linux-kernel - Re: [PATCH 3/5] arm64/ptdump: Test PMD_TYPE

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Message-ID: <db908eb5-fa01-400a-a6c1-36a5ebddb47c@arm.com>
Date: Wed, 9 Oct 2024 14:29:46 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Anshuman Khandual <anshuman.khandual@....com>,
 linux-arm-kernel@...ts.infradead.org
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>,
 James Morse <james.morse@....com>, Catalin Marinas
 <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Ard Biesheuvel <ardb@...nel.org>, Mark Rutland <mark.rutland@....com>,
 kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] arm64/ptdump: Test PMD_TYPE_MASK for block mapping

On 05/10/2024 13:38, Anshuman Khandual wrote:
> arm64 block mapping requires given page table entry's bits[1:0] to be "01".
> But now only bit[1] is checked to be clear, while also implicitly assuming
> bit[0] to be set. This modifies ptdump to check both the relevant bits via
> the mask PMD_TYPE_MASK and check the resultant value against PMD_TYPE_MASK.
> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Ard Biesheuvel <ardb@...nel.org>
> Cc: Ryan Roberts <ryan.roberts@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>

Reviewed-by: Ryan Roberts <ryan.roberts@....com>

> ---
>  arch/arm64/mm/ptdump.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
> index 264c5f9b97d8..8cec0da4cff2 100644
> --- a/arch/arm64/mm/ptdump.c
> +++ b/arch/arm64/mm/ptdump.c
> @@ -80,10 +80,10 @@ static const struct ptdump_prot_bits pte_bits[] = {
>  		.set	= "CON",
>  		.clear	= "   ",
>  	}, {
> -		.mask	= PTE_TABLE_BIT,
> -		.val	= PTE_TABLE_BIT,
> -		.set	= "   ",
> -		.clear	= "BLK",
> +		.mask	= PMD_TYPE_MASK,
> +		.val	= PMD_TYPE_SECT,
> +		.set	= "BLK",
> +		.clear	= "   ",
>  	}, {
>  		.mask	= PTE_UXN,
>  		.val	= PTE_UXN,