On 5/18/26 4:49 PM, Ruidong Tian wrote:
Add KUnit tests for copy_page() and copy_mc_page(), modeled after
the existing memcpy_test() style: a static page-aligned src and a
two-page dst, filled with random bytes plus non-zero edges, then
verify byte-for-byte equality and that the adjacent page is
untouched. The copy_mc_page() case additionally checks the return
value is 0 on clean memory and is gated on CONFIG_ARCH_HAS_COPY_MC.
Signed-off-by: Ruidong Tian <[email protected]>
---
lib/tests/memcpy_kunit.c | 67 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 66 insertions(+), 1 deletion(-)
diff --git a/lib/tests/memcpy_kunit.c b/lib/tests/memcpy_kunit.c
index d36933554e46..85df53ccfb0c 100644
--- a/lib/tests/memcpy_kunit.c
+++ b/lib/tests/memcpy_kunit.c
@@ -493,6 +493,67 @@ static void memmove_overlap_test(struct kunit *test)
}
}
+/* --- Page-sized copy tests --- */
+
+static u8 page_src[PAGE_SIZE] __aligned(PAGE_SIZE);
+static u8 page_dst[PAGE_SIZE * 2] __aligned(PAGE_SIZE);
+static const u8 page_zero[PAGE_SIZE] __aligned(PAGE_SIZE);
+
+static void init_page(struct kunit *test)
+{
+ /* Get many bit patterns. */
+ get_random_bytes(page_src, PAGE_SIZE);
+
+ /* Make sure we have non-zero edges. */
+ set_random_nonzero(test, &page_src[0]);
+ set_random_nonzero(test, &page_src[PAGE_SIZE - 1]);
+
+ /* Explicitly zero the entire destination. */
+ memset(page_dst, 0, ARRAY_SIZE(page_dst));
init_page() memsets the entire two-page page_dst to zero, and the
test then asserts the second page is still zero. A buggy copy_page()
that overwrites the second page with bytes that happen to include a
zero byte would still pass.
Please fill page_dst with a non-zero sentinel (e.g. 0xA5) instead
of zero, and check the second half against that sentinel using
memchr_inv():
memset(page_dst, 0xA5, ARRAY_SIZE(page_dst));
...
KUNIT_ASSERT_TRUE_MSG(test,
!memchr_inv(page_dst + PAGE_SIZE, 0xA5, PAGE_SIZE),
"copy_page overflow into adjacent page");
This also lets you delete page_zero[] entirely, which on
PAGE_SIZE=64K configs (arm64) saves a non-trivial amount of BSS.
+}
+
+static void copy_page_test(struct kunit *test)
+{
+ init_page(test);
+
+ /* Copy. */
+ copy_page(page_dst, page_src);
+
+ /* Verify byte-for-byte exact. */
+ KUNIT_ASSERT_EQ_MSG(test,
+ memcmp(page_dst, page_src, PAGE_SIZE), 0,
+ "copy_page content mismatch with random data");
+
+ /* Verify no overflow into second page. */
+ KUNIT_ASSERT_EQ_MSG(test,
+ memcmp(page_dst + PAGE_SIZE, page_zero, PAGE_SIZE), 0,
+ "copy_page overflow into adjacent page");
+}
+
+#ifdef CONFIG_ARCH_HAS_COPY_MC
+static void copy_mc_page_test(struct kunit *test)
+{
+ int ret;
+
+ init_page(test);
+
+ /* Copy and check return value. */
+ ret = copy_mc_page(page_dst, page_src);
From sashiko:
Does this introduce a build regression on architectures like x86_64 or
powerpc?
The CONFIG_ARCH_HAS_COPY_MC flag is selected by multiple architectures,
but copy_mc_page() is an arm64-specific API. Other architectures use the
generic copy_mc_to_kernel() API instead.
If the kernel is built with KUnit enabled on non-arm64 architectures, it
appears copy_mc_page() would be an undeclared identifier.
Thanks.
Shuai
