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* linux/ipc/shm.c
* Copyright (C) 1992, 1993 Krishna Balasubramanian
* Many improvements/fixes by Bruno Haible.
* Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
* Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
*
* /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
* BIGMEM support, Andrea Arcangeli <andrea@suse.de>
* SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
* HIGHMEM support, Ingo Molnar <mingo@redhat.com>
* avoid vmalloc and make shmmax, shmall, shmmni sysctl'able,
* Christoph Rohland <hans-christoph.rohland@sap.com>
*/
#include <linux/config.h>
#include <linux/malloc.h>
#include <linux/shm.h>
#include <linux/swap.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
#include <linux/highmem.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include "util.h"
struct shmid_kernel /* private to the kernel */
{
struct kern_ipc_perm shm_perm;
size_t shm_segsz;
time_t shm_atime;
time_t shm_dtime;
time_t shm_ctime;
pid_t shm_cpid;
pid_t shm_lpid;
unsigned long shm_nattch;
unsigned long shm_npages; /* size of segment (pages) */
pte_t **shm_dir; /* ptr to array of ptrs to frames -> SHMMAX */
struct vm_area_struct *attaches; /* descriptors for attaches */
int id; /* backreference to id for shm_close */
struct semaphore sem;
};
static struct ipc_ids shm_ids;
#define shm_lock(id) ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
#define shm_unlock(id) ipc_unlock(&shm_ids,id)
#define shm_lockall() ipc_lockall(&shm_ids)
#define shm_unlockall() ipc_unlockall(&shm_ids)
#define shm_get(id) ((struct shmid_kernel*)ipc_get(&shm_ids,id))
#define shm_rmid(id) ((struct shmid_kernel*)ipc_rmid(&shm_ids,id))
#define shm_checkid(s, id) \
ipc_checkid(&shm_ids,&s->shm_perm,id)
#define shm_buildid(id, seq) \
ipc_buildid(&shm_ids, id, seq)
static int newseg (key_t key, int shmflg, size_t size);
static int shm_map (struct vm_area_struct *shmd);
static void killseg (int shmid);
static void shm_open (struct vm_area_struct *shmd);
static void shm_close (struct vm_area_struct *shmd);
static struct page * shm_nopage(struct vm_area_struct *, unsigned long, int);
static int shm_swapout(struct page *, struct file *);
#ifdef CONFIG_PROC_FS
static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
#endif
size_t shm_ctlmax = SHMMAX;
int shm_ctlall = SHMALL;
int shm_ctlmni = SHMMNI;
static int shm_tot = 0; /* total number of shared memory pages */
static int shm_rss = 0; /* number of shared memory pages that are in memory */
static int shm_swp = 0; /* number of shared memory pages that are in swap */
/* locks order:
pagecache_lock
shm_lock()/shm_lockall()
kernel lock
shp->sem
sem_ids.sem
mmap_sem
SMP assumptions:
- swap_free() never sleeps
- add_to_swap_cache() never sleeps
- add_to_swap_cache() doesn't acquire the big kernel lock.
- shm_unuse() is called with the kernel lock acquired.
