[PATCH] perf test: Fix perf test 11 hwmon endianess issue

Thomas Richter
2025-01-31T11:24:23Z

perf test 11 hwmon fails on s390 with this error

# ./perf test -Fv 11
--- start ---
---- end ----
11.1: Basic parsing test : Ok
--- start ---
Testing 'temp_test_hwmon_event1'
Using CPUID IBM,3931,704,A01,3.7,002f
temp_test_hwmon_event1 -> hwmon_a_test_hwmon_pmu/temp_test_hwmon_event1/
FAILED tests/hwmon_pmu.c:189 Unexpected config for
'temp_test_hwmon_event1', 292470092988416 != 655361
---- end ----
11.2: Parsing without PMU name : FAILED!
--- start ---
Testing 'hwmon_a_test_hwmon_pmu/temp_test_hwmon_event1/'
FAILED tests/hwmon_pmu.c:189 Unexpected config for
'hwmon_a_test_hwmon_pmu/temp_test_hwmon_event1/',
292470092988416 != 655361
---- end ----
11.3: Parsing with PMU name : FAILED!
#

The root cause is in member test_event::config which is initialized
to 0xA0001 or 655361. During event parsing a long list event parsing
functions are called and end up with this gdb call stack:

#0 hwmon_pmu__config_term (hwm=0x168dfd0, attr=0x3ffffff5ee8,
term=0x168db60, err=0x3ffffff81c8) at util/hwmon_pmu.c:623
#1 hwmon_pmu__config_terms (pmu=0x168dfd0, attr=0x3ffffff5ee8,
terms=0x3ffffff5ea8, err=0x3ffffff81c8) at util/hwmon_pmu.c:662
#2 0x00000000012f870c in perf_pmu__config_terms (pmu=0x168dfd0,
attr=0x3ffffff5ee8, terms=0x3ffffff5ea8, zero=false,
apply_hardcoded=false, err=0x3ffffff81c8) at util/pmu.c:1519
#3 0x00000000012f88a4 in perf_pmu__config (pmu=0x168dfd0, attr=0x3ffffff5ee8,
head_terms=0x3ffffff5ea8, apply_hardcoded=false, err=0x3ffffff81c8)
at util/pmu.c:1545
#4 0x00000000012680c4 in parse_events_add_pmu (parse_state=0x3ffffff7fb8,
list=0x168dc00, pmu=0x168dfd0, const_parsed_terms=0x3ffffff6090,
auto_merge_stats=true, alternate_hw_config=10)
at util/parse-events.c:1508
#5 0x00000000012684c6 in parse_events_multi_pmu_add (parse_state=0x3ffffff7fb8,
event_name=0x168ec10 "temp_test_hwmon_event1", hw_config=10,
const_parsed_terms=0x0, listp=0x3ffffff6230, loc_=0x3ffffff70e0)
at util/parse-events.c:1592
#6 0x00000000012f0e4e in parse_events_parse (_parse_state=0x3ffffff7fb8,
scanner=0x16878c0) at util/parse-events.y:293
#7 0x00000000012695a0 in parse_events__scanner (str=0x3ffffff81d8
"temp_test_hwmon_event1", input=0x0, parse_state=0x3ffffff7fb8)
at util/parse-events.c:1867
#8 0x000000000126a1e8 in __parse_events (evlist=0x168b580,
str=0x3ffffff81d8 "temp_test_hwmon_event1", pmu_filter=0x0,
err=0x3ffffff81c8, fake_pmu=false, warn_if_reordered=true,
fake_tp=false) at util/parse-events.c:2136
#9 0x00000000011e36aa in parse_events (evlist=0x168b580,
str=0x3ffffff81d8 "temp_test_hwmon_event1", err=0x3ffffff81c8)
at /root/linux/tools/perf/util/parse-events.h:41
#10 0x00000000011e3e64 in do_test (i=0, with_pmu=false, with_alias=false)
at tests/hwmon_pmu.c:164
#11 0x00000000011e422c in test__hwmon_pmu (with_pmu=false)
at tests/hwmon_pmu.c:219
#12 0x00000000011e431c in test__hwmon_pmu_without_pmu (test=0x1610368
<suite.hwmon_pmu>, subtest=1) at tests/hwmon_pmu.c:23

where the attr::config is set to value 292470092988416 or 0x10a0000000000
in line 625 of file ./util/hwmon_pmu.c:

attr->config = key.type_and_num;

However member key::type_and_num is defined as union and bit field:

union hwmon_pmu_event_key {
long type_and_num;
struct {
int num :16;
enum hwmon_type type :8;
};
};

s390 is big endian and Intel is little endian architecture.
The events for the hwmon dummy pmu have num = 1 or num = 2 and
type is set to HWMON_TYPE_TEMP (which is 10).
On s390 this assignes member key::type_and_num the value of
0x10a0000000000 (which is 292470092988416) as shown in above
trace output.

