binder_alloc.c

   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 <kunit/visibility.h>
  27#include "binder_alloc.h"
  28#include "binder_trace.h"
  29
  30static struct list_lru binder_freelist;
  31
  32static DEFINE_MUTEX(binder_alloc_mmap_lock);
  33
  34enum {
  35	BINDER_DEBUG_USER_ERROR             = 1U << 0,
  36	BINDER_DEBUG_OPEN_CLOSE             = 1U << 1,
  37	BINDER_DEBUG_BUFFER_ALLOC           = 1U << 2,
  38	BINDER_DEBUG_BUFFER_ALLOC_ASYNC     = 1U << 3,
  39};
  40static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR;
  41
  42module_param_named(debug_mask, binder_alloc_debug_mask,
  43		   uint, 0644);
  44
  45#define binder_alloc_debug(mask, x...) \
  46	do { \
  47		if (binder_alloc_debug_mask & mask) \
  48			pr_info_ratelimited(x); \
  49	} while (0)
  50
  51static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
  52{
  53	return list_entry(buffer->entry.next, struct binder_buffer, entry);
  54}
  55
  56static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
  57{
  58	return list_entry(buffer->entry.prev, struct binder_buffer, entry);
  59}
  60
  61VISIBLE_IF_KUNIT size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
  62						 struct binder_buffer *buffer)
  63{
  64	if (list_is_last(&buffer->entry, &alloc->buffers))
  65		return alloc->vm_start + alloc->buffer_size - buffer->user_data;
  66	return binder_buffer_next(buffer)->user_data - buffer->user_data;
  67}
  68EXPORT_SYMBOL_IF_KUNIT(binder_alloc_buffer_size);
  69
  70static void binder_insert_free_buffer(struct binder_alloc *alloc,
  71				      struct binder_buffer *new_buffer)
  72{
  73	struct rb_node **p = &alloc->free_buffers.rb_node;
  74	struct rb_node *parent = NULL;
  75	struct binder_buffer *buffer;
  76	size_t buffer_size;
  77	size_t new_buffer_size;
  78
  79	BUG_ON(!new_buffer->free);
  80
  81	new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
  82
  83	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
  84		     "%d: add free buffer, size %zd, at %p\n",
  85		      alloc->pid, new_buffer_size, new_buffer);
  86
  87	while (*p) {
  88		parent = *p;
  89		buffer = rb_entry(parent, struct binder_buffer, rb_node);
  90		BUG_ON(!buffer->free);
  91
  92		buffer_size = binder_alloc_buffer_size(alloc, buffer);
  93
  94		if (new_buffer_size < buffer_size)
  95			p = &parent->rb_left;
  96		else
  97			p = &parent->rb_right;
  98	}
  99	rb_link_node(&new_buffer->rb_node, parent, p);
 100	rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers);
 101}
 102
 103static void binder_insert_allocated_buffer_locked(
 104		struct binder_alloc *alloc, struct binder_buffer *new_buffer)
 105{
 106	struct rb_node **p = &alloc->allocated_buffers.rb_node;
 107	struct rb_node *parent = NULL;
 108	struct binder_buffer *buffer;
 109
 110	BUG_ON(new_buffer->free);
 111
 112	while (*p) {
 113		parent = *p;
 114		buffer = rb_entry(parent, struct binder_buffer, rb_node);
 115		BUG_ON(buffer->free);
 116
 117		if (new_buffer->user_data < buffer->user_data)
 118			p = &parent->rb_left;
 119		else if (new_buffer->user_data > buffer->user_data)
 120			p = &parent->rb_right;
 121		else
 122			BUG();
 123	}
 124	rb_link_node(&new_buffer->rb_node, parent, p);
 125	rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers);
 126}
 127
 128static struct binder_buffer *binder_alloc_prepare_to_free_locked(
 129		struct binder_alloc *alloc,
 130		unsigned long user_ptr)
 131{
 132	struct rb_node *n = alloc->allocated_buffers.rb_node;
 133	struct binder_buffer *buffer;
 134
 135	while (n) {
 136		buffer = rb_entry(n, struct binder_buffer, rb_node);
 137		BUG_ON(buffer->free);
 138
 139		if (user_ptr < buffer->user_data) {
 140			n = n->rb_left;
 141		} else if (user_ptr > buffer->user_data) {
 142			n = n->rb_right;
 143		} else {
 144			/*
 145			 * Guard against user threads attempting to
 146			 * free the buffer when in use by kernel or
 147			 * after it's already been freed.
 148			 */
 149			if (!buffer->allow_user_free)
 150				return ERR_PTR(-EPERM);
 151			buffer->allow_user_free = 0;
 152			return buffer;
 153		}
 154	}
 155	return NULL;
 156}
 157
 158/**
 159 * binder_alloc_prepare_to_free() - get buffer given user ptr
 160 * @alloc:	binder_alloc for this proc
 161 * @user_ptr:	User pointer to buffer data
 162 *
 163 * Validate userspace pointer to buffer data and return buffer corresponding to
 164 * that user pointer. Search the rb tree for buffer that matches user data
 165 * pointer.
