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->vma_vm_mm))
 212                 mm = alloc->vma_vm_mm;
 213
 214         if (mm) {
 215                 mmap_write_lock(mm);
 216                 vma = alloc->vma;
 217         }
 218
 219         if (!vma && need_mm) {
 220                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 221                                    "%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
 222                                    alloc->pid);
 223                 goto err_no_vma;
 224         }
 225
 226         for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 227                 int ret;
 228                 bool on_lru;
 229                 size_t index;
 230
 231                 index = (page_addr - alloc->buffer) / PAGE_SIZE;
 232                 page = &alloc->pages[index];
 233
 234                 if (page->page_ptr) {
 235                         trace_binder_alloc_lru_start(alloc, index);
 236
 237                         on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
 238                         WARN_ON(!on_lru);
 239
 240                         trace_binder_alloc_lru_end(alloc, index);
 241                         continue;
 242                 }
 243
 244                 if (WARN_ON(!vma))
 245                         goto err_page_ptr_cleared;
 246
 247                 trace_binder_alloc_page_start(alloc, index);
 248                 page->page_ptr = alloc_page(GFP_KERNEL |
 249                                             __GFP_HIGHMEM |
 250                                             __GFP_ZERO);
 251                 if (!page->page_ptr) {
 252                         pr_err("%d: binder_alloc_buf failed for page at %pK\n",
 253                                 alloc->pid, page_addr);
 254                         goto err_alloc_page_failed;
 255                 }
 256                 page->alloc = alloc;
 257                 INIT_LIST_HEAD(&page->lru);
 258
 259                 user_page_addr = (uintptr_t)page_addr;
 260                 ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
 261                 if (ret) {
 262                         pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
 263                                alloc->pid, user_page_addr);
 264                         goto err_vm_insert_page_failed;
 265                 }
 266
 267                 if (index + 1 > alloc->pages_high)
 268                         alloc->pages_high = index + 1;
 269
 270                 trace_binder_alloc_page_end(alloc, index);
 271         }
 272         if (mm) {
 273                 mmap_write_unlock(mm);
 274                 mmput_async(mm);
 275         }
 276         return 0;
 277
 278 free_range:
 279         for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) {
 280                 bool ret;
 281                 size_t index;
 282
 283                 index = (page_addr - alloc->buffer) / PAGE_SIZE;
 284                 page = &alloc->pages[index];
 285
 286                 trace_binder_free_lru_start(alloc, index);
 287
 288                 ret = list_lru_add(&binder_alloc_lru, &page->lru);
 289                 WARN_ON(!ret);
 290
 291                 trace_binder_free_lru_end(alloc, index);
 292                 if (page_addr == start)
 293                         break;
 294                 continue;
 295
 296 err_vm_insert_page_failed:
 297                 __free_page(page->page_ptr);
 298                 page->page_ptr = NULL;
 299 err_alloc_page_failed:
 300 err_page_ptr_cleared:
 301                 if (page_addr == start)
 302                         break;
 303         }
 304 err_no_vma:
 305         if (mm) {
 306                 mmap_write_unlock(mm);
 307                 mmput_async(mm);
 308         }
 309         return vma ? -ENOMEM : -ESRCH;
 310 }
 311
 312
 313 static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
 314                 struct vm_area_struct *vma)
 315 {
 316         if (vma)
 317                 alloc->vma_vm_mm = vma->vm_mm;
 318         /*
 319          * If we see alloc->vma is not NULL, buffer data structures set up
 320          * completely. Look at smp_rmb side binder_alloc_get_vma.
 321          * We also want to guarantee new alloc->vma_vm_mm is always visible
 322          * if alloc->vma is set.
 323          */
 324         smp_wmb();
 325         alloc->vma = vma;
 326 }
 327
 328 static inline struct vm_area_struct *binder_alloc_get_vma(
 329                 struct binder_alloc *alloc)
 330 {
 331         struct vm_area_struct *vma = NULL;
 332
 333         if (alloc->vma) {
 334                 /* Look at description in binder_alloc_set_vma */
 335                 smp_rmb();
 336                 vma = alloc->vma;
 337         }
 338         return vma;
 339 }
 340
 341 static void debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
 342 {
 343         /*
 344          * Find the amount and size of buffers allocated by the current caller;
 345          * The idea is that once we cross the threshold, whoever is responsible
 346          * for the low async space is likely to try to send another async txn,
 347          * and at some point we'll catch them in the act. This is more efficient
 348          * than keeping a map per pid.
 349          */
 350         struct rb_node *n;
 351         struct binder_buffer *buffer;
 352         size_t total_alloc_size = 0;
 353         size_t num_buffers = 0;
 354
 355         for (n = rb_first(&alloc->allocated_buffers); n != NULL;
 356                  n = rb_next(n)) {
 357                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 358                 if (buffer->pid != pid)
 359                         continue;
 360                 if (!buffer->async_transaction)
 361                         continue;
 362                 total_alloc_size += binder_alloc_buffer_size(alloc, buffer);
 363                 num_buffers++;
 364         }
 365
 366         /*
 367          * Warn if this pid has more than 50 transactions, or more than 50% of
 368          * async space (which is 25% of total buffer size).
 369          */
 370         if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
 371                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 372                              "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
 373                               alloc->pid, pid, num_buffers, total_alloc_size);
 374         }
 375 }
 376
 377 static struct binder_buffer *binder_alloc_new_buf_locked(
 378                                 struct binder_alloc *alloc,
 379                                 size_t data_size,
 380                                 size_t offsets_size,
 381                                 size_t extra_buffers_size,
 382                                 int is_async,
 383                                 int pid)
 384 {
 385         struct rb_node *n = alloc->free_buffers.rb_node;
 386         struct binder_buffer *buffer;
 387         size_t buffer_size;
 388         struct rb_node *best_fit = NULL;
 389         void __user *has_page_addr;
 390         void __user *end_page_addr;
 391         size_t size, data_offsets_size;
 392         int ret;
 393
 394         if (!binder_alloc_get_vma(alloc)) {
 395                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 396                                    "%d: binder_alloc_buf, no vma\n",
 397                                    alloc->pid);
 398                 return ERR_PTR(-ESRCH);
 399         }
 400
 401         data_offsets_size = ALIGN(data_size, sizeof(void *)) +
 402                 ALIGN(offsets_size, sizeof(void *));
 403
 404         if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
 405                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 406                                 "%d: got transaction with invalid size %zd-%zd\n",
 407                                 alloc->pid, data_size, offsets_size);
 408                 return ERR_PTR(-EINVAL);
 409         }
 410         size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
 411         if (size < data_offsets_size || size < extra_buffers_size) {
 412                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 413                                 "%d: got transaction with invalid extra_buffers_size %zd\n",
 414                                 alloc->pid, extra_buffers_size);
 415                 return ERR_PTR(-EINVAL);
 416         }
 417
 418         /* Pad 0-size buffers so they get assigned unique addresses */
 419         size = max(size, sizeof(void *));
 420
 421         if (is_async && alloc->free_async_space < size) {
 422                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 423                              "%d: binder_alloc_buf size %zd failed, no async space left\n",
 424                               alloc->pid, size);
 425                 return ERR_PTR(-ENOSPC);
 426         }
 427
 428         while (n) {
 429                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 430                 BUG_ON(!buffer->free);
 431                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
 432
 433                 if (size < buffer_size) {
 434                         best_fit = n;
 435                         n = n->rb_left;
 436                 } else if (size > buffer_size)
 437                         n = n->rb_right;
 438                 else {
 439                         best_fit = n;
 440                         break;
 441                 }
 442         }
 443         if (best_fit == NULL) {
 444                 size_t allocated_buffers = 0;
 445                 size_t largest_alloc_size = 0;
 446                 size_t total_alloc_size = 0;
 447                 size_t free_buffers = 0;
 448                 size_t largest_free_size = 0;
 449                 size_t total_free_size = 0;
 450
 451                 for (n = rb_first(&alloc->allocated_buffers); n != NULL;
 452                      n = rb_next(n)) {
 453                         buffer = rb_entry(n, struct binder_buffer, rb_node);
 454                         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 455                         allocated_buffers++;
 456                         total_alloc_size += buffer_size;
 457                         if (buffer_size > largest_alloc_size)
 458                                 largest_alloc_size = buffer_size;
 459                 }
 460                 for (n = rb_first(&alloc->free_buffers); n != NULL;
 461                      n = rb_next(n)) {
 462                         buffer = rb_entry(n, struct binder_buffer, rb_node);
 463                         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 464                         free_buffers++;
 465                         total_free_size += buffer_size;
 466                         if (buffer_size > largest_free_size)
 467                                 largest_free_size = buffer_size;
 468                 }
 469                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 470                                    "%d: binder_alloc_buf size %zd failed, no address space\n",
