From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [PATCH v3 03/22] x86: Replace ist_enter() with nmi_enter() Date: Thu, 20 Feb 2020 11:54:39 +0100 Message-ID: <20200220105439.GA507@zn.tnic> References: <20200219144724.800607165@infradead.org> <20200219150744.547288232@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from mail.skyhub.de ([5.9.137.197]:34572 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726501AbgBTKyt (ORCPT ); Thu, 20 Feb 2020 05:54:49 -0500 Content-Disposition: inline In-Reply-To: <20200219150744.547288232@infradead.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, luto@kernel.org, tony.luck@intel.com, frederic@kernel.org, dan.carpenter@oracle.com, mhiramat@kernel.org On Wed, Feb 19, 2020 at 03:47:27PM +0100, Peter Zijlstra wrote: > @@ -1220,7 +1220,7 @@ static void mce_kill_me_maybe(struct cal > * MCE broadcast. However some CPUs might be broken beyond repair, > * so be always careful when synchronizing with others. > */ > -void do_machine_check(struct pt_regs *regs, long error_code) > +notrace void do_machine_check(struct pt_regs *regs, long error_code) Is there a convention where the notrace marker should come in the function signature? I see all possible combinations while grepping... > { > DECLARE_BITMAP(valid_banks, MAX_NR_BANKS); > DECLARE_BITMAP(toclear, MAX_NR_BANKS); > @@ -1254,10 +1254,10 @@ void do_machine_check(struct pt_regs *re > */ > int lmce = 1; > > - if (__mc_check_crashing_cpu(cpu)) > - return; > + nmi_enter(); > > - ist_enter(regs); > + if (__mc_check_crashing_cpu(cpu)) > + goto out; > > this_cpu_inc(mce_exception_count); > Should that __mc_check_crashing_cpu() happen before nmi_enter? The function is doing only a bunch of checks and clearing MSRs for bystander CPUs... > @@ -1346,7 +1346,7 @@ void do_machine_check(struct pt_regs *re > sync_core(); > > if (worst != MCE_AR_SEVERITY && !kill_it) > - goto out_ist; > + goto out; > > /* Fault was in user mode and we need to take some action */ > if ((m.cs & 3) == 3) { > @@ -1362,10 +1362,11 @@ void do_machine_check(struct pt_regs *re > mce_panic("Failed kernel mode recovery", &m, msg); > } > > -out_ist: > - ist_exit(regs); > +out: > + nmi_exit(); > } > EXPORT_SYMBOL_GPL(do_machine_check); > +NOKPROBE_SYMBOL(do_machine_check); Yah, that's a good idea regardless. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette