[PATCH 02/13] arm64/kvm: Fix assembler compatibility of macros

[geoff@infradead.org (Geoff Levand)]

On Wed, 2014-09-10 at 10:40 +0200, Ard Biesheuvel wrote:
> On 10 September 2014 00:49, Geoff Levand <geoff@infradead.org> wrote:
> > Some of the macros defined in kvm_arm.h are useful in the exception vector
> > routines, but they are not compatible with the assembler.  Change the
> > definition of ESR_EL2_ISS to be compatible.
> >
> > Fixes build errors like these when using kvm_arm.h in assembly
> > source files:
> >
> >   Error: unexpected characters following instruction at operand 3 -- `add x0,x1,#((1U<<25)-1)'
> >
> > Signed-off-by: Geoff Levand <geoff@infradead.org>
> > ---
> >  arch/arm64/include/asm/kvm_arm.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
> > index cc83520..e0e7e64 100644
> > --- a/arch/arm64/include/asm/kvm_arm.h
> > +++ b/arch/arm64/include/asm/kvm_arm.h
> > @@ -176,7 +176,7 @@
> >  #define ESR_EL2_EC_SHIFT       (26)
> >  #define ESR_EL2_EC             (0x3fU << ESR_EL2_EC_SHIFT)
> >  #define ESR_EL2_IL             (1U << 25)
> > -#define ESR_EL2_ISS            (ESR_EL2_IL - 1)
> > +#define ESR_EL2_ISS            (0xffff)
> 
> Don't you mean 0x1ffffff?

Hcalls have a 16 bit 'payload', the upper bits of the ISS field
are specified as zero by the architecture so 0xffff is the same
as 0x1ffffff.

> And, there is a macro UL() for this purpose, so I suppose you could
> redefine ESR_EL2_IL as (UL(1) << 25) as well. I know it is not
> strictly the same thing, but it should be good enough as this is arm64
> only

Sure that will be OK.  The one other use of ESR_EL2_IL will promote
the operation to unsigned long without ill effect.  I'll prepare an
updated patch.

-Geoff