linux-kernel - Re: [PATCH v11 07/22] riscv: mm: Add p?d

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Message-ID: <69a56736-4093-202a-4eaf-feeaaa0216d1@ghiti.fr>
Date:   Tue, 8 Oct 2019 07:31:42 -0400
From:   Alex Ghiti <alex@...ti.fr>
To:     Steven Price <steven.price@....com>, linux-mm@...ck.org
Cc:     Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        James Morse <james.morse@....com>,
        Jérôme Glisse <jglisse@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mark Rutland <Mark.Rutland@....com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Palmer Dabbelt <palmer@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v11 07/22] riscv: mm: Add p?d_leaf() definitions

On 10/7/19 11:38 AM, Steven Price wrote:
> walk_page_range() is going to be allowed to walk page tables other than
> those of user space. For this it needs to know when it has reached a
> 'leaf' entry in the page tables. This information is provided by the
> p?d_leaf() functions/macros.
>
> For riscv a page is a leaf page when it has a read, write or execute bit
> set on it.
>
> CC: Palmer Dabbelt <palmer@...ive.com>
> CC: Albert Ou <aou@...s.berkeley.edu>
> CC: linux-riscv@...ts.infradead.org
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>   arch/riscv/include/asm/pgtable-64.h | 7 +++++++
>   arch/riscv/include/asm/pgtable.h    | 7 +++++++
>   2 files changed, 14 insertions(+)
>
> diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
> index 74630989006d..e88a8e8acbdf 100644
> --- a/arch/riscv/include/asm/pgtable-64.h
> +++ b/arch/riscv/include/asm/pgtable-64.h
> @@ -43,6 +43,13 @@ static inline int pud_bad(pud_t pud)
>   	return !pud_present(pud);
>   }
>   
> +#define pud_leaf	pud_leaf
> +static inline int pud_leaf(pud_t pud)
> +{
> +	return pud_present(pud)
> +		&& (pud_val(pud) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
> +}
> +
>   static inline void set_pud(pud_t *pudp, pud_t pud)
>   {
>   	*pudp = pud;
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 7255f2d8395b..b9a679153265 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -130,6 +130,13 @@ static inline int pmd_bad(pmd_t pmd)
>   	return !pmd_present(pmd);
>   }
>   
> +#define pmd_leaf	pmd_leaf
> +static inline int pmd_leaf(pmd_t pmd)
> +{
> +	return pmd_present(pmd)
> +		&& (pmd_val(pmd) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC));
> +}
> +
>   static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
>   {
>   	*pmdp = pmd;

Hi Steven,

The way you check leaf entries is correct: we do the same for hugepages. 
So is
there a reason you did not use the pmd/pud_huge functions that are 
defined in
arch/riscv/mm/hugetlbpage.c ?

Anyway, FWIW:

Reviewed-by: Alexandre Ghiti <alex@...ti.fr>

Thanks,

Alex