1 /*- 2 * Copyright (c) 2009 Hudson River Trading 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("$FreeBSD$"); 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/rwlock.h> 40 #include <sys/sglist.h> 41 #include <vm/vm.h> 42 #include <vm/vm_param.h> 43 #include <vm/vm_object.h> 44 #include <vm/vm_page.h> 45 #include <vm/vm_pager.h> 46 #include <vm/vm_phys.h> 47 #include <vm/uma.h> 48 49 static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 50 vm_ooffset_t, struct ucred *); 51 static void sg_pager_dealloc(vm_object_t); 52 static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); 53 static void sg_pager_putpages(vm_object_t, vm_page_t *, int, 54 boolean_t, int *); 55 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 56 int *); 57 58 struct pagerops sgpagerops = { 59 .pgo_alloc = sg_pager_alloc, 60 .pgo_dealloc = sg_pager_dealloc, 61 .pgo_getpages = sg_pager_getpages, 62 .pgo_putpages = sg_pager_putpages, 63 .pgo_haspage = sg_pager_haspage, 64 }; 65 66 static vm_object_t 67 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 68 vm_ooffset_t foff, struct ucred *cred) 69 { 70 struct sglist *sg; 71 vm_object_t object; 72 vm_pindex_t npages, pindex; 73 int i; 74 75 /* 76 * Offset should be page aligned. 77 */ 78 if (foff & PAGE_MASK) 79 return (NULL); 80 81 /* 82 * The scatter/gather list must only include page-aligned 83 * ranges. 84 */ 85 npages = 0; 86 sg = handle; 87 for (i = 0; i < sg->sg_nseg; i++) { 88 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 89 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 90 return (NULL); 91 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 92 } 93 94 /* 95 * The scatter/gather list has a fixed size. Refuse requests 96 * to map beyond that. 97 */ 98 size = round_page(size); 99 pindex = UOFF_TO_IDX(foff) + UOFF_TO_IDX(size); 100 if (pindex > npages || pindex < UOFF_TO_IDX(foff) || 101 pindex < UOFF_TO_IDX(size)) 102 return (NULL); 103 104 /* 105 * Allocate a new object and associate it with the 106 * scatter/gather list. It is ok for our purposes to have 107 * multiple VM objects associated with the same scatter/gather 108 * list because scatter/gather lists are static. This is also 109 * simpler than ensuring a unique object per scatter/gather 110 * list. 111 */ 112 object = vm_object_allocate(OBJT_SG, npages); 113 object->handle = sglist_hold(sg); 114 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 115 return (object); 116 } 117 118 static void 119 sg_pager_dealloc(vm_object_t object) 120 { 121 struct sglist *sg; 122 vm_page_t m; 123 124 /* 125 * Free up our fake pages. 126 */ 127 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 128 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 129 vm_page_putfake(m); 130 } 131 132 sg = object->handle; 133 sglist_free(sg); 134 object->handle = NULL; 135 object->type = OBJT_DEAD; 136 } 137 138 static int 139 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 140 int *rahead) 141 { 142 struct sglist *sg; 143 vm_page_t m_paddr, page; 144 vm_pindex_t offset; 145 vm_paddr_t paddr; 146 vm_memattr_t memattr; 147 size_t space; 148 int i; 149 150 /* Since our haspage reports zero after/before, the count is 1. */ 151 KASSERT(count == 1, ("%s: count %d", __func__, count)); 152 VM_OBJECT_ASSERT_WLOCKED(object); 153 sg = object->handle; 154 memattr = object->memattr; 155 VM_OBJECT_WUNLOCK(object); 156 offset = m[0]->pindex; 157 158 /* 159 * Lookup the physical address of the requested page. An initial 160 * value of '1' instead of '0' is used so we can assert that the 161 * page is found since '0' can be a valid page-aligned physical 162 * address. 163 */ 164 space = 0; 165 paddr = 1; 166 for (i = 0; i < sg->sg_nseg; i++) { 167 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 168 space += sg->sg_segs[i].ss_len; 169 continue; 170 } 171 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 172 break; 173 } 174 KASSERT(paddr != 1, ("invalid SG page index")); 175 176 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 177 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 178 pmap_page_get_memattr(m_paddr) != memattr) { 179 memattr = pmap_page_get_memattr(m_paddr); 180 printf( 181 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 182 } 183 184 /* Return a fake page for the requested page. */ 185 KASSERT(!(m[0]->flags & PG_FICTITIOUS), 186 ("backing page for SG is fake")); 187 188 /* Construct a new fake page. */ 189 page = vm_page_getfake(paddr, memattr); 190 VM_OBJECT_WLOCK(object); 191 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 192 vm_page_replace_checked(page, object, offset, m[0]); 193 vm_page_lock(m[0]); 194 vm_page_free(m[0]); 195 vm_page_unlock(m[0]); 196 m[0] = page; 197 page->valid = VM_PAGE_BITS_ALL; 198 199 if (rbehind) 200 *rbehind = 0; 201 if (rahead) 202 *rahead = 0; 203 204 return (VM_PAGER_OK); 205 } 206 207 static void 208 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 209 boolean_t sync, int *rtvals) 210 { 211 212 panic("sg_pager_putpage called"); 213 } 214 215 static boolean_t 216 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 217 int *after) 218 { 219 220 if (before != NULL) 221 *before = 0; 222 if (after != NULL) 223 *after = 0; 224 return (TRUE); 225 } 226