/* $NetBSD: uvm_page.c,v 1.41 2000/09/21 17:46:04 thorpej Exp $ */ /* * Copyright (c) 1997 Charles D. Cranor and Washington University. * Copyright (c) 1991, 1993, The Regents of the University of California. * * All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * 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, * Washington University, the University of California, Berkeley and * its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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. * * @(#)vm_page.c 8.3 (Berkeley) 3/21/94 * from: Id: uvm_page.c,v 1.1.2.18 1998/02/06 05:24:42 chs Exp * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * All rights reserved. * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. */ /* * uvm_page.c: page ops. */ #include #include #include #include #define UVM_PAGE /* pull in uvm_page.h functions */ #include /* * global vars... XXXCDC: move to uvm. structure. */ /* * physical memory config is stored in vm_physmem. */ struct vm_physseg vm_physmem[VM_PHYSSEG_MAX]; /* XXXCDC: uvm.physmem */ int vm_nphysseg = 0; /* XXXCDC: uvm.nphysseg */ /* * Some supported CPUs in a given architecture don't support all * of the things necessary to do idle page zero'ing efficiently. * We therefore provide a way to disable it from machdep code here. */ boolean_t vm_page_zero_enable = TRUE; /* * local variables */ /* * these variables record the values returned by vm_page_bootstrap, * for debugging purposes. The implementation of uvm_pageboot_alloc * and pmap_startup here also uses them internally. */ static vaddr_t virtual_space_start; static vaddr_t virtual_space_end; /* * we use a hash table with only one bucket during bootup. we will * later rehash (resize) the hash table once the allocator is ready. * we static allocate the one bootstrap bucket below... */ static struct pglist uvm_bootbucket; /* * local prototypes */ static void uvm_pageinsert __P((struct vm_page *)); /* * inline functions */ /* * uvm_pageinsert: insert a page in the object and the hash table * * => caller must lock object * => caller must lock page queues * => call should have already set pg's object and offset pointers * and bumped the version counter */ __inline static void uvm_pageinsert(pg) struct vm_page *pg; { struct pglist *buck; int s; #ifdef DIAGNOSTIC if (pg->flags & PG_TABLED) panic("uvm_pageinsert: already inserted"); #endif buck = &uvm.page_hash[uvm_pagehash(pg->uobject,pg->offset)]; s = splimp(); simple_lock(&uvm.hashlock); TAILQ_INSERT_TAIL(buck, pg, hashq); /* put in hash */ simple_unlock(&uvm.hashlock); splx(s); TAILQ_INSERT_TAIL(&pg->uobject->memq, pg, listq); /* put in object */ pg->flags |= PG_TABLED; pg->uobject->uo_npages++; } /* * uvm_page_remove: remove page from object and hash * * => caller must lock object * => caller must lock page queues */ void __inline uvm_pageremove(pg) struct vm_page *pg; { struct pglist *buck; int s; #ifdef DIAGNOSTIC if ((pg->flags & (PG_FAULTING)) != 0) panic("uvm_pageremove: page is faulting"); #endif if ((pg->flags & PG_TABLED) == 0) return; /* XXX: log */ buck = &uvm.page_hash[uvm_pagehash(pg->uobject,pg->offset)]; s = splimp(); simple_lock(&uvm.hashlock); TAILQ_REMOVE(buck, pg, hashq); simple_unlock(&uvm.hashlock); splx(s); /* object should be locked */ TAILQ_REMOVE(&pg->uobject->memq, pg, listq); pg->flags &= ~PG_TABLED; pg->uobject->uo_npages--; pg->uobject = NULL; pg->version++; } /* * uvm_page_init: init the page system. called from uvm_init(). * * => we return the range of kernel virtual memory in kvm_startp/kvm_endp */ void uvm_page_init(kvm_startp, kvm_endp) vaddr_t *kvm_startp, *kvm_endp; { vsize_t