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;
 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         int rv;
 263
 264         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 265                 return (ENOSYS);
 266
 267         get_mplock();
 268 again:
 269         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 270         if (shmmap_s == NULL) {
 271                 size = shminfo.shmseg * sizeof(struct shmmap_state);
 272                 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 273                 for (i = 0; i < shminfo.shmseg; i++)
 274                         shmmap_s[i].shmid = -1;
 275                 if (p->p_vmspace->vm_shm != NULL) {
 276                         kfree(shmmap_s, M_SHM);
 277                         goto again;
 278                 }
 279                 p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 280         }
 281         shmseg = shm_find_segment_by_shmid(uap->shmid);
 282         if (shmseg == NULL) {
 283                 error = EINVAL;
 284                 goto done;
 285         }
 286         error = ipcperm(p, &shmseg->shm_perm,
 287                         (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
 288         if (error)
 289                 goto done;
 290         for (i = 0; i < shminfo.shmseg; i++) {
 291                 if (shmmap_s->shmid == -1)
 292                         break;
 293                 shmmap_s++;
 294         }
 295         if (i >= shminfo.shmseg) {
 296                 error = EMFILE;
 297                 goto done;
 298         }
 299         size = round_page(shmseg->shm_segsz);
 300 #ifdef VM_PROT_READ_IS_EXEC
 301         prot = VM_PROT_READ | VM_PROT_EXECUTE;
 302 #else
 303         prot = VM_PROT_READ;
 304 #endif
 305         if ((uap->shmflg & SHM_RDONLY) == 0)
 306                 prot |= VM_PROT_WRITE;
 307         flags = MAP_ANON | MAP_SHARED;
 308         if (uap->shmaddr) {
 309                 flags |= MAP_FIXED;
 310                 if (uap->shmflg & SHM_RND) {
 311                         attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
 312                 } else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) {
 313                         attach_va = (vm_offset_t)uap->shmaddr;
 314                 } else {
 315                         error = EINVAL;
 316                         goto done;
 317                 }
 318         } else {
 319                 /*
 320                  * This is just a hint to vm_map_find() about where to put it.
 321                  */
 322                 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + maxtsiz + maxdsiz);
 323         }
 324
 325         shm_handle = shmseg->shm_internal;
 326         vm_object_hold(shm_handle->shm_object);
 327         vm_object_chain_wait(shm_handle->shm_object);
 328         vm_object_reference_locked(shm_handle->shm_object);
 329         rv = vm_map_find(&p->p_vmspace->vm_map,
 330                          shm_handle->shm_object, 0,
 331                          &attach_va,
 332                          size, PAGE_SIZE,
 333                          ((flags & MAP_FIXED) ? 0 : 1),
 334                          VM_MAPTYPE_NORMAL,
 335                          prot, prot,
 336                          0);
 337         vm_object_drop(shm_handle->shm_object);
 338         if (rv != KERN_SUCCESS) {
 339                 vm_object_deallocate(shm_handle->shm_object);
 340                 error = ENOMEM;
 341                 goto done;
 342         }
 343         vm_map_inherit(&p->p_vmspace->vm_map,
 344                        attach_va, attach_va + size, VM_INHERIT_SHARE);
 345
 346         KKASSERT(shmmap_s->shmid == -1);
 347         shmmap_s->va = attach_va;
 348         shmmap_s->shmid = uap->shmid;
 349         shmseg->shm_lpid = p->p_pid;
 350         shmseg->shm_atime = time_second;
 351         shmseg->shm_nattch++;
 352         uap->sysmsg_resultp = (void *)attach_va;
 353         error = 0;
 354 done:
 355         rel_mplock();
 356         return error;
 357 }
 358
 359 struct oshmid_ds {
 360         struct  ipc_perm shm_perm;      /* operation perms */
 361         int     shm_segsz;              /* size of segment (bytes) */
 362         ushort  shm_cpid;               /* pid, creator */
 363         ushort  shm_lpid;               /* pid, last operation */
 364         short   shm_nattch;             /* no. of current attaches */
 365         time_t  shm_atime;              /* last attach time */
 366         time_t  shm_dtime;              /* last detach time */
 367         time_t  shm_ctime;              /* last change time */
 368         void    *shm_handle;            /* internal handle for shm segment */
 369 };
 370
 371 struct oshmctl_args {
