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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
29struct list_lru binder_freelist;
30
31static DEFINE_MUTEX(binder_alloc_mmap_lock);
32
33enum {
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};
39static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR;
40
41module_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
50static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
51{
52 return list_entry(buffer->entry.next, struct binder_buffer, entry);
53}
54
55static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
56{
57 return list_entry(buffer->entry.prev, struct binder_buffer, entry);
58}
59
60static 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
68static 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
101static 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
126static struct binder_buffer *binder_alloc_prepare_to_free_locked(
127 struct binder_alloc *alloc,
128 unsigned long user_ptr)
129{
130 struct rb_node *n = alloc->allocated_buffers.rb_node;
131 struct binder_buffer *buffer;
132
133 while (n) {
134 buffer = rb_entry(n, struct binder_buffer, rb_node);
135 BUG_ON(buffer->free);
136
137 if (user_ptr < buffer->user_data) {
138 n = n->rb_left;
139 } else if (user_ptr > buffer->user_data) {
140 n = n->rb_right;
141 } else {
142 /*
143 * Guard against user threads attempting to
144 * free the buffer when in use by kernel or
145 * after it's already been freed.
146 */
147 if (!buffer->allow_user_free)
148 return ERR_PTR(-EPERM);
149 buffer->allow_user_free = 0;
150 return buffer;
151 }
152 }
153 return NULL;
154}
155
156/**
157 * binder_alloc_prepare_to_free() - get buffer given user ptr
158 * @alloc: binder_alloc for this proc
159 * @user_ptr: User pointer to buffer data
160 *
161 * Validate userspace pointer to buffer data and return buffer corresponding to
162 * that user pointer. Search the rb tree for buffer that matches user data
163 * pointer.
164 *
165 * Return: Pointer to buffer or NULL
166 */
167struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
168 unsigned long user_ptr)
169{
170 struct binder_buffer *buffer;
171
172 spin_lock(&alloc->lock);
173 buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
174 spin_unlock(&alloc->lock);
175 return buffer;
176}
177
178static inline void
179binder_set_installed_page(struct binder_lru_page *lru_page,
180 struct page *page)
181{
182 /* Pairs with acquire in binder_get_installed_page() */
183 smp_store_release(&lru_page->page_ptr, page);
184}
185
186static inline struct page *
187binder_get_installed_page(struct binder_lru_page *lru_page)
188{
189 /* Pairs with release in binder_set_installed_page() */
190 return smp_load_acquire(&lru_page->page_ptr);
191}
192
193static void binder_lru_freelist_add(struct binder_alloc *alloc,
194 unsigned long start, unsigned long end)
195{
196 struct binder_lru_page *page;
197 unsigned long page_addr;
198
199 trace_binder_update_page_range(alloc, false, start, end);
200
201 for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
202 size_t index;
203 int ret;
204
205 index = (page_addr - alloc->buffer) / PAGE_SIZE;
206 page = &alloc->pages[index];
207
208 if (!binder_get_installed_page(page))
209 continue;
210
211 trace_binder_free_lru_start(alloc, index);
212
213 ret = list_lru_add_obj(&binder_freelist, &page->lru);
214 WARN_ON(!ret);
215
216 trace_binder_free_lru_end(alloc, index);
217 }
218}
219
220static int binder_install_single_page(struct binder_alloc *alloc,
221 struct binder_lru_page *lru_page,
222 unsigned long addr)
223{
224 struct page *page;
225 int ret = 0;
226
227 if (!mmget_not_zero(alloc->mm))
228 return -ESRCH;
229
230 /*
231 * Protected with mmap_sem in write mode as multiple tasks
232 * might race to install the same page.
