[PATCH 2/3] selftests/lib.mk: Introduce check to validate required configs

[Siddharth Menon <simeddon@gmail.com>]

Currently, kselftests does not have a generalised mechanism to skip compilation
and run tests when required kernel configuration flags are missing.

This patch introduces a check to validate the presence of required config flags
specified in the selftest makefile. In case scripts/config is not found,
this check is skipped.

Use TEST_CONFIG_DEPS to check for specific config options before compiling,
example usage:
```
TEST_CONFIG_DEPS := CONFIG_LIVEPATCH CONFIG_DYNAMIC_DEBUG
```
Here it checks whether CONFIG_LIVEPATCH and CONFIG_DYNAMIC_DEBUG are enabled.

Suggested-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Siddharth Menon <simeddon@gmail.com>
---
 tools/testing/selftests/lib.mk | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
index d6edcfcb5be8..7ca713237bf7 100644
--- a/tools/testing/selftests/lib.mk
+++ b/tools/testing/selftests/lib.mk
@@ -97,7 +97,21 @@ TEST_GEN_PROGS := $(patsubst %,$(OUTPUT)/%,$(TEST_GEN_PROGS))
 TEST_GEN_PROGS_EXTENDED := $(patsubst %,$(OUTPUT)/%,$(TEST_GEN_PROGS_EXTENDED))
 TEST_GEN_FILES := $(patsubst %,$(OUTPUT)/%,$(TEST_GEN_FILES))
 
-all: $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED) $(TEST_GEN_FILES) \
+KDIR ?= /lib/modules/$(shell uname -r)/build
+
+define CHECK_CONFIG_DEPS
+    $(if $(wildcard $(KDIR)/scripts/config),
+        $(eval MISSING_FLAGS := $(filter-out 1,$(foreach cfg,$(TEST_CONFIG_DEPS),\
+            $(shell cd $(KDIR) && scripts/config --state $(cfg) | grep -q '^\(y\|m\)$$' && echo 1 || echo $(cfg))))),
+        $(info Skipping CHECK_GEN_REQ: $(KDIR)/scripts/config not found)
+    )
+    $(if $(MISSING_FLAGS),$(error Missing required config flags: $(MISSING_FLAGS)))
+endef
+
+check_config_deps:
+	$(call CHECK_CONFIG_DEPS)
+
+all: check_config_deps $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED) $(TEST_GEN_FILES) \
 	$(if $(TEST_GEN_MODS_DIR),gen_mods_dir)
 
 define RUN_TESTS
@@ -228,4 +242,4 @@ $(OUTPUT)/%:%.S
 	$(LINK.S) $^ $(LDLIBS) -o $@
 endif
 
-.PHONY: run_tests all clean install emit_tests gen_mods_dir clean_mods_dir
+.PHONY: run_tests all clean install emit_tests gen_mods_dir clean_mods_dir check_config_deps
-- 
2.39.5