1/*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1995, David Greenman 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by David Greenman. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#include <sys/cdefs.h> 35__FBSDID("$FreeBSD$"); 36 37#include <sys/param.h> 38#include <sys/systm.h> 39#include <sys/lock.h> 40#include <sys/proc.h> 41#include <sys/resourcevar.h> 42#include <sys/rwlock.h> 43#include <sys/user.h> 44 45#include <vm/vm.h> 46#include <vm/vm_object.h> 47#include <vm/vm_page.h> 48#include <vm/vm_pager.h> 49#include <vm/swap_pager.h> 50 51static vm_object_t default_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 52 vm_ooffset_t, struct ucred *); 53static void default_pager_dealloc(vm_object_t); 54static int default_pager_getpages(vm_object_t, vm_page_t *, int, 55 int *, int *); 56static void default_pager_putpages(vm_object_t, vm_page_t *, int, 57 boolean_t, int *); 58static boolean_t default_pager_haspage(vm_object_t, vm_pindex_t, int *, 59 int *); 60 61/* 62 * pagerops for OBJT_DEFAULT - "default pager". 63 * 64 * This pager handles anonymous (no handle) swap-backed memory, just 65 * like the swap pager. It allows several optimizations based on the 66 * fact that no pages of a default object can be swapped out. The 67 * most important optimization is in vm_fault(), where the pager is 68 * never asked for a non-resident page. Instead, a freshly allocated 69 * zeroed page is used. 70 * 71 * On the first request to page out a page from a default object, the 72 * object is converted to swap pager type. 73 */ 74const struct pagerops defaultpagerops = { 75 .pgo_kvme_type = KVME_TYPE_DEFAULT, 76 .pgo_alloc = default_pager_alloc, 77 .pgo_dealloc = default_pager_dealloc, 78 .pgo_getpages = default_pager_getpages, 79 .pgo_putpages = default_pager_putpages, 80 .pgo_haspage = default_pager_haspage, 81}; 82 83/* 84 * Return an initialized object. 85 */ 86static vm_object_t 87default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 88 vm_ooffset_t offset, struct ucred *cred) 89{ 90 vm_object_t object; 91 92 if (handle != NULL) 93 panic("default_pager_alloc: handle specified"); 94 if (cred != NULL) { 95 if (!swap_reserve_by_cred(size, cred)) 96 return (NULL); 97 crhold(cred); 98 } 99 object = vm_object_allocate(OBJT_DEFAULT, 100 OFF_TO_IDX(round_page(offset + size))); 101 if (cred != NULL) { 102 object->cred = cred; 103 object->charge = size; 104 } 105 return (object); 106} 107 108/* 109 * Deallocate resources associated with the object. 110 */ 111static void 112default_pager_dealloc(vm_object_t object) 113{ 114 115 /* Reserved swap is released by vm_object_destroy(). */ 116 object->type = OBJT_DEAD; 117} 118 119/* 120 * Load pages from backing store. 121 */ 122static int 123default_pager_getpages(vm_object_t object, vm_page_t *m, int count, 124 int *rbehind, int *rahead) 125{ 126 127 /* 128 * Since an OBJT_DEFAULT object is converted to OBJT_SWAP by the first 129 * call to the putpages method, this function will never be called on 130 * a vm_page with assigned swap. 131 */ 132 return (VM_PAGER_FAIL); 133} 134 135/* 136 * Store pages to backing store. 137 */ 138static void 139default_pager_putpages(vm_object_t object, vm_page_t *m, int count, 140 int flags, int *rtvals) 141{ 142 143 /* The swap pager will convert the object to OBJT_SWAP. */ 144 swappagerops.pgo_putpages(object, m, count, flags, rtvals); 145} 146 147/* 148 * Tell us whether the requested (object,index) is available from the object's 149 * backing store. 150 */ 151static boolean_t 152default_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 153 int *after) 154{ 155 156 /* An OBJT_DEFAULT object has no backing store. */ 157 return (FALSE); 158} 159