linux-kernel - Re: [GIT PULL] Please pull powerpc/linux.git powerpc-5.8-1 tag

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Message-ID: <CAHk-=wh5vSwYqF=YiKOOGBHE=hCwnes_ndbP4QOyjPK_Xocz7w@mail.gmail.com>
Date:   Fri, 5 Jun 2020 12:01:05 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, ajd@...ux.ibm.com,
        alistair@...ple.id.au,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>, Qian Cai <cai@....pw>,
        chenzhou10@...wei.com,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Christophe Leroy <christophe.leroy@....fr>,
        christophe.leroy@...roup.eu, clg@...d.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        ego@...ux.vnet.ibm.com,
        Markus Elfring <elfring@...rs.sourceforge.net>,
        emmanuel.nicolet@...il.com, fbarrat@...ux.ibm.com,
        geoff@...radead.org, "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        haren@...ux.ibm.com, hbathini@...ux.ibm.com,
        Herbert Xu <herbert@...dor.apana.org.au>, huhai@...kylinos.cn,
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        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
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        mikey@...ling.org, Nathan Chancellor <natechancellor@...il.com>,
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        Nick Piggin <npiggin@...il.com>,
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        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        rzinsly@...ux.ibm.com, sbobroff@...ux.ibm.com,
        Segher Boessenkool <segher@...nel.crashing.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>, st5pub@...dex.ru,
        Takashi Iwai <tiwai@...e.de>, wangxiongfeng2@...wei.com,
        wsa@...nel.org
Subject: Re: [GIT PULL] Please pull powerpc/linux.git powerpc-5.8-1 tag

On Fri, Jun 5, 2020 at 9:38 AM Michael Ellerman <mpe@...erman.id.au> wrote:
>
> I've pushed the result of my resolution of the conflicts to the powerpc/merge
> branch, if you want to look at that, though I've also tried to describe it in
> full below.

I ended up doing the machine_check_exception() differently, because I
felt the code itself was done wrong and I wanted to add a note about
that.

Having the same function have completely different semantics depending
on a platform issue is just fundamentally wrong, and makes not just
for fragile code, but also means that you can't do single image
kernels.

It should be two different functions, possibly just

   non_nmi_fn() { ... }

   nmi_fn() { nmi_enter(); non_nmi_fn(); nmi_exit(); }

and now you don't have odd rules for the same function that depends on
how the platform happens to call it.

I didn't do the above. I did something that looked like the old code,
but had a comment. Oh well.

But thanks for describing the merge, I'd have missed the place where
there was a new use of pgd_oiffset().

..and then when I actually compared whether I otherwise got the same
result as you, I realized that this all depends on the module tree.

I'll go merge that first, and then re-do this all. Oh well.

               Linus