From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:50060 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478AbbFCCnV (ORCPT ); Tue, 2 Jun 2015 22:43:21 -0400 Subject: Patch "powerpc/mce: fix off by one errors in mce event handling" has been added to the 4.0-stable tree To: dja@axtens.net, cl@linux.com, gregkh@linuxfoundation.org, mahesh@linux.vnet.ibm.com, mpe@ellerman.id.au Cc: , From: Date: Wed, 03 Jun 2015 11:43:05 +0900 Message-ID: <143329938530126@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled powerpc/mce: fix off by one errors in mce event handling to the 4.0-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-mce-fix-off-by-one-errors-in-mce-event-handling.patch and it can be found in the queue-4.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From ffb2d78eca08a1451137583d4e435aecfd6af809 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Tue, 12 May 2015 13:23:59 +1000 Subject: powerpc/mce: fix off by one errors in mce event handling From: Daniel Axtens commit ffb2d78eca08a1451137583d4e435aecfd6af809 upstream. Before 69111bac42f5 ("powerpc: Replace __get_cpu_var uses"), in save_mce_event, index got the value of mce_nest_count, and mce_nest_count was incremented *after* index was set. However, that patch changed the behaviour so that mce_nest count was incremented *before* setting index. This causes an off-by-one error, as get_mce_event sets index as mce_nest_count - 1 before reading mce_event. Thus get_mce_event reads bogus data, causing warnings like "Machine Check Exception, Unknown event version 0 !" and breaking MCEs handling. Restore the old behaviour and unbreak MCE handling by subtracting one from the newly incremented value. The same broken change occured in machine_check_queue_event (which set a queue read by machine_check_process_queued_event). Fix that too, unbreaking printing of MCE information. Fixes: 69111bac42f5 ("powerpc: Replace __get_cpu_var uses") CC: Mahesh Salgaonkar CC: Christoph Lameter Signed-off-by: Daniel Axtens Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/mce.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c @@ -73,7 +73,7 @@ void save_mce_event(struct pt_regs *regs uint64_t nip, uint64_t addr) { uint64_t srr1; - int index = __this_cpu_inc_return(mce_nest_count); + int index = __this_cpu_inc_return(mce_nest_count) - 1; struct machine_check_event *mce = this_cpu_ptr(&mce_event[index]); /* @@ -184,7 +184,7 @@ void machine_check_queue_event(void) if (!get_mce_event(&evt, MCE_EVENT_RELEASE)) return; - index = __this_cpu_inc_return(mce_queue_count); + index = __this_cpu_inc_return(mce_queue_count) - 1; /* If queue is full, just return for now. */ if (index >= MAX_MC_EVT) { __this_cpu_dec(mce_queue_count); Patches currently in stable-queue which might be from dja@axtens.net are queue-4.0/powerpc-mce-fix-off-by-one-errors-in-mce-event-handling.patch