[PATCH v4 0/2] perf tools: Add PMU alias support

A perf uncore PMU may have two PMU names, a real name and an alias name.
With this patch set, the perf tool can monitor the PMU with either the
real name or the alias.

Use the real name,
 $ perf stat -e uncore_cha_2/event=1/ -x,
   4044879584,,uncore_cha_2/event=1/,2528059205,100.00,,

Use the alias,
 $ perf stat -e uncore_type_0_2/event=1/ -x,
   3659675336,,uncore_type_0_2/event=1/,2287306455,100.00,,

v4:
---
1. Fix memory leaks in pmu_lookup.
2. Rebase to perf/core.

v3:
---
1. Use fgets() to replace fscanf().
2. Resource cleanup.

v2:
---
Add test case to verify the real name and alias name having same effect.

Jin Yao (1):
  perf tests: Test for PMU alias

Kan Liang (1):
  perf pmu: Add PMU alias support

 tools/perf/arch/x86/util/pmu.c  | 129 +++++++++++++++++++++++++++++++-
 tools/perf/tests/parse-events.c |  92 +++++++++++++++++++++++
 tools/perf/util/parse-events.y  |   3 +-
 tools/perf/util/pmu.c           |  47 +++++++++---
 tools/perf/util/pmu.h           |   5 ++
 5 files changed, 264 insertions(+), 12 deletions(-)

-- 
2.17.1

From: Kan Liang <redacted>

A perf uncore PMU may have two PMU names, a real name and an alias. The
alias is exported at /sys/bus/event_source/devices/uncore_*/alias.
The perf tool should support the alias as well.

Add alias_name in the struct perf_pmu to store the alias. For the PMU
which doesn't have an alias. It's NULL.

Introduce two X86 specific functions to retrieve the real name and the
alias separately.

Only go through the sysfs to retrieve the mapping between the real name
and the alias once. The result is cached in a list, uncore_pmu_list.

Nothing changed for the other ARCHs.

With the patch, the perf tool can monitor the PMU with either the real
name or the alias.

Use the real name,
 $ perf stat -e uncore_cha_2/event=1/ -x,
   4044879584,,uncore_cha_2/event=1/,2528059205,100.00,,

Use the alias,
 $ perf stat -e uncore_type_0_2/event=1/ -x,
   3659675336,,uncore_type_0_2/event=1/,2287306455,100.00,,

Co-developed-by: Jin Yao <redacted>
Signed-off-by: Jin Yao <redacted>
Signed-off-by: Kan Liang <redacted>
---
v4:
 - Fix memory leaks in pmu_lookup.
 - Rebase to perf/core.

v3:
 - Use fgets to read alias string from sysfs.
 - Resource cleanup.

v2:
 - No change.

 tools/perf/arch/x86/util/pmu.c | 129 ++++++++++++++++++++++++++++++++-
 tools/perf/util/parse-events.y |   3 +-
 tools/perf/util/pmu.c          |  47 +++++++++---
 tools/perf/util/pmu.h          |   5 ++
 4 files changed, 172 insertions(+), 12 deletions(-)

diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index d48d608517fd..9abba67cc62e 100644
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c

@@ -1,12 +1,29 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <string.h>
-
+#include <stdio.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <fcntl.h>
 #include <linux/stddef.h>
 #include <linux/perf_event.h>
+#include <linux/zalloc.h>
+#include <api/fs/fs.h>
+#include <errno.h>
 
 #include "../../../util/intel-pt.h"
 #include "../../../util/intel-bts.h"
 #include "../../../util/pmu.h"
+#include "../../../util/fncache.h"
+
+#define TEMPLATE_ALIAS	"%s/bus/event_source/devices/%s/alias"
+
+struct perf_pmu_alias_name {
+	char *name;
+	char *alias;
+	struct list_head list;
+};
+
+static LIST_HEAD(pmu_alias_name_list);
 
 struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
 {

@@ -18,3 +35,113 @@ struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu __mayb
 #endif
 	return NULL;
 }
+
+static int setup_pmu_alias_list(void)
+{
+	char path[PATH_MAX];
+	DIR *dir;
+	struct dirent *dent;
+	const char *sysfs = sysfs__mountpoint();
+	struct perf_pmu_alias_name *pmu;
+	char buf[MAX_PMU_NAME_LEN];
+	FILE *file;
+	int ret = 0;
+
+	if (!sysfs)
+		return -1;
+
+	snprintf(path, PATH_MAX,
+		 "%s" EVENT_SOURCE_DEVICE_PATH, sysfs);
+
+	dir = opendir(path);
+	if (!dir)
+		return -1;
+
+	while ((dent = readdir(dir))) {
+		if (!strcmp(dent->d_name, ".") ||
+		    !strcmp(dent->d_name, ".."))
+			continue;
+
+		snprintf(path, PATH_MAX,
+			 TEMPLATE_ALIAS, sysfs, dent->d_name);
+
+		if (!file_available(path))
+			continue;
+
+		file = fopen(path, "r");
+		if (!file)
+			continue;
+
+		if (!fgets(buf, sizeof(buf), file)) {
+			fclose(file);
+			continue;
+		}
+
+		fclose(file);
+
+		pmu = zalloc(sizeof(*pmu));
+		if (!pmu) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		/* Remove the last '\n' */
+		buf[strlen(buf) - 1] = 0;
+
+		pmu->alias = strdup(buf);
+		if (!pmu->alias)
+			goto mem_err;
+
+		pmu->name = strdup(dent->d_name);
+		if (!pmu->name)
+			goto mem_err;
+
+		list_add_tail(&pmu->list, &pmu_alias_name_list);
+		continue;
+mem_err:
+		ret = -ENOMEM;
+		free(pmu->alias);
+		free(pmu->name);
+		free(pmu);
+		break;
+	}
+
+	closedir(dir);
+	return ret;
+}
+
+static char *__pmu_find_real_name(const char *name)
+{
+	struct perf_pmu_alias_name *pmu;
+
+	list_for_each_entry(pmu, &pmu_alias_name_list, list) {
+		if (!strcmp(name, pmu->alias))
+			return strdup(pmu->name);
+	}
+
+	return strdup(name);
+}
+
+char *pmu_find_real_name(const char *name)
+{
+	static bool cached_list;
+
+	if (cached_list)
+		return __pmu_find_real_name(name);
+
+	setup_pmu_alias_list();
+	cached_list = true;
+
+	return __pmu_find_real_name(name);
+}
+
+char *pmu_find_alias_name(const char *name)
+{
+	struct perf_pmu_alias_name *pmu;
+
+	list_for_each_entry(pmu, &pmu_alias_name_list, list) {
+		if (!strcmp(name, pmu->name))
+			return strdup(pmu->alias);
+	}
+	return NULL;
+}

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 9321bd0e2f76..d94e48e1ff9b 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y

@@ -316,7 +316,8 @@ event_pmu_name opt_pmu_config
 			if (!strncmp(name, "uncore_", 7) &&
 			    strncmp($1, "uncore_", 7))
 				name += 7;
-			if (!perf_pmu__match(pattern, name, $1)) {
+			if (!perf_pmu__match(pattern, name, $1) ||
+			    !perf_pmu__match(pattern, pmu->alias_name, $1)) {
 				if (parse_events_copy_term_list(orig_terms, &terms))
 					CLEANUP_YYABORT;
 				if (!parse_events_add_pmu(_parse_state, list, pmu->name, terms, true, false))

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index fc683bc41715..796a4be752f4 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c

@@ -946,6 +946,18 @@ perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
 	return NULL;
 }
 
+char * __weak
+pmu_find_real_name(const char *name)
+{
+	return strdup(name);
+}
+
+char * __weak
+pmu_find_alias_name(const char *name __maybe_unused)
+{
+	return NULL;
+}
+
 static int pmu_max_precise(const char *name)
 {
 	char path[PATH_MAX];

@@ -959,19 +971,25 @@ static int pmu_max_precise(const char *name)
 	return max_precise;
 }
 
-static struct perf_pmu *pmu_lookup(const char *name)
+static struct perf_pmu *pmu_lookup(const char *lookup_name)
 {
-	struct perf_pmu *pmu;
+	struct perf_pmu *pmu = NULL;
 	LIST_HEAD(format);
 	LIST_HEAD(aliases);
 	__u32 type;
-	bool is_hybrid = perf_pmu__hybrid_mounted(name);
+	bool is_hybrid;
+	char *name = pmu_find_real_name(lookup_name);
+
+	if (!name)
+		return NULL;
+
+	is_hybrid = perf_pmu__hybrid_mounted(name);
 
