samples/bpf: fix warning with ignored-attributes

Currently, compiling the bpf programs will result the warning with the
ignored attribute as follows. This commit fixes the warning by adding
cf-protection option.

    In file included from ./arch/x86/include/asm/linkage.h:6:
    ./arch/x86/include/asm/ibt.h:77:8: warning: 'nocf_check' attribute ignored; use -fcf-protection to enable the attribute [-Wignored-attributes]
    extern __noendbr u64 ibt_save(bool disable);
           ^
    ./arch/x86/include/asm/ibt.h:32:34: note: expanded from macro '__noendbr'
                                       ^

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Link: https://lore.kernel.org/r/20230818090119.477441-2-danieltimlee@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 595b98d..b32cb8a 100644 (file)
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -440,7 +440,7 @@ $(obj)/%.o: $(src)/%.c
                -Wno-gnu-variable-sized-type-not-at-end \
                -Wno-address-of-packed-member -Wno-tautological-compare \
                -Wno-unknown-warning-option $(CLANG_ARCH_ARGS) \
-               -fno-asynchronous-unwind-tables \
+               -fno-asynchronous-unwind-tables -fcf-protection \
                -I$(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) | \