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_alloc_lru;
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(list: &buffer->entry, head: &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, buffer: 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(node: &new_buffer->rb_node, parent, rb_link: 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(node: &new_buffer->rb_node, parent, rb_link: 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 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(error: -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 */
170struct 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(lock: &alloc->mutex);
178 return buffer;
179}
180
181static 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(mm: 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, page_index: index);
236
237 on_lru = list_lru_del(lru: &binder_alloc_lru, item: &page->lru);
238 WARN_ON(!on_lru);
239
240 trace_binder_alloc_lru_end(alloc, page_index: index);
241 continue;
242 }
243
244 if (WARN_ON(!vma))
245 goto err_page_ptr_cleared;
246
247 trace_binder_alloc_page_start(alloc, page_index: 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(list: &page->lru);
258
259 user_page_addr = (uintptr_t)page_addr;
260 ret = vm_insert_page(vma, addr: 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, page_index: index);
271 }
272 if (mm) {
273 mmap_write_unlock(mm);
274 mmput(mm);
275 }
276 return 0;
277
278free_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, page_index: index);
287
288 ret = list_lru_add(lru: &binder_alloc_lru, item: &page->lru);
289 WARN_ON(!ret);
290
291 trace_binder_free_lru_end(alloc, page_index: index);
292 if (page_addr == start)
293 break;
294 continue;
295
296err_vm_insert_page_failed:
297 __free_page(page->page_ptr);
298 page->page_ptr = NULL;
299err_alloc_page_failed:
300err_page_ptr_cleared:
301 if (page_addr == start)
302 break;
303 }
304err_no_vma:
305 if (mm) {
306 mmap_write_unlock(mm);
307 mmput(mm);
308 }
309 return vma ? -ENOMEM : -ESRCH;
310}
311
312static 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
319static 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
326static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
327{
328 /*
329 * Find the amount and size of buffers allocated by the current caller;
330 * The idea is that once we cross the threshold, whoever is responsible
331 * for the low async space is likely to try to send another async txn,
332 * and at some point we'll catch them in the act. This is more efficient
333 * than keeping a map per pid.
334 */
335 struct rb_node *n;
336 struct binder_buffer *buffer;
337 size_t total_alloc_size = 0;
338 size_t num_buffers = 0;
339
340 for (n = rb_first(&alloc->allocated_buffers); n != NULL;
341 n = rb_next(n)) {
342 buffer = rb_entry(n, struct binder_buffer, rb_node);
343 if (buffer->pid != pid)
344 continue;
345 if (!buffer->async_transaction)
346 continue;
347 total_alloc_size += binder_alloc_buffer_size(alloc, buffer)
348 + sizeof(struct binder_buffer);
349 num_buffers++;
350 }
351
352 /*
353 * Warn if this pid has more than 50 transactions, or more than 50% of
354 * async space (which is 25% of total buffer size). Oneway spam is only
355 * detected when the threshold is exceeded.
356 */
357 if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
358 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
359 "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
360 alloc->pid, pid, num_buffers, total_alloc_size);
361 if (!alloc->oneway_spam_detected) {
362 alloc->oneway_spam_detected = true;
363 return true;
364 }
365 }
366 return false;
367}
368
369static struct binder_buffer *binder_alloc_new_buf_locked(
370 struct binder_alloc *alloc,
371 size_t data_size,
372 size_t offsets_size,
373 size_t extra_buffers_size,
374 int is_async,
375 int pid)
376{
377 struct rb_node *n = alloc->free_buffers.rb_node;
378 struct binder_buffer *buffer;
379 size_t buffer_size;
380 struct rb_node *best_fit = NULL;
381 void __user *has_page_addr;
382 void __user *end_page_addr;
383 size_t size, data_offsets_size;
384 int ret;
385
386 /* Check binder_alloc is fully initialized */
387 if (!binder_alloc_get_vma(alloc)) {
388 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
389 "%d: binder_alloc_buf, no vma\n",
390 alloc->pid);
391 return ERR_PTR(error: -ESRCH);
392 }
393
394 data_offsets_size = ALIGN(data_size, sizeof(void *)) +
395 ALIGN(offsets_size, sizeof(void *));
396
397 if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
398 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
399 "%d: got transaction with invalid size %zd-%zd\n",
400 alloc->pid, data_size, offsets_size);
401 return ERR_PTR(error: -EINVAL);
