linux-kernel - [PATCH 3/5] perf kwork: Constify control data for BPF

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Message-ID: <20240902200515.2103769-4-namhyung@kernel.org>
Date: Mon,  2 Sep 2024 13:05:13 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Kan Liang <kan.liang@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>,
	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,
	Song Liu <song@...nel.org>,
	bpf@...r.kernel.org,
	Yang Jihong <yangjihong@...edance.com>
Subject: [PATCH 3/5] perf kwork: Constify control data for BPF

The control knobs set before loading BPF programs should be declared as
'const volatile' so that it can be optimized by the BPF core.

Cc: Yang Jihong <yangjihong@...edance.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/bpf_kwork.c                | 9 +++++----
 tools/perf/util/bpf_kwork_top.c            | 7 ++++---
 tools/perf/util/bpf_skel/kwork_top.bpf.c   | 2 +-
 tools/perf/util/bpf_skel/kwork_trace.bpf.c | 5 +++--
 4 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/tools/perf/util/bpf_kwork.c b/tools/perf/util/bpf_kwork.c
index 44f0f708a15d6a14..6c7126b7670dd0c9 100644
--- a/tools/perf/util/bpf_kwork.c
+++ b/tools/perf/util/bpf_kwork.c
@@ -176,8 +176,6 @@ static int setup_filters(struct perf_kwork *kwork)
 			bpf_map_update_elem(fd, &cpu.cpu, &val, BPF_ANY);
 		}
 		perf_cpu_map__put(map);
-
-		skel->bss->has_cpu_filter = 1;
 	}
 
 	if (kwork->profile_name != NULL) {
@@ -197,8 +195,6 @@ static int setup_filters(struct perf_kwork *kwork)
 
 		key = 0;
 		bpf_map_update_elem(fd, &key, kwork->profile_name, BPF_ANY);
-
-		skel->bss->has_name_filter = 1;
 	}
 
 	return 0;
@@ -239,6 +235,11 @@ int perf_kwork__trace_prepare_bpf(struct perf_kwork *kwork)
 			class_bpf->load_prepare(kwork);
 	}
 
+	if (kwork->cpu_list != NULL)
+		skel->rodata->has_cpu_filter = 1;
+	if (kwork->profile_name != NULL)
+		skel->rodata->has_name_filter = 1;
+
 	if (kwork_trace_bpf__load(skel)) {
 		pr_debug("Failed to load kwork trace skeleton\n");
 		goto out;
diff --git a/tools/perf/util/bpf_kwork_top.c b/tools/perf/util/bpf_kwork_top.c
index 22a3b00a1e23f929..7261cad43468d7a4 100644
--- a/tools/perf/util/bpf_kwork_top.c
+++ b/tools/perf/util/bpf_kwork_top.c
@@ -151,14 +151,12 @@ static int setup_filters(struct perf_kwork *kwork)
 			bpf_map_update_elem(fd, &cpu.cpu, &val, BPF_ANY);
 		}
 		perf_cpu_map__put(map);
-
-		skel->bss->has_cpu_filter = 1;
 	}
 
 	return 0;
 }
 
-int perf_kwork__top_prepare_bpf(struct perf_kwork *kwork __maybe_unused)
+int perf_kwork__top_prepare_bpf(struct perf_kwork *kwork)
 {
 	struct bpf_program *prog;
 	struct kwork_class *class;
@@ -193,6 +191,9 @@ int perf_kwork__top_prepare_bpf(struct perf_kwork *kwork __maybe_unused)
 			class_bpf->load_prepare();
 	}
 
+	if (kwork->cpu_list)
+		skel->rodata->has_cpu_filter = 1;
+
 	if (kwork_top_bpf__load(skel)) {
 		pr_debug("Failed to load kwork top skeleton\n");
 		goto out;
diff --git a/tools/perf/util/bpf_skel/kwork_top.bpf.c b/tools/perf/util/bpf_skel/kwork_top.bpf.c
index 84c15ccbab44ccc9..594da91965a2f6c9 100644
--- a/tools/perf/util/bpf_skel/kwork_top.bpf.c
+++ b/tools/perf/util/bpf_skel/kwork_top.bpf.c
@@ -84,7 +84,7 @@ struct {
 
 int enabled = 0;
 
-int has_cpu_filter = 0;
+const volatile int has_cpu_filter = 0;
 
 __u64 from_timestamp = 0;
 __u64 to_timestamp = 0;
diff --git a/tools/perf/util/bpf_skel/kwork_trace.bpf.c b/tools/perf/util/bpf_skel/kwork_trace.bpf.c
index 063c124e099938ed..cbd79bc4b3302d81 100644
--- a/tools/perf/util/bpf_skel/kwork_trace.bpf.c
+++ b/tools/perf/util/bpf_skel/kwork_trace.bpf.c
@@ -68,8 +68,9 @@ struct {
 } perf_kwork_name_filter SEC(".maps");
 
 int enabled = 0;
-int has_cpu_filter = 0;
-int has_name_filter = 0;
+
+const volatile int has_cpu_filter = 0;
+const volatile int has_name_filter = 0;
 
 static __always_inline int local_strncmp(const char *s1,
 					 unsigned int sz, const char *s2)
-- 
2.46.0.469.g59c65b2a67-goog