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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /* binder_alloc.c
  *
  * Android IPC Subsystem
  *
  * Copyright (C) 2007-2017 Google, Inc.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/list.h>
 #include <linux/sched/mm.h>
 #include <linux/module.h>
 #include <linux/rtmutex.h>
 #include <linux/rbtree.h>
 #include <linux/seq_file.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/list_lru.h>
 #include <linux/ratelimit.h>
 #include <asm/cacheflush.h>
 #include <linux/uaccess.h>
 #include <linux/highmem.h>
 #include <linux/sizes.h>
 #include "binder_alloc.h"
 #include "binder_trace.h"
 
 struct list_lru binder_alloc_lru;
 
 static DEFINE_MUTEX(binder_alloc_mmap_lock);
 
 enum {
     BINDER_DEBUG_USER_ERROR             = 1U << 0,
     BINDER_DEBUG_OPEN_CLOSE             = 1U << 1,
     BINDER_DEBUG_BUFFER_ALLOC           = 1U << 2,
     BINDER_DEBUG_BUFFER_ALLOC_ASYNC     = 1U << 3,
 };
 static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR;
 
 module_param_named(debug_mask, binder_alloc_debug_mask,
            uint, 0644);
 
 #define binder_alloc_debug(mask, x...) \
     do { \
         if (binder_alloc_debug_mask & mask) \
             pr_info_ratelimited(x); \
     } while (0)
 
 static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
 {
     return list_entry(buffer->entry.next, struct binder_buffer, entry);
 }
 
 static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
 {
     return list_entry(buffer->entry.prev, struct binder_buffer, entry);
 }
 
 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
                        struct binder_buffer *buffer)
 {
     if (list_is_last(&buffer->entry, &alloc->buffers))
         return alloc->buffer + alloc->buffer_size - buffer->user_data;
     return binder_buffer_next(buffer)->user_data - buffer->user_data;
 }
 
 static void binder_insert_free_buffer(struct binder_alloc *alloc,
                       struct binder_buffer *new_buffer)
 {
     struct rb_node **p = &alloc->free_buffers.rb_node;
     struct rb_node *parent = NULL;
     struct binder_buffer *buffer;
     size_t buffer_size;
     size_t new_buffer_size;
 
     BUG_ON(!new_buffer->free);
 
     new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer);
 
     binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
              "%d: add free buffer, size %zd, at %pK\n",
               alloc->pid, new_buffer_size, new_buffer);
 
     while (*p) {
         parent = *p;
         buffer = rb_entry(parent, struct binder_buffer, rb_node);
         BUG_ON(!buffer->free);
 
         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 
         if (new_buffer_size < buffer_size)
             p = &parent->rb_left;
         else
             p = &parent->rb_right;
     }
     rb_link_node(&new_buffer->rb_node, parent, p);
     rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers);
 }
 
 static void binder_insert_allocated_buffer_locked(
         struct binder_alloc *alloc, struct binder_buffer *new_buffer)
 {
     struct rb_node **p = &alloc->allocated_buffers.rb_node;
     struct rb_node *parent = NULL;
     struct binder_buffer *buffer;
 
     BUG_ON(new_buffer->free);
 
     while (*p) {
         parent = *p;
         buffer = rb_entry(parent, struct binder_buffer, rb_node);
         BUG_ON(buffer->free);
 
         if (new_buffer->user_data < buffer->user_data)
             p = &parent->rb_left;
         else if (new_buffer->user_data > buffer->user_data)
             p = &parent->rb_right;
         else
             BUG();
     }
     rb_link_node(&new_buffer->rb_node, parent, p);
     rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers);
 }
 
 static struct binder_buffer *binder_alloc_prepare_to_free_locked(
         struct binder_alloc *alloc,
         uintptr_t user_ptr)
 {
     struct rb_node *n = alloc->allocated_buffers.rb_node;
     struct binder_buffer *buffer;
     void __user *uptr;
 
     uptr = (void __user *)user_ptr;
 
     while (n) {
         buffer = rb_entry(n, struct binder_buffer, rb_node);
         BUG_ON(buffer->free);
 
         if (uptr < buffer->user_data)
             n = n->rb_left;
         else if (uptr > buffer->user_data)
             n = n->rb_right;
         else {
             /*
              * Guard against user threads attempting to
              * free the buffer when in use by kernel or
              * after it's already been freed.
              */
             if (!buffer->allow_user_free)
                 return ERR_PTR(-EPERM);
             buffer->allow_user_free = 0;
             return buffer;
         }
     }
     return NULL;
 }
 
