Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1409 insertions, 0 deletions

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
new file mode 100644
index 000000000..e4488ad86
--- /dev/null
+++ b/drivers/android/binder_alloc.c
@@ -0,0 +1,1409 @@
+// 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 <kunit/visibility.h>
+#include "binder_alloc.h"
+#include "binder_trace.h"
+
+static struct list_lru binder_freelist;
+
+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);
+}
+
+VISIBLE_IF_KUNIT size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
+						 struct binder_buffer *buffer)
+{
+	if (list_is_last(&buffer->entry, &alloc->buffers))
+		return alloc->vm_start + alloc->buffer_size - buffer->user_data;
+	return binder_buffer_next(buffer)->user_data - buffer->user_data;
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_buffer_size);
+
+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 %p\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,
+		unsigned long user_ptr)
+{
+	struct rb_node *n = alloc->allocated_buffers.rb_node;
+	struct binder_buffer *buffer;
+
+	while (n) {
+		buffer = rb_entry(n, struct binder_buffer, rb_node);
+		BUG_ON(buffer->free);
+
+		if (user_ptr < buffer->user_data) {
+			n = n->rb_left;
+		} else if (user_ptr > 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,
+						   unsigned long user_ptr)
+{
+	guard(mutex)(&alloc->mutex);
+	return binder_alloc_prepare_to_free_locked(alloc, user_ptr);
+}
+
+static inline void
+binder_set_installed_page(struct binder_alloc *alloc,
+			  unsigned long index,
+			  struct page *page)
+{
+	/* Pairs with acquire in binder_get_installed_page() */
+	smp_store_release(&alloc->pages[index], page);
+}
+
+static inline struct page *
+binder_get_installed_page(struct binder_alloc *alloc, unsigned long index)
+{
+	/* Pairs with release in binder_set_installed_page() */
+	return smp_load_acquire(&alloc->pages[index]);
+}
+
+static void binder_lru_freelist_add(struct binder_alloc *alloc,
+				    unsigned long start, unsigned long end)
+{
+	unsigned long page_addr;
+	struct page *page;
+
+	trace_binder_update_page_range(alloc, false, start, end);
+
+	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
+		size_t index;
+		int ret;
+
+		index = (page_addr - alloc->vm_start) / PAGE_SIZE;
+		page = binder_get_installed_page(alloc, index);
+		if (!page)
+			continue;
+
+		trace_binder_free_lru_start(alloc, index);
+
+		ret = list_lru_add(alloc->freelist,
+				   page_to_lru(page),
+				   page_to_nid(page),
+				   NULL);
+		WARN_ON(!ret);
+
+		trace_binder_free_lru_end(alloc, index);
+	}
+}
+
+static inline
+void binder_alloc_set_mapped(struct binder_alloc *alloc, bool state)
+{
+	/* pairs with smp_load_acquire in binder_alloc_is_mapped() */
+	smp_store_release(&alloc->mapped, state);
+}
+
+static inline bool binder_alloc_is_mapped(struct binder_alloc *alloc)
+{
+	/* pairs with smp_store_release in binder_alloc_set_mapped() */
+	return smp_load_acquire(&alloc->mapped);
+}
+
+static struct page *binder_page_lookup(struct binder_alloc *alloc,
+				       unsigned long addr)
+{
+	struct mm_struct *mm = alloc->mm;
+	struct page *page;
+	long npages = 0;
+
+	/*
+	 * Find an existing page in the remote mm. If missing,
+	 * don't attempt to fault-in just propagate an error.
+	 */
+	mmap_read_lock(mm);
+	if (binder_alloc_is_mapped(alloc))
+		npages = get_user_pages_remote(mm, addr, 1, FOLL_NOFAULT,
+					       &page, NULL);
+	mmap_read_unlock(mm);
+
+	return npages > 0 ? page : NULL;
+}
+
+static int binder_page_insert(struct binder_alloc *alloc,
+			      unsigned long addr,
+			      struct page *page)
+{
+	struct mm_struct *mm = alloc->mm;
+	struct vm_area_struct *vma;
+	int ret = -ESRCH;
+
+	/* attempt per-vma lock first */
+	vma = lock_vma_under_rcu(mm, addr);
+	if (vma) {
+		if (binder_alloc_is_mapped(alloc))
+			ret = vm_insert_page(vma, addr, page);
+		vma_end_read(vma);
+		return ret;
+	}
+
+	/* fall back to mmap_lock */
+	mmap_read_lock(mm);
+	vma = vma_lookup(mm, addr);
+	if (vma && binder_alloc_is_mapped(alloc))
+		ret = vm_insert_page(vma, addr, page);
+	mmap_read_unlock(mm);
+
+	return ret;
+}
+
+static struct page *binder_page_alloc(struct binder_alloc *alloc,
+				      unsigned long index)
+{
+	struct binder_shrinker_mdata *mdata;
+	struct page *page;
+
+	page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
+	if (!page)
+		return NULL;
+
+	/* allocate and install shrinker metadata under page->private */
+	mdata = kzalloc_obj(*mdata);
+	if (!mdata) {
+		__free_page(page);
+		return NULL;
+	}
+
+	mdata->alloc = alloc;
+	mdata->page_index = index;
+	INIT_LIST_HEAD(&mdata->lru);
+	set_page_private(page, (unsigned long)mdata);
+
+	return page;
+}
+
+static void binder_free_page(struct page *page)
+{
+	kfree((struct binder_shrinker_mdata *)page_private(page));
+	__free_page(page);
+}
+
+static int binder_install_single_page(struct binder_alloc *alloc,
+				      unsigned long index,
+				      unsigned long addr)
+{
+	struct page *page;
+	int ret;
+
+	if (!mmget_not_zero(alloc->mm))
+		return -ESRCH;
+
+	page = binder_page_alloc(alloc, index);
+	if (!page) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = binder_page_insert(alloc, addr, page);
+	switch (ret) {
+	case -EBUSY:
+		/*
+		 * EBUSY is ok. Someone installed the pte first but the
+		 * alloc->pages[index] has not been updated yet. Discard
+		 * our page and look up the one already installed.
+		 */
+		ret = 0;
+		binder_free_page(page);
+		page = binder_page_lookup(alloc, addr);
+		if (!page) {
+			pr_err("%d: failed to find page at offset %lx\n",
+			       alloc->pid, addr - alloc->vm_start);
+			ret = -ESRCH;
+			break;
+		}
+		fallthrough;
+	case 0:
+		/* Mark page installation complete and safe to use */
+		binder_set_installed_page(alloc, index, page);
+		break;
+	default:
+		binder_free_page(page);
+		pr_err("%d: %s failed to insert page at offset %lx with %d\n",
+		       alloc->pid, __func__, addr - alloc->vm_start, ret);
+		break;
+	}
+out:
+	mmput_async(alloc->mm);
+	return ret;
+}
+
+static int binder_install_buffer_pages(struct binder_alloc *alloc,
+				       struct binder_buffer *buffer,
+				       size_t size)
+{
+	unsigned long start, final;
+	unsigned long page_addr;
+
+	start = buffer->user_data & PAGE_MASK;
+	final = PAGE_ALIGN(buffer->user_data + size);
+
+	for (page_addr = start; page_addr < final; page_addr += PAGE_SIZE) {
+		unsigned long index;
+		int ret;
+
+		index = (page_addr - alloc->vm_start) / PAGE_SIZE;
+		if (binder_get_installed_page(alloc, index))
+			continue;
+
+		trace_binder_alloc_page_start(alloc, index);
+
+		ret = binder_install_single_page(alloc, index, page_addr);
+		if (ret)
+			return ret;
+
+		trace_binder_alloc_page_end(alloc, index);
+	}
+
+	return 0;
+}
+
+/* The range of pages should exclude those shared with other buffers */
+static void binder_lru_freelist_del(struct binder_alloc *alloc,
+				    unsigned long start, unsigned long end)
+{
+	unsigned long page_addr;
+	struct page *page;
+
