sys/uvm/uvm_device.c

/*	$Id: uvm_device.c,v 1.1 1998/02/05 06:25:10 mrg Exp $	*/

/*
 * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
 *	   >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
 */
/*
 *
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * All rights reserved.
 *
 * 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 Charles D. Cranor and
 *      Washington University.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/*
 * uvm_device.c: the device pager.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/mount.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>

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

#include <sys/syscallargs.h>

#include <uvm/uvm.h>
#include <uvm/uvm_device.h>

UVMHIST_DECL(maphist);

/*
 * private global data structure
 *
 * we keep a list of active device objects in the system.
 */

LIST_HEAD(udv_list_struct, uvm_device);
static struct udv_list_struct udv_list;
#if NCPU > 1
static simple_lock_data_t udv_lock;
#endif

/*
 * functions
 */

static void		udv_init __P((void));
struct uvm_object 	*udv_attach __P((void *, vm_prot_t));
static void             udv_reference __P((struct uvm_object *));
static void             udv_detach __P((struct uvm_object *));
static int		udv_fault __P((struct uvm_faultinfo *, vm_offset_t,
				       vm_page_t *, int, int, vm_fault_t,
				       vm_prot_t, int));
static boolean_t        udv_flush __P((struct uvm_object *, vm_offset_t,
					 vm_offset_t, int));
static int		udv_asyncget __P((struct uvm_object *, vm_offset_t,
					    int));
static int		udv_put __P((struct uvm_object *, vm_page_t *,
					int, boolean_t));

/*
 * master pager structure
 */

struct uvm_pagerops uvm_deviceops = {
  udv_init,
  udv_attach,
  udv_reference,
  udv_detach,
  udv_fault,
  udv_flush,
  NULL,			/* no get function since we have udv_fault */
  udv_asyncget,
  udv_put,
  NULL,			/* no cluster function */
  NULL,			/* no put cluster function */
  NULL,			/* no share protect.   no share maps for us */
  NULL,			/* no AIO-DONE function since no async i/o */
  NULL,			/* no releasepg function since no normal pages */
};

/*
 * the ops!
 */

/*
 * udv_init
 *
 * init pager private data structures.
 */

void udv_init()

{
  LIST_INIT(&udv_list);
  simple_lock_init(&udv_lock);
}

/*
 * udv_attach
 *
 * get a VM object that is associated with a device.   allocate a new
 * one if needed.
 *
 * => caller must _not_ already be holding the lock on the uvm_object.
 * => in fact, nothing should be locked so that we can sleep here.
 */

struct uvm_object *udv_attach(arg, accessprot)

void *arg;
vm_prot_t accessprot;

{
  dev_t device = *((dev_t *) arg);
  struct uvm_device *udv, *lcv;
  int (*mapfn) __P((dev_t, int, int));
  UVMHIST_FUNC("udv_attach"); UVMHIST_CALLED(maphist);

  UVMHIST_LOG(maphist, "(device=0x%x)", device,0,0,0);

  /*
   * before we do anything, ensure this device supports mmap
   */

  mapfn = cdevsw[major(device)].d_mmap;
  if (mapfn == NULL ||
      mapfn == (int (*) __P((dev_t, int, int))) enodev ||
      mapfn == (int (*) __P((dev_t, int, int))) nullop)
    return(NULL);

  /*
   * keep looping until we get it
   */

  while (1) {

    /*
     * first, attempt to find it on the main list
     */

    simple_lock(&udv_lock);
    for (lcv = udv_list.lh_first ; lcv != NULL ; lcv = lcv->u_list.le_next) {
      if (device == lcv->u_device)
	break;
    }

    /*
     * got it on main list.  put a hold on it and unlock udv_lock.
     */

    if (lcv) {

      /*
       * if someone else has a hold on it, sleep and start over again.
       */

      if (lcv->u_flags & UVM_DEVICE_HOLD) {
	lcv->u_flags |= UVM_DEVICE_WANTED;
	UVM_UNLOCK_AND_WAIT(lcv, &udv_lock, FALSE, "udv_attach",0);
	continue;
      }

      lcv->u_flags |= UVM_DEVICE_HOLD;	/* we are now holding it */
      simple_unlock(&udv_lock);

