1849 lines
48 KiB
C
1849 lines
48 KiB
C
/* $OpenBSD: uvm_fault.c,v 1.135 2023/09/05 05:08:26 guenther Exp $ */
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/* $NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 thorpej Exp $ */
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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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*
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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_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp
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*/
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/*
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* uvm_fault.c: fault 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/percpu.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 <sys/tracepoint.h>
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#include <uvm/uvm.h>
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/*
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*
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* a word on page faults:
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*
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* types of page faults we handle:
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*
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* CASE 1: upper layer faults CASE 2: lower layer faults
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*
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* CASE 1A CASE 1B CASE 2A CASE 2B
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* read/write1 write>1 read/write +-cow_write/zero
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* | | | |
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* +--|--+ +--|--+ +-----+ + | + | +-----+
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* amap | V | | ---------> new | | | | ^ |
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* +-----+ +-----+ +-----+ + | + | +--|--+
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* | | |
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* +-----+ +-----+ +--|--+ | +--|--+
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* uobj | d/c | | d/c | | V | +----+ |
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* +-----+ +-----+ +-----+ +-----+
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*
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* d/c = don't care
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*
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* case [0]: layerless fault
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* no amap or uobj is present. this is an error.
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*
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* case [1]: upper layer fault [anon active]
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* 1A: [read] or [write with anon->an_ref == 1]
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* I/O takes place in upper level anon and uobj is not touched.
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* 1B: [write with anon->an_ref > 1]
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* new anon is alloc'd and data is copied off ["COW"]
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*
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* case [2]: lower layer fault [uobj]
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* 2A: [read on non-NULL uobj] or [write to non-copy_on_write area]
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* I/O takes place directly in object.
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* 2B: [write to copy_on_write] or [read on NULL uobj]
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* data is "promoted" from uobj to a new anon.
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* if uobj is null, then we zero fill.
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*
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* we follow the standard UVM locking protocol ordering:
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*
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* MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ)
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* we hold a PG_BUSY page if we unlock for I/O
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*
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*
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* the code is structured as follows:
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*
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* - init the "IN" params in the ufi structure
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* ReFault: (ERESTART returned to the loop in uvm_fault)
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* - do lookups [locks maps], check protection, handle needs_copy
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* - check for case 0 fault (error)
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* - establish "range" of fault
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* - if we have an amap lock it and extract the anons
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* - if sequential advice deactivate pages behind us
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* - at the same time check pmap for unmapped areas and anon for pages
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* that we could map in (and do map it if found)
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* - check object for resident pages that we could map in
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* - if (case 2) goto Case2
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* - >>> handle case 1
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* - ensure source anon is resident in RAM
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* - if case 1B alloc new anon and copy from source
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* - map the correct page in
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* Case2:
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* - >>> handle case 2
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* - ensure source page is resident (if uobj)
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* - if case 2B alloc new anon and copy from source (could be zero
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* fill if uobj == NULL)
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* - map the correct page in
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* - done!
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*
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* note on paging:
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* if we have to do I/O we place a PG_BUSY page in the correct object,
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* unlock everything, and do the I/O. when I/O is done we must reverify
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* the state of the world before assuming that our data structures are
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* valid. [because mappings could change while the map is unlocked]
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*
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* alternative 1: unbusy the page in question and restart the page fault
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* from the top (ReFault). this is easy but does not take advantage
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* of the information that we already have from our previous lookup,
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* although it is possible that the "hints" in the vm_map will help here.
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*
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* alternative 2: the system already keeps track of a "version" number of
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* a map. [i.e. every time you write-lock a map (e.g. to change a
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* mapping) you bump the version number up by one...] so, we can save
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* the version number of the map before we release the lock and start I/O.
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* then when I/O is done we can relock and check the version numbers
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* to see if anything changed. this might save us some over 1 because
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* we don't have to unbusy the page and may be less compares(?).
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*
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* alternative 3: put in backpointers or a way to "hold" part of a map
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* in place while I/O is in progress. this could be complex to
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* implement (especially with structures like amap that can be referenced
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* by multiple map entries, and figuring out what should wait could be
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* complex as well...).
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*
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* we use alternative 2. given that we are multi-threaded now we may want
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* to reconsider the choice.
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*/
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/*
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* local data structures
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*/
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struct uvm_advice {
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int nback;
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int nforw;
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};
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/*
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* page range array: set up in uvmfault_init().
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*/
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static struct uvm_advice uvmadvice[MADV_MASK + 1];
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#define UVM_MAXRANGE 16 /* must be max() of nback+nforw+1 */
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/*
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* private prototypes
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*/
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static void uvmfault_amapcopy(struct uvm_faultinfo *);
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static inline void uvmfault_anonflush(struct vm_anon **, int);
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void uvmfault_unlockmaps(struct uvm_faultinfo *, boolean_t);
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void uvmfault_update_stats(struct uvm_faultinfo *);
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/*
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* inline functions
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*/
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/*
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* uvmfault_anonflush: try and deactivate pages in specified anons
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*
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* => does not have to deactivate page if it is busy
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*/
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static inline void
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uvmfault_anonflush(struct vm_anon **anons, int n)
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{
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int lcv;
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struct vm_page *pg;
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for (lcv = 0; lcv < n; lcv++) {
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if (anons[lcv] == NULL)
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continue;
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KASSERT(rw_lock_held(anons[lcv]->an_lock));
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pg = anons[lcv]->an_page;
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if (pg && (pg->pg_flags & PG_BUSY) == 0) {
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uvm_lock_pageq();
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if (pg->wire_count == 0) {
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pmap_page_protect(pg, PROT_NONE);
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uvm_pagedeactivate(pg);
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}
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uvm_unlock_pageq();
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}
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}
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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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* uvmfault_init: compute proper values for the uvmadvice[] array.
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*/
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void
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uvmfault_init(void)
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{
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int npages;
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npages = atop(16384);
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if (npages > 0) {
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KASSERT(npages <= UVM_MAXRANGE / 2);
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uvmadvice[MADV_NORMAL].nforw = npages;
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uvmadvice[MADV_NORMAL].nback = npages - 1;
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}
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npages = atop(32768);
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if (npages > 0) {
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KASSERT(npages <= UVM_MAXRANGE / 2);
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uvmadvice[MADV_SEQUENTIAL].nforw = npages - 1;
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uvmadvice[MADV_SEQUENTIAL].nback = npages;
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}
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}
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/*
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* uvmfault_amapcopy: clear "needs_copy" in a map.
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*
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* => called with VM data structures unlocked (usually, see below)
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* => we get a write lock on the maps and clear needs_copy for a VA
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* => if we are out of RAM we sleep (waiting for more)
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*/
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static void
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uvmfault_amapcopy(struct uvm_faultinfo *ufi)
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{
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for (;;) {
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/*
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* no mapping? give up.
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*/
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if (uvmfault_lookup(ufi, TRUE) == FALSE)
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return;
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/*
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* copy if needed.
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*/
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if (UVM_ET_ISNEEDSCOPY(ufi->entry))
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amap_copy(ufi->map, ufi->entry, M_NOWAIT,
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UVM_ET_ISSTACK(ufi->entry) ? FALSE : TRUE,
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ufi->orig_rvaddr, ufi->orig_rvaddr + 1);
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/*
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* didn't work? must be out of RAM. unlock and sleep.
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*/
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if (UVM_ET_ISNEEDSCOPY(ufi->entry)) {
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uvmfault_unlockmaps(ufi, TRUE);
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uvm_wait("fltamapcopy");
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continue;
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}
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/*
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* got it! unlock and return.
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*/
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uvmfault_unlockmaps(ufi, TRUE);
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return;
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}
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/*NOTREACHED*/
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}
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/*
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* uvmfault_anonget: get data in an anon into a non-busy, non-released
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* page in that anon.
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*
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* => Map, amap and thus anon should be locked by caller.
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* => If we fail, we unlock everything and error is returned.
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* => If we are successful, return with everything still locked.