402 }
403 size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
404 if (size < data_offsets_size || size < extra_buffers_size) {
405 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
406 "%d: got transaction with invalid extra_buffers_size %zd\n",
407 alloc->pid, extra_buffers_size);
408 return ERR_PTR(error: -EINVAL);
409 }
410 if (is_async &&
411 alloc->free_async_space < size + sizeof(struct binder_buffer)) {
412 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
413 "%d: binder_alloc_buf size %zd failed, no async space left\n",
414 alloc->pid, size);
415 return ERR_PTR(error: -ENOSPC);
416 }
417
418 /* Pad 0-size buffers so they get assigned unique addresses */
419 size = max(size, sizeof(void *));
420
421 while (n) {
422 buffer = rb_entry(n, struct binder_buffer, rb_node);
423 BUG_ON(!buffer->free);
424 buffer_size = binder_alloc_buffer_size(alloc, buffer);
425
426 if (size < buffer_size) {
427 best_fit = n;
428 n = n->rb_left;
429 } else if (size > buffer_size)
430 n = n->rb_right;
431 else {
432 best_fit = n;
433 break;
434 }
435 }
436 if (best_fit == NULL) {
437 size_t allocated_buffers = 0;
438 size_t largest_alloc_size = 0;
439 size_t total_alloc_size = 0;
440 size_t free_buffers = 0;
441 size_t largest_free_size = 0;
442 size_t total_free_size = 0;
443
444 for (n = rb_first(&alloc->allocated_buffers); n != NULL;
445 n = rb_next(n)) {
446 buffer = rb_entry(n, struct binder_buffer, rb_node);
447 buffer_size = binder_alloc_buffer_size(alloc, buffer);
448 allocated_buffers++;
449 total_alloc_size += buffer_size;
450 if (buffer_size > largest_alloc_size)
451 largest_alloc_size = buffer_size;
452 }
453 for (n = rb_first(&alloc->free_buffers); n != NULL;
454 n = rb_next(n)) {
455 buffer = rb_entry(n, struct binder_buffer, rb_node);
456 buffer_size = binder_alloc_buffer_size(alloc, buffer);
457 free_buffers++;
458 total_free_size += buffer_size;
459 if (buffer_size > largest_free_size)
460 largest_free_size = buffer_size;
461 }
462 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
463 "%d: binder_alloc_buf size %zd failed, no address space\n",
464 alloc->pid, size);
465 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
466 "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
467 total_alloc_size, allocated_buffers,
468 largest_alloc_size, total_free_size,
469 free_buffers, largest_free_size);
470 return ERR_PTR(error: -ENOSPC);
471 }
472 if (n == NULL) {
473 buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
474 buffer_size = binder_alloc_buffer_size(alloc, buffer);
475 }
476
477 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
478 "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
479 alloc->pid, size, buffer, buffer_size);
480
481 has_page_addr = (void __user *)
482 (((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
483 WARN_ON(n && buffer_size != size);
484 end_page_addr =
485 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
486 if (end_page_addr > has_page_addr)
487 end_page_addr = has_page_addr;
488 ret = binder_update_page_range(alloc, allocate: 1, start: (void __user *)
489 PAGE_ALIGN((uintptr_t)buffer->user_data), end: end_page_addr);
490 if (ret)
491 return ERR_PTR(error: ret);
492
493 if (buffer_size != size) {
494 struct binder_buffer *new_buffer;
495
496 new_buffer = kzalloc(size: sizeof(*buffer), GFP_KERNEL);
497 if (!new_buffer) {
498 pr_err("%s: %d failed to alloc new buffer struct\n",
499 __func__, alloc->pid);
500 goto err_alloc_buf_struct_failed;
501 }
502 new_buffer->user_data = (u8 __user *)buffer->user_data + size;
503 list_add(new: &new_buffer->entry, head: &buffer->entry);
504 new_buffer->free = 1;
505 binder_insert_free_buffer(alloc, new_buffer);
506 }
507
508 rb_erase(best_fit, &alloc->free_buffers);
509 buffer->free = 0;
510 buffer->allow_user_free = 0;
511 binder_insert_allocated_buffer_locked(alloc, new_buffer: buffer);
512 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
513 "%d: binder_alloc_buf size %zd got %pK\n",
514 alloc->pid, size, buffer);
515 buffer->data_size = data_size;
516 buffer->offsets_size = offsets_size;
517 buffer->async_transaction = is_async;
518 buffer->extra_buffers_size = extra_buffers_size;
519 buffer->pid = pid;
520 buffer->oneway_spam_suspect = false;
521 if (is_async) {
522 alloc->free_async_space -= size + sizeof(struct binder_buffer);
523 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
524 "%d: binder_alloc_buf size %zd async free %zd\n",
525 alloc->pid, size, alloc->free_async_space);
526 if (alloc->free_async_space < alloc->buffer_size / 10) {
527 /*
528 * Start detecting spammers once we have less than 20%
529 * of async space left (which is less than 10% of total
530 * buffer size).