+	trace_binder_update_page_range(alloc, true, start, end);
+
+	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
+		unsigned long index;
+		bool on_lru;
+
+		index = (page_addr - alloc->vm_start) / PAGE_SIZE;
+		page = binder_get_installed_page(alloc, index);
+
+		if (page) {
+			trace_binder_alloc_lru_start(alloc, index);
+
+			on_lru = list_lru_del(alloc->freelist,
+					      page_to_lru(page),
+					      page_to_nid(page),
+					      NULL);
+			WARN_ON(!on_lru);
+
+			trace_binder_alloc_lru_end(alloc, index);
+			continue;
+		}
+
+		if (index + 1 > alloc->pages_high)
+			alloc->pages_high = index + 1;
+	}
+}
+
+static void debug_no_space_locked(struct binder_alloc *alloc)
+{
+	size_t largest_alloc_size = 0;
+	struct binder_buffer *buffer;
+	size_t allocated_buffers = 0;
+	size_t largest_free_size = 0;
+	size_t total_alloc_size = 0;
+	size_t total_free_size = 0;
+	size_t free_buffers = 0;
+	size_t buffer_size;
+	struct rb_node *n;
+
+	for (n = rb_first(&alloc->allocated_buffers); n; 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; 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,
+			   "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);
+}
+
+static bool debug_low_async_space_locked(struct binder_alloc *alloc)
+{
+	/*
+	 * 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 binder_buffer *buffer;
+	size_t total_alloc_size = 0;
+	int pid = current->tgid;
+	size_t num_buffers = 0;
+	struct rb_node *n;
+
+	/*
+	 * Only start detecting spammers once we have less than 20% of async
+	 * space left (which is less than 10% of total buffer size).
+	 */
+	if (alloc->free_async_space >= alloc->buffer_size / 10) {
+		alloc->oneway_spam_detected = false;
+		return false;
+	}
+
+	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);
+		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;
+}
+
+/* Callers preallocate @new_buffer, it is freed by this function if unused */
+static struct binder_buffer *binder_alloc_new_buf_locked(
+				struct binder_alloc *alloc,
+				struct binder_buffer *new_buffer,
+				size_t size,
+				int is_async)
+{
+	struct rb_node *n = alloc->free_buffers.rb_node;
+	struct rb_node *best_fit = NULL;
+	struct binder_buffer *buffer;
+	unsigned long next_used_page;
+	unsigned long curr_last_page;
+	size_t buffer_size;
+
+	if (is_async && alloc->free_async_space < size) {
+		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
+			     "%d: binder_alloc_buf size %zd failed, no async space left\n",
+			      alloc->pid, size);
+		buffer = ERR_PTR(-ENOSPC);
+		goto out;
+	}
+
+	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 (unlikely(!best_fit)) {
+		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
+				   "%d: binder_alloc_buf size %zd failed, no address space\n",
+				   alloc->pid, size);
+		debug_no_space_locked(alloc);
+		buffer = ERR_PTR(-ENOSPC);
+		goto out;
+	}
+
+	if (buffer_size != size) {
+		/* Found an oversized buffer and needs to be split */
+		buffer = rb_entry(best_fit, struct binder_buffer, rb_node);
+		buffer_size = binder_alloc_buffer_size(alloc, buffer);
+
+		WARN_ON(n || buffer_size == size);
+		new_buffer->user_data = buffer->user_data + size;
+		list_add(&new_buffer->entry, &buffer->entry);
+		new_buffer->free = 1;
+		binder_insert_free_buffer(alloc, new_buffer);
+		new_buffer = NULL;
+	}
+
+	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
+		     "%d: binder_alloc_buf size %zd got buffer %p size %zd\n",
+		      alloc->pid, size, buffer, buffer_size);
+
+	/*
+	 * Now we remove the pages from the freelist. A clever calculation
+	 * with buffer_size determines if the last page is shared with an
+	 * adjacent in-use buffer. In such case, the page has been already
+	 * removed from the freelist so we trim our range short.
