sysv_shm.c revision 83413 
1/* $FreeBSD: head/sys/kern/sysv_shm.c 83413 2001-09-13 20:20:09Z mr $ */
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/kernel.h>
41#include <sys/lock.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/mutex.h>
48#include <sys/stat.h>
49#include <sys/syscall.h>
50#include <sys/sysent.h>
51#include <sys/sysproto.h>
52#include <sys/jail.h>
53
54#include <vm/vm.h>
55#include <vm/vm_param.h>
56#include <vm/pmap.h>
57#include <vm/vm_object.h>
58#include <vm/vm_map.h>
59#include <vm/vm_page.h>
60#include <vm/vm_pager.h>
61
62static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
63
64struct oshmctl_args;
65static int oshmctl __P((struct thread *td, struct oshmctl_args *uap));
66
67static int shmget_allocate_segment __P((struct thread *td,
68    struct shmget_args *uap, int mode));
69static int shmget_existing __P((struct thread *td, struct shmget_args *uap,
70    int mode, int segnum));
71
72/* XXX casting to (sy_call_t *) is bogus, as usual. */
73static sy_call_t *shmcalls[] = {
74	(sy_call_t *)shmat, (sy_call_t *)oshmctl,
75	(sy_call_t *)shmdt, (sy_call_t *)shmget,
76	(sy_call_t *)shmctl
77};
78
79#define	SHMSEG_FREE     	0x0200
80#define	SHMSEG_REMOVED  	0x0400
81#define	SHMSEG_ALLOCATED	0x0800
82#define	SHMSEG_WANTED		0x1000
83
84static int shm_last_free, shm_nused, shm_committed, shmalloced;
85static struct shmid_ds	*shmsegs;
86
87struct shm_handle {
88	/* vm_offset_t kva; */
89	vm_object_t shm_object;
90};
91
92struct shmmap_state {
93	vm_offset_t va;
94	int shmid;
95};
96
97static void shm_deallocate_segment __P((struct shmid_ds *));
98static int shm_find_segment_by_key __P((key_t));
99static struct shmid_ds *shm_find_segment_by_shmid __P((int));
100static int shm_delete_mapping __P((struct proc *p, struct shmmap_state *));
101static void shmrealloc __P((void));
102static void shminit __P((void));
103static int sysvshm_modload __P((struct module *, int, void *));
104static int shmunload __P((void));
105static void shmexit_myhook __P((struct proc *p));
106static void shmfork_myhook __P((struct proc *p1, struct proc *p2));
107static int sysctl_shmsegs __P((SYSCTL_HANDLER_ARGS));
108
109/*
110 * Tuneable values.
111 */
112#ifndef SHMMAXPGS
113#define	SHMMAXPGS	8192	/* Note: sysv shared memory is swap backed. */
114#endif
115#ifndef SHMMAX
116#define	SHMMAX	(SHMMAXPGS*PAGE_SIZE)
117#endif
118#ifndef SHMMIN
119#define	SHMMIN	1
120#endif
121#ifndef SHMMNI
122#define	SHMMNI	192
123#endif
124#ifndef SHMSEG
125#define	SHMSEG	128
126#endif
127#ifndef SHMALL
128#define	SHMALL	(SHMMAXPGS)
129#endif
130
131struct	shminfo shminfo = {
132	SHMMAX,
133	SHMMIN,
134	SHMMNI,
135	SHMSEG,
136	SHMALL
137};
138
139static int shm_use_phys;
140
141SYSCTL_DECL(_kern_ipc);
142SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, "");
143SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, "");
144SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0, "");
145SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RD, &shminfo.shmseg, 0, "");
146SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, "");
147SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW,
148    &shm_use_phys, 0, "");
149SYSCTL_PROC(_kern_ipc, OID_AUTO, shmsegs, CTLFLAG_RD,
150    NULL, 0, sysctl_shmsegs, "", "");
151
152static int