233 */
234 mmap_write_lock(alloc->mm);
235 if (binder_get_installed_page(lru_page))
236 goto out;
237
238 if (!alloc->vma) {
239 pr_err("%d: %s failed, no vma\n", alloc->pid, __func__);
240 ret = -ESRCH;
241 goto out;
242 }
243
244 page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
245 if (!page) {
246 pr_err("%d: failed to allocate page\n", alloc->pid);
247 ret = -ENOMEM;
248 goto out;
249 }
250
251 ret = vm_insert_page(alloc->vma, addr, page);
252 if (ret) {
253 pr_err("%d: %s failed to insert page at offset %lx with %d\n",
254 alloc->pid, __func__, addr - alloc->buffer, ret);
255 __free_page(page);
256 ret = -ENOMEM;
257 goto out;
258 }
259
260 /* Mark page installation complete and safe to use */
261 binder_set_installed_page(lru_page, page);
262out:
263 mmap_write_unlock(alloc->mm);
264 mmput_async(alloc->mm);
265 return ret;
266}
267
268static int binder_install_buffer_pages(struct binder_alloc *alloc,
269 struct binder_buffer *buffer,
270 size_t size)
271{
272 struct binder_lru_page *page;
273 unsigned long start, final;
274 unsigned long page_addr;
275
276 start = buffer->user_data & PAGE_MASK;
277 final = PAGE_ALIGN(buffer->user_data + size);
278
279 for (page_addr = start; page_addr < final; page_addr += PAGE_SIZE) {
280 unsigned long index;
281 int ret;
282
283 index = (page_addr - alloc->buffer) / PAGE_SIZE;
284 page = &alloc->pages[index];
285
286 if (binder_get_installed_page(page))
287 continue;
288
289 trace_binder_alloc_page_start(alloc, index);
290
291 ret = binder_install_single_page(alloc, page, page_addr);
292 if (ret)
293 return ret;
294
295 trace_binder_alloc_page_end(alloc, index);
296 }
297
298 return 0;
299}
300
301/* The range of pages should exclude those shared with other buffers */
302static void binder_lru_freelist_del(struct binder_alloc *alloc,
303 unsigned long start, unsigned long end)
304{
305 struct binder_lru_page *page;
306 unsigned long page_addr;
307
308 trace_binder_update_page_range(alloc, true, start, end);
309
310 for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
311 unsigned long index;
312 bool on_lru;
313
314 index = (page_addr - alloc->buffer) / PAGE_SIZE;
315 page = &alloc->pages[index];
316
317 if (page->page_ptr) {
318 trace_binder_alloc_lru_start(alloc, index);
319
320 on_lru = list_lru_del_obj(&binder_freelist, &page->lru);
321 WARN_ON(!on_lru);
322
323 trace_binder_alloc_lru_end(alloc, index);
324 continue;
325 }
326
327 if (index + 1 > alloc->pages_high)
328 alloc->pages_high = index + 1;
329 }
330}
331
332static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
333 struct vm_area_struct *vma)
334{
335 /* pairs with smp_load_acquire in binder_alloc_get_vma() */
336 smp_store_release(&alloc->vma, vma);
337}
338
339static inline struct vm_area_struct *binder_alloc_get_vma(
340 struct binder_alloc *alloc)
341{
342 /* pairs with smp_store_release in binder_alloc_set_vma() */
343 return smp_load_acquire(&alloc->vma);
344}
345
346static void debug_no_space_locked(struct binder_alloc *alloc)
347{
348 size_t largest_alloc_size = 0;
349 struct binder_buffer *buffer;
350 size_t allocated_buffers = 0;
351 size_t largest_free_size = 0;
352 size_t total_alloc_size = 0;
353 size_t total_free_size = 0;
354 size_t free_buffers = 0;
355 size_t buffer_size;
356 struct rb_node *n;
357
358 for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
359 buffer = rb_entry(n, struct binder_buffer, rb_node);
360 buffer_size = binder_alloc_buffer_size(alloc, buffer);
361 allocated_buffers++;
362 total_alloc_size += buffer_size;
363 if (buffer_size > largest_alloc_size)
364 largest_alloc_size = buffer_size;
365 }
366
367 for (n = rb_first(&alloc->free_buffers); n; n = rb_next(n)) {
368 buffer = rb_entry(n, struct binder_buffer, rb_node);
369 buffer_size = binder_alloc_buffer_size(alloc, buffer);
370 free_buffers++;
371 total_free_size += buffer_size;
372 if (buffer_size > largest_free_size)
373 largest_free_size = buffer_size;
374 }
375
376 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
377 "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
378 total_alloc_size, allocated_buffers,
379 largest_alloc_size, total_free_size,
380 free_buffers, largest_free_size);
381}
382
383static bool debug_low_async_space_locked(struct binder_alloc *alloc)
384{
385 /*
386 * Find the amount and size of buffers allocated by the current caller;
387 * The idea is that once we cross the threshold, whoever is responsible
388 * for the low async space is likely to try to send another async txn,
389 * and at some point we'll catch them in the act. This is more efficient
390 * than keeping a map per pid.
391 */
392 struct binder_buffer *buffer;
393 size_t total_alloc_size = 0;
394 int pid = current->tgid;
395 size_t num_buffers = 0;
396 struct rb_node *n;
397
398 /*
399 * Only start detecting spammers once we have less than 20% of async
400 * space left (which is less than 10% of total buffer size).
401 */
402 if (alloc->free_async_space >= alloc->buffer_size / 10) {
403 alloc->oneway_spam_detected = false;
404 return false;
405 }
406
407 for (n = rb_first(&alloc->allocated_buffers); n != NULL;
408 n = rb_next(n)) {
409 buffer = rb_entry(n, struct binder_buffer, rb_node);
410 if (buffer->pid != pid)
411 continue;
412 if (!buffer->async_transaction)
413 continue;
414 total_alloc_size += binder_alloc_buffer_size(alloc, buffer);
415 num_buffers++;
416 }
417
418 /*
419 * Warn if this pid has more than 50 transactions, or more than 50% of
420 * async space (which is 25% of total buffer size). Oneway spam is only
421 * detected when the threshold is exceeded.