531 */
532 buffer->oneway_spam_suspect = debug_low_async_space_locked(alloc, pid);
533 } else {
534 alloc->oneway_spam_detected = false;
535 }
536 }
537 return buffer;
538
539err_alloc_buf_struct_failed:
540 binder_update_page_range(alloc, allocate: 0, start: (void __user *)
541 PAGE_ALIGN((uintptr_t)buffer->user_data),
542 end: end_page_addr);
543 return ERR_PTR(error: -ENOMEM);
544}
545
546/**
547 * binder_alloc_new_buf() - Allocate a new binder buffer
548 * @alloc: binder_alloc for this proc
549 * @data_size: size of user data buffer
550 * @offsets_size: user specified buffer offset
551 * @extra_buffers_size: size of extra space for meta-data (eg, security context)
552 * @is_async: buffer for async transaction
553 * @pid: pid to attribute allocation to (used for debugging)
554 *
555 * Allocate a new buffer given the requested sizes. Returns
556 * the kernel version of the buffer pointer. The size allocated
557 * is the sum of the three given sizes (each rounded up to
558 * pointer-sized boundary)
559 *
560 * Return: The allocated buffer or %NULL if error
561 */
562struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
563 size_t data_size,
564 size_t offsets_size,
565 size_t extra_buffers_size,
566 int is_async,
567 int pid)
568{
569 struct binder_buffer *buffer;
570
571 mutex_lock(&alloc->mutex);
572 buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
573 extra_buffers_size, is_async, pid);
574 mutex_unlock(lock: &alloc->mutex);
575 return buffer;
576}
577
578static void __user *buffer_start_page(struct binder_buffer *buffer)
579{
580 return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
581}
582
583static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
584{
585 return (void __user *)
586 (((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
587}
588
589static void binder_delete_free_buffer(struct binder_alloc *alloc,
590 struct binder_buffer *buffer)
591{
592 struct binder_buffer *prev, *next = NULL;
593 bool to_free = true;
594
595 BUG_ON(alloc->buffers.next == &buffer->entry);
596 prev = binder_buffer_prev(buffer);
597 BUG_ON(!prev->free);
598 if (prev_buffer_end_page(buffer: prev) == buffer_start_page(buffer)) {
599 to_free = false;
600 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
601 "%d: merge free, buffer %pK share page with %pK\n",
602 alloc->pid, buffer->user_data,
603 prev->user_data);
604 }
605
606 if (!list_is_last(list: &buffer->entry, head: &alloc->buffers)) {
607 next = binder_buffer_next(buffer);
608 if (buffer_start_page(buffer: next) == buffer_start_page(buffer)) {
609 to_free = false;
610 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
611 "%d: merge free, buffer %pK share page with %pK\n",
612 alloc->pid,
613 buffer->user_data,
614 next->user_data);
615 }
616 }
617
618 if (PAGE_ALIGNED(buffer->user_data)) {
619 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
620 "%d: merge free, buffer start %pK is page aligned\n",
621 alloc->pid, buffer->user_data);
622 to_free = false;
623 }
624
625 if (to_free) {
626 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
627 "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
628 alloc->pid, buffer->user_data,
629 prev->user_data,
630 next ? next->user_data : NULL);
631 binder_update_page_range(alloc, allocate: 0, start: buffer_start_page(buffer),
632 end: buffer_start_page(buffer) + PAGE_SIZE);
633 }
634 list_del(entry: &buffer->entry);
635 kfree(objp: buffer);
636}
637
638static void binder_free_buf_locked(struct binder_alloc *alloc,
639 struct binder_buffer *buffer)
640{
641 size_t size, buffer_size;
642
643 buffer_size = binder_alloc_buffer_size(alloc, buffer);
644
645 size = ALIGN(buffer->data_size, sizeof(void *)) +
646 ALIGN(buffer->offsets_size, sizeof(void *)) +
647 ALIGN(buffer->extra_buffers_size, sizeof(void *));
648
649 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
650 "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
651 alloc->pid, buffer, size, buffer_size);
652
653 BUG_ON(buffer->free);
