On Mon, Jul 14, 2025 at 11:53:17AM -0700, Tiffany Yang wrote:
> Add setup and teardown for testing binder allocator code with KUnit.
> Include minimal test cases to verify that tests are initialized
> correctly.
>
> Tested-by: Rae Moar <rm...@google.com>
> Signed-off-by: Tiffany Yang <ynaf...@google.com>
> ---
> v2:
> * Added tested-by tag
> v3:
> * Split kunit lib change into separate change
> ---
> drivers/android/Kconfig | 11 ++
> drivers/android/Makefile | 1 +
> drivers/android/binder.c | 5 +-
> drivers/android/binder_alloc.c | 15 +-
> drivers/android/binder_alloc.h | 6 +
> drivers/android/binder_internal.h | 4 +
> drivers/android/tests/.kunitconfig | 3 +
> drivers/android/tests/Makefile | 3 +
> drivers/android/tests/binder_alloc_kunit.c | 166 +++++++++++++++++++++
> 9 files changed, 208 insertions(+), 6 deletions(-)
> create mode 100644 drivers/android/tests/.kunitconfig
> create mode 100644 drivers/android/tests/Makefile
> create mode 100644 drivers/android/tests/binder_alloc_kunit.c
>
> diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig
> index 07aa8ae0a058..b1bc7183366c 100644
> --- a/drivers/android/Kconfig
> +++ b/drivers/android/Kconfig
> @@ -47,4 +47,15 @@ config ANDROID_BINDER_IPC_SELFTEST
> exhaustively with combinations of various buffer sizes and
> alignments.
>
> +config ANDROID_BINDER_ALLOC_KUNIT_TEST
> + tristate "KUnit Tests for Android Binder Alloc" if !KUNIT_ALL_TESTS
> + depends on ANDROID_BINDER_IPC && KUNIT
> + default KUNIT_ALL_TESTS
> + help
> + This feature builds the binder alloc KUnit tests.
> +
> + Each test case runs using a pared-down binder_alloc struct and
> + test-specific freelist, which allows this KUnit module to be loaded
> + for testing without interfering with a running system.
> +
> endmenu
> diff --git a/drivers/android/Makefile b/drivers/android/Makefile
> index c9d3d0c99c25..74d02a335d4e 100644
> --- a/drivers/android/Makefile
> +++ b/drivers/android/Makefile
> @@ -4,3 +4,4 @@ ccflags-y += -I$(src) # needed for trace
> events
> obj-$(CONFIG_ANDROID_BINDERFS) += binderfs.o
> obj-$(CONFIG_ANDROID_BINDER_IPC) += binder.o binder_alloc.o
> obj-$(CONFIG_ANDROID_BINDER_IPC_SELFTEST) += binder_alloc_selftest.o
> +obj-$(CONFIG_ANDROID_BINDER_ALLOC_KUNIT_TEST) += tests/
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index c463ca4a8fff..9dfe90c284fc 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -68,6 +68,8 @@
> #include <linux/sizes.h>
> #include <linux/ktime.h>
>
> +#include <kunit/visibility.h>
> +
> #include <uapi/linux/android/binder.h>
>
> #include <linux/cacheflush.h>
> @@ -5956,10 +5958,11 @@ static void binder_vma_close(struct vm_area_struct
> *vma)
> binder_alloc_vma_close(&proc->alloc);
> }
>
> -static vm_fault_t binder_vm_fault(struct vm_fault *vmf)
> +VISIBLE_IF_KUNIT vm_fault_t binder_vm_fault(struct vm_fault *vmf)
> {
> return VM_FAULT_SIGBUS;
> }
> +EXPORT_SYMBOL_IF_KUNIT(binder_vm_fault);
>
> static const struct vm_operations_struct binder_vm_ops = {
> .open = binder_vma_open,
> diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
> index 2e89f9127883..c79e5c6721f0 100644
> --- a/drivers/android/binder_alloc.c
> +++ b/drivers/android/binder_alloc.c
> @@ -23,6 +23,7 @@
> #include <linux/uaccess.h>
> #include <linux/highmem.h>
> #include <linux/sizes.h>
> +#include <kunit/visibility.h>
> #include "binder_alloc.h"
> #include "binder_trace.h"
>
> @@ -57,13 +58,14 @@ 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)
> +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)
> @@ -959,7 +961,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
> failure_string, ret);
> return ret;
> }
> -
> +EXPORT_SYMBOL_IF_KUNIT(binder_alloc_mmap_handler);
>
> void binder_alloc_deferred_release(struct binder_alloc *alloc)
> {
> @@ -1028,6 +1030,7 @@ void binder_alloc_deferred_release(struct binder_alloc