+	 */
+	next_used_page = (buffer->user_data + buffer_size) & PAGE_MASK;
+	curr_last_page = PAGE_ALIGN(buffer->user_data + size);
+	binder_lru_freelist_del(alloc, PAGE_ALIGN(buffer->user_data),
+				min(next_used_page, curr_last_page));
+
+	rb_erase(&buffer->rb_node, &alloc->free_buffers);
+	buffer->free = 0;
+	buffer->allow_user_free = 0;
+	binder_insert_allocated_buffer_locked(alloc, buffer);
+	buffer->async_transaction = is_async;
+	buffer->oneway_spam_suspect = false;
+	if (is_async) {
+		alloc->free_async_space -= size;
+		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 (debug_low_async_space_locked(alloc))
+			buffer->oneway_spam_suspect = true;
+	}
+
+out:
+	/* Discard possibly unused new_buffer */
+	kfree(new_buffer);
+	return buffer;
+}
+
+/* Calculate the sanitized total size, returns 0 for invalid request */
+static inline size_t sanitized_size(size_t data_size,
+				    size_t offsets_size,
+				    size_t extra_buffers_size)
+{
+	size_t total, tmp;
+
+	/* Align to pointer size and check for overflows */
+	tmp = ALIGN(data_size, sizeof(void *)) +
+		ALIGN(offsets_size, sizeof(void *));
+	if (tmp < data_size || tmp < offsets_size)
+		return 0;
+	total = tmp + ALIGN(extra_buffers_size, sizeof(void *));
+	if (total < tmp || total < extra_buffers_size)
+		return 0;
+
+	/* Pad 0-sized buffers so they get a unique address */
+	total = max(total, sizeof(void *));
+
+	return total;
+}
+
+/**
+ * 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
+ *
+ * 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 %ERR_PTR(-errno) 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)
+{
+	struct binder_buffer *buffer, *next;
+	size_t size;
+	int ret;
+
+	/* Check binder_alloc is fully initialized */
+	if (!binder_alloc_is_mapped(alloc)) {
+		binder_alloc_debug(BINDER_DEBUG_USER_ERROR,
+				   "%d: binder_alloc_buf, no vma\n",
+				   alloc->pid);
+		return ERR_PTR(-ESRCH);
+	}
+
+	size = sanitized_size(data_size, offsets_size, extra_buffers_size);
+	if (unlikely(!size)) {
+		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
+				   "%d: got transaction with invalid size %zd-%zd-%zd\n",
+				   alloc->pid, data_size, offsets_size,
+				   extra_buffers_size);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* Preallocate the next buffer */
+	next = kzalloc_obj(*next);
+	if (!next)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_lock(&alloc->mutex);
+	buffer = binder_alloc_new_buf_locked(alloc, next, size, is_async);
+	if (IS_ERR(buffer)) {
+		mutex_unlock(&alloc->mutex);
+		goto out;
+	}
+
+	buffer->data_size = data_size;
+	buffer->offsets_size = offsets_size;
+	buffer->extra_buffers_size = extra_buffers_size;
+	buffer->pid = current->tgid;
+	mutex_unlock(&alloc->mutex);
+
+	ret = binder_install_buffer_pages(alloc, buffer, size);
+	if (ret) {
+		binder_alloc_free_buf(alloc, buffer);
+		buffer = ERR_PTR(ret);
+	}
+out:
+	return buffer;
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_new_buf);
+
+static unsigned long buffer_start_page(struct binder_buffer *buffer)
+{
+	return buffer->user_data & PAGE_MASK;
+}
+
+static unsigned long prev_buffer_end_page(struct binder_buffer *buffer)
+{
+	return (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;
+
+	if (PAGE_ALIGNED(buffer->user_data))
+		goto skip_freelist;
+
+	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))
+		goto skip_freelist;
+
+	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
+		next = binder_buffer_next(buffer);
+		if (buffer_start_page(next) == buffer_start_page(buffer))
+			goto skip_freelist;
+	}
+
+	binder_lru_freelist_add(alloc, buffer_start_page(buffer),
+				buffer_start_page(buffer) + PAGE_SIZE);
+skip_freelist:
+	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 %p 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->vm_start);
+	BUG_ON(buffer->user_data > alloc->vm_start + alloc->buffer_size);
+
+	if (buffer->async_transaction) {
+		alloc->free_async_space += buffer_size;
+		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_lru_freelist_add(alloc, PAGE_ALIGN(buffer->user_data),
