sg_pager.c revision 331017
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: stable/11/sys/vm/sg_pager.c 331017 2018-03-15 19:08:33Z kevans $"); 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 <sys/vmmeter.h> 42 43#include <vm/vm.h> 44#include <vm/vm_param.h> 45#include <vm/vm_object.h> 46#include <vm/vm_page.h> 47#include <vm/vm_pager.h> 48#include <vm/vm_phys.h> 49#include <vm/uma.h> 50 51static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 52 vm_ooffset_t, struct ucred *); 53static void sg_pager_dealloc(vm_object_t); 54static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *); 55static void sg_pager_putpages(vm_object_t, vm_page_t *, int, 56 boolean_t, int *); 57static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *, 58 int *); 59 60struct pagerops sgpagerops = { 61 .pgo_alloc = sg_pager_alloc, 62 .pgo_dealloc = sg_pager_dealloc, 63 .pgo_getpages = sg_pager_getpages, 64 .pgo_putpages = sg_pager_putpages, 65 .pgo_haspage = sg_pager_haspage, 66}; 67 68static vm_object_t 69sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 70 vm_ooffset_t foff, struct ucred *cred) 71{ 72 struct sglist *sg; 73 vm_object_t object; 74 vm_pindex_t npages, pindex; 75 int i; 76 77 /* 78 * Offset should be page aligned. 79 */ 80 if (foff & PAGE_MASK) 81 return (NULL); 82 83 /* 84 * The scatter/gather list must only include page-aligned 85 * ranges. 86 */ 87 npages = 0; 88 sg = handle; 89 for (i = 0; i < sg->sg_nseg; i++) { 90 if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 || 91 (sg->sg_segs[i].ss_len % PAGE_SIZE) != 0) 92 return (NULL); 93 npages += sg->sg_segs[i].ss_len / PAGE_SIZE; 94 } 95 96 /* 97 * The scatter/gather list has a fixed size. Refuse requests 98 * to map beyond that. 99 */ 100 size = round_page(size); 101 pindex = UOFF_TO_IDX(foff) + UOFF_TO_IDX(size); 102 if (pindex > npages || pindex < UOFF_TO_IDX(foff) || 103 pindex < UOFF_TO_IDX(size)) 104 return (NULL); 105 106 /* 107 * Allocate a new object and associate it with the 108 * scatter/gather list. It is ok for our purposes to have 109 * multiple VM objects associated with the same scatter/gather 110 * list because scatter/gather lists are static. This is also 111 * simpler than ensuring a unique object per scatter/gather 112 * list. 113 */ 114 object = vm_object_allocate(OBJT_SG, npages); 115 object->handle = sglist_hold(sg); 116 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist); 117 return (object); 118} 119 120static void 121sg_pager_dealloc(vm_object_t object) 122{ 123 struct sglist *sg; 124 vm_page_t m; 125 126 /* 127 * Free up our fake pages. 128 */ 129 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) { 130 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q); 131 vm_page_putfake(m); 132 } 133 134 sg = object->handle; 135 sglist_free(sg); 136 object->handle = NULL; 137 object->type = OBJT_DEAD; 138} 139 140static int 141sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 142 int *rahead) 143{ 144 struct sglist *sg; 145 vm_page_t m_paddr, page; 146 vm_pindex_t offset; 147 vm_paddr_t paddr; 148 vm_memattr_t memattr; 149 size_t space; 150 int i; 151 152 /* Since our haspage reports zero after/before, the count is 1. */ 153 KASSERT(count == 1, ("%s: count %d", __func__, count)); 154 VM_OBJECT_ASSERT_WLOCKED(object); 155 sg = object->handle; 156 memattr = object->memattr; 157 VM_OBJECT_WUNLOCK(object); 158 offset = m[0]->pindex; 159 160 /* 161 * Lookup the physical address of the requested page. An initial 162 * value of '1' instead of '0' is used so we can assert that the 163 * page is found since '0' can be a valid page-aligned physical 164 * address. 165 */ 166 space = 0; 167 paddr = 1; 168 for (i = 0; i < sg->sg_nseg; i++) { 169 if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) { 170 space += sg->sg_segs[i].ss_len; 171 continue; 172 } 173 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space; 174 break; 175 } 176 KASSERT(paddr != 1, ("invalid SG page index")); 177 178 /* If "paddr" is a real page, perform a sanity check on "memattr". */ 179 if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL && 180 pmap_page_get_memattr(m_paddr) != memattr) { 181 memattr = pmap_page_get_memattr(m_paddr); 182 printf( 183 "WARNING: A device driver has set \"memattr\" inconsistently.\n"); 184 } 185 186 /* Return a fake page for the requested page. */ 187 KASSERT(!(m[0]->flags & PG_FICTITIOUS), 188 ("backing page for SG is fake")); 189 190 /* Construct a new fake page. */ 191 page = vm_page_getfake(paddr, memattr); 192 VM_OBJECT_WLOCK(object); 193 TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q); 194 vm_page_replace_checked(page, object, offset, m[0]); 195 vm_page_lock(m[0]); 196 vm_page_free(m[0]); 197 vm_page_unlock(m[0]); 198 m[0] = page; 199 page->valid = VM_PAGE_BITS_ALL; 200 201 if (rbehind) 202 *rbehind = 0; 203 if (rahead) 204 *rahead = 0; 205 206 return (VM_PAGER_OK); 207} 208 209static void 210sg_pager_putpages(vm_object_t object, vm_page_t *m, int count, 211 boolean_t sync, int *rtvals) 212{ 213 214 panic("sg_pager_putpage called"); 215} 216 217static boolean_t 218sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 219 int *after) 220{ 221 222 if (before != NULL) 223 *before = 0; 224 if (after != NULL) 225 *after = 0; 226 return (TRUE); 227} 228