 /**
  * binder_alloc_prepare_to_free() - get buffer given user ptr
  * @alloc:  binder_alloc for this proc
  * @user_ptr:   User pointer to buffer data
  *
  * Validate userspace pointer to buffer data and return buffer corresponding to
  * that user pointer. Search the rb tree for buffer that matches user data
  * pointer.
  *
  * Return:  Pointer to buffer or NULL
  */
 struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
                            uintptr_t user_ptr)
 {
     struct binder_buffer *buffer;
 
     mutex_lock(&alloc->mutex);
     buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
     mutex_unlock(&alloc->mutex);
     return buffer;
 }
 
 static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
                     void __user *start, void __user *end)
 {
     void __user *page_addr;
     unsigned long user_page_addr;
     struct binder_lru_page *page;
     struct vm_area_struct *vma = NULL;
     struct mm_struct *mm = NULL;
     bool need_mm = false;
 
     binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
              "%d: %s pages %pK-%pK\n", alloc->pid,
              allocate ? "allocate" : "free", start, end);
 
     if (end <= start)
         return 0;
 
     trace_binder_update_page_range(alloc, allocate, start, end);
 
     if (allocate == 0)
         goto free_range;
 
     for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
         page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
         if (!page->page_ptr) {
             need_mm = true;
             break;
         }
     }
 
     if (need_mm && mmget_not_zero(alloc->vma_vm_mm))
         mm = alloc->vma_vm_mm;
 
     if (mm) {
         mmap_read_lock(mm);
         vma = vma_lookup(mm, alloc->vma_addr);
     }
 
     if (!vma && need_mm) {
         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
                    "%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
                    alloc->pid);
         goto err_no_vma;
     }
 
     for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
         int ret;
         bool on_lru;
         size_t index;
 
         index = (page_addr - alloc->buffer) / PAGE_SIZE;
         page = &alloc->pages[index];
 
         if (page->page_ptr) {
             trace_binder_alloc_lru_start(alloc, index);
 
             on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
             WARN_ON(!on_lru);
 
             trace_binder_alloc_lru_end(alloc, index);
             continue;
         }
 
         if (WARN_ON(!vma))
             goto err_page_ptr_cleared;
 
         trace_binder_alloc_page_start(alloc, index);
         page->page_ptr = alloc_page(GFP_KERNEL |
                         __GFP_HIGHMEM |
                         __GFP_ZERO);
         if (!page->page_ptr) {
             pr_err("%d: binder_alloc_buf failed for page at %pK\n",
                 alloc->pid, page_addr);
             goto err_alloc_page_failed;
         }
         page->alloc = alloc;
         INIT_LIST_HEAD(&page->lru);
 
         user_page_addr = (uintptr_t)page_addr;
         ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
         if (ret) {
             pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
                    alloc->pid, user_page_addr);
             goto err_vm_insert_page_failed;
         }
 
         if (index + 1 > alloc->pages_high)
             alloc->pages_high = index + 1;
 
         trace_binder_alloc_page_end(alloc, index);
     }
     if (mm) {
         mmap_read_unlock(mm);
         mmput(mm);
     }
     return 0;
 
 free_range:
     for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) {
         bool ret;
         size_t index;
 
         index = (page_addr - alloc->buffer) / PAGE_SIZE;
         page = &alloc->pages[index];
 
         trace_binder_free_lru_start(alloc, index);
 
         ret = list_lru_add(&binder_alloc_lru, &page->lru);
         WARN_ON(!ret);
 
         trace_binder_free_lru_end(alloc, index);
         if (page_addr == start)
             break;
         continue;
 
 err_vm_insert_page_failed:
         __free_page(page->page_ptr);
         page->page_ptr = NULL;
 err_alloc_page_failed:
 err_page_ptr_cleared:
         if (page_addr == start)
             break;
     }
 err_no_vma:
     if (mm) {
         mmap_read_unlock(mm);
         mmput(mm);
     }
     return vma ? -ENOMEM : -ESRCH;
 }
 
 
 static inline void binder_alloc_set_vma(struct binder_alloc *alloc,
         struct vm_area_struct *vma)
 {
     unsigned long vm_start = 0;
 
     /*
      * Allow clearing the vma with holding just the read lock to allow
      * munmapping downgrade of the write lock before freeing and closing the
      * file using binder_alloc_vma_close().
      */
     if (vma) {
         vm_start = vma->vm_start;
         mmap_assert_write_locked(alloc->vma_vm_mm);
     } else {
         mmap_assert_locked(alloc->vma_vm_mm);
     }
 
     alloc->vma_addr = vm_start;
 }
 
 static inline struct vm_area_struct *binder_alloc_get_vma(
         struct binder_alloc *alloc)
 {
     struct vm_area_struct *vma = NULL;
 
     if (alloc->vma_addr)
         vma = vma_lookup(alloc->vma_vm_mm, alloc->vma_addr);
 
     return vma;
 }
 
 static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid)
 {
     /*
      * Find the amount and size of buffers allocated by the current caller;
      * The idea is that once we cross the threshold, whoever is responsible
      * for the low async space is likely to try to send another async txn,
      * and at some point we'll catch them in the act. This is more efficient
      * than keeping a map per pid.
      */
     struct rb_node *n;
     struct binder_buffer *buffer;
     size_t total_alloc_size = 0;
     size_t num_buffers = 0;
 
     for (n = rb_first(&alloc->allocated_buffers); n != NULL;
          n = rb_next(n)) {
         buffer = rb_entry(n, struct binder_buffer, rb_node);
         if (buffer->pid != pid)
             continue;
         if (!buffer->async_transaction)
             continue;
         total_alloc_size += binder_alloc_buffer_size(alloc, buffer)
             + sizeof(struct binder_buffer);
         num_buffers++;
     }
 
