1 /* binder_alloc.c
2  *
3  * Android IPC Subsystem
4  *
5  * Copyright (C) 2007-2017 Google, Inc.
6  *
7  * This software is licensed under the terms of the GNU General Public
8  * License version 2, as published by the Free Software Foundation, and
9  * may be copied, distributed, and modified under those terms.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  */
17 
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 
20 #include <asm/cacheflush.h>
21 #include <linux/list.h>
22 #include <linux/sched/mm.h>
23 #include <linux/module.h>
24 #include <linux/rtmutex.h>
25 #include <linux/rbtree.h>
26 #include <linux/seq_file.h>
27 #include <linux/vmalloc.h>
28 #include <linux/slab.h>
29 #include <linux/sched.h>
30 #include <linux/list_lru.h>
31 #include "binder_alloc.h"
32 #include "binder_trace.h"
33 
34 struct list_lru binder_alloc_lru;
35 
36 static DEFINE_MUTEX(binder_alloc_mmap_lock);
37 
38 enum {
39 	BINDER_DEBUG_OPEN_CLOSE             = 1U << 1,
40 	BINDER_DEBUG_BUFFER_ALLOC           = 1U << 2,
41 	BINDER_DEBUG_BUFFER_ALLOC_ASYNC     = 1U << 3,
42 };
43 static uint32_t binder_alloc_debug_mask;
44 
45 module_param_named(debug_mask, binder_alloc_debug_mask,
46 		   uint, 0644);
47 
48 #define binder_alloc_debug(mask, x...) \
49 	do { \
50 		if (binder_alloc_debug_mask & mask) \
51 			pr_info(x); \
52 	} while (0)
53 
54 static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
55 {
56 	return list_entry(buffer->entry.next, struct binder_buffer, entry);
57 }
58 
59 static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
60 {
61 	return list_entry(buffer->entry.prev, struct binder_buffer, entry);
62 }
63 
64 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
65 				       struct binder_buffer *buffer)
66 {
67 	if (list_is_last(&buffer->entry, &alloc->buffers))
68 		return (u8 *)alloc->buffer +
69 			alloc->buffer_size - (u8 *)buffer->data;
70 	return (u8 *)binder_buffer_next(buffer)->data - (u8 *)buffer->data;
71 }
72 
73 static void binder_insert_free_buffer(struct binder_alloc *alloc,
74 				      struct binder_buffer *new_buffer)
75 {
76 	struct rb_node **p = &alloc->free_buffers.rb_node;
77 	struct rb_node *parent = NULL;
78 	struct binder_buffer *buffer;
79 	size_t buffer_size;
80 	size_t new_buffer_size;
81 
82 	BUG_ON(!new_buffer->free);
83 
84 	new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
85 
86 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
87 		     "%d: add free buffer, size %zd, at %pK\n",
88 		      alloc->pid, new_buffer_size, new_buffer);
89 
90 	while (*p) {
91 		parent = *p;
92 		buffer = rb_entry(parent, struct binder_buffer, rb_node);
93 		BUG_ON(!buffer->free);
94 
95 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
96 
97 		if (new_buffer_size < buffer_size)
98 			p = &parent->rb_left;
99 		else
100 			p = &parent->rb_right;
101 	}
102 	rb_link_node(&new_buffer->rb_node, parent, p);
103 	rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers);
104 }
105 
106 static void binder_insert_allocated_buffer_locked(
107 		struct binder_alloc *alloc, struct binder_buffer *new_buffer)
108 {
109 	struct rb_node **p = &alloc->allocated_buffers.rb_node;
110 	struct rb_node *parent = NULL;
111 	struct binder_buffer *buffer;
112 
113 	BUG_ON(new_buffer->free);
114 
115 	while (*p) {
116 		parent = *p;
117 		buffer = rb_entry(parent, struct binder_buffer, rb_node);
118 		BUG_ON(buffer->free);
119 
120 		if (new_buffer->data < buffer->data)
121 			p = &parent->rb_left;
122 		else if (new_buffer->data > buffer->data)
123 			p = &parent->rb_right;
124 		else
125 			BUG();
126 	}
127 	rb_link_node(&new_buffer->rb_node, parent, p);
128 	rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers);
129 }
130 
131 static struct binder_buffer *binder_alloc_prepare_to_free_locked(
132 		struct binder_alloc *alloc,
133 		uintptr_t user_ptr)
134 {
135 	struct rb_node *n = alloc->allocated_buffers.rb_node;
