Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755082AbbB0QNn (ORCPT ); Fri, 27 Feb 2015 11:13:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47071 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750777AbbB0QNm (ORCPT ); Fri, 27 Feb 2015 11:13:42 -0500 Message-ID: <54F0979D.5060001@redhat.com> Date: Fri, 27 Feb 2015 17:13:17 +0100 From: Denys Vlasenko User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Andy Lutomirski , x86@kernel.org, linux-kernel@vger.kernel.org CC: Borislav Petkov , Oleg Nesterov , Konrad Rzeszutek Wilk , Boris Ostrovsky , Rusty Russell Subject: Re: [RFC 2/3] x86: Switch all C consumers of kernel_stack to this_cpu_sp0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2130 Lines: 51 On 02/27/2015 01:07 AM, Andy Lutomirski wrote: > This will make modifying the semantics of kernel_stack easier. > > Cc: Konrad Rzeszutek Wilk > Cc: Boris Ostrovsky > Cc: Rusty Russell > Signed-off-by: Andy Lutomirski > --- > arch/x86/include/asm/thread_info.h | 3 +-- > arch/x86/kernel/traps.c | 2 +- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h > index e82e95abc92b..92549053d86d 100644 > --- a/arch/x86/include/asm/thread_info.h > +++ b/arch/x86/include/asm/thread_info.h > @@ -163,8 +163,7 @@ DECLARE_PER_CPU(unsigned long, kernel_stack); > static inline struct thread_info *current_thread_info(void) > { > struct thread_info *ti; > - ti = (void *)(this_cpu_read_stable(kernel_stack) + > - KERNEL_STACK_OFFSET - THREAD_SIZE); > + ti = (void *)(this_cpu_sp0() - THREAD_SIZE); > return ti; > } > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index c74f2f5652da..d287ea779728 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -174,7 +174,7 @@ void ist_begin_non_atomic(struct pt_regs *regs) > * will catch asm bugs and any attempt to use ist_preempt_enable > * from double_fault. > */ > - BUG_ON(((current_stack_pointer() ^ this_cpu_read_stable(kernel_stack)) > + BUG_ON(((current_stack_pointer() ^ (this_cpu_sp0() - 1)) > & ~(THREAD_SIZE - 1)) != 0); While we are at it, I propose a more readable version of this check: BUG_ON(this_cpu_sp0() - current_stack_pointer() >= THREAD_SIZE); Yes, I am aware that it is not equivalent to the existing condition - it uses the fact that this_cpu_sp0(), previous check wasn't making that assumption. But that assumption is true, so shouldn't be a problem. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/