f455dd6596
define a flag UVM_PGA_USERESERVE to allow non-kernel object allocations to use pages from the reserve. use the new flag for allocations in pmap modules.
752 lines
18 KiB
C
752 lines
18 KiB
C
/* $NetBSD: uvm_loan.c,v 1.15 1999/04/11 04:04:11 chs Exp $ */
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/*
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*
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* Copyright (c) 1997 Charles D. Cranor and Washington University.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Charles D. Cranor and
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* Washington University.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* from: Id: uvm_loan.c,v 1.1.6.4 1998/02/06 05:08:43 chs Exp
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*/
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/*
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* uvm_loan.c: page loanout handler
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/malloc.h>
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#include <sys/mman.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_kern.h>
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#include <uvm/uvm.h>
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/*
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* "loaned" pages are pages which are (read-only, copy-on-write) loaned
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* from the VM system to other parts of the kernel. this allows page
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* copying to be avoided (e.g. you can loan pages from objs/anons to
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* the mbuf system).
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*
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* there are 3 types of loans possible:
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* O->K uvm_object page to wired kernel page (e.g. mbuf data area)
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* A->K anon page to kernel wired kernel page (e.g. mbuf data area)
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* O->A uvm_object to anon loan (e.g. vnode page to an anon)
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* note that it possible to have an O page loaned to both an A and K
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* at the same time.
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*
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* loans are tracked by pg->loan_count. an O->A page will have both
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* a uvm_object and a vm_anon, but PQ_ANON will not be set. this sort
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* of page is considered "owned" by the uvm_object (not the anon).
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*
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* each loan of a page to a wired kernel page bumps the pg->wire_count.
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* wired kernel mappings should be entered with pmap_kenter functions
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* so that pmap_page_protect() will not affect the kernel mappings.
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* (this requires the PMAP_NEW interface...).
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*
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* owners that want to free their pages and discover that they are
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* loaned out simply "disown" them (the page becomes an orphan). these
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* pages should be freed when the last loan is dropped. in some cases
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* an anon may "adopt" an orphaned page.
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*
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* locking: to read pg->loan_count either the owner or the page queues
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* must be locked. to modify pg->loan_count, both the owner of the page
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* and the PQs must be locked. pg->flags is (as always) locked by
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* the owner of the page.
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*
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* note that locking from the "loaned" side is tricky since the object
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* getting the loaned page has no reference to the page's owner and thus
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* the owner could "die" at any time. in order to prevent the owner
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* from dying the page queues should be locked. this forces us to sometimes
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* use "try" locking.
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*
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* loans are typically broken by the following events:
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* 1. write fault to a loaned page
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* 2. pageout of clean+inactive O->A loaned page
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* 3. owner frees page (e.g. pager flush)
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*
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* note that loaning a page causes all mappings of the page to become
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* read-only (via pmap_page_protect). this could have an unexpected
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* effect on normal "wired" pages if one is not careful.
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*/
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/*
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* local prototypes
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*/
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static int uvm_loananon __P((struct uvm_faultinfo *, void ***,
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int, struct vm_anon *));
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static int uvm_loanentry __P((struct uvm_faultinfo *, void ***, int));
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static int uvm_loanuobj __P((struct uvm_faultinfo *, void ***,
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int, vaddr_t));
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static int uvm_loanzero __P((struct uvm_faultinfo *, void ***, int));
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/*
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* inlines
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*/
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/*
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* uvm_loanentry: loan out pages in a map entry (helper fn for uvm_loan())
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*
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* => "ufi" is the result of a successful map lookup (meaning that
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* the maps are locked by the caller)
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* => we may unlock the maps if needed (for I/O)
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* => we put our output result in "output"
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* => we return the number of pages we loaned, or -1 if we had an error
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*/
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static __inline int
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uvm_loanentry(ufi, output, flags)
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struct uvm_faultinfo *ufi;
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void ***output;
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int flags;
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{
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vaddr_t curaddr = ufi->orig_rvaddr;
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vsize_t togo = ufi->size;
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struct vm_aref *aref = &ufi->entry->aref;
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struct uvm_object *uobj = ufi->entry->object.uvm_obj;
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struct vm_anon *anon;
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int rv, result = 0;
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/*
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* lock us the rest of the way down
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*/
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if (aref->ar_amap)
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amap_lock(aref->ar_amap);
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if (uobj)
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simple_lock(&uobj->vmobjlock);
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/*
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* loop until done
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*/
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while (togo) {
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/*
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* find the page we want. check the anon layer first.
