Re: [PATCH v12 3/5] arm64: pgtable: Add p*d_page_vaddr helper macros

[Chintan Pandya]

On 6/4/2018 5:43 PM, Will Deacon wrote:
> On Fri, Jun 01, 2018 at 06:09:16PM +0530, Chintan Pandya wrote:
> > Add helper macros to give virtual references to page
> > tables. These will be used while freeing dangling
> > page tables.
> >
> > Signed-off-by: Chintan Pandya <cpandya@xxxxxxxxxxxxxx>
> > ---
> >   arch/arm64/include/asm/pgtable.h | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> > index 7c4c8f3..ef4047f 100644
> > --- a/arch/arm64/include/asm/pgtable.h
> > +++ b/arch/arm64/include/asm/pgtable.h
> > @@ -580,6 +580,9 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd)
> >   
> >   #endif  /* CONFIG_PGTABLE_LEVELS > 3 */
> >   
> > +#define pmd_page_vaddr(pmd) __va(pmd_page_paddr(pmd))
> > +#define pud_page_vaddr(pud) __va(pud_page_paddr(pud))
>
> Are these actually needed, or do pte_offset_kernel and pmd_offset do the
> job already?

I introduced these macros for consistency across different arch.

Looking at pte_offset_kernel, it seems to use READ_ONCE() which looks
little costly for its intended use (in next patch) where we already have
dereferenced value. Do you still suggest to remove this ?

> Will

Chintan
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