Re: [patch V6 36/37] x86/entry: Move paranoid irq tracing out of ASM code

[Thomas Gleixner]

Andy Lutomirski <luto@xxxxxxxxxx> writes:

> On Wed, May 20, 2020 at 8:17 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>>
>> Andy Lutomirski <luto@xxxxxxxxxx> writes:
>>
>> > On Fri, May 15, 2020 at 5:11 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>> >
>> > I think something's missing here.  With this patch applied, don't we
>> > get to exc_debug_kernel() -> handle_debug() without doing
>> > idtentry_enter() or equivalent?  And that can even enable IRQs.
>> >
>> > Maybe exc_debug_kernel() should wrap handle_debug() in some
>> > appropriate _enter() / _exit() pair?
>>
>> I'm the one who is missing something here, i.e. the connection of this
>> patch to #DB. exc_debug_kernel() still looks like this:
>>
>>         nmi_enter_notrace();
>>         handle_debug(regs, dr6, false);
>>         nmi_exit_notrace();
>>
>> Confused.
>>
>
> Hmm.  I guess the code is correct-ish or at least as correct as it
> ever was.  But $SUBJECT says "Move paranoid irq tracing out of ASM
> code" but you didn't move it into all the users.  So now the NMI code
> does trace_hardirqs_on_prepare() but the #DB code doesn't.  Perhaps
> the changelog should mention this.

Duh. I simply missed to add it.

> exc_kernel_debug() is an atrocity.  Every now and then I get started
> on cleanup it up and so far I always get mired in the giant amount of
> indirection.
>
> So Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> if you write a credible
> changelog.