[PATCH bpf-next v3 4/4] selftests/bpf: Fix a user_ringbuf failure with arm64 64KB page size

[Yonghong Song <yonghong.song@linux.dev>]

The ringbuf max_entries must be PAGE_ALIGNED. See kernel function
ringbuf_map_alloc(). So for arm64 64KB page size, adjust max_entries
properly.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 tools/testing/selftests/bpf/prog_tests/user_ringbuf.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c b/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
index d424e7ecbd12..9fd3ae987321 100644
--- a/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
@@ -21,8 +21,7 @@
 #include "../progs/test_user_ringbuf.h"
 
 static const long c_sample_size = sizeof(struct sample) + BPF_RINGBUF_HDR_SZ;
-static const long c_ringbuf_size = 1 << 12; /* 1 small page */
-static const long c_max_entries = c_ringbuf_size / c_sample_size;
+static long c_ringbuf_size, c_max_entries;
 
 static void drain_current_samples(void)
 {
@@ -424,7 +423,9 @@ static void test_user_ringbuf_loop(void)
 	uint32_t remaining_samples = total_samples;
 	int err;
 
-	BUILD_BUG_ON(total_samples <= c_max_entries);
+	if (!ASSERT_LT(c_max_entries, total_samples, "compare_c_max_entries"))
+		return;
+
 	err = load_skel_create_user_ringbuf(&skel, &ringbuf);
 	if (err)
 		return;
@@ -686,6 +687,9 @@ void test_user_ringbuf(void)
 {
 	int i;
 
+	c_ringbuf_size = getpagesize(); /* 1 page */
+	c_max_entries = c_ringbuf_size / c_sample_size;
+
 	for (i = 0; i < ARRAY_SIZE(success_tests); i++) {
 		if (!test__start_subtest(success_tests[i].test_name))
 			continue;
-- 
2.47.1