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>

6 files changed, 26 insertions, 11 deletions

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 0f308b4db2b9..2b9ede311c31 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -2585,7 +2585,7 @@ int parse_events_term__term(struct parse_events_term **term,
 }
 
 int parse_events_term__clone(struct parse_events_term **new,
-			     struct parse_events_term *term)
+			     const struct parse_events_term *term)
 {
 	char *str;
 	struct parse_events_term temp = *term;
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 5695308efab9..e7ac1f13376d 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -178,7 +178,7 @@ int parse_events_term__term(struct parse_events_term **term,
 			    enum parse_events__term_type term_rhs,
 			    void *loc_term, void *loc_val);
 int parse_events_term__clone(struct parse_events_term **new,
-			     struct parse_events_term *term);
+			     const struct parse_events_term *term);
 void parse_events_term__delete(struct parse_events_term *term);
 
 void parse_events_terms__delete(struct parse_events_terms *terms);
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 74dd5bd49d9a..fbbc535ed93f 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -182,7 +182,7 @@ static void perf_pmu_format__load(const struct perf_pmu *pmu, struct perf_pmu_fo
  * Parse & process all the sysfs attributes located under
  * the directory specified in 'dir' parameter.
  */
-int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_load)
+static int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_load)
 {
 	struct dirent *evt_ent;
 	DIR *format_dir;
@@ -232,7 +232,7 @@ int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_load)
  * located at:
  * /sys/bus/event_source/devices/<dev>/format as sysfs group attributes.
  */
-static int pmu_format(struct perf_pmu *pmu, int dirfd, const char *name)
+static int pmu_format(struct perf_pmu *pmu, int dirfd, const char *name, bool eager_load)
 {
 	int fd;
 
@@ -241,7 +241,7 @@ static int pmu_format(struct perf_pmu *pmu, int dirfd, const char *name)
 		return 0;
 
 	/* it'll close the fd */
-	if (perf_pmu__format_parse(pmu, fd, /*eager_load=*/false))
+	if (perf_pmu__format_parse(pmu, fd, eager_load))
 		return -1;
 
 	return 0;
@@ -994,7 +994,8 @@ perf_pmu__arch_init(struct perf_pmu *pmu)
 		pmu->mem_events = perf_mem_events;
 }
 
-struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *name)
+struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *name,
+				  bool eager_load)
 {
 	struct perf_pmu *pmu;
 	__u32 type;
@@ -1023,7 +1024,7 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
 	 * type value and format definitions. Load both right
 	 * now.
 	 */
-	if (pmu_format(pmu, dirfd, name))
+	if (pmu_format(pmu, dirfd, name, eager_load))
 		goto err;
 
 	pmu->is_core = is_pmu_core(name);
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 93d03bd3ecbe..561716aa2b25 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -214,7 +214,6 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct parse_events_terms *head_
 			  struct parse_events_error *err);
 int perf_pmu__find_event(struct perf_pmu *pmu, const char *event, void *state, pmu_event_callback cb);
 
-int perf_pmu__format_parse(struct perf_pmu *pmu, int dirfd, bool eager_load);
 void perf_pmu_format__set_value(void *format, int config, unsigned long *bits);
 bool perf_pmu__has_format(const struct perf_pmu *pmu, const char *name);
 int perf_pmu__for_each_format(struct perf_pmu *pmu, void *state, pmu_format_callback cb);
@@ -272,7 +271,8 @@ int perf_pmu__pathname_scnprintf(char *buf, size_t size,
 int perf_pmu__event_source_devices_fd(void);
 int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, int flags);
 
-struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *lookup_name);
+struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *lookup_name,
+				  bool eager_load);
 struct perf_pmu *perf_pmu__create_placeholder_core_pmu(struct list_head *core_pmus);
 void perf_pmu__delete(struct perf_pmu *pmu);
 struct perf_pmu *perf_pmus__find_core_pmu(void);
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);
+}
diff --git a/tools/perf/util/pmus.h b/tools/perf/util/pmus.h
index eec599d8aebd..9d4ded80b8e9 100644
--- a/tools/perf/util/pmus.h
+++ b/tools/perf/util/pmus.h
@@ -24,4 +24,6 @@ int perf_pmus__num_core_pmus(void);
 bool perf_pmus__supports_extended_type(void);
 char *perf_pmus__default_pmu_name(void);
 
+struct perf_pmu *perf_pmus__add_test_pmu(int test_sysfs_dirfd, const char *name);
+
 #endif /* __PMUS_H */