perf script: Add generic perl handler to process events

The current perf scripting facility only supports tracepoints. This
patch implements a generic perl handler to support other events than
tracepoints too.

This patch introduces a function process_event() that is called by perf
for each sample. The function is called with byte streams as arguments
containing information about the event, its attributes, the sample and
raw data. Perl's unpack() function can easily be used for byte decoding.
The following is the default implementation for process_event() that can
also be generated with perf script:

 # Packed byte string args of process_event():
 #
 # $event:       union perf_event        util/event.h
 # $attr:        struct perf_event_attr  linux/perf_event.h
 # $sample:      struct perf_sample      util/event.h
 # $raw_data:    perf_sample->raw_data   util/event.h

 sub process_event
 {
         my ($event, $attr, $sample, $raw_data) = @_;

         my @event       = unpack("LSS", $event);
         my @attr        = unpack("LLQQQQQLLQQ", $attr);
         my @sample      = unpack("QLLQQQQQLL", $sample);
         my @raw_data    = unpack("C*", $raw_data);

         use Data::Dumper;
         print Dumper \@event, \@attr, \@sample, \@raw_data;
 }

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323969824-9711-4-git-send-email-robert.richter@amd.com


Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>