freebsd-dev/sys/vm/device_pager.c
Konstantin Belousov c42b43a054 Add a new populate() pager method and extend device pager ops vector
with cdev_pg_populate() to provide device drivers access to it.  It
gives drivers fine control of the pages ownership and allows drivers
to implement arbitrary prefault policies.

The populate method is called on a page fault and is supposed to
populate the vm object with the page at the fault location and some
amount of pages around it, at pager's discretion.  VM provides the
pager with the hints about current range of the object mapping, to
avoid instantiation of immediately unused pages, if pager decides so.
Also, VM passes the fault type and map entry protection to the pager,
allowing it to force the optimal required ownership of the mapped
pages.

Installed pages must contiguously fill the returned region, be fully
valid and exclusively busied.  Of course, the pages must be compatible
with the object' type.

After populate() successfully returned, VM fault handler installs as
many instantiated pages into the process page tables as it sees
reasonable, while still obeying the correct semantic for COW and vm
map locking.

The method is opt-in, pager sets OBJ_POPULATE flag to indicate that
the method can be called.  If pager' vm objects can be shadowed, pager
must implement the traditional getpages() method in addition to the
populate().  Populate() might fall back to the getpages() on per-call
basis as well, by returning VM_PAGER_BAD error code.

For now for device pagers, the populate() method is only allowed to be
used by the managed device pagers, but the limitation is only made
because there is no unmanaged fault handlers which could use it right
now.

KPI designed together with, and reviewed by:	alc
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
2016-12-08 11:26:11 +00:00

