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 
binder_buffer_next(struct binder_buffer * buffer)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 
binder_buffer_prev(struct binder_buffer * buffer)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 
binder_alloc_buffer_size(struct binder_alloc * alloc,struct binder_buffer * buffer)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 
binder_insert_free_buffer(struct binder_alloc * alloc,struct binder_buffer * new_buffer)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 
binder_insert_allocated_buffer_locked(struct binder_alloc * alloc,struct binder_buffer * new_buffer)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 
binder_alloc_prepare_to_free_locked(struct binder_alloc * alloc,uintptr_t user_ptr)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  */
binder_alloc_prepare_to_free(struct binder_alloc * alloc,uintptr_t user_ptr)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 
binder_update_page_range(struct binder_alloc * alloc,int allocate,void __user * start,void __user * end)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_async(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_async(mm);
308 	}
309 	return vma ? -ENOMEM : -ESRCH;
310 }
311 
binder_alloc_set_vma(struct binder_alloc * alloc,struct vm_area_struct * vma)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 
binder_alloc_get_vma(struct binder_alloc * alloc)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 
debug_low_async_space_locked(struct binder_alloc * alloc,int pid)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 		num_buffers++;
349 	}
350 
351 	/*
352 	 * Warn if this pid has more than 50 transactions, or more than 50% of
353 	 * async space (which is 25% of total buffer size). Oneway spam is only
354 	 * detected when the threshold is exceeded.
355 	 */
356 	if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
357 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
358 			     "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
359 			      alloc->pid, pid, num_buffers, total_alloc_size);
360 		if (!alloc->oneway_spam_detected) {
361 			alloc->oneway_spam_detected = true;
362 			return true;
363 		}
364 	}
365 	return false;
366 }
367 
binder_alloc_new_buf_locked(struct binder_alloc * alloc,size_t data_size,size_t offsets_size,size_t extra_buffers_size,int is_async,int pid)368 static struct binder_buffer *binder_alloc_new_buf_locked(
369 				struct binder_alloc *alloc,
370 				size_t data_size,
371 				size_t offsets_size,
372 				size_t extra_buffers_size,
373 				int is_async,
374 				int pid)
375 {
376 	struct rb_node *n = alloc->free_buffers.rb_node;
377 	struct binder_buffer *buffer;
378 	size_t buffer_size;
379 	struct rb_node *best_fit = NULL;
380 	void __user *has_page_addr;
381 	void __user *end_page_addr;
382 	size_t size, data_offsets_size;
383 	int ret;
384 
385 	/* Check binder_alloc is fully initialized */
386 	if (!binder_alloc_get_vma(alloc)) {
387 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
388 				   "%d: binder_alloc_buf, no vma\n",
389 				   alloc->pid);
390 		return ERR_PTR(-ESRCH);
391 	}
392 
393 	data_offsets_size = ALIGN(data_size, sizeof(void *)) +
394 		ALIGN(offsets_size, sizeof(void *));
395 
396 	if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
397 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
398 				"%d: got transaction with invalid size %zd-%zd\n",
399 				alloc->pid, data_size, offsets_size);
400 		return ERR_PTR(-EINVAL);
401 	}
402 	size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
403 	if (size < data_offsets_size || size < extra_buffers_size) {
404 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
405 				"%d: got transaction with invalid extra_buffers_size %zd\n",
406 				alloc->pid, extra_buffers_size);
407 		return ERR_PTR(-EINVAL);
408 	}
409 
410 	/* Pad 0-size buffers so they get assigned unique addresses */
411 	size = max(size, sizeof(void *));
412 
413 	if (is_async && alloc->free_async_space < size) {
414 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
415 			     "%d: binder_alloc_buf size %zd failed, no async space left\n",
416 			      alloc->pid, size);
