Re: [PATCH 0/4] powerpc: build out kprobes blacklist

["Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>]

On 2017/04/27 11:24AM, Masami Hiramatsu wrote:
> Hello Naveen,
> 
> On Tue, 25 Apr 2017 22:04:05 +0530
> "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> 
> > This is the second in the series of patches to build out an appropriate
> > kprobes blacklist. This series blacklists system_call() and functions
> > involved when handling the trap itself. Not everything is covered, but
> > this is the first set of functions that I have tested with. More
> > patches to follow once I expand my tests.
> 
> OK, btw, have you tested to put kprobes on these functions and
> saw kernel panic happened?

Thanks for the question! I re-checked and I just realized I hadn't 
tested the PAPR case (stolen time accounting). On testing, I just found 
that those functions are not a problem since they are only invoked when 
we are coming in from user-space and not when we take a trap in-kernel.  
I will re-spin patch 3/4. Other functions have been tested to cause 
issues with kprobes.

There are still a few more functions involved (especially with 
CONFIG_PREEMPT) where I couldn't reproduce an issue, so I haven't 
included those in this series.  I am continuing to test this further and 
will post subsequent patches once I work out which other functions are 
problematic.

> 
> > I have converted many labels into private -- these are labels that I
> > felt are not necessary to read stack traces. If any of those are
> > important to have, please let me know.
> 
> At least from the viewpoint of kprobe-blacklist macros, it seems
> good to me :)
> 
> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
> 
> for this series.
> 
> Thank you,

Thanks for the review!
- Naveen