sys/kern/sysv_shm.c

   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_compat.h"
  32 #include "opt_sysvipc.h"
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/sysproto.h>
  37 #include <sys/kernel.h>
  38 #include <sys/sysctl.h>
  39 #include <sys/shm.h>
  40 #include <sys/proc.h>
  41 #include <sys/malloc.h>
  42 #include <sys/mman.h>
  43 #include <sys/stat.h>
  44 #include <sys/sysent.h>
  45 #include <sys/jail.h>
  46
  47 #include <sys/mplock2.h>
  48
  49 #include <vm/vm.h>
  50 #include <vm/vm_param.h>
  51 #include <sys/lock.h>
  52 #include <vm/pmap.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_map.h>
  55 #include <vm/vm_page.h>
  56 #include <vm/vm_pager.h>
  57
  58 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
  59
  60 struct oshmctl_args;
  61 static int sys_oshmctl (struct proc *p, struct oshmctl_args *uap);
  62
  63 static int shmget_allocate_segment (struct proc *p, struct shmget_args *uap, int mode);
  64 static int shmget_existing (struct proc *p, struct shmget_args *uap, int mode, int segnum);
  65
  66 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  67 static sy_call_t *shmcalls[] = {
  68         (sy_call_t *)sys_shmat, (sy_call_t *)sys_oshmctl,
  69         (sy_call_t *)sys_shmdt, (sy_call_t *)sys_shmget,
  70         (sy_call_t *)sys_shmctl
  71 };
  72
  73 #define SHMSEG_FREE             0x0200
  74 #define SHMSEG_REMOVED          0x0400
  75 #define SHMSEG_ALLOCATED        0x0800
  76 #define SHMSEG_WANTED           0x1000
  77
  78 static int shm_last_free, shm_committed, shmalloced;
  79 int shm_nused;
  80 static struct shmid_ds  *shmsegs;
  81
  82 struct shm_handle {
  83         /* vm_offset_t kva; */
  84         vm_object_t shm_object;
  85 };
  86
  87 struct shmmap_state {
  88         vm_offset_t va;
  89         int shmid;
  90 };
  91
  92 static void shm_deallocate_segment (struct shmid_ds *);
  93 static int shm_find_segment_by_key (key_t);
  94 static struct shmid_ds *shm_find_segment_by_shmid (int);
  95 static int shm_delete_mapping (struct vmspace *vm, struct shmmap_state *);
  96 static void shmrealloc (void);
  97 static void shminit (void *);
  98
  99 /*
 100  * Tuneable values
 101  */
 102 #ifndef SHMMIN
 103 #define SHMMIN  1
 104 #endif
 105 #ifndef SHMMNI
 106 #define SHMMNI  512
 107 #endif
 108 #ifndef SHMSEG
 109 #define SHMSEG  1024
 110 #endif
 111
 112 struct  shminfo shminfo = {
 113         0,
 114         SHMMIN,
 115         SHMMNI,
 116         SHMSEG,
 117         0
 118 };
 119
 120 static int shm_use_phys = 1;
 121
 122 TUNABLE_LONG("kern.ipc.shmmin", &shminfo.shmmin);
 123 TUNABLE_LONG("kern.ipc.shmmni", &shminfo.shmmni);
 124 TUNABLE_LONG("kern.ipc.shmseg", &shminfo.shmseg);
 125 TUNABLE_LONG("kern.ipc.shmmaxpgs", &shminfo.shmall);
 126 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys);
 127
 128 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0,
 129     "Max shared memory segment size");
 130 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0,
 131     "Min shared memory segment size");
 132 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0,
 133     "Max number of shared memory identifiers");
 134 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0,
 135     "Max shared memory segments per process");
 136 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0,
 137     "Max pages of shared memory");
 138 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0,
 139     "Use phys pager allocation instead of swap pager allocation");
 140
 141 static int
 142 shm_find_segment_by_key(key_t key)
 143 {
 144         int i;
 145
 146         for (i = 0; i < shmalloced; i++) {
 147                 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
 148                     shmsegs[i].shm_perm.key == key)
 149                         return i;
 150         }
 151         return -1;
 152 }
 153
 154 static struct shmid_ds *
 155 shm_find_segment_by_shmid(int shmid)
 156 {
 157         int segnum;
 158         struct shmid_ds *shmseg;
 159
 160         segnum = IPCID_TO_IX(shmid);
 161         if (segnum < 0 || segnum >= shmalloced)
 162                 return NULL;
 163         shmseg = &shmsegs[segnum];
 164         if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
 165             != SHMSEG_ALLOCATED ||
