/* * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * Copyright (c) 1994 John S. Dyson * All rights reserved. * Copyright (c) 1994 David Greenman * 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. * * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 * * * 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. */ /* * Page fault handling module. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define PFBAK 4 #define PFFOR 4 #define PAGEORDER_SIZE (PFBAK+PFFOR) static int prefault_pageorder[] = { -1 * PAGE_SIZE, 1 * PAGE_SIZE, -2 * PAGE_SIZE, 2 * PAGE_SIZE, -3 * PAGE_SIZE, 3 * PAGE_SIZE, -4 * PAGE_SIZE, 4 * PAGE_SIZE }; static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); #define VM_FAULT_READ_AHEAD 8 #define VM_FAULT_READ_BEHIND 7 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1) struct faultstate { vm_page_t m; vm_object_t object; vm_pindex_t pindex; vm_page_t first_m; vm_object_t first_object; vm_pindex_t first_pindex; vm_map_t map; vm_map_entry_t entry; int lookup_still_valid; struct vnode *vp; }; static __inline void release_page(struct faultstate *fs) { vm_page_lock_queues(); vm_page_wakeup(fs->m); vm_page_deactivate(fs->m); vm_page_unlock_queues(); fs->m = NULL; } static __inline void unlock_map(struct faultstate *fs) { if (fs->lookup_still_valid) { vm_map_lookup_done(fs->map, fs->entry); fs->lookup_still_valid = FALSE; } } static void _unlock_things(struct faultstate *fs, int dealloc) { vm_object_pip_wakeup(fs->object); VM_OBJECT_UNLOCK(fs->object); if (fs->object != fs->first_object) { VM_OBJECT_LOCK(fs->first_object); vm_page_lock_queues(); vm_page_free(fs->first_m); vm_page_unlock_queues(); vm_object_pip_wakeup(fs->first_object); VM_OBJECT_UNLOCK(fs->first_object); fs->first_m = NULL; } if (dealloc) { vm_object_deallocate(fs->first_object); } unlock_map(fs); if (fs->vp != NULL) { vput(fs->vp); fs->vp = NULL; } if (dealloc) mtx_unlock(&Giant); } #define unlock_things(fs) _unlock_things(fs, 0) #define unlock_and_deallocate(fs) _unlock_things(fs, 1) /* * TRYPAGER - used by vm_fault to calculate whether the pager for the * current object *might* contain the page. * * default objects are zero-fill, there is no real pager. */ #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) /* * vm_fault: * * Handle a page fault occurring 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. */ int vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags) { vm_prot_t prot; int is_first_object_locked, result; boolean_t growstack, wired; int map_generation; vm_object_t next_object; vm_page_t marray[VM_FAULT_READ]; int hardfault; int faultcount; struct faultstate fs; hardfault = 0; growstack = TRUE; atomic_add_int(&cnt.v_vm_faults, 1); RetryFault:; /* * Find the backing store object and offset into it to begin the * search. */ fs.map = map; result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired); if (result != KERN_SUCCESS) { if (result != KERN_PROTECTION_FAILURE || (fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) { if (growstack && result == KERN_INVALID_ADDRESS && map != kernel_map && curproc != NULL) { result = vm_map_growstack(curproc, vaddr); if (result != KERN_SUCCESS) return (KERN_FAILURE); growstack = FALSE; goto RetryFault; } return (result); } /* * If we are user-wiring a r/w segment, and it is COW, then * we need to do the COW operation. Note that we don't COW * currently RO sections now, because it is NOT desirable * to COW .text. We simply keep .text from ever being COW'ed * and take the heat that one cannot debug wired .text sections. */ result = vm_map_lookup(&fs.map, vaddr, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE, &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired); if (result != KERN_SUCCESS) return (result); /* * If we don't COW now, on a user wire, the user will never * be able to