654 BUG_ON(size > buffer_size);
655 BUG_ON(buffer->transaction != NULL);
656 BUG_ON(buffer->user_data < alloc->buffer);
657 BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
658
659 if (buffer->async_transaction) {
660 alloc->free_async_space += buffer_size + sizeof(struct binder_buffer);
661
662 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
663 "%d: binder_free_buf size %zd async free %zd\n",
664 alloc->pid, size, alloc->free_async_space);
665 }
666
667 binder_update_page_range(alloc, allocate: 0,
668 start: (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
669 end: (void __user *)(((uintptr_t)
670 buffer->user_data + buffer_size) & PAGE_MASK));
671
672 rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
673 buffer->free = 1;
674 if (!list_is_last(list: &buffer->entry, head: &alloc->buffers)) {
675 struct binder_buffer *next = binder_buffer_next(buffer);
676
677 if (next->free) {
678 rb_erase(&next->rb_node, &alloc->free_buffers);
679 binder_delete_free_buffer(alloc, buffer: next);
680 }
681 }
682 if (alloc->buffers.next != &buffer->entry) {
683 struct binder_buffer *prev = binder_buffer_prev(buffer);
684
685 if (prev->free) {
686 binder_delete_free_buffer(alloc, buffer);
687 rb_erase(&prev->rb_node, &alloc->free_buffers);
688 buffer = prev;
689 }
690 }
691 binder_insert_free_buffer(alloc, new_buffer: buffer);
692}
693
694static void binder_alloc_clear_buf(struct binder_alloc *alloc,
695 struct binder_buffer *buffer);
696/**
697 * binder_alloc_free_buf() - free a binder buffer
698 * @alloc: binder_alloc for this proc
699 * @buffer: kernel pointer to buffer
700 *
701 * Free the buffer allocated via binder_alloc_new_buf()
702 */
703void binder_alloc_free_buf(struct binder_alloc *alloc,
704 struct binder_buffer *buffer)
705{
706 /*
707 * We could eliminate the call to binder_alloc_clear_buf()
708 * from binder_alloc_deferred_release() by moving this to
709 * binder_alloc_free_buf_locked(). However, that could
710 * increase contention for the alloc mutex if clear_on_free
711 * is used frequently for large buffers. The mutex is not
712 * needed for correctness here.
713 */
714 if (buffer->clear_on_free) {
715 binder_alloc_clear_buf(alloc, buffer);
716 buffer->clear_on_free = false;
717 }
718 mutex_lock(&alloc->mutex);
719 binder_free_buf_locked(alloc, buffer);
720 mutex_unlock(lock: &alloc->mutex);
721}
722
723/**
724 * binder_alloc_mmap_handler() - map virtual address space for proc
725 * @alloc: alloc structure for this proc
726 * @vma: vma passed to mmap()
727 *
728 * Called by binder_mmap() to initialize the space specified in
729 * vma for allocating binder buffers
730 *
731 * Return:
732 * 0 = success
733 * -EBUSY = address space already mapped
734 * -ENOMEM = failed to map memory to given address space
735 */
736int binder_alloc_mmap_handler(struct binder_alloc *alloc,
737 struct vm_area_struct *vma)
738{
739 int ret;
740 const char *failure_string;
741 struct binder_buffer *buffer;
742
743 if (unlikely(vma->vm_mm != alloc->mm)) {
744 ret = -EINVAL;
745 failure_string = "invalid vma->vm_mm";
746 goto err_invalid_mm;
747 }
748
749 mutex_lock(&binder_alloc_mmap_lock);
750 if (alloc->buffer_size) {
751 ret = -EBUSY;
752 failure_string = "already mapped";
753 goto err_already_mapped;
754 }
755 alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
756 SZ_4M);
757 mutex_unlock(lock: &binder_alloc_mmap_lock);
758
759 alloc->buffer = (void __user *)vma->vm_start;
760
761 alloc->pages = kcalloc(n: alloc->buffer_size / PAGE_SIZE,
762 size: sizeof(alloc->pages[0]),
763 GFP_KERNEL);
764 if (alloc->pages == NULL) {
765 ret = -ENOMEM;
766 failure_string = "alloc page array";
767 goto err_alloc_pages_failed;
768 }
769
770 buffer = kzalloc(size: sizeof(*buffer), GFP_KERNEL);
771 if (!buffer) {
772 ret = -ENOMEM;
773 failure_string = "alloc buffer struct";
774 goto err_alloc_buf_struct_failed;
775 }
776
777 buffer->user_data = alloc->buffer;
778 list_add(new: &buffer->entry, head: &alloc->buffers);
779 buffer->free = 1;
