Re: [Xen-devel] [PATCH 2/2] x86: fix indirect thunk usage of CONFIG_INDIRECT_THUNK

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Jan 24, 2018 at 09:23:37AM -0700, Jan Beulich wrote:
> >>> On 24.01.18 at 16:48, <roger.pau@xxxxxxxxxx> wrote:
> > When indirect_thunk_asm.h is instantiated directly into assembly files
> > CONFIG_INDIRECT_THUNK might not be defined, and thus using .if against
> > it is wrong.
> > 
> > Add a check to define CONFIG_INDIRECT_THUNK to 0 if not defined, so
> > that using .if CONFIG_INDIRECT_THUNK is always correct.
> > 
> > This suppresses the following clang error:
> > 
> > <instantiation>:8:9: error: expected absolute expression
> >     .if CONFIG_INDIRECT_THUNK == 1
> >         ^
> > <instantiation>:1:1: note: while in macro instantiation
> > INDIRECT_BRANCH call %rdx
> > ^
> > entry.S:589:9: note: while in macro instantiation
> >         INDIRECT_CALL %rdx
> >         ^
> 
> Why is the same no problem with gas? It wants constant
> expressions with .if too, after all.

Right, and I cannot figure out why it works when using
-no-integrated-as and not when not using it. The more that I cannot
see CONFIG_INDIRECT_THUNK being unconditionally defined to either 0 or
1. I guess I'm missing something.

Roger.

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