Re: [PATCH -tip v4 0/6] kprobes: introduce NOKPROBE_SYMBOL() andfixes crash bugs

From: Ingo Molnar
Date: Thu Dec 05 2013 - 05:21:39 EST



* Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx> wrote:

> > So we need both a maintainable and a sane/safe solution, and I'd
> > like to apply the whole thing at once and be at ease that the
> > solution is round. We should have done this years ago.
>
> For the safeness of kprobes, I have an idea; introduce a whitelist
> for dynamic events. AFAICS, the biggest unstable issue of kprobes
> comes from putting *many* probes on the functions called from
> tracers.

If the number of 'noprobe' annotations is expected to explode then
maybe another approach should be considered.

For example in perf we detect recursion. Could kprobes do that and
detect hitting a probe while running kprobes code, and ignore it [do
an early return]?

That way most of the annotations could be removed and kprobes would
become inherently safe. Is there any complication I'm missing?

Thanks,

Ingo
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