NetBSD/sys/uvm/uvm_aobj.c

1481 lines
34 KiB
C

/* $NetBSD: uvm_aobj.c,v 1.61 2003/09/18 13:48:05 drochner Exp $ */
/*
* Copyright (c) 1998 Chuck Silvers, Charles D. Cranor and
* Washington University.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Charles D. Cranor and
* Washington University.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* from: Id: uvm_aobj.c,v 1.1.2.5 1998/02/06 05:14:38 chs Exp
*/
/*
* uvm_aobj.c: anonymous memory uvm_object pager
*
* author: Chuck Silvers <chuq@chuq.com>
* started: Jan-1998
*
* - design mostly from Chuck Cranor
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_aobj.c,v 1.61 2003/09/18 13:48:05 drochner Exp $");
#include "opt_uvmhist.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/pool.h>
#include <sys/kernel.h>
#include <uvm/uvm.h>
/*
* an aobj manages anonymous-memory backed uvm_objects. in addition
* to keeping the list of resident pages, it also keeps a list of
* allocated swap blocks. depending on the size of the aobj this list
* of allocated swap blocks is either stored in an array (small objects)
* or in a hash table (large objects).
*/
/*
* local structures
*/
/*
* for hash tables, we break the address space of the aobj into blocks
* of UAO_SWHASH_CLUSTER_SIZE pages. we require the cluster size to
* be a power of two.
*/
#define UAO_SWHASH_CLUSTER_SHIFT 4
#define UAO_SWHASH_CLUSTER_SIZE (1 << UAO_SWHASH_CLUSTER_SHIFT)
/* get the "tag" for this page index */
#define UAO_SWHASH_ELT_TAG(PAGEIDX) \
((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT)
/* given an ELT and a page index, find the swap slot */
#define UAO_SWHASH_ELT_PAGESLOT(ELT, PAGEIDX) \
((ELT)->slots[(PAGEIDX) & (UAO_SWHASH_CLUSTER_SIZE - 1)])
/* given an ELT, return its pageidx base */
#define UAO_SWHASH_ELT_PAGEIDX_BASE(ELT) \
((ELT)->tag << UAO_SWHASH_CLUSTER_SHIFT)
/*
* the swhash hash function
*/
#define UAO_SWHASH_HASH(AOBJ, PAGEIDX) \
(&(AOBJ)->u_swhash[(((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) \
& (AOBJ)->u_swhashmask)])
/*
* the swhash threshhold determines if we will use an array or a
* hash table to store the list of allocated swap blocks.
*/
#define UAO_SWHASH_THRESHOLD (UAO_SWHASH_CLUSTER_SIZE * 4)
#define UAO_USES_SWHASH(AOBJ) \
((AOBJ)->u_pages > UAO_SWHASH_THRESHOLD) /* use hash? */
/*
* the number of buckets in a swhash, with an upper bound
*/
#define UAO_SWHASH_MAXBUCKETS 256
#define UAO_SWHASH_BUCKETS(AOBJ) \
(MIN((AOBJ)->u_pages >> UAO_SWHASH_CLUSTER_SHIFT, \
UAO_SWHASH_MAXBUCKETS))
/*
* uao_swhash_elt: when a hash table is being used, this structure defines
* the format of an entry in the bucket list.
*/
struct uao_swhash_elt {
LIST_ENTRY(uao_swhash_elt) list; /* the hash list */
voff_t tag; /* our 'tag' */
int count; /* our number of active slots */
int slots[UAO_SWHASH_CLUSTER_SIZE]; /* the slots */
};
/*
* uao_swhash: the swap hash table structure
*/
LIST_HEAD(uao_swhash, uao_swhash_elt);
/*
* uao_swhash_elt_pool: pool of uao_swhash_elt structures
*/
struct pool uao_swhash_elt_pool;
/*
* uvm_aobj: the actual anon-backed uvm_object
*
* => the uvm_object is at the top of the structure, this allows
* (struct uvm_aobj *) == (struct uvm_object *)
* => only one of u_swslots and u_swhash is used in any given aobj
*/
struct uvm_aobj {
struct uvm_object u_obj; /* has: lock, pgops, memq, #pages, #refs */
int u_pages; /* number of pages in entire object */
int u_flags; /* the flags (see uvm_aobj.h) */
int *u_swslots; /* array of offset->swapslot mappings */
/*
* hashtable of offset->swapslot mappings
* (u_swhash is an array of bucket heads)
*/
struct uao_swhash *u_swhash;
u_long u_swhashmask; /* mask for hashtable */
LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */
};
/*
* uvm_aobj_pool: pool of uvm_aobj structures
*/
struct pool uvm_aobj_pool;
MALLOC_DEFINE(M_UVMAOBJ, "UVM aobj", "UVM aobj and related structures");
/*
* local functions
*/
static struct uao_swhash_elt *uao_find_swhash_elt
__P((struct uvm_aobj *, int, boolean_t));
static void uao_free __P((struct uvm_aobj *));
static int uao_get __P((struct uvm_object *, voff_t, struct vm_page **,
int *, int, vm_prot_t, int, int));
static boolean_t uao_put __P((struct uvm_object *, voff_t, voff_t, int));
static boolean_t uao_pagein __P((struct uvm_aobj *, int, int));
static boolean_t uao_pagein_page __P((struct uvm_aobj *, int));
/*
* aobj_pager
*
* note that some functions (e.g. put) are handled elsewhere
*/
struct uvm_pagerops aobj_pager = {
NULL, /* init */
uao_reference, /* reference */
uao_detach, /* detach */
NULL, /* fault */
uao_get, /* get */
uao_put, /* flush */
};
/*
* uao_list: global list of active aobjs, locked by uao_list_lock
*/
static LIST_HEAD(aobjlist, uvm_aobj) uao_list;
static struct simplelock uao_list_lock;
/*
* functions
*/
/*
* hash table/array related functions
*/
/*
* uao_find_swhash_elt: find (or create) a hash table entry for a page
* offset.
