From cf5b1e7afe8c69083dc31bb4efd65380d8224e21 Mon Sep 17 00:00:00 2001 From: "William F. Jolitz" Date: Tue, 21 Jan 1992 21:58:35 -0800 Subject: [PATCH] 386BSD 0.1 development Work on file usr/src/sys.386bsd/vm/vm_fault.c Co-Authored-By: Lynne Greer Jolitz Synthesized-from: 386BSD-0.1 --- usr/src/sys.386bsd/vm/vm_fault.c | 1072 ++++++++++++++++++++++++++++++ 1 file changed, 1072 insertions(+) create mode 100644 usr/src/sys.386bsd/vm/vm_fault.c diff --git a/usr/src/sys.386bsd/vm/vm_fault.c b/usr/src/sys.386bsd/vm/vm_fault.c new file mode 100644 index 0000000000..9939347684 --- /dev/null +++ b/usr/src/sys.386bsd/vm/vm_fault.c @@ -0,0 +1,1072 @@ +/* + * Copyright (c) 1991 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 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_fault.c 7.6 (Berkeley) 5/7/91 + * + * + * Copyright (c) 1987, 1990 Carnegie-Mellon University. + * All rights reserved. + * + * Authors: Avadis Tevanian, Jr., Michael Wayne Young + * + * 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. + */ + +static char rcsid[] = "$Header: /usr/bill/working/sys/vm/RCS/vm_fault.c,v 1.2 92/01/21 21:58:17 william Exp $"; + +/* + * Page fault handling module. + */ + +#include "param.h" + +#include "vm.h" +#include "vm_page.h" +#include "vm_pageout.h" + +/* + * vm_fault: + * + * Handle a page fault occuring at the given address, + * requiring the given permissions, in the map specified. + * If successful, the page is inserted into the + * associated physical map. + * + * NOTE: the given address should be truncated to the + * proper page address. + * + * KERN_SUCCESS is returned if the page fault is handled; otherwise, + * a standard error specifying why the fault is fatal is returned. + * + * + * The map in question must be referenced, and remains so. + * Caller may hold no locks. + */ +vm_fault(map, vaddr, fault_type, change_wiring) + vm_map_t map; + vm_offset_t vaddr; + vm_prot_t fault_type; + boolean_t change_wiring; +{ + vm_object_t first_object; + vm_offset_t first_offset; + vm_map_entry_t entry; + register vm_object_t object; + register vm_offset_t offset; + register vm_page_t m; + vm_page_t first_m; + vm_prot_t prot; + int result; + boolean_t wired; + boolean_t su; + boolean_t lookup_still_valid; + boolean_t page_exists; + vm_page_t old_m; + vm_object_t next_object; + + vm_stat.faults++; /* needs lock XXX */ +/* + * Recovery actions + */ +#define FREE_PAGE(m) { \ + PAGE_WAKEUP(m); \ + vm_page_lock_queues(); \ + vm_page_free(m); \ + vm_page_unlock_queues(); \ +} + +#define RELEASE_PAGE(m) { \ + PAGE_WAKEUP(m); \ + vm_page_lock_queues(); \ + vm_page_activate(m); \ + vm_page_unlock_queues(); \ +} + +#define UNLOCK_MAP { \ + if (lookup_still_valid) { \ + vm_map_lookup_done(map, entry); \ + lookup_still_valid = FALSE; \ + } \ +} + +#define UNLOCK_THINGS { \ + object->paging_in_progress--; \ + vm_object_unlock(object); \ + if (object != first_object) { \ + vm_object_lock(first_object); \ + FREE_PAGE(first_m); \ + first_object->paging_in_progress--; \ + vm_object_unlock(first_object); \ + } \ + UNLOCK_MAP; \ +} + +#define UNLOCK_AND_DEALLOCATE { \ + UNLOCK_THINGS; \ + vm_object_deallocate(first_object); \ +} + + RetryFault: ; + + /* + * Find the backing store object and offset into + * it to begin the search. + */ + + if ((result = vm_map_lookup(&map, vaddr, fault_type, &entry, + &first_object, &first_offset, + &prot, &wired, &su)) != KERN_SUCCESS) { + return(result); + } + lookup_still_valid = TRUE; + + if (wired) + fault_type = prot; + + first_m = NULL; + + /* + * Make a reference to this object to + * prevent its disposal while we are messing with + * it. Once we have the reference, the map is free + * to be diddled. Since objects reference their + * shadows (and copies), they will stay around as well. + */ + + vm_object_lock(first_object); + + first_object->ref_count++; + first_object->paging_in_progress++; + + /* + * INVARIANTS (through entire routine): + * + * 1) At all times, we must either have the object + * lock or a busy page