linux-kernel - Re: [PATCH] arm64: kvm: Delete duplicated label: in invalid

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Message-ID: <20200414145712.603e37d5@why>
Date:   Tue, 14 Apr 2020 14:57:12 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Fangrui Song <maskray@...gle.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        kvmarm@...ts.cs.columbia.edu, LKML <linux-kernel@...r.kernel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH] arm64: kvm: Delete duplicated label: in invalid_vector

Hi Nick,

On Mon, 13 Apr 2020 16:37:10 -0700
Nick Desaulniers <ndesaulniers@...gle.com> wrote:

> On Mon, Apr 13, 2020 at 4:10 PM Fangrui Song <maskray@...gle.com> wrote:
> >
> > SYM_CODE_START defines \label , so it is redundant to define \label again.
> > A redefinition at the same place is accepted by GNU as
> > (https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=159fbb6088f17a341bcaaac960623cab881b4981)
> > but rejected by the clang integrated assembler.
> >
> > Fixes: 617a2f392c92 ("arm64: kvm: Annotate assembly using modern annoations")  
> 
> Thanks for the patch!  I think a more accurate Fixes tag would be:
> Fixes: 2b28162cf65a ("arm64: KVM: HYP mode entry points")

I'm not sure this commit is accurate. At that time, there was no other
declaration for \label and dropping it would simply break compilation.
I believe that Fangrui is correct in his analysis that 617a2f392c92 is
the first broken commit.

> With this patch applied, and your other arm64 integrated assembler
> patch (https://lore.kernel.org/linux-arm-kernel/20200413033811.75074-1-maskray@google.com/T/#u),
> I can now assemble arch/arm64/kvm/.

Progress! ;-)

> Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
> Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> 
> > Link: https://github.com/ClangBuiltLinux/linux/issues/988
> > Signed-off-by: Fangrui Song <maskray@...gle.com>
> > ---
> >  arch/arm64/kvm/hyp/hyp-entry.S | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
> > index c2a13ab3c471..9c5cfb04170e 100644
> > --- a/arch/arm64/kvm/hyp/hyp-entry.S
> > +++ b/arch/arm64/kvm/hyp/hyp-entry.S
> > @@ -198,7 +198,6 @@ SYM_CODE_END(__hyp_panic)
> >  .macro invalid_vector  label, target = __hyp_panic
> >         .align  2
> >  SYM_CODE_START(\label)
> > -\label:
> >         b \target
> >  SYM_CODE_END(\label)
> >  .endm
> > --
> > 2.26.0.110.g2183baf09c-goog
> >  
> 
> 

I'll pick this up as soon as we've sorted the queue with the rest of
the fixes.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...