From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B77D3C4338F for ; Thu, 12 Aug 2021 09:14:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 587066103A for ; Thu, 12 Aug 2021 09:14:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235700AbhHLJPP (ORCPT ); Thu, 12 Aug 2021 05:15:15 -0400 Received: from foss.arm.com ([217.140.110.172]:40642 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234895AbhHLJPN (ORCPT ); Thu, 12 Aug 2021 05:15:13 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2DEECD6E; Thu, 12 Aug 2021 02:14:48 -0700 (PDT) Received: from [10.163.68.17] (unknown [10.163.68.17]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8C3EB3F718; Thu, 12 Aug 2021 02:14:44 -0700 (PDT) From: Anshuman Khandual Subject: Re: [RFC V2 01/10] mm/mmap: Dynamically initialize protection_map[] To: Catalin Marinas Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, suzuki.poulose@arm.com, mark.rutland@arm.com, will@kernel.org, maz@kernel.org, james.morse@arm.com, steven.price@arm.com References: <1627281445-12445-1-git-send-email-anshuman.khandual@arm.com> <1627281445-12445-2-git-send-email-anshuman.khandual@arm.com> <20210805170318.GB6719@arm.com> Message-ID: Date: Thu, 12 Aug 2021 14:45:37 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210805170318.GB6719@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/5/21 10:33 PM, Catalin Marinas wrote: > On Mon, Jul 26, 2021 at 12:07:16PM +0530, Anshuman Khandual wrote: >> The protection_map[] elements (__PXXX and __SXXX) might sometimes contain >> runtime variables in certain platforms like arm64 preventing a successful >> build because of the current static initialization. So it just defers the >> initialization until mmmap_init() via a new helper init_protection_map(). >> >> Signed-off-by: Anshuman Khandual >> --- >> mm/mmap.c | 26 ++++++++++++++++++++++---- >> 1 file changed, 22 insertions(+), 4 deletions(-) >> >> diff --git a/mm/mmap.c b/mm/mmap.c >> index ca54d36..a95b078 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -100,10 +100,7 @@ static void unmap_region(struct mm_struct *mm, >> * w: (no) no >> * x: (yes) yes >> */ >> -pgprot_t protection_map[16] __ro_after_init = { >> - __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, >> - __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 >> -}; >> +pgprot_t protection_map[16] __ro_after_init; > > Mips, x86, sparc, arm32, m68k all adjust protection_map[] during boot. > Could we do something similar here and avoid changing the generic code? If __P[000..111] and __S[000..111] be made dummy values (e.g 0 or something standard prot temporarily), hence the compilation problem could be avoided. Later in the platform code, protection_map[] could be adjusted with actual prot values which would involve variable.