[PATCH] perf tools: check perf_event_paranoid and kptr_restrict on 'perf top'

Jackie Liu
2021-02-23T06:29:23Z

Perf top will segfault, we should give prompt information like perf
record instead of crashing directly.

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: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
---
tools/perf/builtin-top.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 3673c04d16b6..b257fadba3bd 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1239,6 +1239,14 @@ static int __cmd_top(struct perf_top *top)
return ret;
}

+ if (symbol_conf.kptr_restrict && !evlist__exclude_kernel(top->evlist)) {
+ pr_warning(
+"Kernel address maps (/proc/{kallsyms,modules}) are restricted.\n\n"
+"Check /proc/sys/kernel/kptr_restrict and /proc/sys/kernel/perf_event_paranoid.\n\n"
+"Kernel samples will not be resolved.\n");
+ return -1;
+ }
+
ret = callchain_param__setup_sample_type(&callchain_param);
if (ret)
return ret;
--
2.25.1