+				(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);
+}
+
+/**
+ * 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->vm_start);
+	pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK;
+	size_t index = buffer_space_offset >> PAGE_SHIFT;
+
+	*pgoffp = pgoff;
+
+	return alloc->pages[index];
+}
+
+/**
+ * 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_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_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);
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_free_buf);
+
+/**
+ * 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)
+{
+	struct binder_buffer *buffer;
+	const char *failure_string;
+	int ret;
+
+	if (unlikely(vma->vm_mm != alloc->mm)) {
+		ret = -EINVAL;
+		failure_string = "invalid vma->vm_mm";
+		goto err_invalid_mm;
+	}
+
+	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->vm_start = vma->vm_start;
+
+	alloc->pages = kvzalloc_objs(alloc->pages[0],
+				     alloc->buffer_size / PAGE_SIZE);
+	if (!alloc->pages) {
+		ret = -ENOMEM;
+		failure_string = "alloc page array";
+		goto err_alloc_pages_failed;
+	}
+
+	buffer = kzalloc_obj(*buffer);
+	if (!buffer) {
+		ret = -ENOMEM;
+		failure_string = "alloc buffer struct";
+		goto err_alloc_buf_struct_failed;
+	}
+
+	buffer->user_data = alloc->vm_start;
+	list_add(&buffer->entry, &alloc->buffers);
+	buffer->free = 1;
+	binder_insert_free_buffer(alloc, buffer);
+	alloc->free_async_space = alloc->buffer_size / 2;
+
+	/* Signal binder_alloc is fully initialized */
+	binder_alloc_set_mapped(alloc, true);
+
+	return 0;
+
+err_alloc_buf_struct_failed:
+	kvfree(alloc->pages);
+	alloc->pages = NULL;
+err_alloc_pages_failed:
+	alloc->vm_start = 0;
+	mutex_lock(&binder_alloc_mmap_lock);
+	alloc->buffer_size = 0;
+err_already_mapped:
+	mutex_unlock(&binder_alloc_mmap_lock);
+err_invalid_mm:
+	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;
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_mmap_handler);
+
+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->mapped);
+
+	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++) {
+			struct page *page;
+			bool on_lru;
+
+			page = binder_get_installed_page(alloc, i);
+			if (!page)
+				continue;
+
+			on_lru = list_lru_del(alloc->freelist,
+					      page_to_lru(page),
+					      page_to_nid(page),
+					      NULL);
+			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
+				     "%s: %d: page %d %s\n",
+				     __func__, alloc->pid, i,
+				     on_lru ? "on lru" : "active");
+			binder_free_page(page);
+			page_count++;
+		}
+	}
+	mutex_unlock(&alloc->mutex);
+	kvfree(alloc->pages);
+	if (alloc->mm)
+		mmdrop(alloc->mm);
+
+	binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE,
+		     "%s: %d buffers %d, pages %d\n",
+		     __func__, alloc->pid, buffers, page_count);
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_deferred_release);
+
+/**
+ * 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 binder_buffer *buffer;
+	struct rb_node *n;
+
+	guard(mutex)(&alloc->mutex);
+	for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
+		buffer = rb_entry(n, struct binder_buffer, rb_node);
+		seq_printf(m, "  buffer %d: %lx size %zd:%zd:%zd %s\n",
+			   buffer->debug_id,
+			   buffer->user_data - alloc->vm_start,
+			   buffer->data_size, buffer->offsets_size,
+			   buffer->extra_buffers_size,
+			   buffer->transaction ? "active" : "delivered");
+	}
+}
+
+/**
+ * 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 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.
+	 */
+	if (binder_alloc_is_mapped(alloc)) {
+		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
+			page = binder_get_installed_page(alloc, i);
+			if (!page)
+				free++;
+			else if (list_empty(page_to_lru(page)))
+				active++;
+			else
+				lru++;
+		}
+	}
+	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;
+
+	guard(mutex)(&alloc->mutex);
+	for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
+		count++;
+	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->mapped to prevent new incoming transactions from
+ * allocating more buffers.