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* => We do not move the page on the queues [gets moved later]. If we
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* allocate a new page [we_own], it gets put on the queues. Either way,
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* the result is that the page is on the queues at return time
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*/
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int
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uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
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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 error;
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KASSERT(rw_lock_held(anon->an_lock));
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KASSERT(anon->an_lock == amap->am_lock);
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/* Increment the counters.*/
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counters_inc(uvmexp_counters, flt_anget);
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if (anon->an_page) {
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curproc->p_ru.ru_minflt++;
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} else {
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curproc->p_ru.ru_majflt++;
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}
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error = 0;
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/*
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* Loop until we get the anon data, or fail.
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*/
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for (;;) {
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boolean_t we_own, locked;
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/*
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* Note: 'we_own' will become true if we set PG_BUSY on a page.
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*/
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we_own = FALSE;
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pg = anon->an_page;
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/*
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* Is page resident? Make sure it is not busy/released.
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*/
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if (pg) {
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KASSERT(pg->pg_flags & PQ_ANON);
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KASSERT(pg->uanon == anon);
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/*
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* if the page is busy, we drop all the locks and
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* try again.
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*/
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if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0)
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return (VM_PAGER_OK);
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atomic_setbits_int(&pg->pg_flags, PG_WANTED);
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counters_inc(uvmexp_counters, flt_pgwait);
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/*
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* The last unlock must be an atomic unlock and wait
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* on the owner of page.
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*/
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if (pg->uobject) {
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/* Owner of page is UVM object. */
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uvmfault_unlockall(ufi, amap, NULL);
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rwsleep_nsec(pg, pg->uobject->vmobjlock,
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PVM | PNORELOCK, "anonget1", INFSLP);
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} else {
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/* Owner of page is anon. */
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uvmfault_unlockall(ufi, NULL, NULL);
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rwsleep_nsec(pg, anon->an_lock, PVM | PNORELOCK,
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"anonget2", INFSLP);
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}
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} else {
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/*
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* No page, therefore allocate one.
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*/
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pg = uvm_pagealloc(NULL, 0, anon, 0);
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if (pg == NULL) {
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/* Out of memory. Wait a little. */
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uvmfault_unlockall(ufi, amap, NULL);
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counters_inc(uvmexp_counters, flt_noram);
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uvm_wait("flt_noram1");
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} else {
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/* PG_BUSY bit is set. */
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we_own = TRUE;
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uvmfault_unlockall(ufi, amap, NULL);
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/*
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* Pass a PG_BUSY+PG_FAKE+PG_CLEAN page into
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* the uvm_swap_get() function with all data
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* structures unlocked. Note that it is OK
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* to read an_swslot here, because we hold
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* PG_BUSY on the page.
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*/
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counters_inc(uvmexp_counters, pageins);
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error = uvm_swap_get(pg, anon->an_swslot,
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PGO_SYNCIO);
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/*
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* We clean up after the I/O below in the
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* 'we_own' case.
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*/
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}
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}
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/*
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* Re-lock the map and anon.
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*/
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locked = uvmfault_relock(ufi);
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if (locked || we_own) {
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rw_enter(anon->an_lock, RW_WRITE);
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}
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/*
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* If we own the page (i.e. we set PG_BUSY), then we need
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* to clean up after the I/O. There are three cases to
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* consider:
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*
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* 1) Page was released during I/O: free anon and ReFault.
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* 2) I/O not OK. Free the page and cause the fault to fail.
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* 3) I/O OK! Activate the page and sync with the non-we_own
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* case (i.e. drop anon lock if not locked).
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*/
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if (we_own) {
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if (pg->pg_flags & PG_WANTED) {
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wakeup(pg);
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}
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/*
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* if we were RELEASED during I/O, then our anon is
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* no longer part of an amap. we need to free the
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* anon and try again.
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*/
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if (pg->pg_flags & PG_RELEASED) {
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KASSERT(anon->an_ref == 0);
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/*
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* Released while we had unlocked amap.
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*/
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if (locked)
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uvmfault_unlockall(ufi, NULL, NULL);
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uvm_anon_release(anon); /* frees page for us */
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counters_inc(uvmexp_counters, flt_pgrele);
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return (VM_PAGER_REFAULT); /* refault! */
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}
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if (error != VM_PAGER_OK) {
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KASSERT(error != VM_PAGER_PEND);
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/* remove page from anon */
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anon->an_page = NULL;
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/*
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* Remove the swap slot from the anon and
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* mark the anon as having no real slot.
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* Do not free the swap slot, thus preventing
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* it from being used again.
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*/
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uvm_swap_markbad(anon->an_swslot, 1);
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anon->an_swslot = SWSLOT_BAD;
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/*
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* Note: page was never !PG_BUSY, so it
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* cannot be mapped and thus no need to
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* pmap_page_protect() it.
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*/
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uvm_lock_pageq();
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uvm_pagefree(pg);
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uvm_unlock_pageq();
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if (locked) {
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uvmfault_unlockall(ufi, NULL, NULL);
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}
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rw_exit(anon->an_lock);
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return (VM_PAGER_ERROR);
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}
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/*
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* We have successfully read the page, activate it.
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*/
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pmap_clear_modify(pg);
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uvm_lock_pageq();
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uvm_pageactivate(pg);
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uvm_unlock_pageq();
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atomic_clearbits_int(&pg->pg_flags,
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PG_WANTED|PG_BUSY|PG_FAKE);
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UVM_PAGE_OWN(pg, NULL);
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}
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/*
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* We were not able to re-lock the map - restart the fault.
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*/
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if (!locked) {
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if (we_own) {
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rw_exit(anon->an_lock);
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}
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return (VM_PAGER_REFAULT);
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}
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/*
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* Verify that no one has touched the amap and moved
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* the anon on us.
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*/
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if (ufi != NULL && amap_lookup(&ufi->entry->aref,
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ufi->orig_rvaddr - ufi->entry->start) != anon) {
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uvmfault_unlockall(ufi, amap, NULL);
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return (VM_PAGER_REFAULT);
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}
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/*
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* Retry..
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*/
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counters_inc(uvmexp_counters, flt_anretry);
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continue;
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}
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/*NOTREACHED*/
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}
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/*
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* Update statistics after fault resolution.
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* - maxrss
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*/
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void
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uvmfault_update_stats(struct uvm_faultinfo *ufi)
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{
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struct vm_map *map;
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struct proc *p;
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vsize_t res;
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map = ufi->orig_map;
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/*
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* If this is a nested pmap (eg, a virtual machine pmap managed
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* by vmm(4) on amd64/i386), don't do any updating, just return.
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*
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* pmap_nested() on other archs is #defined to 0, so this is a
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* no-op.
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*/
|
|
if (pmap_nested(map->pmap))
|
|
return;
|
|
|
|
/* Update the maxrss for the process. */
|
|
if (map->flags & VM_MAP_ISVMSPACE) {
|
|
p = curproc;
|
|
KASSERT(p != NULL && &p->p_vmspace->vm_map == map);
|
|
|
|
res = pmap_resident_count(map->pmap);
|
|
/* Convert res from pages to kilobytes. */
|
|
res <<= (PAGE_SHIFT - 10);
|
|
|
|
if (p->p_ru.ru_maxrss < res)
|
|
p->p_ru.ru_maxrss = res;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* F A U L T - m a i n e n t r y p o i n t
|
|
*/
|
|
|
|
/*
|
|
* uvm_fault: page fault handler
|
|
*
|
|
* => called from MD code to resolve a page fault
|
|
* => VM data structures usually should be unlocked. however, it is
|
|
* possible to call here with the main map locked if the caller
|
|
* gets a write lock, sets it recursive, and then calls us (c.f.
|
|
* uvm_map_pageable). this should be avoided because it keeps
|
|
* the map locked off during I/O.
|
|
* => MUST NEVER BE CALLED IN INTERRUPT CONTEXT
|
|
*/
|
|
#define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \
|
|
~PROT_WRITE : PROT_MASK)
|
|
struct uvm_faultctx {
|
|
/*
|
|
* the following members are set up by uvm_fault_check() and
|
|
* read-only after that.
