Commit 187c7723 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarSong 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 165da802

tools/perf/tests/sigtrap.c

+64 −1
Original line number Diff line number Diff line
@@ -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;

	}