write to the mapping. If we don't make this * restriction, the bookkeeping would be nearly impossible. * * XXX The following assignment modifies the map without * holding a write lock on it. */ if ((fs.entry->protection & VM_PROT_WRITE) == 0) fs.entry->max_protection &= ~VM_PROT_WRITE; } map_generation = fs.map->timestamp; if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { panic("vm_fault: fault on nofault entry, addr: %lx", (u_long)vaddr); } /* * 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. * * Bump the paging-in-progress count to prevent size changes (e.g. * truncation operations) during I/O. This must be done after * obtaining the vnode lock in order to avoid possible deadlocks. * * XXX vnode_pager_lock() can block without releasing the map lock. */ mtx_lock(&Giant); VM_OBJECT_LOCK(fs.first_object); vm_object_reference_locked(fs.first_object); fs.vp = vnode_pager_lock(fs.first_object); vm_object_pip_add(fs.first_object, 1); fs.lookup_still_valid = TRUE; if (wired) fault_type = prot; fs.first_m = NULL; /* * Search for the page at object/offset. */ fs.object = fs.first_object; fs.pindex = fs.first_pindex; while (TRUE) { /* * If the object is dead, we stop here */ if (fs.object->flags & OBJ_DEAD) { unlock_and_deallocate(&fs); return (KERN_PROTECTION_FAILURE); } /* * See if page is resident */ fs.m = vm_page_lookup(fs.object, fs.pindex); if (fs.m != NULL) { int queue, s; /* * check for page-based copy on write. * We check fs.object == fs.first_object so * as to ensure the legacy COW mechanism is * used when the page in question is part of * a shadow object. Otherwise, vm_page_cowfault() * removes the page from the backing object, * which is not what we want. */ vm_page_lock_queues(); if ((fs.m->cow) && (fault_type & VM_PROT_WRITE) && (fs.object == fs.first_object)) { s = splvm(); vm_page_cowfault(fs.m); splx(s); vm_page_unlock_queues(); unlock_and_deallocate(&fs); goto RetryFault; } /* * Wait/Retry if the page is busy. We have to do this * if the page is busy via either PG_BUSY or * vm_page_t->busy because the vm_pager may be using * vm_page_t->busy for pageouts ( and even pageins if * it is the vnode pager ), and we could end up trying * to pagein and pageout the same page simultaneously. * * We can theoretically allow the busy case on a read * fault if the page is marked valid, but since such * pages are typically already pmap'd, putting that * special case in might be more effort then it is * worth. We cannot under any circumstances mess * around with a vm_page_t->busy page except, perhaps, * to pmap it. */ if ((fs.m->flags & PG_BUSY) || fs.m->busy) { vm_page_unlock_queues(); unlock_things(&fs); vm_page_lock_queues(); if (!vm_page_sleep_if_busy(fs.m, TRUE, "vmpfw")) vm_page_unlock_queues(); cnt.v_intrans++; mtx_unlock(&Giant); vm_object_deallocate(fs.first_object); goto RetryFault; } queue = fs.m->queue; s = splvm(); vm_pageq_remove_nowakeup(fs.m); splx(s); if ((queue - fs.m->pc) == PQ_CACHE && vm_page_count_severe()) { vm_page_activate(fs.m); vm_page_unlock_queues(); unlock_and_deallocate(&fs); VM_WAITPFAULT; goto RetryFault; } /* * Mark page busy for other processes, and the * pagedaemon. If it still isn't completely valid * (readable), jump to readrest, else break-out ( we * found the page ). */ vm_page_busy(fs.m); vm_page_unlock_queues(); if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) && fs.m->object != kernel_object && fs.m->object != kmem_object) { goto readrest; } break; } /* * Page is not resident, If this is the search termination * or the pager might contain the page, allocate a new page. */ if (TRYPAGER || fs.object == fs.first_object) { if (fs.pindex >= fs.object->size) { unlock_and_deallocate(&fs); return (KERN_PROTECTION_FAILURE); } /* * Allocate a new page for this object/offset pair. */ fs.m = NULL; if (!vm_page_count_severe()) { fs.m = vm_page_alloc(fs.object, fs.pindex, (fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO); } if (fs.m == NULL) { unlock_and_deallocate(&fs); VM_WAITPFAULT; goto RetryFault; } } readrest: /* * We have found a valid page or we have allocated a new page. * The page thus may not be valid or may not be entirely * valid. * * Attempt to fault-in the page if there is a chance that the * pager has it, and potentially fault in additional pages * at the same time. */ if (TRYPAGER) { int rv; int reqpage; int ahead, behind; u_char behavior = vm_map_entry_behavior(fs.entry); if (behavior == MAP_ENTRY_BEHAV_RANDOM) { ahead = 0; behind = 0; } else { behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; if (behind > VM_FAULT_READ_BEHIND) behind = VM_FAULT_READ_BEHIND; ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; if (ahead > VM_FAULT_READ_AHEAD) ahead = VM_FAULT_READ_AHEAD; } is_first_object_locked = FALSE; if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || (behavior != MAP_ENTRY_BEHAV_RANDOM && fs.pindex >= fs.entry->lastr && fs.pindex < fs.entry->lastr + VM_FAULT_READ)) && (fs.first_object == fs.object || (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) && fs.first_object->type != OBJT_DEVICE) { vm_pindex_t firstpindex, tmppindex; if (fs.first_pindex < 2 * VM_FAULT_READ) firstpindex = 0; else firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; vm_page_lock_queues(); /* * note: partially valid pages cannot be * included in the lookahead - NFS piecemeal * writes will barf on it badly. */ for (tmppindex = fs.first_pindex - 1; tmppindex >= firstpindex; --tmppindex) { vm_page_t mt; mt = vm_page_lookup(fs.first_object, tmppindex); if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL)) break; if (mt->busy || (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) || mt->hold_count || mt->wire_count) continue; if (mt->dirty == 0) vm_page_test_dirty(mt); if (mt->dirty) { pmap_remove_all(mt); vm_page_deactivate(mt); } else { vm_page_cache(mt); } } vm_page_unlock_queues(); ahead += behind; behind = 0; } if (is_first_object_locked) VM_OBJECT_UNLOCK(fs.first_object); /* * now we find out if any other pages should be paged * in at this time this routine checks to see if the * pages surrounding this fault reside in the same * object as the page for this fault. If they do, * then they are faulted in also into the object. The * array "marray" returned contains an array of * vm_page_t structs where one of them is the * vm_page_t passed to the routine. The reqpage * return value is the index into the marray for the * vm_page_t passed to the routine. * * fs.m plus the additional pages are PG_BUSY'd. * * XXX vm_fault_additional_pages() can block * without releasing the map lock. */ faultcount = vm_fault_additional_pages( fs.m, behind, ahead, marray, &reqpage); /* * update lastr imperfectly (we do not know how much * getpages will actually read), but good enough. * * XXX The following assignment modifies the map * without holding a write lock on it. */ fs.entry->lastr = fs.pindex + faultcount - behind; /* * Call the pager to retrieve the data, if any, after * releasing the lock on the map. We hold a ref on * fs.object and the pages are PG_BUSY'd. */ unlock_map(&fs); rv = faultcount ? vm_pager_get_pages(fs.object, marray, faultcount, reqpage) : VM_PAGER_FAIL; if (rv == VM_PAGER_OK) { /* * Found the page. Leave it busy while we play * with it. */ /* * Relookup in case pager changed page. Pager * is responsible for disposition of old page * if moved. */ fs.m = vm_page_lookup(fs.object, fs.pindex); if (!fs.m) { unlock_and_deallocate(&fs); goto RetryFault; } hardfault++; break; /* break to PAGE HAS BEEN FOUND */ } /* * 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 process that may want to bring * in this page. * * If this is the top-level