Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752249AbdF3P4d convert rfc822-to-8bit (ORCPT ); Fri, 30 Jun 2017 11:56:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:59262 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751695AbdF3P4b (ORCPT ); Fri, 30 Jun 2017 11:56:31 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D5F2D22BE6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org MIME-Version: 1.0 In-Reply-To: <20170630155500.vnn5szd6smpn5nrz@treble> References: <20170629190559.ttw52ahwtsjynayx@treble> <20170629214134.c36krjhvzegwkfjk@treble> <20170630021249.cqkszxaqtwakmzpg@treble> <20170630131148.yszdjakekrwqlf6k@treble> <20170630155500.vnn5szd6smpn5nrz@treble> From: Andy Lutomirski Date: Fri, 30 Jun 2017 08:56:09 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 6/8] x86/entry: add unwind hint annotations To: Josh Poimboeuf Cc: Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , live-patching@vger.kernel.org, Linus Torvalds , Jiri Slaby , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , Mike Galbraith Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1401 Lines: 45 On Fri, Jun 30, 2017 at 8:55 AM, Josh Poimboeuf wrote: > On Fri, Jun 30, 2017 at 08:44:40AM -0700, Andy Lutomirski wrote: >> > A few comments about the first patch: >> > >> > https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry_irq_stack&id=3e2aa2102cc1c5e60d4a8637bff78d0478a55059 >> > >> > - It uses a '693:' label instead of '.Lirqs_off_\@:' >> >> Touché! >> >> > >> > - There's a comment I don't follow: >> > >> > "Anything that can interrupt us here without using IST must be >> > *extremely* careful to limit its stack usage." >> > >> > What specifically could interrupt there without using IST? >> >> #DB, later on in the series. I'll update the comment. >> >> > >> > - Since do_softirq_own_stack() is a callable function, I think it still >> > needs to save rbp. >> >> Whoops. >> >> > >> > - Why change the "jmp error_exit" to "ret" in >> > xen_do_hypervisor_callback()? >> >> To match the other change I made there. I removed both. > > One more thing I forgot to mention: if you could use r10 instead of r11, > that would be helpful because it means one less register undwarf needs > to know about. (It already deals with r10 because of GCC stack > realignment). I'll let you figure that one out :) (Although I think I agree with hpa: why not let it support all regs? Or am I missing something still?) > > -- > Josh