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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86F31C433EF for ; Thu, 9 Dec 2021 12:17:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237287AbhLIMUk (ORCPT ); Thu, 9 Dec 2021 07:20:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229777AbhLIMUi (ORCPT ); Thu, 9 Dec 2021 07:20:38 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A53DCC061746 for ; Thu, 9 Dec 2021 04:17:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Jq3xq/nvjt8oiQvE+CsLb1XjZN9u+9za66Ekyj2kiFw=; b=JFwR2ar6LXupuYTiL18OZ57ftZ GYNwiFddouK7DRpOOORVqlBcrE/95mf5znZhYwVSF5J06jPSR5Vylc0XIgCAhtsYZKFUWQQfXTM8d teo1/Pzc2JYRP1dckaZzZJ2Ix8J+fsApqLfHv0VOiqHRM9cBpKZt49RRXzpuag+0HimlDJhE6V6RW GcWEovX4keIffubrguy0w/94+Jzzs0tQOhGacX22Ax/3N0dbEvKO1LRy7c1kTGI6QUmQ60mBTIoXB ZuWqZ6JK07jf27pUzdBuIuNFZ6dirYAo0E9H/6Hj1ApSxghD2L8OFl672gY7/90gAnmuDDrkx8HX1 mSCBk3Rg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mvIM4-009Kfy-Ab; Thu, 09 Dec 2021 12:16:57 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 44501300079; Thu, 9 Dec 2021 13:16:56 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2D9C52BB99CBE; Thu, 9 Dec 2021 13:16:56 +0100 (CET) Date: Thu, 9 Dec 2021 13:16:56 +0100 From: Peter Zijlstra To: Borislav Petkov Cc: Tony Luck , X86 ML , LKML Subject: Re: [PATCH v1 04/12] x86/mce: Remove noinstr annotation from mce_setup() Message-ID: References: <20211208111343.8130-1-bp@alien8.de> <20211208111343.8130-5-bp@alien8.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211208111343.8130-5-bp@alien8.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 08, 2021 at 12:13:35PM +0100, Borislav Petkov wrote: > From: Borislav Petkov > > Instead, sandwitch around the call which is done in noinstr context and > mark the caller - mce_gather_info() - as noinstr. > > Signed-off-by: Borislav Petkov > --- > arch/x86/kernel/cpu/mce/core.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 87a277fc80b4..f61f14faa532 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -127,7 +127,7 @@ static struct irq_work mce_irq_work; > BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain); > > /* Do initial initialization of a struct mce */ > -noinstr void mce_setup(struct mce *m) > +void mce_setup(struct mce *m) > { > memset(m, 0, sizeof(struct mce)); > m->cpu = m->extcpu = smp_processor_id(); > @@ -430,9 +430,15 @@ static noinstr void mce_wrmsrl(u32 msr, u64 v) > * check into our "mce" struct so that we can use it later to assess > * the severity of the problem as we read per-bank specific details. > */ > -static inline void mce_gather_info(struct mce *m, struct pt_regs *regs) > +static noinstr void mce_gather_info(struct mce *m, struct pt_regs *regs) > { > + /* > + * Enable instrumentation around mce_setup() which calls external > + * facilities. Yeah, that's what it does; but *why* is that correct? I'm thinking we're well past the exception entry code and are only using noinstr as a means to limit the amount of code in the MCE handler? > + */ > + instrumentation_begin(); > mce_setup(m); > + instrumentation_end(); > > m->mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); > if (regs) { > -- > 2.29.2 >