 471                                    alloc->pid, size);
 472                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 473                                    "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
 474                                    total_alloc_size, allocated_buffers,
 475                                    largest_alloc_size, total_free_size,
 476                                    free_buffers, largest_free_size);
 477                 return ERR_PTR(-ENOSPC);
 478         }
 479         if (n == NULL) {
 480                 buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
 481                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
 482         }
 483
 484         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 485                      "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
 486                       alloc->pid, size, buffer, buffer_size);
 487
 488         has_page_addr = (void __user *)
 489                 (((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
 490         WARN_ON(n && buffer_size != size);
 491         end_page_addr =
 492                 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
 493         if (end_page_addr > has_page_addr)
 494                 end_page_addr = has_page_addr;
 495         ret = binder_update_page_range(alloc, 1, (void __user *)
 496                 PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr);
 497         if (ret)
 498                 return ERR_PTR(ret);
 499
 500         if (buffer_size != size) {
 501                 struct binder_buffer *new_buffer;
 502
 503                 new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 504                 if (!new_buffer) {
 505                         pr_err("%s: %d failed to alloc new buffer struct\n",
 506                                __func__, alloc->pid);
 507                         goto err_alloc_buf_struct_failed;
 508                 }
 509                 new_buffer->user_data = (u8 __user *)buffer->user_data + size;
 510                 list_add(&new_buffer->entry, &buffer->entry);
 511                 new_buffer->free = 1;
 512                 binder_insert_free_buffer(alloc, new_buffer);
 513         }
 514
 515         rb_erase(best_fit, &alloc->free_buffers);
 516         buffer->free = 0;
 517         buffer->allow_user_free = 0;
 518         binder_insert_allocated_buffer_locked(alloc, buffer);
 519         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 520                      "%d: binder_alloc_buf size %zd got %pK\n",
 521                       alloc->pid, size, buffer);
 522         buffer->data_size = data_size;
 523         buffer->offsets_size = offsets_size;
 524         buffer->async_transaction = is_async;
 525         buffer->extra_buffers_size = extra_buffers_size;
 526         buffer->pid = pid;
 527         if (is_async) {
 528                 alloc->free_async_space -= size;
 529                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 530                              "%d: binder_alloc_buf size %zd async free %zd\n",
 531                               alloc->pid, size, alloc->free_async_space);
 532                 if (alloc->free_async_space < alloc->buffer_size / 10) {
 533                         /*
 534                          * Start detecting spammers once we have less than 20%
 535                          * of async space left (which is less than 10% of total
 536                          * buffer size).
 537                          */
 538                         debug_low_async_space_locked(alloc, pid);
 539                 }
 540         }
 541         return buffer;
 542
 543 err_alloc_buf_struct_failed:
 544         binder_update_page_range(alloc, 0, (void __user *)
 545                                  PAGE_ALIGN((uintptr_t)buffer->user_data),
 546                                  end_page_addr);
 547         return ERR_PTR(-ENOMEM);
 548 }
 549
 550 /**
 551  * binder_alloc_new_buf() - Allocate a new binder buffer
 552  * @alloc:              binder_alloc for this proc
 553  * @data_size:          size of user data buffer
 554  * @offsets_size:       user specified buffer offset
 555  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
 556  * @is_async:           buffer for async transaction
 557  * @pid:                                pid to attribute allocation to (used for debugging)
 558  *
 559  * Allocate a new buffer given the requested sizes. Returns
 560  * the kernel version of the buffer pointer. The size allocated
 561  * is the sum of the three given sizes (each rounded up to
 562  * pointer-sized boundary)
 563  *
 564  * Return:      The allocated buffer or %ERR_PTR(-errno) if error
 565  */
 566 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 567                                            size_t data_size,
 568                                            size_t offsets_size,
 569                                            size_t extra_buffers_size,
 570                                            int is_async,
 571                                            int pid)
 572 {
 573         struct binder_buffer *buffer;
 574
 575         mutex_lock(&alloc->mutex);
 576         buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
 577                                              extra_buffers_size, is_async, pid);
 578         mutex_unlock(&alloc->mutex);
 579         return buffer;
 580 }
 581
 582 static void __user *buffer_start_page(struct binder_buffer *buffer)
 583 {
 584         return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
 585 }
 586
 587 static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
 588 {
 589         return (void __user *)
 590                 (((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
 591 }
 592
