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->vma_vm_mm))
212 		mm = alloc->vma_vm_mm;
213 
214 	if (mm) {
215 		down_read(&mm->mmap_sem);
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 		up_read(&mm->mmap_sem);
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 		up_read(&mm->mmap_sem);
307 		mmput(mm);
308 	}
309 	return vma ? -ENOMEM : -ESRCH;
310 }
311 
312 
313 static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
314 		struct vm_area_struct *vma)
315 {
316 	if (vma)
317 		alloc->vma_vm_mm = vma->vm_mm;
318 	/*
319 	 * If we see alloc->vma is not NULL, buffer data structures set up
320 	 * completely. Look at smp_rmb side binder_alloc_get_vma.
321 	 * We also want to guarantee new alloc->vma_vm_mm is always visible
322 	 * if alloc->vma is set.
323 	 */
324 	smp_wmb();
325 	alloc->vma = vma;
326 }
327 
328 static inline struct vm_area_struct *binder_alloc_get_vma(
329 		struct binder_alloc *alloc)
330 {
331 	struct vm_area_struct *vma = NULL;
332 
333 	if (alloc->vma) {
334 		/* Look at description in binder_alloc_set_vma */
335 		smp_rmb();
336 		vma = alloc->vma;
337 	}
338 	return vma;
339 }
340 
341 static struct binder_buffer *binder_alloc_new_buf_locked(
342 				struct binder_alloc *alloc,
343 				size_t data_size,
344 				size_t offsets_size,
345 				size_t extra_buffers_size,
346 				int is_async)
347 {
348 	struct rb_node *n = alloc->free_buffers.rb_node;
349 	struct binder_buffer *buffer;
350 	size_t buffer_size;
351 	struct rb_node *best_fit = NULL;
352 	void __user *has_page_addr;
353 	void __user *end_page_addr;
354 	size_t size, data_offsets_size;
355 	int ret;
356 
357 	if (!binder_alloc_get_vma(alloc)) {
358 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
359 				   "%d: binder_alloc_buf, no vma\n",
360 				   alloc->pid);
361 		return ERR_PTR(-ESRCH);
362 	}
363 
364 	data_offsets_size = ALIGN(data_size, sizeof(void *)) +
365 		ALIGN(offsets_size, sizeof(void *));
366 
367 	if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
368 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
369 				"%d: got transaction with invalid size %zd-%zd\n",
370 				alloc->pid, data_size, offsets_size);
371 		return ERR_PTR(-EINVAL);
372 	}
373 	size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
374 	if (size < data_offsets_size || size < extra_buffers_size) {
375 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
376 				"%d: got transaction with invalid extra_buffers_size %zd\n",
377 				alloc->pid, extra_buffers_size);
378 		return ERR_PTR(-EINVAL);
379 	}
380 	if (is_async &&
381 	    alloc->free_async_space < size + sizeof(struct binder_buffer)) {
382 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
383 			     "%d: binder_alloc_buf size %zd failed, no async space left\n",
384 			      alloc->pid, size);
385 		return ERR_PTR(-ENOSPC);
386 	}
387 
388 	/* Pad 0-size buffers so they get assigned unique addresses */
389 	size = max(size, sizeof(void *));
390 
391 	while (n) {
392 		buffer = rb_entry(n, struct binder_buffer, rb_node);
393 		BUG_ON(!buffer->free);
394 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
395 
396 		if (size < buffer_size) {
397 			best_fit = n;
398 			n = n->rb_left;
399 		} else if (size > buffer_size)
400 			n = n->rb_right;
401 		else {
402 			best_fit = n;
403 			break;
404 		}
405 	}
406 	if (best_fit == NULL) {
407 		size_t allocated_buffers = 0;
408 		size_t largest_alloc_size = 0;
409 		size_t total_alloc_size = 0;
410 		size_t free_buffers = 0;
411 		size_t largest_free_size = 0;
412 		size_t total_free_size = 0;
413 
414 		for (n = rb_first(&alloc->allocated_buffers); n != NULL;
415 		     n = rb_next(n)) {
416 			buffer = rb_entry(n, struct binder_buffer, rb_node);
417 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
418 			allocated_buffers++;
419 			total_alloc_size += buffer_size;
420 			if (buffer_size > largest_alloc_size)
421 				largest_alloc_size = buffer_size;
422 		}
