1 /*
2 * Copyright (c) 1994 Adam Glass and Charles Hannum. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. All advertising materials mentioning features or use of this software
13 * must display the following acknowledgement:
14 * This product includes software developed by Adam Glass and Charles
15 * Hannum.
16 * 4. The names of the authors may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include "opt_sysvipc.h"
32
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/sysmsg.h>
36 #include <sys/kernel.h>
37 #include <sys/sysctl.h>
38 #include <sys/shm.h>
39 #include <sys/proc.h>
40 #include <sys/malloc.h>
41 #include <sys/mman.h>
42 #include <sys/stat.h>
43 #include <sys/sysent.h>
44 #include <sys/jail.h>
45
46 #include <vm/vm.h>
47 #include <vm/vm_param.h>
48 #include <sys/lock.h>
49 #include <vm/pmap.h>
50 #include <vm/vm_object.h>
51 #include <vm/vm_map.h>
52 #include <vm/vm_page.h>
53 #include <vm/vm_pager.h>
54
55 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
56
57 static int shmget_allocate_segment(struct proc *p, struct sysmsg *sysmsg,
58 const struct shmget_args *uap, int mode);
59 static int shmget_existing(struct proc *p, struct sysmsg *sysmsg,
60 const struct shmget_args *uap, int mode, int segnum);
61
62 #define SHMSEG_FREE 0x0200
63 #define SHMSEG_REMOVED 0x0400
64 #define SHMSEG_ALLOCATED 0x0800
65 #define SHMSEG_WANTED 0x1000
66
67 static int shm_last_free, shm_committed, shmalloced, shm_nused;
68 static struct shmid_ds *shmsegs;
69 static struct lwkt_token shm_token = LWKT_TOKEN_INITIALIZER(shm_token);
70
71 struct shm_handle {
72 /* vm_offset_t kva; */
73 vm_object_t shm_object;
74 };
75
76 struct shmmap_state {
77 vm_offset_t va;
78 int shmid;
79 int reserved;
80 };
81
82 static void shm_deallocate_segment (struct shmid_ds *);
83 static int shm_find_segment_by_key (key_t);
84 static struct shmid_ds *shm_find_segment_by_shmid (int);
85 static int shm_delete_mapping (struct vmspace *vm, struct shmmap_state *);
86 static void shmrealloc (void);
87 static void shminit (void *);
88
89 /*
90 * Tuneable values
91 */
92 #ifndef SHMMIN
93 #define SHMMIN 1
94 #endif
95 #ifndef SHMMNI
96 #define SHMMNI 512
97 #endif
98 #ifndef SHMSEG
99 #define SHMSEG 1024
100 #endif
101
102 struct shminfo shminfo = {
103 0,
104 SHMMIN,
105 SHMMNI,
106 SHMSEG,
107 0
108 };
109
110 /*
111 * allow-removed Allow a shared memory segment to be attached by its shmid
112 * even after it has been deleted, as long as it was still
113 * being referenced by someone. This is a trick used by
114 * chrome and other applications to avoid leaving shm
115 * segments hanging around after the application is killed
116 * or seg-faults unexpectedly.
117 *
118 * use-phys Shared memory segments are to use physical memory by
119 * default, which may allow the kernel to better-optimize
120 * the pmap and reduce overhead. The pages are effectively
121 * wired.
