RE: [PATCH v8 30/33] x86/fred: allow dynamic stack frame size

[Thomas Gleixner]

On Tue, Jun 06 2023 at 06:18, Xin3 Li wrote:
>> > A FRED stack frame could contain different amount of information for
>> > This approach also works for IDT, thus we unify the code.
>> 
>> And thereby remove the useful comment and replace it with an undocumented
>> macro mess.
>> 
>> I'm simply refusing to review this. It's not my job to understand this
>> undocumented hackery.
>> 
>
> I believe it's a nice idea to allow dynamic stack frame size, at least for
> FRED.

Believe belongs in the realm of religion. What we need here are proper
facts, explanations and justifications. Nice ideas are not helpful when
they are not having a value.

> It's totally my bad that I didn't make it meet the minimum standards,
> I will rewrite the commit message and add better comments.
>
> After a second thought, I probably should only apply the change to FRED for
> 2 reasons, the change seems problematic with ESPFIX (which FRED
> doesn't need),

Indeed. Making this FRED only is going to need even more justification.

> and such corner cases are hard to test (self-tests needed?)

There is a test. It's not that hard to find:

# git grep -li ESPFIX tools/testing/selftests/
tools/testing/selftests/x86/sigreturn.c

Thanks,

        tglx