selftests/bpf: Test skipping stacktrace

Add a test case for stacktrace with skip > 0 using a small sized
buffer.  It didn't support skipping entries greater than or equal to
the size of buffer and filled the skipped part with 0.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220314182042.71025-2-namhyung@kernel.org

1 files changed, 63 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c
new file mode 100644
index 0000000000000..1932b1e0685cf
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_map_skip.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include "stacktrace_map_skip.skel.h"
+
+#define TEST_STACK_DEPTH  2
+
+void test_stacktrace_map_skip(void)
+{
+	struct stacktrace_map_skip *skel;
+	int stackid_hmap_fd, stackmap_fd, stack_amap_fd;
+	int err, stack_trace_len;
+
+	skel = stacktrace_map_skip__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	/* find map fds */
+	stackid_hmap_fd = bpf_map__fd(skel->maps.stackid_hmap);
+	if (!ASSERT_GE(stackid_hmap_fd, 0, "stackid_hmap fd"))
+		goto out;
+
+	stackmap_fd = bpf_map__fd(skel->maps.stackmap);
+	if (!ASSERT_GE(stackmap_fd, 0, "stackmap fd"))
+		goto out;
+
+	stack_amap_fd = bpf_map__fd(skel->maps.stack_amap);
+	if (!ASSERT_GE(stack_amap_fd, 0, "stack_amap fd"))
+		goto out;
+
+	skel->bss->pid = getpid();
+
+	err = stacktrace_map_skip__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto out;
+
+	/* give some time for bpf program run */
+	sleep(1);
+
+	/* disable stack trace collection */
+	skel->bss->control = 1;
+
+	/* for every element in stackid_hmap, we can find a corresponding one
+	 * in stackmap, and vise versa.
+	 */
+	err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
+	if (!ASSERT_OK(err, "compare_map_keys stackid_hmap vs. stackmap"))
+		goto out;
+
+	err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
+	if (!ASSERT_OK(err, "compare_map_keys stackmap vs. stackid_hmap"))
+		goto out;
+
+	stack_trace_len = TEST_STACK_DEPTH * sizeof(__u64);
+	err = compare_stack_ips(stackmap_fd, stack_amap_fd, stack_trace_len);
+	if (!ASSERT_OK(err, "compare_stack_ips stackmap vs. stack_amap"))
+		goto out;
+
+	if (!ASSERT_EQ(skel->bss->failed, 0, "skip_failed"))
+		goto out;
+
+out:
+	stacktrace_map_skip__destroy(skel);
+}