drivers/android/binder_alloc.c

   1 /* binder_alloc.c
   2  *
   3  * Android IPC Subsystem
   4  *
   5  * Copyright (C) 2007-2017 Google, Inc.
   6  *
   7  * This software is licensed under the terms of the GNU General Public
   8  * License version 2, as published by the Free Software Foundation, and
   9  * may be copied, distributed, and modified under those terms.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/list.h>
  21 #include <linux/sched/mm.h>
  22 #include <linux/module.h>
  23 #include <linux/rtmutex.h>
  24 #include <linux/rbtree.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/vmalloc.h>
  27 #include <linux/slab.h>
  28 #include <linux/sched.h>
  29 #include <linux/list_lru.h>
  30 #include <linux/ratelimit.h>
  31 #include <asm/cacheflush.h>
  32 #include "binder_alloc.h"
  33 #include "binder_trace.h"
  34
  35 struct list_lru binder_alloc_lru;
  36
  37 static DEFINE_MUTEX(binder_alloc_mmap_lock);
  38
  39 enum {
  40         BINDER_DEBUG_USER_ERROR             = 1U << 0,
  41         BINDER_DEBUG_OPEN_CLOSE             = 1U << 1,
  42         BINDER_DEBUG_BUFFER_ALLOC           = 1U << 2,
  43         BINDER_DEBUG_BUFFER_ALLOC_ASYNC     = 1U << 3,
  44 };
  45 static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR;
  46
  47 module_param_named(debug_mask, binder_alloc_debug_mask,
  48                    uint, 0644);
  49
  50 #define binder_alloc_debug(mask, x...) \
  51         do { \
  52                 if (binder_alloc_debug_mask & mask) \
  53                         pr_info_ratelimited(x); \
  54         } while (0)
  55
  56 static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
  57 {
  58         return list_entry(buffer->entry.next, struct binder_buffer, entry);
  59 }
  60
  61 static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
  62 {
  63         return list_entry(buffer->entry.prev, struct binder_buffer, entry);
  64 }
  65
  66 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
  67                                        struct binder_buffer *buffer)
  68 {
  69         if (list_is_last(&buffer->entry, &alloc->buffers))
  70                 return (u8 *)alloc->buffer +
  71                         alloc->buffer_size - (u8 *)buffer->data;
  72         return (u8 *)binder_buffer_next(buffer)->data - (u8 *)buffer->data;
  73 }
  74
  75 static void binder_insert_free_buffer(struct binder_alloc *alloc,
  76                                       struct binder_buffer *new_buffer)
  77 {
  78         struct rb_node **p = &alloc->free_buffers.rb_node;
  79         struct rb_node *parent = NULL;
  80         struct binder_buffer *buffer;
  81         size_t buffer_size;
  82         size_t new_buffer_size;
  83
  84         BUG_ON(!new_buffer->free);
  85
  86         new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
  87
  88         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
  89                      "%d: add free buffer, size %zd, at %pK\n",
  90                       alloc->pid, new_buffer_size, new_buffer);
  91
  92         while (*p) {
  93                 parent = *p;
  94                 buffer = rb_entry(parent, struct binder_buffer, rb_node);
  95                 BUG_ON(!buffer->free);
  96
  97                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
  98
  99                 if (new_buffer_size < buffer_size)
 100                         p = &parent->rb_left;
 101                 else
 102                         p = &parent->rb_right;
 103         }
 104         rb_link_node(&new_buffer->rb_node, parent, p);
 105         rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers);
 106 }
 107
 108 static void binder_insert_allocated_buffer_locked(
 109                 struct binder_alloc *alloc, struct binder_buffer *new_buffer)
 110 {
 111         struct rb_node **p = &alloc->allocated_buffers.rb_node;
 112         struct rb_node *parent = NULL;
 113         struct binder_buffer *buffer;
 114
 115         BUG_ON(new_buffer->free);
 116
 117         while (*p) {
 118                 parent = *p;
 119                 buffer = rb_entry(parent, struct binder_buffer, rb_node);
 120                 BUG_ON(buffer->free);
 121
 122                 if (new_buffer->data < buffer->data)
 123                         p = &parent->rb_left;
 124                 else if (new_buffer->data > buffer->data)
 125                         p = &parent->rb_right;
 126                 else
 127                         BUG();
 128         }
 129         rb_link_node(&new_buffer->rb_node, parent, p);
 130         rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers);
 131 }
 132
 133 static struct binder_buffer *binder_alloc_prepare_to_free_locked(
 134                 struct binder_alloc *alloc,
 135                 uintptr_t user_ptr)
 136 {
 137         struct rb_node *n = alloc->allocated_buffers.rb_node;
 138         struct binder_buffer *buffer;
 139         void *kern_ptr;
 140
 141         kern_ptr = (void *)(user_ptr - alloc->user_buffer_offset);
 142
 143         while (n) {
 144                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 145                 BUG_ON(buffer->free);
 146
 147                 if (kern_ptr < buffer->data)
 148                         n = n->rb_left;
 149                 else if (kern_ptr > buffer->data)
 150                         n = n->rb_right;
 151                 else {
 152                         /*
 153                          * Guard against user threads attempting to
 154                          * free the buffer when in use by kernel or
 155                          * after it's already been freed.