*
* => the object should be locked by the caller
*/
static struct uao_swhash_elt *
uao_find_swhash_elt(aobj, pageidx, create)
struct uvm_aobj *aobj;
int pageidx;
boolean_t create;
{
struct uao_swhash *swhash;
struct uao_swhash_elt *elt;
voff_t page_tag;
swhash = UAO_SWHASH_HASH(aobj, pageidx);
page_tag = UAO_SWHASH_ELT_TAG(pageidx);
/*
* now search the bucket for the requested tag
*/
LIST_FOREACH(elt, swhash, list) {
if (elt->tag == page_tag) {
return elt;
}
}
if (!create) {
return NULL;
}
/*
* allocate a new entry for the bucket and init/insert it in
*/
elt = pool_get(&uao_swhash_elt_pool, PR_NOWAIT);
if (elt == NULL) {
return NULL;
}
LIST_INSERT_HEAD(swhash, elt, list);
elt->tag = page_tag;
elt->count = 0;
memset(elt->slots, 0, sizeof(elt->slots));
return elt;
}
/*
* uao_find_swslot: find the swap slot number for an aobj/pageidx
*
* => object must be locked by caller
*/
int
uao_find_swslot(uobj, pageidx)
struct uvm_object *uobj;
int pageidx;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct uao_swhash_elt *elt;
/*
* if noswap flag is set, then we never return a slot
*/
if (aobj->u_flags & UAO_FLAG_NOSWAP)
return(0);
/*
* if hashing, look in hash table.
*/
if (UAO_USES_SWHASH(aobj)) {
elt = uao_find_swhash_elt(aobj, pageidx, FALSE);
if (elt)
return(UAO_SWHASH_ELT_PAGESLOT(elt, pageidx));
else
return(0);
}
/*
* otherwise, look in the array
*/
return(aobj->u_swslots[pageidx]);
}
/*
* uao_set_swslot: set the swap slot for a page in an aobj.
*
* => setting a slot to zero frees the slot
* => object must be locked by caller
* => we return the old slot number, or -1 if we failed to allocate
* memory to record the new slot number
*/
int
uao_set_swslot(uobj, pageidx, slot)
struct uvm_object *uobj;
int pageidx, slot;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct uao_swhash_elt *elt;
int oldslot;
UVMHIST_FUNC("uao_set_swslot"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "aobj %p pageidx %d slot %d",
aobj, pageidx, slot, 0);
/*
* if noswap flag is set, then we can't set a non-zero slot.
*/
if (aobj->u_flags & UAO_FLAG_NOSWAP) {
if (slot == 0)
return(0);
printf("uao_set_swslot: uobj = %p\n", uobj);
panic("uao_set_swslot: NOSWAP object");
}
/*
* are we using a hash table? if so, add it in the hash.
*/
if (UAO_USES_SWHASH(aobj)) {
/*
* Avoid allocating an entry just to free it again if
* the page had not swap slot in the first place, and
* we are freeing.
*/
elt = uao_find_swhash_elt(aobj, pageidx, slot != 0);
if (elt == NULL) {
return slot ? -1 : 0;
}
oldslot = UAO_SWHASH_ELT_PAGESLOT(elt, pageidx);
UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) = slot;
/*
* now adjust the elt's reference counter and free it if we've
* dropped it to zero.
