Messages in this thread | | | Date | Fri, 18 Feb 2011 00:34:43 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC][PATCH 0/4] ftrace: Use -mfentry when supported (this is for x86_64 right now) |
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(2011/02/17 22:18), Steven Rostedt wrote: > On Thu, 2011-02-17 at 21:37 +0900, Masami Hiramatsu wrote: > >> Oops! with this change, current kprobes might not be able to probe >> the entry of functions, because that is always reserved by ftrace! >> I think we need to have some new interface for replacing each other >> safely... > > Good point. I suspect that this wont be ready till .40 anyway. When I > get a chance to work more an this, I'll also include patches where if > -mfentry is activated kprobes will just hook to the mcount caller > instead. Or ftrace itself :)
Ah, that's a good idea! :) it could be done without -mfentry too. But is that possible to modify just one mcount entry? I also worry about the latency of enabling/disabling one entry.
BTW, without dynamic ftrace (no code modifying), I think we don't need to reserve mcount code, because no one modifies it.
> > I'm also working on making the function tracer a bit more flexible. That > is, to let multiple clients control the dynamic trace instead of just > one big global one.
Nice!
-- Masami HIRAMATSU 2nd Dept. Linux Technology Center Hitachi, Ltd., Systems Development Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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