bpf, samples: Add -fno-asynchronous-unwind-tables to BPF Clang invocation

The samples/bpf Makefile currently compiles BPF files in a way that will
produce an .eh_frame section, which will in turn confuse libbpf and produce
errors when loading BPF programs, like:

  libbpf: elf: skipping unrecognized data section(32) .eh_frame
  libbpf: elf: skipping relo section(33) .rel.eh_frame for section(32) .eh_frame

Fix this by instruction Clang not to produce this section, as it's useless
for BPF anyway.

Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210705103841.180260-1-toke@redhat.com

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 520434e..036998d 100644 (file)
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -331,6 +331,7 @@ $(obj)/%.o: $(src)/%.c
                -Wno-gnu-variable-sized-type-not-at-end \
                -Wno-address-of-packed-member -Wno-tautological-compare \
                -Wno-unknown-warning-option $(CLANG_ARCH_ARGS) \
+               -fno-asynchronous-unwind-tables \
                -I$(srctree)/samples/bpf/ -include asm_goto_workaround.h \
                -O2 -emit-llvm -Xclang -disable-llvm-passes -c $< -o - | \
                $(OPT) -O2 -mtriple=bpf-pc-linux | $(LLVM_DIS) | \