*/
if (slot) {
if (oldslot == 0)
elt->count++;
} else {
if (oldslot)
elt->count--;
if (elt->count == 0) {
LIST_REMOVE(elt, list);
pool_put(&uao_swhash_elt_pool, elt);
}
}
} else {
/* we are using an array */
oldslot = aobj->u_swslots[pageidx];
aobj->u_swslots[pageidx] = slot;
}
return (oldslot);
}
/*
* end of hash/array functions
*/
/*
* uao_free: free all resources held by an aobj, and then free the aobj
*
* => the aobj should be dead
*/
static void
uao_free(aobj)
struct uvm_aobj *aobj;
{
int swpgonlydelta = 0;
simple_unlock(&aobj->u_obj.vmobjlock);
if (UAO_USES_SWHASH(aobj)) {
int i, hashbuckets = aobj->u_swhashmask + 1;
/*
* free the swslots from each hash bucket,
* then the hash bucket, and finally the hash table itself.
*/
for (i = 0; i < hashbuckets; i++) {
struct uao_swhash_elt *elt, *next;
for (elt = LIST_FIRST(&aobj->u_swhash[i]);
elt != NULL;
elt = next) {
int j;
for (j = 0; j < UAO_SWHASH_CLUSTER_SIZE; j++) {
int slot = elt->slots[j];
if (slot > 0) {
uvm_swap_free(slot, 1);
swpgonlydelta++;
}
}
next = LIST_NEXT(elt, list);
pool_put(&uao_swhash_elt_pool, elt);
}
}
free(aobj->u_swhash, M_UVMAOBJ);
} else {
int i;
/*
* free the array
*/
for (i = 0; i < aobj->u_pages; i++) {
int slot = aobj->u_swslots[i];
if (slot > 0) {
uvm_swap_free(slot, 1);
swpgonlydelta++;
}
}
free(aobj->u_swslots, M_UVMAOBJ);
}
/*
* finally free the aobj itself
*/
pool_put(&uvm_aobj_pool, aobj);
/*
* adjust the counter of pages only in swap for all
* the swap slots we've freed.
*/
if (swpgonlydelta > 0) {
simple_lock(&uvm.swap_data_lock);
KASSERT(uvmexp.swpgonly >= swpgonlydelta);
uvmexp.swpgonly -= swpgonlydelta;
simple_unlock(&uvm.swap_data_lock);
}
}
/*
* pager functions
*/
/*
* uao_create: create an aobj of the given size and return its uvm_object.
*
* => for normal use, flags are always zero
* => for the kernel object, the flags are:
* UAO_FLAG_KERNOBJ - allocate the kernel object (can only happen once)
* UAO_FLAG_KERNSWAP - enable swapping of kernel object (" ")
*/
struct uvm_object *
uao_create(size, flags)
vsize_t size;
int flags;
{
static struct uvm_aobj kernel_object_store;
static int kobj_alloced = 0;
int pages = round_page(size) >> PAGE_SHIFT;
struct uvm_aobj *aobj;
/*
* malloc a new aobj unless we are asked for the kernel object
*/
if (flags & UAO_FLAG_KERNOBJ) {
KASSERT(!kobj_alloced);
aobj = &kernel_object_store;
aobj->u_pages = pages;
aobj->u_flags = UAO_FLAG_NOSWAP;
aobj->u_obj.uo_refs = UVM_OBJ_KERN;
kobj_alloced = UAO_FLAG_KERNOBJ;
} else if (flags & UAO_FLAG_KERNSWAP) {
KASSERT(kobj_alloced == UAO_FLAG_KERNOBJ);
aobj = &kernel_object_store;
kobj_alloced = UAO_FLAG_KERNSWAP;
} else {
aobj = pool_get(&uvm_aobj_pool, PR_WAITOK);
aobj->u_pages = pages;
aobj->u_flags = 0;
aobj->u_obj.uo_refs = 1;
}
/*
* allocate hash/array if necessary
*
* note: in the KERNSWAP case no need to worry about locking since
* we are still booting we should be the only thread around.
*/
if (flags == 0 || (flags & UAO_FLAG_KERNSWAP) != 0) {
int mflags = (flags & UAO_FLAG_KERNSWAP) != 0 ?
M_NOWAIT : M_WAITOK;
/* allocate hash table or array depending on object size */
if (UAO_USES_SWHASH(aobj)) {
aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(aobj),
HASH_LIST, M_UVMAOBJ, mflags, &aobj->u_swhashmask);
if (aobj->u_swhash == NULL)
panic("uao_create: hashinit swhash failed");
} else {
aobj->u_swslots = malloc(pages * sizeof(int),
M_UVMAOBJ, mflags);
if (aobj->u_swslots == NULL)
panic("uao_create: malloc swslots failed");
memset(aobj->u_swslots, 0, pages * sizeof(int));
}
if (flags) {
aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */
return(&aobj->u_obj);
}
}
/*
* init aobj fields
*/
simple_lock_init(&aobj->u_obj.vmobjlock);
aobj->u_obj.pgops = &aobj_pager;
TAILQ_INIT(&aobj->u_obj.memq);
aobj->u_obj.uo_npages = 0;
/*
* now that aobj is ready, add it to the global list
*/
simple_lock(&uao_list_lock);
LIST_INSERT_HEAD(&uao_list, aobj, u_list);
simple_unlock(&uao_list_lock);
return(&aobj->u_obj);
}
/*
* uao_init: set up aobj pager subsystem
*
* => called at boot time from uvm_pager_init()
*/
void
uao_init(void)
{
static int uao_initialized;
if (uao_initialized)
return;
uao_initialized = TRUE;
LIST_INIT(&uao_list);
simple_lock_init(&uao_list_lock);
/*
* NOTE: Pages fror this pool must not come from a pageable
* kernel map!
