sysv_shm.c revision 1.40
1 /* $NetBSD: sysv_shm.c,v 1.40 1997/10/09 08:35:13 drochner Exp $ */ 2 3 /* 4 * Copyright (c) 1994 Adam Glass and Charles Hannum. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Adam Glass and Charles 17 * Hannum. 18 * 4. The names of the authors may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/kernel.h> 36 #include <sys/shm.h> 37 #include <sys/proc.h> 38 #include <sys/uio.h> 39 #include <sys/time.h> 40 #include <sys/malloc.h> 41 #include <sys/mman.h> 42 #include <sys/systm.h> 43 #include <sys/stat.h> 44 45 #include <sys/mount.h> 46 #include <sys/syscallargs.h> 47 48 #include <vm/vm.h> 49 #include <vm/vm_map.h> 50 #include <vm/vm_map.h> 51 #include <vm/vm_kern.h> 52 53 struct shmid_ds *shm_find_segment_by_shmid __P((int)); 54 void shmexit __P((struct proc *)); 55 56 /* 57 * Provides the following externally accessible functions: 58 * 59 * shminit(void); initialization 60 * shmexit(struct proc *) cleanup 61 * shmfork(struct proc *, struct proc *) fork handling 62 * shmsys(arg1, arg2, arg3, arg4); shm{at,ctl,dt,get}(arg2, arg3, arg4) 63 * 64 * Structures: 65 * shmsegs (an array of 'struct shmid_ds') 66 * per proc array of 'struct shmmap_state' 67 */ 68 69 #define SHMSEG_FREE 0x0200 70 #define SHMSEG_REMOVED 0x0400 71 #define SHMSEG_ALLOCATED 0x0800 72 #define SHMSEG_WANTED 0x1000 73 74 int shm_last_free, shm_nused, shm_committed; 75 76 struct shm_handle { 77 vm_object_t shm_object; 78 }; 79 80 struct shmmap_state { 81 vm_offset_t va; 82 int shmid; 83 }; 84 85 static int shm_find_segment_by_key __P((key_t)); 86 static void shm_deallocate_segment __P((struct shmid_ds *)); 87 static int shm_delete_mapping __P((struct proc *, struct shmmap_state *)); 88 static int shmget_existing __P((struct proc *, struct sys_shmget_args *, 89 int, int, register_t *)); 90 static int shmget_allocate_segment __P((struct proc *, struct sys_shmget_args *, 91 int, register_t *)); 92 93 static int 94 shm_find_segment_by_key(key) 95 key_t key; 96 { 97 int i; 98 99 for (i = 0; i < shminfo.shmmni; i++) 100 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) && 101 shmsegs[i].shm_perm.key == key) 102 return i; 103 return -1; 104 } 105 106 struct shmid_ds * 107 shm_find_segment_by_shmid(shmid) 108 int shmid; 109 { 110 int segnum; 111 struct shmid_ds *shmseg; 112 113 segnum = IPCID_TO_IX(shmid); 114 if (segnum < 0 || segnum >= shminfo.shmmni) 115 return NULL; 116 shmseg = &shmsegs[segnum]; 117 if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED)) 118 != SHMSEG_ALLOCATED || 119 shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid)) 120 return NULL; 121 return shmseg; 122 } 123 124 static void 125 shm_deallocate_segment(shmseg) 126 struct shmid_ds *shmseg; 127 { 128 struct shm_handle *shm_handle; 129 size_t size; 130 131 shm_handle = shmseg->shm_internal; 132 size = (shmseg->shm_segsz + CLOFSET) & ~CLOFSET; 133 vm_object_deallocate(shm_handle->shm_object); 134 free((caddr_t)shm_handle, M_SHM); 