153shm_find_segment_by_key(key)
154	key_t key;
155{
156	int i;
157
158	for (i = 0; i < shmalloced; i++)
159		if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
160		    shmsegs[i].shm_perm.key == key)
161			return i;
162	return -1;
163}
164
165static struct shmid_ds *
166shm_find_segment_by_shmid(shmid)
167	int shmid;
168{
169	int segnum;
170	struct shmid_ds *shmseg;
171
172	segnum = IPCID_TO_IX(shmid);
173	if (segnum < 0 || segnum >= shmalloced)
174		return NULL;
175	shmseg = &shmsegs[segnum];
176	if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
177	    != SHMSEG_ALLOCATED ||
178	    shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
179		return NULL;
180	return shmseg;
181}
182
183static void
184shm_deallocate_segment(shmseg)
185	struct shmid_ds *shmseg;
186{
187	struct shm_handle *shm_handle;
188	size_t size;
189
190	GIANT_REQUIRED;
191
192	shm_handle = shmseg->shm_internal;
193	vm_object_deallocate(shm_handle->shm_object);
194	free((caddr_t)shm_handle, M_SHM);
195	shmseg->shm_internal = NULL;
196	size = round_page(shmseg->shm_segsz);
197	shm_committed -= btoc(size);
198	shm_nused--;
199	shmseg->shm_perm.mode = SHMSEG_FREE;
200}
201
202static int
203shm_delete_mapping(p, shmmap_s)
204	struct proc *p;
205	struct shmmap_state *shmmap_s;
206{
207	struct shmid_ds *shmseg;
208	int segnum, result;
209	size_t size;
210
211	GIANT_REQUIRED;
212
213	segnum = IPCID_TO_IX(shmmap_s->shmid);
214	shmseg = &shmsegs[segnum];
215	size = round_page(shmseg->shm_segsz);
216	result = vm_map_remove(&p->p_vmspace->vm_map, shmmap_s->va,
217	    shmmap_s->va + size);
218	if (result != KERN_SUCCESS)
219		return EINVAL;
220	shmmap_s->shmid = -1;
221	shmseg->shm_dtime = time_second;
222	if ((--shmseg->shm_nattch <= 0) &&
223	    (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
224		shm_deallocate_segment(shmseg);
225		shm_last_free = segnum;
226	}
227	return 0;
228}
229
230#ifndef _SYS_SYSPROTO_H_
231struct shmdt_args {
232	void *shmaddr;
233};
234#endif
235
236/*
237 * MPSAFE
238 */
239int
240shmdt(td, uap)
241	struct thread *td;
242	struct shmdt_args *uap;
243{
244	struct proc *p = td->td_proc;
245	struct shmmap_state *shmmap_s;
246	int i;
247	int error = 0;
248
249	mtx_lock(&Giant);
250	if (!jail_sysvipc_allowed && jailed(p->p_ucred)) {
251		error = ENOSYS;
252		goto done2;
253	}
254	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
255 	if (shmmap_s == NULL) {
256		error = EINVAL;
257		goto done2;
258	}
259	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
260		if (shmmap_s->shmid != -1 &&
261		    shmmap_s->va == (vm_offset_t)uap->shmaddr) {
262			break;
263		}
264	}
265	if (i == shminfo.shmseg) {
266		error = EINVAL;
267		goto done2;
268	}
269	error = shm_delete_mapping(p, shmmap_s);
270done2:
271	mtx_unlock(&Giant);
272	return (error);
273}
274
275#ifndef _SYS_SYSPROTO_H_
276struct shmat_args {
277	int shmid;
278	void *shmaddr;
279	int shmflg;
280};
281#endif
282
283/*
284 * MPSAFE
285 */
286int
287shmat(td, uap)
288	struct thread *td;
289	struct shmat_args *uap;
290{
291	struct proc *p = td->td_proc;
292	int i, flags;
293	struct shmid_ds *shmseg;
294	struct shmmap_state *shmmap_s = NULL;
295	struct shm_handle *shm_handle;
296	vm_offset_t attach_va;
297	vm_prot_t prot;
298	vm_size_t size;
299	int rv;
300	int error = 0;
301
302	mtx_lock(&Giant);
303	if (!jail_sysvipc_allowed && jailed(p->p_ucred)) {
304		error = ENOSYS;
305		goto done2;
306	}
307	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
308	if (shmmap_s == NULL) {
309		size = shminfo.shmseg * sizeof(struct shmmap_state);
310		shmmap_s = malloc(size, M_SHM, M_WAITOK);
311		for (i = 0; i < shminfo.shmseg; i++)
312			shmmap_s[i].shmid = -1;
313		p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
314	}
315	shmseg = shm_find_segment_by_shmid(uap->shmid);
316	if (shmseg == NULL) {
317		error = EINVAL;
318		goto done2;
319	}
320	error = ipcperm(td, &shmseg->shm_perm,
321	    (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
322	if (error)
323		goto done2;
324	for (i = 0; i < shminfo.shmseg; i++) {
325		if (shmmap_s->shmid == -1)
326			break;
327		shmmap_s++;
328	}
329	if (i >= shminfo.shmseg) {
330		error = EMFILE;
331		goto done2;
332	}
333	size = round_page(shmseg->shm_segsz);
334#ifdef VM_PROT_READ_IS_EXEC
335	prot = VM_PROT_READ | VM_PROT_EXECUTE;
336#else
337	prot = VM_PROT_READ;
338#endif
339	if ((uap->shmflg & SHM_RDONLY) == 0)
340		prot |= VM_PROT_WRITE;
341	flags = MAP_ANON | MAP_SHARED;
342	if (uap->shmaddr) {
343		flags |= MAP_FIXED;
344		if (uap->shmflg & SHM_RND) {
345			attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
346		} else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) {
347			attach_va = (vm_offset_t)uap->shmaddr;
348		} else {
349			error = EINVAL;
350			goto done2;
351		}
352	} else {
353		/*
354		 * This is just a hint to vm_map_find() about where to
355		 * put it.
356		 */
357		attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr
358		    + MAXTSIZ + MAXDSIZ);
359	}
360
361	shm_handle = shmseg->shm_internal;
362	vm_object_reference(shm_handle->shm_object);
363	rv = vm_map_find(&p->p_vmspace->vm_map, shm_handle->shm_object,
364		0, &attach_va, size, (flags & MAP_FIXED)?0:1, prot, prot, 0);
365	if (rv != KERN_SUCCESS) {
366		error = ENOMEM;
367		goto done2;
368	}
369	vm_map_inherit(&p->p_vmspace->vm_map,
370		attach_va, attach_va + size, VM_INHERIT_SHARE);
371
372	shmmap_s->va = attach_va;
373	shmmap_s->shmid = uap->shmid;
374	shmseg->shm_lpid = p->p_pid;
375	shmseg->shm_atime = time_second;
376	shmseg->shm_nattch++;
377	td->td_retval[0] = attach_va;
378done2:
379	mtx_unlock(&Giant);
380	return (error);
381}
382
383struct oshmid_ds {
384	struct	ipc_perm shm_perm;	/* operation perms */
385	int	shm_segsz;		/* size of segment (bytes) */
386	ushort	shm_cpid;		/* pid, creator */
387	ushort	shm_lpid;		/* pid, last operation */
388	short	shm_nattch;		/* no. of current attaches */
389	time_t	shm_atime;		/* last attach time */
390	time_t	shm_dtime;		/* last detach time */
391	time_t	shm_ctime;		/* last change time */
392	void	*shm_handle;		/* internal handle for shm segment */
393};
394
395struct oshmctl_args {
396	int shmid;
397	int cmd;
398	struct oshmid_ds *ubuf;
399};
400
401/*
402 * MPSAFE
403 */
404static int
405oshmctl(td, uap)
406	struct thread *td;
407	struct oshmctl_args *uap;
408{
409#ifdef COMPAT_43
410	int error = 0;
411	struct shmid_ds *shmseg;
412	struct oshmid_ds outbuf;
413
414	mtx_lock(&Giant);
415	if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) {
416		error = ENOSYS;
417		goto done2;
418	}
419	shmseg = shm_find_segment_by_shmid(uap->shmid);
