Re: [v2 PATCH 2/2] powerpc/8xx: use _PAGE_RO instead of _PAGE_RW

[leroy christophe]

Le 18/12/2014 03:22, Scott Wood a Ãcrit :
> On Wed, 2014-12-17 at 10:14 +0100, Christophe Leroy wrote:
> > On powerpc 8xx, in TLB entries, 0x400 bit is set to 1 for read-only pages
> > and is set to 0 for RW pages. So we should use _PAGE_RO instead of _PAGE_RW
> >
> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> >
> > ---
> > v2 is a complete rework compared to v1
> >
> >   arch/powerpc/include/asm/pte-8xx.h | 7 +++----
> >   arch/powerpc/kernel/head_8xx.S     | 3 ---
> >   2 files changed, 3 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h
> > index daa4616..4f5583e 100644
> > --- a/arch/powerpc/include/asm/pte-8xx.h
> > +++ b/arch/powerpc/include/asm/pte-8xx.h
> > @@ -46,7 +46,7 @@
> >    * require a TLB exception handler change.  It is assumed unused bits
> >    * are always zero.
> >    */
> > -#define _PAGE_RW	0x0400	/* lsb PP bits, inverted in HW */
> > +#define _PAGE_RO	0x0400	/* lsb PP bits */
> It looks like pte_update() needs to be updated to match.
>
> >   #define _PAGE_USER	0x0800	/* msb PP bits */
> >   /* set when neither _PAGE_USER nor _PAGE_RW are set */
> Also update this comment.
>
> >   #define _PAGE_KNLRO	0x0200
> > @@ -62,9 +62,8 @@
> >   #define PTE_ATOMIC_UPDATES	1
> >   
> >   /* We need to add _PAGE_SHARED to kernel pages */
> > -#define _PAGE_KERNEL_RO	(_PAGE_SHARED | _PAGE_KNLRO)
> > -#define _PAGE_KERNEL_ROX	(_PAGE_EXEC | _PAGE_KNLRO)
> > -#define _PAGE_KERNEL_RW	(_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE)
> > +#define _PAGE_KERNEL_RO	(_PAGE_SHARED | _PAGE_RO | _PAGE_KNLRO)
> > +#define _PAGE_KERNEL_ROX	(_PAGE_EXEC | _PAGE_RO | _PAGE_KNLRO)
> >   
> >   #endif /* __KERNEL__ */
> >   #endif /*  _ASM_POWERPC_PTE_8xx_H */
> Where did _PAGE_KERNEL_RW go?
It is already defined like this in pte-common.h:

#ifndef _PAGE_KERNEL_RW
#define _PAGE_KERNEL_RW        (_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE)
#endif


Christophe
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