 166 *
 167 * Return:	Pointer to buffer or NULL
 168 */
 169struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
 170						   unsigned long user_ptr)
 171{
 172	guard(mutex)(&alloc->mutex);
 173	return binder_alloc_prepare_to_free_locked(alloc, user_ptr);
 174}
 175
 176static inline void
 177binder_set_installed_page(struct binder_alloc *alloc,
 178			  unsigned long index,
 179			  struct page *page)
 180{
 181	/* Pairs with acquire in binder_get_installed_page() */
 182	smp_store_release(&alloc->pages[index], page);
 183}
 184
 185static inline struct page *
 186binder_get_installed_page(struct binder_alloc *alloc, unsigned long index)
 187{
 188	/* Pairs with release in binder_set_installed_page() */
 189	return smp_load_acquire(&alloc->pages[index]);
 190}
 191
 192static void binder_lru_freelist_add(struct binder_alloc *alloc,
 193				    unsigned long start, unsigned long end)
 194{
 195	unsigned long page_addr;
 196	struct page *page;
 197
 198	trace_binder_update_page_range(alloc, false, start, end);
 199
 200	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 201		size_t index;
 202		int ret;
 203
 204		index = (page_addr - alloc->vm_start) / PAGE_SIZE;
 205		page = binder_get_installed_page(alloc, index);
 206		if (!page)
 207			continue;
 208
 209		trace_binder_free_lru_start(alloc, index);
 210
 211		ret = list_lru_add(alloc->freelist,
 212				   page_to_lru(page),
 213				   page_to_nid(page),
 214				   NULL);
 215		WARN_ON(!ret);
 216
 217		trace_binder_free_lru_end(alloc, index);
 218	}
 219}
 220
 221static inline
 222void binder_alloc_set_mapped(struct binder_alloc *alloc, bool state)
 223{
 224	/* pairs with smp_load_acquire in binder_alloc_is_mapped() */
 225	smp_store_release(&alloc->mapped, state);
 226}
 227
 228static inline bool binder_alloc_is_mapped(struct binder_alloc *alloc)
 229{
 230	/* pairs with smp_store_release in binder_alloc_set_mapped() */
 231	return smp_load_acquire(&alloc->mapped);
 232}
 233
 234static struct page *binder_page_lookup(struct binder_alloc *alloc,
 235				       unsigned long addr)
 236{
 237	struct mm_struct *mm = alloc->mm;
 238	struct page *page;
 239	long npages = 0;
 240
 241	/*
 242	 * Find an existing page in the remote mm. If missing,
 243	 * don't attempt to fault-in just propagate an error.
 244	 */
 245	mmap_read_lock(mm);
 246	if (binder_alloc_is_mapped(alloc))
 247		npages = get_user_pages_remote(mm, addr, 1, FOLL_NOFAULT,
 248					       &page, NULL);
 249	mmap_read_unlock(mm);
 250
 251	return npages > 0 ? page : NULL;
 252}
 253
 254static int binder_page_insert(struct binder_alloc *alloc,
 255			      unsigned long addr,
 256			      struct page *page)
 257{
 258	struct mm_struct *mm = alloc->mm;
 259	struct vm_area_struct *vma;
 260	int ret = -ESRCH;
 261
 262	/* attempt per-vma lock first */
 263	vma = lock_vma_under_rcu(mm, addr);
 264	if (vma) {
 265		if (binder_alloc_is_mapped(alloc))
 266			ret = vm_insert_page(vma, addr, page);
 267		vma_end_read(vma);
 268		return ret;
 269	}
 270
 271	/* fall back to mmap_lock */
 272	mmap_read_lock(mm);
 273	vma = vma_lookup(mm, addr);
 274	if (vma && binder_alloc_is_mapped(alloc))
 275		ret = vm_insert_page(vma, addr, page);
 276	mmap_read_unlock(mm);
 277
 278	return ret;
 279}
 280
 281static struct page *binder_page_alloc(struct binder_alloc *alloc,
 282				      unsigned long index)
 283{
 284	struct binder_shrinker_mdata *mdata;
 285	struct page *page;
 286
 287	page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
 288	if (!page)
 289		return NULL;
 290
 291	/* allocate and install shrinker metadata under page->private */
 292	mdata = kzalloc(sizeof(*mdata), GFP_KERNEL);
 293	if (!mdata) {
 294		__free_page(page);
 295		return NULL;
 296	}
 297
 298	mdata->alloc = alloc;
 299	mdata->page_index = index;
 300	INIT_LIST_HEAD(&mdata->lru);
 301	set_page_private(page, (unsigned long)mdata);
 302
 303	return page;
 304}
 305
 306static void binder_free_page(struct page *page)
 307{
 308	kfree((struct binder_shrinker_mdata *)page_private(page));
 309	__free_page(page);
 310}
 311
 312static int binder_install_single_page(struct binder_alloc *alloc,
 313				      unsigned long index,
 314				      unsigned long addr)
 315{
 316	struct page *page;
 317	int ret;
 318
 319	if (!mmget_not_zero(alloc->mm))
 320		return -ESRCH;
 321
 322	page = binder_page_alloc(alloc, index);
 323	if (!page) {
 324		ret = -ENOMEM;
 325		goto out;
 326	}
 327
 328	ret = binder_page_insert(alloc, addr, page);
 329	switch (ret) {
 330	case -EBUSY:
 331		/*
 332		 * EBUSY is ok. Someone installed the pte first but the
 333		 * alloc->pages[index] has not been updated yet. Discard
 334		 * our page and look up the one already installed.
