1 // SPDX-License-Identifier: GPL-2.0-only
2 /* binder_alloc.c
3  *
4  * Android IPC Subsystem
5  *
6  * Copyright (C) 2007-2017 Google, Inc.
7  */
8 
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 
11 #include <linux/list.h>
12 #include <linux/sched/mm.h>
13 #include <linux/module.h>
14 #include <linux/rtmutex.h>
15 #include <linux/rbtree.h>
16 #include <linux/seq_file.h>
17 #include <linux/vmalloc.h>
18 #include <linux/slab.h>
19 #include <linux/sched.h>
20 #include <linux/list_lru.h>
21 #include <linux/ratelimit.h>
22 #include <asm/cacheflush.h>
23 #include <linux/uaccess.h>
24 #include <linux/highmem.h>
25 #include <linux/sizes.h>
26 #include "binder_alloc.h"
27 #include "binder_trace.h"
28 
29 struct list_lru binder_alloc_lru;
30 
31 static DEFINE_MUTEX(binder_alloc_mmap_lock);
32 
33 enum {
34 	BINDER_DEBUG_USER_ERROR             = 1U << 0,
35 	BINDER_DEBUG_OPEN_CLOSE             = 1U << 1,
36 	BINDER_DEBUG_BUFFER_ALLOC           = 1U << 2,
37 	BINDER_DEBUG_BUFFER_ALLOC_ASYNC     = 1U << 3,
38 };
39 static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR;
40 
41 module_param_named(debug_mask, binder_alloc_debug_mask,
42 		   uint, 0644);
43 
44 #define binder_alloc_debug(mask, x...) \
45 	do { \
46 		if (binder_alloc_debug_mask & mask) \
47 			pr_info_ratelimited(x); \
48 	} while (0)
49 
50 static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
51 {
52 	return list_entry(buffer->entry.next, struct binder_buffer, entry);
53 }
54 
55 static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
56 {
57 	return list_entry(buffer->entry.prev, struct binder_buffer, entry);
58 }
59 
60 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
61 				       struct binder_buffer *buffer)
62 {
63 	if (list_is_last(&buffer->entry, &alloc->buffers))
64 		return alloc->buffer + alloc->buffer_size - buffer->user_data;
65 	return binder_buffer_next(buffer)->user_data - buffer->user_data;
66 }
67 
68 static void binder_insert_free_buffer(struct binder_alloc *alloc,
69 				      struct binder_buffer *new_buffer)
70 {
71 	struct rb_node **p = &alloc->free_buffers.rb_node;
72 	struct rb_node *parent = NULL;
73 	struct binder_buffer *buffer;
74 	size_t buffer_size;
75 	size_t new_buffer_size;
76 
77 	BUG_ON(!new_buffer->free);
78 
79 	new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
80 
81 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
82 		     "%d: add free buffer, size %zd, at %pK\n",
83 		      alloc->pid, new_buffer_size, new_buffer);
84 
85 	while (*p) {
86 		parent = *p;
87 		buffer = rb_entry(parent, struct binder_buffer, rb_node);
88 		BUG_ON(!buffer->free);
89 
90 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
91 
92 		if (new_buffer_size < buffer_size)
93 			p = &parent->rb_left;
94 		else
95 			p = &parent->rb_right;
96 	}
97 	rb_link_node(&new_buffer->rb_node, parent, p);
98 	rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers);
99 }
100 
101 static void binder_insert_allocated_buffer_locked(
102 		struct binder_alloc *alloc, struct binder_buffer *new_buffer)
103 {
104 	struct rb_node **p = &alloc->allocated_buffers.rb_node;
105 	struct rb_node *parent = NULL;
106 	struct binder_buffer *buffer;
107 
108 	BUG_ON(new_buffer->free);
109 
110 	while (*p) {
111 		parent = *p;
112 		buffer = rb_entry(parent, struct binder_buffer, rb_node);
113 		BUG_ON(buffer->free);
114 
115 		if (new_buffer->user_data < buffer->user_data)
116 			p = &parent->rb_left;
117 		else if (new_buffer->user_data > buffer->user_data)
118 			p = &parent->rb_right;
119 		else
120 			BUG();
121 	}
122 	rb_link_node(&new_buffer->rb_node, parent, p);
123 	rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers);
124 }
125 
126 static struct binder_buffer *binder_alloc_prepare_to_free_locked(
127 		struct binder_alloc *alloc,
128 		uintptr_t user_ptr)
129 {
130 	struct rb_node *n = alloc->allocated_buffers.rb_node;
131 	struct binder_buffer *buffer;
132 	void __user *uptr;
133 
134 	uptr = (void __user *)user_ptr;
135 
136 	while (n) {
137 		buffer = rb_entry(n, struct binder_buffer, rb_node);
138 		BUG_ON(buffer->free);
139 
140 		if (uptr < buffer->user_data)
141 			n = n->rb_left;
142 		else if (uptr > buffer->user_data)
143 			n = n->rb_right;
144 		else {
145 			/*
146 			 * Guard against user threads attempting to
147 			 * free the buffer when in use by kernel or
148 			 * after it's already been freed.
149 			 */
150 			if (!buffer->allow_user_free)
151 				return ERR_PTR(-EPERM);
152 			buffer->allow_user_free = 0;
153 			return buffer;
154 		}
155 	}
156 	return NULL;
157 }
158 
159 /**
160  * binder_alloc_prepare_to_free() - get buffer given user ptr
161  * @alloc:	binder_alloc for this proc
162  * @user_ptr:	User pointer to buffer data
163  *
164  * Validate userspace pointer to buffer data and return buffer corresponding to
165  * that user pointer. Search the rb tree for buffer that matches user data
166  * pointer.
