perf tools: Support pipeline stage cycles for powerpc

The pipeline stage cycles details can be recorded on powerpc from the
contents of Performance Monitor Unit (PMU) registers. On ISA v3.1
platform, sampling registers exposes the cycles spent in different
pipeline stages. Patch adds perf tools support to present two of the
cycle counter information along with memory latency (weight).

Re-use the field 'ins_lat' for storing the first pipeline stage cycle.
This is stored in 'var2_w' field of 'perf_sample_weight'.

Add a new field 'p_stage_cyc' to store the second pipeline stage cycle
which is stored in 'var3_w' field of perf_sample_weight.

Add new sort function 'Pipeline Stage Cycle' and include this in
default_mem_sort_order[]. This new sort function may be used to denote
some other pipeline stage in another architecture. So add this to list
of sort entries that can have dynamic header string.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Link: https://lore.kernel.org/r/1616425047-1666-5-git-send-email-atrajeev@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/event.h

@@ -147,6 +147,7 @@ struct perf_sample {
 	u8  cpumode;
 	u16 misc;
 	u16 ins_lat;
+	u16 p_stage_cyc;
 	bool no_hw_idx;		/* No hw_idx collected in branch_stack */
 	char insn[MAX_INSN];
 	void *raw_data;