objtool failures with -march=atom

[Arnd Bergmann]

With the latest objtool failure, I get countless warnings when
-march=atom or -mtune=atom is used,
at least with gcc-4.9 through gcc-7 (I did not try older versions:

kernel/sched/core.o: warning: objtool:
trace_raw_output_sched_stat_runtime()+0x9a: return with modified stack
frame
kernel/sched/core.o: warning: objtool: cpu_cgroup_fork()+0x7c: return
with modified stack frame
kernel/sched/core.o: warning: objtool: walk_tg_tree_from()+0xd3:
return with modified stack frame
kernel/sched/core.o: warning: objtool: ttwu_do_wakeup()+0x2a8: return
with modified stack frame
kernel/sched/core.o: warning: objtool: do_set_cpus_allowed()+0x1fe:
return with modified stack frame
kernel/sched/core.o: warning: objtool: sched_ttwu_pending()+0xf2:
return with modified stack frame
kernel/sched/core.o: warning: objtool: sched_exec()+0xd0: return with
modified stack frame
kernel/sched/core.o: warning: objtool: task_sched_runtime()+0x148:
return with modified stack frame
kernel/sched/core.o: warning: objtool: sched_move_task()+0x176: return
with modified stack frame
kernel/sched/core.o: warning: objtool: sched_init()+0x6cb: return with
modified stack frame

Can you have a look?

There are probably other failures as well, I'm trying to reproduce the
others now with atom
optimizations disabled.

        Arnd