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Subject: Re: [PATCH 4/4] x86/jump-label: Show where and what was wrong on
 errors
From: Steven Rostedt <rostedt@goodmis.org>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>, Jason Baron <jbaron@akamai.com>
Date: Wed, 07 Aug 2013 13:33:06 -0400
In-Reply-To: <20130807172044.GC18272@pd.tnic>
References: <20130807164934.149920591@goodmis.org>
	 <20130807165114.147890467@goodmis.org> <20130807172044.GC18272@pd.tnic>
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On Wed, 2013-08-07 at 19:20 +0200, Borislav Petkov wrote:
>   
> > +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...")
> 
> ?

Because the patch replaced BUG().

> 
> Besides, BUG can be disabled in CONFIG_EXPERT.
> 

Right, and this code keeps the same logic as it was before. If it was
disabled by CONFIG_EXPERT, it stays disabled, but at least you get to
see a warning that your kernel may be corrupt now :-)

-- Steve