From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C7ED328E8 for ; Mon, 7 Nov 2022 09:05:11 +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> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DFA50C4332F for ; Mon, 7 Nov 2022 09:06:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=iJgptZKIrvNoGpgpKOaF2Mk4UJF+XQvPE95kB4GCnsc=; b=VUeWbMnkQ7pYsp NhcZ6aQQt3bZyPSppOz1I7isQNmkKMGgjC2Vzt8TFLYxCr2Bauyn3H4dGbFNXgcq3Chwv0DS2feH5 UPv3q8HvMCwOja2q+h4t4cW4N8L1fGyTc/C/emOP5PDus8ouBDEbMaoLCpaMAbxCE3a/G7Si4LttO ld4zsKvWE2Rb8skNJbPZv6QCH5pQYzJPHDJpVAffJT/xglyZWV0cMasn+5gxcrQ2K//kQD+DC4jc6 Z+d9jjQnxGzJBrs0DKKIDkpMQ+yHi8ADGg14wkCWS/Zk2iJkfwnkgvakJAxpiyyQkadrtJq+f4vTI i4Fig1L3MCsxe1gSWeMA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ory4K-00D4qi-1k; Mon, 07 Nov 2022 09:05:24 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ory4A-00D4lf-LF for linux-arm-kernel@lists.infradead.org; Mon, 07 Nov 2022 09:05:16 +0000 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-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221107_010515_038347_5FB60D64 X-CRM114-Status: GOOD ( 31.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel