FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_shm.c
1 /* $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $ */
2 /*
3 * Copyright (c) 1994 Adam Glass and Charles Hannum. 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 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by Adam Glass and Charles
16 * Hannum.
17 * 4. The names of the authors may not be used to endorse or promote products
18 * derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: releng/5.2/sys/kern/sysv_shm.c 125489 2004-02-05 18:01:26Z nectar $");
34
35 #include "opt_compat.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/syscallsubr.h>
51 #include <sys/sysent.h>
52 #include <sys/sysproto.h>
53 #include <sys/jail.h>
54
55 #include <vm/vm.h>
56 #include <vm/vm_param.h>
57 #include <vm/pmap.h>
58 #include <vm/vm_object.h>
59 #include <vm/vm_map.h>
60 #include <vm/vm_page.h>
61 #include <vm/vm_pager.h>
62
63 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
64
65 struct oshmctl_args;
66 static int oshmctl(struct thread *td, struct oshmctl_args *uap);
67
68 static int shmget_allocate_segment(struct thread *td,
69 struct shmget_args *uap, int mode);
70 static int shmget_existing(struct thread *td, struct shmget_args *uap,
71 int mode, int segnum);
72
73 /* XXX casting to (sy_call_t *) is bogus, as usual. */
74 static sy_call_t *shmcalls[] = {
75 (sy_call_t *)shmat, (sy_call_t *)oshmctl,
76 (sy_call_t *)shmdt, (sy_call_t *)shmget,
77 (sy_call_t *)shmctl
78 };
79
80 #define SHMSEG_FREE 0x0200
81 #define SHMSEG_REMOVED 0x0400
82 #define SHMSEG_ALLOCATED 0x0800
83 #define SHMSEG_WANTED 0x1000
84
85 static int shm_last_free, shm_nused, shm_committed, shmalloced;
86 static struct shmid_ds *shmsegs;
87
88 struct shm_handle {
89 /* vm_offset_t kva; */
90 vm_object_t shm_object;
91 };
92
93 struct shmmap_state {
94 vm_offset_t va;
95 int shmid;
96 };
97
98 static void shm_deallocate_segment(struct shmid_ds *);
99 static int shm_find_segment_by_key(key_t);
100 static struct shmid_ds *shm_find_segment_by_shmid(int);
101 static struct shmid_ds *shm_find_segment_by_shmidx(int);
102 static int shm_delete_mapping(struct vmspace *vm, struct shmmap_state *);
103 static void shmrealloc(void);
104 static void shminit(void);
105 static int sysvshm_modload(struct module *, int, void *);
106 static int shmunload(void);
107 static void shmexit_myhook(struct vmspace *vm);
108 static void shmfork_myhook(struct proc *p1, struct proc *p2);
109 static int sysctl_shmsegs(SYSCTL_HANDLER_ARGS);
110
111 /*
112 * Tuneable values.
113 */
114 #ifndef SHMMAXPGS
115 #define SHMMAXPGS 8192 /* Note: sysv shared memory is swap backed. */
116 #endif
117 #ifndef SHMMAX
118 #define SHMMAX (SHMMAXPGS*PAGE_SIZE)
119 #endif
120 #ifndef SHMMIN
121 #define SHMMIN 1
122 #endif
123 #ifndef SHMMNI
124 #define SHMMNI 192
125 #endif
126 #ifndef SHMSEG
127 #define SHMSEG 128
128 #endif
129 #ifndef SHMALL
130 #define SHMALL (SHMMAXPGS)
131 #endif
132
133 struct shminfo shminfo = {
134 SHMMAX,
135 SHMMIN,
136 SHMMNI,
137 SHMSEG,
138 SHMALL
139 };
140
141 static int shm_use_phys;
142 static int shm_allow_removed;
143
144 SYSCTL_DECL(_kern_ipc);
145 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, "");
146 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, "");
147 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RDTUN, &shminfo.shmmni, 0, "");
148 SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RDTUN, &shminfo.shmseg, 0, "");
149 SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, "");
150 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW,
151 &shm_use_phys, 0, "");
152 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_allow_removed, CTLFLAG_RW,
153 &shm_allow_removed, 0, "");
154 SYSCTL_PROC(_kern_ipc, OID_AUTO, shmsegs, CTLFLAG_RD,
155 NULL, 0, sysctl_shmsegs, "", "");
156
157 static int
158 shm_find_segment_by_key(key)
159 key_t key;
160 {
161 int i;
162
163 for (i = 0; i < shmalloced; i++)
164 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
165 shmsegs[i].shm_perm.key == key)
166 return (i);
167 return (-1);
168 }
169
170 static struct shmid_ds *
171 shm_find_segment_by_shmid(int shmid)
172 {
173 int segnum;
174 struct shmid_ds *shmseg;
175
176 segnum = IPCID_TO_IX(shmid);
177 if (segnum < 0 || segnum >= shmalloced)
178 return (NULL);
179 shmseg = &shmsegs[segnum];
180 if ((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) == 0 ||
181 (!shm_allow_removed &&
182 (shmseg->shm_perm.mode & SHMSEG_REMOVED) != 0) ||
183 shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
184 return (NULL);
185 return (shmseg);
186 }
187
188 static struct shmid_ds *
189 shm_find_segment_by_shmidx(int segnum)
190 {
191 struct shmid_ds *shmseg;
192
193 if (segnum < 0 || segnum >= shmalloced)
194 return (NULL);
195 shmseg = &shmsegs[segnum];
196 if ((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) == 0 ||
197 (!shm_allow_removed &&
198 (shmseg->shm_perm.mode & SHMSEG_REMOVED) != 0))
199 return (NULL);
200 return (shmseg);
201 }
202
203 static void
204 shm_deallocate_segment(shmseg)
205 struct shmid_ds *shmseg;
206 {
207 struct shm_handle *shm_handle;
208 size_t size;
209
210 GIANT_REQUIRED;
211
212 shm_handle = shmseg->shm_internal;
213 vm_object_deallocate(shm_handle->shm_object);
214 free(shm_handle, M_SHM);
215 shmseg->shm_internal = NULL;
216 size = round_page(shmseg->shm_segsz);
217 shm_committed -= btoc(size);
218 shm_nused--;
219 shmseg->shm_perm.mode = SHMSEG_FREE;
220 }
221
222 static int
223 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
224 {
225 struct shmid_ds *shmseg;
226 int segnum, result;
227 size_t size;
228
229 GIANT_REQUIRED;
230
231 segnum = IPCID_TO_IX(shmmap_s->shmid);
232 shmseg = &shmsegs[segnum];
233 size = round_page(shmseg->shm_segsz);
234 result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
235 if (result != KERN_SUCCESS)
236 return (EINVAL);
237 shmmap_s->shmid = -1;
238 shmseg->shm_dtime = time_second;
239 if ((--shmseg->shm_nattch <= 0) &&
240 (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
241 shm_deallocate_segment(shmseg);
242 shm_last_free = segnum;
243 }
244 return (0);
245 }
246
247 #ifndef _SYS_SYSPROTO_H_
248 struct shmdt_args {
249 const void *shmaddr;
250 };
251 #endif
252
253 /*
254 * MPSAFE
255 */
256 int
257 shmdt(td, uap)
258 struct thread *td;
259 struct shmdt_args *uap;
260 {
261 struct proc *p = td->td_proc;
262 struct shmmap_state *shmmap_s;
263 int i;
264 int error = 0;
265
266 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
267 return (ENOSYS);
268 mtx_lock(&Giant);
269 shmmap_s = p->p_vmspace->vm_shm;
270 if (shmmap_s == NULL) {
271 error = EINVAL;
272 goto done2;
273 }
274 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
275 if (shmmap_s->shmid != -1 &&
276 shmmap_s->va == (vm_offset_t)uap->shmaddr) {
277 break;
278 }
279 }
280 if (i == shminfo.shmseg) {
281 error = EINVAL;
282 goto done2;
283 }
284 error = shm_delete_mapping(p->p_vmspace, shmmap_s);
285 done2:
286 mtx_unlock(&Giant);
287 return (error);
288 }
289
290 #ifndef _SYS_SYSPROTO_H_
291 struct shmat_args {
292 int shmid;
293 const void *shmaddr;
294 int shmflg;
295 };
296 #endif
297
298 /*
299 * MPSAFE
300 */
301 int
302 kern_shmat(td, shmid, shmaddr, shmflg)
303 struct thread *td;
304 int shmid;
305 const void *shmaddr;
306 int shmflg;
307 {
308 struct proc *p = td->td_proc;
309 int i, flags;
310 struct shmid_ds *shmseg;
311 struct shmmap_state *shmmap_s = NULL;
312 struct shm_handle *shm_handle;
313 vm_offset_t attach_va;
314 vm_prot_t prot;
315 vm_size_t size;
316 int rv;
317 int error = 0;
318
319 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
320 return (ENOSYS);
321 mtx_lock(&Giant);
322 shmmap_s = p->p_vmspace->vm_shm;
323 if (shmmap_s == NULL) {
324 size = shminfo.shmseg * sizeof(struct shmmap_state);
325 shmmap_s = malloc(size, M_SHM, M_WAITOK);
326 for (i = 0; i < shminfo.shmseg; i++)
327 shmmap_s[i].shmid = -1;
328 p->p_vmspace->vm_shm = shmmap_s;
329 }
330 shmseg = shm_find_segment_by_shmid(shmid);
331 if (shmseg == NULL) {
332 error = EINVAL;
333 goto done2;
334 }
335 error = ipcperm(td, &shmseg->shm_perm,
336 (shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
337 if (error)
338 goto done2;
339 for (i = 0; i < shminfo.shmseg; i++) {
340 if (shmmap_s->shmid == -1)
341 break;
342 shmmap_s++;
343 }
344 if (i >= shminfo.shmseg) {
345 error = EMFILE;
346 goto done2;
347 }
348 size = round_page(shmseg->shm_segsz);
349 #ifdef VM_PROT_READ_IS_EXEC
350 prot = VM_PROT_READ | VM_PROT_EXECUTE;
351 #else
352 prot = VM_PROT_READ;
353 #endif
354 if ((shmflg & SHM_RDONLY) == 0)
355 prot |= VM_PROT_WRITE;
356 flags = MAP_ANON | MAP_SHARED;
357 if (shmaddr) {
358 flags |= MAP_FIXED;
359 if (shmflg & SHM_RND) {
360 attach_va = (vm_offset_t)shmaddr & ~(SHMLBA-1);
361 } else if (((vm_offset_t)shmaddr & (SHMLBA-1)) == 0) {
362 attach_va = (vm_offset_t)shmaddr;
363 } else {
364 error = EINVAL;
365 goto done2;
366 }
367 } else {
368 /*
369 * This is just a hint to vm_map_find() about where to
370 * put it.
371 */
372 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr
373 + maxtsiz + maxdsiz);
374 }
375
376 shm_handle = shmseg->shm_internal;
377 vm_object_reference(shm_handle->shm_object);
378 rv = vm_map_find(&p->p_vmspace->vm_map, shm_handle->shm_object,
379 0, &attach_va, size, (flags & MAP_FIXED)?0:1, prot, prot, 0);
380 if (rv != KERN_SUCCESS) {
381 vm_object_deallocate(shm_handle->shm_object);
382 error = ENOMEM;
383 goto done2;
384 }
385 vm_map_inherit(&p->p_vmspace->vm_map,
386 attach_va, attach_va + size, VM_INHERIT_SHARE);
387
388 shmmap_s->va = attach_va;
389 shmmap_s->shmid = shmid;
390 shmseg->shm_lpid = p->p_pid;
391 shmseg->shm_atime = time_second;
392 shmseg->shm_nattch++;
393 td->td_retval[0] = attach_va;
394 done2:
395 mtx_unlock(&Giant);
396 return (error);
397 }
398
399 int
400 shmat(td, uap)
401 struct thread *td;
402 struct shmat_args *uap;
403 {
404 return kern_shmat(td, uap->shmid, uap->shmaddr, uap->shmflg);
405 }
406
407 struct oshmid_ds {
408 struct ipc_perm shm_perm; /* operation perms */
409 int shm_segsz; /* size of segment (bytes) */
410 u_short shm_cpid; /* pid, creator */
411 u_short shm_lpid; /* pid, last operation */
412 short shm_nattch; /* no. of current attaches */
413 time_t shm_atime; /* last attach time */
414 time_t shm_dtime; /* last detach time */
415 time_t shm_ctime; /* last change time */
416 void *shm_handle; /* internal handle for shm segment */
417 };
418