Fix this and export the structure/union hwmon_pmu_event_key
so the test shares the same implementation as the event parsing
functions for union and bit fields. This should avoid
endianess issues on all platforms.

Output after:
# ./perf test -F 11
11.1: Basic parsing test : Ok
11.2: Parsing without PMU name : Ok
11.3: Parsing with PMU name : Ok
#

Fixes: 531ee0fd4836 ("perf test: Add hwmon "PMU" test")
Cc: Ian Rogers <irogers@google.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
---
tools/perf/tests/hwmon_pmu.c | 16 +++++++++++-----
tools/perf/util/hwmon_pmu.c | 14 --------------
tools/perf/util/hwmon_pmu.h | 16 ++++++++++++++++
3 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/tools/perf/tests/hwmon_pmu.c b/tools/perf/tests/hwmon_pmu.c
index d2b066a2b557..0837aca1cdfa 100644
--- a/tools/perf/tests/hwmon_pmu.c
+++ b/tools/perf/tests/hwmon_pmu.c
@@ -13,17 +13,23 @@
static const struct test_event {
const char *name;
const char *alias;
- long config;
+ union hwmon_pmu_event_key key;
} test_events[] = {
{
"temp_test_hwmon_event1",
"temp1",
- 0xA0001,
+ .key = {
+ .num = 1,
+ .type = 10
+ },
},
{
"temp_test_hwmon_event2",
"temp2",
- 0xA0002,
+ .key = {
+ .num = 2,
+ .type = 10
+ },
},
};

@@ -183,11 +189,11 @@ static int do_test(size_t i, bool with_pmu, bool with_alias)
strcmp(evsel->pmu->name, "hwmon_a_test_hwmon_pmu"))
continue;

- if (evsel->core.attr.config != (u64)test_events[i].config) {
+ if (evsel->core.attr.config != (u64)test_events[i].key.type_and_num) {
pr_debug("FAILED %s:%d Unexpected config for '%s', %lld != %ld\n",
__FILE__, __LINE__, str,
evsel->core.attr.config,
- test_events[i].config);
+ test_events[i].key.type_and_num);
ret = TEST_FAIL;
goto out;
}
diff --git a/tools/perf/util/hwmon_pmu.c b/tools/perf/util/hwmon_pmu.c
index 4acb9bb19b84..acd889b2462f 100644
--- a/tools/perf/util/hwmon_pmu.c
+++ b/tools/perf/util/hwmon_pmu.c
@@ -107,20 +107,6 @@ struct hwmon_pmu {
int hwmon_dir_fd;
};

-/**
- * union hwmon_pmu_event_key: Key for hwmon_pmu->events as such each key
- * represents an event.
- *
- * Related hwmon files start <type><number> that this key represents.
- */
-union hwmon_pmu_event_key {
- long type_and_num;
- struct {
- int num :16;
- enum hwmon_type type :8;
- };
-};
-
/**
* struct hwmon_pmu_event_value: Value in hwmon_pmu->events.
*
diff --git a/tools/perf/util/hwmon_pmu.h b/tools/perf/util/hwmon_pmu.h
index 882566846df4..b3329774d2b2 100644
--- a/tools/perf/util/hwmon_pmu.h
+++ b/tools/perf/util/hwmon_pmu.h
@@ -91,6 +91,22 @@ enum hwmon_item {
HWMON_ITEM__MAX,
};

+/**
+ * union hwmon_pmu_event_key: Key for hwmon_pmu->events as such each key
+ * represents an event.
+ * union is exposed for testing to ensure problems are avoided on big
+ * endian machines.
+ *
+ * Related hwmon files start <type><number> that this key represents.
+ */
+union hwmon_pmu_event_key {
+ long type_and_num;
+ struct {
+ int num :16;
+ enum hwmon_type type :8;
+ };
+};
+
bool perf_pmu__is_hwmon(const struct perf_pmu *pmu);
bool evsel__is_hwmon(const struct evsel *evsel);

--
2.48.1