Re: [PATCH 16/19] selftests/bpf: Add fentry multi func test

On Tue, Jun 08, 2021 at 10:40:24PM -0700, Andrii Nakryiko wrote:

On Sat, Jun 5, 2021 at 4:12 AM Jiri Olsa [off-list ref] wrote:

quoted

Adding selftest for fentry multi func test that attaches
to bpf_fentry_test* functions and checks argument values
based on the processed function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/multi_check.h     | 52 +++++++++++++++++++
 .../bpf/prog_tests/fentry_multi_test.c        | 43 +++++++++++++++
 .../selftests/bpf/progs/fentry_multi_test.c   | 18 +++++++
 3 files changed, 113 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/multi_check.h
 create mode 100644 tools/testing/selftests/bpf/prog_tests/fentry_multi_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/fentry_multi_test.c

diff --git a/tools/testing/selftests/bpf/multi_check.h b/tools/testing/selftests/bpf/multi_check.h
new file mode 100644
index 000000000000..36c2a93f9be3
--- /dev/null
+++ b/tools/testing/selftests/bpf/multi_check.h

we have a proper static linking now, we don't have to use header
inclusion hacks, let's do this properly?

ok, will change

quoted

@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __MULTI_CHECK_H
+#define __MULTI_CHECK_H
+
+extern unsigned long long bpf_fentry_test[8];
+
+static __attribute__((unused)) inline
+void multi_arg_check(unsigned long ip, __u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 f, __u64 *test_result)
+{
+       if (ip == bpf_fentry_test[0]) {
+               *test_result += (int) a == 1;
+       } else if (ip == bpf_fentry_test[1]) {
+               *test_result += (int) a == 2 && (__u64) b == 3;
+       } else if (ip == bpf_fentry_test[2]) {
+               *test_result += (char) a == 4 && (int) b == 5 && (__u64) c == 6;
+       } else if (ip == bpf_fentry_test[3]) {
+               *test_result += (void *) a == (void *) 7 && (char) b == 8 && (int) c == 9 && (__u64) d == 10;
+       } else if (ip == bpf_fentry_test[4]) {
+               *test_result += (__u64) a == 11 && (void *) b == (void *) 12 && (short) c == 13 && (int) d == 14 && (__u64) e == 15;
+       } else if (ip == bpf_fentry_test[5]) {
+               *test_result += (__u64) a == 16 && (void *) b == (void *) 17 && (short) c == 18 && (int) d == 19 && (void *) e == (void *) 20 && (__u64) f == 21;
+       } else if (ip == bpf_fentry_test[6]) {
+               *test_result += 1;
+       } else if (ip == bpf_fentry_test[7]) {
+               *test_result += 1;
+       }

why not use switch? and why the casting?

hum, for switch I'd need constants right? 

casting is extra ;-) wanted to check the actual argument types,
but probably makes no sense

will check

quoted

+}
+

[...]

quoted

diff --git a/tools/testing/selftests/bpf/progs/fentry_multi_test.c b/tools/testing/selftests/bpf/progs/fentry_multi_test.c
new file mode 100644
index 000000000000..a443fc958e5a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fentry_multi_test.c

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "multi_check.h"
+
+char _license[] SEC("license") = "GPL";
+
+unsigned long long bpf_fentry_test[8];
+
+__u64 test_result = 0;
+
+SEC("fentry.multi/bpf_fentry_test*")

wait, that's a regexp syntax that libc supports?.. Not .*? We should
definitely not provide btf__find_by_pattern_kind() API, I'd like to
avoid explaining what flavors of regexps libbpf supports.

ok

thanks,
jirka