Messages in this thread | | | Date | Wed, 14 Oct 2020 15:21:46 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH 7/9] perf tools: Add size to struct perf_record_header_build_id |
| |
On Wed, Oct 14, 2020 at 08:59:08AM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Oct 13, 2020 at 09:24:39PM +0200, Jiri Olsa escreveu: > > We do not store size with build ids in perf data, > > but there's enough space to do it. Adding misc bit > > PERF_RECORD_MISC_BUILD_ID_SIZE to mark build id event > > with size. > > > > With this fix the dso with md5 build id will have correct > > build id data and will be usable for debuginfod processing > > if needed (coming in following patches). > > > > Acked-by: Ian Rogers <irogers@google.com> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > tools/lib/perf/include/perf/event.h | 12 +++++++++++- > > tools/perf/util/build-id.c | 8 +++++--- > > tools/perf/util/header.c | 10 +++++++--- > > 3 files changed, 23 insertions(+), 7 deletions(-) > > > > diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h > > index a6dbba6b9073..988c539bedb6 100644 > > --- a/tools/lib/perf/include/perf/event.h > > +++ b/tools/lib/perf/include/perf/event.h > > @@ -201,10 +201,20 @@ struct perf_record_header_tracing_data { > > __u32 size; > > }; > > > > +#define PERF_RECORD_MISC_BUILD_ID_SIZE (1 << 15) > > + > > struct perf_record_header_build_id { > > struct perf_event_header header; > > pid_t pid; > > - __u8 build_id[24]; > > + union { > > + __u8 build_id[24]; > > + struct { > > + __u8 data[20]; > > + __u8 size; > > + __u8 reserved1__; > > + __u16 reserved2__; > > + }; > > + }; > > char filename[]; > > }; > > Hey, shouldn't we just append the extra info at the end, i.e. keep it > like: > > struct perf_record_header_build_id { > struct perf_event_header header; > pid_t pid; > __u8 build_id[24]; > char filename[]; > __u8 size; > }; > > > No need for PERF_RECORD_MISC_BUILD_ID_SIZE, older tools will continue > working with new perf data files.
hum, then how would we tell if the last byte (size) is present or not?
> > OTOH BUILD_ID_SIZE is 20 and the space on this header is 24, so the last > 4 bytes were not being used, so older tools don't look into it, they > should continue working, have you tested this case? I.e. getting the > perf binary in, say, fedora and check that it works with this new > perf_record_header_build_id layout?
yes, that still works (tested), because we copied only 20 bytes of the build_id[24] and did not care about the rest
jirka
| |