Re: [PATCH RFC] preempt: Put preempt_enable() within an instrumentation*() section.

[Peter Zijlstra]

On Thu, Mar 09, 2023 at 08:27:24AM +0100, Sebastian Andrzej Siewior wrote:
> Callers of preempt_enable() can be within an noinstr section leading to:
> | vmlinux.o: warning: objtool: native_sched_clock+0x97: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
> | vmlinux.o: warning: objtool: kvm_clock_read+0x22: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
> | vmlinux.o: warning: objtool: local_clock+0xb4: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
> | vmlinux.o: warning: objtool: enter_from_user_mode+0xea: call to preempt_schedule_thunk() leaves .noinstr.text section
> | vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x140: call to preempt_schedule_thunk() leaves .noinstr.text section
> | vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare+0xf2: call to preempt_schedule_thunk() leaves .noinstr.text section
> | vmlinux.o: warning: objtool: irqentry_enter_from_user_mode+0xea: call to preempt_schedule_thunk() leaves .noinstr.text section
> 
> This only happens on CONFIG_PREEMPT+ due to the conditional call into the scheduler.

I think I see; but I can't reproduce. I use:

  defconfig + CONFIG_PREEMPT + CONFIG_DEBUG_ENTRY

let me try and figure out wtf to do about this :/