 335		 */
 336		ret = 0;
 337		binder_free_page(page);
 338		page = binder_page_lookup(alloc, addr);
 339		if (!page) {
 340			pr_err("%d: failed to find page at offset %lx\n",
 341			       alloc->pid, addr - alloc->vm_start);
 342			ret = -ESRCH;
 343			break;
 344		}
 345		fallthrough;
 346	case 0:
 347		/* Mark page installation complete and safe to use */
 348		binder_set_installed_page(alloc, index, page);
 349		break;
 350	default:
 351		binder_free_page(page);
 352		pr_err("%d: %s failed to insert page at offset %lx with %d\n",
 353		       alloc->pid, __func__, addr - alloc->vm_start, ret);
 354		break;
 355	}
 356out:
 357	mmput_async(alloc->mm);
 358	return ret;
 359}
 360
 361static int binder_install_buffer_pages(struct binder_alloc *alloc,
 362				       struct binder_buffer *buffer,
 363				       size_t size)
 364{
 365	unsigned long start, final;
 366	unsigned long page_addr;
 367
 368	start = buffer->user_data & PAGE_MASK;
 369	final = PAGE_ALIGN(buffer->user_data + size);
 370
 371	for (page_addr = start; page_addr < final; page_addr += PAGE_SIZE) {
 372		unsigned long index;
 373		int ret;
 374
 375		index = (page_addr - alloc->vm_start) / PAGE_SIZE;
 376		if (binder_get_installed_page(alloc, index))
 377			continue;
 378
 379		trace_binder_alloc_page_start(alloc, index);
 380
 381		ret = binder_install_single_page(alloc, index, page_addr);
 382		if (ret)
 383			return ret;
 384
 385		trace_binder_alloc_page_end(alloc, index);
 386	}
 387
 388	return 0;
 389}
 390
 391/* The range of pages should exclude those shared with other buffers */
 392static void binder_lru_freelist_del(struct binder_alloc *alloc,
 393				    unsigned long start, unsigned long end)
 394{
 395	unsigned long page_addr;
 396	struct page *page;
 397
 398	trace_binder_update_page_range(alloc, true, start, end);
 399
 400	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 401		unsigned long index;
 402		bool on_lru;
 403
 404		index = (page_addr - alloc->vm_start) / PAGE_SIZE;
 405		page = binder_get_installed_page(alloc, index);
 406
 407		if (page) {
 408			trace_binder_alloc_lru_start(alloc, index);
 409
 410			on_lru = list_lru_del(alloc->freelist,
 411					      page_to_lru(page),
 412					      page_to_nid(page),
 413					      NULL);
 414			WARN_ON(!on_lru);
 415
 416			trace_binder_alloc_lru_end(alloc, index);
 417			continue;
 418		}
 419
 420		if (index + 1 > alloc->pages_high)
 421			alloc->pages_high = index + 1;
 422	}
 423}
 424
 425static void debug_no_space_locked(struct binder_alloc *alloc)
 426{
 427	size_t largest_alloc_size = 0;
 428	struct binder_buffer *buffer;
 429	size_t allocated_buffers = 0;
 430	size_t largest_free_size = 0;
 431	size_t total_alloc_size = 0;
 432	size_t total_free_size = 0;
 433	size_t free_buffers = 0;
 434	size_t buffer_size;
 435	struct rb_node *n;
 436
 437	for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
 438		buffer = rb_entry(n, struct binder_buffer, rb_node);
 439		buffer_size = binder_alloc_buffer_size(alloc, buffer);
 440		allocated_buffers++;
 441		total_alloc_size += buffer_size;
 442		if (buffer_size > largest_alloc_size)
 443			largest_alloc_size = buffer_size;
 444	}
 445
 446	for (n = rb_first(&alloc->free_buffers); n; n = rb_next(n)) {
 447		buffer = rb_entry(n, struct binder_buffer, rb_node);
 448		buffer_size = binder_alloc_buffer_size(alloc, buffer);
 449		free_buffers++;
 450		total_free_size += buffer_size;
 451		if (buffer_size > largest_free_size)
 452			largest_free_size = buffer_size;
 453	}
 454
 455	binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 456			   "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
 457			   total_alloc_size, allocated_buffers,
 458			   largest_alloc_size, total_free_size,
 459			   free_buffers, largest_free_size);
 460}
 461
 462static bool debug_low_async_space_locked(struct binder_alloc *alloc)
 463{
 464	/*
 465	 * Find the amount and size of buffers allocated by the current caller;
 466	 * The idea is that once we cross the threshold, whoever is responsible
 467	 * for the low async space is likely to try to send another async txn,
 468	 * and at some point we'll catch them in the act. This is more efficient
 469	 * than keeping a map per pid.
 470	 */
 471	struct binder_buffer *buffer;
 472	size_t total_alloc_size = 0;
 473	int pid = current->tgid;
 474	size_t num_buffers = 0;
 475	struct rb_node *n;
 476
 477	/*
 478	 * Only start detecting spammers once we have less than 20% of async
 479	 * space left (which is less than 10% of total buffer size).
 480	 */
 481	if (alloc->free_async_space >= alloc->buffer_size / 10) {
 482		alloc->oneway_spam_detected = false;
 483		return false;
 484	}
 485
 486	for (n = rb_first(&alloc->allocated_buffers); n != NULL;
 487		 n = rb_next(n)) {
 488		buffer = rb_entry(n, struct binder_buffer, rb_node);
 489		if (buffer->pid != pid)
 490			continue;
 491		if (!buffer->async_transaction)
 492			continue;
 493		total_alloc_size += binder_alloc_buffer_size(alloc, buffer);
 494		num_buffers++;
 495	}
 496
 497	/*
 498	 * Warn if this pid has more than 50 transactions, or more than 50% of
 499	 * async space (which is 25% of total buffer size). Oneway spam is only
 500	 * detected when the threshold is exceeded.
 501	 */
 502	if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
 503		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 504			     "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
 505			      alloc->pid, pid, num_buffers, total_alloc_size);
 506		if (!alloc->oneway_spam_detected) {
 507			alloc->oneway_spam_detected = true;
 508			return true;
 509		}
 510	}
 511	return false;
 512}
 513
 514/* Callers preallocate @new_buffer, it is freed by this function if unused */
 515static struct binder_buffer *binder_alloc_new_buf_locked(
 516				struct binder_alloc *alloc,
 517				struct binder_buffer *new_buffer,
 518				size_t size,
 519				int is_async)
 520{
 521	struct rb_node *n = alloc->free_buffers.rb_node;
 522	struct rb_node *best_fit = NULL;
 523	struct binder_buffer *buffer;
 524	unsigned long next_used_page;
 525	unsigned long curr_last_page;
 526	size_t buffer_size;
 527
 528	if (is_async && alloc->free_async_space < size) {
 529		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 530			     "%d: binder_alloc_buf size %zd failed, no async space left\n",
 531			      alloc->pid, size);
 532		buffer = ERR_PTR(-ENOSPC);
 533		goto out;
 534	}
 535
 536	while (n) {
 537		buffer = rb_entry(n, struct binder_buffer, rb_node);
 538		BUG_ON(!buffer->free);
 539		buffer_size = binder_alloc_buffer_size(alloc, buffer);
 540
 541		if (size < buffer_size) {
 542			best_fit = n;
 543			n = n->rb_left;
 544		} else if (size > buffer_size) {
 545			n = n->rb_right;
 546		} else {
 547			best_fit = n;
 548			break;
 549		}
 550	}
 551
 552	if (unlikely(!best_fit)) {
 553		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 554				   "%d: binder_alloc_buf size %zd failed, no address space\n",
 555				   alloc->pid, size);
 556		debug_no_space_locked(alloc);
 557		buffer = ERR_PTR(-ENOSPC);
 558		goto out;
 559	}
 560
 561	if (buffer_size != size) {
 562		/* Found an oversized buffer and needs to be split */
 563		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
 564		buffer_size = binder_alloc_buffer_size(alloc, buffer);
 565
 566		WARN_ON(n || buffer_size == size);
 567		new_buffer->user_data = buffer->user_data + size;
 568		list_add(&new_buffer->entry, &buffer->entry);
 569		new_buffer->free = 1;
 570		binder_insert_free_buffer(alloc, new_buffer);
 571		new_buffer = NULL;
 572	}
 573
 574	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 575		     "%d: binder_alloc_buf size %zd got buffer %p size %zd\n",
 576		      alloc->pid, size, buffer, buffer_size);
 577
 578	/*
 579	 * Now we remove the pages from the freelist. A clever calculation
 580	 * with buffer_size determines if the last page is shared with an
 581	 * adjacent in-use buffer. In such case, the page has been already
 582	 * removed from the freelist so we trim our range short.
