3 * Copyright (C) 1992, 1993 Krishna Balasubramanian
4 * Many improvements/fixes by Bruno Haible.
5 * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
6 * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
8 * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
9 * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
10 * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
11 * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
12 * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
13 * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
14 * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
16 * support for audit of ipc object properties and permission changes
17 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
21 * Pavel Emelianov <xemul@openvz.org>
24 #include <linux/slab.h>
26 #include <linux/hugetlb.h>
27 #include <linux/shm.h>
28 #include <linux/init.h>
29 #include <linux/file.h>
30 #include <linux/mman.h>
31 #include <linux/shmem_fs.h>
32 #include <linux/security.h>
33 #include <linux/syscalls.h>
34 #include <linux/audit.h>
35 #include <linux/capability.h>
36 #include <linux/ptrace.h>
37 #include <linux/seq_file.h>
38 #include <linux/mutex.h>
39 #include <linux/nsproxy.h>
40 #include <linux/mount.h>
42 #include <asm/uaccess.h>
46 struct shm_file_data {
48 struct ipc_namespace *ns;
50 const struct vm_operations_struct *vm_ops;
53 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
55 static const struct file_operations shm_file_operations;
56 static struct vm_operations_struct shm_vm_ops;
58 static struct ipc_ids init_shm_ids;
60 #define shm_ids(ns) (*((ns)->ids[IPC_SHM_IDS]))
62 #define shm_unlock(shp) \
63 ipc_unlock(&(shp)->shm_perm)
64 #define shm_buildid(ns, id, seq) \
65 ipc_buildid(&shm_ids(ns), id, seq)
67 static int newseg(struct ipc_namespace *, struct ipc_params *);
68 static void shm_open(struct vm_area_struct *vma);
69 static void shm_close(struct vm_area_struct *vma);
70 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
72 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
75 static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
77 ns->ids[IPC_SHM_IDS] = ids;
78 ns->shm_ctlmax = SHMMAX;
79 ns->shm_ctlall = SHMALL;
80 ns->shm_ctlmni = SHMMNI;
85 static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
88 shp->shm_perm.mode |= SHM_DEST;
89 /* Do not find it any more */
90 shp->shm_perm.key = IPC_PRIVATE;
96 int shm_init_ns(struct ipc_namespace *ns)
100 ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
104 __shm_init_ns(ns, ids);
108 void shm_exit_ns(struct ipc_namespace *ns)
110 struct shmid_kernel *shp;
114 mutex_lock(&shm_ids(ns).mutex);
116 in_use = shm_ids(ns).in_use;
118 for (total = 0, next_id = 0; total < in_use; next_id++) {
119 shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
122 ipc_lock_by_ptr(&shp->shm_perm);
123 do_shm_rmid(ns, shp);
126 mutex_unlock(&shm_ids(ns).mutex);
128 kfree(ns->ids[IPC_SHM_IDS]);
129 ns->ids[IPC_SHM_IDS] = NULL;
132 void __init shm_init (void)
134 __shm_init_ns(&init_ipc_ns, &init_shm_ids);
135 ipc_init_proc_interface("sysvipc/shm",
136 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n",
137 IPC_SHM_IDS, sysvipc_shm_proc_show);
140 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
142 return (struct shmid_kernel *) ipc_lock(&shm_ids(ns), id);
145 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
148 return (struct shmid_kernel *) ipc_lock_check(&shm_ids(ns), id);
151 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
153 ipc_rmid(&shm_ids(ns), &s->shm_perm);
156 static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
158 return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
163 /* This is called by fork, once for every shm attach. */
164 static void shm_open(struct vm_area_struct *vma)
166 struct file *file = vma->vm_file;
167 struct shm_file_data *sfd = shm_file_data(file);
168 struct shmid_kernel *shp;
170 shp = shm_lock(sfd->ns, sfd->id);
172 shp->shm_atim = get_seconds();
173 shp->shm_lprid = task_tgid_vnr(current);
179 * shm_destroy - free the struct shmid_kernel
181 * @shp: struct to free
183 * It has to be called with shp and shm_ids.mutex locked,
184 * but returns with shp unlocked and freed.