423 		for (n = rb_first(&alloc->free_buffers); n != NULL;
424 		     n = rb_next(n)) {
425 			buffer = rb_entry(n, struct binder_buffer, rb_node);
426 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
427 			free_buffers++;
428 			total_free_size += buffer_size;
429 			if (buffer_size > largest_free_size)
430 				largest_free_size = buffer_size;
431 		}
432 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
433 				   "%d: binder_alloc_buf size %zd failed, no address space\n",
434 				   alloc->pid, size);
435 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
436 				   "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
437 				   total_alloc_size, allocated_buffers,
438 				   largest_alloc_size, total_free_size,
439 				   free_buffers, largest_free_size);
440 		return ERR_PTR(-ENOSPC);
441 	}
442 	if (n == NULL) {
443 		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
444 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
445 	}
446 
447 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
448 		     "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
449 		      alloc->pid, size, buffer, buffer_size);
450 
451 	has_page_addr = (void __user *)
452 		(((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
453 	WARN_ON(n && buffer_size != size);
454 	end_page_addr =
455 		(void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
456 	if (end_page_addr > has_page_addr)
457 		end_page_addr = has_page_addr;
458 	ret = binder_update_page_range(alloc, 1, (void __user *)
459 		PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr);
460 	if (ret)
461 		return ERR_PTR(ret);
462 
463 	if (buffer_size != size) {
464 		struct binder_buffer *new_buffer;
465 
466 		new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
467 		if (!new_buffer) {
468 			pr_err("%s: %d failed to alloc new buffer struct\n",
469 			       __func__, alloc->pid);
470 			goto err_alloc_buf_struct_failed;
471 		}
472 		new_buffer->user_data = (u8 __user *)buffer->user_data + size;
473 		list_add(&new_buffer->entry, &buffer->entry);
474 		new_buffer->free = 1;
475 		binder_insert_free_buffer(alloc, new_buffer);
476 	}
477 
478 	rb_erase(best_fit, &alloc->free_buffers);
479 	buffer->free = 0;
480 	buffer->allow_user_free = 0;
481 	binder_insert_allocated_buffer_locked(alloc, buffer);
482 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
483 		     "%d: binder_alloc_buf size %zd got %pK\n",
484 		      alloc->pid, size, buffer);
485 	buffer->data_size = data_size;
486 	buffer->offsets_size = offsets_size;
487 	buffer->async_transaction = is_async;
488 	buffer->extra_buffers_size = extra_buffers_size;
489 	if (is_async) {
490 		alloc->free_async_space -= size + sizeof(struct binder_buffer);
491 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
492 			     "%d: binder_alloc_buf size %zd async free %zd\n",
493 			      alloc->pid, size, alloc->free_async_space);
494 	}
495 	return buffer;
496 
497 err_alloc_buf_struct_failed:
498 	binder_update_page_range(alloc, 0, (void __user *)
499 				 PAGE_ALIGN((uintptr_t)buffer->user_data),
500 				 end_page_addr);
501 	return ERR_PTR(-ENOMEM);
502 }
503 
504 /**
505  * binder_alloc_new_buf() - Allocate a new binder buffer
506  * @alloc:              binder_alloc for this proc
507  * @data_size:          size of user data buffer
508  * @offsets_size:       user specified buffer offset
509  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
510  * @is_async:           buffer for async transaction
511  *
512  * Allocate a new buffer given the requested sizes. Returns
513  * the kernel version of the buffer pointer. The size allocated
514  * is the sum of the three given sizes (each rounded up to
515  * pointer-sized boundary)
516  *
517  * Return:	The allocated buffer or %NULL if error
518  */
519 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
520 					   size_t data_size,
521 					   size_t offsets_size,
522 					   size_t extra_buffers_size,
523 					   int is_async)
524 {