419 struct oshmctl_args {
420 int shmid;
421 int cmd;
422 struct oshmid_ds *ubuf;
423 };
424
425 /*
426 * MPSAFE
427 */
428 static int
429 oshmctl(td, uap)
430 struct thread *td;
431 struct oshmctl_args *uap;
432 {
433 #ifdef COMPAT_43
434 int error = 0;
435 struct shmid_ds *shmseg;
436 struct oshmid_ds outbuf;
437
438 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
439 return (ENOSYS);
440 mtx_lock(&Giant);
441 shmseg = shm_find_segment_by_shmid(uap->shmid);
442 if (shmseg == NULL) {
443 error = EINVAL;
444 goto done2;
445 }
446 switch (uap->cmd) {
447 case IPC_STAT:
448 error = ipcperm(td, &shmseg->shm_perm, IPC_R);
449 if (error)
450 goto done2;
451 outbuf.shm_perm = shmseg->shm_perm;
452 outbuf.shm_segsz = shmseg->shm_segsz;
453 outbuf.shm_cpid = shmseg->shm_cpid;
454 outbuf.shm_lpid = shmseg->shm_lpid;
455 outbuf.shm_nattch = shmseg->shm_nattch;
456 outbuf.shm_atime = shmseg->shm_atime;
457 outbuf.shm_dtime = shmseg->shm_dtime;
458 outbuf.shm_ctime = shmseg->shm_ctime;
459 outbuf.shm_handle = shmseg->shm_internal;
460 error = copyout(&outbuf, uap->ubuf, sizeof(outbuf));
461 if (error)
462 goto done2;
463 break;
464 default:
465 /* XXX casting to (sy_call_t *) is bogus, as usual. */
466 error = ((sy_call_t *)shmctl)(td, uap);
467 break;
468 }
469 done2:
470 mtx_unlock(&Giant);
471 return (error);
472 #else
473 return (EINVAL);
474 #endif
475 }
476
477 #ifndef _SYS_SYSPROTO_H_
478 struct shmctl_args {
479 int shmid;
480 int cmd;
481 struct shmid_ds *buf;
482 };
483 #endif
484
485 /*
486 * MPSAFE
487 */
488 int
489 kern_shmctl(td, shmid, cmd, buf, bufsz)
490 struct thread *td;
491 int shmid;
492 int cmd;
493 void *buf;
494 size_t *bufsz;
495 {
496 int error = 0;
497 struct shmid_ds *shmseg;
498
499 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
500 return (ENOSYS);
501
502 mtx_lock(&Giant);
503 switch (cmd) {
504 case IPC_INFO:
505 memcpy(buf, &shminfo, sizeof(shminfo));
506 if (bufsz)
507 *bufsz = sizeof(shminfo);
508 td->td_retval[0] = shmalloced;
509 goto done2;
510 case SHM_INFO: {
511 struct shm_info shm_info;
512 shm_info.used_ids = shm_nused;
513 shm_info.shm_rss = 0; /*XXX where to get from ? */
514 shm_info.shm_tot = 0; /*XXX where to get from ? */
515 shm_info.shm_swp = 0; /*XXX where to get from ? */
516 shm_info.swap_attempts = 0; /*XXX where to get from ? */
517 shm_info.swap_successes = 0; /*XXX where to get from ? */
518 memcpy(buf, &shm_info, sizeof(shm_info));
519 if (bufsz)
520 *bufsz = sizeof(shm_info);
521 td->td_retval[0] = shmalloced;
522 goto done2;
523 }
524 }
525 if (cmd == SHM_STAT)
526 shmseg = shm_find_segment_by_shmidx(shmid);
527 else
528 shmseg = shm_find_segment_by_shmid(shmid);
529 if (shmseg == NULL) {
530 error = EINVAL;
531 goto done2;
532 }
533 switch (cmd) {
534 case SHM_STAT:
535 case IPC_STAT:
536 error = ipcperm(td, &shmseg->shm_perm, IPC_R);
537 if (error)
538 goto done2;
539 memcpy(buf, shmseg, sizeof(struct shmid_ds));
540 if (bufsz)
541 *bufsz = sizeof(struct shmid_ds);
542 if (cmd == SHM_STAT)
543 td->td_retval[0] = IXSEQ_TO_IPCID(shmid, shmseg->shm_perm);
544 break;
545 case IPC_SET: {
546 struct shmid_ds *shmid;
547
548 shmid = (struct shmid_ds *)buf;
549 error = ipcperm(td, &shmseg->shm_perm, IPC_M);
550 if (error)
551 goto done2;
552 shmseg->shm_perm.uid = shmid->shm_perm.uid;
553 shmseg->shm_perm.gid = shmid->shm_perm.gid;
554 shmseg->shm_perm.mode =
555 (shmseg->shm_perm.mode & ~ACCESSPERMS) |
556 (shmid->shm_perm.mode & ACCESSPERMS);
