FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_device.c

     /*      $NetBSD: uvm_device.c,v 1.54.8.1 2009/06/23 06:56:52 snj Exp $  */
     
     /*
      *
      * Copyright (c) 1997 Charles D. Cranor and Washington University.
      * All rights reserved.
      *
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Charles D. Cranor and
     *      Washington University.
     * 4. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
     *
     * from: Id: uvm_device.c,v 1.1.2.9 1998/02/06 05:11:47 chs Exp
     */
    
    /*
     * uvm_device.c: the device pager.
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: uvm_device.c,v 1.54.8.1 2009/06/23 06:56:52 snj Exp $");
    
    #include "opt_uvmhist.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/conf.h>
    #include <sys/proc.h>
    #include <sys/malloc.h>
    #include <sys/vnode.h>
    
    #include <uvm/uvm.h>
    #include <uvm/uvm_device.h>
    
    /*
     * private global data structure
     *
     * we keep a list of active device objects in the system.
     */
    
    LIST_HEAD(udv_list_struct, uvm_device);
    static struct udv_list_struct udv_list;
    static kmutex_t udv_lock;
    
    /*
     * functions
     */
    
    static void     udv_init(void);
    static void     udv_reference(struct uvm_object *);
    static void     udv_detach(struct uvm_object *);
    static int      udv_fault(struct uvm_faultinfo *, vaddr_t,
                              struct vm_page **, int, int, vm_prot_t,
                              int);
    
    /*
     * master pager structure
     */
    
    const struct uvm_pagerops uvm_deviceops = {
            .pgo_init = udv_init,
            .pgo_reference = udv_reference,
            .pgo_detach = udv_detach,
            .pgo_fault = udv_fault,
    };
    
    /*
     * the ops!
     */
    
    /*
     * udv_init
     *
     * init pager private data structures.
     */
    
    static void
    udv_init(void)
   {
           LIST_INIT(&udv_list);
           mutex_init(&udv_lock, MUTEX_DEFAULT, IPL_NONE);
   }
   
   /*
    * udv_attach
    *
    * get a VM object that is associated with a device.   allocate a new
    * one if needed.
    *
    * => caller must _not_ already be holding the lock on the uvm_object.
    * => in fact, nothing should be locked so that we can sleep here.
    */
   
   struct uvm_object *
   udv_attach(void *arg, vm_prot_t accessprot,
       voff_t off,         /* used only for access check */
       vsize_t size        /* used only for access check */)
   {
           dev_t device = *((dev_t *)arg);
           struct uvm_device *udv, *lcv;
           const struct cdevsw *cdev;
           dev_type_mmap((*mapfn));
   
           UVMHIST_FUNC("udv_attach"); UVMHIST_CALLED(maphist);
   
           UVMHIST_LOG(maphist, "(device=0x%x)", device,0,0,0);
   
           /*
            * before we do anything, ensure this device supports mmap
            */
   
           cdev = cdevsw_lookup(device);
           if (cdev == NULL) {
                   return (NULL);
           }
           mapfn = cdev->d_mmap;
           if (mapfn == NULL || mapfn == nommap || mapfn == nullmmap) {
                   return(NULL);
           }
   
           /*
            * Negative offsets on the object are not allowed.
            */
   
           if ((cdev->d_flag & D_NEGOFFSAFE) == 0 &&
               off != UVM_UNKNOWN_OFFSET && off < 0)
                   return(NULL);
   
           /*
            * Check that the specified range of the device allows the
            * desired protection.
            *
            * XXX assumes VM_PROT_* == PROT_*
            * XXX clobbers off and size, but nothing else here needs them.
            */
   
           while (size != 0) {
                   if (cdev_mmap(device, off, accessprot) == -1) {
                           return (NULL);
                   }
                   off += PAGE_SIZE; size -= PAGE_SIZE;
           }
   
           /*
            * keep looping until we get it
            */
   
           for (;;) {
   
                   /*
                    * first, attempt to find it on the main list
                    */
   
                   mutex_enter(&udv_lock);
                   LIST_FOREACH(lcv, &udv_list, u_list) {
                           if (device == lcv->u_device)
                                   break;
                   }
   
                   /*
                    * got it on main list.  put a hold on it and unlock udv_lock.
                    */
   
                   if (lcv) {
   
                           /*
                            * if someone else has a hold on it, sleep and start
                            * over again.
                            */
   