 593 static void binder_delete_free_buffer(struct binder_alloc *alloc,
 594                                       struct binder_buffer *buffer)
 595 {
 596         struct binder_buffer *prev, *next = NULL;
 597         bool to_free = true;
 598
 599         BUG_ON(alloc->buffers.next == &buffer->entry);
 600         prev = binder_buffer_prev(buffer);
 601         BUG_ON(!prev->free);
 602         if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
 603                 to_free = false;
 604                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 605                                    "%d: merge free, buffer %pK share page with %pK\n",
 606                                    alloc->pid, buffer->user_data,
 607                                    prev->user_data);
 608         }
 609
 610         if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 611                 next = binder_buffer_next(buffer);
 612                 if (buffer_start_page(next) == buffer_start_page(buffer)) {
 613                         to_free = false;
 614                         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 615                                            "%d: merge free, buffer %pK share page with %pK\n",
 616                                            alloc->pid,
 617                                            buffer->user_data,
 618                                            next->user_data);
 619                 }
 620         }
 621
 622         if (PAGE_ALIGNED(buffer->user_data)) {
 623                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 624                                    "%d: merge free, buffer start %pK is page aligned\n",
 625                                    alloc->pid, buffer->user_data);
 626                 to_free = false;
 627         }
 628
 629         if (to_free) {
 630                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 631                                    "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
 632                                    alloc->pid, buffer->user_data,
 633                                    prev->user_data,
 634                                    next ? next->user_data : NULL);
 635                 binder_update_page_range(alloc, 0, buffer_start_page(buffer),
 636                                          buffer_start_page(buffer) + PAGE_SIZE);
 637         }
 638         list_del(&buffer->entry);
 639         kfree(buffer);
 640 }
 641
 642 static void binder_free_buf_locked(struct binder_alloc *alloc,
 643                                    struct binder_buffer *buffer)
 644 {
 645         size_t size, buffer_size;
 646
 647         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 648
 649         size = ALIGN(buffer->data_size, sizeof(void *)) +
 650                 ALIGN(buffer->offsets_size, sizeof(void *)) +
 651                 ALIGN(buffer->extra_buffers_size, sizeof(void *));
 652
 653         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 654                      "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
 655                       alloc->pid, buffer, size, buffer_size);
 656
 657         BUG_ON(buffer->free);
 658         BUG_ON(size > buffer_size);
 659         BUG_ON(buffer->transaction != NULL);
 660         BUG_ON(buffer->user_data < alloc->buffer);
 661         BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
 662
 663         if (buffer->async_transaction) {
 664                 alloc->free_async_space += buffer_size;
 665                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 666                              "%d: binder_free_buf size %zd async free %zd\n",
 667                               alloc->pid, size, alloc->free_async_space);
 668         }
 669
 670         binder_update_page_range(alloc, 0,
 671                 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
 672                 (void __user *)(((uintptr_t)
 673                           buffer->user_data + buffer_size) & PAGE_MASK));
 674
 675         rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
 676         buffer->free = 1;
 677         if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 678                 struct binder_buffer *next = binder_buffer_next(buffer);
 679
 680                 if (next->free) {
 681                         rb_erase(&next->rb_node, &alloc->free_buffers);
 682                         binder_delete_free_buffer(alloc, next);
 683                 }
 684         }
 685         if (alloc->buffers.next != &buffer->entry) {
 686                 struct binder_buffer *prev = binder_buffer_prev(buffer);
 687
 688                 if (prev->free) {
 689                         binder_delete_free_buffer(alloc, buffer);
 690                         rb_erase(&prev->rb_node, &alloc->free_buffers);
 691                         buffer = prev;
 692                 }
 693         }
 694         binder_insert_free_buffer(alloc, buffer);
 695 }
 696
 697 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
 698                                    struct binder_buffer *buffer);
 699 /**
 700  * binder_alloc_free_buf() - free a binder buffer
 701  * @alloc:      binder_alloc for this proc
 702  * @buffer:     kernel pointer to buffer
 703  *
 704  * Free the buffer allocated via binder_alloc_new_buf()
 705  */
 706 void binder_alloc_free_buf(struct binder_alloc *alloc,
 707                             struct binder_buffer *buffer)
 708 {
 709         /*
 710          * We could eliminate the call to binder_alloc_clear_buf()
 711          * from binder_alloc_deferred_release() by moving this to
 712          * binder_free_buf_locked(). However, that could
 713          * increase contention for the alloc mutex if clear_on_free
 714          * is used frequently for large buffers. The mutex is not
 715          * needed for correctness here.
