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

Ian Rogers
2025-02-01T07:00:42Z

On Fri, Jan 31, 2025 at 3:24 AM Thomas Richter <tmricht@linux.ibm.com> wrote:
>
> 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>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks!
Ian

> ---
> 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
>