1 /* $NetBSD: pmap_pvt.c,v 1.15 2022/05/08 22:03:02 rin Exp $ */
2
3 /*-
4 * Copyright (c) 2014, 2020 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __RCSID("$NetBSD: pmap_pvt.c,v 1.15 2022/05/08 22:03:02 rin Exp $");
34
35 #include <sys/param.h>
36 #include <sys/atomic.h>
37 #include <sys/kmem.h>
38 #include <sys/pserialize.h>
39
40 #include <uvm/uvm.h>
41 #include <uvm/pmap/pmap_pvt.h>
42
43 #if !defined(PMAP_PV_TRACK_ONLY_STUBS)
44 /*
45 * unmanaged pv-tracked ranges
46 *
47 * This is a linear list for now because the only user are the DRM
48 * graphics drivers, with a single tracked range per device, for the
49 * graphics aperture, so there are expected to be few of them.
50 *
51 * This is used only after the VM system is initialized well enough
52 * that we can use kmem_alloc.
53 */
54
55 struct pv_track {
56 paddr_t pvt_start;
57 psize_t pvt_size;
58 struct pv_track *pvt_next;
59 struct pmap_page pvt_pages[];
60 };
61
62 static struct {
63 kmutex_t lock;
64 pserialize_t psz;
65 struct pv_track *list;
66 } pv_unmanaged __cacheline_aligned;
67
68 void
pmap_pv_init(void)69 pmap_pv_init(void)
70 {
71
72 mutex_init(&pv_unmanaged.lock, MUTEX_DEFAULT, IPL_NONE);
73 pv_unmanaged.psz = pserialize_create();
74 pv_unmanaged.list = NULL;
75 }
76
77 void
pmap_pv_track(paddr_t start,psize_t size)78 pmap_pv_track(paddr_t start, psize_t size)
79 {
80 struct pv_track *pvt;
81 size_t npages;
82
83 KASSERT(start == trunc_page(start));
84 KASSERT(size == trunc_page(size));
85
86 /* We may sleep for allocation. */
87 ASSERT_SLEEPABLE();
88
89 npages = size >> PAGE_SHIFT;
90 pvt = kmem_zalloc(offsetof(struct pv_track, pvt_pages[npages]),
91 KM_SLEEP);
92 pvt->pvt_start = start;
93 pvt->pvt_size = size;
94
95 #ifdef PMAP_PAGE_INIT
96 for (size_t i = 0; i < npages; i++)
97 PMAP_PAGE_INIT(&pvt->pvt_pages[i]);
98 #endif
99
100 mutex_enter(&pv_unmanaged.lock);
101 pvt->pvt_next = pv_unmanaged.list;
102 atomic_store_release(&pv_unmanaged.list, pvt);
103 mutex_exit(&pv_unmanaged.lock);
104 }
105
106 void
pmap_pv_untrack(paddr_t start,psize_t size)107 pmap_pv_untrack(paddr_t start, psize_t size)
108 {
109 struct pv_track **pvtp, *pvt;
110 size_t npages;
111
112 KASSERT(start == trunc_page(start));
113 KASSERT(size == trunc_page(size));
114
115 /* We may sleep for pserialize_perform. */
116 ASSERT_SLEEPABLE();
117
118 mutex_enter(&pv_unmanaged.lock);
119 for (pvtp = &pv_unmanaged.list;
120 (pvt = *pvtp) != NULL;
121 pvtp = &pvt->pvt_next) {
122 if (pvt->pvt_start != start)
123 continue;
124 if (pvt->pvt_size != size)
125 panic("pmap_pv_untrack: pv-tracking at 0x%"PRIxPADDR
126 ": 0x%"PRIxPSIZE" bytes, not 0x%"PRIxPSIZE" bytes",
127 pvt->pvt_start, pvt->pvt_size, size);
128
129 /*
130 * Remove from list. Readers can safely see the old
131 * and new states of the list.
132 */
133 atomic_store_relaxed(pvtp, pvt->pvt_next);
134
135 /* Wait for readers who can see the old state to finish. */
136 pserialize_perform(pv_unmanaged.psz);
137
138 /*
139 * We now have exclusive access to pvt and can destroy
140 * it. Poison it to catch bugs.
141 */
142 explicit_memset(&pvt->pvt_next, 0x1a, sizeof pvt->pvt_next);
143 goto out;
144 }
145 panic("pmap_pv_untrack: pages not pv-tracked at 0x%"PRIxPADDR
146 " (0x%"PRIxPSIZE" bytes)",
147 start, size);
148 out: mutex_exit(&pv_unmanaged.lock);
149
150 npages = size >> PAGE_SHIFT;
151 kmem_free(pvt, offsetof(struct pv_track, pvt_pages[npages]));
152 }
153
154 struct pmap_page *
pmap_pv_tracked(paddr_t pa)155 pmap_pv_tracked(paddr_t pa)
156 {
157 struct pv_track *pvt;
158 size_t pgno;
159 int s;
160
161 KASSERT(pa == trunc_page(pa));
162
163 s = pserialize_read_enter();
164 for (pvt = atomic_load_consume(&pv_unmanaged.list);
165 pvt != NULL;
166 pvt = pvt->pvt_next) {
167 if ((pvt->pvt_start <= pa) &&
168 ((pa - pvt->pvt_start) < pvt->pvt_size))
169 break;
170 }
171 pserialize_read_exit(s);
172
173 if (pvt == NULL)
174 return NULL;
175 KASSERT(pvt->pvt_start <= pa);
176 KASSERT((pa - pvt->pvt_start) < pvt->pvt_size);
177 pgno = (pa - pvt->pvt_start) >> PAGE_SHIFT;
178 return &pvt->pvt_pages[pgno];
179 }
180
181 #else /* PMAP_PV_TRACK_ONLY_STUBS */
182 /*
183 * Provide empty stubs just for MODULAR kernels.
184 */
185
186 void
pmap_pv_init(void)187 pmap_pv_init(void)
188 {
189
190 }
191
192 struct pmap_page *
pmap_pv_tracked(paddr_t pa)193 pmap_pv_tracked(paddr_t pa)
194 {
195
196 return NULL;
197 }
198
199 #if notdef
200 /*
201 * pmap_pv_{,un}track() are intentionally commented out. If modules
202 * call these functions, the result should be an inconsistent state.
203 *
204 * Such modules require real PV-tracking support. Let us make the
205 * two symbols undefined, and prevent these modules from loaded.
206 */
207 void
pmap_pv_track(paddr_t start,psize_t size)208 pmap_pv_track(paddr_t start, psize_t size)
209 {
210
211 panic("PV-tracking not supported");
212 }
213
214 void
pmap_pv_untrack(paddr_t start,psize_t size)215 pmap_pv_untrack(paddr_t start, psize_t size)
216 {
217
218 panic("PV-tracking not supported");
219 }
220 #endif /* notdef */
221
222 #endif /* PMAP_PV_TRACK_ONLY_STUBS */
223