*/
/* some statistics */
static ulong swap_attempts = 0;
static ulong swap_successes = 0;
void __init shm_init (void)
{
ipc_init_ids(&shm_ids, shm_ctlmni);
#ifdef CONFIG_PROC_FS
create_proc_read_entry("sysvipc/shm", 0, 0, sysvipc_shm_read_proc, NULL);
#endif
return;
}
#define SHM_ENTRY(shp, index) (shp)->shm_dir[(index)/PTRS_PER_PTE][(index)%PTRS_PER_PTE]
static pte_t **shm_alloc(unsigned long pages)
{
unsigned short dir = pages / PTRS_PER_PTE;
unsigned short last = pages % PTRS_PER_PTE;
pte_t **ret, **ptr;
ret = kmalloc ((dir+1) * sizeof(pte_t *), GFP_KERNEL);
if (!ret)
goto out;
for (ptr = ret; ptr < ret+dir ; ptr++)
{
*ptr = (pte_t *)__get_free_page (GFP_KERNEL);
if (!*ptr)
goto free;
memset (*ptr, 0, PAGE_SIZE);
}
/* The last one is probably not of PAGE_SIZE: we use kmalloc */
if (last) {
*ptr = kmalloc (last*sizeof(pte_t), GFP_KERNEL);
if (!*ptr)
goto free;
memset (*ptr, 0, last*sizeof(pte_t));
}
out:
return ret;
free:
/* The last failed: we decrement first */
while (--ptr >= ret)
free_page ((unsigned long)*ptr);
kfree (ret);
return NULL;
}
static void shm_free(pte_t** dir, unsigned long pages)
{
pte_t **ptr = dir+pages/PTRS_PER_PTE;
/* first the last page */
if (pages%PTRS_PER_PTE)
kfree (*ptr);
/* now the whole pages */
while (--ptr >= dir)
free_page ((unsigned long)*ptr);
/* Now the indirect block */
kfree (dir);
}
static int shm_revalidate(struct shmid_kernel* shp, int shmid, int pagecount, int flg)
{
struct shmid_kernel* new;
new = shm_lock(shmid);
if(new==NULL) {
return -EIDRM;
}
if(new!=shp || shm_checkid(shp, shmid) || shp->shm_npages != pagecount) {
shm_unlock(shmid);
return -EIDRM;
}
if (ipcperms(&shp->shm_perm, flg)) {
shm_unlock(shmid);
return -EACCES;
}
return 0;
}
static int newseg (key_t key, int shmflg, size_t size)
{
struct shmid_kernel *shp;
int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
int id;
if (size < SHMMIN)
return -EINVAL;
if (size > shm_ctlmax)
return -EINVAL;
if (shm_tot + numpages >= shm_ctlall)
return -ENOSPC;
shp = (struct shmid_kernel *) kmalloc (sizeof (*shp), GFP_KERNEL);
if (!shp)
return -ENOMEM;
shp->shm_dir = shm_alloc (numpages);
if (!shp->shm_dir) {
kfree(shp);
return -ENOMEM;
}
id = ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
if(id == -1) {
shm_free(shp->shm_dir,numpages);
kfree(shp);
return -ENOSPC;
}
shp->shm_perm.key = key;
shp->shm_perm.mode = (shmflg & S_IRWXUGO);
shp->shm_segsz = size;
shp->shm_cpid = current->pid;
shp->attaches = NULL;
shp->shm_lpid = shp->shm_nattch = 0;
shp->shm_atime = shp->shm_dtime = 0;
shp->shm_ctime = CURRENT_TIME;
shp->shm_npages = numpages;
shp->id = shm_buildid(id,shp->shm_perm.seq);
init_MUTEX(&shp->sem);
shm_tot += numpages;
shm_unlock(id);
return shm_buildid(id,shp->shm_perm.seq);
}
asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
{
struct shmid_kernel *shp;
int err, id = 0;
down(&shm_ids.sem);
if (key == IPC_PRIVATE) {
err = newseg(key, shmflg, size);
} else if ((id = ipc_findkey(&shm_ids,key)) == -1) {
if (!(shmflg & IPC_CREAT))
err = -ENOENT;
else
err = newseg(key, shmflg, size);
} else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
err = -EEXIST;
} else {
shp = shm_lock(id);
if(shp==NULL)
BUG();
if (ipcperms(&shp->shm_perm, shmflg))
err = -EACCES;
else
err = shm_buildid(id, shp->shm_perm.seq);
shm_unlock(id);
}
up(&shm_ids.sem);
return err;
}
/*
* Only called after testing nattch and SHM_DEST.
* Here pages, pgtable and shmid_kernel are freed.
