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 
74 static unsigned long mmu_node_start(struct mmu_rb_node *node)
75 {
76 	return node->addr & PAGE_MASK;
77 }
78 
79 static unsigned long mmu_node_last(struct mmu_rb_node *node)
80 {
81 	return PAGE_ALIGN(node->addr + node->len) - 1;
82 }
83 
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 
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 	/* Unregister first so we don't get any more notifications. */
125 	mmu_notifier_unregister(&handler->mn, handler->mn.mm);
126 
127 	/*
128 	 * Make sure the wq delete handler is finished running.  It will not
129 	 * be triggered once the mmu notifiers are unregistered above.
130 	 */
131 	flush_work(&handler->del_work);
132 
133 	INIT_LIST_HEAD(&del_list);
134 
135 	spin_lock_irqsave(&handler->lock, flags);
136 	while ((node = rb_first_cached(&handler->root))) {
137 		rbnode = rb_entry(node, struct mmu_rb_node, node);
138 		rb_erase_cached(node, &handler->root);
139 		/* move from LRU list to delete list */
140 		list_move(&rbnode->list, &del_list);
141 	}
142 	spin_unlock_irqrestore(&handler->lock, flags);
143 
144 	do_remove(handler, &del_list);
145 
146 	kfree(handler);
147 }
148 
149 int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler,
150 		       struct mmu_rb_node *mnode)
151 {
152 	struct mmu_rb_node *node;
153 	unsigned long flags;
154 	int ret = 0;
155 
156 	trace_hfi1_mmu_rb_insert(mnode->addr, mnode->len);
157 
158 	if (current->mm != handler->mn.mm)
159 		return -EPERM;
160 
161 	spin_lock_irqsave(&handler->lock, flags);
162 	node = __mmu_rb_search(handler, mnode->addr, mnode->len);
163 	if (node) {
164 		ret = -EINVAL;
165 		goto unlock;
166 	}
167 	__mmu_int_rb_insert(mnode, &handler->root);
168 	list_add(&mnode->list, &handler->lru_list);
169 
170 	ret = handler->ops->insert(handler->ops_arg, mnode);
171 	if (ret) {
172 		__mmu_int_rb_remove(mnode, &handler->root);
173 		list_del(&mnode->list); /* remove from LRU list */
174 	}
175 	mnode->handler = handler;
176 unlock:
177 	spin_unlock_irqrestore(&handler->lock, flags);
178 	return ret;
179 }
180 
181 /* Caller must hold handler lock */
182 static struct mmu_rb_node *__mmu_rb_search(struct mmu_rb_handler *handler,
183 					   unsigned long addr,
184 					   unsigned long len)
185 {
186 	struct mmu_rb_node *node = NULL;
187 
188 	trace_hfi1_mmu_rb_search(addr, len);
189 	if (!handler->ops->filter) {
190 		node = __mmu_int_rb_iter_first(&handler->root, addr,
191 					       (addr + len) - 1);
192 	} else {
193 		for (node = __mmu_int_rb_iter_first(&handler->root, addr,
194 						    (addr + len) - 1);
195 		     node;
196 		     node = __mmu_int_rb_iter_next(node, addr,
197 						   (addr + len) - 1)) {
198 			if (handler->ops->filter(node, addr, len))
199 				return node;
200 		}
201 	}
202 	return node;
203 }
204 
205 bool hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler *handler,
206 				     unsigned long addr, unsigned long len,
207 				     struct mmu_rb_node **rb_node)
208 {
209 	struct mmu_rb_node *node;
210 	unsigned long flags;
211 	bool ret = false;
212 
213 	if (current->mm != handler->mn.mm)
214 		return ret;
215 
216 	spin_lock_irqsave(&handler->lock, flags);
217 	node = __mmu_rb_search(handler, addr, len);
218 	if (node) {
219 		if (node->addr == addr && node->len == len)
220 			goto unlock;
221 		__mmu_int_rb_remove(node, &handler->root);
222 		list_del(&node->list); /* remove from LRU list */
223 		ret = true;
224 	}
225 unlock:
226 	spin_unlock_irqrestore(&handler->lock, flags);
227 	*rb_node = node;
228 	return ret;
229 }
230 
231 void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg)
232 {
233 	struct mmu_rb_node *rbnode, *ptr;
234 	struct list_head del_list;
235 	unsigned long flags;
236 	bool stop = false;
237 
238 	if (current->mm != handler->mn.mm)
239 		return;
240 
241 	INIT_LIST_HEAD(&del_list);
242 
243 	spin_lock_irqsave(&handler->lock, flags);
244 	list_for_each_entry_safe_reverse(rbnode, ptr, &handler->lru_list,
245 					 list) {
246 		if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg,
247 					&stop)) {
248 			__mmu_int_rb_remove(rbnode, &handler->root);
249 			/* move from LRU list to delete list */
250 			list_move(&rbnode->list, &del_list);
251 		}
252 		if (stop)
253 			break;
254 	}
255 	spin_unlock_irqrestore(&handler->lock, flags);
256 
257 	while (!list_empty(&del_list)) {
258 		rbnode = list_first_entry(&del_list, struct mmu_rb_node, list);
259 		list_del(&rbnode->list);
260 		handler->ops->remove(handler->ops_arg, rbnode);
261 	}
262 }
263 
264 /*
265  * It is up to the caller to ensure that this function does not race with the
266  * mmu invalidate notifier which may be calling the users remove callback on
267  * 'node'.
