Re: [Xen-devel] [PATCH 05/17] xen/arm64: head: Introduce print_reg

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 26/06/2019 01:09, Stefano Stabellini wrote:
> On Mon, 10 Jun 2019, Julien Grall wrote:
> > At the moment, the user should save x30/lr if it cares about it.
> >
> > Follow-up patches will introduce more use of putn in place where lr
> > should be preserved.
> >
> > Furthermore, any user of putn should also move the value to register x0
> > if it was stored in a different register.
> >
> > For convenience, a new macro is introduced to print a given register.
> > The macro will take care for us to move the value to x0 and also
> > preserve lr.
> >
> > Lastly the new macro is used to replace all the callsite of putn. This
> > will simplify rework/review later on.
> >
> > Note that CurrentEL is now stored in x5 instead of x4 because the latter
> > will be clobbered by the macro print_reg.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> > ---
> >   xen/arch/arm/arm64/head.S | 29 ++++++++++++++++++++++-------
> >   1 file changed, 22 insertions(+), 7 deletions(-)
> >
> > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> > index 84e26582c4..9142b4a774 100644
> > --- a/xen/arch/arm/arm64/head.S
> > +++ b/xen/arch/arm/arm64/head.S
> > @@ -90,8 +90,25 @@
> >           bl    puts    ;     \
> >           mov   lr, x3  ;     \
> >           RODATA_STR(98, _s)
> > +
> > +/*
> > + * Macro to print the value of register \xb
> > + *
> > + * Clobbers x0 - x4
> > + */
> > +.macro print_reg xb
> > +        mov   x4, lr
> > +        mov   x0, \xb
> > +        bl    putn
> > +        mov   lr, x4
> I have the same weird issues with my compiler as before, replacing 'lr'
> with 'x30' solves the problem.
Can you have a try with the following line?

lr      .req    x30             // link register

Cheers,

--
Julien Grall

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