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/* $OpenBSD: uvm_aobj.c,v 1.110 2024/04/13 23:44:11 jsg Exp $ */
/* $NetBSD: uvm_aobj.c,v 1.39 2001/02/18 21:19:08 chs 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.
*
* 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/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/pool.h>
#include <sys/stdint.h>
#include <sys/atomic.h>
#include <uvm/uvm.h>
/*
* An anonymous UVM object (aobj) manages anonymous-memory. In addition to
* keeping the list of resident pages, it may also keep a list of allocated
* swap blocks. Depending on the size of the object, this list is either
* stored in an array (small objects) or in a hash table (large objects).
*/
/*
* Note: for hash tables, we break the address space of the aobj into blocks
* of UAO_SWHASH_CLUSTER_SIZE pages, which shall 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(idx) ((idx) >> UAO_SWHASH_CLUSTER_SHIFT)
#define UAO_SWHASH_ELT_PAGESLOT_IDX(idx) \
((idx) & (UAO_SWHASH_CLUSTER_SIZE - 1))
/* Given an ELT and a page index, find the swap slot. */
#define UAO_SWHASH_ELT_PAGESLOT(elt, idx) \
((elt)->slots[UAO_SWHASH_ELT_PAGESLOT_IDX(idx)])
/* Given an ELT, return its pageidx base. */
#define UAO_SWHASH_ELT_PAGEIDX_BASE(elt) \
((elt)->tag << UAO_SWHASH_CLUSTER_SHIFT)
/* The hash function. */
#define UAO_SWHASH_HASH(aobj, idx) \
(&(aobj)->u_swhash[(((idx) >> UAO_SWHASH_CLUSTER_SHIFT) \
& (aobj)->u_swhashmask)])
/*
* The threshold which determines whether 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)
/* The number of buckets in a hash, with an upper bound. */
#define UAO_SWHASH_MAXBUCKETS 256
#define UAO_SWHASH_BUCKETS(pages) \
(min((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: pgops, memt, #pages, #refs */
int u_pages; /* number of pages in entire object */
int u_flags; /* the flags (see uvm_aobj.h) */
/*
* Either an array or hashtable (array of bucket heads) of
* offset -> swapslot mappings for the aobj.
*/
#define u_swslots u_swap.slot_array
#define u_swhash u_swap.slot_hash
union swslots {
int *slot_array;
struct uao_swhash *slot_hash;
} u_swap;
u_long u_swhashmask; /* mask for hashtable */
LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */
};
struct pool uvm_aobj_pool;
static struct uao_swhash_elt *uao_find_swhash_elt(struct uvm_aobj *, int,
boolean_t);
static boolean_t uao_flush(struct uvm_object *, voff_t,
voff_t, int);
static void uao_free(struct uvm_aobj *);
static int uao_get(struct uvm_object *, voff_t,
vm_page_t *, int *, int, vm_prot_t,
int, int);
static boolean_t uao_pagein(struct uvm_aobj *, int, int);
static boolean_t uao_pagein_page(struct uvm_aobj *, int);
void uao_dropswap_range(struct uvm_object *, voff_t, voff_t);
void uao_shrink_flush(struct uvm_object *, int, int);
int uao_shrink_hash(struct uvm_object *, int);
int uao_shrink_array(struct uvm_object *, int);
int uao_shrink_convert(struct uvm_object *, int);
int uao_grow_hash(struct uvm_object *, int);
int uao_grow_array(struct uvm_object *, int);
int uao_grow_convert(struct uvm_object *, int);
/*
* aobj_pager
*
* note that some functions (e.g. put) are handled elsewhere
*/
const struct uvm_pagerops aobj_pager = {
.pgo_reference = uao_reference,
.pgo_detach = uao_detach,
.pgo_flush = uao_flush,
.pgo_get = uao_get,
};
/*
* uao_list: global list of active aobjs, locked by uao_list_lock
*
* Lock ordering: generally the locking order is object lock, then list lock.
* in the case of swap off we have to iterate over the list, and thus the
* ordering is reversed. In that case we must use trylocking to prevent
* deadlock.
