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Message-ID: <073cb6a6-3dbc-75d4-dbfe-a5299a6b0510@arm.com>
Date:   Tue, 19 Apr 2022 15:52:49 +0530
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Subject: Re: [PATCH -next v4 3/4] arm64: mm: add support for page table check
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To:     Tong Tiangen <tongtiangen@huawei.com>,
        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>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-arm-kernel@lists.infradead.org,
        linux-riscv@lists.infradead.org,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Guohanjun <guohanjun@huawei.com>
References: <20220418034444.520928-1-tongtiangen@huawei.com>
 <20220418034444.520928-4-tongtiangen@huawei.com>
From:   Anshuman Khandual <anshuman.khandual@arm.com>
In-Reply-To: <20220418034444.520928-4-tongtiangen@huawei.com>
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On 4/18/22 09:14, Tong Tiangen wrote:
> +#ifdef CONFIG_PAGE_TABLE_CHECK
> +static inline bool pte_user_accessible_page(pte_t pte)
> +{
> +	return pte_present(pte) && (pte_user(pte) || pte_user_exec(pte));
> +}
> +
> +static inline bool pmd_user_accessible_page(pmd_t pmd)
> +{
> +	return pmd_present(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd));
> +}
> +
> +static inline bool pud_user_accessible_page(pud_t pud)
> +{
> +	return pud_present(pud) && pud_user(pud);
> +}
> +#endif
Wondering why check for these page table entry states when init_mm
has already being excluded ? Should not user page tables be checked
for in entirety for all updates ? what is the rationale for filtering
out only pxx_user_access_page entries ?