135 shmseg->shm_internal = NULL; 136 shm_committed -= btoc(size); 137 shmseg->shm_perm.mode = SHMSEG_FREE; 138 shm_nused--; 139 } 140 141 static int 142 shm_delete_mapping(p, shmmap_s) 143 struct proc *p; 144 struct shmmap_state *shmmap_s; 145 { 146 struct shmid_ds *shmseg; 147 int segnum, result; 148 size_t size; 149 150 segnum = IPCID_TO_IX(shmmap_s->shmid); 151 shmseg = &shmsegs[segnum]; 152 size = (shmseg->shm_segsz + CLOFSET) & ~CLOFSET; 153 result = vm_map_remove(&p->p_vmspace->vm_map, 154 shmmap_s->va, shmmap_s->va + size); 155 if (result != KERN_SUCCESS) 156 return EINVAL; 157 shmmap_s->shmid = -1; 158 shmseg->shm_dtime = time.tv_sec; 159 if ((--shmseg->shm_nattch <= 0) && 160 (shmseg->shm_perm.mode & SHMSEG_REMOVED)) { 161 shm_deallocate_segment(shmseg); 162 shm_last_free = segnum; 163 } 164 return 0; 165 } 166 167 int 168 sys_shmdt(p, v, retval) 169 struct proc *p; 170 void *v; 171 register_t *retval; 172 { 173 struct sys_shmdt_args /* { 174 syscallarg(void *) shmaddr; 175 } */ *uap = v; 176 struct shmmap_state *shmmap_s; 177 int i; 178 179 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm; 180 if (shmmap_s == NULL) 181 return EINVAL; 182 183 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) 184 if (shmmap_s->shmid != -1 && 185 shmmap_s->va == (vm_offset_t)SCARG(uap, shmaddr)) 186 break; 187 if (i == shminfo.shmseg) 188 return EINVAL; 189 return shm_delete_mapping(p, shmmap_s); 190 } 191 192 int 193 sys_shmat(p, v, retval) 194 struct proc *p; 195 void *v; 196 register_t *retval; 197 { 198 struct sys_shmat_args /* { 199 syscallarg(int) shmid; 200 syscallarg(void *) shmaddr; 201 syscallarg(int) shmflg; 202 } */ *uap = v; 203 int error, i, flags; 204 struct ucred *cred = p->p_ucred; 205 struct shmid_ds *shmseg; 206 struct shmmap_state *shmmap_s = NULL; 207 struct shm_handle *shm_handle; 208 vm_offset_t attach_va; 209 vm_prot_t prot; 210 vm_size_t size; 211 int rv; 212 213 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm; 214 if (shmmap_s == NULL) { 215 size = shminfo.shmseg * sizeof(struct shmmap_state); 216 shmmap_s = malloc(size, M_SHM, M_WAITOK); 217 for (i = 0; i < shminfo.shmseg; i++) 218 shmmap_s[i].shmid = -1; 219 p->p_vmspace->vm_shm = (caddr_t)shmmap_s; 220 } 221 shmseg = shm_find_segment_by_shmid(SCARG(uap, shmid)); 222 if (shmseg == NULL) 223 return EINVAL; 224 error = ipcperm(cred, &shmseg->shm_perm, 225 (SCARG(uap, shmflg) & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W); 226 if (error) 227 return error; 228 for (i = 0; i < shminfo.shmseg; i++) { 229 if (shmmap_s->shmid == -1) 230 break; 231 shmmap_s++; 232 } 233 if (i >= shminfo.shmseg) 234 return EMFILE; 235 size = (shmseg->shm_segsz + CLOFSET) & ~CLOFSET; 236 prot = VM_PROT_READ; 237 if ((SCARG(uap, shmflg) & SHM_RDONLY) == 0) 238 prot |= VM_PROT_WRITE; 239 flags = MAP_ANON | MAP_SHARED; 240 if (SCARG(uap, shmaddr)) { 241 flags |= MAP_FIXED; 242 if (SCARG(uap, shmflg) & SHM_RND) 243 