Re: Denial of denial of service

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From: Nicholas Clark
Subject: Re: Denial of denial of service
Date: 11:14 on 29 Jan 2007
On Mon, Jan 29, 2007 at 11:06:15AM +0000, Andy Armstrong wrote:
> On 29 Jan 2007, at 01:17, Martin Ebourne wrote:
> >Find me an example in ARM
> 
> Now you're talking :)
> 
> I was lying awake last night formulating a thesis that ARM26 is the  
> absolute pinnacle of instruction set design.

You're forgetting the 2**24 variants of the NOOP instruction.
Although whether this is software is doubtful, and therefore the on-topicness
here is doubtful too.

Oh, and I'm told that the fact that accessing the process mode bits *isn't*
a protected instruction is mildly hateful, as without this, you can't lie to
code about which CPU mode you're in. (If you can lie about the mode, and all
instructions for the privileged mode are themselves protected, then you
can run privilege code sandboxed in an unprivileged mode, and decide just
what it really gets to do, without it having the faintest idea of what's
going on.)

Nicholas Clark
There's stuff above here

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