      /*
       * bump reference count, unhold, return.
       */

      simple_lock(&lcv->u_obj.vmobjlock);
      lcv->u_obj.uo_refs++;
      simple_unlock(&lcv->u_obj.vmobjlock);

      simple_lock(&udv_lock);
      if (lcv->u_flags & UVM_DEVICE_WANTED)
	wakeup(lcv);
      lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD);
      simple_unlock(&udv_lock);
      return(&lcv->u_obj);
    }

    /*
     * did not find it on main list.   need to malloc a new one.
     */

    simple_unlock(&udv_lock);
    /* NOTE: we could sleep in the following malloc() */
    MALLOC(udv, struct uvm_device *, sizeof(*udv), M_TEMP, M_WAITOK);
    simple_lock(&udv_lock);

    /*
     * now we have to double check to make sure no one added it to the
     * list while we were sleeping...
     */

    for (lcv = udv_list.lh_first ; lcv != NULL ; lcv = lcv->u_list.le_next) {
      if (device == lcv->u_device)
	break;
    }

    /*
     * did we lose a race to someone else?   free our memory and retry.
     */

    if (lcv) {
      simple_unlock(&udv_lock);
      FREE(udv, M_TEMP);
      continue;
    }

    /*
     * we have it!   init the data structures, add to list and return.
     */

    simple_lock_init(&udv->u_obj.vmobjlock);
    udv->u_obj.pgops = &uvm_deviceops;
    TAILQ_INIT(&udv->u_obj.memq);	/* not used, but be safe */
    udv->u_obj.uo_npages = 0;
    udv->u_obj.uo_refs = 1;
    udv->u_flags = 0;
    udv->u_device = device;
    LIST_INSERT_HEAD(&udv_list, udv, u_list);
    simple_unlock(&udv_lock);

    return(&udv->u_obj);

  }  /* while(1) loop */

  /*NOTREACHED*/
}

/*
 * udv_reference
 *
 * add a reference to a VM object.   Note that the reference count must
 * already be one (the passed in reference) so there is no chance of the
 * udv being released or locked out here.
 *
 * => caller must call with object unlocked.
 */


static void udv_reference(uobj)

struct uvm_object *uobj;

{
  UVMHIST_FUNC("udv_reference"); UVMHIST_CALLED(maphist);

  simple_lock(&uobj->vmobjlock);
  uobj->uo_refs++;
  UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)",
	uobj, uobj->uo_refs,0,0);
  simple_unlock(&uobj->vmobjlock);
}

/*
 * udv_detach
 *
 * remove a reference to a VM object.
 *
 * => caller must call with object unlocked and map locked.
 */

static void udv_detach(uobj)

struct uvm_object *uobj;

{
  struct uvm_device *udv = (struct uvm_device *) uobj;
  UVMHIST_FUNC("udv_detach"); UVMHIST_CALLED(maphist);

  /*
   * loop until done
   */

  while (1) {
    simple_lock(&uobj->vmobjlock);

    if (uobj->uo_refs > 1) {
      uobj->uo_refs--;			/* drop ref! */
      simple_unlock(&uobj->vmobjlock);
      UVMHIST_LOG(maphist," <- done, uobj=0x%x, ref=%d",
		  uobj,uobj->uo_refs,0,0);
      return;
    }

#ifdef DIAGNOSTIC
    if (uobj->uo_npages || uobj->memq.tqh_first)
      panic("udv_detach: pages in a device object?");
#endif

    /*
     * now lock udv_lock
     */
    simple_lock(&udv_lock);

    /*
     * is it being held?   if so, wait until others are done.
     */
    if (udv->u_flags & UVM_DEVICE_HOLD) {

      /*
       * want it
       */
      udv->u_flags |= UVM_DEVICE_WANTED;
      simple_unlock(&uobj->vmobjlock);
      UVM_UNLOCK_AND_WAIT(udv, &udv_lock, FALSE, "udv_detach",0);
      continue;
    }

    /*
     * got it!   nuke it now.
     */

    LIST_REMOVE(udv, u_list);
    if (udv->u_flags & UVM_DEVICE_WANTED)
      wakeup(udv);
    FREE(udv, M_TEMP);
    break;	/* DONE! */

  }	/* while (1) loop */

  UVMHIST_LOG(maphist," <- done, freed uobj=0x%x", uobj,0,0,0);
  return;
}


/*
 * udv_flush
 *
 * flush pages out of a uvm object.   a no-op for devices.
 */

static boolean_t udv_flush(uobj, start, stop, flags)

struct uvm_object *uobj;
vm_offset_t start, stop;
int flags;

