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

[Vlastimil Babka]

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 at twiddle.net>
> Cc: Vineet Gupta <vgupta at synopsys.com>
> Cc: Russell King <linux at armlinux.org.uk>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Mark Salter <msalter at redhat.com>
> Cc: Guo Ren <guoren at kernel.org>
> Cc: Yoshinori Sato <ysato at users.sourceforge.jp>
> Cc: Brian Cain <bcain at codeaurora.org>
> Cc: Tony Luck <tony.luck at intel.com>
> Cc: Geert Uytterhoeven <geert at linux-m68k.org>
> Cc: Michal Simek <monstr at monstr.eu>
> Cc: Ralf Baechle <ralf at linux-mips.org>
> Cc: Paul Burton <paulburton at kernel.org>
> Cc: Nick Hu <nickhu at andestech.com>
> Cc: Ley Foon Tan <ley.foon.tan at intel.com>
> Cc: Jonas Bonn <jonas at southpole.se>
> Cc: "James E.J. Bottomley" <James.Bottomley at HansenPartnership.com>
> Cc: Michael Ellerman <mpe at ellerman.id.au>
> Cc: Paul Walmsley <paul.walmsley at sifive.com>
> Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
> Cc: Rich Felker <dalias at libc.org>
> Cc: "David S. Miller" <davem at davemloft.net>
> Cc: Guan Xuetao <gxt at pku.edu.cn>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: Jeff Dike <jdike at addtoit.com>
> Cc: Chris Zankel <chris at zankel.net>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: linux-alpha at vger.kernel.org
> Cc: linux-kernel at vger.kernel.org
> Cc: linux-snps-arc at lists.infradead.org
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: linux-c6x-dev at linux-c6x.org
> Cc: uclinux-h8-devel at lists.sourceforge.jp
> Cc: linux-hexagon at vger.kernel.org
> Cc: linux-ia64 at vger.kernel.org
> Cc: linux-m68k at lists.linux-m68k.org
> Cc: linux-mips at vger.kernel.org
> Cc: nios2-dev at lists.rocketboards.org
> Cc: openrisc at lists.librecores.org
> Cc: linux-parisc at vger.kernel.org
> Cc: linuxppc-dev at lists.ozlabs.org
> Cc: linux-riscv at lists.infradead.org
> Cc: linux-s390 at vger.kernel.org
> Cc: linux-sh at vger.kernel.org
> Cc: sparclinux at vger.kernel.org
> Cc: linux-um at lists.infradead.org
> Cc: linux-xtensa at linux-xtensa.org
> Cc: linux-mm at kvack.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com
Reviewed-by: Vlastimil Babka <vbabka at suse.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.

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