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