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From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Li, Xin3" <xin3.li@intel.com>,
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        "Christopherson,, Sean" <seanjc@google.com>,
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        "Shankar, Ravi V" <ravi.v.shankar@intel.com>,
        "jiangshanlai@gmail.com" <jiangshanlai@gmail.com>,
        "Kang, Shan" <shan.kang@intel.com>
Subject: RE: [PATCH v8 30/33] x86/fred: allow dynamic stack frame size
In-Reply-To: <SA1PR11MB673430AC2D6F20C5F77FC83AA852A@SA1PR11MB6734.namprd11.prod.outlook.com>
References: <20230410081438.1750-1-xin3.li@intel.com>
 <20230410081438.1750-31-xin3.li@intel.com> <87wn0i578t.ffs@tglx>
 <SA1PR11MB673430AC2D6F20C5F77FC83AA852A@SA1PR11MB6734.namprd11.prod.outlook.com>
Date:   Tue, 06 Jun 2023 15:27:25 +0200
Message-ID: <87fs74lo02.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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