perf cs-etm: Fix contextid validation

Pre 5.11 kernels don't support 'contextid1' and 'contextid2' so
validation would be skipped. By adding an additional check for
'contextid', old kernels will still have validation done even though
contextid would either be contextid1 or contextid2.

Additionally now that it's possible to override options, an existing bug
in the validation is revealed. 'val' is overwritten by the contextid1
validation, and re-used for contextid2 validation causing it to always
fail. '!val || val != 0x4' is the same as 'val != 0x4' because 0 is also
!= 4, so that expression can be simplified and the temp variable not
overwritten.

Fixes: 35c51f83dd ("perf cs-etm: Validate options after applying them")
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/all/20230501073452.GA4660@leoy-yangtze.lan
Link: https://lore.kernel.org/r/20230504144822.1938717-1-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/arm/util/cs-etm.c

@@ -78,9 +78,9 @@ static int cs_etm_validate_context_id(struct auxtrace_record *itr,
 	char path[PATH_MAX];
 	int err;
 	u32 val;
-	u64 contextid =
-		evsel->core.attr.config &
-		(perf_pmu__format_bits(&cs_etm_pmu->format, "contextid1") |
+	u64 contextid = evsel->core.attr.config &
+		(perf_pmu__format_bits(&cs_etm_pmu->format, "contextid") |
+		 perf_pmu__format_bits(&cs_etm_pmu->format, "contextid1") |
 		 perf_pmu__format_bits(&cs_etm_pmu->format, "contextid2"));
 
 	if (!contextid)
@@ -114,8 +114,7 @@ static int cs_etm_validate_context_id(struct auxtrace_record *itr,
 		 *  0b00100 Maximum of 32-bit Context ID size.
 		 *  All other values are reserved.
 		 */
-		val = BMVAL(val, 5, 9);
-		if (!val || val != 0x4) {
+		if (BMVAL(val, 5, 9) != 0x4) {
 			pr_err("%s: CONTEXTIDR_EL1 isn't supported, disable with %s/contextid1=0/\n",
 			       CORESIGHT_ETM_PMU_NAME, CORESIGHT_ETM_PMU_NAME);
 			return -EINVAL;