binder: Convert binder_alloc selftests to KUnit

Convert the existing binder_alloc_selftest tests into KUnit tests. These
tests allocate and free an exhaustive combination of buffers with
various sizes and alignments. This change allows them to be run without
blocking or otherwise interfering with other processes in binder.

This test is refactored into more meaningful cases in the subsequent
patch.

Signed-off-by: Tiffany Yang <ynaffit@google.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20250714185321.2417234-6-ynaffit@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 279 insertions, 0 deletions

diff --git a/drivers/android/tests/binder_alloc_kunit.c b/drivers/android/tests/binder_alloc_kunit.c
index 4b68b5687d33..9e185e2036e5 100644
--- a/drivers/android/tests/binder_alloc_kunit.c
+++ b/drivers/android/tests/binder_alloc_kunit.c
@@ -21,6 +21,265 @@ MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
 
 #define BINDER_MMAP_SIZE SZ_128K
 
+#define BUFFER_NUM 5
+#define BUFFER_MIN_SIZE (PAGE_SIZE / 8)
+
+static int binder_alloc_test_failures;
+
+/**
+ * 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: The number of enum values in &buf_end_align_type.
+	 * It is used for controlling loop termination.
+	 */
+	LOOP_END,
+};
+
+static void pr_err_size_seq(struct kunit *test, size_t *sizes, int *seq)
+{
+	int i;
+
+	kunit_err(test, "alloc sizes: ");
+	for (i = 0; i < BUFFER_NUM; i++)
+		pr_cont("[%zu]", sizes[i]);
+	pr_cont("\n");
+	kunit_err(test, "free seq: ");
+	for (i = 0; i < BUFFER_NUM; i++)
+		pr_cont("[%d]", seq[i]);
+	pr_cont("\n");
+}
+
+static bool check_buffer_pages_allocated(struct kunit *test,
+					 struct binder_alloc *alloc,
+					 struct binder_buffer *buffer,
+					 size_t size)
+{
+	unsigned long page_addr;
+	unsigned long end;
+	int page_index;
+
+	end = PAGE_ALIGN(buffer->user_data + size);
+	page_addr = buffer->user_data;
+	for (; page_addr < end; page_addr += PAGE_SIZE) {
+		page_index = (page_addr - alloc->vm_start) / PAGE_SIZE;
+		if (!alloc->pages[page_index] ||
+		    !list_empty(page_to_lru(alloc->pages[page_index]))) {
+			kunit_err(test, "expect alloc but is %s at page index %d\n",
+				  alloc->pages[page_index] ?
+				  "lru" : "free", page_index);
+			return false;
+		}
+	}
+	return true;
+}
+
+static void binder_alloc_test_alloc_buf(struct kunit *test,
+					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(test, alloc, buffers[i], sizes[i])) {
+			pr_err_size_seq(test, sizes, seq);
+			binder_alloc_test_failures++;
+		}
+	}
+}
+
+static void binder_alloc_test_free_buf(struct kunit *test,
+				       struct binder_alloc *alloc,
+				       struct binder_buffer *buffers[],
+				       size_t *sizes, int *seq, size_t end)
+{
+	int i;
+
+	for (i = 0; i < BUFFER_NUM; i++)
+		binder_alloc_free_buf(alloc, buffers[seq[i]]);
+
+	for (i = 0; i <= (end - 1) / PAGE_SIZE; i++) {
+		if (list_empty(page_to_lru(alloc->pages[i]))) {
+			pr_err_size_seq(test, sizes, seq);
+			kunit_err(test, "expect lru but is %s at page index %d\n",
+				  alloc->pages[i] ? "alloc" : "free", i);
+			binder_alloc_test_failures++;
+		}
+	}
+}
+
+static void binder_alloc_test_free_page(struct kunit *test,
+					struct binder_alloc *alloc)
+{
+	unsigned long count;
+	int i;
+
+	while ((count = list_lru_count(alloc->freelist))) {
+		list_lru_walk(alloc->freelist, binder_alloc_free_page,
+			      NULL, count);
+	}
+
+	for (i = 0; i < (alloc->buffer_size / PAGE_SIZE); i++) {
+		if (alloc->pages[i]) {