 156                          */
 157                         if (!buffer->allow_user_free)
 158                                 return ERR_PTR(-EPERM);
 159                         buffer->allow_user_free = 0;
 160                         return buffer;
 161                 }
 162         }
 163         return NULL;
 164 }
 165
 166 /**
 167  * binder_alloc_buffer_lookup() - get buffer given user ptr
 168  * @alloc:      binder_alloc for this proc
 169  * @user_ptr:   User pointer to buffer data
 170  *
 171  * Validate userspace pointer to buffer data and return buffer corresponding to
 172  * that user pointer. Search the rb tree for buffer that matches user data
 173  * pointer.
 174  *
 175  * Return:      Pointer to buffer or NULL
 176  */
 177 struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
 178                                                    uintptr_t user_ptr)
 179 {
 180         struct binder_buffer *buffer;
 181
 182         mutex_lock(&alloc->mutex);
 183         buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
 184         mutex_unlock(&alloc->mutex);
 185         return buffer;
 186 }
 187
 188 static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 189                                     void *start, void *end)
 190 {
 191         void *page_addr;
 192         unsigned long user_page_addr;
 193         struct binder_lru_page *page;
 194         struct vm_area_struct *vma = NULL;
 195         struct mm_struct *mm = NULL;
 196         bool need_mm = false;
 197
 198         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 199                      "%d: %s pages %pK-%pK\n", alloc->pid,
 200                      allocate ? "allocate" : "free", start, end);
 201
 202         if (end <= start)
 203                 return 0;
 204
 205         trace_binder_update_page_range(alloc, allocate, start, end);
 206
 207         if (allocate == 0)
 208                 goto free_range;
 209
 210         for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 211                 page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
 212                 if (!page->page_ptr) {
 213                         need_mm = true;
 214                         break;
 215                 }
 216         }
 217
 218         if (need_mm && mmget_not_zero(alloc->vma_vm_mm))
 219                 mm = alloc->vma_vm_mm;
 220
 221         if (mm) {
 222                 down_read(&mm->mmap_sem);
 223                 vma = alloc->vma;
 224         }
 225
 226         if (!vma && need_mm) {
 227                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 228                                    "%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
 229                                    alloc->pid);
 230                 goto err_no_vma;
 231         }
 232
 233         for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 234                 int ret;
 235                 bool on_lru;
 236                 size_t index;
 237
 238                 index = (page_addr - alloc->buffer) / PAGE_SIZE;
 239                 page = &alloc->pages[index];
 240
 241                 if (page->page_ptr) {
 242                         trace_binder_alloc_lru_start(alloc, index);
 243
 244                         on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
 245                         WARN_ON(!on_lru);
 246
 247                         trace_binder_alloc_lru_end(alloc, index);
 248                         continue;
 249                 }
 250
 251                 if (WARN_ON(!vma))
 252                         goto err_page_ptr_cleared;
 253
 254                 trace_binder_alloc_page_start(alloc, index);
 255                 page->page_ptr = alloc_page(GFP_KERNEL |
 256                                             __GFP_HIGHMEM |
 257                                             __GFP_ZERO);
 258                 if (!page->page_ptr) {
 259                         pr_err("%d: binder_alloc_buf failed for page at %pK\n",
 260                                 alloc->pid, page_addr);
 261                         goto err_alloc_page_failed;
 262                 }
 263                 page->alloc = alloc;
 264                 INIT_LIST_HEAD(&page->lru);
 265
 266                 ret = map_kernel_range_noflush((unsigned long)page_addr,
 267                                                PAGE_SIZE, PAGE_KERNEL,
 268                                                &page->page_ptr);
 269                 flush_cache_vmap((unsigned long)page_addr,
 270                                 (unsigned long)page_addr + PAGE_SIZE);
 271                 if (ret != 1) {
 272                         pr_err("%d: binder_alloc_buf failed to map page at %pK in kernel\n",
 273                                alloc->pid, page_addr);
 274                         goto err_map_kernel_failed;
 275                 }
 276                 user_page_addr =
 277                         (uintptr_t)page_addr + alloc->user_buffer_offset;
 278                 ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
 279                 if (ret) {
 280                         pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
 281                                alloc->pid, user_page_addr);
 282                         goto err_vm_insert_page_failed;
 283                 }
 284
 285                 if (index + 1 > alloc->pages_high)
 286                         alloc->pages_high = index + 1;
 287
