Re: [PATCH V5 08/12] perf/x86/intel: Add Icelake support

[Liang, Kan]

On 4/8/2019 11:45 AM, Liang, Kan wrote:
> On 4/8/2019 11:06 AM, Peter Zijlstra wrote:
> > On Tue, Apr 02, 2019 at 12:45:05PM -0700, kan.liang@xxxxxxxxxxxxxxx 
> > wrote:
> > > +static struct event_constraint *
> > > +icl_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
> > > +ÂÂÂÂÂÂÂÂÂÂÂÂÂ struct perf_event *event)
> > > +{
> > > +ÂÂÂ /*
> > > +ÂÂÂÂ * Fixed counter 0 has less skid.
> > > +ÂÂÂÂ * Force instruction:ppp in Fixed counter 0
> > > +ÂÂÂÂ */
> > > +ÂÂÂ if ((event->attr.precise_ip == 3) &&
> > > +ÂÂÂÂÂÂÂ ((event->hw.config & X86_RAW_EVENT_MASK) == 0x00c0))
> > > +ÂÂÂÂÂÂÂ return &fixed_counter0_constraint;
> >
> > Does that want to be:
> >
> > ÂÂÂÂÂÂÂ event->hw.config == X86_CONFIG(.event=0xc0)
> >
> > ?
> >
> > That is, are there really bits we want to mask in there?
>
> For instruction event, right, we don't need mask it.
> I will change it.

Actually, we have to mask some bits here, e.g. 
ARCH_PERFMON_EVENTSEL_INT, ARCH_PERFMON_EVENTSEL_USR and 
ARCH_PERFMON_EVENTSEL_OS. Those bits will be set in hw_config().

Also, other filds, e.g the INV, ANY, E, or CMASK fields are not allowed 
for reduced Skid PEBS.


diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index dae3d84..3fa36c9 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3463,6 +3463,9 @@ hsw_get_event_constraints(struct cpu_hw_events 
*cpuc, int idx,
 	return c;
 }

+#define EVENT_CONFIG(config)		\
+	(config & (X86_ALL_EVENT_FLAGS | INTEL_ARCH_EVENT_MASK))
+
 static struct event_constraint *
 icl_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 			  struct perf_event *event)
@@ -3472,7 +3475,7 @@ icl_get_event_constraints(struct cpu_hw_events 
*cpuc, int idx,
 	 * Force instruction:ppp in Fixed counter 0
 	 */
 	if ((event->attr.precise_ip == 3) &&
-	    (event->hw.config == X86_CONFIG(.event=0xc0)))
+	    (EVENT_CONFIG(event->hw.config) == X86_CONFIG(.event=0xc0)))
 		return &fixed_counter0_constraint;

 	return hsw_get_event_constraints(cpuc, idx, event);

Thanks,
Kan