|
|
*/
|
|
vm_prot_t enter_prot;
|
|
vm_prot_t access_type;
|
|
vaddr_t startva;
|
|
int npages;
|
|
int centeridx;
|
|
boolean_t narrow;
|
|
boolean_t wired;
|
|
paddr_t pa_flags;
|
|
};
|
|
|
|
int uvm_fault_check(
|
|
struct uvm_faultinfo *, struct uvm_faultctx *,
|
|
struct vm_anon ***);
|
|
|
|
int uvm_fault_upper(
|
|
struct uvm_faultinfo *, struct uvm_faultctx *,
|
|
struct vm_anon **, vm_fault_t);
|
|
boolean_t uvm_fault_upper_lookup(
|
|
struct uvm_faultinfo *, const struct uvm_faultctx *,
|
|
struct vm_anon **, struct vm_page **);
|
|
|
|
int uvm_fault_lower(
|
|
struct uvm_faultinfo *, struct uvm_faultctx *,
|
|
struct vm_page **, vm_fault_t);
|
|
|
|
int
|
|
uvm_fault(vm_map_t orig_map, vaddr_t vaddr, vm_fault_t fault_type,
|
|
vm_prot_t access_type)
|
|
{
|
|
struct uvm_faultinfo ufi;
|
|
struct uvm_faultctx flt;
|
|
boolean_t shadowed;
|
|
struct vm_anon *anons_store[UVM_MAXRANGE], **anons;
|
|
struct vm_page *pages[UVM_MAXRANGE];
|
|
int error;
|
|
|
|
counters_inc(uvmexp_counters, faults);
|
|
TRACEPOINT(uvm, fault, vaddr, fault_type, access_type, NULL);
|
|
|
|
/*
|
|
* init the IN parameters in the ufi
|
|
*/
|
|
ufi.orig_map = orig_map;
|
|
ufi.orig_rvaddr = trunc_page(vaddr);
|
|
ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */
|
|
if (fault_type == VM_FAULT_WIRE)
|
|
flt.narrow = TRUE; /* don't look for neighborhood
|
|
* pages on wire */
|
|
else
|
|
flt.narrow = FALSE; /* normal fault */
|
|
flt.access_type = access_type;
|
|
|
|
|
|
error = ERESTART;
|
|
while (error == ERESTART) { /* ReFault: */
|
|
anons = anons_store;
|
|
|
|
error = uvm_fault_check(&ufi, &flt, &anons);
|
|
if (error != 0)
|
|
continue;
|
|
|
|
/* True if there is an anon at the faulting address */
|
|
shadowed = uvm_fault_upper_lookup(&ufi, &flt, anons, pages);
|
|
if (shadowed == TRUE) {
|
|
/* case 1: fault on an anon in our amap */
|
|
error = uvm_fault_upper(&ufi, &flt, anons, fault_type);
|
|
} else {
|
|
struct uvm_object *uobj = ufi.entry->object.uvm_obj;
|
|
|
|
/*
|
|
* if the desired page is not shadowed by the amap and
|
|
* we have a backing object, then we check to see if
|
|
* the backing object would prefer to handle the fault
|
|
* itself (rather than letting us do it with the usual
|
|
* pgo_get hook). the backing object signals this by
|
|
* providing a pgo_fault routine.
|
|
*/
|
|
if (uobj != NULL && uobj->pgops->pgo_fault != NULL) {
|
|
KERNEL_LOCK();
|
|
rw_enter(uobj->vmobjlock, RW_WRITE);
|
|
error = uobj->pgops->pgo_fault(&ufi,
|
|
flt.startva, pages, flt.npages,
|
|
flt.centeridx, fault_type, flt.access_type,
|
|
PGO_LOCKED);
|
|
KERNEL_UNLOCK();
|
|
|
|
if (error == VM_PAGER_OK)
|
|
error = 0;
|
|
else if (error == VM_PAGER_REFAULT)
|
|
error = ERESTART;
|
|
else
|
|
error = EACCES;
|
|
} else {
|
|
/* case 2: fault on backing obj or zero fill */
|
|
error = uvm_fault_lower(&ufi, &flt, pages,
|
|
fault_type);
|
|
}
|
|
}
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_check: check prot, handle needs-copy, etc.
|
|
*
|
|
* 1. lookup entry.
|
|
* 2. check protection.
|
|
* 3. adjust fault condition (mainly for simulated fault).
|
|
* 4. handle needs-copy (lazy amap copy).
|
|
* 5. establish range of interest for neighbor fault (aka pre-fault).
|
|
* 6. look up anons (if amap exists).
|
|
* 7. flush pages (if MADV_SEQUENTIAL)
|
|
*
|
|
* => called with nothing locked.
|
|
* => if we fail (result != 0) we unlock everything.
|
|
* => initialize/adjust many members of flt.
|
|
*/
|
|
int
|
|
uvm_fault_check(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
|
|
struct vm_anon ***ranons)
|
|
{
|
|
struct vm_amap *amap;
|
|
struct uvm_object *uobj;
|
|
int nback, nforw;
|
|
|
|
/*
|
|
* lookup and lock the maps
|
|
*/
|
|
if (uvmfault_lookup(ufi, FALSE) == FALSE) {
|
|
return EFAULT;
|
|
}
|
|
/* locked: maps(read) */
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0)
|
|
panic("uvm_fault: fault on non-pageable map (%p, 0x%lx)",
|
|
ufi->map, ufi->orig_rvaddr);
|
|
#endif
|
|
|
|
/*
|
|
* check protection
|
|
*/
|
|
if ((ufi->entry->protection & flt->access_type) != flt->access_type) {
|
|
uvmfault_unlockmaps(ufi, FALSE);
|
|
return EACCES;
|
|
}
|
|
|
|
/*
|
|
* "enter_prot" is the protection we want to enter the page in at.
|
|
* for certain pages (e.g. copy-on-write pages) this protection can
|
|
* be more strict than ufi->entry->protection. "wired" means either
|
|
* the entry is wired or we are fault-wiring the pg.
|
|
*/
|
|
|
|
flt->enter_prot = ufi->entry->protection;
|
|
flt->pa_flags = UVM_ET_ISWC(ufi->entry) ? PMAP_WC : 0;
|
|
flt->wired = VM_MAPENT_ISWIRED(ufi->entry) || (flt->narrow == TRUE);
|
|
if (flt->wired)
|
|
flt->access_type = flt->enter_prot; /* full access for wired */
|
|
|
|
/* handle "needs_copy" case. */
|
|
if (UVM_ET_ISNEEDSCOPY(ufi->entry)) {
|
|
if ((flt->access_type & PROT_WRITE) ||
|
|
(ufi->entry->object.uvm_obj == NULL)) {
|
|
/* need to clear */
|
|
uvmfault_unlockmaps(ufi, FALSE);
|
|
uvmfault_amapcopy(ufi);
|
|
counters_inc(uvmexp_counters, flt_amcopy);
|
|
return ERESTART;
|
|
} else {
|
|
/*
|
|
* ensure that we pmap_enter page R/O since
|
|
* needs_copy is still true
|
|
*/
|
|
flt->enter_prot &= ~PROT_WRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* identify the players
|
|
*/
|
|
amap = ufi->entry->aref.ar_amap; /* upper layer */
|
|
uobj = ufi->entry->object.uvm_obj; /* lower layer */
|
|
|
|
/*
|
|
* check for a case 0 fault. if nothing backing the entry then
|
|
* error now.
|
|
*/
|
|
if (amap == NULL && uobj == NULL) {
|
|
uvmfault_unlockmaps(ufi, FALSE);
|
|
return EFAULT;
|
|
}
|
|
|
|
/*
|
|
* for a case 2B fault waste no time on adjacent pages because
|
|
* they are likely already entered.
|
|
*/
|
|
if (uobj != NULL && amap != NULL &&
|
|
(flt->access_type & PROT_WRITE) != 0) {
|
|
/* wide fault (!narrow) */
|
|
flt->narrow = TRUE;
|
|
}
|
|
|
|
/*
|
|
* establish range of interest based on advice from mapper
|
|
* and then clip to fit map entry. note that we only want
|
|
* to do this the first time through the fault. if we
|
|
* ReFault we will disable this by setting "narrow" to true.
|
|
*/
|
|
if (flt->narrow == FALSE) {
|
|
|
|
/* wide fault (!narrow) */
|
|
nback = min(uvmadvice[ufi->entry->advice].nback,
|
|
(ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT);
|
|
flt->startva = ufi->orig_rvaddr - ((vsize_t)nback << PAGE_SHIFT);
|
|
nforw = min(uvmadvice[ufi->entry->advice].nforw,
|
|
((ufi->entry->end - ufi->orig_rvaddr) >> PAGE_SHIFT) - 1);
|
|
/*
|
|
* note: "-1" because we don't want to count the
|
|
* faulting page as forw
|
|
*/
|
|
flt->npages = nback + nforw + 1;
|
|
flt->centeridx = nback;
|
|
|
|
flt->narrow = TRUE; /* ensure only once per-fault */
|
|
} else {
|
|
/* narrow fault! */
|
|
nback = nforw = 0;
|
|
flt->startva = ufi->orig_rvaddr;
|
|
flt->npages = 1;
|
|
flt->centeridx = 0;
|
|
}
|
|
|
|
/*
|
|
* if we've got an amap then lock it and extract current anons.
|
|
*/
|
|
if (amap) {
|
|
amap_lock(amap);
|
|
amap_lookups(&ufi->entry->aref,
|
|
flt->startva - ufi->entry->start, *ranons, flt->npages);
|
|
} else {
|
|
*ranons = NULL; /* to be safe */
|
|
}
|
|
|
|
/*
|
|
* for MADV_SEQUENTIAL mappings we want to deactivate the back pages
|
|
* now and then forget about them (for the rest of the fault).
|
|
*/
|
|
if (ufi->entry->advice == MADV_SEQUENTIAL && nback != 0) {
|
|
/* flush back-page anons? */
|
|
if (amap)
|
|
uvmfault_anonflush(*ranons, nback);
|
|
|
|
/*
|
|
* flush object?
|
|
*/
|
|
if (uobj) {
|
|
voff_t uoff;
|
|
|
|
uoff = (flt->startva - ufi->entry->start) + ufi->entry->offset;
|
|
rw_enter(uobj->vmobjlock, RW_WRITE);
|
|
(void) uobj->pgops->pgo_flush(uobj, uoff, uoff +
|
|
((vsize_t)nback << PAGE_SHIFT), PGO_DEACTIVATE);
|
|
rw_exit(uobj->vmobjlock);
|
|
}
|
|
|
|
/* now forget about the backpages */
|
|
if (amap)
|
|
*ranons += nback;
|
|
flt->startva += ((vsize_t)nback << PAGE_SHIFT);
|
|
flt->npages -= nback;
|
|
flt->centeridx = 0;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_upper_lookup: look up existing h/w mapping and amap.
|
|
*
|
|
* iterate range of interest:
|
|
* 1. check if h/w mapping exists. if yes, we don't care
|
|
* 2. check if anon exists. if not, page is lower.
|
|
* 3. if anon exists, enter h/w mapping for neighbors.
|
|
*
|
|
* => called with amap locked (if exists).
|
|
*/
|
|
boolean_t
|
|
uvm_fault_upper_lookup(struct uvm_faultinfo *ufi,
|
|
const struct uvm_faultctx *flt, struct vm_anon **anons,
|
|
struct vm_page **pages)
|
|
{
|
|
struct vm_amap *amap = ufi->entry->aref.ar_amap;
|
|
struct vm_anon *anon;
|
|
boolean_t shadowed;
|
|
vaddr_t currva;
|
|
paddr_t pa;
|
|
int lcv;
|
|
|
|
/* locked: maps(read), amap(if there) */
|
|
KASSERT(amap == NULL ||
|
|
rw_write_held(amap->am_lock));
|
|
|
|
/*
|
|
* map in the backpages and frontpages we found in the amap in hopes
|
|
* of preventing future faults. we also init the pages[] array as
|
|
* we go.
|
|
*/
|
|
currva = flt->startva;
|
|
shadowed = FALSE;
|
|
for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) {
|
|
/*
|
|
* dont play with VAs that are already mapped
|
|
* except for center)
|
|
*/
|
|
if (lcv != flt->centeridx &&
|
|
pmap_extract(ufi->orig_map->pmap, currva, &pa)) {
|
|
pages[lcv] = PGO_DONTCARE;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* unmapped or center page. check if any anon at this level.
|
|
*/
|
|
if (amap == NULL || anons[lcv] == NULL) {
|
|
pages[lcv] = NULL;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* check for present page and map if possible.
|
|
*/
|
|
pages[lcv] = PGO_DONTCARE;
|
|
if (lcv == flt->centeridx) { /* save center for later! */
|
|
shadowed = TRUE;
|
|
continue;
|
|
}
|
|
anon = anons[lcv];
|
|
KASSERT(anon->an_lock == amap->am_lock);
|
|
if (anon->an_page &&
|
|
(anon->an_page->pg_flags & (PG_RELEASED|PG_BUSY)) == 0) {
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(anon->an_page); /* reactivate */
|
|
uvm_unlock_pageq();
|
|
counters_inc(uvmexp_counters, flt_namap);
|
|
|
|
/*
|
|
* Since this isn't the page that's actually faulting,
|
|
* ignore pmap_enter() failures; it's not critical
|
|
* that we enter these right now.
|
|
*/
|
|
(void) pmap_enter(ufi->orig_map->pmap, currva,
|
|
VM_PAGE_TO_PHYS(anon->an_page) | flt->pa_flags,
|
|
(anon->an_ref > 1) ?
|
|
(flt->enter_prot & ~PROT_WRITE) : flt->enter_prot,
|
|
PMAP_CANFAIL |
|
|
(VM_MAPENT_ISWIRED(ufi->entry) ? PMAP_WIRED : 0));
|
|
}
|
|
}
|
|
if (flt->npages > 1)
|
|
pmap_update(ufi->orig_map->pmap);
|
|
|
|
return shadowed;
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_upper: handle upper fault.
|
|
*
|
|
* 1. acquire anon lock.
|
|
* 2. get anon. let uvmfault_anonget do the dirty work.
|
|
* 3. if COW, promote data to new anon
|
|
* 4. enter h/w mapping
|
|
*/
|
|
int
|
|
uvm_fault_upper(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
|
|
struct vm_anon **anons, vm_fault_t fault_type)
|
|
{
|
|
struct vm_amap *amap = ufi->entry->aref.ar_amap;
|
|
struct vm_anon *oanon, *anon = anons[flt->centeridx];
|
|
struct vm_page *pg = NULL;
|
|
int error, ret;
|
|
|
|
/* locked: maps(read), amap, anon */
|
|
KASSERT(rw_write_held(amap->am_lock));
|
|
KASSERT(anon->an_lock == amap->am_lock);
|
|
|
|
/*
|
|
* no matter if we have case 1A or case 1B we are going to need to
|
|
* have the anon's memory resident. ensure that now.
|
|
*/
|
|
/*
|
|
* let uvmfault_anonget do the dirty work.
|
|
* if it fails (!OK) it will unlock everything for us.
|
|
* if it succeeds, locks are still valid and locked.
|
|
* also, if it is OK, then the anon's page is on the queues.
|
|
* if the page is on loan from a uvm_object, then anonget will
|
|
* lock that object for us if it does not fail.
|
|
*/
|
|
error = uvmfault_anonget(ufi, amap, anon);
|
|
switch (error) {
|
|
case VM_PAGER_OK:
|
|
break;
|
|
|
|
case VM_PAGER_REFAULT:
|
|
return ERESTART;
|
|
|
|
case VM_PAGER_ERROR:
|
|
/*
|
|
* An error occurred while trying to bring in the
|
|
* page -- this is the only error we return right
|
|
* now.
|
|
*/
|
|
return EACCES; /* XXX */
|
|
default:
|
|
#ifdef DIAGNOSTIC
|
|
panic("uvm_fault: uvmfault_anonget -> %d", error);
|
|
#else
|
|
return EACCES;
|
|
#endif
|
|
}
|
|
|
|
KASSERT(rw_write_held(amap->am_lock));
|
|
KASSERT(anon->an_lock == amap->am_lock);
|
|
|
|
/*
|
|
* if we are case 1B then we will need to allocate a new blank
|
|
* anon to transfer the data into. note that we have a lock
|
|
* on anon, so no one can busy or release the page until we are done.
