1 /*
2 * Copyright(c) 2020 Cornelis Networks, Inc.
3 * Copyright(c) 2016 - 2017 Intel Corporation.
4 *
5 * This file is provided under a dual BSD/GPLv2 license. When using or
6 * redistributing this file, you may do so under either license.
7 *
8 * GPL LICENSE SUMMARY
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of version 2 of the GNU General Public License as
12 * published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * BSD LICENSE
20 *
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
23 * are met:
24 *
25 * - Redistributions of source code must retain the above copyright
26 * notice, this list of conditions and the following disclaimer.
27 * - Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in
29 * the documentation and/or other materials provided with the
30 * distribution.
31 * - Neither the name of Intel Corporation nor the names of its
32 * contributors may be used to endorse or promote products derived
33 * from this software without specific prior written permission.
34 *
35 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
38 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
39 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
42 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
43 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
44 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
45 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
46 *
47 */
48 #include <linux/list.h>
49 #include <linux/rculist.h>
50 #include <linux/mmu_notifier.h>
51 #include <linux/interval_tree_generic.h>
52 #include <linux/sched/mm.h>
53
54 #include "mmu_rb.h"
55 #include "trace.h"
56
57 static unsigned long mmu_node_start(struct mmu_rb_node *);
58 static unsigned long mmu_node_last(struct mmu_rb_node *);
59 static int mmu_notifier_range_start(struct mmu_notifier *,
60 const struct mmu_notifier_range *);
61 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *,
62 unsigned long, unsigned long);
63 static void do_remove(struct mmu_rb_handler *handler,
64 struct list_head *del_list);
65 static void handle_remove(struct work_struct *work);
66
67 static const struct mmu_notifier_ops mn_opts = {
68 .invalidate_range_start = mmu_notifier_range_start,
69 };
70
71 INTERVAL_TREE_DEFINE(struct mmu_rb_node, node, unsigned long, __last,
72 mmu_node_start, mmu_node_last, static, __mmu_int_rb);
73
mmu_node_start(struct mmu_rb_node * node)74 static unsigned long mmu_node_start(struct mmu_rb_node *node)
75 {
76 return node->addr & PAGE_MASK;
77 }
78
mmu_node_last(struct mmu_rb_node * node)79 static unsigned long mmu_node_last(struct mmu_rb_node *node)
80 {
81 return PAGE_ALIGN(node->addr + node->len) - 1;
82 }
83
hfi1_mmu_rb_register(void * ops_arg,struct mmu_rb_ops * ops,struct workqueue_struct * wq,struct mmu_rb_handler ** handler)84 int hfi1_mmu_rb_register(void *ops_arg,
85 struct mmu_rb_ops *ops,
86 struct workqueue_struct *wq,
87 struct mmu_rb_handler **handler)
88 {
89 struct mmu_rb_handler *h;
90 int ret;
91
92 h = kzalloc(sizeof(*h), GFP_KERNEL);
93 if (!h)
94 return -ENOMEM;
95
96 h->root = RB_ROOT_CACHED;
97 h->ops = ops;
98 h->ops_arg = ops_arg;
99 INIT_HLIST_NODE(&h->mn.hlist);
100 spin_lock_init(&h->lock);
101 h->mn.ops = &mn_opts;
102 INIT_WORK(&h->del_work, handle_remove);
103 INIT_LIST_HEAD(&h->del_list);
104 INIT_LIST_HEAD(&h->lru_list);
105 h->wq = wq;
106
107 ret = mmu_notifier_register(&h->mn, current->mm);
108 if (ret) {
109 kfree(h);
110 return ret;
111 }
112
113 *handler = h;
114 return 0;
115 }
116
hfi1_mmu_rb_unregister(struct mmu_rb_handler * handler)117 void hfi1_mmu_rb_unregister(struct mmu_rb_handler *handler)
118 {
119 struct mmu_rb_node *rbnode;
120 struct rb_node *node;
121 unsigned long flags;
122 struct list_head del_list;
123
124 /* Prevent freeing of mm until we are completely finished. */
125 mmgrab(handler->mn.mm);
126
127 /* Unregister first so we don't get any more notifications. */
128 mmu_notifier_unregister(&handler->mn, handler->mn.mm);
129
130 /*
131 * Make sure the wq delete handler is finished running. It will not
132 * be triggered once the mmu notifiers are unregistered above.
