From: Kan Liang kan.liang@linux.intel.com
A non-0 retire latency can be observed on a Raptorlake which doesn't support the retire latency feature. By design, the retire latency shares the PERF_SAMPLE_WEIGHT_STRUCT sample type with other types of latency. That could avoid adding too many different sample types to support all kinds of latency. For the machine which doesn't support some kind of latency, 0 should be returned.
Perf doesn’t clear/init all the fields of a sample data for the sake of performance. It expects the later perf_{prepare,output}_sample() to update the uninitialized field. However, the current implementation doesn't touch the field of the retire latency if the feature is not supported. The memory garbage is dumped into the perf data.
Clear the retire latency if the feature is not supported.
Fixes: c87a31093c70 ("perf/x86: Support Retire Latency") Reported-by: "Bayduraev, Alexey V" alexey.v.bayduraev@intel.com Tested-by: "Bayduraev, Alexey V" alexey.v.bayduraev@intel.com Signed-off-by: Kan Liang kan.liang@linux.intel.com Cc: stable@vger.kernel.org --- arch/x86/events/intel/ds.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index f95cca6b632a..838f3e23bce9 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1989,8 +1989,12 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event, set_linear_ip(regs, basic->ip); regs->flags = PERF_EFLAGS_EXACT;
- if ((sample_type & PERF_SAMPLE_WEIGHT_STRUCT) && (x86_pmu.flags & PMU_FL_RETIRE_LATENCY)) - data->weight.var3_w = format_size >> PEBS_RETIRE_LATENCY_OFFSET & PEBS_LATENCY_MASK; + if (sample_type & PERF_SAMPLE_WEIGHT_STRUCT) { + if (x86_pmu.flags & PMU_FL_RETIRE_LATENCY) + data->weight.var3_w = format_size >> PEBS_RETIRE_LATENCY_OFFSET & PEBS_LATENCY_MASK; + else + data->weight.var3_w = 0; + }
/* * The record for MEMINFO is in front of GP