perf/x86: Add structures for the attributes of Hybrid PMUs

Hybrid PMUs have different events and formats. In theory, Hybrid PMU
specific attributes should be maintained in the dedicated struct
x86_hybrid_pmu, but it wastes space because the events and formats are
similar among Hybrid PMUs.

To reduce duplication, all hybrid PMUs will share a group of attributes
in the following patch. To distinguish an attribute from different
Hybrid PMUs, a PMU aware attribute structure is introduced. A PMU type
is required for the attribute structure. The type is internal usage. It
is not visible in the sysfs API.

Hybrid PMUs may support the same event name, but with different event
encoding, e.g., the mem-loads event on an Atom PMU has different event
encoding from a Core PMU. It brings issue if two attributes are
created for them. Current sysfs_update_group finds an attribute by
searching the attr name (aka event name). If two attributes have the
same event name, the first attribute will be replaced.
To address the issue, only one attribute is created for the event. The
event_str is extended and stores event encodings from all Hybrid PMUs.
Each event encoding is divided by ";". The order of the event encodings
must follow the order of the hybrid PMU index. The event_str is internal
usage as well. When a user wants to show the attribute of a Hybrid PMU,
only the corresponding part of the string is displayed.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Link: https://lkml.kernel.org/r/1618237865-33448-18-git-send-email-kan.liang@linux.intel.com

Author: Kan Liang

arch/x86/events/core.c

@@ -1860,6 +1860,49 @@ ssize_t events_ht_sysfs_show(struct device *dev, struct device_attribute *attr,
 			pmu_attr->event_str_noht);
 }
 
+ssize_t events_hybrid_sysfs_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *page)
+{
+	struct perf_pmu_events_hybrid_attr *pmu_attr =
+		container_of(attr, struct perf_pmu_events_hybrid_attr, attr);
+	struct x86_hybrid_pmu *pmu;
+	const char *str, *next_str;
+	int i;
+
+	if (hweight64(pmu_attr->pmu_type) == 1)
+		return sprintf(page, "%s", pmu_attr->event_str);
+
+	/*
+	 * Hybrid PMUs may support the same event name, but with different
+	 * event encoding, e.g., the mem-loads event on an Atom PMU has
+	 * different event encoding from a Core PMU.
+	 *
+	 * The event_str includes all event encodings. Each event encoding
+	 * is divided by ";". The order of the event encodings must follow
+	 * the order of the hybrid PMU index.
+	 */
+	pmu = container_of(dev_get_drvdata(dev), struct x86_hybrid_pmu, pmu);
+
+	str = pmu_attr->event_str;
+	for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) {
+		if (!(x86_pmu.hybrid_pmu[i].cpu_type & pmu_attr->pmu_type))
+			continue;
+		if (x86_pmu.hybrid_pmu[i].cpu_type & pmu->cpu_type) {
+			next_str = strchr(str, ';');
+			if (next_str)
+				return snprintf(page, next_str - str + 1, "%s", str);
+			else
+				return sprintf(page, "%s", str);
+		}
+		str = strchr(str, ';');
+		str++;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(events_hybrid_sysfs_show);
+
 EVENT_ATTR(cpu-cycles,			CPU_CYCLES		);
 EVENT_ATTR(instructions,		INSTRUCTIONS		);
 EVENT_ATTR(cache-references,		CACHE_REFERENCES	);

arch/x86/events/perf_event.h

@@ -979,6 +979,22 @@ static struct perf_pmu_events_ht_attr event_attr_##v = {		\
 	.event_str_ht	= ht,						\
 }
 
+#define EVENT_ATTR_STR_HYBRID(_name, v, str, _pmu)			\
+static struct perf_pmu_events_hybrid_attr event_attr_##v = {		\
+	.attr		= __ATTR(_name, 0444, events_hybrid_sysfs_show, NULL),\
+	.id		= 0,						\
+	.event_str	= str,						\
+	.pmu_type	= _pmu,						\
+}
+
+#define FORMAT_HYBRID_PTR(_id) (&format_attr_hybrid_##_id.attr.attr)
+
+#define FORMAT_ATTR_HYBRID(_name, _pmu)					\
+static struct perf_pmu_format_hybrid_attr format_attr_hybrid_##_name = {\
+	.attr		= __ATTR_RO(_name),				\
+	.pmu_type	= _pmu,						\
+}
+
 struct pmu *x86_get_pmu(unsigned int cpu);
 extern struct x86_pmu x86_pmu __read_mostly;
 
@@ -1149,6 +1165,9 @@ ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr,
 			  char *page);
 ssize_t events_ht_sysfs_show(struct device *dev, struct device_attribute *attr,
 			  char *page);
+ssize_t events_hybrid_sysfs_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *page);
 
 static inline bool fixed_counter_disabled(int i, struct pmu *pmu)
 {

include/linux/perf_event.h

@@ -1549,6 +1549,18 @@ struct perf_pmu_events_ht_attr {
 	const char				*event_str_noht;
 };
 
+struct perf_pmu_events_hybrid_attr {
+	struct device_attribute			attr;
+	u64					id;
+	const char				*event_str;
+	u64					pmu_type;
+};
+
+struct perf_pmu_format_hybrid_attr {
+	struct device_attribute			attr;
+	u64					pmu_type;
+};
+
 ssize_t perf_event_sysfs_show(struct device *dev, struct device_attribute *attr,
 			      char *page);