136 	struct binder_buffer *buffer;
137 	void *kern_ptr;
138 
139 	kern_ptr = (void *)(user_ptr - alloc->user_buffer_offset);
140 
141 	while (n) {
142 		buffer = rb_entry(n, struct binder_buffer, rb_node);
143 		BUG_ON(buffer->free);
144 
145 		if (kern_ptr < buffer->data)
146 			n = n->rb_left;
147 		else if (kern_ptr > buffer->data)
148 			n = n->rb_right;
149 		else {
150 			/*
151 			 * Guard against user threads attempting to
152 			 * free the buffer twice
153 			 */
154 			if (buffer->free_in_progress) {
155 				pr_err("%d:%d FREE_BUFFER u%016llx user freed buffer twice\n",
156 				       alloc->pid, current->pid, (u64)user_ptr);
157 				return NULL;
158 			}
159 			buffer->free_in_progress = 1;
160 			return buffer;
161 		}
162 	}
163 	return NULL;
164 }
165 
166 /**
167  * binder_alloc_buffer_lookup() - get buffer given user ptr
168  * @alloc:	binder_alloc for this proc
169  * @user_ptr:	User pointer to buffer data
170  *
171  * Validate userspace pointer to buffer data and return buffer corresponding to
172  * that user pointer. Search the rb tree for buffer that matches user data
173  * pointer.
174  *
175  * Return:	Pointer to buffer or NULL
176  */
177 struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
178 						   uintptr_t user_ptr)
179 {
180 	struct binder_buffer *buffer;
181 
182 	mutex_lock(&alloc->mutex);
183 	buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
184 	mutex_unlock(&alloc->mutex);
185 	return buffer;
186 }
187 
188 static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
189 				    void *start, void *end)
190 {
191 	void *page_addr;
192 	unsigned long user_page_addr;
193 	struct binder_lru_page *page;
194 	struct vm_area_struct *vma = NULL;
195 	struct mm_struct *mm = NULL;
196 	bool need_mm = false;
197 
198 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
199 		     "%d: %s pages %pK-%pK\n", alloc->pid,
200 		     allocate ? "allocate" : "free", start, end);
201 
202 	if (end <= start)
203 		return 0;
204 
205 	trace_binder_update_page_range(alloc, allocate, start, end);
206 
207 	if (allocate == 0)
208 		goto free_range;
209 
210 	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
211 		page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
212 		if (!page->page_ptr) {
213 			need_mm = true;
214 			break;
215 		}
216 	}
217 
218 	if (need_mm && mmget_not_zero(alloc->vma_vm_mm))
219 		mm = alloc->vma_vm_mm;
220 
221 	if (mm) {
222 		down_write(&mm->mmap_sem);
223 		vma = alloc->vma;
224 	}
225 
226 	if (!vma && need_mm) {
227 		pr_err("%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
228 			alloc->pid);
229 		goto err_no_vma;
230 	}
231 
232 	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
233 		int ret;
234 		bool on_lru;
235 		size_t index;
236 
237 		index = (page_addr - alloc->buffer) / PAGE_SIZE;
238 		page = &alloc->pages[index];
239 
240 		if (page->page_ptr) {
241 			trace_binder_alloc_lru_start(alloc, index);
242 
243 			on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
244 			WARN_ON(!on_lru);
245 
246 			trace_binder_alloc_lru_end(alloc, index);
247 			continue;
248 		}
249 
250 		if (WARN_ON(!vma))
251 			goto err_page_ptr_cleared;
252 
253 		trace_binder_alloc_page_start(alloc, index);
254 		page->page_ptr = alloc_page(GFP_KERNEL |
255 					    __GFP_HIGHMEM |
256 					    __GFP_ZERO);
257 		if (!page->page_ptr) {
258 			pr_err("%d: binder_alloc_buf failed for page at %pK\n",
259 				alloc->pid, page_addr);
260 			goto err_alloc_page_failed;
261 		}
262 		page->alloc = alloc;
263 		INIT_LIST_HEAD(&page->lru);
264 
265 		ret = map_kernel_range_noflush((unsigned long)page_addr,
266 					       PAGE_SIZE, PAGE_KERNEL,
267 					       &page->page_ptr);
268 		flush_cache_vmap((unsigned long)page_addr,
269 				(unsigned long)page_addr + PAGE_SIZE);
270 		if (ret != 1) {
271 			pr_err("%d: binder_alloc_buf failed to map page at %pK in kernel\n",
272 			       alloc->pid, page_addr);
