linux-kernel - Re: Wanted: simple, safe x86 stack overflow detection

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Message-Id: <1173279863.3540.2.camel@laptopd505.fenrus.org>
Date:	Wed, 07 Mar 2007 07:04:23 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	Bill Irwin <bill.irwin@...cle.com>
Cc:	Hugh Dickins <hugh@...itas.com>, Chuck Ebbert <cebbert@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Wanted: simple, safe x86 stack overflow detection


> > just removing the if() and the explicit IRQ enabling already makes irqs no longer nest...
> 
> I can see why that would raise eyebrows. I can see getting bashed
> mercilessly with interrupt latency concerns as a result here. Can you
> suggest any defenses?


hardirq handlers are supposed to be fast. If they're slow the code
should (and generally is) using bottom halves/tasklets/softirqs. Combine
this with the fact that each new irq handler will start with a bunch of
cache misses, the latency added isn't generally that significant. In
addition, the cache miss thing makes the nesting suck a lot, it's faster
to batch the irqs in sequence.

-- 
if you want to mail me at work (you don't), use arjan (at) linux.intel.com
Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org

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