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IABSD.fr/src/sys/uvm/uvm_aobj.c
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- sys/uvm/uvm_aobj.c
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/* $OpenBSD: uvm_aobj.c,v 1.103 2021/12/29 20:22:06 mpi 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 int uao_find_swslot(struct uvm_object *, int); 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 */ inline static 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) { atomic_setbits_int(&pg->pg_flags, PG_WANTED); rwsleep_nsec(pg, uobj->vmobjlock, PVM, "uao_det", INFSLP); 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) { atomic_setbits_int(&pg->pg_flags, PG_WANTED); rwsleep_nsec(pg, uobj->vmobjlock, PVM, "uaoflsh", INFSLP); 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) { atomic_setbits_int(&ptmp->pg_flags, PG_WANTED); rwsleep_nsec(ptmp, uobj->vmobjlock, PVM, "uao_get", INFSLP); 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, slot, 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. */ slot = uao_set_swslot(&aobj->u_obj, pageidx, 0); uvm_swap_free(slot, 1); 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); } }