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mirror of https://git.FreeBSD.org/src.git synced 2024-12-05 09:14:03 +00:00
freebsd/sys/vm/phys_pager.c
Alfred Perlstein b5861b3450 Really fix phys_pager:
Backout the previous delta (rev 1.4), it didn't make any difference.

If the requested handle is NULL then don't add it to the list of
objects, to be found by handle.

The problem is that when asking for a NULL handle you are implying
you want a new object.  Because objects with NULL handles were
being added to the list, any further requests for phys backed
objects with NULL handles would return a reference to the initial
NULL handle object after finding it on the list.

Basically one couldn't have more than one phys backed object without
a handle in the entire system without this fix.  If you did more
than one shared memory allocation using the phys pager it would
give you your initial allocation again.
2000-12-06 21:52:23 +00:00

188 lines
4.7 KiB
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>
/* list of device pager objects */
static struct pagerlst phys_pager_object_list;
static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
static void
phys_pager_init(void)
{
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);
if (handle != NULL) {
/*
* 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_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);
} else {
object = vm_object_allocate(OBJT_PHYS,
OFF_TO_IDX(foff + size));
}
return (object);
}
static void
phys_pager_dealloc(vm_object_t object)
{
if (object->handle != NULL)
TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
}
static int
phys_pager_getpages(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_unmanage(m[i]);
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;
}
}
splx(s);
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");
}
/*
* 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(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);
}
struct pagerops physpagerops = {
phys_pager_init,
phys_pager_alloc,
phys_pager_dealloc,
phys_pager_getpages,
phys_pager_putpages,
phys_pager_haspage,
NULL
};