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

[Masami Hiramatsu <mhiramat@redhat.com>]

Ingo Molnar wrote:
> * Masami Hiramatsu <mhiramat@redhat.com> 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@redhat.com