167  *
168  * Return:	Pointer to buffer or NULL
169  */
170 struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
171 						   uintptr_t user_ptr)
172 {
173 	struct binder_buffer *buffer;
174 
175 	mutex_lock(&alloc->mutex);
176 	buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
177 	mutex_unlock(&alloc->mutex);
178 	return buffer;
179 }
180 
181 static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
182 				    void __user *start, void __user *end)
183 {
184 	void __user *page_addr;
185 	unsigned long user_page_addr;
186 	struct binder_lru_page *page;
187 	struct vm_area_struct *vma = NULL;
188 	struct mm_struct *mm = NULL;
189 	bool need_mm = false;
190 
191 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
192 		     "%d: %s pages %pK-%pK\n", alloc->pid,
193 		     allocate ? "allocate" : "free", start, end);
194 
195 	if (end <= start)
196 		return 0;
197 
198 	trace_binder_update_page_range(alloc, allocate, start, end);
199 
200 	if (allocate == 0)
201 		goto free_range;
202 
203 	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
204 		page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
205 		if (!page->page_ptr) {
206 			need_mm = true;
207 			break;
208 		}
209 	}
210 
211 	if (need_mm && mmget_not_zero(alloc->mm))
212 		mm = alloc->mm;
213 
214 	if (mm) {
215 		mmap_write_lock(mm);
216 		vma = alloc->vma;
217 	}
218 
219 	if (!vma && need_mm) {
220 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
221 				   "%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
222 				   alloc->pid);
223 		goto err_no_vma;
224 	}
225 
226 	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
227 		int ret;
228 		bool on_lru;
229 		size_t index;
230 
231 		index = (page_addr - alloc->buffer) / PAGE_SIZE;
232 		page = &alloc->pages[index];
233 
234 		if (page->page_ptr) {
235 			trace_binder_alloc_lru_start(alloc, index);
236 
237 			on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
238 			WARN_ON(!on_lru);
239 
240 			trace_binder_alloc_lru_end(alloc, index);
241 			continue;
242 		}
243 
244 		if (WARN_ON(!vma))
245 			goto err_page_ptr_cleared;
246 
247 		trace_binder_alloc_page_start(alloc, index);
248 		page->page_ptr = alloc_page(GFP_KERNEL |
249 					    __GFP_HIGHMEM |
250 					    __GFP_ZERO);
251 		if (!page->page_ptr) {
252 			pr_err("%d: binder_alloc_buf failed for page at %pK\n",
253 				alloc->pid, page_addr);
254 			goto err_alloc_page_failed;
255 		}
256 		page->alloc = alloc;
257 		INIT_LIST_HEAD(&page->lru);
258 
259 		user_page_addr = (uintptr_t)page_addr;
260 		ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
261 		if (ret) {
262 			pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
263 			       alloc->pid, user_page_addr);
264 			goto err_vm_insert_page_failed;
265 		}
266 
267 		if (index + 1 > alloc->pages_high)
268 			alloc->pages_high = index + 1;
269 
270 		trace_binder_alloc_page_end(alloc, index);
271 	}
272 	if (mm) {
273 		mmap_write_unlock(mm);
274 		mmput(mm);
275 	}
276 	return 0;
277 
278 free_range:
279 	for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) {
280 		bool ret;
281 		size_t index;
282 
283 		index = (page_addr - alloc->buffer) / PAGE_SIZE;
284 		page = &alloc->pages[index];
285 
286 		trace_binder_free_lru_start(alloc, index);
287 
288 		ret = list_lru_add(&binder_alloc_lru, &page->lru);
289 		WARN_ON(!ret);
290 
291 		trace_binder_free_lru_end(alloc, index);
292 		if (page_addr == start)
293 			break;
294 		continue;
295 
296 err_vm_insert_page_failed:
297 		__free_page(page->page_ptr);
298 		page->page_ptr = NULL;
299 err_alloc_page_failed:
300 err_page_ptr_cleared:
301 		if (page_addr == start)
302 			break;
303 	}
304 err_no_vma:
305 	if (mm) {
306 		mmap_write_unlock(mm);
307 		mmput(mm);
308 	}
309 	return vma ? -ENOMEM : -ESRCH;
310 }
311 
312 static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
313 		struct vm_area_struct *vma)
314 {
315 	/* pairs with smp_load_acquire in binder_alloc_get_vma() */
316 	smp_store_release(&alloc->vma, vma);
317 }
318 
319 static inline struct vm_area_struct *binder_alloc_get_vma(
320 		struct binder_alloc *alloc)
321 {
322 	/* pairs with smp_store_release in binder_alloc_set_vma() */
323 	return smp_load_acquire(&alloc->vma);
324 }
325 
326 static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
327 {
328 	/*
329 	 * Find the amount and size of buffers allocated by the current caller;
330 	 * The idea is that once we cross the threshold, whoever is responsible
331 	 * for the low async space is likely to try to send another async txn,
332 	 * and at some point we'll catch them in the act. This is more efficient
333 	 * than keeping a map per pid.