*/
static LIST_HEAD(aobjlist, uvm_aobj) uao_list = LIST_HEAD_INITIALIZER(uao_list);
static struct mutex uao_list_lock = MUTEX_INITIALIZER(IPL_MPFLOOR);
/*
* functions
*/
/*
* hash table/array related functions
*/
/*
* uao_find_swhash_elt: find (or create) a hash table entry for a page
* offset.
*/
static struct uao_swhash_elt *
uao_find_swhash_elt(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); /* first hash to get bucket */
page_tag = UAO_SWHASH_ELT_TAG(pageidx); /* tag to search for */
/*
* 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 | PR_ZERO);
/*
* XXX We cannot sleep here as the hash table might disappear
* from under our feet. And we run the risk of deadlocking
* the pagedeamon. In fact this code will only be called by
* the pagedaemon and allocation will only fail if we
* exhausted the pagedeamon reserve. In that case we're
* doomed anyway, so panic.
*/
if (elt == NULL)
panic("%s: can't allocate entry", __func__);
LIST_INSERT_HEAD(swhash, elt, list);
elt->tag = page_tag;
return elt;
}
/*
* uao_find_swslot: find the swap slot number for an aobj/pageidx
*/
int
uao_find_swslot(struct uvm_object *uobj, int pageidx)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
/*
* 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)) {
struct uao_swhash_elt *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(struct uvm_object *uobj, int pageidx, int slot)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
int oldslot;
KASSERT(rw_write_held(uobj->vmobjlock) || uobj->uo_refs == 0);
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
/*
* if noswap flag is set, then we can't set a slot
*/
if (aobj->u_flags & UAO_FLAG_NOSWAP) {
if (slot == 0)
return 0; /* a clear is ok */
/* but a set is not */
printf("uao_set_swslot: uobj = %p\n", uobj);
panic("uao_set_swslot: attempt to set a slot on a 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.
*/
struct uao_swhash_elt *elt =
uao_find_swhash_elt(aobj, pageidx, slot ? TRUE : FALSE);
if (elt == NULL) {
KASSERT(slot == 0);
return 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(struct uvm_aobj *aobj)
{
struct uvm_object *uobj = &aobj->u_obj;
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
KASSERT(rw_write_held(uobj->vmobjlock));
uao_dropswap_range(uobj, 0, 0);
rw_exit(uobj->vmobjlock);
if (UAO_USES_SWHASH(aobj)) {
/*
* free the hash table itself.
*/
hashfree(aobj->u_swhash, UAO_SWHASH_BUCKETS(aobj->u_pages), M_UVMAOBJ);
} else {
free(aobj->u_swslots, M_UVMAOBJ, aobj->u_pages * sizeof(int));
}
/*
* finally free the aobj itself
*/
uvm_obj_destroy(uobj);
pool_put(&uvm_aobj_pool, aobj);
}
/*
* pager functions
*/
#ifdef TMPFS
/*
* Shrink an aobj to a given number of pages. The procedure is always the same:
* assess the necessity of data structure conversion (hash to array), secure
* resources, flush pages and drop swap slots.
*
*/
void
uao_shrink_flush(struct uvm_object *uobj, int startpg, int endpg)
{
KASSERT(startpg < endpg);
KASSERT(uobj->uo_refs == 1);
uao_flush(uobj, (voff_t)startpg << PAGE_SHIFT,
(voff_t)endpg << PAGE_SHIFT, PGO_FREE);
uao_dropswap_range(uobj, startpg, endpg);
}
int
uao_shrink_hash(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct uao_swhash *new_swhash;
struct uao_swhash_elt *elt;
unsigned long new_hashmask;
int i;
KASSERT(UAO_USES_SWHASH(aobj));
/*
* If the size of the hash table doesn't change, all we need to do is
* to adjust the page count.
*/
if (UAO_SWHASH_BUCKETS(aobj->u_pages) == UAO_SWHASH_BUCKETS(pages)) {
uao_shrink_flush(uobj, pages, aobj->u_pages);
aobj->u_pages = pages;
return 0;
}
new_swhash = hashinit(UAO_SWHASH_BUCKETS(pages), M_UVMAOBJ,
M_WAITOK | M_CANFAIL, &new_hashmask);
if (new_swhash == NULL)
return ENOMEM;
uao_shrink_flush(uobj, pages, aobj->u_pages);
/*
* Even though the hash table size is changing, the hash of the buckets
* we are interested in copying should not change.