417 		return ERR_PTR(-ENOSPC);
418 	}
419 
420 	while (n) {
421 		buffer = rb_entry(n, struct binder_buffer, rb_node);
422 		BUG_ON(!buffer->free);
423 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
424 
425 		if (size < buffer_size) {
426 			best_fit = n;
427 			n = n->rb_left;
428 		} else if (size > buffer_size)
429 			n = n->rb_right;
430 		else {
431 			best_fit = n;
432 			break;
433 		}
434 	}
435 	if (best_fit == NULL) {
436 		size_t allocated_buffers = 0;
437 		size_t largest_alloc_size = 0;
438 		size_t total_alloc_size = 0;
439 		size_t free_buffers = 0;
440 		size_t largest_free_size = 0;
441 		size_t total_free_size = 0;
442 
443 		for (n = rb_first(&alloc->allocated_buffers); n != NULL;
444 		     n = rb_next(n)) {
445 			buffer = rb_entry(n, struct binder_buffer, rb_node);
446 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
447 			allocated_buffers++;
448 			total_alloc_size += buffer_size;
449 			if (buffer_size > largest_alloc_size)
450 				largest_alloc_size = buffer_size;
451 		}
452 		for (n = rb_first(&alloc->free_buffers); n != NULL;
453 		     n = rb_next(n)) {
454 			buffer = rb_entry(n, struct binder_buffer, rb_node);
455 			buffer_size = binder_alloc_buffer_size(alloc, buffer);
456 			free_buffers++;
457 			total_free_size += buffer_size;
458 			if (buffer_size > largest_free_size)
459 				largest_free_size = buffer_size;
460 		}
461 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
462 				   "%d: binder_alloc_buf size %zd failed, no address space\n",
463 				   alloc->pid, size);
464 		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
465 				   "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
466 				   total_alloc_size, allocated_buffers,
467 				   largest_alloc_size, total_free_size,
468 				   free_buffers, largest_free_size);
469 		return ERR_PTR(-ENOSPC);
470 	}
471 	if (n == NULL) {
472 		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
473 		buffer_size = binder_alloc_buffer_size(alloc, buffer);
474 	}
475 
476 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
477 		     "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
478 		      alloc->pid, size, buffer, buffer_size);
479 
480 	has_page_addr = (void __user *)
481 		(((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
482 	WARN_ON(n && buffer_size != size);
483 	end_page_addr =
484 		(void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
485 	if (end_page_addr > has_page_addr)
486 		end_page_addr = has_page_addr;
487 	ret = binder_update_page_range(alloc, 1, (void __user *)
488 		PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr);
489 	if (ret)
490 		return ERR_PTR(ret);
491 
492 	if (buffer_size != size) {
493 		struct binder_buffer *new_buffer;
494 
495 		new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
496 		if (!new_buffer) {
497 			pr_err("%s: %d failed to alloc new buffer struct\n",
498 			       __func__, alloc->pid);
499 			goto err_alloc_buf_struct_failed;
500 		}
501 		new_buffer->user_data = (u8 __user *)buffer->user_data + size;
502 		list_add(&new_buffer->entry, &buffer->entry);
503 		new_buffer->free = 1;
504 		binder_insert_free_buffer(alloc, new_buffer);
505 	}
506 
507 	rb_erase(best_fit, &alloc->free_buffers);
508 	buffer->free = 0;
509 	buffer->allow_user_free = 0;
510 	binder_insert_allocated_buffer_locked(alloc, buffer);
511 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
512 		     "%d: binder_alloc_buf size %zd got %pK\n",
513 		      alloc->pid, size, buffer);
514 	buffer->data_size = data_size;
515 	buffer->offsets_size = offsets_size;
516 	buffer->async_transaction = is_async;
517 	buffer->extra_buffers_size = extra_buffers_size;
518 	buffer->pid = pid;
519 	buffer->oneway_spam_suspect = false;
520 	if (is_async) {
521 		alloc->free_async_space -= size;
522 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
523 			     "%d: binder_alloc_buf size %zd async free %zd\n",
524 			      alloc->pid, size, alloc->free_async_space);
525 		if (alloc->free_async_space < alloc->buffer_size / 10) {
526 			/*
527 			 * Start detecting spammers once we have less than 20%
528 			 * of async space left (which is less than 10% of total
529 			 * buffer size).
