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 A66B742A83; Sun, 27 Apr 2025 01:02:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745715765; cv=none; b=Ul9kI4xQinifjUbMvK3i6ER/B+ylSDCxyQ762YahzayzHYCOUFVPdYUZzs1hpDHKJ9JrDRvshDL37JI/Ff5s5NTRcADMZzJlje6iRVXxvtfubrzW9i2iPdA2omtv8K0P4XUwrS7PtZLhc+AVzYIhaUxOZr5TD9/Lk/qxRPrxvHA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745715765; c=relaxed/simple; bh=MwWC0ebZT3d3MlgdSCMljk/IiWQqDJK/sfFSFFVgLjw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WIKIWTkuZMIybfEWF43J2/bDRdWU07aaK2TzTUjZU/iuKkApLX9U5ShG4yT60AAgn9cjYCvhOealb88YY2/L+l3cHUn5+BgF3uA3UmdweLsYqYCuCOC/KhkIfLSU1D2mAQN97sW1PrbBdkP2AVX5A/6LTI6XtSAK49ZmrZI88As= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bPyZLOlv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bPyZLOlv" 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> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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