422 */
423 if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
424 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
425 "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
426 alloc->pid, pid, num_buffers, total_alloc_size);
427 if (!alloc->oneway_spam_detected) {
428 alloc->oneway_spam_detected = true;
429 return true;
430 }
431 }
432 return false;
433}
434
435/* Callers preallocate @new_buffer, it is freed by this function if unused */
436static struct binder_buffer *binder_alloc_new_buf_locked(
437 struct binder_alloc *alloc,
438 struct binder_buffer *new_buffer,
439 size_t size,
440 int is_async)
441{
442 struct rb_node *n = alloc->free_buffers.rb_node;
443 struct rb_node *best_fit = NULL;
444 struct binder_buffer *buffer;
445 unsigned long next_used_page;
446 unsigned long curr_last_page;
447 size_t buffer_size;
448
449 if (is_async && alloc->free_async_space < size) {
450 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
451 "%d: binder_alloc_buf size %zd failed, no async space left\n",
452 alloc->pid, size);
453 buffer = ERR_PTR(-ENOSPC);
454 goto out;
455 }
456
457 while (n) {
458 buffer = rb_entry(n, struct binder_buffer, rb_node);
459 BUG_ON(!buffer->free);
460 buffer_size = binder_alloc_buffer_size(alloc, buffer);
461
462 if (size < buffer_size) {
463 best_fit = n;
464 n = n->rb_left;
465 } else if (size > buffer_size) {
466 n = n->rb_right;
467 } else {
468 best_fit = n;
469 break;
470 }
471 }
472
473 if (unlikely(!best_fit)) {
474 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
475 "%d: binder_alloc_buf size %zd failed, no address space\n",
476 alloc->pid, size);
477 debug_no_space_locked(alloc);
478 buffer = ERR_PTR(-ENOSPC);
479 goto out;
480 }
481
482 if (buffer_size != size) {
483 /* Found an oversized buffer and needs to be split */
484 buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
485 buffer_size = binder_alloc_buffer_size(alloc, buffer);
486
487 WARN_ON(n || buffer_size == size);
488 new_buffer->user_data = buffer->user_data + size;
489 list_add(&new_buffer->entry, &buffer->entry);
490 new_buffer->free = 1;
491 binder_insert_free_buffer(alloc, new_buffer);
492 new_buffer = NULL;
493 }
494
495 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
496 "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
497 alloc->pid, size, buffer, buffer_size);
498
499 /*
500 * Now we remove the pages from the freelist. A clever calculation
501 * with buffer_size determines if the last page is shared with an
502 * adjacent in-use buffer. In such case, the page has been already
503 * removed from the freelist so we trim our range short.
504 */
505 next_used_page = (buffer->user_data + buffer_size) & PAGE_MASK;
506 curr_last_page = PAGE_ALIGN(buffer->user_data + size);
507 binder_lru_freelist_del(alloc, PAGE_ALIGN(buffer->user_data),
508 min(next_used_page, curr_last_page));
509
510 rb_erase(&buffer->rb_node, &alloc->free_buffers);
511 buffer->free = 0;
512 buffer->allow_user_free = 0;
513 binder_insert_allocated_buffer_locked(alloc, buffer);
514 buffer->async_transaction = is_async;
515 buffer->oneway_spam_suspect = false;
516 if (is_async) {
517 alloc->free_async_space -= size;
518 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
519 "%d: binder_alloc_buf size %zd async free %zd\n",
520 alloc->pid, size, alloc->free_async_space);
521 if (debug_low_async_space_locked(alloc))
522 buffer->oneway_spam_suspect = true;
523 }
524
525out:
526 /* Discard possibly unused new_buffer */
527 kfree(new_buffer);
528 return buffer;
529}
530
531/* Calculate the sanitized total size, returns 0 for invalid request */
532static inline size_t sanitized_size(size_t data_size,
533 size_t offsets_size,
534 size_t extra_buffers_size)
535{
536 size_t total, tmp;
537
538 /* Align to pointer size and check for overflows */
539 tmp = ALIGN(data_size, sizeof(void *)) +
540 ALIGN(offsets_size, sizeof(void *));
541 if (tmp < data_size || tmp < offsets_size)
542 return 0;
543 total = tmp + ALIGN(extra_buffers_size, sizeof(void *));
544 if (total < tmp || total < extra_buffers_size)
545 return 0;
546
547 /* Pad 0-sized buffers so they get a unique address */
548 total = max(total, sizeof(void *));
549
550 return total;
551}
552
553/**
554 * binder_alloc_new_buf() - Allocate a new binder buffer
555 * @alloc: binder_alloc for this proc
556 * @data_size: size of user data buffer
557 * @offsets_size: user specified buffer offset
558 * @extra_buffers_size: size of extra space for meta-data (eg, security context)
559 * @is_async: buffer for async transaction
560 *
561 * Allocate a new buffer given the requested sizes. Returns
562 * the kernel version of the buffer pointer. The size allocated
563 * is the sum of the three given sizes (each rounded up to
564 * pointer-sized boundary)
565 *
566 * Return: The allocated buffer or %ERR_PTR(-errno) if error
