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: 35c51f8 ("perf cs-etm: Validate options after applying them")
Reviewed-by: Leo Yan <[email protected]>
Signed-off-by: James Clark <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/all/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: James-A-Clark

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;