freebsd-dev/sys/vm/phys_pager.c

/*
 * Copyright (c) 2000 Peter Wemm
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
 *
 * $FreeBSD$
 */

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

#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_zone.h>

static void phys_pager_init __P((void));
static vm_object_t phys_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
		vm_ooffset_t));
static void phys_pager_dealloc __P((vm_object_t));
static int phys_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
static void phys_pager_putpages __P((vm_object_t, vm_page_t *, int, 
		boolean_t, int *));
static boolean_t phys_pager_haspage __P((vm_object_t, vm_pindex_t, int *,
		int *));

/* list of device pager objects */
static struct pagerlst phys_pager_object_list;

static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;

struct pagerops physpagerops = {
	phys_pager_init,
	phys_pager_alloc,
	phys_pager_dealloc,
	phys_pager_getpages,
	phys_pager_putpages,
	phys_pager_haspage,
	NULL
};

static void
phys_pager_init()
{
	TAILQ_INIT(&phys_pager_object_list);
}

static vm_object_t
phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
		 vm_ooffset_t foff)
{
	vm_object_t object;

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

	size = round_page(size);

	/*
	 * Lock to prevent object creation race condition.
	 */
	while (phys_pager_alloc_lock) {
		phys_pager_alloc_lock_want++;
		tsleep(&phys_pager_alloc_lock, PVM, "ppall", 0);
		phys_pager_alloc_lock_want--;
	}
	phys_pager_alloc_lock = 1;

	/*
	 * Look up pager, creating as necessary.
	 */
	object = vm_pager_object_lookup(&phys_pager_object_list, handle);
	if (object == NULL) {
		/*
		 * Allocate object and associate it with the pager.
		 */
		object = vm_object_allocate(OBJT_PHYS,
			OFF_TO_IDX(foff + size));
		object->handle = handle;
		TAILQ_INIT(&object->un_pager.physp.physp_pglist);
		TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
		    pager_object_list);
	} else {
		/*
		 * Gain a reference to the object.
		 */
		vm_object_reference(object);
		if (OFF_TO_IDX(foff + size) > object->size)
			object->size = OFF_TO_IDX(foff + size);
	}

	phys_pager_alloc_lock = 0;
	if (phys_pager_alloc_lock_want)
		wakeup(&phys_pager_alloc_lock);

	return (object);
}

static void
phys_pager_dealloc(object)
	vm_object_t object;
{
	vm_page_t m;
	int s;

	TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
	/*
	 * Free up our fake pages.
	 */
	s = splvm();
	while ((m = TAILQ_FIRST(&object->un_pager.physp.physp_pglist)) != 0) {
		TAILQ_REMOVE(&object->un_pager.physp.physp_pglist, m, pageq);
		/* return the page back to normal */
		m->flags &= ~PG_FICTITIOUS;
		m->dirty = 0;
		vm_page_unwire(m, 0);
		vm_page_flag_clear(m, PG_ZERO);
		vm_page_free(m);
	}
	splx(s);
}

static int
phys_pager_getpages(object, m, count, reqpage)
	vm_object_t object;
	vm_page_t *m;
	int count;
	int reqpage;
{
	int i, s;

	s = splvm();
	/*
	 * Fill as many pages as vm_fault has allocated for us.
	 */
	for (i = 0; i < count; i++) {
		if ((m[i]->flags & PG_ZERO) == 0)
			vm_page_zero_fill(m[i]);
		vm_page_flag_set(m[i], PG_ZERO);
		/* Switch off pv_entries */
		vm_page_wire(m[i]);
		vm_page_flag_set(m[i], PG_FICTITIOUS);
		m[i]->valid = VM_PAGE_BITS_ALL;
		m[i]->dirty = 0;
		/* The requested page must remain busy, the others not. */
		if (reqpage != i) {
			vm_page_flag_clear(m[i], PG_BUSY);
			m[i]->busy = 0;
		}
		TAILQ_INSERT_TAIL(&object->un_pager.physp.physp_pglist, m[i],
		    pageq);
	}
	splx(s);

	return (VM_PAGER_OK);
}

static void
phys_pager_putpages(object, m, count, sync, rtvals)
	vm_object_t object;
	vm_page_t *m;
	int count;
	boolean_t sync;
	int *rtvals;
{
	panic("phys_pager_putpage called");
}

/*
 * Implement a pretty aggressive clustered getpages strategy.  Hint that
 * everything in an entire 4MB window should be prefaulted at once.
 *
 * XXX 4MB (1024 slots per page table page) is convenient for x86,
 * but may not be for other arches.
 */
#ifndef PHYSCLUSTER
#define PHYSCLUSTER 1024
#endif
static boolean_t
phys_pager_haspage(object, pindex, before, after)
	vm_object_t object;
	vm_pindex_t pindex;
	int *before;
	int *after;
{
	vm_pindex_t base, end;

	base = pindex & (~(PHYSCLUSTER - 1));
	end = base + (PHYSCLUSTER - 1);
	if (before != NULL)
		*before = pindex - base;
	if (after != NULL)
		*after = end - pindex;
	return (TRUE);
}