in some object to prevent + * some other thread from trying to bring in + * the same page. + * + * Note that we cannot hold any locks during the + * pager access or when waiting for memory, so + * we use a busy page then. + * + * Note also that we aren't as concerned about + * more than one thead attempting to pager_data_unlock + * the same page at once, so we don't hold the page + * as busy then, but do record the highest unlock + * value so far. [Unlock requests may also be delivered + * out of order.] + * + * 2) Once we have a busy page, we must remove it from + * the pageout queues, so that the pageout daemon + * will not grab it away. + * + * 3) To prevent another thread from racing us down the + * shadow chain and entering a new page in the top + * object before we do, we must keep a busy page in + * the top object while following the shadow chain. + * + * 4) We must increment paging_in_progress on any object + * for which we have a busy page, to prevent + * vm_object_collapse from removing the busy page + * without our noticing. + */ + + /* + * Search for the page at object/offset. + */ + + object = first_object; + offset = first_offset; + + /* + * See whether this page is resident + */ + + while (TRUE) { + m = vm_page_lookup(object, offset); + if (m != NULL) { + /* + * If the page is being brought in, + * wait for it and then retry. + */ + if (m->busy) { +#ifdef DOTHREADS + int wait_result; + + PAGE_ASSERT_WAIT(m, !change_wiring); + UNLOCK_THINGS; + thread_block(); + wait_result = current_thread()->wait_result; + vm_object_deallocate(first_object); + if (wait_result != THREAD_AWAKENED) + return(KERN_SUCCESS); + goto RetryFault; +#else + PAGE_ASSERT_WAIT(m, !change_wiring); + UNLOCK_THINGS; +thread_wakeup(&vm_pages_needed); /* XXX! */ + thread_block(); + vm_object_deallocate(first_object); + goto RetryFault; +#endif + } + + if (m->absent) + panic("vm_fault: absent"); + + /* + * If the desired access to this page has + * been locked out, request that it be unlocked. + */ + + if (fault_type & m->page_lock) { +#ifdef DOTHREADS + int wait_result; + + if ((fault_type & m->unlock_request) != fault_type) + panic("vm_fault: pager_data_unlock"); + + PAGE_ASSERT_WAIT(m, !change_wiring); + UNLOCK_THINGS; + thread_block(); + wait_result = current_thread()->wait_result; + vm_object_deallocate(first_object); + if (wait_result != THREAD_AWAKENED) + return(KERN_SUCCESS); + goto RetryFault; +#else + if ((fault_type & m->unlock_request) != fault_type) + panic("vm_fault: pager_data_unlock"); + + PAGE_ASSERT_WAIT(m, !change_wiring); + UNLOCK_THINGS; +thread_wakeup(&vm_pages_needed); /* XXX */ + thread_block(); + vm_object_deallocate(first_object); + goto RetryFault; +#endif + } + + /* + * Remove the page from the pageout daemon's + * reach while we play with it. + */ + + vm_page_lock_queues(); + if (m->inactive) { + queue_remove(&vm_page_queue_inactive, m, + vm_page_t, pageq); + m->inactive = FALSE; + vm_page_inactive_count--; + vm_stat.reactivations++; + } + + if (m->active) { + queue_remove(&vm_page_queue_active, m, + vm_page_t, pageq); + m->active = FALSE; + vm_page_active_count--; + } + vm_page_unlock_queues(); + + /* + * Mark page busy for other threads. + */ + m->busy = TRUE; + m->absent = FALSE; + break; + } + + if (((object->pager != NULL) && + (!change_wiring || wired)) + || (object == first_object)) { + + /* + * Allocate a new page for this object/offset + * pair. + */ + + m = vm_page_alloc(object, offset); + + if (m == NULL) { + UNLOCK_AND_DEALLOCATE; + VM_WAIT; + goto RetryFault; + } + } + + if ((object->pager != NULL) && + (!change_wiring || wired)) { + int rv; + + /* + * Now that we have a busy page, we can + * release the object lock. + */ + vm_object_unlock(object); + + /* + * Call the pager to retrieve the data, if any, + * after releasing the lock on the map. + */ + UNLOCK_MAP; + + rv = vm_pager_get(object->pager, m, TRUE); + if (rv == VM_PAGER_OK) { + /* + * Found the page. + * Leave it busy while we play with it. + */ + vm_object_lock(object); + + /* + * Relookup in case pager changed page. + * Pager is responsible for disposition + * of old page if moved. + */ + m = vm_page_lookup(object, offset); + + vm_stat.pageins++; + m->fake = FALSE; + pmap_clear_modify(VM_PAGE_TO_PHYS(m)); + break; + } + + /* + * Remove the bogus page (which does not + * exist at this object/offset); before + * doing so, we must get back our object + * lock to preserve our invariant. + * + * Also wake up any other thread that may want + * to bring in this page. + * + * If this is the top-level object, we must + * leave the busy page to prevent another + * thread from rushing past us, and inserting + * the page in that object at the same time + * that we are. + */ + + vm_object_lock(object); + /* + * Data outside the range of the pager; an error + */ + if (rv == VM_PAGER_BAD) { + FREE_PAGE(m); + UNLOCK_AND_DEALLOCATE; + return(KERN_PROTECTION_FAILURE); /* XXX */ + } + if (object != first_object) { + FREE_PAGE(m); + /* + * XXX - we cannot just fall out at this + * point, m has been freed and is invalid! + */ + } + } + + /* + * We get here if the object has no pager (or unwiring) + * or the pager doesn't have the page. + */ + if (object == first_object) + first_m = m; + + /* + * Move on to the next object. Lock the next + * object before unlocking the current one. + */ + + offset += object->shadow_offset; + next_object = object->shadow; + if (next_object == NULL) { + /* + * If there's no object left, fill the page + * in the top object with zeros. + */ + if (object != first_object) { + object->paging_in_progress--; + vm_object_unlock(object); + + object = first_object; + offset = first_offset; + m = first_m; + vm_object_lock(object); + } + first_m = NULL; + + vm_page_zero_fill(m); + vm_stat.zero_fill_count++; + m->fake = FALSE; + m->absent = FALSE; + break; + } + else { + vm_object_lock(next_object); + if (object != first_object) + object->paging_in_progress--; + vm_object_unlock(object); + object = next_object; + object->paging_in_progress++; + } + } + + if (m->absent || m->active || m->inactive || !m->busy) + panic("vm_fault: absent or active or inactive or not busy after main loop"); + + /* + * PAGE HAS BEEN FOUND. + * [Loop invariant still holds -- the object lock + * is held.] + */ + + old_m = m; /* save page that would be copied */ + + /* + * If the page is being written, but isn't + * already owned by the top-level object, + * we have to copy it into a new page owned + * by the top-level object. + */ + + if (object != first_object) { + /* + * We only really need to copy if we + * want to write it. + */ + + if (fault_type & VM_PROT_WRITE) { + + /* + * If we try to collapse first_object at this + * point, we may deadlock when we try to get + * the lock on an intermediate object (since we + * have the bottom object locked). We can't + * unlock the bottom object, because the page + * we found may move (by collapse) if we do. + * + * Instead, we first copy the page. Then, when + * we have no more use for the bottom object, + * we unlock it and try to collapse. + * + * Note that we copy the page even if we didn't + * need to... that's the breaks. + */ + + /* + * We already have an empty page in + * first_object - use it. + */ + + vm_page_copy(m, first_m); + first_m->fake = FALSE; + first_m->absent = FALSE; + + /* + * If another map is truly sharing this + * page with us, we have to flush all + * uses of the original page, since we + * can't distinguish those which want the + * original from those which need the + * new copy. + * + * XXX If we know that only one map has + * access to this page, then we could + * avoid the pmap_page_protect() call. + */ + + vm_page_lock_queues(); + vm_page_deactivate(m); + pmap_page_protect(VM_PAGE_TO_PHYS(m), VM_PROT_NONE); + vm_page_unlock_queues(); + + /* + * We no longer need the old page or object. + */ + PAGE_WAKEUP(m); + object->paging_in_progress--; + vm_object_unlock(object); + + /* + * Only use the new page below... + */ + + vm_stat.cow_faults++; + m = first_m; + object = first_object; + offset = first_offset; + + /* + * Now that we've gotten the copy out of the + * way, let's try to collapse the top object. + */ + vm_object_lock(object); + /* + * But we have to play ugly games with + * paging_in_progress to do that... + */ + object->paging_in_progress--; + vm_object_collapse(object); + object->paging_in_progress++; + } + else { + prot &= (~VM_PROT_WRITE); + m->copy_on_write = TRUE; + } + } + + if (m->active || m->inactive) + panic("vm_fault: active or inactive before copy object handling"); + + /* + * If the page is being written, but hasn't been + * copied to the copy-object, we have to copy it there. + */ + RetryCopy: + if (first_object->copy != NULL) { + vm_object_t copy_object = first_object->copy; + vm_offset_t copy_offset; + vm_page_t copy_m; + + /* + * We only need to copy if we want to write it. + */ + if ((fault_type & VM_PROT_WRITE) == 0) { + prot &= ~VM_PROT_WRITE; + m->copy_on_write = TRUE; + } + else { + /* + * Try to get the lock on the copy_object. + */ + if (!vm_object_lock_try(copy_object)) { + vm_object_unlock(object); + /* should spin a bit here... */ + vm_object_lock(object); + goto RetryCopy; + } + + /* + * Make another reference to the copy-object, + * to keep it from disappearing during the + * copy. + */ + copy_object->ref_count++; + + /* + * Does the page exist in the copy? + */ + copy_offset = first_offset + - copy_object->shadow_offset; + copy_m = vm_page_lookup(copy_object, copy_offset); + if (page_exists = (copy_m != NULL)) { + if (copy_m->busy) { +#ifdef DOTHREADS + int wait_result; + + /* + * If the page is being brought + * in, wait for it and then retry. + */ + PAGE_ASSERT_WAIT(copy_m, !change_wiring); + RELEASE_PAGE(m); + copy_object->ref_count--; + vm_object_unlock(copy_object); + UNLOCK_THINGS; + thread_block(); + wait_result = current_thread()->wait_result; + vm_object_deallocate(first_object); + if (wait_result != THREAD_AWAKENED) + return(KERN_SUCCESS); + goto RetryFault; +#else + /* + * If the page is being brought + * in, wait for it and then retry. + */ + PAGE_ASSERT_WAIT(copy_m, !change_wiring); + RELEASE_PAGE(m); + copy_object->ref_count--; + vm_object_unlock(copy_object); + UNLOCK_THINGS; +thread_wakeup(&vm_pages_needed); /* XXX */ + thread_block(); + vm_object_deallocate(first_object); + goto RetryFault; +#endif + } + } + + /* + * If the page is not in memory (in the object) + * and the object has a pager, we have to check + * if the pager has the data in secondary + * storage. + */ + if (!page_exists) { + + /* + * If we don't allocate a (blank) page + * here... another thread could try + * to page it in, allocate a page, and + * then block on the busy page in its + * shadow (first_object). Then we'd + * trip over the busy page after we + * found that the copy_object's pager + * doesn't have the page... + */ + copy_m = vm_page_alloc(copy_object, + copy_offset); + if (copy_m == NULL) { + /* + * Wait for a page, then retry. + */ + RELEASE_PAGE(m); + copy_object->ref_count--; + vm_object_unlock(copy_object); + UNLOCK_AND_DEALLOCATE; + VM_WAIT; + goto RetryFault; + } + + if (copy_object->pager != NULL) { + vm_object_unlock(object); + vm_object_unlock(copy_object); + UNLOCK_MAP; + + page_exists = vm_pager_has_page( + copy_object->pager, + (copy_offset + copy_object->paging_offset)); + + vm_object_lock(copy_object); + + /* + * Since the map is unlocked, someone + * else could have copied this object + * and put a different copy_object + * between the two. Or, the last + * reference to the copy-object (other + * than the one we have) may have + * disappeared - if that has happened, + * we don't need to make the copy. + */ + if (copy_object->shadow != object || + copy_object->ref_count == 1) { + /* + * Gaah... start over! + */ + FREE_PAGE(copy_m); + vm_object_unlock(copy_object); + vm_object_deallocate(copy_object); + /* may block */ + vm_object_lock(object); + goto RetryCopy; + } + vm_object_lock(object); + + if (page_exists) { + /* + * We didn't need the page + */ + FREE_PAGE(copy_m); + } + } + } + if (!page_exists) { + /* + * Must copy page into copy-object. + */ + vm_page_copy(m, copy_m); + copy_m->fake = FALSE; + copy_m->absent = FALSE; + + /* + * Things to remember: + * 1. The copied page must be marked 'dirty' + * so it will be paged out to the copy + * object. + * 2. If the old page was in use by any users + * of the copy-object, it must be removed + * from all pmaps. (We can't know which + * pmaps use it.) + */ + vm_page_lock_queues(); + pmap_page_protect(VM_PAGE_TO_PHYS(old_m), + VM_PROT_NONE); + copy_m->clean = FALSE; + vm_page_activate(copy_m); /* XXX */ + vm_page_unlock_queues(); + + PAGE_WAKEUP(copy_m); + } + /* + * The reference count on copy_object must be + * at least 2: one for our extra reference, + * and at least one from the outside world + * (we checked that when we last locked + * copy_object). + */ + copy_object->ref_count--; + vm_object_unlock(copy_object); + m->copy_on_write = FALSE; + } + } + + if (m->active || m->inactive) + panic("vm_fault: active or inactive before retrying lookup"); + + /* + * We must verify that the maps have not changed + * since our last lookup. + */ + + if (!lookup_still_valid) { + vm_object_t retry_object; + vm_offset_t retry_offset; + vm_prot_t retry_prot; + + /* + * Since map entries may be pageable, make sure we can + * take a page fault on them. + */ + vm_object_unlock(object); + + /* + * To avoid trying to write_lock the map while another + * thread has it read_locked (in vm_map_pageable), we + * do not try for write permission. If the page is + * still writable, we will get write permission. If it + * is not, or has been marked needs_copy, we enter the + * mapping without write permission, and will merely + * take another fault. + */ + result = vm_map_lookup(&map, vaddr, + fault_type & ~VM_PROT_WRITE, &entry, + &retry_object, &retry_offset, &retry_prot, + &wired, &su); + + vm_object_lock(object); + + /* + * If we don't need the page any longer, put it on the + * active list (the easiest thing to do here). If no + * one needs it, pageout will grab it eventually. + */ + + if (result != KERN_SUCCESS) { + RELEASE_PAGE(m); + UNLOCK_AND_DEALLOCATE; + return(result); + } + + lookup_still_valid = TRUE; + + if ((retry_object != first_object) || + (retry_offset != first_offset)) { + RELEASE_PAGE(m); + UNLOCK_AND_DEALLOCATE; + goto RetryFault; + } + + /* + * Check whether the protection has changed or the object + * has been copied while we left the map unlocked. + * Changing from read to write permission is OK - we leave + * the page write-protected, and catch the write fault. + * Changing from write to read permission means that we + * can't mark the page write-enabled after all. + */ + prot &= retry_prot; + if (m->copy_on_write) + prot &= ~VM_PROT_WRITE; + } + + /* + * (the various bits we're fiddling with here are locked by + * the object's lock) + */ + + /* XXX This distorts the meaning of the copy_on_write bit */ + + if (prot & VM_PROT_WRITE) + m->copy_on_write = FALSE; + + /* + * It's critically important that a wired-down page be faulted + * only once in each map for which it is wired. + */ + + if (m->active || m->inactive) + panic("vm_fault: active or inactive before pmap_enter"); + + vm_object_unlock(object); + + /* + * Put this page into the physical map. + * We had to do the unlock above because pmap_enter + * may cause other faults. We don't put the + * page back on the active queue until later so + * that the page-out daemon won't find us (yet). + */ + + pmap_enter(map->pmap, vaddr, VM_PAGE_TO_PHYS(m), + prot & ~(m->page_lock), wired); + + /* + * If the page is not wired down, then put it where the + * pageout daemon can find it. + */ + vm_object_lock(object); + vm_page_lock_queues(); + if (change_wiring) { + if (wired) + vm_page_wire(m); + else + vm_page_unwire(m); + } + else + vm_page_activate(m); + vm_page_unlock_queues(); + + /* + * Unlock everything, and return + */ + + PAGE_WAKEUP(m); + UNLOCK_AND_DEALLOCATE; + + return(KERN_SUCCESS); + +} + +/* + * vm_fault_wire: + * + * Wire down a range of virtual addresses in a map. + */ +void vm_fault_wire(map, start, end) + vm_map_t map; + vm_offset_t start, end; +{ + + register vm_offset_t va; + register pmap_t pmap; + + pmap = vm_map_pmap(map); + + /* + * Inform the physical mapping system that the + * range of addresses may not fault, so that + * page tables and such can be locked down as well. + */ + + pmap_pageable(pmap, start, end, FALSE); + + /* + * We simulate a fault to get the page and enter it + * in the physical map. + */ + + for (va = start; va < end; va += PAGE_SIZE) { + (void) vm_fault(map, va, VM_PROT_NONE, TRUE); + } +} + + +/* + * vm_fault_unwire: + * + * Unwire a range of virtual addresses in a map. + */ +void vm_fault_unwire(map, start, end) + vm_map_t map; + vm_offset_t start, end; +{ + + register vm_offset_t va, pa; + register pmap_t pmap; + + pmap = vm_map_pmap(map); + + /* + * Since the pages are wired down, we must be able to + * get their mappings from the physical map system. + */ + + vm_page_lock_queues(); + + for (va = start; va < end; va += PAGE_SIZE) { + pa = pmap_extract(pmap, va); + if (pa == (vm_offset_t) 0) { + panic("unwire: page not in pmap"); + } + pmap_change_wiring(pmap, va, FALSE); + vm_page_unwire(PHYS_TO_VM_PAGE(pa)); + } + vm_page_unlock_queues(); + + /* + * Inform the physical mapping system that the range + * of addresses may fault, so that page tables and + * such may be unwired themselves. + */ + + pmap_pageable(pmap, start, end, TRUE); + +} + +/* + * Routine: + * vm_fault_copy_entry + * Function: + * Copy all of the pages from a wired-down map entry to another. + * + * In/out conditions: + * The source and destination maps must be locked for write. + * The source map entry must be wired down (or be a sharing map + * entry corresponding to a main map entry that is wired down). + */ + +void vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry) + vm_map_t dst_map; + vm_map_t src_map; + vm_map_entry_t dst_entry; + vm_map_entry_t src_entry; +{ + + vm_object_t dst_object; + vm_object_t src_object; + vm_offset_t dst_offset; + vm_offset_t src_offset; + vm_prot_t prot; + vm_offset_t vaddr; + vm_page_t dst_m; + vm_page_t src_m; + +#ifdef lint + src_map++; +#endif lint + + src_object = src_entry->object.vm_object; + src_offset = src_entry->offset; + + /* + * Create the top-level object for the destination entry. + * (Doesn't actually shadow anything - we copy the pages + * directly.) + */ + dst_object = vm_object_allocate( + (vm_size_t) (dst_entry->end - dst_entry->start)); + + dst_entry->object.vm_object = dst_object; + dst_entry->offset = 0; + + prot = dst_entry->max_protection; + + /* + * Loop through all of the pages in the entry's range, copying + * each one from the source object (it should be there) to the + * destination object. + */ + for (vaddr = dst_entry->start, dst_offset = 0; + vaddr < dst_entry->end; + vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { + + /* + * Allocate a page in the destination object + */ + vm_object_lock(dst_object); + do { + dst_m = vm_page_alloc(dst_object, dst_offset); + if (dst_m == NULL) { + vm_object_unlock(dst_object); + VM_WAIT; + vm_object_lock(dst_object); + } + } while (dst_m == NULL); + + /* + * Find the page in the source object, and copy it in. + * (Because the source is wired down, the page will be + * in memory.) + */ + vm_object_lock(src_object); + src_m = vm_page_lookup(src_object, dst_offset + src_offset); + if (src_m == NULL) + panic("vm_fault_copy_wired: page missing"); + + vm_page_copy(src_m, dst_m); + + /* + * Enter it in the pmap... + */ + vm_object_unlock(src_object); + vm_object_unlock(dst_object); + + pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m), + prot, FALSE); + + /* + * Mark it no longer busy, and put it on the active list. + */ + vm_object_lock(dst_object); + vm_page_lock_queues(); + vm_page_activate(dst_m); + vm_page_unlock_queues(); + PAGE_WAKEUP(dst_m); + vm_object_unlock(dst_object); + } + +} -- 2.20.1