780 binder_insert_free_buffer(alloc, new_buffer: buffer);
781 alloc->free_async_space = alloc->buffer_size / 2;
782
783 /* Signal binder_alloc is fully initialized */
784 binder_alloc_set_vma(alloc, vma);
785
786 return 0;
787
788err_alloc_buf_struct_failed:
789 kfree(objp: alloc->pages);
790 alloc->pages = NULL;
791err_alloc_pages_failed:
792 alloc->buffer = NULL;
793 mutex_lock(&binder_alloc_mmap_lock);
794 alloc->buffer_size = 0;
795err_already_mapped:
796 mutex_unlock(lock: &binder_alloc_mmap_lock);
797err_invalid_mm:
798 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
799 "%s: %d %lx-%lx %s failed %d\n", __func__,
800 alloc->pid, vma->vm_start, vma->vm_end,
801 failure_string, ret);
802 return ret;
803}
804
805
806void binder_alloc_deferred_release(struct binder_alloc *alloc)
807{
808 struct rb_node *n;
809 int buffers, page_count;
810 struct binder_buffer *buffer;
811
812 buffers = 0;
813 mutex_lock(&alloc->mutex);
814 BUG_ON(alloc->vma);
815
816 while ((n = rb_first(&alloc->allocated_buffers))) {
817 buffer = rb_entry(n, struct binder_buffer, rb_node);
818
819 /* Transaction should already have been freed */
820 BUG_ON(buffer->transaction);
821
822 if (buffer->clear_on_free) {
823 binder_alloc_clear_buf(alloc, buffer);
824 buffer->clear_on_free = false;
825 }
826 binder_free_buf_locked(alloc, buffer);
827 buffers++;
828 }
829
830 while (!list_empty(head: &alloc->buffers)) {
831 buffer = list_first_entry(&alloc->buffers,
832 struct binder_buffer, entry);
833 WARN_ON(!buffer->free);
834
835 list_del(entry: &buffer->entry);
836 WARN_ON_ONCE(!list_empty(&alloc->buffers));
837 kfree(objp: buffer);
838 }
839
840 page_count = 0;
841 if (alloc->pages) {
842 int i;
843
844 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
845 void __user *page_addr;
846 bool on_lru;
847
848 if (!alloc->pages[i].page_ptr)
849 continue;
850
851 on_lru = list_lru_del(lru: &binder_alloc_lru,
852 item: &alloc->pages[i].lru);
853 page_addr = alloc->buffer + i * PAGE_SIZE;
854 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
855 "%s: %d: page %d at %pK %s\n",
856 __func__, alloc->pid, i, page_addr,
857 on_lru ? "on lru" : "active");
858 __free_page(alloc->pages[i].page_ptr);
859 page_count++;
860 }
861 kfree(objp: alloc->pages);
862 }
863 mutex_unlock(lock: &alloc->mutex);
864 if (alloc->mm)
865 mmdrop(mm: alloc->mm);
866
867 binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
868 "%s: %d buffers %d, pages %d\n",
869 __func__, alloc->pid, buffers, page_count);
870}
871
872static void print_binder_buffer(struct seq_file *m, const char *prefix,
873 struct binder_buffer *buffer)
874{
875 seq_printf(m, fmt: "%s %d: %pK size %zd:%zd:%zd %s\n",
876 prefix, buffer->debug_id, buffer->user_data,
877 buffer->data_size, buffer->offsets_size,
878 buffer->extra_buffers_size,
879 buffer->transaction ? "active" : "delivered");
880}
881
882/**
883 * binder_alloc_print_allocated() - print buffer info
884 * @m: seq_file for output via seq_printf()
885 * @alloc: binder_alloc for this proc
886 *
887 * Prints information about every buffer associated with
888 * the binder_alloc state to the given seq_file
889 */
890void binder_alloc_print_allocated(struct seq_file *m,
891 struct binder_alloc *alloc)
892{
893 struct rb_node *n;
894
895 mutex_lock(&alloc->mutex);
896 for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
897 print_binder_buffer(m, prefix: " buffer",
898 rb_entry(n, struct binder_buffer, rb_node));
899 mutex_unlock(lock: &alloc->mutex);
900}
901
902/**
903 * binder_alloc_print_pages() - print page usage
904 * @m: seq_file for output via seq_printf()
905 * @alloc: binder_alloc for this proc
906 */
907void binder_alloc_print_pages(struct seq_file *m,
908 struct binder_alloc *alloc)
909{
910 struct binder_lru_page *page;
911 int i;
912 int active = 0;
913 int lru = 0;
914 int free = 0;
915
916 mutex_lock(&alloc->mutex);
917 /*
918 * Make sure the binder_alloc is fully initialized, otherwise we might
919 * read inconsistent state.
920 */
921 if (binder_alloc_get_vma(alloc) != NULL) {
922 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
923 page = &alloc->pages[i];
924 if (!page->page_ptr)
925 free++;
926 else if (list_empty(head: &page->lru))
927 active++;
928 else
929 lru++;
930 }
931 }
932 mutex_unlock(lock: &alloc->mutex);
933 seq_printf(m, fmt: " pages: %d:%d:%d\n", active, lru, free);
934 seq_printf(m, fmt: " pages high watermark: %zu\n", alloc->pages_high);
935}
936
937/**
938 * binder_alloc_get_allocated_count() - return count of buffers
939 * @alloc: binder_alloc for this proc
940 *
941 * Return: count of allocated buffers
942 */
943int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
944{
945 struct rb_node *n;
946 int count = 0;
947
948 mutex_lock(&alloc->mutex);
949 for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
950 count++;
951 mutex_unlock(lock: &alloc->mutex);
952 return count;
953}
954
955
956/**
957 * binder_alloc_vma_close() - invalidate address space
958 * @alloc: binder_alloc for this proc
959 *
960 * Called from binder_vma_close() when releasing address space.
961 * Clears alloc->vma to prevent new incoming transactions from
962 * allocating more buffers.
963 */
964void binder_alloc_vma_close(struct binder_alloc *alloc)
965{
966 binder_alloc_set_vma(alloc, NULL);
967}
968
969/**
970 * binder_alloc_free_page() - shrinker callback to free pages
971 * @item: item to free
972 * @lock: lock protecting the item
973 * @cb_arg: callback argument
974 *
975 * Called from list_lru_walk() in binder_shrink_scan() to free
976 * up pages when the system is under memory pressure.
977 */
978enum lru_status binder_alloc_free_page(struct list_head *item,
979 struct list_lru_one *lru,
980 spinlock_t *lock,
981 void *cb_arg)
982 __must_hold(lock)
983{
984 struct mm_struct *mm = NULL;
985 struct binder_lru_page *page = container_of(item,
986 struct binder_lru_page,
987 lru);
988 struct binder_alloc *alloc;
989 uintptr_t page_addr;
990 size_t index;
991 struct vm_area_struct *vma;
992
993 alloc = page->alloc;
994 if (!mutex_trylock(lock: &alloc->mutex))
995 goto err_get_alloc_mutex_failed;
996
997 if (!page->page_ptr)
998 goto err_page_already_freed;
999
1000 index = page - alloc->pages;
1001 page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
1002
1003 mm = alloc->mm;
1004 if (!mmget_not_zero(mm))
1005 goto err_mmget;
1006 if (!mmap_read_trylock(mm))
1007 goto err_mmap_read_lock_failed;
1008 vma = binder_alloc_get_vma(alloc);
1009
1010 list_lru_isolate(list: lru, item);
1011 spin_unlock(lock);
1012
1013 if (vma) {
1014 trace_binder_unmap_user_start(alloc, page_index: index);
1015
1016 zap_page_range_single(vma, address: page_addr, PAGE_SIZE, NULL);
1017
1018 trace_binder_unmap_user_end(alloc, page_index: index);
1019 }
1020 mmap_read_unlock(mm);
1021 mmput_async(mm);
1022
1023 trace_binder_unmap_kernel_start(alloc, page_index: index);
1024
1025 __free_page(page->page_ptr);
1026 page->page_ptr = NULL;
1027
1028 trace_binder_unmap_kernel_end(alloc, page_index: index);
1029
1030 spin_lock(lock);
1031 mutex_unlock(lock: &alloc->mutex);
1032 return LRU_REMOVED_RETRY;
1033
1034err_mmap_read_lock_failed:
1035 mmput_async(mm);
1036err_mmget:
1037err_page_already_freed:
1038 mutex_unlock(lock: &alloc->mutex);
1039err_get_alloc_mutex_failed:
1040 return LRU_SKIP;
1041}
1042
1043static unsigned long
1044binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1045{
1046 return list_lru_count(lru: &binder_alloc_lru);