 166             shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid)) {
 167                 return NULL;
 168         }
 169         return shmseg;
 170 }
 171
 172 static void
 173 shm_deallocate_segment(struct shmid_ds *shmseg)
 174 {
 175         struct shm_handle *shm_handle;
 176         size_t size;
 177
 178         shm_handle = shmseg->shm_internal;
 179         vm_object_deallocate(shm_handle->shm_object);
 180         kfree((caddr_t)shm_handle, M_SHM);
 181         shmseg->shm_internal = NULL;
 182         size = round_page(shmseg->shm_segsz);
 183         shm_committed -= btoc(size);
 184         shm_nused--;
 185         shmseg->shm_perm.mode = SHMSEG_FREE;
 186 }
 187
 188 static int
 189 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
 190 {
 191         struct shmid_ds *shmseg;
 192         int segnum, result;
 193         size_t size;
 194
 195         segnum = IPCID_TO_IX(shmmap_s->shmid);
 196         shmseg = &shmsegs[segnum];
 197         size = round_page(shmseg->shm_segsz);
 198         result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
 199         if (result != KERN_SUCCESS)
 200                 return EINVAL;
 201         shmmap_s->shmid = -1;
 202         shmseg->shm_dtime = time_second;
 203         if ((--shmseg->shm_nattch <= 0) &&
 204             (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
 205                 shm_deallocate_segment(shmseg);
 206                 shm_last_free = segnum;
 207         }
 208         return 0;
 209 }
 210
 211 /*
 212  * MPALMOSTSAFE
 213  */
 214 int
 215 sys_shmdt(struct shmdt_args *uap)
 216 {
 217         struct thread *td = curthread;
 218         struct proc *p = td->td_proc;
 219         struct shmmap_state *shmmap_s;
 220         long i;
 221         int error;
 222
 223         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 224                 return (ENOSYS);
 225
 226         get_mplock();
 227         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 228         if (shmmap_s == NULL) {
 229                 error = EINVAL;
 230                 goto done;
 231         }
 232         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
 233                 if (shmmap_s->shmid != -1 &&
 234                     shmmap_s->va == (vm_offset_t)uap->shmaddr)
 235                         break;
 236         }
 237         if (i == shminfo.shmseg)
 238                 error = EINVAL;
 239         else
 240                 error = shm_delete_mapping(p->p_vmspace, shmmap_s);
 241 done:
 242         rel_mplock();
 243         return (error);
 244 }
 245
 246 /*
 247  * MPALMOSTSAFE
 248  */
 249 int
 250 sys_shmat(struct shmat_args *uap)
 251 {
 252         struct thread *td = curthread;
 253         struct proc *p = td->td_proc;
 254         int error, flags;
 255         long i;
 256         struct shmid_ds *shmseg;
 257         struct shmmap_state *shmmap_s = NULL;
 258         struct shm_handle *shm_handle;
 259         vm_offset_t attach_va;
 260         vm_prot_t prot;
 261         vm_size_t size;
 262         vm_size_t align;
 263         int rv;
 264
 265         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 266                 return (ENOSYS);
 267
 268         get_mplock();
 269 again:
 270         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 271         if (shmmap_s == NULL) {
 272                 size = shminfo.shmseg * sizeof(struct shmmap_state);
 273                 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 274                 for (i = 0; i < shminfo.shmseg; i++)
 275                         shmmap_s[i].shmid = -1;
 276                 if (p->p_vmspace->vm_shm != NULL) {
 277                         kfree(shmmap_s, M_SHM);
 278                         goto again;
 279                 }
 280                 p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 281         }
 282         shmseg = shm_find_segment_by_shmid(uap->shmid);
 283         if (shmseg == NULL) {
 284                 error = EINVAL;
 285                 goto done;
 286         }
 287         error = ipcperm(p, &shmseg->shm_perm,
 288                         (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
 289         if (error)
 290                 goto done;
 291         for (i = 0; i < shminfo.shmseg; i++) {
 292                 if (shmmap_s->shmid == -1)
