Messages in this thread | | | Date | Tue, 7 Oct 2014 16:17:41 +0200 | Subject | Re: [PATCH v2] perf tools: fix off-by-one error in maps | From | Stephane Eranian <> |
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On Tue, Oct 7, 2014 at 4:00 PM, Arnaldo Carvalho de Melo <acme@redhat.com> 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
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