|
|
* also note that the ref count can't drop to zero here because
|
|
* it is > 1 and we are only dropping one ref.
|
|
*
|
|
* in the (hopefully very rare) case that we are out of RAM we
|
|
* will unlock, wait for more RAM, and refault.
|
|
*
|
|
* if we are out of anon VM we wait for RAM to become available.
|
|
*/
|
|
|
|
if ((flt->access_type & PROT_WRITE) != 0 && anon->an_ref > 1) {
|
|
counters_inc(uvmexp_counters, flt_acow);
|
|
oanon = anon; /* oanon = old */
|
|
anon = uvm_analloc();
|
|
if (anon) {
|
|
anon->an_lock = amap->am_lock;
|
|
pg = uvm_pagealloc(NULL, 0, anon, 0);
|
|
}
|
|
|
|
/* check for out of RAM */
|
|
if (anon == NULL || pg == NULL) {
|
|
uvmfault_unlockall(ufi, amap, NULL);
|
|
if (anon == NULL)
|
|
counters_inc(uvmexp_counters, flt_noanon);
|
|
else {
|
|
anon->an_lock = NULL;
|
|
anon->an_ref--;
|
|
uvm_anfree(anon);
|
|
counters_inc(uvmexp_counters, flt_noram);
|
|
}
|
|
|
|
if (uvm_swapisfull())
|
|
return ENOMEM;
|
|
|
|
/* out of RAM, wait for more */
|
|
if (anon == NULL)
|
|
uvm_anwait();
|
|
else
|
|
uvm_wait("flt_noram3");
|
|
return ERESTART;
|
|
}
|
|
|
|
/* got all resources, replace anon with nanon */
|
|
uvm_pagecopy(oanon->an_page, pg); /* pg now !PG_CLEAN */
|
|
/* un-busy! new page */
|
|
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
ret = amap_add(&ufi->entry->aref,
|
|
ufi->orig_rvaddr - ufi->entry->start, anon, 1);
|
|
KASSERT(ret == 0);
|
|
|
|
/* deref: can not drop to zero here by defn! */
|
|
oanon->an_ref--;
|
|
|
|
#if defined(MULTIPROCESSOR) && !defined(__HAVE_PMAP_MPSAFE_ENTER_COW)
|
|
/*
|
|
* If there are multiple threads, either uvm or the
|
|
* pmap has to make sure no threads see the old RO
|
|
* mapping once any have seen the new RW mapping.
|
|
* uvm does it by inserting the new mapping RO and
|
|
* letting it fault again.
|
|
* This is only a problem on MP systems.
|
|
*/
|
|
if (P_HASSIBLING(curproc)) {
|
|
flt->enter_prot &= ~PROT_WRITE;
|
|
flt->access_type &= ~PROT_WRITE;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* note: anon is _not_ locked, but we have the sole references
|
|
* to in from amap.
|
|
* thus, no one can get at it until we are done with it.
|
|
*/
|
|
} else {
|
|
counters_inc(uvmexp_counters, flt_anon);
|
|
oanon = anon;
|
|
pg = anon->an_page;
|
|
if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */
|
|
flt->enter_prot = flt->enter_prot & ~PROT_WRITE;
|
|
}
|
|
|
|
/*
|
|
* now map the page in .
|
|
*/
|
|
if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr,
|
|
VM_PAGE_TO_PHYS(pg) | flt->pa_flags, flt->enter_prot,
|
|
flt->access_type | PMAP_CANFAIL | (flt->wired ? PMAP_WIRED : 0)) != 0) {
|
|
/*
|
|
* No need to undo what we did; we can simply think of
|
|
* this as the pmap throwing away the mapping information.
|
|
*
|
|
* We do, however, have to go through the ReFault path,
|
|
* as the map may change while we're asleep.
|
|
*/
|
|
uvmfault_unlockall(ufi, amap, NULL);
|
|
if (uvm_swapisfull()) {
|
|
/* XXX instrumentation */
|
|
return ENOMEM;
|
|
}
|
|
/* XXX instrumentation */
|
|
uvm_wait("flt_pmfail1");
|
|
return ERESTART;
|
|
}
|
|
|
|
/*
|
|
* ... update the page queues.
|
|
*/
|
|
uvm_lock_pageq();
|
|
|
|
if (fault_type == VM_FAULT_WIRE) {
|
|
uvm_pagewire(pg);
|
|
/*
|
|
* since the now-wired page cannot be paged out,
|
|
* release its swap resources for others to use.
|
|
* since an anon with no swap cannot be PG_CLEAN,
|
|
* clear its clean flag now.
|
|
*/
|
|
atomic_clearbits_int(&pg->pg_flags, PG_CLEAN);
|
|
uvm_anon_dropswap(anon);
|
|
} else {
|
|
/* activate it */
|
|
uvm_pageactivate(pg);
|
|
}
|
|
|
|
uvm_unlock_pageq();
|
|
|
|
/*
|
|
* done case 1! finish up by unlocking everything and returning success
|
|
*/
|
|
uvmfault_unlockall(ufi, amap, NULL);
|
|
pmap_update(ufi->orig_map->pmap);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_lower_lookup: look up on-memory uobj pages.
|
|
*
|
|
* 1. get on-memory pages.
|
|
* 2. if failed, give up (get only center page later).
|
|
* 3. if succeeded, enter h/w mapping of neighbor pages.
|
|
*/
|
|
|
|
struct vm_page *
|
|
uvm_fault_lower_lookup(
|
|
struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt,
|
|
struct vm_page **pages)
|
|
{
|
|
struct uvm_object *uobj = ufi->entry->object.uvm_obj;
|
|
struct vm_page *uobjpage = NULL;
|
|
int lcv, gotpages;
|
|
vaddr_t currva;
|
|
|
|
rw_enter(uobj->vmobjlock, RW_WRITE);
|
|
|
|
counters_inc(uvmexp_counters, flt_lget);
|
|
gotpages = flt->npages;
|
|
(void) uobj->pgops->pgo_get(uobj,
|
|
ufi->entry->offset + (flt->startva - ufi->entry->start),
|
|
pages, &gotpages, flt->centeridx,
|
|
flt->access_type & MASK(ufi->entry), ufi->entry->advice,
|
|
PGO_LOCKED);
|
|
|
|
/*
|
|
* check for pages to map, if we got any
|
|
*/
|
|
if (gotpages == 0) {
|
|
return NULL;
|
|
}
|
|
|
|
currva = flt->startva;
|
|
for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) {
|
|
if (pages[lcv] == NULL ||
|
|
pages[lcv] == PGO_DONTCARE)
|
|
continue;
|
|
|
|
KASSERT((pages[lcv]->pg_flags & PG_RELEASED) == 0);
|
|
|
|
/*
|
|
* if center page is resident and not
|
|
* PG_BUSY, then pgo_get made it PG_BUSY
|
|
* for us and gave us a handle to it.
|
|
* remember this page as "uobjpage."
|
|
* (for later use).
|
|
*/
|
|
if (lcv == flt->centeridx) {
|
|
uobjpage = pages[lcv];
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* note: calling pgo_get with locked data
|
|
* structures returns us pages which are
|
|
* neither busy nor released, so we don't
|
|
* need to check for this. we can just
|
|
* directly enter the page (after moving it
|
|
* to the head of the active queue [useful?]).
|
|
*/
|
|
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(pages[lcv]); /* reactivate */
|
|
uvm_unlock_pageq();
|
|
counters_inc(uvmexp_counters, flt_nomap);
|
|
|
|
/*
|
|
* Since this page isn't the page that's
|
|
* actually faulting, ignore pmap_enter()
|
|
* failures; it's not critical that we
|
|
* enter these right now.
|
|
*/
|
|
(void) pmap_enter(ufi->orig_map->pmap, currva,
|
|
VM_PAGE_TO_PHYS(pages[lcv]) | flt->pa_flags,
|
|
flt->enter_prot & MASK(ufi->entry),
|
|
PMAP_CANFAIL |
|
|
(flt->wired ? PMAP_WIRED : 0));
|
|
|
|
/*
|
|
* NOTE: page can't be PG_WANTED because
|
|
* we've held the lock the whole time
|
|
* we've had the handle.
