Re: [PATCH] perf parse-events: report bpf errors

[Ian Rogers <irogers@google.com>]

On Wed, Jul 8, 2020 at 4:19 AM Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
> Em Tue, Jul 07, 2020 at 02:14:49PM -0700, Ian Rogers escreveu:
> > Setting the parse_events_error directly doesn't increment num_errors
> > causing the error message not to be displayed. Use the
> > parse_events__handle_error function that sets num_errors and handle
> > multiple errors.
>
> What was the command line you used to exercise the error and then the
> fix?

You need something to stand in for the BPF event so:

Before:
```
$ /tmp/perf/perf record -e /tmp/perf/util/parse-events.o
Run 'perf list' for a list of valid events

Usage: perf record [<options>] [<command>]
   or: perf record [<options>] -- <command> [<options>]

   -e, --event <event>   event selector. use 'perf list' to list available event
```
After:
```
$ /tmp/perf/perf record -e /tmp/perf/util/parse-events.o
event syntax error: '/tmp/perf/util/parse-events.o'
                    \___ Failed to load /tmp/perf/util/parse-events.o:
BPF object format invalid

(add -v to see detail)
Run 'perf list' for a list of valid events

Usage: perf record [<options>] [<command>]
   or: perf record [<options>] -- <command> [<options>]

   -e, --event <event>   event selector. use 'perf list' to list
available events
```

Thanks,
Ian

> - Arnaldo
>
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/util/parse-events.c | 38 ++++++++++++++++++----------------
> >  1 file changed, 20 insertions(+), 18 deletions(-)
> >
> > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> > index c4906a6a9f1a..e88e4c7a2a9a 100644
> > --- a/tools/perf/util/parse-events.c
> > +++ b/tools/perf/util/parse-events.c
> > @@ -767,8 +767,8 @@ int parse_events_load_bpf_obj(struct parse_events_state *parse_state,
> >
> >       return 0;
> >  errout:
> > -     parse_state->error->help = strdup("(add -v to see detail)");
> > -     parse_state->error->str = strdup(errbuf);
> > +     parse_events__handle_error(parse_state->error, 0,
> > +                             strdup(errbuf), strdup("(add -v to see detail)"));
> >       return err;
> >  }
> >
> > @@ -784,36 +784,38 @@ parse_events_config_bpf(struct parse_events_state *parse_state,
> >               return 0;
> >
> >       list_for_each_entry(term, head_config, list) {
> > -             char errbuf[BUFSIZ];
> >               int err;
> >
> >               if (term->type_term != PARSE_EVENTS__TERM_TYPE_USER) {
> > -                     snprintf(errbuf, sizeof(errbuf),
> > -                              "Invalid config term for BPF object");
> > -                     errbuf[BUFSIZ - 1] = '\0';
> > -
> > -                     parse_state->error->idx = term->err_term;
> > -                     parse_state->error->str = strdup(errbuf);
> > +                     parse_events__handle_error(parse_state->error, term->err_term,
> > +                                             strdup("Invalid config term for BPF object"),
> > +                                             NULL);
> >                       return -EINVAL;
> >               }
> >
> >               err = bpf__config_obj(obj, term, parse_state->evlist, &error_pos);
> >               if (err) {
> > +                     char errbuf[BUFSIZ];
> > +                     int idx;
> > +
> >                       bpf__strerror_config_obj(obj, term, parse_state->evlist,
> >                                                &error_pos, err, errbuf,
> >                                                sizeof(errbuf));
> > -                     parse_state->error->help = strdup(
> > +
> > +                     if (err == -BPF_LOADER_ERRNO__OBJCONF_MAP_VALUE)
> > +                             idx = term->err_val;
> > +                     else
> > +                             idx = term->err_term + error_pos;
> > +
> > +                     parse_events__handle_error(parse_state->error, idx,
> > +                                             strdup(errbuf),
> > +                                             strdup(
> >  "Hint:\tValid config terms:\n"
> >  "     \tmap:[<arraymap>].value<indices>=[value]\n"
> >  "     \tmap:[<eventmap>].event<indices>=[event]\n"
> >  "\n"
> >  "     \twhere <indices> is something like [0,3...5] or [all]\n"
> > -"     \t(add -v to see detail)");
> > -                     parse_state->error->str = strdup(errbuf);
> > -                     if (err == -BPF_LOADER_ERRNO__OBJCONF_MAP_VALUE)
> > -                             parse_state->error->idx = term->err_val;
> > -                     else
> > -                             parse_state->error->idx = term->err_term + error_pos;
> > +"     \t(add -v to see detail)"));
> >                       return err;
> >               }
> >       }
> > @@ -877,8 +879,8 @@ int parse_events_load_bpf(struct parse_events_state *parse_state,
> >                                                  -err, errbuf,
> >                                                  sizeof(errbuf));
> >
> > -             parse_state->error->help = strdup("(add -v to see detail)");
> > -             parse_state->error->str = strdup(errbuf);
> > +             parse_events__handle_error(parse_state->error, 0,
> > +                                     strdup(errbuf), strdup("(add -v to see detail)"));
> >               return err;
> >       }
> >
> > --
> > 2.27.0.383.g050319c2ae-goog
> >
>
> --
>
> - Arnaldo