drivers/android/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 "binder_alloc.h"
  27 #include "binder_trace.h"
  28
  29 struct list_lru binder_alloc_lru;
  30
  31 static DEFINE_MUTEX(binder_alloc_mmap_lock);
  32
  33 enum {
  34         BINDER_DEBUG_USER_ERROR             = 1U << 0,
  35         BINDER_DEBUG_OPEN_CLOSE             = 1U << 1,
  36         BINDER_DEBUG_BUFFER_ALLOC           = 1U << 2,
  37         BINDER_DEBUG_BUFFER_ALLOC_ASYNC     = 1U << 3,
  38 };
  39 static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR;
  40
  41 module_param_named(debug_mask, binder_alloc_debug_mask,
  42                    uint, 0644);
  43
  44 #define binder_alloc_debug(mask, x...) \
  45         do { \
  46                 if (binder_alloc_debug_mask & mask) \
  47                         pr_info_ratelimited(x); \
  48         } while (0)
  49
  50 static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
  51 {
  52         return list_entry(buffer->entry.next, struct binder_buffer, entry);
  53 }
  54
  55 static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
  56 {
  57         return list_entry(buffer->entry.prev, struct binder_buffer, entry);
  58 }
  59
  60 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
  61                                        struct binder_buffer *buffer)
  62 {
  63         if (list_is_last(&buffer->entry, &alloc->buffers))
  64                 return alloc->buffer + alloc->buffer_size - buffer->user_data;
  65         return binder_buffer_next(buffer)->user_data - buffer->user_data;
  66 }
  67
  68 static void binder_insert_free_buffer(struct binder_alloc *alloc,
  69                                       struct binder_buffer *new_buffer)
  70 {
  71         struct rb_node **p = &alloc->free_buffers.rb_node;
  72         struct rb_node *parent = NULL;
  73         struct binder_buffer *buffer;
  74         size_t buffer_size;
  75         size_t new_buffer_size;
  76
  77         BUG_ON(!new_buffer->free);
  78
  79         new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
  80
  81         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
  82                      "%d: add free buffer, size %zd, at %pK\n",
  83                       alloc->pid, new_buffer_size, new_buffer);
  84
  85         while (*p) {
  86                 parent = *p;
  87                 buffer = rb_entry(parent, struct binder_buffer, rb_node);
  88                 BUG_ON(!buffer->free);
  89
  90                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
  91
  92                 if (new_buffer_size < buffer_size)
  93                         p = &parent->rb_left;
  94                 else
  95                         p = &parent->rb_right;
  96         }
  97         rb_link_node(&new_buffer->rb_node, parent, p);
  98         rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers);
  99 }
 100
 101 static void binder_insert_allocated_buffer_locked(
 102                 struct binder_alloc *alloc, struct binder_buffer *new_buffer)
 103 {
 104         struct rb_node **p = &alloc->allocated_buffers.rb_node;
 105         struct rb_node *parent = NULL;
 106         struct binder_buffer *buffer;
 107
 108         BUG_ON(new_buffer->free);
 109
 110         while (*p) {
 111                 parent = *p;
 112                 buffer = rb_entry(parent, struct binder_buffer, rb_node);
 113                 BUG_ON(buffer->free);
 114
 115                 if (new_buffer->user_data < buffer->user_data)
 116                         p = &parent->rb_left;
 117                 else if (new_buffer->user_data > buffer->user_data)
 118                         p = &parent->rb_right;
 119                 else
 120                         BUG();
 121         }
 122         rb_link_node(&new_buffer->rb_node, parent, p);
 123         rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers);
 124 }
 125
 126 static struct binder_buffer *binder_alloc_prepare_to_free_locked(
 127                 struct binder_alloc *alloc,
 128                 uintptr_t user_ptr)
 129 {
 130         struct rb_node *n = alloc->allocated_buffers.rb_node;
 131         struct binder_buffer *buffer;
 132         void __user *uptr;
 133
 134         uptr = (void __user *)user_ptr;
 135
 136         while (n) {
 137                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 138                 BUG_ON(buffer->free);
 139
 140                 if (uptr < buffer->user_data)
 141                         n = n->rb_left;
 142                 else if (uptr > buffer->user_data)
 143                         n = n->rb_right;
 144                 else {
 145                         /*
 146                          * Guard against user threads attempting to
 147                          * free the buffer when in use by kernel or
 148                          * after it's already been freed.
 149                          */
 150                         if (!buffer->allow_user_free)
 151                                 return ERR_PTR(-EPERM);
 152                         buffer->allow_user_free = 0;
 153                         return buffer;
 154                 }
 155         }
 156         return NULL;
 157 }
 158
 159 /**
 160  * binder_alloc_prepare_to_free() - get buffer given user ptr
 161  * @alloc:      binder_alloc for this proc
 162  * @user_ptr:   User pointer to buffer data
 163  *
 164  * Validate userspace pointer to buffer data and return buffer corresponding to
 165  * that user pointer. Search the rb tree for buffer that matches user data
 166  * pointer.
