perf stat: Fix L2 Topdown metrics disappear for raw events

In perf/Documentation/perf-stat.txt, for "--td-level" the default "0" means
the max level that the current hardware support.

So we need initialize the stat_config.topdown_level to TOPDOWN_MAX_LEVEL
when “--td-level=0” or no “--td-level” option. Otherwise, for the
hardware with a max level is 2, the 2nd level metrics disappear for raw
events in this case.

The issue cannot be observed for the perf stat default or "--topdown"
options. This commit fixes the raw events issue and removes the
duplicated code for the perf stat default.

Before:

# ./perf stat -e "cpu-clock,context-switches,cpu-migrations,page-faults,instructions,cycles,ref-cycles,branches,branch-misses,{slots,topdown-retiring,topdown-bad-spec,topdown-fe-bound,topdown-be-bound,topdown-heavy-ops,topdown-br-mispredict,topdown-fetch-lat,topdown-mem-bound}" sleep 1

Performance counter stats for 'sleep 1':

1.03 msec cpu-clock # 0.001 CPUs utilized
1 context-switches # 966.216 /sec
0 cpu-migrations # 0.000 /sec
60 page-faults # 57.973 K/sec
1,132,112 instructions # 1.41 insn per cycle
803,872 cycles # 0.777 GHz
1,909,120 ref-cycles # 1.845 G/sec
236,634 branches # 228.640 M/sec
6,367 branch-misses # 2.69% of all branches
4,823,232 slots # 4.660 G/sec
1,210,536 topdown-retiring # 25.1% Retiring
699,841 topdown-bad-spec # 14.5% Bad Speculation
1,777,975 topdown-fe-bound # 36.9% Frontend Bound
1,134,878 topdown-be-bound # 23.5% Backend Bound
189,146 topdown-heavy-ops # 182.756 M/sec
662,012 topdown-br-mispredict # 639.647 M/sec
1,097,048 topdown-fetch-lat # 1.060 G/sec
416,121 topdown-mem-bound # 402.063 M/sec

1.002423690 seconds time elapsed

0.002494000 seconds user
0.000000000 seconds sys

After:

# ./perf stat -e "cpu-clock,context-switches,cpu-migrations,page-faults,instructions,cycles,ref-cycles,branches,branch-misses,{slots,topdown-retiring,topdown-bad-spec,topdown-fe-bound,topdown-be-bound,topdown-heavy-ops,topdown-br-mispredict,topdown-fetch-lat,topdown-mem-bound}" sleep 1

Performance counter stats for 'sleep 1':

1.13 msec cpu-clock # 0.001 CPUs utilized
1 context-switches # 882.128 /sec
0 cpu-migrations # 0.000 /sec
61 page-faults # 53.810 K/sec
1,137,612 instructions # 1.29 insn per cycle
881,477 cycles # 0.778 GHz
2,093,496 ref-cycles # 1.847 G/sec
236,356 branches # 208.496 M/sec
7,090 branch-misses # 3.00% of all branches
5,288,862 slots # 4.665 G/sec
1,223,697 topdown-retiring # 23.1% Retiring
767,403 topdown-bad-spec # 14.5% Bad Speculation
2,053,322 topdown-fe-bound # 38.8% Frontend Bound
1,244,438 topdown-be-bound # 23.5% Backend Bound
186,665 topdown-heavy-ops # 3.5% Heavy Operations # 19.6% Light Operations
725,922 topdown-br-mispredict # 13.7% Branch Mispredict # 0.8% Machine Clears
1,327,400 topdown-fetch-lat # 25.1% Fetch Latency # 13.7% Fetch Bandwidth
497,775 topdown-mem-bound # 9.4% Memory Bound # 14.1% Core Bound

1.002701530 seconds time elapsed

0.002744000 seconds user
0.000000000 seconds sys

Fixes: 63e39aa6ae103451 ("perf stat: Support L2 Topdown events")
Reviewed-by: Kan Liang <[e-mail]>
Signed-off-by: Xing Zhengjun <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-stat.c

···
 		free(str);
 	}
 
+	if (!stat_config.topdown_level)
+		stat_config.topdown_level = TOPDOWN_MAX_LEVEL;
+
 	if (!evsel_list->core.nr_entries) {
 		if (target__has_cpu(&target))
 			default_attrs0[0].config = PERF_COUNT_SW_CPU_CLOCK;
···
 		}
 		if (evlist__add_default_attrs(evsel_list, default_attrs1) < 0)
 			return -1;
-
-		stat_config.topdown_level = TOPDOWN_MAX_LEVEL;
 		/* Platform specific attrs */
 		if (evlist__add_default_attrs(evsel_list, default_null_attrs) < 0)
 			return -1;