*/
pool_init(&uao_swhash_elt_pool, sizeof(struct uao_swhash_elt),
0, 0, 0, "uaoeltpl", NULL);
pool_init(&uvm_aobj_pool, sizeof(struct uvm_aobj), 0, 0, 0,
"aobjpl", &pool_allocator_nointr);
}
/*
* uao_reference: add a ref to an aobj
*
* => aobj must be unlocked
* => just lock it and call the locked version
*/
void
uao_reference(uobj)
struct uvm_object *uobj;
{
simple_lock(&uobj->vmobjlock);
uao_reference_locked(uobj);
simple_unlock(&uobj->vmobjlock);
}
/*
* uao_reference_locked: add a ref to an aobj that is already locked
*
* => aobj must be locked
* this needs to be separate from the normal routine
* since sometimes we need to add a reference to an aobj when
* it's already locked.
*/
void
uao_reference_locked(uobj)
struct uvm_object *uobj;
{
UVMHIST_FUNC("uao_reference"); UVMHIST_CALLED(maphist);
/*
* kernel_object already has plenty of references, leave it alone.
*/
if (UVM_OBJ_IS_KERN_OBJECT(uobj))
return;
uobj->uo_refs++;
UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)",
uobj, uobj->uo_refs,0,0);
}
/*
* uao_detach: drop a reference to an aobj
*
* => aobj must be unlocked
* => just lock it and call the locked version
*/
void
uao_detach(uobj)
struct uvm_object *uobj;
{
simple_lock(&uobj->vmobjlock);
uao_detach_locked(uobj);
}
/*
* uao_detach_locked: drop a reference to an aobj
*
* => aobj must be locked, and is unlocked (or freed) upon return.
* this needs to be separate from the normal routine
* since sometimes we need to detach from an aobj when
* it's already locked.
*/
void
uao_detach_locked(uobj)
struct uvm_object *uobj;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct vm_page *pg;
UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist);
/*
* detaching from kernel_object is a noop.
*/
if (UVM_OBJ_IS_KERN_OBJECT(uobj)) {
simple_unlock(&uobj->vmobjlock);
return;
}
UVMHIST_LOG(maphist," (uobj=0x%x) ref=%d", uobj,uobj->uo_refs,0,0);
uobj->uo_refs--;
if (uobj->uo_refs) {
simple_unlock(&uobj->vmobjlock);
UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0);
return;
}
/*
* remove the aobj from the global list.
*/
simple_lock(&uao_list_lock);
LIST_REMOVE(aobj, u_list);
simple_unlock(&uao_list_lock);
/*
* free all the pages left in the aobj. for each page,
* when the page is no longer busy (and thus after any disk i/o that
* it's involved in is complete), release any swap resources and
* free the page itself.
*/
uvm_lock_pageq();
while ((pg = TAILQ_FIRST(&uobj->memq)) != NULL) {
pmap_page_protect(pg, VM_PROT_NONE);
if (pg->flags & PG_BUSY) {
pg->flags |= PG_WANTED;
uvm_unlock_pageq();
UVM_UNLOCK_AND_WAIT(pg, &uobj->vmobjlock, FALSE,
"uao_det", 0);
simple_lock(&uobj->vmobjlock);
uvm_lock_pageq();
continue;
}
uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT);
uvm_pagefree(pg);
}
uvm_unlock_pageq();
/*
* finally, free the aobj itself.
*/
uao_free(aobj);
}
/*
* uao_put: flush pages out of a uvm object
*
* => object should be locked by caller. we may _unlock_ the object
* if (and only if) we need to clean a page (PGO_CLEANIT).
* XXXJRT Currently, however, we don't. In the case of cleaning
* XXXJRT a page, we simply just deactivate it. Should probably
* XXXJRT handle this better, in the future (although "flushing"
* XXXJRT anonymous memory isn't terribly important).
* => if PGO_CLEANIT is not set, then we will neither unlock the object
* or block.
* => if PGO_ALLPAGE is set, then all pages in the object are valid targets
* for flushing.