122 */
123 static int shm_allow_removed = 1;
124 static int shm_use_phys = 1;
125
126 TUNABLE_LONG("kern.ipc.shmmin", &shminfo.shmmin);
127 TUNABLE_LONG("kern.ipc.shmmni", &shminfo.shmmni);
128 TUNABLE_LONG("kern.ipc.shmseg", &shminfo.shmseg);
129 TUNABLE_LONG("kern.ipc.shmmaxpgs", &shminfo.shmall);
130 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys);
131
132 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0,
133 "Max shared memory segment size");
134 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0,
135 "Min shared memory segment size");
136 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0,
137 "Max number of shared memory identifiers");
138 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0,
139 "Max shared memory segments per process");
140 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0,
141 "Max pages of shared memory");
142 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0,
143 "Use phys pager allocation instead of swap pager allocation");
144 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_allow_removed, CTLFLAG_RW,
145 &shm_allow_removed, 0,
146 "Enable/Disable attachment to attached segments marked for removal");
147
148 static int
shm_find_segment_by_key(key_t key)149 shm_find_segment_by_key(key_t key)
150 {
151 int i;
152
153 for (i = 0; i < shmalloced; i++) {
154 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
155 shmsegs[i].shm_perm.key == key)
156 return i;
157 }
158 return -1;
159 }
160
161 static struct shmid_ds *
shm_find_segment_by_shmid(int shmid)162 shm_find_segment_by_shmid(int shmid)
163 {
164 int segnum;
165 struct shmid_ds *shmseg;
166
167 segnum = IPCID_TO_IX(shmid);
168 if (segnum < 0 || segnum >= shmalloced)
169 return NULL;
170 shmseg = &shmsegs[segnum];
171 if ((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) == 0 ||
172 (!shm_allow_removed &&
173 (shmseg->shm_perm.mode & SHMSEG_REMOVED) != 0) ||
174 shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid)) {
175 return NULL;
176 }
177 return shmseg;
178 }
179
180 static void
shm_deallocate_segment(struct shmid_ds * shmseg)181 shm_deallocate_segment(struct shmid_ds *shmseg)
182 {
183 struct shm_handle *shm_handle;
184 size_t size;
185
186 shm_handle = shmseg->shm_internal;
187 vm_object_deallocate(shm_handle->shm_object);
188 kfree((caddr_t)shm_handle, M_SHM);
189 shmseg->shm_internal = NULL;
190 size = round_page(shmseg->shm_segsz);
191 shm_committed -= btoc(size);
192 shm_nused--;
193 shmseg->shm_perm.mode = SHMSEG_FREE;
194 }
195
196 static int
shm_delete_mapping(struct vmspace * vm,struct shmmap_state * shmmap_s)197 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
198 {
199 struct shmid_ds *shmseg;
200 int segnum, result;
201 size_t size;
202
203 segnum = IPCID_TO_IX(shmmap_s->shmid);
204 shmseg = &shmsegs[segnum];
205 size = round_page(shmseg->shm_segsz);
206 result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
207 if (result != KERN_SUCCESS)
208 return EINVAL;
209 shmmap_s->shmid = -1;
210 shmseg->shm_dtime = time_second;
211 if ((--shmseg->shm_nattch <= 0) &&
212 (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
213 shm_deallocate_segment(shmseg);
214 shm_last_free = segnum;
215 }
216 return 0;
217 }
218
219 /*
220 * MPALMOSTSAFE
221 */
222 int
sys_shmdt(struct sysmsg * sysmsg,const struct shmdt_args * uap)223 sys_shmdt(struct sysmsg *sysmsg, const struct shmdt_args *uap)
224 {
225 struct thread *td = curthread;
226 struct proc *p = td->td_proc;
227 struct shmmap_state *shmmap_s;
