Re: [PATCH v6 13/29] arm64/build: Assert for unwanted sections

[Arvind Sankar]

On Tue, Oct 27, 2020 at 01:28:02PM -0700, Nick Desaulniers wrote:
> > commit 3193c0836f203a91bef96d88c64cccf0be090d9c
> > Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > Date:   Wed Jul 17 20:36:45 2019 -0500
> >
> >     bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()
> >
> > has
> >
> > Fixes: e55a73251da3 ("bpf: Fix ORC unwinding in non-JIT BPF code")
> >
> > and mentions objtool and CONFIG_RETPOLINE.
> 
> Thanks for the context.  It might be time to revisit the above commit.
> If I revert it (small conflict that's easy to fixup),
> kernel/bpf/core.o builds cleanly with defconfig+GCC-9.3, so maybe
> obtool did get smart enough to handle that case?  Probably regresses
> the performance of that main dispatch loop for BPF, but not sure what
> folks are expecting when retpolines are enabled.
> -- 
> Thanks,
> ~Nick Desaulniers

The objtool issue was with RETPOLINE disabled.