557 shmseg->shm_ctime = time_second;
558 break;
559 }
560 case IPC_RMID:
561 error = ipcperm(td, &shmseg->shm_perm, IPC_M);
562 if (error)
563 goto done2;
564 shmseg->shm_perm.key = IPC_PRIVATE;
565 shmseg->shm_perm.mode |= SHMSEG_REMOVED;
566 if (shmseg->shm_nattch <= 0) {
567 shm_deallocate_segment(shmseg);
568 shm_last_free = IPCID_TO_IX(shmid);
569 }
570 break;
571 #if 0
572 case SHM_LOCK:
573 case SHM_UNLOCK:
574 #endif
575 default:
576 error = EINVAL;
577 break;
578 }
579 done2:
580 mtx_unlock(&Giant);
581 return (error);
582 }
583
584 int
585 shmctl(td, uap)
586 struct thread *td;
587 struct shmctl_args *uap;
588 {
589 int error = 0;
590 struct shmid_ds buf;
591 size_t bufsz;
592
593 /* IPC_SET needs to copyin the buffer before calling kern_shmctl */
594 if (uap->cmd == IPC_SET) {
595 if ((error = copyin(uap->buf, &buf, sizeof(struct shmid_ds))))
596 goto done;
597 }
598
599 error = kern_shmctl(td, uap->shmid, uap->cmd, (void *)&buf, &bufsz);
600 if (error)
601 goto done;
602
603 /* Cases in which we need to copyout */
604 switch (uap->cmd) {
605 case IPC_INFO:
606 case SHM_INFO:
607 case SHM_STAT:
608 case IPC_STAT:
609 error = copyout(&buf, uap->buf, bufsz);
610 break;
611 }
612
613 done:
614 if (error) {
615 /* Invalidate the return value */
616 td->td_retval[0] = -1;
617 }
618 return (error);
619 }
620
621
622 #ifndef _SYS_SYSPROTO_H_
623 struct shmget_args {
624 key_t key;
625 size_t size;
626 int shmflg;
627 };
628 #endif
629
630 static int
631 shmget_existing(td, uap, mode, segnum)
632 struct thread *td;
633 struct shmget_args *uap;
634 int mode;
635 int segnum;
636 {
637 struct shmid_ds *shmseg;
638 int error;
639
640 shmseg = &shmsegs[segnum];
641 if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
642 /*
643 * This segment is in the process of being allocated. Wait
644 * until it's done, and look the key up again (in case the
645 * allocation failed or it was freed).
646 */
647 shmseg->shm_perm.mode |= SHMSEG_WANTED;
648 error = tsleep(shmseg, PLOCK | PCATCH, "shmget", 0);
649 if (error)
650 return (error);
651 return (EAGAIN);
652 }
653 if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
654 return (EEXIST);
655 error = ipcperm(td, &shmseg->shm_perm, mode);
656 if (error)
657 return (error);
658 if (uap->size && uap->size > shmseg->shm_segsz)
659 return (EINVAL);
660 td->td_retval[0] = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
661 return (0);
662 }
663
664 static int
665 shmget_allocate_segment(td, uap, mode)
666 struct thread *td;
667 struct shmget_args *uap;
668 int mode;
669 {
670 int i, segnum, shmid, size;
671 struct ucred *cred = td->td_ucred;
672 struct shmid_ds *shmseg;
673 struct shm_handle *shm_handle;
674
675 GIANT_REQUIRED;
676
677 if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
678 return (EINVAL);
679 if (shm_nused >= shminfo.shmmni) /* Any shmids left? */
680 return (ENOSPC);
681 size = round_page(uap->size);
682 if (shm_committed + btoc(size) > shminfo.shmall)
683 return (ENOMEM);
684 if (shm_last_free < 0) {
685 shmrealloc(); /* Maybe expand the shmsegs[] array. */
686 for (i = 0; i < shmalloced; i++)
687 if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
688 break;
689 if (i == shmalloced)
690 return (ENOSPC);
691 segnum = i;
692 } else {
693 segnum = shm_last_free;
694 shm_last_free = -1;
695 }
696 shmseg = &shmsegs[segnum];
697 /*
698 * In case we sleep in malloc(), mark the segment present but deleted
699 * so that noone else tries to create the same key.