freepages, pagecount, n; vm_page_t pagearray; int lcv, i; paddr_t paddr; /* * step 1: init the page queues and page queue locks */ for (lcv = 0; lcv < VM_NFREELIST; lcv++) { for (i = 0; i < PGFL_NQUEUES; i++) TAILQ_INIT(&uvm.page_free[lcv].pgfl_queues[i]); } TAILQ_INIT(&uvm.page_active); TAILQ_INIT(&uvm.page_inactive_swp); TAILQ_INIT(&uvm.page_inactive_obj); simple_lock_init(&uvm.pageqlock); simple_lock_init(&uvm.fpageqlock); /* * step 2: init the => hash table. for now * we just have one bucket (the bootstrap bucket). later on we * will allocate new buckets as we dynamically resize the hash table. */ uvm.page_nhash = 1; /* 1 bucket */ uvm.page_hashmask = 0; /* mask for hash function */ uvm.page_hash = &uvm_bootbucket; /* install bootstrap bucket */ TAILQ_INIT(uvm.page_hash); /* init hash table */ simple_lock_init(&uvm.hashlock); /* init hash table lock */ /* * step 3: allocate vm_page structures. */ /* * sanity check: * before calling this function the MD code is expected to register * some free RAM with the uvm_page_physload() function. our job * now is to allocate vm_page structures for this memory. */ if (vm_nphysseg == 0) panic("vm_page_bootstrap: no memory pre-allocated"); /* * first calculate the number of free pages... * * note that we use start/end rather than avail_start/avail_end. * this allows us to allocate extra vm_page structures in case we * want to return some memory to the pool after booting. */ freepages = 0; for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) freepages += (vm_physmem[lcv].end - vm_physmem[lcv].start); /* * we now know we have (PAGE_SIZE * freepages) bytes of memory we can * use. for each page of memory we use we need a vm_page structure. * thus, the total number of pages we can use is the total size of * the memory divided by the PAGE_SIZE plus the size of the vm_page * structure. we add one to freepages as a fudge factor to avoid * truncation errors (since we can only allocate in terms of whole * pages). */ pagecount = ((freepages + 1) << PAGE_SHIFT) / (PAGE_SIZE + sizeof(struct vm_page)); pagearray = (vm_page_t)uvm_pageboot_alloc(pagecount * sizeof(struct vm_page)); memset(pagearray, 0, pagecount * sizeof(struct vm_page)); /* * step 4: init the vm_page structures and put them in the correct * place... */ for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) { n = vm_physmem[lcv].end - vm_physmem[lcv].start; if (n > pagecount) { printf("uvm_page_init: lost %ld page(s) in init\n", (long)(n - pagecount)); panic("uvm_page_init"); /* XXXCDC: shouldn't happen? */ /* n = pagecount; */ } /* set up page array pointers */ vm_physmem[lcv].pgs = pagearray; pagearray += n; pagecount -= n; vm_physmem[lcv].lastpg = vm_physmem[lcv].pgs + (n - 1); /* init and free vm_pages (we've already zeroed them) */ paddr = ptoa(vm_physmem[lcv].start); for (i = 0 ; i < n ; i++, paddr += PAGE_SIZE) { vm_physmem[lcv].pgs[i].phys_addr = paddr; if (atop(paddr) >= vm_physmem[lcv].avail_start && atop(paddr) <= vm_physmem[lcv].avail_end) { uvmexp.npages++; /* add page to free pool */ uvm_pagefree(&vm_physmem[lcv].pgs[i]); } } } /* * step 5: pass up the values of virtual_space_start and * virtual_space_end (obtained by uvm_pageboot_alloc) to the upper * layers of the VM. */ *kvm_startp = round_page(virtual_space_start); *kvm_endp = trunc_page(virtual_space_end); /* * step 6: init pagedaemon lock */ simple_lock_init(&uvm.pagedaemon_lock); /* * step 7: init reserve thresholds * XXXCDC - values may need adjusting */ uvmexp.reserve_pagedaemon = 1; uvmexp.reserve_kernel = 5; /* * step 8: determine if we should zero pages in the idle * loop. * * XXXJRT - might consider