 293                         break;
 294                 shmmap_s++;
 295         }
 296         if (i >= shminfo.shmseg) {
 297                 error = EMFILE;
 298                 goto done;
 299         }
 300         size = round_page(shmseg->shm_segsz);
 301 #ifdef VM_PROT_READ_IS_EXEC
 302         prot = VM_PROT_READ | VM_PROT_EXECUTE;
 303 #else
 304         prot = VM_PROT_READ;
 305 #endif
 306         if ((uap->shmflg & SHM_RDONLY) == 0)
 307                 prot |= VM_PROT_WRITE;
 308         flags = MAP_ANON | MAP_SHARED;
 309         if (uap->shmaddr) {
 310                 flags |= MAP_FIXED;
 311                 if (uap->shmflg & SHM_RND) {
 312                         attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
 313                 } else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) {
 314                         attach_va = (vm_offset_t)uap->shmaddr;
 315                 } else {
 316                         error = EINVAL;
 317                         goto done;
 318                 }
 319         } else {
 320                 /*
 321                  * This is just a hint to vm_map_find() about where to put it.
 322                  */
 323                 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr +
 324                                        maxtsiz + maxdsiz);
 325         }
 326
 327         /*
 328          * Handle alignment.  For large memory maps it is possible
 329          * that the MMU can optimize the page table so align anything
 330          * that is a multiple of SEG_SIZE to SEG_SIZE.
 331          */
 332         if ((flags & MAP_FIXED) == 0 && (size & SEG_MASK) == 0)
 333                 align = SEG_SIZE;
 334         else
 335                 align = PAGE_SIZE;
 336
 337         shm_handle = shmseg->shm_internal;
 338         vm_object_hold(shm_handle->shm_object);
 339         vm_object_chain_wait(shm_handle->shm_object, 0);
 340         vm_object_reference_locked(shm_handle->shm_object);
 341         rv = vm_map_find(&p->p_vmspace->vm_map,
 342                          shm_handle->shm_object, 0,
 343                          &attach_va,
 344                          size, align,
 345                          ((flags & MAP_FIXED) ? 0 : 1),
 346                          VM_MAPTYPE_NORMAL,
 347                          prot, prot,
 348                          0);
 349         vm_object_drop(shm_handle->shm_object);
 350         if (rv != KERN_SUCCESS) {
 351                 vm_object_deallocate(shm_handle->shm_object);
 352                 error = ENOMEM;
 353                 goto done;
 354         }
 355         vm_map_inherit(&p->p_vmspace->vm_map,
 356                        attach_va, attach_va + size, VM_INHERIT_SHARE);
 357
 358         KKASSERT(shmmap_s->shmid == -1);
 359         shmmap_s->va = attach_va;
 360         shmmap_s->shmid = uap->shmid;
 361         shmseg->shm_lpid = p->p_pid;
 362         shmseg->shm_atime = time_second;
 363         shmseg->shm_nattch++;
 364         uap->sysmsg_resultp = (void *)attach_va;
 365         error = 0;
 366 done:
 367         rel_mplock();
 368         return error;
 369 }
 370
 371 struct oshmid_ds {
 372         struct  ipc_perm shm_perm;      /* operation perms */
 373         int     shm_segsz;              /* size of segment (bytes) */
 374         ushort  shm_cpid;               /* pid, creator */
 375         ushort  shm_lpid;               /* pid, last operation */
 376         short   shm_nattch;             /* no. of current attaches */
 377         time_t  shm_atime;              /* last attach time */
 378         time_t  shm_dtime;              /* last detach time */
 379         time_t  shm_ctime;              /* last change time */
 380         void    *shm_handle;            /* internal handle for shm segment */
 381 };
 382
 383 struct oshmctl_args {
 384         struct sysmsg sysmsg;
 385         int shmid;
 386         int cmd;
 387         struct oshmid_ds *ubuf;
 388 };
 389
 390 /*
 391  * MPALMOSTSAFE
 392  */
 393 static int
 394 sys_oshmctl(struct proc *p, struct oshmctl_args *uap)
 395 {
 396 #ifdef COMPAT_43
 397         struct thread *td = curthread;
 398         struct shmid_ds *shmseg;
 399         struct oshmid_ds outbuf;
 400         int error;
 401