525 	struct binder_buffer *buffer;
526 
527 	mutex_lock(&alloc->mutex);
528 	buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
529 					     extra_buffers_size, is_async);
530 	mutex_unlock(&alloc->mutex);
531 	return buffer;
532 }
533 
534 static void __user *buffer_start_page(struct binder_buffer *buffer)
535 {
536 	return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
537 }
538 
539 static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
540 {
541 	return (void __user *)
542 		(((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
543 }
544 
545 static void binder_delete_free_buffer(struct binder_alloc *alloc,
546 				      struct binder_buffer *buffer)
547 {
548 	struct binder_buffer *prev, *next = NULL;
549 	bool to_free = true;
550 	BUG_ON(alloc->buffers.next == &buffer->entry);
551 	prev = binder_buffer_prev(buffer);
552 	BUG_ON(!prev->free);
553 	if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
554 		to_free = false;
555 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
556 				   "%d: merge free, buffer %pK share page with %pK\n",
557 				   alloc->pid, buffer->user_data,
558 				   prev->user_data);
559 	}
560 
561 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
562 		next = binder_buffer_next(buffer);
563 		if (buffer_start_page(next) == buffer_start_page(buffer)) {
564 			to_free = false;
565 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
566 					   "%d: merge free, buffer %pK share page with %pK\n",
567 					   alloc->pid,
568 					   buffer->user_data,
569 					   next->user_data);
570 		}
571 	}
572 
573 	if (PAGE_ALIGNED(buffer->user_data)) {
574 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
575 				   "%d: merge free, buffer start %pK is page aligned\n",
576 				   alloc->pid, buffer->user_data);
577 		to_free = false;
578 	}
579 
580 	if (to_free) {
581 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
582 				   "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
583 				   alloc->pid, buffer->user_data,
584 				   prev->user_data,
585 				   next ? next->user_data : NULL);
586 		binder_update_page_range(alloc, 0, buffer_start_page(buffer),
587 					 buffer_start_page(buffer) + PAGE_SIZE);
588 	}
589 	list_del(&buffer->entry);
590 	kfree(buffer);
591 }
592 
593 static void binder_free_buf_locked(struct binder_alloc *alloc,
594 				   struct binder_buffer *buffer)
595 {
596 	size_t size, buffer_size;
597 
598 	buffer_size = binder_alloc_buffer_size(alloc, buffer);
599 
600 	size = ALIGN(buffer->data_size, sizeof(void *)) +
601 		ALIGN(buffer->offsets_size, sizeof(void *)) +
602 		ALIGN(buffer->extra_buffers_size, sizeof(void *));
603 
604 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
605 		     "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
606 		      alloc->pid, buffer, size, buffer_size);
607 
608 	BUG_ON(buffer->free);
609 	BUG_ON(size > buffer_size);
610 	BUG_ON(buffer->transaction != NULL);
611 	BUG_ON(buffer->user_data < alloc->buffer);
612 	BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
613 
614 	if (buffer->async_transaction) {
615 		alloc->free_async_space += size + sizeof(struct binder_buffer);
616 
617 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
618 			     "%d: binder_free_buf size %zd async free %zd\n",
619 			      alloc->pid, size, alloc->free_async_space);
620 	}
621 
622 	binder_update_page_range(alloc, 0,
623 		(void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
624 		(void __user *)(((uintptr_t)
625 			  buffer->user_data + buffer_size) & PAGE_MASK));
626 
627 	rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
628 	buffer->free = 1;
629 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
630 		struct binder_buffer *next = binder_buffer_next(buffer);
631 
632 		if (next->free) {
633 			rb_erase(&next->rb_node, &alloc->free_buffers);
634 			binder_delete_free_buffer(alloc, next);
635 		}
636 	}
637 	if (alloc->buffers.next != &buffer->entry) {
