1 /* $FreeBSD: src/sys/kern/sysv_shm.c,v 1.45.2.6 2002/10/22 20:45:03 fjoe Exp $ */ 2 /* $DragonFly: src/sys/kern/sysv_shm.c,v 1.21 2008/01/06 16:55:51 swildner Exp $ */ 3 /* $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $ */ 4 5 /* 6 * Copyright (c) 1994 Adam Glass and Charles Hannum. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Adam Glass and Charles 19 * Hannum. 20 * 4. The names of the authors may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 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/sysproto.h> 41 #include <sys/kernel.h> 42 #include <sys/sysctl.h> 43 #include <sys/shm.h> 44 #include <sys/proc.h> 45 #include <sys/malloc.h> 46 #include <sys/mman.h> 47 #include <sys/stat.h> 48 #include <sys/sysent.h> 49 #include <sys/jail.h> 50 51 #include <sys/mplock2.h> 52 53 #include <vm/vm.h> 54 #include <vm/vm_param.h> 55 #include <sys/lock.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 62 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments"); 63 64 struct oshmctl_args; 65 static int sys_oshmctl (struct proc *p, struct oshmctl_args *uap); 66 67 static int shmget_allocate_segment (struct proc *p, struct shmget_args *uap, int mode); 68 static int shmget_existing (struct proc *p, struct shmget_args *uap, int mode, int segnum); 69 70 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 71 static sy_call_t *shmcalls[] = { 72 (sy_call_t *)sys_shmat, (sy_call_t *)sys_oshmctl, 73 (sy_call_t *)sys_shmdt, (sy_call_t *)sys_shmget, 74 (sy_call_t *)sys_shmctl 75 }; 76 77 #define SHMSEG_FREE 0x0200 78 #define SHMSEG_REMOVED 0x0400 79 #define SHMSEG_ALLOCATED 0x0800 80 #define SHMSEG_WANTED 0x1000 81 82 static int shm_last_free, shm_committed, shmalloced; 83 int shm_nused; 84 static struct shmid_ds *shmsegs; 85 86 struct shm_handle { 87 /* vm_offset_t kva; */ 88 vm_object_t shm_object; 89 }; 90 91 struct shmmap_state { 92 vm_offset_t va; 93 int shmid; 94 }; 95 96 static void shm_deallocate_segment (struct shmid_ds *); 97 static int shm_find_segment_by_key (key_t); 98 static struct shmid_ds *shm_find_segment_by_shmid (int); 99 static int shm_delete_mapping (struct vmspace *vm, struct shmmap_state *); 100 static void shmrealloc (void); 101 static void shminit (void *); 102 103 /* 104 * Tuneable values 105 */ 106 #ifndef SHMMAXPGS 107 #define SHMMAXPGS 8192 /* note: sysv shared memory is swap backed */ 108 #endif 109 #ifndef SHMMAX 110 #define SHMMAX (SHMMAXPGS*PAGE_SIZE) 111 #endif 112 #ifndef SHMMIN 113 #define SHMMIN 1 114 #endif 115 #ifndef SHMMNI 116 #define SHMMNI 192 117 #endif 118 #ifndef SHMSEG 119 #define SHMSEG 128 120 #endif 121 #ifndef SHMALL 122 #define SHMALL (SHMMAXPGS) 123 #endif 124 125 struct shminfo shminfo = { 126 SHMMAX, 127 SHMMIN, 128 SHMMNI, 129 SHMSEG, 130 SHMALL 131 }; 132 133 static int shm_use_phys; 134 135 TUNABLE_INT("kern.ipc.shmmin", &shminfo.shmmin); 136 TUNABLE_INT("kern.ipc.shmmni", &shminfo.shmmni); 137 TUNABLE_INT("kern.ipc.shmseg", &shminfo.shmseg); 138 TUNABLE_INT("kern.ipc.shmmaxpgs", &shminfo.shmall); 139 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys); 140 141 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, 142 "Max shared memory segment size"); 143 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, 144 "Min shared memory segment size"); 145 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0, 146 "Max number of shared memory identifiers"); 147 SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0, 148 "Max shared memory segments per process"); 149 SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, 150 "Max pages of shared memory"); 151 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0, 152 "Use phys pager allocation instead of swap