sys/kern/sysv_shm.c

   1 /* $FreeBSD: src/sys/kern/sysv_shm.c,v 1.45.2.6 2002/10/22 20:45:03 fjoe Exp $ */
   2 /*      $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $      */
   3
   4 /*
   5  * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by Adam Glass and Charles
  18  *      Hannum.
  19  * 4. The names of the authors may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include "opt_compat.h"
  35 #include "opt_sysvipc.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/sysproto.h>
  40 #include <sys/kernel.h>
  41 #include <sys/sysctl.h>
  42 #include <sys/shm.h>
  43 #include <sys/proc.h>
  44 #include <sys/malloc.h>
  45 #include <sys/mman.h>
  46 #include <sys/stat.h>
  47 #include <sys/sysent.h>
  48 #include <sys/jail.h>
  49
  50 #include <sys/mplock2.h>
  51
  52 #include <vm/vm.h>
  53 #include <vm/vm_param.h>
  54 #include <sys/lock.h>
  55 #include <vm/pmap.h>
  56 #include <vm/vm_object.h>
  57 #include <vm/vm_map.h>
  58 #include <vm/vm_page.h>
  59 #include <vm/vm_pager.h>
  60
  61 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
  62
  63 struct oshmctl_args;
  64 static int sys_oshmctl (struct proc *p, struct oshmctl_args *uap);
  65
  66 static int shmget_allocate_segment (struct proc *p, struct shmget_args *uap, int mode);
  67 static int shmget_existing (struct proc *p, struct shmget_args *uap, int mode, int segnum);
  68
  69 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  70 static sy_call_t *shmcalls[] = {
  71         (sy_call_t *)sys_shmat, (sy_call_t *)sys_oshmctl,
  72         (sy_call_t *)sys_shmdt, (sy_call_t *)sys_shmget,
  73         (sy_call_t *)sys_shmctl
  74 };
  75
  76 #define SHMSEG_FREE             0x0200
  77 #define SHMSEG_REMOVED          0x0400
  78 #define SHMSEG_ALLOCATED        0x0800
  79 #define SHMSEG_WANTED           0x1000
  80
  81 static int shm_last_free, shm_committed, shmalloced;
  82 int shm_nused;
  83 static struct shmid_ds  *shmsegs;
  84
  85 struct shm_handle {
  86         /* vm_offset_t kva; */
  87         vm_object_t shm_object;
  88 };
  89
  90 struct shmmap_state {
  91         vm_offset_t va;
  92         int shmid;
  93 };
  94
  95 static void shm_deallocate_segment (struct shmid_ds *);
  96 static int shm_find_segment_by_key (key_t);
  97 static struct shmid_ds *shm_find_segment_by_shmid (int);
  98 static int shm_delete_mapping (struct vmspace *vm, struct shmmap_state *);
  99 static void shmrealloc (void);
 100 static void shminit (void *);
 101
 102 /*
 103  * Tuneable values
 104  */
 105 #ifndef SHMMAXPGS
 106 #define SHMMAXPGS       8192    /* note: sysv shared memory is swap backed */
 107 #endif
 108 #ifndef SHMMAX
 109 #define SHMMAX  (SHMMAXPGS*PAGE_SIZE)
 110 #endif
 111 #ifndef SHMMIN
 112 #define SHMMIN  1
 113 #endif
 114 #ifndef SHMMNI
 115 #define SHMMNI  192
 116 #endif
 117 #ifndef SHMSEG
 118 #define SHMSEG  128
 119 #endif
 120 #ifndef SHMALL
 121 #define SHMALL  (SHMMAXPGS)
 122 #endif
 123
 124 struct  shminfo shminfo = {
 125         SHMMAX,
 126         SHMMIN,
 127         SHMMNI,
 128         SHMSEG,
 129         SHMALL
 130 };
 131
 132 static int shm_use_phys;
 133
 134 TUNABLE_INT("kern.ipc.shmmin", &shminfo.shmmin);
 135 TUNABLE_INT("kern.ipc.shmmni", &shminfo.shmmni);
 136 TUNABLE_INT("kern.ipc.shmseg", &shminfo.shmseg);
 137 TUNABLE_INT("kern.ipc.shmmaxpgs", &shminfo.shmall);
 138 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys);
 139
 140 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0,
 141     "Max shared memory segment size");
 142 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0,
 143     "Min shared memory segment size");
 144 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0,
 145     "Max number of shared memory identifiers");
 146 SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0,
 147     "Max shared memory segments per process");
 148 SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0,
 149     "Max pages of shared memory");
 150 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0,
 151     "Use phys pager allocation instead of swap pager allocation");
 152
 153 static int
 154 shm_find_segment_by_key(key_t key)
 155 {
 156         int i;
 157
 158         for (i = 0; i < shmalloced; i++)
 159                 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
 160                     shmsegs[i].shm_perm.key == key)
 161                         return i;
 162         return -1;
 163 }
 164
 165 static struct shmid_ds *
 166 shm_find_segment_by_shmid(int shmid)
 167 {
 168         int segnum;
 169         struct shmid_ds *shmseg;
 170
 171         segnum = IPCID_TO_IX(shmid);
 172         if (segnum < 0 || segnum >= shmalloced)
 173                 return NULL;
 174         shmseg = &shmsegs[segnum];
