2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2009 Hudson River Trading LLC
5 * Written by: John H. Baldwin <jhb@FreeBSD.org>
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
34 * This pager manages OBJT_SG objects. These objects are backed by
35 * a scatter/gather list of physical address ranges.
38 #include <sys/param.h>
40 #include <sys/mutex.h>
41 #include <sys/rwlock.h>
42 #include <sys/sglist.h>
43 #include <sys/vmmeter.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>
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,
59 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
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,
71 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
72 vm_ooffset_t foff, struct ucred *cred)
76 vm_pindex_t npages, pindex;
80 * Offset should be page aligned.
86 * The scatter/gather list must only include page-aligned
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)
95 npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
99 * The scatter/gather list has a fixed size. Refuse requests
100 * to map beyond that.
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))
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
116 object = vm_object_allocate(OBJT_SG, npages);
117 object->handle = sglist_hold(sg);
118 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
123 sg_pager_dealloc(vm_object_t object)
129 * Free up our fake pages.
131 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
132 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q);
138 object->handle = NULL;
139 object->type = OBJT_DEAD;
143 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
147 vm_page_t m_paddr, page;
150 vm_memattr_t memattr;
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);
158 memattr = object->memattr;
159 VM_OBJECT_WUNLOCK(object);
160 offset = m[0]->pindex;
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
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;
175 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
178 KASSERT(paddr != 1, ("invalid SG page index"));
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);
185 "WARNING: A device driver has set \"memattr\" inconsistently.\n");
188 /* Return a fake page for the requested page. */
189 KASSERT(!(m[0]->flags & PG_FICTITIOUS),
190 ("backing page for SG is fake"));
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]);
199 vm_page_unlock(m[0]);
201 page->valid = VM_PAGE_BITS_ALL;
208 return (VM_PAGER_OK);
212 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
213 boolean_t sync, int *rtvals)
216 panic("sg_pager_putpage called");
220 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,