273 			goto err_map_kernel_failed;
274 		}
275 		user_page_addr =
276 			(uintptr_t)page_addr + alloc->user_buffer_offset;
277 		ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
278 		if (ret) {
279 			pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
280 			       alloc->pid, user_page_addr);
281 			goto err_vm_insert_page_failed;
282 		}
283 
284 		trace_binder_alloc_page_end(alloc, index);
285 		/* vm_insert_page does not seem to increment the refcount */
286 	}
287 	if (mm) {
288 		up_write(&mm->mmap_sem);
289 		mmput(mm);
290 	}
291 	return 0;
292 
293 free_range:
294 	for (page_addr = end - PAGE_SIZE; page_addr >= start;
295 	     page_addr -= PAGE_SIZE) {
296 		bool ret;
297 		size_t index;
298 
299 		index = (page_addr - alloc->buffer) / PAGE_SIZE;
300 		page = &alloc->pages[index];
301 
302 		trace_binder_free_lru_start(alloc, index);
303 
304 		ret = list_lru_add(&binder_alloc_lru, &page->lru);
305 		WARN_ON(!ret);
306 
307 		trace_binder_free_lru_end(alloc, index);
308 		continue;
309 
310 err_vm_insert_page_failed:
311 		unmap_kernel_range((unsigned long)page_addr, PAGE_SIZE);
312 err_map_kernel_failed:
313 		__free_page(page->page_ptr);
314 		page->page_ptr = NULL;
315 err_alloc_page_failed:
316 err_page_ptr_cleared:
317 		;
318 	}
319 err_no_vma:
320 	if (mm) {
321 		up_write(&mm->mmap_sem);
322 		mmput(mm);
323 	}
324 	return vma ? -ENOMEM : -ESRCH;
325 }
326 
327 struct binder_buffer *binder_alloc_new_buf_locked(struct binder_alloc *alloc,
328 						  size_t data_size,
329 						  size_t offsets_size,
330 						  size_t extra_buffers_size,
331 						  int is_async)
332 {
333 	struct rb_node *n = alloc->free_buffers.rb_node;
334 	struct binder_buffer *buffer;
335 	size_t buffer_size;
336 	struct rb_node *best_fit = NULL;
337 	void *has_page_addr;
338 	void *end_page_addr;
339 	size_t size, data_offsets_size;
340 	int ret;
341 
342 	if (alloc->vma == NULL) {
343 		pr_err("%d: binder_alloc_buf, no vma\n",
344 		       alloc->pid);
345 		return ERR_PTR(-ESRCH);
346 	}
347 
348 	data_offsets_size = ALIGN(data_size, sizeof(void *)) +
349 		ALIGN(offsets_size, sizeof(void *));
350 
351 	if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
352 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
353 				"%d: got transaction with invalid size %zd-%zd\n",
354 				alloc->pid, data_size, offsets_size);
355 		return ERR_PTR(-EINVAL);
356 	}
357 	size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
358 	if (size < data_offsets_size || size < extra_buffers_size) {
359 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
360 				"%d: got transaction with invalid extra_buffers_size %zd\n",
361 				alloc->pid, extra_buffers_size);
362 		return ERR_PTR(-EINVAL);
363 	}
364 	if (is_async &&
365 	    alloc->free_async_space < size + sizeof(struct binder_buffer)) {
366 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
367 			     "%d: binder_alloc_buf size %zd failed, no async space left\n",
368 			      alloc->pid, size);
369 		return ERR_PTR(-ENOSPC);
370 	}
371 
372 	/* Pad 0-size buffers so they get assigned unique addresses */
373 	size = max(size, sizeof(void *));
374 
375 	while (n) {
376 		buffer = rb_entry(n, struct binder_buffer, rb_node);
377 		BUG_ON(!buffer->free);
378 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
379 
380 		if (size < buffer_size) {
381 			best_fit = n;
382 			n = n->rb_left;
383 		} else if (size > buffer_size)
384 			n = n->rb_right;
385 		else {
386 			best_fit = n;
387 			break;
388 		}
389 	}
390 	if (best_fit == NULL) {
391 		size_t allocated_buffers = 0;
392 		size_t largest_alloc_size = 0;
393 		size_t total_alloc_size = 0;
394 		size_t free_buffers = 0;
395 		size_t largest_free_size = 0;
396 		size_t total_free_size = 0;
397 
398 		for (n = rb_first(&alloc->allocated_buffers); n != NULL;
399 		     n = rb_next(n)) {
400 			buffer = rb_entry(n, struct binder_buffer, rb_node);
