From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753908AbdK0R3e (ORCPT ); Mon, 27 Nov 2017 12:29:34 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:60559 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775AbdK0R3d (ORCPT ); Mon, 27 Nov 2017 12:29:33 -0500 Date: Mon, 27 Nov 2017 18:29:27 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Dave Hansen , Andy Lutomirski , Thomas Gleixner , "H . Peter Anvin" , Borislav Petkov , Linus Torvalds Subject: Re: [PATCH 10/24] x86/mm/kaiser: Map the entry stack variables Message-ID: <20171127172927.ng5iigkvnkfgmixb@hirez.programming.kicks-ass.net> References: <20171127104923.14378-1-mingo@kernel.org> <20171127104923.14378-11-mingo@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171127104923.14378-11-mingo@kernel.org> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 27, 2017 at 11:49:09AM +0100, Ingo Molnar wrote: > diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c > index 7b348cc33e2d..f4f4ab8525bd 100644 > --- a/arch/x86/kernel/cpu/common.c > +++ b/arch/x86/kernel/cpu/common.c > @@ -1515,7 +1515,7 @@ EXPORT_PER_CPU_SYMBOL(__preempt_count); > * the top of the kernel stack. Use an extra percpu variable to track the > * top of the kernel stack directly. > */ > -DEFINE_PER_CPU(unsigned long, cpu_current_top_of_stack) = > +DEFINE_PER_CPU_USER_MAPPED(unsigned long, cpu_current_top_of_stack) = > (unsigned long)&init_thread_union + THREAD_SIZE; > EXPORT_PER_CPU_SYMBOL(cpu_current_top_of_stack); I can't find where we would access this one without already having switched to kernel CR3. A kernel with this entire patch reverted seems to boot for me.