|
|
*/
|
|
atomic_clearbits_int(&pages[lcv]->pg_flags, PG_BUSY);
|
|
UVM_PAGE_OWN(pages[lcv], NULL);
|
|
}
|
|
pmap_update(ufi->orig_map->pmap);
|
|
|
|
return uobjpage;
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_lower: handle lower fault.
|
|
*
|
|
*/
|
|
int
|
|
uvm_fault_lower(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt,
|
|
struct vm_page **pages, vm_fault_t fault_type)
|
|
{
|
|
struct vm_amap *amap = ufi->entry->aref.ar_amap;
|
|
struct uvm_object *uobj = ufi->entry->object.uvm_obj;
|
|
boolean_t promote, locked;
|
|
int result;
|
|
struct vm_page *uobjpage, *pg = NULL;
|
|
struct vm_anon *anon = NULL;
|
|
voff_t uoff;
|
|
|
|
/*
|
|
* now, if the desired page is not shadowed by the amap and we have
|
|
* a backing object that does not have a special fault routine, then
|
|
* we ask (with pgo_get) the object for resident pages that we care
|
|
* about and attempt to map them in. we do not let pgo_get block
|
|
* (PGO_LOCKED).
|
|
*/
|
|
if (uobj == NULL) {
|
|
/* zero fill; don't care neighbor pages */
|
|
uobjpage = NULL;
|
|
} else {
|
|
uobjpage = uvm_fault_lower_lookup(ufi, flt, pages);
|
|
}
|
|
|
|
/*
|
|
* note that at this point we are done with any front or back pages.
|
|
* we are now going to focus on the center page (i.e. the one we've
|
|
* faulted on). if we have faulted on the bottom (uobj)
|
|
* layer [i.e. case 2] and the page was both present and available,
|
|
* then we've got a pointer to it as "uobjpage" and we've already
|
|
* made it BUSY.
|
|
*/
|
|
|
|
/*
|
|
* locked:
|
|
*/
|
|
KASSERT(amap == NULL ||
|
|
rw_write_held(amap->am_lock));
|
|
KASSERT(uobj == NULL ||
|
|
rw_write_held(uobj->vmobjlock));
|
|
|
|
/*
|
|
* note that uobjpage can not be PGO_DONTCARE at this point. we now
|
|
* set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we
|
|
* have a backing object, check and see if we are going to promote
|
|
* the data up to an anon during the fault.
|
|
*/
|
|
if (uobj == NULL) {
|
|
uobjpage = PGO_DONTCARE;
|
|
promote = TRUE; /* always need anon here */
|
|
} else {
|
|
KASSERT(uobjpage != PGO_DONTCARE);
|
|
promote = (flt->access_type & PROT_WRITE) &&
|
|
UVM_ET_ISCOPYONWRITE(ufi->entry);
|
|
}
|
|
|
|
/*
|
|
* if uobjpage is not null then we do not need to do I/O to get the
|
|
* uobjpage.
|
|
*
|
|
* if uobjpage is null, then we need to ask the pager to
|
|
* get the data for us. once we have the data, we need to reverify
|
|
* the state the world. we are currently not holding any resources.
|
|
*/
|
|
if (uobjpage) {
|
|
/* update rusage counters */
|
|
curproc->p_ru.ru_minflt++;
|
|
} else {
|
|
int gotpages;
|
|
|
|
/* update rusage counters */
|
|
curproc->p_ru.ru_majflt++;
|
|
|
|
uvmfault_unlockall(ufi, amap, NULL);
|
|
|
|
counters_inc(uvmexp_counters, flt_get);
|
|
gotpages = 1;
|
|
uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset;
|
|
result = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages,
|
|
0, flt->access_type & MASK(ufi->entry), ufi->entry->advice,
|
|
PGO_SYNCIO);
|
|
|
|
/*
|
|
* recover from I/O
|
|
*/
|
|
if (result != VM_PAGER_OK) {
|
|
KASSERT(result != VM_PAGER_PEND);
|
|
|
|
if (result == VM_PAGER_AGAIN) {
|
|
tsleep_nsec(&nowake, PVM, "fltagain2",
|
|
MSEC_TO_NSEC(5));
|
|
return ERESTART;
|
|
}
|
|
|
|
if (!UVM_ET_ISNOFAULT(ufi->entry))
|
|
return (EIO);
|
|
|
|
uobjpage = PGO_DONTCARE;
|
|
uobj = NULL;
|
|
promote = TRUE;
|
|
}
|
|
|
|
/* re-verify the state of the world. */
|
|
locked = uvmfault_relock(ufi);
|
|
if (locked && amap != NULL)
|
|
amap_lock(amap);
|
|
|
|
/* might be changed */
|
|
if (uobjpage != PGO_DONTCARE) {
|
|
uobj = uobjpage->uobject;
|
|
rw_enter(uobj->vmobjlock, RW_WRITE);
|
|
}
|
|
|
|
/*
|
|
* Re-verify that amap slot is still free. if there is
|
|
* a problem, we clean up.
|
|
*/
|
|
if (locked && amap && amap_lookup(&ufi->entry->aref,
|
|
ufi->orig_rvaddr - ufi->entry->start)) {
|
|
if (locked)
|
|
uvmfault_unlockall(ufi, amap, NULL);
|
|
locked = FALSE;
|
|
}
|
|
|
|
/* didn't get the lock? release the page and retry. */
|
|
if (locked == FALSE && uobjpage != PGO_DONTCARE) {
|
|
uvm_lock_pageq();
|
|
/* make sure it is in queues */
|
|
uvm_pageactivate(uobjpage);
|
|
uvm_unlock_pageq();
|
|
|
|
if (uobjpage->pg_flags & PG_WANTED)
|
|
/* still holding object lock */
|
|
wakeup(uobjpage);
|
|
atomic_clearbits_int(&uobjpage->pg_flags,
|
|
PG_BUSY|PG_WANTED);
|
|
UVM_PAGE_OWN(uobjpage, NULL);
|
|
}
|
|
|
|
if (locked == FALSE) {
|
|
if (uobjpage != PGO_DONTCARE)
|
|
rw_exit(uobj->vmobjlock);
|
|
return ERESTART;
|
|
}
|
|
|
|
/*
|
|
* we have the data in uobjpage which is PG_BUSY
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* notes:
|
|
* - at this point uobjpage can not be NULL
|
|
* - at this point uobjpage could be PG_WANTED (handle later)
|
|
*/
|
|
if (promote == FALSE) {
|
|
/*
|
|
* we are not promoting. if the mapping is COW ensure that we
|
|
* don't give more access than we should (e.g. when doing a read
|
|
* fault on a COPYONWRITE mapping we want to map the COW page in
|
|
* R/O even though the entry protection could be R/W).
|
|
*
|
|
* set "pg" to the page we want to map in (uobjpage, usually)
|
|
*/
|
|
counters_inc(uvmexp_counters, flt_obj);
|
|
if (UVM_ET_ISCOPYONWRITE(ufi->entry))
|
|
flt->enter_prot &= ~PROT_WRITE;
|
|
pg = uobjpage; /* map in the actual object */
|
|
|
|
/* assert(uobjpage != PGO_DONTCARE) */
|
|
|
|
/*
|
|
* we are faulting directly on the page.
|
|
*/
|
|
} else {
|
|
/*
|
|
* if we are going to promote the data to an anon we
|
|
* allocate a blank anon here and plug it into our amap.
|
|
*/
|
|
#ifdef DIAGNOSTIC
|
|
if (amap == NULL)
|
|
panic("uvm_fault: want to promote data, but no anon");
|
|
#endif
|
|
|
|
anon = uvm_analloc();
|
|
if (anon) {
|
|
/*
|
|
* In `Fill in data...' below, if
|
|
* uobjpage == PGO_DONTCARE, we want
|
|
* a zero'd, dirty page, so have
|
|
* uvm_pagealloc() do that for us.
