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[PATCH v2 0/5] android: binder: move allocator metadata and add shrinker

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  [PATCH v2 0/5] android: binder: move allocator metadata and add shrinker Sherry Yang <sherryy@android.com> - 2017-08-23 17:50 +0200
    [PATCH v2 2/5] android: binder: Add allocator selftest Sherry Yang <sherryy@android.com> - 2017-08-23 17:50 +0200

#1718465 — [PATCH v2 0/5] android: binder: move allocator metadata and add shrinker

This patch set moves internal kernel data in the binder driver
out of mmap regions that is readable by user space. A shrinker
is added to the driver to dynamically manage the memory used
by binder transactions and only free pages when the system is
under memory pressure. This patch set also adds tests and
refactoring in binder allocator.

      android: binder: Refactor prev and next buffer into a helper function
      android: binder: Add allocator selftest
      android: binder: Move buffer out of area shared with user space
      android: binder: Add global lru shrinker to binder
      android: binder: Add shrinker tracepoints

 drivers/android/Kconfig                 |  10 +
 drivers/android/Makefile                |   1 +
 drivers/android/binder.c                |   4 +
 drivers/android/binder_alloc.c          | 365 ++++++++++++++++------
 drivers/android/binder_alloc.h          |  30 +-
 drivers/android/binder_alloc_selftest.c | 310 ++++++++++++++++++
 drivers/android/binder_trace.h          |  55 ++++
 7 files changed, 678 insertions(+), 97 deletions(-)

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#1718466 — [PATCH v2 2/5] android: binder: Add allocator selftest

binder_alloc_selftest tests that alloc_new_buf handles page allocation and
deallocation properly when allocate and free buffers. The test allocates 5
buffers of various sizes to cover all possible page alignment cases, and
frees the buffers using a list of exhaustive freeing order.

Test: boot the device with ANDROID_BINDER_IPC_SELFTEST config option
enabled. Allocator selftest passes.

Signed-off-by: Sherry Yang <sherryy@android.com>
---
 drivers/android/Kconfig                 |  10 ++
 drivers/android/Makefile                |   1 +
 drivers/android/binder.c                |   2 +
 drivers/android/binder_alloc.h          |   5 +
 drivers/android/binder_alloc_selftest.c | 271 ++++++++++++++++++++++++++++++++
 5 files changed, 289 insertions(+)
 create mode 100644 drivers/android/binder_alloc_selftest.c

diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig
index 832e885349b1..0f295704abd4 100644
--- a/drivers/android/Kconfig
+++ b/drivers/android/Kconfig
@@ -44,6 +44,16 @@ config ANDROID_BINDER_IPC_32BIT
 
 	  Note that enabling this will break newer Android user-space.
 
+config ANDROID_BINDER_IPC_SELFTEST
+	bool "Android Binder IPC Driver Selftest"
+	depends on ANDROID_BINDER_IPC
+	---help---
+	  This feature allows binder selftest to run.
+
+	  Binder selftest checks the allocation and free of binder buffers
+	  exhaustively with combinations of various buffer sizes and
+	  alignments.
+
 endif # if ANDROID
 
 endmenu
diff --git a/drivers/android/Makefile b/drivers/android/Makefile
index 4b7c726bb560..a01254c43ee3 100644
--- a/drivers/android/Makefile
+++ b/drivers/android/Makefile
@@ -1,3 +1,4 @@
 ccflags-y += -I$(src)			# needed for trace events
 
 obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o binder_alloc.o
+obj-$(CONFIG_ANDROID_BINDER_IPC_SELFTEST) += binder_alloc_selftest.o
diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 9f95d7093f32..b31e64c6f666 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -4225,6 +4225,8 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	/*pr_info("binder_ioctl: %d:%d %x %lx\n",
 			proc->pid, current->pid, cmd, arg);*/
 
+	binder_selftest_alloc(&proc->alloc);
+
 	trace_binder_ioctl(cmd, arg);
 
 	ret = wait_event_interruptible(binder_user_error_wait, binder_stop_on_user_error < 2);
diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index 088e4ffc6230..4f02cc084c15 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -102,6 +102,11 @@ struct binder_alloc {
 	int pid;
 };
 