 	/*
 	 * Check pmu name for hybrid and the pmu may be invalid in sysfs
 	 */
 	if (!strncmp(name, "cpu_", 4) && !is_hybrid)
-		return NULL;
+		goto out;
 
 	/*
 	 * The pmu data we store & need consists of the pmu

@@ -979,23 +997,24 @@ static struct perf_pmu *pmu_lookup(const char *name)
 	 * now.
 	 */
 	if (pmu_format(name, &format))
-		return NULL;
+		goto out;
 
 	/*
 	 * Check the type first to avoid unnecessary work.
 	 */
 	if (pmu_type(name, &type))
-		return NULL;
+		goto out;
 
 	if (pmu_aliases(name, &aliases))
-		return NULL;
+		goto out;
 
 	pmu = zalloc(sizeof(*pmu));
 	if (!pmu)
-		return NULL;
+		goto out;
 
 	pmu->cpus = pmu_cpumask(name);
-	pmu->name = strdup(name);
+	pmu->name = name;
+	pmu->alias_name = pmu_find_alias_name(name);
 	pmu->type = type;
 	pmu->is_uncore = pmu_is_uncore(name);
 	if (pmu->is_uncore)

@@ -1017,6 +1036,10 @@ static struct perf_pmu *pmu_lookup(const char *name)
 
 	pmu->default_config = perf_pmu__get_default_config(pmu);
 
+out:
+	if (!pmu)
+		free(name);
+
 	return pmu;
 }
 

@@ -1025,7 +1048,8 @@ static struct perf_pmu *pmu_find(const char *name)
 	struct perf_pmu *pmu;
 
 	list_for_each_entry(pmu, &pmus, list)
-		if (!strcmp(pmu->name, name))
+		if (!strcmp(pmu->name, name) ||
+		    (pmu->alias_name && !strcmp(pmu->alias_name, name)))
 			return pmu;
 
 	return NULL;

@@ -1920,6 +1944,9 @@ bool perf_pmu__has_hybrid(void)
 
 int perf_pmu__match(char *pattern, char *name, char *tok)
 {
+	if (!name)
+		return -1;
+
 	if (fnmatch(pattern, name, 0))
 		return -1;
 

diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 926da483a141..f6ca9f6a06ef 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h

@@ -21,6 +21,7 @@ enum {
 #define PERF_PMU_FORMAT_BITS 64
 #define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/"
 #define CPUS_TEMPLATE_CPU	"%s/bus/event_source/devices/%s/cpus"
+#define MAX_PMU_NAME_LEN 128
 
 struct perf_event_attr;
 

@@ -32,6 +33,7 @@ struct perf_pmu_caps {
 
 struct perf_pmu {
 	char *name;
+	char *alias_name;	/* PMU alias name */
 	char *id;
 	__u32 type;
 	bool selectable;

@@ -135,4 +137,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
 bool perf_pmu__has_hybrid(void);
 int perf_pmu__match(char *pattern, char *name, char *tok);
 
+char *pmu_find_real_name(const char *name);
+char *pmu_find_alias_name(const char *name);
+
 #endif /* __PMU_H */

-- 
2.17.1

A perf uncore PMU may have two PMU names, a real name and an alias
name. Add one test case to verify the real name and alias name having
the same effect.

Iterate the sysfs to get one event which has an alias and create
evlist by adding two evsels. Evsel1 is created by event and evsel2
is created by alias.

Test asserts:
evsel1->core.attr.type == evsel2->core.attr.type
evsel1->core.attr.config == evsel2->core.attr.config

Signed-off-by: Jin Yao <redacted>
---
v4:
 - Rebase to perf/core.

v3:
 - Use fgets to read alias string from sysfs.
 - Resource cleanup.

v2:
 - New in v2.

 tools/perf/tests/parse-events.c | 92 +++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/tools/perf/tests/parse-events.c b/tools/perf/tests/parse-events.c
index 8d4866739255..fd3556cc9ad4 100644
--- a/tools/perf/tests/parse-events.c
+++ b/tools/perf/tests/parse-events.c

@@ -9,6 +9,7 @@
 #include "pmu-hybrid.h"
 #include <dirent.h>
 #include <errno.h>
+#include "fncache.h"
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>