 716          */
 717         if (buffer->clear_on_free) {
 718                 binder_alloc_clear_buf(alloc, buffer);
 719                 buffer->clear_on_free = false;
 720         }
 721         mutex_lock(&alloc->mutex);
 722         binder_free_buf_locked(alloc, buffer);
 723         mutex_unlock(&alloc->mutex);
 724 }
 725
 726 /**
 727  * binder_alloc_mmap_handler() - map virtual address space for proc
 728  * @alloc:      alloc structure for this proc
 729  * @vma:        vma passed to mmap()
 730  *
 731  * Called by binder_mmap() to initialize the space specified in
 732  * vma for allocating binder buffers
 733  *
 734  * Return:
 735  *      0 = success
 736  *      -EBUSY = address space already mapped
 737  *      -ENOMEM = failed to map memory to given address space
 738  */
 739 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 740                               struct vm_area_struct *vma)
 741 {
 742         int ret;
 743         const char *failure_string;
 744         struct binder_buffer *buffer;
 745
 746         mutex_lock(&binder_alloc_mmap_lock);
 747         if (alloc->buffer_size) {
 748                 ret = -EBUSY;
 749                 failure_string = "already mapped";
 750                 goto err_already_mapped;
 751         }
 752         alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
 753                                    SZ_4M);
 754         mutex_unlock(&binder_alloc_mmap_lock);
 755
 756         alloc->buffer = (void __user *)vma->vm_start;
 757
 758         alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
 759                                sizeof(alloc->pages[0]),
 760                                GFP_KERNEL);
 761         if (alloc->pages == NULL) {
 762                 ret = -ENOMEM;
 763                 failure_string = "alloc page array";
 764                 goto err_alloc_pages_failed;
 765         }
 766
 767         buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 768         if (!buffer) {
 769                 ret = -ENOMEM;
 770                 failure_string = "alloc buffer struct";
 771                 goto err_alloc_buf_struct_failed;
 772         }
 773
 774         buffer->user_data = alloc->buffer;
 775         list_add(&buffer->entry, &alloc->buffers);
 776         buffer->free = 1;
 777         binder_insert_free_buffer(alloc, buffer);
 778         alloc->free_async_space = alloc->buffer_size / 2;
 779         binder_alloc_set_vma(alloc, vma);
 780         mmgrab(alloc->vma_vm_mm);
 781
 782         return 0;
 783
 784 err_alloc_buf_struct_failed:
 785         kfree(alloc->pages);
 786         alloc->pages = NULL;
 787 err_alloc_pages_failed:
 788         alloc->buffer = NULL;
 789         mutex_lock(&binder_alloc_mmap_lock);
 790         alloc->buffer_size = 0;
 791 err_already_mapped:
 792         mutex_unlock(&binder_alloc_mmap_lock);
 793         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 794                            "%s: %d %lx-%lx %s failed %d\n", __func__,
 795                            alloc->pid, vma->vm_start, vma->vm_end,
 796                            failure_string, ret);
 797         return ret;
 798 }
 799
 800
 801 void binder_alloc_deferred_release(struct binder_alloc *alloc)
 802 {
 803         struct rb_node *n;
 804         int buffers, page_count;
 805         struct binder_buffer *buffer;
 806
 807         buffers = 0;
 808         mutex_lock(&alloc->mutex);
 809         BUG_ON(alloc->vma);
 810
 811         while ((n = rb_first(&alloc->allocated_buffers))) {
 812                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 813
 814                 /* Transaction should already have been freed */
 815                 BUG_ON(buffer->transaction);
 816
 817                 if (buffer->clear_on_free) {
 818                         binder_alloc_clear_buf(alloc, buffer);
 819                         buffer->clear_on_free = false;
 820                 }
 821                 binder_free_buf_locked(alloc, buffer);
 822                 buffers++;
 823         }
 824
 825         while (!list_empty(&alloc->buffers)) {
 826                 buffer = list_first_entry(&alloc->buffers,
 827                                           struct binder_buffer, entry);
 828                 WARN_ON(!buffer->free);
 829
 830                 list_del(&buffer->entry);
 831                 WARN_ON_ONCE(!list_empty(&alloc->buffers));
 832                 kfree(buffer);
 833         }
 834
 835         page_count = 0;
 836         if (alloc->pages) {
 837                 int i;
 838
 839                 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 840                         void __user *page_addr;
 841                         bool on_lru;
 842
 843                         if (!alloc->pages[i].page_ptr)
 844                                 continue;
 845
 846                         on_lru = list_lru_del(&binder_alloc_lru,
 847                                               &alloc->pages[i].lru);
 848                         page_addr = alloc->buffer + i * PAGE_SIZE;
 849                         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 850                                      "%s: %d: page %d at %pK %s\n",
 851                                      __func__, alloc->pid, i, page_addr,
 852                                      on_lru ? "on lru" : "active");
 853                         __free_page(alloc->pages[i].page_ptr);
 854                         page_count++;
 855                 }
 856                 kfree(alloc->pages);
 857         }
 858         mutex_unlock(&alloc->mutex);
 859         if (alloc->vma_vm_mm)
 860                 mmdrop(alloc->vma_vm_mm);
 861
 862         binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
 863                      "%s: %d buffers %d, pages %d\n",
 864                      __func__, alloc->pid, buffers, page_count);
 865 }
 866
 867 static void print_binder_buffer(struct seq_file *m, const char *prefix,
 868                                 struct binder_buffer *buffer)
 869 {
 870         seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
 871                    prefix, buffer->debug_id, buffer->user_data,
 872                    buffer->data_size, buffer->offsets_size,
 873                    buffer->extra_buffers_size,
 874                    buffer->transaction ? "active" : "delivered");
 875 }
 876
 877 /**
 878  * binder_alloc_print_allocated() - print buffer info
 879  * @m:     seq_file for output via seq_printf()
 880  * @alloc: binder_alloc for this proc
 881  *
 882  * Prints information about every buffer associated with
 883  * the binder_alloc state to the given seq_file
 884  */
 885 void binder_alloc_print_allocated(struct seq_file *m,
 886                                   struct binder_alloc *alloc)
 887 {
 888         struct rb_node *n;
 889
 890         mutex_lock(&alloc->mutex);
 891         for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 892                 print_binder_buffer(m, "  buffer",
 893                                     rb_entry(n, struct binder_buffer, rb_node));
 894         mutex_unlock(&alloc->mutex);
 895 }
 896
 897 /**
 898  * binder_alloc_print_pages() - print page usage
 899  * @m:     seq_file for output via seq_printf()
 900  * @alloc: binder_alloc for this proc
 901  */
 902 void binder_alloc_print_pages(struct seq_file *m,
 903                               struct binder_alloc *alloc)
 904 {
 905         struct binder_lru_page *page;
 906         int i;
 907         int active = 0;
 908         int lru = 0;
 909         int free = 0;
 910
 911         mutex_lock(&alloc->mutex);
 912         /*
 913          * Make sure the binder_alloc is fully initialized, otherwise we might
 914          * read inconsistent state.
