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perf/x86/intel/ds: Fix non 0 retire latency on Raptorlake

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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: c87a31093c ("perf/x86: Support Retire Latency")
Reported-by: "Bayduraev, Alexey V" <alexey.v.bayduraev@intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: "Bayduraev, Alexey V" <alexey.v.bayduraev@intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20240708193336.1192217-4-kan.liang@linux.intel.com
This commit is contained in:
Kan Liang 2024-07-08 12:33:36 -07:00 committed by Peter Zijlstra
parent 556a7c039a
commit e5f32ad56b
1 changed files with 6 additions and 2 deletions
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8
arch/x86/events/intel/ds.c
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@ -1944,8 +1944,12 @@ 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