 175         if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
 176             != SHMSEG_ALLOCATED ||
 177             shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
 178                 return NULL;
 179         return shmseg;
 180 }
 181
 182 static void
 183 shm_deallocate_segment(struct shmid_ds *shmseg)
 184 {
 185         struct shm_handle *shm_handle;
 186         size_t size;
 187
 188         shm_handle = shmseg->shm_internal;
 189         vm_object_deallocate(shm_handle->shm_object);
 190         kfree((caddr_t)shm_handle, M_SHM);
 191         shmseg->shm_internal = NULL;
 192         size = round_page(shmseg->shm_segsz);
 193         shm_committed -= btoc(size);
 194         shm_nused--;
 195         shmseg->shm_perm.mode = SHMSEG_FREE;
 196 }
 197
 198 static int
 199 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
 200 {
 201         struct shmid_ds *shmseg;
 202         int segnum, result;
 203         size_t size;
 204
 205         segnum = IPCID_TO_IX(shmmap_s->shmid);
 206         shmseg = &shmsegs[segnum];
 207         size = round_page(shmseg->shm_segsz);
 208         result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
 209         if (result != KERN_SUCCESS)
 210                 return EINVAL;
 211         shmmap_s->shmid = -1;
 212         shmseg->shm_dtime = time_second;
 213         if ((--shmseg->shm_nattch <= 0) &&
 214             (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
 215                 shm_deallocate_segment(shmseg);
 216                 shm_last_free = segnum;
 217         }
 218         return 0;
 219 }
 220
 221 /*
 222  * MPALMOSTSAFE
 223  */
 224 int
 225 sys_shmdt(struct shmdt_args *uap)
 226 {
 227         struct thread *td = curthread;
 228         struct proc *p = td->td_proc;
 229         struct shmmap_state *shmmap_s;
 230         int i;
 231         int error;
 232
 233         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 234                 return (ENOSYS);
 235
 236         get_mplock();
 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         rel_mplock();
 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         int error, i, flags;
 265         struct shmid_ds *shmseg;
 266         struct shmmap_state *shmmap_s = NULL;
 267         struct shm_handle *shm_handle;
 268         vm_offset_t attach_va;
 269         vm_prot_t prot;
 270         vm_size_t size;
 271         int rv;
 272
 273         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 274                 return (ENOSYS);
 275
 276         get_mplock();
 277 again:
 278         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 279         if (shmmap_s == NULL) {
 280                 size = shminfo.shmseg * sizeof(struct shmmap_state);
 281                 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 282                 for (i = 0; i < shminfo.shmseg; i++)
 283                         shmmap_s[i].shmid = -1;
 284                 if (p->p_vmspace->vm_shm != NULL) {
 285                         kfree(shmmap_s, M_SHM);
 286                         goto again;
 287                 }
 288                 p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 289         }
 290         shmseg = shm_find_segment_by_shmid(uap->shmid);
 291         if (shmseg == NULL) {
 292                 error = EINVAL;
 293                 goto done;
 294         }
 295         error = ipcperm(p, &shmseg->shm_perm,
 296                         (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
 297         if (error)
 298                 goto done;
 299         for (i = 0; i < shminfo.shmseg; i++) {
 300                 if (shmmap_s->shmid == -1)
 301                         break;
 302                 shmmap_s++;
 303         }
 304         if (i >= shminfo.shmseg) {
 305                 error = EMFILE;
 306                 goto done;
 307         }
 308         size = round_page(shmseg->shm_segsz);
 309 #ifdef VM_PROT_READ_IS_EXEC
 310         prot = VM_PROT_READ | VM_PROT_EXECUTE;
 311 #else
 312         prot = VM_PROT_READ;
 313 #endif
 314         if ((uap->shmflg & SHM_RDONLY) == 0)
 315                 prot |= VM_PROT_WRITE;
 316         flags = MAP_ANON | MAP_SHARED;
 317         if (uap->shmaddr) {
 318                 flags |= MAP_FIXED;
 319                 if (uap->shmflg & SHM_RND) {
 320                         attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
 321                 } else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) {
 322                         attach_va = (vm_offset_t)uap->shmaddr;
 323                 } else {
 324                         error = EINVAL;
 325                         goto done;
 326                 }
 327         } else {
 328                 /*
 329                  * This is just a hint to vm_map_find() about where to put it.