133 */
134 flush_work(&handler->del_work);
135
136 INIT_LIST_HEAD(&del_list);
137
138 spin_lock_irqsave(&handler->lock, flags);
139 while ((node = rb_first_cached(&handler->root))) {
140 rbnode = rb_entry(node, struct mmu_rb_node, node);
141 rb_erase_cached(node, &handler->root);
142 /* move from LRU list to delete list */
143 list_move(&rbnode->list, &del_list);
144 }
145 spin_unlock_irqrestore(&handler->lock, flags);
146
147 do_remove(handler, &del_list);
148
149 /* Now the mm may be freed. */
150 mmdrop(handler->mn.mm);
151
152 kfree(handler);
153 }
154
hfi1_mmu_rb_insert(struct mmu_rb_handler * handler,struct mmu_rb_node * mnode)155 int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
156 struct mmu_rb_node *mnode)
157 {
158 struct mmu_rb_node *node;
159 unsigned long flags;
160 int ret = 0;
161
162 trace_hfi1_mmu_rb_insert(mnode->addr, mnode->len);
163
164 if (current->mm != handler->mn.mm)
165 return -EPERM;
166
167 spin_lock_irqsave(&handler->lock, flags);
168 node = __mmu_rb_search(handler, mnode->addr, mnode->len);
169 if (node) {
170 ret = -EINVAL;
171 goto unlock;
172 }
173 __mmu_int_rb_insert(mnode, &handler->root);
174 list_add(&mnode->list, &handler->lru_list);
175
176 ret = handler->ops->insert(handler->ops_arg, mnode);
177 if (ret) {
178 __mmu_int_rb_remove(mnode, &handler->root);
179 list_del(&mnode->list); /* remove from LRU list */
180 }
181 mnode->handler = handler;
182 unlock:
183 spin_unlock_irqrestore(&handler->lock, flags);
184 return ret;
185 }
186
187 /* Caller must hold handler lock */
__mmu_rb_search(struct mmu_rb_handler * handler,unsigned long addr,unsigned long len)188 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *handler,
189 unsigned long addr,
190 unsigned long len)
191 {
192 struct mmu_rb_node *node = NULL;
193
194 trace_hfi1_mmu_rb_search(addr, len);
195 if (!handler->ops->filter) {
196 node = __mmu_int_rb_iter_first(&handler->root, addr,
197 (addr + len) - 1);
198 } else {
199 for (node = __mmu_int_rb_iter_first(&handler->root, addr,
200 (addr + len) - 1);
201 node;
202 node = __mmu_int_rb_iter_next(node, addr,
203 (addr + len) - 1)) {
204 if (handler->ops->filter(node, addr, len))
205 return node;
206 }
207 }
208 return node;
209 }
210
hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler * handler,unsigned long addr,unsigned long len,struct mmu_rb_node ** rb_node)211 bool hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler *handler,
212 unsigned long addr, unsigned long len,
213 struct mmu_rb_node **rb_node)
214 {
215 struct mmu_rb_node *node;
216 unsigned long flags;
217 bool ret = false;
218
219 if (current->mm != handler->mn.mm)
220 return ret;
221
222 spin_lock_irqsave(&handler->lock, flags);
223 node = __mmu_rb_search(handler, addr, len);
224 if (node) {
225 if (node->addr == addr && node->len == len)
226 goto unlock;
227 __mmu_int_rb_remove(node, &handler->root);
228 list_del(&node->list); /* remove from LRU list */
229 ret = true;
230 }
231 unlock:
232 spin_unlock_irqrestore(&handler->lock, flags);
233 *rb_node = node;
234 return ret;
235 }
236
hfi1_mmu_rb_evict(struct mmu_rb_handler * handler,void * evict_arg)237 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
238 {
239 struct mmu_rb_node *rbnode, *ptr;
240 struct list_head del_list;
241 unsigned long flags;
242 bool stop = false;
243
244 if (current->mm != handler->mn.mm)
245 return;
246
247 INIT_LIST_HEAD(&del_list);
248
249 spin_lock_irqsave(&handler->lock, flags);
250 list_for_each_entry_safe_reverse(rbnode, ptr, &handler->lru_list,
251 list) {
252 if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg,
253 &stop)) {
254 __mmu_int_rb_remove(rbnode, &handler->root);
255 /* move from LRU list to delete list */
256 list_move(&rbnode->list, &del_list);
257 }
258 if (stop)
259 break;
260 }
261 spin_unlock_irqrestore(&handler->lock, flags);
262
263 while (!list_empty(&del_list)) {
264 rbnode = list_first_entry(&del_list, struct mmu_rb_node, list);
265 list_del(&rbnode->list);
266 handler->ops->remove(handler->ops_arg, rbnode);
267 }
268 }
269
270 /*
271 * It is up to the caller to ensure that this function does not race with the
272 * mmu invalidate notifier which may be calling the users remove callback on
273 * 'node'.
