libbpf: auto-generate list of BPF helper definitions

Get rid of list of BPF helpers in bpf_helpers.h (irony...) and
auto-generate it into bpf_helpers_defs.h, which is now included from
bpf_helpers.h.
Suggested-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/.gitignore

@@ -39,3 +39,4 @@ libbpf.so.*
 test_hashmap
 test_btf_dump
 xdping
+/bpf_helper_defs.h

tools/testing/selftests/bpf/Makefile

@@ -90,6 +90,10 @@ include ../lib.mk
 TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
 all: $(TEST_CUSTOM_PROGS)
 
+bpf_helper_defs.h: $(APIDIR)/linux/bpf.h
+	$(BPFDIR)/../../../scripts/bpf_helpers_doc.py --header 		\
+		--file $(APIDIR)/linux/bpf.h > bpf_helper_defs.h
+
 $(OUTPUT)/urandom_read: $(OUTPUT)/%: %.c
 	$(CC) -o $@ $< -Wl,--build-id
 
@@ -123,7 +127,7 @@ $(OUTPUT)/test_cgroup_attach: cgroup_helpers.c
 # force a rebuild of BPFOBJ when its dependencies are updated
 force:
 
-$(BPFOBJ): force
+$(BPFOBJ): force bpf_helper_defs.h
 	$(MAKE) -C $(BPFDIR) OUTPUT=$(OUTPUT)/
 
 PROBE := $(shell $(LLC) -march=bpf -mcpu=probe -filetype=null /dev/null 2>&1)
@@ -319,4 +323,4 @@ $(VERIFIER_TESTS_H): $(VERIFIER_TEST_FILES) | $(VERIFIER_TESTS_DIR)
 
 EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(ALU32_BUILD_DIR) $(BPF_GCC_BUILD_DIR) \
 	$(VERIFIER_TESTS_H) $(PROG_TESTS_H) $(MAP_TESTS_H) \
-	feature
+	feature bpf_helper_defs.h