186 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
188 ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
191 if (!is_file_hugepages(shp->shm_file))
192 shmem_lock(shp->shm_file, 0, shp->mlock_user);
194 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
196 fput (shp->shm_file);
197 security_shm_free(shp);
202 * remove the attach descriptor vma.
203 * free memory for segment if it is marked destroyed.
204 * The descriptor has already been removed from the current->mm->mmap list
205 * and will later be kfree()d.
207 static void shm_close(struct vm_area_struct *vma)
209 struct file * file = vma->vm_file;
210 struct shm_file_data *sfd = shm_file_data(file);
211 struct shmid_kernel *shp;
212 struct ipc_namespace *ns = sfd->ns;
214 mutex_lock(&shm_ids(ns).mutex);
215 /* remove from the list of attaches of the shm segment */
216 shp = shm_lock(ns, sfd->id);
218 shp->shm_lprid = task_tgid_vnr(current);
219 shp->shm_dtim = get_seconds();
221 if(shp->shm_nattch == 0 &&
222 shp->shm_perm.mode & SHM_DEST)
223 shm_destroy(ns, shp);
226 mutex_unlock(&shm_ids(ns).mutex);
229 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
231 struct file *file = vma->vm_file;
232 struct shm_file_data *sfd = shm_file_data(file);
234 return sfd->vm_ops->fault(vma, vmf);
238 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
240 struct file *file = vma->vm_file;
241 struct shm_file_data *sfd = shm_file_data(file);
243 if (sfd->vm_ops->set_policy)
244 err = sfd->vm_ops->set_policy(vma, new);
248 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
251 struct file *file = vma->vm_file;
252 struct shm_file_data *sfd = shm_file_data(file);
253 struct mempolicy *pol = NULL;
255 if (sfd->vm_ops->get_policy)
256 pol = sfd->vm_ops->get_policy(vma, addr);
257 else if (vma->vm_policy)
258 pol = vma->vm_policy;
260 pol = current->mempolicy;
265 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
267 struct shm_file_data *sfd = shm_file_data(file);
270 ret = sfd->file->f_op->mmap(sfd->file, vma);
273 sfd->vm_ops = vma->vm_ops;
275 BUG_ON(!sfd->vm_ops->fault);
277 vma->vm_ops = &shm_vm_ops;
283 static int shm_release(struct inode *ino, struct file *file)
285 struct shm_file_data *sfd = shm_file_data(file);
288 shm_file_data(file) = NULL;
293 static int shm_fsync(struct file *file, struct dentry *dentry, int datasync)
295 int (*fsync) (struct file *, struct dentry *, int datasync);
296 struct shm_file_data *sfd = shm_file_data(file);
299 fsync = sfd->file->f_op->fsync;
301 ret = fsync(sfd->file, sfd->file->f_path.dentry, datasync);
305 static unsigned long shm_get_unmapped_area(struct file *file,
306 unsigned long addr, unsigned long len, unsigned long pgoff,
309 struct shm_file_data *sfd = shm_file_data(file);
310 return get_unmapped_area(sfd->file, addr, len, pgoff, flags);
313 int is_file_shm_hugepages(struct file *file)
317 if (file->f_op == &shm_file_operations) {
318 struct shm_file_data *sfd;
319 sfd = shm_file_data(file);
320 ret = is_file_hugepages(sfd->file);
325 static const struct file_operations shm_file_operations = {
328 .release = shm_release,
329 .get_unmapped_area = shm_get_unmapped_area,
332 static struct vm_operations_struct shm_vm_ops = {
333 .open = shm_open, /* callback for a new vm-area open */
334 .close = shm_close, /* callback for when the vm-area is released */
336 #if defined(CONFIG_NUMA)
337 .set_policy = shm_set_policy,
338 .get_policy = shm_get_policy,
342 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
344 key_t key = params->key;
345 int shmflg = params->flg;
346 size_t size = params->u.size;
348 struct shmid_kernel *shp;
349 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
354 if (size < SHMMIN || size > ns->shm_ctlmax)
