Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() andgeneral cleaning of kprobe blacklist

[Masami Hiramatsu]

(2013/11/21 2:36), Frank Ch. Eigler wrote:
> Hi -
> 
>>> Does this new blacklist cover enough that the kernel now survives a 
>>> broadly wildcarded perf-probe, e.g. over e.g. all of its kallsyms?
>>
>> That's generally the purpose of the annotations - if it doesn't then 
>> that's a bug.
> 
> AFAIK, no kernel since kprobes was introduced has ever stood up to
> that test.  perf probe lacks the wildcarding powers of systemtap, so
> one needs to resort to something like:
> 
> # cat /proc/kallsyms | grep ' [tT] ' | while read addr type symbol; do
>    perf probe $symbol
> done
> 
> then wait for a few hours for that to finish. Then, or while the loop
> is still running, run
> 
> # perf record -e 'probe:*' -aR sleep 1
> 
> to take a kernel down.

Um, indeed, current blacklist is not perfect. As I reported in this
series, I've found 2 more patterns. I guess there still have some
others.

But anyway, I don't think it is good to fix all such bugs
in this series.
This is just the first step to do it. :)

Thank you,

-- 
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx


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