This will allow sessions with more than CORESIGHT_TRACE_IDS_MAX ETMs as long as there are fewer than that many ETMs connected to each sink.
Each sink owns its own trace ID map, and any Perf session connecting to that sink will allocate from it, even if the sink is currently in use by other users. This is similar to the existing behavior where the dynamic trace IDs are constant as long as there is any concurrent Perf session active. It's not completely optimal because slightly more IDs will be used than necessary, but the optimal solution involves tracking the PIDs of each session and allocating ID maps based on the session owner. This is difficult to do with the combination of per-thread and per-cpu modes and some scheduling issues. The complexity of this isn't likely to worth it because even with multiple users they'd just see a difference in the ordering of ID allocations rather than hitting any limits (unless the hardware does have too many ETMs connected to one sink).
Per-thread mode works but only until there are any overlapping IDs, at which point Perf will error out. Both per-thread mode and sysfs mode are left to future changes, but both can be added on top of this initial implementation and only sysfs mode requires further driver changes.
The HW_ID version field hasn't been bumped in order to not break Perf which already has an error condition for other values of that field. Instead a new minor version has been added which signifies that there are new fields but the old fields are backwards compatible.
Changes since v2:
* Rebase on coresight-next 6.10-rc2 (b9b25c8496). * Fix double free of csdev if device registration fails. * Fix leak of coresight_trace_id_perf_start() if trace ID allocation fails. * Don't resend HW_ID for sink changes in per-thread mode. The existing CPU field on AUX records can be used to track this instead. * Tidy function doc for coresight_trace_id_release_all() * Drop first two commits now that they are in coresight-next * Add a commit to make the trace ID spinlock local to the map
Changes since V1:
* Rename coresight_device.perf_id_map to perf_sink_id_map. * Instead of outputting a HW_ID for each reachable ETM, output the sink ID and continue to output only the HW_ID once for each mapping. * Keep the first two Perf patches so that it applies cleanly on coresight-next, although they have been applied on perf-tools-next * Add new *_map() functions to the trace ID public API instead of modifying existing ones. * Collapse "coresight: Pass trace ID map into source enable" into "coresight: Use per-sink trace ID maps for Perf sessions" because the first commit relied on the default map being accessible which is no longer necessary due to the previous bullet point.
James Clark (14): perf: cs-etm: Create decoders after both AUX and HW_ID search passes perf: cs-etm: Allocate queues for all CPUs perf: cs-etm: Move traceid_list to each queue perf: cs-etm: Create decoders based on the trace ID mappings perf: cs-etm: Support version 0.1 of HW_ID packets coresight: Remove unused ETM Perf stubs coresight: Clarify comments around the PID of the sink owner coresight: Move struct coresight_trace_id_map to common header coresight: Expose map arguments in trace ID API coresight: Make CPU id map a property of a trace ID map coresight: Use per-sink trace ID maps for Perf sessions coresight: Remove pending trace ID release mechanism coresight: Emit sink ID in the HW_ID packets coresight: Make trace ID map spinlock local to the map
drivers/hwtracing/coresight/coresight-core.c | 37 +- drivers/hwtracing/coresight/coresight-dummy.c | 3 +- .../hwtracing/coresight/coresight-etm-perf.c | 36 +- .../hwtracing/coresight/coresight-etm-perf.h | 18 - .../coresight/coresight-etm3x-core.c | 9 +- .../coresight/coresight-etm4x-core.c | 9 +- drivers/hwtracing/coresight/coresight-priv.h | 1 + drivers/hwtracing/coresight/coresight-stm.c | 3 +- drivers/hwtracing/coresight/coresight-sysfs.c | 3 +- .../hwtracing/coresight/coresight-tmc-etr.c | 5 +- drivers/hwtracing/coresight/coresight-tmc.h | 5 +- drivers/hwtracing/coresight/coresight-tpdm.c | 3 +- .../hwtracing/coresight/coresight-trace-id.c | 133 ++-- .../hwtracing/coresight/coresight-trace-id.h | 70 +- include/linux/coresight-pmu.h | 17 +- include/linux/coresight.h | 21 +- tools/include/linux/coresight-pmu.h | 17 +- .../perf/util/cs-etm-decoder/cs-etm-decoder.c | 28 +- tools/perf/util/cs-etm.c | 600 +++++++++++------- tools/perf/util/cs-etm.h | 2 +- 20 files changed, 614 insertions(+), 406 deletions(-)