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=-14.2 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,TVD_SUBJ_WIPE_DEBT, URIBL_BLOCKED,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 A3C8CC433E6 for ; Wed, 10 Mar 2021 08:15:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7526664FF1 for ; Wed, 10 Mar 2021 08:15:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231389AbhCJIPC (ORCPT ); Wed, 10 Mar 2021 03:15:02 -0500 Received: from pegase1.c-s.fr ([93.17.236.30]:8101 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229643AbhCJIOb (ORCPT ); Wed, 10 Mar 2021 03:14:31 -0500 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4DwPxX24hjz9tyNS; Wed, 10 Mar 2021 09:14:24 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id tNNusIgIeCpa; Wed, 10 Mar 2021 09:14:24 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4DwPxX17kXz9tyNR; Wed, 10 Mar 2021 09:14:24 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 249A98B783; Wed, 10 Mar 2021 09:14:25 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id aH2RPuDK2FLr; Wed, 10 Mar 2021 09:14:25 +0100 (CET) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 9CA0F8B77E; Wed, 10 Mar 2021 09:14:24 +0100 (CET) Subject: Re: [PATCH v1 01/15] powerpc/uaccess: Remove __get_user_allowed() and unsafe_op_wrap() To: Daniel Axtens , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org References: <87im6ao7ld.fsf@dja-thinkpad.axtens.net> From: Christophe Leroy Message-ID: Date: Wed, 10 Mar 2021 09:14:23 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <87im6ao7ld.fsf@dja-thinkpad.axtens.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 01/03/2021 à 23:02, Daniel Axtens a écrit : > > > Christophe Leroy writes: > >> Those two macros have only one user which is unsafe_get_user(). >> >> Put everything in one place and remove them. >> >> Signed-off-by: Christophe Leroy >> --- >> arch/powerpc/include/asm/uaccess.h | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h >> index 78e2a3990eab..8cbf3e3874f1 100644 >> --- a/arch/powerpc/include/asm/uaccess.h >> +++ b/arch/powerpc/include/asm/uaccess.h >> @@ -53,9 +53,6 @@ static inline bool __access_ok(unsigned long addr, unsigned long size) >> #define __put_user(x, ptr) \ >> __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr))) >> >> -#define __get_user_allowed(x, ptr) \ >> - __get_user_nocheck((x), (ptr), sizeof(*(ptr)), false) >> - >> #define __get_user_inatomic(x, ptr) \ >> __get_user_nosleep((x), (ptr), sizeof(*(ptr))) >> #define __put_user_inatomic(x, ptr) \ >> @@ -482,8 +479,11 @@ user_write_access_begin(const void __user *ptr, size_t len) >> #define user_write_access_begin user_write_access_begin >> #define user_write_access_end prevent_current_write_to_user >> >> -#define unsafe_op_wrap(op, err) do { if (unlikely(op)) goto err; } while (0) >> -#define unsafe_get_user(x, p, e) unsafe_op_wrap(__get_user_allowed(x, p), e) >> +#define unsafe_get_user(x, p, e) do { \ >> + if (unlikely(__get_user_nocheck((x), (p), sizeof(*(p)), false)))\ >> + goto e; \ >> +} while (0) >> + > > This seems correct to me. > > Checkpatch does have one check that is relevant: > > CHECK: Macro argument reuse 'p' - possible side-effects? > #36: FILE: arch/powerpc/include/asm/uaccess.h:482: > +#define unsafe_get_user(x, p, e) do { \ > + if (unlikely(__get_user_nocheck((x), (p), sizeof(*(p)), false)))\ > + goto e; \ > +} while (0) > > Given that we are already creating a new block, should we do something > like this (completely untested): > > #define unsafe_get_user(x, p, e) do { \ > __typeof__(p) __p = (p); > if (unlikely(__get_user_nocheck((x), (__p), sizeof(*(__p)), false)))\ > goto e; \ > } while (0) > As mentioned by Segher, this is not needed, sizeof(p) doesn't evaluate (p) so (p) is only evaluated once in the macro, so no risk of side-effects with that. Christophe