700 */
701 shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
702 shmseg->shm_perm.key = uap->key;
703 shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
704 shm_handle = (struct shm_handle *)
705 malloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
706 shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
707
708 /*
709 * We make sure that we have allocated a pager before we need
710 * to.
711 */
712 if (shm_use_phys) {
713 shm_handle->shm_object =
714 vm_pager_allocate(OBJT_PHYS, 0, size, VM_PROT_DEFAULT, 0);
715 } else {
716 shm_handle->shm_object =
717 vm_pager_allocate(OBJT_SWAP, 0, size, VM_PROT_DEFAULT, 0);
718 }
719 VM_OBJECT_LOCK(shm_handle->shm_object);
720 vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
721 vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
722 VM_OBJECT_UNLOCK(shm_handle->shm_object);
723
724 shmseg->shm_internal = shm_handle;
725 shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
726 shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
727 shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
728 (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
729 shmseg->shm_segsz = uap->size;
730 shmseg->shm_cpid = td->td_proc->p_pid;
731 shmseg->shm_lpid = shmseg->shm_nattch = 0;
732 shmseg->shm_atime = shmseg->shm_dtime = 0;
733 shmseg->shm_ctime = time_second;
734 shm_committed += btoc(size);
735 shm_nused++;
736 if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
737 /*
738 * Somebody else wanted this key while we were asleep. Wake
739 * them up now.
740 */
741 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
742 wakeup(shmseg);
743 }
744 td->td_retval[0] = shmid;
745 return (0);
746 }
747
748 /*
749 * MPSAFE
750 */
751 int
752 shmget(td, uap)
753 struct thread *td;
754 struct shmget_args *uap;
755 {
756 int segnum, mode;
757 int error;
758
759 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
760 return (ENOSYS);
761 mtx_lock(&Giant);
762 mode = uap->shmflg & ACCESSPERMS;
763 if (uap->key != IPC_PRIVATE) {
764 again:
765 segnum = shm_find_segment_by_key(uap->key);
766 if (segnum >= 0) {
767 error = shmget_existing(td, uap, mode, segnum);
768 if (error == EAGAIN)
769 goto again;
770 goto done2;
771 }
772 if ((uap->shmflg & IPC_CREAT) == 0) {
773 error = ENOENT;
774 goto done2;
775 }
776 }
777 error = shmget_allocate_segment(td, uap, mode);
778 done2:
779 mtx_unlock(&Giant);
780 return (error);
781 }
782
783 /*
784 * MPSAFE
785 */
786 int
787 shmsys(td, uap)
788 struct thread *td;
789 /* XXX actually varargs. */
790 struct shmsys_args /* {
791 int which;
792 int a2;
793 int a3;
794 int a4;
795 } */ *uap;
796 {
797 int error;
798
799 if (!jail_sysvipc_allowed && jailed(td->td_ucred))
800 return (ENOSYS);
801 if (uap->which < 0 ||
802 uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
803 return (EINVAL);
804 mtx_lock(&Giant);
805 error = (*shmcalls[uap->which])(td, &uap->a2);
806 mtx_unlock(&Giant);
807 return (error);
808 }
809
810 static void
811 shmfork_myhook(p1, p2)
812 struct proc *p1, *p2;
813 {
814 struct shmmap_state *shmmap_s;
815 size_t size;
816 int i;
817
818 size = shminfo.shmseg * sizeof(struct shmmap_state);
819 shmmap_s = malloc(size, M_SHM, M_WAITOK);
820 bcopy(p1->p_vmspace->vm_shm, shmmap_s, size);