 288                 trace_binder_alloc_page_end(alloc, index);
 289                 /* vm_insert_page does not seem to increment the refcount */
 290         }
 291         if (mm) {
 292                 up_read(&mm->mmap_sem);
 293                 mmput(mm);
 294         }
 295         return 0;
 296
 297 free_range:
 298         for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) {
 299                 bool ret;
 300                 size_t index;
 301
 302                 index = (page_addr - alloc->buffer) / PAGE_SIZE;
 303                 page = &alloc->pages[index];
 304
 305                 trace_binder_free_lru_start(alloc, index);
 306
 307                 ret = list_lru_add(&binder_alloc_lru, &page->lru);
 308                 WARN_ON(!ret);
 309
 310                 trace_binder_free_lru_end(alloc, index);
 311                 if (page_addr == start)
 312                         break;
 313                 continue;
 314
 315 err_vm_insert_page_failed:
 316                 unmap_kernel_range((unsigned long)page_addr, PAGE_SIZE);
 317 err_map_kernel_failed:
 318                 __free_page(page->page_ptr);
 319                 page->page_ptr = NULL;
 320 err_alloc_page_failed:
 321 err_page_ptr_cleared:
 322                 if (page_addr == start)
 323                         break;
 324         }
 325 err_no_vma:
 326         if (mm) {
 327                 up_read(&mm->mmap_sem);
 328                 mmput(mm);
 329         }
 330         return vma ? -ENOMEM : -ESRCH;
 331 }
 332
 333
 334 static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
 335                 struct vm_area_struct *vma)
 336 {
 337         if (vma)
 338                 alloc->vma_vm_mm = vma->vm_mm;
 339         /*
 340          * If we see alloc->vma is not NULL, buffer data structures set up
 341          * completely. Look at smp_rmb side binder_alloc_get_vma.
 342          * We also want to guarantee new alloc->vma_vm_mm is always visible
 343          * if alloc->vma is set.
 344          */
 345         smp_wmb();
 346         alloc->vma = vma;
 347 }
 348
 349 static inline struct vm_area_struct *binder_alloc_get_vma(
 350                 struct binder_alloc *alloc)
 351 {
 352         struct vm_area_struct *vma = NULL;
 353
 354         if (alloc->vma) {
 355                 /* Look at description in binder_alloc_set_vma */
 356                 smp_rmb();
 357                 vma = alloc->vma;
 358         }
 359         return vma;
 360 }
 361
 362 static struct binder_buffer *binder_alloc_new_buf_locked(
 363                                 struct binder_alloc *alloc,
 364                                 size_t data_size,
 365                                 size_t offsets_size,
 366                                 size_t extra_buffers_size,
 367                                 int is_async)
 368 {
 369         struct rb_node *n = alloc->free_buffers.rb_node;
 370         struct binder_buffer *buffer;
 371         size_t buffer_size;
 372         struct rb_node *best_fit = NULL;
 373         void *has_page_addr;
 374         void *end_page_addr;
 375         size_t size, data_offsets_size;
 376         int ret;
 377
 378         if (!binder_alloc_get_vma(alloc)) {
 379                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 380                                    "%d: binder_alloc_buf, no vma\n",
 381                                    alloc->pid);
 382                 return ERR_PTR(-ESRCH);
 383         }
 384
 385         data_offsets_size = ALIGN(data_size, sizeof(void *)) +
 386                 ALIGN(offsets_size, sizeof(void *));
 387
 388         if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
 389                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 390                                 "%d: got transaction with invalid size %zd-%zd\n",
 391                                 alloc->pid, data_size, offsets_size);
 392                 return ERR_PTR(-EINVAL);
 393         }
 394         size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
 395         if (size < data_offsets_size || size < extra_buffers_size) {
 396                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 397                                 "%d: got transaction with invalid extra_buffers_size %zd\n",
 398                                 alloc->pid, extra_buffers_size);
 399                 return ERR_PTR(-EINVAL);
 400         }
 401         if (is_async &&
 402             alloc->free_async_space < size + sizeof(struct binder_buffer)) {
 403                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 404                              "%d: binder_alloc_buf size %zd failed, no async space left\n",
 405                               alloc->pid, size);
 406                 return ERR_PTR(-ENOSPC);
 407         }
 408
 409         /* Pad 0-size buffers so they get assigned unique addresses */
 410         size = max(size, sizeof(void *));
 411
 412         while (n) {
 413                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 414                 BUG_ON(!buffer->free);
 415                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
 416
 417                 if (size < buffer_size) {
 418                         best_fit = n;
 419                         n = n->rb_left;
 420                 } else if (size > buffer_size)
 421                         n = n->rb_right;
 422                 else {
 423                         best_fit = n;
