From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754754AbdKJWcj (ORCPT ); Fri, 10 Nov 2017 17:32:39 -0500 Received: from mail.efficios.com ([167.114.142.141]:41237 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754705AbdKJWch (ORCPT ); Fri, 10 Nov 2017 17:32:37 -0500 Date: Fri, 10 Nov 2017 22:32:54 +0000 (UTC) From: Mathieu Desnoyers To: Andy Lutomirski Cc: Boqun Feng , Peter Zijlstra , "Paul E. McKenney" , linux-kernel , linux-api , Andrew Hunter , maged michael , Avi Kivity , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Dave Watson , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrea Parri , "Russell King, ARM Linux" , Greg Hackmann , Will Deacon , David Sehr , Linus Torvalds , x86 , linux-arch Message-ID: <115800448.13060.1510353174125.JavaMail.zimbra@efficios.com> In-Reply-To: <1007217384.13056.1510352430448.JavaMail.zimbra@efficios.com> References: <20171110213717.12457-1-mathieu.desnoyers@efficios.com> <20171110213717.12457-6-mathieu.desnoyers@efficios.com> <1007217384.13056.1510352430448.JavaMail.zimbra@efficios.com> Subject: Re: [RFC PATCH for 4.15 05/10] x86: Introduce sync_core_before_usermode MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.142.141] X-Mailer: Zimbra 8.7.11_GA_1854 (ZimbraWebClient - FF52 (Linux)/8.7.11_GA_1854) Thread-Topic: x86: Introduce sync_core_before_usermode Thread-Index: 7ad8kyaDHgwyeovhIovyLBFp1+w4pNhVf7c0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Nov 10, 2017, at 5:20 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > ----- On Nov 10, 2017, at 5:02 PM, Andy Lutomirski luto@kernel.org wrote: > >> On Fri, Nov 10, 2017 at 1:37 PM, Mathieu Desnoyers >> wrote: >>> Introduce an architecture function that ensures the current CPU >>> issues a core serializing instruction before returning to usermode. >>> >>> This is needed to fix an existing core serialization bug on >>> thread migration, and also needed by the membarrier "sync_core" command. >>> >>> Architectures defining the sync_core_before_usermode() static inline >>> need to define ARCH_HAS_SYNC_CORE_BEFORE_USERMODE. >>> >>> Signed-off-by: Mathieu Desnoyers >>> CC: Peter Zijlstra >>> CC: Andy Lutomirski >>> CC: Paul E. McKenney >>> CC: Boqun Feng >>> CC: Andrew Hunter >>> CC: Maged Michael >>> CC: Avi Kivity >>> CC: Benjamin Herrenschmidt >>> CC: Paul Mackerras >>> CC: Michael Ellerman >>> CC: Dave Watson >>> CC: Thomas Gleixner >>> CC: Ingo Molnar >>> CC: "H. Peter Anvin" >>> CC: Andrea Parri >>> CC: Russell King >>> CC: Greg Hackmann >>> CC: Will Deacon >>> CC: David Sehr >>> CC: Linus Torvalds >>> CC: x86@kernel.org >>> CC: linux-arch@vger.kernel.org >>> --- >>> arch/x86/Kconfig | 1 + >>> arch/x86/include/asm/processor.h | 10 ++++++++++ >>> include/linux/processor.h | 6 ++++++ >>> 3 files changed, 17 insertions(+) >>> >>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >>> index 01f78c1d40b5..54fbb8960d94 100644 >>> --- a/arch/x86/Kconfig >>> +++ b/arch/x86/Kconfig >>> @@ -62,6 +62,7 @@ config X86 >>> select ARCH_HAS_SG_CHAIN >>> select ARCH_HAS_STRICT_KERNEL_RWX >>> select ARCH_HAS_STRICT_MODULE_RWX >>> + select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE >>> select ARCH_HAS_UBSAN_SANITIZE_ALL >>> select ARCH_HAS_ZONE_DEVICE if X86_64 >>> select ARCH_HAVE_NMI_SAFE_CMPXCHG >>> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h >>> index bdac19ab2488..6ce996a7c730 100644 >>> --- a/arch/x86/include/asm/processor.h >>> +++ b/arch/x86/include/asm/processor.h >>> @@ -706,6 +706,16 @@ static inline void sync_core(void) >>> #endif >>> } >>> >>> +/* >>> + * Ensure that a core serializing instruction is issued before returning >>> + * to user-mode. x86 implements return to user-space through sysexit and >>> + * sysretq, which are not core serializing. >>> + */ >>> +static inline void sync_core_before_usermode(void) >>> +{ >>> + sync_core(); >>> +} >> >> Make this if (!in_interrupt()) sync_core(); please. We can optimize >> it better later on. > > Sure, done. It will be part of the next version of that patch. Of course, using