 402         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 403                 return (ENOSYS);
 404
 405         get_mplock();
 406         shmseg = shm_find_segment_by_shmid(uap->shmid);
 407         if (shmseg == NULL) {
 408                 error = EINVAL;
 409                 goto done;
 410         }
 411
 412         switch (uap->cmd) {
 413         case IPC_STAT:
 414                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 415                 if (error)
 416                         break;
 417                 outbuf.shm_perm = shmseg->shm_perm;
 418                 outbuf.shm_segsz = shmseg->shm_segsz;
 419                 outbuf.shm_cpid = shmseg->shm_cpid;
 420                 outbuf.shm_lpid = shmseg->shm_lpid;
 421                 outbuf.shm_nattch = shmseg->shm_nattch;
 422                 outbuf.shm_atime = shmseg->shm_atime;
 423                 outbuf.shm_dtime = shmseg->shm_dtime;
 424                 outbuf.shm_ctime = shmseg->shm_ctime;
 425                 outbuf.shm_handle = shmseg->shm_internal;
 426                 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
 427                 break;
 428         default:
 429                 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 430                 error = sys_shmctl((struct shmctl_args *)uap);
 431         }
 432 done:
 433         rel_mplock();
 434         return error;
 435 #else
 436         return EINVAL;
 437 #endif
 438 }
 439
 440 /*
 441  * MPALMOSTSAFE
 442  */
 443 int
 444 sys_shmctl(struct shmctl_args *uap)
 445 {
 446         struct thread *td = curthread;
 447         struct proc *p = td->td_proc;
 448         int error;
 449         struct shmid_ds inbuf;
 450         struct shmid_ds *shmseg;
 451
 452         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 453                 return (ENOSYS);
 454
 455         get_mplock();
 456         shmseg = shm_find_segment_by_shmid(uap->shmid);
 457         if (shmseg == NULL) {
 458                 error = EINVAL;
 459                 goto done;
 460         }
 461
 462         switch (uap->cmd) {
 463         case IPC_STAT:
 464                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 465                 if (error == 0)
 466                         error = copyout(shmseg, uap->buf, sizeof(inbuf));
 467                 break;
 468         case IPC_SET:
 469                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 470                 if (error == 0)
 471                         error = copyin(uap->buf, &inbuf, sizeof(inbuf));
 472                 if (error == 0) {
 473                         shmseg->shm_perm.uid = inbuf.shm_perm.uid;
 474                         shmseg->shm_perm.gid = inbuf.shm_perm.gid;
 475                         shmseg->shm_perm.mode =
 476                             (shmseg->shm_perm.mode & ~ACCESSPERMS) |
 477                             (inbuf.shm_perm.mode & ACCESSPERMS);
 478                         shmseg->shm_ctime = time_second;
 479                 }
 480                 break;
 481         case IPC_RMID:
 482                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 483                 if (error == 0) {
 484                         shmseg->shm_perm.key = IPC_PRIVATE;
 485                         shmseg->shm_perm.mode |= SHMSEG_REMOVED;
 486                         if (shmseg->shm_nattch <= 0) {
 487                                 shm_deallocate_segment(shmseg);
 488                                 shm_last_free = IPCID_TO_IX(uap->shmid);
 489                         }
 490                 }
 491                 break;
 492 #if 0
 493         case SHM_LOCK:
 494         case SHM_UNLOCK:
 495 #endif
 496         default:
 497                 error = EINVAL;
 498                 break;
 499         }
 500 done:
 501         rel_mplock();
 502         return error;
 503 }
 504
 505 static int
 506 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum)
 507 {
 508         struct shmid_ds *shmseg;
 509         int error;
 510
 511         shmseg = &shmsegs[segnum];
 512         if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
 513                 /*
 514                  * This segment is in the process of being allocated.  Wait
 515                  * until it's done, and look the key up again (in case the
 516                  * allocation failed or it was freed).
