On Sat, Sep 9, 2017 at 8:44 AM, Ram Pai <linux...@us.ibm.com> wrote:
> Introduce pte_set_hash_slot().It sets the (H_PAGE_F_SECOND|H_PAGE_F_GIX)
> bits at the appropriate location in the PTE of 4K PTE. For
> 64K PTE, it sets the bits in the second part of the PTE. Though
> the implementation for the former just needs the slot parameter, it does
> take some additional parameters to keep the prototype consistent.
>
> This function will be handy as we work towards re-arranging the
> bits in the later patches.
>
> Reviewed-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> Signed-off-by: Ram Pai <linux...@us.ibm.com>
> ---
> arch/powerpc/include/asm/book3s/64/hash-4k.h | 15 +++++++++++++++
> arch/powerpc/include/asm/book3s/64/hash-64k.h | 25
> +++++++++++++++++++++++++
> 2 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h
> b/arch/powerpc/include/asm/book3s/64/hash-4k.h
> index 0c4e470..8909039 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
> @@ -48,6 +48,21 @@ static inline int hash__hugepd_ok(hugepd_t hpd)
> }
> #endif
>
> +/*
> + * 4k pte format is different from 64k pte format. Saving the
> + * hash_slot is just a matter of returning the pte bits that need to
> + * be modified. On 64k pte, things are a little more involved and
> + * hence needs many more parameters to accomplish the same.
> + * However we want to abstract this out from the caller by keeping
> + * the prototype consistent across the two formats.
> + */
> +static inline unsigned long pte_set_hash_slot(pte_t *ptep, real_pte_t rpte,
> + unsigned int subpg_index, unsigned long slot)
> +{
> + return (slot << H_PAGE_F_GIX_SHIFT) &
> + (H_PAGE_F_SECOND | H_PAGE_F_GIX);
> +}
> +
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>
> static inline char *get_hpte_slot_array(pmd_t *pmdp)
> diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h
> b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> index 9732837..6652669 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
> @@ -74,6 +74,31 @@ static inline unsigned long __rpte_to_hidx(real_pte_t
> rpte, unsigned long index)
> return (pte_val(rpte.pte) >> H_PAGE_F_GIX_SHIFT) & 0xf;
> }
>
> +/*
> + * Commit the hash slot and return pte bits that needs to be modified.
> + * The caller is expected to modify the pte bits accordingly and
> + * commit the pte to memory.
> + */
> +static inline unsigned long pte_set_hash_slot(pte_t *ptep, real_pte_t rpte,
> + unsigned int subpg_index, unsigned long slot)
> +{
> + unsigned long *hidxp = (unsigned long *)(ptep + PTRS_PER_PTE);
> +
> + rpte.hidx &= ~(0xfUL << (subpg_index << 2));
> + *hidxp = rpte.hidx | (slot << (subpg_index << 2));
> + /*
> + * Commit the hidx bits to memory before returning.
> + * Anyone reading pte must ensure hidx bits are
> + * read only after reading the pte by using the
Can you lose the only and make it "read after reading the pte"
read only is easy to confuse as read-only
> + * read-side barrier smp_rmb(). __real_pte() can
> + * help ensure that.
> + */
> + smp_wmb();
> +
> + /* no pte bits to be modified, return 0x0UL */
> + return 0x0UL;
Acked-by: Balbir Singh <bsinghar...@gmail.com>
Balbir Singh.
