From 187c7723e4aae6d5729e27179542956975624ff8 Mon Sep 17 00:00:00 2001
From: Namhyung Kim <namhyung@kernel.org>
Date: Thu, 8 Sep 2022 16:01:50 -0700
Subject: [PATCH] perf test: Skip sigtrap test on old kernels
If it runs on an old kernel, perf_event_open would fail because of the
new fields sigtrap and sig_data. Just skipping the test could miss an
actual bug in the kernel.
Let's check BTF (when we have libbpf) if it has the sigtrap field in the
perf_event_attr. Otherwise, we can check it with a minimal event config.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Suggested-by: Arnaldo Carvalho de Melo <acme@redhat.com> # Using BTF to check for the struct members
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220908230150.4105955-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/tests/sigtrap.c | 65 +++++++++++++++++++++++++++++++++++++-
1 file changed, 64 insertions(+), 1 deletion(-)
diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
index e32ece90e164a..1de7478ec1894 100644
--- a/tools/perf/tests/sigtrap.c
+++ b/tools/perf/tests/sigtrap.c
@@ -54,6 +54,63 @@ static struct perf_event_attr make_event_attr(void)
return attr;
}
+#ifdef HAVE_BPF_SKEL
+#include <bpf/btf.h>
+
+static bool attr_has_sigtrap(void)
+{
+ bool ret = false;
+ struct btf *btf;
+ const struct btf_type *t;
+ const struct btf_member *m;
+ const char *name;
+ int i, id;
+
+ btf = btf__load_vmlinux_btf();
+ if (btf == NULL) {
+ /* should be an old kernel */
+ return false;
+ }
+
+ id = btf__find_by_name_kind(btf, "perf_event_attr", BTF_KIND_STRUCT);
+ if (id < 0)
+ goto out;
+
+ t = btf__type_by_id(btf, id);
+ for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
+ name = btf__name_by_offset(btf, m->name_off);
+ if (!strcmp(name, "sigtrap")) {
+ ret = true;
+ break;
+ }
+ }
+out:
+ btf__free(btf);
+ return ret;
+}
+#else /* !HAVE_BPF_SKEL */
+static bool attr_has_sigtrap(void)
+{
+ struct perf_event_attr attr = {
+ .type = PERF_TYPE_SOFTWARE,
+ .config = PERF_COUNT_SW_DUMMY,
+ .size = sizeof(attr),
+ .remove_on_exec = 1, /* Required by sigtrap. */
+ .sigtrap = 1, /* Request synchronous SIGTRAP on event. */
+ };
+ int fd;
+ bool ret = false;
+
+ fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
+ if (fd >= 0) {
+ ret = true;
+ close(fd);
+ }
+
+ return ret;
+}
+#endif /* HAVE_BPF_SKEL */
+
static void
sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
{
@@ -139,7 +196,13 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
if (fd < 0) {
- pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
+ if (attr_has_sigtrap()) {
+ pr_debug("FAILED sys_perf_event_open(): %s\n",
+ str_error_r(errno, sbuf, sizeof(sbuf)));
+ } else {
+ pr_debug("perf_event_attr doesn't have sigtrap\n");
+ ret = TEST_SKIP;
+ }
goto out_restore_sigaction;
}
--
2.30.2