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 __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/user.h> 44 #include <sys/vmmeter.h> 45 46 #include <vm/vm.h> 47 #include <vm/vm_param.h> 48 #include <vm/vm_object.h> 49 #include <vm/vm_page.h> 50 #include <vm/vm_pager.h> 51 #include <vm/vm_phys.h> 52 #include <vm/uma.h> 53 54 static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 55 vm_ooffset_t, struct ucred *); 56 static void sg_pager_dealloc(vm_object_t); 57 static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); 58 static void sg_pager_putpages(vm_object_t, vm_page_t *, int, 59 int, int *); 60 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 61 int *); 62 63 const struct pagerops sgpagerops = { 64 .pgo_kvme_type = KVME_TYPE_SG, 65 .pgo_alloc = sg_pager_alloc, 66 .pgo_dealloc = sg_pager_dealloc, 67 .pgo_getpages = sg_pager_getpages, 68 .pgo_putpages = sg_pager_putpages, 69 .pgo_haspage = sg_pager_haspage, 70 }; 71 72 static vm_object_t 73 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 74 vm_ooffset_t foff, struct ucred *cred) 75 { 76 struct sglist *sg; 77 vm_object_t object; 78 vm_pindex_t npages, pindex; 79 int i; 80 81 /* 82 * Offset should be page aligned. 83 */ 84 if (foff & PAGE_MASK) 85 return (NULL); 86 87 /* 88 * The scatter/gather list must only include page-aligned 89 * ranges. 90 */ 91 npages = 0; 92 sg = handle; 93 for (i = 0; i < sg->sg_nseg; i++) { 94 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 95 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 96 return (NULL); 97 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 98 } 99 100 /* 101 * The scatter/gather list has a fixed size. Refuse requests 102 * to map beyond that. 103 */ 104 size = round_page(size); 105 pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size); 106 if (pindex > npages || pindex < OFF_TO_IDX(foff) || 107 pindex < OFF_TO_IDX(size)) 108 return (NULL); 109 110 /* 111 * Allocate a new object and associate it with the 112 * scatter/gather list. It is ok for our purposes to have 113 * multiple VM objects associated with the same scatter/gather 114 * list because scatter/gather lists are static. This is also 115 * simpler than ensuring a unique object per scatter/gather 116 * list. 117 */ 118 object = vm_object_allocate(OBJT_SG, npages); 119 object->handle = sglist_hold(sg); 120 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 121 return (object); 122 } 123 124 static void 125 sg_pager_dealloc(vm_object_t object) 126 { 127 struct sglist *sg; 128 vm_page_t m; 129 130 /* 131 * Free up our fake pages. 132 */ 133 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 134 if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0) 135 continue; 136 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 137 vm_page_putfake(m); 138 } 139 140 sg = object->handle; 141 sglist_free(sg); 142 object->handle = NULL; 143 object->type = OBJT_DEAD; 144 } 145 146 static int 147 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 148 int *rahead) 149 { 150 struct sglist *sg; 151 vm_page_t m_paddr, page; 152 vm_pindex_t offset; 153 vm_paddr_t paddr; 154 vm_memattr_t memattr; 155 size_t space; 156 int i; 157 158 /* Since our haspage reports zero after/before, the count is 1. */ 159 KASSERT(count == 1, ("%s: count %d", __func__, count)); 160 /* Handle is stable while paging is in progress. */ 161 sg = object->handle; 162 memattr = object->memattr; 163 offset = m[0]->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[0]->flags & PG_FICTITIOUS), 193 ("backing page for SG is fake")); 194 195 /* Construct a new fake page. */ 196 page = vm_page_getfake(paddr, memattr); 197 VM_OBJECT_WLOCK(object); 198 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 199 vm_page_replace(page, object, offset, m[0]); 200 VM_OBJECT_WUNLOCK(object); 201 m[0] = page; 202 vm_page_valid(page); 203 204 if (rbehind) 205 *rbehind = 0; 206 if (rahead) 207 *rahead = 0; 208 209 return (VM_PAGER_OK); 210 } 211 212 static void 213 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 214 int flags, int *rtvals) 215 { 216 217 panic("sg_pager_putpage called"); 218 } 219 220 static boolean_t 221 sg_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