567 */
568struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
569 size_t data_size,
570 size_t offsets_size,
571 size_t extra_buffers_size,
572 int is_async)
573{
574 struct binder_buffer *buffer, *next;
575 size_t size;
576 int ret;
577
578 /* Check binder_alloc is fully initialized */
579 if (!binder_alloc_get_vma(alloc)) {
580 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
581 "%d: binder_alloc_buf, no vma\n",
582 alloc->pid);
583 return ERR_PTR(-ESRCH);
584 }
585
586 size = sanitized_size(data_size, offsets_size, extra_buffers_size);
587 if (unlikely(!size)) {
588 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
589 "%d: got transaction with invalid size %zd-%zd-%zd\n",
590 alloc->pid, data_size, offsets_size,
591 extra_buffers_size);
592 return ERR_PTR(-EINVAL);
593 }
594
595 /* Preallocate the next buffer */
596 next = kzalloc(sizeof(*next), GFP_KERNEL);
597 if (!next)
598 return ERR_PTR(-ENOMEM);
599
600 spin_lock(&alloc->lock);
601 buffer = binder_alloc_new_buf_locked(alloc, next, size, is_async);
602 if (IS_ERR(buffer)) {
603 spin_unlock(&alloc->lock);
604 goto out;
605 }
606
607 buffer->data_size = data_size;
608 buffer->offsets_size = offsets_size;
609 buffer->extra_buffers_size = extra_buffers_size;
610 buffer->pid = current->tgid;
611 spin_unlock(&alloc->lock);
612
613 ret = binder_install_buffer_pages(alloc, buffer, size);
614 if (ret) {
615 binder_alloc_free_buf(alloc, buffer);
616 buffer = ERR_PTR(ret);
617 }
618out:
619 return buffer;
620}
621
622static unsigned long buffer_start_page(struct binder_buffer *buffer)
623{
624 return buffer->user_data & PAGE_MASK;
625}
626
627static unsigned long prev_buffer_end_page(struct binder_buffer *buffer)
628{
629 return (buffer->user_data - 1) & PAGE_MASK;
630}
631
632static void binder_delete_free_buffer(struct binder_alloc *alloc,
633 struct binder_buffer *buffer)
634{
635 struct binder_buffer *prev, *next;
636
637 if (PAGE_ALIGNED(buffer->user_data))
638 goto skip_freelist;
639
640 BUG_ON(alloc->buffers.next == &buffer->entry);
641 prev = binder_buffer_prev(buffer);
642 BUG_ON(!prev->free);
643 if (prev_buffer_end_page(prev) == buffer_start_page(buffer))
644 goto skip_freelist;
645
646 if (!list_is_last(&buffer->entry, &alloc->buffers)) {
647 next = binder_buffer_next(buffer);
648 if (buffer_start_page(next) == buffer_start_page(buffer))
649 goto skip_freelist;
650 }
651
652 binder_lru_freelist_add(alloc, buffer_start_page(buffer),
653 buffer_start_page(buffer) + PAGE_SIZE);
654skip_freelist:
655 list_del(&buffer->entry);
656 kfree(buffer);
657}
658
659static void binder_free_buf_locked(struct binder_alloc *alloc,
660 struct binder_buffer *buffer)
661{
662 size_t size, buffer_size;
663
664 buffer_size = binder_alloc_buffer_size(alloc, buffer);
665
666 size = ALIGN(buffer->data_size, sizeof(void *)) +
667 ALIGN(buffer->offsets_size, sizeof(void *)) +
668 ALIGN(buffer->extra_buffers_size, sizeof(void *));
669
670 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
671 "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
672 alloc->pid, buffer, size, buffer_size);
673
674 BUG_ON(buffer->free);
675 BUG_ON(size > buffer_size);
676 BUG_ON(buffer->transaction != NULL);
677 BUG_ON(buffer->user_data < alloc->buffer);
678 BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
679
680 if (buffer->async_transaction) {
681 alloc->free_async_space += buffer_size;
682 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
683 "%d: binder_free_buf size %zd async free %zd\n",
684 alloc->pid, size, alloc->free_async_space);
685 }
686
687 binder_lru_freelist_add(alloc, PAGE_ALIGN(buffer->user_data),
688 (buffer->user_data + buffer_size) & PAGE_MASK);
689
690 rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
691 buffer->free = 1;
692 if (!list_is_last(&buffer->entry, &alloc->buffers)) {
693 struct binder_buffer *next = binder_buffer_next(buffer);
694
695 if (next->free) {
696 rb_erase(&next->rb_node, &alloc->free_buffers);
697 binder_delete_free_buffer(alloc, next);
698 }
699 }
700 if (alloc->buffers.next != &buffer->entry) {
701 struct binder_buffer *prev = binder_buffer_prev(buffer);
702
703 if (prev->free) {
704 binder_delete_free_buffer(alloc, buffer);
705 rb_erase(&prev->rb_node, &alloc->free_buffers);
706 buffer = prev;
707 }
708 }
709 binder_insert_free_buffer(alloc, buffer);
710}
711
712/**
713 * binder_alloc_get_page() - get kernel pointer for given buffer offset
714 * @alloc: binder_alloc for this proc
715 * @buffer: binder buffer to be accessed
716 * @buffer_offset: offset into @buffer data
717 * @pgoffp: address to copy final page offset to
718 *
719 * Lookup the struct page corresponding to the address
720 * at @buffer_offset into @buffer->user_data. If @pgoffp is not
721 * NULL, the byte-offset into the page is written there.