     /*
      * Warn if this pid has more than 50 transactions, or more than 50% of
      * async space (which is 25% of total buffer size). Oneway spam is only
      * detected when the threshold is exceeded.
      */
     if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) {
         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
                  "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n",
                   alloc->pid, pid, num_buffers, total_alloc_size);
         if (!alloc->oneway_spam_detected) {
             alloc->oneway_spam_detected = true;
             return true;
         }
     }
     return false;
 }
 
 static struct binder_buffer *binder_alloc_new_buf_locked(
                 struct binder_alloc *alloc,
                 size_t data_size,
                 size_t offsets_size,
                 size_t extra_buffers_size,
                 int is_async,
                 int pid)
 {
     struct rb_node *n = alloc->free_buffers.rb_node;
     struct binder_buffer *buffer;
     size_t buffer_size;
     struct rb_node *best_fit = NULL;
     void __user *has_page_addr;
     void __user *end_page_addr;
     size_t size, data_offsets_size;
     int ret;
 
     mmap_read_lock(alloc->vma_vm_mm);
     if (!binder_alloc_get_vma(alloc)) {
         mmap_read_unlock(alloc->vma_vm_mm);
         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
                    "%d: binder_alloc_buf, no vma\n",
                    alloc->pid);
         return ERR_PTR(-ESRCH);
     }
     mmap_read_unlock(alloc->vma_vm_mm);
 
     data_offsets_size = ALIGN(data_size, sizeof(void *)) +
         ALIGN(offsets_size, sizeof(void *));
 
     if (data_offsets_size < data_size || data_offsets_size < offsets_size) {
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                 "%d: got transaction with invalid size %zd-%zd\n",
                 alloc->pid, data_size, offsets_size);
         return ERR_PTR(-EINVAL);
     }
     size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *));
     if (size < data_offsets_size || size < extra_buffers_size) {
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                 "%d: got transaction with invalid extra_buffers_size %zd\n",
                 alloc->pid, extra_buffers_size);
         return ERR_PTR(-EINVAL);
     }
     if (is_async &&
         alloc->free_async_space < size + sizeof(struct binder_buffer)) {
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                  "%d: binder_alloc_buf size %zd failed, no async space left\n",
                   alloc->pid, size);
         return ERR_PTR(-ENOSPC);
     }
 
     /* Pad 0-size buffers so they get assigned unique addresses */
     size = max(size, sizeof(void *));
 
     while (n) {
         buffer = rb_entry(n, struct binder_buffer, rb_node);
         BUG_ON(!buffer->free);
         buffer_size = binder_alloc_buffer_size(alloc, buffer);
 
         if (size < buffer_size) {
             best_fit = n;
             n = n->rb_left;
         } else if (size > buffer_size)
             n = n->rb_right;
         else {
             best_fit = n;
             break;
         }
     }
     if (best_fit == NULL) {
         size_t allocated_buffers = 0;
         size_t largest_alloc_size = 0;
         size_t total_alloc_size = 0;
         size_t free_buffers = 0;
         size_t largest_free_size = 0;
         size_t total_free_size = 0;
 
         for (n = rb_first(&alloc->allocated_buffers); n != NULL;
              n = rb_next(n)) {
             buffer = rb_entry(n, struct binder_buffer, rb_node);
             buffer_size = binder_alloc_buffer_size(alloc, buffer);
             allocated_buffers++;
             total_alloc_size += buffer_size;
             if (buffer_size > largest_alloc_size)
                 largest_alloc_size = buffer_size;
         }
         for (n = rb_first(&alloc->free_buffers); n != NULL;
              n = rb_next(n)) {
             buffer = rb_entry(n, struct binder_buffer, rb_node);
             buffer_size = binder_alloc_buffer_size(alloc, buffer);
             free_buffers++;
             total_free_size += buffer_size;
             if (buffer_size > largest_free_size)
                 largest_free_size = buffer_size;
         }
         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
                    "%d: binder_alloc_buf size %zd failed, no address space\n",
                    alloc->pid, size);
         binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
                    "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n",
                    total_alloc_size, allocated_buffers,
                    largest_alloc_size, total_free_size,
                    free_buffers, largest_free_size);
         return ERR_PTR(-ENOSPC);
     }
     if (n == NULL) {
         buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
         buffer_size = binder_alloc_buffer_size(alloc, buffer);
     }
 
     binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
              "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n",
               alloc->pid, size, buffer, buffer_size);
 