 583	 */
 584	next_used_page = (buffer->user_data + buffer_size) & PAGE_MASK;
 585	curr_last_page = PAGE_ALIGN(buffer->user_data + size);
 586	binder_lru_freelist_del(alloc, PAGE_ALIGN(buffer->user_data),
 587				min(next_used_page, curr_last_page));
 588
 589	rb_erase(&buffer->rb_node, &alloc->free_buffers);
 590	buffer->free = 0;
 591	buffer->allow_user_free = 0;
 592	binder_insert_allocated_buffer_locked(alloc, buffer);
 593	buffer->async_transaction = is_async;
 594	buffer->oneway_spam_suspect = false;
 595	if (is_async) {
 596		alloc->free_async_space -= size;
 597		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 598			     "%d: binder_alloc_buf size %zd async free %zd\n",
 599			      alloc->pid, size, alloc->free_async_space);
 600		if (debug_low_async_space_locked(alloc))
 601			buffer->oneway_spam_suspect = true;
 602	}
 603
 604out:
 605	/* Discard possibly unused new_buffer */
 606	kfree(new_buffer);
 607	return buffer;
 608}
 609
 610/* Calculate the sanitized total size, returns 0 for invalid request */
 611static inline size_t sanitized_size(size_t data_size,
 612				    size_t offsets_size,
 613				    size_t extra_buffers_size)
 614{
 615	size_t total, tmp;
 616
 617	/* Align to pointer size and check for overflows */
 618	tmp = ALIGN(data_size, sizeof(void *)) +
 619		ALIGN(offsets_size, sizeof(void *));
 620	if (tmp < data_size || tmp < offsets_size)
 621		return 0;
 622	total = tmp + ALIGN(extra_buffers_size, sizeof(void *));
 623	if (total < tmp || total < extra_buffers_size)
 624		return 0;
 625
 626	/* Pad 0-sized buffers so they get a unique address */
 627	total = max(total, sizeof(void *));
 628
 629	return total;
 630}
 631
 632/**
 633 * binder_alloc_new_buf() - Allocate a new binder buffer
 634 * @alloc:              binder_alloc for this proc
 635 * @data_size:          size of user data buffer
 636 * @offsets_size:       user specified buffer offset
 637 * @extra_buffers_size: size of extra space for meta-data (eg, security context)
 638 * @is_async:           buffer for async transaction
 639 *
 640 * Allocate a new buffer given the requested sizes. Returns
 641 * the kernel version of the buffer pointer. The size allocated
 642 * is the sum of the three given sizes (each rounded up to
 643 * pointer-sized boundary)
 644 *
 645 * Return:	The allocated buffer or %ERR_PTR(-errno) if error
 646 */
 647struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 648					   size_t data_size,
 649					   size_t offsets_size,
 650					   size_t extra_buffers_size,
 651					   int is_async)
 652{
 653	struct binder_buffer *buffer, *next;
 654	size_t size;
 655	int ret;
 656
 657	/* Check binder_alloc is fully initialized */
 658	if (!binder_alloc_is_mapped(alloc)) {
 659		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 660				   "%d: binder_alloc_buf, no vma\n",
 661				   alloc->pid);
 662		return ERR_PTR(-ESRCH);
 663	}
 664
 665	size = sanitized_size(data_size, offsets_size, extra_buffers_size);
 666	if (unlikely(!size)) {
 667		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 668				   "%d: got transaction with invalid size %zd-%zd-%zd\n",
 669				   alloc->pid, data_size, offsets_size,
 670				   extra_buffers_size);
 671		return ERR_PTR(-EINVAL);
 672	}
 673
 674	/* Preallocate the next buffer */
 675	next = kzalloc(sizeof(*next), GFP_KERNEL);
 676	if (!next)
 677		return ERR_PTR(-ENOMEM);
 678
 679	mutex_lock(&alloc->mutex);
 680	buffer = binder_alloc_new_buf_locked(alloc, next, size, is_async);
 681	if (IS_ERR(buffer)) {
 682		mutex_unlock(&alloc->mutex);
 683		goto out;
 684	}
 685
 686	buffer->data_size = data_size;
 687	buffer->offsets_size = offsets_size;
 688	buffer->extra_buffers_size = extra_buffers_size;
 689	buffer->pid = current->tgid;
 690	mutex_unlock(&alloc->mutex);
 691
 692	ret = binder_install_buffer_pages(alloc, buffer, size);
 693	if (ret) {
 694		binder_alloc_free_buf(alloc, buffer);
 695		buffer = ERR_PTR(ret);
 696	}
 697out:
 698	return buffer;
 699}
 700EXPORT_SYMBOL_IF_KUNIT(binder_alloc_new_buf);
 701
 702static unsigned long buffer_start_page(struct binder_buffer *buffer)
 703{
 704	return buffer->user_data & PAGE_MASK;
 705}
 706
 707static unsigned long prev_buffer_end_page(struct binder_buffer *buffer)
 708{
 709	return (buffer->user_data - 1) & PAGE_MASK;
 710}
 711
 712static void binder_delete_free_buffer(struct binder_alloc *alloc,
 713				      struct binder_buffer *buffer)
 714{
 715	struct binder_buffer *prev, *next;
 716
 717	if (PAGE_ALIGNED(buffer->user_data))
 718		goto skip_freelist;
 719
 720	BUG_ON(alloc->buffers.next == &buffer->entry);
 721	prev = binder_buffer_prev(buffer);
 722	BUG_ON(!prev->free);
 723	if (prev_buffer_end_page(prev) == buffer_start_page(buffer))
 724		goto skip_freelist;
 725
 726	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 727		next = binder_buffer_next(buffer);