zero'ing up to the target *now*, * but that could take an awfully long time if you * have a lot of memory. */ uvm.page_idle_zero = vm_page_zero_enable; /* * done! */ uvm.page_init_done = TRUE; } /* * uvm_setpagesize: set the page size * * => sets page_shift and page_mask from uvmexp.pagesize. * => XXXCDC: move global vars. */ void uvm_setpagesize() { if (uvmexp.pagesize == 0) uvmexp.pagesize = DEFAULT_PAGE_SIZE; uvmexp.pagemask = uvmexp.pagesize - 1; if ((uvmexp.pagemask & uvmexp.pagesize) != 0) panic("uvm_setpagesize: page size not a power of two"); for (uvmexp.pageshift = 0; ; uvmexp.pageshift++) if ((1 << uvmexp.pageshift) == uvmexp.pagesize) break; } /* * uvm_pageboot_alloc: steal memory from physmem for bootstrapping */ vaddr_t uvm_pageboot_alloc(size) vsize_t size; { #if defined(PMAP_STEAL_MEMORY) vaddr_t addr; /* * defer bootstrap allocation to MD code (it may want to allocate * from a direct-mapped segment). pmap_steal_memory should round * off virtual_space_start/virtual_space_end. */ addr = pmap_steal_memory(size, &virtual_space_start, &virtual_space_end); return(addr); #else /* !PMAP_STEAL_MEMORY */ static boolean_t initialized = FALSE; vaddr_t addr, vaddr; paddr_t paddr; /* round to page size */ size = round_page(size); /* * on first call to this function, initialize ourselves. */ if (initialized == FALSE) { pmap_virtual_space(&virtual_space_start, &virtual_space_end); /* round it the way we like it */ virtual_space_start = round_page(virtual_space_start); virtual_space_end = trunc_page(virtual_space_end); initialized = TRUE; } /* * allocate virtual memory for this request */ if (virtual_space_start == virtual_space_end || (virtual_space_end - virtual_space_start) < size) panic("uvm_pageboot_alloc: out of virtual space"); addr = virtual_space_start; #ifdef PMAP_GROWKERNEL /* * If the kernel pmap can't map the requested space, * then allocate more resources for it. */ if (uvm_maxkaddr < (addr + size)) { uvm_maxkaddr = pmap_growkernel(addr + size); if (uvm_maxkaddr < (addr + size)) panic("uvm_pageboot_alloc: pmap_growkernel() failed"); } #endif virtual_space_start += size; /* * allocate and mapin physical pages to back new virtual pages */ for (vaddr = round_page(addr) ; vaddr < addr + size ; vaddr += PAGE_SIZE) { if (!uvm_page_physget(&paddr)) panic("uvm_pageboot_alloc: out of memory"); /* * Note this memory is no longer managed, so using * pmap_kenter is safe. */ pmap_kenter_pa(vaddr, paddr, VM_PROT_READ|VM_PROT_WRITE); } return(addr); #endif /* PMAP_STEAL_MEMORY */ } #if !defined(PMAP_STEAL_MEMORY) /* * uvm_page_physget: "steal" one page from the vm_physmem structure. * * => attempt to allocate it off the end of a segment in which the "avail" * values match the start/end values. if we can't do that, then we * will advance both values (making them equal, and removing some * vm_page structures from the non-avail area). * => return false if out of memory. */ /* subroutine: try to allocate from memory chunks on the specified freelist */ static boolean_t uvm_page_physget_freelist __P((paddr_t *, int)); static boolean_t uvm_page_physget_freelist(paddrp, freelist) paddr_t *paddrp; int freelist; { int lcv, x; /* pass 1: try allocating from a matching end */ #if (VM_PHYSSEG_STRAT == VM_PSTRAT_BIGFIRST) for (lcv = vm_nphysseg - 1 ; lcv >= 0 ; lcv--) #else for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) #endif { if (uvm.page_init_done == TRUE) panic("vm_page_physget: called _after_ bootstrap"); if (vm_physmem[lcv].free_list != freelist) continue; /* try from front */ if (vm_physmem[lcv].avail_start == vm_physmem[lcv].start && vm_physmem[lcv].avail_start < vm_physmem[lcv].avail_end) { *paddrp = ptoa(vm_physmem[lcv].avail_start); vm_physmem[lcv].avail_start++; vm_physmem[lcv].start++; /* nothing left? nuke it */ if (vm_physmem[lcv].avail_start == vm_physmem[lcv].end) { if (vm_nphysseg == 1) panic("vm_page_physget: out of memory!"); vm_nphysseg--; for (x = lcv ; x < vm_nphysseg ; x++) /* structure copy */ vm_physmem[x] = vm_physmem[x+1]; } return (TRUE); } /* try from rear */ if (vm_physmem[lcv].avail_end == vm_physmem[lcv].end && vm_physmem[lcv].avail_start < vm_physmem[lcv].avail_end) { *paddrp = ptoa(vm_physmem[lcv].avail_end - 1); vm_physmem[lcv].avail_end--; vm_physmem[lcv].end--; /* nothing left? nuke it */ if (vm_physmem[lcv].avail_end == vm_physmem[lcv].start) { if (vm_nphysseg == 1) panic("vm_page_physget: out of memory!"); vm_nphysseg--; for (x = lcv ; x < vm_nphysseg ; x++) /* structure copy */ vm_physmem[x] = vm_physmem[x+1]; } return (TRUE); } } /* pass2: forget about matching ends, just allocate something */ #if (VM_PHYSSEG_STRAT == VM_PSTRAT_BIGFIRST) for (lcv = vm_nphysseg - 1 ; lcv >= 0 ; lcv--) #else for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) #endif { /* any room in this bank? */ if (vm_physmem[lcv].avail_start >= vm_physmem[lcv].avail_end) continue; /* nope */ *paddrp = ptoa(vm_physmem[lcv].avail_start); vm_physmem[lcv].avail_start++; /* truncate! */ vm_physmem[lcv].start = vm_physmem[lcv].avail_start; /* nothing left? nuke it */ if (vm_physmem[lcv].avail_start == vm_physmem[lcv].end) { if (vm_nphysseg == 1) panic("vm_page_physget: out of memory!"); vm_nphysseg--; for (x = lcv ; x < vm_nphysseg ; x++) /* structure copy */ vm_physmem[x] = vm_physmem[x+1]; } return (TRUE); } return (FALSE); /* whoops! */ } boolean_t uvm_page_physget(paddrp) paddr_t *paddrp; { int i; /* try in the order of freelist preference */ for (i = 0; i < VM_NFREELIST; i++) if (uvm_page_physget_freelist(paddrp, i) == TRUE) return (TRUE); return (FALSE); } #endif /* PMAP_STEAL_MEMORY */ /* * uvm_page_physload: load physical memory into VM system * * => all args are PFs * => all pages in start/end get vm_page structures * => areas marked by avail_start/avail_end get added to the free page pool * => we are limited to VM_PHYSSEG_MAX physical memory segments */ void uvm_page_physload(start, end, avail_start, avail_end, free_list) paddr_t start, end, avail_start, avail_end; int free_list; { int preload, lcv; psize_t npages; struct vm_page *pgs; struct vm_physseg *ps; if (uvmexp.pagesize == 0) panic("vm_page_physload: page size not set!"); if (free_list >= VM_NFREELIST || free_list < VM_FREELIST_DEFAULT) panic("uvm_page_physload: bad free list %d\n", free_list); if (start >= end) panic("uvm_page_physload: start >= end"); /* * do we have room? */ if (vm_nphysseg == VM_PHYSSEG_MAX) { printf("vm_page_physload: unable to load physical memory " "segment\n"); printf("\t%d segments allocated, ignoring 0x%llx -> 0x%llx\n", VM_PHYSSEG_MAX, (long long)start, (long long)end); return; } /* * check to see if this is a "preload" (i.e. uvm_mem_init hasn't been * called yet, so malloc is not available). */ for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) { if (vm_physmem[lcv].pgs) break; } preload = (lcv == vm_nphysseg); /* * if VM is already running, attempt to malloc() vm_page structures */ if (!preload) { #if defined(VM_PHYSSEG_NOADD) panic("vm_page_physload: tried to add RAM after vm_mem_init"); #else /* XXXCDC: need some sort of lockout for this case */ paddr_t paddr; npages = end - start; /* # of pages */ pgs = malloc(sizeof(struct vm_page) * npages, M_VMPAGE, M_NOWAIT); if (pgs == NULL) { printf("vm_page_physload: can not