perf pmu: Fix alias matching

Commit c47a559 ("perf tools: Fix pattern matching for same
substring in different PMU type"), may have fixed some alias matching,
but has broken some others.

Firstly it cannot handle the simple scenario of PMU name in form
pmu_name{digits} - it can only handle pmu_name_{digits}.

Secondly it cannot handle more complex matching in the case where we
have multiple tokens. In this scenario, the code failed to realise that
we may examine multiple substrings in the PMU name.

Fix in two ways:

- Change perf_pmu__valid_suffix() to accept a PMU name without '_' in the
  suffix

- Only pay attention to perf_pmu__valid_suffix() for the final token

Also add const qualifiers as necessary to avoid casting.

Fixes: c47a559 ("perf tools: Fix pattern matching for same substring in different PMU type")
Signed-off-by: John Garry <john.garry@huawei.com>
Tested-by: Jin Yao <yao.jin@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/1626793819-79090-1-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pmu.c

@@ -742,9 +742,13 @@ struct pmu_events_map *__weak pmu_events_map__find(void)
 	return perf_pmu__find_map(NULL);
 }
 
-static bool perf_pmu__valid_suffix(char *pmu_name, char *tok)
+/*
+ * Suffix must be in form tok_{digits}, or tok{digits}, or same as pmu_name
+ * to be valid.
+ */
+static bool perf_pmu__valid_suffix(const char *pmu_name, char *tok)
 {
-	char *p;
+	const char *p;
 
 	if (strncmp(pmu_name, tok, strlen(tok)))
 		return false;
@@ -753,12 +757,16 @@ static bool perf_pmu__valid_suffix(char *pmu_name, char *tok)
 	if (*p == 0)
 		return true;
 
-	if (*p != '_')
-		return false;
+	if (*p == '_')
+		++p;
 
-	++p;
-	if (*p == 0 || !isdigit(*p))
-		return false;
+	/* Ensure we end in a number */
+	while (1) {
+		if (!isdigit(*p))
+			return false;
+		if (*(++p) == 0)
+			break;
+	}
 
 	return true;
 }
@@ -789,12 +797,19 @@ bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
 	 *	    match "socket" in "socketX_pmunameY" and then "pmuname" in
 	 *	    "pmunameY".
 	 */
-	for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
+	while (1) {
+		char *next_tok = strtok_r(NULL, ",", &tmp);
+
 		name = strstr(name, tok);
-		if (!name || !perf_pmu__valid_suffix((char *)name, tok)) {
+		if (!name ||
+		    (!next_tok && !perf_pmu__valid_suffix(name, tok))) {
 			res = false;
 			goto out;
 		}
+		if (!next_tok)
+			break;
+		tok = next_tok;
+		name += strlen(tok);
 	}
 
 	res = true;