Messages in this thread |  | | | Date | Wed, 24 Feb 2010 08:41:13 -0500 | | From | Masami Hiramatsu <> | | Subject | Re: [PATCH -tip v10 0/9] kprobes: Kprobes jump optimization support |
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Masami Hiramatsu wrote: > Steven Rostedt wrote: >> On Thu, 2010-02-18 at 17:12 -0500, Masami Hiramatsu wrote: >> >>> This version of patch series uses text_poke_smp() which >>> update kernel text by stop_machine(). That is 'officially' >>> supported on Intel's processors. text_poke_smp() can't >>> be used for modifying NMI code, >> >> But it can be made to use with NMI code. If you look at what I did to >> allow ftrace to modify NMI code, it may be able to do the same thing. > > Yeah, I know. But basically, kprobes doesn't support probing NMI. > Maybe, it's possibly the next step. :)
I mean that it may be overkill for this series, because the kprobes itself doesn't support NMI. So I think it should be done by another series (for simplify patches).
BTW, now there are two candidates for NMI supported text_poke() on x86. AFAIK, those have following issues/features.
- text_poke_fixup() - Send IPI twice instead of kstop_machine. - Need a detour buffer if replacing code is not a jump. - Unofficial method for x86.
- generic ftrace_modify_code - Use kstop_machine and wait an NMI. - Temporarily clear the kernel text read-only flag entirely (can we use text_poke instead?)
Thank you,
-- Masami Hiramatsu e-mail: mhiramat@redhat.com
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