* => NOTE: we rely on the fact that the object's memq is a TAILQ and
* that new pages are inserted on the tail end of the list. thus,
* we can make a complete pass through the object in one go by starting
* at the head and working towards the tail (new pages are put in
* front of us).
* => NOTE: we are allowed to lock the page queues, so the caller
* must not be holding the lock on them [e.g. pagedaemon had
* better not call us with the queues locked]
* => we return TRUE unless we encountered some sort of I/O error
* XXXJRT currently never happens, as we never directly initiate
* XXXJRT I/O
*
* note on page traversal:
* we can traverse the pages in an object either by going down the
* linked list in "uobj->memq", or we can go over the address range
* by page doing hash table lookups for each address. depending
* on how many pages are in the object it may be cheaper to do one
* or the other. we set "by_list" to true if we are using memq.
* if the cost of a hash lookup was equal to the cost of the list
* traversal we could compare the number of pages in the start->stop
* range to the total number of pages in the object. however, it
* seems that a hash table lookup is more expensive than the linked
* list traversal, so we multiply the number of pages in the
* start->stop range by a penalty which we define below.
*/
int
uao_put(uobj, start, stop, flags)
struct uvm_object *uobj;
voff_t start, stop;
int flags;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct vm_page *pg, *nextpg, curmp, endmp;
boolean_t by_list;
voff_t curoff;
UVMHIST_FUNC("uao_put"); UVMHIST_CALLED(maphist);
curoff = 0;
if (flags & PGO_ALLPAGES) {
start = 0;
stop = aobj->u_pages << PAGE_SHIFT;
by_list = TRUE; /* always go by the list */
} else {
start = trunc_page(start);
stop = round_page(stop);
if (stop > (aobj->u_pages << PAGE_SHIFT)) {
printf("uao_flush: strange, got an out of range "
"flush (fixed)\n");
stop = aobj->u_pages << PAGE_SHIFT;
}
by_list = (uobj->uo_npages <=
((stop - start) >> PAGE_SHIFT) * UVM_PAGE_HASH_PENALTY);
}
UVMHIST_LOG(maphist,
" flush start=0x%lx, stop=0x%x, by_list=%d, flags=0x%x",
start, stop, by_list, flags);
/*
* Don't need to do any work here if we're not freeing
* or deactivating pages.
*/
if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) {
simple_unlock(&uobj->vmobjlock);
return 0;
}
/*
* Initialize the marker pages. See the comment in
* genfs_putpages() also.
*/
curmp.uobject = uobj;
curmp.offset = (voff_t)-1;
curmp.flags = PG_BUSY;
endmp.uobject = uobj;
endmp.offset = (voff_t)-1;
endmp.flags = PG_BUSY;
/*
* now do it. note: we must update nextpg in the body of loop or we
* will get stuck. we need to use nextpg if we'll traverse the list
* because we may free "pg" before doing the next loop.
*/
if (by_list) {
TAILQ_INSERT_TAIL(&uobj->memq, &endmp, listq);
nextpg = TAILQ_FIRST(&uobj->memq);
PHOLD(curlwp);
} else {
curoff = start;
nextpg = NULL; /* Quell compiler warning */
}
uvm_lock_pageq();
/* locked: both page queues and uobj */
for (;;) {
if (by_list) {
pg = nextpg;
if (pg == &endmp)
break;
nextpg = TAILQ_NEXT(pg, listq);
if (pg->offset < start || pg->offset >= stop)
continue;
} else {
if (curoff < stop) {
pg = uvm_pagelookup(uobj, curoff);
curoff += PAGE_SIZE;
} else
break;
if (pg == NULL)
continue;
}
switch (flags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE)) {
/*
* XXX In these first 3 cases, we always just
* XXX deactivate the page. We may want to
* XXX handle the different cases more specifically
* XXX in the future.
*/
case PGO_CLEANIT|PGO_FREE:
case PGO_CLEANIT|PGO_DEACTIVATE:
case PGO_DEACTIVATE:
deactivate_it:
/* skip the page if it's loaned or wired */
if (pg->loan_count != 0 || pg->wire_count != 0)
continue;
/* ...and deactivate the page. */
pmap_clear_reference(pg);
uvm_pagedeactivate(pg);
continue;
case PGO_FREE:
/*
* If there are multiple references to
* the object, just deactivate the page.
*/
if (uobj->uo_refs > 1)
goto deactivate_it;
/* XXX skip the page if it's loaned or wired */
if (pg->loan_count != 0 || pg->wire_count != 0)
continue;
/*
* wait and try again if the page is busy.
* otherwise free the swap slot and the page.
