perf trace: Dump stack on segfaults

  [root@ssdandy ~]# perf trace --filter-pids 16348
     0.000 ( 0.000 ms): tuned/1027  ... [continued]: select()) = 0 Timeout
   793.770 ( 0.000 ms): lsmd/895  ... [continued]: select()) = 0 Timeout
   793.775 (793.724 ms): tuned/1027 select(tvp: 0x7f7655556e50) ...
  perf: Segmentation fault
  Obtained 15 stack frames.
  perf(dump_stack+0x2e) [0x4ed330]
  perf(sighandler_dump_stack+0x2e) [0x4ed40f]
  /lib64/libc.so.6(+0x35640) [0x7fa2d5b69640]
  perf() [0x4c2d35]
  perf(machine__findnew_thread+0x39) [0x4c2ed6]
  perf() [0x454a4d]
  perf() [0x455f87]
  perf() [0x456556]
  perf(cmd_trace+0xa7e) [0x4580af]
  perf() [0x4867bd]
  perf() [0x486a1c]
  perf() [0x486b68]
  perf(main+0x23b) [0x486ec9]
  /lib64/libc.so.6(__libc_start_main+0xf5) [0x7fa2d5b55af5]
  perf() [0x41bd91]
[  root@ssdandy ~]#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-v38cbxcnm2yf5qn9u4y4n9ab@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -2660,6 +2660,9 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 	int err;
 	char bf[BUFSIZ];
 
+	signal(SIGSEGV, sighandler_dump_stack);
+	signal(SIGFPE, sighandler_dump_stack);
+
 	trace.evlist = perf_evlist__new();
 	if (trace.evlist == NULL)
 		return -ENOMEM;