|
|
*/
|
|
anon->an_lock = amap->am_lock;
|
|
pg = uvm_pagealloc(NULL, 0, anon,
|
|
(uobjpage == PGO_DONTCARE) ? UVM_PGA_ZERO : 0);
|
|
}
|
|
|
|
/*
|
|
* out of memory resources?
|
|
*/
|
|
if (anon == NULL || pg == NULL) {
|
|
/*
|
|
* arg! must unbusy our page and fail or sleep.
|
|
*/
|
|
if (uobjpage != PGO_DONTCARE) {
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(uobjpage);
|
|
uvm_unlock_pageq();
|
|
|
|
if (uobjpage->pg_flags & PG_WANTED)
|
|
wakeup(uobjpage);
|
|
atomic_clearbits_int(&uobjpage->pg_flags,
|
|
PG_BUSY|PG_WANTED);
|
|
UVM_PAGE_OWN(uobjpage, NULL);
|
|
}
|
|
|
|
/* unlock and fail ... */
|
|
uvmfault_unlockall(ufi, amap, uobj);
|
|
if (anon == NULL)
|
|
counters_inc(uvmexp_counters, flt_noanon);
|
|
else {
|
|
anon->an_lock = NULL;
|
|
anon->an_ref--;
|
|
uvm_anfree(anon);
|
|
counters_inc(uvmexp_counters, flt_noram);
|
|
}
|
|
|
|
if (uvm_swapisfull())
|
|
return (ENOMEM);
|
|
|
|
/* out of RAM, wait for more */
|
|
if (anon == NULL)
|
|
uvm_anwait();
|
|
else
|
|
uvm_wait("flt_noram5");
|
|
return ERESTART;
|
|
}
|
|
|
|
/*
|
|
* fill in the data
|
|
*/
|
|
if (uobjpage != PGO_DONTCARE) {
|
|
counters_inc(uvmexp_counters, flt_prcopy);
|
|
/* copy page [pg now dirty] */
|
|
uvm_pagecopy(uobjpage, pg);
|
|
|
|
/*
|
|
* promote to shared amap? make sure all sharing
|
|
* procs see it
|
|
*/
|
|
if ((amap_flags(amap) & AMAP_SHARED) != 0) {
|
|
pmap_page_protect(uobjpage, PROT_NONE);
|
|
}
|
|
#if defined(MULTIPROCESSOR) && !defined(__HAVE_PMAP_MPSAFE_ENTER_COW)
|
|
/*
|
|
* Otherwise:
|
|
* If there are multiple threads, either uvm or the
|
|
* pmap has to make sure no threads see the old RO
|
|
* mapping once any have seen the new RW mapping.
|
|
* uvm does it here by forcing it to PROT_NONE before
|
|
* inserting the new mapping.
|
|
*/
|
|
else if (P_HASSIBLING(curproc)) {
|
|
pmap_page_protect(uobjpage, PROT_NONE);
|
|
}
|
|
#endif
|
|
|
|
/* dispose of uobjpage. drop handle to uobj as well. */
|
|
if (uobjpage->pg_flags & PG_WANTED)
|
|
wakeup(uobjpage);
|
|
atomic_clearbits_int(&uobjpage->pg_flags,
|
|
PG_BUSY|PG_WANTED);
|
|
UVM_PAGE_OWN(uobjpage, NULL);
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(uobjpage);
|
|
uvm_unlock_pageq();
|
|
rw_exit(uobj->vmobjlock);
|
|
uobj = NULL;
|
|
} else {
|
|
counters_inc(uvmexp_counters, flt_przero);
|
|
/*
|
|
* Page is zero'd and marked dirty by uvm_pagealloc()
|
|
* above.
|
|
*/
|
|
}
|
|
|
|
if (amap_add(&ufi->entry->aref,
|
|
ufi->orig_rvaddr - ufi->entry->start, anon, 0)) {
|
|
uvmfault_unlockall(ufi, amap, uobj);
|
|
uvm_anfree(anon);
|
|
counters_inc(uvmexp_counters, flt_noamap);
|
|
|
|
if (uvm_swapisfull())
|
|
return (ENOMEM);
|
|
|
|
amap_populate(&ufi->entry->aref,
|
|
ufi->orig_rvaddr - ufi->entry->start);
|
|
return ERESTART;
|
|
}
|
|
}
|
|
|
|
/* note: pg is either the uobjpage or the new page in the new anon */
|
|
/*
|
|
* all resources are present. we can now map it in and free our
|
|
* resources.
|
|
*/
|
|
if (amap == NULL)
|
|
KASSERT(anon == NULL);
|
|
else {
|
|
KASSERT(rw_write_held(amap->am_lock));
|
|
KASSERT(anon == NULL || anon->an_lock == amap->am_lock);
|
|
}
|
|
if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr,
|
|
VM_PAGE_TO_PHYS(pg) | flt->pa_flags, flt->enter_prot,
|
|
flt->access_type | PMAP_CANFAIL | (flt->wired ? PMAP_WIRED : 0)) != 0) {
|
|
/*
|
|
* No need to undo what we did; we can simply think of
|
|
* this as the pmap throwing away the mapping information.
|
|
*
|
|
* We do, however, have to go through the ReFault path,
|
|
* as the map may change while we're asleep.
|
|
*/
|
|
if (pg->pg_flags & PG_WANTED)
|
|
wakeup(pg);
|
|
|
|
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE|PG_WANTED);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
uvmfault_unlockall(ufi, amap, uobj);
|
|
if (uvm_swapisfull()) {
|
|
/* XXX instrumentation */
|
|
return (ENOMEM);
|
|
}
|
|
/* XXX instrumentation */
|
|
uvm_wait("flt_pmfail2");
|
|
return ERESTART;
|
|
}
|
|
|
|
if (fault_type == VM_FAULT_WIRE) {
|
|
uvm_lock_pageq();
|
|
uvm_pagewire(pg);
|
|
uvm_unlock_pageq();
|
|
if (pg->pg_flags & PQ_AOBJ) {
|
|
/*
|
|
* since the now-wired page cannot be paged out,
|
|
* release its swap resources for others to use.
|
|
* since an aobj page with no swap cannot be clean,
|
|
* mark it dirty now.
|
|
*
|
|
* use pg->uobject here. if the page is from a
|
|
* tmpfs vnode, the pages are backed by its UAO and
|
|
* not the vnode.
|
|
*/
|
|
KASSERT(uobj != NULL);
|
|
KASSERT(uobj->vmobjlock == pg->uobject->vmobjlock);
|
|
atomic_clearbits_int(&pg->pg_flags, PG_CLEAN);
|
|
uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
|
|
}
|
|
} else {
|
|
/* activate it */
|
|
uvm_lock_pageq();
|
|
uvm_pageactivate(pg);
|
|
uvm_unlock_pageq();
|
|
}
|
|
|
|
if (pg->pg_flags & PG_WANTED)
|
|
wakeup(pg);
|
|
|
|
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE|PG_WANTED);
|
|
UVM_PAGE_OWN(pg, NULL);
|
|
uvmfault_unlockall(ufi, amap, uobj);
|
|
pmap_update(ufi->orig_map->pmap);
|
|
|
|
return (0);
|
|
}
|
|
|
|
|
|
/*
|
|
* uvm_fault_wire: wire down a range of virtual addresses in a map.
|
|
*
|
|
* => map may be read-locked by caller, but MUST NOT be write-locked.
|
|
* => if map is read-locked, any operations which may cause map to
|
|
* be write-locked in uvm_fault() must be taken care of by
|
|
* the caller. See uvm_map_pageable().
|
|
*/
|
|
int
|
|
uvm_fault_wire(vm_map_t map, vaddr_t start, vaddr_t end, vm_prot_t access_type)
|
|
{
|
|
vaddr_t va;
|
|
int rv;
|
|
|
|
/*
|
|
* now fault it in a page at a time. if the fault fails then we have
|
|
* to undo what we have done. note that in uvm_fault PROT_NONE
|
|
* is replaced with the max protection if fault_type is VM_FAULT_WIRE.
|
|
*/
|
|
for (va = start ; va < end ; va += PAGE_SIZE) {
|
|
rv = uvm_fault(map, va, VM_FAULT_WIRE, access_type);
|
|
if (rv) {
|
|
if (va != start) {
|
|
uvm_fault_unwire(map, start, va);
|
|
}
|
|
return (rv);
|
|
}
|
|
}
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_unwire(): unwire range of virtual space.