401 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
402 			allocated_buffers++;
403 			total_alloc_size += buffer_size;
404 			if (buffer_size > largest_alloc_size)
405 				largest_alloc_size = buffer_size;
406 		}
407 		for (n = rb_first(&alloc->free_buffers); n != NULL;
408 		     n = rb_next(n)) {
409 			buffer = rb_entry(n, struct binder_buffer, rb_node);
410 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
411 			free_buffers++;
412 			total_free_size += buffer_size;
413 			if (buffer_size > largest_free_size)
414 				largest_free_size = buffer_size;
415 		}
416 		pr_err("%d: binder_alloc_buf size %zd failed, no address space\n",
417 			alloc->pid, size);
418 		pr_err("allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
419 		       total_alloc_size, allocated_buffers, largest_alloc_size,
420 		       total_free_size, free_buffers, largest_free_size);
421 		return ERR_PTR(-ENOSPC);
422 	}
423 	if (n == NULL) {
424 		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
425 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
426 	}
427 
428 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
429 		     "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
430 		      alloc->pid, size, buffer, buffer_size);
431 
432 	has_page_addr =
433 		(void *)(((uintptr_t)buffer->data + buffer_size) & PAGE_MASK);
434 	WARN_ON(n && buffer_size != size);
435 	end_page_addr =
436 		(void *)PAGE_ALIGN((uintptr_t)buffer->data + size);
437 	if (end_page_addr > has_page_addr)
438 		end_page_addr = has_page_addr;
439 	ret = binder_update_page_range(alloc, 1,
440 	    (void *)PAGE_ALIGN((uintptr_t)buffer->data), end_page_addr);
441 	if (ret)
442 		return ERR_PTR(ret);
443 
444 	if (buffer_size != size) {
445 		struct binder_buffer *new_buffer;
446 
447 		new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
448 		if (!new_buffer) {
449 			pr_err("%s: %d failed to alloc new buffer struct\n",
450 			       __func__, alloc->pid);
451 			goto err_alloc_buf_struct_failed;
452 		}
453 		new_buffer->data = (u8 *)buffer->data + size;
454 		list_add(&new_buffer->entry, &buffer->entry);
455 		new_buffer->free = 1;
456 		binder_insert_free_buffer(alloc, new_buffer);
457 	}
458 
459 	rb_erase(best_fit, &alloc->free_buffers);
460 	buffer->free = 0;
461 	buffer->free_in_progress = 0;
462 	binder_insert_allocated_buffer_locked(alloc, buffer);
463 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
464 		     "%d: binder_alloc_buf size %zd got %pK\n",
465 		      alloc->pid, size, buffer);
466 	buffer->data_size = data_size;
467 	buffer->offsets_size = offsets_size;
468 	buffer->async_transaction = is_async;
469 	buffer->extra_buffers_size = extra_buffers_size;
470 	if (is_async) {
471 		alloc->free_async_space -= size + sizeof(struct binder_buffer);
472 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
473 			     "%d: binder_alloc_buf size %zd async free %zd\n",
474 			      alloc->pid, size, alloc->free_async_space);
475 	}
476 	return buffer;
477 
478 err_alloc_buf_struct_failed:
479 	binder_update_page_range(alloc, 0,
480 				 (void *)PAGE_ALIGN((uintptr_t)buffer->data),
481 				 end_page_addr);
482 	return ERR_PTR(-ENOMEM);
483 }
484 
485 /**
486  * binder_alloc_new_buf() - Allocate a new binder buffer
487  * @alloc:              binder_alloc for this proc
488  * @data_size:          size of user data buffer
489  * @offsets_size:       user specified buffer offset
490  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
491  * @is_async:           buffer for async transaction
492  *
493  * Allocate a new buffer given the requested sizes. Returns
494  * the kernel version of the buffer pointer. The size allocated
495  * is the sum of the three given sizes (each rounded up to
496  * pointer-sized boundary)
497  *
498  * Return:	The allocated buffer or %NULL if error
499  */
500 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
501 					   size_t data_size,
502 					   size_t offsets_size,
