perf test pmu: Refactor format test and exposed test APIs

In tests/pmu.c, make a common utility that creates a PMU in a mkdtemp
directory and uses regular PMU parsing logic to load that PMU. Formats
must still be eagerly loaded as by default the PMU code assumes devices
are going to be in sysfs.

In util/pmu.[ch], hide perf_pmu__format_parse but add the eager argument
to perf_pmu__lookup called by perf_pmus__add_test_pmu. Later patches
will eagerly load other non-sysfs files when eager loading is enabled.

In tests/pmu.c, rather than manually constructing a list of term
arguments, just use the term parsing code from a string.

Add more comments and debug logging.

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/r/20240502213507.2339733-4-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index 2fd369e45832..b9b4c5eb5002 100644
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -124,7 +124,8 @@ struct perf_pmu *perf_pmus__find(const char *name)
 		return NULL;
 
 	dirfd = perf_pmu__event_source_devices_fd();
-	pmu = perf_pmu__lookup(core_pmu ? &core_pmus : &other_pmus, dirfd, name);
+	pmu = perf_pmu__lookup(core_pmu ? &core_pmus : &other_pmus, dirfd, name,
+			       /*eager_load=*/false);
 	close(dirfd);
 
 	if (!pmu) {
@@ -159,7 +160,8 @@ static struct perf_pmu *perf_pmu__find2(int dirfd, const char *name)
 	if (core_pmu && read_sysfs_core_pmus)
 		return NULL;
 
-	return perf_pmu__lookup(core_pmu ? &core_pmus : &other_pmus, dirfd, name);
+	return perf_pmu__lookup(core_pmu ? &core_pmus : &other_pmus, dirfd, name,
+				/*eager_load=*/false);
 }
 
 static int pmus_cmp(void *priv __maybe_unused,
@@ -696,3 +698,13 @@ struct perf_pmu *perf_pmus__find_core_pmu(void)
 {
 	return perf_pmus__scan_core(NULL);
 }
+
+struct perf_pmu *perf_pmus__add_test_pmu(int test_sysfs_dirfd, const char *name)
+{
+	/*
+	 * Some PMU functions read from the sysfs mount point, so care is
+	 * needed, hence passing the eager_load flag to load things like the
+	 * format files.
+	 */
+	return perf_pmu__lookup(&other_pmus, test_sysfs_dirfd, name, /*eager_load=*/true);
+}