Kprobes stress test prototype

[Ananth N Mavinakayanahalli]

On Fri, Jun 26, 2009 at 02:33:04PM -0400, Masami Hiramatsu wrote:
> Hi,
> 
> Here is a script of kprobes stress test which uses
> kprobes-ftrace engine. Currently, this doesn't use any
> benchmarks for making a load.
> Any updates, comments, and reports are welcome!
> 
> On KVM/x86-64, I've found some symbols must be marked
> as __kprobes or blacklisted by using this script.
> 
> <always system hang up>
> p irq_return
> p start_critical_timing
> p time_hardirqs_off
> p bad_address
> p trace_hardirqs_off_thunk
> p restore
> 
> <not always, but potentially dangerous>
> p start_critical_timings
> p stop_critical_timing
> p trace_hardirqs_on_thunk
> p restore_norax
> 
> (I've encountered other odd memory corruptions too.
>  However, I couldn't identify the reason, it might be a bug
>  in kprobes or kvm.)
> 
> Basic usage is very simple.
> Of course, this needs kprobes-ftrace engine patchset which
> I posted to lkml (http://lkml.org/lkml/2009/6/1/461).
> 
> 1. Make a working area and put the script;
>  $ mkdir stest/
>  $ cp kprobestest stest/
> 
> 2. Run it.
>  $ cd stest/
>  $ ./kprobestest run
> 
> 3. If kernel gets trouble, reboot it and run again.
>  $ cd stest/
>  $ ./kprobestest run
> 
> 4. Repeat it, until all symbols are tested.

Excellent!

> First, the test lists up all symbols in ".text" section, except
> ".text.kprobes"(*) and breaks it into sub-lists. Initially, each
> sub-lists has 64 symbols and are stored into "gray" dir.
> The test passes each sub-list to kprobes-ftrace engine and makes
> a load(currently, just sleep 2secs).

Wouldn't this be a very simplistic scenario? There could be cases where
the probes inserted were never hit during the 2sec interval, but may
potentially still be dangerous.

Ananth