 167  *
 168  * Return:      Pointer to buffer or NULL
 169  */
 170 struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
 171                                                    uintptr_t user_ptr)
 172 {
 173         struct binder_buffer *buffer;
 174
 175         mutex_lock(&alloc->mutex);
 176         buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
 177         mutex_unlock(&alloc->mutex);
 178         return buffer;
 179 }
 180
 181 static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 182                                     void __user *start, void __user *end)
 183 {
 184         void __user *page_addr;
 185         unsigned long user_page_addr;
 186         struct binder_lru_page *page;
 187         struct vm_area_struct *vma = NULL;
 188         struct mm_struct *mm = NULL;
 189         bool need_mm = false;
 190
 191         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 192                      "%d: %s pages %pK-%pK\n", alloc->pid,
 193                      allocate ? "allocate" : "free", start, end);
 194
 195         if (end <= start)
 196                 return 0;
 197
 198         trace_binder_update_page_range(alloc, allocate, start, end);
 199
 200         if (allocate == 0)
 201                 goto free_range;
 202
 203         for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 204                 page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
 205                 if (!page->page_ptr) {
 206                         need_mm = true;
 207                         break;
 208                 }
 209         }
 210
 211         if (need_mm && mmget_not_zero(alloc->mm))
 212                 mm = alloc->mm;
 213
 214         if (mm) {
 215                 mmap_read_lock(mm);
 216                 vma = vma_lookup(mm, alloc->vma_addr);
 217         }
 218
 219         if (!vma && need_mm) {
 220                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 221                                    "%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
 222                                    alloc->pid);
 223                 goto err_no_vma;
 224         }
 225
 226         for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 227                 int ret;
 228                 bool on_lru;
 229                 size_t index;
 230
 231                 index = (page_addr - alloc->buffer) / PAGE_SIZE;
 232                 page = &alloc->pages[index];
 233
 234                 if (page->page_ptr) {
 235                         trace_binder_alloc_lru_start(alloc, index);
 236
 237                         on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
 238                         WARN_ON(!on_lru);
 239
 240                         trace_binder_alloc_lru_end(alloc, index);
 241                         continue;
 242                 }
 243
 244                 if (WARN_ON(!vma))
 245                         goto err_page_ptr_cleared;
 246
 247                 trace_binder_alloc_page_start(alloc, index);
 248                 page->page_ptr = alloc_page(GFP_KERNEL |
 249                                             __GFP_HIGHMEM |
 250                                             __GFP_ZERO);
 251                 if (!page->page_ptr) {
 252                         pr_err("%d: binder_alloc_buf failed for page at %pK\n",
 253                                 alloc->pid, page_addr);
 254                         goto err_alloc_page_failed;
 255                 }
 256                 page->alloc = alloc;
 257                 INIT_LIST_HEAD(&page->lru);
 258
 259                 user_page_addr = (uintptr_t)page_addr;
 260                 ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
 261                 if (ret) {
 262                         pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
 263                                alloc->pid, user_page_addr);
 264                         goto err_vm_insert_page_failed;
 265                 }
 266
 267                 if (index + 1 > alloc->pages_high)
 268                         alloc->pages_high = index + 1;
 269
 270                 trace_binder_alloc_page_end(alloc, index);
 271         }
 272         if (mm) {
 273                 mmap_read_unlock(mm);
 274                 mmput(mm);
 275         }
 276         return 0;
 277
 278 free_range:
 279         for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) {
 280                 bool ret;
 281                 size_t index;
 282
 283                 index = (page_addr - alloc->buffer) / PAGE_SIZE;
 284                 page = &alloc->pages[index];
 285
 286                 trace_binder_free_lru_start(alloc, index);
 287
 288                 ret = list_lru_add(&binder_alloc_lru, &page->lru);
 289                 WARN_ON(!ret);
 290
 291                 trace_binder_free_lru_end(alloc, index);
 292                 if (page_addr == start)
 293                         break;
 294                 continue;
 295
 296 err_vm_insert_page_failed:
 297                 __free_page(page->page_ptr);
 298                 page->page_ptr = NULL;
 299 err_alloc_page_failed:
 300 err_page_ptr_cleared:
 301                 if (page_addr == start)
 302                         break;
 303         }
 304 err_no_vma:
 305         if (mm) {
 306                 mmap_read_unlock(mm);
 307                 mmput(mm);
 308         }
 309         return vma ? -ENOMEM : -ESRCH;
 310 }
 311
 312 static inline struct vm_area_struct *binder_alloc_get_vma(
 313                 struct binder_alloc *alloc)
 314 {
 315         struct vm_area_struct *vma = NULL;
 316
 317         if (alloc->vma_addr)
 318                 vma = vma_lookup(alloc->mm, alloc->vma_addr);
 319
 320         return vma;
 321 }
 322
 323 static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
 324 {
 325         /*
 326          * Find the amount and size of buffers allocated by the current caller;
 327          * The idea is that once we cross the threshold, whoever is responsible
 328          * for the low async space is likely to try to send another async txn,
 329          * and at some point we'll catch them in the act. This is more efficient
 330          * than keeping a map per pid.
 331          */
 332         struct rb_node *n;
 333         struct binder_buffer *buffer;
 334         size_t total_alloc_size = 0;
 335         size_t num_buffers = 0;
 336
 337         for (n = rb_first(&alloc->allocated_buffers); n != NULL;
 338                  n = rb_next(n)) {
 339                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 340                 if (buffer->pid != pid)
 341                         continue;
 342                 if (!buffer->async_transaction)
 343                         continue;
 344                 total_alloc_size += binder_alloc_buffer_size(alloc, buffer)
 345                         + sizeof(struct binder_buffer);
 346                 num_buffers++;
 347         }
 348
 349         /*
 350          * Warn if this pid has more than 50 transactions, or more than 50% of
 351          * async space (which is 25% of total buffer size). Oneway spam is only
 352          * detected when the threshold is exceeded.
