Re: [PATCH 02/14] arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1

[Robin Murphy]

On 24/05/18 11:52, Mark Rutland wrote:
> On Wed, May 23, 2018 at 10:23:20AM +0100, Julien Grall wrote:
> > Hi Marc,
> >
> > On 05/22/2018 04:06 PM, Marc Zyngier wrote:
> > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> > > index ec2ee720e33e..f33e6aed3037 100644
> > > --- a/arch/arm64/kernel/entry.S
> > > +++ b/arch/arm64/kernel/entry.S
> > > @@ -18,6 +18,7 @@
> > >     * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> > >     */
> > > +#include <linux/arm-smccc.h>
> > >    #include <linux/init.h>
> > >    #include <linux/linkage.h>
> > > @@ -137,6 +138,18 @@ alternative_else_nop_endif
> > >    	add	\dst, \dst, #(\sym - .entry.tramp.text)
> > >    	.endm
> > > +	// This macro corrupts x0-x3. It is the caller's duty
> > > +	// to save/restore them if required.
> >
> > NIT: Shouldn't you use /* ... */ for multi-line comments?
>
> There's no requirement to do so, and IIRC even Torvalds prefers '//'
> comments for multi-line things these days.

Also, this is an assembly code, not C; '//' is the actual A64 assembler 
comment syntax so is arguably more appropriate here in spite of being 
moot thanks to preprocessing.

Robin.