420	if (shmseg == NULL) {
421		error = EINVAL;
422		goto done2;
423	}
424	switch (uap->cmd) {
425	case IPC_STAT:
426		error = ipcperm(td, &shmseg->shm_perm, IPC_R);
427		if (error)
428			goto done2;
429		outbuf.shm_perm = shmseg->shm_perm;
430		outbuf.shm_segsz = shmseg->shm_segsz;
431		outbuf.shm_cpid = shmseg->shm_cpid;
432		outbuf.shm_lpid = shmseg->shm_lpid;
433		outbuf.shm_nattch = shmseg->shm_nattch;
434		outbuf.shm_atime = shmseg->shm_atime;
435		outbuf.shm_dtime = shmseg->shm_dtime;
436		outbuf.shm_ctime = shmseg->shm_ctime;
437		outbuf.shm_handle = shmseg->shm_internal;
438		error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
439		if (error)
440			goto done2;
441		break;
442	default:
443		/* XXX casting to (sy_call_t *) is bogus, as usual. */
444		error = ((sy_call_t *)shmctl)(td, uap);
445		break;
446	}
447done2:
448	mtx_unlock(&Giant);
449	return (error);
450#else
451	return EINVAL;
452#endif
453}
454
455#ifndef _SYS_SYSPROTO_H_
456struct shmctl_args {
457	int shmid;
458	int cmd;
459	struct shmid_ds *buf;
460};
461#endif
462
463/*
464 * MPSAFE
465 */
466int
467shmctl(td, uap)
468	struct thread *td;
469	struct shmctl_args *uap;
470{
471	int error = 0;
472	struct shmid_ds inbuf;
473	struct shmid_ds *shmseg;
474
475	mtx_lock(&Giant);
476	if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) {
477		error = ENOSYS;
478		goto done2;
479	}
480	shmseg = shm_find_segment_by_shmid(uap->shmid);
481	if (shmseg == NULL) {
482		error = EINVAL;
483		goto done2;
484	}
485	switch (uap->cmd) {
486	case IPC_STAT:
487		error = ipcperm(td, &shmseg->shm_perm, IPC_R);
488		if (error)
489			goto done2;
490		error = copyout((caddr_t)shmseg, uap->buf, sizeof(inbuf));
491		if (error)
492			goto done2;
493		break;
494	case IPC_SET:
495		error = ipcperm(td, &shmseg->shm_perm, IPC_M);
496		if (error)
497			goto done2;
498		error = copyin(uap->buf, (caddr_t)&inbuf, sizeof(inbuf));
499		if (error)
500			goto done2;
501		shmseg->shm_perm.uid = inbuf.shm_perm.uid;
502		shmseg->shm_perm.gid = inbuf.shm_perm.gid;
503		shmseg->shm_perm.mode =
504		    (shmseg->shm_perm.mode & ~ACCESSPERMS) |
505		    (inbuf.shm_perm.mode & ACCESSPERMS);
506		shmseg->shm_ctime = time_second;
507		break;
508	case IPC_RMID:
509		error = ipcperm(td, &shmseg->shm_perm, IPC_M);
510		if (error)
511			goto done2;
512		shmseg->shm_perm.key = IPC_PRIVATE;
513		shmseg->shm_perm.mode |= SHMSEG_REMOVED;
514		if (shmseg->shm_nattch <= 0) {
515			shm_deallocate_segment(shmseg);
516			shm_last_free = IPCID_TO_IX(uap->shmid);
517		}
518		break;
519#if 0
520	case SHM_LOCK:
521	case SHM_UNLOCK:
522#endif
523	default:
524		error = EINVAL;
525		break;
526	}
527done2:
528	mtx_unlock(&Giant);
529	return (error);
530}
531
532#ifndef _SYS_SYSPROTO_H_
533struct shmget_args {
534	key_t key;
535	size_t size;
536	int shmflg;
537};
538#endif
539
540static int
541shmget_existing(td, uap, mode, segnum)
542	struct thread *td;
543	struct shmget_args *uap;
544	int mode;
545	int segnum;
546{
547	struct shmid_ds *shmseg;
548	int error;
549
550	shmseg = &shmsegs[segnum];
551	if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
552		/*
553		 * This segment is in the process of being allocated.  Wait
554		 * until it's done, and look the key up again (in case the
555		 * allocation failed or it was freed).
