linux-kernel - Re: [PATCH 2/3] objtool: Ignore retpoline alternatives

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Date:   Thu, 11 Jan 2018 16:39:38 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Andi Kleen <ak@...ux.intel.com>, Paul Turner <pjt@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Kees Cook <keescook@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        Jiri Kosina <jikos@...nel.org>, gnomes@...rguk.ukuu.org.uk
Subject: Re: [PATCH 2/3] objtool: Ignore retpoline alternatives

On Thu, 2018-01-11 at 10:33 -0600, Josh Poimboeuf wrote:
> On Thu, Jan 11, 2018 at 04:27:38PM +0000, David Woodhouse wrote:
> > 
> > On Wed, 2018-01-10 at 19:48 -0600, Josh Poimboeuf wrote:
> > > 
> > > 
> > > +#define ANNOTATE_NOSPEC_ALTERNATIVE                            \
> > > +       "999:\n\t"                                              \
> > > +       ".pushsection .discard.nospec\n\t"                      \
> > > +       ".long 999b - .\n\t"                                    \
> > > +       ".popsection\n\t"
> > > +
> > 
> >   Ick, numbers. Use .Lfoo_%= instead.
> > 
> I seem to recall that not working with inline asm, maybe old versions of
> GCC don't like it or something?  I can try it and see if 0-day bot
> complains.

You just need %= (for inline asm) instead of \@ (for .macro).

I already fixed it up in
http://git.infradead.org/users/dwmw2/linux-retpoline.git/ and will get
nagmail from 0day shortly if it doesn't work :)

(I love you Fengguang)
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