From 187c7723e4aae6d5729e27179542956975624ff8 Mon Sep 17 00:00:00 2001 From: Namhyung Kim 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 Acked-by: Song Liu Suggested-by: Arnaldo Carvalho de Melo # Using BTF to check for the struct members Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Marco Elver Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20220908230150.4105955-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- 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 e32ece9..1de7478 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 + +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; } -- 2.7.4