503 					   size_t extra_buffers_size,
504 					   int is_async)
505 {
506 	struct binder_buffer *buffer;
507 
508 	mutex_lock(&alloc->mutex);
509 	buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
510 					     extra_buffers_size, is_async);
511 	mutex_unlock(&alloc->mutex);
512 	return buffer;
513 }
514 
515 static void *buffer_start_page(struct binder_buffer *buffer)
516 {
517 	return (void *)((uintptr_t)buffer->data & PAGE_MASK);
518 }
519 
520 static void *prev_buffer_end_page(struct binder_buffer *buffer)
521 {
522 	return (void *)(((uintptr_t)(buffer->data) - 1) & PAGE_MASK);
523 }
524 
525 static void binder_delete_free_buffer(struct binder_alloc *alloc,
526 				      struct binder_buffer *buffer)
527 {
528 	struct binder_buffer *prev, *next = NULL;
529 	bool to_free = true;
530 	BUG_ON(alloc->buffers.next == &buffer->entry);
531 	prev = binder_buffer_prev(buffer);
532 	BUG_ON(!prev->free);
533 	if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
534 		to_free = false;
535 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
536 				   "%d: merge free, buffer %pK share page with %pK\n",
537 				   alloc->pid, buffer->data, prev->data);
538 	}
539 
540 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
541 		next = binder_buffer_next(buffer);
542 		if (buffer_start_page(next) == buffer_start_page(buffer)) {
543 			to_free = false;
544 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
545 					   "%d: merge free, buffer %pK share page with %pK\n",
546 					   alloc->pid,
547 					   buffer->data,
548 					   next->data);
549 		}
550 	}
551 
552 	if (PAGE_ALIGNED(buffer->data)) {
553 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
554 				   "%d: merge free, buffer start %pK is page aligned\n",
555 				   alloc->pid, buffer->data);
556 		to_free = false;
557 	}
558 
559 	if (to_free) {
560 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
561 				   "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
562 				   alloc->pid, buffer->data,
563 				   prev->data, next ? next->data : NULL);
564 		binder_update_page_range(alloc, 0, buffer_start_page(buffer),
565 					 buffer_start_page(buffer) + PAGE_SIZE);
566 	}
567 	list_del(&buffer->entry);
568 	kfree(buffer);
569 }
570 
571 static void binder_free_buf_locked(struct binder_alloc *alloc,
572 				   struct binder_buffer *buffer)
573 {
574 	size_t size, buffer_size;
575 
576 	buffer_size = binder_alloc_buffer_size(alloc, buffer);
577 
578 	size = ALIGN(buffer->data_size, sizeof(void *)) +
579 		ALIGN(buffer->offsets_size, sizeof(void *)) +
580 		ALIGN(buffer->extra_buffers_size, sizeof(void *));
581 
582 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
583 		     "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
584 		      alloc->pid, buffer, size, buffer_size);
585 
586 	BUG_ON(buffer->free);
587 	BUG_ON(size > buffer_size);
588 	BUG_ON(buffer->transaction != NULL);
589 	BUG_ON(buffer->data < alloc->buffer);
590 	BUG_ON(buffer->data > alloc->buffer + alloc->buffer_size);
591 
592 	if (buffer->async_transaction) {
593 		alloc->free_async_space += size + sizeof(struct binder_buffer);
594 
595 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
596 			     "%d: binder_free_buf size %zd async free %zd\n",
597 			      alloc->pid, size, alloc->free_async_space);
598 	}
599 
600 	binder_update_page_range(alloc, 0,
601 		(void *)PAGE_ALIGN((uintptr_t)buffer->data),
602 		(void *)(((uintptr_t)buffer->data + buffer_size) & PAGE_MASK));
603 
604 	rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
605 	buffer->free = 1;
606 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
607 		struct binder_buffer *next = binder_buffer_next(buffer);
608 
609 		if (next->free) {
610 			rb_erase(&next->rb_node, &alloc->free_buffers);
611 			binder_delete_free_buffer(alloc, next);
612 		}
613 	}
614 	if (alloc->buffers.next != &buffer->entry) {