*/
for (i = 0; i < UAO_SWHASH_BUCKETS(aobj->u_pages); i++) {
while (LIST_EMPTY(&aobj->u_swhash[i]) == 0) {
elt = LIST_FIRST(&aobj->u_swhash[i]);
LIST_REMOVE(elt, list);
LIST_INSERT_HEAD(&new_swhash[i], elt, list);
}
}
hashfree(aobj->u_swhash, UAO_SWHASH_BUCKETS(aobj->u_pages), M_UVMAOBJ);
aobj->u_swhash = new_swhash;
aobj->u_pages = pages;
aobj->u_swhashmask = new_hashmask;
return 0;
}
int
uao_shrink_convert(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct uao_swhash_elt *elt;
int i, *new_swslots;
new_swslots = mallocarray(pages, sizeof(int), M_UVMAOBJ,
M_WAITOK | M_CANFAIL | M_ZERO);
if (new_swslots == NULL)
return ENOMEM;
uao_shrink_flush(uobj, pages, aobj->u_pages);
/* Convert swap slots from hash to array. */
for (i = 0; i < pages; i++) {
elt = uao_find_swhash_elt(aobj, i, FALSE);
if (elt != NULL) {
new_swslots[i] = UAO_SWHASH_ELT_PAGESLOT(elt, i);
if (new_swslots[i] != 0)
elt->count--;
if (elt->count == 0) {
LIST_REMOVE(elt, list);
pool_put(&uao_swhash_elt_pool, elt);
}
}
}
hashfree(aobj->u_swhash, UAO_SWHASH_BUCKETS(aobj->u_pages), M_UVMAOBJ);
aobj->u_swslots = new_swslots;
aobj->u_pages = pages;
return 0;
}
int
uao_shrink_array(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
int i, *new_swslots;
new_swslots = mallocarray(pages, sizeof(int), M_UVMAOBJ,
M_WAITOK | M_CANFAIL | M_ZERO);
if (new_swslots == NULL)
return ENOMEM;
uao_shrink_flush(uobj, pages, aobj->u_pages);
for (i = 0; i < pages; i++)
new_swslots[i] = aobj->u_swslots[i];
free(aobj->u_swslots, M_UVMAOBJ, aobj->u_pages * sizeof(int));
aobj->u_swslots = new_swslots;
aobj->u_pages = pages;
return 0;
}
int
uao_shrink(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
KASSERT(pages < aobj->u_pages);
/*
* Distinguish between three possible cases:
* 1. aobj uses hash and must be converted to array.
* 2. aobj uses array and array size needs to be adjusted.
* 3. aobj uses hash and hash size needs to be adjusted.
*/
if (pages > UAO_SWHASH_THRESHOLD)
return uao_shrink_hash(uobj, pages); /* case 3 */
else if (aobj->u_pages > UAO_SWHASH_THRESHOLD)
return uao_shrink_convert(uobj, pages); /* case 1 */
else
return uao_shrink_array(uobj, pages); /* case 2 */
}
/*
* Grow an aobj to a given number of pages. Right now we only adjust the swap
* slots. We could additionally handle page allocation directly, so that they
* don't happen through uvm_fault(). That would allow us to use another
* mechanism for the swap slots other than malloc(). It is thus mandatory that
* the caller of these functions does not allow faults to happen in case of
* growth error.