 424                         break;
 425                 }
 426         }
 427         if (best_fit == NULL) {
 428                 size_t allocated_buffers = 0;
 429                 size_t largest_alloc_size = 0;
 430                 size_t total_alloc_size = 0;
 431                 size_t free_buffers = 0;
 432                 size_t largest_free_size = 0;
 433                 size_t total_free_size = 0;
 434
 435                 for (n = rb_first(&alloc->allocated_buffers); n != NULL;
 436                      n = rb_next(n)) {
 437                         buffer = rb_entry(n, struct binder_buffer, rb_node);
 438                         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 439                         allocated_buffers++;
 440                         total_alloc_size += buffer_size;
 441                         if (buffer_size > largest_alloc_size)
 442                                 largest_alloc_size = buffer_size;
 443                 }
 444                 for (n = rb_first(&alloc->free_buffers); n != NULL;
 445                      n = rb_next(n)) {
 446                         buffer = rb_entry(n, struct binder_buffer, rb_node);
 447                         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 448                         free_buffers++;
 449                         total_free_size += buffer_size;
 450                         if (buffer_size > largest_free_size)
 451                                 largest_free_size = buffer_size;
 452                 }
 453                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 454                                    "%d: binder_alloc_buf size %zd failed, no address space\n",
 455                                    alloc->pid, size);
 456                 binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 457                                    "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
 458                                    total_alloc_size, allocated_buffers,
 459                                    largest_alloc_size, total_free_size,
 460                                    free_buffers, largest_free_size);
 461                 return ERR_PTR(-ENOSPC);
 462         }
 463         if (n == NULL) {
 464                 buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
 465                 buffer_size = binder_alloc_buffer_size(alloc, buffer);
 466         }
 467
 468         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 469                      "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
 470                       alloc->pid, size, buffer, buffer_size);
 471
 472         has_page_addr =
 473                 (void *)(((uintptr_t)buffer->data + buffer_size) & PAGE_MASK);
 474         WARN_ON(n && buffer_size != size);
 475         end_page_addr =
 476                 (void *)PAGE_ALIGN((uintptr_t)buffer->data + size);
 477         if (end_page_addr > has_page_addr)
 478                 end_page_addr = has_page_addr;
 479         ret = binder_update_page_range(alloc, 1,
 480             (void *)PAGE_ALIGN((uintptr_t)buffer->data), end_page_addr);
 481         if (ret)
 482                 return ERR_PTR(ret);
 483
 484         if (buffer_size != size) {
 485                 struct binder_buffer *new_buffer;
 486
 487                 new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 488                 if (!new_buffer) {
 489                         pr_err("%s: %d failed to alloc new buffer struct\n",
 490                                __func__, alloc->pid);
 491                         goto err_alloc_buf_struct_failed;
 492                 }
 493                 new_buffer->data = (u8 *)buffer->data + size;
 494                 list_add(&new_buffer->entry, &buffer->entry);
 495                 new_buffer->free = 1;
 496                 binder_insert_free_buffer(alloc, new_buffer);
 497         }
 498
 499         rb_erase(best_fit, &alloc->free_buffers);
 500         buffer->free = 0;
 501         buffer->allow_user_free = 0;
 502         binder_insert_allocated_buffer_locked(alloc, buffer);
 503         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 504                      "%d: binder_alloc_buf size %zd got %pK\n",
 505                       alloc->pid, size, buffer);
 506         buffer->data_size = data_size;
 507         buffer->offsets_size = offsets_size;
 508         buffer->async_transaction = is_async;
 509         buffer->extra_buffers_size = extra_buffers_size;
 510         if (is_async) {
 511                 alloc->free_async_space -= size + sizeof(struct binder_buffer);
 512                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 513                              "%d: binder_alloc_buf size %zd async free %zd\n",
 514                               alloc->pid, size, alloc->free_async_space);
 515         }
 516         return buffer;
 517
 518 err_alloc_buf_struct_failed:
 519         binder_update_page_range(alloc, 0,
 520                                  (void *)PAGE_ALIGN((uintptr_t)buffer->data),
 521                                  end_page_addr);
 522         return ERR_PTR(-ENOMEM);
 523 }
 524
 525 /**
 526  * binder_alloc_new_buf() - Allocate a new binder buffer
 527  * @alloc:              binder_alloc for this proc
 528  * @data_size:          size of user data buffer
 529  * @offsets_size:       user specified buffer offset
 530  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
 531  * @is_async:           buffer for async transaction
 532  *
 533  * Allocate a new buffer given the requested sizes. Returns
 534  * the kernel version of the buffer pointer. The size allocated
 535  * is the sum of the three given sizes (each rounded up to
 536  * pointer-sized boundary)
 537  *
 538  * Return:      The allocated buffer or %NULL if error
 539  */
 540 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 541                                            size_t data_size,
 542                                            size_t offsets_size,
 543                                            size_t extra_buffers_size,
 544                                            int is_async)
 545 {
 546         struct binder_buffer *buffer;
 547
 548         mutex_lock(&alloc->mutex);
 549         buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
 550                                              extra_buffers_size, is_async);
 551         mutex_unlock(&alloc->mutex);
 552         return buffer;
 553 }
 554
 555 static void *buffer_start_page(struct binder_buffer *buffer)
 556 {
 557         return (void *)((uintptr_t)buffer->data & PAGE_MASK);
 558 }
 559
 560 static void *prev_buffer_end_page(struct binder_buffer *buffer)
 561 {
 562         return (void *)(((uintptr_t)(buffer->data) - 1) & PAGE_MASK);
 563 }
 564
 565 static void binder_delete_free_buffer(struct binder_alloc *alloc,
 566                                       struct binder_buffer *buffer)
 567 {
 568         struct binder_buffer *prev, *next = NULL;
 569         bool to_free = true;
 570         BUG_ON(alloc->buffers.next == &buffer->entry);
 571         prev = binder_buffer_prev(buffer);
 572         BUG_ON(!prev->free);
 573         if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
 574                 to_free = false;
 575                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 576                                    "%d: merge free, buffer %pK share page with %pK\n",
 577                                    alloc->pid, buffer->data, prev->data);
 578         }
 579
 580         if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 581                 next = binder_buffer_next(buffer);
 582                 if (buffer_start_page(next) == buffer_start_page(buffer)) {
 583                         to_free = false;
 584                         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 585                                            "%d: merge free, buffer %pK share page with %pK\n",
 586                                            alloc->pid,
 587                                            buffer->data,
 588                                            next->data);
 589                 }
 590         }
 591
 592         if (PAGE_ALIGNED(buffer->data)) {
 593                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 594                                    "%d: merge free, buffer start %pK is page aligned\n",
 595                                    alloc->pid, buffer->data);
 596                 to_free = false;
 597         }
 598
 599         if (to_free) {
 600                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 601                                    "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
 602                                    alloc->pid, buffer->data,
 603                                    prev->data, next ? next->data : NULL);
 604                 binder_update_page_range(alloc, 0, buffer_start_page(buffer),
 605                                          buffer_start_page(buffer) + PAGE_SIZE);
 606         }
 607         list_del(&buffer->entry);
 608         kfree(buffer);
 609 }
 610
 611 static void binder_free_buf_locked(struct binder_alloc *alloc,
 612                                    struct binder_buffer *buffer)
 613 {
 614         size_t size, buffer_size;
 615
 616         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 617
 618         size = ALIGN(buffer->data_size, sizeof(void *)) +
 619                 ALIGN(buffer->offsets_size, sizeof(void *)) +
 620                 ALIGN(buffer->extra_buffers_size, sizeof(void *));
 621
 622         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 623                      "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
 624                       alloc->pid, buffer, size, buffer_size);
 625
 626         BUG_ON(buffer->free);
 627         BUG_ON(size > buffer_size);
 628         BUG_ON(buffer->transaction != NULL);
 629         BUG_ON(buffer->data < alloc->buffer);
 630         BUG_ON(buffer->data > alloc->buffer + alloc->buffer_size);
 631
 632         if (buffer->async_transaction) {
 633                 alloc->free_async_space += buffer_size + sizeof(struct binder_buffer);
 634
 635                 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
 636                              "%d: binder_free_buf size %zd async free %zd\n",
 637                               alloc->pid, size, alloc->free_async_space);
 638         }
 639
 640         binder_update_page_range(alloc, 0,
 641                 (void *)PAGE_ALIGN((uintptr_t)buffer->data),
 642                 (void *)(((uintptr_t)buffer->data + buffer_size) & PAGE_MASK));
 643
 644         rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
 645         buffer->free = 1;
 646         if (!list_is_last(&buffer->entry, &alloc->buffers)) {
 647                 struct binder_buffer *next = binder_buffer_next(buffer);
