	SHMSEG_REMOVED  	0x0400
78#define	SHMSEG_ALLOCATED	0x0800
79#define	SHMSEG_WANTED		0x1000
80
81static int shm_last_free, shm_nused, shm_committed, shmalloced;
82static struct shmid_ds	*shmsegs;
83
84struct shm_handle {
85	/* vm_offset_t kva; */
86	vm_object_t shm_object;
87};
88
89struct shmmap_state {
90	vm_offset_t va;
91	int shmid;
92};
93
94static void shm_deallocate_segment __P((struct shmid_ds *));
95static int shm_find_segment_by_key __P((key_t));
96static struct shmid_ds *shm_find_segment_by_shmid __P((int));
97static int shm_delete_mapping __P((struct proc *, struct shmmap_state *));
98static void shmrealloc __P((void));
99static void shminit __P((void));
100static int sysvshm_modload __P((struct module *, int, void *));
101static int shmunload __P((void));
102static void shmexit_myhook __P((struct proc *p));
103static void shmfork_myhook __P((struct proc *p1, struct proc *p2));
104
105/*
106 * Tuneable values
107 */
108#ifndef SHMMAXPGS
109#define	SHMMAXPGS	1024	/* XXX increase this, it's not in kva! */
110#endif
111#ifndef SHMMAX
112#define	SHMMAX	(SHMMAXPGS*PAGE_SIZE)
113#endif
114#ifndef SHMMIN
115#define	SHMMIN	1
116#endif
117#ifndef SHMMNI
118#define	SHMMNI	96
119#endif
120#ifndef SHMSEG
121#define	SHMSEG	64
122#endif
123#ifndef SHMALL
124#define	SHMALL	(SHMMAXPGS)
125#endif
126
127struct	shminfo shminfo = {
128	SHMMAX,
129	SHMMIN,
130	SHMMNI,
131	SHMSEG,
132	SHMALL
133};
134
135static int shm_use_phys;
136
137SYSCTL_DECL(_kern_ipc);
138SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, "");
139SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, "");
140SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0, "");
141SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0, "");
142SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, "");
143SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0, "");
144
145static int
146shm_find_segment_by_key(key)
147	key_t key;
148{
149	int i;
150
151	for (i = 0; i < shmalloced; i++)
152		if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
153		    shmsegs[i].shm_perm.key == key)
154			return i;
155	return -1;
156}
157
158static struct shmid_ds *
159shm_find_segment_by_shmid(shmid)
160	int shmid;
161{
162	int segnum;
163	struct shmid_ds *shmseg;
164
165	segnum = IPCID_TO_IX(shmid);
166	if (segnum < 0 || segnum >= shmalloced)
167		return NULL;
168	shmseg = &shmsegs[segnum];
169	if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
170	    != SHMSEG_ALLOCATED ||
171	    shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
172		return NULL;
173	return shmseg;
174}
175
176static void
177shm_deallocate_segment(shmseg)
178	struct shmid_ds *shmseg;
179{
180	struct shm_handle *shm_handle;
181	size_t size;
182
183	shm_handle = shmseg->shm_internal;
184	vm_object_deallocate(shm_handle->shm_object);
185	free((caddr_t)shm_handle, M_SHM);
186	shmseg->shm_internal = NULL;
187	size = round_page(shmseg->shm_segsz);
188	shm_committed -= btoc(size);
189	shm_nused--;
190	shmseg->shm_perm.mode = SHMSEG_FREE;
191}
192
193static int
194shm_delete_mapping(p, shmmap_s)
195	struct proc *p;
196	struct shmmap_state *shmmap_s;
197{
198	struct shmid_ds *shmseg;
199	int segnum, result;
200	size_t size;
201
202	segnum = IPCID_TO_IX(shmmap_s->shmid);
203	shmseg = &shmsegs[segnum];
204	size = round_page(shmseg->shm_segsz);
205	result = vm_map_remove(&p->p_vmspace->vm_map, shmmap_s->va, shmmap_s->va + size);
206	if (result != KERN_SUCCESS)
207		return EINVAL;
208	shmmap_s->shmid = -1;
209	shmseg->shm_dtime = time_second;
210	if ((--shmseg->shm_nattch <= 0) &&
211	    (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