357 if (ns->shm_tot + numpages > ns->shm_ctlall)
360 shp = ipc_rcu_alloc(sizeof(*shp));
364 shp->shm_perm.key = key;
365 shp->shm_perm.mode = (shmflg & S_IRWXUGO);
366 shp->mlock_user = NULL;
368 shp->shm_perm.security = NULL;
369 error = security_shm_alloc(shp);
375 sprintf (name, "SYSV%08x", key);
376 if (shmflg & SHM_HUGETLB) {
377 /* hugetlb_file_setup takes care of mlock user accounting */
378 file = hugetlb_file_setup(name, size);
379 shp->mlock_user = current->user;
381 int acctflag = VM_ACCOUNT;
383 * Do not allow no accounting for OVERCOMMIT_NEVER, even
386 if ((shmflg & SHM_NORESERVE) &&
387 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
389 file = shmem_file_setup(name, size, acctflag);
391 error = PTR_ERR(file);
396 id = shm_addid(ns, shp);
400 shp->shm_cprid = task_tgid_vnr(current);
402 shp->shm_atim = shp->shm_dtim = 0;
403 shp->shm_ctim = get_seconds();
404 shp->shm_segsz = size;
406 shp->shm_perm.id = shm_buildid(ns, id, shp->shm_perm.seq);
407 shp->shm_file = file;
409 * shmid gets reported as "inode#" in /proc/pid/maps.
410 * proc-ps tools use this. Changing this will break them.
412 file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
414 ns->shm_tot += numpages;
415 error = shp->shm_perm.id;
422 security_shm_free(shp);
427 static inline int shm_security(void *shp, int shmflg)
429 return security_shm_associate((struct shmid_kernel *) shp, shmflg);
432 static inline int shm_more_checks(void *shp, struct ipc_params *params)
434 if (((struct shmid_kernel *)shp)->shm_segsz < params->u.size)
440 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
442 struct ipc_namespace *ns;
443 struct ipc_ops shm_ops;
444 struct ipc_params shm_params;
446 ns = current->nsproxy->ipc_ns;
448 shm_ops.getnew = newseg;
449 shm_ops.associate = shm_security;
450 shm_ops.more_checks = shm_more_checks;
452 shm_params.key = key;
453 shm_params.flg = shmflg;
454 shm_params.u.size = size;
456 return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
459 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
463 return copy_to_user(buf, in, sizeof(*in));
468 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
469 out.shm_segsz = in->shm_segsz;
470 out.shm_atime = in->shm_atime;
471 out.shm_dtime = in->shm_dtime;
472 out.shm_ctime = in->shm_ctime;
473 out.shm_cpid = in->shm_cpid;
474 out.shm_lpid = in->shm_lpid;
475 out.shm_nattch = in->shm_nattch;
477 return copy_to_user(buf, &out, sizeof(out));
490 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
495 struct shmid64_ds tbuf;
497 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
500 out->uid = tbuf.shm_perm.uid;
501 out->gid = tbuf.shm_perm.gid;
502 out->mode = tbuf.shm_perm.mode;
508 struct shmid_ds tbuf_old;
510 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
513 out->uid = tbuf_old.shm_perm.uid;
514 out->gid = tbuf_old.shm_perm.gid;
515 out->mode = tbuf_old.shm_perm.mode;
524 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
528 return copy_to_user(buf, in, sizeof(*in));
533 if(in->shmmax > INT_MAX)
534 out.shmmax = INT_MAX;
536 out.shmmax = (int)in->shmmax;
538 out.shmmin = in->shmmin;
539 out.shmmni = in->shmmni;
540 out.shmseg = in->shmseg;
541 out.shmall = in->shmall;
543 return copy_to_user(buf, &out, sizeof(out));
550 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
559 in_use = shm_ids(ns).in_use;
561 for (total = 0, next_id = 0; total < in_use; next_id++) {
562 struct shmid_kernel *shp;
566 * idr_find() is called via shm_get(), so with shm_ids.mutex
567 * locked. Since ipc_addid() is also called with
568 * shm_ids.mutex down, there is no need to add read barriers
569 * here to gurantee the writes in ipc_addid() are seen in
570 * order here (for Alpha).