 648
 649                 if (next->free) {
 650                         rb_erase(&next->rb_node, &alloc->free_buffers);
 651                         binder_delete_free_buffer(alloc, next);
 652                 }
 653         }
 654         if (alloc->buffers.next != &buffer->entry) {
 655                 struct binder_buffer *prev = binder_buffer_prev(buffer);
 656
 657                 if (prev->free) {
 658                         binder_delete_free_buffer(alloc, buffer);
 659                         rb_erase(&prev->rb_node, &alloc->free_buffers);
 660                         buffer = prev;
 661                 }
 662         }
 663         binder_insert_free_buffer(alloc, buffer);
 664 }
 665
 666 /**
 667  * binder_alloc_free_buf() - free a binder buffer
 668  * @alloc:      binder_alloc for this proc
 669  * @buffer:     kernel pointer to buffer
 670  *
 671  * Free the buffer allocated via binder_alloc_new_buffer()
 672  */
 673 void binder_alloc_free_buf(struct binder_alloc *alloc,
 674                             struct binder_buffer *buffer)
 675 {
 676         mutex_lock(&alloc->mutex);
 677         binder_free_buf_locked(alloc, buffer);
 678         mutex_unlock(&alloc->mutex);
 679 }
 680
 681 /**
 682  * binder_alloc_mmap_handler() - map virtual address space for proc
 683  * @alloc:      alloc structure for this proc
 684  * @vma:        vma passed to mmap()
 685  *
 686  * Called by binder_mmap() to initialize the space specified in
 687  * vma for allocating binder buffers
 688  *
 689  * Return:
 690  *      0 = success
 691  *      -EBUSY = address space already mapped
 692  *      -ENOMEM = failed to map memory to given address space
 693  */
 694 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 695                               struct vm_area_struct *vma)
 696 {
 697         int ret;
 698         struct vm_struct *area;
 699         const char *failure_string;
 700         struct binder_buffer *buffer;
 701
 702         mutex_lock(&binder_alloc_mmap_lock);
 703         if (alloc->buffer) {
 704                 ret = -EBUSY;
 705                 failure_string = "already mapped";
 706                 goto err_already_mapped;
 707         }
 708
 709         area = get_vm_area(vma->vm_end - vma->vm_start, VM_ALLOC);
 710         if (area == NULL) {
 711                 ret = -ENOMEM;
 712                 failure_string = "get_vm_area";
 713                 goto err_get_vm_area_failed;
 714         }
 715         alloc->buffer = area->addr;
 716         alloc->user_buffer_offset =
 717                 vma->vm_start - (uintptr_t)alloc->buffer;
 718         mutex_unlock(&binder_alloc_mmap_lock);
 719
 720 #ifdef CONFIG_CPU_CACHE_VIPT
 721         if (cache_is_vipt_aliasing()) {
 722                 while (CACHE_COLOUR(
 723                                 (vma->vm_start ^ (uint32_t)alloc->buffer))) {
 724                         pr_info("%s: %d %lx-%lx maps %pK bad alignment\n",
 725                                 __func__, alloc->pid, vma->vm_start,
 726                                 vma->vm_end, alloc->buffer);
 727                         vma->vm_start += PAGE_SIZE;
 728                 }
 729         }
 730 #endif
 731         alloc->pages = kcalloc((vma->vm_end - vma->vm_start) / PAGE_SIZE,
 732                                sizeof(alloc->pages[0]),
 733                                GFP_KERNEL);
 734         if (alloc->pages == NULL) {
 735                 ret = -ENOMEM;
 736                 failure_string = "alloc page array";
 737                 goto err_alloc_pages_failed;
 738         }
 739         alloc->buffer_size = vma->vm_end - vma->vm_start;
 740
 741         buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 742         if (!buffer) {
 743                 ret = -ENOMEM;
 744                 failure_string = "alloc buffer struct";
 745                 goto err_alloc_buf_struct_failed;
 746         }
 747
 748         buffer->data = alloc->buffer;
 749         list_add(&buffer->entry, &alloc->buffers);
 750         buffer->free = 1;
 751         binder_insert_free_buffer(alloc, buffer);
 752         alloc->free_async_space = alloc->buffer_size / 2;
 753         binder_alloc_set_vma(alloc, vma);
 754         mmgrab(alloc->vma_vm_mm);
 755
 756         return 0;
 757
 758 err_alloc_buf_struct_failed:
 759         kfree(alloc->pages);
 760         alloc->pages = NULL;
 761 err_alloc_pages_failed:
 762         mutex_lock(&binder_alloc_mmap_lock);
 763         vfree(alloc->buffer);
 764         alloc->buffer = NULL;
 765 err_get_vm_area_failed:
 766 err_already_mapped:
 767         mutex_unlock(&binder_alloc_mmap_lock);
 768         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
 769                            "%s: %d %lx-%lx %s failed %d\n", __func__,
 770                            alloc->pid, vma->vm_start, vma->vm_end,
 771                            failure_string, ret);
 772         return ret;
 773 }
 774
 775
 776 void binder_alloc_deferred_release(struct binder_alloc *alloc)
 777 {
 778         struct rb_node *n;
 779         int buffers, page_count;
 780         struct binder_buffer *buffer;
 781
 782         buffers = 0;
 783         mutex_lock(&alloc->mutex);
 784         BUG_ON(alloc->vma);
 785
 786         while ((n = rb_first(&alloc->allocated_buffers))) {
 787                 buffer = rb_entry(n, struct binder_buffer, rb_node);
 788
 789                 /* Transaction should already have been freed */