+#ifdef CONFIG_ANDROID_BINDER_IPC_SELFTEST
+void binder_selftest_alloc(struct binder_alloc *alloc);
+#else
+static inline void binder_selftest_alloc(struct binder_alloc *alloc) {}
+#endif
 extern struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 						  size_t data_size,
 						  size_t offsets_size,
diff --git a/drivers/android/binder_alloc_selftest.c b/drivers/android/binder_alloc_selftest.c
new file mode 100644
index 000000000000..cc00ab6ee29d
--- /dev/null
+++ b/drivers/android/binder_alloc_selftest.c
@@ -0,0 +1,271 @@
+/* binder_alloc_selftest.c
+ *
+ * Android IPC Subsystem
+ *
+ * Copyright (C) 2017 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/mm_types.h>
+#include <linux/err.h>
+#include "binder_alloc.h"
+
+#define BUFFER_NUM 5
+#define BUFFER_MIN_SIZE (PAGE_SIZE / 8)
+
+static bool binder_selftest_run = true;
+static int binder_selftest_failures;
+static DEFINE_MUTEX(binder_selftest_lock);
+
+/**
+ * enum buf_end_align_type - Page alignment of a buffer
+ * end with regard to the end of the previous buffer.
+ *
+ * In the pictures below, buf2 refers to the buffer we
+ * are aligning. buf1 refers to previous buffer by addr.
+ * Symbol [ means the start of a buffer, ] means the end
+ * of a buffer, and | means page boundaries.
+ */
+enum buf_end_align_type {
+	/**
+	 * @SAME_PAGE_UNALIGNED: The end of this buffer is on
+	 * the same page as the end of the previous buffer and
+	 * is not page aligned. Examples:
+	 * buf1 ][ buf2 ][ ...
+	 * buf1 ]|[ buf2 ][ ...
+	 */
+	SAME_PAGE_UNALIGNED = 0,
+	/**
+	 * @SAME_PAGE_ALIGNED: When the end of the previous buffer
+	 * is not page aligned, the end of this buffer is on the
+	 * same page as the end of the previous buffer and is page
+	 * aligned. When the previous buffer is page aligned, the
+	 * end of this buffer is aligned to the next page boundary.
+	 * Examples:
+	 * buf1 ][ buf2 ]| ...
+	 * buf1 ]|[ buf2 ]| ...
+	 */
+	SAME_PAGE_ALIGNED,
+	/**
+	 * @NEXT_PAGE_UNALIGNED: The end of this buffer is on
+	 * the page next to the end of the previous buffer and
+	 * is not page aligned. Examples:
+	 * buf1 ][ buf2 | buf2 ][ ...
+	 * buf1 ]|[ buf2 | buf2 ][ ...
+	 */
+	NEXT_PAGE_UNALIGNED,
+	/**
+	 * @NEXT_PAGE_ALIGNED: The end of this buffer is on
+	 * the page next to the end of the previous buffer and
+	 * is page aligned. Examples:
+	 * buf1 ][ buf2 | buf2 ]| ...
+	 * buf1 ]|[ buf2 | buf2 ]| ...
+	 */
+	NEXT_PAGE_ALIGNED,
+	/**
+	 * @NEXT_NEXT_UNALIGNED: The end of this buffer is on
+	 * the page that follows the page after the end of the
+	 * previous buffer and is not page aligned. Examples:
+	 * buf1 ][ buf2 | buf2 | buf2 ][ ...
+	 * buf1 ]|[ buf2 | buf2 | buf2 ][ ...
+	 */
+	NEXT_NEXT_UNALIGNED,
+	LOOP_END,
+};
+
+static void pr_err_size_seq(size_t *sizes, int *seq)
+{
+	int i;
+
+	pr_err("alloc sizes: ");
+	for (i = 0; i < BUFFER_NUM; i++)
+		pr_cont("[%zu]", sizes[i]);
+	pr_cont("\n");
+	pr_err("free seq: ");
+	for (i = 0; i < BUFFER_NUM; i++)
+		pr_cont("[%d]", seq[i]);
+	pr_cont("\n");
+}
+
+static bool check_buffer_pages_allocated(struct binder_alloc *alloc,
+					 struct binder_buffer *buffer,
+					 size_t size)
+{
+	void *page_addr, *end;
+	int page_index;
+
+	end = (void *)PAGE_ALIGN((uintptr_t)buffer + size);
+	for (page_addr = buffer; page_addr < end; page_addr += PAGE_SIZE) {
+		page_index = (page_addr - alloc->buffer) / PAGE_SIZE;
+		if (!alloc->pages[page_index]) {
+			pr_err("incorrect alloc state at page index %d\n",
+			       page_index);
+			return false;
+		}
+	}
+	return true;
+}
+
+static void binder_selftest_alloc_buf(struct binder_alloc *alloc,
+				      struct binder_buffer *buffers[],
+				      size_t *sizes, int *seq)
+{
+	int i;
+
+	for (i = 0; i < BUFFER_NUM; i++) {
+		buffers[i] = binder_alloc_new_buf(alloc, sizes[i], 0, 0, 0);
+		if (IS_ERR(buffers[i]) ||
+		    !check_buffer_pages_allocated(alloc, buffers[i],