*/
int
uao_grow_array(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
int i, *new_swslots;
KASSERT(aobj->u_pages <= UAO_SWHASH_THRESHOLD);
new_swslots = mallocarray(pages, sizeof(int), M_UVMAOBJ,
M_WAITOK | M_CANFAIL | M_ZERO);
if (new_swslots == NULL)
return ENOMEM;
for (i = 0; i < aobj->u_pages; i++)
new_swslots[i] = aobj->u_swslots[i];
free(aobj->u_swslots, M_UVMAOBJ, aobj->u_pages * sizeof(int));
aobj->u_swslots = new_swslots;
aobj->u_pages = pages;
return 0;
}
int
uao_grow_hash(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct uao_swhash *new_swhash;
struct uao_swhash_elt *elt;
unsigned long new_hashmask;
int i;
KASSERT(pages > UAO_SWHASH_THRESHOLD);
/*
* If the size of the hash table doesn't change, all we need to do is
* to adjust the page count.
*/
if (UAO_SWHASH_BUCKETS(aobj->u_pages) == UAO_SWHASH_BUCKETS(pages)) {
aobj->u_pages = pages;
return 0;
}
KASSERT(UAO_SWHASH_BUCKETS(aobj->u_pages) < UAO_SWHASH_BUCKETS(pages));
new_swhash = hashinit(UAO_SWHASH_BUCKETS(pages), M_UVMAOBJ,
M_WAITOK | M_CANFAIL, &new_hashmask);
if (new_swhash == NULL)
return ENOMEM;
for (i = 0; i < UAO_SWHASH_BUCKETS(aobj->u_pages); i++) {
while (LIST_EMPTY(&aobj->u_swhash[i]) == 0) {
elt = LIST_FIRST(&aobj->u_swhash[i]);
LIST_REMOVE(elt, list);
LIST_INSERT_HEAD(&new_swhash[i], elt, list);
}
}
hashfree(aobj->u_swhash, UAO_SWHASH_BUCKETS(aobj->u_pages), M_UVMAOBJ);
aobj->u_swhash = new_swhash;
aobj->u_pages = pages;
aobj->u_swhashmask = new_hashmask;
return 0;
}
int
uao_grow_convert(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct uao_swhash *new_swhash;
struct uao_swhash_elt *elt;
unsigned long new_hashmask;
int i, *old_swslots;
new_swhash = hashinit(UAO_SWHASH_BUCKETS(pages), M_UVMAOBJ,
M_WAITOK | M_CANFAIL, &new_hashmask);
if (new_swhash == NULL)
return ENOMEM;
/* Set these now, so we can use uao_find_swhash_elt(). */
old_swslots = aobj->u_swslots;
aobj->u_swhash = new_swhash;
aobj->u_swhashmask = new_hashmask;
for (i = 0; i < aobj->u_pages; i++) {
if (old_swslots[i] != 0) {
elt = uao_find_swhash_elt(aobj, i, TRUE);
elt->count++;
UAO_SWHASH_ELT_PAGESLOT(elt, i) = old_swslots[i];
}
}
free(old_swslots, M_UVMAOBJ, aobj->u_pages * sizeof(int));
aobj->u_pages = pages;
return 0;
}
int
uao_grow(struct uvm_object *uobj, int pages)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
KASSERT(pages > aobj->u_pages);
/*
* Distinguish between three possible cases:
* 1. aobj uses hash and hash size needs to be adjusted.
* 2. aobj uses array and array size needs to be adjusted.
* 3. aobj uses array and must be converted to hash.
*/
if (pages <= UAO_SWHASH_THRESHOLD)
return uao_grow_array(uobj, pages); /* case 2 */
else if (aobj->u_pages > UAO_SWHASH_THRESHOLD)
return uao_grow_hash(uobj, pages); /* case 1 */
else
return uao_grow_convert(uobj, pages);
}
#endif /* TMPFS */
/*
* uao_create: create an aobj of the given size and return its uvm_object.
*
* => for normal use, flags are zero or UAO_FLAG_CANFAIL.
* => 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(vsize_t size, int flags)
{
static struct uvm_aobj kernel_object_store;
static struct rwlock bootstrap_kernel_object_lock;
static int kobj_alloced = 0;
int pages = round_page(size) >> PAGE_SHIFT;
struct uvm_aobj *aobj;
int refs;
/*
* Allocate a new aobj, unless kernel object is requested.