334 	 */
335 	struct rb_node *n;
336 	struct binder_buffer *buffer;
337 	size_t total_alloc_size = 0;
338 	size_t num_buffers = 0;
339 
340 	for (n = rb_first(&alloc->allocated_buffers); n != NULL;
341 		 n = rb_next(n)) {
342 		buffer = rb_entry(n, struct binder_buffer, rb_node);
343 		if (buffer->pid != pid)
344 			continue;
345 		if (!buffer->async_transaction)
346 			continue;
347 		total_alloc_size += binder_alloc_buffer_size(alloc, buffer)
348 			+ sizeof(struct binder_buffer);
349 		num_buffers++;
350 	}
351 
352 	/*
353 	 * Warn if this pid has more than 50 transactions, or more than 50% of
354 	 * async space (which is 25% of total buffer size). Oneway spam is only
355 	 * detected when the threshold is exceeded.
356 	 */
357 	if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
358 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
359 			     "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
360 			      alloc->pid, pid, num_buffers, total_alloc_size);
361 		if (!alloc->oneway_spam_detected) {
362 			alloc->oneway_spam_detected = true;
363 			return true;
364 		}
365 	}
366 	return false;
367 }
368 
369 static struct binder_buffer *binder_alloc_new_buf_locked(
370 				struct binder_alloc *alloc,
371 				size_t data_size,
372 				size_t offsets_size,
373 				size_t extra_buffers_size,
374 				int is_async,
375 				int pid)
376 {
377 	struct rb_node *n = alloc->free_buffers.rb_node;
378 	struct binder_buffer *buffer;
379 	size_t buffer_size;
380 	struct rb_node *best_fit = NULL;
381 	void __user *has_page_addr;
382 	void __user *end_page_addr;
383 	size_t size, data_offsets_size;
384 	int ret;
385 
386 	/* Check binder_alloc is fully initialized */
387 	if (!binder_alloc_get_vma(alloc)) {
388 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
389 				   "%d: binder_alloc_buf, no vma\n",
390 				   alloc->pid);
391 		return ERR_PTR(-ESRCH);
392 	}
393 
394 	data_offsets_size = ALIGN(data_size, sizeof(void *)) +
395 		ALIGN(offsets_size, sizeof(void *));
396 
397 	if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
398 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
399 				"%d: got transaction with invalid size %zd-%zd\n",
400 				alloc->pid, data_size, offsets_size);
401 		return ERR_PTR(-EINVAL);
402 	}
403 	size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
404 	if (size < data_offsets_size || size < extra_buffers_size) {
405 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
406 				"%d: got transaction with invalid extra_buffers_size %zd\n",
407 				alloc->pid, extra_buffers_size);
408 		return ERR_PTR(-EINVAL);
409 	}
410 	if (is_async &&
411 	    alloc->free_async_space < size + sizeof(struct binder_buffer)) {
412 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
413 			     "%d: binder_alloc_buf size %zd failed, no async space left\n",
414 			      alloc->pid, size);
415 		return ERR_PTR(-ENOSPC);
416 	}
417 
418 	/* Pad 0-size buffers so they get assigned unique addresses */
419 	size = max(size, sizeof(void *));
420 
421 	while (n) {
422 		buffer = rb_entry(n, struct binder_buffer, rb_node);
423 		BUG_ON(!buffer->free);
424 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
425 
426 		if (size < buffer_size) {
427 			best_fit = n;
428 			n = n->rb_left;
429 		} else if (size > buffer_size)
430 			n = n->rb_right;
431 		else {
432 			best_fit = n;
433 			break;
434 		}
435 	}
436 	if (best_fit == NULL) {
437 		size_t allocated_buffers = 0;
438 		size_t largest_alloc_size = 0;
439 		size_t total_alloc_size = 0;
440 		size_t free_buffers = 0;
441 		size_t largest_free_size = 0;
442 		size_t total_free_size = 0;
443 
444 		for (n = rb_first(&alloc->allocated_buffers); n != NULL;
445 		     n = rb_next(n)) {
446 			buffer = rb_entry(n, struct binder_buffer, rb_node);
447 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
448 			allocated_buffers++;
449 			total_alloc_size += buffer_size;
450 			if (buffer_size > largest_alloc_size)
451 				largest_alloc_size = buffer_size;
452 		}
453 		for (n = rb_first(&alloc->free_buffers); n != NULL;
454 		     n = rb_next(n)) {
455 			buffer = rb_entry(n, struct binder_buffer, rb_node);
456 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
457 			free_buffers++;
458 			total_free_size += buffer_size;
459 			if (buffer_size > largest_free_size)
460 				largest_free_size = buffer_size;
461 		}
462 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
463 				   "%d: binder_alloc_buf size %zd failed, no address space\n",
464 				   alloc->pid, size);
465 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
466 				   "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
467 				   total_alloc_size, allocated_buffers,
468 				   largest_alloc_size, total_free_size,
469 				   free_buffers, largest_free_size);
470 		return ERR_PTR(-ENOSPC);
471 	}
472 	if (n == NULL) {
473 		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
474 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
475 	}
476 
477 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
478 		     "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
479 		      alloc->pid, size, buffer, buffer_size);
480 
481 	has_page_addr = (void __user *)
482 		(((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
483 	WARN_ON(n && buffer_size != size);
484 	end_page_addr =
485 		(void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
486 	if (end_page_addr > has_page_addr)
487 		end_page_addr = has_page_addr;
488 	ret = binder_update_page_range(alloc, 1, (void __user *)
489 		PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr);
490 	if (ret)
491 		return ERR_PTR(ret);
492 
493 	if (buffer_size != size) {
494 		struct binder_buffer *new_buffer;
495 
496 		new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
497 		if (!new_buffer) {
498 			pr_err("%s: %d failed to alloc new buffer struct\n",
499 			       __func__, alloc->pid);
500 			goto err_alloc_buf_struct_failed;
501 		}
502 		new_buffer->user_data = (u8 __user *)buffer->user_data + size;
503 		list_add(&new_buffer->entry, &buffer->entry);
504 		new_buffer->free = 1;
505 		binder_insert_free_buffer(alloc, new_buffer);
506 	}
507 
508 	rb_erase(best_fit, &alloc->free_buffers);
509 	buffer->free = 0;
510 	buffer->allow_user_free = 0;
511 	binder_insert_allocated_buffer_locked(alloc, buffer);
512 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
513 		     "%d: binder_alloc_buf size %zd got %pK\n",
514 		      alloc->pid, size, buffer);
515 	buffer->data_size = data_size;
516 	buffer->offsets_size = offsets_size;
517 	buffer->async_transaction = is_async;
518 	buffer->extra_buffers_size = extra_buffers_size;
519 	buffer->pid = pid;
520 	buffer->oneway_spam_suspect = false;
521 	if (is_async) {
522 		alloc->free_async_space -= size + sizeof(struct binder_buffer);
523 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
524 			     "%d: binder_alloc_buf size %zd async free %zd\n",
525 			      alloc->pid, size, alloc->free_async_space);
526 		if (alloc->free_async_space < alloc->buffer_size / 10) {
527 			/*
528 			 * Start detecting spammers once we have less than 20%
529 			 * of async space left (which is less than 10% of total
530 			 * buffer size).
531 			 */
532 			buffer->oneway_spam_suspect = debug_low_async_space_locked(alloc, pid);
533 		} else {
534 			alloc->oneway_spam_detected = false;
535 		}
536 	}
537 	return buffer;
538 
539 err_alloc_buf_struct_failed:
540 	binder_update_page_range(alloc, 0, (void __user *)
541 				 PAGE_ALIGN((uintptr_t)buffer->user_data),
542 				 end_page_addr);
543 	return ERR_PTR(-ENOMEM);
544 }
545 
546 /**
547  * binder_alloc_new_buf() - Allocate a new binder buffer
548  * @alloc:              binder_alloc for this proc
549  * @data_size:          size of user data buffer
550  * @offsets_size:       user specified buffer offset
551  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
552  * @is_async:           buffer for async transaction
553  * @pid:				pid to attribute allocation to (used for debugging)
554  *
555  * Allocate a new buffer given the requested sizes. Returns
556  * the kernel version of the buffer pointer. The size allocated
557  * is the sum of the three given sizes (each rounded up to
558  * pointer-sized boundary)
559  *
560  * Return:	The allocated buffer or %NULL if error
561  */
562 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
563 					   size_t data_size,
564 					   size_t offsets_size,
565 					   size_t extra_buffers_size,
566 					   int is_async,
567 					   int pid)
568 {
569 	struct binder_buffer *buffer;
570 
571 	mutex_lock(&alloc->mutex);
572 	buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
573 					     extra_buffers_size, is_async, pid);
574 	mutex_unlock(&alloc->mutex);
575 	return buffer;
576 }
577 
578 static void __user *buffer_start_page(struct binder_buffer *buffer)
579 {
580 	return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
581 }
582 
583 static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
584 {
585 	return (void __user *)
586 		(((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
587 }
588 
589 static void binder_delete_free_buffer(struct binder_alloc *alloc,
590 				      struct binder_buffer *buffer)
591 {
592 	struct binder_buffer *prev, *next = NULL;
593 	bool to_free = true;
594 
595 	BUG_ON(alloc->buffers.next == &buffer->entry);
596 	prev = binder_buffer_prev(buffer);
597 	BUG_ON(!prev->free);
598 	if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
599 		to_free = false;
600 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
601 				   "%d: merge free, buffer %pK share page with %pK\n",
602 				   alloc->pid, buffer->user_data,
603 				   prev->user_data);
604 	}
605 
606 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
607 		next = binder_buffer_next(buffer);
608 		if (buffer_start_page(next) == buffer_start_page(buffer)) {
609 			to_free = false;
610 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
611 					   "%d: merge free, buffer %pK share page with %pK\n",
612 					   alloc->pid,
613 					   buffer->user_data,
614 					   next->user_data);
615 		}
616 	}
617 
618 	if (PAGE_ALIGNED(buffer->user_data)) {
619 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
620 				   "%d: merge free, buffer start %pK is page aligned\n",
621 				   alloc->pid, buffer->user_data);
622 		to_free = false;
623 	}
624 
625 	if (to_free) {
626 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