 790                 BUG_ON(buffer->transaction);
 791
 792                 binder_free_buf_locked(alloc, buffer);
 793                 buffers++;
 794         }
 795
 796         while (!list_empty(&alloc->buffers)) {
 797                 buffer = list_first_entry(&alloc->buffers,
 798                                           struct binder_buffer, entry);
 799                 WARN_ON(!buffer->free);
 800
 801                 list_del(&buffer->entry);
 802                 WARN_ON_ONCE(!list_empty(&alloc->buffers));
 803                 kfree(buffer);
 804         }
 805
 806         page_count = 0;
 807         if (alloc->pages) {
 808                 int i;
 809
 810                 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 811                         void *page_addr;
 812                         bool on_lru;
 813
 814                         if (!alloc->pages[i].page_ptr)
 815                                 continue;
 816
 817                         on_lru = list_lru_del(&binder_alloc_lru,
 818                                               &alloc->pages[i].lru);
 819                         page_addr = alloc->buffer + i * PAGE_SIZE;
 820                         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 821                                      "%s: %d: page %d at %pK %s\n",
 822                                      __func__, alloc->pid, i, page_addr,
 823                                      on_lru ? "on lru" : "active");
 824                         unmap_kernel_range((unsigned long)page_addr, PAGE_SIZE);
 825                         __free_page(alloc->pages[i].page_ptr);
 826                         page_count++;
 827                 }
 828                 kfree(alloc->pages);
 829                 vfree(alloc->buffer);
 830         }
 831         mutex_unlock(&alloc->mutex);
 832         if (alloc->vma_vm_mm)
 833                 mmdrop(alloc->vma_vm_mm);
 834
 835         binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
 836                      "%s: %d buffers %d, pages %d\n",
 837                      __func__, alloc->pid, buffers, page_count);
 838 }
 839
 840 static void print_binder_buffer(struct seq_file *m, const char *prefix,
 841                                 struct binder_buffer *buffer)
 842 {
 843         seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
 844                    prefix, buffer->debug_id, buffer->data,
 845                    buffer->data_size, buffer->offsets_size,
 846                    buffer->extra_buffers_size,
 847                    buffer->transaction ? "active" : "delivered");
 848 }
 849
 850 /**
 851  * binder_alloc_print_allocated() - print buffer info
 852  * @m:     seq_file for output via seq_printf()
 853  * @alloc: binder_alloc for this proc
 854  *
 855  * Prints information about every buffer associated with
 856  * the binder_alloc state to the given seq_file
 857  */
 858 void binder_alloc_print_allocated(struct seq_file *m,
 859                                   struct binder_alloc *alloc)
 860 {
 861         struct rb_node *n;
 862
 863         mutex_lock(&alloc->mutex);
 864         for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 865                 print_binder_buffer(m, "  buffer",
 866                                     rb_entry(n, struct binder_buffer, rb_node));
 867         mutex_unlock(&alloc->mutex);
 868 }
 869
 870 /**
 871  * binder_alloc_print_pages() - print page usage
 872  * @m:     seq_file for output via seq_printf()
 873  * @alloc: binder_alloc for this proc
 874  */
 875 void binder_alloc_print_pages(struct seq_file *m,
 876                               struct binder_alloc *alloc)
 877 {
 878         struct binder_lru_page *page;
 879         int i;
 880         int active = 0;
 881         int lru = 0;
 882         int free = 0;
 883
 884         mutex_lock(&alloc->mutex);
 885         /*
 886          * Make sure the binder_alloc is fully initialized, otherwise we might
 887          * read inconsistent state.
 888          */
 889         if (binder_alloc_get_vma(alloc) != NULL) {
 890                 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 891                         page = &alloc->pages[i];
 892                         if (!page->page_ptr)
 893                                 free++;
 894                         else if (list_empty(&page->lru))
 895                                 active++;
 896                         else
 897                                 lru++;
 898                 }
 899         }
 900         mutex_unlock(&alloc->mutex);
 901         seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
 902         seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
 903 }
 904
 905 /**
 906  * binder_alloc_get_allocated_count() - return count of buffers
 907  * @alloc: binder_alloc for this proc
 908  *
 909  * Return: count of allocated buffers
 910  */
 911 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
 912 {
 913         struct rb_node *n;
 914         int count = 0;
 915
 916         mutex_lock(&alloc->mutex);
 917         for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
 918                 count++;
 919         mutex_unlock(&alloc->mutex);
 920         return count;
 921 }
 922
 923
 924 /**
 925  * binder_alloc_vma_close() - invalidate address space
 926  * @alloc: binder_alloc for this proc
 927  *
 928  * Called from binder_vma_close() when releasing address space.
