linux-kernel - Re: [PATCH v2 2/2] Compiler Attributes: naked can be shared

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Date:   Tue, 18 Sep 2018 20:56:04 +0200
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Eli Friedman <efriedma@...eaurora.org>,
        Christopher Li <sparse@...isli.org>,
        Kees Cook <keescook@...omium.org>,
        Ingo Molnar <mingo@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Joe Perches <joe@...ches.com>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-sparse@...r.kernel.org
Subject: Re: [PATCH v2 2/2] Compiler Attributes: naked can be shared

Hi Greg,

On Tue, Sep 18, 2018 at 7:34 PM, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> On Tue, Sep 18, 2018 at 06:55:42PM +0200, Miguel Ojeda wrote:
>> The naked attribute is supported by at least gcc >= 4.6 (for ARM,
>> which is the only current user), gcc >= 8 (for x86), clang >= 3.1
>> and icc >= 13. See https://godbolt.org/z/350Dyc
>>
>> Therefore, move it out of compiler-gcc.h so that the definition
>> is shared by all compilers.
>>
>> This also fixes Clang support for ARM32 --- 815f0ddb346c
>> ("include/linux/compiler*.h: make compiler-*.h mutually exclusive").
>
> So, with this applied, does clang really build an arm32 kernel
> successfully?  No other problem at all?  And this isn't really a
> regression, arm32 never really worked with clang yet, right?
>

To recap a bit: these two patches come from the "Compiler Attributes"
series which is meant as a general improvement. Since Linus/Andrew/you
didn't comment on whether you wanted or not this for 4.19, we are
assuming they would go in for 4.20. However, Stefan/Nick/... wanted
this for 4.19 instead, they asked me to extract these patches two
separately for 4.19. I let them comment further on the status of Clang
on arm32.

I am going to send a v5 of the entire series without these two
patches, based on -rc4 (or -next, which one do you prefer? I would say
these patches should be applied early in the -next branches, so that
everyone is ready for the change, given it "touches" every translation
unit).

Cheers,
Miguel