perf pmu: Add PMU alias support

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,,

Committer notes:

Rename 'struct perf_pmu_alias_name' to 'pmu_alias', the 'perf_' prefix
should be used for libperf, things inside just tools/perf/ are being
moved away from that prefix.

Also 'pmu_alias' is shorter and reflects the abstraction.

Also don't use 'pmu' as the name for variables for that type, we should
use that for the 'struct perf_pmu' variables, avoiding confusion. Use
'pmu_alias' for 'struct pmu_alias' variables.

Co-developed-by: Jin Yao <yao.jin@linux.intel.com>
Co-developed-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.garry@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Link: http://lore.kernel.org/lkml/20210902065955.1299-2-yao.jin@linux.intel.com
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 37 insertions, 3 deletions

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 5f486ccb6fe6..bdabd62170d2 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -945,6 +945,18 @@ perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
 	return NULL;
 }
 
+char * __weak
+pmu_find_real_name(const char *name)
+{
+	return (char *)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];
@@ -958,13 +970,15 @@ 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;
 	LIST_HEAD(format);
 	LIST_HEAD(aliases);
 	__u32 type;
+	char *name = pmu_find_real_name(lookup_name);
 	bool is_hybrid = perf_pmu__hybrid_mounted(name);
+	char *alias_name;
 
 	/*
 	 * Check pmu name for hybrid and the pmu may be invalid in sysfs
@@ -995,6 +1009,16 @@ static struct perf_pmu *pmu_lookup(const char *name)
 
 	pmu->cpus = pmu_cpumask(name);
 	pmu->name = strdup(name);
+	if (!pmu->name)
+		goto err;
+
+	alias_name = pmu_find_alias_name(name);
+	if (alias_name) {
+		pmu->alias_name = strdup(alias_name);
+		if (!pmu->alias_name)
+			goto err;
+	}
+
 	pmu->type = type;
 	pmu->is_uncore = pmu_is_uncore(name);
 	if (pmu->is_uncore)
@@ -1017,15 +1041,22 @@ static struct perf_pmu *pmu_lookup(const char *name)
 	pmu->default_config = perf_pmu__get_default_config(pmu);
 
 	return pmu;
+err:
+	if (pmu->name)
+		free(pmu->name);
+	free(pmu);
+	return NULL;
 }
 
 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))
+	list_for_each_entry(pmu, &pmus, list) {
+		if (!strcmp(pmu->name, name) ||
+		    (pmu->alias_name && !strcmp(pmu->alias_name, name)))
 			return pmu;
+	}
 
 	return NULL;
 }
@@ -1919,6 +1950,9 @@ 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;