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

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Date:   Tue, 22 Mar 2022 11:07:22 +0800
From:   Tong Tiangen <tongtiangen@...wei.com>
To:     Catalin Marinas <catalin.marinas@....com>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Pasha Tatashin <pasha.tatashin@...een.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Will Deacon" <will@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "Palmer Dabbelt" <palmer@...belt.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH -next 3/4] arm64: mm: add support for page table check



在 2022/3/22 0:40, Catalin Marinas 写道:
> 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.

Yeah, PTC only check pmd block mapping(huge page) and pud is similar.
These code logic will be included in V2.

Thanks.

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