in_interrupt() from linux/interrupt.h from asm/processor.h is not such a good idea (circular dependency). Any recommendation on where to move that static inline on x86 ? Thanks, Mathieu > > Thanks! > > Mathieu > > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: Re: [RFC PATCH for 4.15 05/10] x86: Introduce sync_core_before_usermode Date: Fri, 10 Nov 2017 22:32:54 +0000 (UTC) Message-ID: <115800448.13060.1510353174125.JavaMail.zimbra@efficios.com> References: <20171110213717.12457-1-mathieu.desnoyers@efficios.com> <20171110213717.12457-6-mathieu.desnoyers@efficios.com> <1007217384.13056.1510352430448.JavaMail.zimbra@efficios.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1007217384.13056.1510352430448.JavaMail.zimbra@efficios.com> Sender: linux-arch-owner@vger.kernel.org To: Andy Lutomirski Cc: Boqun Feng , Peter Zijlstra , "Paul E. McKenney" , linux-kernel , linux-api , Andrew Hunter , maged michael , Avi Kivity , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Dave Watson , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrea Parri , "Russell King, ARM Linux" , Greg Hackmann , Will Deacon , David List-Id: linux-api@vger.kernel.org ----- On Nov 10, 2017, at 5:20 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > ----- On Nov 10, 2017, at 5:02 PM, Andy Lutomirski luto@kernel.org wrote: > >> On Fri, Nov 10, 2017 at 1:37 PM, Mathieu Desnoyers >> wrote: >>> Introduce an architecture function that ensures the current CPU >>> issues a core serializing instruction before returning to usermode. >>> >>> This is needed to fix an existing core serialization bug on >>> thread migration, and also needed by the membarrier "sync_core" command. >>> >>> Architectures defining the sync_core_before_usermode() static inline >>> need to define ARCH_HAS_SYNC_CORE_BEFORE_USERMODE. >>> >>> Signed-off-by: Mathieu Desnoyers >>> CC: Peter Zijlstra >>> CC: Andy Lutomirski >>> CC: Paul E. McKenney >>> CC: Boqun Feng >>> CC: Andrew Hunter >>> CC: Maged Michael >>> CC: Avi Kivity >>> CC: Benjamin Herrenschmidt >>> CC: Paul Mackerras >>> CC: Michael Ellerman >>> CC: Dave Watson >>> CC: Thomas Gleixner >>> CC: Ingo Molnar >>> CC: "H. Peter Anvin" >>> CC: Andrea Parri >>> CC: Russell King >>> CC: Greg Hackmann >>> CC: Will Deacon >>> CC: David Sehr >>> CC: Linus Torvalds >>> CC: x86@kernel.org >>> CC: linux-arch@vger.kernel.org >>> --- >>> arch/x86/Kconfig | 1 + >>> arch/x86/include/asm/processor.h | 10 ++++++++++ >>> include/linux/processor.h | 6 ++++++ >>> 3 files changed, 17 insertions(+) >>> >>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >>> index 01f78c1d40b5..54fbb8960d94 100644 >>> --- a/arch/x86/Kconfig >>> +++ b/arch/x86/Kconfig >>> @@ -62,6 +62,7 @@ config X86 >>> select ARCH_HAS_SG_CHAIN >>> select ARCH_HAS_STRICT_KERNEL_RWX >>> select ARCH_HAS_STRICT_MODULE_RWX >>> + select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE >>> select ARCH_HAS_UBSAN_SANITIZE_ALL >>> select ARCH_HAS_ZONE_DEVICE if X86_64 >>> select ARCH_HAVE_NMI_SAFE_CMPXCHG >>> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h >>> index bdac19ab2488..6ce996a7c730 100644 >>> --- a/arch/x86/include/asm/processor.h >>> +++ b/arch/x86/include/asm/processor.h >>> @@ -706,6 +706,16 @@ static inline void sync_core(void) >>> #endif >>> } >>> >>> +/* >>> + * Ensure that a core serializing instruction is issued before returning >>> + * to user-mode. x86 implements return to user-space through sysexit and >>> + * sysretq, which are not core serializing. >>> + */ >>> +static inline void sync_core_before_usermode(void) >>> +{ >>> + sync_core(); >>> +} >> >> Make this if (!in_interrupt()) sync_core(); please. We can optimize >> it better later on. > > Sure, done. It will be part of the next version of that patch. Of course, using in_interrupt() from linux/interrupt.h from asm/processor.h is not such a good idea (circular dependency). Any recommendation on where to move that static inline on x86 ? Thanks, Mathieu > > Thanks! > > Mathieu > > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com