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 C142FC369D8 for ; Sun, 27 Apr 2025 01:07:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lhZqNPK+3qur5KT4zF1H9SCOT7iiZxQ3shEb0zor8do=; b=YZuIo1xYwC4seD5ggxNyR/cLKm hUPwibfZj12C7zuFrHk+DQauYad4avJhrACXsPJHlOP8XmJTzi/diKun+R413M8Z6HWHOViyic15f Q6Y2nVCCj+5GoUQNDDOIrfD23DNq7cJT33hC1JzhYYyTJeUaiPouwt7VGteG15Nt2hnFcZW4/ov5I 0Np12us1AaF4oRD+Z2FyCekdU5Q6d6brk4Penkm4Jy2ZWFk+Eag2seu0tDyyrsAYUVMwTimc/i7kY 8VfsOF7bRqjwYflOZFi5eL1zlSBF1eIdB7Oz7EC4C1EAv/SdKnXoCWgAvZR4iu6iHoKctEESVw2Fy 68PO3NKA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8qUZ-00000002hJu-3gKF; Sun, 27 Apr 2025 01:07:35 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8qPu-00000002gqe-0g5K; Sun, 27 Apr 2025 01:02:47 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 4A6B45C5B40; Sun, 27 Apr 2025 01:00:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A008C4CEE2; Sun, 27 Apr 2025 01:02:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745715765; bh=MwWC0ebZT3d3MlgdSCMljk/IiWQqDJK/sfFSFFVgLjw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bPyZLOlvkggv+3wlQaPSM6gxDYFrytafe2vABHHUGe/DW28h51dobXwpP5JnZZv8e siueA/NSLIi8nuwG9dfsk1681ilJovb4Z29iknbvMhR8GPTRbN0ZVeKBFFKZOwwljj 3U9QNUIWg3TN3LjeAfIWIWZYU3/vTYkS431OGKS6sxinbT9y/6X+clr/wOAXFX7E2r VeFF9mnbIdUIuH/fv/IyMBN/ULQFSIccwdyDW2UT7HFOKtoe4pSnJMpfS90ZAD5CqB IjZesituwcBevS0RAxopmnZA/CE/trjgjd8Bsfakzob1TBrOKKYrpOqivjGk4OuyjL pu9aEs4XUVNSA== Date: Sat, 26 Apr 2025 18:02:48 -0700 From: Eric Biggers To: Herbert Xu Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, sparclinux@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, ardb@kernel.org, Jason@zx2c4.com, torvalds@linux-foundation.org Subject: Re: [PATCH 11/13] crypto: x86/sha256 - implement library instead of shash Message-ID: <20250427010248.GA68006@quark> References: <20250426065041.1551914-12-ebiggers@kernel.org> <20250426180326.GA1184@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250426_180246_246045_A0065DA4 X-CRM114-Status: GOOD ( 17.29 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Apr 27, 2025 at 08:18:56AM +0800, Herbert Xu wrote: > On Sat, Apr 26, 2025 at 11:03:26AM -0700, Eric Biggers wrote: > > > > The SHA-256 library functions currently work in any context, and this patch > > series preserves that behavior. Changing that would be a separate change. > > I've already removed the SIMD fallback path and your patch is > adding it back. While you've been pushing out a lot of random broken changes to shash recently, the SHA-256 library functions weren't SIMD-optimized until this patchset. > > But also as I've explained before, for the library API the performance benefit > > of removing the crypto_simd_usable() doesn't seem to be worth the footgun that > > would be introduced. Your position is, effectively, that if someone calls one > > of the sha256*() functions from a hardirq, we should sometimes corrupt a random > > task's FPU registers. That's a really bad bug that is very difficult to > > root-cause. My position is that we should make it just work as expected. > > kernel_fpu_begin already does a WARN_ON when called in hardirq > context and it can't safely use the FPU, there is no silent > corruption. Only when CONFIG_X86_DEBUG_FPU is enabled, which people don't enable in production. And even if that is enabled, it's just a WARN, so the registers still get used and corrupted anyway. - Eric