*/
static void killseg (int shmid)
{
struct shmid_kernel *shp;
int i, numpages;
int rss, swp;
down(&shm_ids.sem);
shp = shm_lock(shmid);
if(shp==NULL) {
out_up:
up(&shm_ids.sem);
return;
}
if(shm_checkid(shp,shmid) || shp->shm_nattch > 0 ||
!(shp->shm_perm.mode & SHM_DEST)) {
shm_unlock(shmid);
goto out_up;
}
shp = shm_rmid(shmid);
if(shp==NULL)
BUG();
if (!shp->shm_dir)
BUG();
shm_unlock(shmid);
up(&shm_ids.sem);
numpages = shp->shm_npages;
for (i = 0, rss = 0, swp = 0; i < numpages ; i++) {
pte_t pte;
pte = SHM_ENTRY (shp,i);
if (pte_none(pte))
continue;
if (pte_present(pte)) {
__free_page (pte_page(pte));
rss++;
} else {
swap_free(pte_to_swp_entry(pte));
swp++;
}
}
shm_free (shp->shm_dir, numpages);
kfree(shp);
shm_lockall();
shm_rss -= rss;
shm_swp -= swp;
shm_tot -= numpages;
shm_unlockall();
return;
}
static inline unsigned long copy_shmid_to_user(void *buf, struct shmid64_ds *in, int version)
{
switch(version) {
case IPC_64:
return copy_to_user(buf, in, sizeof(*in));
case IPC_OLD:
{
struct shmid_ds out;
ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
out.shm_segsz = in->shm_segsz;
out.shm_atime = in->shm_atime;
out.shm_dtime = in->shm_dtime;
out.shm_ctime = in->shm_ctime;
out.shm_cpid = in->shm_cpid;
out.shm_lpid = in->shm_lpid;
out.shm_nattch = in->shm_nattch;
return copy_to_user(buf, &out, sizeof(out));
}
default:
return -EINVAL;
}
}
struct shm_setbuf {
uid_t uid;
gid_t gid;
mode_t mode;
};
static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void *buf, int version)
{
switch(version) {
case IPC_64:
{
struct shmid64_ds tbuf;
if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
return -EFAULT;
out->uid = tbuf.shm_perm.uid;
out->gid = tbuf.shm_perm.gid;
out->mode = tbuf.shm_perm.mode;
return 0;
}
case IPC_OLD:
{
struct shmid_ds tbuf_old;
if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
return -EFAULT;
out->uid = tbuf_old.shm_perm.uid;
out->gid = tbuf_old.shm_perm.gid;
out->mode = tbuf_old.shm_perm.mode;
return 0;
}
default:
return -EINVAL;
}
}
static inline unsigned long copy_shminfo_to_user(void *buf, struct shminfo64 *in, int version)
{
switch(version) {
case IPC_64:
return copy_to_user(buf, in, sizeof(*in));
case IPC_OLD:
{
struct shminfo out;
if(in->shmmax > INT_MAX)
out.shmmax = INT_MAX;
else
out.shmmax = (int)in->shmmax;
out.shmmin = in->shmmin;
out.shmmni = in->shmmni;
out.shmseg = in->shmseg;
out.shmall = in->shmall;
return copy_to_user(buf, &out, sizeof(out));
}
default:
return -EINVAL;
}
}
asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds *buf)
{
struct shm_setbuf setbuf;
struct shmid_kernel *shp;
int err, version;
if (cmd < 0 || shmid < 0)
return -EINVAL;
version = ipc_parse_version(&cmd);
switch (cmd) { /* replace with proc interface ? */
case IPC_INFO:
{
struct shminfo64 shminfo;
memset(&shminfo,0,sizeof(shminfo));
shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
shminfo.shmmax = shm_ctlmax;
shminfo.shmall = shm_ctlall;
shminfo.shmmin = SHMMIN;
if(copy_shminfo_to_user (buf, &shminfo, version))