|
|
*/
|
|
void
|
|
uvm_fault_unwire(vm_map_t map, vaddr_t start, vaddr_t end)
|
|
{
|
|
|
|
vm_map_lock_read(map);
|
|
uvm_fault_unwire_locked(map, start, end);
|
|
vm_map_unlock_read(map);
|
|
}
|
|
|
|
/*
|
|
* uvm_fault_unwire_locked(): the guts of uvm_fault_unwire().
|
|
*
|
|
* => map must be at least read-locked.
|
|
*/
|
|
void
|
|
uvm_fault_unwire_locked(vm_map_t map, vaddr_t start, vaddr_t end)
|
|
{
|
|
vm_map_entry_t entry, oentry = NULL, next;
|
|
pmap_t pmap = vm_map_pmap(map);
|
|
vaddr_t va;
|
|
paddr_t pa;
|
|
struct vm_page *pg;
|
|
|
|
KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
|
|
vm_map_assert_anylock(map);
|
|
|
|
/*
|
|
* we assume that the area we are unwiring has actually been wired
|
|
* in the first place. this means that we should be able to extract
|
|
* the PAs from the pmap.
|
|
*/
|
|
|
|
/*
|
|
* find the beginning map entry for the region.
|
|
*/
|
|
KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map));
|
|
if (uvm_map_lookup_entry(map, start, &entry) == FALSE)
|
|
panic("uvm_fault_unwire_locked: address not in map");
|
|
|
|
for (va = start; va < end ; va += PAGE_SIZE) {
|
|
if (pmap_extract(pmap, va, &pa) == FALSE)
|
|
continue;
|
|
|
|
/*
|
|
* find the map entry for the current address.
|
|
*/
|
|
KASSERT(va >= entry->start);
|
|
while (entry && va >= entry->end) {
|
|
next = RBT_NEXT(uvm_map_addr, entry);
|
|
entry = next;
|
|
}
|
|
|
|
if (entry == NULL)
|
|
return;
|
|
if (va < entry->start)
|
|
continue;
|
|
|
|
/*
|
|
* lock it.
|
|
*/
|
|
if (entry != oentry) {
|
|
if (oentry != NULL) {
|
|
uvm_map_unlock_entry(oentry);
|
|
}
|
|
uvm_map_lock_entry(entry);
|
|
oentry = entry;
|
|
}
|
|
|
|
/*
|
|
* if the entry is no longer wired, tell the pmap.
|
|
*/
|
|
if (VM_MAPENT_ISWIRED(entry) == 0)
|
|
pmap_unwire(pmap, va);
|
|
|
|
pg = PHYS_TO_VM_PAGE(pa);
|
|
if (pg) {
|
|
uvm_lock_pageq();
|
|
uvm_pageunwire(pg);
|
|
uvm_unlock_pageq();
|
|
}
|
|
}
|
|
|
|
if (oentry != NULL) {
|
|
uvm_map_unlock_entry(oentry);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* uvmfault_unlockmaps: unlock the maps
|
|
*/
|
|
void
|
|
uvmfault_unlockmaps(struct uvm_faultinfo *ufi, boolean_t write_locked)
|
|
{
|
|
/*
|
|
* ufi can be NULL when this isn't really a fault,
|
|
* but merely paging in anon data.
|
|
*/
|
|
if (ufi == NULL) {
|
|
return;
|
|
}
|
|
|
|
uvmfault_update_stats(ufi);
|
|
if (write_locked) {
|
|
vm_map_unlock(ufi->map);
|
|
} else {
|
|
vm_map_unlock_read(ufi->map);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* uvmfault_unlockall: unlock everything passed in.
|
|
*
|
|
* => maps must be read-locked (not write-locked).
|
|
*/
|
|
void
|
|
uvmfault_unlockall(struct uvm_faultinfo *ufi, struct vm_amap *amap,
|
|
struct uvm_object *uobj)
|
|
{
|
|
if (uobj)
|
|
rw_exit(uobj->vmobjlock);
|
|
if (amap != NULL)
|
|
amap_unlock(amap);
|
|
uvmfault_unlockmaps(ufi, FALSE);
|
|
}
|
|
|
|
/*
|
|
* uvmfault_lookup: lookup a virtual address in a map
|
|
*
|
|
* => caller must provide a uvm_faultinfo structure with the IN
|
|
* params properly filled in
|
|
* => we will lookup the map entry (handling submaps) as we go
|
|
* => if the lookup is a success we will return with the maps locked
|
|
* => if "write_lock" is TRUE, we write_lock the map, otherwise we only
|
|
* get a read lock.
|
|
* => note that submaps can only appear in the kernel and they are
|
|
* required to use the same virtual addresses as the map they
|
|
* are referenced by (thus address translation between the main
|
|
* map and the submap is unnecessary).
|
|
*/
|
|
|
|
boolean_t
|
|
uvmfault_lookup(struct uvm_faultinfo *ufi, boolean_t write_lock)
|
|
{
|
|
vm_map_t tmpmap;
|
|
|
|
/*
|
|
* init ufi values for lookup.
|
|
*/
|
|
ufi->map = ufi->orig_map;
|
|
ufi->size = ufi->orig_size;
|
|
|
|
/*
|
|
* keep going down levels until we are done. note that there can
|
|
* only be two levels so we won't loop very long.
|
|
*/
|
|
while (1) {
|
|
if (ufi->orig_rvaddr < ufi->map->min_offset ||
|
|
ufi->orig_rvaddr >= ufi->map->max_offset)
|
|
return FALSE;
|
|
|
|
/* lock map */
|
|
if (write_lock) {
|
|
vm_map_lock(ufi->map);
|
|
} else {
|
|
vm_map_lock_read(ufi->map);
|
|
}
|
|
|
|
/* lookup */
|
|
if (!uvm_map_lookup_entry(ufi->map, ufi->orig_rvaddr,
|
|
&ufi->entry)) {
|
|
uvmfault_unlockmaps(ufi, write_lock);
|
|
return FALSE;
|
|
}
|
|
|
|
/* reduce size if necessary */
|
|
if (ufi->entry->end - ufi->orig_rvaddr < ufi->size)
|
|
ufi->size = ufi->entry->end - ufi->orig_rvaddr;
|
|
|
|
/*
|
|
* submap? replace map with the submap and lookup again.
|
|
* note: VAs in submaps must match VAs in main map.
|
|
*/
|
|
if (UVM_ET_ISSUBMAP(ufi->entry)) {
|
|
tmpmap = ufi->entry->object.sub_map;
|
|
uvmfault_unlockmaps(ufi, write_lock);
|
|
ufi->map = tmpmap;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* got it!
|
|
*/
|
|
ufi->mapv = ufi->map->timestamp;
|
|
return TRUE;
|
|
|
|
} /* while loop */
|
|
|
|
/*NOTREACHED*/
|
|
}
|
|
|
|
/*
|
|
* uvmfault_relock: attempt to relock the same version of the map
|
|
*
|
|
* => fault data structures should be unlocked before calling.
|
|
* => if a success (TRUE) maps will be locked after call.
|
|
*/
|
|
boolean_t
|
|
uvmfault_relock(struct uvm_faultinfo *ufi)
|
|
{
|
|
/*
|
|
* ufi can be NULL when this isn't really a fault,
|
|
* but merely paging in anon data.
|
|
*/
|
|
if (ufi == NULL) {
|
|
return TRUE;
|
|
}
|
|
|
|
counters_inc(uvmexp_counters, flt_relck);
|
|
|
|
/*
|
|
* relock map. fail if version mismatch (in which case nothing
|
|
* gets locked).
|
|
*/
|
|
vm_map_lock_read(ufi->map);
|
|
if (ufi->mapv != ufi->map->timestamp) {
|
|
vm_map_unlock_read(ufi->map);
|
|
return FALSE;
|
|
}
|
|
|
|
counters_inc(uvmexp_counters, flt_relckok);
|
|
return TRUE; /* got it! */
|
|
}
|