459 lines
13 KiB
C

/*-
* Copyright (c) 1990 University of Utah.
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)device_pager.c 8.1 (Berkeley) 6/11/93
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/mutex.h>
#include <sys/mman.h>
#include <sys/rwlock.h>
#include <sys/sx.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 void dev_pager_init(void);
static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
vm_ooffset_t, struct ucred *);
static void dev_pager_dealloc(vm_object_t);
static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
static void dev_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
static void dev_pager_free_page(vm_object_t object, vm_page_t m);
static int dev_pager_populate(vm_object_t object, vm_pindex_t pidx,
int fault_type, vm_prot_t, vm_pindex_t *first, vm_pindex_t *last);
/* list of device pager objects */
static struct pagerlst dev_pager_object_list;
/* protect list manipulation */
static struct mtx dev_pager_mtx;
struct pagerops devicepagerops = {
.pgo_init = dev_pager_init,
.pgo_alloc = dev_pager_alloc,
.pgo_dealloc = dev_pager_dealloc,
.pgo_getpages = dev_pager_getpages,
.pgo_putpages = dev_pager_putpages,
.pgo_haspage = dev_pager_haspage,
};
struct pagerops mgtdevicepagerops = {
.pgo_alloc = dev_pager_alloc,
.pgo_dealloc = dev_pager_dealloc,
.pgo_getpages = dev_pager_getpages,
.pgo_putpages = dev_pager_putpages,
.pgo_haspage = dev_pager_haspage,
.pgo_populate = dev_pager_populate,
};
static int old_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred, u_short *color);
static void old_dev_pager_dtor(void *handle);
static int old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset,
int prot, vm_page_t *mres);
static struct cdev_pager_ops old_dev_pager_ops = {
.cdev_pg_ctor = old_dev_pager_ctor,
.cdev_pg_dtor = old_dev_pager_dtor,
.cdev_pg_fault = old_dev_pager_fault
};
static void
dev_pager_init(void)
{
TAILQ_INIT(&dev_pager_object_list);
mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
}
vm_object_t
cdev_pager_lookup(void *handle)
{
vm_object_t object;
mtx_lock(&dev_pager_mtx);
object = vm_pager_object_lookup(&dev_pager_object_list, handle);
mtx_unlock(&dev_pager_mtx);
return (object);
}
vm_object_t
cdev_pager_allocate(void *handle, enum obj_type tp, struct cdev_pager_ops *ops,
vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff, struct ucred *cred)
{
vm_object_t object, object1;
vm_pindex_t pindex;
u_short color;
if (tp != OBJT_DEVICE && tp != OBJT_MGTDEVICE)
return (NULL);
KASSERT(tp == OBJT_MGTDEVICE || ops->cdev_pg_populate == NULL,
("populate on unmanaged device pager"));
/*
* Offset should be page aligned.
*/
if (foff & PAGE_MASK)
return (NULL);
size = round_page(size);
pindex = OFF_TO_IDX(foff + size);
if (ops->cdev_pg_ctor(handle, size, prot, foff, cred, &color) != 0)
return (NULL);
mtx_lock(&dev_pager_mtx);
/*
* Look up pager, creating as necessary.
*/
object1 = NULL;
object = vm_pager_object_lookup(&dev_pager_object_list, handle);
if (object == NULL) {
/*
* Allocate object and associate it with the pager. Initialize
* the object's pg_color based upon the physical address of the
* device's memory.
*/
mtx_unlock(&dev_pager_mtx);
object1 = vm_object_allocate(tp, pindex);
object1->flags |= OBJ_COLORED;
object1->pg_color = color;
object1->handle = handle;
object1->un_pager.devp.ops = ops;
object1->un_pager.devp.dev = handle;
TAILQ_INIT(&object1->un_pager.devp.devp_pglist);
mtx_lock(&dev_pager_mtx);
object = vm_pager_object_lookup(&dev_pager_object_list, handle);
if (object != NULL) {
/*
* We raced with other thread while allocating object.
*/
if (pindex > object->size)
object->size = pindex;
KASSERT(object->type == tp,
("Inconsistent device pager type %p %d",
object, tp));
KASSERT(object->un_pager.devp.ops == ops,
("Inconsistent devops %p %p", object, ops));
} else {
object = object1;
object1 = NULL;
object->handle = handle;
TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
pager_object_list);
if (ops->cdev_pg_populate != NULL)
vm_object_set_flag(object, OBJ_POPULATE);
}
} else {
if (pindex > object->size)
object->size = pindex;
KASSERT(object->type == tp,
("Inconsistent device pager type %p %d", object, tp));
}
mtx_unlock(&dev_pager_mtx);
if (object1 != NULL) {
object1->handle = object1;
mtx_lock(&dev_pager_mtx);
TAILQ_INSERT_TAIL(&dev_pager_object_list, object1,
pager_object_list);
mtx_unlock(&dev_pager_mtx);
vm_object_deallocate(object1);
}
return (object);
}
static vm_object_t
dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred)
{
return (cdev_pager_allocate(handle, OBJT_DEVICE, &old_dev_pager_ops,
size, prot, foff, cred));
}
void
cdev_pager_free_page(vm_object_t object, vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->type == OBJT_MGTDEVICE) {
KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("unmanaged %p", m));
pmap_remove_all(m);
vm_page_lock(m);
vm_page_remove(m);
vm_page_unlock(m);
} else if (object->type == OBJT_DEVICE)
dev_pager_free_page(object, m);
}