     has_page_addr = (void __user *)
         (((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK);
     WARN_ON(n && buffer_size != size);
     end_page_addr =
         (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
     if (end_page_addr > has_page_addr)
         end_page_addr = has_page_addr;
     ret = binder_update_page_range(alloc, 1, (void __user *)
         PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr);
     if (ret)
         return ERR_PTR(ret);
 
     if (buffer_size != size) {
         struct binder_buffer *new_buffer;
 
         new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
         if (!new_buffer) {
             pr_err("%s: %d failed to alloc new buffer struct\n",
                    __func__, alloc->pid);
             goto err_alloc_buf_struct_failed;
         }
         new_buffer->user_data = (u8 __user *)buffer->user_data + size;
         list_add(&new_buffer->entry, &buffer->entry);
         new_buffer->free = 1;
         binder_insert_free_buffer(alloc, new_buffer);
     }
 
     rb_erase(best_fit, &alloc->free_buffers);
     buffer->free = 0;
     buffer->allow_user_free = 0;
     binder_insert_allocated_buffer_locked(alloc, buffer);
     binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
              "%d: binder_alloc_buf size %zd got %pK\n",
               alloc->pid, size, buffer);
     buffer->data_size = data_size;
     buffer->offsets_size = offsets_size;
     buffer->async_transaction = is_async;
     buffer->extra_buffers_size = extra_buffers_size;
     buffer->pid = pid;
     buffer->oneway_spam_suspect = false;
     if (is_async) {
         alloc->free_async_space -= size + sizeof(struct binder_buffer);
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
                  "%d: binder_alloc_buf size %zd async free %zd\n",
                   alloc->pid, size, alloc->free_async_space);
         if (alloc->free_async_space < alloc->buffer_size / 10) {
             /*
              * Start detecting spammers once we have less than 20%
              * of async space left (which is less than 10% of total
              * buffer size).
              */
             buffer->oneway_spam_suspect = debug_low_async_space_locked(alloc, pid);
         } else {
             alloc->oneway_spam_detected = false;
         }
     }
     return buffer;
 
 err_alloc_buf_struct_failed:
     binder_update_page_range(alloc, 0, (void __user *)
                  PAGE_ALIGN((uintptr_t)buffer->user_data),
                  end_page_addr);
     return ERR_PTR(-ENOMEM);
 }
 
 /**
  * binder_alloc_new_buf() - Allocate a new binder buffer
  * @alloc:              binder_alloc for this proc
  * @data_size:          size of user data buffer
  * @offsets_size:       user specified buffer offset
  * @extra_buffers_size: size of extra space for meta-data (eg, security context)
  * @is_async:           buffer for async transaction
  * @pid:                pid to attribute allocation to (used for debugging)
  *
  * Allocate a new buffer given the requested sizes. Returns
  * the kernel version of the buffer pointer. The size allocated
  * is the sum of the three given sizes (each rounded up to
  * pointer-sized boundary)
  *
  * Return:  The allocated buffer or %NULL if error
  */
 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
                        size_t data_size,
                        size_t offsets_size,
                        size_t extra_buffers_size,
                        int is_async,
                        int pid)
 {
     struct binder_buffer *buffer;
 
     mutex_lock(&alloc->mutex);
     buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size,
                          extra_buffers_size, is_async, pid);
     mutex_unlock(&alloc->mutex);
     return buffer;
 }
 
 static void __user *buffer_start_page(struct binder_buffer *buffer)
 {
     return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK);
 }
 
 static void __user *prev_buffer_end_page(struct binder_buffer *buffer)
 {
     return (void __user *)
         (((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK);
 }
 
 static void binder_delete_free_buffer(struct binder_alloc *alloc,
                       struct binder_buffer *buffer)
 {
     struct binder_buffer *prev, *next = NULL;
     bool to_free = true;
 
     BUG_ON(alloc->buffers.next == &buffer->entry);
     prev = binder_buffer_prev(buffer);
     BUG_ON(!prev->free);
     if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
         to_free = false;
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                    "%d: merge free, buffer %pK share page with %pK\n",
                    alloc->pid, buffer->user_data,
                    prev->user_data);
     }
 
     if (!list_is_last(&buffer->entry, &alloc->buffers)) {
         next = binder_buffer_next(buffer);
         if (buffer_start_page(next) == buffer_start_page(buffer)) {
             to_free = false;
             binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                        "%d: merge free, buffer %pK share page with %pK\n",
                        alloc->pid,
                        buffer->user_data,
                        next->user_data);
         }
     }
 
     if (PAGE_ALIGNED(buffer->user_data)) {
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                    "%d: merge free, buffer start %pK is page aligned\n",
                    alloc->pid, buffer->user_data);
         to_free = false;
     }
 
     if (to_free) {
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                    "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
                    alloc->pid, buffer->user_data,
                    prev->user_data,
                    next ? next->user_data : NULL);
         binder_update_page_range(alloc, 0, buffer_start_page(buffer),
                      buffer_start_page(buffer) + PAGE_SIZE);
     }
     list_del(&buffer->entry);
     kfree(buffer);
 }
 
 static void binder_free_buf_locked(struct binder_alloc *alloc,
                    struct binder_buffer *buffer)
 {
     size_t size, buffer_size;
 
     buffer_size = binder_alloc_buffer_size(alloc, buffer);
 
     size = ALIGN(buffer->data_size, sizeof(void *)) +
         ALIGN(buffer->offsets_size, sizeof(void *)) +
         ALIGN(buffer->extra_buffers_size, sizeof(void *));
 
     binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
              "%d: binder_free_buf %pK size %zd buffer_size %zd\n",
               alloc->pid, buffer, size, buffer_size);
 