722 *
723 * The caller is responsible to ensure that the offset points
724 * to a valid address within the @buffer and that @buffer is
725 * not freeable by the user. Since it can't be freed, we are
726 * guaranteed that the corresponding elements of @alloc->pages[]
727 * cannot change.
728 *
729 * Return: struct page
730 */
731static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
732 struct binder_buffer *buffer,
733 binder_size_t buffer_offset,
734 pgoff_t *pgoffp)
735{
736 binder_size_t buffer_space_offset = buffer_offset +
737 (buffer->user_data - alloc->buffer);
738 pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
739 size_t index = buffer_space_offset >> PAGE_SHIFT;
740 struct binder_lru_page *lru_page;
741
742 lru_page = &alloc->pages[index];
743 *pgoffp = pgoff;
744 return lru_page->page_ptr;
745}
746
747/**
748 * binder_alloc_clear_buf() - zero out buffer
749 * @alloc: binder_alloc for this proc
750 * @buffer: binder buffer to be cleared
751 *
752 * memset the given buffer to 0
753 */
754static void binder_alloc_clear_buf(struct binder_alloc *alloc,
755 struct binder_buffer *buffer)
756{
757 size_t bytes = binder_alloc_buffer_size(alloc, buffer);
758 binder_size_t buffer_offset = 0;
759
760 while (bytes) {
761 unsigned long size;
762 struct page *page;
763 pgoff_t pgoff;
764
765 page = binder_alloc_get_page(alloc, buffer,
766 buffer_offset, &pgoff);
767 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
768 memset_page(page, pgoff, 0, size);
769 bytes -= size;
770 buffer_offset += size;
771 }
772}
773
774/**
775 * binder_alloc_free_buf() - free a binder buffer
776 * @alloc: binder_alloc for this proc
777 * @buffer: kernel pointer to buffer
778 *
779 * Free the buffer allocated via binder_alloc_new_buf()
780 */
781void binder_alloc_free_buf(struct binder_alloc *alloc,
782 struct binder_buffer *buffer)
783{
784 /*
785 * We could eliminate the call to binder_alloc_clear_buf()
786 * from binder_alloc_deferred_release() by moving this to
787 * binder_free_buf_locked(). However, that could
788 * increase contention for the alloc->lock if clear_on_free
789 * is used frequently for large buffers. This lock is not
790 * needed for correctness here.
791 */
792 if (buffer->clear_on_free) {
793 binder_alloc_clear_buf(alloc, buffer);
794 buffer->clear_on_free = false;
795 }
796 spin_lock(&alloc->lock);
797 binder_free_buf_locked(alloc, buffer);
798 spin_unlock(&alloc->lock);
799}
800
801/**
802 * binder_alloc_mmap_handler() - map virtual address space for proc
803 * @alloc: alloc structure for this proc
804 * @vma: vma passed to mmap()
805 *
806 * Called by binder_mmap() to initialize the space specified in
807 * vma for allocating binder buffers
808 *
809 * Return:
810 * 0 = success
811 * -EBUSY = address space already mapped
812 * -ENOMEM = failed to map memory to given address space
813 */
814int binder_alloc_mmap_handler(struct binder_alloc *alloc,
815 struct vm_area_struct *vma)
816{
817 struct binder_buffer *buffer;
818 const char *failure_string;
819 int ret, i;
820
821 if (unlikely(vma->vm_mm != alloc->mm)) {
822 ret = -EINVAL;
823 failure_string = "invalid vma->vm_mm";
824 goto err_invalid_mm;
825 }
826
827 mutex_lock(&binder_alloc_mmap_lock);
828 if (alloc->buffer_size) {
829 ret = -EBUSY;
830 failure_string = "already mapped";
831 goto err_already_mapped;
832 }
833 alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
834 SZ_4M);
835 mutex_unlock(&binder_alloc_mmap_lock);
836
837 alloc->buffer = vma->vm_start;
838
839 alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
840 sizeof(alloc->pages[0]),
841 GFP_KERNEL);
842 if (alloc->pages == NULL) {
843 ret = -ENOMEM;
844 failure_string = "alloc page array";
845 goto err_alloc_pages_failed;
846 }
847
848 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
849 alloc->pages[i].alloc = alloc;
850 INIT_LIST_HEAD(&alloc->pages[i].lru);
851 }
852
853 buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
