From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anshuman Khandual <anshuman.khandual@arm.com>
Subject: Re: [PATCH V2] mm/special: Create generic fallbacks for pte_special()
 and pte_mkspecial()
Date: Tue, 10 Mar 2020 19:16:42 +0530
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References: <1583802551-15406-1-git-send-email-anshuman.khandual@arm.com>
 <20200310132747.GA12601@alpha.franken.de>
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To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mm@kvack.org, Richard Henderson <rth@twiddle.net>, Ivan Kokshaysky <ink@jurassic.park.msu.ru>, Matt Turner <mattst88@gmail.com>, Russell King <linux@armlinux.org.uk>, Guo Ren <guoren@kernel.org>, Brian Cain <bcain@codeaurora.org>, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Sam Creasey <sammy@sammy.net>, Michal Simek <monstr@monstr.eu>, Ralf Baechle <ralf@linux-mips.org>, Paul Burton <paulburton@kernel.org>, Nick Hu <nickhu@andestech.com>, Greentime Hu <green.hu@gmail.com>, Vincent Chen <deanbo422@gmail.com>, Ley Foon Tan <ley.foon.tan@intel.com>, Jonas Bonn <jonas@southpole.se>, Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>, Stafford Horne <shorne@gmail.com>



On 03/10/2020 06:57 PM, Thomas Bogendoerfer wrote:
> On Tue, Mar 10, 2020 at 06:39:11AM +0530, Anshuman Khandual wrote:
>> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
>> index aef5378f909c..8e4e4be1ca00 100644
>> --- a/arch/mips/include/asm/pgtable.h
>> +++ b/arch/mips/include/asm/pgtable.h
>> @@ -269,6 +269,36 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
>>   */
>>  extern pgd_t swapper_pg_dir[];
>>  
>> +/*
>> + * Platform specific pte_special() and pte_mkspecial() definitions
>> + * are required only when ARCH_HAS_PTE_SPECIAL is enabled.
>> + */
>> +#if !defined(CONFIG_32BIT) && !defined(CONFIG_CPU_HAS_RIXI)
> 
> this looks wrong.
> 
> current Kconfig statement is
> 
> select ARCH_HAS_PTE_SPECIAL if !(32BIT && CPU_HAS_RIXI)
> 
> so we can't use PTE_SPECIAL on 32bit _and_ CPUs with RIXI support.

I already had asked for clarification on this.

> 
> Why can't we use
> 
> #if defined(CONFIG_ARCH_HAS_PTE_SPECIAL)
> 
> here as the comment already suggests ?

Yes, that will be easier and will automatically adjust in case
ARCH_HAS_PTE_SPECIAL scope changes later. Will respin the patch.

> 
> Thomas.
>