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*/
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if (aref->ar_amap) {
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anon = amap_lookup(aref, curaddr - ufi->entry->start);
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} else {
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anon = NULL;
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}
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if (anon) {
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rv = uvm_loananon(ufi, output, flags, anon);
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} else if (uobj) {
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rv = uvm_loanuobj(ufi, output, flags, curaddr);
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} else if (UVM_ET_ISCOPYONWRITE(ufi->entry)) {
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rv = uvm_loanzero(ufi, output, flags);
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} else {
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rv = -1; /* null map entry... fail now */
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}
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/* total failure */
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if (rv < 0)
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return(-1);
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/* relock failed, need to do another lookup */
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if (rv == 0)
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return(result);
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/*
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* got it... advance to next page
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*/
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result++;
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togo -= PAGE_SIZE;
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curaddr += PAGE_SIZE;
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}
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/*
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* unlock everything and return
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*/
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uvmfault_unlockall(ufi, aref->ar_amap, uobj, NULL);
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return(result);
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}
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/*
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* normal functions
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*/
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/*
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* uvm_loan: loan pages out to anons or to the kernel
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*
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* => map should be unlocked
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* => start and len should be multiples of PAGE_SIZE
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* => result is either an array of anon's or vm_pages (depending on flags)
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* => flag values: UVM_LOAN_TOANON - loan to anons
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* UVM_LOAN_TOPAGE - loan to wired kernel page
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* one and only one of these flags must be set!
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*/
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int
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uvm_loan(map, start, len, result, flags)
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struct vm_map *map;
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vaddr_t start;
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vsize_t len;
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void **result;
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int flags;
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{
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struct uvm_faultinfo ufi;
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void **output;
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int rv;
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/*
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* ensure that one and only one of the flags is set
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*/
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if ((flags & (UVM_LOAN_TOANON|UVM_LOAN_TOPAGE)) ==
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(UVM_LOAN_TOANON|UVM_LOAN_TOPAGE) ||
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(flags & (UVM_LOAN_TOANON|UVM_LOAN_TOPAGE)) == 0)
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return(KERN_FAILURE);
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/*
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* "output" is a pointer to the current place to put the loaned
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* page...
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*/
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output = &result[0]; /* start at the beginning ... */
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/*
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* while we've got pages to do
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*/
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while (len > 0) {
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/*
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* fill in params for a call to uvmfault_lookup
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*/
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ufi.orig_map = map;
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ufi.orig_rvaddr = start;
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ufi.orig_size = len;
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/*
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* do the lookup, the only time this will fail is if we hit on
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* an unmapped region (an error)
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*/
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if (!uvmfault_lookup(&ufi, FALSE))
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goto fail;
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/*
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* now do the loanout
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*/
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rv = uvm_loanentry(&ufi, &output, flags);
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if (rv < 0)
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goto fail;
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/*
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* done! advance pointers and unlock.
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*/
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rv <<= PAGE_SHIFT;
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len -= rv;
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start += rv;
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uvmfault_unlockmaps(&ufi, FALSE);
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}
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/*
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* got it! return success.
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*/
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return(KERN_SUCCESS);
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fail:
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/*
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* fail: failed to do it. drop our loans and return failure code.
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*/
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if (output - result) {
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if (flags & UVM_LOAN_TOANON)
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uvm_unloananon((struct vm_anon **)result,
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output - result);
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else
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uvm_unloanpage((struct vm_page **)result,
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output - result);
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}
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return(KERN_FAILURE);
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}
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/*
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* uvm_loananon: loan a page from an anon out
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*
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* => return value:
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* -1 = fatal error, everything is unlocked, abort.
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* 0 = lookup in ufi went stale, everything unlocked, relookup and
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* try again
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* 1 = got it, everything still locked
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*/
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int
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uvm_loananon(ufi, output, flags, anon)
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struct uvm_faultinfo *ufi;
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void ***output;
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int flags;
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struct vm_anon *anon;
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{
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struct vm_page *pg;
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int result;
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/*
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* if we are loaning to another anon then it is easy, we just
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* bump the reference count on the current anon and return a
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* pointer to it.
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*/
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if (flags & UVM_LOAN_TOANON) {
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simple_lock(&anon->an_lock);
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pg = anon->u.an_page;
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if (pg && (pg->pqflags & PQ_ANON) != 0 && anon->an_ref == 1)
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/* read protect it */
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pmap_page_protect(PMAP_PGARG(pg), VM_PROT_READ);
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anon->an_ref++;
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**output = anon;
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*output = (*output) + 1;
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simple_unlock(&anon->an_lock);
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return(1);
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}
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/*
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* we are loaning to a kernel-page. we need to get the page
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* resident so we can wire it. uvmfault_anonget will handle
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* this for us.
