linux-kernel - Re: [RFC v6 07/62] powerpc: use helper functions in __hash_page

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Message-Id: <87vamnps2v.fsf@skywalker.in.ibm.com>
Date:   Thu, 20 Jul 2017 11:28:48 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     Ram Pai <linuxram@...ibm.com>, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, x86@...nel.org, linux-doc@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        khandual@...ux.vnet.ibm.com, bsingharora@...il.com,
        dave.hansen@...el.com, hbabu@...ibm.com, linuxram@...ibm.com,
        arnd@...db.de, akpm@...ux-foundation.org, corbet@....net,
        mingo@...hat.com, mhocko@...nel.org
Subject: Re: [RFC v6 07/62] powerpc: use helper functions in __hash_page_huge() for 64K PTE

Ram Pai <linuxram@...ibm.com> writes:

> replace redundant code in __hash_page_huge() with helper
> functions pte_get_hash_gslot() and pte_set_hash_slot()
>

Can you fold all the helper function usage into one patch ?


> Signed-off-by: Ram Pai <linuxram@...ibm.com>
> ---
>  arch/powerpc/mm/hugetlbpage-hash64.c |   24 ++++--------------------
>  1 files changed, 4 insertions(+), 20 deletions(-)
>
> diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
> index 6f7aee3..e6dcd50 100644
> --- a/arch/powerpc/mm/hugetlbpage-hash64.c
> +++ b/arch/powerpc/mm/hugetlbpage-hash64.c
> @@ -23,7 +23,6 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
>  		     int ssize, unsigned int shift, unsigned int mmu_psize)
>  {
>  	real_pte_t rpte;
> -	unsigned long *hidxp;
>  	unsigned long vpn;
>  	unsigned long old_pte, new_pte;
>  	unsigned long rflags, pa, sz;
> @@ -74,16 +73,10 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
>  	/* Check if pte already has an hpte (case 2) */
>  	if (unlikely(old_pte & H_PAGE_HASHPTE)) {
>  		/* There MIGHT be an HPTE for this pte */
> -		unsigned long hash, slot, hidx;
> +		unsigned long gslot;
>
> -		hash = hpt_hash(vpn, shift, ssize);
> -		hidx = __rpte_to_hidx(rpte, 0);
> -		if (hidx & _PTEIDX_SECONDARY)
> -			hash = ~hash;
> -		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
> -		slot += hidx & _PTEIDX_GROUP_IX;
> -
> -		if (mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, mmu_psize,
> +		gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
> +		if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, mmu_psize,
>  					       mmu_psize, ssize, flags) == -1)
>  			old_pte &= ~_PAGE_HPTEFLAGS;
>  	}
> @@ -110,16 +103,7 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
>  			return -1;
>  		}
>
> -		/*
> -		 * Insert slot number & secondary bit in PTE second half.
> -		 */
> -		hidxp = (unsigned long *)(ptep + PTRS_PER_PTE);
> -		rpte.hidx &= ~(0xfUL);
> -		*hidxp = rpte.hidx  | (slot & 0xfUL);
> -		/*
> -		 * check __real_pte for details on matching smp_rmb()
> -		 */
> -		smp_wmb();
> +		new_pte |= pte_set_hash_slot(ptep, rpte, 0, slot);
>  	}
>
>  	/*
> -- 
> 1.7.1