@@ -2194,9 +2195,91 @@ static int test_pmu_events(void)
 	return ret;
 }
 
+static bool test_alias(char **event, char **alias)
+{
+	char path[PATH_MAX];
+	DIR *dir;
+	struct dirent *dent;
+	const char *sysfs = sysfs__mountpoint();
+	char buf[128];
+	FILE *file;
+
+	if (!sysfs)
+		return false;
+
+	snprintf(path, PATH_MAX, "%s/bus/event_source/devices/", sysfs);
+	dir = opendir(path);
+	if (!dir)
+		return false;
+
+	while ((dent = readdir(dir))) {
+		if (!strcmp(dent->d_name, ".") ||
+		    !strcmp(dent->d_name, ".."))
+			continue;
+
+		snprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s/alias",
+			 sysfs, dent->d_name);
+
+		if (!file_available(path))
+			continue;
+
+		file = fopen(path, "r");
+		if (!file)
+			continue;
+
+		if (!fgets(buf, sizeof(buf), file)) {
+			fclose(file);
+			continue;
+		}
+
+		/* Remove the last '\n' */
+		buf[strlen(buf) - 1] = 0;
+
+		fclose(file);
+		*event = strdup(dent->d_name);
+		*alias = strdup(buf);
+		closedir(dir);
+
+		if (*event == NULL || *alias == NULL) {
+			free(*event);
+			free(*alias);
+			return false;
+		}
+
+		return true;
+	}
+
+	closedir(dir);
+	return false;
+}
+
+static int test__checkevent_pmu_events_alias(struct evlist *evlist)
+{
+	struct evsel *evsel1 = evlist__first(evlist);
+	struct evsel *evsel2 = evlist__last(evlist);
+
+	TEST_ASSERT_VAL("wrong type", evsel1->core.attr.type == evsel2->core.attr.type);
+	TEST_ASSERT_VAL("wrong config", evsel1->core.attr.config == evsel2->core.attr.config);
+	return 0;
+}
+
+static int test_pmu_events_alias(char *event, char *alias)
+{
+	struct evlist_test e = { .id = 0, };
+	char name[2 * NAME_MAX + 20];
+
+	snprintf(name, sizeof(name), "%s/event=1/,%s/event=1/",
+		 event, alias);
+
+	e.name  = name;
+	e.check = test__checkevent_pmu_events_alias;
+	return test_event(&e);
+}
+
 int test__parse_events(struct test *test __maybe_unused, int subtest __maybe_unused)
 {
 	int ret1, ret2 = 0;
+	char *event, *alias;
 
 #define TEST_EVENTS(tests)				\
 do {							\

@@ -2221,6 +2304,15 @@ do {							\
 			return ret;
 	}
 
+	if (test_alias(&event, &alias)) {
+		int ret = test_pmu_events_alias(event, alias);
+
+		free(event);
+		free(alias);
+		if (ret)
+			return ret;
+	}
+
 	ret1 = test_terms(test__terms, ARRAY_SIZE(test__terms));
 	if (!ret2)
 		ret2 = ret1;

-- 
2.17.1

+
+	dir = opendir(path);
+	if (!dir)
+		return -1;

Could we cache/check the opendir result through file_available too?


The rest looks good


Reviewed-by: Andi Kleen <redacted>

-Andi

On Wed, Aug 11, 2021 at 10:48:26AM +0800, Jin Yao wrote:

SNIP

hm, why does this need to return already strdup? it forces you
to add all those goto below.. could just return name and keep
the 'pmu->name = strdup(name);' below?

that should make the change simpler

jirka

Hi Jiri,

On 8/12/2021 3:23 AM, Jiri Olsa wrote:

On Wed, Aug 11, 2021 at 10:48:26AM +0800, Jin Yao wrote:

SNIP

quoted

  				if (!parse_events_add_pmu(_parse_state, list, pmu->name, terms, true, false))

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index fc683bc41715..796a4be752f4 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c

@@ -946,6 +946,18 @@ perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
  	return NULL;
  }
  
+char * __weak
+pmu_find_real_name(const char *name)
+{
+	return strdup(name);
+}

hm, why does this need to return already strdup? it forces you
to add all those goto below.. could just return name and keep
the 'pmu->name = strdup(name);' below?

that should make the change simpler

jirka

In x86 specific __pmu_find_real_name,

static char *__pmu_find_real_name(const char *name)
{
	struct perf_pmu_alias_name *pmu;

	list_for_each_entry(pmu, &pmu_alias_name_list, list) {
		if (!strcmp(name, pmu->alias))
			return strdup(pmu->name);
	}

	return strdup(name);
}

We have returned with strdup(name).