pager allocation"); 153 154 static int 155 shm_find_segment_by_key(key_t key) 156 { 157 int i; 158 159 for (i = 0; i < shmalloced; i++) 160 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) && 161 shmsegs[i].shm_perm.key == key) 162 return i; 163 return -1; 164 } 165 166 static struct shmid_ds * 167 shm_find_segment_by_shmid(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 } 182 183 static void 184 shm_deallocate_segment(struct shmid_ds *shmseg) 185 { 186 struct shm_handle *shm_handle; 187 size_t size; 188 189 shm_handle = shmseg->shm_internal; 190 vm_object_deallocate(shm_handle->shm_object); 191 kfree((caddr_t)shm_handle, M_SHM); 192 shmseg->shm_internal = NULL; 193 size = round_page(shmseg->shm_segsz); 194 shm_committed -= btoc(size); 195 shm_nused--; 196 shmseg->shm_perm.mode = SHMSEG_FREE; 197 } 198 199 static int 200 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s) 201 { 202 struct shmid_ds *shmseg; 203 int segnum, result; 204 size_t size; 205 206 segnum = IPCID_TO_IX(shmmap_s->shmid); 207 shmseg = &shmsegs[segnum]; 208 size = round_page(shmseg->shm_segsz); 209 result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size); 210 if (result != KERN_SUCCESS) 211 return EINVAL; 212 shmmap_s->shmid = -1; 213 shmseg->shm_dtime = time_second; 214 if ((--shmseg->shm_nattch <= 0) && 215 (shmseg->shm_perm.mode & SHMSEG_REMOVED)) { 216 shm_deallocate_segment(shmseg); 217 shm_last_free = segnum; 218 } 219 return 0; 220 } 221 222 /* 223 * MPALMOSTSAFE 224 */ 225 int 226 sys_shmdt(struct shmdt_args *uap) 227 { 228 struct thread *td = curthread; 229 struct proc *p = td->td_proc; 230 struct shmmap_state *shmmap_s; 231 int i; 232 int error; 233 234 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 235 return (ENOSYS); 236 237 get_mplock(); 238 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm; 239 if (shmmap_s == NULL) { 240 error = EINVAL; 241 goto done; 242 } 243 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) { 244 if (shmmap_s->shmid != -1 && 245 shmmap_s->va == (vm_offset_t)uap->shmaddr) 246 break; 247 } 248 if (i == shminfo.shmseg) 249 error = EINVAL; 250 else 251 error = shm_delete_mapping(p->p_vmspace, shmmap_s); 252 done: 253 rel_mplock(); 254 return (error); 255 } 256 257 /* 258 * MPALMOSTSAFE 259 */ 260 int 261 sys_shmat(struct shmat_args *uap) 262 { 263 struct thread *td = curthread; 264 struct proc *p = td->td_proc; 265 int error, i, flags; 266 struct shmid_ds *shmseg; 267 struct shmmap_state *shmmap_s = NULL; 268 struct shm_handle *shm_handle; 269 vm_offset_t attach_va; 270 vm_prot_t prot; 271 vm_size_t size; 272 int rv; 273 274 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 275 return (ENOSYS); 276 277 get_mplock(); 278 again: 279 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm; 280 if (shmmap_s == NULL) { 281 size = shminfo.shmseg * sizeof(struct shmmap_state); 282 shmmap_s = kmalloc(size, M_SHM, M_WAITOK); 283 for (i = 0; i < shminfo.shmseg; i++) 284 shmmap_s[i].shmid = -1; 285 if (p->p_vmspace->vm_shm != NULL) { 286 kfree(shmmap_s, M_SHM); 287 goto again; 288 } 289 p->p_vmspace->vm_shm = (caddr_t)shmmap_s; 290 } 291 shmseg = shm_find_segment_by_shmid(uap->shmid); 292 if (shmseg == NULL) { 293 error = EINVAL; 294 goto done; 295 } 296 error = ipcperm(p, &shmseg->shm_perm, 297 (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W); 298 if (error) 299 goto done; 300 for (i = 0; i < shminfo.shmseg; i++) { 301 if (shmmap_s->shmid == -1) 302 break; 303 shmmap_s++; 304 } 305 if (i >= shminfo.shmseg) { 306 error = EMFILE; 307 goto done; 308 } 309 size = round_page(shmseg->shm_segsz); 310 #ifdef VM_PROT_READ_IS_EXEC 311 prot = VM_PROT_READ | VM_PROT_EXECUTE; 312 #else 313 prot = VM_PROT_READ; 314 #endif 315 if ((uap->shmflg & SHM_RDONLY) == 0) 316 prot |= VM_PROT_WRITE; 317 flags = MAP_ANON | MAP_SHARED; 318 if (uap->shmaddr) { 319 flags |= MAP_FIXED; 320 if (uap->shmflg & SHM_RND) { 321 attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1); 322 } else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) { 323 attach_va = (vm_offset_t)uap->shmaddr; 324 } else { 325 error = EINVAL; 326 goto done; 327 } 328 } else { 329 /* 330 * This is just a hint to vm_map_find() about where to put it. 331 */ 332 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + maxtsiz + maxdsiz); 333 } 334 335 shm_handle = shmseg->shm_internal; 336 vm_object_reference(shm_handle->shm_object); 337 rv = vm_map_find(&p->p_vmspace->vm_map, 338 shm_handle->shm_object, 0, 339 &attach_va, 340 size, PAGE_SIZE, 341 ((flags & MAP_FIXED) ? 0 : 1), 342 VM_MAPTYPE_NORMAL, 343 prot, prot, 344 0); 345 if (rv != KERN_SUCCESS) { 346 vm_object_deallocate(shm_handle->shm_object); 347 error = ENOMEM; 348 goto done; 349 } 350 vm_map_inherit(&p->p_vmspace->vm_map, 351 attach_va, attach_va + size, VM_INHERIT_SHARE); 352 353 KKASSERT(shmmap_s->shmid == -1); 354 shmmap_s->va = attach_va; 355 shmmap_s->shmid = uap->shmid; 356 shmseg->shm_lpid = p->p_pid; 357 shmseg->shm_atime = time_second; 358 shmseg->shm_nattch++; 359 uap->sysmsg_resultp = (void *)attach_va; 360 error = 0; 361 done: 362 rel_mplock(); 363 return error; 364 } 365 366 struct oshmid_ds { 367 struct ipc_perm shm_perm; /* operation perms */ 368 int shm_segsz; /* size of segment (bytes) */ 369 ushort shm_cpid; /* pid, creator */ 370 ushort shm_lpid; /* pid, last operation */ 371 short shm_nattch; /* no. of current attaches */ 372 time_t shm_atime; /* last attach time */ 373 time_t shm_dtime; /* last detach time */ 374 time_t shm_ctime; /* last change time */ 375 void *shm_handle; /* internal handle for shm segment */ 376 }; 377 378 struct oshmctl_args { 379 struct sysmsg sysmsg; 380 int shmid; 381 int cmd; 382 struct oshmid_ds *ubuf; 383 }; 384 385 /* 386 * MPALMOSTSAFE 387 */ 388 static int 389 sys_oshmctl(struct proc *p, struct oshmctl_args *uap) 390 { 391 #ifdef COMPAT_43 392 struct thread *td = curthread; 393 struct shmid_ds *shmseg; 394 struct oshmid_ds outbuf; 395 int error; 396 397 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 398 return (ENOSYS); 399 400 get_mplock(); 401 shmseg = shm_find_segment_by_shmid(uap->shmid); 402 if (shmseg == NULL) { 403 error = EINVAL; 404 goto done; 405 } 406 407 switch (uap->cmd) { 408 case IPC_STAT: 409 error = ipcperm(p, &shmseg->shm_perm, IPC_R); 410 if (error) 411 break; 412 outbuf.shm_perm = shmseg->shm_perm; 413 outbuf.shm_segsz = shmseg->shm_segsz; 414 outbuf.shm_cpid = shmseg->shm_cpid; 415 outbuf.shm_lpid = shmseg->shm_lpid; 416 outbuf.shm_nattch = shmseg->shm_nattch; 417 outbuf.shm_atime = shmseg->shm_atime; 418 outbuf.shm_dtime = shmseg->shm_dtime; 419 outbuf.shm_ctime = shmseg->shm_ctime; 420 outbuf.shm_handle = shmseg->shm_internal; 421 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf)); 422 break; 423 default: 424 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 425 error = sys_shmctl((struct shmctl_args *)uap); 426 } 427 done: 428 rel_mplock(); 429 return error; 430 #else 431 return EINVAL; 432 #endif 433 } 434 435 /* 436 * MPALMOSTSAFE 437 */ 438 int 439 sys_shmctl(struct shmctl_args *uap) 440 { 441 struct thread *td = curthread; 442 struct proc *p = td->td_proc; 443 int error; 444 struct shmid_ds inbuf; 445 struct shmid_ds *shmseg; 446 447 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 448 return (ENOSYS); 449 450 get_mplock(); 451 shmseg = shm_find_segment_by_shmid(uap->shmid); 452 if (shmseg == NULL) { 453 error = EINVAL; 454 goto done; 455 } 456 457 switch (uap->cmd) { 458 case IPC_STAT: 459 error = ipcperm(p, &shmseg->shm_perm, IPC_R); 460 if (error == 0) 461 error = copyout(shmseg, uap->buf, sizeof(inbuf)); 462 break; 463 case IPC_SET: 464 error = ipcperm(p, &shmseg->shm_perm, IPC_M); 465 if (error == 0) 466 error = copyin(uap->buf, &inbuf, sizeof(inbuf)); 467 if (error == 0) { 468 shmseg->shm_perm.uid = inbuf.shm_perm.uid; 469 shmseg->shm_perm.gid = inbuf.shm_perm.gid; 470 shmseg->shm_perm.mode = 471 (shmseg->shm_perm.mode & ~ACCESSPERMS) | 472 (inbuf.shm_perm.mode & ACCESSPERMS); 473 shmseg->shm_ctime = time_second; 474 } 475 break; 476 case IPC_RMID: 477 error = ipcperm(p, &shmseg->shm_perm, IPC_M); 478 if (error == 0) { 479 shmseg->shm_perm.key = IPC_PRIVATE; 480 shmseg->shm_perm.mode |= SHMSEG_REMOVED; 481 if (shmseg->shm_nattch <= 0) { 482 shm_deallocate_segment(shmseg); 483 shm_last_free = IPCID_TO_IX(uap->shmid); 484 } 485 } 486 break; 487 #if 0 488 case SHM_LOCK: 489 case SHM_UNLOCK: 490 #endif 491 default: 492 error = EINVAL; 493 break; 494 } 495 done: 496 rel_mplock(); 497 return error; 498 } 499 500 static int 501 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum) 502 { 503 struct shmid_ds *shmseg; 504 int error; 505 506 shmseg = &shmsegs[segnum]; 507 if (shmseg->shm_perm.mode & SHMSEG_REMOVED) { 508 /* 509 * This segment is in the process of being allocated. Wait 510 * until it's done, and look the key up again (in case the 511 * allocation failed or it was freed). 512 */ 513 shmseg->shm_perm.mode |= SHMSEG_WANTED; 514 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0); 515 if (error) 516 return error; 517 return EAGAIN; 518 } 519 if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL)) 520 return EEXIST; 521 error = ipcperm(p, &shmseg->shm_perm, mode); 522 if (error) 523 return error; 524 if (uap->size && uap->size > shmseg->shm_segsz) 525 return EINVAL; 526 uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm); 527 return 0; 528 } 529 530 static int 531 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode) 532 { 533 int i, segnum, shmid, size; 534 struct ucred *cred = p->p_ucred; 535 struct shmid_ds *shmseg; 536 struct shm_handle *shm_handle; 537 538 if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax) 539 return EINVAL; 540 if (shm_nused >= shminfo.shmmni) /* any shmids left? */ 541 return ENOSPC; 542 size = round_page(uap->size); 543 if (shm_committed + btoc(size) > shminfo.shmall) 544 return ENOMEM; 545 if (shm_last_free < 0) { 546 shmrealloc(); /* maybe expand the shmsegs[] array */ 547 for (i = 0; i < shmalloced; i++) 548 if (shmsegs[i].shm_perm.mode & SHMSEG_FREE) 549 break; 550 if (i == shmalloced) 551 return ENOSPC; 552 segnum = i; 553 } else { 554 segnum = shm_last_free; 555 shm_last_free = -1; 556 } 557 shmseg = &shmsegs[segnum]; 558 /* 559 * In case we sleep in malloc(), mark the segment present but deleted 560 * so that noone else tries to create the same key. 561 */ 562 shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED; 563 shmseg->shm_perm.key = uap->key; 564 shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff; 565 shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK); 566 shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm); 567 568 /* 569 * We make sure that we have allocated a pager before we need 570 * to. 571 */ 572 if (shm_use_phys) { 573 shm_handle->shm_object = 574 phys_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0); 575 } else { 576 shm_handle->shm_object = 577 swap_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0); 578 } 579 vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING); 580 vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT); 