> *alloc)
> "%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
> @@ -1122,6 +1125,7 @@ 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
> @@ -1229,8 +1233,8 @@ binder_shrink_scan(struct shrinker *shrink, struct
> shrink_control *sc)
>
> static struct shrinker *binder_shrinker;
>
> -static void __binder_alloc_init(struct binder_alloc *alloc,
> - struct list_lru *freelist)
> +VISIBLE_IF_KUNIT void __binder_alloc_init(struct binder_alloc *alloc,
> + struct list_lru *freelist)
> {
> alloc->pid = current->group_leader->pid;
> alloc->mm = current->mm;
> @@ -1239,6 +1243,7 @@ static void __binder_alloc_init(struct binder_alloc
> *alloc,
> 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
> diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
> index aa05a9df1360..dc8dce2469a7 100644
> --- a/drivers/android/binder_alloc.h
> +++ b/drivers/android/binder_alloc.h
> @@ -188,5 +188,11 @@ int binder_alloc_copy_from_buffer(struct binder_alloc
> *alloc,
> binder_size_t buffer_offset,
> size_t bytes);
>
> +#if IS_ENABLED(CONFIG_KUNIT)
> +void __binder_alloc_init(struct binder_alloc *alloc, struct list_lru
> *freelist);
> +size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
> + struct binder_buffer *buffer);
> +#endif
> +
> #endif /* _LINUX_BINDER_ALLOC_H */
>
> diff --git a/drivers/android/binder_internal.h
> b/drivers/android/binder_internal.h
> index 1ba5caf1d88d..b5d3014fb4dc 100644
> --- a/drivers/android/binder_internal.h
> +++ b/drivers/android/binder_internal.h
> @@ -592,4 +592,8 @@ void binder_add_device(struct binder_device *device);
> */
> void binder_remove_device(struct binder_device *device);
>
> +#if IS_ENABLED(CONFIG_KUNIT)
> +vm_fault_t binder_vm_fault(struct vm_fault *vmf);
> +#endif
I'm used to the "#ifdef CONFIG_..." idiom, but looking at the tree, I
see that "#if IS_ENANLED(CONFIG...)" is relatively common too. I don't
think there is a function difference, so I leave the style choice up to
you! ;)
> +
> #endif /* _LINUX_BINDER_INTERNAL_H */
> diff --git a/drivers/android/tests/.kunitconfig
> b/drivers/android/tests/.kunitconfig
> new file mode 100644
> index 000000000000..a73601231049
> --- /dev/null
> +++ b/drivers/android/tests/.kunitconfig
> @@ -0,0 +1,3 @@
> +CONFIG_KUNIT=y
> +CONFIG_ANDROID_BINDER_IPC=y
> +CONFIG_ANDROID_BINDER_ALLOC_KUNIT_TEST=y
> diff --git a/drivers/android/tests/Makefile b/drivers/android/tests/Makefile
> new file mode 100644
> index 000000000000..6780967e573b
> --- /dev/null
> +++ b/drivers/android/tests/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +
> +obj-$(CONFIG_ANDROID_BINDER_ALLOC_KUNIT_TEST) += binder_alloc_kunit.o
> diff --git a/drivers/android/tests/binder_alloc_kunit.c
> b/drivers/android/tests/binder_alloc_kunit.c
> new file mode 100644
> index 000000000000..4b68b5687d33
> --- /dev/null
> +++ b/drivers/android/tests/binder_alloc_kunit.c
> @@ -0,0 +1,166 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Test cases for binder allocator code
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <kunit/test.h>
> +#include <linux/anon_inodes.h>
> +#include <linux/err.h>
> +#include <linux/file.h>
> +#include <linux/fs.h>
> +#include <linux/mm.h>
> +#include <linux/mman.h>
> +#include <linux/sizes.h>
> +
> +#include "../binder_alloc.h"
> +#include "../binder_internal.h"
> +
> +MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
> +
> +#define BINDER_MMAP_SIZE SZ_128K
> +
> +struct binder_alloc_test {
> + struct binder_alloc alloc;
> + struct list_lru binder_test_freelist;
> + struct file *filp;
> + unsigned long mmap_uaddr;
> +};
> +
> +static void binder_alloc_test_init_freelist(struct kunit *test)
> +{
> + struct binder_alloc_test *priv = test->priv;
> +
> + KUNIT_EXPECT_PTR_EQ(test, priv->alloc.freelist,
> + &priv->binder_test_freelist);
> +}
> +
