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/* $OpenBSD: uvm_anon.c,v 1.37 2013/05/30 16:29:46 tedu Exp $ */
/* $NetBSD: uvm_anon.c,v 1.10 2000/11/25 06:27:59 chs Exp $ */
/*
*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Charles D. Cranor and
* Washington University.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* uvm_anon.c: uvm anon ops
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/kernel.h>
#include <uvm/uvm.h>
#include <uvm/uvm_swap.h>
struct pool uvm_anon_pool;
/*
* allocate anons
*/
void
uvm_anon_init(void)
{
pool_init(&uvm_anon_pool, sizeof(struct vm_anon), 0, 0, 0, "anonpl",
&pool_allocator_nointr);
pool_sethiwat(&uvm_anon_pool, uvmexp.free / 16);
}
/*
* allocate an anon
*/
struct vm_anon *
uvm_analloc(void)
{
struct vm_anon *anon;
anon = pool_get(&uvm_anon_pool, PR_NOWAIT);
if (anon) {
anon->an_ref = 1;
anon->an_page = NULL;
anon->an_swslot = 0;
}
return(anon);
}
/*
* uvm_anfree: free a single anon structure
*
* => caller must remove anon from its amap before calling (if it was in
* an amap).
* => we may lock the pageq's.
*/
void
uvm_anfree(struct vm_anon *anon)
{
struct vm_page *pg;
/*
* get page
*/
pg = anon->an_page;
/*
* if there is a resident page and it is loaned, then anon may not
* own it. call out to uvm_anon_lockpage() to ensure the real owner
* of the page has been identified and locked.
*/
if (pg && pg->loan_count)
pg = uvm_anon_lockloanpg(anon);
/*
* if we have a resident page, we must dispose of it before freeing
* the anon.
*/
if (pg) {
/*
* if the page is owned by a uobject, then we must
* kill the loan on the page rather than free it.
*/
if (pg->uobject) {
uvm_lock_pageq();
KASSERT(pg->loan_count > 0);
pg->loan_count--;
pg->uanon = NULL;
uvm_unlock_pageq();
} else {
/*
* page has no uobject, so we must be the owner of it.
*
* if page is busy then we just mark it as released
* (who ever has it busy must check for this when they
* wake up). if the page is not busy then we can
* free it now.
*/
if ((pg->pg_flags & PG_BUSY) != 0) {
/* tell them to dump it when done */
atomic_setbits_int(&pg->pg_flags, PG_RELEASED);
return;
}
pmap_page_protect(pg, VM_PROT_NONE);
uvm_lock_pageq(); /* lock out pagedaemon */
uvm_pagefree(pg); /* bye bye */
uvm_unlock_pageq(); /* free the daemon */
}
}
if (pg == NULL && anon->an_swslot != 0) {
/* this page is no longer only in swap. */
KASSERT(uvmexp.swpgonly > 0);
uvmexp.swpgonly--;
}
/*
* free any swap resources.
*/
uvm_anon_dropswap(anon);
/*
* now that we've stripped the data areas from the anon, free the anon
* itself!
*/
KASSERT(anon->an_page == NULL);
KASSERT(anon->an_swslot == 0);
pool_put(&uvm_anon_pool, anon);
}
/*
* uvm_anon_dropswap: release any swap resources from this anon.
*/
void
uvm_anon_dropswap(struct vm_anon *anon)
{
if (anon->an_swslot == 0)
return;
uvm_swap_free(anon->an_swslot, 1);
anon->an_swslot = 0;
}
/*
* uvm_anon_lockloanpg: given a locked anon, lock its resident page
*
* => on return:
* if there is a resident page:
* if it is ownerless, we take over as owner
* we return the resident page (it can change during
* this function)
* => note that the only time an anon has an ownerless resident page
* is if the page was loaned from a uvm_object and the uvm_object
* disowned it
* => this only needs to be called when you want to do an operation
* on an anon's resident page and that page has a non-zero loan
* count.
*/
struct vm_page *
uvm_anon_lockloanpg(struct vm_anon *anon)
{
struct vm_page *pg;
/*
* loop while we have a resident page that has a non-zero loan count.
* if we successfully get our lock, we will "break" the loop.
* note that the test for pg->loan_count is not protected -- this
* may produce false positive results. note that a false positive
* result may cause us to do more work than we need to, but it will
* not produce an incorrect result.
*/
while (((pg = anon->an_page) != NULL) && pg->loan_count != 0) {
/*
* if page is un-owned [i.e. the object dropped its ownership],
* then we can take over as owner!
*/
if (pg->uobject == NULL && (pg->pg_flags & PQ_ANON) == 0) {
uvm_lock_pageq();
atomic_setbits_int(&pg->pg_flags, PQ_ANON);
pg->loan_count--; /* ... and drop our loan */
uvm_unlock_pageq();
}
/*
* we did it! break the loop
*/
break;
}
return(pg);
}
/*
* fetch an anon's page.
*
* => returns TRUE if pagein was aborted due to lack of memory.
*/
boolean_t
uvm_anon_pagein(struct vm_anon *anon)
{
struct vm_page *pg;
struct uvm_object *uobj;
int rv;
rv = uvmfault_anonget(NULL, NULL, anon);
switch (rv) {
case VM_PAGER_OK:
break;
case VM_PAGER_ERROR:
case VM_PAGER_REFAULT:
/*
* nothing more to do on errors.
* VM_PAGER_REFAULT can only mean that the anon was freed,
* so again there's nothing to do.
*/
return FALSE;
default:
#ifdef DIAGNOSTIC
panic("anon_pagein: uvmfault_anonget -> %d", rv);
#else
return FALSE;
#endif
}
/*
* ok, we've got the page now.
* mark it as dirty, clear its swslot and un-busy it.
*/
pg = anon->an_page;
uobj = pg->uobject;
uvm_swap_free(anon->an_swslot, 1);
anon->an_swslot = 0;
atomic_clearbits_int(&pg->pg_flags, PG_CLEAN);
/*
* deactivate the page (to put it on a page queue)
*/
pmap_clear_reference(pg);
pmap_page_protect(pg, VM_PROT_NONE);
uvm_lock_pageq();
uvm_pagedeactivate(pg);
uvm_unlock_pageq();
return FALSE;
}
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