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 AD5C7C369CB for ; Sat, 26 Apr 2025 18:05:39 +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=wJjqLBoiEqR01dLF6VgyUiMDMqkfGLWifEiEbgwa85M=; b=Gi44ymBCQmSvmF EJfm7cuZufb8KtT9Jyh8kb5oRFOc4ml2pWFt5g/RxiBxRkZN3uNoA4CCTwWpYwZJ+dqDRfni4O6aY CcfYOz/RCHuDcw+l7IClVMJY69h53cEsOPCdebwBVGUC6VeLXepyku1YoD9XAHD8G8l+90xrgxFXR oC0ah2S+yq6jii8YpKdoZ+MjsaO4PE0cbhaHFeQ8aNfYp04PeICauJeH+CJuPpx2KuXxo6nnXr8Hy qT+OXojwaZv435beNqrP1xGhcVGs9sKhF/Sf1Gm4K80Yjsh23EyE+OFY6cw9xK6d81YacQBkO8Cwf sqH9q5GNZ/KJiCEU5p7w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8ju5-00000002NTB-364L; Sat, 26 Apr 2025 18:05:29 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u8jsB-00000002NJG-1ynD; Sat, 26 Apr 2025 18:03:31 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 13AE16115D; Sat, 26 Apr 2025 18:03:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C994C4CEE2; Sat, 26 Apr 2025 18:03:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745690608; bh=thPYajZSkuIUqKSQ0PKrjdP700DcSK2zwAu2Gky2T80=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nAIxHEC/RBFXC7YAAr3+tsr8rzEcee3Oga1vMPOVdLEclJGRGGYsap6d40ssYdREa 631y8iWvrWajenPInP5JKnMuJ2fzsFVn4xbQ/K+cHhgPVnyuchNRRoD0ozvKffZkS3 MqUsr8paPOUnFmn+B8HDI8yKlJGh1TXUf3fq6tuJ1SIjPZir6nq73386jFGlYKnBTI uo2ZHr9L3pkwpshwb0rthNh+eao6mVOKjQYtoSDUrpgKEgzJXu+h6VzFzy4Z/K4auE MgMeah9RtM9RNppv7fmQMq0y8aXytAvAE0U5aitXE09LbzHtDgGADWAkJrVYOWn55s dQXkKhP5hQ5yw== Date: Sat, 26 Apr 2025 11:03:26 -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: <20250426180326.GA1184@sol.localdomain> References: <20250426065041.1551914-12-ebiggers@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Sat, Apr 26, 2025 at 06:50:43PM +0800, Herbert Xu wrote: > Eric Biggers wrote: > > > > +void sha256_blocks_arch(u32 state[SHA256_STATE_WORDS], > > + const u8 *data, size_t nblocks) > > +{ > > + if (static_branch_likely(&have_sha256_x86) && crypto_simd_usable()) { > > + kernel_fpu_begin(); > > + static_call(sha256_blocks_x86)(state, data, nblocks); > > + kernel_fpu_end(); > > + } else { > > + sha256_blocks_generic(state, data, nblocks); > > + } > > Why did you restore the SIMD fallback path? Please provide a real > use-case for doing SHA2 in a hardirq or I'll just remove it again. The SHA-256 library functions currently work in any context, and this patch series preserves that behavior. Changing that would be a separate change. 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. Yes, no one *should* be doing SHA-256 in a hardirq. But I don't think that means we should corrupt a random task's FPU registers if someone doesn't follow best practices, when we can easily make the API just work as expected. - Eric _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv