Messages in this thread | | | Date | Mon, 20 Jun 2022 21:54:24 +0300 | Subject | Re: [PATCH] perf: Adjust perf-inject output data offset for backward compatibility | From | Adrian Hunter <> |
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On 20/06/22 19:49, Raul Silvera wrote: > When perf inject creates a new file, it reuses the data offset from the > input file. If there has been a change on the size of the header, as > happened in v5.12 -> v5.13, the new offsets will be wrong, resulting in > a corrupted output file. > > This change adds the function perf_session__data_offset to compute the > data offset based on the current header size, and uses that instead of > the offset from the original input file. > > Signed-off-by: Raul Silvera <rsilvera@google.com> > --- > tools/perf/builtin-inject.c | 2 +- > tools/perf/util/header.c | 16 +++++++++++++++- > tools/perf/util/header.h | 2 ++ > 3 files changed, 18 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c > index a75bf11585b5..1dfdcef36607 100644 > --- a/tools/perf/builtin-inject.c > +++ b/tools/perf/builtin-inject.c > @@ -916,7 +916,7 @@ static int __cmd_inject(struct perf_inject *inject) > inject->tool.tracing_data = perf_event__repipe_tracing_data; > } > > - output_data_offset = session->header.data_offset; > + output_data_offset = perf_session__data_offset(session->evlist); > > if (inject->build_id_all) { > inject->tool.mmap = perf_event__repipe_buildid_mmap; > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c > index 53332da100e8..93706ae827f1 100644 > --- a/tools/perf/util/header.c > +++ b/tools/perf/util/header.c > @@ -3660,7 +3660,7 @@ static int perf_session__do_write_header(struct perf_session *session, > .size = evlist->core.nr_entries * sizeof(f_attr), > }, > .data = { > - .offset = header->data_offset, > + .offset = attr_offset + evlist->core.nr_entries * sizeof(f_attr),
This looks too late since, although the header comes before the data, it also gets written afterwards (at_exit == true). It would be better if we could rely on header->data_offset at this point.
> .size = header->data_size, > }, > /* event_types is ignored, store zeros */ > @@ -3686,6 +3686,20 @@ int perf_session__write_header(struct perf_session *session, > return perf_session__do_write_header(session, evlist, fd, at_exit, NULL); > } > > +size_t perf_session__data_offset(const struct evlist *evlist) > +{ > + struct evsel *evsel; > + size_t data_offset; > + > + data_offset = sizeof(struct perf_file_header); > + evlist__for_each_entry(evlist, evsel) { > + data_offset += evsel->core.ids * sizeof(u64); > + } > + data_offset += evlist->core.nr_entries * sizeof(struct perf_file_attr); > + > + return data_offset; > +} > + > int perf_session__inject_header(struct perf_session *session, > struct evlist *evlist, > int fd, > diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h > index 08563c1f1bff..56916dabce7b 100644 > --- a/tools/perf/util/header.h > +++ b/tools/perf/util/header.h > @@ -136,6 +136,8 @@ int perf_session__inject_header(struct perf_session *session, > int fd, > struct feat_copier *fc); > > +size_t perf_session__data_offset(const struct evlist *evlist); > + > void perf_header__set_feat(struct perf_header *header, int feat); > void perf_header__clear_feat(struct perf_header *header, int feat); > bool perf_header__has_feat(const struct perf_header *header, int feat);
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