854 if (!buffer) {
855 ret = -ENOMEM;
856 failure_string = "alloc buffer struct";
857 goto err_alloc_buf_struct_failed;
858 }
859
860 buffer->user_data = alloc->buffer;
861 list_add(&buffer->entry, &alloc->buffers);
862 buffer->free = 1;
863 binder_insert_free_buffer(alloc, buffer);
864 alloc->free_async_space = alloc->buffer_size / 2;
865
866 /* Signal binder_alloc is fully initialized */
867 binder_alloc_set_vma(alloc, vma);
868
869 return 0;
870
871err_alloc_buf_struct_failed:
872 kfree(alloc->pages);
873 alloc->pages = NULL;
874err_alloc_pages_failed:
875 alloc->buffer = 0;
876 mutex_lock(&binder_alloc_mmap_lock);
877 alloc->buffer_size = 0;
878err_already_mapped:
879 mutex_unlock(&binder_alloc_mmap_lock);
880err_invalid_mm:
881 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
882 "%s: %d %lx-%lx %s failed %d\n", __func__,
883 alloc->pid, vma->vm_start, vma->vm_end,
884 failure_string, ret);
885 return ret;
886}
887
888
889void binder_alloc_deferred_release(struct binder_alloc *alloc)
890{
891 struct rb_node *n;
892 int buffers, page_count;
893 struct binder_buffer *buffer;
894
895 buffers = 0;
896 spin_lock(&alloc->lock);
897 BUG_ON(alloc->vma);
898
899 while ((n = rb_first(&alloc->allocated_buffers))) {
900 buffer = rb_entry(n, struct binder_buffer, rb_node);
901
902 /* Transaction should already have been freed */
903 BUG_ON(buffer->transaction);
904
905 if (buffer->clear_on_free) {
906 binder_alloc_clear_buf(alloc, buffer);
907 buffer->clear_on_free = false;
908 }
909 binder_free_buf_locked(alloc, buffer);
910 buffers++;
911 }
912
913 while (!list_empty(&alloc->buffers)) {
914 buffer = list_first_entry(&alloc->buffers,
915 struct binder_buffer, entry);
916 WARN_ON(!buffer->free);
917
918 list_del(&buffer->entry);
919 WARN_ON_ONCE(!list_empty(&alloc->buffers));
920 kfree(buffer);
921 }
922
923 page_count = 0;
924 if (alloc->pages) {
925 int i;
926
927 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
928 bool on_lru;
929
930 if (!alloc->pages[i].page_ptr)
931 continue;
932
933 on_lru = list_lru_del_obj(&binder_freelist,
934 &alloc->pages[i].lru);
935 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
936 "%s: %d: page %d %s\n",
937 __func__, alloc->pid, i,
938 on_lru ? "on lru" : "active");
939 __free_page(alloc->pages[i].page_ptr);
940 page_count++;
941 }
942 kfree(alloc->pages);
943 }
944 spin_unlock(&alloc->lock);
945 if (alloc->mm)
946 mmdrop(alloc->mm);
947
948 binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
949 "%s: %d buffers %d, pages %d\n",
950 __func__, alloc->pid, buffers, page_count);
951}
952
953/**
954 * binder_alloc_print_allocated() - print buffer info
955 * @m: seq_file for output via seq_printf()
956 * @alloc: binder_alloc for this proc
957 *
958 * Prints information about every buffer associated with
959 * the binder_alloc state to the given seq_file
960 */
961void binder_alloc_print_allocated(struct seq_file *m,
962 struct binder_alloc *alloc)
963{
964 struct binder_buffer *buffer;
965 struct rb_node *n;
966
967 spin_lock(&alloc->lock);
968 for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
969 buffer = rb_entry(n, struct binder_buffer, rb_node);
970 seq_printf(m, " buffer %d: %lx size %zd:%zd:%zd %s\n",
971 buffer->debug_id,
972 buffer->user_data - alloc->buffer,
973 buffer->data_size, buffer->offsets_size,
974 buffer->extra_buffers_size,
975 buffer->transaction ? "active" : "delivered");
976 }
977 spin_unlock(&alloc->lock);
978}
979
980/**
981 * binder_alloc_print_pages() - print page usage
982 * @m: seq_file for output via seq_printf()
983 * @alloc: binder_alloc for this proc
984 */
985void binder_alloc_print_pages(struct seq_file *m,
986 struct binder_alloc *alloc)
987{
988 struct binder_lru_page *page;
989 int i;
990 int active = 0;
991 int lru = 0;
992 int free = 0;
993
994 spin_lock(&alloc->lock);
995 /*
996 * Make sure the binder_alloc is fully initialized, otherwise we might
997 * read inconsistent state.
