linux-kernel - Re: Partially Privileged Applications

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Date:	Sun, 10 Nov 2013 17:24:35 +0100
From:	Shahbaz Youssefi <shabbyx@...il.com>
To:	Richard Weinberger <richard.weinberger@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Partially Privileged Applications

Not sure if I understood you (or you understood me). We don't throw
away anything. Only difference would be instead of generating a trap
to call a function in the kernel, we can just call it and have the
hardware take care of privileges. The "trap way" is the one that
actually seems hacky! A hack proposed to fix the brain-dead processors
of twenty years ago.

As a bonus you would also have more control over what parts of a
driver actually get run in privileged mode.

Care to explain why you would call this a step backwards?

On Sun, Nov 10, 2013 at 5:18 PM, Richard Weinberger
<richard.weinberger@...il.com> wrote:
> On Sun, Nov 10, 2013 at 4:03 PM, Shahbaz Youssefi <shabbyx@...il.com> wrote:
>> Dear all,
>>
>> First, please CC replies to myself. Second, this is an RFC.
>>
>> I've been tampering with an idea for some time now and I've done some
>> research. Finally, I wrote it down here (a terrible place as it turned
>> out):
>>
>> http://shahbaz-youssefi.blogspot.it/2013/11/partially-privileged-applications.html
>>
>> and would like to know what you think. This idea requires an
>> improvement to the CPU architectures to allow unifying kernel and user
>> spaces and perform privileged instructions based on the location of
>> the instruction rather than a manually switched mode (or via traps).
>>
>> Please, do take a look at the link. I'm far from a kernel expert so
>> the idea may not be as rainbows and unicorns as it seems to me right
>> now. But it also may be. In that case, probably we need a push by
>> well-known people (i.e., Linus) to get the manufacturers to implement
>> the feature.
>>
>> At least from a developer's point of view, with this idea you could
>> gdb or even valgrind check the drivers in the very least with much
>> less chance of a kernel oops. How faster can you imagine debugging a
>> kernel module?
>
> So, we throw away 20 years of OS development and go back to hacky call
> gates? ;-)
>
>> Thanks,
>> An unfortunate soul who has to deal with buggy kernel modules
>> --
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>
>
>
> --
> Thanks,
> //richard
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