*/
if (flags & UAO_FLAG_KERNOBJ) {
KASSERT(!kobj_alloced);
aobj = &kernel_object_store;
aobj->u_pages = pages;
aobj->u_flags = UAO_FLAG_NOSWAP;
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;
refs = 1;
}
/*
* allocate hash/array if necessary
*/
if (flags == 0 || (flags & (UAO_FLAG_KERNSWAP | UAO_FLAG_CANFAIL))) {
int mflags;
if (flags)
mflags = M_NOWAIT;
else
mflags = M_WAITOK;
/* allocate hash table or array depending on object size */
if (UAO_USES_SWHASH(aobj)) {
aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(pages),
M_UVMAOBJ, mflags, &aobj->u_swhashmask);
if (aobj->u_swhash == NULL) {
if (flags & UAO_FLAG_CANFAIL) {
pool_put(&uvm_aobj_pool, aobj);
return NULL;
}
panic("uao_create: hashinit swhash failed");
}
} else {
aobj->u_swslots = mallocarray(pages, sizeof(int),
M_UVMAOBJ, mflags|M_ZERO);
if (aobj->u_swslots == NULL) {
if (flags & UAO_FLAG_CANFAIL) {
pool_put(&uvm_aobj_pool, aobj);
return NULL;
}
panic("uao_create: malloc swslots failed");
}
}
if (flags & UAO_FLAG_KERNSWAP) {
aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */
return &aobj->u_obj;
/* done! */
}
}
/*
* Initialise UVM object.
*/
uvm_obj_init(&aobj->u_obj, &aobj_pager, refs);
if (flags & UAO_FLAG_KERNOBJ) {
/* Use a temporary static lock for kernel_object. */
rw_init(&bootstrap_kernel_object_lock, "kobjlk");
uvm_obj_setlock(&aobj->u_obj, &bootstrap_kernel_object_lock);
}
/*
* now that aobj is ready, add it to the global list
*/
mtx_enter(&uao_list_lock);
LIST_INSERT_HEAD(&uao_list, aobj, u_list);
mtx_leave(&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)
{
/*
* NOTE: Pages for this pool must not come from a pageable
* kernel map!
*/
pool_init(&uao_swhash_elt_pool, sizeof(struct uao_swhash_elt), 0,
IPL_NONE, PR_WAITOK, "uaoeltpl", NULL);
pool_init(&uvm_aobj_pool, sizeof(struct uvm_aobj), 0,
IPL_NONE, PR_WAITOK, "aobjpl", NULL);
}
/*
* uao_reference: hold a reference to an anonymous UVM object.
*/
void
uao_reference(struct uvm_object *uobj)
{
/* Kernel object is persistent. */
if (UVM_OBJ_IS_KERN_OBJECT(uobj))
return;
atomic_inc_int(&uobj->uo_refs);
}
/*
* uao_detach: drop a reference to an anonymous UVM object.
*/
void
uao_detach(struct uvm_object *uobj)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
struct vm_page *pg;
/*
* Detaching from kernel_object is a NOP.
*/
if (UVM_OBJ_IS_KERN_OBJECT(uobj))
return;
/*
* Drop the reference. If it was the last one, destroy the object.
*/
if (atomic_dec_int_nv(&uobj->uo_refs) > 0) {
return;
}
/*
* Remove the aobj from the global list.
*/
mtx_enter(&uao_list_lock);
LIST_REMOVE(aobj, u_list);
mtx_leave(&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 is
* involved in is complete), release any swap resources and free
* the page itself.
*/
rw_enter(uobj->vmobjlock, RW_WRITE);
while ((pg = RBT_ROOT(uvm_objtree, &uobj->memt)) != NULL) {
pmap_page_protect(pg, PROT_NONE);
if (pg->pg_flags & PG_BUSY) {
uvm_pagewait(pg, uobj->vmobjlock, "uao_det");
rw_enter(uobj->vmobjlock, RW_WRITE);
continue;
}
uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT);
uvm_lock_pageq();
uvm_pagefree(pg);
uvm_unlock_pageq();
}
/*
* Finally, free the anonymous UVM object itself.
*/
uao_free(aobj);
}
/*
* uao_flush: flush pages out of a uvm object
*
* => if PGO_CLEANIT is not set, then we will not block.
