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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A44FC433FE for ; Mon, 7 Nov 2022 09:05:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5B4906B0071; Mon, 7 Nov 2022 04:05:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 564336B0072; Mon, 7 Nov 2022 04:05:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 453706B0073; Mon, 7 Nov 2022 04:05:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 37CE26B0071 for ; Mon, 7 Nov 2022 04:05:15 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 06E5C120CFF for ; Mon, 7 Nov 2022 09:05:15 +0000 (UTC) X-FDA: 80106062190.18.0A17351 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf23.hostedemail.com (Postfix) with ESMTP id 6B7C0140008 for ; Mon, 7 Nov 2022 09:05:14 +0000 (UTC) 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 ams.source.kernel.org (Postfix) with ESMTPS id BB916B80E84; Mon, 7 Nov 2022 09:05:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEFD2C433C1; Mon, 7 Nov 2022 09:05:07 +0000 (UTC) Date: Mon, 7 Nov 2022 09:05:04 +0000 From: Catalin Marinas To: Herbert Xu Cc: Linus Torvalds , Arnd Bergmann , Christoph Hellwig , Greg Kroah-Hartman , Will Deacon , Marc Zyngier , Andrew Morton , Ard Biesheuvel , Isaac Manjarres , Saravana Kannan , Alasdair Kergon , Daniel Vetter , Joerg Roedel , Mark Brown , Mike Snitzer , "Rafael J. Wysocki" , Robin Murphy , linux-mm@kvack.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 11/13] crypto: Use ARCH_DMA_MINALIGN instead of ARCH_KMALLOC_MINALIGN Message-ID: References: <20221106220143.2129263-1-catalin.marinas@arm.com> <20221106220143.2129263-12-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf23.hostedemail.com: domain of cmarinas@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=cmarinas@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667811914; a=rsa-sha256; cv=none; b=3YuitDlLR5jeRuFWpIkCsQFHveGmEnN5FBJpudVjZC2ki43ggxIU5NIyHLgPs0vrIfom4I Uy7ntlgkfUDXnawaEoo7EKoOyoMyAFZ4DV+HaU8L8zsaYtn4wRviDRTOblTeoyw8foyo4G +faPPfzEbr/+qlo1W3WyTHlJ0lcDpU4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667811914; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VBLIWHRQpu51JrVkcbVJKZAUbMoASYwU81bAncg94uQ=; b=Tv3d3ZohFSc4BDMZzoe1MQdz1EF8RW9iPIhWeJGDP32OlSz4MR0QbM0OmAqbrU/P2Atr1v MjYulUvCpL4Yw/+PsH3jlyDlKrDcLUqSU5qLqqQ+K/UiXXIyys5cyxsbhb3l5FsjTxk9/6 Q9l8SzWPv7AlpwCUEr+PnpKtgWohIF4= X-Stat-Signature: iqii6isaukyybem7t1ikkhck9qsa1817 X-Rspamd-Queue-Id: 6B7C0140008 Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=arm.com (policy=none); spf=pass (imf23.hostedemail.com: domain of cmarinas@kernel.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=cmarinas@kernel.org X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1667811914-659498 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Nov 07, 2022 at 10:22:18AM +0800, Herbert Xu wrote: > On Sun, Nov 06, 2022 at 10:01:41PM +0000, Catalin Marinas wrote: > > ARCH_DMA_MINALIGN represents the minimum (static) alignment for safe DMA > > operations while ARCH_KMALLOC_MINALIGN is the minimum kmalloc() > > alignment. This will ensure that the static alignment of various > > structures or members of those structures( e.g. __ctx[] in struct > > aead_request) is safe for DMA. Note that sizeof such structures becomes > > aligned to ARCH_DMA_MINALIGN and kmalloc() will honour such alignment, > > so there is no confusion for the compiler. > > > > Signed-off-by: Catalin Marinas > > Cc: Herbert Xu > > Cc: Ard Biesheuvel > > --- > > > > I know Herbert NAK'ed this patch but I'm still keeping it here > > temporarily, until we agree on some refactoring at the crypto code. FTR, > > I don't think there's anything wrong with this patch since kmalloc() > > will return ARCH_DMA_MINALIGN-aligned objects if the sizeof such objects > > is a multiple of ARCH_DMA_MINALIGN (side-effect of > > CRYPTO_MINALIGN_ATTR). > > As I said before changing CRYPTO_MINALIGN doesn't do anything and > that's why this patch is broken. Well, it does ensure that the __alignof__ and sizeof structures like crypto_alg and aead_request is still 128 after this change. A kmalloc() of a size multiple of 128 returns a 128-byte aligned object. So the aim is just to keep the current binary layout/alignment to 128 on arm64. In theory, no functional change. Of course, there are better ways to do it but I think the crypto code should move away from ARCH_KMALLOC_MINALIGN and use something like dma_get_cache_alignment() instead. The cra_alignmask should be specific to the device and typically small values (or 0 if no alignment required by the device). The DMA alignment is specific to the SoC and CPU, so this should be handled elsewhere. As I don't fully understand the crypto code, I had a naive attempt at forcing a higher alignmask but it ended up in a kernel panic: diff --git a/include/linux/crypto.h b/include/linux/crypto.h index 2324ab6f1846..6dc84c504b52 100644 --- a/include/linux/crypto.h +++ b/include/linux/crypto.h @@ -13,6 +13,7 @@ #define _LINUX_CRYPTO_H #include +#include #include #include #include @@ -696,7 +697,7 @@ static inline unsigned int crypto_tfm_alg_blocksize(struct crypto_tfm *tfm) static inline unsigned int crypto_tfm_alg_alignmask(struct crypto_tfm *tfm) { - return tfm->__crt_alg->cra_alignmask; + return tfm->__crt_alg->cra_alignmask | (dma_get_cache_alignment() - 1); } static inline u32 crypto_tfm_get_flags(struct crypto_tfm *tfm) -- Catalin