 372         struct sysmsg sysmsg;
 373         int shmid;
 374         int cmd;
 375         struct oshmid_ds *ubuf;
 376 };
 377
 378 /*
 379  * MPALMOSTSAFE
 380  */
 381 static int
 382 sys_oshmctl(struct proc *p, struct oshmctl_args *uap)
 383 {
 384 #ifdef COMPAT_43
 385         struct thread *td = curthread;
 386         struct shmid_ds *shmseg;
 387         struct oshmid_ds outbuf;
 388         int error;
 389
 390         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 391                 return (ENOSYS);
 392
 393         get_mplock();
 394         shmseg = shm_find_segment_by_shmid(uap->shmid);
 395         if (shmseg == NULL) {
 396                 error = EINVAL;
 397                 goto done;
 398         }
 399
 400         switch (uap->cmd) {
 401         case IPC_STAT:
 402                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 403                 if (error)
 404                         break;
 405                 outbuf.shm_perm = shmseg->shm_perm;
 406                 outbuf.shm_segsz = shmseg->shm_segsz;
 407                 outbuf.shm_cpid = shmseg->shm_cpid;
 408                 outbuf.shm_lpid = shmseg->shm_lpid;
 409                 outbuf.shm_nattch = shmseg->shm_nattch;
 410                 outbuf.shm_atime = shmseg->shm_atime;
 411                 outbuf.shm_dtime = shmseg->shm_dtime;
 412                 outbuf.shm_ctime = shmseg->shm_ctime;
 413                 outbuf.shm_handle = shmseg->shm_internal;
 414                 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
 415                 break;
 416         default:
 417                 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 418                 error = sys_shmctl((struct shmctl_args *)uap);
 419         }
 420 done:
 421         rel_mplock();
 422         return error;
 423 #else
 424         return EINVAL;
 425 #endif
 426 }
 427
 428 /*
 429  * MPALMOSTSAFE
 430  */
 431 int
 432 sys_shmctl(struct shmctl_args *uap)
 433 {
 434         struct thread *td = curthread;
 435         struct proc *p = td->td_proc;
 436         int error;
 437         struct shmid_ds inbuf;
 438         struct shmid_ds *shmseg;
 439
 440         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 441                 return (ENOSYS);
 442
 443         get_mplock();
 444         shmseg = shm_find_segment_by_shmid(uap->shmid);
 445         if (shmseg == NULL) {
 446                 error = EINVAL;
 447                 goto done;
 448         }
 449
 450         switch (uap->cmd) {
 451         case IPC_STAT:
 452                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 453                 if (error == 0)
 454                         error = copyout(shmseg, uap->buf, sizeof(inbuf));
 455                 break;
 456         case IPC_SET:
 457                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 458                 if (error == 0)
 459                         error = copyin(uap->buf, &inbuf, sizeof(inbuf));
 460                 if (error == 0) {
 461                         shmseg->shm_perm.uid = inbuf.shm_perm.uid;
 462                         shmseg->shm_perm.gid = inbuf.shm_perm.gid;
 463                         shmseg->shm_perm.mode =
 464                             (shmseg->shm_perm.mode & ~ACCESSPERMS) |
 465                             (inbuf.shm_perm.mode & ACCESSPERMS);
 466                         shmseg->shm_ctime = time_second;
 467                 }
 468                 break;
 469         case IPC_RMID:
 470                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 471                 if (error == 0) {
 472                         shmseg->shm_perm.key = IPC_PRIVATE;
 473                         shmseg->shm_perm.mode |= SHMSEG_REMOVED;
 474                         if (shmseg->shm_nattch <= 0) {
 475                                 shm_deallocate_segment(shmseg);
 476                                 shm_last_free = IPCID_TO_IX(uap->shmid);
 477                         }
 478                 }
 479                 break;
 480 #if 0
 481         case SHM_LOCK:
 482         case SHM_UNLOCK:
 483 #endif
 484         default:
 485                 error = EINVAL;
 486                 break;
 487         }
 488 done:
 489         rel_mplock();
 490         return error;
 491 }
 492
 493 static int
 494 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum)
 495 {
 496         struct shmid_ds *shmseg;
 497         int error;
 498
 499         shmseg = &shmsegs[segnum];
 500         if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
 501                 /*
 502                  * This segment is in the process of being allocated.  Wait
 503                  * until it's done, and look the key up again (in case the
 504                  * allocation failed or it was freed).
