perf intel-pt: Add support for decoding PSB+ only

A single q option decodes ip from only FUP/TIP packets. Make it so that
repeating the q option (i.e. qq) decodes only PSB+, getting ip if there
is a FUP packet within PSB+ (i.e. between PSB and PSBEND).

Example:

 $ perf record -e intel_pt//u grep -rI pudding drivers
 [ perf record: Woken up 52 times to write data ]
 [ perf record: Captured and wrote 57.870 MB perf.data ]
 $ time perf script --itrace=bi | wc -l
 58948289

 real    1m23.863s
 user    1m23.251s
 sys     0m7.452s
 $ time perf script --itrace=biq | wc -l
 3385694

 real    0m4.453s
 user    0m4.455s
 sys     0m0.328s
 $ time perf script --itrace=biqq | wc -l
 1883

 real    0m0.047s
 user    0m0.043s
 sys     0m0.009s

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200710151104.15137-13-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-intel-pt.txt

@@ -999,6 +999,21 @@ What *will* be decoded with the (single) q option:
 Note the q option does not specify what events will be synthesized e.g. the p
 option must be used also to show power events.
 
+Repeating the q option (double-q i.e. qq) results in even faster decoding and even
+less detail.  The decoder decodes only extended PSB (PSB+) packets, getting the
+instruction pointer if there is a FUP packet within PSB+ (i.e. between PSB and
+PSBEND).  Note PSB packets occur regularly in the trace based on the psb_period
+config term (refer config terms section).  There will be a FUP packet if the
+PSB+ occurs while control flow is being traced.
+
+What will *not* be decoded with the qq option:
+
+	- everything except instruction pointer associated with PSB packets
+
+What *will* be decoded with the qq option:
+
+	- instruction pointer associated with PSB packets
+
 
 dump option
 ~~~~~~~~~~~