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/lock.h>
38#include <sys/mutex.h>
39#include <sys/rwlock.h>
40#include <sys/sglist.h>
41#include <sys/user.h>
42#include <sys/vmmeter.h>
43
44#include <vm/vm.h>
45#include <vm/vm_param.h>
46#include <vm/vm_object.h>
47#include <vm/vm_page.h>
48#include <vm/vm_pager.h>
49#include <vm/vm_phys.h>
50#include <vm/uma.h>
51
52static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
53    vm_ooffset_t, struct ucred *);
54static void sg_pager_dealloc(vm_object_t);
55static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
56static void sg_pager_putpages(vm_object_t, vm_page_t *, int,
57		int, int *);
58static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
59		int *);
60
61const struct pagerops sgpagerops = {
62	.pgo_kvme_type = KVME_TYPE_SG,
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,
68};
69
70static vm_object_t
71sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
72    vm_ooffset_t foff, struct ucred *cred)
73{
74	struct sglist *sg;
75	vm_object_t object;
76	vm_pindex_t npages, pindex;
77	int i;
78
79	/*
80	 * Offset should be page aligned.
81	 */
82	if (foff & PAGE_MASK)
83		return (NULL);
84
85	/*
86	 * The scatter/gather list must only include page-aligned
87	 * ranges.
88	 */
89	npages = 0;
90	sg = handle;
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)
94			return (NULL);
95		npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
96	}
97
98	/*
99	 * The scatter/gather list has a fixed size.  Refuse requests
100	 * to map beyond that.
101	 */
102	size = round_page(size);
103	pindex = OFF_TO_IDX(foff) + OFF_TO_IDX(size);
104	if (pindex > npages || pindex < OFF_TO_IDX(foff) ||
105	    pindex < OFF_TO_IDX(size))
106		return (NULL);
107
108	/*
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
114	 * list.
115	 */
116	object = vm_object_allocate(OBJT_SG, npages);
117	object->handle = sglist_hold(sg);
118	TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
119	return (object);
120}
121
122static void
123sg_pager_dealloc(vm_object_t object)
124{
125	struct sglist *sg;
126	vm_page_t m;
127
128	/*
129	 * Free up our fake pages.
130	 */
131	while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
132		if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0)
133			continue;
134		TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q);
135		vm_page_putfake(m);
136	}
137
138	sg = object->handle;
139	sglist_free(sg);
140	object->handle = NULL;
141	object->type = OBJT_DEAD;
142}
143
144static int
145sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
146    int *rahead)
147{
148	struct sglist *sg;
149	vm_page_t m_paddr, page;
150	vm_pindex_t offset;
151	vm_paddr_t paddr;
152	vm_memattr_t memattr;
153	size_t space;
154	int i;
155
156	/* Since our haspage reports zero after/before, the count is 1. */
157	KASSERT(count == 1, ("%s: count %d", __func__, count));
158	/* Handle is stable while paging is in progress. */
159	sg = object->handle;
160	memattr = object->memattr;
161	offset = m[0]->pindex;
162
163	/*
164	 * Lookup the physical address of the requested page.  An initial
165	 * value of '1' instead of '0' is used so we can assert that the
166	 * page is found since '0' can be a valid page-aligned physical
167	 * address.
168	 */
169	space = 0;
170	paddr = 1;
171	for (i = 0; i < sg->sg_nseg; i++) {
172		if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) {
173			space += sg->sg_segs[i].ss_len;
174			continue;
175		}
176		paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
177		break;
178	}
179	KASSERT(paddr != 1, ("invalid SG page index"));
180
181	/* If "paddr" is a real page, perform a sanity check on "memattr". */
182	if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
183	    pmap_page_get_memattr(m_paddr) != memattr) {
184		memattr = pmap_page_get_memattr(m_paddr);
185		printf(
186	    "WARNING: A device driver has set \"memattr\" inconsistently.\n");
187	}
188
189	/* Return a fake page for the requested page. */
190	KASSERT(!(m[0]->flags & PG_FICTITIOUS),
191	    ("backing page for SG is fake"));
192
193	/* Construct a new fake page. */
194	page = vm_page_getfake(paddr, memattr);
195	VM_OBJECT_WLOCK(object);
196	TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q);
197	vm_page_replace(page, object, offset, m[0]);
198	VM_OBJECT_WUNLOCK(object);
199	m[0] = page;
200	vm_page_valid(page);
201
202	if (rbehind)
203		*rbehind = 0;
204	if (rahead)
205		*rahead = 0;
206
207	return (VM_PAGER_OK);
208}
209
210static void
211sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
212    int flags, int *rtvals)
213{
214
215	panic("sg_pager_putpage called");
216}
217
218static boolean_t
219sg_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
220    int *after)
221{
222
223	if (before != NULL)
224		*before = 0;
225	if (after != NULL)
226		*after = 0;
227	return (TRUE);
228}
229