phys_pager.c revision 171737
1/*- 2 * Copyright (c) 2000 Peter Wemm 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 */ 25 26#include <sys/cdefs.h> 27__FBSDID("$FreeBSD: head/sys/vm/phys_pager.c 171737 2007-08-05 21:04:32Z alc $"); 28 29#include <sys/param.h> 30#include <sys/systm.h> 31#include <sys/linker_set.h> 32#include <sys/conf.h> 33#include <sys/kernel.h> 34#include <sys/lock.h> 35#include <sys/proc.h> 36#include <sys/mutex.h> 37#include <sys/mman.h> 38#include <sys/sysctl.h> 39 40#include <vm/vm.h> 41#include <vm/vm_object.h> 42#include <vm/vm_page.h> 43#include <vm/vm_pager.h> 44 45/* prevent concurrent creation races */ 46static int phys_pager_alloc_lock; 47/* list of device pager objects */ 48static struct pagerlst phys_pager_object_list; 49/* protect access to phys_pager_object_list */ 50static struct mtx phys_pager_mtx; 51 52static void 53phys_pager_init(void) 54{ 55 56 TAILQ_INIT(&phys_pager_object_list); 57 mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF); 58} 59 60/* 61 * MPSAFE 62 */ 63static vm_object_t 64phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 65 vm_ooffset_t foff) 66{ 67 vm_object_t object; 68 vm_pindex_t pindex; 69 70 /* 71 * Offset should be page aligned. 72 */ 73 if (foff & PAGE_MASK) 74 return (NULL); 75 76 pindex = OFF_TO_IDX(foff + PAGE_MASK + size); 77 78 if (handle != NULL) { 79 mtx_lock(&Giant); 80 /* 81 * Lock to prevent object creation race condition. 82 */ 83 while (phys_pager_alloc_lock) { 84 phys_pager_alloc_lock = -1; 85 tsleep(&phys_pager_alloc_lock, PVM, "swpalc", 0); 86 } 87 phys_pager_alloc_lock = 1; 88 89 /* 90 * Look up pager, creating as necessary. 91 */ 92 object = vm_pager_object_lookup(&phys_pager_object_list, handle); 93 if (object == NULL) { 94 /* 95 * Allocate object and associate it with the pager. 96 */ 97 object = vm_object_allocate(OBJT_PHYS, pindex); 98 object->handle = handle; 99 mtx_lock(&phys_pager_mtx); 100 TAILQ_INSERT_TAIL(&phys_pager_object_list, object, 101 pager_object_list); 102 mtx_unlock(&phys_pager_mtx); 103 } else { 104 if (pindex > object->size) 105 object->size = pindex; 106 } 107 if (phys_pager_alloc_lock == -1) 108 wakeup(&phys_pager_alloc_lock); 109 phys_pager_alloc_lock = 0; 110 mtx_unlock(&Giant); 111 } else { 112 object = vm_object_allocate(OBJT_PHYS, pindex); 113 } 114 115 return (object); 116} 117 118/* 119 * MPSAFE 120 */ 121static void 122phys_pager_dealloc(vm_object_t object) 123{ 124 125 if (object->handle != NULL) { 126 mtx_lock(&phys_pager_mtx); 127 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list); 128 mtx_unlock(&phys_pager_mtx); 129 } 130} 131 132/* 133 * Fill as many pages as vm_fault has allocated for us. 134 */ 135static int 136phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 137{ 138 int i; 139 140 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 141 for (i = 0; i < count; i++) { 142 if (m[i]->valid == 0) { 143 if ((m[i]->flags & PG_ZERO) == 0) 144 pmap_zero_page(m[i]); 145 m[i]->valid = VM_PAGE_BITS_ALL; 146 } 147 KASSERT(m[i]->valid == VM_PAGE_BITS_ALL, 148 ("phys_pager_getpages: partially valid page %p", m[i])); 149 m[i]->dirty = 0; 150 /* The requested page must remain busy, the others not. */ 151 if (reqpage != i) { 152 m[i]->oflags &= ~VPO_BUSY; 153 m[i]->busy = 0; 154 } 155 } 156 return (VM_PAGER_OK); 157} 158 159static void 160phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync, 161 int *rtvals) 162{ 163 164 panic("phys_pager_putpage called"); 165} 166 167/* 168 * Implement a pretty aggressive clustered getpages strategy. Hint that 169 * everything in an entire 4MB window should be prefaulted at once. 170 * 171 * XXX 4MB (1024 slots per page table page) is convenient for x86, 172 * but may not be for other arches. 173 */ 174#ifndef PHYSCLUSTER 175#define PHYSCLUSTER 1024 176#endif 177static boolean_t 178phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 179 int *after) 180{ 181 vm_pindex_t base, end; 182 183 base = pindex & (~(PHYSCLUSTER - 1)); 184 end = base + (PHYSCLUSTER - 1); 185 if (before != NULL) 186 *before = pindex - base; 187 if (after != NULL) 188 *after = end - pindex; 189 return (TRUE); 190} 191 192struct pagerops physpagerops = { 193 .pgo_init = phys_pager_init, 194 .pgo_alloc = phys_pager_alloc, 195 .pgo_dealloc = phys_pager_dealloc, 196 .pgo_getpages = phys_pager_getpages, 197 .pgo_putpages = phys_pager_putpages, 198 .pgo_haspage = phys_pager_haspage, 199}; 200