1047}
1048
1049static unsigned long
1050binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1051{
1052 return list_lru_walk(lru: &binder_alloc_lru, isolate: binder_alloc_free_page,
1053 NULL, nr_to_walk: sc->nr_to_scan);
1054}
1055
1056static struct shrinker *binder_shrinker;
1057
1058/**
1059 * binder_alloc_init() - called by binder_open() for per-proc initialization
1060 * @alloc: binder_alloc for this proc
1061 *
1062 * Called from binder_open() to initialize binder_alloc fields for
1063 * new binder proc
1064 */
1065void binder_alloc_init(struct binder_alloc *alloc)
1066{
1067 alloc->pid = current->group_leader->pid;
1068 alloc->mm = current->mm;
1069 mmgrab(mm: alloc->mm);
1070 mutex_init(&alloc->mutex);
1071 INIT_LIST_HEAD(list: &alloc->buffers);
1072}
1073
1074int binder_alloc_shrinker_init(void)
1075{
1076 int ret;
1077
1078 ret = list_lru_init(&binder_alloc_lru);
1079 if (ret)
1080 return ret;
1081
1082 binder_shrinker = shrinker_alloc(flags: 0, fmt: "android-binder");
1083 if (!binder_shrinker) {
1084 list_lru_destroy(lru: &binder_alloc_lru);
1085 return -ENOMEM;
1086 }
1087
1088 binder_shrinker->count_objects = binder_shrink_count;
1089 binder_shrinker->scan_objects = binder_shrink_scan;
1090
1091 shrinker_register(shrinker: binder_shrinker);
1092
1093 return 0;
1094}
1095
1096void binder_alloc_shrinker_exit(void)
1097{
1098 shrinker_free(shrinker: binder_shrinker);
1099 list_lru_destroy(lru: &binder_alloc_lru);
1100}
1101
1102/**
1103 * check_buffer() - verify that buffer/offset is safe to access
1104 * @alloc: binder_alloc for this proc
1105 * @buffer: binder buffer to be accessed
1106 * @offset: offset into @buffer data
1107 * @bytes: bytes to access from offset
1108 *
1109 * Check that the @offset/@bytes are within the size of the given
1110 * @buffer and that the buffer is currently active and not freeable.
1111 * Offsets must also be multiples of sizeof(u32). The kernel is
1112 * allowed to touch the buffer in two cases:
1113 *
1114 * 1) when the buffer is being created:
1115 * (buffer->free == 0 && buffer->allow_user_free == 0)
1116 * 2) when the buffer is being torn down:
1117 * (buffer->free == 0 && buffer->transaction == NULL).
1118 *
1119 * Return: true if the buffer is safe to access
1120 */
1121static inline bool check_buffer(struct binder_alloc *alloc,
1122 struct binder_buffer *buffer,
1123 binder_size_t offset, size_t bytes)
1124{
1125 size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1126
1127 return buffer_size >= bytes &&
1128 offset <= buffer_size - bytes &&
1129 IS_ALIGNED(offset, sizeof(u32)) &&
1130 !buffer->free &&
1131 (!buffer->allow_user_free || !buffer->transaction);
1132}
1133
1134/**
1135 * binder_alloc_get_page() - get kernel pointer for given buffer offset
1136 * @alloc: binder_alloc for this proc
1137 * @buffer: binder buffer to be accessed
1138 * @buffer_offset: offset into @buffer data
1139 * @pgoffp: address to copy final page offset to
1140 *
1141 * Lookup the struct page corresponding to the address
1142 * at @buffer_offset into @buffer->user_data. If @pgoffp is not
1143 * NULL, the byte-offset into the page is written there.
1144 *
1145 * The caller is responsible to ensure that the offset points
1146 * to a valid address within the @buffer and that @buffer is
1147 * not freeable by the user. Since it can't be freed, we are
1148 * guaranteed that the corresponding elements of @alloc->pages[]
1149 * cannot change.
