linux-kernel - Re: [RFC 1/3] mm/vma: Define a default value for VM_DATA_DEFAULT

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Message-ID: <8b0f4c1b-f693-e139-4f66-ee4e1e88b95c@arm.com>
Date:   Wed, 4 Mar 2020 10:49:13 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org
Cc:     Richard Henderson <rth@...ddle.net>,
        Vineet Gupta <vgupta@...opsys.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Salter <msalter@...hat.com>, Guo Ren <guoren@...nel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Brian Cain <bcain@...eaurora.org>,
        Tony Luck <tony.luck@...el.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Michal Simek <monstr@...str.eu>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paulburton@...nel.org>,
        Nick Hu <nickhu@...estech.com>,
        Ley Foon Tan <ley.foon.tan@...el.com>,
        Jonas Bonn <jonas@...thpole.se>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        Guan Xuetao <gxt@....edu.cn>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jeff Dike <jdike@...toit.com>, Chris Zankel <chris@...kel.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-alpha@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-c6x-dev@...ux-c6x.org,
        uclinux-h8-devel@...ts.sourceforge.jp,
        linux-hexagon@...r.kernel.org, linux-ia64@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, linux-mips@...r.kernel.org,
        nios2-dev@...ts.rocketboards.org, openrisc@...ts.librecores.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-um@...ts.infradead.org, linux-xtensa@...ux-xtensa.org
Subject: Re: [RFC 1/3] mm/vma: Define a default value for
 VM_DATA_DEFAULT_FLAGS



On 03/03/2020 10:55 PM, Vlastimil Babka wrote:
> On 3/2/20 7:47 AM, Anshuman Khandual wrote:
>> There are many platforms with exact same value for VM_DATA_DEFAULT_FLAGS
>> This creates a default value for VM_DATA_DEFAULT_FLAGS in line with the
>> existing VM_STACK_DEFAULT_FLAGS. While here, also define some more macros
>> with standard VMA access flag combinations that are used frequently across
>> many platforms. Apart from simplification, this reduces code duplication
>> as well.
>>
>> Cc: Richard Henderson <rth@...ddle.net>
>> Cc: Vineet Gupta <vgupta@...opsys.com>
>> Cc: Russell King <linux@...linux.org.uk>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Mark Salter <msalter@...hat.com>
>> Cc: Guo Ren <guoren@...nel.org>
>> Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
>> Cc: Brian Cain <bcain@...eaurora.org>
>> Cc: Tony Luck <tony.luck@...el.com>
>> Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
>> Cc: Michal Simek <monstr@...str.eu>
>> Cc: Ralf Baechle <ralf@...ux-mips.org>
>> Cc: Paul Burton <paulburton@...nel.org>
>> Cc: Nick Hu <nickhu@...estech.com>
>> Cc: Ley Foon Tan <ley.foon.tan@...el.com>
>> Cc: Jonas Bonn <jonas@...thpole.se>
>> Cc: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: Paul Walmsley <paul.walmsley@...ive.com>
>> Cc: Heiko Carstens <heiko.carstens@...ibm.com>
>> Cc: Rich Felker <dalias@...c.org>
>> Cc: "David S. Miller" <davem@...emloft.net>
>> Cc: Guan Xuetao <gxt@....edu.cn>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Jeff Dike <jdike@...toit.com>
>> Cc: Chris Zankel <chris@...kel.net>
>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>> Cc: linux-alpha@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> Cc: linux-snps-arc@...ts.infradead.org
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-c6x-dev@...ux-c6x.org
>> Cc: uclinux-h8-devel@...ts.sourceforge.jp
>> Cc: linux-hexagon@...r.kernel.org
>> Cc: linux-ia64@...r.kernel.org
>> Cc: linux-m68k@...ts.linux-m68k.org
>> Cc: linux-mips@...r.kernel.org
>> Cc: nios2-dev@...ts.rocketboards.org
>> Cc: openrisc@...ts.librecores.org
>> Cc: linux-parisc@...r.kernel.org
>> Cc: linuxppc-dev@...ts.ozlabs.org
>> Cc: linux-riscv@...ts.infradead.org
>> Cc: linux-s390@...r.kernel.org
>> Cc: linux-sh@...r.kernel.org
>> Cc: sparclinux@...r.kernel.org
>> Cc: linux-um@...ts.infradead.org
>> Cc: linux-xtensa@...ux-xtensa.org
>> Cc: linux-mm@...ck.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com
> Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
> 
> Nit:
> 
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index b0e53ef13ff1..7a764ae6ab68 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -342,6 +342,21 @@ extern unsigned int kobjsize(const void *objp);
>>  /* Bits set in the VMA until the stack is in its final location */
>>  #define VM_STACK_INCOMPLETE_SETUP	(VM_RAND_READ | VM_SEQ_READ)
>>  
>> +#define TASK_EXEC ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0)
>> +
>> +/* Common data flag combinations */
>> +#define VM_DATA_FLAGS_TSK_EXEC	(VM_READ | VM_WRITE | TASK_EXEC | \
>> +				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
>> +#define VM_DATA_FLAGS_NON_EXEC	(VM_READ | VM_WRITE | VM_MAYREAD | \
>> +				 VM_MAYWRITE | VM_MAYEXEC)
>> +#define VM_DATA_FLAGS_EXEC	(VM_READ | VM_WRITE | VM_EXEC | \
>> +				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
>> +
>> +#ifndef VM_DATA_DEFAULT_FLAGS		/* arch can override this */
>> +#define VM_DATA_DEFAULT_FLAGS	(VM_READ | VM_WRITE | VM_EXEC | \
>> +				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
> 
> Should you use VM_DATA_FLAGS_EXEC here? Yeah one more macro to expand, but it's
> right above this.

Sure, can do that.

> 
>> +#endif
>> +
>>  #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
>>  #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
>>  #endif
>>
> 
> 
>