627 				   "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
628 				   alloc->pid, buffer->user_data,
629 				   prev->user_data,
630 				   next ? next->user_data : NULL);
631 		binder_update_page_range(alloc, 0, buffer_start_page(buffer),
632 					 buffer_start_page(buffer) + PAGE_SIZE);
633 	}
634 	list_del(&buffer->entry);
635 	kfree(buffer);
636 }
637 
638 static void binder_free_buf_locked(struct binder_alloc *alloc,
639 				   struct binder_buffer *buffer)
640 {
641 	size_t size, buffer_size;
642 
643 	buffer_size = binder_alloc_buffer_size(alloc, buffer);
644 
645 	size = ALIGN(buffer->data_size, sizeof(void *)) +
646 		ALIGN(buffer->offsets_size, sizeof(void *)) +
647 		ALIGN(buffer->extra_buffers_size, sizeof(void *));
648 
649 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
650 		     "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
651 		      alloc->pid, buffer, size, buffer_size);
652 
653 	BUG_ON(buffer->free);
654 	BUG_ON(size > buffer_size);
655 	BUG_ON(buffer->transaction != NULL);
656 	BUG_ON(buffer->user_data < alloc->buffer);
657 	BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
658 
659 	if (buffer->async_transaction) {
660 		alloc->free_async_space += buffer_size + sizeof(struct binder_buffer);
661 
662 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
663 			     "%d: binder_free_buf size %zd async free %zd\n",
664 			      alloc->pid, size, alloc->free_async_space);
665 	}
666 
667 	binder_update_page_range(alloc, 0,
668 		(void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
669 		(void __user *)(((uintptr_t)
670 			  buffer->user_data + buffer_size) & PAGE_MASK));
671 
672 	rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
673 	buffer->free = 1;
674 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
675 		struct binder_buffer *next = binder_buffer_next(buffer);
676 
677 		if (next->free) {
678 			rb_erase(&next->rb_node, &alloc->free_buffers);
679 			binder_delete_free_buffer(alloc, next);
680 		}
681 	}
682 	if (alloc->buffers.next != &buffer->entry) {
683 		struct binder_buffer *prev = binder_buffer_prev(buffer);
684 
685 		if (prev->free) {
686 			binder_delete_free_buffer(alloc, buffer);
687 			rb_erase(&prev->rb_node, &alloc->free_buffers);
688 			buffer = prev;
689 		}
690 	}
691 	binder_insert_free_buffer(alloc, buffer);
692 }
693 
694 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
695 				   struct binder_buffer *buffer);
696 /**
697  * binder_alloc_free_buf() - free a binder buffer
698  * @alloc:	binder_alloc for this proc
699  * @buffer:	kernel pointer to buffer
700  *
701  * Free the buffer allocated via binder_alloc_new_buf()
702  */
703 void binder_alloc_free_buf(struct binder_alloc *alloc,
704 			    struct binder_buffer *buffer)
705 {
706 	/*
707 	 * We could eliminate the call to binder_alloc_clear_buf()
708 	 * from binder_alloc_deferred_release() by moving this to
709 	 * binder_alloc_free_buf_locked(). However, that could
710 	 * increase contention for the alloc mutex if clear_on_free
711 	 * is used frequently for large buffers. The mutex is not
712 	 * needed for correctness here.
713 	 */
714 	if (buffer->clear_on_free) {
715 		binder_alloc_clear_buf(alloc, buffer);
716 		buffer->clear_on_free = false;
717 	}
718 	mutex_lock(&alloc->mutex);
719 	binder_free_buf_locked(alloc, buffer);
720 	mutex_unlock(&alloc->mutex);
721 }
722 
723 /**
724  * binder_alloc_mmap_handler() - map virtual address space for proc
725  * @alloc:	alloc structure for this proc
726  * @vma:	vma passed to mmap()
727  *
728  * Called by binder_mmap() to initialize the space specified in
729  * vma for allocating binder buffers
730  *
731  * Return:
732  *      0 = success
733  *      -EBUSY = address space already mapped
734  *      -ENOMEM = failed to map memory to given address space
735  */
736 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
737 			      struct vm_area_struct *vma)
738 {
739 	int ret;
740 	const char *failure_string;
741 	struct binder_buffer *buffer;
742 
743 	if (unlikely(vma->vm_mm != alloc->mm)) {
744 		ret = -EINVAL;
745 		failure_string = "invalid vma->vm_mm";
746 		goto err_invalid_mm;
747 	}
748 
749 	mutex_lock(&binder_alloc_mmap_lock);
750 	if (alloc->buffer_size) {
751 		ret = -EBUSY;
752 		failure_string = "already mapped";
753 		goto err_already_mapped;
754 	}
755 	alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
756 				   SZ_4M);
757 	mutex_unlock(&binder_alloc_mmap_lock);
758 
759 	alloc->buffer = (void __user *)vma->vm_start;
760 
761 	alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
762 			       sizeof(alloc->pages[0]),
763 			       GFP_KERNEL);
764 	if (alloc->pages == NULL) {
765 		ret = -ENOMEM;
766 		failure_string = "alloc page array";
767 		goto err_alloc_pages_failed;
768 	}
769 
770 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
771 	if (!buffer) {
772 		ret = -ENOMEM;
773 		failure_string = "alloc buffer struct";
774 		goto err_alloc_buf_struct_failed;
775 	}
776 
777 	buffer->user_data = alloc->buffer;
778 	list_add(&buffer->entry, &alloc->buffers);
779 	buffer->free = 1;
780 	binder_insert_free_buffer(alloc, buffer);
781 	alloc->free_async_space = alloc->buffer_size / 2;
782 
783 	/* Signal binder_alloc is fully initialized */