571 * However idr_find() itself does not necessary require
572 * ipc_ids.mutex down. So if idr_find() is used by other
573 * places without ipc_ids.mutex down, then it needs read
574 * read memory barriers as ipc_lock() does.
577 shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
581 inode = shp->shm_file->f_path.dentry->d_inode;
583 if (is_file_hugepages(shp->shm_file)) {
584 struct address_space *mapping = inode->i_mapping;
585 *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
587 struct shmem_inode_info *info = SHMEM_I(inode);
588 spin_lock(&info->lock);
589 *rss += inode->i_mapping->nrpages;
590 *swp += info->swapped;
591 spin_unlock(&info->lock);
598 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
600 struct shm_setbuf setbuf;
601 struct shmid_kernel *shp;
603 struct ipc_namespace *ns;
605 if (cmd < 0 || shmid < 0) {
610 version = ipc_parse_version(&cmd);
611 ns = current->nsproxy->ipc_ns;
613 switch (cmd) { /* replace with proc interface ? */
616 struct shminfo64 shminfo;
618 err = security_shm_shmctl(NULL, cmd);
622 memset(&shminfo,0,sizeof(shminfo));
623 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
624 shminfo.shmmax = ns->shm_ctlmax;
625 shminfo.shmall = ns->shm_ctlall;
627 shminfo.shmmin = SHMMIN;
628 if(copy_shminfo_to_user (buf, &shminfo, version))
630 /* reading a integer is always atomic */
631 err = ipc_get_maxid(&shm_ids(ns));
638 struct shm_info shm_info;
640 err = security_shm_shmctl(NULL, cmd);
644 memset(&shm_info,0,sizeof(shm_info));
645 mutex_lock(&shm_ids(ns).mutex);
646 shm_info.used_ids = shm_ids(ns).in_use;
647 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
648 shm_info.shm_tot = ns->shm_tot;
649 shm_info.swap_attempts = 0;
650 shm_info.swap_successes = 0;
651 err = ipc_get_maxid(&shm_ids(ns));
652 mutex_unlock(&shm_ids(ns).mutex);
653 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
658 err = err < 0 ? 0 : err;
664 struct shmid64_ds tbuf;
672 if (cmd == SHM_STAT) {
673 shp = shm_lock(ns, shmid);
678 result = shp->shm_perm.id;
680 shp = shm_lock_check(ns, shmid);
688 if (ipcperms (&shp->shm_perm, S_IRUGO))
690 err = security_shm_shmctl(shp, cmd);
693 memset(&tbuf, 0, sizeof(tbuf));
694 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
695 tbuf.shm_segsz = shp->shm_segsz;
696 tbuf.shm_atime = shp->shm_atim;
697 tbuf.shm_dtime = shp->shm_dtim;
698 tbuf.shm_ctime = shp->shm_ctim;
699 tbuf.shm_cpid = shp->shm_cprid;
700 tbuf.shm_lpid = shp->shm_lprid;
701 tbuf.shm_nattch = shp->shm_nattch;
703 if(copy_shmid_to_user (buf, &tbuf, version))
712 shp = shm_lock_check(ns, shmid);
718 err = audit_ipc_obj(&(shp->shm_perm));
722 if (!capable(CAP_IPC_LOCK)) {
724 if (current->euid != shp->shm_perm.uid &&
725 current->euid != shp->shm_perm.cuid)
727 if (cmd == SHM_LOCK &&
728 !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
732 err = security_shm_shmctl(shp, cmd);
737 struct user_struct * user = current->user;
738 if (!is_file_hugepages(shp->shm_file)) {
739 err = shmem_lock(shp->shm_file, 1, user);
740 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
741 shp->shm_perm.mode |= SHM_LOCKED;
742 shp->mlock_user = user;
745 } else if (!is_file_hugepages(shp->shm_file)) {
746 shmem_lock(shp->shm_file, 0, shp->mlock_user);
747 shp->shm_perm.mode &= ~SHM_LOCKED;
748 shp->mlock_user = NULL;
756 * We cannot simply remove the file. The SVID states
757 * that the block remains until the last person
758 * detaches from it, then is deleted. A shmat() on
759 * an RMID segment is legal in older Linux and if
760 * we change it apps break...
