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

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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: 0c1228486b ("perf lock contention: Support pre-5.14 kernels")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian 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: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Link: https://lore.kernel.org/r/20230427234833.1576130-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Namhyung Kim 2023-04-27 16:48:33 -07:00 committed by Arnaldo Carvalho de Melo
parent e53de7b65a
commit b9f82b5c63
1 changed files with 7 additions and 7 deletions
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14
tools/perf/util/bpf_skel/lock_contention.bpf.c
View file

@ -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);
}