530 			 */
531 			buffer->oneway_spam_suspect = debug_low_async_space_locked(alloc, pid);
532 		} else {
533 			alloc->oneway_spam_detected = false;
534 		}
535 	}
536 	return buffer;
537 
538 err_alloc_buf_struct_failed:
539 	binder_update_page_range(alloc, 0, (void __user *)
540 				 PAGE_ALIGN((uintptr_t)buffer->user_data),
541 				 end_page_addr);
542 	return ERR_PTR(-ENOMEM);
543 }
544 
545 /**
546  * binder_alloc_new_buf() - Allocate a new binder buffer
547  * @alloc:              binder_alloc for this proc
548  * @data_size:          size of user data buffer
549  * @offsets_size:       user specified buffer offset
550  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
551  * @is_async:           buffer for async transaction
552  * @pid:				pid to attribute allocation to (used for debugging)
553  *
554  * Allocate a new buffer given the requested sizes. Returns
555  * the kernel version of the buffer pointer. The size allocated
556  * is the sum of the three given sizes (each rounded up to
557  * pointer-sized boundary)
558  *
559  * Return:	The allocated buffer or %ERR_PTR(-errno) if error
560  */
binder_alloc_new_buf(struct binder_alloc * alloc,size_t data_size,size_t offsets_size,size_t extra_buffers_size,int is_async,int pid)561 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
562 					   size_t data_size,
563 					   size_t offsets_size,
564 					   size_t extra_buffers_size,
565 					   int is_async,
566 					   int pid)
567 {
568 	struct binder_buffer *buffer;
569 
570 	mutex_lock(&alloc->mutex);
571 	buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
572 					     extra_buffers_size, is_async, pid);
573 	mutex_unlock(&alloc->mutex);
574 	return buffer;
575 }
576 
buffer_start_page(struct binder_buffer * buffer)577 static void __user *buffer_start_page(struct binder_buffer *buffer)
578 {
579 	return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
580 }
581 
prev_buffer_end_page(struct binder_buffer * buffer)582 static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
583 {
584 	return (void __user *)
585 		(((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
586 }
587 
binder_delete_free_buffer(struct binder_alloc * alloc,struct binder_buffer * buffer)588 static void binder_delete_free_buffer(struct binder_alloc *alloc,
589 				      struct binder_buffer *buffer)
590 {
591 	struct binder_buffer *prev, *next = NULL;
592 	bool to_free = true;
593 
594 	BUG_ON(alloc->buffers.next == &buffer->entry);
595 	prev = binder_buffer_prev(buffer);
596 	BUG_ON(!prev->free);
597 	if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
598 		to_free = false;
599 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
600 				   "%d: merge free, buffer %pK share page with %pK\n",
601 				   alloc->pid, buffer->user_data,
602 				   prev->user_data);
603 	}
604 
605 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
606 		next = binder_buffer_next(buffer);
607 		if (buffer_start_page(next) == buffer_start_page(buffer)) {
608 			to_free = false;
609 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
610 					   "%d: merge free, buffer %pK share page with %pK\n",
611 					   alloc->pid,
612 					   buffer->user_data,
613 					   next->user_data);
614 		}
615 	}
616 
617 	if (PAGE_ALIGNED(buffer->user_data)) {
618 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
619 				   "%d: merge free, buffer start %pK is page aligned\n",
620 				   alloc->pid, buffer->user_data);
621 		to_free = false;
622 	}
623 
624 	if (to_free) {
625 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
626 				   "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
627 				   alloc->pid, buffer->user_data,
628 				   prev->user_data,
629 				   next ? next->user_data : NULL);
630 		binder_update_page_range(alloc, 0, buffer_start_page(buffer),
631 					 buffer_start_page(buffer) + PAGE_SIZE);
632 	}
633 	list_del(&buffer->entry);
634 	kfree(buffer);
635 }
636 
binder_free_buf_locked(struct binder_alloc * alloc,struct binder_buffer * buffer)637 static void binder_free_buf_locked(struct binder_alloc *alloc,
638 				   struct binder_buffer *buffer)
639 {
640 	size_t size, buffer_size;
641 
642 	buffer_size = binder_alloc_buffer_size(alloc, buffer);
643 
644 	size = ALIGN(buffer->data_size, sizeof(void *)) +
645 		ALIGN(buffer->offsets_size, sizeof(void *)) +
646 		ALIGN(buffer->extra_buffers_size, sizeof(void *));
647 
648 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
