Re: [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer

From: Masami Hiramatsu
Date: Fri Apr 03 2009 - 12:56:21 EST


Ingo Molnar wrote:
> * Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
>
>> Hmm, I'd like to know actually kvm aims to emulate all kinds of
>> instructions. If so, I might find some bugs in x86_emulate.c.
>> However, I don't know all bugs. To find all of them, we have to
>> port x86_emulate.c to user-space, decode binaries with it, and
>> compare its output with another decoder, as Jim had done with
>> insn.c.
>>
>> https://www.redhat.com/archives/utrace-devel/2009-March/msg00031.html
>
> btw., i'd suggest we put a build time check for this into the kernel
> version as well. For example to decode the vmlinux via objdump, run
> it through your decoder as well and compare the results. Put under a
> CONFIG_DEBUG_X86_DECODER_TEST kind of (deault-off) build-time
> self-test.
>
> This would ensure that the kernel we are running is fully supported
> by the decoder - even as GCC/GAS starts using new instructions, etc.
>
> How does this sound to you?

Thanks! That is a good idea.
Jim, would you think you can port your script into kernel tree?

Thank you,

--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@xxxxxxxxxx

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