From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759585AbdEWFBt (ORCPT ); Tue, 23 May 2017 01:01:49 -0400 Received: from [128.1.224.119] ([128.1.224.119]:47990 "EHLO deadmen.hmeau.com" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1757491AbdEWFBr (ORCPT ); Tue, 23 May 2017 01:01:47 -0400 Date: Tue, 23 May 2017 13:01:27 +0800 From: Herbert Xu To: Eric Biggers Cc: linux-crypto@vger.kernel.org, "David S . Miller" , x86@kernel.org, linux-kernel@vger.kernel.org, Josh Poimboeuf , Eric Biggers Subject: Re: [PATCH] crypto: x86/aes - Don't use %rbp as temporary register Message-ID: <20170523050127.GD17569@gondor.apana.org.au> References: <20170517040308.406-1-ebiggers3@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170517040308.406-1-ebiggers3@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 16, 2017 at 09:03:08PM -0700, Eric Biggers wrote: > From: Eric Biggers > > When using the "aes-asm" implementation of AES (*not* the AES-NI > implementation) on an x86_64, v4.12-rc1 kernel with lockdep enabled, the > following warning was reported, along with a long unwinder dump: > > WARNING: kernel stack regs at ffffc90000643558 in kworker/u4:2:155 has bad 'bp' value 000000000000001c > > The problem is that aes_enc_block() and aes_dec_block() use %rbp as a > temporary register, which breaks stack traces if an interrupt occurs. > > Fix this by replacing %rbp with %r9, which was being used to hold the > saved value of %rbp. This required rearranging the AES round macro > slightly since %r9d cannot be used as the target of a move from %ah-%dh. > > Performance is essentially unchanged --- actually about 0.2% faster than > before. Interestingly, I also measured aes-generic as being nearly 7% > faster than aes-asm, so perhaps aes-asm has outlived its usefulness... > > Signed-off-by: Eric Biggers Patch applied. Thanks. -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt