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SubjectRe: disabling group leader perf_event
  On 09/06/2010 06:47 PM, Ingo Molnar wrote:
>> The actual language doesn't really matter.
> There are 3 basic categories:
> 1- Most (least abstract) specific code: a block of bytecode in the form
> of a simplified, executable, kernel-checked x86 machine code block -
> this is also the fastest form. [yes, this is actually possible.]

Do you then recompile it? x86 is quite unpleasant.

> 2- Least specific (most abstract) code: A subset/sideset of C - as it's
> the most kernel-developer-trustable/debuggable form.
> 3- Everything else little more than a dot on the spectrum between the
> first two points.
> I lean towards #2 - but #1 looks interesting too. #3 is distinctly
> uninteresting as it cannot be as fast as #1 and cannot be as convenient
> as #2.

Curious - how do you guarantee safety of #1 or even #2? Can you point
me to any research?

Everything I'm aware of is bytecode with explicit measures to prevent
forged pointers, but I admit I've spent no time on it. It's interesting
stuff, though.

I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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