228 struct prison *pr = p->p_ucred->cr_prison;
229
230 long i;
231 int error;
232
233 if (pr && !PRISON_CAP_ISSET(pr->pr_caps, PRISON_CAP_SYS_SYSVIPC))
234 return (ENOSYS);
235
236 lwkt_gettoken(&shm_token);
237 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
238 if (shmmap_s == NULL) {
239 error = EINVAL;
240 goto done;
241 }
242 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
243 if (shmmap_s->shmid != -1 &&
244 shmmap_s->va == (vm_offset_t)uap->shmaddr)
245 break;
246 }
247 if (i == shminfo.shmseg)
248 error = EINVAL;
249 else
250 error = shm_delete_mapping(p->p_vmspace, shmmap_s);
251 done:
252 lwkt_reltoken(&shm_token);
253
254 return (error);
255 }
256
257 /*
258 * MPALMOSTSAFE
259 */
260 int
sys_shmat(struct sysmsg * sysmsg,const struct shmat_args * uap)261 sys_shmat(struct sysmsg *sysmsg, const struct shmat_args *uap)
262 {
263 struct thread *td = curthread;
264 struct proc *p = td->td_proc;
265 struct prison *pr = p->p_ucred->cr_prison;
266 int error, flags;
267 long i;
268 struct shmid_ds *shmseg;
269 struct shmmap_state *shmmap_s = NULL;
270 struct shm_handle *shm_handle;
271 vm_offset_t attach_va;
272 vm_prot_t prot;
273 vm_size_t size;
274 vm_size_t align;
275 int rv;
276
277 if (pr && !PRISON_CAP_ISSET(pr->pr_caps, PRISON_CAP_SYS_SYSVIPC))
278 return (ENOSYS);
279
280 lwkt_gettoken(&shm_token);
281 again:
282 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
283 if (shmmap_s == NULL) {
284 size = shminfo.shmseg * sizeof(struct shmmap_state);
285 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
286 for (i = 0; i < shminfo.shmseg; i++) {
287 shmmap_s[i].shmid = -1;
288 shmmap_s[i].reserved = 0;
289 }
290 if (p->p_vmspace->vm_shm != NULL) {
291 kfree(shmmap_s, M_SHM);
292 goto again;
293 }
294 p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
295 }
296 shmseg = shm_find_segment_by_shmid(uap->shmid);
297 if (shmseg == NULL) {
298 error = EINVAL;
299 goto done;
300 }
301 error = ipcperm(p, &shmseg->shm_perm,
302 (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
303 if (error)
304 goto done;
305
306 /*
307 * Find a free element and mark reserved. This fixes races
308 * against concurrent allocations due to the token being
309 * interrupted by blocking operations. The shmmap_s reservation
310 * will be cleared upon completion or error.
311 */
312 for (i = 0; i < shminfo.shmseg; i++) {
313 if (shmmap_s->shmid == -1 && shmmap_s->reserved == 0) {
314 shmmap_s->reserved = 1;
315 break;
316 }
317 shmmap_s++;
318 }
319 if (i >= shminfo.shmseg) {
320 error = EMFILE;
321 goto done;
322 }
323 size = round_page(shmseg->shm_segsz);
324 #ifdef VM_PROT_READ_IS_EXEC
325 prot = VM_PROT_READ | VM_PROT_EXECUTE;
326 #else
327 prot = VM_PROT_READ;
328 #endif
329 if ((uap->shmflg & SHM_RDONLY) == 0)
330 prot |= VM_PROT_WRITE;
331 flags = MAP_ANON | MAP_SHARED;
332 if (uap->shmaddr) {
333 flags |= MAP_FIXED;
334 if (uap->shmflg & SHM_RND) {
335 attach_va =
336 rounddown2((vm_offset_t)uap->shmaddr, SHMLBA);
337 } else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) {
338 attach_va = (vm_offset_t)uap->shmaddr;
339 } else {
340 error = EINVAL;
341 shmmap_s->reserved = 0;
342 goto done;
343 }
344 } else {
345 /*
346 * This is just a hint to vm_map_find() about where to put it.
347 */
348 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr +
349 maxtsiz + maxdsiz);
350 }
351
352 /*
353 * Handle alignment. For large memory maps it is possible
354 * that the MMU can optimize the page table so align anything
355 * that is a multiple of SEG_SIZE to SEG_SIZE.