 353          */
 354         if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
 355                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 356                              "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
 357                               alloc->pid, pid, num_buffers, total_alloc_size);
 358                 if (!alloc->oneway_spam_detected) {
 359                         alloc->oneway_spam_detected = true;
 360                         return true;
 361                 }
 362         }
 363         return false;
 364 }
 365
 366 static struct binder_buffer *binder_alloc_new_buf_locked(
 367                                 struct binder_alloc *alloc,
 368                                 size_t data_size,
 369                                 size_t offsets_size,
 370                                 size_t extra_buffers_size,
 371                                 int is_async,
 372                                 int pid)
 373 {
 374         struct rb_node *n = alloc->free_buffers.rb_node;
 375         struct binder_buffer *buffer;
 376         size_t buffer_size;
 377         struct rb_node *best_fit = NULL;
 378         void __user *has_page_addr;
 379         void __user *end_page_addr;
 380         size_t size, data_offsets_size;
 381         int ret;
 382
 383         mmap_read_lock(alloc->mm);
 384         if (!binder_alloc_get_vma(alloc)) {
 385                 mmap_read_unlock(alloc->mm);
 386                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 387                                    "%d: binder_alloc_buf, no vma\n",
 388                                    alloc->pid);
 389                 return ERR_PTR(-ESRCH);
 390         }
 391         mmap_read_unlock(alloc->mm);
 392
 393         data_offsets_size = ALIGN(data_size, sizeof(void *)) +
 394                 ALIGN(offsets_size, sizeof(void *));
 395
 396         if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
 397                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 398                                 "%d: got transaction with invalid size %zd-%zd\n",
 399                                 alloc->pid, data_size, offsets_size);
 400                 return ERR_PTR(-EINVAL);
 401         }
 402         size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
 403         if (size < data_offsets_size || size < extra_buffers_size) {
 404                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 405                                 "%d: got transaction with invalid extra_buffers_size %zd\n",
 406                                 alloc->pid, extra_buffers_size);
 407                 return ERR_PTR(-EINVAL);
 408         }
 409         if (is_async &&
 410             alloc->free_async_space < size + sizeof(struct binder_buffer)) {
 411                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 412                              "%d: binder_alloc_buf size %zd failed, no async space left\n",
 413                               alloc->pid, size);
 414                 return ERR_PTR(-ENOSPC);
 415         }
 416
 417         /* Pad 0-size buffers so they get assigned unique addresses */
 418         size = max(size, sizeof(void *));
 419
 420         while (n) {
 421                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 422                 BUG_ON(!buffer->free);
 423                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
 424
 425                 if (size < buffer_size) {
 426                         best_fit = n;
 427                         n = n->rb_left;
 428                 } else if (size > buffer_size)
 429                         n = n->rb_right;
 430                 else {
 431                         best_fit = n;
 432                         break;
 433                 }
 434         }
 435         if (best_fit == NULL) {
 436                 size_t allocated_buffers = 0;
 437                 size_t largest_alloc_size = 0;
 438                 size_t total_alloc_size = 0;
 439                 size_t free_buffers = 0;
 440                 size_t largest_free_size = 0;
 441                 size_t total_free_size = 0;
 442
 443                 for (n = rb_first(&alloc->allocated_buffers); n != NULL;
 444                      n = rb_next(n)) {
 445                         buffer = rb_entry(n, struct binder_buffer, rb_node);
 446                         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 447                         allocated_buffers++;
 448                         total_alloc_size += buffer_size;
 449                         if (buffer_size > largest_alloc_size)
 450                                 largest_alloc_size = buffer_size;
 451                 }
 452                 for (n = rb_first(&alloc->free_buffers); n != NULL;
 453                      n = rb_next(n)) {
 454                         buffer = rb_entry(n, struct binder_buffer, rb_node);
 455                         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 456                         free_buffers++;
 457                         total_free_size += buffer_size;
 458                         if (buffer_size > largest_free_size)
 459                                 largest_free_size = buffer_size;
 460                 }
 461                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 462                                    "%d: binder_alloc_buf size %zd failed, no address space\n",
 463                                    alloc->pid, size);
 464                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 465                                    "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
 466                                    total_alloc_size, allocated_buffers,
 467                                    largest_alloc_size, total_free_size,
 468                                    free_buffers, largest_free_size);
 469                 return ERR_PTR(-ENOSPC);
 470         }
 471         if (n == NULL) {
 472                 buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
 473                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
 474         }
 475
 476         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 477                      "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
 478                       alloc->pid, size, buffer, buffer_size);
 479
 480         has_page_addr = (void __user *)
 481                 (((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
 482         WARN_ON(n && buffer_size != size);
 483         end_page_addr =
 484                 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
 485         if (end_page_addr > has_page_addr)
 486                 end_page_addr = has_page_addr;
 487         ret = binder_update_page_range(alloc, 1, (void __user *)
 488                 PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr);
 489         if (ret)
 490                 return ERR_PTR(ret);
 491
 492         if (buffer_size != size) {
 493                 struct binder_buffer *new_buffer;
 494
 495                 new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 496                 if (!new_buffer) {
 497                         pr_err("%s: %d failed to alloc new buffer struct\n",
 498                                __func__, alloc->pid);
 499                         goto err_alloc_buf_struct_failed;
 500                 }
 501                 new_buffer->user_data = (u8 __user *)buffer->user_data + size;
 502                 list_add(&new_buffer->entry, &buffer->entry);
 503                 new_buffer->free = 1;
 504                 binder_insert_free_buffer(alloc, new_buffer);
 505         }
 506
 507         rb_erase(best_fit, &alloc->free_buffers);
 508         buffer->free = 0;
 509         buffer->allow_user_free = 0;
 510         binder_insert_allocated_buffer_locked(alloc, buffer);
 511         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 512                      "%d: binder_alloc_buf size %zd got %pK\n",
 513                       alloc->pid, size, buffer);
 514         buffer->data_size = data_size;
 515         buffer->offsets_size = offsets_size;
 516         buffer->async_transaction = is_async;
 517         buffer->extra_buffers_size = extra_buffers_size;
 518         buffer->pid = pid;
 519         buffer->oneway_spam_suspect = false;
 520         if (is_async) {
 521                 alloc->free_async_space -= size + sizeof(struct binder_buffer);
 522                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 523                              "%d: binder_alloc_buf size %zd async free %zd\n",
 524                               alloc->pid, size, alloc->free_async_space);
 525                 if (alloc->free_async_space < alloc->buffer_size / 10) {
 526                         /*
 527                          * Start detecting spammers once we have less than 20%
 528                          * of async space left (which is less than 10% of total
 529                          * buffer size).