581 582 shmseg->shm_internal = shm_handle; 583 shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid; 584 shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid; 585 shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) | 586 (mode & ACCESSPERMS) | SHMSEG_ALLOCATED; 587 shmseg->shm_segsz = uap->size; 588 shmseg->shm_cpid = p->p_pid; 589 shmseg->shm_lpid = shmseg->shm_nattch = 0; 590 shmseg->shm_atime = shmseg->shm_dtime = 0; 591 shmseg->shm_ctime = time_second; 592 shm_committed += btoc(size); 593 shm_nused++; 594 if (shmseg->shm_perm.mode & SHMSEG_WANTED) { 595 /* 596 * Somebody else wanted this key while we were asleep. Wake 597 * them up now. 598 */ 599 shmseg->shm_perm.mode &= ~SHMSEG_WANTED; 600 wakeup((caddr_t)shmseg); 601 } 602 uap->sysmsg_result = shmid; 603 return 0; 604 } 605 606 /* 607 * MPALMOSTSAFE 608 */ 609 int 610 sys_shmget(struct shmget_args *uap) 611 { 612 struct thread *td = curthread; 613 struct proc *p = td->td_proc; 614 int segnum, mode, error; 615 616 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 617 return (ENOSYS); 618 619 mode = uap->shmflg & ACCESSPERMS; 620 get_mplock(); 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 rel_mplock(); 639 return (error); 640 } 641 642 /* 643 * shmsys_args(int which, int a2, ...) (VARARGS) 644 * 645 * MPALMOSTSAFE 646 */ 647 int 648 sys_shmsys(struct shmsys_args *uap) 649 { 650 struct thread *td = curthread; 651 unsigned int which = (unsigned int)uap->which; 652 int error; 653 654 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 655 return (ENOSYS); 656 657 if (which >= sizeof(shmcalls)/sizeof(shmcalls[0])) 658 return EINVAL; 659 get_mplock(); 660 bcopy(&uap->a2, &uap->which, 661 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2)); 662 error = ((*shmcalls[which])(uap)); 663 rel_mplock(); 664 665 return(error); 666 } 667 668 void 669 shmfork(struct proc *p1, struct proc *p2) 670 { 671 struct shmmap_state *shmmap_s; 672 size_t size; 673 int i; 674 675 size = shminfo.shmseg * sizeof(struct shmmap_state); 676 shmmap_s = kmalloc(size, M_SHM, M_WAITOK); 677 bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size); 678 p2->p_vmspace->vm_shm = (caddr_t)shmmap_s; 679 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) 680 if (shmmap_s->shmid != -1) 681 shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++; 682 } 683 684 void 685 shmexit(struct vmspace *vm) 686 { 687 struct shmmap_state *base, *shm; 688 int i; 689 690 if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) { 691 vm->vm_shm = NULL; 692 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) { 693 if (shm->shmid != -1) 694 shm_delete_mapping(vm, shm); 695 } 696 kfree(base, M_SHM); 697 } 698 } 699 700 static void 701 shmrealloc(void) 702 { 703 int i; 704 struct shmid_ds *newsegs; 705 706 if (shmalloced >= shminfo.shmmni) 707 return; 708 709 newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK); 710 for (i = 0; i < shmalloced; i++) 711 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0])); 712 for (; i < shminfo.shmmni; i++) { 713 shmsegs[i].shm_perm.mode = SHMSEG_FREE; 714 shmsegs[i].shm_perm.seq = 0; 715 } 716 kfree(shmsegs, M_SHM); 717 shmsegs = newsegs; 718 shmalloced = shminfo.shmmni; 719 } 720 721 static void 722 shminit(void *dummy) 723 { 724 int i; 725 726 shminfo.shmmax = shminfo.shmall * PAGE_SIZE; 727 shmalloced = shminfo.shmmni; 728 shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK); 729 for (i = 0; i < shmalloced; i++) { 730 shmsegs[i].shm_perm.mode = SHMSEG_FREE; 731 shmsegs[i].shm_perm.seq = 0; 732 } 733 shm_last_free = 0; 734 shm_nused = 0; 735 shm_committed = 0; 736 } 737 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL); 738