selftests/bpf: do not ignore clang failures

When compiling an eBPF prog fails, make still returns 0, because
failing clang command's output is piped to llc and therefore its
exit status is ignored.

When clang fails, pipe the string "clang failed" to llc. This will make
llc fail with an informative error message. This solution was chosen
over using pipefail, having separate targets or getting rid of llc
invocation due to its simplicity.

In addition, pull Kbuild.include in order to get .DELETE_ON_ERROR target,
which would cause partial .o files to be removed.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 2620406a53ecc341c9e6704b043c33a008ea7d78..8312db1ae7c225f3203c7f46add46027b3816c5b 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+include ../../../../scripts/Kbuild.include
 
 LIBDIR := ../../../lib
 BPFDIR := $(LIBDIR)/bpf
@@ -196,8 +197,8 @@ $(ALU32_BUILD_DIR)/test_progs_32: prog_tests/*.c
 
 $(ALU32_BUILD_DIR)/%.o: progs/%.c $(ALU32_BUILD_DIR) \
                                        $(ALU32_BUILD_DIR)/test_progs_32
-       $(CLANG) $(CLANG_FLAGS) \
-                -O2 -target bpf -emit-llvm -c $< -o - |      \
+       ($(CLANG) $(CLANG_FLAGS) -O2 -target bpf -emit-llvm -c $< -o - || \
+               echo "clang failed") | \
        $(LLC) -march=bpf -mattr=+alu32 -mcpu=$(CPU) $(LLC_FLAGS) \
                -filetype=obj -o $@
 ifeq ($(DWARF2BTF),y)
@@ -208,16 +209,16 @@ endif
 # Have one program compiled without "-target bpf" to test whether libbpf loads
 # it successfully
 $(OUTPUT)/test_xdp.o: progs/test_xdp.c
-       $(CLANG) $(CLANG_FLAGS) \
-               -O2 -emit-llvm -c $< -o - | \
+       ($(CLANG) $(CLANG_FLAGS) -O2 -emit-llvm -c $< -o - || \
+               echo "clang failed") | \
        $(LLC) -march=bpf -mcpu=$(CPU) $(LLC_FLAGS) -filetype=obj -o $@
 ifeq ($(DWARF2BTF),y)
        $(BTF_PAHOLE) -J $@
 endif
 
 $(OUTPUT)/%.o: progs/%.c
-       $(CLANG) $(CLANG_FLAGS) \
-                -O2 -target bpf -emit-llvm -c $< -o - |      \
+       ($(CLANG) $(CLANG_FLAGS) -O2 -target bpf -emit-llvm -c $< -o - || \
+               echo "clang failed") | \
        $(LLC) -march=bpf -mcpu=$(CPU) $(LLC_FLAGS) -filetype=obj -o $@
 ifeq ($(DWARF2BTF),y)
        $(BTF_PAHOLE) -J $@