kprobes problem

[Frank Ch. Eigler]

Hi -


On Sat, Mar 12, 2005 at 03:34:45PM +0000, Baruch Even wrote:
> [...]
> The ret code is at:
> c0386cbb:       5d                      pop    %ebp
> c0386cbc:       c3                      ret
> 
> If I put the kprobe at cbc it crashes, if I put it in cbb it works. [...]
> Is it impossible to put a kprobe on a ret instruction? [...]

I think you encountered a genuine kprobes bug.  This might be a known
limitation but I don't remember seeing it.  It may relate to the way
instructions are manually decoded for copying or single-stepping.
Would you mind helping out the debugging process by trying a few
things, like

- finding some other "ret"'s in the kernel, and trying kprobes there
- adding both pre- and post- handlers for the trial kprobes, and put
  printk's in there, to see which (if any) gets processed
- transcribing the oops message

Thank you.


- FChE
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