freebsd-dev/sys/vm/phys_pager.c
Jeff Roberson 0012f373e4 (4/6) Protect page valid with the busy lock.
Atomics are used for page busy and valid state when the shared busy is
held.  The details of the locking protocol and valid and dirty
synchronization are in the updated vm_page.h comments.

Reviewed by:    kib, markj
Tested by:      pho
Sponsored by:   Netflix, Intel
Differential Revision:        https://reviews.freebsd.org/D21594
2019-10-15 03:45:41 +00:00

252 lines
6.6 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/mutex.h>
#include <sys/mman.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
/* list of phys pager objects */
static struct pagerlst phys_pager_object_list;
/* protect access to phys_pager_object_list */
static struct mtx phys_pager_mtx;
static void
phys_pager_init(void)
{
TAILQ_INIT(&phys_pager_object_list);
mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
}
static vm_object_t
phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred)
{
vm_object_t object, object1;
vm_pindex_t pindex;
/*
* Offset should be page aligned.
*/
if (foff & PAGE_MASK)
return (NULL);
pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
if (handle != NULL) {
mtx_lock(&phys_pager_mtx);
/*
* Look up pager, creating as necessary.
*/
object1 = NULL;
object = vm_pager_object_lookup(&phys_pager_object_list, handle);
if (object == NULL) {
/*
* Allocate object and associate it with the pager.
*/
mtx_unlock(&phys_pager_mtx);
object1 = vm_object_allocate(OBJT_PHYS, pindex);
mtx_lock(&phys_pager_mtx);
object = vm_pager_object_lookup(&phys_pager_object_list,
handle);
if (object != NULL) {
/*
* We raced with other thread while
* allocating object.
*/
if (pindex > object->size)
object->size = pindex;
} else {
object = object1;
object1 = NULL;
object->handle = handle;
vm_object_set_flag(object, OBJ_POPULATE);
TAILQ_INSERT_TAIL(&phys_pager_object_list,
object, pager_object_list);
}
} else {
if (pindex > object->size)
object->size = pindex;
}
mtx_unlock(&phys_pager_mtx);
vm_object_deallocate(object1);
} else {
object = vm_object_allocate(OBJT_PHYS, pindex);
vm_object_set_flag(object, OBJ_POPULATE);
}
return (object);
}
static void
phys_pager_dealloc(vm_object_t object)
{
if (object->handle != NULL) {
VM_OBJECT_WUNLOCK(object);
mtx_lock(&phys_pager_mtx);
TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
mtx_unlock(&phys_pager_mtx);
VM_OBJECT_WLOCK(object);
}
object->handle = NULL;
object->type = OBJT_DEAD;
}
/*
* Fill as many pages as vm_fault has allocated for us.
*/
static int
phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
int *rahead)
{
int i;
VM_OBJECT_ASSERT_WLOCKED(object);
for (i = 0; i < count; i++) {
if (vm_page_none_valid(m[i])) {
if ((m[i]->flags & PG_ZERO) == 0)
pmap_zero_page(m[i]);
vm_page_valid(m[i]);
}
KASSERT(vm_page_all_valid(m[i]),
("phys_pager_getpages: partially valid page %p", m[i]));
KASSERT(m[i]->dirty == 0,
("phys_pager_getpages: dirty page %p", m[i]));
}
if (rbehind)
*rbehind = 0;
if (rahead)
*rahead = 0;
return (VM_PAGER_OK);
}
/*
* Implement a pretty aggressive clustered getpages strategy. Hint that
* everything in an entire 4MB window should be prefaulted at once.
*
* 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 int phys_pager_cluster = PHYSCLUSTER;
SYSCTL_INT(_vm, OID_AUTO, phys_pager_cluster, CTLFLAG_RWTUN,
&phys_pager_cluster, 0,
"prefault window size for phys pager");
/*
* Max hint to vm_page_alloc() about the further allocation needs
* inside the phys_pager_populate() loop. The number of bits used to
* implement VM_ALLOC_COUNT() determines the hard limit on this value.
* That limit is currently 65535.
*/
#define PHYSALLOC 16
static int
phys_pager_populate(vm_object_t object, vm_pindex_t pidx,
int fault_type __unused, vm_prot_t max_prot __unused, vm_pindex_t *first,
vm_pindex_t *last)
{
vm_page_t m;
vm_pindex_t base, end, i;
int ahead;
base = rounddown(pidx, phys_pager_cluster);
end = base + phys_pager_cluster - 1;
if (end >= object->size)
end = object->size - 1;
if (*first > base)
base = *first;
if (end > *last)
end = *last;
*first = base;
*last = end;
for (i = base; i <= end; i++) {
ahead = MIN(end - i, PHYSALLOC);
m = vm_page_grab(object, i,
VM_ALLOC_NORMAL | VM_ALLOC_COUNT(ahead));
if (!vm_page_all_valid(m))
vm_page_zero_invalid(m, TRUE);
KASSERT(m->dirty == 0,
("phys_pager_populate: dirty page %p", m));
}
return (VM_PAGER_OK);
}
static void
phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
int *rtvals)
{
panic("phys_pager_putpage called");
}
static boolean_t
phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
int *after)
{
vm_pindex_t base, end;
base = rounddown(pindex, phys_pager_cluster);
end = base + phys_pager_cluster - 1;
if (before != NULL)
*before = pindex - base;
if (after != NULL)
*after = end - pindex;
return (TRUE);
}
struct pagerops physpagerops = {
.pgo_init = phys_pager_init,
.pgo_alloc = phys_pager_alloc,
.pgo_dealloc = phys_pager_dealloc,
.pgo_getpages = phys_pager_getpages,
.pgo_putpages = phys_pager_putpages,
.pgo_haspage = phys_pager_haspage,
.pgo_populate = phys_pager_populate,
};