     BUG_ON(buffer->free);
     BUG_ON(size > buffer_size);
     BUG_ON(buffer->transaction != NULL);
     BUG_ON(buffer->user_data < alloc->buffer);
     BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size);
 
     if (buffer->async_transaction) {
         alloc->free_async_space += buffer_size + sizeof(struct binder_buffer);
 
         binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC,
                  "%d: binder_free_buf size %zd async free %zd\n",
                   alloc->pid, size, alloc->free_async_space);
     }
 
     binder_update_page_range(alloc, 0,
         (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data),
         (void __user *)(((uintptr_t)
               buffer->user_data + buffer_size) & PAGE_MASK));
 
     rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
     buffer->free = 1;
     if (!list_is_last(&buffer->entry, &alloc->buffers)) {
         struct binder_buffer *next = binder_buffer_next(buffer);
 
         if (next->free) {
             rb_erase(&next->rb_node, &alloc->free_buffers);
             binder_delete_free_buffer(alloc, next);
         }
     }
     if (alloc->buffers.next != &buffer->entry) {
         struct binder_buffer *prev = binder_buffer_prev(buffer);
 
         if (prev->free) {
             binder_delete_free_buffer(alloc, buffer);
             rb_erase(&prev->rb_node, &alloc->free_buffers);
             buffer = prev;
         }
     }
     binder_insert_free_buffer(alloc, buffer);
 }
 
 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
                    struct binder_buffer *buffer);
 /**
  * binder_alloc_free_buf() - free a binder buffer
  * @alloc:  binder_alloc for this proc
  * @buffer: kernel pointer to buffer
  *
  * Free the buffer allocated via binder_alloc_new_buf()
  */
 void binder_alloc_free_buf(struct binder_alloc *alloc,
                 struct binder_buffer *buffer)
 {
     /*
      * We could eliminate the call to binder_alloc_clear_buf()
      * from binder_alloc_deferred_release() by moving this to
      * binder_alloc_free_buf_locked(). However, that could
      * increase contention for the alloc mutex if clear_on_free
      * is used frequently for large buffers. The mutex is not
      * needed for correctness here.
      */
     if (buffer->clear_on_free) {
         binder_alloc_clear_buf(alloc, buffer);
         buffer->clear_on_free = false;
     }
     mutex_lock(&alloc->mutex);
     binder_free_buf_locked(alloc, buffer);
     mutex_unlock(&alloc->mutex);
 }
 
 /**
  * binder_alloc_mmap_handler() - map virtual address space for proc
  * @alloc:  alloc structure for this proc
  * @vma:    vma passed to mmap()
  *
  * Called by binder_mmap() to initialize the space specified in
  * vma for allocating binder buffers
  *
  * Return:
  *      0 = success
  *      -EBUSY = address space already mapped
  *      -ENOMEM = failed to map memory to given address space
  */
 int binder_alloc_mmap_handler(struct binder_alloc *alloc,
                   struct vm_area_struct *vma)
 {
     int ret;
     const char *failure_string;
     struct binder_buffer *buffer;
 
     mutex_lock(&binder_alloc_mmap_lock);
     if (alloc->buffer_size) {
         ret = -EBUSY;
         failure_string = "already mapped";
         goto err_already_mapped;
     }
     alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start,
                    SZ_4M);
     mutex_unlock(&binder_alloc_mmap_lock);
 
     alloc->buffer = (void __user *)vma->vm_start;
 
     alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE,
                    sizeof(alloc->pages[0]),
                    GFP_KERNEL);
     if (alloc->pages == NULL) {
         ret = -ENOMEM;
         failure_string = "alloc page array";
         goto err_alloc_pages_failed;
     }
 
     buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
     if (!buffer) {
         ret = -ENOMEM;
         failure_string = "alloc buffer struct";
         goto err_alloc_buf_struct_failed;
     }
 
     buffer->user_data = alloc->buffer;
     list_add(&buffer->entry, &alloc->buffers);
     buffer->free = 1;
     binder_insert_free_buffer(alloc, buffer);
     alloc->free_async_space = alloc->buffer_size / 2;
     binder_alloc_set_vma(alloc, vma);
 
     return 0;
 
