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/8.2/sys/vm/device_pager.c 212229 2010-09-05 14:27:55Z kib $");
   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 static __inline int
   97 dev_mmap(struct cdevsw *csw, struct cdev *dev, vm_offset_t offset,
   98     vm_paddr_t *paddr, int nprot, vm_memattr_t *memattr)
   99 {
  100 
  101         if (csw->d_flags & D_MMAP2)
  102                 return (csw->d_mmap2(dev, offset, paddr, nprot, memattr));
  103         else
  104                 return (csw->d_mmap(dev, offset, paddr, nprot));
  105 }
  106 
  107 /*
  108  * MPSAFE
  109  */
  110 static vm_object_t
  111 dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  112     vm_ooffset_t foff, struct ucred *cred)
  113 {
  114         struct cdev *dev;
  115         vm_object_t object, object1;
  116         vm_pindex_t pindex;
  117         unsigned int npages;
  118         vm_paddr_t paddr;
  119         vm_offset_t off;
  120         vm_memattr_t dummy;
  121         struct cdevsw *csw;
  122         int ref;
  123 
  124         /*
  125          * Offset should be page aligned.
  126          */
  127         if (foff & PAGE_MASK)
  128                 return (NULL);
  129 
  130         size = round_page(size);
  131         pindex = OFF_TO_IDX(foff + size);
  132 
  133         /*
  134          * Make sure this device can be mapped.
  135          */
  136         dev = handle;
  137         csw = dev_refthread(dev, &ref);
  138         if (csw == NULL)
  139                 return (NULL);
  140 
  141         /*
  142          * Check that the specified range of the device allows the desired
  143          * protection.
  144          *
  145          * XXX assumes VM_PROT_* == PROT_*
  146          */
  147         npages = OFF_TO_IDX(size);
  148         for (off = foff; npages--; off += PAGE_SIZE)
  149                 if (dev_mmap(csw, dev, off, &paddr, (int)prot, &dummy) != 0) {
  150                         dev_relthread(dev, ref);
  151                         return (NULL);
  152                 }
  153 
  154         mtx_lock(&dev_pager_mtx);
  155 
  156         /*
  157          * Look up pager, creating as necessary.
  158          */
  159         object1 = NULL;
  160         object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  161         if (object == NULL) {
  162                 /*
  163                  * Allocate object and associate it with the pager.  Initialize
  164                  * the object's pg_color based upon the physical address of the
  165                  * device's memory.
  166                  */
  167                 mtx_unlock(&dev_pager_mtx);
  168                 object1 = vm_object_allocate(OBJT_DEVICE, pindex);
  169                 object1->flags |= OBJ_COLORED;
  170                 object1->pg_color = atop(paddr) - OFF_TO_IDX(off - PAGE_SIZE);
  171                 mtx_lock(&dev_pager_mtx);
  172                 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
  173                 if (object != NULL) {
  174                         /*
  175                          * We raced with other thread while allocating object.
  176                          */
  177                         if (pindex > object->size)
  178                                 object->size = pindex;
  179                 } else {
  180                         object = object1;
  181                         object1 = NULL;
  182                         object->handle = handle;
  183                         TAILQ_INIT(&object->un_pager.devp.devp_pglist);
  184                         TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
  185                             pager_object_list);
  186                 }
  187         } else {
  188                 if (pindex > object->size)
  189                         object->size = pindex;
  190         }
  191         mtx_unlock(&dev_pager_mtx);
  192         dev_relthread(dev, ref);
  193         vm_object_deallocate(object1);
  194         return (object);
  195 }
  196 
  197 static void
  198 dev_pager_dealloc(object)
  199         vm_object_t object;
  200 {
  201         vm_page_t m;
  202 
  203         VM_OBJECT_UNLOCK(object);
  204         mtx_lock(&dev_pager_mtx);
  205         TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
  206         mtx_unlock(&dev_pager_mtx);
  207         VM_OBJECT_LOCK(object);
  208         /*
  209          * Free up our fake pages.