object, we must leave the * busy page to prevent another process from rushing * past us, and inserting the page in that object at * the same time that we are. */ if (rv == VM_PAGER_ERROR) printf("vm_fault: pager read error, pid %d (%s)\n", curproc->p_pid, curproc->p_comm); /* * Data outside the range of the pager or an I/O error */ /* * XXX - the check for kernel_map is a kludge to work * around having the machine panic on a kernel space * fault w/ I/O error. */ if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) { vm_page_lock_queues(); vm_page_free(fs.m); vm_page_unlock_queues(); fs.m = NULL; unlock_and_deallocate(&fs); return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); } if (fs.object != fs.first_object) { vm_page_lock_queues(); vm_page_free(fs.m); vm_page_unlock_queues(); fs.m = NULL; /* * XXX - we cannot just fall out at this * point, m has been freed and is invalid! */ } } /* * We get here if the object has default pager (or unwiring) * or the pager doesn't have the page. */ if (fs.object == fs.first_object) fs.first_m = fs.m; /* * Move on to the next object. Lock the next object before * unlocking the current one. */ fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); next_object = fs.object->backing_object; if (next_object == NULL) { /* * If there's no object left, fill the page in the top * object with zeros. */ if (fs.object != fs.first_object) { vm_object_pip_wakeup(fs.object); VM_OBJECT_UNLOCK(fs.object); fs.object = fs.first_object; fs.pindex = fs.first_pindex; fs.m = fs.first_m; VM_OBJECT_LOCK(fs.object); } fs.first_m = NULL; /* * Zero the page if necessary and mark it valid. */ if ((fs.m->flags & PG_ZERO) == 0) { pmap_zero_page(fs.m); } else { cnt.v_ozfod++; } cnt.v_zfod++; fs.m->valid = VM_PAGE_BITS_ALL; break; /* break to PAGE HAS BEEN FOUND */ } else { KASSERT(fs.object != next_object, ("object loop %p", next_object)); VM_OBJECT_LOCK(next_object); vm_object_pip_add(next_object, 1); if (fs.object != fs.first_object) vm_object_pip_wakeup(fs.object); VM_OBJECT_UNLOCK(fs.object); fs.object = next_object; } } KASSERT((fs.m->flags & PG_BUSY) != 0, ("vm_fault: not busy after main loop")); /* * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock * is held.] */ /* * 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 (fs.object != fs.first_object) { /* * We only really need to copy if we want to write it. */ if (fault_type & VM_PROT_WRITE) { /* * This allows pages to be virtually copied from a * backing_object into the first_object, where the * backing object has no other refs to it, and cannot * gain any more refs. Instead of a bcopy, we just * move the page from the backing object to the * first object. Note that we must mark the page * dirty in the first object so that it will go out * to swap when needed. */ is_first_object_locked = FALSE; if ( /* * Only one shadow object */ (fs.object->shadow_count == 1) && /* * No COW refs, except us */ (fs.object->ref_count == 1) && /* * No one else can look this object up */ (fs.object->handle == NULL) && /* * No other ways to look the object up */ ((fs.object->type == OBJT_DEFAULT) || (fs.object->type == OBJT_SWAP)) && (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && /* * We don't chase down the shadow chain */ fs.object == fs.first_object->backing_object) { vm_page_lock_queues(); /* * get rid of the unnecessary page */ pmap_remove_all(fs.first_m); vm_page_free(fs.first_m); /* * grab the page and put it into the * process'es object. The page is * automatically made dirty. */ vm_page_rename(fs.m, fs.first_object, fs.first_pindex); vm_page_busy(fs.m); vm_page_unlock_queues(); fs.first_m = fs.m; fs.m = NULL; cnt.v_cow_optim++; } else { /* * Oh, well, lets copy it. */ pmap_copy_page(fs.m, fs.first_m); fs.first_m->valid = VM_PAGE_BITS_ALL; } if (fs.m) { /* * We no longer need the old