Re: [PATCH -next 3/4] arm64: mm: add support for page table check

From: Catalin Marinas <catalin.marinas@arm.com>
To: Tong Tiangen <tongtiangen@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Pasha Tatashin <pasha.tatashin@soleen.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Palmer Dabbelt <palmerdabbelt@google.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH -next 3/4] arm64: mm: add support for page table check
Date: Mon, 21 Mar 2022 16:40:59 +0000	[thread overview]
Message-ID: <Yjiqm6tQB5To5Jd9@arm.com> (raw)
In-Reply-To: <d3006048-f737-439e-b985-cfbab69c4167@huawei.com>

On Mon, Mar 21, 2022 at 02:15:36PM +0800, Tong Tiangen wrote:
> Considering all your suggestions, The final logic should be:
> 
> +#define pte_user(pte)          (!!(pte_val(pte) & PTE_USER))
> 
> +#define pmd_user(pmd)		pte_user(pmd_pte(pmd))
> +#define pmd_user_exec(pmd)	pte_user_exec(pmd_pte(pmd))
> 
> +#define pud_user(pud)          pte_user(pud_pte(pud))
> 
> +static inline bool pte_user_accessible_page(pte_t pte)
> +{
> +	return pte_present(pte) && (pte_user(pte)|| pte_user_exec(pte));
> +}

This is fine.

> +static inline bool pmd_user_accessible_page(pmd_t pmd)
> +{
> +	return pmd_present(pmd) && (pmd_user(pmd)|| pmd_user_exec(pmd));
> +}

That's fine as well assuming that the function is only called on the
set_pmd_at() path where we know that the pmd would be a block mapping
(huge page). I think that's the case from a quick look at the current
x86 implementation.

> +static inline bool pud_user_accessible_page(pud_t pud)
> +{
> +	return pud_present(pud) && pud_user(pud);
> +}

Same here.

-- 
Catalin

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