998 */
999 if (binder_alloc_get_vma(alloc) != NULL) {
1000 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
1001 page = &alloc->pages[i];
1002 if (!page->page_ptr)
1003 free++;
1004 else if (list_empty(&page->lru))
1005 active++;
1006 else
1007 lru++;
1008 }
1009 }
1010 spin_unlock(&alloc->lock);
1011 seq_printf(m, " pages: %d:%d:%d\n", active, lru, free);
1012 seq_printf(m, " pages high watermark: %zu\n", alloc->pages_high);
1013}
1014
1015/**
1016 * binder_alloc_get_allocated_count() - return count of buffers
1017 * @alloc: binder_alloc for this proc
1018 *
1019 * Return: count of allocated buffers
1020 */
1021int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
1022{
1023 struct rb_node *n;
1024 int count = 0;
1025
1026 spin_lock(&alloc->lock);
1027 for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
1028 count++;
1029 spin_unlock(&alloc->lock);
1030 return count;
1031}
1032
1033
1034/**
1035 * binder_alloc_vma_close() - invalidate address space
1036 * @alloc: binder_alloc for this proc
1037 *
1038 * Called from binder_vma_close() when releasing address space.
1039 * Clears alloc->vma to prevent new incoming transactions from
1040 * allocating more buffers.
1041 */
1042void binder_alloc_vma_close(struct binder_alloc *alloc)
1043{
1044 binder_alloc_set_vma(alloc, NULL);
1045}
1046
1047/**
1048 * binder_alloc_free_page() - shrinker callback to free pages
1049 * @item: item to free
1050 * @lock: lock protecting the item
1051 * @cb_arg: callback argument
1052 *
1053 * Called from list_lru_walk() in binder_shrink_scan() to free
1054 * up pages when the system is under memory pressure.
1055 */
1056enum lru_status binder_alloc_free_page(struct list_head *item,
1057 struct list_lru_one *lru,
1058 spinlock_t *lock,
1059 void *cb_arg)
1060 __must_hold(lock)
1061{
1062 struct binder_lru_page *page = container_of(item, typeof(*page), lru);
1063 struct binder_alloc *alloc = page->alloc;
1064 struct mm_struct *mm = alloc->mm;
1065 struct vm_area_struct *vma;
1066 struct page *page_to_free;
1067 unsigned long page_addr;
1068 size_t index;
1069
1070 if (!mmget_not_zero(mm))
1071 goto err_mmget;
1072 if (!mmap_read_trylock(mm))
1073 goto err_mmap_read_lock_failed;
1074 if (!spin_trylock(&alloc->lock))
1075 goto err_get_alloc_lock_failed;
1076 if (!page->page_ptr)
1077 goto err_page_already_freed;
1078
1079 index = page - alloc->pages;
1080 page_addr = alloc->buffer + index * PAGE_SIZE;
1081
1082 vma = vma_lookup(mm, page_addr);
1083 if (vma && vma != binder_alloc_get_vma(alloc))
1084 goto err_invalid_vma;
1085
1086 trace_binder_unmap_kernel_start(alloc, index);
1087
1088 page_to_free = page->page_ptr;
1089 page->page_ptr = NULL;
1090
1091 trace_binder_unmap_kernel_end(alloc, index);
1092
1093 list_lru_isolate(lru, item);
1094 spin_unlock(&alloc->lock);
1095 spin_unlock(lock);
1096
1097 if (vma) {
1098 trace_binder_unmap_user_start(alloc, index);
1099
1100 zap_page_range_single(vma, page_addr, PAGE_SIZE, NULL);
1101
1102 trace_binder_unmap_user_end(alloc, index);
1103 }
1104
1105 mmap_read_unlock(mm);
1106 mmput_async(mm);
1107 __free_page(page_to_free);
1108
1109 spin_lock(lock);
1110 return LRU_REMOVED_RETRY;
1111
1112err_invalid_vma:
1113err_page_already_freed:
1114 spin_unlock(&alloc->lock);
1115err_get_alloc_lock_failed:
1116 mmap_read_unlock(mm);
1117err_mmap_read_lock_failed:
1118 mmput_async(mm);
1119err_mmget:
1120 return LRU_SKIP;
1121}
1122
1123static unsigned long
1124binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1125{
1126 return list_lru_count(&binder_freelist);
1127}
1128
1129static unsigned long
1130binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1131{
1132 return list_lru_walk(&binder_freelist, binder_alloc_free_page,
1133 NULL, sc->nr_to_scan);
1134}
1135
1136static struct shrinker *binder_shrinker;
1137
1138/**
1139 * binder_alloc_init() - called by binder_open() for per-proc initialization
1140 * @alloc: binder_alloc for this proc
1141 *
1142 * Called from binder_open() to initialize binder_alloc fields for
1143 * new binder proc
1144 */
1145void binder_alloc_init(struct binder_alloc *alloc)
1146{
1147 alloc->pid = current->group_leader->pid;
1148 alloc->mm = current->mm;
1149 mmgrab(alloc->mm);
1150 spin_lock_init(&alloc->lock);
1151 INIT_LIST_HEAD(&alloc->buffers);
1152}
1153
1154int binder_alloc_shrinker_init(void)
1155{
1156 int ret;
1157
1158 ret = list_lru_init(&binder_freelist);
1159 if (ret)
1160 return ret;
1161
1162 binder_shrinker = shrinker_alloc(0, "android-binder");
1163 if (!binder_shrinker) {
1164 list_lru_destroy(&binder_freelist);
1165 return -ENOMEM;
1166 }
1167
1168 binder_shrinker->count_objects = binder_shrink_count;
1169 binder_shrinker->scan_objects = binder_shrink_scan;
1170
1171 shrinker_register(binder_shrinker);
1172
1173 return 0;
1174}
1175
1176void binder_alloc_shrinker_exit(void)
1177{
1178 shrinker_free(binder_shrinker);
1179 list_lru_destroy(&binder_freelist);
1180}
1181
1182/**
1183 * check_buffer() - verify that buffer/offset is safe to access
1184 * @alloc: binder_alloc for this proc
1185 * @buffer: binder buffer to be accessed
1186 * @offset: offset into @buffer data
1187 * @bytes: bytes to access from offset
1188 *
1189 * Check that the @offset/@bytes are within the size of the given
1190 * @buffer and that the buffer is currently active and not freeable.