1150 *
1151 * Return: struct page
1152 */
1153static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
1154 struct binder_buffer *buffer,
1155 binder_size_t buffer_offset,
1156 pgoff_t *pgoffp)
1157{
1158 binder_size_t buffer_space_offset = buffer_offset +
1159 (buffer->user_data - alloc->buffer);
1160 pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
1161 size_t index = buffer_space_offset >> PAGE_SHIFT;
1162 struct binder_lru_page *lru_page;
1163
1164 lru_page = &alloc->pages[index];
1165 *pgoffp = pgoff;
1166 return lru_page->page_ptr;
1167}
1168
1169/**
1170 * binder_alloc_clear_buf() - zero out buffer
1171 * @alloc: binder_alloc for this proc
1172 * @buffer: binder buffer to be cleared
1173 *
1174 * memset the given buffer to 0
1175 */
1176static void binder_alloc_clear_buf(struct binder_alloc *alloc,
1177 struct binder_buffer *buffer)
1178{
1179 size_t bytes = binder_alloc_buffer_size(alloc, buffer);
1180 binder_size_t buffer_offset = 0;
1181
1182 while (bytes) {
1183 unsigned long size;
1184 struct page *page;
1185 pgoff_t pgoff;
1186
1187 page = binder_alloc_get_page(alloc, buffer,
1188 buffer_offset, pgoffp: &pgoff);
1189 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1190 memset_page(page, offset: pgoff, val: 0, len: size);
1191 bytes -= size;
1192 buffer_offset += size;
1193 }
1194}
1195
1196/**
1197 * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1198 * @alloc: binder_alloc for this proc
1199 * @buffer: binder buffer to be accessed
1200 * @buffer_offset: offset into @buffer data
1201 * @from: userspace pointer to source buffer
1202 * @bytes: bytes to copy
1203 *
1204 * Copy bytes from source userspace to target buffer.
1205 *
1206 * Return: bytes remaining to be copied
1207 */
1208unsigned long
1209binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1210 struct binder_buffer *buffer,
1211 binder_size_t buffer_offset,
1212 const void __user *from,
1213 size_t bytes)
1214{
1215 if (!check_buffer(alloc, buffer, offset: buffer_offset, bytes))
1216 return bytes;
1217
1218 while (bytes) {
1219 unsigned long size;
1220 unsigned long ret;
1221 struct page *page;
1222 pgoff_t pgoff;
1223 void *kptr;
1224
1225 page = binder_alloc_get_page(alloc, buffer,
1226 buffer_offset, pgoffp: &pgoff);
1227 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1228 kptr = kmap_local_page(page) + pgoff;
1229 ret = copy_from_user(to: kptr, from, n: size);
1230 kunmap_local(kptr);
1231 if (ret)
1232 return bytes - size + ret;
1233 bytes -= size;
1234 from += size;
1235 buffer_offset += size;
1236 }
1237 return 0;
1238}
1239
1240static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1241 bool to_buffer,
1242 struct binder_buffer *buffer,
1243 binder_size_t buffer_offset,
1244 void *ptr,
1245 size_t bytes)
1246{
1247 /* All copies must be 32-bit aligned and 32-bit size */
1248 if (!check_buffer(alloc, buffer, offset: buffer_offset, bytes))
1249 return -EINVAL;
1250
1251 while (bytes) {
1252 unsigned long size;
1253 struct page *page;
1254 pgoff_t pgoff;
1255
1256 page = binder_alloc_get_page(alloc, buffer,
1257 buffer_offset, pgoffp: &pgoff);
1258 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1259 if (to_buffer)
1260 memcpy_to_page(page, offset: pgoff, from: ptr, len: size);
1261 else
1262 memcpy_from_page(to: ptr, page, offset: pgoff, len: size);
1263 bytes -= size;
1264 pgoff = 0;
1265 ptr = ptr + size;
1266 buffer_offset += size;
1267 }
1268 return 0;
1269}
1270
1271int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1272 struct binder_buffer *buffer,
1273 binder_size_t buffer_offset,
1274 void *src,
1275 size_t bytes)
1276{
1277 return binder_alloc_do_buffer_copy(alloc, to_buffer: true, buffer, buffer_offset,
1278 ptr: src, bytes);
1279}
1280
1281int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1282 void *dest,
1283 struct binder_buffer *buffer,
1284 binder_size_t buffer_offset,
1285 size_t bytes)
1286{
1287 return binder_alloc_do_buffer_copy(alloc, to_buffer: false, buffer, buffer_offset,
1288 ptr: dest, bytes);
1289}
1290
1291

source code of linux/drivers/android/binder_alloc.c