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