*/
pmap_page_protect(pg, VM_PROT_NONE);
if (pg->flags & PG_BUSY) {
if (by_list) {
TAILQ_INSERT_BEFORE(pg, &curmp, listq);
}
pg->flags |= PG_WANTED;
uvm_unlock_pageq();
UVM_UNLOCK_AND_WAIT(pg, &uobj->vmobjlock, 0,
"uao_put", 0);
simple_lock(&uobj->vmobjlock);
uvm_lock_pageq();
if (by_list) {
nextpg = TAILQ_NEXT(&curmp, listq);
TAILQ_REMOVE(&uobj->memq, &curmp,
listq);
} else
curoff -= PAGE_SIZE;
continue;
}
uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
uvm_pagefree(pg);
continue;
}
}
uvm_unlock_pageq();
if (by_list) {
TAILQ_REMOVE(&uobj->memq, &endmp, listq);
PRELE(curlwp);
}
simple_unlock(&uobj->vmobjlock);
return 0;
}
/*
* uao_get: fetch me a page
*
* we have three cases:
* 1: page is resident -> just return the page.
* 2: page is zero-fill -> allocate a new page and zero it.
* 3: page is swapped out -> fetch the page from swap.
*
* cases 1 and 2 can be handled with PGO_LOCKED, case 3 cannot.
* so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES),
* then we will need to return EBUSY.
*
* => prefer map unlocked (not required)
* => object must be locked! we will _unlock_ it before starting any I/O.
* => flags: PGO_ALLPAGES: get all of the pages
* PGO_LOCKED: fault data structures are locked
* => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx]
* => NOTE: caller must check for released pages!!
*/
static int
uao_get(uobj, offset, pps, npagesp, centeridx, access_type, advice, flags)
struct uvm_object *uobj;
voff_t offset;
struct vm_page **pps;
int *npagesp;
int centeridx, advice, flags;
vm_prot_t access_type;
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
voff_t current_offset;
struct vm_page *ptmp = NULL; /* Quell compiler warning */
int lcv, gotpages, maxpages, swslot, error, pageidx;
boolean_t done;
UVMHIST_FUNC("uao_get"); UVMHIST_CALLED(pdhist);
UVMHIST_LOG(pdhist, "aobj=%p offset=%d, flags=%d",
aobj, offset, flags,0);
/*
* get number of pages
*/
maxpages = *npagesp;
/*
* step 1: handled the case where fault data structures are locked.
*/
if (flags & PGO_LOCKED) {
/*
* step 1a: get pages that are already resident. only do
* this if the data structures are locked (i.e. the first
* time through).
*/
done = TRUE; /* be optimistic */
gotpages = 0; /* # of pages we got so far */
for (lcv = 0, current_offset = offset ; lcv < maxpages ;
lcv++, current_offset += PAGE_SIZE) {
/* do we care about this page? if not, skip it */
if (pps[lcv] == PGO_DONTCARE)
continue;
ptmp = uvm_pagelookup(uobj, current_offset);
/*
* if page is new, attempt to allocate the page,
* zero-fill'd.
*/
if (ptmp == NULL && uao_find_swslot(&aobj->u_obj,
current_offset >> PAGE_SHIFT) == 0) {
ptmp = uvm_pagealloc(uobj, current_offset,
NULL, UVM_PGA_ZERO);
if (ptmp) {
/* new page */
ptmp->flags &= ~(PG_FAKE);
ptmp->pqflags |= PQ_AOBJ;
goto gotpage;
}
}
/*
* to be useful must get a non-busy page
*/
if (ptmp == NULL || (ptmp->flags & PG_BUSY) != 0) {
if (lcv == centeridx ||
(flags & PGO_ALLPAGES) != 0)
/* need to do a wait or I/O! */
done = FALSE;
continue;
}
/*
* useful page: busy/lock it and plug it in our
* result array
*/
/* caller must un-busy this page */
ptmp->flags |= PG_BUSY;
UVM_PAGE_OWN(ptmp, "uao_get1");
gotpage:
pps[lcv] = ptmp;
gotpages++;
}
/*
* step 1b: now we've either done everything needed or we
* to unlock and do some waiting or I/O.
*/
UVMHIST_LOG(pdhist, "<- done (done=%d)", done, 0,0,0);
*npagesp = gotpages;
if (done)
return 0;
else
return EBUSY;
}
/*
* step 2: get non-resident or busy pages.
* object is locked. data structures are unlocked.
*/
for (lcv = 0, current_offset = offset ; lcv < maxpages ;
lcv++, current_offset += PAGE_SIZE) {
/*
* - skip over pages we've already gotten or don't want
* - skip over pages we don't _have_ to get
*/
if (pps[lcv] != NULL ||
(lcv != centeridx && (flags & PGO_ALLPAGES) == 0))
continue;
pageidx = current_offset >> PAGE_SHIFT;
/*
* we have yet to locate the current page (pps[lcv]). we
* first look for a page that is already at the current offset.
