perf lock: Add bpf maps for owner stack tracing

Add a struct and few bpf maps in order to tracing owner stack.
`struct owner_tracing_data`: Contains owner's pid, stack id, timestamp for
  when the owner acquires lock, and the count of lock waiters.
`stack_buf`: Percpu buffer for retrieving owner stacktrace.
`owner_stacks`: For tracing owner stacktrace to customized owner stack id.
`owner_data`: For tracing lock_address to `struct owner_tracing_data` in
  bpf program.
`owner_stat`: For reporting owner stacktrace in usermode.

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Tested-by: Athira Rajeev <atrajeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20250227003359.732948-2-ctshao@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c
index fc8666222399c995da414498ab042250537bc9df..76542b86e83ffd72cf9167bc8ffbd235c5787cbd 100644 (file)
--- a/tools/perf/util/bpf_lock_contention.c
+++ b/tools/perf/util/bpf_lock_contention.c
@@ -131,10 +131,20 @@ int lock_contention_prepare(struct lock_contention *con)
        else
                bpf_map__set_max_entries(skel->maps.task_data, 1);
 
-       if (con->save_callstack)
+       if (con->save_callstack) {
                bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);
-       else
+               if (con->owner) {
+                       bpf_map__set_value_size(skel->maps.stack_buf, con->max_stack * sizeof(u64));
+                       bpf_map__set_key_size(skel->maps.owner_stacks,
+                                               con->max_stack * sizeof(u64));
+                       bpf_map__set_max_entries(skel->maps.owner_stacks, con->map_nr_entries);
+                       bpf_map__set_max_entries(skel->maps.owner_data, con->map_nr_entries);
+                       bpf_map__set_max_entries(skel->maps.owner_stat, con->map_nr_entries);
+                       skel->rodata->max_stack = con->max_stack;
+               }
+       } else {
                bpf_map__set_max_entries(skel->maps.stacks, 1);
+       }
 
        if (target__has_cpu(target)) {
                skel->rodata->has_cpu = 1;

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 6533ea9b044c71d14353081768ea2216edbab5ef..23fe9cc980aec3f82d9dc56ce2b750d733bf89bf 100644 (file)
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -27,6 +27,38 @@ struct {
        __uint(max_entries, MAX_ENTRIES);
 } stacks SEC(".maps");
 
+/* buffer for owner stacktrace */
+struct {
+       __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+       __uint(key_size, sizeof(__u32));
+       __uint(value_size, sizeof(__u64));
+       __uint(max_entries, 1);
+} stack_buf SEC(".maps");
+
+/* a map for tracing owner stacktrace to owner stack id */
+struct {
+       __uint(type, BPF_MAP_TYPE_HASH);
+       __uint(key_size, sizeof(__u64)); // owner stacktrace
+       __uint(value_size, sizeof(__s32)); // owner stack id
+       __uint(max_entries, 1);
+} owner_stacks SEC(".maps");
+
+/* a map for tracing lock address to owner data */
+struct {
+       __uint(type, BPF_MAP_TYPE_HASH);
+       __uint(key_size, sizeof(__u64)); // lock address
+       __uint(value_size, sizeof(struct owner_tracing_data));
+       __uint(max_entries, 1);
+} owner_data SEC(".maps");
+
+/* a map for contention_key (stores owner stack id) to contention data */
+struct {
+       __uint(type, BPF_MAP_TYPE_HASH);
+       __uint(key_size, sizeof(struct contention_key));
+       __uint(value_size, sizeof(struct contention_data));
+       __uint(max_entries, 1);
+} owner_stat SEC(".maps");
+
 /* maintain timestamp at the beginning of contention */
 struct {
        __uint(type, BPF_MAP_TYPE_HASH);
@@ -143,6 +175,7 @@ const volatile int needs_callstack;
 const volatile int stack_skip;
 const volatile int lock_owner;
 const volatile int use_cgroup_v2;
+const volatile int max_stack;
 
 /* determine the key of lock stat */
 const volatile int aggr_mode;

diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index c15f734d7fc4aecb518eada554ef2330f5bf2abe..15f5743bd409f2f93e3c9137d6efeea8811b0dd0 100644 (file)
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -3,6 +3,13 @@
 #ifndef UTIL_BPF_SKEL_LOCK_DATA_H
 #define UTIL_BPF_SKEL_LOCK_DATA_H
 
+struct owner_tracing_data {
+       u32 pid; // Who has the lock.
+       u32 count; // How many waiters for this lock.
+       u64 timestamp; // The time while the owner acquires lock and contention is going on.
+       s32 stack_id; // Identifier for `owner_stat`, which stores as value in `owner_stacks`
+};
+
 struct tstamp_data {
        u64 timestamp;
        u64 lock;