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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 53447C43331 for ; Fri, 6 Sep 2019 15:18:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 301A620650 for ; Fri, 6 Sep 2019 15:18:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390892AbfIFPSM (ORCPT ); Fri, 6 Sep 2019 11:18:12 -0400 Received: from foss.arm.com ([217.140.110.172]:58016 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390430AbfIFPSK (ORCPT ); Fri, 6 Sep 2019 11:18:10 -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 3FAE828; Fri, 6 Sep 2019 08:18:10 -0700 (PDT) Received: from [10.1.196.105] (unknown [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 21E023F59C; Fri, 6 Sep 2019 08:18:08 -0700 (PDT) From: James Morse Subject: Re: [PATCH v3 06/17] arm64, hibernate: add trans_pgd public functions To: Pavel Tatashin Cc: jmorris@namei.org, sashal@kernel.org, ebiederm@xmission.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, corbet@lwn.net, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, marc.zyngier@arm.com, vladimir.murzin@arm.com, matthias.bgg@gmail.com, bhsharma@redhat.com, linux-mm@kvack.org, mark.rutland@arm.com References: <20190821183204.23576-1-pasha.tatashin@soleen.com> <20190821183204.23576-7-pasha.tatashin@soleen.com> Message-ID: Date: Fri, 6 Sep 2019 16:18:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190821183204.23576-7-pasha.tatashin@soleen.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pavel, On 21/08/2019 19:31, Pavel Tatashin wrote: > trans_pgd_create_copy() and trans_pgd_map_page() are going to be > the basis for public interface of new subsystem that handles page Please don't call this a subsystem. 'sound' and 'mm' are subsystems, this is just some shared code. > tables for cases which are between kernels: kexec, and hibernate. Even though you've baked the get_safe_page() calls into trans_pgd_map_page()? > diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c > index 750ecc7f2cbe..2e29d620b56c 100644 > --- a/arch/arm64/kernel/hibernate.c > +++ b/arch/arm64/kernel/hibernate.c > @@ -182,39 +182,15 @@ int arch_hibernation_header_restore(void *addr) > +int trans_pgd_map_page(pgd_t *trans_pgd, void *page, > + unsigned long dst_addr, > + pgprot_t pgprot) If this thing is going to be exposed, its name should reflect that its creating a set of page tables, to map a single page. A function called 'map_page' with this prototype should 'obviously' map @page at @dst_addr in @trans_pgd using the provided @pgprot... but it doesn't. This is what 'create' was doing in the old name, if that wasn't obvious, its because naming things is hard! | trans_create_single_page_mapping()? (might be too verbose) I think this bites you in patch 8, where you 'generalise' this. > { > - void *page = (void *)get_safe_page(GFP_ATOMIC); > - pgd_t *trans_pgd; > pgd_t *pgdp; > pud_t *pudp; > pmd_t *pmdp; > pte_t *ptep; > > - if (!page) > - return -ENOMEM; > - > - memcpy(page, src_start, length); > - __flush_icache_range((unsigned long)page, (unsigned long)page + length); > - > - trans_pgd = (void *)get_safe_page(GFP_ATOMIC); > - if (!trans_pgd) > - return -ENOMEM; > - > pgdp = pgd_offset_raw(trans_pgd, dst_addr); > if (pgd_none(READ_ONCE(*pgdp))) { > pudp = (void *)get_safe_page(GFP_ATOMIC); > @@ -242,6 +218,44 @@ static int create_safe_exec_page(void *src_start, size_t length, > ptep = pte_offset_kernel(pmdp, dst_addr); > set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC)); > > + return 0; > +} > + > +/* > + * Copies length bytes, starting at src_start into an new page, > + * perform cache maintentance, then maps it at the specified address low Could you fix the spelling of maintenance as git thinks you've moved it? > + * address as executable. > + * > + * This is used by hibernate to copy the code it needs to execute when > + * overwriting the kernel text. This function generates a new set of page > + * tables, which it loads into ttbr0. > + * > + * Length is provided as we probably only want 4K of data, even on a 64K > + * page system. > + */ > +static int create_safe_exec_page(void *src_start, size_t length, > + unsigned long dst_addr, > + phys_addr_t *phys_dst_addr) > +{ Thanks, James