Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754168AbaJGORo (ORCPT ); Tue, 7 Oct 2014 10:17:44 -0400 Received: from mail-oi0-f46.google.com ([209.85.218.46]:52003 "EHLO mail-oi0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753122AbaJGORl (ORCPT ); Tue, 7 Oct 2014 10:17:41 -0400 MIME-Version: 1.0 In-Reply-To: <20141007140050.GB2256@redhat.com> References: <20141006083532.GA4850@quad> <8761fwh1nc.fsf@sejong.aot.lge.com> <20141007140050.GB2256@redhat.com> Date: Tue, 7 Oct 2014 16:17:41 +0200 Message-ID: Subject: Re: [PATCH v2] perf tools: fix off-by-one error in maps From: Stephane Eranian To: Arnaldo Carvalho de Melo Cc: Namhyung Kim , LKML , Jiri Olsa , Peter Zijlstra , "mingo@elte.hu" , David Ahern Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 7, 2014 at 4:00 PM, Arnaldo Carvalho de Melo wrote: > Em Tue, Oct 07, 2014 at 02:47:19PM +0900, Namhyung Kim escreveu: >> On Mon, 6 Oct 2014 10:35:32 +0200, Stephane Eranian wrote: >> > This patch fixes off-by-one errors in the management of maps. >> > A map is defined by start address and length as implemented by map__new(): > >> > map__init(map, type, start, start + len, pgoff, dso); > >> > map->start = addr; >> > map->end = end; > >> > Consequently, the actual address range is ]start; end[ >> > map->end is the first byte outside the range. This patch >> > fixes two bugs where upper bound checking was off-by-one. > >> > In V2, we fix map_groups__fixup_overlappings() some more >> > where map->start was off-by-one as reported by Jiri. > >> It seems we also need to fix maps__find(): > >> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c >> index b7090596ac50..107a8c90785b 100644 >> --- a/tools/perf/util/map.c >> +++ b/tools/perf/util/map.c >> @@ -752,7 +752,7 @@ struct map *maps__find(struct rb_root *maps, u64 ip) >> m = rb_entry(parent, struct map, rb_node); >> if (ip < m->start) >> p = &(*p)->rb_left; >> - else if (ip > m->end) >> + else if (ip >= m->end) >> p = &(*p)->rb_right; >> else >> return m; > > I keep thinking that this change is making things unclear. > > I.e. the _start_ of a map (map->start) is _in_ the map, and the _end_ > of a map (map->end) is _in_ the map as well. > > if (addr > m->end) > > is shorter than: > > if (addr >= m->end) > > "start" and "end" should have the same rule applied, i.e. if one is in, > the other is in as well. > It is okay but then we need to be consistent all across. This is not the case today. I mentioned the cases I ran into. > Etc. > > - Arnaldo -- 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/