615 		struct binder_buffer *prev = binder_buffer_prev(buffer);
616 
617 		if (prev->free) {
618 			binder_delete_free_buffer(alloc, buffer);
619 			rb_erase(&prev->rb_node, &alloc->free_buffers);
620 			buffer = prev;
621 		}
622 	}
623 	binder_insert_free_buffer(alloc, buffer);
624 }
625 
626 /**
627  * binder_alloc_free_buf() - free a binder buffer
628  * @alloc:	binder_alloc for this proc
629  * @buffer:	kernel pointer to buffer
630  *
631  * Free the buffer allocated via binder_alloc_new_buffer()
632  */
633 void binder_alloc_free_buf(struct binder_alloc *alloc,
634 			    struct binder_buffer *buffer)
635 {
636 	mutex_lock(&alloc->mutex);
637 	binder_free_buf_locked(alloc, buffer);
638 	mutex_unlock(&alloc->mutex);
639 }
640 
641 /**
642  * binder_alloc_mmap_handler() - map virtual address space for proc
643  * @alloc:	alloc structure for this proc
644  * @vma:	vma passed to mmap()
645  *
646  * Called by binder_mmap() to initialize the space specified in
647  * vma for allocating binder buffers
648  *
649  * Return:
650  *      0 = success
651  *      -EBUSY = address space already mapped
652  *      -ENOMEM = failed to map memory to given address space
653  */
654 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
655 			      struct vm_area_struct *vma)
656 {
657 	int ret;
658 	struct vm_struct *area;
659 	const char *failure_string;
660 	struct binder_buffer *buffer;
661 
662 	mutex_lock(&binder_alloc_mmap_lock);
663 	if (alloc->buffer) {
664 		ret = -EBUSY;
665 		failure_string = "already mapped";
666 		goto err_already_mapped;
667 	}
668 
669 	area = get_vm_area(vma->vm_end - vma->vm_start, VM_IOREMAP);
670 	if (area == NULL) {
671 		ret = -ENOMEM;
672 		failure_string = "get_vm_area";
673 		goto err_get_vm_area_failed;
674 	}
675 	alloc->buffer = area->addr;
676 	alloc->user_buffer_offset =
677 		vma->vm_start - (uintptr_t)alloc->buffer;
678 	mutex_unlock(&binder_alloc_mmap_lock);
679 
680 #ifdef CONFIG_CPU_CACHE_VIPT
681 	if (cache_is_vipt_aliasing()) {
682 		while (CACHE_COLOUR(
683 				(vma->vm_start ^ (uint32_t)alloc->buffer))) {
684 			pr_info("%s: %d %lx-%lx maps %pK bad alignment\n",
685 				__func__, alloc->pid, vma->vm_start,
686 				vma->vm_end, alloc->buffer);
687 			vma->vm_start += PAGE_SIZE;
688 		}
689 	}
690 #endif
691 	alloc->pages = kzalloc(sizeof(alloc->pages[0]) *
692 				   ((vma->vm_end - vma->vm_start) / PAGE_SIZE),
693 			       GFP_KERNEL);
694 	if (alloc->pages == NULL) {
695 		ret = -ENOMEM;
696 		failure_string = "alloc page array";
697 		goto err_alloc_pages_failed;
698 	}
699 	alloc->buffer_size = vma->vm_end - vma->vm_start;
700 
701 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
702 	if (!buffer) {
703 		ret = -ENOMEM;
704 		failure_string = "alloc buffer struct";
705 		goto err_alloc_buf_struct_failed;
706 	}
707 
708 	buffer->data = alloc->buffer;
709 	list_add(&buffer->entry, &alloc->buffers);
710 	buffer->free = 1;
711 	binder_insert_free_buffer(alloc, buffer);
712 	alloc->free_async_space = alloc->buffer_size / 2;
713 	barrier();
714 	alloc->vma = vma;
715 	alloc->vma_vm_mm = vma->vm_mm;
716 	mmgrab(alloc->vma_vm_mm);
717 
718 	return 0;
719 
720 err_alloc_buf_struct_failed:
721 	kfree(alloc->pages);
722 	alloc->pages = NULL;
723 err_alloc_pages_failed:
724 	mutex_lock(&binder_alloc_mmap_lock);
725 	vfree(alloc->buffer);
726 	alloc->buffer = NULL;
727 err_get_vm_area_failed:
728 err_already_mapped:
729 	mutex_unlock(&binder_alloc_mmap_lock);
730 	pr_err("%s: %d %lx-%lx %s failed %d\n", __func__,
731 	       alloc->pid, vma->vm_start, vma->vm_end, failure_string, ret);
732 	return ret;
733 }
734 
735 
736 void binder_alloc_deferred_release(struct binder_alloc *alloc)
737 {
738 	struct rb_node *n;
739 	int buffers, page_count;
740 	struct binder_buffer *buffer;
741 
742 	BUG_ON(alloc->vma);
743 
744 	buffers = 0;
745 	mutex_lock(&alloc->mutex);
746 	while ((n = rb_first(&alloc->allocated_buffers))) {
747 		buffer = rb_entry(n, struct binder_buffer, rb_node);