 505                  */
 506                 shmseg->shm_perm.mode |= SHMSEG_WANTED;
 507                 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
 508                 if (error)
 509                         return error;
 510                 return EAGAIN;
 511         }
 512         if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
 513                 return EEXIST;
 514         error = ipcperm(p, &shmseg->shm_perm, mode);
 515         if (error)
 516                 return error;
 517         if (uap->size && uap->size > shmseg->shm_segsz)
 518                 return EINVAL;
 519         uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 520         return 0;
 521 }
 522
 523 static int
 524 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode)
 525 {
 526         int i, segnum, shmid;
 527         size_t size;
 528         struct ucred *cred = p->p_ucred;
 529         struct shmid_ds *shmseg;
 530         struct shm_handle *shm_handle;
 531
 532         if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
 533                 return EINVAL;
 534         if (shm_nused >= shminfo.shmmni) /* any shmids left? */
 535                 return ENOSPC;
 536         size = round_page(uap->size);
 537         if (shm_committed + btoc(size) > shminfo.shmall)
 538                 return ENOMEM;
 539         if (shm_last_free < 0) {
 540                 shmrealloc();   /* maybe expand the shmsegs[] array */
 541                 for (i = 0; i < shmalloced; i++) {
 542                         if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
 543                                 break;
 544                 }
 545                 if (i == shmalloced)
 546                         return ENOSPC;
 547                 segnum = i;
 548         } else  {
 549                 segnum = shm_last_free;
 550                 shm_last_free = -1;
 551         }
 552         shmseg = &shmsegs[segnum];
 553         /*
 554          * In case we sleep in malloc(), mark the segment present but deleted
 555          * so that noone else tries to create the same key.
 556          */
 557         shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
 558         shmseg->shm_perm.key = uap->key;
 559         shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
 560         shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
 561         shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 562
 563         /*
 564          * We make sure that we have allocated a pager before we need
 565          * to.
 566          */
 567         if (shm_use_phys) {
 568                 shm_handle->shm_object =
 569                    phys_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 570         } else {
 571                 shm_handle->shm_object =
 572                    swap_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 573         }
 574         vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
 575         vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
 576
 577         shmseg->shm_internal = shm_handle;
 578         shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
 579         shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
 580         shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
 581             (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
 582         shmseg->shm_segsz = uap->size;
 583         shmseg->shm_cpid = p->p_pid;
 584         shmseg->shm_lpid = shmseg->shm_nattch = 0;
 585         shmseg->shm_atime = shmseg->shm_dtime = 0;
 586         shmseg->shm_ctime = time_second;
 587         shm_committed += btoc(size);
 588         shm_nused++;
 589
 590         /*
 591          * If a physical mapping is desired and we have a ton of free pages
 592          * we pre-allocate the pages here in order to avoid on-the-fly
 593          * allocation later.  This has a big effect on database warm-up
 594          * times since DFly supports concurrent page faults coming from the
 595          * same VM object for pages which already exist.
 596          *
 597          * This can hang the kernel for a while so only do it if shm_use_phys
 598          * is set to 2 or higher.
 599          */
 600         if (shm_use_phys > 1) {
 601                 vm_pindex_t pi, pmax;
 602                 vm_page_t m;
 603
 604                 pmax = round_page(shmseg->shm_segsz) >> PAGE_SHIFT;
 605                 vm_object_hold(shm_handle->shm_object);
 606                 if (pmax > vmstats.v_free_count)
 607                         pmax = vmstats.v_free_count;
 608                 for (pi = 0; pi < pmax; ++pi) {
 609                         m = vm_page_grab(shm_handle->shm_object, pi,
 610                                          VM_ALLOC_SYSTEM | VM_ALLOC_NULL_OK |
 611                                          VM_ALLOC_ZERO);
 612                         if (m == NULL)
 613                                 break;
 614                         vm_pager_get_page(shm_handle->shm_object, &m, 1);
 615                         vm_page_activate(m);
 616                         vm_page_wakeup(m);
 617                         lwkt_yield();
 618                 }
 619                 vm_object_drop(shm_handle->shm_object);
 620         }
 621
 622         if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
 623                 /*
 624                  * Somebody else wanted this key while we were asleep.  Wake
 625                  * them up now.