+			kunit_err(test, "expect free but is %s at page index %d\n",
+				  list_empty(page_to_lru(alloc->pages[i])) ?
+				  "alloc" : "lru", i);
+			binder_alloc_test_failures++;
+		}
+	}
+}
+
+static void binder_alloc_test_alloc_free(struct kunit *test,
+					 struct binder_alloc *alloc,
+					 size_t *sizes, int *seq, size_t end)
+{
+	struct binder_buffer *buffers[BUFFER_NUM];
+
+	binder_alloc_test_alloc_buf(test, alloc, buffers, sizes, seq);
+	binder_alloc_test_free_buf(test, alloc, buffers, sizes, seq, end);
+
+	/* Allocate from lru. */
+	binder_alloc_test_alloc_buf(test, alloc, buffers, sizes, seq);
+	if (list_lru_count(alloc->freelist))
+		kunit_err(test, "lru list should be empty but is not\n");
+
+	binder_alloc_test_free_buf(test, alloc, buffers, sizes, seq, end);
+	binder_alloc_test_free_page(test, alloc);
+}
+
+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 permute_frees(struct kunit *test, struct binder_alloc *alloc,
+			  size_t *sizes, int *seq, int index, size_t end)
+{
+	int i;
+
+	if (index == BUFFER_NUM) {
+		binder_alloc_test_alloc_free(test, alloc, sizes, seq, end);
+		return;
+	}
+	for (i = 0; i < BUFFER_NUM; i++) {
+		if (is_dup(seq, index, i))
+			continue;
+		seq[index] = i;
+		permute_frees(test, alloc, sizes, seq, index + 1, end);
+	}
+}
+
+static void gen_buf_sizes(struct kunit *test, struct binder_alloc *alloc,
+			  size_t *end_offset)
+{
+	size_t last_offset, offset = 0;
+	size_t front_sizes[BUFFER_NUM];
+	size_t back_sizes[BUFFER_NUM];
+	int seq[BUFFER_NUM] = {0};
+	int i;
+
+	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];
+	permute_frees(test, alloc, front_sizes, seq, 0,
+		      end_offset[BUFFER_NUM - 1]);
+	permute_frees(test, alloc, back_sizes, seq, 0, alloc->buffer_size);
+}
+
+static void gen_buf_offsets(struct kunit *test, struct binder_alloc *alloc,
+			    size_t *end_offset, int index)
+{
+	size_t end, prev;
+	int align;
+
+	if (index == BUFFER_NUM) {
+		gen_buf_sizes(test, alloc, end_offset);
+		return;
+	}
+	prev = index == 0 ? 0 : end_offset[index - 1];
+	end = prev;
+
+	BUILD_BUG_ON(BUFFER_MIN_SIZE * 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;
+		gen_buf_offsets(test, alloc, end_offset, index + 1);
+	}
+}
+
 struct binder_alloc_test {
 	struct binder_alloc alloc;
 	struct list_lru binder_test_freelist;
@@ -56,6 +315,25 @@ static void binder_alloc_test_mmap(struct kunit *test)
 	KUNIT_EXPECT_TRUE(test, list_is_last(&buf->entry, &alloc->buffers));
 }
 
+/**
+ * binder_alloc_exhaustive_test() - Exhaustively test alloc and free of buffer pages.
+ * @test: The test context object.
+ *
+ * Allocate BUFFER_NUM buffers to cover all page alignment cases,
+ * then free them in all orders possible. Check that pages are
+ * correctly allocated, put onto lru when buffers are freed, and
+ * are freed when binder_alloc_free_page() is called.
+ */
+static void binder_alloc_exhaustive_test(struct kunit *test)
+{
+	struct binder_alloc_test *priv = test->priv;
+	size_t end_offset[BUFFER_NUM];
+
+	gen_buf_offsets(test, &priv->alloc, end_offset, 0);
+
+	KUNIT_EXPECT_EQ(test, binder_alloc_test_failures, 0);
+}
+
 /* ===== End test cases ===== */
 
 static void binder_alloc_test_vma_close(struct vm_area_struct *vma)
@@ -149,6 +427,7 @@ static void binder_alloc_test_exit(struct kunit *test)
 static struct kunit_case binder_alloc_test_cases[] = {
 	KUNIT_CASE(binder_alloc_test_init_freelist),
 	KUNIT_CASE(binder_alloc_test_mmap),
+	KUNIT_CASE(binder_alloc_exhaustive_test),
 	{}
 };