sg_pager.c revision 283927
1/*- 2 * Copyright (c) 2009 Hudson River Trading LLC 3 * Written by: John H. Baldwin <jhb@FreeBSD.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD: stable/10/sys/vm/sg_pager.c 283927 2015-06-02 19:20:39Z jhb $"); 30 31/* 32 * This pager manages OBJT_SG objects. These objects are backed by 33 * a scatter/gather list of physical address ranges. 34 */ 35 36#include <sys/param.h> 37#include <sys/lock.h> 38#include <sys/mutex.h> 39#include <sys/rwlock.h> 40#include <sys/sglist.h> 41#include <vm/vm.h> 42#include <vm/vm_param.h> 43#include <vm/vm_object.h> 44#include <vm/vm_page.h> 45#include <vm/vm_pager.h> 46#include <vm/vm_phys.h> 47#include <vm/uma.h> 48 49static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 50 vm_ooffset_t, struct ucred *); 51static void sg_pager_dealloc(vm_object_t); 52static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int); 53static void sg_pager_putpages(vm_object_t, vm_page_t *, int, 54 boolean_t, int *); 55static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 56 int *); 57 58struct pagerops sgpagerops = { 59 .pgo_alloc = sg_pager_alloc, 60 .pgo_dealloc = sg_pager_dealloc, 61 .pgo_getpages = sg_pager_getpages, 62 .pgo_putpages = sg_pager_putpages, 63 .pgo_haspage = sg_pager_haspage, 64}; 65 66static vm_object_t 67sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 68 vm_ooffset_t foff, struct ucred *cred) 69{ 70 struct sglist *sg; 71 vm_object_t object; 72 vm_pindex_t npages, pindex; 73 int i; 74 75 /* 76 * Offset should be page aligned. 77 */ 78 if (foff & PAGE_MASK) 79 return (NULL); 80 81 /* 82 * The scatter/gather list must only include page-aligned 83 * ranges. 84 */ 85 npages = 0; 86 sg = handle; 87 for (i = 0; i < sg->sg_nseg; i++) { 88 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 89 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 90 return (NULL); 91 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 92 } 93 94 /* 95 * The scatter/gather list has a fixed size. Refuse requests 96 * to map beyond that. 97 */ 98 size = round_page(size); 99 pindex = OFF_TO_IDX(foff + size); 100 if (pindex > npages) 101 return (NULL); 102 103 /* 104 * Allocate a new object and associate it with the 105 * scatter/gather list. It is ok for our purposes to have 106 * multiple VM objects associated with the same scatter/gather 107 * list because scatter/gather lists are static. This is also 108 * simpler than ensuring a unique object per scatter/gather 109 * list. 110 */ 111 object = vm_object_allocate(OBJT_SG, npages); 112 object->handle = sglist_hold(sg); 113 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 114 return (object); 115} 116 117static void 118sg_pager_dealloc(vm_object_t object) 119{ 120 struct sglist *sg; 121 vm_page_t m; 122 123 /* 124 * Free up our fake pages. 125 */ 126 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 127 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 128 vm_page_putfake(m); 129 } 130 131 sg = object->handle; 132 sglist_free(sg); 133} 134 135static int 136sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 137{ 138 struct sglist *sg; 139 vm_page_t m_paddr, page; 140 vm_pindex_t offset; 141 vm_paddr_t paddr; 142 vm_memattr_t memattr; 143 size_t space; 144 int i; 145 146 VM_OBJECT_ASSERT_WLOCKED(object); 147 sg = object->handle; 148 memattr = object->memattr; 149 VM_OBJECT_WUNLOCK(object); 150 offset = m[reqpage]->pindex; 151 152 /* 153 * Lookup the physical address of the requested page. An initial 154 * value of '1' instead of '0' is used so we can assert that the 155 * page is found since '0' can be a valid page-aligned physical 156 * address. 157 */ 158 space = 0; 159 paddr = 1; 160 for (i = 0; i < sg->sg_nseg; i++) { 161 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 162 space += sg->sg_segs[i].ss_len; 163 continue; 164 } 165 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 166 break; 167 } 168 KASSERT(paddr != 1, ("invalid SG page index")); 169 170 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 171 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 172 pmap_page_get_memattr(m_paddr) != memattr) { 173 memattr = pmap_page_get_memattr(m_paddr); 174 printf( 175 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 176 } 177 178 /* Return a fake page for the requested page. */ 179 KASSERT(!(m[reqpage]->flags & PG_FICTITIOUS), 180 ("backing page for SG is fake")); 181 182 /* Construct a new fake page. */ 183 page = vm_page_getfake(paddr, memattr); 184 VM_OBJECT_WLOCK(object); 185 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 186 187 /* Free the original pages and insert this fake page into the object. */ 188 for (i = 0; i < count; i++) { 189 if (i == reqpage && 190 vm_page_replace(page, object, offset) != m[i]) 191 panic("sg_pager_getpages: invalid place replacement"); 192 vm_page_lock(m[i]); 193 vm_page_free(m[i]); 194 vm_page_unlock(m[i]); 195 } 196 m[reqpage] = page; 197 page->valid = VM_PAGE_BITS_ALL; 198 199 return (VM_PAGER_OK); 200} 201 202static void 203sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 204 boolean_t sync, int *rtvals) 205{ 206 207 panic("sg_pager_putpage called"); 208} 209 210static boolean_t 211sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 212 int *after) 213{ 214 215 if (before != NULL) 216 *before = 0; 217 if (after != NULL) 218 *after = 0; 219 return (TRUE); 220} 221