 530                          */
 531                         buffer->oneway_spam_suspect = debug_low_async_space_locked(alloc, pid);
 532                 } else {
 533                         alloc->oneway_spam_detected = false;
 534                 }
 535         }
 536         return buffer;
 537
 538 err_alloc_buf_struct_failed:
 539         binder_update_page_range(alloc, 0, (void __user *)
 540                                  PAGE_ALIGN((uintptr_t)buffer->user_data),
 541                                  end_page_addr);
 542         return ERR_PTR(-ENOMEM);
 543 }
 544
 545 /**
 546  * binder_alloc_new_buf() - Allocate a new binder buffer
 547  * @alloc:              binder_alloc for this proc
 548  * @data_size:          size of user data buffer
 549  * @offsets_size:       user specified buffer offset
 550  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
 551  * @is_async:           buffer for async transaction
 552  * @pid:                                pid to attribute allocation to (used for debugging)
 553  *
 554  * Allocate a new buffer given the requested sizes. Returns
 555  * the kernel version of the buffer pointer. The size allocated
 556  * is the sum of the three given sizes (each rounded up to
 557  * pointer-sized boundary)
 558  *
 559  * Return:      The allocated buffer or %NULL if error
 560  */
 561 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 562                                            size_t data_size,
 563                                            size_t offsets_size,
 564                                            size_t extra_buffers_size,
 565                                            int is_async,
 566                                            int pid)
 567 {
 568         struct binder_buffer *buffer;
 569
 570         mutex_lock(&alloc->mutex);
 571         buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
 572                                              extra_buffers_size, is_async, pid);
 573         mutex_unlock(&alloc->mutex);
 574         return buffer;
 575 }
 576
 577 static void __user *buffer_start_page(struct binder_buffer *buffer)
 578 {
 579         return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
 580 }
 581
 582 static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
 583 {
 584         return (void __user *)
 585                 (((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
 586 }
 587
 588 static void binder_delete_free_buffer(struct binder_alloc *alloc,
 589                                       struct binder_buffer *buffer)
 590 {
 591         struct binder_buffer *prev, *next = NULL;
 592         bool to_free = true;
 593
 594         BUG_ON(alloc->buffers.next == &buffer->entry);
 595         prev = binder_buffer_prev(buffer);
 596         BUG_ON(!prev->free);
 597         if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
 598                 to_free = false;
 599                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 600                                    "%d: merge free, buffer %pK share page with %pK\n",
 601                                    alloc->pid, buffer->user_data,
 602                                    prev->user_data);
 603         }
 604
 605         if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 606                 next = binder_buffer_next(buffer);
 607                 if (buffer_start_page(next) == buffer_start_page(buffer)) {
 608                         to_free = false;
 609                         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 610                                            "%d: merge free, buffer %pK share page with %pK\n",
 611                                            alloc->pid,
 612                                            buffer->user_data,
 613                                            next->user_data);
 614                 }
 615         }
 616
 617         if (PAGE_ALIGNED(buffer->user_data)) {
 618                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 619                                    "%d: merge free, buffer start %pK is page aligned\n",
 620                                    alloc->pid, buffer->user_data);
 621                 to_free = false;
 622         }
 623
 624         if (to_free) {
 625                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 626                                    "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
 627                                    alloc->pid, buffer->user_data,
 628                                    prev->user_data,
 629                                    next ? next->user_data : NULL);
 630                 binder_update_page_range(alloc, 0, buffer_start_page(buffer),
 631                                          buffer_start_page(buffer) + PAGE_SIZE);
 632         }
 633         list_del(&buffer->entry);
 634         kfree(buffer);
 635 }
 636
 637 static void binder_free_buf_locked(struct binder_alloc *alloc,
 638                                    struct binder_buffer *buffer)
 639 {
 640         size_t size, buffer_size;
 641
 642         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 643
 644         size = ALIGN(buffer->data_size, sizeof(void *)) +
 645                 ALIGN(buffer->offsets_size, sizeof(void *)) +
 646                 ALIGN(buffer->extra_buffers_size, sizeof(void *));
 647
 648         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 649                      "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
 650                       alloc->pid, buffer, size, buffer_size);
 651
 652         BUG_ON(buffer->free);
 653         BUG_ON(size > buffer_size);
 654         BUG_ON(buffer->transaction != NULL);
 655         BUG_ON(buffer->user_data < alloc->buffer);
 656         BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
 657
 658         if (buffer->async_transaction) {
 659                 alloc->free_async_space += buffer_size + sizeof(struct binder_buffer);