748 
749 		/* Transaction should already have been freed */
750 		BUG_ON(buffer->transaction);
751 
752 		binder_free_buf_locked(alloc, buffer);
753 		buffers++;
754 	}
755 
756 	while (!list_empty(&alloc->buffers)) {
757 		buffer = list_first_entry(&alloc->buffers,
758 					  struct binder_buffer, entry);
759 		WARN_ON(!buffer->free);
760 
761 		list_del(&buffer->entry);
762 		WARN_ON_ONCE(!list_empty(&alloc->buffers));
763 		kfree(buffer);
764 	}
765 
766 	page_count = 0;
767 	if (alloc->pages) {
768 		int i;
769 
770 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
771 			void *page_addr;
772 			bool on_lru;
773 
774 			if (!alloc->pages[i].page_ptr)
775 				continue;
776 
777 			on_lru = list_lru_del(&binder_alloc_lru,
778 					      &alloc->pages[i].lru);
779 			page_addr = alloc->buffer + i * PAGE_SIZE;
780 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
781 				     "%s: %d: page %d at %pK %s\n",
782 				     __func__, alloc->pid, i, page_addr,
783 				     on_lru ? "on lru" : "active");
784 			unmap_kernel_range((unsigned long)page_addr, PAGE_SIZE);
785 			__free_page(alloc->pages[i].page_ptr);
786 			page_count++;
787 		}
788 		kfree(alloc->pages);
789 		vfree(alloc->buffer);
790 	}
791 	mutex_unlock(&alloc->mutex);
792 	if (alloc->vma_vm_mm)
793 		mmdrop(alloc->vma_vm_mm);
794 
795 	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
796 		     "%s: %d buffers %d, pages %d\n",
797 		     __func__, alloc->pid, buffers, page_count);
798 }
799 
800 static void print_binder_buffer(struct seq_file *m, const char *prefix,
801 				struct binder_buffer *buffer)
802 {
803 	seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
804 		   prefix, buffer->debug_id, buffer->data,
805 		   buffer->data_size, buffer->offsets_size,
806 		   buffer->extra_buffers_size,
807 		   buffer->transaction ? "active" : "delivered");
808 }
809 
810 /**
811  * binder_alloc_print_allocated() - print buffer info
812  * @m:     seq_file for output via seq_printf()
813  * @alloc: binder_alloc for this proc
814  *
815  * Prints information about every buffer associated with
816  * the binder_alloc state to the given seq_file
817  */
818 void binder_alloc_print_allocated(struct seq_file *m,
819 				  struct binder_alloc *alloc)
820 {
821 	struct rb_node *n;
822 
823 	mutex_lock(&alloc->mutex);
824 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
825 		print_binder_buffer(m, "  buffer",
826 				    rb_entry(n, struct binder_buffer, rb_node));
827 	mutex_unlock(&alloc->mutex);
828 }
829 
830 /**
831  * binder_alloc_print_pages() - print page usage
832  * @m:     seq_file for output via seq_printf()
833  * @alloc: binder_alloc for this proc
834  */
835 void binder_alloc_print_pages(struct seq_file *m,
836 			      struct binder_alloc *alloc)
837 {
838 	struct binder_lru_page *page;
839 	int i;
840 	int active = 0;
841 	int lru = 0;
842 	int free = 0;
843 
844 	mutex_lock(&alloc->mutex);
845 	for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
846 		page = &alloc->pages[i];
847 		if (!page->page_ptr)
848 			free++;
849 		else if (list_empty(&page->lru))
850 			active++;
851 		else
852 			lru++;
853 	}
854 	mutex_unlock(&alloc->mutex);
855 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
856 }
857 
858 /**
859  * binder_alloc_get_allocated_count() - return count of buffers
860  * @alloc: binder_alloc for this proc
861  *
862  * Return: count of allocated buffers
863  */
864 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
865 {
866 	struct rb_node *n;
867 	int count = 0;
868 
869 	mutex_lock(&alloc->mutex);
870 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
871 		count++;
872 	mutex_unlock(&alloc->mutex);
873 	return count;
874 }
875 
876 
877 /**
878  * binder_alloc_vma_close() - invalidate address space
879  * @alloc: binder_alloc for this proc
880  *
881  * Called from binder_vma_close() when releasing address space.