212		shm_deallocate_segment(shmseg);
213		shm_last_free = segnum;
214	}
215	return 0;
216}
217
218#ifndef _SYS_SYSPROTO_H_
219struct shmdt_args {
220	void *shmaddr;
221};
222#endif
223
224int
225shmdt(p, uap)
226	struct proc *p;
227	struct shmdt_args *uap;
228{
229	struct shmmap_state *shmmap_s;
230	int i;
231
232	if (!jail_sysvipc_allowed && p->p_prison != NULL)
233		return (ENOSYS);
234
235	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
236 	if (shmmap_s == NULL)
237 	    return EINVAL;
238	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
239		if (shmmap_s->shmid != -1 &&
240		    shmmap_s->va == (vm_offset_t)uap->shmaddr)
241			break;
242	if (i == shminfo.shmseg)
243		return EINVAL;
244	return shm_delete_mapping(p, shmmap_s);
245}
246
247#ifndef _SYS_SYSPROTO_H_
248struct shmat_args {
249	int shmid;
250	void *shmaddr;
251	int shmflg;
252};
253#endif
254
255int
256shmat(p, uap)
257	struct proc *p;
258	struct shmat_args *uap;
259{
260	int error, i, flags;
261	struct shmid_ds *shmseg;
262	struct shmmap_state *shmmap_s = NULL;
263	struct shm_handle *shm_handle;
264	vm_offset_t attach_va;
265	vm_prot_t prot;
266	vm_size_t size;
267	int rv;
268
269	if (!jail_sysvipc_allowed && p->p_prison != NULL)
270		return (ENOSYS);
271
272	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
273	if (shmmap_s == NULL) {
274		size = shminfo.shmseg * sizeof(struct shmmap_state);
275		shmmap_s = malloc(size, M_SHM, M_WAITOK);
276		for (i = 0; i < shminfo.shmseg; i++)
277			shmmap_s[i].shmid = -1;
278		p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
279	}
280	shmseg = shm_find_segment_by_shmid(uap->shmid);
281	if (shmseg == NULL)
282		return EINVAL;
283	error = ipcperm(p, &shmseg->shm_perm,
284	    (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
285	if (error)
286		return error;
287	for (i = 0; i < shminfo.shmseg; i++) {
288		if (shmmap_s->shmid == -1)
289			break;
290		shmmap_s++;
291	}
292	if (i >= shminfo.shmseg)
293		return EMFILE;
294	size = round_page(shmseg->shm_segsz);
295#ifdef VM_PROT_READ_IS_EXEC
296	prot = VM_PROT_READ | VM_PROT_EXECUTE;
297#else
298	prot = VM_PROT_READ;
299#endif
300	if ((uap->shmflg & SHM_RDONLY) == 0)
301		prot |= VM_PROT_WRITE;
302	flags = MAP_ANON | MAP_SHARED;
303	if (uap->shmaddr) {
304		flags |= MAP_FIXED;
305		if (uap->shmflg & SHM_RND)
306			attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
307		else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0)
308			attach_va = (vm_offset_t)uap->shmaddr;
309		else
310			return EINVAL;
311	} else {
312		/* This is just a hint to vm_map_find() about where to put it. */
313		attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + MAXTSIZ + MAXDSIZ);
314	}
315
316	shm_handle = shmseg->shm_internal;
317	vm_object_reference(shm_handle->shm_object);
318	rv = vm_map_find(&p->p_vmspace->vm_map, shm_handle->shm_object,
319		0, &attach_va, size, (flags & MAP_FIXED)?0:1, prot, prot, 0);
320	if (rv != KERN_SUCCESS) {
321		return ENOMEM;
322	}
323	vm_map_inherit(&p->p_vmspace->vm_map,
324		attach_va, attach_va + size, VM_INHERIT_SHARE);
325
326	shmmap_s->va = attach_va;
327	shmmap_s->shmid = uap->shmid;
328	shmseg->shm_lpid = p->p_pid;
329	shmseg->shm_atime = time_second;
330	shmseg->shm_nattch++;
331	p->p_retval[0] = attach_va;
332	return 0;
333}
334
335struct oshmid_ds {
336	struct	ipc_perm shm_perm;	/* operation perms */
337	int	shm_segsz;		/* size of segment (bytes) */
338	ushort	shm_cpid;		/* pid, creator */
339	ushort	shm_lpid;		/* pid, last operation */
340	short	shm_nattch;		/* no. of current attaches */
341	time_t	shm_atime;		/* last attach time */
