device_pager.c

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    1 /*-
    2  * Copyright (c) 1990 University of Utah.
    3  * Copyright (c) 1991, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the Systems Programming Group of the University of Utah Computer
    8  * Science Department.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)device_pager.c      8.1 (Berkeley) 6/11/93
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/8.0/sys/vm/device_pager.c 195774 2009-07-19 21:40:19Z alc $");
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/conf.h>
   43 #include <sys/lock.h>
   44 #include <sys/proc.h>
   45 #include <sys/mutex.h>
   46 #include <sys/mman.h>
   47 #include <sys/sx.h>
   48 
   49 #include <vm/vm.h>
   50 #include <vm/vm_object.h>
   51 #include <vm/vm_page.h>
   52 #include <vm/vm_pager.h>
   53 #include <vm/uma.h>
   54 
   55 static void dev_pager_init(void);
   56 static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
   57     vm_ooffset_t, struct ucred *);
   58 static void dev_pager_dealloc(vm_object_t);
   59 static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
   60 static void dev_pager_putpages(vm_object_t, vm_page_t *, int, 
   61                 boolean_t, int *);
   62 static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
   63                 int *);
   64 
   65 /* list of device pager objects */
   66 static struct pagerlst dev_pager_object_list;
   67 /* protect list manipulation */
   68 static struct mtx dev_pager_mtx;
   69 
   70 
   71 static uma_zone_t fakepg_zone;
   72 
   73 static vm_page_t dev_pager_getfake(vm_paddr_t, vm_memattr_t);
   74 static void dev_pager_putfake(vm_page_t);
   75 static void dev_pager_updatefake(vm_page_t, vm_paddr_t, vm_memattr_t);
   76 
   77 struct pagerops devicepagerops = {
   78         .pgo_init =     dev_pager_init,
   79         .pgo_alloc =    dev_pager_alloc,
   80         .pgo_dealloc =  dev_pager_dealloc,
   81         .pgo_getpages = dev_pager_getpages,
   82         .pgo_putpages = dev_pager_putpages,
   83         .pgo_haspage =  dev_pager_haspage,
   84 };
   85 
   86 static void
   87 dev_pager_init()
   88 {
   89         TAILQ_INIT(&dev_pager_object_list);
   90         mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
   91         fakepg_zone = uma_zcreate("DP fakepg", sizeof(struct vm_page),
   92             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR,
   93             UMA_ZONE_NOFREE|UMA_ZONE_VM); 
   94 }
   95 
   96 /*
   97  * MPSAFE
   98  */
   99 static vm_object_t
  100 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  101     vm_ooffset_t foff, struct ucred *cred)
  102 {
  103         struct cdev *dev;
  104         vm_object_t object, object1;
  105         vm_pindex_t pindex;
  106         unsigned int npages;
  107         vm_paddr_t paddr;
  108         vm_offset_t off;
  109         struct cdevsw *csw;
  110 
  111         /*
  112          * Offset should be page aligned.
  113          */
  114         if (foff & PAGE_MASK)
  115                 return (NULL);
  116 
  117         size = round_page(size);
  118         pindex = OFF_TO_IDX(foff + size);
  119 
  120         /*
  121          * Make sure this device can be mapped.
  122          */
  123         dev = handle;
  124         csw = dev_refthread(dev);
  125         if (csw == NULL)
  126                 return (NULL);
  127 
  128         /*
  129          * Check that the specified range of the device allows the desired
  130          * protection.
  131          *
  132          * XXX assumes VM_PROT_* == PROT_*
  133          */
  134         npages = OFF_TO_IDX(size);
  135         for (off = foff; npages--; off += PAGE_SIZE)
  136                 if ((*csw->d_mmap)(dev, off, &paddr, (int)prot) != 0) {
  137                         dev_relthread(dev);
  138                         return (NULL);
  139                 }
  140 
  141         mtx_lock(&dev_pager_mtx);
  142 
  143         /*
  144          * Look up pager, creating as necessary.
  145          */
  146         object1 = NULL;
  147         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  148         if (object == NULL) {
  149                 /*
  150                  * Allocate object and associate it with the pager.  Initialize
  151                  * the object's pg_color based upon the physical address of the
  152                  * device's memory.
  153                  */
  154                 mtx_unlock(&dev_pager_mtx);
  155                 object1 = vm_object_allocate(OBJT_DEVICE, pindex);
  156                 object1->flags |= OBJ_COLORED;
  157                 object1->pg_color = atop(paddr) - OFF_TO_IDX(off - PAGE_SIZE);
  158                 mtx_lock(&dev_pager_mtx);
  159                 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  160                 if (object != NULL) {
  161                         /*
  162                          * We raced with other thread while allocating object.
  163                          */
  164                         if (pindex > object->size)
  165                                 object->size = pindex;
  166                 } else {
  167                         object = object1;
  168                         object1 = NULL;
  169                         object->handle = handle;
  170                         TAILQ_INIT(&object->un_pager.devp.devp_pglist);
  171                         TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
  172                             pager_object_list);
  173                 }
  174         } else {
  175                 if (pindex > object->size)
  176                         object->size = pindex;
  177         }
  178         mtx_unlock(&dev_pager_mtx);
  179         dev_relthread(dev);
  180         vm_object_deallocate(object1);
  181         return (object);
  182 }
  183 
  184 static void
  185 dev_pager_dealloc(object)
  186         vm_object_t object;
  187 {
  188         vm_page_t m;
  189 
  190         VM_OBJECT_UNLOCK(object);
  191         mtx_lock(&dev_pager_mtx);
  192         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
  193         mtx_unlock(&dev_pager_mtx);
  194         VM_OBJECT_LOCK(object);
  195         /*
  196          * Free up our fake pages.
