Commit b9f82b5c authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf lock contention: Rework offset calculation with BPF CO-RE 



It seems BPF CO-RE reloc doesn't work well with the pattern that gets
the field-offset only.  Use offsetof() to make it explicit so that
the compiler would generate the correct code.

Fixes: 0c122848 ("perf lock contention: Support pre-5.14 kernels")
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Acked-by: default avatarIan Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Co-developed-by: default avatarAndrii Nakryiko <andrii.nakryiko@gmail.com>
Link: https://lore.kernel.org/r/20230427234833.1576130-2-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent e53de7b6

tools/perf/util/bpf_skel/lock_contention.bpf.c

+7 −7
Original line number Diff line number Diff line
@@ -429,21 +429,21 @@ struct rq___new { 
SEC("raw_tp/bpf_test_finish")

int BPF_PROG(collect_lock_syms)

{

	__u64 lock_addr;

	__u64 lock_addr, lock_off;

	__u32 lock_flag;



	if (bpf_core_field_exists(struct rq___new, __lock))

		lock_off = offsetof(struct rq___new, __lock);

	else

		lock_off = offsetof(struct rq___old, lock);



	for (int i = 0; i < MAX_CPUS; i++) {

		struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);

		struct rq___new *rq_new = (void *)rq;

		struct rq___old *rq_old = (void *)rq;



		if (rq == NULL)

			break;



		if (bpf_core_field_exists(rq_new->__lock))

			lock_addr = (__u64)&rq_new->__lock;

		else

			lock_addr = (__u64)&rq_old->lock;

		lock_addr = (__u64)(void *)rq + lock_off;

		lock_flag = LOCK_CLASS_RQLOCK;

		bpf_map_update_elem(&lock_syms, &lock_addr, &lock_flag, BPF_ANY);

	}