649 		     "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
650 		      alloc->pid, buffer, size, buffer_size);
651 
652 	BUG_ON(buffer->free);
653 	BUG_ON(size > buffer_size);
654 	BUG_ON(buffer->transaction != NULL);
655 	BUG_ON(buffer->user_data < alloc->buffer);
656 	BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
657 
658 	if (buffer->async_transaction) {
659 		alloc->free_async_space += buffer_size;
660 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
661 			     "%d: binder_free_buf size %zd async free %zd\n",
662 			      alloc->pid, size, alloc->free_async_space);
663 	}
664 
665 	binder_update_page_range(alloc, 0,
666 		(void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
667 		(void __user *)(((uintptr_t)
668 			  buffer->user_data + buffer_size) & PAGE_MASK));
669 
670 	rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
671 	buffer->free = 1;
672 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
673 		struct binder_buffer *next = binder_buffer_next(buffer);
674 
675 		if (next->free) {
676 			rb_erase(&next->rb_node, &alloc->free_buffers);
677 			binder_delete_free_buffer(alloc, next);
678 		}
679 	}
680 	if (alloc->buffers.next != &buffer->entry) {
681 		struct binder_buffer *prev = binder_buffer_prev(buffer);
682 
683 		if (prev->free) {
684 			binder_delete_free_buffer(alloc, buffer);
685 			rb_erase(&prev->rb_node, &alloc->free_buffers);
686 			buffer = prev;
687 		}
688 	}
689 	binder_insert_free_buffer(alloc, buffer);
690 }
691 
692 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
693 				   struct binder_buffer *buffer);
694 /**
695  * binder_alloc_free_buf() - free a binder buffer
696  * @alloc:	binder_alloc for this proc
697  * @buffer:	kernel pointer to buffer
698  *
699  * Free the buffer allocated via binder_alloc_new_buf()
700  */
binder_alloc_free_buf(struct binder_alloc * alloc,struct binder_buffer * buffer)701 void binder_alloc_free_buf(struct binder_alloc *alloc,
702 			    struct binder_buffer *buffer)
703 {
704 	/*
705 	 * We could eliminate the call to binder_alloc_clear_buf()
706 	 * from binder_alloc_deferred_release() by moving this to
707 	 * binder_free_buf_locked(). However, that could
708 	 * increase contention for the alloc mutex if clear_on_free
709 	 * is used frequently for large buffers. The mutex is not
710 	 * needed for correctness here.
711 	 */
712 	if (buffer->clear_on_free) {
713 		binder_alloc_clear_buf(alloc, buffer);
714 		buffer->clear_on_free = false;
715 	}
716 	mutex_lock(&alloc->mutex);
717 	binder_free_buf_locked(alloc, buffer);
718 	mutex_unlock(&alloc->mutex);
719 }
720 
721 /**
722  * binder_alloc_mmap_handler() - map virtual address space for proc
723  * @alloc:	alloc structure for this proc
724  * @vma:	vma passed to mmap()
725  *
726  * Called by binder_mmap() to initialize the space specified in
727  * vma for allocating binder buffers
728  *
729  * Return:
730  *      0 = success
731  *      -EBUSY = address space already mapped
732  *      -ENOMEM = failed to map memory to given address space
733  */
binder_alloc_mmap_handler(struct binder_alloc * alloc,struct vm_area_struct * vma)734 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
735 			      struct vm_area_struct *vma)
736 {
737 	int ret;
738 	const char *failure_string;
739 	struct binder_buffer *buffer;
740 
741 	if (unlikely(vma->vm_mm != alloc->mm)) {
742 		ret = -EINVAL;
743 		failure_string = "invalid vma->vm_mm";
744 		goto err_invalid_mm;
745 	}
746 
747 	mutex_lock(&binder_alloc_mmap_lock);
748 	if (alloc->buffer_size) {
749 		ret = -EBUSY;
750 		failure_string = "already mapped";
751 		goto err_already_mapped;
752 	}
753 	alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
754 				   SZ_4M);
755 	mutex_unlock(&binder_alloc_mmap_lock);
756 
757 	alloc->buffer = (void __user *)vma->vm_start;
758 
759 	alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
760 			       sizeof(alloc->pages[0]),
761 			       GFP_KERNEL);
762 	if (alloc->pages == NULL) {
763 		ret = -ENOMEM;
764 		failure_string = "alloc page array";
765 		goto err_alloc_pages_failed;
766 	}
767 
768 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
769 	if (!buffer) {
770 		ret = -ENOMEM;
771 		failure_string = "alloc buffer struct";
772 		goto err_alloc_buf_struct_failed;
773 	}
774 
775 	buffer->user_data = alloc->buffer;
776 	list_add(&buffer->entry, &alloc->buffers);
777 	buffer->free = 1;
778 	binder_insert_free_buffer(alloc, buffer);
779 	alloc->free_async_space = alloc->buffer_size / 2;
780 
781 	/* Signal binder_alloc is fully initialized */
782 	binder_alloc_set_vma(alloc, vma);
783 
784 	return 0;
785 
786 err_alloc_buf_struct_failed:
787 	kfree(alloc->pages);
788 	alloc->pages = NULL;
789 err_alloc_pages_failed:
790 	alloc->buffer = NULL;
791 	mutex_lock(&binder_alloc_mmap_lock);
792 	alloc->buffer_size = 0;
793 err_already_mapped:
794 	mutex_unlock(&binder_alloc_mmap_lock);
795 err_invalid_mm:
796 	binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
797 			   "%s: %d %lx-%lx %s failed %d\n", __func__,
798 			   alloc->pid, vma->vm_start, vma->vm_end,
799 			   failure_string, ret);
800 	return ret;
801 }
802 
803 
binder_alloc_deferred_release(struct binder_alloc * alloc)804 void binder_alloc_deferred_release(struct binder_alloc *alloc)
805 {
806 	struct rb_node *n;
807 	int buffers, page_count;
808 	struct binder_buffer *buffer;
809 
810 	buffers = 0;
811 	mutex_lock(&alloc->mutex);
812 	BUG_ON(alloc->vma);
813 
814 	while ((n = rb_first(&alloc->allocated_buffers))) {
815 		buffer = rb_entry(n, struct binder_buffer, rb_node);
816 
817 		/* Transaction should already have been freed */
818 		BUG_ON(buffer->transaction);
819 
820 		if (buffer->clear_on_free) {
821 			binder_alloc_clear_buf(alloc, buffer);
822 			buffer->clear_on_free = false;
823 		}
824 		binder_free_buf_locked(alloc, buffer);
825 		buffers++;
826 	}
827 
828 	while (!list_empty(&alloc->buffers)) {
829 		buffer = list_first_entry(&alloc->buffers,
830 					  struct binder_buffer, entry);
831 		WARN_ON(!buffer->free);
832 
833 		list_del(&buffer->entry);
834 		WARN_ON_ONCE(!list_empty(&alloc->buffers));
835 		kfree(buffer);
836 	}
837 
838 	page_count = 0;
839 	if (alloc->pages) {
840 		int i;
841 
842 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
843 			void __user *page_addr;
844 			bool on_lru;
845 
846 			if (!alloc->pages[i].page_ptr)
847 				continue;
848 
849 			on_lru = list_lru_del(&binder_alloc_lru,
850 					      &alloc->pages[i].lru);
851 			page_addr = alloc->buffer + i * PAGE_SIZE;
852 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
853 				     "%s: %d: page %d at %pK %s\n",
854 				     __func__, alloc->pid, i, page_addr,
855 				     on_lru ? "on lru" : "active");
856 			__free_page(alloc->pages[i].page_ptr);
857 			page_count++;
858 		}
859 		kfree(alloc->pages);
860 	}
861 	mutex_unlock(&alloc->mutex);
862 	if (alloc->mm)
863 		mmdrop(alloc->mm);
864 
865 	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
866 		     "%s: %d buffers %d, pages %d\n",
867 		     __func__, alloc->pid, buffers, page_count);
868 }
869 
print_binder_buffer(struct seq_file * m,const char * prefix,struct binder_buffer * buffer)870 static void print_binder_buffer(struct seq_file *m, const char *prefix,
871 				struct binder_buffer *buffer)
872 {
873 	seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
874 		   prefix, buffer->debug_id, buffer->user_data,
875 		   buffer->data_size, buffer->offsets_size,
876 		   buffer->extra_buffers_size,
877 		   buffer->transaction ? "active" : "delivered");
878 }
879 
880 /**
881  * binder_alloc_print_allocated() - print buffer info
882  * @m:     seq_file for output via seq_printf()
883  * @alloc: binder_alloc for this proc
884  *
885  * Prints information about every buffer associated with
886  * the binder_alloc state to the given seq_file
887  */
binder_alloc_print_allocated(struct seq_file * m,struct binder_alloc * alloc)888 void binder_alloc_print_allocated(struct seq_file *m,
889 				  struct binder_alloc *alloc)
890 {
891 	struct rb_node *n;
892 
893 	mutex_lock(&alloc->mutex);
894 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
895 		print_binder_buffer(m, "  buffer",
896 				    rb_entry(n, struct binder_buffer, rb_node));
897 	mutex_unlock(&alloc->mutex);
898 }
899 
900 /**
901  * binder_alloc_print_pages() - print page usage
902  * @m:     seq_file for output via seq_printf()
903  * @alloc: binder_alloc for this proc
904  */
binder_alloc_print_pages(struct seq_file * m,struct binder_alloc * alloc)905 void binder_alloc_print_pages(struct seq_file *m,
906 			      struct binder_alloc *alloc)
907 {
908 	struct binder_lru_page *page;
909 	int i;
910 	int active = 0;
911 	int lru = 0;
912 	int free = 0;
913 
914 	mutex_lock(&alloc->mutex);
915 	/*
916 	 * Make sure the binder_alloc is fully initialized, otherwise we might
917 	 * read inconsistent state.