762 * Instead we set a destroyed flag, and then blow
763 * the name away when the usage hits zero.
765 mutex_lock(&shm_ids(ns).mutex);
766 shp = shm_lock_check(ns, shmid);
772 err = audit_ipc_obj(&(shp->shm_perm));
776 if (current->euid != shp->shm_perm.uid &&
777 current->euid != shp->shm_perm.cuid &&
778 !capable(CAP_SYS_ADMIN)) {
783 err = security_shm_shmctl(shp, cmd);
787 do_shm_rmid(ns, shp);
788 mutex_unlock(&shm_ids(ns).mutex);
799 if (copy_shmid_from_user (&setbuf, buf, version)) {
803 mutex_lock(&shm_ids(ns).mutex);
804 shp = shm_lock_check(ns, shmid);
809 err = audit_ipc_obj(&(shp->shm_perm));
812 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
816 if (current->euid != shp->shm_perm.uid &&
817 current->euid != shp->shm_perm.cuid &&
818 !capable(CAP_SYS_ADMIN)) {
822 err = security_shm_shmctl(shp, cmd);
826 shp->shm_perm.uid = setbuf.uid;
827 shp->shm_perm.gid = setbuf.gid;
828 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
829 | (setbuf.mode & S_IRWXUGO);
830 shp->shm_ctim = get_seconds();
843 mutex_unlock(&shm_ids(ns).mutex);
852 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
854 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
855 * "raddr" thing points to kernel space, and there has to be a wrapper around
858 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
860 struct shmid_kernel *shp;
868 unsigned long user_addr;
869 struct ipc_namespace *ns;
870 struct shm_file_data *sfd;
877 else if ((addr = (ulong)shmaddr)) {
878 if (addr & (SHMLBA-1)) {
879 if (shmflg & SHM_RND)
880 addr &= ~(SHMLBA-1); /* round down */
882 #ifndef __ARCH_FORCE_SHMLBA
883 if (addr & ~PAGE_MASK)
887 flags = MAP_SHARED | MAP_FIXED;
889 if ((shmflg & SHM_REMAP))
895 if (shmflg & SHM_RDONLY) {
900 prot = PROT_READ | PROT_WRITE;
901 acc_mode = S_IRUGO | S_IWUGO;
902 f_mode = FMODE_READ | FMODE_WRITE;
904 if (shmflg & SHM_EXEC) {
910 * We cannot rely on the fs check since SYSV IPC does have an
911 * additional creator id...
913 ns = current->nsproxy->ipc_ns;
914 shp = shm_lock_check(ns, shmid);
921 if (ipcperms(&shp->shm_perm, acc_mode))
924 err = security_shm_shmat(shp, shmaddr, shmflg);
928 path.dentry = dget(shp->shm_file->f_path.dentry);
929 path.mnt = shp->shm_file->f_path.mnt;
931 size = i_size_read(path.dentry->d_inode);
935 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
941 file = alloc_file(path.mnt, path.dentry, f_mode, &shm_file_operations);
945 file->private_data = sfd;
946 file->f_mapping = shp->shm_file->f_mapping;
947 sfd->id = shp->shm_perm.id;
948 sfd->ns = get_ipc_ns(ns);
949 sfd->file = shp->shm_file;
952 down_write(¤t->mm->mmap_sem);
953 if (addr && !(shmflg & SHM_REMAP)) {
955 if (find_vma_intersection(current->mm, addr, addr + size))
958 * If shm segment goes below stack, make sure there is some
959 * space left for the stack to grow (at least 4 pages).
