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