 517                  */
 518                 shmseg->shm_perm.mode |= SHMSEG_WANTED;
 519                 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
 520                 if (error)
 521                         return error;
 522                 return EAGAIN;
 523         }
 524         if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
 525                 return EEXIST;
 526         error = ipcperm(p, &shmseg->shm_perm, mode);
 527         if (error)
 528                 return error;
 529         if (uap->size && uap->size > shmseg->shm_segsz)
 530                 return EINVAL;
 531         uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 532         return 0;
 533 }
 534
 535 static int
 536 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode)
 537 {
 538         int i, segnum, shmid;
 539         size_t size;
 540         struct ucred *cred = p->p_ucred;
 541         struct shmid_ds *shmseg;
 542         struct shm_handle *shm_handle;
 543
 544         if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
 545                 return EINVAL;
 546         if (shm_nused >= shminfo.shmmni) /* any shmids left? */
 547                 return ENOSPC;
 548         size = round_page(uap->size);
 549         if (shm_committed + btoc(size) > shminfo.shmall)
 550                 return ENOMEM;
 551         if (shm_last_free < 0) {
 552                 shmrealloc();   /* maybe expand the shmsegs[] array */
 553                 for (i = 0; i < shmalloced; i++) {
 554                         if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
 555                                 break;
 556                 }
 557                 if (i == shmalloced)
 558                         return ENOSPC;
 559                 segnum = i;
 560         } else  {
 561                 segnum = shm_last_free;
 562                 shm_last_free = -1;
 563         }
 564         shmseg = &shmsegs[segnum];
 565         /*
 566          * In case we sleep in malloc(), mark the segment present but deleted
 567          * so that noone else tries to create the same key.
 568          */
 569         shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
 570         shmseg->shm_perm.key = uap->key;
 571         shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
 572         shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
 573         shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 574
 575         /*
 576          * We make sure that we have allocated a pager before we need
 577          * to.
 578          */
 579         if (shm_use_phys) {
 580                 shm_handle->shm_object =
 581                    phys_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 582         } else {
 583                 shm_handle->shm_object =
 584                    swap_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 585         }
 586         vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
 587         vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
 588
 589         shmseg->shm_internal = shm_handle;
 590         shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
 591         shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
 592         shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
 593             (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
 594         shmseg->shm_segsz = uap->size;
 595         shmseg->shm_cpid = p->p_pid;
 596         shmseg->shm_lpid = shmseg->shm_nattch = 0;
 597         shmseg->shm_atime = shmseg->shm_dtime = 0;
 598         shmseg->shm_ctime = time_second;
 599         shm_committed += btoc(size);
 600         shm_nused++;
 601
 602         /*
 603          * If a physical mapping is desired and we have a ton of free pages
 604          * we pre-allocate the pages here in order to avoid on-the-fly
 605          * allocation later.  This has a big effect on database warm-up
 606          * times since DFly supports concurrent page faults coming from the
 607          * same VM object for pages which already exist.
 608          *
 609          * This can hang the kernel for a while so only do it if shm_use_phys
 610          * is set to 2 or higher.
 611          */
 612         if (shm_use_phys > 1) {
 613                 vm_pindex_t pi, pmax;
 614                 vm_page_t m;
 615
 616                 pmax = round_page(shmseg->shm_segsz) >> PAGE_SHIFT;
 617                 vm_object_hold(shm_handle->shm_object);
 618                 if (pmax > vmstats.v_free_count)
 619                         pmax = vmstats.v_free_count;
 620                 for (pi = 0; pi < pmax; ++pi) {
 621                         m = vm_page_grab(shm_handle->shm_object, pi,
 622                                          VM_ALLOC_SYSTEM | VM_ALLOC_NULL_OK |
 623                                          VM_ALLOC_ZERO);
 624                         if (m == NULL)
 625                                 break;
 626                         vm_pager_get_page(shm_handle->shm_object, &m, 1);
 627                         vm_page_activate(m);
 628                         vm_page_wakeup(m);
 629                         lwkt_yield();
 630                 }
 631                 vm_object_drop(shm_handle->shm_object);
 632         }
 633
 634         if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
 635                 /*
 636                  * Somebody else wanted this key while we were asleep.  Wake
 637                  * them up now.