821 p2->p_vmspace->vm_shm = shmmap_s;
822 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
823 if (shmmap_s->shmid != -1)
824 shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
825 }
826
827 static void
828 shmexit_myhook(struct vmspace *vm)
829 {
830 struct shmmap_state *base, *shm;
831 int i;
832
833 GIANT_REQUIRED;
834
835 if ((base = vm->vm_shm) != NULL) {
836 vm->vm_shm = NULL;
837 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
838 if (shm->shmid != -1)
839 shm_delete_mapping(vm, shm);
840 }
841 free(base, M_SHM);
842 }
843 }
844
845 static void
846 shmrealloc(void)
847 {
848 int i;
849 struct shmid_ds *newsegs;
850
851 if (shmalloced >= shminfo.shmmni)
852 return;
853
854 newsegs = malloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
855 if (newsegs == NULL)
856 return;
857 for (i = 0; i < shmalloced; i++)
858 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
859 for (; i < shminfo.shmmni; i++) {
860 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
861 shmsegs[i].shm_perm.seq = 0;
862 }
863 free(shmsegs, M_SHM);
864 shmsegs = newsegs;
865 shmalloced = shminfo.shmmni;
866 }
867
868 static void
869 shminit()
870 {
871 int i;
872
873 TUNABLE_INT_FETCH("kern.ipc.shmmaxpgs", &shminfo.shmall);
874 for (i = PAGE_SIZE; i > 0; i--) {
875 shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
876 if (shminfo.shmmax >= shminfo.shmall)
877 break;
878 }
879 TUNABLE_INT_FETCH("kern.ipc.shmmin", &shminfo.shmmin);
880 TUNABLE_INT_FETCH("kern.ipc.shmmni", &shminfo.shmmni);
881 TUNABLE_INT_FETCH("kern.ipc.shmseg", &shminfo.shmseg);
882 TUNABLE_INT_FETCH("kern.ipc.shm_use_phys", &shm_use_phys);
883
884 shmalloced = shminfo.shmmni;
885 shmsegs = malloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
886 if (shmsegs == NULL)
887 panic("cannot allocate initial memory for sysvshm");
888 for (i = 0; i < shmalloced; i++) {
889 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
890 shmsegs[i].shm_perm.seq = 0;
891 }
892 shm_last_free = 0;
893 shm_nused = 0;
894 shm_committed = 0;
895 shmexit_hook = &shmexit_myhook;
896 shmfork_hook = &shmfork_myhook;
897 }
898
899 static int
900 shmunload()
901 {
902
903 if (shm_nused > 0)
904 return (EBUSY);
905
906 free(shmsegs, M_SHM);
907 shmexit_hook = NULL;
908 shmfork_hook = NULL;
909 return (0);
910 }
911
912 static int
913 sysctl_shmsegs(SYSCTL_HANDLER_ARGS)
914 {
915
916 return (SYSCTL_OUT(req, shmsegs, shmalloced * sizeof(shmsegs[0])));
917 }
918
919 static int
920 sysvshm_modload(struct module *module, int cmd, void *arg)
921 {
922 int error = 0;
923
924 switch (cmd) {
925 case MOD_LOAD:
926 shminit();
927 break;
928 case MOD_UNLOAD:
929 error = shmunload();
930 break;
931 case MOD_SHUTDOWN:
932 break;
933 default:
934 error = EINVAL;
935 break;
936 }
937 return (error);
938 }
939
940 static moduledata_t sysvshm_mod = {
941 "sysvshm",
942 &sysvshm_modload,
943 NULL
944 };
945
946 SYSCALL_MODULE_HELPER(shmsys);
947 SYSCALL_MODULE_HELPER(shmat);
948 SYSCALL_MODULE_HELPER(shmctl);
949 SYSCALL_MODULE_HELPER(shmdt);
950 SYSCALL_MODULE_HELPER(shmget);
951
952 DECLARE_MODULE(sysvshm, sysvshm_mod,
953 SI_SUB_SYSV_SHM, SI_ORDER_FIRST);
954 MODULE_VERSION(sysvshm, 1);
Cache object: 3e9d3576ebb56aa10681e65986e3da67
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