return -EFAULT;
/* reading a integer is always atomic */
err= shm_ids.max_id;
if(err<0)
err = 0;
return err;
}
case SHM_INFO:
{
struct shm_info shm_info;
memset(&shm_info,0,sizeof(shm_info));
shm_lockall();
shm_info.used_ids = shm_ids.in_use;
shm_info.shm_rss = shm_rss;
shm_info.shm_tot = shm_tot;
shm_info.shm_swp = shm_swp;
shm_info.swap_attempts = swap_attempts;
shm_info.swap_successes = swap_successes;
err = shm_ids.max_id;
shm_unlockall();
if(copy_to_user (buf, &shm_info, sizeof(shm_info)))
return -EFAULT;
return err < 0 ? 0 : err;
}
case SHM_STAT:
case IPC_STAT:
{
struct shmid64_ds tbuf;
int result;
memset(&tbuf, 0, sizeof(tbuf));
shp = shm_lock(shmid);
if(shp==NULL)
return -EINVAL;
if(cmd==SHM_STAT) {
err = -EINVAL;
if (shmid > shm_ids.max_id)
goto out_unlock;
result = shm_buildid(shmid, shp->shm_perm.seq);
} else {
err = -EIDRM;
if(shm_checkid(shp,shmid))
goto out_unlock;
result = 0;
}
err=-EACCES;
if (ipcperms (&shp->shm_perm, S_IRUGO))
goto out_unlock;
kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
tbuf.shm_segsz = shp->shm_segsz;
tbuf.shm_atime = shp->shm_atime;
tbuf.shm_dtime = shp->shm_dtime;
tbuf.shm_ctime = shp->shm_ctime;
tbuf.shm_cpid = shp->shm_cpid;
tbuf.shm_lpid = shp->shm_lpid;
tbuf.shm_nattch = shp->shm_nattch;
shm_unlock(shmid);
if(copy_shmid_to_user (buf, &tbuf, version))
return -EFAULT;
return result;
}
case SHM_LOCK:
case SHM_UNLOCK:
{
/* Allow superuser to lock segment in memory */
/* Should the pages be faulted in here or leave it to user? */
/* need to determine interaction with current->swappable */
struct kern_ipc_perm *ipcp;
if (!capable(CAP_IPC_LOCK))
return -EPERM;
shp = shm_lock(shmid);
if(shp==NULL)
return -EINVAL;
err=-EIDRM;
if(shm_checkid(shp,shmid))
goto out_unlock;
ipcp = &shp->shm_perm;
if(cmd==SHM_LOCK) {
if (!(ipcp->mode & SHM_LOCKED)) {
ipcp->mode |= SHM_LOCKED;
err = 0;
}
} else {
if (ipcp->mode & SHM_LOCKED) {
ipcp->mode &= ~SHM_LOCKED;
err = 0;
}
}
shm_unlock(shmid);
return err;
}
case IPC_RMID:
case IPC_SET:
break;
default:
return -EINVAL;
}
if (cmd == IPC_SET) {
if(copy_shmid_from_user (&setbuf, buf, version))
return -EFAULT;
}
down(&shm_ids.sem);
shp = shm_lock(shmid);
err=-EINVAL;
if(shp==NULL)
goto out_up;
err=-EIDRM;
if(shm_checkid(shp,shmid))
goto out_unlock_up;
err=-EPERM;
if (current->euid != shp->shm_perm.uid &&
current->euid != shp->shm_perm.cuid &&
!capable(CAP_SYS_ADMIN)) {
goto out_unlock_up;
}
switch (cmd) {
case IPC_SET:
shp->shm_perm.uid = setbuf.uid;
shp->shm_perm.gid = setbuf.gid;
shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
| (setbuf.mode & S_IRWXUGO);
shp->shm_ctime = CURRENT_TIME;
break;
case IPC_RMID:
shp->shm_perm.mode |= SHM_DEST;
if (shp->shm_nattch <= 0) {
shm_unlock(shmid);
up(&shm_ids.sem);
killseg (shmid);
return 0;
}
}
err = 0;
out_unlock_up:
shm_unlock(shmid);
out_up:
up(&shm_ids.sem);
return err;
out_unlock:
shm_unlock(shmid);
return err;
}
/*
* The per process internal structure for managing segments is
* `struct vm_area_struct'.
* A shmat will add to and shmdt will remove from the list.
* shmd->vm_mm the attacher
* shmd->vm_start virt addr of attach, multiple of SHMLBA
* shmd->vm_end multiple of SHMLBA
* shmd->vm_next next attach for task
* shmd->vm_next_share next attach for segment
* shmd->vm_pgoff offset into segment (in pages)
* shmd->vm_private_data signature for this attach
*/
static struct vm_operations_struct shm_vm_ops = {
shm_open, /* open - callback for a new vm-area open */
shm_close, /* close - callback for when the vm-area is released */
NULL, /* no need to sync pages at unmap */
NULL, /* protect */
NULL, /* sync */
NULL, /* advise */
shm_nopage, /* nopage */
NULL, /* wppage */
shm_swapout /* swapout */
};
/* Insert shmd into the list shp->attaches */
static inline void insert_attach (struct shmid_kernel * shp, struct vm_area_struct * shmd)
{
if((shmd->vm_next_share = shp->attaches) != NULL)
shp->attaches->vm_pprev_share = &shmd->vm_next_share;
shp->attaches = shmd;
shmd->vm_pprev_share = &shp->attaches;
}
/* Remove shmd from list shp->attaches */
static inline void remove_attach (struct shmid_kernel * shp, struct vm_area_struct * shmd)
{
if(shmd->vm_next_share)
shmd->vm_next_share->vm_pprev_share = shmd->vm_pprev_share;
*shmd->vm_pprev_share = shmd->vm_next_share;
}
/*
* ensure page tables exist
* mark page table entries with shm_sgn.
*/
static int shm_map (struct vm_area_struct *shmd)
{
unsigned long tmp;
/* clear old mappings */
do_munmap(shmd->vm_start, shmd->vm_end - shmd->vm_start);
/* add new mapping */
tmp = shmd->vm_end - shmd->vm_start;
if((current->mm->total_vm << PAGE_SHIFT) + tmp
> (unsigned long) current->rlim[RLIMIT_AS].rlim_cur)
return -ENOMEM;
current->mm->total_vm += tmp >> PAGE_SHIFT;
vmlist_modify_lock(current->mm);
insert_vm_struct(current->mm, shmd);
merge_segments(current->mm, shmd->vm_start, shmd->vm_end);
vmlist_modify_unlock(current->mm);
return 0;
}
/*
* Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
*/
asmlinkage long sys_shmat (int shmid, char *shmaddr, int shmflg, ulong *raddr)
{
struct shmid_kernel *shp;
struct vm_area_struct *shmd;
int err;
unsigned long addr;
unsigned long len;
short flg = shmflg & SHM_RDONLY ? S_IRUGO : S_IRUGO|S_IWUGO;
if (shmid < 0)
return -EINVAL;
down(¤t->mm->mmap_sem);
err = -EINVAL;
shp = shm_lock(shmid);
if (!shp)
goto out_up;
err = -EACCES;
if (ipcperms(&shp->shm_perm, flg))
goto out_unlock_up;
err = -EIDRM;
if (shm_checkid(shp,shmid))
goto out_unlock_up;
if (!(addr = (ulong) shmaddr)) {
if (shmflg & SHM_REMAP)
goto out_unlock_up;
err = -ENOMEM;
addr = 0;
again:
if (!(addr = get_unmapped_area(addr, (unsigned long)shp->shm_segsz)))
goto out_unlock_up;
if(addr & (SHMLBA - 1)) {
addr = (addr + (SHMLBA - 1)) & ~(SHMLBA - 1);
goto again;
}
} else if (addr & (SHMLBA-1)) {
err=-EINVAL;
if (shmflg & SHM_RND)
addr &= ~(SHMLBA-1); /* round down */
else
goto out_unlock_up;
}
/*
* Check if addr exceeds TASK_SIZE (from do_mmap)
*/
len = PAGE_SIZE*shp->shm_npages;
err = -EINVAL;
if (addr >= TASK_SIZE || len > TASK_SIZE || addr > TASK_SIZE - len)
goto out_unlock_up;
/*
* If shm segment goes below stack, make sure there is some
* space left for the stack to grow (presently 4 pages).
*/
if (addr < current->mm->start_stack &&
addr > current->mm->start_stack - PAGE_SIZE*(shp->shm_npages + 4))
goto out_unlock_up;
if (!(shmflg & SHM_REMAP) && find_vma_intersection(current->mm, addr, addr + (unsigned long)shp->shm_segsz))
goto out_unlock_up;
shm_unlock(shmid);
err = -ENOMEM;
shmd = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
err = shm_revalidate(shp, shmid, len/PAGE_SIZE,flg);
if(err) {
kmem_cache_free(vm_area_cachep, shmd);
goto out_up;
}
shmd->vm_private_data = shp;
shmd->vm_start = addr;
shmd->vm_end = addr + shp->shm_npages * PAGE_SIZE;
shmd->vm_mm = current->mm;
shmd->vm_page_prot = (shmflg & SHM_RDONLY) ? PAGE_READONLY : PAGE_SHARED;
shmd->vm_flags = VM_SHM | VM_MAYSHARE | VM_SHARED
| VM_MAYREAD | VM_MAYEXEC | VM_READ | VM_EXEC
| ((shmflg & SHM_RDONLY) ? 0 : VM_MAYWRITE | VM_WRITE);
shmd->vm_file = NULL;
shmd->vm_pgoff = 0;
shmd->vm_ops = &shm_vm_ops;
shp->shm_nattch++; /* prevent destruction */
shm_unlock(shp->id);
err = shm_map (shmd);
shm_lock(shmid); /* cannot fail */
if (err)
goto failed_shm_map;
insert_attach(shp,shmd); /* insert shmd into shp->attaches */
shp->shm_lpid = current->pid;
shp->shm_atime = CURRENT_TIME;
*raddr = addr;
err = 0;
out_unlock_up:
shm_unlock(shmid);
out_up:
up(¤t->mm->mmap_sem);
return err;
failed_shm_map:
{
int delete = 0;
if (--shp->shm_nattch <= 0 && shp->shm_perm.mode & SHM_DEST)
delete = 1;
shm_unlock(shmid);
up(¤t->mm->mmap_sem);
kmem_cache_free(vm_area_cachep, shmd);
if(delete)
killseg(shmid);
return err;
}
}
/* This is called by fork, once for every shm attach. */
static void shm_open (struct vm_area_struct *shmd)
{
struct shmid_kernel *shp;
shp = (struct shmid_kernel *) shmd->vm_private_data;
if(shp != shm_lock(shp->id))
BUG();
insert_attach(shp,shmd); /* insert shmd into shp->attaches */
shp->shm_nattch++;
shp->shm_atime = CURRENT_TIME;
shp->shm_lpid = current->pid;
shm_unlock(shp->id);
}
/*
* remove the attach descriptor shmd.
* free memory for segment if it is marked destroyed.
* The descriptor has already been removed from the current->mm->mmap list
* and will later be kfree()d.
*/
static void shm_close (struct vm_area_struct *shmd)
{
struct shmid_kernel *shp;
int id;
/* remove from the list of attaches of the shm segment */
shp = (struct shmid_kernel *) shmd->vm_private_data;
if(shp != shm_lock(shp->id))
BUG();
remove_attach(shp,shmd); /* remove from shp->attaches */
shp->shm_lpid = current->pid;
shp->shm_dtime = CURRENT_TIME;
id=-1;
if (--shp->shm_nattch <= 0 && shp->shm_perm.mode & SHM_DEST)
id=shp->id;
shm_unlock(shp->id);
if(id!=-1)
killseg(id);
}
/*
* detach and kill segment if marked destroyed.
* The work is done in shm_close.
*/
asmlinkage long sys_shmdt (char *shmaddr)
{
struct vm_area_struct *shmd, *shmdnext;
down(¤t->mm->mmap_sem);
for (shmd = current->mm->mmap; shmd; shmd = shmdnext) {
shmdnext = shmd->vm_next;
if (shmd->vm_ops == &shm_vm_ops
&& shmd->vm_start - (shmd->vm_pgoff << PAGE_SHIFT) == (ulong) shmaddr)
do_munmap(shmd->vm_start, shmd->vm_end - shmd->vm_start);
}
up(¤t->mm->mmap_sem);
return 0;
}
/*
* Enter the shm page into the SHM data structures.
*
* The way "nopage" is done, we don't actually have to
* do anything here: nopage will have filled in the shm
* data structures already, and shm_swap_out() will just
* work off them..
*/
static int shm_swapout(struct page * page, struct file *file)
{
return 0;
}
/*
* page not present ... go through shm_dir
*/
static struct page * shm_nopage(struct vm_area_struct * shmd, unsigned long address, int no_share)
{
pte_t pte;
struct shmid_kernel *shp;
unsigned int idx;
struct page * page;
shp = (struct shmid_kernel *) shmd->vm_private_data;
idx = (address - shmd->vm_start) >> PAGE_SHIFT;
idx += shmd->vm_pgoff;
down(&shp->sem);
if(shp != shm_lock(shp->id))
BUG();
pte = SHM_ENTRY(shp,idx);
if (!pte_present(pte)) {
/* page not present so shm_swap can't race with us
and the semaphore protects us by other tasks that
could potentially fault on our pte under us */
if (pte_none(pte)) {
shm_unlock(shp->id);
page = alloc_page(GFP_HIGHUSER);
if (!page)
goto oom;
clear_highpage(page);
if(shp != shm_lock(shp->id))
BUG();
} else {
swp_entry_t entry = pte_to_swp_entry(pte);
shm_unlock(shp->id);
page = lookup_swap_cache(entry);
if (!page) {
lock_kernel();
swapin_readahead(entry);
page = read_swap_cache(entry);
unlock_kernel();
if (!page)
goto oom;
}
delete_from_swap_cache(page);
page = replace_with_highmem(page);
swap_free(entry);
if(shp != shm_lock(shp->id))
BUG();
shm_swp--;
}
shm_rss++;
pte = pte_mkdirty(mk_pte(page, PAGE_SHARED));
SHM_ENTRY(shp, idx) = pte;
} else
--current->maj_flt; /* was incremented in do_no_page */
/* pte_val(pte) == SHM_ENTRY (shp, idx) */
get_page(pte_page(pte));
shm_unlock(shp->id);
up(&shp->sem);
current->min_flt++;
return pte_page(pte);
oom:
up(&shp->sem);
return NOPAGE_OOM;
}
/*
* Goes through counter = (shm_rss >> prio) present shm pages.