882  * Clears alloc->vma to prevent new incoming transactions from
883  * allocating more buffers.
884  */
885 void binder_alloc_vma_close(struct binder_alloc *alloc)
886 {
887 	WRITE_ONCE(alloc->vma, NULL);
888 }
889 
890 /**
891  * binder_alloc_free_page() - shrinker callback to free pages
892  * @item:   item to free
893  * @lock:   lock protecting the item
894  * @cb_arg: callback argument
895  *
896  * Called from list_lru_walk() in binder_shrink_scan() to free
897  * up pages when the system is under memory pressure.
898  */
899 enum lru_status binder_alloc_free_page(struct list_head *item,
900 				       struct list_lru_one *lru,
901 				       spinlock_t *lock,
902 				       void *cb_arg)
903 {
904 	struct mm_struct *mm = NULL;
905 	struct binder_lru_page *page = container_of(item,
906 						    struct binder_lru_page,
907 						    lru);
908 	struct binder_alloc *alloc;
909 	uintptr_t page_addr;
910 	size_t index;
911 	struct vm_area_struct *vma;
912 
913 	alloc = page->alloc;
914 	if (!mutex_trylock(&alloc->mutex))
915 		goto err_get_alloc_mutex_failed;
916 
917 	if (!page->page_ptr)
918 		goto err_page_already_freed;
919 
920 	index = page - alloc->pages;
921 	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
922 	vma = alloc->vma;
923 	if (vma) {
924 		if (!mmget_not_zero(alloc->vma_vm_mm))
925 			goto err_mmget;
926 		mm = alloc->vma_vm_mm;
927 		if (!down_write_trylock(&mm->mmap_sem))
928 			goto err_down_write_mmap_sem_failed;
929 	}
930 
931 	list_lru_isolate(lru, item);
932 	spin_unlock(lock);
933 
934 	if (vma) {
935 		trace_binder_unmap_user_start(alloc, index);
936 
937 		zap_page_range(vma,
938 			       page_addr + alloc->user_buffer_offset,
939 			       PAGE_SIZE);
940 
941 		trace_binder_unmap_user_end(alloc, index);
942 
943 		up_write(&mm->mmap_sem);
944 		mmput(mm);
945 	}
946 
947 	trace_binder_unmap_kernel_start(alloc, index);
948 
949 	unmap_kernel_range(page_addr, PAGE_SIZE);
950 	__free_page(page->page_ptr);
951 	page->page_ptr = NULL;
952 
953 	trace_binder_unmap_kernel_end(alloc, index);
954 
955 	spin_lock(lock);
956 	mutex_unlock(&alloc->mutex);
957 	return LRU_REMOVED_RETRY;
958 
959 err_down_write_mmap_sem_failed:
960 	mmput_async(mm);
961 err_mmget:
962 err_page_already_freed:
963 	mutex_unlock(&alloc->mutex);
964 err_get_alloc_mutex_failed:
965 	return LRU_SKIP;
966 }
967 
968 static unsigned long
969 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
970 {
971 	unsigned long ret = list_lru_count(&binder_alloc_lru);
972 	return ret;
973 }
974 
975 static unsigned long
976 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
977 {
978 	unsigned long ret;
979 
980 	ret = list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
981 			    NULL, sc->nr_to_scan);
982 	return ret;
983 }
984 
985 static struct shrinker binder_shrinker = {
986 	.count_objects = binder_shrink_count,
987 	.scan_objects = binder_shrink_scan,
988 	.seeks = DEFAULT_SEEKS,
989 };
990 
991 /**
992  * binder_alloc_init() - called by binder_open() for per-proc initialization
993  * @alloc: binder_alloc for this proc
994  *
995  * Called from binder_open() to initialize binder_alloc fields for
996  * new binder proc
997  */
998 void binder_alloc_init(struct binder_alloc *alloc)
999 {
1000 	alloc->pid = current->group_leader->pid;
1001 	mutex_init(&alloc->mutex);
1002 	INIT_LIST_HEAD(&alloc->buffers);
1003 }
1004 
1005 void binder_alloc_shrinker_init(void)
1006 {
1007 	list_lru_init(&binder_alloc_lru);
1008 	register_shrinker(&binder_shrinker);
1009 }
1010