 660
 661                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 662                              "%d: binder_free_buf size %zd async free %zd\n",
 663                               alloc->pid, size, alloc->free_async_space);
 664         }
 665
 666         binder_update_page_range(alloc, 0,
 667                 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
 668                 (void __user *)(((uintptr_t)
 669                           buffer->user_data + buffer_size) & PAGE_MASK));
 670
 671         rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
 672         buffer->free = 1;
 673         if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 674                 struct binder_buffer *next = binder_buffer_next(buffer);
 675
 676                 if (next->free) {
 677                         rb_erase(&next->rb_node, &alloc->free_buffers);
 678                         binder_delete_free_buffer(alloc, next);
 679                 }
 680         }
 681         if (alloc->buffers.next != &buffer->entry) {
 682                 struct binder_buffer *prev = binder_buffer_prev(buffer);
 683
 684                 if (prev->free) {
 685                         binder_delete_free_buffer(alloc, buffer);
 686                         rb_erase(&prev->rb_node, &alloc->free_buffers);
 687                         buffer = prev;
 688                 }
 689         }
 690         binder_insert_free_buffer(alloc, buffer);
 691 }
 692
 693 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
 694                                    struct binder_buffer *buffer);
 695 /**
 696  * binder_alloc_free_buf() - free a binder buffer
 697  * @alloc:      binder_alloc for this proc
 698  * @buffer:     kernel pointer to buffer
 699  *
 700  * Free the buffer allocated via binder_alloc_new_buf()
 701  */
 702 void binder_alloc_free_buf(struct binder_alloc *alloc,
 703                             struct binder_buffer *buffer)
 704 {
 705         /*
 706          * We could eliminate the call to binder_alloc_clear_buf()
 707          * from binder_alloc_deferred_release() by moving this to
 708          * binder_alloc_free_buf_locked(). However, that could
 709          * increase contention for the alloc mutex if clear_on_free
 710          * is used frequently for large buffers. The mutex is not
 711          * needed for correctness here.
 712          */
 713         if (buffer->clear_on_free) {
 714                 binder_alloc_clear_buf(alloc, buffer);
 715                 buffer->clear_on_free = false;
 716         }
 717         mutex_lock(&alloc->mutex);
 718         binder_free_buf_locked(alloc, buffer);
 719         mutex_unlock(&alloc->mutex);
 720 }
 721
 722 /**
 723  * binder_alloc_mmap_handler() - map virtual address space for proc
 724  * @alloc:      alloc structure for this proc
 725  * @vma:        vma passed to mmap()
 726  *
 727  * Called by binder_mmap() to initialize the space specified in
 728  * vma for allocating binder buffers
 729  *
 730  * Return:
 731  *      0 = success
 732  *      -EBUSY = address space already mapped
 733  *      -ENOMEM = failed to map memory to given address space
 734  */
 735 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 736                               struct vm_area_struct *vma)
 737 {
 738         int ret;
 739         const char *failure_string;
 740         struct binder_buffer *buffer;
 741
 742         if (unlikely(vma->vm_mm != alloc->mm)) {
 743                 ret = -EINVAL;
 744                 failure_string = "invalid vma->vm_mm";
 745                 goto err_invalid_mm;
 746         }
 747
 748         mutex_lock(&binder_alloc_mmap_lock);
 749         if (alloc->buffer_size) {
 750                 ret = -EBUSY;
 751                 failure_string = "already mapped";
 752                 goto err_already_mapped;
 753         }
 754         alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
 755                                    SZ_4M);
 756         mutex_unlock(&binder_alloc_mmap_lock);
 757
 758         alloc->buffer = (void __user *)vma->vm_start;
 759
 760         alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
 761                                sizeof(alloc->pages[0]),
 762                                GFP_KERNEL);
 763         if (alloc->pages == NULL) {
 764                 ret = -ENOMEM;
 765                 failure_string = "alloc page array";
 766                 goto err_alloc_pages_failed;
 767         }
 768
 769         buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 770         if (!buffer) {
 771                 ret = -ENOMEM;
 772                 failure_string = "alloc buffer struct";
 773                 goto err_alloc_buf_struct_failed;
 774         }
 775
 776         buffer->user_data = alloc->buffer;
 777         list_add(&buffer->entry, &alloc->buffers);
 778         buffer->free = 1;
 779         binder_insert_free_buffer(alloc, buffer);
 780         alloc->free_async_space = alloc->buffer_size / 2;
 781         alloc->vma_addr = vma->vm_start;
 782
 783         return 0;
 784
 785 err_alloc_buf_struct_failed:
 786         kfree(alloc->pages);
 787         alloc->pages = NULL;
 788 err_alloc_pages_failed:
 789         alloc->buffer = NULL;
 790         mutex_lock(&binder_alloc_mmap_lock);
 791         alloc->buffer_size = 0;
 792 err_already_mapped:
 793         mutex_unlock(&binder_alloc_mmap_lock);
 794 err_invalid_mm:
 795         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 796                            "%s: %d %lx-%lx %s failed %d\n", __func__,
 797                            alloc->pid, vma->vm_start, vma->vm_end,
 798                            failure_string, ret);
 799         return ret;
 800 }
 801
 802
 803 void binder_alloc_deferred_release(struct binder_alloc *alloc)
 804 {
 805         struct rb_node *n;
 806         int buffers, page_count;
 807         struct binder_buffer *buffer;
 808
 809         buffers = 0;
 810         mutex_lock(&alloc->mutex);