 626                  */
 627                 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
 628                 wakeup((caddr_t)shmseg);
 629         }
 630         uap->sysmsg_result = shmid;
 631         return 0;
 632 }
 633
 634 /*
 635  * MPALMOSTSAFE
 636  */
 637 int
 638 sys_shmget(struct shmget_args *uap)
 639 {
 640         struct thread *td = curthread;
 641         struct proc *p = td->td_proc;
 642         int segnum, mode, error;
 643
 644         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 645                 return (ENOSYS);
 646
 647         mode = uap->shmflg & ACCESSPERMS;
 648         get_mplock();
 649
 650         if (uap->key != IPC_PRIVATE) {
 651         again:
 652                 segnum = shm_find_segment_by_key(uap->key);
 653                 if (segnum >= 0) {
 654                         error = shmget_existing(p, uap, mode, segnum);
 655                         if (error == EAGAIN)
 656                                 goto again;
 657                         goto done;
 658                 }
 659                 if ((uap->shmflg & IPC_CREAT) == 0) {
 660                         error = ENOENT;
 661                         goto done;
 662                 }
 663         }
 664         error = shmget_allocate_segment(p, uap, mode);
 665 done:
 666         rel_mplock();
 667         return (error);
 668 }
 669
 670 /*
 671  * shmsys_args(int which, int a2, ...) (VARARGS)
 672  *
 673  * MPALMOSTSAFE
 674  */
 675 int
 676 sys_shmsys(struct shmsys_args *uap)
 677 {
 678         struct thread *td = curthread;
 679         unsigned int which = (unsigned int)uap->which;
 680         int error;
 681
 682         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 683                 return (ENOSYS);
 684
 685         if (which >= NELEM(shmcalls))
 686                 return EINVAL;
 687         get_mplock();
 688         bcopy(&uap->a2, &uap->which,
 689                 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2));
 690         error = ((*shmcalls[which])(uap));
 691         rel_mplock();
 692
 693         return(error);
 694 }
 695
 696 void
 697 shmfork(struct proc *p1, struct proc *p2)
 698 {
 699         struct shmmap_state *shmmap_s;
 700         size_t size;
 701         int i;
 702
 703         get_mplock();
 704         size = shminfo.shmseg * sizeof(struct shmmap_state);
 705         shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 706         bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
 707         p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 708         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
 709                 if (shmmap_s->shmid != -1)
 710                         shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
 711         }
 712         rel_mplock();
 713 }
 714
 715 void
 716 shmexit(struct vmspace *vm)
 717 {
 718         struct shmmap_state *base, *shm;
 719         int i;
 720
 721         if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
 722                 vm->vm_shm = NULL;
 723                 get_mplock();
 724                 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
 725                         if (shm->shmid != -1)
 726                                 shm_delete_mapping(vm, shm);
 727                 }
 728                 kfree(base, M_SHM);
 729                 rel_mplock();
 730         }
 731 }
 732
 733 static void
 734 shmrealloc(void)
 735 {
 736         int i;
 737         struct shmid_ds *newsegs;
 738
 739         if (shmalloced >= shminfo.shmmni)
 740                 return;
 741
 742         newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
 743         for (i = 0; i < shmalloced; i++)
 744                 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
 745         for (; i < shminfo.shmmni; i++) {
 746                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 747                 shmsegs[i].shm_perm.seq = 0;
 748         }
 749         kfree(shmsegs, M_SHM);
 750         shmsegs = newsegs;
 751         shmalloced = shminfo.shmmni;
 752 }
 753
 754 static void
 755 shminit(void *dummy)
 756 {
 757         int i;
 758
 759         /*
 760          * If not overridden by a tunable set the maximum shm to
 761          * 2/3 of main memory.
 762          */
 763         if (shminfo.shmall == 0)
 764                 shminfo.shmall = (size_t)vmstats.v_page_count * 2 / 3;
 765
 766         shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
 767         shmalloced = shminfo.shmmni;
 768         shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
 769         for (i = 0; i < shmalloced; i++) {
 770                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 771                 shmsegs[i].shm_perm.seq = 0;
 772         }
 773         shm_last_free = 0;
 774         shm_nused = 0;
 775         shm_committed = 0;
 776 }
 777 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);