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=-8.3 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=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 66728C10F14 for ; Thu, 10 Oct 2019 06:56:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 473952053B for ; Thu, 10 Oct 2019 06:56:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733038AbfJJG4L (ORCPT ); Thu, 10 Oct 2019 02:56:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47478 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732930AbfJJG4K (ORCPT ); Thu, 10 Oct 2019 02:56:10 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4DA0D3001A6C; Thu, 10 Oct 2019 06:56:10 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-56.pek2.redhat.com [10.72.12.56]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C749519D70; Thu, 10 Oct 2019 06:56:04 +0000 (UTC) Date: Thu, 10 Oct 2019 14:56:00 +0800 From: Dave Young To: Arvind Sankar Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Hans de Goede , linux-crypto@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Herbert Xu , Ard Biesheuvel , Stephan Mueller , kexec@lists.infradead.org Subject: Re: [PATCH] lib/string: make memzero_explicit inline instead of external Message-ID: <20191010065600.GA9838@dhcp-128-65.nay.redhat.com> References: <1d17349e-98ab-b582-6981-b484b0e970b6@redhat.com> <20191007220000.GA408752@rani.riverdale.lan> <20191010025229.GA3376@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191010025229.GA3376@dhcp-128-65.nay.redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Thu, 10 Oct 2019 06:56:10 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/10/19 at 10:52am, Dave Young wrote: > On 10/07/19 at 06:00pm, Arvind Sankar wrote: > > With the use of the barrier implied by barrier_data(), there is no need > > for memzero_explicit to be extern. Making it inline saves the overhead > > of a function call, and allows the code to be reused in arch/*/purgatory > > without having to duplicate the implementation. > > > > Fixes: 906a4bb97f5d ("crypto: sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit") > > Reviewed-by: Hans de Goede > > Tested-by: Hans de Goede > > Signed-off-by: Arvind Sankar > > --- > > include/linux/string.h | 21 ++++++++++++++++++++- > > lib/string.c | 21 --------------------- > > 2 files changed, 20 insertions(+), 22 deletions(-) > > > > diff --git a/include/linux/string.h b/include/linux/string.h > > index b2f9df7f0761..b6ccdc2c7f02 100644 > > --- a/include/linux/string.h > > +++ b/include/linux/string.h > > @@ -227,7 +227,26 @@ static inline bool strstarts(const char *str, const char *prefix) > > } > > > > size_t memweight(const void *ptr, size_t bytes); > > -void memzero_explicit(void *s, size_t count); > > + > > +/** > > + * memzero_explicit - Fill a region of memory (e.g. sensitive > > + * keying data) with 0s. > > + * @s: Pointer to the start of the area. > > + * @count: The size of the area. > > + * > > + * Note: usually using memset() is just fine (!), but in cases > > + * where clearing out _local_ data at the end of a scope is > > + * necessary, memzero_explicit() should be used instead in > > + * order to prevent the compiler from optimising away zeroing. > > + * > > + * memzero_explicit() doesn't need an arch-specific version as > > + * it just invokes the one of memset() implicitly. > > + */ > > +static inline void memzero_explicit(void *s, size_t count) > > +{ > > + memset(s, 0, count); > > + barrier_data(s); > > +} > > > > /** > > * kbasename - return the last part of a pathname. > > diff --git a/lib/string.c b/lib/string.c > > index cd7a10c19210..08ec58cc673b 100644 > > --- a/lib/string.c > > +++ b/lib/string.c > > @@ -748,27 +748,6 @@ void *memset(void *s, int c, size_t count) > > EXPORT_SYMBOL(memset); > > #endif > > > > -/** > > - * memzero_explicit - Fill a region of memory (e.g. sensitive > > - * keying data) with 0s. > > - * @s: Pointer to the start of the area. > > - * @count: The size of the area. > > - * > > - * Note: usually using memset() is just fine (!), but in cases > > - * where clearing out _local_ data at the end of a scope is > > - * necessary, memzero_explicit() should be used instead in > > - * order to prevent the compiler from optimising away zeroing. > > - * > > - * memzero_explicit() doesn't need an arch-specific version as > > - * it just invokes the one of memset() implicitly. > > - */ > > -void memzero_explicit(void *s, size_t count) > > -{ > > - memset(s, 0, count); > > - barrier_data(s); > > -} > > -EXPORT_SYMBOL(memzero_explicit); > > - > > #ifndef __HAVE_ARCH_MEMSET16 > > /** > > * memset16() - Fill a memory area with a uint16_t > > -- > > Thanks for the fix! Ccing kexec list since the problem is kexec/kdump > related. People can try it when they see same issue. > Also: Tested-by: Dave Young Thanks Dave