784 	binder_alloc_set_vma(alloc, vma);
785 
786 	return 0;
787 
788 err_alloc_buf_struct_failed:
789 	kfree(alloc->pages);
790 	alloc->pages = NULL;
791 err_alloc_pages_failed:
792 	alloc->buffer = NULL;
793 	mutex_lock(&binder_alloc_mmap_lock);
794 	alloc->buffer_size = 0;
795 err_already_mapped:
796 	mutex_unlock(&binder_alloc_mmap_lock);
797 err_invalid_mm:
798 	binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
799 			   "%s: %d %lx-%lx %s failed %d\n", __func__,
800 			   alloc->pid, vma->vm_start, vma->vm_end,
801 			   failure_string, ret);
802 	return ret;
803 }
804 
805 
806 void binder_alloc_deferred_release(struct binder_alloc *alloc)
807 {
808 	struct rb_node *n;
809 	int buffers, page_count;
810 	struct binder_buffer *buffer;
811 
812 	buffers = 0;
813 	mutex_lock(&alloc->mutex);
814 	BUG_ON(alloc->vma);
815 
816 	while ((n = rb_first(&alloc->allocated_buffers))) {
817 		buffer = rb_entry(n, struct binder_buffer, rb_node);
818 
819 		/* Transaction should already have been freed */
820 		BUG_ON(buffer->transaction);
821 
822 		if (buffer->clear_on_free) {
823 			binder_alloc_clear_buf(alloc, buffer);
824 			buffer->clear_on_free = false;
825 		}
826 		binder_free_buf_locked(alloc, buffer);
827 		buffers++;
828 	}
829 
830 	while (!list_empty(&alloc->buffers)) {
831 		buffer = list_first_entry(&alloc->buffers,
832 					  struct binder_buffer, entry);
833 		WARN_ON(!buffer->free);
834 
835 		list_del(&buffer->entry);
836 		WARN_ON_ONCE(!list_empty(&alloc->buffers));
837 		kfree(buffer);
838 	}
839 
840 	page_count = 0;
841 	if (alloc->pages) {
842 		int i;
843 
844 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
845 			void __user *page_addr;
846 			bool on_lru;
847 
848 			if (!alloc->pages[i].page_ptr)
849 				continue;
850 
851 			on_lru = list_lru_del(&binder_alloc_lru,
852 					      &alloc->pages[i].lru);
853 			page_addr = alloc->buffer + i * PAGE_SIZE;
854 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
855 				     "%s: %d: page %d at %pK %s\n",
856 				     __func__, alloc->pid, i, page_addr,
857 				     on_lru ? "on lru" : "active");
858 			__free_page(alloc->pages[i].page_ptr);
859 			page_count++;
860 		}
861 		kfree(alloc->pages);
862 	}
863 	mutex_unlock(&alloc->mutex);
864 	if (alloc->mm)
865 		mmdrop(alloc->mm);
866 
867 	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
868 		     "%s: %d buffers %d, pages %d\n",
869 		     __func__, alloc->pid, buffers, page_count);
870 }
871 
872 static void print_binder_buffer(struct seq_file *m, const char *prefix,
873 				struct binder_buffer *buffer)
874 {
875 	seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
876 		   prefix, buffer->debug_id, buffer->user_data,
877 		   buffer->data_size, buffer->offsets_size,
878 		   buffer->extra_buffers_size,
879 		   buffer->transaction ? "active" : "delivered");
880 }
881 
882 /**
883  * binder_alloc_print_allocated() - print buffer info
884  * @m:     seq_file for output via seq_printf()
885  * @alloc: binder_alloc for this proc
886  *
887  * Prints information about every buffer associated with
888  * the binder_alloc state to the given seq_file
889  */
890 void binder_alloc_print_allocated(struct seq_file *m,
891 				  struct binder_alloc *alloc)
892 {
893 	struct rb_node *n;
894 
895 	mutex_lock(&alloc->mutex);
896 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
897 		print_binder_buffer(m, "  buffer",
898 				    rb_entry(n, struct binder_buffer, rb_node));
899 	mutex_unlock(&alloc->mutex);
900 }
901 
902 /**
903  * binder_alloc_print_pages() - print page usage
904  * @m:     seq_file for output via seq_printf()
905  * @alloc: binder_alloc for this proc
906  */
907 void binder_alloc_print_pages(struct seq_file *m,
908 			      struct binder_alloc *alloc)
909 {
910 	struct binder_lru_page *page;
911 	int i;
912 	int active = 0;
913 	int lru = 0;
914 	int free = 0;
915 
916 	mutex_lock(&alloc->mutex);
917 	/*
918 	 * Make sure the binder_alloc is fully initialized, otherwise we might
919 	 * read inconsistent state.
920 	 */
921 	if (binder_alloc_get_vma(alloc) != NULL) {
922 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
923 			page = &alloc->pages[i];
924 			if (!page->page_ptr)
925 				free++;
926 			else if (list_empty(&page->lru))
927 				active++;
928 			else
929 				lru++;
930 		}
931 	}
932 	mutex_unlock(&alloc->mutex);
933 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
934 	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
935 }
936 
937 /**
938  * binder_alloc_get_allocated_count() - return count of buffers
939  * @alloc: binder_alloc for this proc
940  *
941  * Return: count of allocated buffers
942  */
943 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
944 {
945 	struct rb_node *n;
946 	int count = 0;
947 
948 	mutex_lock(&alloc->mutex);
949 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
950 		count++;
951 	mutex_unlock(&alloc->mutex);
952 	return count;
953 }
954 
955 
956 /**
957  * binder_alloc_vma_close() - invalidate address space
958  * @alloc: binder_alloc for this proc
959  *
960  * Called from binder_vma_close() when releasing address space.
961  * Clears alloc->vma to prevent new incoming transactions from
962  * allocating more buffers.