static void
dev_pager_free_page(vm_object_t object, vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->type == OBJT_DEVICE &&
(m->oflags & VPO_UNMANAGED) != 0),
("Managed device or page obj %p m %p", object, m));
TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, plinks.q);
vm_page_putfake(m);
}
static void
dev_pager_dealloc(vm_object_t object)
{
vm_page_t m;
VM_OBJECT_WUNLOCK(object);
object->un_pager.devp.ops->cdev_pg_dtor(object->un_pager.devp.dev);
mtx_lock(&dev_pager_mtx);
TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
mtx_unlock(&dev_pager_mtx);
VM_OBJECT_WLOCK(object);
if (object->type == OBJT_DEVICE) {
/*
* Free up our fake pages.
*/
while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist))
!= NULL)
dev_pager_free_page(object, m);
}
object->handle = NULL;
object->type = OBJT_DEAD;
}
static int
dev_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind,
int *rahead)
{
int error;
/* Since our haspage reports zero after/before, the count is 1. */
KASSERT(count == 1, ("%s: count %d", __func__, count));
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->un_pager.devp.ops->cdev_pg_fault == NULL)
return (VM_PAGER_FAIL);
error = object->un_pager.devp.ops->cdev_pg_fault(object,
IDX_TO_OFF(ma[0]->pindex), PROT_READ, &ma[0]);
VM_OBJECT_ASSERT_WLOCKED(object);
if (error == VM_PAGER_OK) {
KASSERT((object->type == OBJT_DEVICE &&
(ma[0]->oflags & VPO_UNMANAGED) != 0) ||
(object->type == OBJT_MGTDEVICE &&
(ma[0]->oflags & VPO_UNMANAGED) == 0),
("Wrong page type %p %p", ma[0], object));
if (object->type == OBJT_DEVICE) {
TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist,
ma[0], plinks.q);
}
if (rbehind)
*rbehind = 0;
if (rahead)
*rahead = 0;
}
return (error);
}
static int
dev_pager_populate(vm_object_t object, vm_pindex_t pidx, int fault_type,
vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->un_pager.devp.ops->cdev_pg_populate == NULL)
return (VM_PAGER_FAIL);
return (object->un_pager.devp.ops->cdev_pg_populate(object, pidx,
fault_type, max_prot, first, last));
}
static int
old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
vm_page_t *mres)
{
vm_paddr_t paddr;
vm_page_t m_paddr, page;
struct cdev *dev;
struct cdevsw *csw;
struct file *fpop;
struct thread *td;
vm_memattr_t memattr, memattr1;
int ref, ret;
memattr = object->memattr;
VM_OBJECT_WUNLOCK(object);
dev = object->handle;
csw = dev_refthread(dev, &ref);
if (csw == NULL) {
VM_OBJECT_WLOCK(object);
return (VM_PAGER_FAIL);
}
td = curthread;
fpop = td->td_fpop;
td->td_fpop = NULL;
ret = csw->d_mmap(dev, offset, &paddr, prot, &memattr);
td->td_fpop = fpop;
dev_relthread(dev, ref);
if (ret != 0) {
printf(
"WARNING: dev_pager_getpage: map function returns error %d", ret);
VM_OBJECT_WLOCK(object);
return (VM_PAGER_FAIL);
}
/* If "paddr" is a real page, perform a sanity check on "memattr". */
if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
(memattr1 = pmap_page_get_memattr(m_paddr)) != memattr) {
/*
* For the /dev/mem d_mmap routine to return the
* correct memattr, pmap_page_get_memattr() needs to
* be called, which we do there.
*/
if ((csw->d_flags & D_MEM) == 0) {
printf("WARNING: Device driver %s has set "
"\"memattr\" inconsistently (drv %u pmap %u).\n",
csw->d_name, memattr, memattr1);
}
memattr = memattr1;
}
if (((*mres)->flags & PG_FICTITIOUS) != 0) {
/*
* If the passed in result page is a fake page, update it with
* the new physical address.
*/
page = *mres;
VM_OBJECT_WLOCK(object);
vm_page_updatefake(page, paddr, memattr);
} else {
/*
* Replace the passed in reqpage page with our own fake page and
* free up the all of the original pages.
*/
page = vm_page_getfake(paddr, memattr);
VM_OBJECT_WLOCK(object);
vm_page_replace_checked(page, object, (*mres)->pindex, *mres);
vm_page_lock(*mres);
vm_page_free(*mres);
vm_page_unlock(*mres);
*mres = page;
}
page->valid = VM_PAGE_BITS_ALL;
return (VM_PAGER_OK);
}
static void
dev_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
int *rtvals)
{
panic("dev_pager_putpage called");
}
static boolean_t
dev_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);
}
static int
old_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred, u_short *color)
{
struct cdev *dev;
struct cdevsw *csw;
vm_memattr_t dummy;
vm_ooffset_t off;
vm_paddr_t paddr;
unsigned int npages;
int ref;
/*
* Make sure this device can be mapped.
*/
dev = handle;
csw = dev_refthread(dev, &ref);
if (csw == NULL)
return (ENXIO);
/*
* Check that the specified range of the device allows the desired
* protection.
*
* XXX assumes VM_PROT_* == PROT_*
*/
npages = OFF_TO_IDX(size);
paddr = 0; /* Make paddr initialized for the case of size == 0. */
for (off = foff; npages--; off += PAGE_SIZE) {
if (csw->d_mmap(dev, off, &paddr, (int)prot, &dummy) != 0) {
dev_relthread(dev, ref);
return (EINVAL);
}
}
dev_ref(dev);
dev_relthread(dev, ref);
*color = atop(paddr) - OFF_TO_IDX(off - PAGE_SIZE);
return (0);
}
static void
old_dev_pager_dtor(void *handle)
{
dev_rel(handle);
}