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