 728		if (buffer_start_page(next) == buffer_start_page(buffer))
 729			goto skip_freelist;
 730	}
 731
 732	binder_lru_freelist_add(alloc, buffer_start_page(buffer),
 733				buffer_start_page(buffer) + PAGE_SIZE);
 734skip_freelist:
 735	list_del(&buffer->entry);
 736	kfree(buffer);
 737}
 738
 739static void binder_free_buf_locked(struct binder_alloc *alloc,
 740				   struct binder_buffer *buffer)
 741{
 742	size_t size, buffer_size;
 743
 744	buffer_size = binder_alloc_buffer_size(alloc, buffer);
 745
 746	size = ALIGN(buffer->data_size, sizeof(void *)) +
 747		ALIGN(buffer->offsets_size, sizeof(void *)) +
 748		ALIGN(buffer->extra_buffers_size, sizeof(void *));
 749
 750	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 751		     "%d: binder_free_buf %p size %zd buffer_size %zd\n",
 752		      alloc->pid, buffer, size, buffer_size);
 753
 754	BUG_ON(buffer->free);
 755	BUG_ON(size > buffer_size);
 756	BUG_ON(buffer->transaction != NULL);
 757	BUG_ON(buffer->user_data < alloc->vm_start);
 758	BUG_ON(buffer->user_data > alloc->vm_start + alloc->buffer_size);
 759
 760	if (buffer->async_transaction) {
 761		alloc->free_async_space += buffer_size;
 762		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 763			     "%d: binder_free_buf size %zd async free %zd\n",
 764			      alloc->pid, size, alloc->free_async_space);
 765	}
 766
 767	binder_lru_freelist_add(alloc, PAGE_ALIGN(buffer->user_data),
 768				(buffer->user_data + buffer_size) & PAGE_MASK);
 769
 770	rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
 771	buffer->free = 1;
 772	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 773		struct binder_buffer *next = binder_buffer_next(buffer);
 774
 775		if (next->free) {
 776			rb_erase(&next->rb_node, &alloc->free_buffers);
 777			binder_delete_free_buffer(alloc, next);
 778		}
 779	}
 780	if (alloc->buffers.next != &buffer->entry) {
 781		struct binder_buffer *prev = binder_buffer_prev(buffer);
 782
 783		if (prev->free) {
 784			binder_delete_free_buffer(alloc, buffer);
 785			rb_erase(&prev->rb_node, &alloc->free_buffers);
 786			buffer = prev;
 787		}
 788	}
 789	binder_insert_free_buffer(alloc, buffer);
 790}
 791
 792/**
 793 * binder_alloc_get_page() - get kernel pointer for given buffer offset
 794 * @alloc: binder_alloc for this proc
 795 * @buffer: binder buffer to be accessed
 796 * @buffer_offset: offset into @buffer data
 797 * @pgoffp: address to copy final page offset to
 798 *
 799 * Lookup the struct page corresponding to the address
 800 * at @buffer_offset into @buffer->user_data. If @pgoffp is not
 801 * NULL, the byte-offset into the page is written there.
 802 *
 803 * The caller is responsible to ensure that the offset points
 804 * to a valid address within the @buffer and that @buffer is
 805 * not freeable by the user. Since it can't be freed, we are
 806 * guaranteed that the corresponding elements of @alloc->pages[]
 807 * cannot change.
 808 *
 809 * Return: struct page
 810 */
 811static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
 812					  struct binder_buffer *buffer,
 813					  binder_size_t buffer_offset,
 814					  pgoff_t *pgoffp)
 815{
 816	binder_size_t buffer_space_offset = buffer_offset +
 817		(buffer->user_data - alloc->vm_start);
 818	pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
 819	size_t index = buffer_space_offset >> PAGE_SHIFT;
 820
 821	*pgoffp = pgoff;
 822
 823	return alloc->pages[index];
 824}
 825
 826/**
 827 * binder_alloc_clear_buf() - zero out buffer
 828 * @alloc: binder_alloc for this proc
 829 * @buffer: binder buffer to be cleared
 830 *
 831 * memset the given buffer to 0
 832 */
 833static void binder_alloc_clear_buf(struct binder_alloc *alloc,
 834				   struct binder_buffer *buffer)
 835{
 836	size_t bytes = binder_alloc_buffer_size(alloc, buffer);
 837	binder_size_t buffer_offset = 0;
 838
 839	while (bytes) {
 840		unsigned long size;
 841		struct page *page;
 842		pgoff_t pgoff;
 843
 844		page = binder_alloc_get_page(alloc, buffer,
 845					     buffer_offset, &pgoff);
 846		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
 847		memset_page(page, pgoff, 0, size);
 848		bytes -= size;
 849		buffer_offset += size;
 850	}
 851}
 852
 853/**
 854 * binder_alloc_free_buf() - free a binder buffer
 855 * @alloc:	binder_alloc for this proc
 856 * @buffer:	kernel pointer to buffer
 857 *
 858 * Free the buffer allocated via binder_alloc_new_buf()
 859 */
 860void binder_alloc_free_buf(struct binder_alloc *alloc,
 861			    struct binder_buffer *buffer)
 862{
 863	/*
 864	 * We could eliminate the call to binder_alloc_clear_buf()
 865	 * from binder_alloc_deferred_release() by moving this to
 866	 * binder_free_buf_locked(). However, that could
 867	 * increase contention for the alloc mutex if clear_on_free
 868	 * is used frequently for large buffers. The mutex is not
 869	 * needed for correctness here.
