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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 AA15CC433EF for ; Fri, 17 Sep 2021 14:32:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B27760EE2 for ; Fri, 17 Sep 2021 14:32:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242727AbhIQOdw convert rfc822-to-8bit (ORCPT ); Fri, 17 Sep 2021 10:33:52 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.85.151]:32494 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241700AbhIQOdt (ORCPT ); Fri, 17 Sep 2021 10:33:49 -0400 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-62-I8DWIADxNXumcC2ZvYPdxg-1; Fri, 17 Sep 2021 15:32:25 +0100 X-MC-Unique: I8DWIADxNXumcC2ZvYPdxg-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) by AcuMS.aculab.com (fd9f:af1c:a25b:0:994c:f5c2:35d6:9b65) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Fri, 17 Sep 2021 15:32:23 +0100 Received: from AcuMS.Aculab.com ([fe80::994c:f5c2:35d6:9b65]) by AcuMS.aculab.com ([fe80::994c:f5c2:35d6:9b65%12]) with mapi id 15.00.1497.023; Fri, 17 Sep 2021 15:32:23 +0100 From: David Laight To: 'Christophe Leroy' , Benjamin Herrenschmidt , Paul Mackerras , "Michael Ellerman" CC: "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH v2] powerpc/32: Don't use a struct based type for pte_t Thread-Topic: [PATCH v2] powerpc/32: Don't use a struct based type for pte_t Thread-Index: AQHXq8wPR5JW25uF60m9xktVKLekzquoSMug Date: Fri, 17 Sep 2021 14:32:22 +0000 Message-ID: <505920070e5f4bf8ad7ccaa12f346469@AcuMS.aculab.com> References: In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christophe Leroy > Sent: 17 September 2021 14:58 > > Long time ago we had a config item called STRICT_MM_TYPECHECKS > to build the kernel with pte_t defined as a structure in order > to perform additional build checks or build it with pte_t > defined as a simple type in order to get simpler generated code. > ... > diff --git a/arch/powerpc/include/asm/pgtable-types.h b/arch/powerpc/include/asm/pgtable-types.h > index d11b4c61d686..c60199fc6fa6 100644 > --- a/arch/powerpc/include/asm/pgtable-types.h > +++ b/arch/powerpc/include/asm/pgtable-types.h > @@ -5,14 +5,26 @@ > /* PTE level */ > #if defined(CONFIG_PPC_8xx) && defined(CONFIG_PPC_16K_PAGES) > typedef struct { pte_basic_t pte, pte1, pte2, pte3; } pte_t; > -#else > +#elif defined(__CHECKER__) || !defined(CONFIG_PPC32) > typedef struct { pte_basic_t pte; } pte_t; > +#else > +typedef pte_basic_t pte_t; > #endif > + > +#if defined(__CHECKER__) || !defined(CONFIG_PPC32) || \ > + (defined(CONFIG_PPC_8xx) && defined(CONFIG_PPC_16K_PAGES)) > #define __pte(x) ((pte_t) { (x) }) > static inline pte_basic_t pte_val(pte_t x) > { > return x.pte; > } > +#else > +#define __pte(x) ((pte_t)(x)) > +static inline pte_basic_t pte_val(pte_t x) > +{ > + return x; > +} > +#endif Would it be better to define: static inline pte_basic_*pte_basic(pte_t *x) { #if xxx return x; #else return &x->pte; #endif } Then pte_val(x) is always *pt_basic(x) and the casts like: > - pte_basic_t *entry = &ptep->pte; > + pte_basic_t *entry = (pte_basic_t *)ptep; can go away. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)