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SubjectRe: [Patch 1/1] Introduce register_user_hbp_by_pid() and unregister_user_hbp_by_pid()
On Wed, Dec 30, 2009 at 11:28:39PM +0100, Frederic Weisbecker wrote:
> On Tue, Dec 22, 2009 at 12:16:31AM +0530, K.Prasad wrote:
> > On Fri, Dec 18, 2009 at 09:47:48PM +0100, Frederic Weisbecker wrote:
>
> > > And this function needs rcu too.
> > >
> > > I don't see any in-kernel user for this new feature.
> > > That would be required to integrate it.
> > >
> >
> > The proposed interfaces, as obvious, are mere wrappers over existing
> > (un)register_user_* interfaces, and don't do anything vastly different
> > in order to demonstrate them separately.
> >
> > I can get a sample kernel module ready - that consumes pid and user-space
> > address to track write accesses, if you prefer it.
>
>
> Ok. The code looks good and useful.
>
> But the usual philosophy in the kernel is to not add code
> that is left unused upstream. And samples don't substitute a user.
> I'm not sure this is a good idea to merge this.
>

Back to the old trick!...How about an ftrace plugin that accepts pid,
user-space address and memory access type and traces all the IP
addresses that caused access?

echo <pid>:<user_addr><access_type> > usym_trace_filter
echo 567:0x1234567:rw- > usym_trace_filter
Breakpoint IP
------------ ---------
567:0x1234567 0x0abcdef
I'm unsure if it sounds interesting at all, but I suspect it wouldn't be
as easy as above to gather the shown information through any existing
tools.

Thanks,
K.Prasad



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