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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4BCCCC433F5 for ; Wed, 17 Nov 2021 11:12:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2158C610D1 for ; Wed, 17 Nov 2021 11:12:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236676AbhKQLP4 (ORCPT ); Wed, 17 Nov 2021 06:15:56 -0500 Received: from muru.com ([72.249.23.125]:57208 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236674AbhKQLPz (ORCPT ); Wed, 17 Nov 2021 06:15:55 -0500 Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 8A3CB80F0; Wed, 17 Nov 2021 11:13:32 +0000 (UTC) Date: Wed, 17 Nov 2021 13:12:53 +0200 From: Tony Lindgren To: Ard Biesheuvel Cc: Arnd Bergmann , "Russell King (Oracle)" , Guillaume Tucker , linux-omap , Linux ARM , Nicolas Pitre , Kees Cook , Keith Packard , Linus Walleij , Nick Desaulniers , "kernelci@groups.io" Subject: Re: [PATCH v3 7/7] ARM: implement support for vmap'ed stacks Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org * Ard Biesheuvel [211117 10:49]: > On Wed, 17 Nov 2021 at 10:08, Ard Biesheuvel wrote: > > > > On Wed, 17 Nov 2021 at 10:07, Arnd Bergmann wrote: > > > > > > On Wed, Nov 17, 2021 at 10:03 AM Arnd Bergmann wrote: > > > > > > > > On Wed, Nov 17, 2021 at 9:36 AM Tony Lindgren wrote: > > > > > * Ard Biesheuvel [211117 08:29]: > > > > > > > > > > > > Thanks Tony, that is very helpful. I have a Beaglebone white somewhere > > > > > > so I'll try and reproduce it locally as well. > > > > > > > > > > I think with Beaglebone you may hit this only with suspend/resume if at > > > > > all. On am335x cpuidle is not shutting down the CPU. And only some models > > > > > will suspend to deeper idle states as it depends on the PMIC. > > > > > > > > > > If you have some test patch to try, just let me know. > > > > > > > > I looked at how the sleep code is called and found that cpu_suspend()/ > > > > __cpu_suspend() has interesting manipulation of the stack pointer to > > > > call the platform specific function with a simple 1:1 page table, > > > > I would expect the problem somewhere in there, haven't pinpointed > > > > the exact line yet, but if any of that code tries to local the physical > > > > address of the stack using virt_to_phys or its asm equivalent, this > > > > fails for a vmap stack. > > > > > > and just after sending this I see > > > > > > void __cpu_suspend_save(u32 *ptr, u32 ptrsz, u32 sp, u32 *save_ptr) > > > { > > > *save_ptr = virt_to_phys(ptr); > > > > > > 'ptr' is a pointer to the stack here. It might not be the only place that > > > needs fixing, but this clearly has to do a page table walk like > > > vmalloc_to_page() does to get to the correct physical address. > > > > > > > I had just arrived at the same conclusion. I'll fix this up and drop > > it in kernelci. > > Updated branch here: > https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/commit/?h=arm-vmap-stacks-v4 Great that branch boots for me! Regards, Tony