BSD 4_4_Lite1 release

[unix-history] / usr / src / sys / vm / device_pager.c

/*
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991, 1993
*      The Regents of the University of California.  All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*      @(#)device_pager.c      8.5 (Berkeley) 1/12/94
*/

/*
* Page to/from special files.
*/

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/mman.h>
#include <sys/malloc.h>

#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/device_pager.h>

struct pagerlst dev_pager_list;         /* list of managed devices */
struct pglist   dev_pager_fakelist;     /* list of available vm_page_t's */

#ifdef DEBUG
int     dpagerdebug = 0;
#define DDB_FOLLOW      0x01
#define DDB_INIT        0x02
#define DDB_ALLOC       0x04
#define DDB_FAIL        0x08
#endif

static vm_pager_t        dev_pager_alloc
                           __P((caddr_t, vm_size_t, vm_prot_t, vm_offset_t));
static void              dev_pager_dealloc __P((vm_pager_t));
static int               dev_pager_getpage
                           __P((vm_pager_t, vm_page_t *, int, boolean_t));
static boolean_t         dev_pager_haspage __P((vm_pager_t, vm_offset_t));
static void              dev_pager_init __P((void));
static int               dev_pager_putpage
                           __P((vm_pager_t, vm_page_t *, int, boolean_t));
static vm_page_t         dev_pager_getfake __P((vm_offset_t));
static void              dev_pager_putfake __P((vm_page_t));

struct pagerops devicepagerops = {
       dev_pager_init,
       dev_pager_alloc,
       dev_pager_dealloc,
       dev_pager_getpage,
       dev_pager_putpage,
       dev_pager_haspage,
       vm_pager_clusternull
};

static void
dev_pager_init()
{
#ifdef DEBUG
       if (dpagerdebug & DDB_FOLLOW)
               printf("dev_pager_init()\n");
#endif
       TAILQ_INIT(&dev_pager_list);
       TAILQ_INIT(&dev_pager_fakelist);
}

static vm_pager_t
dev_pager_alloc(handle, size, prot, foff)
       caddr_t handle;
       vm_size_t size;
       vm_prot_t prot;
       vm_offset_t foff;
{
       dev_t dev;
       vm_pager_t pager;
       int (*mapfunc)();
       vm_object_t object;
       dev_pager_t devp;
       int npages, off;

#ifdef DEBUG
       if (dpagerdebug & DDB_FOLLOW)
               printf("dev_pager_alloc(%x, %x, %x, %x)\n",
                      handle, size, prot, foff);
#endif
#ifdef DIAGNOSTIC
       /*
        * Pageout to device, should never happen.
        */
       if (handle == NULL)
               panic("dev_pager_alloc called");
#endif

       /*
        * Make sure this device can be mapped.
        */
       dev = (dev_t)handle;
       mapfunc = cdevsw[major(dev)].d_mmap;
       if (mapfunc == NULL || mapfunc == enodev || mapfunc == nullop)
               return(NULL);

       /*
        * Offset should be page aligned.
        */
       if (foff & PAGE_MASK)
               return(NULL);

       /*
        * Check that the specified range of the device allows the
        * desired protection.
        *
        * XXX assumes VM_PROT_* == PROT_*
        */
       npages = atop(round_page(size));
       for (off = foff; npages--; off += PAGE_SIZE)
               if ((*mapfunc)(dev, off, (int)prot) == -1)
                       return(NULL);

       /*
        * Look up pager, creating as necessary.
        */
top:
       pager = vm_pager_lookup(&dev_pager_list, handle);
       if (pager == NULL) {
               /*
                * Allocate and initialize pager structs
                */
               pager = (vm_pager_t)malloc(sizeof *pager, M_VMPAGER, M_WAITOK);
               if (pager == NULL)
                       return(NULL);
               devp = (dev_pager_t)malloc(sizeof *devp, M_VMPGDATA, M_WAITOK);
               if (devp == NULL) {
                       free((caddr_t)pager, M_VMPAGER);
                       return(NULL);
               }
               pager->pg_handle = handle;
               pager->pg_ops = &devicepagerops;
               pager->pg_type = PG_DEVICE;
               pager->pg_flags = 0;
               pager->pg_data = devp;
               TAILQ_INIT(&devp->devp_pglist);
               /*
                * Allocate object and associate it with the pager.
                */
               object = devp->devp_object = vm_object_allocate(0);
               vm_object_enter(object, pager);
               vm_object_setpager(object, pager, (vm_offset_t)0, FALSE);
               /*
                * Finally, put it on the managed list so other can find it.
                * First we re-lookup in case someone else beat us to this
                * point (due to blocking in the various mallocs).  If so,
                * we free everything and start over.
                */
               if (vm_pager_lookup(&dev_pager_list, handle)) {
                       free((caddr_t)devp, M_VMPGDATA);
                       free((caddr_t)pager, M_VMPAGER);
                       goto top;
               }
               TAILQ_INSERT_TAIL(&dev_pager_list, pager, pg_list);
#ifdef DEBUG
               if (dpagerdebug & DDB_ALLOC) {
                       printf("dev_pager_alloc: pager %x devp %x object %x\n",
                              pager, devp, object);
                       vm_object_print(object, FALSE);
               }
#endif
       } else {
               /*
                * vm_object_lookup() gains a reference and also
                * removes the object from the cache.
                */
               object = vm_object_lookup(pager);
#ifdef DIAGNOSTIC
               devp = (dev_pager_t)pager->pg_data;
               if (object != devp->devp_object)
                       panic("dev_pager_setup: bad object");
#endif
       }
       return(pager);
}

static void
dev_pager_dealloc(pager)
       vm_pager_t pager;
{
       dev_pager_t devp;
       vm_object_t object;
       vm_page_t m;

