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.
--- Changes in v5: - Use bitfields wherever possible instead of converting to a u64. This is more consistent with the existing format helper functions and fixes a build error on i386 where unsigned long is 32 bits. - Link to v4: https://lore.kernel.org/r/20251222-james-perf-config-bits-v4-0-0608438186fc@...
Changes in v4: - Constify some function args (Ian) - Move some evsel__* functions to evsel.c and make some pmu.c functions public to support this (Ian) - Drop pmu arg where it can be fetched from evsel->pmu (Ian) - Link to v3: https://lore.kernel.org/r/20251212-james-perf-config-bits-v3-0-aa36a4846776@...
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@...
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@...
--- James Clark (14): perf parse-events: Refactor get_config_terms() to remove macros perf evsel: Refactor evsel__set_config_if_unset() arguments perf evsel: Move evsel__* functions to evsel.c 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 | 201 +++++++++++++++------------- tools/perf/arch/arm64/util/arm-spe.c | 17 +-- tools/perf/arch/x86/util/intel-pt.c | 3 +- tools/perf/tests/pmu.c | 91 +++++++++++++ tools/perf/util/evsel.c | 120 ++++++++++++++++- tools/perf/util/evsel.h | 6 +- tools/perf/util/evsel_config.h | 7 +- tools/perf/util/parse-events.c | 248 ++++++++++++++++++++--------------- tools/perf/util/pmu.c | 95 ++++---------- tools/perf/util/pmu.h | 34 ++++- 10 files changed, 537 insertions(+), 285 deletions(-) --- base-commit: 54a23bff770961e024e2c61cd1f46888190c3e79 change-id: 20251112-james-perf-config-bits-bee7106f0f00
Best regards,