*/
static unsigned long swap_id = 0; /* currently being swapped */
static unsigned long swap_idx = 0; /* next to swap */
int shm_swap (int prio, int gfp_mask, zone_t *zone)
{
pte_t page;
struct shmid_kernel *shp;
swp_entry_t swap_entry;
unsigned long id, idx;
int loop = 0;
int counter;
struct page * page_map;
counter = shm_rss >> prio;
if (!counter)
return 0;
lock_kernel();
/* subtle: preload the swap count for the swap cache. We can't
increase the count inside the critical section as we can't release
the shm_lock there. And we can't acquire the big lock with the
shm_lock held (otherwise we would deadlock too easily). */
swap_entry = __get_swap_page(2);
if (!swap_entry.val) {
unlock_kernel();
return 0;
}
unlock_kernel();
shm_lockall();
check_id:
shp = shm_get(swap_id);
if(shp==NULL || shp->shm_perm.mode & SHM_LOCKED) {
next_id:
swap_idx = 0;
if (++swap_id > shm_ids.max_id) {
swap_id = 0;
if (loop)
goto failed;
loop = 1;
}
goto check_id;
}
id = swap_id;
check_table:
idx = swap_idx++;
if (idx >= shp->shm_npages)
goto next_id;
page = SHM_ENTRY(shp, idx);
if (!pte_present(page))
goto check_table;
page_map = pte_page(page);
if (zone && (!memclass(page_map->zone, zone)))
goto check_table;
swap_attempts++;
if (--counter < 0) { /* failed */
failed:
shm_unlockall();
__swap_free(swap_entry, 2);
return 0;
}
if (page_count(page_map) != 1)
goto check_table;
if (!(page_map = prepare_highmem_swapout(page_map)))
goto failed;
SHM_ENTRY (shp, idx) = swp_entry_to_pte(swap_entry);
swap_successes++;
shm_swp++;
shm_rss--;
/* add the locked page to the swap cache before allowing
the swapin path to run lookup_swap_cache(). This avoids
reading a not yet uptodate block from disk.
NOTE: we just accounted the swap space reference for this
swap cache page at __get_swap_page() time. */
add_to_swap_cache(page_map, swap_entry);
shm_unlockall();
lock_kernel();
rw_swap_page(WRITE, page_map, 0);
unlock_kernel();
__free_page(page_map);
return 1;
}
/*
* Free the swap entry and set the new pte for the shm page.
*/
static void shm_unuse_page(struct shmid_kernel *shp, unsigned long idx,
swp_entry_t entry, struct page *page)
{
pte_t pte;
pte = pte_mkdirty(mk_pte(page, PAGE_SHARED));
SHM_ENTRY(shp, idx) = pte;
get_page(page);
shm_rss++;
shm_swp--;
swap_free(entry);
}
/*
* unuse_shm() search for an eventually swapped out shm page.
*/
void shm_unuse(swp_entry_t entry, struct page *page)
{
int i, n;
shm_lockall();
for (i = 0; i <= shm_ids.max_id; i++) {
struct shmid_kernel *shp = shm_get(i);
if(shp==NULL)
continue;
for (n = 0; n < shp->shm_npages; n++) {
if (pte_none(SHM_ENTRY(shp,n)))
continue;
if (pte_present(SHM_ENTRY(shp,n)))
continue;
if (pte_to_swp_entry(SHM_ENTRY(shp,n)).val == entry.val) {
shm_unuse_page(shp, n, entry, page);
goto out;
}
}
}
out:
shm_unlockall();
}
#ifdef CONFIG_PROC_FS
static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
{
off_t pos = 0;
off_t begin = 0;
int i, len = 0;
down(&shm_ids.sem);
len += sprintf(buffer, " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n");
for(i = 0; i <= shm_ids.max_id; i++) {
struct shmid_kernel* shp = shm_lock(i);
if(shp!=NULL) {
#define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
#define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
char *format;
if (sizeof(size_t) <= sizeof(int))
format = SMALL_STRING;
else
format = BIG_STRING;
len += sprintf(buffer + len, format,
shp->shm_perm.key,
shm_buildid(i, shp->shm_perm.seq),
shp->shm_perm.mode,
shp->shm_segsz,
shp->shm_cpid,
shp->shm_lpid,
shp->shm_nattch,
shp->shm_perm.uid,
shp->shm_perm.gid,
shp->shm_perm.cuid,
shp->shm_perm.cgid,
shp->shm_atime,
shp->shm_dtime,
shp->shm_ctime);
shm_unlock(i);
pos += len;
if(pos < offset) {
len = 0;
begin = pos;
}
if(pos > offset + length)
goto done;
}
}
*eof = 1;
done:
up(&shm_ids.sem);
*start = buffer + (offset - begin);
len -= (offset - begin);
if(len > length)
len = length;
if(len < 0)
len = 0;
return len;
}
#endif
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