 870	 */
 871	if (buffer->clear_on_free) {
 872		binder_alloc_clear_buf(alloc, buffer);
 873		buffer->clear_on_free = false;
 874	}
 875	mutex_lock(&alloc->mutex);
 876	binder_free_buf_locked(alloc, buffer);
 877	mutex_unlock(&alloc->mutex);
 878}
 879EXPORT_SYMBOL_IF_KUNIT(binder_alloc_free_buf);
 880
 881/**
 882 * binder_alloc_mmap_handler() - map virtual address space for proc
 883 * @alloc:	alloc structure for this proc
 884 * @vma:	vma passed to mmap()
 885 *
 886 * Called by binder_mmap() to initialize the space specified in
 887 * vma for allocating binder buffers
 888 *
 889 * Return:
 890 *      0 = success
 891 *      -EBUSY = address space already mapped
 892 *      -ENOMEM = failed to map memory to given address space
 893 */
 894int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 895			      struct vm_area_struct *vma)
 896{
 897	struct binder_buffer *buffer;
 898	const char *failure_string;
 899	int ret;
 900
 901	if (unlikely(vma->vm_mm != alloc->mm)) {
 902		ret = -EINVAL;
 903		failure_string = "invalid vma->vm_mm";
 904		goto err_invalid_mm;
 905	}
 906
 907	mutex_lock(&binder_alloc_mmap_lock);
 908	if (alloc->buffer_size) {
 909		ret = -EBUSY;
 910		failure_string = "already mapped";
 911		goto err_already_mapped;
 912	}
 913	alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
 914				   SZ_4M);
 915	mutex_unlock(&binder_alloc_mmap_lock);
 916
 917	alloc->vm_start = vma->vm_start;
 918
 919	alloc->pages = kvcalloc(alloc->buffer_size / PAGE_SIZE,
 920				sizeof(alloc->pages[0]),
 921				GFP_KERNEL);
 922	if (!alloc->pages) {
 923		ret = -ENOMEM;
 924		failure_string = "alloc page array";
 925		goto err_alloc_pages_failed;
 926	}
 927
 928	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 929	if (!buffer) {
 930		ret = -ENOMEM;
 931		failure_string = "alloc buffer struct";
 932		goto err_alloc_buf_struct_failed;
 933	}
 934
 935	buffer->user_data = alloc->vm_start;
 936	list_add(&buffer->entry, &alloc->buffers);
 937	buffer->free = 1;
 938	binder_insert_free_buffer(alloc, buffer);
 939	alloc->free_async_space = alloc->buffer_size / 2;
 940
 941	/* Signal binder_alloc is fully initialized */
 942	binder_alloc_set_mapped(alloc, true);
 943
 944	return 0;
 945
 946err_alloc_buf_struct_failed:
 947	kvfree(alloc->pages);
 948	alloc->pages = NULL;
 949err_alloc_pages_failed:
 950	alloc->vm_start = 0;
 951	mutex_lock(&binder_alloc_mmap_lock);
 952	alloc->buffer_size = 0;
 953err_already_mapped:
 954	mutex_unlock(&binder_alloc_mmap_lock);
 955err_invalid_mm:
 956	binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 957			   "%s: %d %lx-%lx %s failed %d\n", __func__,
 958			   alloc->pid, vma->vm_start, vma->vm_end,
 959			   failure_string, ret);
 960	return ret;
 961}
 962EXPORT_SYMBOL_IF_KUNIT(binder_alloc_mmap_handler);
 963
 964void binder_alloc_deferred_release(struct binder_alloc *alloc)
 965{
 966	struct rb_node *n;
 967	int buffers, page_count;
 968	struct binder_buffer *buffer;
 969
 970	buffers = 0;
 971	mutex_lock(&alloc->mutex);
 972	BUG_ON(alloc->mapped);
 973
 974	while ((n = rb_first(&alloc->allocated_buffers))) {
 975		buffer = rb_entry(n, struct binder_buffer, rb_node);
 976
 977		/* Transaction should already have been freed */
 978		BUG_ON(buffer->transaction);
 979
 980		if (buffer->clear_on_free) {
 981			binder_alloc_clear_buf(alloc, buffer);
 982			buffer->clear_on_free = false;
 983		}
 984		binder_free_buf_locked(alloc, buffer);
 985		buffers++;
 986	}
 987
 988	while (!list_empty(&alloc->buffers)) {
 989		buffer = list_first_entry(&alloc->buffers,
 990					  struct binder_buffer, entry);
 991		WARN_ON(!buffer->free);
 992
 993		list_del(&buffer->entry);
 994		WARN_ON_ONCE(!list_empty(&alloc->buffers));
 995		kfree(buffer);
 996	}
 997
 998	page_count = 0;
 999	if (alloc->pages) {
1000		int i;
1001
1002		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
1003			struct page *page;
1004			bool on_lru;
1005
1006			page = binder_get_installed_page(alloc, i);
1007			if (!page)
1008				continue;
1009
1010			on_lru = list_lru_del(alloc->freelist,
1011					      page_to_lru(page),
1012					      page_to_nid(page),
1013					      NULL);
1014			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
1015				     "%s: %d: page %d %s\n",
1016				     __func__, alloc->pid, i,
1017				     on_lru ? "on lru" : "active");
1018			binder_free_page(page);
1019			page_count++;
1020		}
1021	}
1022	mutex_unlock(&alloc->mutex);
1023	kvfree(alloc->pages);
1024	if (alloc->mm)
1025		mmdrop(alloc->mm);
1026
1027	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
1028		     "%s: %d buffers %d, pages %d\n",
1029		     __func__, alloc->pid, buffers, page_count);
1030}
1031EXPORT_SYMBOL_IF_KUNIT(binder_alloc_deferred_release);
1032
1033/**
1034 * binder_alloc_print_allocated() - print buffer info
1035 * @m:     seq_file for output via seq_printf()
1036 * @alloc: binder_alloc for this proc
1037 *
1038 * Prints information about every buffer associated with
1039 * the binder_alloc state to the given seq_file
1040 */
1041void binder_alloc_print_allocated(struct seq_file *m,
1042				  struct binder_alloc *alloc)
1043{
1044	struct binder_buffer *buffer;
1045	struct rb_node *n;
1046
1047	guard(mutex)(&alloc->mutex);
1048	for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
1049		buffer = rb_entry(n, struct binder_buffer, rb_node);
1050		seq_printf(m, "  buffer %d: %lx size %zd:%zd:%zd %s\n",
1051			   buffer->debug_id,
1052			   buffer->user_data - alloc->vm_start,
1053			   buffer->data_size, buffer->offsets_size,
1054			   buffer->extra_buffers_size,
1055			   buffer->transaction ? "active" : "delivered");
1056	}
1057}
1058
1059/**
1060 * binder_alloc_print_pages() - print page usage
1061 * @m:     seq_file for output via seq_printf()
1062 * @alloc: binder_alloc for this proc
1063 */
1064void binder_alloc_print_pages(struct seq_file *m,
1065			      struct binder_alloc *alloc)
1066{
1067	struct page *page;
1068	int i;
1069	int active = 0;
1070	int lru = 0;
1071	int free = 0;
1072
1073	mutex_lock(&alloc->mutex);
1074	/*
1075	 * Make sure the binder_alloc is fully initialized, otherwise we might
1076	 * read inconsistent state.