 915          */
 916         if (binder_alloc_get_vma(alloc) != NULL) {
 917                 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 918                         page = &alloc->pages[i];
 919                         if (!page->page_ptr)
 920                                 free++;
 921                         else if (list_empty(&page->lru))
 922                                 active++;
 923                         else
 924                                 lru++;
 925                 }
 926         }
 927         mutex_unlock(&alloc->mutex);
 928         seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
 929         seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
 930 }
 931
 932 /**
 933  * binder_alloc_get_allocated_count() - return count of buffers
 934  * @alloc: binder_alloc for this proc
 935  *
 936  * Return: count of allocated buffers
 937  */
 938 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
 939 {
 940         struct rb_node *n;
 941         int count = 0;
 942
 943         mutex_lock(&alloc->mutex);
 944         for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 945                 count++;
 946         mutex_unlock(&alloc->mutex);
 947         return count;
 948 }
 949
 950
 951 /**
 952  * binder_alloc_vma_close() - invalidate address space
 953  * @alloc: binder_alloc for this proc
 954  *
 955  * Called from binder_vma_close() when releasing address space.
 956  * Clears alloc->vma to prevent new incoming transactions from
 957  * allocating more buffers.
 958  */
 959 void binder_alloc_vma_close(struct binder_alloc *alloc)
 960 {
 961         binder_alloc_set_vma(alloc, NULL);
 962 }
 963
 964 /**
 965  * binder_alloc_free_page() - shrinker callback to free pages
 966  * @item:   item to free
 967  * @lock:   lock protecting the item
 968  * @cb_arg: callback argument
 969  *
 970  * Called from list_lru_walk() in binder_shrink_scan() to free
 971  * up pages when the system is under memory pressure.
 972  */
 973 enum lru_status binder_alloc_free_page(struct list_head *item,
 974                                        struct list_lru_one *lru,
 975                                        spinlock_t *lock,
 976                                        void *cb_arg)
 977         __must_hold(lock)
 978 {
 979         struct mm_struct *mm = NULL;
 980         struct binder_lru_page *page = container_of(item,
 981                                                     struct binder_lru_page,
 982                                                     lru);
 983         struct binder_alloc *alloc;
 984         uintptr_t page_addr;
 985         size_t index;
 986         struct vm_area_struct *vma;
 987
 988         alloc = page->alloc;
 989         if (!mutex_trylock(&alloc->mutex))
 990                 goto err_get_alloc_mutex_failed;
 991
 992         if (!page->page_ptr)
 993                 goto err_page_already_freed;
 994
 995         index = page - alloc->pages;
 996         page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
 997
 998         mm = alloc->vma_vm_mm;
 999         if (!mmget_not_zero(mm))
1000                 goto err_mmget;
1001         if (!mmap_read_trylock(mm))
1002                 goto err_mmap_read_lock_failed;
1003         vma = find_vma(mm, page_addr);
1004         if (vma && vma != binder_alloc_get_vma(alloc))
1005                 goto err_invalid_vma;
1006
1007         list_lru_isolate(lru, item);
1008         spin_unlock(lock);
1009
1010         if (vma) {
1011                 trace_binder_unmap_user_start(alloc, index);
1012
1013                 zap_page_range(vma, page_addr, PAGE_SIZE);
1014
1015                 trace_binder_unmap_user_end(alloc, index);
1016         }
1017         mmap_read_unlock(mm);
1018         mmput_async(mm);
1019
1020         trace_binder_unmap_kernel_start(alloc, index);
1021
1022         __free_page(page->page_ptr);
1023         page->page_ptr = NULL;
1024
1025         trace_binder_unmap_kernel_end(alloc, index);
1026
1027         spin_lock(lock);
1028         mutex_unlock(&alloc->mutex);
1029         return LRU_REMOVED_RETRY;
