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