[PATCH bpf-next v7 6/9] selftests/bpf: derive the bench object list from the sources

The bench binary links every benchs/bench_*.c object, but the link
rule names them one by one in a hand-maintained list, which has to be
extended by hand for every new benchmark although the pattern rule
already builds any bench_*.c placed in benchs/. Derive the list with
a wildcard instead: a new benchmark is compiled and linked in by
dropping its source there (its skeleton dependency line, when it has
one, is still declared next to the others).

The derived list is sorted, which changes the link order of the bench
objects (previously roughly chronological) and with it the symbol
layout of the binary; no benchmark behaves differently. The trailing
'#' terminator goes away together with the block it closed: the two
remaining entries after the variable are fixed, so the append
friendliness it provided no longer buys anything.

Signed-off-by: Mykola Lysenko <[email protected]>
---
 tools/testing/selftests/bpf/Makefile | 28 ++++------------------------
 1 file changed, 4 insertions(+), 24 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 2070a07015ae..9f18dd291736 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -955,7 +955,8 @@ $(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
 	$(call msg,CXX,,$@)
 	$(Q)$(CXX) $(CXXFLAGS) $(filter %.a %.o %.cpp,$^) $(LDLIBS) -o $@
 
-# Benchmark runner
+# Benchmark runner. Every benchs/bench_*.c is compiled and linked in.
+BENCH_OBJS := $(sort $(patsubst benchs/%.c,$(OUTPUT)/%.o,$(wildcard benchs/bench_*.c)))
 $(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h $(BPFOBJ)
 	$(call msg,CC,,$@)
 	$(Q)$(CC) $(CFLAGS) -O2 -c $(filter %.c,$^) $(LDLIBS) -o $@ $(call skip_on_fail,BENCH)
@@ -986,30 +987,9 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o \
 		 $(TESTING_HELPERS) \
 		 $(TRACE_HELPERS) \
 		 $(CGROUP_HELPERS) \
-		 $(OUTPUT)/bench_count.o \
-		 $(OUTPUT)/bench_rename.o \
-		 $(OUTPUT)/bench_trigger.o \
-		 $(OUTPUT)/bench_ringbufs.o \
-		 $(OUTPUT)/bench_bloom_filter_map.o \
-		 $(OUTPUT)/bench_bpf_loop.o \
-		 $(OUTPUT)/bench_bpf_for.o \
-		 $(OUTPUT)/bench_strncmp.o \
-		 $(OUTPUT)/bench_bpf_hashmap_full_update.o \
-		 $(OUTPUT)/bench_local_storage.o \
-		 $(OUTPUT)/bench_local_storage_rcu_tasks_trace.o \
-		 $(OUTPUT)/bench_bpf_hashmap_lookup.o \
-		 $(OUTPUT)/bench_local_storage_create.o \
-		 $(OUTPUT)/bench_htab_mem.o \
-		 $(OUTPUT)/bench_bpf_crypto.o \
-		 $(OUTPUT)/bench_sockmap.o \
-		 $(OUTPUT)/bench_lpm_trie_map.o \
-		 $(OUTPUT)/bench_bpf_timing.o \
-		 $(OUTPUT)/bench_bpf_nop.o \
-		 $(OUTPUT)/bench_xdp_lb.o \
-		 $(OUTPUT)/bench_libarena.o \
+		 $(BENCH_OBJS) \
 		 $(OUTPUT)/usdt_1.o \
-		 $(OUTPUT)/usdt_2.o \
-		 #
+		 $(OUTPUT)/usdt_2.o
 	$(call msg,BINARY,,$@)
 	$(Q)$(CC) $(CFLAGS) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@ $(call skip_on_fail,LINK,,(some benchmarks may have been skipped))
 
-- 
2.43.0