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*/
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simple_lock(&anon->an_lock);
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result = uvmfault_anonget(ufi, ufi->entry->aref.ar_amap, anon);
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/*
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* if we were unable to get the anon, then uvmfault_anonget has
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* unlocked everything and returned an error code.
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*/
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if (result != VM_PAGER_OK) {
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/* need to refault (i.e. refresh our lookup) ? */
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if (result == VM_PAGER_REFAULT)
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return(0);
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/* "try again"? sleep a bit and retry ... */
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if (result == VM_PAGER_AGAIN) {
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tsleep((caddr_t)&lbolt, PVM, "loanagain", 0);
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return(0);
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}
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/* otherwise flag it as an error */
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return(-1);
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}
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/*
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* we have the page and its owner locked: do the loan now.
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*/
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pg = anon->u.an_page;
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uvm_lock_pageq();
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if (pg->loan_count == 0)
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pmap_page_protect(PMAP_PGARG(pg), VM_PROT_READ);
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pg->loan_count++;
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uvm_pagewire(pg); /* always wire it */
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uvm_unlock_pageq();
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**output = pg;
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*output = (*output) + 1;
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/* unlock anon and return success */
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if (pg->uobject)
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simple_unlock(&pg->uobject->vmobjlock);
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simple_unlock(&anon->an_lock);
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return(1);
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}
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/*
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* uvm_loanuobj: loan a page from a uobj out
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*
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* => return value:
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* -1 = fatal error, everything is unlocked, abort.
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* 0 = lookup in ufi went stale, everything unlocked, relookup and
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* try again
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* 1 = got it, everything still locked
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*/
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int
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uvm_loanuobj(ufi, output, flags, va)
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struct uvm_faultinfo *ufi;
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void ***output;
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int flags;
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vaddr_t va;
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{
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struct vm_amap *amap = ufi->entry->aref.ar_amap;
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struct uvm_object *uobj = ufi->entry->object.uvm_obj;
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struct vm_page *pg;
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struct vm_anon *anon;
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int result, npages;
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boolean_t locked;
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/*
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* first we must make sure the page is resident.
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*
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* XXXCDC: duplicate code with uvm_fault().
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*/
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if (uobj->pgops->pgo_get) {
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npages = 1;
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pg = NULL;
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result = uobj->pgops->pgo_get(uobj, va - ufi->entry->start,
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&pg, &npages, 0, VM_PROT_READ, MADV_NORMAL, PGO_LOCKED);
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} else {
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result = VM_PAGER_ERROR;
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}
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/*
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* check the result of the locked pgo_get. if there is a problem,
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* then we fail the loan.
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*/
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if (result != VM_PAGER_OK && result != VM_PAGER_UNLOCK) {
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uvmfault_unlockall(ufi, amap, uobj, NULL);
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return(-1);
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}
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/*
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* if we need to unlock for I/O, do so now.
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*/
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if (result == VM_PAGER_UNLOCK) {
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uvmfault_unlockall(ufi, amap, NULL, NULL);
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npages = 1;
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/* locked: uobj */
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result = uobj->pgops->pgo_get(uobj, va - ufi->entry->start,
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&pg, &npages, 0, VM_PROT_READ, MADV_NORMAL, 0);
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/* locked: <nothing> */
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/*
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* check for errors
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*/
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if (result != VM_PAGER_OK) {
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if (result == VM_PAGER_AGAIN) {
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tsleep((caddr_t)&lbolt, PVM, "fltagain2", 0);
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return(0); /* redo the lookup and try again */
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}
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return(-1); /* total failure */
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}
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/*
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* pgo_get was a success. attempt to relock everything.
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*/
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locked = uvmfault_relock(ufi);
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if (locked && amap)
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amap_lock(amap);
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simple_lock(&uobj->vmobjlock);
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/*
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* verify that the page has not be released and re-verify
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* that amap slot is still free. if there is a problem we
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* drop our lock (thus force a lookup refresh/retry).
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*/
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if ((pg->flags & PG_RELEASED) != 0 ||
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(locked && amap && amap_lookup(&ufi->entry->aref,
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ufi->orig_rvaddr - ufi->entry->start))) {
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if (locked)
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uvmfault_unlockall(ufi, amap, NULL, NULL);
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locked = FALSE;
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}
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/*
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* didn't get the lock? release the page and retry.
