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 = UOFF_TO_IDX(foff) + UOFF_TO_IDX(size); 104 if (pindex > npages || pindex < UOFF_TO_IDX(foff) || 105 pindex < UOFF_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 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 133 vm_page_putfake(m); 134 } 135 136 sg = object->handle; 137 sglist_free(sg); 138 object->handle = NULL; 139 object->type = OBJT_DEAD; 140 } 141 142 static int 143 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 144 int *rahead) 145 { 146 struct sglist *sg; 147 vm_page_t m_paddr, page; 148 vm_pindex_t offset; 149 vm_paddr_t paddr; 150 vm_memattr_t memattr; 151 size_t space; 152 int i; 153 154 /* Since our haspage reports zero after/before, the count is 1. */ 155 KASSERT(count == 1, ("%s: count %d", __func__, count)); 156 VM_OBJECT_ASSERT_WLOCKED(object); 157 sg = object->handle; 158 memattr = object->memattr; 159 VM_OBJECT_WUNLOCK(object); 160 offset = m[0]->pindex; 161 162 /* 163 * Lookup the physical address of the requested page. An initial 164 * value of '1' instead of '0' is used so we can assert that the 165 * page is found since '0' can be a valid page-aligned physical 166 * address. 167 */ 168 space = 0; 169 paddr = 1; 170 for (i = 0; i < sg->sg_nseg; i++) { 171 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 172 space += sg->sg_segs[i].ss_len; 173 continue; 174 } 175 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 176 break; 177 } 178 KASSERT(paddr != 1, ("invalid SG page index")); 179 180 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 181 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 182 pmap_page_get_memattr(m_paddr) != memattr) { 183 memattr = pmap_page_get_memattr(m_paddr); 184 printf( 185 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 186 } 187 188 /* Return a fake page for the requested page. */ 189 KASSERT(!(m[0]->flags & PG_FICTITIOUS), 190 ("backing page for SG is fake")); 191 192 /* Construct a new fake page. */ 193 page = vm_page_getfake(paddr, memattr); 194 VM_OBJECT_WLOCK(object); 195 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 196 vm_page_replace_checked(page, object, offset, m[0]); 197 vm_page_lock(m[0]); 198 vm_page_free(m[0]); 199 vm_page_unlock(m[0]); 200 m[0] = page; 201 page->valid = VM_PAGE_BITS_ALL; 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 boolean_t sync, 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