638 		struct binder_buffer *prev = binder_buffer_prev(buffer);
639 
640 		if (prev->free) {
641 			binder_delete_free_buffer(alloc, buffer);
642 			rb_erase(&prev->rb_node, &alloc->free_buffers);
643 			buffer = prev;
644 		}
645 	}
646 	binder_insert_free_buffer(alloc, buffer);
647 }
648 
649 /**
650  * binder_alloc_free_buf() - free a binder buffer
651  * @alloc:	binder_alloc for this proc
652  * @buffer:	kernel pointer to buffer
653  *
654  * Free the buffer allocated via binder_alloc_new_buffer()
655  */
656 void binder_alloc_free_buf(struct binder_alloc *alloc,
657 			    struct binder_buffer *buffer)
658 {
659 	mutex_lock(&alloc->mutex);
660 	binder_free_buf_locked(alloc, buffer);
661 	mutex_unlock(&alloc->mutex);
662 }
663 
664 /**
665  * binder_alloc_mmap_handler() - map virtual address space for proc
666  * @alloc:	alloc structure for this proc
667  * @vma:	vma passed to mmap()
668  *
669  * Called by binder_mmap() to initialize the space specified in
670  * vma for allocating binder buffers
671  *
672  * Return:
673  *      0 = success
674  *      -EBUSY = address space already mapped
675  *      -ENOMEM = failed to map memory to given address space
676  */
677 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
678 			      struct vm_area_struct *vma)
679 {
680 	int ret;
681 	const char *failure_string;
682 	struct binder_buffer *buffer;
683 
684 	mutex_lock(&binder_alloc_mmap_lock);
685 	if (alloc->buffer_size) {
686 		ret = -EBUSY;
687 		failure_string = "already mapped";
688 		goto err_already_mapped;
689 	}
690 	alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
691 				   SZ_4M);
692 	mutex_unlock(&binder_alloc_mmap_lock);
693 
694 	alloc->buffer = (void __user *)vma->vm_start;
695 
696 	alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
697 			       sizeof(alloc->pages[0]),
698 			       GFP_KERNEL);
699 	if (alloc->pages == NULL) {
700 		ret = -ENOMEM;
701 		failure_string = "alloc page array";
702 		goto err_alloc_pages_failed;
703 	}
704 
705 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
706 	if (!buffer) {
707 		ret = -ENOMEM;
708 		failure_string = "alloc buffer struct";
709 		goto err_alloc_buf_struct_failed;
710 	}
711 
712 	buffer->user_data = alloc->buffer;
713 	list_add(&buffer->entry, &alloc->buffers);
714 	buffer->free = 1;
715 	binder_insert_free_buffer(alloc, buffer);
716 	alloc->free_async_space = alloc->buffer_size / 2;
717 	binder_alloc_set_vma(alloc, vma);
718 	mmgrab(alloc->vma_vm_mm);
719 
720 	return 0;
721 
722 err_alloc_buf_struct_failed:
723 	kfree(alloc->pages);
724 	alloc->pages = NULL;
725 err_alloc_pages_failed:
726 	alloc->buffer = NULL;
727 	mutex_lock(&binder_alloc_mmap_lock);
728 	alloc->buffer_size = 0;
729 err_already_mapped:
730 	mutex_unlock(&binder_alloc_mmap_lock);
731 	binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
732 			   "%s: %d %lx-%lx %s failed %d\n", __func__,
733 			   alloc->pid, vma->vm_start, vma->vm_end,
734 			   failure_string, ret);
735 	return ret;
736 }
737 
738 
739 void binder_alloc_deferred_release(struct binder_alloc *alloc)
740 {
741 	struct rb_node *n;
742 	int buffers, page_count;
743 	struct binder_buffer *buffer;
744 
745 	buffers = 0;
746 	mutex_lock(&alloc->mutex);
747 	BUG_ON(alloc->vma);
748 
749 	while ((n = rb_first(&alloc->allocated_buffers))) {
750 		buffer = rb_entry(n, struct binder_buffer, rb_node);
751 
752 		/* Transaction should already have been freed */
753 		BUG_ON(buffer->transaction);
754 
755 		binder_free_buf_locked(alloc, buffer);
756 		buffers++;
757 	}
758 
759 	while (!list_empty(&alloc->buffers)) {
760 		buffer = list_first_entry(&alloc->buffers,
761 					  struct binder_buffer, entry);
762 		WARN_ON(!buffer->free);
763 
764 		list_del(&buffer->entry);
765 		WARN_ON_ONCE(!list_empty(&alloc->buffers));
766 		kfree(buffer);
767 	}
768 
769 	page_count = 0;
770 	if (alloc->pages) {
771 		int i;
772 
773 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
774 			void __user *page_addr;
775 			bool on_lru;
