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=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 24E78C4363A for ; Mon, 5 Oct 2020 19:14:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D7318208C3 for ; Mon, 5 Oct 2020 19:14:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725904AbgJETOG (ORCPT ); Mon, 5 Oct 2020 15:14:06 -0400 Received: from mga18.intel.com ([134.134.136.126]:51941 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725616AbgJETOG (ORCPT ); Mon, 5 Oct 2020 15:14:06 -0400 IronPort-SDR: 0Popd5/pSk4OR+5X7bcXDlpfJmGx/DH+CZI3SDgVLqjuvRHz+sckQF+SpzRdiFQ0uxN50yB/PQ 0auWBNGxaBqg== X-IronPort-AV: E=McAfee;i="6000,8403,9765"; a="151646159" X-IronPort-AV: E=Sophos;i="5.77,340,1596524400"; d="scan'208";a="151646159" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga106.jf.intel.com with ESMTP; 05 Oct 2020 12:07:58 -0700 IronPort-SDR: kdsXKpSKidRHOVCfk6kIHXFh+U6tZUg/+QO16UtMuVUULNg+Z9brYP4bU/VH7A2SaUhL7fdfdJ oVhj50NWXIcg== X-IronPort-AV: E=Sophos;i="5.77,340,1596524400"; d="scan'208";a="459867950" Received: from agluck-desk2.sc.intel.com (HELO agluck-desk2.amr.corp.intel.com) ([10.3.52.68]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2020 10:47:28 -0700 Date: Mon, 5 Oct 2020 10:47:14 -0700 From: "Luck, Tony" To: Borislav Petkov Cc: Youquan Song , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 6/7] x86/mce: Recover from poison found while copying from user space Message-ID: <20201005174714.GA30330@agluck-desk2.amr.corp.intel.com> References: <20200921113144.GD5901@zn.tnic> <20200930232611.15355-1-tony.luck@intel.com> <20200930232611.15355-7-tony.luck@intel.com> <20201005163247.GE21151@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201005163247.GE21151@zn.tnic> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 05, 2020 at 06:32:47PM +0200, Borislav Petkov wrote: > On Wed, Sep 30, 2020 at 04:26:10PM -0700, Tony Luck wrote: > > arch/x86/kernel/cpu/mce/core.c | 33 +++++++++++++++++++++------------ > > include/linux/sched.h | 2 ++ > > 2 files changed, 23 insertions(+), 12 deletions(-) > > Isn't that just simpler? Yes. A helper function avoids making the code a mess of if/else with subtle fall through cases. > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 4d2cf08820af..dc6c83aa2ec1 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -1261,6 +1261,21 @@ static void kill_me_maybe(struct callback_head *cb) > kill_me_now(cb); > } > > +static inline void queue_task_work(struct mce *m, int kill_it) Does it need to be "inline" though? I hope machine check processing is never in the critical code path for anyone! > +{ > + current->mce_addr = m->addr; > + current->mce_kflags = m->kflags; > + current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV); > + current->mce_whole_page = whole_page(m); > + > + if (kill_it) > + current->mce_kill_me.func = kill_me_now; > + else > + current->mce_kill_me.func = kill_me_maybe; > + > + task_work_add(current, ¤t->mce_kill_me, true); > +} > + > /* > * The actual machine check handler. This only handles real > * exceptions when something got corrupted coming in through int 18. > @@ -1402,13 +1417,8 @@ noinstr void do_machine_check(struct pt_regs *regs) > /* If this triggers there is no way to recover. Die hard. */ > BUG_ON(!on_thread_stack() || !user_mode(regs)); > > - current->mce_addr = m.addr; > - current->mce_ripv = !!(m.mcgstatus & MCG_STATUS_RIPV); > - current->mce_whole_page = whole_page(&m); > - current->mce_kill_me.func = kill_me_maybe; > - if (kill_it) > - current->mce_kill_me.func = kill_me_now; > - task_work_add(current, ¤t->mce_kill_me, true); > + queue_task_work(&m, kill_it); > + > } else { > /* > * Handle an MCE which has happened in kernel space but from > @@ -1423,6 +1433,9 @@ noinstr void do_machine_check(struct pt_regs *regs) > if (!fixup_exception(regs, X86_TRAP_MC, 0, 0)) > mce_panic("Failed kernel mode recovery", &m, msg); > } > + > + if (m.kflags & MCE_IN_KERNEL_COPYIN) > + queue_task_work(&m, kill_it); > } > out: > mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); -Tony