From: Athira Rajeev atrajeev@linux.vnet.ibm.com
[ Upstream commit 0198322379c25215b2778482bf1221743a76e2b5 ]
Trace IMC (In-Memory collection counters) in powerpc is useful for application level profiling.
For trace_imc, presently task context (task_ctx_nr) is set to perf_hw_context. But perf_hw_context should only be used for CPU PMU. See commit 26657848502b ("perf/core: Verify we have a single perf_hw_context PMU").
So for trace_imc, even though it is per thread PMU, it is preferred to use sw_context in order to be able to do application level monitoring. Hence change the task_ctx_nr to use perf_sw_context.
Fixes: 012ae244845f ("powerpc/perf: Trace imc PMU functions") Signed-off-by: Athira Rajeev atrajeev@linux.vnet.ibm.com Reviewed-by: Madhavan Srinivasan maddy@linux.vnet.ibm.com [mpe: Update subject & incorporate notes into change log, reflow comment] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220202041837.65968-1-atrajeev@linux.vnet.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/perf/imc-pmu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c index e106909ff9c3..e7583fbcc8fa 100644 --- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c @@ -1457,7 +1457,11 @@ static int trace_imc_event_init(struct perf_event *event)
event->hw.idx = -1;
- event->pmu->task_ctx_nr = perf_hw_context; + /* + * There can only be a single PMU for perf_hw_context events which is assigned to + * core PMU. Hence use "perf_sw_context" for trace_imc. + */ + event->pmu->task_ctx_nr = perf_sw_context; event->destroy = reset_global_refc; return 0; }