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*/
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if (locked == FALSE) {
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if (pg->flags & PG_WANTED)
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/* still holding object lock */
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thread_wakeup(pg);
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if (pg->flags & PG_RELEASED) {
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#ifdef DIAGNOSTIC
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if (uobj->pgops->pgo_releasepg == NULL)
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panic("uvm_loanuobj: object has no releasepg function");
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#endif
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/* frees page */
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if (uobj->pgops->pgo_releasepg(pg, NULL))
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simple_unlock(&uobj->vmobjlock);
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return (0);
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}
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uvm_lock_pageq();
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uvm_pageactivate(pg); /* make sure it is in queues */
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uvm_unlock_pageq();
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pg->flags &= ~(PG_BUSY|PG_WANTED);
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UVM_PAGE_OWN(pg, NULL);
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simple_unlock(&uobj->vmobjlock);
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return (0);
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}
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}
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/*
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* at this point we have the page we want ("pg") marked PG_BUSY for us
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* and we have all data structures locked. do the loanout. page can
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* not be PG_RELEASED (we caught this above).
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*/
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if ((flags & UVM_LOAN_TOANON) == 0) { /* loan to wired-kernel page? */
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uvm_lock_pageq();
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if (pg->loan_count == 0)
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pmap_page_protect(PMAP_PGARG(pg), VM_PROT_READ);
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pg->loan_count++;
|
|
uvm_pagewire(pg);
|
|
uvm_unlock_pageq();
|
|
**output = pg;
|
|
*output = (*output) + 1;
|
|
if (pg->flags & PG_WANTED)
|
|
thread_wakeup(pg);
|
|
pg->flags &= ~(PG_WANTED|PG_BUSY);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
return(1); /* got it! */
|
|
}
|
|
|
|
/*
|
|
* must be a loan to an anon. check to see if there is already
|
|
* an anon associated with this page. if so, then just return
|
|
* a reference to this object. the page should already be
|
|
* mapped read-only because it is already on loan.
|
|
*/
|
|
|
|
if (pg->uanon) {
|
|
anon = pg->uanon;
|
|
simple_lock(&anon->an_lock);
|
|
anon->an_ref++;
|
|
simple_unlock(&anon->an_lock);
|
|
**output = anon;
|
|
*output = (*output) + 1;
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(pg); /* reactivate */
|
|
uvm_unlock_pageq();
|
|
if (pg->flags & PG_WANTED)
|
|
thread_wakeup(pg);
|
|
pg->flags &= ~(PG_WANTED|PG_BUSY);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
return(1);
|
|
}
|
|
|
|
/*
|
|
* need to allocate a new anon
|
|
*/
|
|
|
|
anon = uvm_analloc();
|
|
if (anon == NULL) { /* out of VM! */
|
|
if (pg->flags & PG_WANTED)
|
|
thread_wakeup(pg);
|
|
pg->flags &= ~(PG_WANTED|PG_BUSY);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
uvmfault_unlockall(ufi, amap, uobj, NULL);
|
|
return(-1);
|
|
}
|
|
anon->u.an_page = pg;
|
|
pg->uanon = anon;
|
|
uvm_lock_pageq();
|
|
if (pg->loan_count == 0)
|
|
pmap_page_protect(PMAP_PGARG(pg), VM_PROT_READ);
|
|
pg->loan_count++;
|
|
uvm_pageactivate(pg);
|
|
uvm_unlock_pageq();
|
|
**output = anon;
|
|
*output = (*output) + 1;
|
|
if (pg->flags & PG_WANTED)
|
|
thread_wakeup(pg);
|
|
pg->flags &= ~(PG_WANTED|PG_BUSY);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
return(1);
|
|
}
|
|
|
|
/*
|
|
* uvm_loanzero: "loan" a zero-fill page out
|
|
*
|
|
* => return value:
|
|
* -1 = fatal error, everything is unlocked, abort.
