/* $OpenBSD: uvm_aobj.c,v 1.10 2001/06/23 19:24:33 smart Exp $ */ /* $NetBSD: uvm_aobj.c,v 1.25 1999/08/21 02:19:05 thorpej 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 * started: Jan-1998 * * - design mostly from Chuck Cranor */ #include #include #include #include #include #include #include #include #include /* * 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 */ vaddr_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_device *) == (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; /* * local functions */ static void uao_init __P((void)); static struct uao_swhash_elt *uao_find_swhash_elt __P((struct uvm_aobj *, int, boolean_t)); static int uao_find_swslot __P((struct uvm_aobj *, int)); static boolean_t uao_flush __P((struct uvm_object *, vaddr_t, vaddr_t, int)); static void uao_free __P((struct uvm_aobj *)); static int uao_get __P((struct uvm_object *, vaddr_t, vm_page_t *, int *, int, vm_prot_t, int, int)); static boolean_t uao_releasepg __P((struct vm_page *, struct vm_page **)); /* * aobj_pager * * note that some functions (e.g. put) are handled elsewhere */ struct uvm_pagerops aobj_pager = { uao_init, /* init */ uao_reference, /* reference */ uao_detach, /* detach */ NULL, /* fault */ uao_flush, /* flush */ uao_get, /* get */ NULL, /* asyncget */ NULL, /* put (done by pagedaemon) */ NULL, /* cluster */ NULL, /* mk_pcluster */ uvm_shareprot, /* shareprot */ NULL, /* aiodone */ uao_releasepg /* releasepg */ }; /* * uao_list: global list of active aobjs, locked by uao_list_lock */ static LIST_HEAD(aobjlist, uvm_aobj) uao_list; static simple_lock_data_t 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; int 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 */ for (elt = swhash->lh_first; elt != NULL; elt = elt->list.le_next) { if (elt->tag == page_tag) return(elt); } /* fail now if we are not allowed to create a new entry in the bucket */ if (!create) return NULL; /* * allocate a new entry for the bucket and init/insert it in */ elt = pool_get(&uao_swhash_elt_pool, PR_WAITOK); 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 */ __inline static int uao_find_swslot(aobj, pageidx) struct uvm_aobj *aobj; int pageidx; { /* * 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(NULL); } /* * 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 */ int uao_set_swslot(uobj, pageidx, slot) struct uvm_object *uobj; int pageidx, slot; { struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 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 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) { #ifdef DIAGNOSTIC if (slot) panic("uao_set_swslot: didn't create elt"); #endif 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. */ /* an allocation? */ if (slot) { if (oldslot == 0) elt->count++; } else { /* freeing slot ... */ if (oldslot) /* to be safe */ 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; { 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 = aobj->u_swhash[i].lh_first; elt != NULL; elt = next) { int j; for (j = 0; j < UAO_SWHASH_CLUSTER_SIZE; j++) { int slot = elt->slots[j]; if (slot) { uvm_swap_free(slot, 1); /* * this page is no longer * only in swap. */ simple_lock(&uvm.swap_data_lock); uvmexp.swpgonly--; simple_unlock(&uvm.swap_data_lock); } } next = elt->list.le_next; 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) { uvm_swap_free(slot, 1); /* this page is no longer only in swap. */ simple_lock(&uvm.swap_data_lock); uvmexp.swpgonly--; simple_unlock(&uvm.swap_data_lock); } } FREE(aobj->u_swslots, M_UVMAOBJ); } /* * finally free the aobj itself */ pool_put(&uvm_aobj_pool, aobj); } /* * 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; /* home of kernel_object */ static int kobj_alloced = 0; /* not allocated yet */ 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) { /* want kernel object? */ if (kobj_alloced) panic("uao_create: kernel object already allocated"); /* * XXXTHORPEJ: Need to call this now, so the pool gets * initialized! */ uao_init(); aobj = &kernel_object_store; aobj->u_pages = pages; aobj->u_flags = UAO_FLAG_NOSWAP; /* no swap to start */ /* we are special, we never die */ aobj->u_obj.uo_refs = UVM_OBJ_KERN; kobj_alloced = UAO_FLAG_KERNOBJ; } else if (flags & UAO_FLAG_KERNSWAP) { aobj = &kernel_object_store; if (kobj_alloced != UAO_FLAG_KERNOBJ) panic("uao_create: asked to enable swap on kernel object"); kobj_alloced = UAO_FLAG_KERNSWAP; } else { /* normal object */ aobj = pool_get(&uvm_aobj_pool, PR_WAITOK); aobj->u_pages = pages; aobj->u_flags = 0; /* normal object */ aobj->u_obj.uo_refs = 1; /* start with 1 reference */ } /* * 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), M_UVMAOBJ, mflags, &aobj->u_swhashmask); if (aobj->u_swhash == NULL) panic("uao_create: hashinit swhash failed"); } else { MALLOC(aobj->u_swslots, int *, 