356 */
357 if ((flags & MAP_FIXED) == 0 && (size & SEG_MASK) == 0)
358 align = SEG_SIZE;
359 else
360 align = PAGE_SIZE;
361
362 shm_handle = shmseg->shm_internal;
363 vm_object_hold(shm_handle->shm_object);
364 vm_object_reference_locked(shm_handle->shm_object);
365 rv = vm_map_find(&p->p_vmspace->vm_map,
366 shm_handle->shm_object, NULL,
367 0, &attach_va, size,
368 align,
369 ((flags & MAP_FIXED) ? 0 : 1),
370 VM_MAPTYPE_NORMAL, VM_SUBSYS_SHMEM,
371 prot, prot, 0);
372 vm_object_drop(shm_handle->shm_object);
373 if (rv != KERN_SUCCESS) {
374 vm_object_deallocate(shm_handle->shm_object);
375 shmmap_s->reserved = 0;
376 error = ENOMEM;
377 goto done;
378 }
379 vm_map_inherit(&p->p_vmspace->vm_map,
380 attach_va, attach_va + size, VM_INHERIT_SHARE);
381
382 KKASSERT(shmmap_s->shmid == -1);
383 shmmap_s->va = attach_va;
384 shmmap_s->shmid = uap->shmid;
385 shmmap_s->reserved = 0;
386 shmseg->shm_lpid = p->p_pid;
387 shmseg->shm_atime = time_second;
388 shmseg->shm_nattch++;
389 sysmsg->sysmsg_resultp = (void *)attach_va;
390 error = 0;
391 done:
392 lwkt_reltoken(&shm_token);
393
394 return error;
395 }
396
397 /*
398 * MPALMOSTSAFE
399 */
400 int
sys_shmctl(struct sysmsg * sysmsg,const struct shmctl_args * uap)401 sys_shmctl(struct sysmsg *sysmsg, const struct shmctl_args *uap)
402 {
403 struct thread *td = curthread;
404 struct proc *p = td->td_proc;
405 struct prison *pr = p->p_ucred->cr_prison;
406 int error;
407 struct shmid_ds inbuf;
408 struct shmid_ds *shmseg;
409
410 if (pr && !PRISON_CAP_ISSET(pr->pr_caps, PRISON_CAP_SYS_SYSVIPC))
411 return (ENOSYS);
412
413 lwkt_gettoken(&shm_token);
414 shmseg = shm_find_segment_by_shmid(uap->shmid);
415 if (shmseg == NULL) {
416 error = EINVAL;
417 goto done;
418 }
419
420 switch (uap->cmd) {
421 case IPC_STAT:
422 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
423 if (error == 0)
424 error = copyout(shmseg, uap->buf, sizeof(inbuf));
425 break;
426 case IPC_SET:
427 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
428 if (error == 0)
429 error = copyin(uap->buf, &inbuf, sizeof(inbuf));
430 if (error == 0) {
431 shmseg->shm_perm.uid = inbuf.shm_perm.uid;
432 shmseg->shm_perm.gid = inbuf.shm_perm.gid;
433 shmseg->shm_perm.mode =
434 (shmseg->shm_perm.mode & ~ACCESSPERMS) |
435 (inbuf.shm_perm.mode & ACCESSPERMS);
436 shmseg->shm_ctime = time_second;
437 }
438 break;
439 case IPC_RMID:
440 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
441 if (error == 0) {
442 shmseg->shm_perm.key = IPC_PRIVATE;
443 shmseg->shm_perm.mode |= SHMSEG_REMOVED;
444 if (shmseg->shm_nattch <= 0) {
445 shm_deallocate_segment(shmseg);
446 shm_last_free = IPCID_TO_IX(uap->shmid);
447 }
448 }
449 break;
450 #if 0
451 case SHM_LOCK:
452 case SHM_UNLOCK:
453 #endif
454 default:
455 error = EINVAL;
456 break;
457 }
458 done:
459 lwkt_reltoken(&shm_token);
460
461 return error;
462 }
463
464 static int
shmget_existing(struct proc * p,struct sysmsg * sysmsg,const struct shmget_args * uap,int mode,int segnum)465 shmget_existing(struct proc *p, struct sysmsg *sysmsg,
466 const struct shmget_args *uap, int mode, int segnum)
467 {
468 struct shmid_ds *shmseg;
469 int error;
470
471 shmseg = &shmsegs[segnum];
472 if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
473 /*
474 * This segment is in the process of being allocated. Wait
475 * until it's done, and look the key up again (in case the
476 * allocation failed or it was freed).