|
|
* 0 = lookup in ufi went stale, everything unlocked, relookup and
|
|
* try again
|
|
* 1 = got it, everything still locked
|
|
*/
|
|
|
|
int
|
|
uvm_loanzero(ufi, output, flags)
|
|
struct uvm_faultinfo *ufi;
|
|
void ***output;
|
|
int flags;
|
|
{
|
|
struct vm_anon *anon;
|
|
struct vm_page *pg;
|
|
|
|
if ((flags & UVM_LOAN_TOANON) == 0) { /* loaning to kernel-page */
|
|
|
|
while ((pg = uvm_pagealloc(NULL, 0, NULL, 0)) == NULL) {
|
|
uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap,
|
|
ufi->entry->object.uvm_obj, NULL);
|
|
uvm_wait("loanzero1");
|
|
if (!uvmfault_relock(ufi))
|
|
return(0);
|
|
if (ufi->entry->aref.ar_amap)
|
|
amap_lock(ufi->entry->aref.ar_amap);
|
|
if (ufi->entry->object.uvm_obj)
|
|
simple_lock(
|
|
&ufi->entry->object.uvm_obj->vmobjlock);
|
|
/* ... and try again */
|
|
}
|
|
|
|
/* got a page, zero it and return */
|
|
uvm_pagezero(pg); /* clears PG_CLEAN */
|
|
pg->flags &= ~(PG_BUSY|PG_FAKE);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
**output = pg;
|
|
*output = (*output) + 1;
|
|
uvm_lock_pageq();
|
|
/* wire it as we are loaning to kernel-page */
|
|
uvm_pagewire(pg);
|
|
pg->loan_count = 1;
|
|
uvm_unlock_pageq();
|
|
return(1);
|
|
}
|
|
|
|
/* loaning to an anon */
|
|
while ((anon = uvm_analloc()) == NULL ||
|
|
(pg = uvm_pagealloc(NULL, 0, anon, 0)) == NULL) {
|
|
|
|
/* unlock everything */
|
|
uvmfault_unlockall(ufi, ufi->entry->aref.ar_amap,
|
|
ufi->entry->object.uvm_obj, NULL);
|
|
|
|
/* out of swap causes us to fail */
|
|
if (anon == NULL)
|
|
return(-1);
|
|
|
|
uvm_anfree(anon);
|
|
uvm_wait("loanzero2"); /* wait for pagedaemon */
|
|
|
|
if (!uvmfault_relock(ufi))
|
|
/* map changed while unlocked, need relookup */
|
|
return (0);
|
|
|
|
/* relock everything else */
|
|
if (ufi->entry->aref.ar_amap)
|
|
amap_lock(ufi->entry->aref.ar_amap);
|
|
if (ufi->entry->object.uvm_obj)
|
|
simple_lock(&ufi->entry->object.uvm_obj->vmobjlock);
|
|
/* ... and try again */
|
|
}
|
|
|
|
/* got a page, zero it and return */
|
|
uvm_pagezero(pg); /* clears PG_CLEAN */
|
|
pg->flags &= ~(PG_BUSY|PG_FAKE);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(pg);
|
|
uvm_unlock_pageq();
|
|
**output = anon;
|
|
*output = (*output) + 1;
|
|
return(1);
|
|
}
|
|
|
|
|
|
/*
|
|
* uvm_unloananon: kill loans on anons (basically a normal ref drop)
|
|
*
|
|
* => we expect all our resources to be unlocked
|
|
*/
|
|
|
|
void
|
|
uvm_unloananon(aloans, nanons)
|
|
struct vm_anon **aloans;
|
|
int nanons;
|
|
{
|
|
struct vm_anon *anon;
|
|
|
|
while (nanons-- > 0) {
|
|
int refs;
|
|
|
|
anon = *aloans++;
|
|
simple_lock(&anon->an_lock);
|
|
refs = --anon->an_ref;
|
|
simple_unlock(&anon->an_lock);
|
|
|
|
if (refs == 0) {
|
|
uvm_anfree(anon); /* last reference: kill anon */
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* uvm_unloanpage: kill loans on pages loaned out to the kernel
|
|
*
|
|
* => we expect all our resources to be unlocked
|
|
*/
|
|
|
|
void
|
|
uvm_unloanpage(ploans, npages)
|
|
struct vm_page **ploans;
|
|
int npages;
|
|
{
|
|
struct vm_page *pg;
|
|
|
|
uvm_lock_pageq();
|
|
|
|
while (npages-- > 0) {
|
|
pg = *ploans++;
|
|
|
|
if (pg->loan_count < 1)
|
|
panic("uvm_unloanpage: page %p isn't loaned", pg);
|
|
|
|
pg->loan_count--; /* drop loan */
|
|
uvm_pageunwire(pg); /* and wire */
|
|
|
|
/*
|
|
* if page is unowned and we killed last loan, then we can
|
|
* free it
|
|
*/
|
|
if (pg->loan_count == 0 && pg->uobject == NULL &&
|
|
pg->uanon == NULL) {
|
|
|
|
if (pg->flags & PG_BUSY)
|
|
panic("uvm_unloanpage: page %p unowned but PG_BUSY!", pg);
|
|
|
|
/* be safe */
|
|
pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE);
|
|
uvm_pagefree(pg); /* pageq locked above */
|
|
|
|
}
|
|
}
|
|
|
|
uvm_unlock_pageq();
|
|
}
|
|
|