[PATCH v3 00/12] perf cs-etm/arm-spe: Remove hard coded config fields

James Clark
2025-12-12T15:32:40Z

The specific config field that an event format attribute is in is
consistently hard coded, even though the API is supposed to be that the
driver publishes the config field name. To stop this pattern from being
copy pasted and causing problems in the future, replace them all with
calls to a new helper that returns the value that a user set.

This reveals some issues in evsel__set_config_if_unset(). It doesn't
work with sparse bitfields, which are an unused but documented feature.
And it also only writes to the attr.config field. To fix it we need to
start tracking user changes for all config fields and then use existing
helper functions that support sparse bitfields. Some other refactoring
was also required and a test was added.

Signed-off-by: James Clark <james.clark@linaro.org>
---
Changes in v3:
- Fix uninitialized variable warning on GCC
- Fix leak of evlist in test
- Confirm no type punning issues with ubsan (Ian)
- Link to v2: https://lore.kernel.org/r/20251208-james-perf-config-bits-v2-0-4ac0281993b0@linaro.org

Changes in v2:
- Remove macros in get_config_chgs() and some other refactoring.
- Support sparse bitfields in evsel__set_config_if_unset().
- Always track user changes instead of only when
'pmu->perf_event_attr_init_default' is set.
- Add a test.
- Don't bail out in cs-etm.c if any format fields are missing (Leo).
- Rename 'guess' to 'synth' (Mike).
- Link to v1: https://lore.kernel.org/r/20251201-james-perf-config-bits-v1-0-22ecbbf8007c@linaro.org

---
James Clark (12):
perf parse-events: Refactor get_config_terms() to remove macros
perf evsel: Support sparse fields in evsel__set_config_if_unset()
perf parse-events: Track all user changed config bits
perf evsel: apply evsel__set_config_if_unset() to all config fields
perf evsel: Add a helper to get the value of a config field
perf parse-events: Always track user config changes
perf tests: Test evsel__set_config_if_unset() and config change tracking
perf cs-etm: Make a helper to find the Coresight evsel
perf cs-etm: Don't use hard coded config bits when setting up ETMCR
perf cs-etm: Don't use hard coded config bits when setting up TRCCONFIGR
perf cs-etm: Don't hard code config attribute when configuring the event
perf arm-spe: Don't hard code config attribute

tools/perf/arch/arm/util/cs-etm.c | 193 +++++++++++++++------------
tools/perf/arch/arm64/util/arm-spe.c | 15 ++-
tools/perf/tests/pmu.c | 91 +++++++++++++
tools/perf/util/evsel.c | 6 +-
tools/perf/util/evsel.h | 2 +
tools/perf/util/evsel_config.h | 7 +-
tools/perf/util/parse-events.c | 248 ++++++++++++++++++++---------------
tools/perf/util/pmu.c | 112 ++++++++++++++--
8 files changed, 460 insertions(+), 214 deletions(-)
---
base-commit: 2eeb09fe1c5173b659929f92fee4461796ca8c14
change-id: 20251112-james-perf-config-bits-bee7106f0f00

Best regards,
--
James Clark <james.clark@linaro.org>