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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F257C43441 for ; Thu, 22 Nov 2018 12:26:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4FEA820684 for ; Thu, 22 Nov 2018 12:26:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="GKJK6TOz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4FEA820684 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395043AbeKVXF4 (ORCPT ); Thu, 22 Nov 2018 18:05:56 -0500 Received: from mail.skyhub.de ([5.9.137.197]:55660 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394865AbeKVXFz (ORCPT ); Thu, 22 Nov 2018 18:05:55 -0500 Received: from zn.tnic (p200300EC2BDC9100898E5A1DF8FAB135.dip0.t-ipconnect.de [IPv6:2003:ec:2bdc:9100:898e:5a1d:f8fa:b135]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 9622B1EC06CA; Thu, 22 Nov 2018 13:26:44 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1542889604; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=2nkS/vyfMpcXqPrRDlywSEwnWD2aQO5tYYcJsd0LxZg=; b=GKJK6TOzv6XPBTNqnHlaHEEUu2NKm0cIORN12NVsdaViYtcC4u9anDG3M+ZXcMyxRmgDqZ oYTQpVO9wN1KnaCa2P082cgOSsQyBvXbwAl0PC4A9AcCnQ8slqaTQ0PCNoWBVxhO3XKHKB R/NVvrlZeFpNCG993o6mWAqsDFiW+H8= Date: Thu, 22 Nov 2018 13:26:38 +0100 From: Borislav Petkov To: Thomas Gleixner Cc: LKML , x86@kernel.org, Peter Zijlstra , Andy Lutomirski , Linus Torvalds , Jiri Kosina , Tom Lendacky , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , Waiman Long , Greg KH , Dave Stewart , Kees Cook , Tim Chen Subject: Re: [patch 22/24] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Message-ID: <20181122122638.GC10365@zn.tnic> References: <20181121201430.559770965@linutronix.de> <20181121201724.414692525@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181121201724.414692525@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 21, 2018 at 09:14:52PM +0100, Thomas Gleixner wrote: > From: Tim Chen > > Add the PR_SPEC_INDIR_BRANCH option for the PR_GET_SPECULATION_CTRL and > PR_SET_SPECULATION_CTRL prctls to allow fine grained per task control of > indirect branch speculation via STIBP. > > Invocations: > Check indirect branch speculation status with > - prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_INDIR_BRANCH, 0, 0, 0); > > Enable indirect branch speculation with > - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIR_BRANCH, PR_SPEC_ENABLE, 0, 0); > > Disable indirect branch speculation with > - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIR_BRANCH, PR_SPEC_DISABLE, 0, 0); > > Force disable indirect branch speculation with > - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIR_BRANCH, PR_SPEC_FORCE_DISABLE, 0, 0); > > See Documentation/userspace-api/spec_ctrl.rst. > > Signed-off-by: Tim Chen > Signed-off-by: Thomas Gleixner > > --- > Documentation/userspace-api/spec_ctrl.rst | 9 +++ > arch/x86/include/asm/nospec-branch.h | 1 > arch/x86/kernel/cpu/bugs.c | 71 ++++++++++++++++++++++++++++++ > include/linux/sched.h | 9 +++ > include/uapi/linux/prctl.h | 1 > tools/include/uapi/linux/prctl.h | 1 > 6 files changed, 92 insertions(+) > @@ -753,12 +755,56 @@ static int ssb_prctl_set(struct task_str > return 0; > } > > +static int indir_branch_prctl_set(struct task_struct *task, unsigned long ctrl) > +{ > + switch (ctrl) { > + case PR_SPEC_ENABLE: > + if (spectre_v2_app2app == SPECTRE_V2_APP2APP_NONE) > + return 0; > + /* > + * Indirect branch speculation is always disabled in strict > + * mode. > + */ > + if (spectre_v2_app2app == SPECTRE_V2_APP2APP_STRICT) > + return -EPERM; > + task_clear_spec_indir_branch_disable(task); > + task_update_spec_tif(task, TIF_SPEC_IB, false); > + break; > + case PR_SPEC_DISABLE: > + /* > + * Indirect branch speculation is always allowed when > + * mitigation is force disabled. > + */ > + if (spectre_v2_app2app == SPECTRE_V2_APP2APP_NONE) > + return -EPERM; > + if (spectre_v2_app2app == SPECTRE_V2_APP2APP_STRICT) > + return 0; > + task_set_spec_indir_branch_disable(task); > + task_update_spec_tif(task, TIF_SPEC_IB, true); > + break; > + case PR_SPEC_FORCE_DISABLE: > + if (spectre_v2_app2app == SPECTRE_V2_APP2APP_NONE) > + return -EPERM; > + if (spectre_v2_app2app == SPECTRE_V2_APP2APP_STRICT) > + return 0; > + task_set_spec_indir_branch_disable(task); > + task_set_spec_indir_branch_force_disable(task); > + task_update_spec_tif(task, TIF_SPEC_IB, true); > + break; > + default: > + return -ERANGE; > + } > + return 0; > +} Perhaps merge the two DISABLE branches to make it obvious what the difference between them is: diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 6eac074e3935..28cece3a067b 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -769,7 +769,9 @@ static int indir_branch_prctl_set(struct task_struct *task, unsigned long ctrl) task_clear_spec_indir_branch_disable(task); task_update_spec_tif(task, TIF_SPEC_IB, false); break; + case PR_SPEC_DISABLE: + case PR_SPEC_FORCE_DISABLE: /* * Indirect branch speculation is always allowed when * mitigation is force disabled. @@ -780,16 +782,11 @@ static int indir_branch_prctl_set(struct task_struct *task, unsigned long ctrl) return 0; task_set_spec_indir_branch_disable(task); task_update_spec_tif(task, TIF_SPEC_IB, true); + + if (ctrl == PR_SPEC_FORCE_DISABLE) + task_set_spec_indir_branch_force_disable(task); break; - case PR_SPEC_FORCE_DISABLE: - if (spectre_v2_app2app == SPECTRE_V2_APP2APP_NONE) - return -EPERM; - if (spectre_v2_app2app == SPECTRE_V2_APP2APP_STRICT) - return 0; - task_set_spec_indir_branch_disable(task); - task_set_spec_indir_branch_force_disable(task); - task_update_spec_tif(task, TIF_SPEC_IB, true); - break; + default: return -ERANGE; } > @@ -1453,6 +1453,8 @@ static inline bool is_percpu_thread(void > #define PFA_SPREAD_SLAB 2 /* Spread some slab caches over cpuset */ > #define PFA_SPEC_SSB_DISABLE 3 /* Speculative Store Bypass disabled */ > #define PFA_SPEC_SSB_FORCE_DISABLE 4 /* Speculative Store Bypass force disabled*/ > +#define PFA_SPEC_INDIR_BRANCH_DISABLE 5 /* Indirect branch speculation restricted */ > +#define PFA_SPEC_INDIR_BRANCH_FORCE_DISABLE 6 /* Indirect branch speculation permanentely restricted */ permanently -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.