 929  * Clears alloc->vma to prevent new incoming transactions from
 930  * allocating more buffers.
 931  */
 932 void binder_alloc_vma_close(struct binder_alloc *alloc)
 933 {
 934         binder_alloc_set_vma(alloc, NULL);
 935 }
 936
 937 /**
 938  * binder_alloc_free_page() - shrinker callback to free pages
 939  * @item:   item to free
 940  * @lock:   lock protecting the item
 941  * @cb_arg: callback argument
 942  *
 943  * Called from list_lru_walk() in binder_shrink_scan() to free
 944  * up pages when the system is under memory pressure.
 945  */
 946 enum lru_status binder_alloc_free_page(struct list_head *item,
 947                                        struct list_lru_one *lru,
 948                                        spinlock_t *lock,
 949                                        void *cb_arg)
 950 {
 951         struct mm_struct *mm = NULL;
 952         struct binder_lru_page *page = container_of(item,
 953                                                     struct binder_lru_page,
 954                                                     lru);
 955         struct binder_alloc *alloc;
 956         uintptr_t page_addr;
 957         size_t index;
 958         struct vm_area_struct *vma;
 959
 960         alloc = page->alloc;
 961         if (!mutex_trylock(&alloc->mutex))
 962                 goto err_get_alloc_mutex_failed;
 963
 964         if (!page->page_ptr)
 965                 goto err_page_already_freed;
 966
 967         index = page - alloc->pages;
 968         page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
 969
 970         mm = alloc->vma_vm_mm;
 971         if (!mmget_not_zero(mm))
 972                 goto err_mmget;
 973         if (!down_read_trylock(&mm->mmap_sem))
 974                 goto err_down_read_mmap_sem_failed;
 975         vma = binder_alloc_get_vma(alloc);
 976
 977         list_lru_isolate(lru, item);
 978         spin_unlock(lock);
 979
 980         if (vma) {
 981                 trace_binder_unmap_user_start(alloc, index);
 982
 983                 zap_page_range(vma,
 984                                page_addr + alloc->user_buffer_offset,
 985                                PAGE_SIZE);
 986
 987                 trace_binder_unmap_user_end(alloc, index);
 988         }
 989         up_read(&mm->mmap_sem);
 990         mmput_async(mm);
 991
 992         trace_binder_unmap_kernel_start(alloc, index);
 993
 994         unmap_kernel_range(page_addr, PAGE_SIZE);
 995         __free_page(page->page_ptr);
 996         page->page_ptr = NULL;
 997
 998         trace_binder_unmap_kernel_end(alloc, index);
 999
1000         spin_lock(lock);
1001         mutex_unlock(&alloc->mutex);
1002         return LRU_REMOVED_RETRY;
1003
1004 err_down_read_mmap_sem_failed:
1005         mmput_async(mm);
1006 err_mmget:
1007 err_page_already_freed:
1008         mutex_unlock(&alloc->mutex);
1009 err_get_alloc_mutex_failed:
1010         return LRU_SKIP;
1011 }
1012
1013 static unsigned long
1014 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
1015 {
1016         unsigned long ret = list_lru_count(&binder_alloc_lru);
1017         return ret;
1018 }
1019
1020 static unsigned long
1021 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
1022 {
1023         unsigned long ret;
1024
1025         ret = list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
1026                             NULL, sc->nr_to_scan);
1027         return ret;
1028 }
1029
1030 static struct shrinker binder_shrinker = {
1031         .count_objects = binder_shrink_count,
1032         .scan_objects = binder_shrink_scan,
1033         .seeks = DEFAULT_SEEKS,
1034 };
1035
1036 /**
1037  * binder_alloc_init() - called by binder_open() for per-proc initialization
1038  * @alloc: binder_alloc for this proc
1039  *
1040  * Called from binder_open() to initialize binder_alloc fields for
1041  * new binder proc
1042  */
1043 void binder_alloc_init(struct binder_alloc *alloc)
1044 {
1045         alloc->pid = current->group_leader->pid;
1046         mutex_init(&alloc->mutex);
1047         INIT_LIST_HEAD(&alloc->buffers);
1048 }
1049
1050 int binder_alloc_shrinker_init(void)
1051 {
1052         int ret = list_lru_init(&binder_alloc_lru);
1053
1054         if (ret == 0) {
1055                 ret = register_shrinker(&binder_shrinker);
1056                 if (ret)
1057                         list_lru_destroy(&binder_alloc_lru);
1058         }
1059         return ret;
1060 }