1077	 */
1078	if (binder_alloc_is_mapped(alloc)) {
1079		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
1080			page = binder_get_installed_page(alloc, i);
1081			if (!page)
1082				free++;
1083			else if (list_empty(page_to_lru(page)))
1084				active++;
1085			else
1086				lru++;
1087		}
1088	}
1089	mutex_unlock(&alloc->mutex);
1090	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
1091	seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
1092}
1093
1094/**
1095 * binder_alloc_get_allocated_count() - return count of buffers
1096 * @alloc: binder_alloc for this proc
1097 *
1098 * Return: count of allocated buffers
1099 */
1100int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
1101{
1102	struct rb_node *n;
1103	int count = 0;
1104
1105	guard(mutex)(&alloc->mutex);
1106	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
1107		count++;
1108	return count;
1109}
1110
1111
1112/**
1113 * binder_alloc_vma_close() - invalidate address space
1114 * @alloc: binder_alloc for this proc
1115 *
1116 * Called from binder_vma_close() when releasing address space.
1117 * Clears alloc->mapped to prevent new incoming transactions from
1118 * allocating more buffers.
1119 */
1120void binder_alloc_vma_close(struct binder_alloc *alloc)
1121{
1122	binder_alloc_set_mapped(alloc, false);
1123}
1124EXPORT_SYMBOL_IF_KUNIT(binder_alloc_vma_close);
1125
1126/**
1127 * binder_alloc_free_page() - shrinker callback to free pages
1128 * @item:   item to free
1129 * @lru:    list_lru instance of the item
1130 * @cb_arg: callback argument
1131 *
1132 * Called from list_lru_walk() in binder_shrink_scan() to free
1133 * up pages when the system is under memory pressure.
1134 */
1135enum lru_status binder_alloc_free_page(struct list_head *item,
1136				       struct list_lru_one *lru,
1137				       void *cb_arg)
1138	__must_hold(&lru->lock)
1139{
1140	struct binder_shrinker_mdata *mdata = container_of(item, typeof(*mdata), lru);
1141	struct binder_alloc *alloc = mdata->alloc;
1142	struct mm_struct *mm = alloc->mm;
1143	struct vm_area_struct *vma;
1144	struct page *page_to_free;
1145	unsigned long page_addr;
1146	int mm_locked = 0;
1147	size_t index;
1148
1149	if (!mmget_not_zero(mm))
1150		goto err_mmget;
1151
1152	index = mdata->page_index;
1153	page_addr = alloc->vm_start + index * PAGE_SIZE;
1154
1155	/* attempt per-vma lock first */
1156	vma = lock_vma_under_rcu(mm, page_addr);
1157	if (!vma) {
1158		/* fall back to mmap_lock */
1159		if (!mmap_read_trylock(mm))
1160			goto err_mmap_read_lock_failed;
1161		mm_locked = 1;
1162		vma = vma_lookup(mm, page_addr);
1163	}
1164
1165	if (!mutex_trylock(&alloc->mutex))
1166		goto err_get_alloc_mutex_failed;
1167
1168	/*
1169	 * Since a binder_alloc can only be mapped once, we ensure
1170	 * the vma corresponds to this mapping by checking whether
1171	 * the binder_alloc is still mapped.
