Messages in this thread | | | From | JackieLiu <> | Date | Fri, 26 Feb 2021 08:54:19 +0800 | Subject | Re: [PATCH v2] perf tools: perf_event_paranoid and kptr_restrict may crash on 'perf top' |
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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 <jolsa@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 <jolsa@redhat.com> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Ingo Molnar <mingo@redhat.com> > > Cc: Arnaldo Carvalho de Melo <acme@kernel.org> > > Cc: Mark Rutland <mark.rutland@arm.com> > > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> > > Cc: Namhyung Kim <namhyung@kernel.org> > > Signed-off-by: Jackie Liu <liuyun01@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 > > >
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