{
  return(TRUE);
}

/*
 * udv_fault: non-standard fault routine for device "pages"
 *
 * => rather than having a "get" function, we have a fault routine
 *	since we don't return vm_pages we need full control over the
 *	pmap_enter map in
 * => all the usual fault data structured are locked by the caller
 *	(i.e. maps(read), amap (if any), uobj)
 * => on return, we unlock all fault data structures
 * => flags: PGO_ALLPAGES: get all of the pages
 *	     PGO_LOCKED: fault data structures are locked
 *    XXX: currently PGO_LOCKED is always required ... consider removing
 *	it as a flag
 * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx]
 */

static int udv_fault(ufi, vaddr, pps, npages, centeridx, fault_type,
		     access_type, flags)

struct uvm_faultinfo *ufi;
vm_offset_t vaddr;
vm_page_t *pps;
int npages, centeridx, flags;
vm_fault_t fault_type;
vm_prot_t access_type;

{
  struct uvm_object *uobj;
  struct uvm_device *udv;
  vm_offset_t curr_offset, curr_va, paddr;
  struct vm_map_entry *entry = ufi->entry;
  int lcv, retval;
  dev_t device;
  int (*mapfn) __P((dev_t, int, int));
  UVMHIST_FUNC("udv_fault"); UVMHIST_CALLED(maphist);
  UVMHIST_LOG(maphist,"  flags=%d", flags,0,0,0);

  /*
   * XXX: !PGO_LOCKED calls are currently not allowed (or used)
   */

  if ((flags & PGO_LOCKED) == 0)
    panic("udv_fault: !PGO_LOCKED fault");

  /*
   * we do not allow device mappings to be mapped copy-on-write
   * so we kill any attempt to do so here.
   */

  if (UVM_ET_ISCOPYONWRITE(entry)) {
    UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=0x%x)",
		entry->etype, 0,0,0);
    uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL);
    return(VM_PAGER_ERROR);
  }

  /*
   * get object pointers and map function.
   */
  uobj = entry->object.uvm_obj;
  udv = (struct uvm_device *) uobj;
  device = udv->u_device;
  mapfn = cdevsw[major(device)].d_mmap;

  /*
   * now we must determine the offset in udv to use and the VA to use
   * for pmap_enter.  note that we always pmap_enter() in the
   * ufi->orig_map's pmap, but that our ufi->entry may be from some
   * other map (in the submap/sharemap case).  so we must convert the
   * VA from ufi->map to ufi->orig_map (note that in many cases these
   * maps are the same).   note that ufi->orig_rvaddr and ufi->rvaddr
   * refer to the same physical page.
   */
  /* udv offset = (offset from start of entry) + entry's offset */
  curr_offset = (vaddr - entry->start) + entry->offset;
  /* pmap va = orig_va + (offset of vaddr from translated va) */
  curr_va = ufi->orig_rvaddr + (vaddr - ufi->rvaddr);

  /*
   * loop over the page range entering in as needed
   */

  retval = VM_PAGER_OK;
  for (lcv = 0 ; lcv < npages ;
       lcv++, curr_offset += PAGE_SIZE, curr_va += PAGE_SIZE) {

    if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx)
      continue;

    if (pps[lcv] == PGO_DONTCARE)
      continue;

    paddr = pmap_phys_address((*mapfn)(device, (int)curr_offset, access_type));

    if (paddr == -1) {
      retval = VM_PAGER_ERROR;
      break;
    }

    UVMHIST_LOG(maphist, "  MAPPING: device: pm=0x%x, va=0x%x, pa=0x%x, at=%d",
                ufi->orig_map->pmap, curr_va, paddr, access_type);
    pmap_enter(ufi->orig_map->pmap, curr_va, paddr, access_type, 0);

  }

  uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL);
  return(retval);
}

/*
 * udv_asyncget: start async I/O to bring pages into ram
 *
 * => caller must lock object(???XXX: see if this is best)
 * => a no-op for devices
 */

static int udv_asyncget(uobj, offset, npages)

struct uvm_object *uobj;
vm_offset_t offset;
int npages;

{
  return(KERN_SUCCESS);
}

/*
 * udv_put: flush page data to backing store.
 *
 * => this function should never be called (since we never have any
 *	page structures to "put")
 */

static int udv_put(uobj, pps, npages, flags)

struct uvm_object *uobj;
struct vm_page **pps;
int npages, flags;

{
  panic("udv_put: trying to page out to a device!");
}