From 0513eeee86d67930f3567e450357d8db1cfb4f16 Mon Sep 17 00:00:00 2001 From: Viktor Malik Date: Fri, 1 Nov 2024 09:27:12 +0100 Subject: bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile When building selftests with CFLAGS set via env variable, the value of CFLAGS is propagated into bpftool Makefile (called from selftests Makefile). This makes the compilation fail as _GNU_SOURCE is defined two times - once from selftests Makefile (by including lib.mk) and once from bpftool Makefile (by calling `llvm-config --cflags`): $ CFLAGS="" make -C tools/testing/selftests/bpf [...] CC /bpf-next/tools/testing/selftests/bpf/tools/build/bpftool/btf.o : error: "_GNU_SOURCE" redefined [-Werror] : note: this is the location of the previous definition cc1: all warnings being treated as errors [...] Filter out -D_GNU_SOURCE from the result of `llvm-config --cflags` in bpftool Makefile to prevent this error. Signed-off-by: Viktor Malik Signed-off-by: Andrii Nakryiko Acked-by: Quentin Monnet Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/acec3108b62d4df1436cda777e58e93e033ac7a7.1730449390.git.vmalik@redhat.com --- tools/bpf/bpftool/Makefile | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'tools/bpf') diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index ba927379eb20..a4263dfb5e03 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -147,7 +147,11 @@ ifeq ($(feature-llvm),1) # If LLVM is available, use it for JIT disassembly CFLAGS += -DHAVE_LLVM_SUPPORT LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets - CFLAGS += $(shell $(LLVM_CONFIG) --cflags) + # llvm-config always adds -D_GNU_SOURCE, however, it may already be in CFLAGS + # (e.g. when bpftool build is called from selftests build as selftests + # Makefile includes lib.mk which sets -D_GNU_SOURCE) which would cause + # compilation error due to redefinition. Let's filter it out here. + CFLAGS += $(filter-out -D_GNU_SOURCE,$(shell $(LLVM_CONFIG) --cflags)) LIBS += $(shell $(LLVM_CONFIG) --libs $(LLVM_CONFIG_LIB_COMPONENTS)) ifeq ($(shell $(LLVM_CONFIG) --shared-mode),static) LIBS += $(shell $(LLVM_CONFIG) --system-libs $(LLVM_CONFIG_LIB_COMPONENTS)) -- cgit v1.2.3-58-ga151