                           if (lcv->u_flags & UVM_DEVICE_HOLD) {
                                   lcv->u_flags |= UVM_DEVICE_WANTED;
                                   UVM_UNLOCK_AND_WAIT(lcv, &udv_lock, false,
                                       "udv_attach",0);
                                   continue;
                           }
   
                           /* we are now holding it */
                           lcv->u_flags |= UVM_DEVICE_HOLD;
                           mutex_exit(&udv_lock);
   
                           /*
                            * bump reference count, unhold, return.
                            */
   
                           mutex_enter(&lcv->u_obj.vmobjlock);
                           lcv->u_obj.uo_refs++;
                           mutex_exit(&lcv->u_obj.vmobjlock);
   
                           mutex_enter(&udv_lock);
                           if (lcv->u_flags & UVM_DEVICE_WANTED)
                                   wakeup(lcv);
                           lcv->u_flags &= ~(UVM_DEVICE_WANTED|UVM_DEVICE_HOLD);
                           mutex_exit(&udv_lock);
                           return(&lcv->u_obj);
                   }
   
                   /*
                    * did not find it on main list.   need to malloc a new one.
                    */
   
                   mutex_exit(&udv_lock);
                   /* NOTE: we could sleep in the following malloc() */
                   MALLOC(udv, struct uvm_device *, sizeof(*udv), M_TEMP,
                          M_WAITOK);
                   mutex_enter(&udv_lock);
   
                   /*
                    * now we have to double check to make sure no one added it
                    * to the list while we were sleeping...
                    */
   
                   LIST_FOREACH(lcv, &udv_list, u_list) {
                           if (device == lcv->u_device)
                                   break;
                   }
   
                   /*
                    * did we lose a race to someone else?
                    * free our memory and retry.
                    */
   
                   if (lcv) {
                           mutex_exit(&udv_lock);
                           FREE(udv, M_TEMP);
                           continue;
                   }
   
                   /*
                    * we have it!   init the data structures, add to list
                    * and return.
                    */
   
                   UVM_OBJ_INIT(&udv->u_obj, &uvm_deviceops, 1);
                   udv->u_flags = 0;
                   udv->u_device = device;
                   LIST_INSERT_HEAD(&udv_list, udv, u_list);
                   mutex_exit(&udv_lock);
                   return(&udv->u_obj);
           }
           /*NOTREACHED*/
   }
   
   /*
    * udv_reference
    *
    * add a reference to a VM object.   Note that the reference count must
    * already be one (the passed in reference) so there is no chance of the
    * udv being released or locked out here.
    *
    * => caller must call with object unlocked.
    */
   
   static void
   udv_reference(struct uvm_object *uobj)
   {
           UVMHIST_FUNC("udv_reference"); UVMHIST_CALLED(maphist);
   
           mutex_enter(&uobj->vmobjlock);
           uobj->uo_refs++;
           UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)",
                       uobj, uobj->uo_refs,0,0);
           mutex_exit(&uobj->vmobjlock);
   }
   
   /*
    * udv_detach
    *
    * remove a reference to a VM object.
    *
    * => caller must call with object unlocked and map locked.
    */
   
   static void
   udv_detach(struct uvm_object *uobj)
   {
           struct uvm_device *udv = (struct uvm_device *)uobj;
           UVMHIST_FUNC("udv_detach"); UVMHIST_CALLED(maphist);
   
           /*
            * loop until done
            */
   again:
           mutex_enter(&uobj->vmobjlock);
           if (uobj->uo_refs > 1) {
                   uobj->uo_refs--;
                   mutex_exit(&uobj->vmobjlock);
                   UVMHIST_LOG(maphist," <- done, uobj=0x%x, ref=%d",
                             uobj,uobj->uo_refs,0,0);
                   return;
           }
   
           /*
            * is it being held?   if so, wait until others are done.
            */
   
           mutex_enter(&udv_lock);
           if (udv->u_flags & UVM_DEVICE_HOLD) {
                   udv->u_flags |= UVM_DEVICE_WANTED;
                   mutex_exit(&uobj->vmobjlock);
                   UVM_UNLOCK_AND_WAIT(udv, &udv_lock, false, "udv_detach",0);
                   goto again;
           }
   
           /*
            * got it!   nuke it now.
            */
   
           LIST_REMOVE(udv, u_list);
           if (udv->u_flags & UVM_DEVICE_WANTED)
                   wakeup(udv);
           mutex_exit(&udv_lock);
           mutex_exit(&uobj->vmobjlock);
           UVM_OBJ_DESTROY(uobj);
           FREE(udv, M_TEMP);
           UVMHIST_LOG(maphist," <- done, freed uobj=0x%x", uobj,0,0,0);
   }
   