+						  sizes[i])) {
+			pr_err_size_seq(sizes, seq);
+			binder_selftest_failures++;
+		}
+	}
+}
+
+static void binder_selftest_free_buf(struct binder_alloc *alloc,
+				     struct binder_buffer *buffers[],
+				     size_t *sizes, int *seq)
+{
+	int i;
+
+	for (i = 0; i < BUFFER_NUM; i++)
+		binder_alloc_free_buf(alloc, buffers[seq[i]]);
+
+	for (i = 0; i < (alloc->buffer_size / PAGE_SIZE); i++) {
+		if ((!alloc->pages[i]) == (i == 0)) {
+			pr_err("incorrect free state at page index %d\n", i);
+			binder_selftest_failures++;
+		}
+	}
+}
+
+static void binder_selftest_alloc_free(struct binder_alloc *alloc,
+				       size_t *sizes, int *seq)
+{
+	struct binder_buffer *buffers[BUFFER_NUM];
+
+	binder_selftest_alloc_buf(alloc, buffers, sizes, seq);
+	binder_selftest_free_buf(alloc, buffers, sizes, seq);
+}
+
+static bool is_dup(int *seq, int index, int val)
+{
+	int i;
+
+	for (i = 0; i < index; i++) {
+		if (seq[i] == val)
+			return true;
+	}
+	return false;
+}
+
+/* Generate BUFFER_NUM factorial free orders. */
+static void binder_selftest_free_seq(struct binder_alloc *alloc,
+				     size_t *sizes, int *seq, int index)
+{
+	int i;
+
+	if (index == BUFFER_NUM) {
+		binder_selftest_alloc_free(alloc, sizes, seq);
+		return;
+	}
+	for (i = 0; i < BUFFER_NUM; i++) {
+		if (is_dup(seq, index, i))
+			continue;
+		seq[index] = i;
+		binder_selftest_free_seq(alloc, sizes, seq, index + 1);
+	}
+}
+
+static void binder_selftest_alloc_size(struct binder_alloc *alloc,
+				       size_t *end_offset)
+{
+	int i;
+	int seq[BUFFER_NUM] = {0};
+	size_t front_sizes[BUFFER_NUM];
+	size_t back_sizes[BUFFER_NUM];
+	size_t last_offset, offset = 0;
+
+	for (i = 0; i < BUFFER_NUM; i++) {
+		last_offset = offset;
+		offset = end_offset[i];
+		front_sizes[i] = offset - last_offset;
+		back_sizes[BUFFER_NUM - i - 1] = front_sizes[i];
+	}
+	/*
+	 * Buffers share the first or last few pages.
+	 * Only BUFFER_NUM - 1 buffer sizes are adjustable since
+	 * we need one giant buffer before getting to the last page.
+	 */
+	back_sizes[0] += alloc->buffer_size - end_offset[BUFFER_NUM - 1]
+		- sizeof(struct binder_buffer) * BUFFER_NUM;
+	binder_selftest_free_seq(alloc, front_sizes, seq, 0);
+	binder_selftest_free_seq(alloc, back_sizes, seq, 0);
+}
+
+static void binder_selftest_alloc_offset(struct binder_alloc *alloc,
+					 size_t *end_offset, int index)
+{
+	int align;
+	size_t end, prev;
+
+	if (index == BUFFER_NUM) {
+		binder_selftest_alloc_size(alloc, end_offset);
+		return;
+	}
+	prev = index == 0 ? 0 : end_offset[index - 1];
+	end = prev;
+
+	BUILD_BUG_ON((BUFFER_MIN_SIZE + sizeof(struct binder_buffer))
+		     * BUFFER_NUM >= PAGE_SIZE);
+
+	for (align = SAME_PAGE_UNALIGNED; align < LOOP_END; align++) {
+		if (align % 2)
+			end = ALIGN(end, PAGE_SIZE);
+		else
+			end += BUFFER_MIN_SIZE;
+		end_offset[index] = end;
+		binder_selftest_alloc_offset(alloc, end_offset, index + 1);
+	}
+}
+
+/**
+ * binder_selftest_alloc() - Test alloc and free of buffer pages.
+ * @alloc: Pointer to alloc struct.
+ *
+ * Allocate BUFFER_NUM buffers to cover all page alignment cases,
+ * then free them in all orders possible. Check that pages are
+ * allocated after buffer alloc and freed after freeing buffer.
+ */
+void binder_selftest_alloc(struct binder_alloc *alloc)
+{
+	size_t end_offset[BUFFER_NUM];
+
+	if (!binder_selftest_run)
+		return;
+	mutex_lock(&binder_selftest_lock);
+	if (!binder_selftest_run || !alloc->vma)
+		goto done;
+	pr_info("STARTED\n");
+	binder_selftest_alloc_offset(alloc, end_offset, 0);
+	binder_selftest_run = false;
+	if (binder_selftest_failures > 0)
+		pr_info("%d tests FAILED\n", binder_selftest_failures);
+	else
+		pr_info("PASSED\n");
+
+done:
+	mutex_unlock(&binder_selftest_lock);
+}
-- 
2.14.1.342.g6490525c54-goog

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