Re: [PATCH 1/2] perf: Pass appropriate frame pointer to dump_trace()

[Frederic Weisbecker <fweisbec@gmail.com>]

On Thu, Dec 31, 2009 at 05:53:02AM +0100, Frederic Weisbecker wrote:
> Pass the frame pointer from the regs of the interrupted path
> to dump_trace() while processing the stack trace.
> 
> Currently, dump_trace() takes the current bp and starts the
> callchain from dump_trace() itself. This is wasteful because
> we need to walk through the entire NMI/DEBUG stack before
> retrieving the interrupted point.
> 
> We can fix that by just using the frame pointer from the captured
> regs. It points exactly where we want to start.



BTW, another effect of this patch: we didn't have the
nmi/debug stack frame filtering in x86-32. So the callchains
were polluted by the perf_callchain path, do_debug and so
on...

After this patch we don't need this filtering anymore
as the nmi/debug frames are zapped. It becomes clean
like in x86-64.