1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2009 Hudson River Trading LLC 5 * Written by: John H. Baldwin <jhb@FreeBSD.org> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 /* 34 * This pager manages OBJT_SG objects. These objects are backed by 35 * a scatter/gather list of physical address ranges. 36 */ 37 38 #include <sys/param.h> 39 #include <sys/lock.h> 40 #include <sys/mutex.h> 41 #include <sys/rwlock.h> 42 #include <sys/sglist.h> 43 #include <sys/vmmeter.h> 44 45 #include <vm/vm.h> 46 #include <vm/vm_param.h> 47 #include <vm/vm_object.h> 48 #include <vm/vm_page.h> 49 #include <vm/vm_pager.h> 50 #include <vm/vm_phys.h> 51 #include <vm/uma.h> 52 53 static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 54 vm_ooffset_t, struct ucred *); 55 static void sg_pager_dealloc(vm_object_t); 56 static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); 57 static void sg_pager_putpages(vm_object_t, vm_page_t *, int, 58 boolean_t, int *); 59 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 60 int *); 61 62 struct pagerops sgpagerops = { 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 70 static vm_object_t 71 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 72 vm_ooffset_t foff, struct ucred *cred) 73 { 74 struct sglist *sg; 75 vm_object_t object; 76 vm_pindex_t npages, pindex; 77 int i; 78 79 /* 80 * Offset should be page aligned. 81 */ 82 if (foff & PAGE_MASK) 83 return (NULL); 84 85 /* 86 * The scatter/gather list must only include page-aligned 87 * ranges. 88 */ 89 npages = 0; 90 sg = handle; 91 for (i = 0; i < sg->sg_nseg; i++) { 92 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 93 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 94 return (NULL); 95 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 96 } 97 98 /* 99 * The scatter/gather list has a fixed size. Refuse requests 100 * to map beyond that. 101 */ 102 size = round_page(size); 103 pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size); 104 if (pindex > npages || pindex < OFF_TO_IDX(foff) || 105 pindex < OFF_TO_IDX(size)) 106 return (NULL); 107 108 /* 109 * Allocate a new object and associate it with the 110 * scatter/gather list. It is ok for our purposes to have 111 * multiple VM objects associated with the same scatter/gather 112 * list because scatter/gather lists are static. This is also 113 * simpler than ensuring a unique object per scatter/gather 114 * list. 115 */ 116 object = vm_object_allocate(OBJT_SG, npages); 117 object->handle = sglist_hold(sg); 118 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 119 return (object); 120 } 121 122 static void 123 sg_pager_dealloc(vm_object_t object) 124 { 125 struct sglist *sg; 126 vm_page_t m; 127 128 /* 129 * Free up our fake pages. 130 */ 131 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 132 if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0) 133 continue; 134 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 135 vm_page_putfake(m); 136 } 137 138 sg = object->handle; 139 sglist_free(sg); 140 object->handle = NULL; 141 object->type = OBJT_DEAD; 142 } 143 144 static int 145 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 146 int *rahead) 147 { 148 struct sglist *sg; 149 vm_page_t m_paddr, page; 150 vm_pindex_t offset; 151 vm_paddr_t paddr; 152 vm_memattr_t memattr; 153 size_t space; 154 int i; 155 156 /* Since our haspage reports zero after/before, the count is 1. */ 157 KASSERT(count == 1, ("%s: count %d", __func__, count)); 158 /* Handle is stable while paging is in progress. */ 159 sg = object->handle; 160 memattr = object->memattr; 161 offset = m[0]->pindex; 162 163 /* 164 * Lookup the physical address of the requested page. An initial 165 * value of '1' instead of '0' is used so we can assert that the 166 * page is found since '0' can be a valid page-aligned physical 167 * address. 168 */ 169 space = 0; 170 paddr = 1; 171 for (i = 0; i < sg->sg_nseg; i++) { 172 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 173 space += sg->sg_segs[i].ss_len; 174 continue; 175 } 176 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 177 break; 178 } 179 KASSERT(paddr != 1, ("invalid SG page index")); 180 181 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 182 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 183 pmap_page_get_memattr(m_paddr) != memattr) { 184 memattr = pmap_page_get_memattr(m_paddr); 185 printf( 186 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 187 } 188 189 /* Return a fake page for the requested page. */ 190 KASSERT(!(m[0]->flags & PG_FICTITIOUS), 191 ("backing page for SG is fake")); 192 193 /* Construct a new fake page. */ 194 page = vm_page_getfake(paddr, memattr); 195 VM_OBJECT_WLOCK(object); 196 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 197 vm_page_replace(page, object, offset, m[0]); 198 VM_OBJECT_WUNLOCK(object); 199 m[0] = page; 200 vm_page_valid(page); 201 202 if (rbehind) 203 *rbehind = 0; 204 if (rahead) 205 *rahead = 0; 206 207 return (VM_PAGER_OK); 208 } 209 210 static void 211 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 212 boolean_t sync, int *rtvals) 213 { 214 215 panic("sg_pager_putpage called"); 216 } 217 218 static boolean_t 219 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 220 int *after) 221 { 222 223 if (before != NULL) 224 *before = 0; 225 if (after != NULL) 226 *after = 0; 227 return (TRUE); 228 } 229