556		 */
557		shmseg->shm_perm.mode |= SHMSEG_WANTED;
558		error = tsleep((caddr_t)shmseg, PLOCK | PCATCH, "shmget", 0);
559		if (error)
560			return error;
561		return EAGAIN;
562	}
563	if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
564		return EEXIST;
565	error = ipcperm(td, &shmseg->shm_perm, mode);
566	if (error)
567		return error;
568	if (uap->size && uap->size > shmseg->shm_segsz)
569		return EINVAL;
570	td->td_retval[0] = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
571	return 0;
572}
573
574static int
575shmget_allocate_segment(td, uap, mode)
576	struct thread *td;
577	struct shmget_args *uap;
578	int mode;
579{
580	int i, segnum, shmid, size;
581	struct ucred *cred = td->td_proc->p_ucred;
582	struct shmid_ds *shmseg;
583	struct shm_handle *shm_handle;
584
585	GIANT_REQUIRED;
586
587	if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
588		return EINVAL;
589	if (shm_nused >= shminfo.shmmni) /* Any shmids left? */
590		return ENOSPC;
591	size = round_page(uap->size);
592	if (shm_committed + btoc(size) > shminfo.shmall)
593		return ENOMEM;
594	if (shm_last_free < 0) {
595		shmrealloc();	/* Maybe expand the shmsegs[] array. */
596		for (i = 0; i < shmalloced; i++)
597			if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
598				break;
599		if (i == shmalloced)
600			return ENOSPC;
601		segnum = i;
602	} else  {
603		segnum = shm_last_free;
604		shm_last_free = -1;
605	}
606	shmseg = &shmsegs[segnum];
607	/*
608	 * In case we sleep in malloc(), mark the segment present but deleted
609	 * so that noone else tries to create the same key.
610	 */
611	shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
612	shmseg->shm_perm.key = uap->key;
613	shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
614	shm_handle = (struct shm_handle *)
615	    malloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
616	shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
617
618	/*
619	 * We make sure that we have allocated a pager before we need
620	 * to.
621	 */
622	if (shm_use_phys) {
623		shm_handle->shm_object =
624		    vm_pager_allocate(OBJT_PHYS, 0, size, VM_PROT_DEFAULT, 0);
625	} else {
626		shm_handle->shm_object =
627		    vm_pager_allocate(OBJT_SWAP, 0, size, VM_PROT_DEFAULT, 0);
628	}
629	vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
630	vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
631
632	shmseg->shm_internal = shm_handle;
633	shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
634	shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
635	shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
636	    (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
637	shmseg->shm_segsz = uap->size;
638	shmseg->shm_cpid = td->td_proc->p_pid;
639	shmseg->shm_lpid = shmseg->shm_nattch = 0;
640	shmseg->shm_atime = shmseg->shm_dtime = 0;
641	shmseg->shm_ctime = time_second;
642	shm_committed += btoc(size);
643	shm_nused++;
644	if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
645		/*
646		 * Somebody else wanted this key while we were asleep.  Wake
647		 * them up now.
648		 */
649		shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
650		wakeup((caddr_t)shmseg);
651	}
652	td->td_retval[0] = shmid;
653	return 0;
654}
655
656/*
657 * MPSAFE
658 */
659int
660shmget(td, uap)
661	struct thread *td;
662	struct shmget_args *uap;
663{
664	int segnum, mode;
665	int error;
666
667	mtx_lock(&Giant);
668	if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) {
669		error = ENOSYS;
670		goto done2;
671	}
672	mode = uap->shmflg & ACCESSPERMS;
673	if (uap->key != IPC_PRIVATE) {
674	again:
675		segnum = shm_find_segment_by_key(uap->key);
676		if (segnum >= 0) {
677			error = shmget_existing(td, uap, mode, segnum);
678			if (error == EAGAIN)
679				goto again;
680			goto done2;
681		}
682		if ((uap->shmflg & IPC_CREAT) == 0) {
683			error = ENOENT;
684			goto done2;
685		}
686	}
687	error = shmget_allocate_segment(td, uap, mode);
688done2:
689	mtx_unlock(&Giant);
690	return (error);
691}
692
693/*
694 * MPSAFE
