linux-kernel - [PATCH 5/6] perf lock contention: Support lock addr/name filtering for BPF

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Date:   Mon, 19 Dec 2022 12:17:31 -0800
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, Song Liu <song@...nel.org>,
        Blake Jones <blakejones@...gle.com>, bpf@...r.kernel.org
Subject: [PATCH 5/6] perf lock contention: Support lock addr/name filtering for BPF

Likewise, add addr_filter BPF hash map and check it with the lock
address.

  $ sudo ./perf lock con -ab -L tasklist_lock -- ./perf bench sched messaging
  # Running 'sched/messaging' benchmark:
  # 20 sender and receiver processes per group
  # 10 groups == 400 processes run

       Total time: 0.169 [sec]
   contended   total wait     max wait     avg wait         type   caller

          18    174.09 us     25.31 us      9.67 us     rwlock:W   do_exit+0x36d
           5     32.34 us     10.87 us      6.47 us     rwlock:R   do_wait+0x8b
           4     15.41 us      4.73 us      3.85 us     rwlock:W   release_task+0x6e

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/bpf_lock_contention.c         | 42 ++++++++++++++++++-
 .../perf/util/bpf_skel/lock_contention.bpf.c  | 17 ++++++++
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index b8590b82ad3d..4a95c0ebcb3c 100644
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -20,7 +20,7 @@ static struct lock_contention_bpf *skel;
 int lock_contention_prepare(struct lock_contention *con)
 {
 	int i, fd;
-	int ncpus = 1, ntasks = 1, ntypes = 1;
+	int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1;
 	struct evlist *evlist = con->evlist;
 	struct target *target = con->target;
 
@@ -49,9 +49,39 @@ int lock_contention_prepare(struct lock_contention *con)
 	if (con->filters->nr_types)
 		ntypes = con->filters->nr_types;
 
+	/* resolve lock name filters to addr */
+	if (con->filters->nr_syms) {
+		struct symbol *sym;
+		struct map *kmap;
+		unsigned long *addrs;
+
+		for (i = 0; i < con->filters->nr_syms; i++) {
+			sym = machine__find_kernel_symbol_by_name(con->machine,
+								  con->filters->syms[i],
+								  &kmap);
+			if (sym == NULL) {
+				pr_warning("ignore unknown symbol: %s\n",
+					   con->filters->syms[i]);
+				continue;
+			}
+
+			addrs = realloc(con->filters->addrs,
+					(con->filters->nr_addrs + 1) * sizeof(*addrs));
+			if (addrs == NULL) {
+				pr_warning("memory allocation failure\n");
+				continue;
+			}
+
+			addrs[con->filters->nr_addrs++] = kmap->unmap_ip(kmap, sym->start);
+			con->filters->addrs = addrs;
+		}
+		naddrs = con->filters->nr_addrs;
+	}
+
 	bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
 	bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
 	bpf_map__set_max_entries(skel->maps.type_filter, ntypes);
+	bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);
 
 	if (lock_contention_bpf__load(skel) < 0) {
 		pr_err("Failed to load lock-contention BPF skeleton\n");
@@ -103,6 +133,16 @@ int lock_contention_prepare(struct lock_contention *con)
 			bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);
 	}
 
+	if (con->filters->nr_addrs) {
+		u8 val = 1;
+
+		skel->bss->has_addr = 1;
+		fd = bpf_map__fd(skel->maps.addr_filter);
+
+		for (i = 0; i < con->filters->nr_addrs; i++)
+			bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);
+	}
+
 	/* these don't work well if in the rodata section */
 	skel->bss->stack_skip = con->stack_skip;
 	skel->bss->aggr_mode = con->aggr_mode;
diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index fb0128de7c00..ad0ca5d50557 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -69,11 +69,19 @@ struct {
 	__uint(max_entries, 1);
 } type_filter SEC(".maps");
 
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u64));
+	__uint(value_size, sizeof(__u8));
+	__uint(max_entries, 1);
+} addr_filter SEC(".maps");
+
 /* control flags */
 int enabled;
 int has_cpu;
 int has_task;
 int has_type;
+int has_addr;
 int stack_skip;
 
 /* determine the key of lock stat */
@@ -111,6 +119,15 @@ static inline int can_record(u64 *ctx)
 			return 0;
 	}
 
+	if (has_addr) {
+		__u8 *ok;
+		__u64 addr = ctx[0];
+
+		ok = bpf_map_lookup_elem(&addr_filter, &addr);
+		if (!ok)
+			return 0;
+	}
+
 	return 1;
 }
 
-- 
2.39.0.314.g84b9a713c41-goog