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Subject[PATCH V2 18/23] perf/x86/intel: Disable sampling read slots and topdown
Date
From: Kan Liang <kan.liang@linux.intel.com>

To get correct PERF_METRICS value, the fixed counter 3 must start from
0. It would bring problems when sampling read slots and topdown events.
For example,
perf record -e '{slots, topdown-retiring}:S'
The slots would not overflow if it starts from 0.

Add specific validate_group() support to reject the case and error out
for Icelake.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---

No changes since V1.

arch/x86/events/core.c | 2 ++
arch/x86/events/intel/core.c | 20 ++++++++++++++++++++
arch/x86/events/perf_event.h | 2 ++
3 files changed, 24 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 7d4d56f76436..b9bee53e53d8 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2122,6 +2122,8 @@ static int validate_group(struct perf_event *event)

ret = x86_pmu.schedule_events(fake_cpuc, n, NULL);

+ if (x86_pmu.validate_group)
+ ret = x86_pmu.validate_group(fake_cpuc, n);
out:
free_fake_cpuc(fake_cpuc);
return ret;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index b08e361fc718..ef6045544628 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4331,6 +4331,25 @@ static int icl_set_period(struct perf_event *event)
return 1;
}

+static int icl_validate_group(struct cpu_hw_events *cpuc, int n)
+{
+ bool has_sampling_slots = false, has_metrics = false;
+ struct perf_event *e;
+ int i;
+
+ for (i = 0; i < n; i++) {
+ e = cpuc->event_list[i];
+ if (is_slots_event(e) && is_sampling_event(e))
+ has_sampling_slots = true;
+
+ if (is_perf_metrics_event(e))
+ has_metrics = true;
+ }
+ if (unlikely(has_sampling_slots && has_metrics))
+ return -EINVAL;
+ return 0;
+}
+
EVENT_ATTR_STR(mem-loads, mem_ld_hsw, "event=0xcd,umask=0x1,ldlat=3");
EVENT_ATTR_STR(mem-stores, mem_st_hsw, "event=0xd0,umask=0x82")

@@ -5037,6 +5056,7 @@ __init int intel_pmu_init(void)
x86_pmu.has_metric = x86_pmu.intel_cap.perf_metrics;
x86_pmu.metric_update_event = icl_metric_update_event;
x86_pmu.set_period = icl_set_period;
+ x86_pmu.validate_group = icl_validate_group;
pr_cont("Icelake events, ");
name = "icelake";
break;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index 06f1fe553ac1..bd0dbbc2adeb 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -627,6 +627,8 @@ struct x86_pmu {
u64 (*limit_period)(struct perf_event *event, u64 l);
int (*set_period)(struct perf_event *event);

+ int (*validate_group)(struct cpu_hw_events *cpuc, int n);
+
/* PMI handler bits */
unsigned int late_ack :1,
counter_freezing :1;
--
2.17.1
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