page or object. */ release_page(&fs); } /* * fs.object != fs.first_object due to above * conditional */ vm_object_pip_wakeup(fs.object); VM_OBJECT_UNLOCK(fs.object); /* * Only use the new page below... */ fs.object = fs.first_object; fs.pindex = fs.first_pindex; fs.m = fs.first_m; if (!is_first_object_locked) VM_OBJECT_LOCK(fs.object); cnt.v_cow_faults++; } else { prot &= ~VM_PROT_WRITE; } } /* * We must verify that the maps have not changed since our last * lookup. */ if (!fs.lookup_still_valid && (fs.map->timestamp != map_generation)) { vm_object_t retry_object; vm_pindex_t retry_pindex; vm_prot_t retry_prot; /* * Since map entries may be pageable, make sure we can take a * page fault on them. */ /* * Unlock vnode before the lookup to avoid deadlock. E.G. * avoid a deadlock between the inode and exec_map that can * occur due to locks being obtained in different orders. */ if (fs.vp != NULL) { vput(fs.vp); fs.vp = NULL; } if (fs.map->infork) { release_page(&fs); unlock_and_deallocate(&fs); goto RetryFault; } VM_OBJECT_UNLOCK(fs.object); /* * To avoid trying to write_lock the map while another process * has it read_locked (in vm_map_wire), 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(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE, &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); map_generation = fs.map->timestamp; VM_OBJECT_LOCK(fs.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(&fs); unlock_and_deallocate(&fs); return (result); } fs.lookup_still_valid = TRUE; if ((retry_object != fs.first_object) || (retry_pindex != fs.first_pindex)) { release_page(&fs); unlock_and_deallocate(&fs); 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; } /* * 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). */ if (prot & VM_PROT_WRITE) { vm_page_lock_queues(); vm_page_flag_set(fs.m, PG_WRITEABLE); vm_object_set_writeable_dirty(fs.m->object); /* * If the fault is a write, we know that this page is being * written NOW so dirty it explicitly to save on * pmap_is_modified() calls later. * * If this is a NOSYNC mmap we do not want to set PG_NOSYNC * if the page is already dirty to prevent data written with * the expectation of being synced from not being synced. * Likewise if this entry does not request NOSYNC then make * sure the page isn't marked NOSYNC. Applications sharing * data should use the same flags to avoid ping ponging. * * Also tell the backing pager, if any, that it should remove * any swap backing since the page is now dirty. */ if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { if (fs.m->dirty == 0) vm_page_flag_set(fs.m, PG_NOSYNC); } else { vm_page_flag_clear(fs.m, PG_NOSYNC); } vm_page_unlock_queues(); if (fault_flags & VM_FAULT_DIRTY) { int s; vm_page_dirty(fs.m); s = splvm(); vm_pager_page_unswapped(fs.m); splx(s); } } /* * Page had better still be busy */ KASSERT(fs.m->flags & PG_BUSY, ("vm_fault: page %p not busy!", fs.m)); /* * Sanity check: page must be completely valid or it is not fit to * map into user space. vm_pager_get_pages() ensures this. */ if (fs.m->valid != VM_PAGE_BITS_ALL) { vm_page_zero_invalid(fs.m, TRUE); printf("Warning: page %p partially invalid on fault\n", fs.m); } unlock_things(&fs); pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired); if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) { vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); } mtx_unlock(&Giant); vm_page_lock_queues(); vm_page_flag_clear(fs.m, PG_ZERO); vm_page_flag_set(fs.m, PG_REFERENCED); /* * If the page is not wired down, then put it where the pageout daemon * can find it. */ if (fault_flags & VM_FAULT_WIRE_MASK) { if (wired) vm_page_wire(fs.m); else vm_page_unwire(fs.m, 1); } else { vm_page_activate(fs.m); } vm_page_wakeup(fs.m); vm_page_unlock_queues(); PROC_LOCK(curproc); if ((curproc->p_sflag & PS_INMEM) && curproc->p_stats) { if (hardfault) { curproc->p_stats->p_ru.ru_majflt++; } else { curproc->p_stats->p_ru.ru_minflt++; } } PROC_UNLOCK(curproc); /* * Unlock everything, and return */ vm_object_deallocate(fs.first_object); return (KERN_SUCCESS); } /* * vm_fault_prefault provides a quick way of clustering * pagefaults into a processes address space. It is a "cousin" * of vm_map_pmap_enter, except it runs at page fault time instead * of mmap time. */ static void vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) { int i; vm_offset_t addr, starta; vm_pindex_t pindex; vm_page_t m, mpte; vm_object_t object; if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace))) return; object = entry->object.vm_object; starta = addra - PFBAK * PAGE_SIZE; if (starta < entry->start) { starta = entry->start; } else if (starta > addra) { starta = 0; } mpte = NULL; for (i = 0; i < PAGEORDER_SIZE; i++) { vm_object_t backing_object, lobject; addr = addra + prefault_pageorder[i]; if (addr > addra + (PFFOR * PAGE_SIZE)) addr = 0; if (addr < starta || addr >= entry->end) continue; if (!pmap_is_prefaultable(pmap, addr)) continue; pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; lobject = object; VM_OBJECT_LOCK(lobject); while ((m = vm_page_lookup(lobject, pindex)) == NULL && lobject->type == OBJT_DEFAULT && (backing_object = lobject->backing_object) != NULL) { if (lobject->backing_object_offset & PAGE_MASK) break; pindex += lobject->backing_object_offset >> PAGE_SHIFT; VM_OBJECT_LOCK(backing_object); VM_OBJECT_UNLOCK(lobject); lobject = backing_object; } /* * give-up when a page is not in memory */ if (m == NULL) { VM_OBJECT_UNLOCK(lobject); break; } vm_page_lock_queues(); if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) && (m->busy == 0) && (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) { if ((m->queue - m->pc) == PQ_CACHE) { vm_page_deactivate(m); } vm_page_busy(m); vm_page_unlock_queues(); VM_OBJECT_UNLOCK(lobject); mpte = pmap_enter_quick(pmap, addr, m, mpte); VM_OBJECT_LOCK(lobject); vm_page_lock_queues(); vm_page_wakeup(m); } vm_page_unlock_queues(); VM_OBJECT_UNLOCK(lobject); } } /* * vm_fault_quick: * * Ensure that the requested virtual address, which may be in userland, * is valid. Fault-in the page if necessary. Return -1 on failure. */ int vm_fault_quick(caddr_t v, int prot) { int r; if (prot & VM_PROT_WRITE) r = subyte(v, fubyte(v)); else r = fubyte(v); return(r); } /* * vm_fault_wire: * * Wire down a range of virtual addresses in a map. */ int vm_fault_wire(map, start, end, user_wire) vm_map_t map; vm_offset_t start, end; boolean_t user_wire; { vm_offset_t va; int rv; /* * We simulate a fault to get the page and enter it in the physical * map. For user wiring, we only ask for read access on currently * read-only sections. */ for (va = start; va < end; va += PAGE_SIZE) { rv = vm_fault(map, va, user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE, user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING); if (rv) { if (va != start) vm_fault_unwire(map, start, va); return (rv); } } return (KERN_SUCCESS); } /* * 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; { vm_paddr_t pa; vm_offset_t va; pmap_t pmap; pmap = vm_map_pmap(map); mtx_lock(&Giant); /* * Since the pages are wired down, we must be able to get their * mappings from the physical map system. */ for (va = start; va < end; va += PAGE_SIZE) { pa = pmap_extract(pmap, va); if (pa != 0) { pmap_change_wiring(pmap, va, FALSE); vm_page_lock_queues(); vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); vm_page_unlock_queues(); } } mtx_unlock(&Giant); } /* * 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 backing_object, dst_object, object; vm_object_t src_object; vm_ooffset_t dst_offset; vm_ooffset_t src_offset; vm_pindex_t pindex; 