malloc vm_page " "structs for segment\n"); printf("\tignoring 0x%lx -> 0x%lx\n", start, end); return; } /* zero data, init phys_addr and free_list, and free pages */ memset(pgs, 0, sizeof(struct vm_page) * npages); for (lcv = 0, paddr = ptoa(start) ; lcv < npages ; lcv++, paddr += PAGE_SIZE) { pgs[lcv].phys_addr = paddr; pgs[lcv].free_list = free_list; if (atop(paddr) >= avail_start && atop(paddr) <= avail_end) uvm_pagefree(&pgs[lcv]); } /* XXXCDC: incomplete: need to update uvmexp.free, what else? */ /* XXXCDC: need hook to tell pmap to rebuild pv_list, etc... */ #endif } else { /* gcc complains if these don't get init'd */ pgs = NULL; npages = 0; } /* * now insert us in the proper place in vm_physmem[] */ #if (VM_PHYSSEG_STRAT == VM_PSTRAT_RANDOM) /* random: put it at the end (easy!) */ ps = &vm_physmem[vm_nphysseg]; #elif (VM_PHYSSEG_STRAT == VM_PSTRAT_BSEARCH) { int x; /* sort by address for binary search */ for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) if (start < vm_physmem[lcv].start) break; ps = &vm_physmem[lcv]; /* move back other entries, if necessary ... */ for (x = vm_nphysseg ; x > lcv ; x--) /* structure copy */ vm_physmem[x] = vm_physmem[x - 1]; } #elif (VM_PHYSSEG_STRAT == VM_PSTRAT_BIGFIRST) { int x; /* sort by largest segment first */ for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) if ((end - start) > (vm_physmem[lcv].end - vm_physmem[lcv].start)) break; ps = &vm_physmem[lcv]; /* move back other entries, if necessary ... */ for (x = vm_nphysseg ; x > lcv ; x--) /* structure copy */ vm_physmem[x] = vm_physmem[x - 1]; } #else panic("vm_page_physload: unknown physseg strategy selected!"); #endif ps->start = start; ps->end = end; ps->avail_start = avail_start; ps->avail_end = avail_end; if (preload) { ps->pgs = NULL; } else { ps->pgs = pgs; ps->lastpg = pgs + npages - 1; } ps->free_list = free_list; vm_nphysseg++; /* * done! */ if (!preload) uvm_page_rehash(); return; } /* * uvm_page_rehash: reallocate hash table based on number of free pages. */ void uvm_page_rehash() { int freepages, lcv, bucketcount, s, oldcount; struct pglist *newbuckets, *oldbuckets; struct vm_page *pg; size_t newsize, oldsize; /* * compute number of pages that can go in the free pool */ freepages = 0; for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) freepages += (vm_physmem[lcv].avail_end - vm_physmem[lcv].avail_start); /* * compute number of buckets needed for this number of pages */ bucketcount = 1; while (bucketcount < freepages) bucketcount = bucketcount * 2; /* * compute the size of the current table and new table. */ oldbuckets = uvm.page_hash; oldcount = uvm.page_nhash; oldsize = round_page(sizeof(struct pglist) * oldcount); newsize = round_page(sizeof(struct pglist) * bucketcount); /* * allocate the new buckets */ newbuckets = (struct pglist *) uvm_km_alloc(kernel_map, newsize); if (newbuckets == NULL) { printf("uvm_page_physrehash: WARNING: could not grow page " "hash table\n"); return; } for (lcv = 0 ; lcv < bucketcount ; lcv++) TAILQ_INIT(&newbuckets[lcv]); /* * now replace the old buckets with the new ones and rehash everything */ s = splimp(); simple_lock(&uvm.hashlock); uvm.page_hash = newbuckets; uvm.page_nhash = bucketcount; uvm.page_hashmask = bucketcount - 1; /* power of 2 */ /* ... and rehash */ for (lcv = 0 ; lcv < oldcount ; lcv++) { while ((pg = oldbuckets[lcv].tqh_first) != NULL) { TAILQ_REMOVE(&oldbuckets[lcv], pg, hashq); TAILQ_INSERT_TAIL( &uvm.page_hash[uvm_pagehash(pg->uobject, pg->offset)], pg, hashq); } } simple_unlock(&uvm.hashlock); splx(s); /* * free old bucket array if is not the boot-time table */ if (oldbuckets != &uvm_bootbucket) uvm_km_free(kernel_map, (vaddr_t) oldbuckets, oldsize); /* * done */ return; } #if 1 /* XXXCDC: TMP TMP TMP DEBUG DEBUG DEBUG */ void uvm_page_physdump __P((void)); /* SHUT UP GCC */ /* call from DDB */ void uvm_page_physdump() { int lcv; printf("rehash: physical memory config [segs=%d of %d]:\n", vm_nphysseg, VM_PHYSSEG_MAX); for (lcv = 0 ; lcv < vm_nphysseg ; lcv++) printf("0x%llx->0x%llx [0x%llx->0x%llx]\n", (long long)vm_physmem[lcv].start, (long long)vm_physmem[lcv].end, (long long)vm_physmem[lcv].avail_start, (long long)vm_physmem[lcv].avail_end); printf("STRATEGY = "); switch (VM_PHYSSEG_STRAT) { case VM_PSTRAT_RANDOM: printf("RANDOM\n"); break; case VM_PSTRAT_BSEARCH: printf("BSEARCH\n"); break; case VM_PSTRAT_BIGFIRST: printf("BIGFIRST\n"); break; default: printf("<>!!!!\n"); } printf("number of buckets = %d\n", uvm.page_nhash); } #endif /* * uvm_pagealloc_strat: allocate vm_page from a particular free list. * * => return null if no pages free * => wake up pagedaemon if number of free pages drops below low water mark * => if obj != NULL, obj must be locked (to put in hash) * => if anon != NULL, anon must be locked (to put in anon) * => only one of obj or anon can be non-null * => caller must activate/deactivate page if it is not wired. * => free_list is ignored if strat == UVM_PGA_STRAT_NORMAL. * => policy decision: it is more important to pull a page off of the * appropriate priority free list than it is to get a zero'd or * unknown contents page. This is because we live with the * consequences of a bad free list decision for the entire * lifetime of the page, e.g. if the page comes from memory that * is slower to access. */ struct vm_page * uvm_pagealloc_strat(obj, off, anon, flags, strat, free_list) struct uvm_object *obj; voff_t off; int flags; struct vm_anon *anon; int strat, free_list; { int lcv, try1, try2, s, zeroit = 0; struct vm_page *pg; struct pglist *freeq; struct pgfreelist *pgfl; boolean_t use_reserve; #ifdef DIAGNOSTIC /* sanity check */ if (obj && anon) panic("uvm_pagealloc: obj and anon != NULL"); #endif s = uvm_lock_fpageq(); /* lock free page queue */ /* * check to see if we need to generate some free pages waking * the pagedaemon. */ if (uvmexp.free < uvmexp.freemin || (uvmexp.free < uvmexp.freetarg && uvmexp.inactive < uvmexp.inactarg)) wakeup(&uvm.pagedaemon); /* * fail if any of these conditions is true: * [1] there really are no free pages, or * [2] only kernel "reserved" pages remain and * the page isn't being allocated to a kernel object. * [3] only pagedaemon "reserved" pages remain and * the requestor isn't the pagedaemon. */ use_reserve = (flags & UVM_PGA_USERESERVE) || (obj && UVM_OBJ_IS_KERN_OBJECT(obj)); if ((uvmexp.free <= uvmexp.reserve_kernel && !use_reserve) || (uvmexp.free <= uvmexp.reserve_pagedaemon && !(use_reserve && curproc == uvm.pagedaemon_proc))) goto fail; #if PGFL_NQUEUES != 2 #error uvm_pagealloc_strat needs to be updated #endif /* * If we want a zero'd page, try the ZEROS queue first, otherwise * we try the UNKNOWN queue first. */ if (flags & UVM_PGA_ZERO) { try1 = PGFL_ZEROS; try2 = PGFL_UNKNOWN; } else { try1 = PGFL_UNKNOWN; try2 = PGFL_ZEROS; } again: switch (strat) { case UVM_PGA_STRAT_NORMAL: /* Check all freelists in descending priority order. */ for (lcv = 0; lcv < VM_NFREELIST; lcv++) { pgfl = &uvm.page_free[lcv]; if ((pg = TAILQ_FIRST((freeq = &pgfl->pgfl_queues[try1]))) != NULL || (pg = TAILQ_FIRST((freeq = &pgfl->pgfl_queues[try2]))) != NULL) goto gotit; } /* No pages free! */ goto fail; case UVM_PGA_STRAT_ONLY: case UVM_PGA_STRAT_FALLBACK: /* Attempt to allocate from the specified