776 
777 			if (!alloc->pages[i].page_ptr)
778 				continue;
779 
780 			on_lru = list_lru_del(&binder_alloc_lru,
781 					      &alloc->pages[i].lru);
782 			page_addr = alloc->buffer + i * PAGE_SIZE;
783 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
784 				     "%s: %d: page %d at %pK %s\n",
785 				     __func__, alloc->pid, i, page_addr,
786 				     on_lru ? "on lru" : "active");
787 			__free_page(alloc->pages[i].page_ptr);
788 			page_count++;
789 		}
790 		kfree(alloc->pages);
791 	}
792 	mutex_unlock(&alloc->mutex);
793 	if (alloc->vma_vm_mm)
794 		mmdrop(alloc->vma_vm_mm);
795 
796 	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
797 		     "%s: %d buffers %d, pages %d\n",
798 		     __func__, alloc->pid, buffers, page_count);
799 }
800 
801 static void print_binder_buffer(struct seq_file *m, const char *prefix,
802 				struct binder_buffer *buffer)
803 {
804 	seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
805 		   prefix, buffer->debug_id, buffer->user_data,
806 		   buffer->data_size, buffer->offsets_size,
807 		   buffer->extra_buffers_size,
808 		   buffer->transaction ? "active" : "delivered");
809 }
810 
811 /**
812  * binder_alloc_print_allocated() - print buffer info
813  * @m:     seq_file for output via seq_printf()
814  * @alloc: binder_alloc for this proc
815  *
816  * Prints information about every buffer associated with
817  * the binder_alloc state to the given seq_file
818  */
819 void binder_alloc_print_allocated(struct seq_file *m,
820 				  struct binder_alloc *alloc)
821 {
822 	struct rb_node *n;
823 
824 	mutex_lock(&alloc->mutex);
825 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
826 		print_binder_buffer(m, "  buffer",
827 				    rb_entry(n, struct binder_buffer, rb_node));
828 	mutex_unlock(&alloc->mutex);
829 }
830 
831 /**
832  * binder_alloc_print_pages() - print page usage
833  * @m:     seq_file for output via seq_printf()
834  * @alloc: binder_alloc for this proc
835  */
836 void binder_alloc_print_pages(struct seq_file *m,
837 			      struct binder_alloc *alloc)
838 {
839 	struct binder_lru_page *page;
840 	int i;
841 	int active = 0;
842 	int lru = 0;
843 	int free = 0;
844 
845 	mutex_lock(&alloc->mutex);
846 	/*
847 	 * Make sure the binder_alloc is fully initialized, otherwise we might
848 	 * read inconsistent state.
849 	 */
850 	if (binder_alloc_get_vma(alloc) != NULL) {
851 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
852 			page = &alloc->pages[i];
853 			if (!page->page_ptr)
854 				free++;
855 			else if (list_empty(&page->lru))
856 				active++;
857 			else
858 				lru++;
859 		}
860 	}
861 	mutex_unlock(&alloc->mutex);
862 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
863 	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
864 }
865 
866 /**
867  * binder_alloc_get_allocated_count() - return count of buffers
868  * @alloc: binder_alloc for this proc
869  *
870  * Return: count of allocated buffers
871  */
872 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
873 {
874 	struct rb_node *n;
875 	int count = 0;
876 
877 	mutex_lock(&alloc->mutex);
878 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
879 		count++;
880 	mutex_unlock(&alloc->mutex);
881 	return count;
882 }
883 
884 
885 /**
886  * binder_alloc_vma_close() - invalidate address space
887  * @alloc: binder_alloc for this proc
888  *
889  * Called from binder_vma_close() when releasing address space.
890  * Clears alloc->vma to prevent new incoming transactions from
891  * allocating more buffers.
892  */
893 void binder_alloc_vma_close(struct binder_alloc *alloc)
894 {
895 	binder_alloc_set_vma(alloc, NULL);
896 }
897 
898 /**
899  * binder_alloc_free_page() - shrinker callback to free pages
900  * @item:   item to free
901  * @lock:   lock protecting the item
902  * @cb_arg: callback argument
903  *
904  * Called from list_lru_walk() in binder_shrink_scan() to free
905  * up pages when the system is under memory pressure.