+ */
+void binder_alloc_vma_close(struct binder_alloc *alloc)
+{
+	binder_alloc_set_mapped(alloc, false);
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_vma_close);
+
+/**
+ * binder_alloc_free_page() - shrinker callback to free pages
+ * @item:   item to free
+ * @lru:    list_lru instance of 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,
+				       void *cb_arg)
+	__must_hold(&lru->lock)
+{
+	struct binder_shrinker_mdata *mdata = container_of(item, typeof(*mdata), lru);
+	struct binder_alloc *alloc = mdata->alloc;
+	struct mm_struct *mm = alloc->mm;
+	struct vm_area_struct *vma;
+	struct page *page_to_free;
+	unsigned long page_addr;
+	int mm_locked = 0;
+	size_t index;
+
+	if (!mmget_not_zero(mm))
+		goto err_mmget;
+
+	index = mdata->page_index;
+	page_addr = alloc->vm_start + index * PAGE_SIZE;
+
+	/* attempt per-vma lock first */
+	vma = lock_vma_under_rcu(mm, page_addr);
+	if (!vma) {
+		/* fall back to mmap_lock */
+		if (!mmap_read_trylock(mm))
+			goto err_mmap_read_lock_failed;
+		mm_locked = 1;
+		vma = vma_lookup(mm, page_addr);
+	}
+
+	if (!mutex_trylock(&alloc->mutex))
+		goto err_get_alloc_mutex_failed;
+
+	/*
+	 * Since a binder_alloc can only be mapped once, we ensure
+	 * the vma corresponds to this mapping by checking whether
+	 * the binder_alloc is still mapped.
+	 */
+	if (vma && !binder_alloc_is_mapped(alloc))
+		goto err_invalid_vma;
+
+	trace_binder_unmap_kernel_start(alloc, index);
+
+	page_to_free = alloc->pages[index];
+	binder_set_installed_page(alloc, index, NULL);
+
+	trace_binder_unmap_kernel_end(alloc, index);
+
+	list_lru_isolate(lru, item);
+	spin_unlock(&lru->lock);
+
+	if (vma) {
+		trace_binder_unmap_user_start(alloc, index);
+
+		zap_vma_range(vma, page_addr, PAGE_SIZE);
+
+		trace_binder_unmap_user_end(alloc, index);
+	}
+
+	mutex_unlock(&alloc->mutex);
+	if (mm_locked)
+		mmap_read_unlock(mm);
+	else
+		vma_end_read(vma);
+	mmput_async(mm);
+	binder_free_page(page_to_free);
+
+	return LRU_REMOVED_RETRY;
+
+err_invalid_vma:
+	mutex_unlock(&alloc->mutex);
+err_get_alloc_mutex_failed:
+	if (mm_locked)
+		mmap_read_unlock(mm);
+	else
+		vma_end_read(vma);
+err_mmap_read_lock_failed:
+	mmput_async(mm);
+err_mmget:
+	return LRU_SKIP;
+}
+EXPORT_SYMBOL_IF_KUNIT(binder_alloc_free_page);
+
+static unsigned long
+binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+	return list_lru_count(&binder_freelist);
+}
+
+static unsigned long
+binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+	return list_lru_walk(&binder_freelist, binder_alloc_free_page,
+			    NULL, sc->nr_to_scan);
+}
+
+static struct shrinker *binder_shrinker;
+
+VISIBLE_IF_KUNIT void __binder_alloc_init(struct binder_alloc *alloc,
+					  struct list_lru *freelist)
+{
+	alloc->pid = current->tgid;
+	alloc->mm = current->mm;
+	mmgrab(alloc->mm);
+	mutex_init(&alloc->mutex);
+	INIT_LIST_HEAD(&alloc->buffers);
+	alloc->freelist = freelist;
+}
+EXPORT_SYMBOL_IF_KUNIT(__binder_alloc_init);
+
+/**
+ * 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)
+{
+	__binder_alloc_init(alloc, &binder_freelist);
+}
+
+int binder_alloc_shrinker_init(void)
+{
+	int ret;
+
+	ret = list_lru_init(&binder_freelist);
+	if (ret)
+		return ret;
+
+	binder_shrinker = shrinker_alloc(0, "android-binder");
+	if (!binder_shrinker) {
+		list_lru_destroy(&binder_freelist);
+		return -ENOMEM;
+	}
+
+	binder_shrinker->count_objects = binder_shrink_count;
+	binder_shrinker->scan_objects = binder_shrink_scan;
+
+	shrinker_register(binder_shrinker);
+
+	return 0;
+}
+
+void binder_alloc_shrinker_exit(void)
+{
+	shrinker_free(binder_shrinker);
+	list_lru_destroy(&binder_freelist);
+}
+
+/**
+ * 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_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);
+}