queue-6.1/selftests-bpf-fix-a-user_ringbuf-failure-with-arm64-.patch

From 138151c5d0c378aa43b7d5f15741e3cb8ed89332 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 6 Jun 2025 18:36:26 -0700
Subject: selftests/bpf: Fix a user_ringbuf failure with arm64 64KB page size

From: Yonghong Song <yonghong.song@linux.dev>

[ Upstream commit bbc7bd658ddc662083639b9e9a280b90225ecd9a ]

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>
Link: https://lore.kernel.org/r/20250607013626.1553001-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 ca81d660eb96..5e88d37973c5 100644
--- a/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
@@ -23,8 +23,7 @@
 static size_t log_buf_sz = 1 << 20; /* 1 MB */
 static char obj_log_buf[1048576];
 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)
 {
@@ -426,7 +425,9 @@ 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;
@@ -739,6 +740,9 @@ 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;
-- 
2.39.5