274 */
hfi1_mmu_rb_remove(struct mmu_rb_handler * handler,struct mmu_rb_node * node)275 void hfi1_mmu_rb_remove(struct mmu_rb_handler *handler,
276 struct mmu_rb_node *node)
277 {
278 unsigned long flags;
279
280 if (current->mm != handler->mn.mm)
281 return;
282
283 /* Validity of handler and node pointers has been checked by caller. */
284 trace_hfi1_mmu_rb_remove(node->addr, node->len);
285 spin_lock_irqsave(&handler->lock, flags);
286 __mmu_int_rb_remove(node, &handler->root);
287 list_del(&node->list); /* remove from LRU list */
288 spin_unlock_irqrestore(&handler->lock, flags);
289
290 handler->ops->remove(handler->ops_arg, node);
291 }
292
mmu_notifier_range_start(struct mmu_notifier * mn,const struct mmu_notifier_range * range)293 static int mmu_notifier_range_start(struct mmu_notifier *mn,
294 const struct mmu_notifier_range *range)
295 {
296 struct mmu_rb_handler *handler =
297 container_of(mn, struct mmu_rb_handler, mn);
298 struct rb_root_cached *root = &handler->root;
299 struct mmu_rb_node *node, *ptr = NULL;
300 unsigned long flags;
301 bool added = false;
302
303 spin_lock_irqsave(&handler->lock, flags);
304 for (node = __mmu_int_rb_iter_first(root, range->start, range->end-1);
305 node; node = ptr) {
306 /* Guard against node removal. */
307 ptr = __mmu_int_rb_iter_next(node, range->start,
308 range->end - 1);
309 trace_hfi1_mmu_mem_invalidate(node->addr, node->len);
310 if (handler->ops->invalidate(handler->ops_arg, node)) {
311 __mmu_int_rb_remove(node, root);
312 /* move from LRU list to delete list */
313 list_move(&node->list, &handler->del_list);
314 added = true;
315 }
316 }
317 spin_unlock_irqrestore(&handler->lock, flags);
318
319 if (added)
320 queue_work(handler->wq, &handler->del_work);
321
322 return 0;
323 }
324
325 /*
326 * Call the remove function for the given handler and the list. This
327 * is expected to be called with a delete list extracted from handler.
328 * The caller should not be holding the handler lock.
329 */
do_remove(struct mmu_rb_handler * handler,struct list_head * del_list)330 static void do_remove(struct mmu_rb_handler *handler,
331 struct list_head *del_list)
332 {
333 struct mmu_rb_node *node;
334
335 while (!list_empty(del_list)) {
336 node = list_first_entry(del_list, struct mmu_rb_node, list);
337 list_del(&node->list);
338 handler->ops->remove(handler->ops_arg, node);
339 }
340 }
341
342 /*
343 * Work queue function to remove all nodes that have been queued up to
344 * be removed. The key feature is that mm->mmap_lock is not being held
345 * and the remove callback can sleep while taking it, if needed.
346 */
handle_remove(struct work_struct * work)347 static void handle_remove(struct work_struct *work)
348 {
349 struct mmu_rb_handler *handler = container_of(work,
350 struct mmu_rb_handler,
351 del_work);
352 struct list_head del_list;
353 unsigned long flags;
354
355 /* remove anything that is queued to get removed */
356 spin_lock_irqsave(&handler->lock, flags);
357 list_replace_init(&handler->del_list, &del_list);
358 spin_unlock_irqrestore(&handler->lock, flags);
359
360 do_remove(handler, &del_list);
361 }
362