Subject: Re: [RFC v6 04/62] powerpc: introduce pte_get_hash_gslot() helper

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Thu, 20 Jul 2017 11:27:24 +0530

Ram Pai <[email-masked]> writes:

> Introduce pte_get_hash_gslot()() which returns the slot number of the
> HPTE in the global hash table.
>
> This function will come in handy as we work towards re-arranging the
> PTE bits in the later patches.
>

Reviewed-by: Aneesh Kumar K.V <[email-masked]>

> Signed-off-by: Ram Pai <[email-masked]>
> ---
>  arch/powerpc/include/asm/book3s/64/hash.h |    3 +++
>  arch/powerpc/mm/hash_utils_64.c           |   18 ++++++++++++++++++
>  2 files changed, 21 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
> index d27f885..277158c 100644
> --- a/arch/powerpc/include/asm/book3s/64/hash.h
> +++ b/arch/powerpc/include/asm/book3s/64/hash.h
> @@ -156,6 +156,9 @@ static inline int hash__pte_none(pte_t pte)
>  	return (pte_val(pte) & ~H_PTE_NONE_MASK) == 0;
>  }
>
> +unsigned long pte_get_hash_gslot(unsigned long vpn, unsigned long shift,
> +		int ssize, real_pte_t rpte, unsigned int subpg_index);
> +
>  /* This low level function performs the actual PTE insertion
>   * Setting the PTE depends on the MMU type and other factors. It's
>   * an horrible mess that I'm not going to try to clean up now but
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index 1b494d0..d3604da 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -1591,6 +1591,24 @@ static inline void tm_flush_hash_page(int local)
>  }
>  #endif
>
> +/*
> + * return the global hash slot, corresponding to the given
> + * pte, which contains the hpte.
> + */
> +unsigned long pte_get_hash_gslot(unsigned long vpn, unsigned long shift,
> +		int ssize, real_pte_t rpte, unsigned int subpg_index)
> +{
> +	unsigned long hash, slot, hidx;
> +
> +	hash = hpt_hash(vpn, shift, ssize);
> +	hidx = __rpte_to_hidx(rpte, subpg_index);
> +	if (hidx & _PTEIDX_SECONDARY)
> +		hash = ~hash;
> +	slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
> +	slot += hidx & _PTEIDX_GROUP_IX;
> +	return slot;
> +}
> +
>  /* WARNING: This is called from hash_low_64.S, if you change this prototype,
>   *          do not forget to update the assembly call site !
>   */
> -- 
> 1.7.1