coresight: tmc: add the handle of the event to the path

[ Upstream commit aaa5abc ]

The handle is essential for retrieving the AUX_EVENT of each CPU and is
required in perf mode. It has been added to the coresight_path so that
dependent devices can access it from the path when needed.

The existing bug can be reproduced with:
perf record -e cs_etm//k -C 0-9 dd if=/dev/zero of=/dev/null

Showing an oops as follows:
Unable to handle kernel paging request at virtual address 000f6e84934ed19e

Call trace:
 tmc_etr_get_buffer+0x30/0x80 [coresight_tmc] (P)
 catu_enable_hw+0xbc/0x3d0 [coresight_catu]
 catu_enable+0x70/0xe0 [coresight_catu]
 coresight_enable_path+0xb0/0x258 [coresight]

Fixes: 080ee83 ("Coresight: Change functions to accept the coresight_path")
Signed-off-by: Carl Worth <carl@os.amperecomputing.com>
Reviewed-by: Leo Yan <leo.yan@arm.com>
Co-developed-by: Jie Gan <jie.gan@oss.qualcomm.com>
Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250925-fix_helper_data-v2-1-edd8a07c1646@oss.qualcomm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: cworth-ampere

drivers/hwtracing/coresight/coresight-etm-perf.c

@@ -520,6 +520,7 @@ static void etm_event_start(struct perf_event *event, int flags)
 		goto out;
 
 	path = etm_event_cpu_path(event_data, cpu);
+	path->handle = handle;
 	/* We need a sink, no need to continue without one */
 	sink = coresight_get_sink(path);
 	if (WARN_ON_ONCE(!sink))

drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -1334,7 +1334,8 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
 struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev,
 				   enum cs_mode mode, void *data)
 {
-	struct perf_output_handle *handle = data;
+	struct coresight_path *path = data;
+	struct perf_output_handle *handle = path->handle;
 	struct etr_perf_buffer *etr_perf;
 
 	switch (mode) {

include/linux/coresight.h

@@ -332,12 +332,14 @@ static struct coresight_dev_list (var) = {				\
 
 /**
  * struct coresight_path - data needed by enable/disable path
- * @path_list:              path from source to sink.
- * @trace_id:          trace_id of the whole path.
+ * @path_list:		path from source to sink.
+ * @trace_id:		trace_id of the whole path.
+ * @handle:		handle of the aux_event.
  */
 struct coresight_path {
-	struct list_head	path_list;
-	u8			trace_id;
+	struct list_head		path_list;
+	u8				trace_id;
+	struct perf_output_handle	*handle;
 };
 
 enum cs_mode {