342	time_t	shm_dtime;		/* last detach time */
343	time_t	shm_ctime;		/* last change time */
344	void	*shm_handle;		/* internal handle for shm segment */
345};
346
347struct oshmctl_args {
348	int shmid;
349	int cmd;
350	struct oshmid_ds *ubuf;
351};
352
353static int
354oshmctl(p, uap)
355	struct proc *p;
356	struct oshmctl_args *uap;
357{
358#ifdef COMPAT_43
359	int error;
360	struct shmid_ds *shmseg;
361	struct oshmid_ds outbuf;
362
363	if (!jail_sysvipc_allowed && p->p_prison != NULL)
364		return (ENOSYS);
365
366	shmseg = shm_find_segment_by_shmid(uap->shmid);
367	if (shmseg == NULL)
368		return EINVAL;
369	switch (uap->cmd) {
370	case IPC_STAT:
371		error = ipcperm(p, &shmseg->shm_perm, IPC_R);
372		if (error)
373			return error;
374		outbuf.shm_perm = shmseg->shm_perm;
375		outbuf.shm_segsz = shmseg->shm_segsz;
376		outbuf.shm_cpid = shmseg->shm_cpid;
377		outbuf.shm_lpid = shmseg->shm_lpid;
378		outbuf.shm_nattch = shmseg->shm_nattch;
379		outbuf.shm_atime = shmseg->shm_atime;
380		outbuf.shm_dtime = shmseg->shm_dtime;
381		outbuf.shm_ctime = shmseg->shm_ctime;
382		outbuf.shm_handle = shmseg->shm_internal;
383		error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
384		if (error)
385			return error;
386		break;
387	default:
388		/* XXX casting to (sy_call_t *) is bogus, as usual. */
389		return ((sy_call_t *)shmctl)(p, uap);
390	}
391	return 0;
392#else
393	return EINVAL;
394#endif
395}
396
397#ifndef _SYS_SYSPROTO_H_
398struct shmctl_args {
399	int shmid;
400	int cmd;
401	struct shmid_ds *buf;
402};
403#endif
404
405int
406shmctl(p, uap)
407	struct proc *p;
408	struct shmctl_args *uap;
409{
410	int error;
411	struct shmid_ds inbuf;
412	struct shmid_ds *shmseg;
413
414	if (!jail_sysvipc_allowed && p->p_prison != NULL)
415		return (ENOSYS);
416
417	shmseg = shm_find_segment_by_shmid(uap->shmid);
418	if (shmseg == NULL)
419		return EINVAL;
420	switch (uap->cmd) {
421	case IPC_STAT:
422		error = ipcperm(p, &shmseg->shm_perm, IPC_R);
423		if (error)
424			return error;
425		error = copyout((caddr_t)shmseg, uap->buf, sizeof(inbuf));
426		if (error)
427			return error;
428		break;
429	case IPC_SET:
430		error = ipcperm(p, &shmseg->shm_perm, IPC_M);
431		if (error)
432			return error;
433		error = copyin(uap->buf, (caddr_t)&inbuf, sizeof(inbuf));
434		if (error)
435			return error;
436		shmseg->shm_perm.uid = inbuf.shm_perm.uid;
437		shmseg->shm_perm.gid = inbuf.shm_perm.gid;
438		shmseg->shm_perm.mode =
439		    (shmseg->shm_perm.mode & ~ACCESSPERMS) |
440		    (inbuf.shm_perm.mode & ACCESSPERMS);
441		shmseg->shm_ctime = time_second;
442		break;
443	case IPC_RMID:
444		error = ipcperm(p, &shmseg->shm_perm, IPC_M);
445		if (error)
446			return error;
447		shmseg->shm_perm.key = IPC_PRIVATE;
448		shmseg->shm_perm.mode |= SHMSEG_REMOVED;
449		if (shmseg->shm_nattch <= 0) {
450			shm_deallocate_segment(shmseg);
451			shm_last_free = IPCID_TO_IX(uap->shmid);
452		}
453		break;
454#if 0
455	case SHM_LOCK:
456	case SHM_UNLOCK:
457#endif
458	default:
459		return EINVAL;
460	}
461	return 0;
462}
463
464#ifndef _SYS_SYSPROTO_H_
465struct shmget_args {
466	key_t key;
467	size_t size;
468	int shmflg;
469};
470#endif
471
472static int
473shmget_existing(p, uap, mode, segnum)
474	struct proc *p;
475	struct shmget_args *uap;
476	int mode;
477	int segnum;
478{
479	struct shmid_ds *shmseg;
480	int error;
481
482	shmseg = &shmsegs[segnum];
483	if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
484		/*
485		 * This segment is in the process of being allocated.  Wait
486		 * until it's done, and look the key up again (in case the
487		 * allocation failed or it was freed).
