From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755850Ab2GAWQf (ORCPT ); Sun, 1 Jul 2012 18:16:35 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:51529 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753803Ab2GAWQe (ORCPT ); Sun, 1 Jul 2012 18:16:34 -0400 Message-ID: <4FF0CC3E.8010303@gmail.com> Date: Sun, 01 Jul 2012 16:16:30 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: psuriset@linux.vnet.ibm.com, Arnaldo Carvalho de Melo CC: linux-kernel@vger.kernel.org, Ingo Molnar , Jiri Olsa , Namhyung Kim , Frederic Weisbecker , Peter Zijlstra Subject: Re: [PATCH] perf kvm: fix segfault with default guest arguments References: <1340599286-89757-1-git-send-email-dsahern@gmail.com> In-Reply-To: <1340599286-89757-1-git-send-email-dsahern@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnaldo: Please ignore this one in favor of the patch I just sent -- 'perf kvm: fix regression with guest machine creation'. On 6/24/12 10:41 PM, David Ahern wrote: > (This time with actual backtrace; forgot to remove the leading '#' on the frames.) > > File generated with: > $ perf kvm --host --guest --guestkallsyms=/tmp/guest-kallsyms > --guestmodules=/tmp/guest-modules record -a > > The report command: > $ perf kvm --host --guest --guestkallsyms=/tmp/guest-kallsyms > --guestmodules=/tmp/guest-modules report > > dies with a SEGFAULT: > Program received signal SIGSEGV, Segmentation fault. > 0x000000000046dd7b in machine__mmap_name (self=0x0, bf=0x7fffffffbd20 "q\021", size=4096) at util/map.c:715 > 715 snprintf(bf, size, "[%s.%d]", "guest.kernel.kallsyms", self->pid); > > (gdb) bt > 0 0x000000000046dd7b in machine__mmap_name (self=0x0, bf=0x7fffffffbd20 "q\021", size=4096) at util/map.c:715 > 1 0x0000000000444161 in perf_event__process_kernel_mmap (tool=0x7fffffffdd80, event=0x7ffff7fb4120, machine=0x0) at util/event.c:562 > 2 0x0000000000444642 in perf_event__process_mmap (tool=0x7fffffffdd80, event=0x7ffff7fb4120, sample=0x7fffffffd210, machine=0x0) > at util/event.c:668 > 3 0x0000000000470e0b in perf_session_deliver_event (session=0x915ca0, event=0x7ffff7fb4120, sample=0x7fffffffd210, tool=0x7fffffffdd80, > file_offset=8480) at util/session.c:979 > 4 0x000000000047032e in flush_sample_queue (s=0x915ca0, tool=0x7fffffffdd80) at util/session.c:679 > 5 0x0000000000471c8d in __perf_session__process_events (session=0x915ca0, data_offset=400, data_size=150448, file_size=150848, tool= > 0x7fffffffdd80) at util/session.c:1363 > 6 0x0000000000471d42 in perf_session__process_events (self=0x915ca0, tool=0x7fffffffdd80) at util/session.c:1379 > 7 0x000000000042484a in __cmd_report (rep=0x7fffffffdd80) at builtin-report.c:368 > 8 0x0000000000425bf1 in cmd_report (argc=0, argv=0x915b00, prefix=0x0) at builtin-report.c:756 > 9 0x0000000000438505 in __cmd_report (argc=4, argv=0x7fffffffe260) at builtin-kvm.c:84 > 10 0x000000000043882a in cmd_kvm (argc=4, argv=0x7fffffffe260, prefix=0x0) at builtin-kvm.c:131 > 11 0x00000000004152cd in run_builtin (p=0x7a54e8, argc=9, argv=0x7fffffffe260) at perf.c:273 > 12 0x00000000004154c7 in handle_internal_command (argc=9, argv=0x7fffffffe260) at perf.c:345 > 13 0x0000000000415613 in run_argv (argcp=0x7fffffffe14c, argv=0x7fffffffe140) at perf.c:389 > 14 0x0000000000415899 in main (argc=9, argv=0x7fffffffe260) at perf.c:487 > > If no samples hit within a guest module then no build id events are written > to the header during the record. On the report side this cases no 'machine' > to be generated for the default guest (pid == 0) leading to a > machine == NULL in perf_session_deliver_event. > > perf's handling of default kallsyms and guest-modules needs to be reworked. > Until then perf should at least not segfault. > > Reported-by: Pradeep Kumar Surisetty > CC: Arnaldo Carvalho de Melo > Cc: Ingo Molnar > Cc: Jiri Olsa > Cc: Namhyung Kim > Cc: Frederic Weisbecker > Cc: Peter Zijlstra > Signed-off-by: David Ahern > > Signed-off-by: David Ahern > --- > tools/perf/util/session.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index c3e399b..3999d5e 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -976,6 +976,8 @@ static int perf_session_deliver_event(struct perf_session *session, > } > return tool->sample(tool, event, sample, evsel, machine); > case PERF_RECORD_MMAP: > + if (machine == NULL) > + return 0; > return tool->mmap(tool, event, sample, machine); > case PERF_RECORD_COMM: > return tool->comm(tool, event, sample, machine); >