   /*
    * udv_fault: non-standard fault routine for device "pages"
    *
    * => rather than having a "get" function, we have a fault routine
    *      since we don't return vm_pages we need full control over the
    *      pmap_enter map in
    * => all the usual fault data structured are locked by the caller
    *      (i.e. maps(read), amap (if any), uobj)
    * => on return, we unlock all fault data structures
    * => flags: PGO_ALLPAGES: get all of the pages
    *           PGO_LOCKED: fault data structures are locked
    *    XXX: currently PGO_LOCKED is always required ... consider removing
    *      it as a flag
    * => NOTE: vaddr is the VA of pps[0] in ufi->entry, _NOT_ pps[centeridx]
    */
   
   static int
   udv_fault(struct uvm_faultinfo *ufi, vaddr_t vaddr, struct vm_page **pps,
       int npages, int centeridx, vm_prot_t access_type,
       int flags)
   {
           struct vm_map_entry *entry = ufi->entry;
           struct uvm_object *uobj = entry->object.uvm_obj;
           struct uvm_device *udv = (struct uvm_device *)uobj;
           vaddr_t curr_va;
           off_t curr_offset;
           paddr_t paddr, mdpgno;
           int lcv, retval;
           dev_t device;
           vm_prot_t mapprot;
           UVMHIST_FUNC("udv_fault"); UVMHIST_CALLED(maphist);
           UVMHIST_LOG(maphist,"  flags=%d", flags,0,0,0);
   
           /*
            * we do not allow device mappings to be mapped copy-on-write
            * so we kill any attempt to do so here.
            */
   
           if (UVM_ET_ISCOPYONWRITE(entry)) {
                   UVMHIST_LOG(maphist, "<- failed -- COW entry (etype=0x%x)",
                   entry->etype, 0,0,0);
                   uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL);
                   return(EIO);
           }
   
           /*
            * get device map function.
            */
   
           device = udv->u_device;
           if (cdevsw_lookup(device) == NULL) {
                   /* XXX This should not happen */
                   uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL);
                   return (EIO);
           }
   
           /*
            * now we must determine the offset in udv to use and the VA to
            * use for pmap_enter.  note that we always use orig_map's pmap
            * for pmap_enter (even if we have a submap).   since virtual
            * addresses in a submap must match the main map, this is ok.
            */
   
           /* udv offset = (offset from start of entry) + entry's offset */
           curr_offset = entry->offset + (vaddr - entry->start);
           /* pmap va = vaddr (virtual address of pps[0]) */
           curr_va = vaddr;
   
           /*
            * loop over the page range entering in as needed
            */
   
           retval = 0;
           for (lcv = 0 ; lcv < npages ; lcv++, curr_offset += PAGE_SIZE,
               curr_va += PAGE_SIZE) {
                   if ((flags & PGO_ALLPAGES) == 0 && lcv != centeridx)
                           continue;
   
                   if (pps[lcv] == PGO_DONTCARE)
                           continue;
   
                   mdpgno = cdev_mmap(device, curr_offset, access_type);
                   if (mdpgno == -1) {
                           retval = EIO;
                           break;
                   }
                   paddr = pmap_phys_address(mdpgno);
                   mapprot = ufi->entry->protection;
                   UVMHIST_LOG(maphist,
                       "  MAPPING: device: pm=0x%x, va=0x%x, pa=0x%lx, at=%d",
                       ufi->orig_map->pmap, curr_va, paddr, mapprot);
                   if (pmap_enter(ufi->orig_map->pmap, curr_va, paddr,
                       mapprot, PMAP_CANFAIL | mapprot) != 0) {
                           /*
                            * pmap_enter() didn't have the resource to
                            * enter this mapping.  Unlock everything,
                            * wait for the pagedaemon to free up some
                            * pages, and then tell uvm_fault() to start
                            * the fault again.
                            *
                            * XXX Needs some rethinking for the PGO_ALLPAGES
                            * XXX case.
                            */
                           pmap_update(ufi->orig_map->pmap);       /* sync what we have so far */
                           uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap,
                               uobj, NULL);
                           uvm_wait("udv_fault");
                           return (ERESTART);
                   }
           }
   
           pmap_update(ufi->orig_map->pmap);
           uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap, uobj, NULL);
           return (retval);
   }

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