961 if (addr < current->mm->start_stack &&
962 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
966 user_addr = do_mmap (file, addr, size, prot, flags, 0);
969 if (IS_ERR_VALUE(user_addr))
970 err = (long)user_addr;
972 up_write(¤t->mm->mmap_sem);
977 mutex_lock(&shm_ids(ns).mutex);
978 shp = shm_lock(ns, shmid);
981 if(shp->shm_nattch == 0 &&
982 shp->shm_perm.mode & SHM_DEST)
983 shm_destroy(ns, shp);
986 mutex_unlock(&shm_ids(ns).mutex);
1002 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
1007 err = do_shmat(shmid, shmaddr, shmflg, &ret);
1010 force_successful_syscall_return();
1015 * detach and kill segment if marked destroyed.
1016 * The work is done in shm_close.
1018 asmlinkage long sys_shmdt(char __user *shmaddr)
1020 struct mm_struct *mm = current->mm;
1021 struct vm_area_struct *vma, *next;
1022 unsigned long addr = (unsigned long)shmaddr;
1024 int retval = -EINVAL;
1026 if (addr & ~PAGE_MASK)
1029 down_write(&mm->mmap_sem);
1032 * This function tries to be smart and unmap shm segments that
1033 * were modified by partial mlock or munmap calls:
1034 * - It first determines the size of the shm segment that should be
1035 * unmapped: It searches for a vma that is backed by shm and that
1036 * started at address shmaddr. It records it's size and then unmaps
1038 * - Then it unmaps all shm vmas that started at shmaddr and that
1039 * are within the initially determined size.
1040 * Errors from do_munmap are ignored: the function only fails if
1041 * it's called with invalid parameters or if it's called to unmap
1042 * a part of a vma. Both calls in this function are for full vmas,
1043 * the parameters are directly copied from the vma itself and always
1044 * valid - therefore do_munmap cannot fail. (famous last words?)
1047 * If it had been mremap()'d, the starting address would not
1048 * match the usual checks anyway. So assume all vma's are
1049 * above the starting address given.
1051 vma = find_vma(mm, addr);
1054 next = vma->vm_next;
1057 * Check if the starting address would match, i.e. it's
1058 * a fragment created by mprotect() and/or munmap(), or it
1059 * otherwise it starts at this address with no hassles.
1061 if ((vma->vm_ops == &shm_vm_ops) &&
1062 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1065 size = vma->vm_file->f_path.dentry->d_inode->i_size;
1066 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1068 * We discovered the size of the shm segment, so
1069 * break out of here and fall through to the next
1070 * loop that uses the size information to stop
1071 * searching for matching vma's.
1081 * We need look no further than the maximum address a fragment
1082 * could possibly have landed at. Also cast things to loff_t to
1083 * prevent overflows and make comparisions vs. equal-width types.
1085 size = PAGE_ALIGN(size);
1086 while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1087 next = vma->vm_next;
1089 /* finding a matching vma now does not alter retval */
1090 if ((vma->vm_ops == &shm_vm_ops) &&
1091 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1093 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1097 up_write(&mm->mmap_sem);
1101 #ifdef CONFIG_PROC_FS
1102 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1104 struct shmid_kernel *shp = it;
1107 #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1108 #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1110 if (sizeof(size_t) <= sizeof(int))
1111 format = SMALL_STRING;
1113 format = BIG_STRING;
1114 return seq_printf(s, format,