Re: [RFC 1/3] mm/vma: Define a default value for VM_DATA_DEFAULT_FLAGS

[Anshuman Khandual]

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@xxxxxxxxxxx>
>> Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
>> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
>> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
>> Cc: Mark Salter <msalter@xxxxxxxxxx>
>> Cc: Guo Ren <guoren@xxxxxxxxxx>
>> Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Brian Cain <bcain@xxxxxxxxxxxxxx>
>> Cc: Tony Luck <tony.luck@xxxxxxxxx>
>> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> Cc: Michal Simek <monstr@xxxxxxxxx>
>> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
>> Cc: Paul Burton <paulburton@xxxxxxxxxx>
>> Cc: Nick Hu <nickhu@xxxxxxxxxxxxx>
>> Cc: Ley Foon Tan <ley.foon.tan@xxxxxxxxx>
>> Cc: Jonas Bonn <jonas@xxxxxxxxxxxx>
>> Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
>> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>> Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
>> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
>> Cc: Rich Felker <dalias@xxxxxxxx>
>> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
>> Cc: Guan Xuetao <gxt@xxxxxxxxxx>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Jeff Dike <jdike@xxxxxxxxxxx>
>> Cc: Chris Zankel <chris@xxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: linux-alpha@xxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx
>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
>> Cc: linux-c6x-dev@xxxxxxxxxxxxx
>> Cc: uclinux-h8-devel@xxxxxxxxxxxxxxxxxxxx
>> Cc: linux-hexagon@xxxxxxxxxxxxxxx
>> Cc: linux-ia64@xxxxxxxxxxxxxxx
>> Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx
>> Cc: linux-mips@xxxxxxxxxxxxxxx
>> Cc: nios2-dev@xxxxxxxxxxxxxxxxxxxxxx
>> Cc: openrisc@xxxxxxxxxxxxxxxxxxxx
>> Cc: linux-parisc@xxxxxxxxxxxxxxx
>> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
>> Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
>> Cc: linux-s390@xxxxxxxxxxxxxxx
>> Cc: linux-sh@xxxxxxxxxxxxxxx
>> Cc: sparclinux@xxxxxxxxxxxxxxx
>> Cc: linux-um@xxxxxxxxxxxxxxxxxxx
>> Cc: linux-xtensa@xxxxxxxxxxxxxxxx
>> Cc: linux-mm@xxxxxxxxx
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx
> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> 
> 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
>>
> 
> 
>