268  */
269 void hfi1_mmu_rb_remove(struct mmu_rb_handler *handler,
270 			struct mmu_rb_node *node)
271 {
272 	unsigned long flags;
273 
274 	if (current->mm != handler->mn.mm)
275 		return;
276 
277 	/* Validity of handler and node pointers has been checked by caller. */
278 	trace_hfi1_mmu_rb_remove(node->addr, node->len);
279 	spin_lock_irqsave(&handler->lock, flags);
280 	__mmu_int_rb_remove(node, &handler->root);
281 	list_del(&node->list); /* remove from LRU list */
282 	spin_unlock_irqrestore(&handler->lock, flags);
283 
284 	handler->ops->remove(handler->ops_arg, node);
285 }
286 
287 static int mmu_notifier_range_start(struct mmu_notifier *mn,
288 		const struct mmu_notifier_range *range)
289 {
290 	struct mmu_rb_handler *handler =
291 		container_of(mn, struct mmu_rb_handler, mn);
292 	struct rb_root_cached *root = &handler->root;
293 	struct mmu_rb_node *node, *ptr = NULL;
294 	unsigned long flags;
295 	bool added = false;
296 
297 	spin_lock_irqsave(&handler->lock, flags);
298 	for (node = __mmu_int_rb_iter_first(root, range->start, range->end-1);
299 	     node; node = ptr) {
300 		/* Guard against node removal. */
301 		ptr = __mmu_int_rb_iter_next(node, range->start,
302 					     range->end - 1);
303 		trace_hfi1_mmu_mem_invalidate(node->addr, node->len);
304 		if (handler->ops->invalidate(handler->ops_arg, node)) {
305 			__mmu_int_rb_remove(node, root);
306 			/* move from LRU list to delete list */
307 			list_move(&node->list, &handler->del_list);
308 			added = true;
309 		}
310 	}
311 	spin_unlock_irqrestore(&handler->lock, flags);
312 
313 	if (added)
314 		queue_work(handler->wq, &handler->del_work);
315 
316 	return 0;
317 }
318 
319 /*
320  * Call the remove function for the given handler and the list.  This
321  * is expected to be called with a delete list extracted from handler.
322  * The caller should not be holding the handler lock.
323  */
324 static void do_remove(struct mmu_rb_handler *handler,
325 		      struct list_head *del_list)
326 {
327 	struct mmu_rb_node *node;
328 
329 	while (!list_empty(del_list)) {
330 		node = list_first_entry(del_list, struct mmu_rb_node, list);
331 		list_del(&node->list);
332 		handler->ops->remove(handler->ops_arg, node);
333 	}
334 }
335 
336 /*
337  * Work queue function to remove all nodes that have been queued up to
338  * be removed.  The key feature is that mm->mmap_lock is not being held
339  * and the remove callback can sleep while taking it, if needed.
340  */
341 static void handle_remove(struct work_struct *work)
342 {
343 	struct mmu_rb_handler *handler = container_of(work,
344 						struct mmu_rb_handler,
345 						del_work);
346 	struct list_head del_list;
347 	unsigned long flags;
348 
349 	/* remove anything that is queued to get removed */
350 	spin_lock_irqsave(&handler->lock, flags);
351 	list_replace_init(&handler->del_list, &del_list);
352 	spin_unlock_irqrestore(&handler->lock, flags);
353 
354 	do_remove(handler, &del_list);
355 }
356