918 	 */
919 	if (binder_alloc_get_vma(alloc) != NULL) {
920 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
921 			page = &alloc->pages[i];
922 			if (!page->page_ptr)
923 				free++;
924 			else if (list_empty(&page->lru))
925 				active++;
926 			else
927 				lru++;
928 		}
929 	}
930 	mutex_unlock(&alloc->mutex);
931 	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
932 	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
933 }
934 
935 /**
936  * binder_alloc_get_allocated_count() - return count of buffers
937  * @alloc: binder_alloc for this proc
938  *
939  * Return: count of allocated buffers
940  */
binder_alloc_get_allocated_count(struct binder_alloc * alloc)941 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
942 {
943 	struct rb_node *n;
944 	int count = 0;
945 
946 	mutex_lock(&alloc->mutex);
947 	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
948 		count++;
949 	mutex_unlock(&alloc->mutex);
950 	return count;
951 }
952 
953 
954 /**
955  * binder_alloc_vma_close() - invalidate address space
956  * @alloc: binder_alloc for this proc
957  *
958  * Called from binder_vma_close() when releasing address space.
959  * Clears alloc->vma to prevent new incoming transactions from
960  * allocating more buffers.
961  */
binder_alloc_vma_close(struct binder_alloc * alloc)962 void binder_alloc_vma_close(struct binder_alloc *alloc)
963 {
964 	binder_alloc_set_vma(alloc, NULL);
965 }
966 
967 /**
968  * binder_alloc_free_page() - shrinker callback to free pages
969  * @item:   item to free
970  * @lock:   lock protecting the item
971  * @cb_arg: callback argument
972  *
973  * Called from list_lru_walk() in binder_shrink_scan() to free
974  * up pages when the system is under memory pressure.
975  */
binder_alloc_free_page(struct list_head * item,struct list_lru_one * lru,spinlock_t * lock,void * cb_arg)976 enum lru_status binder_alloc_free_page(struct list_head *item,
977 				       struct list_lru_one *lru,
978 				       spinlock_t *lock,
979 				       void *cb_arg)
980 	__must_hold(lock)
981 {
982 	struct mm_struct *mm = NULL;
983 	struct binder_lru_page *page = container_of(item,
984 						    struct binder_lru_page,
985 						    lru);
986 	struct binder_alloc *alloc;
987 	uintptr_t page_addr;
988 	size_t index;
989 	struct vm_area_struct *vma;
990 
991 	alloc = page->alloc;
992 	if (!mutex_trylock(&alloc->mutex))
993 		goto err_get_alloc_mutex_failed;
994 
995 	if (!page->page_ptr)
996 		goto err_page_already_freed;
997 
998 	index = page - alloc->pages;
999 	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
1000 
1001 	mm = alloc->mm;
1002 	if (!mmget_not_zero(mm))
1003 		goto err_mmget;
1004 	if (!mmap_read_trylock(mm))
1005 		goto err_mmap_read_lock_failed;
1006 	vma = vma_lookup(mm, page_addr);
1007 	if (vma && vma != binder_alloc_get_vma(alloc))
1008 		goto err_invalid_vma;
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_invalid_vma:
1035 	mmap_read_unlock(mm);
1036 err_mmap_read_lock_failed:
1037 	mmput_async(mm);
1038 err_mmget:
1039 err_page_already_freed:
1040 	mutex_unlock(&alloc->mutex);
1041 err_get_alloc_mutex_failed:
1042 	return LRU_SKIP;
1043 }
1044 
1045 static unsigned long
binder_shrink_count(struct shrinker * shrink,struct shrink_control * sc)1046 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1047 {
1048 	return list_lru_count(&binder_alloc_lru);
1049 }
1050 
1051 static unsigned long
binder_shrink_scan(struct shrinker * shrink,struct shrink_control * sc)1052 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1053 {
1054 	return list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
1055 			    NULL, sc->nr_to_scan);
1056 }
1057 
1058 static struct shrinker binder_shrinker = {
1059 	.count_objects = binder_shrink_count,
1060 	.scan_objects = binder_shrink_scan,
1061 	.seeks = DEFAULT_SEEKS,
1062 };
1063 
1064 /**
1065  * binder_alloc_init() - called by binder_open() for per-proc initialization
1066  * @alloc: binder_alloc for this proc
1067  *
1068  * Called from binder_open() to initialize binder_alloc fields for
1069  * new binder proc
1070  */
binder_alloc_init(struct binder_alloc * alloc)1071 void binder_alloc_init(struct binder_alloc *alloc)
1072 {
1073 	alloc->pid = current->group_leader->pid;
1074 	alloc->mm = current->mm;
1075 	mmgrab(alloc->mm);
1076 	mutex_init(&alloc->mutex);
1077 	INIT_LIST_HEAD(&alloc->buffers);
1078 }
1079 
binder_alloc_shrinker_init(void)1080 int binder_alloc_shrinker_init(void)
1081 {
1082 	int ret = list_lru_init(&binder_alloc_lru);
1083 
1084 	if (ret == 0) {
1085 		ret = register_shrinker(&binder_shrinker, "android-binder");
1086 		if (ret)
1087 			list_lru_destroy(&binder_alloc_lru);
1088 	}
1089 	return ret;
1090 }
1091 
binder_alloc_shrinker_exit(void)1092 void binder_alloc_shrinker_exit(void)
1093 {
1094 	unregister_shrinker(&binder_shrinker);
1095 	list_lru_destroy(&binder_alloc_lru);
1096 }
1097 
1098 /**
1099  * check_buffer() - verify that buffer/offset is safe to access
1100  * @alloc: binder_alloc for this proc
1101  * @buffer: binder buffer to be accessed
1102  * @offset: offset into @buffer data
1103  * @bytes: bytes to access from offset
1104  *
1105  * Check that the @offset/@bytes are within the size of the given
1106  * @buffer and that the buffer is currently active and not freeable.
1107  * Offsets must also be multiples of sizeof(u32). The kernel is
1108  * allowed to touch the buffer in two cases:
1109  *
1110  * 1) when the buffer is being created:
1111  *     (buffer->free == 0 && buffer->allow_user_free == 0)
1112  * 2) when the buffer is being torn down:
1113  *     (buffer->free == 0 && buffer->transaction == NULL).
1114  *
1115  * Return: true if the buffer is safe to access
1116  */
check_buffer(struct binder_alloc * alloc,struct binder_buffer * buffer,binder_size_t offset,size_t bytes)1117 static inline bool check_buffer(struct binder_alloc *alloc,
1118 				struct binder_buffer *buffer,
1119 				binder_size_t offset, size_t bytes)
1120 {
1121 	size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1122 
1123 	return buffer_size >= bytes &&
1124 		offset <= buffer_size - bytes &&
1125 		IS_ALIGNED(offset, sizeof(u32)) &&
1126 		!buffer->free &&
1127 		(!buffer->allow_user_free || !buffer->transaction);
1128 }
1129 
1130 /**
1131  * binder_alloc_get_page() - get kernel pointer for given buffer offset
1132  * @alloc: binder_alloc for this proc
1133  * @buffer: binder buffer to be accessed
1134  * @buffer_offset: offset into @buffer data
1135  * @pgoffp: address to copy final page offset to
1136  *
1137  * Lookup the struct page corresponding to the address
1138  * at @buffer_offset into @buffer->user_data. If @pgoffp is not
1139  * NULL, the byte-offset into the page is written there.
1140  *
1141  * The caller is responsible to ensure that the offset points
1142  * to a valid address within the @buffer and that @buffer is
1143  * not freeable by the user. Since it can't be freed, we are
1144  * guaranteed that the corresponding elements of @alloc->pages[]
1145  * cannot change.