695 */
696int
697shmsys(td, uap)
698	struct thread *td;
699	/* XXX actually varargs. */
700	struct shmsys_args /* {
701		u_int	which;
702		int	a2;
703		int	a3;
704		int	a4;
705	} */ *uap;
706{
707	int error;
708
709	mtx_lock(&Giant);
710	if (!jail_sysvipc_allowed && jailed(td->td_proc->p_ucred)) {
711		error = ENOSYS;
712		goto done2;
713	}
714	if (uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0])) {
715		error = EINVAL;
716		goto done2;
717	}
718	error = (*shmcalls[uap->which])(td, &uap->a2);
719done2:
720	mtx_unlock(&Giant);
721	return (error);
722}
723
724static void
725shmfork_myhook(p1, p2)
726	struct proc *p1, *p2;
727{
728	struct shmmap_state *shmmap_s;
729	size_t size;
730	int i;
731
732	size = shminfo.shmseg * sizeof(struct shmmap_state);
733	shmmap_s = malloc(size, M_SHM, M_WAITOK);
734	bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
735	p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
736	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
737		if (shmmap_s->shmid != -1)
738			shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
739}
740
741static void
742shmexit_myhook(p)
743	struct proc *p;
744{
745	struct shmmap_state *shmmap_s;
746	int i;
747
748	GIANT_REQUIRED;
749
750	shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
751	for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
752		if (shmmap_s->shmid != -1)
753			shm_delete_mapping(p, shmmap_s);
754	free((caddr_t)p->p_vmspace->vm_shm, M_SHM);
755	p->p_vmspace->vm_shm = NULL;
756}
757
758static void
759shmrealloc(void)
760{
761	int i;
762	struct shmid_ds *newsegs;
763
764	if (shmalloced >= shminfo.shmmni)
765		return;
766
767	newsegs = malloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
768	if (newsegs == NULL)
769		return;
770	for (i = 0; i < shmalloced; i++)
771		bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
772	for (; i < shminfo.shmmni; i++) {
773		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
774		shmsegs[i].shm_perm.seq = 0;
775	}
776	free(shmsegs, M_SHM);
777	shmsegs = newsegs;
778	shmalloced = shminfo.shmmni;
779}
780
781static void
782shminit()
783{
784	int i;
785
786	TUNABLE_INT_FETCH("kern.ipc.shmmaxpgs", &shminfo.shmall);
787	shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
788	TUNABLE_INT_FETCH("kern.ipc.shmmin", &shminfo.shmmin);
789	TUNABLE_INT_FETCH("kern.ipc.shmmni", &shminfo.shmmni);
790	TUNABLE_INT_FETCH("kern.ipc.shmseg", &shminfo.shmseg);
791	TUNABLE_INT_FETCH("kern.ipc.shm_use_phys", &shm_use_phys);
792
793	shmalloced = shminfo.shmmni;
794	shmsegs = malloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
795	if (shmsegs == NULL)
796		panic("cannot allocate initial memory for sysvshm");
797	for (i = 0; i < shmalloced; i++) {
798		shmsegs[i].shm_perm.mode = SHMSEG_FREE;
799		shmsegs[i].shm_perm.seq = 0;
800	}
801	shm_last_free = 0;
802	shm_nused = 0;
803	shm_committed = 0;
804	shmexit_hook = &shmexit_myhook;
805	shmfork_hook = &shmfork_myhook;
806}
807
808static int
809shmunload()
810{
811
812	if (shm_nused > 0)
813		return (EBUSY);
814
815	free(shmsegs, M_SHM);
816	shmexit_hook = NULL;
817	shmfork_hook = NULL;
818	return (0);
819}
820
821static int
822sysctl_shmsegs(SYSCTL_HANDLER_ARGS)
823{
824
825	return (SYSCTL_OUT(req, shmsegs, shmalloced * sizeof(shmsegs[0])));
826}
827
828static int
829sysvshm_modload(struct module *module, int cmd, void *arg)
830{
831	int error = 0;
832
833	switch (cmd) {
834	case MOD_LOAD:
835		shminit();
836		break;
837	case MOD_UNLOAD:
838		error = shmunload();
839		break;
840	case MOD_SHUTDOWN:
841		break;
842	default:
843		error = EINVAL;
844		break;
845	}
846	return (error);
847}
848
849static moduledata_t sysvshm_mod = {
850	"sysvshm",
851	&sysvshm_modload,
852	NULL
853};
854
855SYSCALL_MODULE_HELPER(shmsys, 4);
856SYSCALL_MODULE_HELPER(shmat, 3);
857SYSCALL_MODULE_HELPER(shmctl, 3);
858SYSCALL_MODULE_HELPER(shmdt, 1);
859SYSCALL_MODULE_HELPER(shmget, 3);
860
861DECLARE_MODULE(sysvshm, sysvshm_mod,
862	SI_SUB_SYSV_SHM, SI_ORDER_FIRST);
863MODULE_VERSION(sysvshm, 1);
864