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Date:   Wed, 26 Feb 2020 13:38:53 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Mark Brown <broonie@kernel.org>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Paul Elliott <paul.elliott@arm.com>,
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        Yu-cheng Yu <yu-cheng.yu@intel.com>,
        Amit Kachhap <amit.kachhap@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Marc Zyngier <maz@kernel.org>,
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Subject: Re: [PATCH v7 11/11] arm64: mm: Display guarded pages in ptdump
Message-ID: <202002261338.9890367C@keescook>
References: <20200226155714.43937-1-broonie@kernel.org>
 <20200226155714.43937-12-broonie@kernel.org>
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On Wed, Feb 26, 2020 at 03:57:14PM +0000, Mark Brown wrote:
> v8.5-BTI introduces the GP field in stage 1 translation tables which
> indicates that blocks and pages with it set are guarded pages for which
> branch target identification checks should be performed. Decode this
> when dumping the page tables to aid debugging.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  arch/arm64/mm/dump.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
> index 860c00ec8bd3..78163b7a7dde 100644
> --- a/arch/arm64/mm/dump.c
> +++ b/arch/arm64/mm/dump.c
> @@ -145,6 +145,11 @@ static const struct prot_bits pte_bits[] = {
>  		.val	= PTE_UXN,
>  		.set	= "UXN",
>  		.clear	= "   ",
> +	}, {
> +		.mask	= PTE_GP,
> +		.val	= PTE_GP,
> +		.set	= "GP",
> +		.clear	= "  ",
>  	}, {
>  		.mask	= PTE_ATTRINDX_MASK,
>  		.val	= PTE_ATTRINDX(MT_DEVICE_nGnRnE),
> -- 
> 2.20.1
> 

-- 
Kees Cook