2020-04-14 13:43:54

by Fangrui Song

Subject: [PATCH] arm64: kvm: Delete duplicated label: in invalid_vector

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")
Link: https://github.com/ClangBuiltLinux/linux/issues/988
Signed-off-by: Fangrui Song <[email protected]>
---
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

2020-04-14 13:44:40

by Nick Desaulniers

Subject: Re: [PATCH] arm64: kvm: Delete duplicated label: in invalid_vector

On Mon, Apr 13, 2020 at 4:10 PM Fangrui Song <[email protected]> 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")

With this patch applied, and your other arm64 integrated assembler
patch (https://lore.kernel.org/linux-arm-kernel/[email protected]/T/#u),
I can now assemble arch/arm64/kvm/.

Reviewed-by: Nick Desaulniers <[email protected]>
Tested-by: Nick Desaulniers <[email protected]>

> Link: https://github.com/ClangBuiltLinux/linux/issues/988
> Signed-off-by: Fangrui Song <[email protected]>
> ---
> 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
>


--
Thanks,
~Nick Desaulniers

2020-04-14 16:06:31

by Marc Zyngier

Subject: Re: [PATCH] arm64: kvm: Delete duplicated label: in invalid_vector

Hi Nick,

On Mon, 13 Apr 2020 16:37:10 -0700
Nick Desaulniers <[email protected]> wrote:

> On Mon, Apr 13, 2020 at 4:10 PM Fangrui Song <[email protected]> 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/[email protected]/T/#u),
> I can now assemble arch/arm64/kvm/.

Progress! ;-)

> Reviewed-by: Nick Desaulniers <[email protected]>
> Tested-by: Nick Desaulniers <[email protected]>
>
> > Link: https://github.com/ClangBuiltLinux/linux/issues/988
> > Signed-off-by: Fangrui Song <[email protected]>
> > ---
> > 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...