 638                  */
 639                 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
 640                 wakeup((caddr_t)shmseg);
 641         }
 642         uap->sysmsg_result = shmid;
 643         return 0;
 644 }
 645
 646 /*
 647  * MPALMOSTSAFE
 648  */
 649 int
 650 sys_shmget(struct shmget_args *uap)
 651 {
 652         struct thread *td = curthread;
 653         struct proc *p = td->td_proc;
 654         int segnum, mode, error;
 655
 656         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 657                 return (ENOSYS);
 658
 659         mode = uap->shmflg & ACCESSPERMS;
 660         get_mplock();
 661
 662         if (uap->key != IPC_PRIVATE) {
 663         again:
 664                 segnum = shm_find_segment_by_key(uap->key);
 665                 if (segnum >= 0) {
 666                         error = shmget_existing(p, uap, mode, segnum);
 667                         if (error == EAGAIN)
 668                                 goto again;
 669                         goto done;
 670                 }
 671                 if ((uap->shmflg & IPC_CREAT) == 0) {
 672                         error = ENOENT;
 673                         goto done;
 674                 }
 675         }
 676         error = shmget_allocate_segment(p, uap, mode);
 677 done:
 678         rel_mplock();
 679         return (error);
 680 }
 681
 682 /*
 683  * shmsys_args(int which, int a2, ...) (VARARGS)
 684  *
 685  * MPALMOSTSAFE
 686  */
 687 int
 688 sys_shmsys(struct shmsys_args *uap)
 689 {
 690         struct thread *td = curthread;
 691         unsigned int which = (unsigned int)uap->which;
 692         int error;
 693
 694         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 695                 return (ENOSYS);
 696
 697         if (which >= NELEM(shmcalls))
 698                 return EINVAL;
 699         get_mplock();
 700         bcopy(&uap->a2, &uap->which,
 701                 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2));
 702         error = ((*shmcalls[which])(uap));
 703         rel_mplock();
 704
 705         return(error);
 706 }
 707
 708 void
 709 shmfork(struct proc *p1, struct proc *p2)
 710 {
 711         struct shmmap_state *shmmap_s;
 712         size_t size;
 713         int i;
 714
 715         get_mplock();
 716         size = shminfo.shmseg * sizeof(struct shmmap_state);
 717         shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 718         bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
 719         p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 720         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
 721                 if (shmmap_s->shmid != -1)
 722                         shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
 723         }
 724         rel_mplock();
 725 }
 726
 727 void
 728 shmexit(struct vmspace *vm)
 729 {
 730         struct shmmap_state *base, *shm;
 731         int i;
 732
 733         if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
 734                 vm->vm_shm = NULL;
 735                 get_mplock();
 736                 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
 737                         if (shm->shmid != -1)
 738                                 shm_delete_mapping(vm, shm);
 739                 }
 740                 kfree(base, M_SHM);
 741                 rel_mplock();
 742         }
 743 }
 744
 745 static void
 746 shmrealloc(void)
 747 {
 748         int i;
 749         struct shmid_ds *newsegs;
 750
 751         if (shmalloced >= shminfo.shmmni)
 752                 return;
 753
 754         newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
 755         for (i = 0; i < shmalloced; i++)
 756                 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
 757         for (; i < shminfo.shmmni; i++) {
 758                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 759                 shmsegs[i].shm_perm.seq = 0;
 760         }
 761         kfree(shmsegs, M_SHM);
 762         shmsegs = newsegs;
 763         shmalloced = shminfo.shmmni;
 764 }
 765
 766 static void
 767 shminit(void *dummy)
 768 {
 769         int i;
 770
 771         /*
 772          * If not overridden by a tunable set the maximum shm to
 773          * 2/3 of main memory.
 774          */
 775         if (shminfo.shmall == 0)
 776                 shminfo.shmall = (size_t)vmstats.v_page_count * 2 / 3;
 777
 778         shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
 779         shmalloced = shminfo.shmmni;
 780         shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
 781         for (i = 0; i < shmalloced; i++) {
 782                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 783                 shmsegs[i].shm_perm.seq = 0;
 784         }
 785         shm_last_free = 0;
 786         shm_nused = 0;
 787         shm_committed = 0;
 788 }
 789 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);