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Re: [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: Ingo Molnar <mingo at elte dot hu>, Jim Keniston <jkenisto at us dot ibm dot com>
- Cc: Avi Kivity <avi at redhat dot com>, "H. Peter Anvin" <hpa at zytor dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Steven Rostedt <rostedt at goodmis dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Andrew Morton <akpm at linux-foundation dot org>, Andi Kleen <andi at firstfloor dot org>, kvm at vger dot kernel dot org, systemtap-ml <systemtap at sources dot redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>, Vegard Nossum <vegard dot nossum at gmail dot com>
- Date: Fri, 03 Apr 2009 12:55:12 -0400
- Subject: Re: [PATCH -tip 0/6 V4] tracing: kprobe-based event tracer
- References: <49D4F4B5.9040107@redhat.com> <20090403112639.GC31399@elte.hu> <49D5F80B.7000305@redhat.com> <49D61B56.9020408@redhat.com> <20090403142325.GA14932@elte.hu>
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