* if we find a page, we check to see if it is busy or
* released. if that is the case, then we sleep on the page
* until it is no longer busy or released and repeat the lookup.
* if the page we found is neither busy nor released, then we
* busy it (so we own it) and plug it into pps[lcv]. this
* 'break's the following while loop and indicates we are
* ready to move on to the next page in the "lcv" loop above.
*
* if we exit the while loop with pps[lcv] still set to NULL,
* then it means that we allocated a new busy/fake/clean page
* ptmp in the object and we need to do I/O to fill in the data.
*/
/* top of "pps" while loop */
while (pps[lcv] == NULL) {
/* look for a resident page */
ptmp = uvm_pagelookup(uobj, current_offset);
/* not resident? allocate one now (if we can) */
if (ptmp == NULL) {
ptmp = uvm_pagealloc(uobj, current_offset,
NULL, 0);
/* out of RAM? */
if (ptmp == NULL) {
simple_unlock(&uobj->vmobjlock);
UVMHIST_LOG(pdhist,
"sleeping, ptmp == NULL\n",0,0,0,0);
uvm_wait("uao_getpage");
simple_lock(&uobj->vmobjlock);
continue;
}
/*
* safe with PQ's unlocked: because we just
* alloc'd the page
*/
ptmp->pqflags |= PQ_AOBJ;
/*
* got new page ready for I/O. break pps while
* loop. pps[lcv] is still NULL.
*/
break;
}
/* page is there, see if we need to wait on it */
if ((ptmp->flags & PG_BUSY) != 0) {
ptmp->flags |= PG_WANTED;
UVMHIST_LOG(pdhist,
"sleeping, ptmp->flags 0x%x\n",
ptmp->flags,0,0,0);
UVM_UNLOCK_AND_WAIT(ptmp, &uobj->vmobjlock,
FALSE, "uao_get", 0);
simple_lock(&uobj->vmobjlock);
continue;
}
/*
* if we get here then the page has become resident and
* unbusy between steps 1 and 2. we busy it now (so we
* own it) and set pps[lcv] (so that we exit the while
* loop).
*/
/* we own it, caller must un-busy */
ptmp->flags |= PG_BUSY;
UVM_PAGE_OWN(ptmp, "uao_get2");
pps[lcv] = ptmp;
}
/*
* if we own the valid page at the correct offset, pps[lcv] will
* point to it. nothing more to do except go to the next page.
*/
if (pps[lcv])
continue; /* next lcv */
/*
* we have a "fake/busy/clean" page that we just allocated.
* do the needed "i/o", either reading from swap or zeroing.
*/
swslot = uao_find_swslot(&aobj->u_obj, pageidx);
/*
* just zero the page if there's nothing in swap.
*/
if (swslot == 0) {
/*
* page hasn't existed before, just zero it.
*/
uvm_pagezero(ptmp);
} else {
UVMHIST_LOG(pdhist, "pagein from swslot %d",
swslot, 0,0,0);
/*
* page in the swapped-out page.
* unlock object for i/o, relock when done.
*/
simple_unlock(&uobj->vmobjlock);
error = uvm_swap_get(ptmp, swslot, PGO_SYNCIO);
simple_lock(&uobj->vmobjlock);
/*
* I/O done. check for errors.
*/
if (error != 0) {
UVMHIST_LOG(pdhist, "<- done (error=%d)",
error,0,0,0);
if (ptmp->flags & PG_WANTED)
wakeup(ptmp);
/*
* remove the swap slot from the aobj
* and mark the aobj as having no real slot.
* don't free the swap slot, thus preventing
* it from being used again.
*/
swslot = uao_set_swslot(&aobj->u_obj, pageidx,
SWSLOT_BAD);
if (swslot > 0) {
uvm_swap_markbad(swslot, 1);
}
uvm_lock_pageq();
uvm_pagefree(ptmp);
uvm_unlock_pageq();
simple_unlock(&uobj->vmobjlock);
return error;
}
}
/*
* we got the page! clear the fake flag (indicates valid
* data now in page) and plug into our result array. note
* that page is still busy.
*
* it is the callers job to:
* => check if the page is released
* => unbusy the page
* => activate the page
*/
ptmp->flags &= ~PG_FAKE;
pps[lcv] = ptmp;
}
/*
* finally, unlock object and return.
*/
simple_unlock(&uobj->vmobjlock);
UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0);
return 0;
}
/*
* uao_dropswap: release any swap resources from this aobj page.
*
* => aobj must be locked or have a reference count of 0.
*/
void
uao_dropswap(uobj, pageidx)
struct uvm_object *uobj;
int pageidx;
{
int slot;
slot = uao_set_swslot(uobj, pageidx, 0);
if (slot) {
uvm_swap_free(slot, 1);
}
}
/*
* page in every page in every aobj that is paged-out to a range of swslots.