attach_va = 244 (vm_offset_t)SCARG(uap, shmaddr) & ~(SHMLBA-1); 245 else if (((vm_offset_t)SCARG(uap, shmaddr) & (SHMLBA-1)) == 0) 246 attach_va = (vm_offset_t)SCARG(uap, shmaddr); 247 else 248 return EINVAL; 249 } else { 250 /* This is just a hint to vm_mmap() about where to put it. */ 251 attach_va = 252 round_page(p->p_vmspace->vm_taddr + MAXTSIZ + MAXDSIZ); 253 } 254 shm_handle = shmseg->shm_internal; 255 vm_object_reference(shm_handle->shm_object); 256 rv = vm_map_find(&p->p_vmspace->vm_map, shm_handle->shm_object, 257 0, &attach_va, size, (flags & MAP_FIXED)?0:1); 258 if (rv != KERN_SUCCESS) { 259 return ENOMEM; 260 } 261 vm_map_protect(&p->p_vmspace->vm_map, attach_va, attach_va + size, 262 prot, 0); 263 vm_map_inherit(&p->p_vmspace->vm_map, 264 attach_va, attach_va + size, VM_INHERIT_SHARE); 265 266 shmmap_s->va = attach_va; 267 shmmap_s->shmid = SCARG(uap, shmid); 268 shmseg->shm_lpid = p->p_pid; 269 shmseg->shm_atime = time.tv_sec; 270 shmseg->shm_nattch++; 271 *retval = attach_va; 272 return 0; 273 } 274 275 int 276 sys_shmctl(p, v, retval) 277 struct proc *p; 278 void *v; 279 register_t *retval; 280 { 281 struct sys_shmctl_args /* { 282 syscallarg(int) shmid; 283 syscallarg(int) cmd; 284 syscallarg(struct shmid_ds *) buf; 285 } */ *uap = v; 286 int error; 287 struct ucred *cred = p->p_ucred; 288 struct shmid_ds inbuf; 289 struct shmid_ds *shmseg; 290 291 shmseg = shm_find_segment_by_shmid(SCARG(uap, shmid)); 292 if (shmseg == NULL) 293 return EINVAL; 294 switch (SCARG(uap, cmd)) { 295 case IPC_STAT: 296 if ((error = ipcperm(cred, &shmseg->shm_perm, IPC_R)) != 0) 297 return error; 298 error = copyout((caddr_t)shmseg, SCARG(uap, buf), 299 sizeof(inbuf)); 300 if (error) 301 return error; 302 break; 303 case IPC_SET: 304 if ((error = ipcperm(cred, &shmseg->shm_perm, IPC_M)) != 0) 305 return error; 306 error = copyin(SCARG(uap, buf), (caddr_t)&inbuf, 307 sizeof(inbuf)); 308 if (error) 309 return error; 310 shmseg->shm_perm.uid = inbuf.shm_perm.uid; 311 shmseg->shm_perm.gid = inbuf.shm_perm.gid; 312 shmseg->shm_perm.mode = 313 (shmseg->shm_perm.mode & ~ACCESSPERMS) | 314 (inbuf.shm_perm.mode & ACCESSPERMS); 315 shmseg->shm_ctime = time.tv_sec; 316 break; 317 case IPC_RMID: 318 if ((error = ipcperm(cred, &shmseg->shm_perm, IPC_M)) != 0) 319 return error; 320 shmseg->shm_perm.key = IPC_PRIVATE; 321 shmseg->shm_perm.mode |= SHMSEG_REMOVED; 322 if (shmseg->shm_nattch <= 0) { 323 shm_deallocate_segment(shmseg); 324 shm_last_free = IPCID_TO_IX(SCARG(uap, shmid)); 325 } 326 break; 327 case SHM_LOCK: 328 case SHM_UNLOCK: 329 default: 330 return EINVAL; 331 } 332 return 0; 333 } 334 335 static int 336 shmget_existing(p, uap, mode, segnum, retval) 337 struct proc *p; 338 struct sys_shmget_args /* { 339 syscallarg(key_t) key; 340 syscallarg(int) size; 341 syscallarg(int) shmflg; 342 } */ *uap; 343 int mode; 344 int segnum; 345 register_t *retval; 346 { 347 struct shmid_ds *shmseg; 348 struct ucred *cred = p->p_ucred; 349 int error; 350 351 shmseg = &shmsegs[segnum]; 352 if (shmseg->shm_perm.mode & SHMSEG_REMOVED) { 353 /* 354 * This segment is in the process of being allocated. Wait 355 * until it's done, and look the key up again (in case the 356 * allocation failed or it was freed). 357 */ 358 shmseg->shm_perm.mode |= SHMSEG_WANTED; 359 error = tsleep((caddr_t)shmseg, PLOCK | PCATCH, "shmget", 0); 360 if (error) 361 return error; 362 return EAGAIN; 363 } 364 if ((error = ipcperm(cred, &shmseg->shm_perm, mode)) != 0) 365 return error; 366 if (SCARG(uap, size) && SCARG(uap, size) > shmseg->shm_segsz) 367 return EINVAL; 368 if ((SCARG(uap, shmflg) & (IPC_CREAT | IPC_EXCL)) == 369 (IPC_CREAT | IPC_EXCL)) 370 return EEXIST; 371 *retval = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm); 372 return 0; 373 } 374 375 static int 376 shmget_allocate_segment(p, uap, mode, retval) 377 struct proc *p; 378 struct sys_shmget_args /* { 379 syscallarg(key_t) key; 380 syscallarg(int) size; 381 syscallarg(int) shmflg; 382 } */ *uap; 383 int mode; 384 register_t *retval; 385 { 386 int i, segnum, shmid, size; 387 struct ucred *cred = p->p_ucred; 388 struct shmid_ds *shmseg; 389 struct shm_handle *shm_handle; 390 vm_pager_t pager; 391 int error = 0; 392 393 if (SCARG(uap, size) < shminfo.shmmin || 394 SCARG(uap, size) > shminfo.shmmax) 395 return EINVAL; 396 if (shm_nused >= shminfo.shmmni) /* any shmids left? */ 397 return ENOSPC; 398 size = (SCARG(uap, size) + CLOFSET) & ~CLOFSET; 399 if (shm_committed + btoc(size) > shminfo.shmall) 400 return ENOMEM; 401 if (shm_last_free < 0) { 402 for (i = 0; i < shminfo.shmmni; i++) 403 if (shmsegs[i].shm_perm.mode & SHMSEG_FREE) 404 break; 405 if (i == shminfo.shmmni) 406 panic("shmseg free count inconsistent"); 407 segnum = i; 408 } else { 409 segnum = shm_last_free; 410 shm_last_free = -1; 411 } 412 shmseg = &shmsegs[segnum]; 413 /* 414 * In case we sleep in malloc(), mark the segment present but deleted 415 * so that noone else tries to create the same key. 416 */ 417 shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED; 418 shmseg->shm_perm.key = SCARG(uap, key); 419 shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff; 420 shm_handle = (struct shm_handle *) 421 malloc(sizeof(struct shm_handle), M_SHM, M_WAITOK); 422 shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm); 423 424 shm_handle->shm_object = vm_object_allocate(size); 425 if (shm_handle->shm_object == NULL) { 426 /* XXX cannot happen */ 427 error = ENOMEM; 428 goto out; 429 } 430 /* 431 * We make sure that we have allocated a pager before we need 432 * to. 433 */ 434 pager = vm_pager_allocate(PG_DFLT, 0, size, VM_PROT_DEFAULT, 0); 435 if (pager == NULL) { 436 error = ENOMEM; 437 goto out; 438 } 439 vm_object_setpager(shm_handle->shm_object, pager, 0, 0); 440 shmseg->shm_internal = shm_handle; 441 shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid; 442 shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid; 