1191 * Offsets must also be multiples of sizeof(u32). The kernel is
1192 * allowed to touch the buffer in two cases:
1193 *
1194 * 1) when the buffer is being created:
1195 * (buffer->free == 0 && buffer->allow_user_free == 0)
1196 * 2) when the buffer is being torn down:
1197 * (buffer->free == 0 && buffer->transaction == NULL).
1198 *
1199 * Return: true if the buffer is safe to access
1200 */
1201static inline bool check_buffer(struct binder_alloc *alloc,
1202 struct binder_buffer *buffer,
1203 binder_size_t offset, size_t bytes)
1204{
1205 size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1206
1207 return buffer_size >= bytes &&
1208 offset <= buffer_size - bytes &&
1209 IS_ALIGNED(offset, sizeof(u32)) &&
1210 !buffer->free &&
1211 (!buffer->allow_user_free || !buffer->transaction);
1212}
1213
1214/**
1215 * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1216 * @alloc: binder_alloc for this proc
1217 * @buffer: binder buffer to be accessed
1218 * @buffer_offset: offset into @buffer data
1219 * @from: userspace pointer to source buffer
1220 * @bytes: bytes to copy
1221 *
1222 * Copy bytes from source userspace to target buffer.
1223 *
1224 * Return: bytes remaining to be copied
1225 */
1226unsigned long
1227binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1228 struct binder_buffer *buffer,
1229 binder_size_t buffer_offset,
1230 const void __user *from,
1231 size_t bytes)
1232{
1233 if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1234 return bytes;
1235
1236 while (bytes) {
1237 unsigned long size;
1238 unsigned long ret;
1239 struct page *page;
1240 pgoff_t pgoff;
1241 void *kptr;
1242
1243 page = binder_alloc_get_page(alloc, buffer,
1244 buffer_offset, &pgoff);
1245 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1246 kptr = kmap_local_page(page) + pgoff;
1247 ret = copy_from_user(kptr, from, size);
1248 kunmap_local(kptr);
1249 if (ret)
1250 return bytes - size + ret;
1251 bytes -= size;
1252 from += size;
1253 buffer_offset += size;
1254 }
1255 return 0;
1256}
1257
1258static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1259 bool to_buffer,
1260 struct binder_buffer *buffer,
1261 binder_size_t buffer_offset,
1262 void *ptr,
1263 size_t bytes)
1264{
1265 /* All copies must be 32-bit aligned and 32-bit size */
1266 if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1267 return -EINVAL;
1268
1269 while (bytes) {
1270 unsigned long size;
1271 struct page *page;
1272 pgoff_t pgoff;
1273
1274 page = binder_alloc_get_page(alloc, buffer,
1275 buffer_offset, &pgoff);
1276 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1277 if (to_buffer)
1278 memcpy_to_page(page, pgoff, ptr, size);
1279 else
1280 memcpy_from_page(ptr, page, pgoff, size);
1281 bytes -= size;
1282 pgoff = 0;
1283 ptr = ptr + size;
1284 buffer_offset += size;
1285 }
1286 return 0;
1287}
1288
1289int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1290 struct binder_buffer *buffer,
1291 binder_size_t buffer_offset,
1292 void *src,
1293 size_t bytes)
1294{
1295 return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1296 src, bytes);
1297}
1298
1299int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1300 void *dest,
1301 struct binder_buffer *buffer,
1302 binder_size_t buffer_offset,
1303 size_t bytes)
1304{
1305 return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1306 dest, bytes);
1307}