Re: [patch V4 part 2 06/18] x86/entry: Move irq flags tracing to prepare_exit_to_usermode()

[Thomas Gleixner]

Andy Lutomirski <luto@xxxxxxxxxx> writes:
> On Tue, May 5, 2020 at 7:14 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>>
>> This is another step towards more C-code and less convoluted ASM.
>>
>> Similar to the entry path, invoke the tracer before context tracking which
>> might turn off RCU and invoke lockdep as the last step before going back to
>> user space. Annotate the code sections in exit_to_user_mode() accordingly
>> so objtool won't complain about the tracer invocation.
>
> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
>
> Note to self: the nmi code needs to be reworked to go through
> prepare_exit_to_usermode(), too.  I'll do this once this whole pile
> lands.

Why? NMI does not set any work stuff or preemption. If something needs
to be done then NMI raises irq_work which uses the regular path.

Thanks,

        tglx