phys_pager.c revision 107989
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 * $FreeBSD: head/sys/vm/phys_pager.c 107989 2002-12-17 19:55:28Z alc $ 26 */ 27 28#include <sys/param.h> 29#include <sys/systm.h> 30#include <sys/linker_set.h> 31#include <sys/conf.h> 32#include <sys/kernel.h> 33#include <sys/lock.h> 34#include <sys/proc.h> 35#include <sys/mutex.h> 36#include <sys/mman.h> 37#include <sys/sysctl.h> 38 39#include <vm/vm.h> 40#include <vm/vm_object.h> 41#include <vm/vm_page.h> 42#include <vm/vm_pager.h> 43 44/* prevent concurrant creation races */ 45static int phys_pager_alloc_lock; 46/* list of device pager objects */ 47static struct pagerlst phys_pager_object_list; 48/* protect access to phys_pager_object_list */ 49static struct mtx phys_pager_mtx; 50 51static void 52phys_pager_init(void) 53{ 54 55 TAILQ_INIT(&phys_pager_object_list); 56 mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF); 57} 58 59/* 60 * MPSAFE 61 */ 62static vm_object_t 63phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 64 vm_ooffset_t foff) 65{ 66 vm_object_t object; 67 68 /* 69 * Offset should be page aligned. 70 */ 71 if (foff & PAGE_MASK) 72 return (NULL); 73 74 size = round_page(size); 75 76 if (handle != NULL) { 77 mtx_lock(&Giant); 78 /* 79 * Lock to prevent object creation race condition. 80 */ 81 while (phys_pager_alloc_lock) { 82 phys_pager_alloc_lock = -1; 83 tsleep(&phys_pager_alloc_lock, PVM, "swpalc", 0); 84 } 85 phys_pager_alloc_lock = 1; 86 87 /* 88 * Look up pager, creating as necessary. 89 */ 90 object = vm_pager_object_lookup(&phys_pager_object_list, handle); 91 if (object == NULL) { 92 /* 93 * Allocate object and associate it with the pager. 94 */ 95 object = vm_object_allocate(OBJT_PHYS, 96 OFF_TO_IDX(foff + size)); 97 object->handle = handle; 98 mtx_lock(&phys_pager_mtx); 99 TAILQ_INSERT_TAIL(&phys_pager_object_list, object, 100 pager_object_list); 101 mtx_unlock(&phys_pager_mtx); 102 } else { 103 /* 104 * Gain a reference to the object. 105 */ 106 vm_object_reference(object); 107 if (OFF_TO_IDX(foff + size) > object->size) 108 object->size = OFF_TO_IDX(foff + size); 109 } 110 if (phys_pager_alloc_lock == -1) 111 wakeup(&phys_pager_alloc_lock); 112 phys_pager_alloc_lock = 0; 113 mtx_unlock(&Giant); 114 } else { 115 object = vm_object_allocate(OBJT_PHYS, 116 OFF_TO_IDX(foff + size)); 117 } 118 119 return (object); 120} 121 122/* 123 * MPSAFE 124 */ 125static void 126phys_pager_dealloc(vm_object_t object) 127{ 128 129 if (object->handle != NULL) { 130 mtx_lock(&phys_pager_mtx); 131 TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list); 132 mtx_unlock(&phys_pager_mtx); 133 } 134} 135 136static int 137phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 138{ 139 int i, s; 140 141 s = splvm(); 142 /* 143 * Fill as many pages as vm_fault has allocated for us. 144 */ 145 for (i = 0; i < count; i++) { 146 if ((m[i]->flags & PG_ZERO) == 0) 147 pmap_zero_page(m[i]); 148 /* Switch off pv_entries */ 149 vm_page_lock_queues(); 150 vm_page_flag_set(m[i], PG_ZERO); 151 vm_page_unmanage(m[i]); 152 vm_page_unlock_queues(); 153 m[i]->valid = VM_PAGE_BITS_ALL; 154 m[i]->dirty = 0; 155 /* The requested page must remain busy, the others not. */ 156 if (reqpage != i) { 157 vm_page_flag_clear(m[i], PG_BUSY); 158 m[i]->busy = 0; 159 } 160 } 161 splx(s); 162 163 return (VM_PAGER_OK); 164} 165 166static void 167phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync, 168 int *rtvals) 169{ 170 171 panic("phys_pager_putpage called"); 172} 173 174/* 175 * Implement a pretty aggressive clustered getpages strategy. Hint that 176 * everything in an entire 4MB window should be prefaulted at once. 177 * 178 * XXX 4MB (1024 slots per page table page) is convenient for x86, 179 * but may not be for other arches. 180 */ 181#ifndef PHYSCLUSTER 182#define PHYSCLUSTER 1024 183#endif 184static boolean_t 185phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 186 int *after) 187{ 188 vm_pindex_t base, end; 189 190 base = pindex & (~(PHYSCLUSTER - 1)); 191 end = base + (PHYSCLUSTER - 1); 192 if (before != NULL) 193 *before = pindex - base; 194 if (after != NULL) 195 *after = end - pindex; 196 return (TRUE); 197} 198 199struct pagerops physpagerops = { 200 phys_pager_init, 201 phys_pager_alloc, 202 phys_pager_dealloc, 203 phys_pager_getpages, 204 phys_pager_putpages, 205 phys_pager_haspage, 206 NULL 207}; 208