[PATCH v6 3/4] perf jevents: Switch build to use jevents.py

[Ian Rogers <irogers@google.com>]

Generate pmu-events.c using jevents.py rather than the binary built from
jevents.c. Add a new config variable NO_JEVENTS that is set when there
is no architecture json or an appropriate python interpreter isn't present.
When NO_JEVENTS is defined the file pmu-events/empty-pmu-events.c is copied
and used as the pmu-events.c file.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/Makefile.config               | 19 +++++++++++++++++++
 tools/perf/Makefile.perf                 |  1 +
 tools/perf/pmu-events/Build              | 11 +++++++++--
 tools/perf/pmu-events/empty-pmu-events.c | 21 +++++++++++++++++++++
 4 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 tools/perf/pmu-events/empty-pmu-events.c

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 16c1a87444b8..153c18909ff5 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -889,6 +889,25 @@ else
   endif
 endif
 
+ifneq ($(NO_JEVENTS),1)
+  ifeq ($(wildcard pmu-events/arch/$(SRCARCH)/mapfile.csv),)
+    NO_JEVENTS := 1
+  endif
+endif
+ifneq ($(NO_JEVENTS),1)
+  NO_JEVENTS := 0
+  ifndef PYTHON
+    $(warning No python interpreter disabling jevent generation)
+    NO_JEVENTS := 1
+  else
+    # jevents.py uses f-strings present in Python 3.6 released in Dec. 2016.
+    JEVENTS_PYTHON_GOOD := $(shell $(PYTHON) -c 'import sys;print("1" if(sys.version_info.major >= 3 and sys.version_info.minor >= 6) else "0")' 2> /dev/null)
+    ifneq ($(JEVENTS_PYTHON_GOOD), 1)
+      $(warning Python interpreter too old (older than 3.6) disabling jevent generation)
+      NO_JEVENTS := 1
+    endif
+  endif
+endif
 
 ifndef NO_LIBBFD
   ifeq ($(feature-libbfd), 1)
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 1e29c8936f71..dc6b177ac1de 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -655,6 +655,7 @@ JEVENTS       := $(OUTPUT)pmu-events/jevents
 JEVENTS_IN    := $(OUTPUT)pmu-events/jevents-in.o
 
 PMU_EVENTS_IN := $(OUTPUT)pmu-events/pmu-events-in.o
+export NO_JEVENTS
 
 export JEVENTS
 
diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build
index a055dee6a46a..5e459e1c7a85 100644
--- a/tools/perf/pmu-events/Build
+++ b/tools/perf/pmu-events/Build
@@ -9,10 +9,17 @@ JSON		=  $(shell [ -d $(JDIR) ] &&				\
 JDIR_TEST	=  pmu-events/arch/test
 JSON_TEST	=  $(shell [ -d $(JDIR_TEST) ] &&			\
 			find $(JDIR_TEST) -name '*.json')
+JEVENTS_PY	=  pmu-events/jevents.py
 
 #
 # Locate/process JSON files in pmu-events/arch/
 # directory and create tables in pmu-events.c.
 #
-$(OUTPUT)pmu-events/pmu-events.c: $(JSON) $(JSON_TEST) $(JEVENTS)
-	$(Q)$(call echo-cmd,gen)$(JEVENTS) $(SRCARCH) pmu-events/arch $(OUTPUT)pmu-events/pmu-events.c $(V)
+
+ifeq ($(NO_JEVENTS),1)
+$(OUTPUT)pmu-events/pmu-events.c: pmu-events/empty-pmu-events.c
+	$(Q)cp $< $@
+else
+$(OUTPUT)pmu-events/pmu-events.c: $(JSON) $(JSON_TEST) $(JEVENTS_PY)
+	$(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(SRCARCH) pmu-events/arch $@
+endif
diff --git a/tools/perf/pmu-events/empty-pmu-events.c b/tools/perf/pmu-events/empty-pmu-events.c
new file mode 100644
index 000000000000..08fee615e015
--- /dev/null
+++ b/tools/perf/pmu-events/empty-pmu-events.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * An empty pmu-events.c file used when there is no architecture json files in
+ * arch or when the jevents.py script cannot be run.
+ */
+#include "pmu-events/pmu-events.h"
+
+const struct pmu_events_map pmu_events_map[] = {
+	{
+		.cpuid = 0,
+		.version = 0,
+		.type = 0,
+		.table = 0,
+	},
+};
+
+const struct pmu_sys_events pmu_sys_event_tables[] = {
+	{
+		.table = 0
+	},
+};
-- 
2.36.1.476.g0c4daa206d-goog