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Re: Kprobes Support for ARM arch

Hi All,

The attached patch addresses the branch instructions
check for ARM kprobes last week release and avoids 
unexpected crash when probe is placed for branch 
type instructions. If any one finds issues, please let 
me know.


----- Original Message -----
From: Ananth N Mavinakayanahalli <>
Date: Friday, January 12, 2007 11:02 am
Subject: Re: Kprobes Support for ARM arch

> On Thu, Jan 11, 2007 at 07:58:07PM +0500, wrote:
> Hi Madhvesh,
> > Hi All,
> > 
> > Recently we completed the kprobes support for ARM architecture
> > targetted at 2.6.16 kernel. I have uploaded these patches in the
> > below CELF wiki page along with few test programs.
> > This implementation is tested using 2.6.16-24 kernel for
> > OMAP5912 OSK reference platform.
> I am not familiar with the ARM architecture details... the following
> comments are from a quick glance at the patch.
> > The patch is available in the below CELF wiki page
> >
> > 
> > The patch can be downloaded directly from here
> > 
> > 
> > This implementation supports only kprobes and doesnot
> > support any other variants like jprobes, kretprobes etc.
> > Also it doesnot support branch/jump instructions probing.
> How are you ensuring that a kprobe register request on a branch/jump
> instruction fails? I don't see any profiling done to verify what the
> underlying instruction is.
> See arch_prepare_kprobe() from the powerpc port as to how we fail 
> kproberegistration on certain instructions.
> > I noticed some discussions regarding ARM kprobes in the
> > archive. We are open to suggestions and how this implementation can
> > be improved.
> Given that quite a bit of the kprobes code for any platform is
> architecture specific, its important that your code gets reviewed 
> by the
> ARM kernel gurus/maintainers, if you intend that the patch be included
> in the mainline Linux kernels.
> Also, you may want to port the patch to the latest kernel. There have
> been some interface changes:
> - kprobe modules are more portable with the addition of in-kernel 
> symbol  lookup.
> - The page fault case gets its own notifier so there isn't a 
> penalty paid
>  when kprobes aren't in use.
> Good work!
> Ananth

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