 811         BUG_ON(alloc->vma_addr &&
 812                vma_lookup(alloc->mm, alloc->vma_addr));
 813
 814         while ((n = rb_first(&alloc->allocated_buffers))) {
 815                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 816
 817                 /* Transaction should already have been freed */
 818                 BUG_ON(buffer->transaction);
 819
 820                 if (buffer->clear_on_free) {
 821                         binder_alloc_clear_buf(alloc, buffer);
 822                         buffer->clear_on_free = false;
 823                 }
 824                 binder_free_buf_locked(alloc, buffer);
 825                 buffers++;
 826         }
 827
 828         while (!list_empty(&alloc->buffers)) {
 829                 buffer = list_first_entry(&alloc->buffers,
 830                                           struct binder_buffer, entry);
 831                 WARN_ON(!buffer->free);
 832
 833                 list_del(&buffer->entry);
 834                 WARN_ON_ONCE(!list_empty(&alloc->buffers));
 835                 kfree(buffer);
 836         }
 837
 838         page_count = 0;
 839         if (alloc->pages) {
 840                 int i;
 841
 842                 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 843                         void __user *page_addr;
 844                         bool on_lru;
 845
 846                         if (!alloc->pages[i].page_ptr)
 847                                 continue;
 848
 849                         on_lru = list_lru_del(&binder_alloc_lru,
 850                                               &alloc->pages[i].lru);
 851                         page_addr = alloc->buffer + i * PAGE_SIZE;
 852                         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 853                                      "%s: %d: page %d at %pK %s\n",
 854                                      __func__, alloc->pid, i, page_addr,
 855                                      on_lru ? "on lru" : "active");
 856                         __free_page(alloc->pages[i].page_ptr);
 857                         page_count++;
 858                 }
 859                 kfree(alloc->pages);
 860         }
 861         mutex_unlock(&alloc->mutex);
 862         if (alloc->mm)
 863                 mmdrop(alloc->mm);
 864
 865         binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
 866                      "%s: %d buffers %d, pages %d\n",
 867                      __func__, alloc->pid, buffers, page_count);
 868 }
 869
 870 static void print_binder_buffer(struct seq_file *m, const char *prefix,
 871                                 struct binder_buffer *buffer)
 872 {
 873         seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
 874                    prefix, buffer->debug_id, buffer->user_data,
 875                    buffer->data_size, buffer->offsets_size,
 876                    buffer->extra_buffers_size,
 877                    buffer->transaction ? "active" : "delivered");
 878 }
 879
 880 /**
 881  * binder_alloc_print_allocated() - print buffer info
 882  * @m:     seq_file for output via seq_printf()
 883  * @alloc: binder_alloc for this proc
 884  *
 885  * Prints information about every buffer associated with
 886  * the binder_alloc state to the given seq_file
 887  */
 888 void binder_alloc_print_allocated(struct seq_file *m,
 889                                   struct binder_alloc *alloc)
 890 {
 891         struct rb_node *n;
 892
 893         mutex_lock(&alloc->mutex);
 894         for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 895                 print_binder_buffer(m, "  buffer",
 896                                     rb_entry(n, struct binder_buffer, rb_node));
 897         mutex_unlock(&alloc->mutex);
 898 }
 899
 900 /**
 901  * binder_alloc_print_pages() - print page usage
 902  * @m:     seq_file for output via seq_printf()
 903  * @alloc: binder_alloc for this proc
 904  */
 905 void binder_alloc_print_pages(struct seq_file *m,
 906                               struct binder_alloc *alloc)
 907 {
 908         struct binder_lru_page *page;
 909         int i;
 910         int active = 0;
 911         int lru = 0;
 912         int free = 0;
 913
 914         mutex_lock(&alloc->mutex);
 915         /*
 916          * Make sure the binder_alloc is fully initialized, otherwise we might
 917          * read inconsistent state.
 918          */
 919
 920         mmap_read_lock(alloc->mm);
 921         if (binder_alloc_get_vma(alloc) == NULL) {
 922                 mmap_read_unlock(alloc->mm);
 923                 goto uninitialized;
 924         }
 925
 926         mmap_read_unlock(alloc->mm);
 927         for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 928                 page = &alloc->pages[i];
 929                 if (!page->page_ptr)
 930                         free++;
 931                 else if (list_empty(&page->lru))
 932                         active++;
 933                 else
 934                         lru++;
 935         }
 936
 937 uninitialized:
 938         mutex_unlock(&alloc->mutex);
 939         seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
 940         seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
 941 }
 942
 943 /**
 944  * binder_alloc_get_allocated_count() - return count of buffers
 945  * @alloc: binder_alloc for this proc
 946  *
 947  * Return: count of allocated buffers
 948  */
 949 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
 950 {
 951         struct rb_node *n;
 952         int count = 0;
 953
 954         mutex_lock(&alloc->mutex);
 955         for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 956                 count++;
 957         mutex_unlock(&alloc->mutex);
 958         return count;
 959 }
 960
 961
 962 /**
 963  * binder_alloc_vma_close() - invalidate address space
 964  * @alloc: binder_alloc for this proc
 965  *
 966  * Called from binder_vma_close() when releasing address space.
