linux-kernel - [PATCH 1/2] perf bpf-filter: Fix sample flag check with ||

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Message-ID: <20230811025822.3859771-1-namhyung@kernel.org>
Date:   Thu, 10 Aug 2023 19:58:21 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-perf-users@...r.kernel.org
Subject: [PATCH 1/2] perf bpf-filter: Fix sample flag check with ||

For logical OR operator, the actual sample_flags are in the 'groups'
list so it needs to check entries in the list instead.  Otherwise it
would show the following error message.

  $ sudo perf record -a -e cycles:p --filter 'period > 100 || weight > 0' sleep 1
  Error: cycles:p event does not have sample flags 0
  failed to set filter "BPF" on event cycles:p with 2 (No such file or directory)

Actually it should warn on 'weight' is used without WEIGHT flag.

  Error: cycles:p event does not have PERF_SAMPLE_WEIGHT
   Hint: please add -W option to perf record
  failed to set filter "BPF" on event cycles:p with 2 (No such file or directory)

Fixes: 4310551b76e0 ("perf bpf filter: Show warning for missing sample flags")
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/bpf-filter.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/perf/util/bpf-filter.c b/tools/perf/util/bpf-filter.c
index 47f01df658d9..b51544996046 100644
--- a/tools/perf/util/bpf-filter.c
+++ b/tools/perf/util/bpf-filter.c
@@ -62,6 +62,16 @@ static int check_sample_flags(struct evsel *evsel, struct perf_bpf_filter_expr *
 	if (evsel->core.attr.sample_type & expr->sample_flags)
 		return 0;
 
+	if (expr->op == PBF_OP_GROUP_BEGIN) {
+		struct perf_bpf_filter_expr *group;
+
+		list_for_each_entry(group, &expr->groups, list) {
+			if (check_sample_flags(evsel, group) < 0)
+				return -1;
+		}
+		return 0;
+	}
+
 	info = get_sample_info(expr->sample_flags);
 	if (info == NULL) {
 		pr_err("Error: %s event does not have sample flags %lx\n",
-- 
2.41.0.640.ga95def55d0-goog