1 /* $NetBSD: uvm_page_status.c,v 1.6 2020/08/14 09:06:15 chs Exp $ */ 2 3 /*- 4 * Copyright (c)2011 YAMAMOTO Takashi, 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 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: uvm_page_status.c,v 1.6 2020/08/14 09:06:15 chs Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 35 #include <uvm/uvm.h> 36 37 /* 38 * page dirtiness status tracking 39 * 40 * separated from uvm_page.c mainly for rump 41 */ 42 43 /* 44 * these constants are chosen to match so that we can convert between 45 * them quickly. 46 */ 47 48 __CTASSERT(UVM_PAGE_STATUS_UNKNOWN == 0); 49 __CTASSERT(UVM_PAGE_STATUS_DIRTY == PG_DIRTY); 50 __CTASSERT(UVM_PAGE_STATUS_CLEAN == PG_CLEAN); 51 52 /* 53 * uvm_pagegetdirty: return the dirtiness status (one of UVM_PAGE_STATUS_ 54 * values) of the page. 55 * 56 * called with the owner locked. 57 */ 58 59 unsigned int 60 uvm_pagegetdirty(struct vm_page *pg) 61 { 62 struct uvm_object * const uobj __diagused = pg->uobject; 63 64 KASSERT((~pg->flags & (PG_CLEAN|PG_DIRTY)) != 0); 65 KASSERT(uvm_page_owner_locked_p(pg, false)); 66 KASSERT(uobj == NULL || ((pg->flags & PG_CLEAN) == 0) == 67 uvm_obj_page_dirty_p(pg)); 68 return pg->flags & (PG_CLEAN|PG_DIRTY); 69 } 70 71 /* 72 * uvm_pagemarkdirty: set the dirtiness status (one of UVM_PAGE_STATUS_ values) 73 * of the page. 74 * 75 * called with the owner locked. 76 * 77 * update the radix tree tag for object-owned page. 78 * 79 * if new status is UVM_PAGE_STATUS_UNKNOWN, clear pmap-level dirty bit 80 * so that later uvm_pagecheckdirty() can notice modifications on the page. 81 */ 82 83 void 84 uvm_pagemarkdirty(struct vm_page *pg, unsigned int newstatus) 85 { 86 struct uvm_object * const uobj = pg->uobject; 87 const unsigned int oldstatus = uvm_pagegetdirty(pg); 88 enum cpu_count base; 89 90 KASSERT((~newstatus & (PG_CLEAN|PG_DIRTY)) != 0); 91 KASSERT((newstatus & ~(PG_CLEAN|PG_DIRTY)) == 0); 92 KASSERT(uvm_page_owner_locked_p(pg, true)); 93 KASSERT(uobj == NULL || ((pg->flags & PG_CLEAN) == 0) == 94 uvm_obj_page_dirty_p(pg)); 95 96 if (oldstatus == newstatus) { 97 return; 98 } 99 100 /* 101 * set UVM_PAGE_DIRTY_TAG tag unless known CLEAN so that putpages can 102 * find possibly-dirty pages quickly. 103 */ 104 105 if (uobj != NULL) { 106 if (newstatus == UVM_PAGE_STATUS_CLEAN) { 107 uvm_obj_page_clear_dirty(pg); 108 } else if (oldstatus == UVM_PAGE_STATUS_CLEAN) { 109 /* 110 * on first dirty page, mark the object dirty. 111 * for vnodes this inserts to the syncer worklist. 112 */ 113 if (uvm_obj_clean_p(uobj) && 114 uobj->pgops->pgo_markdirty != NULL) { 115 (*uobj->pgops->pgo_markdirty)(uobj); 116 } 117 uvm_obj_page_set_dirty(pg); 118 } 119 } 120 if (newstatus == UVM_PAGE_STATUS_UNKNOWN) { 121 /* 122 * start relying on pmap-level dirtiness tracking. 123 */ 124 pmap_clear_modify(pg); 125 } 126 pg->flags &= ~(PG_CLEAN|PG_DIRTY); 127 pg->flags |= newstatus; 128 KASSERT(uobj == NULL || ((pg->flags & PG_CLEAN) == 0) == 129 uvm_obj_page_dirty_p(pg)); 130 if ((pg->flags & PG_STAT) != 0) { 131 if ((pg->flags & PG_SWAPBACKED) != 0) { 132 base = CPU_COUNT_ANONUNKNOWN; 133 } else { 134 base = CPU_COUNT_FILEUNKNOWN; 135 } 136 kpreempt_disable(); 137 CPU_COUNT(base + oldstatus, -1); 138 CPU_COUNT(base + newstatus, +1); 139 kpreempt_enable(); 140 } 141 } 142 143 /* 144 * uvm_pagecheckdirty: check if page is dirty, and remove its dirty bit. 145 * 146 * called with the owner locked. 147 * 148 * returns if the page was dirty. 149 * 150 * if protected is true, mark the page CLEAN. otherwise, mark the page UNKNOWN. 151 * ("mark" in the sense of uvm_pagemarkdirty().) 152 */ 153 154 bool 155 uvm_pagecheckdirty(struct vm_page *pg, bool pgprotected) 156 { 157 const unsigned int oldstatus = uvm_pagegetdirty(pg); 158 bool modified; 159 160 KASSERT(uvm_page_owner_locked_p(pg, true)); 161 162 /* 163 * if pgprotected is true, mark the page CLEAN. 164 * otherwise mark the page UNKNOWN unless it's CLEAN. 165 * 166 * possible transitions: 167 * 168 * CLEAN -> CLEAN , modified = false 169 * UNKNOWN -> UNKNOWN, modified = true 170 * UNKNOWN -> UNKNOWN, modified = false 171 * UNKNOWN -> CLEAN , modified = true 172 * UNKNOWN -> CLEAN , modified = false 173 * DIRTY -> UNKNOWN, modified = true 174 * DIRTY -> CLEAN , modified = true 175 * 176 * pmap_clear_modify is necessary if either of 177 * oldstatus or newstatus is UVM_PAGE_STATUS_UNKNOWN. 178 */ 179 180 if (oldstatus == UVM_PAGE_STATUS_CLEAN) { 181 modified = false; 182 } else { 183 const unsigned int newstatus = pgprotected ? 184 UVM_PAGE_STATUS_CLEAN : UVM_PAGE_STATUS_UNKNOWN; 185 186 if (oldstatus == UVM_PAGE_STATUS_DIRTY) { 187 modified = true; 188 if (newstatus == UVM_PAGE_STATUS_UNKNOWN) { 189 pmap_clear_modify(pg); 190 } 191 } else { 192 KASSERT(oldstatus == UVM_PAGE_STATUS_UNKNOWN); 193 modified = pmap_clear_modify(pg); 194 } 195 uvm_pagemarkdirty(pg, newstatus); 196 } 197 return modified; 198 } 199
Indexes created Sat Sep 20 22:09:52 GMT 2025