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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 2C9CBC43603 for ; Fri, 20 Dec 2019 11:48:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2EAA24680 for ; Fri, 20 Dec 2019 11:48:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727283AbfLTLsh (ORCPT ); Fri, 20 Dec 2019 06:48:37 -0500 Received: from foss.arm.com ([217.140.110.172]:49838 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727177AbfLTLsh (ORCPT ); Fri, 20 Dec 2019 06:48:37 -0500 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 8487B30E; Fri, 20 Dec 2019 03:48:36 -0800 (PST) Received: from [10.1.194.52] (e112269-lin.cambridge.arm.com [10.1.194.52]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D3F1C3F719; Fri, 20 Dec 2019 03:48:33 -0800 (PST) Subject: Re: [PATCH v17 01/23] mm: Add generic p?d_leaf() macros To: Michael Ellerman , Andrew Morton , linux-mm@kvack.org Cc: Mark Rutland , x86@kernel.org, Arnd Bergmann , Ard Biesheuvel , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-kernel@vger.kernel.org, =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Ingo Molnar , Borislav Petkov , Andy Lutomirski , "H. Peter Anvin" , James Morse , Thomas Gleixner , Will Deacon , linux-arm-kernel@lists.infradead.org, "Liang, Kan" References: <20191218162402.45610-1-steven.price@arm.com> <20191218162402.45610-2-steven.price@arm.com> <878sn8mtgt.fsf@mpe.ellerman.id.au> From: Steven Price Message-ID: <0951d79f-919a-4a9d-00f7-b40be96af118@arm.com> Date: Fri, 20 Dec 2019 11:48:32 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <878sn8mtgt.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/12/2019 11:43, Michael Ellerman wrote: > Steven Price writes: >> Exposing the pud/pgd levels of the page tables to walk_page_range() means >> we may come across the exotic large mappings that come with large areas >> of contiguous memory (such as the kernel's linear map). >> >> For architectures that don't provide all p?d_leaf() macros, provide >> generic do nothing default that are suitable where there cannot be leaf >> pages at that level. Futher patches will add implementations for >> individual architectures. >> >> The name p?d_leaf() is chosen to minimize the confusion with existing >> uses of "large" pages and "huge" pages which do not necessary mean that >> the entry is a leaf (for example it may be a set of contiguous entries >> that only take 1 TLB slot). For the purpose of walking the page tables >> we don't need to know how it will be represented in the TLB, but we do >> need to know for sure if it is a leaf of the tree. >> >> Signed-off-by: Steven Price >> Acked-by: Mark Rutland >> --- >> include/asm-generic/pgtable.h | 20 ++++++++++++++++++++ >> 1 file changed, 20 insertions(+) >> >> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h >> index 798ea36a0549..e2e2bef07dd2 100644 >> --- a/include/asm-generic/pgtable.h >> +++ b/include/asm-generic/pgtable.h >> @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void) >> #define mm_pmd_folded(mm) __is_defined(__PAGETABLE_PMD_FOLDED) >> #endif >> >> +/* >> + * p?d_leaf() - true if this entry is a final mapping to a physical address. >> + * This differs from p?d_huge() by the fact that they are always available (if >> + * the architecture supports large pages at the appropriate level) even >> + * if CONFIG_HUGETLB_PAGE is not defined. >> + * Only meaningful when called on a valid entry. >> + */ >> +#ifndef pgd_leaf >> +#define pgd_leaf(x) 0 >> +#endif >> +#ifndef p4d_leaf >> +#define p4d_leaf(x) 0 >> +#endif >> +#ifndef pud_leaf >> +#define pud_leaf(x) 0 >> +#endif >> +#ifndef pmd_leaf >> +#define pmd_leaf(x) 0 >> +#endif > > Any reason you made these #defines rather than static inlines? No strong reason - but these have to be #defines in the arch overrides so the #ifndef works, so I was being consistent here. I guess a static inline might avoid warnings although I haven't seen any. Steve