OK, I will change the code to:

static char *__pmu_find_real_name(const char *name)
{
	struct perf_pmu_alias_name *pmu;

	list_for_each_entry(pmu, &pmu_alias_name_list, list) {
		if (!strcmp(name, pmu->alias))
			return pmu->name;
	}

	return name;
}

And keep 'pmu->name = strdup(name);' in pmu_lookup().

Thanks
Jin Yao

On 8/11/2021 9:27 PM, Andi Kleen wrote:

quoted

+
+    dir = opendir(path);
+    if (!dir)
+        return -1;

Could we cache/check the opendir result through file_available too?


The rest looks good


Reviewed-by: Andi Kleen <redacted>

-Andi

Thanks Andi! Let me check how to do it.

Thanks
Jin Yao

perf pmu: Add x86 PMU alias support

+char *pmu_find_real_name(const char *name)
+{
+	static bool cached_list;
+
+	if (cached_list)
+		return __pmu_find_real_name(name);
+
+	setup_pmu_alias_list();
+	cached_list = true;
+
+	return __pmu_find_real_name(name);
+}
+
+char *pmu_find_alias_name(const char *name)
+{
+	struct perf_pmu_alias_name *pmu;
+
+	list_for_each_entry(pmu, &pmu_alias_name_list, list) {
+		if (!strcmp(name, pmu->name))
+			return strdup(pmu->alias);

I would not expect a function which does a "find" to duplicate the name.

Same goes for all the other places which does similar.

That's not finding anything.

+
+char * __weak
+pmu_find_alias_name(const char *name __maybe_unused)
+{
+	return NULL;

 > +}

I don't understand this. There are lots of places this function can fail 
, but we don't free memories allocated previously - why just free this one?

I'd be inclined to use {} for the list_for_each_entry() call

useless comment

Hi John,

On 8/12/2021 8:14 PM, John Garry wrote:

perf pmu: Add x86 PMU alias support

quoted

+char *pmu_find_real_name(const char *name)
+{
+    static bool cached_list;
+
+    if (cached_list)
+        return __pmu_find_real_name(name);
+
+    setup_pmu_alias_list();
+    cached_list = true;
+
+    return __pmu_find_real_name(name);
+}
+
+char *pmu_find_alias_name(const char *name)
+{
+    struct perf_pmu_alias_name *pmu;
+
+    list_for_each_entry(pmu, &pmu_alias_name_list, list) {
+        if (!strcmp(name, pmu->name))
+            return strdup(pmu->alias);

I would not expect a function which does a "find" to duplicate the name.

Same goes for all the other places which does similar.

Yes, you are right. Jiri has the similar comment for the name duplicating here. We will still keep 
the 'pmu->name = strdup(name);' in pmu_lookup() in v5.

quoted

+    }
+    return NULL;
+}

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 9321bd0e2f76..d94e48e1ff9b 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y

@@ -316,7 +316,8 @@ event_pmu_name opt_pmu_config

              if (!strncmp(name, "uncore_", 7) &&
                  strncmp($1, "uncore_", 7))
                  name += 7;
-            if (!perf_pmu__match(pattern, name, $1)) {
+            if (!perf_pmu__match(pattern, name, $1) ||
+                !perf_pmu__match(pattern, pmu->alias_name, $1)) {
                  if (parse_events_copy_term_list(orig_terms, &terms))
                      CLEANUP_YYABORT;
                  if (!parse_events_add_pmu(_parse_state, list, pmu->name, terms, true, false))

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index fc683bc41715..796a4be752f4 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c

@@ -946,6 +946,18 @@ perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)

      return NULL;
  }
+char * __weak
+pmu_find_real_name(const char *name)
+{
+    return strdup(name);
+}

That's not finding anything.

