sg_pager.c revision 196637
1/*- 2 * Copyright (c) 2009 Advanced Computing Technologies 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: head/sys/vm/sg_pager.c 196637 2009-08-29 02:17:40Z 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/sglist.h> 40#include <vm/vm.h> 41#include <vm/vm_object.h> 42#include <vm/vm_page.h> 43#include <vm/vm_pager.h> 44#include <vm/uma.h> 45 46static void sg_pager_init(void); 47static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 48 vm_ooffset_t, struct ucred *); 49static void sg_pager_dealloc(vm_object_t); 50static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int); 51static void sg_pager_putpages(vm_object_t, vm_page_t *, int, 52 boolean_t, int *); 53static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 54 int *); 55 56static uma_zone_t fakepg_zone; 57 58static vm_page_t sg_pager_getfake(vm_paddr_t, vm_memattr_t); 59static void sg_pager_putfake(vm_page_t); 60 61struct pagerops sgpagerops = { 62 .pgo_init = sg_pager_init, 63 .pgo_alloc = sg_pager_alloc, 64 .pgo_dealloc = sg_pager_dealloc, 65 .pgo_getpages = sg_pager_getpages, 66 .pgo_putpages = sg_pager_putpages, 67 .pgo_haspage = sg_pager_haspage, 68}; 69 70static void 71sg_pager_init(void) 72{ 73 74 fakepg_zone = uma_zcreate("SG fakepg", sizeof(struct vm_page), 75 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 76 UMA_ZONE_NOFREE|UMA_ZONE_VM); 77} 78 79static vm_object_t 80sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 81 vm_ooffset_t foff, struct ucred *cred) 82{ 83 struct sglist *sg; 84 vm_object_t object; 85 vm_pindex_t npages, pindex; 86 int i; 87 88 /* 89 * Offset should be page aligned. 90 */ 91 if (foff & PAGE_MASK) 92 return (NULL); 93 94 /* 95 * The scatter/gather list must only include page-aligned 96 * ranges. 97 */ 98 npages = 0; 99 sg = handle; 100 for (i = 0; i < sg->sg_nseg; i++) { 101 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 102 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 103 return (NULL); 104 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 105 } 106 107 /* 108 * The scatter/gather list has a fixed size. Refuse requests 109 * to map beyond that. 110 */ 111 size = round_page(size); 112 pindex = OFF_TO_IDX(foff + size); 113 if (pindex > npages) 114 return (NULL); 115 116 /* 117 * Allocate a new object and associate it with the 118 * scatter/gather list. It is ok for our purposes to have 119 * multiple VM objects associated with the same scatter/gather 120 * list because scatter/gather lists are static. This is also 121 * simpler than ensuring a unique object per scatter/gather 122 * list. 123 */ 124 object = vm_object_allocate(OBJT_SG, npages); 125 object->handle = sglist_hold(sg); 126 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 127 return (object); 128} 129 130static void 131sg_pager_dealloc(vm_object_t object) 132{ 133 struct sglist *sg; 134 vm_page_t m; 135 136 /* 137 * Free up our fake pages. 138 */ 139 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 140 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, pageq); 141 sg_pager_putfake(m); 142 } 143 144 sg = object->handle; 145 sglist_free(sg); 146} 147 148static int 149sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 150{ 151 struct sglist *sg; 152 vm_page_t m_paddr, page; 153 vm_pindex_t offset; 154 vm_paddr_t paddr; 155 vm_memattr_t memattr; 156 size_t space; 157 int i; 158 159 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 160 sg = object->handle; 161 memattr = object->memattr; 162 VM_OBJECT_UNLOCK(object); 163 offset = m[reqpage]->pindex; 164 165 /* 166 * Lookup the physical address of the requested page. An initial 167 * value of '1' instead of '0' is used so we can assert that the 168 * page is found since '0' can be a valid page-aligned physical 169 * address. 170 */ 171 space = 0; 172 paddr = 1; 173 for (i = 0; i < sg->sg_nseg; i++) { 174 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 175 space += sg->sg_segs[i].ss_len; 176 continue; 177 } 178 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 179 break; 180 } 181 KASSERT(paddr != 1, ("invalid SG page index")); 182 183 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 184 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 185 pmap_page_get_memattr(m_paddr) != memattr) { 186 memattr = pmap_page_get_memattr(m_paddr); 187 printf( 188 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 189 } 190 191 /* Return a fake page for the requested page. */ 192 KASSERT(!(m[reqpage]->flags & PG_FICTITIOUS), 193 ("backing page for SG is fake")); 194 195 /* Construct a new fake page. */ 196 page = sg_pager_getfake(paddr, memattr); 197 VM_OBJECT_LOCK(object); 198 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, pageq); 199 200 /* Free the original pages and insert this fake page into the object. */ 201 vm_page_lock_queues(); 202 for (i = 0; i < count; i++) 203 vm_page_free(m[i]); 204 vm_page_unlock_queues(); 205 vm_page_insert(page, object, offset); 206 m[reqpage] = page; 207 page->valid = VM_PAGE_BITS_ALL; 208 209 return (VM_PAGER_OK); 210} 211 212static void 213sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 214 boolean_t sync, int *rtvals) 215{ 216 217 panic("sg_pager_putpage called"); 218} 219 220static boolean_t 221sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 222 int *after) 223{ 224 225 if (before != NULL) 226 *before = 0; 227 if (after != NULL) 228 *after = 0; 229 return (TRUE); 230} 231 232/* 233 * Create a fictitious page with the specified physical address and memory 234 * attribute. The memory attribute is the only the machine-dependent aspect 235 * of a fictitious page that must be initialized. 236 */ 237static vm_page_t 238sg_pager_getfake(vm_paddr_t paddr, vm_memattr_t memattr) 239{ 240 vm_page_t m; 241 242 m = uma_zalloc(fakepg_zone, M_WAITOK | M_ZERO); 243 m->phys_addr = paddr; 244 /* Fictitious pages don't use "segind". */ 245 m->flags = PG_FICTITIOUS; 246 /* Fictitious pages don't use "order" or "pool". */ 247 m->oflags = VPO_BUSY; 248 m->wire_count = 1; 249 pmap_page_set_memattr(m, memattr); 250 return (m); 251} 252 253static void 254sg_pager_putfake(vm_page_t m) 255{ 256 257 if (!(m->flags & PG_FICTITIOUS)) 258 panic("sg_pager_putfake: bad page"); 259 uma_zfree(fakepg_zone, m); 260} 261