1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 /* 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/event.h> 38 #include <sys/lock.h> 39 #include <sys/mutex.h> 40 #include <sys/rwlock.h> 41 #include <sys/sglist.h> 42 #include <sys/user.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 int, int *); 59 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 60 int *); 61 62 const struct pagerops sgpagerops = { 63 .pgo_kvme_type = KVME_TYPE_SG, 64 .pgo_alloc = sg_pager_alloc, 65 .pgo_dealloc = sg_pager_dealloc, 66 .pgo_getpages = sg_pager_getpages, 67 .pgo_putpages = sg_pager_putpages, 68 .pgo_haspage = sg_pager_haspage, 69 }; 70 71 static vm_object_t 72 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 73 vm_ooffset_t foff, struct ucred *cred) 74 { 75 struct sglist *sg; 76 vm_object_t object; 77 vm_pindex_t npages, pindex; 78 int i; 79 80 /* 81 * Offset should be page aligned. 82 */ 83 if (foff & PAGE_MASK) 84 return (NULL); 85 86 /* 87 * The scatter/gather list must only include page-aligned 88 * ranges. 89 */ 90 npages = 0; 91 sg = handle; 92 for (i = 0; i < sg->sg_nseg; i++) { 93 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 94 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 95 return (NULL); 96 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 97 } 98 99 /* 100 * The scatter/gather list has a fixed size. Refuse requests 101 * to map beyond that. 102 */ 103 size = round_page(size); 104 pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size); 105 if (pindex > npages || pindex < OFF_TO_IDX(foff) || 106 pindex < OFF_TO_IDX(size)) 107 return (NULL); 108 109 /* 110 * Allocate a new object and associate it with the 111 * scatter/gather list. It is ok for our purposes to have 112 * multiple VM objects associated with the same scatter/gather 113 * list because scatter/gather lists are static. This is also 114 * simpler than ensuring a unique object per scatter/gather 115 * list. 116 */ 117 object = vm_object_allocate(OBJT_SG, npages); 118 object->handle = sglist_hold(sg); 119 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 120 return (object); 121 } 122 123 static void 124 sg_pager_dealloc(vm_object_t object) 125 { 126 struct sglist *sg; 127 vm_page_t m; 128 129 /* 130 * Free up our fake pages. 131 */ 132 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 133 if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0) 134 continue; 135 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 136 vm_page_putfake(m); 137 } 138 139 sg = object->handle; 140 sglist_free(sg); 141 object->handle = NULL; 142 object->type = OBJT_DEAD; 143 } 144 145 static int 146 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 147 int *rahead) 148 { 149 struct sglist *sg; 150 vm_page_t m_paddr, page; 151 vm_pindex_t offset; 152 vm_paddr_t paddr; 153 vm_memattr_t memattr; 154 size_t space; 155 int i; 156 157 /* Since our haspage reports zero after/before, the count is 1. */ 158 KASSERT(count == 1, ("%s: count %d", __func__, count)); 159 /* Handle is stable while paging is in progress. */ 160 sg = object->handle; 161 memattr = object->memattr; 162 offset = m[0]->pindex; 163 164 /* 165 * Lookup the physical address of the requested page. An initial 166 * value of '1' instead of '0' is used so we can assert that the 167 * page is found since '0' can be a valid page-aligned physical 168 * address. 169 */ 170 space = 0; 171 paddr = 1; 172 for (i = 0; i < sg->sg_nseg; i++) { 173 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 174 space += sg->sg_segs[i].ss_len; 175 continue; 176 } 177 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 178 break; 179 } 180 KASSERT(paddr != 1, ("invalid SG page index")); 181 182 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 183 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 184 pmap_page_get_memattr(m_paddr) != memattr) { 185 memattr = pmap_page_get_memattr(m_paddr); 186 printf( 187 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 188 } 189 190 /* Return a fake page for the requested page. */ 191 KASSERT(!(m[0]->flags & PG_FICTITIOUS), 192 ("backing page for SG is fake")); 193 194 /* Construct a new fake page. */ 195 page = vm_page_getfake(paddr, memattr); 196 VM_OBJECT_WLOCK(object); 197 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 198 vm_page_replace(page, object, offset, m[0]); 199 VM_OBJECT_WUNLOCK(object); 200 m[0] = page; 201 vm_page_valid(page); 202 203 if (rbehind) 204 *rbehind = 0; 205 if (rahead) 206 *rahead = 0; 207 208 return (VM_PAGER_OK); 209 } 210 211 static void 212 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 213 int flags, int *rtvals) 214 { 215 216 panic("sg_pager_putpage called"); 217 } 218 219 static boolean_t 220 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 221 int *after) 222 { 223 224 if (before != NULL) 225 *before = 0; 226 if (after != NULL) 227 *after = 0; 228 return (TRUE); 229 } 230