linux-kernel - Re: [PATCH] x86: remove unneeded endless loop in BUG()

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Date:	Thu, 19 Feb 2009 11:53:30 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Petr Tesarik <ptesarik@...e.cz>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: remove unneeded endless loop in BUG()

Ingo Molnar wrote:
> 
> the problem is that the DO_BUG() will generate the u2d 
> instruction into a random place where GCC puts it. It certainly 
> wont be in the place where the __bug_table logic above expects 
> it.
> 
> The result will be cryptic crashes instead of a clean BUG 
> message assert.
> 

For that to happen, it would have to move the asm volatile relative to 
the __builtin_trap(), which seems slightly unlikely -- are there any 
cases at which this has been known to happen, or is that conjecture on 
your part?

It would be more of a "right thing" to do this with a label on the 
__builtin_trap(), but the problem with that labels have function scope 
even if they occur inside a block.

	-hpa

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