device_pager.c

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/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 * 3. 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 <sys/user.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 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;
 
const struct pagerops devicepagerops = {
        .pgo_kvme_type = KVME_TYPE_DEVICE,
        .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,
};
 
const struct pagerops mgtdevicepagerops = {
        .pgo_kvme_type = KVME_TYPE_MGTDEVICE,
        .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 const 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,
    const 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);
 
        /*
         * Treat the mmap(2) file offset as an unsigned value for a
         * device mapping.  This, in effect, allows a user to pass all
         * possible off_t values as the mapping cookie to the driver.  At
         * this point, we know that both foff and size are a multiple
         * of the page size.  Do a check to avoid wrap.
         */
        size = round_page(size);
        pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size);
        if (pindex > OBJ_MAX_SIZE || pindex < OFF_TO_IDX(foff) ||
            pindex < OFF_TO_IDX(size))
                return (NULL);
 
        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);
                (void)vm_page_remove(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) {
                        if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0)
                                continue;
 
                        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));
        if (object->un_pager.devp.ops->cdev_pg_fault == NULL)
                return (VM_PAGER_FAIL);
        VM_OBJECT_WLOCK(object);
        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;
        }
        VM_OBJECT_WUNLOCK(object);
 
        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(page, object, (*mres)->pindex, *mres);
                *mres = page;
        }
        vm_page_valid(page);
        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);
}