perf vendor events: Use more flexible pattern matching for CPU identification for mapfile.csv

The powerpc cpuid information includes chip revision information.
Changes between chip revisions are usually minor bug fixes and usually
do not affect the operation of the performance monitoring hardware.

The original mapfile.csv matching requires enumerating every possible
cpuid string.  When a new minor chip revision is produced a new entry
has to be added to the mapfile.csv and the code recompiled to allow perf
to have the implementation specific perf events for this new minor
revision.  For users of various distibutions of Linux having to wait for
a new release of the kernel's perf tool to be built with these trivial
patches is inconvenient.

Using regular expressions rather than exactly string matching of the
entire cpuid string allows developers to write mapfile.csv files that do
not require patches and recompiles for each of these minor version
changes.  If special cases need to be made for some particular versions,
they can be placed earlier in the mapfile.csv file before the more
general matches.

Signed-off-by: William Cohen <wcohen@redhat.com>
Tested-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shriya <shriyak@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20171204145728.16792-1-wcohen@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 8b7c151579c0..57e38fdf0b34 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -12,6 +12,7 @@
 #include <dirent.h>
 #include <api/fs/fs.h>
 #include <locale.h>
+#include <regex.h>
 #include "util.h"
 #include "pmu.h"
 #include "parse-events.h"
@@ -609,14 +610,31 @@ 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 (!strcmp(map->cpuid, cpuid))
+		if (regcomp(&re, map->cpuid, REG_EXTENDED) != 0) {
+			/* Warn unable to generate match particular string. */
+			pr_info("Invalid regular expression %s\n", map->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;