 err_alloc_buf_struct_failed:
     kfree(alloc->pages);
     alloc->pages = NULL;
 err_alloc_pages_failed:
     alloc->buffer = NULL;
     mutex_lock(&binder_alloc_mmap_lock);
     alloc->buffer_size = 0;
 err_already_mapped:
     mutex_unlock(&binder_alloc_mmap_lock);
     binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
                "%s: %d %lx-%lx %s failed %d\n", __func__,
                alloc->pid, vma->vm_start, vma->vm_end,
                failure_string, ret);
     return ret;
 }
 
 
 void binder_alloc_deferred_release(struct binder_alloc *alloc)
 {
     struct rb_node *n;
     int buffers, page_count;
     struct binder_buffer *buffer;
 
     buffers = 0;
     mutex_lock(&alloc->mutex);
     BUG_ON(alloc->vma_addr &&
            vma_lookup(alloc->vma_vm_mm, alloc->vma_addr));
 
     while ((n = rb_first(&alloc->allocated_buffers))) {
         buffer = rb_entry(n, struct binder_buffer, rb_node);
 
         /* Transaction should already have been freed */
         BUG_ON(buffer->transaction);
 
         if (buffer->clear_on_free) {
             binder_alloc_clear_buf(alloc, buffer);
             buffer->clear_on_free = false;
         }
         binder_free_buf_locked(alloc, buffer);
         buffers++;
     }
 
     while (!list_empty(&alloc->buffers)) {
         buffer = list_first_entry(&alloc->buffers,
                       struct binder_buffer, entry);
         WARN_ON(!buffer->free);
 
         list_del(&buffer->entry);
         WARN_ON_ONCE(!list_empty(&alloc->buffers));
         kfree(buffer);
     }
 
     page_count = 0;
     if (alloc->pages) {
         int i;
 
         for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
             void __user *page_addr;
             bool on_lru;
 
             if (!alloc->pages[i].page_ptr)
                 continue;
 
             on_lru = list_lru_del(&binder_alloc_lru,
                           &alloc->pages[i].lru);
             page_addr = alloc->buffer + i * PAGE_SIZE;
             binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
                      "%s: %d: page %d at %pK %s\n",
                      __func__, alloc->pid, i, page_addr,
                      on_lru ? "on lru" : "active");
             __free_page(alloc->pages[i].page_ptr);
             page_count++;
         }
         kfree(alloc->pages);
     }
     mutex_unlock(&alloc->mutex);
     if (alloc->vma_vm_mm)
         mmdrop(alloc->vma_vm_mm);
 
     binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
              "%s: %d buffers %d, pages %d\n",
              __func__, alloc->pid, buffers, page_count);
 }
 
 static void print_binder_buffer(struct seq_file *m, const char *prefix,
                 struct binder_buffer *buffer)
 {
     seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n",
            prefix, buffer->debug_id, buffer->user_data,
            buffer->data_size, buffer->offsets_size,
            buffer->extra_buffers_size,
            buffer->transaction ? "active" : "delivered");
 }
 
 /**
  * binder_alloc_print_allocated() - print buffer info
  * @m:     seq_file for output via seq_printf()
  * @alloc: binder_alloc for this proc
  *
  * Prints information about every buffer associated with
  * the binder_alloc state to the given seq_file
  */
 void binder_alloc_print_allocated(struct seq_file *m,
                   struct binder_alloc *alloc)
 {
     struct rb_node *n;
 
     mutex_lock(&alloc->mutex);
     for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
         print_binder_buffer(m, "  buffer",
                     rb_entry(n, struct binder_buffer, rb_node));
     mutex_unlock(&alloc->mutex);
 }
 
 /**
  * binder_alloc_print_pages() - print page usage
  * @m:     seq_file for output via seq_printf()
  * @alloc: binder_alloc for this proc
  */
 void binder_alloc_print_pages(struct seq_file *m,
                   struct binder_alloc *alloc)
 {
     struct binder_lru_page *page;
     int i;
     int active = 0;
     int lru = 0;
     int free = 0;
 
     mutex_lock(&alloc->mutex);
     /*
      * Make sure the binder_alloc is fully initialized, otherwise we might
      * read inconsistent state.
      */
 
     mmap_read_lock(alloc->vma_vm_mm);
     if (binder_alloc_get_vma(alloc) == NULL) {
         mmap_read_unlock(alloc->vma_vm_mm);
         goto uninitialized;
     }
 
     mmap_read_unlock(alloc->vma_vm_mm);
     for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
         page = &alloc->pages[i];
         if (!page->page_ptr)
             free++;
         else if (list_empty(&page->lru))
             active++;
         else
             lru++;
     }
 
 uninitialized:
     mutex_unlock(&alloc->mutex);
     seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
     seq_printf(m, "  pages high watermark: %zu\n", alloc->pages_high);
 }
 
 /**
  * binder_alloc_get_allocated_count() - return count of buffers
  * @alloc: binder_alloc for this proc
  *
  * Return: count of allocated buffers
  */
 int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
 {
     struct rb_node *n;
     int count = 0;
 
     mutex_lock(&alloc->mutex);
     for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
         count++;
     mutex_unlock(&alloc->mutex);
     return count;
 }
 