963  */
964 void binder_alloc_vma_close(struct binder_alloc *alloc)
965 {
966 	binder_alloc_set_vma(alloc, NULL);
967 }
968 
969 /**
970  * binder_alloc_free_page() - shrinker callback to free pages
971  * @item:   item to free
972  * @lock:   lock protecting the item
973  * @cb_arg: callback argument
974  *
975  * Called from list_lru_walk() in binder_shrink_scan() to free
976  * up pages when the system is under memory pressure.
977  */
978 enum lru_status binder_alloc_free_page(struct list_head *item,
979 				       struct list_lru_one *lru,
980 				       spinlock_t *lock,
981 				       void *cb_arg)
982 	__must_hold(lock)
983 {
984 	struct mm_struct *mm = NULL;
985 	struct binder_lru_page *page = container_of(item,
986 						    struct binder_lru_page,
987 						    lru);
988 	struct binder_alloc *alloc;
989 	uintptr_t page_addr;
990 	size_t index;
991 	struct vm_area_struct *vma;
992 
993 	alloc = page->alloc;
994 	if (!mutex_trylock(&alloc->mutex))
995 		goto err_get_alloc_mutex_failed;
996 
997 	if (!page->page_ptr)
998 		goto err_page_already_freed;
999 
1000 	index = page - alloc->pages;
1001 	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
1002 
1003 	mm = alloc->mm;
1004 	if (!mmget_not_zero(mm))
1005 		goto err_mmget;
1006 	if (!mmap_read_trylock(mm))
1007 		goto err_mmap_read_lock_failed;
1008 	vma = binder_alloc_get_vma(alloc);
1009 
1010 	list_lru_isolate(lru, item);
1011 	spin_unlock(lock);
1012 
1013 	if (vma) {
1014 		trace_binder_unmap_user_start(alloc, index);
1015 
1016 		zap_page_range_single(vma, page_addr, PAGE_SIZE, NULL);
1017 
1018 		trace_binder_unmap_user_end(alloc, index);
1019 	}
1020 	mmap_read_unlock(mm);
1021 	mmput_async(mm);
1022 
1023 	trace_binder_unmap_kernel_start(alloc, index);
1024 
1025 	__free_page(page->page_ptr);
1026 	page->page_ptr = NULL;
1027 
1028 	trace_binder_unmap_kernel_end(alloc, index);
1029 
1030 	spin_lock(lock);
1031 	mutex_unlock(&alloc->mutex);
1032 	return LRU_REMOVED_RETRY;
1033 
1034 err_mmap_read_lock_failed:
1035 	mmput_async(mm);
1036 err_mmget:
1037 err_page_already_freed:
1038 	mutex_unlock(&alloc->mutex);
1039 err_get_alloc_mutex_failed:
1040 	return LRU_SKIP;
1041 }
1042 
1043 static unsigned long
1044 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1045 {
1046 	return list_lru_count(&binder_alloc_lru);
1047 }
1048 
1049 static unsigned long
1050 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1051 {
1052 	return list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
1053 			    NULL, sc->nr_to_scan);
1054 }
1055 
1056 static struct shrinker binder_shrinker = {
1057 	.count_objects = binder_shrink_count,
1058 	.scan_objects = binder_shrink_scan,
1059 	.seeks = DEFAULT_SEEKS,
1060 };
1061 
1062 /**
1063  * binder_alloc_init() - called by binder_open() for per-proc initialization
1064  * @alloc: binder_alloc for this proc
1065  *
1066  * Called from binder_open() to initialize binder_alloc fields for
1067  * new binder proc
1068  */
1069 void binder_alloc_init(struct binder_alloc *alloc)
1070 {
1071 	alloc->pid = current->group_leader->pid;
1072 	alloc->mm = current->mm;
1073 	mmgrab(alloc->mm);
1074 	mutex_init(&alloc->mutex);
1075 	INIT_LIST_HEAD(&alloc->buffers);
1076 }
1077 
1078 int binder_alloc_shrinker_init(void)
1079 {
1080 	int ret = list_lru_init(&binder_alloc_lru);
1081 
1082 	if (ret == 0) {
1083 		ret = register_shrinker(&binder_shrinker, "android-binder");
1084 		if (ret)
1085 			list_lru_destroy(&binder_alloc_lru);
1086 	}
1087 	return ret;
1088 }
1089 
1090 void binder_alloc_shrinker_exit(void)
1091 {
1092 	unregister_shrinker(&binder_shrinker);
1093 	list_lru_destroy(&binder_alloc_lru);
1094 }
1095 
1096 /**
1097  * check_buffer() - verify that buffer/offset is safe to access
1098  * @alloc: binder_alloc for this proc
1099  * @buffer: binder buffer to be accessed
1100  * @offset: offset into @buffer data
1101  * @bytes: bytes to access from offset
1102  *
1103  * Check that the @offset/@bytes are within the size of the given
1104  * @buffer and that the buffer is currently active and not freeable.
1105  * Offsets must also be multiples of sizeof(u32). The kernel is
1106  * allowed to touch the buffer in two cases:
1107  *
1108  * 1) when the buffer is being created:
1109  *     (buffer->free == 0 && buffer->allow_user_free == 0)
1110  * 2) when the buffer is being torn down:
1111  *     (buffer->free == 0 && buffer->transaction == NULL).
