Re: [PATCH] bpf: Tweak BPF jump table optimizations for objtool compatibility

On Tue, May 05, 2020 at 12:14:05PM -0700, Alexei Starovoitov wrote:

quoted

Hi,

I see the objtool warning:
kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0x33: call without frame pointer save/setup

when using:
gcc (SUSE Linux) 9.3.1 20200406 [revision 6db837a5288ee3ca5ec504fbd5a765817e556ac2]

with the attached config file.

Thanks Randy. I reproduced it.

This problem isn't a mystery, it's caused by __attribute__((optimize)).

The only real solution is to revert

  3193c0836f20 ("bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()")

Once you do that (and disable retpolines) then you should see the
problem described in my other email.

-- 
Josh