Re: [PATCH 2/7] xen/arm32: head.S: Introduce a macro to load the physical address of a symbol

[Julien Grall <julien@xxxxxxx>]

On 27/06/2022 07:31, Michal Orzel wrote:
> Hi Julien,
Hi Michal,

> On 24.06.2022 11:11, Julien Grall wrote:
> > From: Julien Grall <jgrall@xxxxxxxxxx>
> >
> > A lot of places in the ARM32 assembly requires to load the physical address
> > of a symbol. Rather than open-coding the translation, introduce a new macro
> > that will load the phyiscal address of a symbol.
> >
> > Lastly, use the new macro to replace all the current open-coded version.
> >
> > Note that most of the comments associated to the code changed have been
> > removed because the code is now self-explanatory.
> >
> > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/arm32/head.S | 23 +++++++++++------------
> >   1 file changed, 11 insertions(+), 12 deletions(-)
> >
> > diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
> > index c837d3054cf9..77f0a619ca51 100644
> > --- a/xen/arch/arm/arm32/head.S
> > +++ b/xen/arch/arm/arm32/head.S
> > @@ -65,6 +65,11 @@
> >           .endif
> >   .endm
> >   
> > +.macro load_paddr rb, sym
> > +        ldr   \rb, =\sym
> > +        add   \rb, \rb, r10
> > +.endm
> > +
> All the macros in this file have a comment so it'd be useful to follow this 
> convention.
This is not really a convention. Most of the macros are non-trivial 
(e.g. they may clobber registers).
The comment I have in mind here would be:

"Load the physical address of \sym in \rb"

I am fairly confident that anyone can understand from the ".macro" 
line... So I don't feel the comment is necessary.
Cheers,

--
Julien Grall