1030
1031 err_invalid_vma:
1032         mmap_read_unlock(mm);
1033 err_mmap_read_lock_failed:
1034         mmput_async(mm);
1035 err_mmget:
1036 err_page_already_freed:
1037         mutex_unlock(&alloc->mutex);
1038 err_get_alloc_mutex_failed:
1039         return LRU_SKIP;
1040 }
1041
1042 static unsigned long
1043 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1044 {
1045         unsigned long ret = list_lru_count(&binder_alloc_lru);
1046         return ret;
1047 }
1048
1049 static unsigned long
1050 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1051 {
1052         unsigned long ret;
1053
1054         ret = list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
1055                             NULL, sc->nr_to_scan);
1056         return ret;
1057 }
1058
1059 static struct shrinker binder_shrinker = {
1060         .count_objects = binder_shrink_count,
1061         .scan_objects = binder_shrink_scan,
1062         .seeks = DEFAULT_SEEKS,
1063 };
1064
1065 /**
1066  * binder_alloc_init() - called by binder_open() for per-proc initialization
1067  * @alloc: binder_alloc for this proc
1068  *
1069  * Called from binder_open() to initialize binder_alloc fields for
1070  * new binder proc
1071  */
1072 void binder_alloc_init(struct binder_alloc *alloc)
1073 {
1074         alloc->pid = current->group_leader->pid;
1075         mutex_init(&alloc->mutex);
1076         INIT_LIST_HEAD(&alloc->buffers);
1077 }
1078
1079 int binder_alloc_shrinker_init(void)
1080 {
1081         int ret = list_lru_init(&binder_alloc_lru);
1082
1083         if (ret == 0) {
1084                 ret = register_shrinker(&binder_shrinker);
1085                 if (ret)
1086                         list_lru_destroy(&binder_alloc_lru);
1087         }
1088         return ret;
1089 }
1090
1091 void binder_alloc_shrinker_exit(void)
1092 {
1093         unregister_shrinker(&binder_shrinker);
1094         list_lru_destroy(&binder_alloc_lru);
1095 }
1096
1097 /**
1098  * check_buffer() - verify that buffer/offset is safe to access
1099  * @alloc: binder_alloc for this proc
1100  * @buffer: binder buffer to be accessed
1101  * @offset: offset into @buffer data
1102  * @bytes: bytes to access from offset
1103  *
1104  * Check that the @offset/@bytes are within the size of the given
1105  * @buffer and that the buffer is currently active and not freeable.
1106  * Offsets must also be multiples of sizeof(u32). The kernel is
1107  * allowed to touch the buffer in two cases:
1108  *
1109  * 1) when the buffer is being created:
1110  *     (buffer->free == 0 && buffer->allow_user_free == 0)
1111  * 2) when the buffer is being torn down:
1112  *     (buffer->free == 0 && buffer->transaction == NULL).
1113  *
1114  * Return: true if the buffer is safe to access
1115  */
1116 static inline bool check_buffer(struct binder_alloc *alloc,
1117                                 struct binder_buffer *buffer,
1118                                 binder_size_t offset, size_t bytes)
1119 {
1120         size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
1121
1122         return buffer_size >= bytes &&
1123                 offset <= buffer_size - bytes &&
1124                 IS_ALIGNED(offset, sizeof(u32)) &&
1125                 !buffer->free &&
1126                 (!buffer->allow_user_free || !buffer->transaction);
1127 }
1128
1129 /**
1130  * binder_alloc_get_page() - get kernel pointer for given buffer offset
1131  * @alloc: binder_alloc for this proc
1132  * @buffer: binder buffer to be accessed
1133  * @buffer_offset: offset into @buffer data
1134  * @pgoffp: address to copy final page offset to
1135  *
1136  * Lookup the struct page corresponding to the address
1137  * at @buffer_offset into @buffer->user_data. If @pgoffp is not
1138  * NULL, the byte-offset into the page is written there.
1139  *
1140  * The caller is responsible to ensure that the offset points
1141  * to a valid address within the @buffer and that @buffer is
1142  * not freeable by the user. Since it can't be freed, we are
1143  * guaranteed that the corresponding elements of @alloc->pages[]
1144  * cannot change.
1145  *
1146  * Return: struct page
1147  */
1148 static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
1149                                           struct binder_buffer *buffer,
1150                                           binder_size_t buffer_offset,
1151                                           pgoff_t *pgoffp)
1152 {
1153         binder_size_t buffer_space_offset = buffer_offset +
1154                 (buffer->user_data - alloc->buffer);
1155         pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
1156         size_t index = buffer_space_offset >> PAGE_SHIFT;
1157         struct binder_lru_page *lru_page;
1158
1159         lru_page = &alloc->pages[index];
1160         *pgoffp = pgoff;
1161         return lru_page->page_ptr;
1162 }
1163
1164 /**
1165  * binder_alloc_clear_buf() - zero out buffer
1166  * @alloc: binder_alloc for this proc
1167  * @buffer: binder buffer to be cleared
1168  *
1169  * memset the given buffer to 0
1170  */
1171 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
1172                                    struct binder_buffer *buffer)
1173 {
1174         size_t bytes = binder_alloc_buffer_size(alloc, buffer);
1175         binder_size_t buffer_offset = 0;
1176
1177         while (bytes) {
1178                 unsigned long size;
1179                 struct page *page;
1180                 pgoff_t pgoff;
1181                 void *kptr;
1182
1183                 page = binder_alloc_get_page(alloc, buffer,
1184                                              buffer_offset, &pgoff);
1185                 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1186                 kptr = kmap(page) + pgoff;
1187                 memset(kptr, 0, size);
1188                 kunmap(page);
1189                 bytes -= size;
1190                 buffer_offset += size;
1191         }
1192 }
1193
1194 /**
1195  * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
1196  * @alloc: binder_alloc for this proc
1197  * @buffer: binder buffer to be accessed
1198  * @buffer_offset: offset into @buffer data
1199  * @from: userspace pointer to source buffer
1200  * @bytes: bytes to copy
1201  *
1202  * Copy bytes from source userspace to target buffer.
1203  *
1204  * Return: bytes remaining to be copied
1205  */
1206 unsigned long
1207 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
1208                                  struct binder_buffer *buffer,
1209                                  binder_size_t buffer_offset,
1210                                  const void __user *from,
1211                                  size_t bytes)
1212 {
1213         if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1214                 return bytes;
1215
1216         while (bytes) {
1217                 unsigned long size;
1218                 unsigned long ret;
1219                 struct page *page;
1220                 pgoff_t pgoff;
1221                 void *kptr;
1222
1223                 page = binder_alloc_get_page(alloc, buffer,
1224                                              buffer_offset, &pgoff);
1225                 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1226                 kptr = kmap(page) + pgoff;
1227                 ret = copy_from_user(kptr, from, size);
1228                 kunmap(page);
1229                 if (ret)
1230                         return bytes - size + ret;
1231                 bytes -= size;
1232                 from += size;
1233                 buffer_offset += size;
1234         }
1235         return 0;
1236 }
1237
1238 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
1239                                        bool to_buffer,
1240                                        struct binder_buffer *buffer,
1241                                        binder_size_t buffer_offset,
1242                                        void *ptr,
1243                                        size_t bytes)
1244 {
1245         /* All copies must be 32-bit aligned and 32-bit size */
1246         if (!check_buffer(alloc, buffer, buffer_offset, bytes))
1247                 return -EINVAL;
1248
1249         while (bytes) {
1250                 unsigned long size;
1251                 struct page *page;
1252                 pgoff_t pgoff;
1253                 void *tmpptr;
1254                 void *base_ptr;
1255
1256                 page = binder_alloc_get_page(alloc, buffer,
1257                                              buffer_offset, &pgoff);
1258                 size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
1259                 base_ptr = kmap_atomic(page);
1260                 tmpptr = base_ptr + pgoff;
1261                 if (to_buffer)
1262                         memcpy(tmpptr, ptr, size);
1263                 else
1264                         memcpy(ptr, tmpptr, size);
1265                 /*
1266                  * kunmap_atomic() takes care of flushing the cache
1267                  * if this device has VIVT cache arch
1268                  */
1269                 kunmap_atomic(base_ptr);
1270                 bytes -= size;
1271                 pgoff = 0;
1272                 ptr = ptr + size;
1273                 buffer_offset += size;
1274         }
1275         return 0;
1276 }
1277
1278 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
1279                                 struct binder_buffer *buffer,
1280                                 binder_size_t buffer_offset,
1281                                 void *src,
1282                                 size_t bytes)
1283 {
1284         return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
1285                                            src, bytes);
1286 }
1287
1288 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
1289                                   void *dest,
1290                                   struct binder_buffer *buffer,
1291                                   binder_size_t buffer_offset,
1292                                   size_t bytes)
1293 {
1294         return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
1295                                            dest, bytes);
1296 }
1297