Thanks jirka, I will check again, and I saw another crash after this
patch, so I need to debug again.
BR, Jackie Liu
Jiri Olsa <jo...@redhat.com> 于2021年2月26日周五 上午12:11写道：
>
> On Thu, Feb 25, 2021 at 02:25:30PM +0800, Jackie Liu wrote:
> > After install the libelf-dev package and compiling perf, kptr_restrict=2
> > and perf_event_paranoid=3 will cause perf top to crash, because the
> > value of /proc/kallsyms cannot be obtained, which leads to
> > info->jited_ksyms == NULL. In order to solve this problem, Add a
> > judgment before use.
> >
> > Suggested-by: Jiri Olsa <jo...@redhat.com>
> > Cc: Peter Zijlstra <pet...@infradead.org>
> > Cc: Ingo Molnar <mi...@redhat.com>
> > Cc: Arnaldo Carvalho de Melo <a...@kernel.org>
> > Cc: Mark Rutland <mark.rutl...@arm.com>
> > Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
> > Cc: Namhyung Kim <namhy...@kernel.org>
> > Signed-off-by: Jackie Liu <liuyu...@kylinos.cn>
> > ---
> > tools/perf/util/bpf-event.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> > index 57d58c81a5f8..b1ce2d189d37 100644
> > --- a/tools/perf/util/bpf-event.c
> > +++ b/tools/perf/util/bpf-event.c
> > @@ -225,6 +225,11 @@ static int perf_event__synthesize_one_bpf_prog(struct
> > perf_session *session,
> > perf_env__fetch_btf(env, info->btf_id, btf);
> > }
> >
> > + if (!info->jited_ksyms) {
> > + err = -1;
> > + goto out;
> > + }
> > +
>
> I think this check should be moved above, right after line:
>
> info = &info_linear->info;
>
> so we don't do those extra btf checks
>
> thanks,
> jirka
>
> > /* Synthesize PERF_RECORD_KSYMBOL */
> > for (i = 0; i < sub_prog_cnt; i++) {
> > __u32 *prog_lens = (__u32
> > *)(uintptr_t)(info->jited_func_lens);
> > --
> > 2.25.1
> >
>