1112  *
1113  * Return: true if the buffer is safe to access
1114  */
1115 static inline bool check_buffer(struct binder_alloc *alloc,
1116 				struct binder_buffer *buffer,
1117 				binder_size_t offset, size_t bytes)
1118 {
1119 	size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1120 
1121 	return buffer_size >= bytes &&
1122 		offset <= buffer_size - bytes &&
1123 		IS_ALIGNED(offset, sizeof(u32)) &&
1124 		!buffer->free &&
1125 		(!buffer->allow_user_free || !buffer->transaction);
1126 }
1127 
1128 /**
1129  * binder_alloc_get_page() - get kernel pointer for given buffer offset
1130  * @alloc: binder_alloc for this proc
1131  * @buffer: binder buffer to be accessed
1132  * @buffer_offset: offset into @buffer data
1133  * @pgoffp: address to copy final page offset to
1134  *
1135  * Lookup the struct page corresponding to the address
1136  * at @buffer_offset into @buffer->user_data. If @pgoffp is not
1137  * NULL, the byte-offset into the page is written there.
1138  *
1139  * The caller is responsible to ensure that the offset points
1140  * to a valid address within the @buffer and that @buffer is
1141  * not freeable by the user. Since it can't be freed, we are
1142  * guaranteed that the corresponding elements of @alloc->pages[]
1143  * cannot change.
1144  *
1145  * Return: struct page
1146  */
1147 static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
1148 					  struct binder_buffer *buffer,
1149 					  binder_size_t buffer_offset,
1150 					  pgoff_t *pgoffp)
1151 {
1152 	binder_size_t buffer_space_offset = buffer_offset +
1153 		(buffer->user_data - alloc->buffer);
1154 	pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
1155 	size_t index = buffer_space_offset >> PAGE_SHIFT;
1156 	struct binder_lru_page *lru_page;
1157 
1158 	lru_page = &alloc->pages[index];
1159 	*pgoffp = pgoff;
1160 	return lru_page->page_ptr;
1161 }
1162 
1163 /**
1164  * binder_alloc_clear_buf() - zero out buffer
1165  * @alloc: binder_alloc for this proc
1166  * @buffer: binder buffer to be cleared
1167  *
1168  * memset the given buffer to 0
1169  */
1170 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
1171 				   struct binder_buffer *buffer)
1172 {
1173 	size_t bytes = binder_alloc_buffer_size(alloc, buffer);
1174 	binder_size_t buffer_offset = 0;
1175 
1176 	while (bytes) {
1177 		unsigned long size;
1178 		struct page *page;
1179 		pgoff_t pgoff;
1180 
1181 		page = binder_alloc_get_page(alloc, buffer,
1182 					     buffer_offset, &pgoff);
1183 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1184 		memset_page(page, pgoff, 0, size);
1185 		bytes -= size;
1186 		buffer_offset += size;
1187 	}
1188 }
1189 
1190 /**
1191  * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1192  * @alloc: binder_alloc for this proc
1193  * @buffer: binder buffer to be accessed
1194  * @buffer_offset: offset into @buffer data
1195  * @from: userspace pointer to source buffer
1196  * @bytes: bytes to copy
1197  *
1198  * Copy bytes from source userspace to target buffer.
1199  *
1200  * Return: bytes remaining to be copied
1201  */
1202 unsigned long
1203 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1204 				 struct binder_buffer *buffer,
1205 				 binder_size_t buffer_offset,
1206 				 const void __user *from,
1207 				 size_t bytes)
1208 {
1209 	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1210 		return bytes;
1211 
1212 	while (bytes) {
1213 		unsigned long size;
1214 		unsigned long ret;
1215 		struct page *page;
1216 		pgoff_t pgoff;
1217 		void *kptr;
1218 
1219 		page = binder_alloc_get_page(alloc, buffer,
1220 					     buffer_offset, &pgoff);
1221 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1222 		kptr = kmap_local_page(page) + pgoff;
1223 		ret = copy_from_user(kptr, from, size);
1224 		kunmap_local(kptr);
1225 		if (ret)
1226 			return bytes - size + ret;
1227 		bytes -= size;
1228 		from += size;
1229 		buffer_offset += size;
1230 	}
1231 	return 0;
1232 }
1233 
1234 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1235 				       bool to_buffer,
1236 				       struct binder_buffer *buffer,
1237 				       binder_size_t buffer_offset,
1238 				       void *ptr,
1239 				       size_t bytes)
1240 {
1241 	/* All copies must be 32-bit aligned and 32-bit size */
1242 	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1243 		return -EINVAL;
1244 
1245 	while (bytes) {
1246 		unsigned long size;
1247 		struct page *page;
1248 		pgoff_t pgoff;
1249 
1250 		page = binder_alloc_get_page(alloc, buffer,
1251 					     buffer_offset, &pgoff);
1252 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1253 		if (to_buffer)
1254 			memcpy_to_page(page, pgoff, ptr, size);
1255 		else
1256 			memcpy_from_page(ptr, page, pgoff, size);
1257 		bytes -= size;
1258 		pgoff = 0;
1259 		ptr = ptr + size;
1260 		buffer_offset += size;
1261 	}
1262 	return 0;
1263 }
1264 
1265 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1266 				struct binder_buffer *buffer,
1267 				binder_size_t buffer_offset,
1268 				void *src,
1269 				size_t bytes)
1270 {
1271 	return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1272 					   src, bytes);
1273 }
1274 
1275 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1276 				  void *dest,
1277 				  struct binder_buffer *buffer,
1278 				  binder_size_t buffer_offset,
1279 				  size_t bytes)
1280 {
1281 	return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1282 					   dest, bytes);
1283 }
1284 
1285