From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
Subject: Re: [PATCH V3 09/30] arm/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT
Date: Mon, 28 Feb 2022 10:57:18 +0000
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References: <1646045273-9343-1-git-send-email-anshuman.khandual@arm.com>
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To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, geert@linux-m68k.org, Christoph Hellwig <hch@infradead.org>, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org, linux-mips@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-s390@vger.kernel.org, linux-riscv@lists.infradead.org, linux-alpha@vger.kernel.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-parisc@vger.kernel.org, openrisc@lists.librecores.org, linux-um@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>

On Mon, Feb 28, 2022 at 04:17:32PM +0530, Anshuman Khandual wrote:
> This defines and exports a platform specific custom vm_get_page_prot() via
> subscribing ARCH_HAS_VM_GET_PAGE_PROT. Subsequently all __SXXX and __PXXX
> macros can be dropped which are no longer needed.

What I would really like to know is why having to run _code_ to work out
what the page protections need to be is better than looking it up in a
table.

Not only is this more expensive in terms of CPU cycles, it also brings
additional code size with it.

I'm struggling to see what the benefit is.

-- 
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