 330                  */
 331                 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + maxtsiz + maxdsiz);
 332         }
 333
 334         shm_handle = shmseg->shm_internal;
 335         vm_object_reference(shm_handle->shm_object);
 336         rv = vm_map_find(&p->p_vmspace->vm_map,
 337                          shm_handle->shm_object, 0,
 338                          &attach_va,
 339                          size, PAGE_SIZE,
 340                          ((flags & MAP_FIXED) ? 0 : 1),
 341                          VM_MAPTYPE_NORMAL,
 342                          prot, prot,
 343                          0);
 344         if (rv != KERN_SUCCESS) {
 345                 vm_object_deallocate(shm_handle->shm_object);
 346                 error = ENOMEM;
 347                 goto done;
 348         }
 349         vm_map_inherit(&p->p_vmspace->vm_map,
 350                        attach_va, attach_va + size, VM_INHERIT_SHARE);
 351
 352         KKASSERT(shmmap_s->shmid == -1);
 353         shmmap_s->va = attach_va;
 354         shmmap_s->shmid = uap->shmid;
 355         shmseg->shm_lpid = p->p_pid;
 356         shmseg->shm_atime = time_second;
 357         shmseg->shm_nattch++;
 358         uap->sysmsg_resultp = (void *)attach_va;
 359         error = 0;
 360 done:
 361         rel_mplock();
 362         return error;
 363 }
 364
 365 struct oshmid_ds {
 366         struct  ipc_perm shm_perm;      /* operation perms */
 367         int     shm_segsz;              /* size of segment (bytes) */
 368         ushort  shm_cpid;               /* pid, creator */
 369         ushort  shm_lpid;               /* pid, last operation */
 370         short   shm_nattch;             /* no. of current attaches */
 371         time_t  shm_atime;              /* last attach time */
 372         time_t  shm_dtime;              /* last detach time */
 373         time_t  shm_ctime;              /* last change time */
 374         void    *shm_handle;            /* internal handle for shm segment */
 375 };
 376
 377 struct oshmctl_args {
 378         struct sysmsg sysmsg;
 379         int shmid;
 380         int cmd;
 381         struct oshmid_ds *ubuf;
 382 };
 383
 384 /*
 385  * MPALMOSTSAFE
 386  */
 387 static int
 388 sys_oshmctl(struct proc *p, struct oshmctl_args *uap)
 389 {
 390 #ifdef COMPAT_43
 391         struct thread *td = curthread;
 392         struct shmid_ds *shmseg;
 393         struct oshmid_ds outbuf;
 394         int error;
 395
 396         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 397                 return (ENOSYS);
 398
 399         get_mplock();
 400         shmseg = shm_find_segment_by_shmid(uap->shmid);
 401         if (shmseg == NULL) {
 402                 error = EINVAL;
 403                 goto done;
 404         }
 405
 406         switch (uap->cmd) {
 407         case IPC_STAT:
 408                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 409                 if (error)
 410                         break;
 411                 outbuf.shm_perm = shmseg->shm_perm;
 412                 outbuf.shm_segsz = shmseg->shm_segsz;
 413                 outbuf.shm_cpid = shmseg->shm_cpid;
 414                 outbuf.shm_lpid = shmseg->shm_lpid;
 415                 outbuf.shm_nattch = shmseg->shm_nattch;
 416                 outbuf.shm_atime = shmseg->shm_atime;
 417                 outbuf.shm_dtime = shmseg->shm_dtime;
 418                 outbuf.shm_ctime = shmseg->shm_ctime;
 419                 outbuf.shm_handle = shmseg->shm_internal;
 420                 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
 421                 break;
 422         default:
 423                 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 424                 error = sys_shmctl((struct shmctl_args *)uap);
 425         }
 426 done:
 427         rel_mplock();
 428         return error;
 429 #else
 430         return EINVAL;
 431 #endif
 432 }
 433
 434 /*
 435  * MPALMOSTSAFE
 436  */
 437 int
 438 sys_shmctl(struct shmctl_args *uap)
 439 {
 440         struct thread *td = curthread;
 441         struct proc *p = td->td_proc;
 442         int error;
 443         struct shmid_ds inbuf;
 444         struct shmid_ds *shmseg;
 445
 446         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 447                 return (ENOSYS);
 448
 449         get_mplock();
 450         shmseg = shm_find_segment_by_shmid(uap->shmid);
 451         if (shmseg == NULL) {
 452                 error = EINVAL;
 453                 goto done;
 454         }
 455
 456         switch (uap->cmd) {
 457         case IPC_STAT:
 458                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 459                 if (error == 0)