 967  * Clears alloc->vma to prevent new incoming transactions from
 968  * allocating more buffers.
 969  */
 970 void binder_alloc_vma_close(struct binder_alloc *alloc)
 971 {
 972         alloc->vma_addr = 0;
 973 }
 974
 975 /**
 976  * binder_alloc_free_page() - shrinker callback to free pages
 977  * @item:   item to free
 978  * @lock:   lock protecting the item
 979  * @cb_arg: callback argument
 980  *
 981  * Called from list_lru_walk() in binder_shrink_scan() to free
 982  * up pages when the system is under memory pressure.
 983  */
 984 enum lru_status binder_alloc_free_page(struct list_head *item,
 985                                        struct list_lru_one *lru,
 986                                        spinlock_t *lock,
 987                                        void *cb_arg)
 988         __must_hold(lock)
 989 {
 990         struct mm_struct *mm = NULL;
 991         struct binder_lru_page *page = container_of(item,
 992                                                     struct binder_lru_page,
 993                                                     lru);
 994         struct binder_alloc *alloc;
 995         uintptr_t page_addr;
 996         size_t index;
 997         struct vm_area_struct *vma;
 998
 999         alloc = page->alloc;
1000         if (!mutex_trylock(&alloc->mutex))
1001                 goto err_get_alloc_mutex_failed;
1002
1003         if (!page->page_ptr)
1004                 goto err_page_already_freed;
1005
1006         index = page - alloc->pages;
1007         page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
1008
1009         mm = alloc->mm;
1010         if (!mmget_not_zero(mm))
1011                 goto err_mmget;
1012         if (!mmap_read_trylock(mm))
1013                 goto err_mmap_read_lock_failed;
1014         vma = binder_alloc_get_vma(alloc);
1015
1016         list_lru_isolate(lru, item);
1017         spin_unlock(lock);
1018
1019         if (vma) {
1020                 trace_binder_unmap_user_start(alloc, index);
1021
1022                 zap_page_range(vma, page_addr, PAGE_SIZE);
1023
1024                 trace_binder_unmap_user_end(alloc, index);
1025         }
1026         mmap_read_unlock(mm);
1027         mmput_async(mm);
1028
1029         trace_binder_unmap_kernel_start(alloc, index);
1030
1031         __free_page(page->page_ptr);
1032         page->page_ptr = NULL;
1033
1034         trace_binder_unmap_kernel_end(alloc, index);
1035
1036         spin_lock(lock);
1037         mutex_unlock(&alloc->mutex);
1038         return LRU_REMOVED_RETRY;
1039
1040 err_mmap_read_lock_failed:
1041         mmput_async(mm);
1042 err_mmget:
1043 err_page_already_freed:
1044         mutex_unlock(&alloc->mutex);
1045 err_get_alloc_mutex_failed:
1046         return LRU_SKIP;
1047 }
1048
1049 static unsigned long
1050 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1051 {
1052         return list_lru_count(&binder_alloc_lru);
1053 }
1054
1055 static unsigned long
1056 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1057 {
1058         return list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
1059                             NULL, sc->nr_to_scan);
1060 }
1061
1062 static struct shrinker binder_shrinker = {
1063         .count_objects = binder_shrink_count,
1064         .scan_objects = binder_shrink_scan,
1065         .seeks = DEFAULT_SEEKS,
1066 };
1067
1068 /**
1069  * binder_alloc_init() - called by binder_open() for per-proc initialization
1070  * @alloc: binder_alloc for this proc
1071  *
1072  * Called from binder_open() to initialize binder_alloc fields for
1073  * new binder proc
1074  */
1075 void binder_alloc_init(struct binder_alloc *alloc)
1076 {
1077         alloc->pid = current->group_leader->pid;
1078         alloc->mm = current->mm;
1079         mmgrab(alloc->mm);
1080         mutex_init(&alloc->mutex);
1081         INIT_LIST_HEAD(&alloc->buffers);
1082 }
1083
1084 int binder_alloc_shrinker_init(void)
1085 {
1086         int ret = list_lru_init(&binder_alloc_lru);
1087
1088         if (ret == 0) {
1089                 ret = register_shrinker(&binder_shrinker, "android-binder");
1090                 if (ret)
1091                         list_lru_destroy(&binder_alloc_lru);
1092         }
1093         return ret;
1094 }
1095
1096 /**
1097  * check_buffer() - verify that buffer/offset is safe to access
1098  * @alloc: binder_alloc for this proc
1099  * @buffer: binder buffer to be accessed
1100  * @offset: offset into @buffer data
1101  * @bytes: bytes to access from offset
1102  *
1103  * Check that the @offset/@bytes are within the size of the given
1104  * @buffer and that the buffer is currently active and not freeable.
1105  * Offsets must also be multiples of sizeof(u32). The kernel is
1106  * allowed to touch the buffer in two cases:
1107  *
1108  * 1) when the buffer is being created:
1109  *     (buffer->free == 0 && buffer->allow_user_free == 0)
1110  * 2) when the buffer is being torn down:
1111  *     (buffer->free == 0 && buffer->transaction == NULL).
