From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-120200-1516212645-2-13412288121631085649 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='com', MailFrom='org', XOriginatingCountry='CA' X-Spam-charsets: plain='utf-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: linux-api-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1516212643; b=sMfHaHeCgKh+xW7X5rsxmgyyGDUioSKaf43iHgJO5Do36Kl dJ8op+rAy4cx7VdRmR3w/NKT2IOjJc8Y4p5oaxkj2oV58P//9tw12Fub38zYf+M0 bhACc4G+rI7Sp3jn6M+fHKXv4KU+9jkm1GIkfpjl08kCS6hxKiFQM7ltW5o3Y1Mu 3144EsDkJqSVFOgElMyDfxphWUqg8ge5KiJUKzAb1dGE303xKS1vGenN/Z+2HF84 44oEey8k7YkgS1YnUJ+mRrLmHcZyx5gHdTsQK1pIrtswkxF/eFPK16k5za6rJJrs 9nEZpX/UUiAMc0Zo9Mi3EpIufXJAArARcBbZcbQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-type :content-transfer-encoding:sender:list-id; s=arctest; t= 1516212643; bh=TnmP/vHcqX7kH+mr/WCokmkpP3KODILuDJpZlaY2YeA=; b=q 6rnBwxpaFXb5Say6j18ETfR2rx1SdwaCKH//JBirGrIzXx9xyk2ZeZISpQ+Wc2xv X1df+a+BstM39A1r7cHFAWz9/+cSUnUJkFBl/FXGfzvG1nz8tog7t4xC0XOYRdOM jGjBlVcwLahELLmEbPLZbQzIG9FD/wmGHSwHqMz4UYlmOB0tZqnc8K+VUxYBFBL1 5HoRHqMBvIptYVWGVkW4hFZoHw2oTmFKIXuJTjS8hntR3yPuP9ueTYr1laUWUrAQ unuGRZ97oYcjny8ZvVLiANxEI7B+bFAMeMuuoplpRaI4mxZj00E15JNAZ8OukcbW lP4gI82IEJyOzPN6IQqjA== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=efficios.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=efficios.com header.result=pass header_is_org_domain=yes Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=efficios.com; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=linux-api-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=efficios.com header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752654AbeAQSKl (ORCPT ); Wed, 17 Jan 2018 13:10:41 -0500 Received: from mail.efficios.com ([167.114.142.141]:47672 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752268AbeAQSKk (ORCPT ); Wed, 17 Jan 2018 13:10:40 -0500 Date: Wed, 17 Jan 2018 18:10:36 +0000 (UTC) From: Mathieu Desnoyers To: Andy Lutomirski Cc: Ingo Molnar , Peter Zijlstra , Thomas Gleixner , linux-kernel , linux-api , "Paul E. McKenney" , Boqun Feng , Andrew Hunter , maged michael , Avi Kivity , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Dave Watson , "H. Peter Anvin" , Andrea Parri , "Russell King, ARM Linux" , Greg Hackmann , Will Deacon , David Sehr , Linus Torvalds , x86 , linux-arch Message-ID: <712464074.4666.1516212636860.JavaMail.zimbra@efficios.com> In-Reply-To: References: <20180117165458.13330-1-mathieu.desnoyers@efficios.com> <20180117165458.13330-8-mathieu.desnoyers@efficios.com> Subject: Re: [PATCH for 4.16 07/11] x86: Implement sync_core_before_usermode (v3) 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: Implement sync_core_before_usermode (v3) Thread-Index: 59lROjmLbZAQF6x/FpnI2Ub60LBxdA== Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: ----- On Jan 17, 2018, at 12:53 PM, Andy Lutomirski luto@kernel.org wrote: > On Wed, Jan 17, 2018 at 8:54 AM, Mathieu Desnoyers > wrote: >> Ensure that a core serializing instruction is issued before returning to >> user-mode. x86 implements return to user-space through sysexit, sysrel, >> and sysretq, which are not core serializing. >> >> Signed-off-by: Mathieu Desnoyers >> Reviewed-by: Thomas Gleixner >> 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: 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 >> --- >> Changes since v1: >> - Fix prototype of sync_core_before_usermode in generic code (missing >> return type). >> - Add linux/processor.h include to sched/core.c. >> - Add ARCH_HAS_SYNC_CORE_BEFORE_USERMODE to init/Kconfig. >> - Fix linux/processor.h ifdef to target >> CONFIG_ARCH_HAS_SYNC_CORE_BEFORE_USERMODE rather than >> ARCH_HAS_SYNC_CORE_BEFORE_USERMODE. >> - Move empty static inline in processor.h to generic patch. >> --- >> arch/x86/Kconfig | 1 + >> arch/x86/include/asm/processor.h | 10 ++++++++++ >> 2 files changed, 11 insertions(+) >> >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >> index 20da391b5f32..0b44c8dd0e95 100644 >> --- a/arch/x86/Kconfig >> +++ b/arch/x86/Kconfig >> @@ -61,6 +61,7 @@ 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 d3a67fba200a..3257d34dbb40 100644 >> --- a/arch/x86/include/asm/processor.h >> +++ b/arch/x86/include/asm/processor.h >> @@ -722,6 +722,16 @@ 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, >> + * sysrel, and sysretq, which are not core serializing. >> + */ >> +static inline void sync_core_before_usermode(void) >> +{ > > /* With PTI, we unconditionally serialize before running user code. */ > if (static_cpu_has(X86_FEATURE_PTI)) > return; One issue I'm facing with this change is header dependency: sync_core_before_usermode() is currently implemented in arch/x86/include/asm/processor.h, but arch/x86/include/asm/cpufeature.h is needed for static_cpu_has, and it happens to include asm/processor.h. I'm facing a similar issue for adding a (in_irq() || in_nmi()) check. Should we move sync_core_before_usermode() to a different header, and if so, any suggestion ? Thanks, Mathieu > >> + sync_core(); >> +} > > --Andy -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com