> +static void binder_alloc_test_mmap(struct kunit *test)
> +{
> + struct binder_alloc_test *priv = test->priv;
> + struct binder_alloc *alloc = &priv->alloc;
> + struct binder_buffer *buf;
> + struct rb_node *n;
> +
> + KUNIT_EXPECT_EQ(test, alloc->mapped, true);
> + KUNIT_EXPECT_EQ(test, alloc->buffer_size, BINDER_MMAP_SIZE);
> +
> + n = rb_first(&alloc->allocated_buffers);
> + KUNIT_EXPECT_PTR_EQ(test, n, NULL);
> +
> + n = rb_first(&alloc->free_buffers);
> + buf = rb_entry(n, struct binder_buffer, rb_node);
> + KUNIT_EXPECT_EQ(test, binder_alloc_buffer_size(alloc, buf),
> + BINDER_MMAP_SIZE);
> + KUNIT_EXPECT_TRUE(test, list_is_last(&buf->entry, &alloc->buffers));
> +}
> +
> +/* ===== End test cases ===== */
> +
> +static void binder_alloc_test_vma_close(struct vm_area_struct *vma)
> +{
> + struct binder_alloc *alloc = vma->vm_private_data;
> +
> + binder_alloc_vma_close(alloc);
> +}
> +
> +static const struct vm_operations_struct binder_alloc_test_vm_ops = {
> + .close = binder_alloc_test_vma_close,
> + .fault = binder_vm_fault,
> +};
> +
> +static int binder_alloc_test_mmap_handler(struct file *filp,
> + struct vm_area_struct *vma)
> +{
> + struct binder_alloc *alloc = filp->private_data;
> +
> + vm_flags_mod(vma, VM_DONTCOPY | VM_MIXEDMAP, VM_MAYWRITE);
> +
> + vma->vm_ops = &binder_alloc_test_vm_ops;
> + vma->vm_private_data = alloc;
> +
> + return binder_alloc_mmap_handler(alloc, vma);
> +}
> +
> +static const struct file_operations binder_alloc_test_fops = {
> + .mmap = binder_alloc_test_mmap_handler,
> +};
> +
> +static int binder_alloc_test_init(struct kunit *test)
> +{
> + struct binder_alloc_test *priv;
> + int ret;
> +
> + priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> + test->priv = priv;
> +
> + ret = list_lru_init(&priv->binder_test_freelist);
> + if (ret) {
> + kunit_err(test, "Failed to initialize test freelist\n");
> + return ret;
> + }
> +
> + /* __binder_alloc_init requires mm to be attached */
> + ret = kunit_attach_mm();
> + if (ret) {
> + kunit_err(test, "Failed to attach mm\n");
> + return ret;
> + }
> + __binder_alloc_init(&priv->alloc, &priv->binder_test_freelist);
> +
> + priv->filp = anon_inode_getfile("binder_alloc_kunit",
> + &binder_alloc_test_fops, &priv->alloc,
> + O_RDWR | O_CLOEXEC);
> + if (IS_ERR_OR_NULL(priv->filp)) {
> + kunit_err(test, "Failed to open binder alloc test driver
> file\n");
> + return priv->filp ? PTR_ERR(priv->filp) : -ENOMEM;
> + }
> +
> + priv->mmap_uaddr = kunit_vm_mmap(test, priv->filp, 0, BINDER_MMAP_SIZE,
> + PROT_READ, MAP_PRIVATE | MAP_NORESERVE,
> + 0);
> + if (!priv->mmap_uaddr) {
> + kunit_err(test, "Could not map the test's transaction
> memory\n");
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static void binder_alloc_test_exit(struct kunit *test)
> +{
> + struct binder_alloc_test *priv = test->priv;
> +
> + /* Close the backing file to make sure binder_alloc_vma_close runs */
> + if (!IS_ERR_OR_NULL(priv->filp))
> + fput(priv->filp);
> +
> + if (priv->alloc.mm)
> + binder_alloc_deferred_release(&priv->alloc);
> +
> + /* Make sure freelist is empty */
> + KUNIT_EXPECT_EQ(test, list_lru_count(&priv->binder_test_freelist), 0);
> + list_lru_destroy(&priv->binder_test_freelist);
> +}
> +
> +static struct kunit_case binder_alloc_test_cases[] = {
> + KUNIT_CASE(binder_alloc_test_init_freelist),
> + KUNIT_CASE(binder_alloc_test_mmap),
> + {}
> +};
> +
> +static struct kunit_suite binder_alloc_test_suite = {
> + .name = "binder_alloc",
> + .test_cases = binder_alloc_test_cases,
> + .init = binder_alloc_test_init,
> + .exit = binder_alloc_test_exit,
> +};
> +
> +kunit_test_suite(binder_alloc_test_suite);
> +
> +MODULE_AUTHOR("Tiffany Yang <ynaf...@google.com>");
> +MODULE_DESCRIPTION("Binder Alloc KUnit tests");
> +MODULE_LICENSE("GPL");
Reviewed-by: Kees Cook <k...@kernel.org>
--
Kees Cook