 
 /**
  * binder_alloc_vma_close() - invalidate address space
  * @alloc: binder_alloc for this proc
  *
  * Called from binder_vma_close() when releasing address space.
  * Clears alloc->vma to prevent new incoming transactions from
  * allocating more buffers.
  */
 void binder_alloc_vma_close(struct binder_alloc *alloc)
 {
     binder_alloc_set_vma(alloc, NULL);
 }
 
 /**
  * binder_alloc_free_page() - shrinker callback to free pages
  * @item:   item to free
  * @lock:   lock protecting the item
  * @cb_arg: callback argument
  *
  * Called from list_lru_walk() in binder_shrink_scan() to free
  * up pages when the system is under memory pressure.
  */
 enum lru_status binder_alloc_free_page(struct list_head *item,
                        struct list_lru_one *lru,
                        spinlock_t *lock,
                        void *cb_arg)
     __must_hold(lock)
 {
     struct mm_struct *mm = NULL;
     struct binder_lru_page *page = container_of(item,
                             struct binder_lru_page,
                             lru);
     struct binder_alloc *alloc;
     uintptr_t page_addr;
     size_t index;
     struct vm_area_struct *vma;
 
     alloc = page->alloc;
     if (!mutex_trylock(&alloc->mutex))
         goto err_get_alloc_mutex_failed;
 
     if (!page->page_ptr)
         goto err_page_already_freed;
 
     index = page - alloc->pages;
     page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
 
     mm = alloc->vma_vm_mm;
     if (!mmget_not_zero(mm))
         goto err_mmget;
     if (!mmap_read_trylock(mm))
         goto err_mmap_read_lock_failed;
     vma = binder_alloc_get_vma(alloc);
 
     list_lru_isolate(lru, item);
     spin_unlock(lock);
 
     if (vma) {
         trace_binder_unmap_user_start(alloc, index);
 
         zap_page_range(vma, page_addr, PAGE_SIZE);
 
         trace_binder_unmap_user_end(alloc, index);
     }
     mmap_read_unlock(mm);
     mmput_async(mm);
 
     trace_binder_unmap_kernel_start(alloc, index);
 
     __free_page(page->page_ptr);
     page->page_ptr = NULL;
 
     trace_binder_unmap_kernel_end(alloc, index);
 
     spin_lock(lock);
     mutex_unlock(&alloc->mutex);
     return LRU_REMOVED_RETRY;
 
 err_mmap_read_lock_failed:
     mmput_async(mm);
 err_mmget:
 err_page_already_freed:
     mutex_unlock(&alloc->mutex);
 err_get_alloc_mutex_failed:
     return LRU_SKIP;
 }
 
 static unsigned long
 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
 {
     return list_lru_count(&binder_alloc_lru);
 }
 
 static unsigned long
 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 {
     return list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
                 NULL, sc->nr_to_scan);
 }
 
 static struct shrinker binder_shrinker = {
     .count_objects = binder_shrink_count,
     .scan_objects = binder_shrink_scan,
     .seeks = DEFAULT_SEEKS,
 };
 
 /**
  * binder_alloc_init() - called by binder_open() for per-proc initialization
  * @alloc: binder_alloc for this proc
  *
  * Called from binder_open() to initialize binder_alloc fields for
  * new binder proc
  */
 void binder_alloc_init(struct binder_alloc *alloc)
 {
     alloc->pid = current->group_leader->pid;
     alloc->vma_vm_mm = current->mm;
     mmgrab(alloc->vma_vm_mm);
     mutex_init(&alloc->mutex);
     INIT_LIST_HEAD(&alloc->buffers);
 }
 
 int binder_alloc_shrinker_init(void)
 {
     int ret = list_lru_init(&binder_alloc_lru);
 
     if (ret == 0) {
         ret = register_shrinker(&binder_shrinker, "android-binder");
         if (ret)
             list_lru_destroy(&binder_alloc_lru);
     }
     return ret;
 }
 
 /**
  * check_buffer() - verify that buffer/offset is safe to access
  * @alloc: binder_alloc for this proc
  * @buffer: binder buffer to be accessed
  * @offset: offset into @buffer data
  * @bytes: bytes to access from offset
  *
  * Check that the @offset/@bytes are within the size of the given
  * @buffer and that the buffer is currently active and not freeable.
  * Offsets must also be multiples of sizeof(u32). The kernel is
  * allowed to touch the buffer in two cases:
  *
  * 1) when the buffer is being created:
  *     (buffer->free == 0 && buffer->allow_user_free == 0)
  * 2) when the buffer is being torn down:
  *     (buffer->free == 0 && buffer->transaction == NULL).
  *
  * Return: true if the buffer is safe to access
  */
 static inline bool check_buffer(struct binder_alloc *alloc,
                 struct binder_buffer *buffer,
                 binder_size_t offset, size_t bytes)
 {
     size_t buffer_size = binder_alloc_buffer_size(alloc, buffer);
 
     return buffer_size >= bytes &&
         offset <= buffer_size - bytes &&
         IS_ALIGNED(offset, sizeof(u32)) &&
         !buffer->free &&
         (!buffer->allow_user_free || !buffer->transaction);
 }
 
