From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757343Ab3HGRUx (ORCPT ); Wed, 7 Aug 2013 13:20:53 -0400 Received: from mail.skyhub.de ([78.46.96.112]:58987 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757261Ab3HGRUq (ORCPT ); Wed, 7 Aug 2013 13:20:46 -0400 Date: Wed, 7 Aug 2013 19:20:44 +0200 From: Borislav Petkov To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" , Linus Torvalds , Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Jason Baron Subject: Re: [PATCH 4/4] x86/jump-label: Show where and what was wrong on errors Message-ID: <20130807172044.GC18272@pd.tnic> References: <20130807164934.149920591@goodmis.org> <20130807165114.147890467@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20130807165114.147890467@goodmis.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 07, 2013 at 12:49:38PM -0400, Steven Rostedt wrote: > From: Steven Rostedt > > When modifying text sections for jump labels, a paranoid check is > performed. If the check fails, the system "bugs". But why it failed > is not shown. > > The BUG_ON()s in the jump label update code is replaced with bug_at(ip). > This is a function that will show what pointer failed, and what was > at the location of the failure that made jump label panic. > > Signed-off-by: Steven Rostedt > --- > arch/x86/kernel/jump_label.c | 21 ++++++++++++++++++--- > 1 file changed, 18 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c > index 24cf2b2..912a528 100644 > --- a/arch/x86/kernel/jump_label.c > +++ b/arch/x86/kernel/jump_label.c > @@ -24,6 +24,18 @@ union jump_code_union { > } __attribute__((packed)); > }; > > +static void bug_at(unsigned char *ip, int line) > +{ > + /* > + * The location is not an op that we were expecting. > + * Something went wrong. Crash the box, as something could be > + * corrupting the kernel. > + */ > + pr_warning("Unexpected op at %pS [%p] (%02x %02x %02x %02x %02x) %s:%d\n", > + ip, ip, ip[0], ip[1], ip[2], ip[3], ip[4], __FILE__, line); > + BUG(); Why not simply panic("Unexpected...") ? Besides, BUG can be disabled in CONFIG_EXPERT. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. --