 460                         error = copyout(shmseg, uap->buf, sizeof(inbuf));
 461                 break;
 462         case IPC_SET:
 463                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 464                 if (error == 0)
 465                         error = copyin(uap->buf, &inbuf, sizeof(inbuf));
 466                 if (error == 0) {
 467                         shmseg->shm_perm.uid = inbuf.shm_perm.uid;
 468                         shmseg->shm_perm.gid = inbuf.shm_perm.gid;
 469                         shmseg->shm_perm.mode =
 470                             (shmseg->shm_perm.mode & ~ACCESSPERMS) |
 471                             (inbuf.shm_perm.mode & ACCESSPERMS);
 472                         shmseg->shm_ctime = time_second;
 473                 }
 474                 break;
 475         case IPC_RMID:
 476                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 477                 if (error == 0) {
 478                         shmseg->shm_perm.key = IPC_PRIVATE;
 479                         shmseg->shm_perm.mode |= SHMSEG_REMOVED;
 480                         if (shmseg->shm_nattch <= 0) {
 481                                 shm_deallocate_segment(shmseg);
 482                                 shm_last_free = IPCID_TO_IX(uap->shmid);
 483                         }
 484                 }
 485                 break;
 486 #if 0
 487         case SHM_LOCK:
 488         case SHM_UNLOCK:
 489 #endif
 490         default:
 491                 error = EINVAL;
 492                 break;
 493         }
 494 done:
 495         rel_mplock();
 496         return error;
 497 }
 498
 499 static int
 500 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum)
 501 {
 502         struct shmid_ds *shmseg;
 503         int error;
 504
 505         shmseg = &shmsegs[segnum];
 506         if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
 507                 /*
 508                  * This segment is in the process of being allocated.  Wait
 509                  * until it's done, and look the key up again (in case the
 510                  * allocation failed or it was freed).
 511                  */
 512                 shmseg->shm_perm.mode |= SHMSEG_WANTED;
 513                 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
 514                 if (error)
 515                         return error;
 516                 return EAGAIN;
 517         }
 518         if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
 519                 return EEXIST;
 520         error = ipcperm(p, &shmseg->shm_perm, mode);
 521         if (error)
 522                 return error;
 523         if (uap->size && uap->size > shmseg->shm_segsz)
 524                 return EINVAL;
 525         uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 526         return 0;
 527 }
 528
 529 static int
 530 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode)
 531 {
 532         int i, segnum, shmid, size;
 533         struct ucred *cred = p->p_ucred;
 534         struct shmid_ds *shmseg;
 535         struct shm_handle *shm_handle;
 536
 537         if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
 538                 return EINVAL;
 539         if (shm_nused >= shminfo.shmmni) /* any shmids left? */
 540                 return ENOSPC;
 541         size = round_page(uap->size);
 542         if (shm_committed + btoc(size) > shminfo.shmall)
 543                 return ENOMEM;
 544         if (shm_last_free < 0) {
 545                 shmrealloc();   /* maybe expand the shmsegs[] array */
 546                 for (i = 0; i < shmalloced; i++)
 547                         if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
 548                                 break;
 549                 if (i == shmalloced)
 550                         return ENOSPC;
 551                 segnum = i;
 552         } else  {
 553                 segnum = shm_last_free;
 554                 shm_last_free = -1;
 555         }
 556         shmseg = &shmsegs[segnum];
 557         /*
 558          * In case we sleep in malloc(), mark the segment present but deleted
 559          * so that noone else tries to create the same key.
 560          */
 561         shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
 562         shmseg->shm_perm.key = uap->key;
 563         shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
 564         shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
 565         shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 566
 567         /*
 568          * We make sure that we have allocated a pager before we need
 569          * to.