 /**
  * binder_alloc_get_page() - get kernel pointer for given buffer offset
  * @alloc: binder_alloc for this proc
  * @buffer: binder buffer to be accessed
  * @buffer_offset: offset into @buffer data
  * @pgoffp: address to copy final page offset to
  *
  * Lookup the struct page corresponding to the address
  * at @buffer_offset into @buffer->user_data. If @pgoffp is not
  * NULL, the byte-offset into the page is written there.
  *
  * The caller is responsible to ensure that the offset points
  * to a valid address within the @buffer and that @buffer is
  * not freeable by the user. Since it can't be freed, we are
  * guaranteed that the corresponding elements of @alloc->pages[]
  * cannot change.
  *
  * Return: struct page
  */
 static struct page *binder_alloc_get_page(struct binder_alloc *alloc,
                       struct binder_buffer *buffer,
                       binder_size_t buffer_offset,
                       pgoff_t *pgoffp)
 {
     binder_size_t buffer_space_offset = buffer_offset +
         (buffer->user_data - alloc->buffer);
     pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
     size_t index = buffer_space_offset >> PAGE_SHIFT;
     struct binder_lru_page *lru_page;
 
     lru_page = &alloc->pages[index];
     *pgoffp = pgoff;
     return lru_page->page_ptr;
 }
 
 /**
  * binder_alloc_clear_buf() - zero out buffer
  * @alloc: binder_alloc for this proc
  * @buffer: binder buffer to be cleared
  *
  * memset the given buffer to 0
  */
 static void binder_alloc_clear_buf(struct binder_alloc *alloc,
                    struct binder_buffer *buffer)
 {
     size_t bytes = binder_alloc_buffer_size(alloc, buffer);
     binder_size_t buffer_offset = 0;
 
     while (bytes) {
         unsigned long size;
         struct page *page;
         pgoff_t pgoff;
 
         page = binder_alloc_get_page(alloc, buffer,
                          buffer_offset, &pgoff);
         size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
         memset_page(page, pgoff, 0, size);
         bytes -= size;
         buffer_offset += size;
     }
 }
 
 /**
  * binder_alloc_copy_user_to_buffer() - copy src user to tgt user
  * @alloc: binder_alloc for this proc
  * @buffer: binder buffer to be accessed
  * @buffer_offset: offset into @buffer data
  * @from: userspace pointer to source buffer
  * @bytes: bytes to copy
  *
  * Copy bytes from source userspace to target buffer.
  *
  * Return: bytes remaining to be copied
  */
 unsigned long
 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc,
                  struct binder_buffer *buffer,
                  binder_size_t buffer_offset,
                  const void __user *from,
                  size_t bytes)
 {
     if (!check_buffer(alloc, buffer, buffer_offset, bytes))
         return bytes;
 
     while (bytes) {
         unsigned long size;
         unsigned long ret;
         struct page *page;
         pgoff_t pgoff;
         void *kptr;
 
         page = binder_alloc_get_page(alloc, buffer,
                          buffer_offset, &pgoff);
         size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
         kptr = kmap_local_page(page) + pgoff;
         ret = copy_from_user(kptr, from, size);
         kunmap_local(kptr);
         if (ret)
             return bytes - size + ret;
         bytes -= size;
         from += size;
         buffer_offset += size;
     }
     return 0;
 }
 
 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc,
                        bool to_buffer,
                        struct binder_buffer *buffer,
                        binder_size_t buffer_offset,
                        void *ptr,
                        size_t bytes)
 {
     /* All copies must be 32-bit aligned and 32-bit size */
     if (!check_buffer(alloc, buffer, buffer_offset, bytes))
         return -EINVAL;
 
     while (bytes) {
         unsigned long size;
         struct page *page;
         pgoff_t pgoff;
 
         page = binder_alloc_get_page(alloc, buffer,
                          buffer_offset, &pgoff);
         size = min_t(size_t, bytes, PAGE_SIZE - pgoff);
         if (to_buffer)
             memcpy_to_page(page, pgoff, ptr, size);
         else
             memcpy_from_page(ptr, page, pgoff, size);
         bytes -= size;
         pgoff = 0;
         ptr = ptr + size;
         buffer_offset += size;
     }
     return 0;
 }
 
 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc,
                 struct binder_buffer *buffer,
                 binder_size_t buffer_offset,
                 void *src,
                 size_t bytes)
 {
     return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset,
                        src, bytes);
 }
 
 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc,
                   void *dest,
                   struct binder_buffer *buffer,
                   binder_size_t buffer_offset,
                   size_t bytes)
 {
     return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset,
                        dest, bytes);
 }
 

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