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(OBJT_DEFAULT, (vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start)); VM_OBJECT_LOCK(dst_object); 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 */ do { dst_m = vm_page_alloc(dst_object, OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL); 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); object = src_object; pindex = 0; while ((src_m = vm_page_lookup(object, pindex + OFF_TO_IDX(dst_offset + src_offset))) == NULL && (src_entry->protection & VM_PROT_WRITE) == 0 && (backing_object = object->backing_object) != NULL) { /* * Allow fallback to backing objects if we are reading. */ VM_OBJECT_LOCK(backing_object); pindex += OFF_TO_IDX(object->backing_object_offset); VM_OBJECT_UNLOCK(object); object = backing_object; } if (src_m == NULL) panic("vm_fault_copy_wired: page missing"); pmap_copy_page(src_m, dst_m); VM_OBJECT_UNLOCK(object); dst_m->valid = VM_PAGE_BITS_ALL; VM_OBJECT_UNLOCK(dst_object); /* * Enter it in the pmap... */ pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE); VM_OBJECT_LOCK(dst_object); vm_page_lock_queues(); if ((prot & VM_PROT_WRITE) != 0) vm_page_flag_set(dst_m, PG_WRITEABLE); /* * Mark it no longer busy, and put it on the active list. */ vm_page_activate(dst_m); vm_page_wakeup(dst_m); vm_page_unlock_queues(); } VM_OBJECT_UNLOCK(dst_object); } /* * This routine checks around the requested page for other pages that * might be able to be faulted in. This routine brackets the viable * pages for the pages to be paged in. * * Inputs: * m, rbehind, rahead * * Outputs: * marray (array of vm_page_t), reqpage (index of requested page) * * Return value: * number of pages in marray * * This routine can't block. */ static int vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) vm_page_t m; int rbehind; int rahead; vm_page_t *marray; int *reqpage; { int i,j; vm_object_t object; vm_pindex_t pindex, startpindex, endpindex, tpindex; vm_page_t rtm; int cbehind, cahead; VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); object = m->object; pindex = m->pindex; /* * we don't fault-ahead for device pager */ if (object->type == OBJT_DEVICE) { *reqpage = 0; marray[0] = m; return 1; } /* * if the requested page is not available, then give up now */ if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { return 0; } if ((cbehind == 0) && (cahead == 0)) { *reqpage = 0; marray[0] = m; return 1; } if (rahead > cahead) { rahead = cahead; } if (rbehind > cbehind) { rbehind = cbehind; } /* * try to do any readahead that we might have free pages for. */ if ((rahead + rbehind) > ((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) { pagedaemon_wakeup(); marray[0] = m; *reqpage = 0; return 1; } /* * scan backward for the read behind pages -- in memory */ if (pindex > 0) { if (rbehind > pindex) { rbehind = pindex; startpindex = 0; } else { startpindex = pindex - rbehind; } for (tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) { if (vm_page_lookup(object, tpindex)) { startpindex = tpindex + 1; break; } if (tpindex == 0) break; } for (i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) { rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); if (rtm == NULL) { vm_page_lock_queues(); for (j = 0; j < i; j++) { vm_page_free(marray[j]); } vm_page_unlock_queues(); marray[0] = m; *reqpage = 0; return 1; } marray[i] = rtm; } } else { startpindex = 0; i = 0; } marray[i] = m; /* page offset of the required page */ *reqpage = i; tpindex = pindex + 1; i++; /* * scan forward for the read ahead pages */ endpindex = tpindex + rahead; if (endpindex > object->size) endpindex = object->size; for (; tpindex < endpindex; i++, tpindex++) { if (vm_page_lookup(object, tpindex)) { break; } rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); if (rtm == NULL) { break; } marray[i] = rtm; } /* return number of bytes of pages */ return i; }