477 */
478 shmseg->shm_perm.mode |= SHMSEG_WANTED;
479 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
480 if (error)
481 return error;
482 return EAGAIN;
483 }
484 if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
485 return EEXIST;
486 error = ipcperm(p, &shmseg->shm_perm, mode);
487 if (error)
488 return error;
489 if (uap->size && uap->size > shmseg->shm_segsz)
490 return EINVAL;
491 sysmsg->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
492 return 0;
493 }
494
495 static int
shmget_allocate_segment(struct proc * p,struct sysmsg * sysmsg,const struct shmget_args * uap,int mode)496 shmget_allocate_segment(struct proc *p, struct sysmsg *sysmsg,
497 const struct shmget_args *uap, int mode)
498 {
499 int i, segnum, shmid;
500 size_t size;
501 struct ucred *cred = p->p_ucred;
502 struct shmid_ds *shmseg;
503 struct shm_handle *shm_handle;
504
505 if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
506 return EINVAL;
507 if (shm_nused >= shminfo.shmmni) /* any shmids left? */
508 return ENOSPC;
509 size = round_page(uap->size);
510 if (shm_committed + btoc(size) > shminfo.shmall)
511 return ENOMEM;
512 if (shm_last_free < 0) {
513 shmrealloc(); /* maybe expand the shmsegs[] array */
514 for (i = 0; i < shmalloced; i++) {
515 if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
516 break;
517 }
518 if (i == shmalloced)
519 return ENOSPC;
520 segnum = i;
521 } else {
522 segnum = shm_last_free;
523 shm_last_free = -1;
524 }
525 shmseg = &shmsegs[segnum];
526 /*
527 * In case we sleep in malloc(), mark the segment present but deleted
528 * so that noone else tries to create the same key.
529 */
530 shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
531 shmseg->shm_perm.key = uap->key;
532 shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
533 shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
534 shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
535
536 /*
537 * We make sure that we have allocated a pager before we need
538 * to.
539 */
540 if (shm_use_phys) {
541 shm_handle->shm_object =
542 phys_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
543 } else {
544 shm_handle->shm_object =
545 swap_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
546 }
547 vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
548 vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
549
550 shmseg->shm_internal = shm_handle;
551 shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
552 shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
553 shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
554 (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
555 shmseg->shm_segsz = uap->size;
556 shmseg->shm_cpid = p->p_pid;
557 shmseg->shm_lpid = shmseg->shm_nattch = 0;
558 shmseg->shm_atime = shmseg->shm_dtime = 0;
559 shmseg->shm_ctime = time_second;
560 shm_committed += btoc(size);
561 shm_nused++;
562
563 /*
564 * If a physical mapping is desired and we have a ton of free pages
565 * we pre-allocate the pages here in order to avoid on-the-fly
566 * allocation later. This has a big effect on database warm-up
567 * times since DFly supports concurrent page faults coming from the
568 * same VM object for pages which already exist.
569 *
570 * This can hang the kernel for a while so only do it if shm_use_phys
571 * is set to 2 or higher.
572 */
573 if (shm_use_phys > 1) {
574 vm_pindex_t pi, pmax;
575 vm_page_t m;
576
577 pmax = round_page(shmseg->shm_segsz) >> PAGE_SHIFT;
578 vm_object_hold(shm_handle->shm_object);
579 if (pmax > vmstats.v_free_count)
580 pmax = vmstats.v_free_count;
581 for (pi = 0; pi < pmax; ++pi) {
582 m = vm_page_grab(shm_handle->shm_object, pi,
583 VM_ALLOC_SYSTEM | VM_ALLOC_NULL_OK |
584 VM_ALLOC_ZERO);
585 if (m == NULL)
586 break;
587 vm_pager_get_page(shm_handle->shm_object, pi, &m, 1);
588 vm_page_activate(m);
589 vm_page_wakeup(m);
590 lwkt_yield();
591 }
592 vm_object_drop(shm_handle->shm_object);
593 }
594
595 if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
596 /*
597 * Somebody else wanted this key while we were asleep. Wake
598 * them up now.