906  */
907 enum lru_status binder_alloc_free_page(struct list_head *item,
908 				       struct list_lru_one *lru,
909 				       spinlock_t *lock,
910 				       void *cb_arg)
911 	__must_hold(lock)
912 {
913 	struct mm_struct *mm = NULL;
914 	struct binder_lru_page *page = container_of(item,
915 						    struct binder_lru_page,
916 						    lru);
917 	struct binder_alloc *alloc;
918 	uintptr_t page_addr;
919 	size_t index;
920 	struct vm_area_struct *vma;
921 
922 	alloc = page->alloc;
923 	if (!mutex_trylock(&alloc->mutex))
924 		goto err_get_alloc_mutex_failed;
925 
926 	if (!page->page_ptr)
927 		goto err_page_already_freed;
928 
929 	index = page - alloc->pages;
930 	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
931 
932 	mm = alloc->vma_vm_mm;
933 	if (!mmget_not_zero(mm))
934 		goto err_mmget;
935 	if (!down_read_trylock(&mm->mmap_sem))
936 		goto err_down_read_mmap_sem_failed;
937 	vma = binder_alloc_get_vma(alloc);
938 
939 	list_lru_isolate(lru, item);
940 	spin_unlock(lock);
941 
942 	if (vma) {
943 		trace_binder_unmap_user_start(alloc, index);
944 
945 		zap_page_range(vma, page_addr, PAGE_SIZE);
946 
947 		trace_binder_unmap_user_end(alloc, index);
948 	}
949 	up_read(&mm->mmap_sem);
950 	mmput(mm);
951 
952 	trace_binder_unmap_kernel_start(alloc, index);
953 
954 	__free_page(page->page_ptr);
955 	page->page_ptr = NULL;
956 
957 	trace_binder_unmap_kernel_end(alloc, index);
958 
959 	spin_lock(lock);
960 	mutex_unlock(&alloc->mutex);
961 	return LRU_REMOVED_RETRY;
962 
963 err_down_read_mmap_sem_failed:
964 	mmput_async(mm);
965 err_mmget:
966 err_page_already_freed:
967 	mutex_unlock(&alloc->mutex);
968 err_get_alloc_mutex_failed:
969 	return LRU_SKIP;
970 }
971 
972 static unsigned long
973 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
974 {
975 	unsigned long ret = list_lru_count(&binder_alloc_lru);
976 	return ret;
977 }
978 
979 static unsigned long
980 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
981 {
982 	unsigned long ret;
983 
984 	ret = list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
985 			    NULL, sc->nr_to_scan);
986 	return ret;
987 }
988 
989 static struct shrinker binder_shrinker = {
990 	.count_objects = binder_shrink_count,
991 	.scan_objects = binder_shrink_scan,
992 	.seeks = DEFAULT_SEEKS,
993 };
994 
995 /**
996  * binder_alloc_init() - called by binder_open() for per-proc initialization
997  * @alloc: binder_alloc for this proc
998  *
999  * Called from binder_open() to initialize binder_alloc fields for
1000  * new binder proc
1001  */
1002 void binder_alloc_init(struct binder_alloc *alloc)
1003 {
1004 	alloc->pid = current->group_leader->pid;
1005 	mutex_init(&alloc->mutex);
1006 	INIT_LIST_HEAD(&alloc->buffers);
1007 }
1008 
1009 int binder_alloc_shrinker_init(void)
1010 {
1011 	int ret = list_lru_init(&binder_alloc_lru);
1012 
1013 	if (ret == 0) {
1014 		ret = register_shrinker(&binder_shrinker);
1015 		if (ret)
1016 			list_lru_destroy(&binder_alloc_lru);
1017 	}
1018 	return ret;
1019 }
1020 
1021 /**
1022  * check_buffer() - verify that buffer/offset is safe to access
1023  * @alloc: binder_alloc for this proc
1024  * @buffer: binder buffer to be accessed
1025  * @offset: offset into @buffer data
1026  * @bytes: bytes to access from offset
1027  *
1028  * Check that the @offset/@bytes are within the size of the given
1029  * @buffer and that the buffer is currently active and not freeable.
1030  * Offsets must also be multiples of sizeof(u32). The kernel is
1031  * allowed to touch the buffer in two cases:
1032  *
1033  * 1) when the buffer is being created:
1034  *     (buffer->free == 0 && buffer->allow_user_free == 0)
1035  * 2) when the buffer is being torn down:
1036  *     (buffer->free == 0 && buffer->transaction == NULL).
1037  *
1038  * Return: true if the buffer is safe to access
1039  */
1040 static inline bool check_buffer(struct binder_alloc *alloc,
1041 				struct binder_buffer *buffer,
1042 				binder_size_t offset, size_t bytes)
1043 {
1044 	size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1045 
1046 	return buffer_size >= bytes &&
1047 		offset <= buffer_size - bytes &&
1048 		IS_ALIGNED(offset, sizeof(u32)) &&
1049 		!buffer->free &&
1050 		(!buffer->allow_user_free || !buffer->transaction);
1051 }
1052 
1053 /**
1054  * binder_alloc_get_page() - get kernel pointer for given buffer offset
1055  * @alloc: binder_alloc for this proc
1056  * @buffer: binder buffer to be accessed
1057  * @buffer_offset: offset into @buffer data
1058  * @pgoffp: address to copy final page offset to
1059  *
1060  * Lookup the struct page corresponding to the address
1061  * at @buffer_offset into @buffer->user_data. If @pgoffp is not
1062  * NULL, the byte-offset into the page is written there.
