coresight: Use per-sink trace ID maps for Perf sessions

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).

Signed-off-by: James Clark <james.clark@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20240722101202.26915-15-james.clark@linaro.org

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 7d62b88bfb5c..9c3067e2e38b 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -290,6 +290,7 @@ struct coresight_device {
 	bool sysfs_sink_activated;
 	struct dev_ext_attribute *ea;
 	struct coresight_device *def_sink;
+	struct coresight_trace_id_map perf_sink_id_map;
 	/* sysfs links between components */
 	int nr_links;
 	bool has_conns_grp;
@@ -384,7 +385,7 @@ struct coresight_ops_link {
 struct coresight_ops_source {
 	int (*cpu_id)(struct coresight_device *csdev);
 	int (*enable)(struct coresight_device *csdev, struct perf_event *event,
-		      enum cs_mode mode);
+		      enum cs_mode mode, struct coresight_trace_id_map *id_map);
 	void (*disable)(struct coresight_device *csdev,
 			struct perf_event *event);
 };