 570          */
 571         if (shm_use_phys) {
 572                 shm_handle->shm_object =
 573                    phys_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 574         } else {
 575                 shm_handle->shm_object =
 576                    swap_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 577         }
 578         vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
 579         vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
 580
 581         shmseg->shm_internal = shm_handle;
 582         shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
 583         shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
 584         shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
 585             (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
 586         shmseg->shm_segsz = uap->size;
 587         shmseg->shm_cpid = p->p_pid;
 588         shmseg->shm_lpid = shmseg->shm_nattch = 0;
 589         shmseg->shm_atime = shmseg->shm_dtime = 0;
 590         shmseg->shm_ctime = time_second;
 591         shm_committed += btoc(size);
 592         shm_nused++;
 593         if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
 594                 /*
 595                  * Somebody else wanted this key while we were asleep.  Wake
 596                  * them up now.
 597                  */
 598                 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
 599                 wakeup((caddr_t)shmseg);
 600         }
 601         uap->sysmsg_result = shmid;
 602         return 0;
 603 }
 604
 605 /*
 606  * MPALMOSTSAFE
 607  */
 608 int
 609 sys_shmget(struct shmget_args *uap)
 610 {
 611         struct thread *td = curthread;
 612         struct proc *p = td->td_proc;
 613         int segnum, mode, error;
 614
 615         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 616                 return (ENOSYS);
 617
 618         mode = uap->shmflg & ACCESSPERMS;
 619         get_mplock();
 620
 621         if (uap->key != IPC_PRIVATE) {
 622         again:
 623                 segnum = shm_find_segment_by_key(uap->key);
 624                 if (segnum >= 0) {
 625                         error = shmget_existing(p, uap, mode, segnum);
 626                         if (error == EAGAIN)
 627                                 goto again;
 628                         goto done;
 629                 }
 630                 if ((uap->shmflg & IPC_CREAT) == 0) {
 631                         error = ENOENT;
 632                         goto done;
 633                 }
 634         }
 635         error = shmget_allocate_segment(p, uap, mode);
 636 done:
 637         rel_mplock();
 638         return (error);
 639 }
 640
 641 /*
 642  * shmsys_args(int which, int a2, ...) (VARARGS)
 643  *
 644  * MPALMOSTSAFE
 645  */
 646 int
 647 sys_shmsys(struct shmsys_args *uap)
 648 {
 649         struct thread *td = curthread;
 650         unsigned int which = (unsigned int)uap->which;
 651         int error;
 652
 653         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 654                 return (ENOSYS);
 655
 656         if (which >= NELEM(shmcalls))
 657                 return EINVAL;
 658         get_mplock();
 659         bcopy(&uap->a2, &uap->which,
 660                 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2));
 661         error = ((*shmcalls[which])(uap));
 662         rel_mplock();
 663
 664         return(error);
 665 }
 666
 667 void
 668 shmfork(struct proc *p1, struct proc *p2)
 669 {
 670         struct shmmap_state *shmmap_s;
 671         size_t size;
 672         int i;
 673
 674         size = shminfo.shmseg * sizeof(struct shmmap_state);
 675         shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 676         bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
 677         p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 678         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
 679                 if (shmmap_s->shmid != -1)
 680                         shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
 681 }
 682
 683 void
 684 shmexit(struct vmspace *vm)
 685 {
 686         struct shmmap_state *base, *shm;
 687         int i;
 688
 689         if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
 690                 vm->vm_shm = NULL;
 691                 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
 692                         if (shm->shmid != -1)
 693                                 shm_delete_mapping(vm, shm);
 694                 }
 695                 kfree(base, M_SHM);
 696         }
 697 }
 698
 699 static void
 700 shmrealloc(void)
 701 {
 702         int i;
 703         struct shmid_ds *newsegs;
 704
 705         if (shmalloced >= shminfo.shmmni)
 706                 return;
 707
 708         newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
 709         for (i = 0; i < shmalloced; i++)
 710                 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
 711         for (; i < shminfo.shmmni; i++) {
 712                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 713                 shmsegs[i].shm_perm.seq = 0;
 714         }
 715         kfree(shmsegs, M_SHM);
 716         shmsegs = newsegs;
 717         shmalloced = shminfo.shmmni;
 718 }
 719
 720 static void
 721 shminit(void *dummy)
 722 {
 723         int i;
 724
 725         shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
 726         shmalloced = shminfo.shmmni;
 727         shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
 728         for (i = 0; i < shmalloced; i++) {
 729                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 730                 shmsegs[i].shm_perm.seq = 0;
 731         }
 732         shm_last_free = 0;
 733         shm_nused = 0;
 734         shm_committed = 0;
 735 }
 736 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);