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