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); /* done! */ } } /* * 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 * XXXCHS: uao_init hasn't been called'd in the KERNOBJ case, * do we really need the kernel object on this list anyway? */ simple_lock(&uao_list_lock); LIST_INSERT_HEAD(&uao_list, aobj, u_list); simple_unlock(&uao_list_lock); /* * done! */ return(&aobj->u_obj); } /* * uao_init: set up aobj pager subsystem * * => called at boot time from uvm_pager_init() */ static void uao_init() { 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", 0, NULL, NULL, M_UVMAOBJ); pool_init(&uvm_aobj_pool, sizeof(struct uvm_aobj), 0, 0, 0, "aobjpl", 0, pool_page_alloc_nointr, pool_page_free_nointr, M_UVMAOBJ); } /* * uao_reference: add a ref to an aobj * * => aobj must be unlocked (we will lock it) */ void uao_reference(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; simple_lock(&uobj->vmobjlock); uobj->uo_refs++; /* bump! */ UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)", uobj, uobj->uo_refs,0,0); simple_unlock(&uobj->vmobjlock); } /* * uao_detach: drop a reference to an aobj * * => aobj must be unlocked, we will lock it */ void uao_detach(uobj) struct uvm_object *uobj; { struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; struct vm_page *pg; boolean_t busybody; UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist); /* * detaching from kernel_object is a noop. */ if (UVM_OBJ_IS_KERN_OBJECT(uobj)) return; simple_lock(&uobj->vmobjlock); UVMHIST_LOG(maphist," (uobj=0x%x) ref=%d", uobj,uobj->uo_refs,0,0); uobj->uo_refs--; /* drop ref! */ if (uobj->uo_refs) { /* still more 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 that aren't PG_BUSY, mark for release any that are. */ busybody = FALSE; for (pg = uobj->memq.tqh_first ; pg != NULL ; pg = pg->listq.tqe_next) { if (pg->flags & PG_BUSY) { pg->flags |= PG_RELEASED; busybody = TRUE; continue; } /* zap the mappings, free the swap slot, free the page */ pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE); uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT); uvm_lock_pageq(); uvm_pagefree(pg); uvm_unlock_pageq(); } /* * if we found any busy pages, we're done for now. * mark the aobj for death, releasepg will finish up for us. */ if (busybody) { aobj->u_flags |= UAO_FLAG_KILLME; simple_unlock(&aobj->u_obj.vmobjlock); return; } /* * finally, free the rest. */ uao_free(aobj); } /* * uao_flush: "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 * * comment on "cleaning" object and PG_BUSY pages: * this routine is holding the lock on the object. the only time * that is can run into a PG_BUSY page that it does not own is if * some other process has started I/O on the page (e.g. either * a pagein or a pageout). if the PG_BUSY page is being paged * in, then it can not be dirty (!PG_CLEAN) because no one has * had a change to modify it yet. if the PG_BUSY page is being * paged out then it means that someone else has already started * cleaning the page for us (how nice!). in this case, if we * have syncio specified, then after we make our pass through the * object we need to wait for the other PG_BUSY pages to clear * off (i.e. we need to do an iosync). also note that once a * page is PG_BUSY is must stary in its object until it is un-busyed. * XXXJRT We never actually do this, as we are "flushing" anonymous * XXXJRT memory, which doesn't have persistent backing store. * * 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. */ #define UAO_HASH_PENALTY 4 /* XXX: a guess */ boolean_t uao_flush(uobj, start, stop, flags) struct uvm_object *uobj; vaddr_t start, stop; int flags; { struct uvm_aobj *aobj = (struct uvm_aobj *) uobj; struct vm_page *pp, *ppnext; boolean_t retval, by_list; vaddr_t curoff; UVMHIST_FUNC("uao_flush"); UVMHIST_CALLED(maphist); curoff = 0; /* XXX: shut up gcc */ retval = TRUE; /* default to success */ 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) * UAO_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) { UVMHIST_LOG(maphist, "<- done (no work to do)",0,0,0,0); return (retval); } /* * now do it. note: we must update ppnext in the body of loop or we * will get stuck. we need to use ppnext because we may free "pp" * before doing the next loop. */ if (by_list) { pp = uobj->memq.tqh_first; } else { curoff = start; pp = uvm_pagelookup(uobj, curoff); } ppnext = NULL; /* XXX: shut up gcc */ uvm_lock_pageq(); /* page queues locked */ /* locked: both page queues and uobj */ for ( ; (by_list && pp != NULL) || (!by_list && curoff < stop) ; pp = ppnext) { if (by_list) { ppnext = pp->listq.tqe_next; /* range check */ if (pp->offset < start || pp->offset >= stop) continue; } else { curoff += PAGE_SIZE; if (curoff < stop) ppnext = uvm_pagelookup(uobj, curoff); /* null check */ if (pp == 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 (pp->loan_count != 0 || pp->wire_count != 0) continue; /* zap all mappings for the page. */ pmap_page_protect(PMAP_PGARG(pp), VM_PROT_NONE); /* ...and deactivate the page. */ uvm_pagedeactivate(pp); 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 (pp->loan_count != 0 || pp->wire_count != 0) continue; /* * mark the page as released if its busy. */ if (pp->flags & PG_BUSY) { pp->flags |= PG_RELEASED; continue; } /* zap all mappings for the page. */ pmap_page_protect(PMAP_PGARG(pp), VM_PROT_NONE); uao_dropswap(uobj, pp->offset >> PAGE_SHIFT); uvm_pagefree(pp); continue; default: panic("uao_flush: weird flags"); } #ifdef DIAGNOSTIC panic("uao_flush: unreachable code"); #endif } uvm_unlock_pageq(); UVMHIST_LOG(maphist, "<- done, rv=%d",retval,0,0,0); return (retval); } /* * 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 VM_PAGER_UNLOCK. * * => 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; vaddr_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; vaddr_t current_offset; vm_page_t ptmp; int lcv, gotpages, maxpages, swslot, rv; 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, then * zero-fill it. */ if (ptmp == NULL && uao_find_swslot(aobj, current_offset >> PAGE_SHIFT) == 0) { ptmp = uvm_pagealloc(uobj, current_offset, NULL, 0); if (ptmp) { /* new page */ ptmp->flags &= ~(PG_BUSY|PG_FAKE); ptmp->pqflags |= PQ_AOBJ; UVM_PAGE_OWN(ptmp, NULL); uvm_pagezero(ptmp); } } /* * to be useful must get a non-busy, non-released page */ if (ptmp == NULL || (ptmp->flags & (PG_BUSY|PG_RELEASED)) != 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"); pps[lcv] = ptmp; gotpages++; } /* "for" lcv loop */ /* * 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) /* 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. * 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; /* * 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); /* goto top of pps while loop */ 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|PG_RELEASED)) != 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; /* goto top of pps while loop */ } /* * 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, current_offset >> PAGE_SHIFT); /* * 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); rv = uvm_swap_get(ptmp, swslot, PGO_SYNCIO); simple_lock(&uobj->vmobjlock); /* * I/O done. check for errors. */ if (rv != VM_PAGER_OK) { UVMHIST_LOG(pdhist, "<- done (error=%d)", rv,0,0,0); if (ptmp->flags & PG_WANTED) /* object lock still held */ wakeup(ptmp); ptmp->flags &= ~(PG_WANTED|PG_BUSY); UVM_PAGE_OWN(ptmp, NULL); uvm_lock_pageq(); uvm_pagefree(ptmp); uvm_unlock_pageq(); simple_unlock(&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 */ ptmp->flags &= ~PG_FAKE; /* data is valid ... */ pmap_clear_modify(PMAP_PGARG(ptmp)); /* ... and clean */ pps[lcv] = ptmp; } /* lcv loop */ /* * finally, unlock object and return. */ simple_unlock(&uobj->vmobjlock); UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0); return(VM_PAGER_OK); } /* * uao_releasepg: handle released page in an aobj * * => "pg" is a PG_BUSY [caller owns it], PG_RELEASED page that we need * to dispose of. * => caller must handle PG_WANTED case * => called with page's object locked, pageq's unlocked * => returns TRUE if page's object is still alive, FALSE if we * killed the page's object. if we return TRUE, then we * return with the object locked. * => if (nextpgp != NULL) => we return pageq.tqe_next here, and return * with the page queues locked [for pagedaemon] * => if (nextpgp == NULL) => we return with page queues unlocked [normal case] * => we kill the aobj if it is not referenced and we are suppose to * kill it ("KILLME"). */ static boolean_t uao_releasepg(pg, nextpgp) struct vm_page *pg; struct vm_page **nextpgp; /* OUT */ { struct uvm_aobj *aobj = (struct uvm_aobj *) pg->uobject; #ifdef DIAGNOSTIC if ((pg->flags & PG_RELEASED) == 0) panic("uao_releasepg: page not released!"); #endif /* * dispose of the page [caller handles PG_WANTED] and swap slot. */ pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE); uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT); uvm_lock_pageq(); if (nextpgp) *nextpgp = pg->pageq.tqe_next; /* next page for daemon */ uvm_pagefree(pg); if (!nextpgp) uvm_unlock_pageq(); /* keep locked for daemon */ /* * if we're not killing the object, we're done. */ if ((aobj->u_flags & UAO_FLAG_KILLME) == 0) return TRUE; #ifdef DIAGNOSTIC if (aobj->u_obj.uo_refs) panic("uvm_km_releasepg: kill flag set on referenced object!"); #endif /* * if there are still pages in the object, we're done for now. */ if (aobj->u_obj.uo_npages != 0) return TRUE; #ifdef DIAGNOSTIC if (aobj->u_obj.memq.tqh_first) panic("uvn_releasepg: pages in object with npages == 0"); #endif /* * finally, free the rest. */ uao_free(aobj); return FALSE; } /* * 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); } }