Re: [Xen-devel] [PATCH for-4.13] xen/arm32: head: Fix build when using GAS 2.25.0

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 30 Sep 2019, Andrew Cooper wrote:
> On 30/09/2019 19:44, Julien Grall wrote:
> > GAS 2.25.0 throws multiple errors when building arm32/head.S:
> >
> > arm32/head.S: Assembler messages:
> > arm32/head.S:452: Error: invalid constant (f7f) after fixup
> > arm32/head.S:453: Error: invalid constant (f7f) after fixup
> > arm32/head.S:495: Error: invalid constant (f7f) after fixup
> > arm32/head.S:510: Error: invalid constant (f7f) after fixup
> > arm32/head.S:514: Error: invalid constant (f7f) after fixup
> > arm32/head.S:516: Error: invalid constant (f7f) after fixup
> > arm32/head.S:633: Error: invalid constant (f7f) after fixup
> >
> > This makes sense because the instruction mov is only able to deal with a
> > specific set of immediate (see "modified immediate constants in ARM
> > instructions"). For any 16-bit immediate, the instruction movw should be
> > used.
> >
> > It looks like newer version of GAS will seemly switch to movw if the
> > immediate does not fit in the immediate encoding for mov. But we should
> > not rely on this. So switch to movw.
> >
> > Fixes: 23dfe48d10 ("xen/arm32: head: Introduce macros to create table and 
> > mapping entry")
> > Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> 
> FWIW, Tested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, only insofar
> as it fixing the build.  I haven't booted the resulting binary.

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

Given that this is a straightforward build fix, and due to timezone
differences, I have committed it (after verifying it fixes the build
myself). I hope that Juergen approves.

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