599 */
600 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
601 wakeup((caddr_t)shmseg);
602 }
603 sysmsg->sysmsg_result = shmid;
604 return 0;
605 }
606
607 /*
608 * MPALMOSTSAFE
609 */
610 int
sys_shmget(struct sysmsg * sysmsg,const struct shmget_args * uap)611 sys_shmget(struct sysmsg *sysmsg, const struct shmget_args *uap)
612 {
613 struct thread *td = curthread;
614 struct proc *p = td->td_proc;
615 struct prison *pr = p->p_ucred->cr_prison;
616 int segnum, mode, error;
617
618 if (pr && !PRISON_CAP_ISSET(pr->pr_caps, PRISON_CAP_SYS_SYSVIPC))
619 return (ENOSYS);
620
621 mode = uap->shmflg & ACCESSPERMS;
622
623 lwkt_gettoken(&shm_token);
624
625 if (uap->key != IPC_PRIVATE) {
626 again:
627 segnum = shm_find_segment_by_key(uap->key);
628 if (segnum >= 0) {
629 error = shmget_existing(p, sysmsg, uap, mode, segnum);
630 if (error == EAGAIN)
631 goto again;
632 goto done;
633 }
634 if ((uap->shmflg & IPC_CREAT) == 0) {
635 error = ENOENT;
636 goto done;
637 }
638 }
639 error = shmget_allocate_segment(p, sysmsg, uap, mode);
640 done:
641 lwkt_reltoken(&shm_token);
642
643 return (error);
644 }
645
646 void
shmfork(struct proc * p1,struct proc * p2)647 shmfork(struct proc *p1, struct proc *p2)
648 {
649 struct shmmap_state *shmmap_s;
650 size_t size;
651 int i;
652
653 lwkt_gettoken(&shm_token);
654 size = shminfo.shmseg * sizeof(struct shmmap_state);
655 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
656 bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
657 p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
658 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
659 if (shmmap_s->shmid != -1)
660 shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
661 }
662 lwkt_reltoken(&shm_token);
663 }
664
665 void
shmexit(struct vmspace * vm)666 shmexit(struct vmspace *vm)
667 {
668 struct shmmap_state *base, *shm;
669 int i;
670
671 if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
672 vm->vm_shm = NULL;
673 lwkt_gettoken(&shm_token);
674 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
675 if (shm->shmid != -1)
676 shm_delete_mapping(vm, shm);
677 }
678 kfree(base, M_SHM);
679 lwkt_reltoken(&shm_token);
680 }
681 }
682
683 static void
shmrealloc(void)684 shmrealloc(void)
685 {
686 int i;
687 struct shmid_ds *newsegs;
688
689 if (shmalloced >= shminfo.shmmni)
690 return;
691
692 newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
693 for (i = 0; i < shmalloced; i++)
694 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
695 for (; i < shminfo.shmmni; i++) {
696 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
697 shmsegs[i].shm_perm.seq = 0;
698 }
699 kfree(shmsegs, M_SHM);
700 shmsegs = newsegs;
701 shmalloced = shminfo.shmmni;
702 }
703
704 static void
shminit(void * dummy)705 shminit(void *dummy)
706 {
707 int i;
708
709 /*
710 * If not overridden by a tunable set the maximum shm to
711 * 2/3 of main memory.
712 */
713 if (shminfo.shmall == 0)
714 shminfo.shmall = (size_t)vmstats.v_page_count * 2 / 3;
715
716 shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
717 shmalloced = shminfo.shmmni;
718 shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
719 for (i = 0; i < shmalloced; i++) {
720 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
721 shmsegs[i].shm_perm.seq = 0;
722 }
723 shm_last_free = 0;
724 shm_nused = 0;
725 shm_committed = 0;
726 }
727 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);
728