Messages in this thread | | | Date | Thu, 29 Oct 2009 20:49:48 -0400 | From | Masami Hiramatsu <> | Subject | Re: [PATCH 0/3][RFC] tracing/kprobes: prevent jprobes from crashing function graph tracer |
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Steven Rostedt wrote: > On Thu, 2009-10-29 at 19:22 -0400, Masami Hiramatsu wrote: >> Steven Rostedt wrote: > >>>> I think we can skip those user handlers, because those are irregular >>>> functions and user can control (enable/disable) it. >>> >>> True, but it may be nice to still trace them. >> >> Hm, in that case, I think we can change jprobe_return() to call >> f-g-tracer's return handler if needed as below; >> --- >> static inline jprobe_return(void) >> { >> implicit_function_return(); /* This executes f-g-tracer prologue */ >> __jprobe_return(); /* This should be notraced */ >> } > > Hmm, That looks like it can be quite a hack. We don't know at that > moment if the handler has been traced or not. We can't always do the > function graph logic.
Ah, right. Perhaps, jprobe might be able to save the address of top of the stack and check if it has been modified to return_to_handler at jprobe_return().
But anyway, I think your patch can fix that too. :-)
Thank you,
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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