Will just return name in non-x86 implementation.

pmu_find_real_name(const char *name)
{
	return name;
}

quoted

+
+char * __weak
+pmu_find_alias_name(const char *name __maybe_unused)
+{
+    return NULL;

 > +}

quoted

+
  static int pmu_max_precise(const char *name)
  {
      char path[PATH_MAX];

@@ -959,19 +971,25 @@ static int pmu_max_precise(const char *name)

      return max_precise;
  }
-static struct perf_pmu *pmu_lookup(const char *name)
+static struct perf_pmu *pmu_lookup(const char *lookup_name)
  {
-    struct perf_pmu *pmu;
+    struct perf_pmu *pmu = NULL;
      LIST_HEAD(format);
      LIST_HEAD(aliases);
      __u32 type;
-    bool is_hybrid = perf_pmu__hybrid_mounted(name);
+    bool is_hybrid;
+    char *name = pmu_find_real_name(lookup_name);
+
+    if (!name)
+        return NULL;
+
+    is_hybrid = perf_pmu__hybrid_mounted(name);
      /*
       * Check pmu name for hybrid and the pmu may be invalid in sysfs
       */
      if (!strncmp(name, "cpu_", 4) && !is_hybrid)
-        return NULL;
+        goto out;
      /*
       * The pmu data we store & need consists of the pmu

@@ -979,23 +997,24 @@ static struct perf_pmu *pmu_lookup(const char *name)

       * now.
       */
      if (pmu_format(name, &format))
-        return NULL;
+        goto out;
      /*
       * Check the type first to avoid unnecessary work.
       */
      if (pmu_type(name, &type))
-        return NULL;
+        goto out;
      if (pmu_aliases(name, &aliases))
-        return NULL;
+        goto out;
      pmu = zalloc(sizeof(*pmu));
      if (!pmu)
-        return NULL;
+        goto out;
      pmu->cpus = pmu_cpumask(name);
-    pmu->name = strdup(name);
+    pmu->name = name;
+    pmu->alias_name = pmu_find_alias_name(name);
      pmu->type = type;
      pmu->is_uncore = pmu_is_uncore(name);
      if (pmu->is_uncore)

@@ -1017,6 +1036,10 @@ static struct perf_pmu *pmu_lookup(const char *name)

      pmu->default_config = perf_pmu__get_default_config(pmu);
+out:
+    if (!pmu)
+        free(name);

I don't understand this. There are lots of places this function can fail , but we don't free 
memories allocated previously - why just free this one?

That's because it's only introduced by my patch (duplicating name). :)

But if we keep 'pmu->name = strdup(name)' in pmu_lookup(), I'm OK to keep original code/behavior.

quoted

+
      return pmu;
  }

@@ -1025,7 +1048,8 @@ static struct perf_pmu *pmu_find(const char *name)

      struct perf_pmu *pmu;
      list_for_each_entry(pmu, &pmus, list)
-        if (!strcmp(pmu->name, name))
+        if (!strcmp(pmu->name, name) ||
+            (pmu->alias_name && !strcmp(pmu->alias_name, name)))
              return pmu;

I'd be inclined to use {} for the list_for_each_entry() call

OK, I will add {}, thanks!

quoted

      return NULL;

@@ -1920,6 +1944,9 @@ bool perf_pmu__has_hybrid(void)

  int perf_pmu__match(char *pattern, char *name, char *tok)
  {
+    if (!name)
+        return -1;
+
      if (fnmatch(pattern, name, 0))
          return -1;

diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 926da483a141..f6ca9f6a06ef 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h

@@ -21,6 +21,7 @@ enum {

  #define PERF_PMU_FORMAT_BITS 64
  #define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/"
  #define CPUS_TEMPLATE_CPU    "%s/bus/event_source/devices/%s/cpus"
+#define MAX_PMU_NAME_LEN 128
  struct perf_event_attr;

@@ -32,6 +33,7 @@ struct perf_pmu_caps {

  struct perf_pmu {
      char *name;
+    char *alias_name;    /* PMU alias name */

useless comment

OK, remove it :)

Thanks
Jin Yao

quoted

      char *id;
      __u32 type;
      bool selectable;

@@ -135,4 +137,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,

  bool perf_pmu__has_hybrid(void);
  int perf_pmu__match(char *pattern, char *name, char *tok);
+char *pmu_find_real_name(const char *name);
+char *pmu_find_alias_name(const char *name);
+
  #endif /* __PMU_H */