1063  *
1064  * The caller is responsible to ensure that the offset points
1065  * to a valid address within the @buffer and that @buffer is
1066  * not freeable by the user. Since it can't be freed, we are
1067  * guaranteed that the corresponding elements of @alloc->pages[]
1068  * cannot change.
1069  *
1070  * Return: struct page
1071  */
1072 static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
1073 					  struct binder_buffer *buffer,
1074 					  binder_size_t buffer_offset,
1075 					  pgoff_t *pgoffp)
1076 {
1077 	binder_size_t buffer_space_offset = buffer_offset +
1078 		(buffer->user_data - alloc->buffer);
1079 	pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
1080 	size_t index = buffer_space_offset >> PAGE_SHIFT;
1081 	struct binder_lru_page *lru_page;
1082 
1083 	lru_page = &alloc->pages[index];
1084 	*pgoffp = pgoff;
1085 	return lru_page->page_ptr;
1086 }
1087 
1088 /**
1089  * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1090  * @alloc: binder_alloc for this proc
1091  * @buffer: binder buffer to be accessed
1092  * @buffer_offset: offset into @buffer data
1093  * @from: userspace pointer to source buffer
1094  * @bytes: bytes to copy
1095  *
1096  * Copy bytes from source userspace to target buffer.
1097  *
1098  * Return: bytes remaining to be copied
1099  */
1100 unsigned long
1101 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1102 				 struct binder_buffer *buffer,
1103 				 binder_size_t buffer_offset,
1104 				 const void __user *from,
1105 				 size_t bytes)
1106 {
1107 	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1108 		return bytes;
1109 
1110 	while (bytes) {
1111 		unsigned long size;
1112 		unsigned long ret;
1113 		struct page *page;
1114 		pgoff_t pgoff;
1115 		void *kptr;
1116 
1117 		page = binder_alloc_get_page(alloc, buffer,
1118 					     buffer_offset, &pgoff);
1119 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1120 		kptr = kmap(page) + pgoff;
1121 		ret = copy_from_user(kptr, from, size);
1122 		kunmap(page);
1123 		if (ret)
1124 			return bytes - size + ret;
1125 		bytes -= size;
1126 		from += size;
1127 		buffer_offset += size;
1128 	}
1129 	return 0;
1130 }
1131 
1132 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1133 				       bool to_buffer,
1134 				       struct binder_buffer *buffer,
1135 				       binder_size_t buffer_offset,
1136 				       void *ptr,
1137 				       size_t bytes)
1138 {
1139 	/* All copies must be 32-bit aligned and 32-bit size */
1140 	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1141 		return -EINVAL;
1142 
1143 	while (bytes) {
1144 		unsigned long size;
1145 		struct page *page;
1146 		pgoff_t pgoff;
1147 		void *tmpptr;
1148 		void *base_ptr;
1149 
1150 		page = binder_alloc_get_page(alloc, buffer,
1151 					     buffer_offset, &pgoff);
1152 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1153 		base_ptr = kmap_atomic(page);
1154 		tmpptr = base_ptr + pgoff;
1155 		if (to_buffer)
1156 			memcpy(tmpptr, ptr, size);
1157 		else
1158 			memcpy(ptr, tmpptr, size);
1159 		/*
1160 		 * kunmap_atomic() takes care of flushing the cache
1161 		 * if this device has VIVT cache arch
1162 		 */
1163 		kunmap_atomic(base_ptr);
1164 		bytes -= size;
1165 		pgoff = 0;
1166 		ptr = ptr + size;
1167 		buffer_offset += size;
1168 	}
1169 	return 0;
1170 }
1171 
1172 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1173 				struct binder_buffer *buffer,
1174 				binder_size_t buffer_offset,
1175 				void *src,
1176 				size_t bytes)
1177 {
1178 	return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1179 					   src, bytes);
1180 }
1181 
1182 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1183 				  void *dest,
1184 				  struct binder_buffer *buffer,
1185 				  binder_size_t buffer_offset,
1186 				  size_t bytes)
1187 {
1188 	return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1189 					   dest, bytes);
1190 }
1191 
1192