linux-kernel - Re: [PATCH -next v5 2/5] mm: page_table_check: move pxx_user_accessible

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Date:   Fri, 22 Apr 2022 14:30:03 +0800
From:   Tong Tiangen <tongtiangen@...wei.com>
To:     Anshuman Khandual <anshuman.khandual@....com>,
        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>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-riscv@...ts.infradead.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH -next v5 2/5] mm: page_table_check: move
 pxx_user_accessible_page into x86



在 2022/4/22 13:11, Anshuman Khandual 写道:
> Similar to previous commits on the same file, the following subject
> line format, would have been preferred.
> 
> mm/page_table_check: <description>
> 
> On 4/21/22 13:50, Tong Tiangen wrote:
>> From: Kefeng Wang <wangkefeng.wang@...wei.com>
>>
>> The pxx_user_accessible_page() check the PTE bit, it's
> 
> s/check/checks			 ^^^^
> 
>> architecture-specific code, move them into x86's pgtable.h
> The commit message should have been more clear, atleast complete in
> sentences. I dont want to be bike shedding here but this is definitely
> incomplete. These helpers are being moved out to make the page table
> check framework, platform independent. Hence the commit message should
> mention this.

The commit message is not very clear and it is too simple.

Thanks.

> 
>>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
>> Signed-off-by: Tong Tiangen <tongtiangen@...wei.com>
>> Acked-by: Pasha Tatashin <pasha.tatashin@...een.com>
>> ---
>>   arch/x86/include/asm/pgtable.h | 19 +++++++++++++++++++
>>   mm/page_table_check.c          | 17 -----------------
>>   2 files changed, 19 insertions(+), 17 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
>> index b7464f13e416..564abe42b0f7 100644
>> --- a/arch/x86/include/asm/pgtable.h
>> +++ b/arch/x86/include/asm/pgtable.h
>> @@ -1447,6 +1447,25 @@ static inline bool arch_has_hw_pte_young(void)
>>   	return true;
>>   }
>>   
>> +#ifdef CONFIG_PAGE_TABLE_CHECK
>> +static inline bool pte_user_accessible_page(pte_t pte)
>> +{
>> +	return (pte_val(pte) & _PAGE_PRESENT) && (pte_val(pte) & _PAGE_USER);
>> +}
>> +
>> +static inline bool pmd_user_accessible_page(pmd_t pmd)
>> +{
>> +	return pmd_leaf(pmd) && (pmd_val(pmd) & _PAGE_PRESENT) &&
>> +		(pmd_val(pmd) & _PAGE_USER);
>> +}
>> +
>> +static inline bool pud_user_accessible_page(pud_t pud)
>> +{
>> +	return pud_leaf(pud) && (pud_val(pud) & _PAGE_PRESENT) &&
>> +		(pud_val(pud) & _PAGE_USER);
> 
> A line break is not really required here (and above as well). As single
> complete line would still be within 100 characters.
> 
Right, now one line can have 100 characters.

Thanks.

>> +}
>> +#endif
>> +
>>   #endif	/* __ASSEMBLY__ */
>>   
>>   #endif /* _ASM_X86_PGTABLE_H */
>> diff --git a/mm/page_table_check.c b/mm/page_table_check.c
>> index eb0d0b71cdf6..3692bea2ea2c 100644
>> --- a/mm/page_table_check.c
>> +++ b/mm/page_table_check.c
>> @@ -52,23 +52,6 @@ static struct page_table_check *get_page_table_check(struct page_ext *page_ext)
>>   	return (void *)(page_ext) + page_table_check_ops.offset;
>>   }
>>   
>> -static inline bool pte_user_accessible_page(pte_t pte)
>> -{
>> -	return (pte_val(pte) & _PAGE_PRESENT) && (pte_val(pte) & _PAGE_USER);
>> -}
>> -
>> -static inline bool pmd_user_accessible_page(pmd_t pmd)
>> -{
>> -	return pmd_leaf(pmd) && (pmd_val(pmd) & _PAGE_PRESENT) &&
>> -		(pmd_val(pmd) & _PAGE_USER);
>> -}
>> -
>> -static inline bool pud_user_accessible_page(pud_t pud)
>> -{
>> -	return pud_leaf(pud) && (pud_val(pud) & _PAGE_PRESENT) &&
>> -		(pud_val(pud) & _PAGE_USER);
>> -}
>> -
>>   /*
>>    * An enty is removed from the page table, decrement the counters for that page
>>    * verify that it is of correct type and counters do not become negative.
> 
> With above mentioned code cleanup and commit message changes in place.
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
> .