[PATCH 2/8] selftests/bpf: build bench.o for any $(OUTPUT)

[Yauheni Kaliuta <yauheni.kaliuta@redhat.com>]

bench.o is produced by implicit rule only if it's built in the same
directory where bench.c is located. If OUTPUT points somewhere else,
build fails.

Make an explicit rule for it (factor out common part).
Add bench.c as a dependency to make it source for CC.

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
---
 tools/testing/selftests/bpf/Makefile | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 09700db35c2d..f0b7d41ed6dd 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -243,6 +243,11 @@ define GCC_BPF_BUILD_RULE
 	$(BPF_GCC) $3 $4 -O2 -c $1 -o $2
 endef
 
+define COMPILE_C_RULE
+	$(call msg,CC,,$@)
+	$(CC) $(CFLAGS) -c $(filter %.c,$^) $(LDLIBS) -o $@
+endef
+
 SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
 
 # Set up extra TRUNNER_XXX "temporary" variables in the environment (relies on
@@ -409,11 +414,11 @@ $(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
 
 # Benchmark runner
 $(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h
-	$(call msg,CC,,$@)
-	$(CC) $(CFLAGS) -c $(filter %.c,$^) $(LDLIBS) -o $@
+	$(COMPILE_C_RULE)
 $(OUTPUT)/bench_rename.o: $(OUTPUT)/test_overhead.skel.h
 $(OUTPUT)/bench_trigger.o: $(OUTPUT)/trigger_bench.skel.h
-$(OUTPUT)/bench.o: bench.h testing_helpers.h
+$(OUTPUT)/bench.o: bench.c bench.h testing_helpers.h
+	$(COMPILE_C_RULE)
 $(OUTPUT)/bench: LDLIBS += -lm
 $(OUTPUT)/bench: $(OUTPUT)/bench.o $(OUTPUT)/testing_helpers.o \
 		 $(OUTPUT)/bench_count.o \
-- 
2.26.2