1172	 */
1173	if (vma && !binder_alloc_is_mapped(alloc))
1174		goto err_invalid_vma;
1175
1176	trace_binder_unmap_kernel_start(alloc, index);
1177
1178	page_to_free = alloc->pages[index];
1179	binder_set_installed_page(alloc, index, NULL);
1180
1181	trace_binder_unmap_kernel_end(alloc, index);
1182
1183	list_lru_isolate(lru, item);
1184	spin_unlock(&lru->lock);
1185
1186	if (vma) {
1187		trace_binder_unmap_user_start(alloc, index);
1188
1189		zap_page_range_single(vma, page_addr, PAGE_SIZE, NULL);
1190
1191		trace_binder_unmap_user_end(alloc, index);
1192	}
1193
1194	mutex_unlock(&alloc->mutex);
1195	if (mm_locked)
1196		mmap_read_unlock(mm);
1197	else
1198		vma_end_read(vma);
1199	mmput_async(mm);
1200	binder_free_page(page_to_free);
1201
1202	return LRU_REMOVED_RETRY;
1203
1204err_invalid_vma:
1205	mutex_unlock(&alloc->mutex);
1206err_get_alloc_mutex_failed:
1207	if (mm_locked)
1208		mmap_read_unlock(mm);
1209	else
1210		vma_end_read(vma);
1211err_mmap_read_lock_failed:
1212	mmput_async(mm);
1213err_mmget:
1214	return LRU_SKIP;
1215}
1216EXPORT_SYMBOL_IF_KUNIT(binder_alloc_free_page);
1217
1218static unsigned long
1219binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1220{
1221	return list_lru_count(&binder_freelist);
1222}
1223
1224static unsigned long
1225binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1226{
1227	return list_lru_walk(&binder_freelist, binder_alloc_free_page,
1228			    NULL, sc->nr_to_scan);
1229}
1230
1231static struct shrinker *binder_shrinker;
1232
1233VISIBLE_IF_KUNIT void __binder_alloc_init(struct binder_alloc *alloc,
1234					  struct list_lru *freelist)
1235{
1236	alloc->pid = current->group_leader->pid;
1237	alloc->mm = current->mm;
1238	mmgrab(alloc->mm);
1239	mutex_init(&alloc->mutex);
1240	INIT_LIST_HEAD(&alloc->buffers);
1241	alloc->freelist = freelist;
1242}
1243EXPORT_SYMBOL_IF_KUNIT(__binder_alloc_init);
1244
1245/**
1246 * binder_alloc_init() - called by binder_open() for per-proc initialization
1247 * @alloc: binder_alloc for this proc
1248 *
1249 * Called from binder_open() to initialize binder_alloc fields for
1250 * new binder proc
1251 */
1252void binder_alloc_init(struct binder_alloc *alloc)
1253{
1254	__binder_alloc_init(alloc, &binder_freelist);
1255}
1256
1257int binder_alloc_shrinker_init(void)
1258{
1259	int ret;
1260
1261	ret = list_lru_init(&binder_freelist);
1262	if (ret)
1263		return ret;
1264
1265	binder_shrinker = shrinker_alloc(0, "android-binder");
1266	if (!binder_shrinker) {
1267		list_lru_destroy(&binder_freelist);
1268		return -ENOMEM;
1269	}
1270
1271	binder_shrinker->count_objects = binder_shrink_count;
1272	binder_shrinker->scan_objects = binder_shrink_scan;
1273
1274	shrinker_register(binder_shrinker);
1275
1276	return 0;
1277}
1278
1279void binder_alloc_shrinker_exit(void)
1280{
1281	shrinker_free(binder_shrinker);
1282	list_lru_destroy(&binder_freelist);
1283}
1284
1285/**
1286 * check_buffer() - verify that buffer/offset is safe to access
1287 * @alloc: binder_alloc for this proc
1288 * @buffer: binder buffer to be accessed
1289 * @offset: offset into @buffer data
1290 * @bytes: bytes to access from offset
1291 *
1292 * Check that the @offset/@bytes are within the size of the given
1293 * @buffer and that the buffer is currently active and not freeable.
1294 * Offsets must also be multiples of sizeof(u32). The kernel is
1295 * allowed to touch the buffer in two cases:
1296 *
1297 * 1) when the buffer is being created:
1298 *     (buffer->free == 0 && buffer->allow_user_free == 0)
1299 * 2) when the buffer is being torn down:
1300 *     (buffer->free == 0 && buffer->transaction == NULL).
1301 *
1302 * Return: true if the buffer is safe to access
1303 */
1304static inline bool check_buffer(struct binder_alloc *alloc,
1305				struct binder_buffer *buffer,
1306				binder_size_t offset, size_t bytes)
1307{
1308	size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1309
1310	return buffer_size >= bytes &&
1311		offset <= buffer_size - bytes &&
1312		IS_ALIGNED(offset, sizeof(u32)) &&
1313		!buffer->free &&
1314		(!buffer->allow_user_free || !buffer->transaction);
1315}
1316
1317/**
1318 * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1319 * @alloc: binder_alloc for this proc
1320 * @buffer: binder buffer to be accessed
1321 * @buffer_offset: offset into @buffer data
1322 * @from: userspace pointer to source buffer
1323 * @bytes: bytes to copy
1324 *
1325 * Copy bytes from source userspace to target buffer.
1326 *
1327 * Return: bytes remaining to be copied
1328 */
1329unsigned long
1330binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1331				 struct binder_buffer *buffer,
1332				 binder_size_t buffer_offset,
1333				 const void __user *from,
1334				 size_t bytes)
1335{
1336	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1337		return bytes;
1338
1339	while (bytes) {
1340		unsigned long size;
1341		unsigned long ret;
1342		struct page *page;
1343		pgoff_t pgoff;
1344		void *kptr;
1345
1346		page = binder_alloc_get_page(alloc, buffer,
1347					     buffer_offset, &pgoff);
1348		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1349		kptr = kmap_local_page(page) + pgoff;
1350		ret = copy_from_user(kptr, from, size);
1351		kunmap_local(kptr);
1352		if (ret)
1353			return bytes - size + ret;
1354		bytes -= size;
1355		from += size;
1356		buffer_offset += size;
1357	}
1358	return 0;
1359}
1360
1361static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1362				       bool to_buffer,
1363				       struct binder_buffer *buffer,
1364				       binder_size_t buffer_offset,
1365				       void *ptr,
1366				       size_t bytes)
1367{
1368	/* All copies must be 32-bit aligned and 32-bit size */
1369	if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1370		return -EINVAL;
1371
1372	while (bytes) {
1373		unsigned long size;
1374		struct page *page;
1375		pgoff_t pgoff;
1376
1377		page = binder_alloc_get_page(alloc, buffer,
1378					     buffer_offset, &pgoff);
1379		size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1380		if (to_buffer)
1381			memcpy_to_page(page, pgoff, ptr, size);
1382		else
1383			memcpy_from_page(ptr, page, pgoff, size);
1384		bytes -= size;
1385		pgoff = 0;
1386		ptr = ptr + size;
1387		buffer_offset += size;
1388	}
1389	return 0;
1390}
1391
1392int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1393				struct binder_buffer *buffer,
1394				binder_size_t buffer_offset,
1395				void *src,
1396				size_t bytes)
1397{
1398	return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1399					   src, bytes);
1400}
1401
1402int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1403				  void *dest,
1404				  struct binder_buffer *buffer,
1405				  binder_size_t buffer_offset,
1406				  size_t bytes)
1407{
1408	return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1409					   dest, bytes);
1410}