free list. */ #ifdef DIAGNOSTIC if (free_list >= VM_NFREELIST || free_list < 0) panic("uvm_pagealloc_strat: bad free list %d", free_list); #endif pgfl = &uvm.page_free[free_list]; if ((pg = TAILQ_FIRST((freeq = &pgfl->pgfl_queues[try1]))) != NULL || (pg = TAILQ_FIRST((freeq = &pgfl->pgfl_queues[try2]))) != NULL) goto gotit; /* Fall back, if possible. */ if (strat == UVM_PGA_STRAT_FALLBACK) { strat = UVM_PGA_STRAT_NORMAL; goto again; } /* No pages free! */ goto fail; default: panic("uvm_pagealloc_strat: bad strat %d", strat); /* NOTREACHED */ } gotit: TAILQ_REMOVE(freeq, pg, pageq); uvmexp.free--; /* update zero'd page count */ if (pg->flags & PG_ZERO) uvmexp.zeropages--; /* * update allocation statistics and remember if we have to * zero the page */ if (flags & UVM_PGA_ZERO) { if (pg->flags & PG_ZERO) { uvmexp.pga_zerohit++; zeroit = 0; } else { uvmexp.pga_zeromiss++; zeroit = 1; } } uvm_unlock_fpageq(s); /* unlock free page queue */ pg->offset = off; pg->uobject = obj; pg->uanon = anon; pg->flags = PG_BUSY|PG_CLEAN|PG_FAKE; pg->version++; pg->wire_count = 0; pg->loan_count = 0; if (anon) { anon->u.an_page = pg; pg->pqflags = PQ_ANON; } else { if (obj) uvm_pageinsert(pg); pg->pqflags = 0; } #if defined(UVM_PAGE_TRKOWN) pg->owner_tag = NULL; #endif UVM_PAGE_OWN(pg, "new alloc"); if (flags & UVM_PGA_ZERO) { /* * A zero'd page is not clean. If we got a page not already * zero'd, then we have to zero it ourselves. */ pg->flags &= ~PG_CLEAN; if (zeroit) pmap_zero_page(VM_PAGE_TO_PHYS(pg)); } return(pg); fail: uvm_unlock_fpageq(s); return (NULL); } /* * uvm_pagerealloc: reallocate a page from one object to another * * => both objects must be locked */ void uvm_pagerealloc(pg, newobj, newoff) struct vm_page *pg; struct uvm_object *newobj; voff_t newoff; { /* * remove it from the old object */ if (pg->uobject) { uvm_pageremove(pg); } /* * put it in the new object */ if (newobj) { pg->uobject = newobj; pg->offset = newoff; pg->version++; uvm_pageinsert(pg); } return; } /* * uvm_pagefree: free page * * => erase page's identity (i.e. remove from hash/object) * => put page on free list * => caller must lock owning object (either anon or uvm_object) * => caller must lock page queues * => assumes all valid mappings of pg are gone */ void uvm_pagefree(pg) struct vm_page *pg; { int s; int saved_loan_count = pg->loan_count; /* * if the page was an object page (and thus "TABLED"), remove it * from the object. */ if (pg->flags & PG_TABLED) { /* * if the object page is on loan we are going to drop ownership. * it is possible that an anon will take over as owner for this * page later on. the anon will want a !PG_CLEAN page so that * it knows it needs to allocate swap if it wants to page the * page out. */ if (saved_loan_count) pg->flags &= ~PG_CLEAN; /* in case an anon takes over */ uvm_pageremove(pg); /* * if our page was on loan, then we just lost control over it * (in fact, if it was loaned to an anon, the anon may have * already taken over ownership of the page by now and thus * changed the loan_count [e.g. in uvmfault_anonget()]) we just * return (when the last loan is dropped, then the page can be * freed by whatever was holding the last loan). */ if (saved_loan_count) return; } else if (saved_loan_count && (pg->pqflags & PQ_ANON)) { /* * if our page is owned by an anon and is loaned out to the * kernel then we just want to drop ownership and return. * the kernel must free the page when all its loans clear ... * note that the kernel can't change the loan status of our * page as long as we are holding PQ lock. */ pg->pqflags &= ~PQ_ANON; pg->uanon = NULL; return; } #ifdef DIAGNOSTIC if (saved_loan_count) { printf("uvm_pagefree: warning: freeing page with a loan " "count of %d\n", saved_loan_count); panic("uvm_pagefree: loan count"); } #endif /* * now remove the page from the queues */ if (pg->pqflags & PQ_ACTIVE) { TAILQ_REMOVE(&uvm.page_active, pg, pageq); pg->pqflags &= ~PQ_ACTIVE; uvmexp.active--; } if (pg->pqflags & PQ_INACTIVE) { if (pg->pqflags & PQ_SWAPBACKED) TAILQ_REMOVE(&uvm.page_inactive_swp, pg, pageq); else TAILQ_REMOVE(&uvm.page_inactive_obj, pg, pageq); pg->pqflags &= ~PQ_INACTIVE; uvmexp.inactive--; } /* * if the page was wired, unwire it now. */ if (pg->wire_count) { pg->wire_count = 0; uvmexp.wired--; } /* * and put on free queue */ pg->flags &= ~PG_ZERO; s = uvm_lock_fpageq(); TAILQ_INSERT_TAIL(&uvm.page_free[ uvm_page_lookup_freelist(pg)].pgfl_queues[PGFL_UNKNOWN], pg, pageq); pg->pqflags = PQ_FREE; #ifdef DEBUG pg->uobject = (void *)0xdeadbeef; pg->offset = 0xdeadbeef; pg->uanon = (void *)0xdeadbeef; #endif uvmexp.free++; if (uvmexp.zeropages < UVM_PAGEZERO_TARGET) uvm.page_idle_zero = vm_page_zero_enable; uvm_unlock_fpageq(s); } #if defined(UVM_PAGE_TRKOWN) /* * uvm_page_own: set or release page ownership * * => this is a debugging function that keeps track of who sets PG_BUSY * and where they do it. it can be used to track down problems * such a process setting "PG_BUSY" and never releasing it. * => page's object [if any] must be locked * => if "tag" is NULL then we are releasing page ownership */ void uvm_page_own(pg, tag) struct vm_page *pg; char *tag; { /* gain ownership? */ if (tag) { if (pg->owner_tag) { printf("uvm_page_own: page %p already owned " "by proc %d [%s]\n", pg, pg->owner, pg->owner_tag); panic("uvm_page_own"); } pg->owner = (curproc) ? curproc->p_pid : (pid_t) -1; pg->owner_tag = tag; return; } /* drop ownership */ if (pg->owner_tag == NULL) { printf("uvm_page_own: dropping ownership of an non-owned " "page (%p)\n", pg); panic("uvm_page_own"); } pg->owner_tag = NULL; return; } #endif /* * uvm_pageidlezero: zero free pages while the system is idle. * * => we do at least one iteration per call, if we are below the target. * => we loop until we either reach the target or whichqs indicates that * there is a process ready to run. */ void uvm_pageidlezero() { struct vm_page *pg; struct pgfreelist *pgfl; int free_list, s; do { s = uvm_lock_fpageq(); if (uvmexp.zeropages >= UVM_PAGEZERO_TARGET) { uvm.page_idle_zero = FALSE; uvm_unlock_fpageq(s); return; } for (free_list = 0; free_list < VM_NFREELIST; free_list++) { pgfl = &uvm.page_free[free_list]; if ((pg = TAILQ_FIRST(&pgfl->pgfl_queues[ PGFL_UNKNOWN])) != NULL) break; } if (pg == NULL) { /* * No non-zero'd pages; don't bother trying again * until we know we have non-zero'd pages free. */ uvm.page_idle_zero = FALSE; uvm_unlock_fpageq(s); return; } TAILQ_REMOVE(&pgfl->pgfl_queues[PGFL_UNKNOWN], pg, pageq); uvmexp.free--; uvm_unlock_fpageq(s); #ifdef PMAP_PAGEIDLEZERO if (PMAP_PAGEIDLEZERO(VM_PAGE_TO_PHYS(pg)) == FALSE) { /* * The machine-dependent code detected some * reason for us to abort zeroing pages, * probably because there is a process now * ready to run. */ s = uvm_lock_fpageq(); TAILQ_INSERT_HEAD(&pgfl->pgfl_queues[PGFL_UNKNOWN], pg, pageq); uvmexp.free++; uvmexp.zeroaborts++; uvm_unlock_fpageq(s); return; } #else /* * XXX This will toast the cache unless the pmap_zero_page() * XXX implementation does uncached access. */ pmap_zero_page(VM_PAGE_TO_PHYS(pg)); #endif pg->flags |= PG_ZERO; s = uvm_lock_fpageq(); TAILQ_INSERT_HEAD(&pgfl->pgfl_queues[PGFL_ZEROS], pg, pageq); uvmexp.free++; uvmexp.zeropages++; uvm_unlock_fpageq(s); } while (sched_whichqs == 0); }