* => if PGO_ALLPAGE is set, then all pages in the object are valid targets
* for flushing.
* => 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
*/
boolean_t
uao_flush(struct uvm_object *uobj, voff_t start, voff_t stop, int flags)
{
struct uvm_aobj *aobj = (struct uvm_aobj *) uobj;
struct vm_page *pg;
voff_t curoff;
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
KASSERT(rw_write_held(uobj->vmobjlock));
if (flags & PGO_ALLPAGES) {
start = 0;
stop = (voff_t)aobj->u_pages << PAGE_SHIFT;
} else {
start = trunc_page(start);
stop = round_page(stop);
if (stop > ((voff_t)aobj->u_pages << PAGE_SHIFT)) {
printf("uao_flush: strange, got an out of range "
"flush (fixed)\n");
stop = (voff_t)aobj->u_pages << PAGE_SHIFT;
}
}
/*
* Don't need to do any work here if we're not freeing
* or deactivating pages.
*/
if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) {
return TRUE;
}
curoff = start;
for (;;) {
if (curoff < stop) {
pg = uvm_pagelookup(uobj, curoff);
curoff += PAGE_SIZE;
if (pg == NULL)
continue;
} else {
break;
}
/* Make sure page is unbusy, else wait for it. */
if (pg->pg_flags & PG_BUSY) {
uvm_pagewait(pg, uobj->vmobjlock, "uaoflsh");
rw_enter(uobj->vmobjlock, RW_WRITE);
curoff -= PAGE_SIZE;
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:
/* FALLTHROUGH */
case PGO_CLEANIT|PGO_DEACTIVATE:
/* FALLTHROUGH */
case PGO_DEACTIVATE:
deactivate_it:
if (pg->wire_count != 0)
continue;
uvm_lock_pageq();
pmap_page_protect(pg, PROT_NONE);
uvm_pagedeactivate(pg);
uvm_unlock_pageq();
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 wired */
if (pg->wire_count != 0)
continue;
/*
* free the swap slot and the page.
*/
pmap_page_protect(pg, PROT_NONE);
/*
* freeing swapslot here is not strictly necessary.
* however, leaving it here doesn't save much
* because we need to update swap accounting anyway.
*/
uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
uvm_lock_pageq();
uvm_pagefree(pg);
uvm_unlock_pageq();
continue;
default:
panic("uao_flush: weird flags");
}
}
return TRUE;
}
/*
* 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 can be handled with PGO_LOCKED, cases 2 and 3 cannot.
* so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES),
* then we will need to return VM_PAGER_UNLOCK.
*
* => 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(struct uvm_object *uobj, voff_t offset, struct vm_page **pps,
int *npagesp, int centeridx, vm_prot_t access_type, int advice, int flags)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
voff_t current_offset;
vm_page_t ptmp;
int lcv, gotpages, maxpages, swslot, rv, pageidx;
boolean_t done;
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
KASSERT(rw_write_held(uobj->vmobjlock));
/*
* get number of pages
*/
maxpages = *npagesp;
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(uobj,
current_offset >> PAGE_SHIFT) == 0) {
ptmp = uvm_pagealloc(uobj, current_offset,
NULL, UVM_PGA_ZERO);
if (ptmp) {
/* new page */
atomic_clearbits_int(&ptmp->pg_flags,
PG_BUSY|PG_FAKE);
atomic_setbits_int(&ptmp->pg_flags,
PQ_AOBJ);
UVM_PAGE_OWN(ptmp, NULL);
}
}
/*
* to be useful must get a non-busy page
*/
if (ptmp == NULL ||
(ptmp->pg_flags & PG_BUSY) != 0) {
if (lcv == centeridx ||
(flags & PGO_ALLPAGES) != 0)
/* need to do a wait or I/O! */
done = FALSE;
continue;
}
/*
* useful page: plug it in our result array
*/
atomic_setbits_int(&ptmp->pg_flags, PG_BUSY);
UVM_PAGE_OWN(ptmp, "uao_get1");
pps[lcv] = ptmp;
gotpages++;
}
/*
* step 1b: now we've either done everything needed or we
* to unlock and do some waiting or I/O.
