Re: [PATCH 07/12] perf_events: add LBR software filter support forIntel X86

[Masami Hiramatsu]

(2011/10/10 15:09), Ingo Molnar wrote:
> 
> * Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx> wrote:
> 
>> (2011/10/07 20:21), Peter Zijlstra wrote:
>>> On Fri, 2011-10-07 at 13:18 +0200, Peter Zijlstra wrote:
>>>>> Yeah, depending on the depth of the LBR. But then what happens, you
>>>>> decode an instruction that is not what was executed. 
>>>>
>>>> Right, and Andi's concern is that this might cause our instruction
>>>> decoder to blow up, or worse. 
>>>
>>> That is, we have a fair confidence that its capable of correctly
>>> decoding correct streams, but I understood from Masami that they haven't
>>> actually tried feeding it crap.
>>
>> OK, I'll do hardening it.
> 
> Yes, that's a good idea. Could you perhaps add it to the existing 
> build time sanity test we do for the instruction decoder, to feed it 
> a sequence of /dev/urandom input or such?

Ah, nice. Maybe we need another test binary, since current one is
just ensuring the output of objdump and decoder is same.
anyway it's not so difficult if it feeds random binaries to
ensure the decoder doesn't access bad address.

Thank you,

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/