[PATCH v3 05/12] perf evsel: Add a helper to get the value of a config field

James Clark
2025-12-12T15:32:52Z

This will be used by aux PMUs to read an already written value for
configuring their events and for also testing.

Its helper pmu_format_unpack() does the opposite of the existing
pmu_format_value() so rename that one to pmu_format_pack() so it's clear
how they are related.

Signed-off-by: James Clark <james.clark@linaro.org>
---
tools/perf/util/evsel.h | 2 ++
tools/perf/util/pmu.c | 77 ++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 68 insertions(+), 11 deletions(-)

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index a08130ff2e47a887b19f6c47bfa9f51e0c40d226..092904a61ec7afdc59253f9b78a9fe8b7cb5bfa7 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -575,6 +575,8 @@ void evsel__uniquify_counter(struct evsel *counter);
((((src) >> (pos)) & ((1ull << (size)) - 1)) << (63 - ((pos) + (size) - 1)))

u64 evsel__bitfield_swap_branch_flags(u64 value);
+int evsel__get_config_val(struct perf_pmu *pmu, struct evsel *evsel,
+ const char *config_name, u64 *val);
void evsel__set_config_if_unset(struct perf_pmu *pmu, struct evsel *evsel,
const char *config_name, u64 val);

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 514cba91f5d99b399d2d6a1e350971660c54a9fc..ef7358ad1fb955f29f2e68b3d0ce711754e4d67c 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -144,8 +144,8 @@ struct perf_pmu_format {
};

static int pmu_aliases_parse(struct perf_pmu *pmu);
-static void pmu_format_value(unsigned long *format, __u64 value, __u64 *v,
- bool zero);
+static void pmu_format_pack(unsigned long *format, __u64 value, __u64 *v,
+ bool zero);
static struct perf_pmu_format *pmu_find_format(const struct list_head *formats,
const char *name);

@@ -1377,6 +1377,61 @@ bool evsel__is_aux_event(const struct evsel *evsel)
return pmu && pmu->auxtrace;
}

+/*
+ * Unpacks a raw config[n] value using the sparse bitfield that defines a
+ * format attr. For example "config1:1,6-7,44" defines a 4 bit value across non
+ * contiguous bits and this function returns those 4 bits as a value.
+ */
+static u64 pmu_format_unpack(u64 format, u64 config_val)
+{
+ int val_bit = 0;
+ u64 res = 0;
+ int fmt_bit;
+
+ for_each_set_bit(fmt_bit, &format, PERF_PMU_FORMAT_BITS) {
+ if (test_bit(fmt_bit, &config_val))
+ res |= BIT_ULL(val_bit);
+
+ val_bit++;
+ }
+ return res;
+}
+
+int evsel__get_config_val(struct perf_pmu *pmu, struct evsel *evsel,
+ const char *config_name, u64 *val)
+{
+ struct perf_pmu_format *format = pmu_find_format(&pmu->format, config_name);
+ u64 bits = perf_pmu__format_bits(pmu, config_name);
+
+ if (!format || !bits) {
+ pr_err("Unknown/empty format name: %s\n", config_name);
+ *val = 0;
+ return -EINVAL;
+ }
+
+ switch (format->value) {
+ case PERF_PMU_FORMAT_VALUE_CONFIG:
+ *val = pmu_format_unpack(bits, evsel->core.attr.config);
+ return 0;
+ case PERF_PMU_FORMAT_VALUE_CONFIG1:
+ *val = pmu_format_unpack(bits, evsel->core.attr.config1);
+ return 0;
+ case PERF_PMU_FORMAT_VALUE_CONFIG2:
+ *val = pmu_format_unpack(bits, evsel->core.attr.config2);
+ return 0;
+ case PERF_PMU_FORMAT_VALUE_CONFIG3:
+ *val = pmu_format_unpack(bits, evsel->core.attr.config3);
+ return 0;
+ case PERF_PMU_FORMAT_VALUE_CONFIG4:
+ *val = pmu_format_unpack(bits, evsel->core.attr.config4);
+ return 0;
+ default:
+ pr_err("Unknown format value: %d\n", format->value);
+ *val = 0;
+ return -EINVAL;
+ }
+}
+
/*
* Set @config_name to @val as long as the user hasn't already set or cleared it
* by passing a config term on the command line.
@@ -1432,7 +1487,7 @@ void evsel__set_config_if_unset(struct perf_pmu *pmu, struct evsel *evsel,
return;

/* Otherwise replace it */
- pmu_format_value(&bits, val, vp, /*zero=*/true);
+ pmu_format_pack(&bits, val, vp, /*zero=*/true);
}

static struct perf_pmu_format *
@@ -1477,8 +1532,8 @@ int perf_pmu__format_type(struct perf_pmu *pmu, const char *name)
* Sets value based on the format definition (format parameter)
* and unformatted value (value parameter).
*/
-static void pmu_format_value(unsigned long *format, __u64 value, __u64 *v,
- bool zero)
+static void pmu_format_pack(unsigned long *format, __u64 value, __u64 *v,
+ bool zero)
{
unsigned long fbit, vbit;

@@ -1595,23 +1650,23 @@ static int pmu_config_term(const struct perf_pmu *pmu,
switch (term->type_term) {
case PARSE_EVENTS__TERM_TYPE_CONFIG:
assert(term->type_val == PARSE_EVENTS__TERM_TYPE_NUM);
- pmu_format_value(bits, term->val.num, &attr->config, zero);
+ pmu_format_pack(bits, term->val.num, &attr->config, zero);
break;
case PARSE_EVENTS__TERM_TYPE_CONFIG1:
assert(term->type_val == PARSE_EVENTS__TERM_TYPE_NUM);
- pmu_format_value(bits, term->val.num, &attr->config1, zero);
+ pmu_format_pack(bits, term->val.num, &attr->config1, zero);
break;
case PARSE_EVENTS__TERM_TYPE_CONFIG2:
assert(term->type_val == PARSE_EVENTS__TERM_TYPE_NUM);
- pmu_format_value(bits, term->val.num, &attr->config2, zero);
+ pmu_format_pack(bits, term->val.num, &attr->config2, zero);
break;
case PARSE_EVENTS__TERM_TYPE_CONFIG3:
assert(term->type_val == PARSE_EVENTS__TERM_TYPE_NUM);
- pmu_format_value(bits, term->val.num, &attr->config3, zero);
+ pmu_format_pack(bits, term->val.num, &attr->config3, zero);
break;
case PARSE_EVENTS__TERM_TYPE_CONFIG4:
assert(term->type_val == PARSE_EVENTS__TERM_TYPE_NUM);
- pmu_format_value(bits, term->val.num, &attr->config4, zero);
+ pmu_format_pack(bits, term->val.num, &attr->config4, zero);
break;
case PARSE_EVENTS__TERM_TYPE_LEGACY_HARDWARE_CONFIG:
assert(term->type_val == PARSE_EVENTS__TERM_TYPE_NUM);
@@ -1749,7 +1804,7 @@ static int pmu_config_term(const struct perf_pmu *pmu,
*/
}

- pmu_format_value(format->bits, val, vp, zero);
+ pmu_format_pack(format->bits, val, vp, zero);
return 0;
}

--
2.34.1