488		 */
489		shmseg->shm_perm.mode |= SHMSEG_WANTED;
490		error = tsleep((caddr_t)shmseg, PLOCK | PCATCH, "shmget", 0);
491		if (error)
492			return error;
493		return EAGAIN;
494	}
495	if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
496		return EEXIST;
497	error = ipcperm(p, &shmseg->shm_perm, mode);
498	if (error)
499		return error;
500	if (uap->size && uap->size > shmseg->shm_segsz)
501		return EINVAL;
502	p->p_retval[0] = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
503	return 0;
504}
505
506static int
507shmget_allocate_segment(p, uap, mode)
508	struct proc *p;
509	struct shmget_args *uap;
510	int mode;
511{
512	int i, segnum, shmid, size;
513	struct ucred *cred = p->p_ucred;
514	struct shmid_ds *shmseg;
515	struct shm_handle *shm_handle;
516
517	if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
518		return EINVAL;
519	if (shm_nused >= shminfo.shmmni) /* any shmids left? */
520		return ENOSPC;
521	size = round_page(uap->size);
522	if (shm_committed + btoc(size) > shminfo.shmall)
523		return ENOMEM;
524	if (shm_last_free < 0) {
525		shmrealloc();	/* maybe expand the shmsegs[] array */
526		for (i = 0; i < shmalloced; i++)
527			if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
528				break;
529		if (i == shmalloced)
530			return ENOSPC;
531		segnum = i;
532	} else  {
533		segnum = shm_last_free;
534		shm_last_free = -1;
535	}
536	shmseg = &shmsegs[segnum];
537	/*
538	 * In case we sleep in malloc(), mark the segment present but deleted
539	 * so that noone else tries to create the same key.
540	 */
541	shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
542	shmseg->shm_perm.key = uap->key;
543	shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
544	shm_handle = (struct shm_handle *)
545	    malloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
546	shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
547
548	/*
549	 * We make sure that we have allocated a pager before we need
550	 * to.
551	 */
552	if (shm_use_phys) {
553		shm_handle->shm_object =
554		    vm_pager_allocate(OBJT_PHYS, 0, size, VM_PROT_DEFAULT, 0);
555	} else {
556		shm_handle->shm_object =
557		    vm_pager_allocate(OBJT_SWAP, 0, size, VM_PROT_DEFAULT, 0);
558	}
559	vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
560	vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
561
562	shmseg->shm_internal = shm_handle;
563	shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
564	shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
565	shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
566	    (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
567	shmseg->shm_segsz = uap->size;
568	shmseg->shm_cpid = p->p_pid;
569	shmseg->shm_lpid = shmseg->shm_nattch = 0;
570	shmseg->shm_atime = shmseg->shm_dtime = 0;
571	shmseg->shm_ctime = time_second;
572	shm_committed += btoc(size);
573	shm_nused++;
574	if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
575		/*
576		 * Somebody else wanted this key while we were asleep.  Wake
577		 * them up now.
