Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758167Ab2EaNqF (ORCPT ); Thu, 31 May 2012 09:46:05 -0400 Received: from mail-vb0-f46.google.com ([209.85.212.46]:54699 "EHLO mail-vb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757948Ab2EaNqD (ORCPT ); Thu, 31 May 2012 09:46:03 -0400 Date: Thu, 31 May 2012 10:45:57 -0300 From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Peter Zijlstra , Paul Mackerras , Ingo Molnar , Namhyung Kim , LKML , Sunjin Yang Subject: Re: [PATCH/RFC 2/2] perf tools: Check callchain is corrupted Message-ID: <20120531134557.GB13591@infradead.org> References: <1338443007-24857-1-git-send-email-namhyung.kim@lge.com> <1338443007-24857-2-git-send-email-namhyung.kim@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338443007-24857-2-git-send-email-namhyung.kim@lge.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2699 Lines: 82 Em Thu, May 31, 2012 at 02:43:27PM +0900, Namhyung Kim escreveu: > We faced segmentation fault on perf top -G at very high sampling > rate due to a corrupted callchain. While the root cause was not > revealed (I failed to figure it out), this patch tries to protect > us from the segfault on such cases. Capping the callchain lenght may even be a feature, not a consistency check, but I don't know how long, for consistency checking, we should consider too much, as there are cases of loooong callchains. Ingo? Peter? - Arnaldo > Reported-by: Arnaldo Carvalho de Melo > Signed-off-by: Namhyung Kim > --- > include/linux/perf_event.h | 4 ++-- > tools/perf/util/session.c | 14 +++++++++++++- > 2 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 8adf70e9e3cc..0430ea6054ef 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -555,6 +555,8 @@ enum perf_event_type { > PERF_RECORD_MAX, /* non-ABI */ > }; > > +#define PERF_MAX_STACK_DEPTH 255 > + > enum perf_callchain_context { > PERF_CONTEXT_HV = (__u64)-32, > PERF_CONTEXT_KERNEL = (__u64)-128, > @@ -609,8 +611,6 @@ struct perf_guest_info_callbacks { > #include > #include > > -#define PERF_MAX_STACK_DEPTH 255 > - > struct perf_callchain_entry { > __u64 nr; > __u64 ip[PERF_MAX_STACK_DEPTH]; > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index a7de2acac460..fa14e60ed459 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -300,6 +300,11 @@ int machine__resolve_callchain(struct machine *self, > > callchain_cursor_reset(&callchain_cursor); > > + if (chain->nr > PERF_MAX_STACK_DEPTH) { > + pr_warning("corrupted callchain. skipping...\n"); > + return 0; > + } > + > for (i = 0; i < chain->nr; i++) { > u64 ip; > struct addr_location al; > @@ -318,7 +323,14 @@ int machine__resolve_callchain(struct machine *self, > case PERF_CONTEXT_USER: > cpumode = PERF_RECORD_MISC_USER; break; > default: > - break; > + pr_debug("invalid callchain context: " > + "%"PRId64"\n", (s64) ip); > + /* > + * It seems the callchain is corrupted. > + * Discard all. > + */ > + callchain_cursor_reset(&callchain_cursor); > + return 0; > } > continue; > } > -- > 1.7.10.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/