perf lock contention: Show per-cpu rq_lock with address

Using the BPF_PROG_RUN mechanism, we can run a raw_tp BPF program to
collect some semi-global locks like per-cpu locks.  Let's add runqueue
locks using bpf_per_cpu_ptr() helper.

  $ sudo ./perf lock con -abl -- sleep 1
   contended   total wait     max wait     avg wait            address   symbol

         248      3.25 ms     32.23 us     13.10 us   ffff8cc75cfd2940   siglock
          60    217.91 us      9.69 us      3.63 us   ffff8cc700061c00
           8     70.23 us     13.86 us      8.78 us   ffff8cc703629484
           4     56.32 us     35.81 us     14.08 us   ffff8cc78b66f778   mmap_lock
           4     16.70 us      5.18 us      4.18 us   ffff8cc7036a0684
           3      4.99 us      2.65 us      1.66 us   ffff8d053da30c80   rq_lock
           2      3.44 us      2.28 us      1.72 us   ffff8d053dcf0c80   rq_lock
           9      2.51 us       371 ns       278 ns   ffff8ccb92479440
           2      2.11 us      1.24 us      1.06 us   ffff8d053db30c80   rq_lock
           2      2.06 us      1.69 us      1.03 us   ffff8d053d970c80   rq_lock

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230313204825.2665483-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index f76cde065c5d..ed9160999c32 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -10,6 +10,9 @@
 /* default buffer size */
 #define MAX_ENTRIES  10240
 
+/* for collect_lock_syms().  4096 was rejected by the verifier */
+#define MAX_CPUS  1024
+
 /* lock contention flags from include/trace/events/lock.h */
 #define LCB_F_SPIN	(1U << 0)
 #define LCB_F_READ	(1U << 1)
@@ -58,6 +61,13 @@ struct {
 
 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(__u64));
+	__uint(value_size, sizeof(__u32));
+	__uint(max_entries, 16384);
+} lock_syms SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
 	__uint(key_size, sizeof(__u32));
 	__uint(value_size, sizeof(__u8));
 	__uint(max_entries, 1);
@@ -384,4 +394,25 @@ int contention_end(u64 *ctx)
 	return 0;
 }
 
+extern struct rq runqueues __ksym;
+
+SEC("raw_tp/bpf_test_finish")
+int BPF_PROG(collect_lock_syms)
+{
+	__u64 lock_addr;
+	__u32 lock_flag;
+
+	for (int i = 0; i < MAX_CPUS; i++) {
+		struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
+
+		if (rq == NULL)
+			break;
+
+		lock_addr = (__u64)&rq->__lock;
+		lock_flag = LOCK_CLASS_RQLOCK;
+		bpf_map_update_elem(&lock_syms, &lock_addr, &lock_flag, BPF_ANY);
+	}
+	return 0;
+}
+
 char LICENSE[] SEC("license") = "Dual BSD/GPL";