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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>
This commit is contained in:
Namhyung Kim 2022-09-08 16:01:50 -07:00 committed by Arnaldo Carvalho de Melo
parent 165da80296
commit 187c7723e4
1 changed files with 64 additions and 1 deletions
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65
tools/perf/tests/sigtrap.c
View File

@ -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;
}