  210          */
  211         while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != NULL) {
  212                 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
  213                 dev_pager_putfake(m);
  214         }
  215 }
  216 
  217 static int
  218 dev_pager_getpages(object, m, count, reqpage)
  219         vm_object_t object;
  220         vm_page_t *m;
  221         int count;
  222         int reqpage;
  223 {
  224         vm_pindex_t offset;
  225         vm_paddr_t paddr;
  226         vm_page_t m_paddr, page;
  227         vm_memattr_t memattr;
  228         struct cdev *dev;
  229         int i, ref, ret;
  230         struct cdevsw *csw;
  231         struct thread *td;
  232         struct file *fpop;
  233 
  234         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  235         dev = object->handle;
  236         page = m[reqpage];
  237         offset = page->pindex;
  238         memattr = object->memattr;
  239         VM_OBJECT_UNLOCK(object);
  240         csw = dev_refthread(dev, &ref);
  241         if (csw == NULL)
  242                 panic("dev_pager_getpage: no cdevsw");
  243         td = curthread;
  244         fpop = td->td_fpop;
  245         td->td_fpop = NULL;
  246         ret = dev_mmap(csw, dev, (vm_offset_t)offset << PAGE_SHIFT, &paddr,
  247             PROT_READ, &memattr);
  248         KASSERT(ret == 0, ("dev_pager_getpage: map function returns error"));
  249         td->td_fpop = fpop;
  250         dev_relthread(dev, ref);
  251         /* If "paddr" is a real page, perform a sanity check on "memattr". */
  252         if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
  253             pmap_page_get_memattr(m_paddr) != memattr) {
  254                 memattr = pmap_page_get_memattr(m_paddr);
  255                 printf(
  256             "WARNING: A device driver has set \"memattr\" inconsistently.\n");
  257         }
  258         if ((page->flags & PG_FICTITIOUS) != 0) {
  259                 /*
  260                  * If the passed in reqpage page is a fake page, update it with
  261                  * the new physical address.
  262                  */
  263                 VM_OBJECT_LOCK(object);
  264                 dev_pager_updatefake(page, paddr, memattr);
  265                 if (count > 1) {
  266                         vm_page_lock_queues();
  267                         for (i = 0; i < count; i++) {
  268                                 if (i != reqpage)
  269                                         vm_page_free(m[i]);
  270                         }
  271                         vm_page_unlock_queues();
  272                 }
  273         } else {
  274                 /*
  275                  * Replace the passed in reqpage page with our own fake page and
  276                  * free up the all of the original pages.
  277                  */
  278                 page = dev_pager_getfake(paddr, memattr);
  279                 VM_OBJECT_LOCK(object);
  280                 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
  281                 vm_page_lock_queues();
  282                 for (i = 0; i < count; i++)
  283                         vm_page_free(m[i]);
  284                 vm_page_unlock_queues();
  285                 vm_page_insert(page, object, offset);
  286                 m[reqpage] = page;
  287         }
  288         page->valid = VM_PAGE_BITS_ALL;
  289         return (VM_PAGER_OK);
  290 }
  291 
  292 static void
  293 dev_pager_putpages(object, m, count, sync, rtvals)
  294         vm_object_t object;
  295         vm_page_t *m;
  296         int count;
  297         boolean_t sync;
  298         int *rtvals;
  299 {
  300         panic("dev_pager_putpage called");
  301 }
  302 
  303 static boolean_t
  304 dev_pager_haspage(object, pindex, before, after)
  305         vm_object_t object;
  306         vm_pindex_t pindex;
  307         int *before;
  308         int *after;
  309 {
  310         if (before != NULL)
  311                 *before = 0;
  312         if (after != NULL)
  313                 *after = 0;
  314         return (TRUE);
  315 }
  316 
  317 /*
  318  * Create a fictitious page with the specified physical address and memory
  319  * attribute.  The memory attribute is the only the machine-dependent aspect
  320  * of a fictitious page that must be initialized.
  321  */
  322 static vm_page_t
  323 dev_pager_getfake(vm_paddr_t paddr, vm_memattr_t memattr)
  324 {
  325         vm_page_t m;
  326 
  327         m = uma_zalloc(fakepg_zone, M_WAITOK | M_ZERO);
  328         m->phys_addr = paddr;
  329         /* Fictitious pages don't use "segind". */
  330         m->flags = PG_FICTITIOUS;
  331         /* Fictitious pages don't use "order" or "pool". */
  332         m->oflags = VPO_BUSY;
  333         m->wire_count = 1;
  334         pmap_page_set_memattr(m, memattr);
  335         return (m);
  336 }
  337 
  338 /*
  339  * Release a fictitious page.
  340  */
  341 static void
  342 dev_pager_putfake(vm_page_t m)
  343 {
  344 
  345         if (!(m->flags & PG_FICTITIOUS))
  346                 panic("dev_pager_putfake: bad page");
  347         uma_zfree(fakepg_zone, m);
  348 }
  349 
  350 /*
  351  * Update the given fictitious page to the specified physical address and
  352  * memory attribute.
  353  */
  354 static void
  355 dev_pager_updatefake(vm_page_t m, vm_paddr_t paddr, vm_memattr_t memattr)
  356 {
  357 
  358         if (!(m->flags & PG_FICTITIOUS))
  359                 panic("dev_pager_updatefake: bad page");
  360         m->phys_addr = paddr;
  361         pmap_page_set_memattr(m, memattr);
  362 }
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FreeBSD/Linux Kernel Cross Reference sys/vm/device_pager.c

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