443 shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) | 444 (mode & ACCESSPERMS) | SHMSEG_ALLOCATED; 445 shmseg->shm_segsz = SCARG(uap, size); 446 shmseg->shm_cpid = p->p_pid; 447 shmseg->shm_lpid = shmseg->shm_nattch = 0; 448 shmseg->shm_atime = shmseg->shm_dtime = 0; 449 shmseg->shm_ctime = time.tv_sec; 450 shm_committed += btoc(size); 451 shm_nused++; 452 453 out: 454 if (error) { 455 if (shm_handle->shm_object != NULL) 456 vm_object_deallocate(shm_handle->shm_object); 457 free(shm_handle, M_SHM); 458 shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) 459 | SHMSEG_FREE; 460 } else 461 *retval = shmid; 462 if (shmseg->shm_perm.mode & SHMSEG_WANTED) { 463 /* 464 * Somebody else wanted this key while we were asleep. Wake 465 * them up now. 466 */ 467 shmseg->shm_perm.mode &= ~SHMSEG_WANTED; 468 wakeup((caddr_t)shmseg); 469 } 470 return error; 471 } 472 473 int 474 sys_shmget(p, v, retval) 475 struct proc *p; 476 void *v; 477 register_t *retval; 478 { 479 struct sys_shmget_args /* { 480 syscallarg(key_t) key; 481 syscallarg(int) size; 482 syscallarg(int) shmflg; 483 } */ *uap = v; 484 int segnum, mode, error; 485 486 mode = SCARG(uap, shmflg) & ACCESSPERMS; 487 if (SCARG(uap, key) != IPC_PRIVATE) { 488 again: 489 segnum = shm_find_segment_by_key(SCARG(uap, key)); 490 if (segnum >= 0) { 491 error = shmget_existing(p, uap, mode, segnum, retval); 492 if (error == EAGAIN) 493 goto again; 494 return error; 495 } 496 if ((SCARG(uap, shmflg) & IPC_CREAT) == 0) 497 return ENOENT; 498 } 499 return shmget_allocate_segment(p, uap, mode, retval); 500 } 501 502 void 503 shmfork(p1, p2) 504 struct proc *p1, *p2; 505 { 506 struct shmmap_state *shmmap_s; 507 size_t size; 508 int i; 509 510 if (p1->p_vmspace->vm_shm == NULL) { 511 p2->p_vmspace->vm_shm = NULL; 512 return; 513 } 514 515 size = shminfo.shmseg * sizeof(struct shmmap_state); 516 shmmap_s = malloc(size, M_SHM, M_WAITOK); 517 bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size); 518 p2->p_vmspace->vm_shm = (caddr_t)shmmap_s; 519 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) 520 if (shmmap_s->shmid != -1) 521 shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++; 522 } 523 524 void 525 shmexit(p) 526 struct proc *p; 527 { 528 struct shmmap_state *shmmap_s; 529 int i; 530 531 shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm; 532 if (shmmap_s == NULL) 533 return; 534 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) 535 if (shmmap_s->shmid != -1) 536 shm_delete_mapping(p, shmmap_s); 537 free((caddr_t)p->p_vmspace->vm_shm, M_SHM); 538 p->p_vmspace->vm_shm = NULL; 539 } 540 541 void 542 shminit() 543 { 544 int i; 545 546 shminfo.shmmax *= NBPG; 547 548 for (i = 0; i < shminfo.shmmni; i++) { 549 shmsegs[i].shm_perm.mode = SHMSEG_FREE; 550 shmsegs[i].shm_perm.seq = 0; 551 } 552 shm_last_free = 0; 553 shm_nused = 0; 554 shm_committed = 0; 555 } 556
Indexes created Tue Sep 23 23:09:58 GMT 2025