1112  *
1113  * Return: true if the buffer is safe to access
1114  */
1115 static inline bool check_buffer(struct binder_alloc *alloc,
1116                                 struct binder_buffer *buffer,
1117                                 binder_size_t offset, size_t bytes)
1118 {
1119         size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1120
1121         return buffer_size >= bytes &&
1122                 offset <= buffer_size - bytes &&
1123                 IS_ALIGNED(offset, sizeof(u32)) &&
1124                 !buffer->free &&
1125                 (!buffer->allow_user_free || !buffer->transaction);
1126 }
1127
1128 /**
1129  * binder_alloc_get_page() - get kernel pointer for given buffer offset
1130  * @alloc: binder_alloc for this proc
1131  * @buffer: binder buffer to be accessed
1132  * @buffer_offset: offset into @buffer data
1133  * @pgoffp: address to copy final page offset to
1134  *
1135  * Lookup the struct page corresponding to the address
1136  * at @buffer_offset into @buffer->user_data. If @pgoffp is not
1137  * NULL, the byte-offset into the page is written there.
1138  *
1139  * The caller is responsible to ensure that the offset points
1140  * to a valid address within the @buffer and that @buffer is
1141  * not freeable by the user. Since it can't be freed, we are
1142  * guaranteed that the corresponding elements of @alloc->pages[]
1143  * cannot change.
1144  *
1145  * Return: struct page
1146  */
1147 static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
1148                                           struct binder_buffer *buffer,
1149                                           binder_size_t buffer_offset,
1150                                           pgoff_t *pgoffp)
1151 {
1152         binder_size_t buffer_space_offset = buffer_offset +
1153                 (buffer->user_data - alloc->buffer);
1154         pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
1155         size_t index = buffer_space_offset >> PAGE_SHIFT;
1156         struct binder_lru_page *lru_page;
1157
1158         lru_page = &alloc->pages[index];
1159         *pgoffp = pgoff;
1160         return lru_page->page_ptr;
1161 }
1162
1163 /**
1164  * binder_alloc_clear_buf() - zero out buffer
1165  * @alloc: binder_alloc for this proc
1166  * @buffer: binder buffer to be cleared
1167  *
1168  * memset the given buffer to 0
1169  */
1170 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
1171                                    struct binder_buffer *buffer)
1172 {
1173         size_t bytes = binder_alloc_buffer_size(alloc, buffer);
1174         binder_size_t buffer_offset = 0;
1175
1176         while (bytes) {
1177                 unsigned long size;
1178                 struct page *page;
1179                 pgoff_t pgoff;
1180
1181                 page = binder_alloc_get_page(alloc, buffer,
1182                                              buffer_offset, &pgoff);
1183                 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1184                 memset_page(page, pgoff, 0, size);
1185                 bytes -= size;
1186                 buffer_offset += size;
1187         }
1188 }
1189
1190 /**
1191  * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1192  * @alloc: binder_alloc for this proc
1193  * @buffer: binder buffer to be accessed
1194  * @buffer_offset: offset into @buffer data
1195  * @from: userspace pointer to source buffer
1196  * @bytes: bytes to copy
1197  *
1198  * Copy bytes from source userspace to target buffer.
1199  *
1200  * Return: bytes remaining to be copied
1201  */
1202 unsigned long
1203 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1204                                  struct binder_buffer *buffer,
1205                                  binder_size_t buffer_offset,
1206                                  const void __user *from,
1207                                  size_t bytes)
1208 {
1209         if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1210                 return bytes;
1211
1212         while (bytes) {
1213                 unsigned long size;
1214                 unsigned long ret;
1215                 struct page *page;
1216                 pgoff_t pgoff;
1217                 void *kptr;
1218
1219                 page = binder_alloc_get_page(alloc, buffer,
1220                                              buffer_offset, &pgoff);
1221                 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1222                 kptr = kmap_local_page(page) + pgoff;
1223                 ret = copy_from_user(kptr, from, size);
1224                 kunmap_local(kptr);
1225                 if (ret)
1226                         return bytes - size + ret;
1227                 bytes -= size;
1228                 from += size;
1229                 buffer_offset += size;
1230         }
1231         return 0;
1232 }
1233
1234 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1235                                        bool to_buffer,
1236                                        struct binder_buffer *buffer,
1237                                        binder_size_t buffer_offset,
1238                                        void *ptr,
1239                                        size_t bytes)
1240 {
1241         /* All copies must be 32-bit aligned and 32-bit size */
1242         if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1243                 return -EINVAL;
1244
1245         while (bytes) {
1246                 unsigned long size;
1247                 struct page *page;
1248                 pgoff_t pgoff;
1249
1250                 page = binder_alloc_get_page(alloc, buffer,
1251                                              buffer_offset, &pgoff);
1252                 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1253                 if (to_buffer)
1254                         memcpy_to_page(page, pgoff, ptr, size);
1255                 else
1256                         memcpy_from_page(ptr, page, pgoff, size);
1257                 bytes -= size;
1258                 pgoff = 0;
1259                 ptr = ptr + size;
1260                 buffer_offset += size;
1261         }
1262         return 0;
1263 }
1264
1265 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1266                                 struct binder_buffer *buffer,
1267                                 binder_size_t buffer_offset,
1268                                 void *src,
1269                                 size_t bytes)
1270 {
1271         return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1272                                            src, bytes);
1273 }
1274
1275 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1276                                   void *dest,
1277                                   struct binder_buffer *buffer,
1278                                   binder_size_t buffer_offset,
1279                                   size_t bytes)
1280 {
1281         return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1282                                            dest, bytes);
1283 }
1284