578		 */
579		shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
580		wakeup((caddr_t)shmseg);
581	}
582	p->p_retval[0] = shmid;
583	return 0;
584}
585
586int
587shmget(p, uap)
588	struct proc *p;
589	struct shmget_args *uap;
590{
591	int segnum, mode, error;
592
593	if (!jail_sysvipc_allowed && p->p_prison != NULL)
594		return (ENOSYS);
595
596	mode = uap->shmflg & ACCESSPERMS;
597	if (uap->key != IPC_PRIVATE) {
598	again:
599		segnum = shm_find_segment_by_key(uap->key);
600		if (segnum >= 0) {
601			error = shmget_existing(p, uap, mode, segnum);
602			if (error == EAGAIN)
603				goto again;
604			return error;
605		}
606		if ((uap->shmflg & IPC_CREAT) == 0)
607			return ENOENT;
608	}
609	return shmget_allocate_segment(p, uap, mode);
610}
611
612int
613shmsys(p, uap)
614	struct proc *p;
615	/* XXX actually varargs. */
616	struct shmsys_args /* {
617		u_int	which;
618		int	a2;
619		int	a3;
620		int	a4;
621	} */ *uap;
622{
623
624	if (!jail_sysvipc_allowed && p->p_prison != NULL)
625		return (ENOSYS);
626
627	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
628		return EINVAL;
629	return ((*shmcalls[uap->which])(p, &uap->a2));
630}
631
632static void
633shmfork_myhook(p1, p2)
634	struct proc *p1, *p2;
635{
636	struct shmmap_state *shmmap_s;
637	size_t size;
638	int i;
639
640	size = shminfo.shmseg * sizeof(struct shmmap_state);
641	shmmap_s = malloc(size, M_SHM, M_WAITOK);
642	bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
643	p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
644	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
645		if (shmmap_s->shmid != -1)
646			shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
647}
648
649static void
650shmexit_myhook(p)
651	struct proc *p;
652{
653	struct shmmap_state *shmmap_s;
654	int i;
655
656	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
657	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
658		if (shmmap_s->shmid != -1)
659			shm_delete_mapping(p, shmmap_s);
660	free((caddr_t)p->p_vmspace->vm_shm, M_SHM);
661	p->p_vmspace->vm_shm = NULL;
662}
663
664static void
665shmrealloc(void)
666{
667	int i;
668	struct shmid_ds *newsegs;
669
670	if (shmalloced >= shminfo.shmmni)
671		return;
672
673	newsegs = malloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
674	if (newsegs == NULL)
675		return;
676	for (i = 0; i < shmalloced; i++)
677		bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
678	for (; i < shminfo.shmmni; i++) {
679		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
680		shmsegs[i].shm_perm.seq = 0;
681	}
682	free(shmsegs, M_SHM);
683	shmsegs = newsegs;
684	shmalloced = shminfo.shmmni;
685}
686
687static void
688shminit()
689{
690	int i;
691
692	shmalloced = shminfo.shmmni;
693	shmsegs = malloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
694	if (shmsegs == NULL)
695		panic("cannot allocate initial memory for sysvshm");
696	for (i = 0; i < shmalloced; i++) {
697		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
698		shmsegs[i].shm_perm.seq = 0;
699	}
700	shm_last_free = 0;
701	shm_nused = 0;
702	shm_committed = 0;
703	shmexit_hook = &shmexit_myhook;
704	shmfork_hook = &shmfork_myhook;
705}
706
707static int
708shmunload()
709{
710
711	if (shm_nused > 0)
712		return (EBUSY);
713
714	free(shmsegs, M_SHM);
715	shmexit_hook = NULL;
716	shmfork_hook = NULL;
717	return (0);
718}
719
720static int
721sysvshm_modload(struct module *module, int cmd, void *arg)
722{
723	int error = 0;
724
725	switch (cmd) {
726	case MOD_LOAD:
727		shminit();
728		break;
729	case MOD_UNLOAD:
730		error = shmunload();
731		break;
732	case MOD_SHUTDOWN:
733		break;
734	default:
735		error = EINVAL;
736		break;
737	}
738	return (error);
739}
740
741static moduledata_t sysvshm_mod = {
742	"sysvshm",
743	&sysvshm_modload,
744	NULL
745};
746
747SYSCALL_MODULE_HELPER(shmsys, 4);
748SYSCALL_MODULE_HELPER(shmat, 3);
749SYSCALL_MODULE_HELPER(shmctl, 3);
750SYSCALL_MODULE_HELPER(shmdt, 1);
751SYSCALL_MODULE_HELPER(shmget, 3);
752
753DECLARE_MODULE(sysvshm, sysvshm_mod,
754	SI_SUB_SYSV_SHM, SI_ORDER_FIRST);
755MODULE_VERSION(sysvshm, 1);
756