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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2009 Hudson River Trading LLC
* Written by: John H. Baldwin <jhb@FreeBSD.org>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* This pager manages OBJT_SG objects. These objects are backed by
* a scatter/gather list of physical address ranges.
*/
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/sglist.h>
#include <sys/vmmeter.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_phys.h>
#include <vm/uma.h>
static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
vm_ooffset_t, struct ucred *);
static void sg_pager_dealloc(vm_object_t);
static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
static void sg_pager_putpages(vm_object_t, vm_page_t *, int,
boolean_t, int *);
static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
int *);
struct pagerops sgpagerops = {
.pgo_alloc = sg_pager_alloc,
.pgo_dealloc = sg_pager_dealloc,
.pgo_getpages = sg_pager_getpages,
.pgo_putpages = sg_pager_putpages,
.pgo_haspage = sg_pager_haspage,
};
static vm_object_t
sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred)
{
struct sglist *sg;
vm_object_t object;
vm_pindex_t npages, pindex;
int i;
/*
* Offset should be page aligned.
*/
if (foff & PAGE_MASK)
return (NULL);
/*
* The scatter/gather list must only include page-aligned
* ranges.
*/
npages = 0;
sg = handle;
for (i = 0; i < sg->sg_nseg; i++) {
if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 ||
(sg->sg_segs[i].ss_len % PAGE_SIZE) != 0)
return (NULL);
npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
}
/*
* The scatter/gather list has a fixed size. Refuse requests
* to map beyond that.
*/
size = round_page(size);
pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size);
if (pindex > npages || pindex < OFF_TO_IDX(foff) ||
pindex < OFF_TO_IDX(size))
return (NULL);
/*
* Allocate a new object and associate it with the
* scatter/gather list. It is ok for our purposes to have
* multiple VM objects associated with the same scatter/gather
* list because scatter/gather lists are static. This is also
* simpler than ensuring a unique object per scatter/gather
* list.
*/
object = vm_object_allocate(OBJT_SG, npages);
object->handle = sglist_hold(sg);
TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
return (object);
}
static void
sg_pager_dealloc(vm_object_t object)
{
struct sglist *sg;
vm_page_t m;
/*
* Free up our fake pages.
*/
while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q);
vm_page_putfake(m);
}
sg = object->handle;
sglist_free(sg);
object->handle = NULL;
object->type = OBJT_DEAD;
}
static int
sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
int *rahead)
{
struct sglist *sg;
vm_page_t m_paddr, page;
vm_pindex_t offset;
vm_paddr_t paddr;
vm_memattr_t memattr;
size_t space;
int i;
/* Since our haspage reports zero after/before, the count is 1. */
KASSERT(count == 1, ("%s: count %d", __func__, count));
VM_OBJECT_ASSERT_WLOCKED(object);
sg = object->handle;
memattr = object->memattr;
VM_OBJECT_WUNLOCK(object);
offset = m[0]->pindex;
/*
* Lookup the physical address of the requested page. An initial
* value of '1' instead of '0' is used so we can assert that the
* page is found since '0' can be a valid page-aligned physical
* address.
*/
space = 0;
paddr = 1;
for (i = 0; i < sg->sg_nseg; i++) {
if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) {
space += sg->sg_segs[i].ss_len;
continue;
}
paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
break;
}
KASSERT(paddr != 1, ("invalid SG page index"));
/* If "paddr" is a real page, perform a sanity check on "memattr". */
if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
pmap_page_get_memattr(m_paddr) != memattr) {
memattr = pmap_page_get_memattr(m_paddr);
printf(
"WARNING: A device driver has set \"memattr\" inconsistently.\n");
}
/* Return a fake page for the requested page. */
KASSERT(!(m[0]->flags & PG_FICTITIOUS),
("backing page for SG is fake"));
/* Construct a new fake page. */
page = vm_page_getfake(paddr, memattr);
VM_OBJECT_WLOCK(object);
TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q);
vm_page_replace_checked(page, object, offset, m[0]);
vm_page_lock(m[0]);
vm_page_free(m[0]);
vm_page_unlock(m[0]);
m[0] = page;
page->valid = VM_PAGE_BITS_ALL;
if (rbehind)
*rbehind = 0;
if (rahead)
*rahead = 0;
return (VM_PAGER_OK);
}
static void
sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
boolean_t sync, int *rtvals)
{
panic("sg_pager_putpage called");
}
static boolean_t
sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
int *after)
{
if (before != NULL)
*before = 0;
if (after != NULL)
*after = 0;
return (TRUE);
}
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