Re: [PATCH v1 17/24] kvm: arm64: Add __hyp_pa_symbol helper macro

[David Brazdil]

On Mon, Nov 09, 2020 at 06:10:05PM +0000, Marc Zyngier wrote:
> On 2020-11-09 16:59, Quentin Perret wrote:
> > Hey David,
> > 
> > On Monday 09 Nov 2020 at 11:32:26 (+0000), David Brazdil wrote:
> > > Add helper macro for computing the PA of a kernel symbol in nVHE hyp
> > > code. This will be useful for computing the PA of a PSCI CPU_ON entry
> > > point.
> > > 
> > > Signed-off-by: David Brazdil <dbrazdil@xxxxxxxxxx>
> > > ---
> > >  arch/arm64/kvm/hyp/nvhe/psci.c | 10 ++++++++++
> > >  1 file changed, 10 insertions(+)
> > > 
> > > diff --git a/arch/arm64/kvm/hyp/nvhe/psci.c
> > > b/arch/arm64/kvm/hyp/nvhe/psci.c
> > > index b0b5df590ba5..7510b9e174e9 100644
> > > --- a/arch/arm64/kvm/hyp/nvhe/psci.c
> > > +++ b/arch/arm64/kvm/hyp/nvhe/psci.c
> > > @@ -20,6 +20,16 @@ s64 hyp_physvirt_offset;
> > > 
> > >  #define __hyp_pa(x) ((phys_addr_t)((x)) + hyp_physvirt_offset)
> > > 
> > > +#define __hyp_pa_symbol(sym)					\
> > > +	({							\
> > > +		extern char sym[];				\
> > > +		unsigned long kern_va;				\
> > > +								\
> > > +		asm volatile("ldr %0, =%1" : "=r" (kern_va)	\
> > > +					   : "S" (sym));	\
> > > +		kern_va - kimage_voffset;			\
> > > +	})
> > > +
> > 
> > Could this be simplified to __hyp_pa(hyp_symbol_addr(sym))? That would
> > avoid the dependency on kimage_voffset.

Ah, didn't see that one. Ok, removing this patch.

> 
> I'm going to move away from evaluating kimage_voffset at runtime anyway,
> see [1].

Awesome! One more dependency gone.

> 
> Thanks,
> 
>         M.
> 
> [1] https://lore.kernel.org/r/20201109175923.445945-1-maz@xxxxxxxxxx
> -- 
> Jazz is not dead. It just smells funny...