1146  *
1147  * Return: struct page
1148  */
binder_alloc_get_page(struct binder_alloc * alloc,struct binder_buffer * buffer,binder_size_t buffer_offset,pgoff_t * pgoffp)1149 static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
1150 					  struct binder_buffer *buffer,
1151 					  binder_size_t buffer_offset,
1152 					  pgoff_t *pgoffp)
1153 {
1154 	binder_size_t buffer_space_offset = buffer_offset +
1155 		(buffer->user_data - alloc->buffer);
1156 	pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
1157 	size_t index = buffer_space_offset >> PAGE_SHIFT;
1158 	struct binder_lru_page *lru_page;
1159 
1160 	lru_page = &alloc->pages[index];
1161 	*pgoffp = pgoff;
1162 	return lru_page->page_ptr;
1163 }
1164 
1165 /**
1166  * binder_alloc_clear_buf() - zero out buffer
1167  * @alloc: binder_alloc for this proc
1168  * @buffer: binder buffer to be cleared
1169  *
1170  * memset the given buffer to 0
1171  */
binder_alloc_clear_buf(struct binder_alloc * alloc,struct binder_buffer * buffer)1172 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
1173 				   struct binder_buffer *buffer)
1174 {
1175 	size_t bytes = binder_alloc_buffer_size(alloc, buffer);
1176 	binder_size_t buffer_offset = 0;
1177 
1178 	while (bytes) {
1179 		unsigned long size;
1180 		struct page *page;
1181 		pgoff_t pgoff;
1182 
1183 		page = binder_alloc_get_page(alloc, buffer,
1184 					     buffer_offset, &pgoff);
1185 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1186 		memset_page(page, pgoff, 0, size);
1187 		bytes -= size;
1188 		buffer_offset += size;
1189 	}
1190 }
1191 
1192 /**
1193  * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1194  * @alloc: binder_alloc for this proc
1195  * @buffer: binder buffer to be accessed
1196  * @buffer_offset: offset into @buffer data
1197  * @from: userspace pointer to source buffer
1198  * @bytes: bytes to copy
1199  *
1200  * Copy bytes from source userspace to target buffer.
1201  *
1202  * Return: bytes remaining to be copied
1203  */
1204 unsigned long
binder_alloc_copy_user_to_buffer(struct binder_alloc * alloc,struct binder_buffer * buffer,binder_size_t buffer_offset,const void __user * from,size_t bytes)1205 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1206 				 struct binder_buffer *buffer,
1207 				 binder_size_t buffer_offset,
1208 				 const void __user *from,
1209 				 size_t bytes)
1210 {
1211 	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1212 		return bytes;
1213 
1214 	while (bytes) {
1215 		unsigned long size;
1216 		unsigned long ret;
1217 		struct page *page;
1218 		pgoff_t pgoff;
1219 		void *kptr;
1220 
1221 		page = binder_alloc_get_page(alloc, buffer,
1222 					     buffer_offset, &pgoff);
1223 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1224 		kptr = kmap_local_page(page) + pgoff;
1225 		ret = copy_from_user(kptr, from, size);
1226 		kunmap_local(kptr);
1227 		if (ret)
1228 			return bytes - size + ret;
1229 		bytes -= size;
1230 		from += size;
1231 		buffer_offset += size;
1232 	}
1233 	return 0;
1234 }
1235 
binder_alloc_do_buffer_copy(struct binder_alloc * alloc,bool to_buffer,struct binder_buffer * buffer,binder_size_t buffer_offset,void * ptr,size_t bytes)1236 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1237 				       bool to_buffer,
1238 				       struct binder_buffer *buffer,
1239 				       binder_size_t buffer_offset,
1240 				       void *ptr,
1241 				       size_t bytes)
1242 {
1243 	/* All copies must be 32-bit aligned and 32-bit size */
1244 	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1245 		return -EINVAL;
1246 
1247 	while (bytes) {
1248 		unsigned long size;
1249 		struct page *page;
1250 		pgoff_t pgoff;
1251 
1252 		page = binder_alloc_get_page(alloc, buffer,
1253 					     buffer_offset, &pgoff);
1254 		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1255 		if (to_buffer)
1256 			memcpy_to_page(page, pgoff, ptr, size);
1257 		else
1258 			memcpy_from_page(ptr, page, pgoff, size);
1259 		bytes -= size;
1260 		pgoff = 0;
1261 		ptr = ptr + size;
1262 		buffer_offset += size;
1263 	}
1264 	return 0;
1265 }
1266 
binder_alloc_copy_to_buffer(struct binder_alloc * alloc,struct binder_buffer * buffer,binder_size_t buffer_offset,void * src,size_t bytes)1267 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1268 				struct binder_buffer *buffer,
1269 				binder_size_t buffer_offset,
1270 				void *src,
1271 				size_t bytes)
1272 {
1273 	return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1274 					   src, bytes);
1275 }
1276 
binder_alloc_copy_from_buffer(struct binder_alloc * alloc,void * dest,struct binder_buffer * buffer,binder_size_t buffer_offset,size_t bytes)1277 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1278 				  void *dest,
1279 				  struct binder_buffer *buffer,
1280 				  binder_size_t buffer_offset,
1281 				  size_t bytes)
1282 {
1283 	return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1284 					   dest, bytes);
1285 }
1286 
1287