#ifdef DEBUG
       if (dpagerdebug & DDB_FOLLOW)
               printf("dev_pager_dealloc(%x)\n", pager);
#endif
       TAILQ_REMOVE(&dev_pager_list, pager, pg_list);
       /*
        * Get the object.
        * Note: cannot use vm_object_lookup since object has already
        * been removed from the hash chain.
        */
       devp = (dev_pager_t)pager->pg_data;
       object = devp->devp_object;
#ifdef DEBUG
       if (dpagerdebug & DDB_ALLOC)
               printf("dev_pager_dealloc: devp %x object %x\n", devp, object);
#endif
       /*
        * Free up our fake pages.
        */
       while ((m = devp->devp_pglist.tqh_first) != NULL) {
               TAILQ_REMOVE(&devp->devp_pglist, m, pageq);
               dev_pager_putfake(m);
       }
       free((caddr_t)devp, M_VMPGDATA);
       free((caddr_t)pager, M_VMPAGER);
}

static int
dev_pager_getpage(pager, mlist, npages, sync)
       vm_pager_t pager;
       vm_page_t *mlist;
       int npages;
       boolean_t sync;
{
       register vm_object_t object;
       vm_offset_t offset, paddr;
       vm_page_t page;
       dev_t dev;
       int (*mapfunc)(), prot;
       vm_page_t m;

#ifdef DEBUG
       if (dpagerdebug & DDB_FOLLOW)
               printf("dev_pager_getpage(%x, %x, %x, %x)\n",
                      pager, mlist, npages, sync);
#endif

       if (npages != 1)
               panic("dev_pager_getpage: cannot handle multiple pages");
       m = *mlist;

       object = m->object;
       dev = (dev_t)pager->pg_handle;
       offset = m->offset + object->paging_offset;
       prot = PROT_READ;       /* XXX should pass in? */
       mapfunc = cdevsw[major(dev)].d_mmap;
#ifdef DIAGNOSTIC
       if (mapfunc == NULL || mapfunc == enodev || mapfunc == nullop)
               panic("dev_pager_getpage: no map function");
#endif
       paddr = pmap_phys_address((*mapfunc)(dev, (int)offset, prot));
#ifdef DIAGNOSTIC
       if (paddr == -1)
               panic("dev_pager_getpage: map function returns error");
#endif
       /*
        * Replace the passed in page with our own fake page and free
        * up the original.
        */
       page = dev_pager_getfake(paddr);
       TAILQ_INSERT_TAIL(&((dev_pager_t)pager->pg_data)->devp_pglist, page,
           pageq);
       vm_object_lock(object);
       vm_page_lock_queues();
       vm_page_free(m);
       vm_page_insert(page, object, offset);
       vm_page_unlock_queues();
       PAGE_WAKEUP(m);
       if (offset + PAGE_SIZE > object->size)
               object->size = offset + PAGE_SIZE;      /* XXX anal */
       vm_object_unlock(object);

       return(VM_PAGER_OK);
}

static int
dev_pager_putpage(pager, mlist, npages, sync)
       vm_pager_t pager;
       vm_page_t *mlist;
       int npages;
       boolean_t sync;
{
#ifdef DEBUG
       if (dpagerdebug & DDB_FOLLOW)
               printf("dev_pager_putpage(%x, %x, %x, %x)\n",
                      pager, mlist, npages, sync);
#endif
       if (pager == NULL)
               return;
       panic("dev_pager_putpage called");
}

static boolean_t
dev_pager_haspage(pager, offset)
       vm_pager_t pager;
       vm_offset_t offset;
{
#ifdef DEBUG
       if (dpagerdebug & DDB_FOLLOW)
               printf("dev_pager_haspage(%x, %x)\n", pager, offset);
#endif
       return(TRUE);
}

static vm_page_t
dev_pager_getfake(paddr)
       vm_offset_t paddr;
{
       vm_page_t m;
       int i;

       if (dev_pager_fakelist.tqh_first == NULL) {
               m = (vm_page_t)malloc(PAGE_SIZE, M_VMPGDATA, M_WAITOK);
               for (i = PAGE_SIZE / sizeof(*m); i > 0; i--) {
                       TAILQ_INSERT_TAIL(&dev_pager_fakelist, m, pageq);
                       m++;
               }
       }
       m = dev_pager_fakelist.tqh_first;
       TAILQ_REMOVE(&dev_pager_fakelist, m, pageq);
       m->flags = PG_BUSY | PG_CLEAN | PG_FAKE | PG_FICTITIOUS;
       m->phys_addr = paddr;
       m->wire_count = 1;
       return(m);
}

static void
dev_pager_putfake(m)
       vm_page_t m;
{
#ifdef DIAGNOSTIC
       if (!(m->flags & PG_FICTITIOUS))
               panic("dev_pager_putfake: bad page");
#endif
       TAILQ_INSERT_TAIL(&dev_pager_fakelist, m, pageq);
}