*/
*npagesp = gotpages;
if (done)
/* bingo! */
return VM_PAGER_OK;
else
/* EEK! Need to unlock and I/O */
return VM_PAGER_UNLOCK;
}
/*
* step 2: get non-resident or busy pages.
* 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) {
rw_exit(uobj->vmobjlock);
uvm_wait("uao_getpage");
rw_enter(uobj->vmobjlock, RW_WRITE);
/* goto top of pps while loop */
continue;
}
/*
* safe with PQ's unlocked: because we just
* alloc'd the page
*/
atomic_setbits_int(&ptmp->pg_flags, 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->pg_flags & PG_BUSY) != 0) {
uvm_pagewait(ptmp, uobj->vmobjlock, "uao_get");
rw_enter(uobj->vmobjlock, RW_WRITE);
continue; /* goto top of pps while loop */
}
/*
* if we get here then the page is resident and
* unbusy. we busy it now (so we own it).
*/
/* we own it, caller must un-busy */
atomic_setbits_int(&ptmp->pg_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(uobj, 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 {
/*
* page in the swapped-out page.
* unlock object for i/o, relock when done.
*/
rw_exit(uobj->vmobjlock);
rv = uvm_swap_get(ptmp, swslot, PGO_SYNCIO);
rw_enter(uobj->vmobjlock, RW_WRITE);
/*
* I/O done. check for errors.
*/
if (rv != VM_PAGER_OK) {
/*
* 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);
uvm_swap_markbad(swslot, 1);
if (ptmp->pg_flags & PG_WANTED)
wakeup(ptmp);
atomic_clearbits_int(&ptmp->pg_flags,
PG_WANTED|PG_BUSY);
UVM_PAGE_OWN(ptmp, NULL);
uvm_lock_pageq();
uvm_pagefree(ptmp);
uvm_unlock_pageq();
rw_exit(uobj->vmobjlock);
return rv;
}
}
/*
* 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
*/
atomic_clearbits_int(&ptmp->pg_flags, PG_FAKE);
pmap_clear_modify(ptmp); /* ... and clean */
pps[lcv] = ptmp;
} /* lcv loop */
rw_exit(uobj->vmobjlock);
return VM_PAGER_OK;
}
/*
* uao_dropswap: release any swap resources from this aobj page.
*
* => aobj must be locked or have a reference count of 0.
*/
int
uao_dropswap(struct uvm_object *uobj, int pageidx)
{
int slot;
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
slot = uao_set_swslot(uobj, pageidx, 0);
if (slot) {
uvm_swap_free(slot, 1);
}
return slot;
}
/*
* page in every page in every aobj that is paged-out to a range of swslots.
*
* => aobj must be locked and is returned locked.
* => returns TRUE if pagein was aborted due to lack of memory.
*/
boolean_t
uao_swap_off(int startslot, int endslot)
{
struct uvm_aobj *aobj;
/*
* Walk the list of all anonymous UVM objects. Grab the first.
*/
mtx_enter(&uao_list_lock);
if ((aobj = LIST_FIRST(&uao_list)) == NULL) {
mtx_leave(&uao_list_lock);
return FALSE;
}
uao_reference(&aobj->u_obj);
do {
struct uvm_aobj *nextaobj;
boolean_t rv;
/*
* Prefetch the next object and immediately hold a reference
* on it, so neither the current nor the next entry could
* disappear while we are iterating.
*/
if ((nextaobj = LIST_NEXT(aobj, u_list)) != NULL) {
uao_reference(&nextaobj->u_obj);
}
mtx_leave(&uao_list_lock);
/*
* Page in all pages in the swap slot range.
*/
rw_enter(aobj->u_obj.vmobjlock, RW_WRITE);
rv = uao_pagein(aobj, startslot, endslot);
rw_exit(aobj->u_obj.vmobjlock);
/* Drop the reference of the current object. */
uao_detach(&aobj->u_obj);
if (rv) {
if (nextaobj) {
uao_detach(&nextaobj->u_obj);
}
return rv;
}
aobj = nextaobj;
mtx_enter(&uao_list_lock);
} while (aobj);
/*
* done with traversal, unlock the list
*/
mtx_leave(&uao_list_lock);
return FALSE;
}
/*
* page in any pages from aobj in the given range.
*
* => returns TRUE if pagein was aborted due to lack of memory.
*/
static boolean_t
uao_pagein(struct uvm_aobj *aobj, int startslot, int 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;
}
/*
* uao_pagein_page: page in a single page from an anonymous UVM object.
*
* => Returns TRUE if pagein was aborted due to lack of memory.
*/
static boolean_t
uao_pagein_page(struct uvm_aobj *aobj, int pageidx)
{
struct uvm_object *uobj = &aobj->u_obj;
struct vm_page *pg;
int rv, npages;
pg = NULL;
npages = 1;
KASSERT(rw_write_held(uobj->vmobjlock));
rv = uao_get(&aobj->u_obj, (voff_t)pageidx << PAGE_SHIFT,
&pg, &npages, 0, PROT_READ | PROT_WRITE, 0, 0);
/*
* relock and finish up.
*/
rw_enter(uobj->vmobjlock, RW_WRITE);
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;
}
/*
* ok, we've got the page now.
* mark it as dirty, clear its swslot and un-busy it.
*/
uao_dropswap(&aobj->u_obj, pageidx);
atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_CLEAN|PG_FAKE);
UVM_PAGE_OWN(pg, NULL);
/*
* deactivate the page (to put it on a page queue).
*/
pmap_clear_reference(pg);
uvm_lock_pageq();
uvm_pagedeactivate(pg);
uvm_unlock_pageq();
return FALSE;
}
/*
* uao_dropswap_range: drop swapslots in the range.
*
* => aobj must be locked and is returned locked.
* => start is inclusive. end is exclusive.
*/
void
uao_dropswap_range(struct uvm_object *uobj, voff_t start, voff_t end)
{
struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
int swpgonlydelta = 0;
KASSERT(UVM_OBJ_IS_AOBJ(uobj));
KASSERT(rw_write_held(uobj->vmobjlock));
if (end == 0) {
end = INT64_MAX;
}
if (UAO_USES_SWHASH(aobj)) {
int i, hashbuckets = aobj->u_swhashmask + 1;
voff_t taghi;
voff_t taglo;
taglo = UAO_SWHASH_ELT_TAG(start);
taghi = UAO_SWHASH_ELT_TAG(end);
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 startidx, endidx;
int j;
next = LIST_NEXT(elt, list);
if (elt->tag < taglo || taghi < elt->tag) {
continue;
}
if (elt->tag == taglo) {
startidx =
UAO_SWHASH_ELT_PAGESLOT_IDX(start);
} else {
startidx = 0;
}
if (elt->tag == taghi) {
endidx =
UAO_SWHASH_ELT_PAGESLOT_IDX(end);
} else {
endidx = UAO_SWHASH_CLUSTER_SIZE;
}
for (j = startidx; j < endidx; j++) {
int slot = elt->slots[j];
KASSERT(uvm_pagelookup(&aobj->u_obj,
(voff_t)(UAO_SWHASH_ELT_PAGEIDX_BASE(elt)
+ j) << PAGE_SHIFT) == NULL);
if (slot > 0) {
uvm_swap_free(slot, 1);
swpgonlydelta++;
KASSERT(elt->count > 0);
elt->slots[j] = 0;
elt->count--;
}
}
if (elt->count == 0) {
LIST_REMOVE(elt, list);
pool_put(&uao_swhash_elt_pool, elt);
}
}
}
} else {
int i;
if (aobj->u_pages < end) {
end = aobj->u_pages;
}
for (i = start; i < end; i++) {
int slot = aobj->u_swslots[i];
if (slot > 0) {
uvm_swap_free(slot, 1);
swpgonlydelta++;
}
}
}
/*
* adjust the counter of pages only in swap for all
* the swap slots we've freed.
*/
if (swpgonlydelta > 0) {
KASSERT(uvmexp.swpgonly >= swpgonlydelta);
atomic_add_int(&uvmexp.swpgonly, -swpgonlydelta);
}
}
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