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perf/bpf: Always use perf callchains if exist

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If the perf_event has PERF_SAMPLE_CALLCHAIN, BPF can use it for stack trace.
The problematic cases like PEBS and IBS already handled in the PMU driver and
they filled the callchain info in the sample data.  For others, we can call
perf_callchain() before the BPF handler.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220908214104.3851807-2-namhyung@kernel.org
This commit is contained in:
Namhyung Kim
2022-09-08 14:41:03 -07:00
committed by Peter Zijlstra
parent 3749d33e51
commit 16817ad7e8
2 changed files with 12 additions and 4 deletions
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12
kernel/events/core.c
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@@ -10000,8 +10000,16 @@ static void bpf_overflow_handler(struct perf_event *event,
goto out;
rcu_read_lock();
prog = READ_ONCE(event->prog);
if (prog)
if (prog) {
if (prog->call_get_stack &&
(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) &&
!(data->sample_flags & PERF_SAMPLE_CALLCHAIN)) {
data->callchain = perf_callchain(event, regs);
data->sample_flags |= PERF_SAMPLE_CALLCHAIN;
}
ret = bpf_prog_run(prog, &ctx);
}
rcu_read_unlock();
out:
__this_cpu_dec(bpf_prog_active);
@@ -10027,7 +10035,7 @@ static int perf_event_set_bpf_handler(struct perf_event *event,
if (event->attr.precise_ip &&
prog->call_get_stack &&
(!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY) ||
(!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
event->attr.exclude_callchain_kernel ||
event->attr.exclude_callchain_user)) {
/*