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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77F22C433F5 for ; Thu, 7 Apr 2022 09:25:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243709AbiDGJ1Y (ORCPT ); Thu, 7 Apr 2022 05:27:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241322AbiDGJ1T (ORCPT ); Thu, 7 Apr 2022 05:27:19 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B21F8BE14 for ; Thu, 7 Apr 2022 02:25:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 323EBCE26CD for ; Thu, 7 Apr 2022 09:25:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77837C385A0; Thu, 7 Apr 2022 09:25:13 +0000 (UTC) Date: Thu, 7 Apr 2022 10:25:10 +0100 From: Catalin Marinas To: Muchun Song Cc: Will Deacon , Marc Zyngier , Arnd Bergmann , Greg Kroah-Hartman , Andrew Morton , Linus Torvalds , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Herbert Xu , "David S. Miller" Subject: Re: [PATCH 07/10] crypto: Use ARCH_DMA_MINALIGN instead of ARCH_KMALLOC_MINALIGN Message-ID: References: <20220405135758.774016-1-catalin.marinas@arm.com> <20220405135758.774016-8-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 07, 2022 at 02:14:15PM +0800, Muchun Song wrote: > On Tue, Apr 05, 2022 at 02:57:55PM +0100, Catalin Marinas wrote: > > ARCH_DMA_MINALIGN represents the minimum (static) alignment for safe DMA > > operations while ARCH_KMALLOC_MINALIGN is the minimum kmalloc() objects > > alignment. > > > > Signed-off-by: Catalin Marinas > > Cc: Herbert Xu > > Cc: "David S. Miller" > > --- > > include/linux/crypto.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/linux/crypto.h b/include/linux/crypto.h > > index 2324ab6f1846..654b9c355575 100644 > > --- a/include/linux/crypto.h > > +++ b/include/linux/crypto.h > > @@ -167,7 +167,7 @@ > > * maintenance for non-coherent DMA (cache invalidation in particular) does not > > * affect data that may be accessed by the CPU concurrently. > > */ > > -#define CRYPTO_MINALIGN ARCH_KMALLOC_MINALIGN > > +#define CRYPTO_MINALIGN ARCH_DMA_MINALIGN > > I don't think this should be changed since ARCH_KMALLOC_MINALIGN is > already aligned with the size what you need. With this series, ARCH_KMALLOC_MINALIGN is no longer safe for non-coherent DMA on all arm64 SoCs, that's what ARCH_DMA_MINALIGN will cover. Now, looking at the comment for CRYPTO_MINALIGN, one aspect it covers is the minimum alignment required by C for the crypto_tfm structure access. So a smaller ARCH_KMALLOC_MINALIGN would do. But the other part of the comment mentions in-structure alignment for non-coherent DMA. Here we'd need the upper bound alignment, ARCH_DMA_MINALIGN. I'll follow up on Herbert's email as I think he has a good point on structure vs kmalloc() alignment. -- Catalin