*
* => nothing should be locked.
* => returns TRUE if pagein was aborted due to lack of memory.
*/
boolean_t
uao_swap_off(startslot, endslot)
int startslot, endslot;
{
struct uvm_aobj *aobj, *nextaobj;
boolean_t rv;
/*
* walk the list of all aobjs.
*/
restart:
simple_lock(&uao_list_lock);
for (aobj = LIST_FIRST(&uao_list);
aobj != NULL;
aobj = nextaobj) {
/*
* try to get the object lock, start all over if we fail.
* most of the time we'll get the aobj lock,
* so this should be a rare case.
*/
if (!simple_lock_try(&aobj->u_obj.vmobjlock)) {
simple_unlock(&uao_list_lock);
goto restart;
}
/*
* add a ref to the aobj so it doesn't disappear
* while we're working.
*/
uao_reference_locked(&aobj->u_obj);
/*
* now it's safe to unlock the uao list.
*/
simple_unlock(&uao_list_lock);
/*
* page in any pages in the swslot range.
* if there's an error, abort and return the error.
*/
rv = uao_pagein(aobj, startslot, endslot);
if (rv) {
uao_detach_locked(&aobj->u_obj);
return rv;
}
/*
* we're done with this aobj.
* relock the list and drop our ref on the aobj.
*/
simple_lock(&uao_list_lock);
nextaobj = LIST_NEXT(aobj, u_list);
uao_detach_locked(&aobj->u_obj);
}
/*
* done with traversal, unlock the list
*/
simple_unlock(&uao_list_lock);
return FALSE;
}
/*
* page in any pages from aobj in the given range.
*
* => aobj must be locked and is returned locked.
* => returns TRUE if pagein was aborted due to lack of memory.
*/
static boolean_t
uao_pagein(aobj, startslot, endslot)
struct uvm_aobj *aobj;
int startslot, endslot;
{
boolean_t rv;
if (UAO_USES_SWHASH(aobj)) {
struct uao_swhash_elt *elt;
int bucket;
restart:
for (bucket = aobj->u_swhashmask; bucket >= 0; bucket--) {
for (elt = LIST_FIRST(&aobj->u_swhash[bucket]);
elt != NULL;
elt = LIST_NEXT(elt, list)) {
int i;
for (i = 0; i < UAO_SWHASH_CLUSTER_SIZE; i++) {
int slot = elt->slots[i];
/*
* if the slot isn't in range, skip it.
*/
if (slot < startslot ||
slot >= endslot) {
continue;
}
/*
* process the page,
* the start over on this object
* since the swhash elt
* may have been freed.
*/
rv = uao_pagein_page(aobj,
UAO_SWHASH_ELT_PAGEIDX_BASE(elt) + i);
if (rv) {
return rv;
}
goto restart;
}
}
}
} else {
int i;
for (i = 0; i < aobj->u_pages; i++) {
int slot = aobj->u_swslots[i];
/*
* if the slot isn't in range, skip it
*/
if (slot < startslot || slot >= endslot) {
continue;
}
/*
* process the page.
*/
rv = uao_pagein_page(aobj, i);
if (rv) {
return rv;
}
}
}
return FALSE;
}
/*
* page in a page from an aobj. used for swap_off.
* returns TRUE if pagein was aborted due to lack of memory.
*
* => aobj must be locked and is returned locked.
*/
static boolean_t
uao_pagein_page(aobj, pageidx)
struct uvm_aobj *aobj;
int pageidx;
{
struct vm_page *pg;
int rv, npages;
pg = NULL;
npages = 1;
/* locked: aobj */
rv = uao_get(&aobj->u_obj, pageidx << PAGE_SHIFT,
&pg, &npages, 0, VM_PROT_READ|VM_PROT_WRITE, 0, 0);
/* unlocked: aobj */
/*
* relock and finish up.
*/
simple_lock(&aobj->u_obj.vmobjlock);
switch (rv) {
case 0:
break;
case EIO:
case ERESTART:
/*
* nothing more to do on errors.
* ERESTART can only mean that the anon was freed,
* so again there's nothing to do.
*/
return FALSE;
default:
return TRUE;
}
/*
* ok, we've got the page now.
* mark it as dirty, clear its swslot and un-busy it.
*/
uao_dropswap(&aobj->u_obj, pageidx);
/*
* deactivate the page (to make sure it's on a page queue).
*/
uvm_lock_pageq();
if (pg->wire_count == 0)
uvm_pagedeactivate(pg);
uvm_unlock_pageq();
if (pg->flags & PG_WANTED) {
wakeup(pg);
}
pg->flags &= ~(PG_WANTED|PG_BUSY|PG_CLEAN|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
return FALSE;
}