perf cpuid: Introduce a platform specific cpuid compare function

The function get_cpuid_str() is called by perf_pmu__getcpuid() and on
s390 returns a complete description of the CPU and its capabilities,
which is a comma separated list.

To map the CPU type with the value defined in the
pmu-events/arch/s390/mapfile.csv, introduce an architecture specific
cpuid compare function named strcmp_cpuid_str()

The currently used regex algorithm is defined as the weak default and
will be used if no platform specific one is defined. This matches the
current behavior.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180213151419.80737-3-tmricht@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/s390/util/header.c

@@ -146,3 +146,21 @@ char *get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
 		zfree(&buf);
 	return buf;
 }
+
+/*
+ * Compare the cpuid string returned by get_cpuid() function
+ * with the name generated by the jevents file read from
+ * pmu-events/arch/s390/mapfile.csv.
+ *
+ * Parameter mapcpuid is the cpuid as stored in the
+ * pmu-events/arch/s390/mapfile.csv. This is just the type number.
+ * Parameter cpuid is the cpuid returned by function get_cpuid().
+ */
+int strcmp_cpuid_str(const char *mapcpuid, const char *cpuid)
+{
+	char *cp = strchr(cpuid, ',');
+
+	if (cp == NULL)
+		return -1;
+	return strncmp(cp + 1, mapcpuid, strlen(mapcpuid));
+}

tools/perf/util/header.h

@@ -174,4 +174,5 @@ int write_padded(struct feat_fd *fd, const void *bf,
 int get_cpuid(char *buffer, size_t sz);
 
 char *get_cpuid_str(struct perf_pmu *pmu __maybe_unused);
+int strcmp_cpuid_str(const char *s1, const char *s2);
 #endif /* __PERF_HEADER_H */

tools/perf/util/pmu.c

@@ -576,6 +576,34 @@ char * __weak get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
 	return NULL;
 }
 
+/* Return zero when the cpuid from the mapfile.csv matches the
+ * cpuid string generated on this platform.
+ * Otherwise return non-zero.
+ */
+int __weak strcmp_cpuid_str(const char *mapcpuid, const char *cpuid)
+{
+	regex_t re;
+	regmatch_t pmatch[1];
+	int match;
+
+	if (regcomp(&re, mapcpuid, REG_EXTENDED) != 0) {
+		/* Warn unable to generate match particular string. */
+		pr_info("Invalid regular expression %s\n", mapcpuid);
+		return 1;
+	}
+
+	match = !regexec(&re, cpuid, 1, pmatch, 0);
+	regfree(&re);
+	if (match) {
+		size_t match_len = (pmatch[0].rm_eo - pmatch[0].rm_so);
+
+		/* Verify the entire string matched. */
+		if (match_len == strlen(cpuid))
+			return 0;
+	}
+	return 1;
+}
+
 static char *perf_pmu__getcpuid(struct perf_pmu *pmu)
 {
 	char *cpuid;
@@ -610,31 +638,14 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
 
 	i = 0;
 	for (;;) {
-		regex_t re;
-		regmatch_t pmatch[1];
-		int match;
-
 		map = &pmu_events_map[i++];
 		if (!map->table) {
 			map = NULL;
 			break;
 		}
 
-		if (regcomp(&re, map->cpuid, REG_EXTENDED) != 0) {
-			/* Warn unable to generate match particular string. */
-			pr_info("Invalid regular expression %s\n", map->cpuid);
+		if (!strcmp_cpuid_str(map->cpuid, cpuid))
 			break;
-		}
-
-		match = !regexec(&re, cpuid, 1, pmatch, 0);
-		regfree(&re);
-		if (match) {
-			size_t match_len = (pmatch[0].rm_eo - pmatch[0].rm_so);
-
-			/* Verify the entire string matched. */
-			if (match_len == strlen(cpuid))
-				break;
-		}
 	}
 	free(cpuid);
 	return map;