Re: [RFC 03/23] ARM: LPAE: use phys_addr_t on virt <--> phys conversion

[Cyril Chemparathy]

On 7/24/2012 6:37 AM, Catalin Marinas wrote:
> On Tue, Jul 24, 2012 at 02:09:05AM +0100, Cyril Chemparathy wrote:
> > This patch fixes up the types used when converting back and forth between
> > physical and virtual addresses.
> >
> > Signed-off-by: Vitaly Andrianov <vitalya@xxxxxx>
> > Signed-off-by: Cyril Chemparathy <cyril@xxxxxx>
> > ---
> >   arch/arm/include/asm/memory.h |   17 +++++++++++------
> >   1 file changed, 11 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> > index fcb5757..7629dfe 100644
> > --- a/arch/arm/include/asm/memory.h
> > +++ b/arch/arm/include/asm/memory.h
> > @@ -169,22 +169,27 @@ extern unsigned long __pv_phys_offset;
> >   	: "=r" (to)					\
> >   	: "r" (from), "I" (type))
> >
> > -static inline unsigned long __virt_to_phys(unsigned long x)
> > +static inline phys_addr_t __virt_to_phys(unsigned long x)
> >   {
> >   	unsigned long t;
> >   	__pv_stub(x, t, "add", __PV_BITS_31_24);
> >   	return t;
> >   }
> >
> > -static inline unsigned long __phys_to_virt(unsigned long x)
> > +static inline unsigned long __phys_to_virt(phys_addr_t x)
> >   {
> >   	unsigned long t;
> >   	__pv_stub(x, t, "sub", __PV_BITS_31_24);
> >   	return t;
> >   }
>
> BTW, I would prefer if the phys-to-virt patching was fixed as well. It
> shouldn't be difficult.

On that topic - yes, we have this on our radar, but in our case we;re 
talking about patching (in head.S) and then repatching (at switch over).

One of the ideas we've been bouncing around has been to convert the 
phys-virt patch code into arithmetic on PFNs.  This way we don't have to 
get too messy with 64-bit in the patch code, and we can use the same 
patch code for both phys_to_virt and virt_to_phys.  Thoughts on this 
approach?

--
Thanks
- Cyril
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