2 * Copyright (c) 2009 Hudson River Trading LLC
3 * Written by: John H. Baldwin <jhb@FreeBSD.org>
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
32 * This pager manages OBJT_SG objects. These objects are backed by
33 * a scatter/gather list of physical address ranges.
36 #include <sys/param.h>
38 #include <sys/mutex.h>
39 #include <sys/rwlock.h>
40 #include <sys/sglist.h>
41 #include <sys/vmmeter.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>
51 static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
52 vm_ooffset_t, struct ucred *);
53 static void sg_pager_dealloc(vm_object_t);
54 static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
55 static void sg_pager_putpages(vm_object_t, vm_page_t *, int,
57 static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
60 struct 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,
69 sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
70 vm_ooffset_t foff, struct ucred *cred)
74 vm_pindex_t npages, pindex;
78 * Offset should be page aligned.
84 * The scatter/gather list must only include page-aligned
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)
93 npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
97 * The scatter/gather list has a fixed size. Refuse requests
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))
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
114 object = vm_object_allocate(OBJT_SG, npages);
115 object->handle = sglist_hold(sg);
116 TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
121 sg_pager_dealloc(vm_object_t object)
127 * Free up our fake pages.
129 while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
130 TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q);
136 object->handle = NULL;
137 object->type = OBJT_DEAD;
141 sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
145 vm_page_t m_paddr, page;
148 vm_memattr_t memattr;
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);
156 memattr = object->memattr;
157 VM_OBJECT_WUNLOCK(object);
158 offset = m[0]->pindex;
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
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;
173 paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
176 KASSERT(paddr != 1, ("invalid SG page index"));
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);
183 "WARNING: A device driver has set \"memattr\" inconsistently.\n");
186 /* Return a fake page for the requested page. */
187 KASSERT(!(m[0]->flags & PG_FICTITIOUS),
188 ("backing page for SG is fake"));
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]);
197 vm_page_unlock(m[0]);
199 page->valid = VM_PAGE_BITS_ALL;
206 return (VM_PAGER_OK);
210 sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
211 boolean_t sync, int *rtvals)
214 panic("sg_pager_putpage called");
218 sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,