  197          */
  198         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != NULL) {
  199                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
  200                 dev_pager_putfake(m);
  201         }
  202 }
  203 
  204 static int
  205 dev_pager_getpages(object, m, count, reqpage)
  206         vm_object_t object;
  207         vm_page_t *m;
  208         int count;
  209         int reqpage;
  210 {
  211         vm_pindex_t offset;
  212         vm_paddr_t paddr;
  213         vm_page_t m_paddr, page;
  214         vm_memattr_t memattr;
  215         struct cdev *dev;
  216         int i, ret;
  217         int prot;
  218         struct cdevsw *csw;
  219         struct thread *td;
  220         struct file *fpop;
  221 
  222         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  223         dev = object->handle;
  224         page = m[reqpage];
  225         offset = page->pindex;
  226         memattr = object->memattr;
  227         VM_OBJECT_UNLOCK(object);
  228         csw = dev_refthread(dev);
  229         if (csw == NULL)
  230                 panic("dev_pager_getpage: no cdevsw");
  231         prot = PROT_READ;       /* XXX should pass in? */
  232 
  233         td = curthread;
  234         fpop = td->td_fpop;
  235         td->td_fpop = NULL;
  236         ret = (*csw->d_mmap)(dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr, prot);
  237         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
  238         td->td_fpop = fpop;
  239         dev_relthread(dev);
  240         /* If "paddr" is a real page, perform a sanity check on "memattr". */
  241         if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
  242             pmap_page_get_memattr(m_paddr) != memattr) {
  243                 memattr = pmap_page_get_memattr(m_paddr);
  244                 printf(
  245             "WARNING: A device driver has set \"memattr\" inconsistently.\n");
  246         }
  247         if ((page->flags & PG_FICTITIOUS) != 0) {
  248                 /*
  249                  * If the passed in reqpage page is a fake page, update it with
  250                  * the new physical address.
  251                  */
  252                 VM_OBJECT_LOCK(object);
  253                 dev_pager_updatefake(page, paddr, memattr);
  254                 if (count > 1) {
  255                         vm_page_lock_queues();
  256                         for (i = 0; i < count; i++) {
  257                                 if (i != reqpage)
  258                                         vm_page_free(m[i]);
  259                         }
  260                         vm_page_unlock_queues();
  261                 }
  262         } else {
  263                 /*
  264                  * Replace the passed in reqpage page with our own fake page and
  265                  * free up the all of the original pages.
  266                  */
  267                 page = dev_pager_getfake(paddr, memattr);
  268                 VM_OBJECT_LOCK(object);
  269                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
  270                 vm_page_lock_queues();
  271                 for (i = 0; i < count; i++)
  272                         vm_page_free(m[i]);
  273                 vm_page_unlock_queues();
  274                 vm_page_insert(page, object, offset);
  275                 m[reqpage] = page;
  276         }
  277         page->valid = VM_PAGE_BITS_ALL;
  278         return (VM_PAGER_OK);
  279 }
  280 
  281 static void
  282 dev_pager_putpages(object, m, count, sync, rtvals)
  283         vm_object_t object;
  284         vm_page_t *m;
  285         int count;
  286         boolean_t sync;
  287         int *rtvals;
  288 {
  289         panic("dev_pager_putpage called");
  290 }
  291 
  292 static boolean_t
  293 dev_pager_haspage(object, pindex, before, after)
  294         vm_object_t object;
  295         vm_pindex_t pindex;
  296         int *before;
  297         int *after;
  298 {
  299         if (before != NULL)
  300                 *before = 0;
  301         if (after != NULL)
  302                 *after = 0;
  303         return (TRUE);
  304 }
  305 
  306 /*
  307  * Create a fictitious page with the specified physical address and memory
  308  * attribute.  The memory attribute is the only the machine-dependent aspect
  309  * of a fictitious page that must be initialized.
  310  */
  311 static vm_page_t
  312 dev_pager_getfake(vm_paddr_t paddr, vm_memattr_t memattr)
  313 {
  314         vm_page_t m;
  315 
  316         m = uma_zalloc(fakepg_zone, M_WAITOK | M_ZERO);
  317         m->phys_addr = paddr;
  318         /* Fictitious pages don't use "segind". */
  319         m->flags = PG_FICTITIOUS;
  320         /* Fictitious pages don't use "order" or "pool". */
  321         m->oflags = VPO_BUSY;
  322         m->wire_count = 1;
  323         pmap_page_set_memattr(m, memattr);
  324         return (m);
  325 }
  326 
  327 /*
  328  * Release a fictitious page.
  329  */
  330 static void
  331 dev_pager_putfake(vm_page_t m)
  332 {
  333 
  334         if (!(m->flags & PG_FICTITIOUS))
  335                 panic("dev_pager_putfake: bad page");
  336         uma_zfree(fakepg_zone, m);
  337 }
  338 
  339 /*
  340  * Update the given fictitious page to the specified physical address and
  341  * memory attribute.
  342  */
  343 static void
  344 dev_pager_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
  345 {
  346 
  347         if (!(m->flags & PG_FICTITIOUS))
  348                 panic("dev_pager_updatefake: bad page");
  349         m->phys_addr = paddr;
  350         pmap_page_set_memattr(m, memattr);
  351 }
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FreeBSD/Linux Kernel Cross Reference sys/vm/device_pager.c

FreeBSD/Linux Kernel Cross Reference
sys/vm/device_pager.c
