perf test sigtrap: Print errno string when failing
Helps a bit the user figuring out why it is failing:
Before:
$ perf test sigtrap
73: Sigtrap : FAILED!
$ perf test -v sigtrap
73: Sigtrap :
--- start ---
test child forked, pid 3816772
FAILED sys_perf_event_open()
test child finished with -1
---- end ----
Sigtrap: FAILED!
$
After:
$ perf test sigtrap
73: Sigtrap : FAILED!
$ perf test -v sigtrap
73: Sigtrap :
--- start ---
test child forked, pid 3816772
FAILED sys_perf_event_open(): Permission denied
test child finished with -1
---- end ----
Sigtrap: FAILED!
$
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Fabian Hemmer <copy@copy.sh>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kasan-dev@googlegroups.com
Link: http://lore.kernel.org/lkml/YZOpSVOCXe0zWeRs@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>